Sample records for adjusted bearing contact
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Design and Stress Analysis of Low-Noise Adjusted Bearing Contact Spiral Bevel Gears
NASA Technical Reports Server (NTRS)
Litvin, Faydor L.; Fuentes, Alfonso; Mullins, Baxter R.; Woods, Ron
2002-01-01
An integrated computerized approach for design and stress analysis of low-noise spiral bevel gear drives with adjusted bearing contact has been developed. The computation procedure is an iterative process, requiring four separate steps that provide: (a) a parabolic function of transmission errors that is able to reduce the effect of errors of alignment, and (b) reduction of the shift of bearing contact caused by misalignment. Application of finite element analysis permits the contact and bending stresses to be determined and investigate the formation of the bearing contact. The design of finite element models and boundary conditions is automated and does not require an intermediate CAD computer program. A commercially available finite element analysis computer program with contact capability was used to conduct the stress analysis. The theory developed is illustrated with numerical examples.
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Design and Stress Analysis of Low-Noise Adjusted Bearing Contact Spiral Bevel Gears
NASA Technical Reports Server (NTRS)
Fuentes, A.; Litvin, F. L.; Mullins, B. R.; Woods, R.; Handschuh, R. F.; Lewicki, David G.
2002-01-01
An integrated computerized approach for design and stress analysis of low-noise spiral bevel gear drives with adjusted bearing contact is proposed. The procedure of computations is an iterative process that requires four separate procedures and provide: (a) a parabolic function of transmission errors that is able to reduce the effect of errors of alignment on noise and vibration, and (b) reduction of the shift of bearing contact caused by misalignment. Application of finite element analysis enables us to determine the contact and bending stresses and investigate the formation of the bearing contact. The design of finite element models and boundary conditions is automated and does not require intermediate CAD computer programs for application of general purpose computer program for finite element analysis.
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Self-adjusting magnetic bearing systems
Post, Richard F.
1998-01-01
A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described.
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Self-adjusting magnetic bearing systems
Post, R.F.
1998-07-21
A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described. 7 figs.
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Non-contacting "snubber bearing" for passive magnetic bearing systems
Post, Richard F
2017-08-22
A new non-contacting magnetic "snubber" bearing is provided for application to rotating systems such as vehicular electromechanical battery systems subject to frequent accelerations. The design is such that in the equilibrium position the drag force of the snubber is very small (milliwatts). However in a typical case, if the rotor is displaced by as little as 2 millimeters a large restoring force is generated without any physical contact between the stationary and rotating parts of the snubber bearing.
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NASA Technical Reports Server (NTRS)
Litvin, Faydor L.; Tsay, Chung-Biau
1987-01-01
The authors have proposed a method for the generation of circular arc helical gears which is based on the application of standard equipment, worked out all aspects of the geometry of the gears, proposed methods for the computer aided simulation of conditions of meshing and bearing contact, investigated the influence of manufacturing and assembly errors, and proposed methods for the adjustment of gears to these errors. The results of computer aided solutions are illustrated with computer graphics.
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Ball bearing lubrication: The elastohydrodynamics of elliptical contacts
NASA Technical Reports Server (NTRS)
Hamrock, B. J.; Dowson, D.
1981-01-01
The history of ball bearings is examined, taking into account rollers and the wheel in the early civilizations, the development of early forms of rolling-element bearings in the classical civilizations, the Middle Ages, the Industrial Revolution, the emergence of the precision ball bearing, scientific studies of contact mechanics and rolling friction, and the past fifty years. An introduction to ball bearings is presented, and aspects of ball bearing mechanics are explored. Basic characteristics of lubrication are considered along with lubrication equations, the lubrication of rigid ellipsoidal solids, and elastohydrodynamic lubrication theory. Attention is given to the theoretical results for fully flooded elliptical hydrodynamic contacts, the theoretical results for starved elliptical contacts, experimental investigations, the elastohydrodynamics of elliptical contacts for materials of low elastic modulus, the film thickness for different regimes of fluid-film lubrication, and applications.
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Effects of bolt-hole contact on bearing-bypass damage-onset strength
NASA Technical Reports Server (NTRS)
Crews, John H., Jr.; Naik, Rajiv A.
1991-01-01
A combined experimental and analytical study was conducted to investigate the effects of bolt-hole contact on the bearing bypass strength of a graphite-epoxy laminate. Tests were conducted on specimens consisting of 16-ply quasi-isotropic T300/5208 laminates with a centrally located hole. Bearing loads were applied through a clearance-fit steel bolt. Damage onset strength and damage mode were determined for each test case. A finite element procedure was used to calculate the bolt-hole stresses and bolt contact for each test case. A finite element procedure was used to calculate the bolt-hole stresses and bolt contact for each measured damage-onset strength. For the tension bearing-bypass cases tested, the bolt contact half-angle was approximately 60 degrees at damage onset. For compression, the contact angle was 20 degrees as the bypass load increased. A corresponding decrease in the bearing damage onset strength was attributed to the decrease in contact angle which made the bearing loads more severe. Hole boundary stresses were also computed by superimposing stresses for separate bearing and bypass loading. Stresses at the specimen net section were accurately approximated by the superposition procedure. However, the peak bearing stresses had large errors because the bolt contact angles were not represented correctly. For compression, peak bearing stress errors of nearly 50 percent were calculated.
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NASA Astrophysics Data System (ADS)
Nonato, Fábio; Cavalca, Katia L.
2014-12-01
This work presents a methodology for including the Elastohydrodynamic (EHD) film effects to a lateral vibration model of a deep groove ball bearing by using a novel approximation for the EHD contacts by a set of equivalent nonlinear spring and viscous damper. The fitting of the equivalent contact model used the results of a transient multi-level finite difference EHD algorithm to adjust the dynamic parameters. The comparison between the approximated model and the finite difference simulated results showed a suitable representation of the stationary and dynamic contact behaviors. The linear damping hypothesis could be shown as a rough representation of the actual hysteretic behavior of the EHD contact. Nevertheless, the overall accuracy of the model was not impaired by the use of such approximation. Further on, the inclusion of the equivalent EHD contact model is equated for both the restoring and the dissipative components of the bearing's lateral dynamics. The derived model was used to investigate the effects of the rolling element bearing lubrication on the vibration response of a rotor's lumped parameter model. The fluid film stiffening effect, previously only observable by experimentation, could be quantified using the proposed model, as well as the portion of the bearing damping provided by the EHD fluid film. Results from a laboratory rotor-bearing test rig were used to indirectly validate the proposed contact approximation. A finite element model of the rotor accounting for the lubricated bearing formulation adequately portrayed the frequency content of the bearing orbits observed on the test rig.
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Design and Operating Characteristics of High-Speed, Small-Bore, Angular-Contact Ball Bearings
NASA Technical Reports Server (NTRS)
Pinel, Stanley I.; Signer, Hans R.; Zaretsky, Erwin V.
1998-01-01
The computer program SHABERTH was used to analyze 35-mm-bore, angular-contact ball bearings designed and manufactured for high-speed turbomachinery applications. Parametric tests of the bearings were conducted on a high-speed, high-temperature bearing tester and were compared with the computer predictions. Four bearing and cage designs were studied. The bearings were lubricated either by jet lubrication or through the split inner ring with and without outer-ring cooling. The predicted bearing life decreased with increasing speed because of increased operating contact stresses caused by changes in contact angle and centrifugal load. For thrust loads only, the difference in calculated life for the 24 deg. and 30 deg. contact-angle bearings was insignificant. However, for combined loading, the 24 deg. contact-angle bearing gave longer life. For split-inner-ring bearings, optimal operating conditions were obtained with a 24 deg. contact angle and an inner-ring, land-guided cage, using outer-ring cooling in conjunction with low lubricant flow rates. Lower temperature and power losses were obtained with a single-outer-ring, land-guided cage for the 24 deg. contact-angle bearing having a relieved inner ring and partially relieved outer ring. Inner-ring temperatures were independent of lubrication mode and cage design. In comparison with measured values, reasonably good engineering correlation was obtained using the computer program SHABERTH for predicted bearing power loss and for inner- and outer-ring temperatures. The Parker formula for XCAV (used in SHABERTH, a measure of oil volume in the bearing cavity) may need to be refined to reflect bearing lubrication mode, cage design, and location of cage-controlling land.
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Tool Indicates Contact Angles In Bearing Raceways
NASA Technical Reports Server (NTRS)
Akian, Richard A.; Butner, Myles F.
1995-01-01
Tool devised for use in measuring contact angles between balls and races in previously operated ball bearings. Used on both inner and outer raceways of bearings having cross-sectional widths between approximately 0.5 and 2.0 in. Consists of integral protractor mounted in vertical plane on bracket equipped with leveling screws and circular level indicator. Protractor includes rotatable indicator needle and set of disks of various sizes to fit various raceway curvatures.
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Wang, F C; Jin, Z M; McEwen, H M J; Fisher, J
2003-01-01
The effect of the roughness and topography of ultrahigh molecular weight polyethylene (UHMWPE) bearing surfaces on the microscopic contact mechanics with a metallic counterface was investigated in the present study. Both simple sinusoidal roughness forms, with a wide range of amplitudes and wavelengths, and real surface topographies, measured before and after wear testing in a simple pin-on-plate machine, were considered in the theoretical analysis. The finite difference method was used to solve the microscopic contact between the rough UHMWPE bearing surface and a smooth hard counterface. The fast Fourier transform (FFT) was used to cope with the large number of mesh points required to represent the surface topography of the UHMWPE bearing surface. It was found that only isolated asperity contacts occurred under physiological loading, and the real contact area was only a small fraction of the nominal contact area. Consequently, the average contact pressure experienced at the articulating surfaces was significantly higher than the nominal contact pressure. Furthermore, it was shown that the majority of asperities on the worn UHMWPE pin were deformed in the elastic region, and consideration of the plastic deformation only resulted in a negligible increase in the predicted asperity contact area. Microscopic asperity contact and deformation mechanisms may play an important role in the understanding of the wear mechanisms of UHMWPE bearing surfaces.
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Sliding Contact Bearings for Service to 700 C
NASA Technical Reports Server (NTRS)
Sliney, Harold E.
1996-01-01
Cylindrical, sliding contact bearings made entirely of a self-lubricating powder metallurgy composite (PM212) or of super alloy shells lined with clad PM212 were tested in an oscillating mode at temperatures from 25 to 700 C. Tests of 100 hr duration or longer were conducted at a bearing unit load of 3.45 Mpa (500 psi). Shorter duration tests at various unit loads up to 24.1 Mpa (3500 psi) were also conducted. In comparison tests, bearings lubricated with PM212 had superior anti-wear characteristics compared to the baseline, unlubricated, super alloy bearings: no galling of PM212-lubricated bearings occurred, while severe surface damage including galling occurred, especially at high loads, during the baseline tests. A heat treatment procedure, which dimensionally stabilizes PM212 and thereby minimizes clearance changes during high temperature bearing operation, is described.
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Nonlinear dynamic modeling of rotor system supported by angular contact ball bearings
NASA Astrophysics Data System (ADS)
Wang, Hong; Han, Qinkai; Zhou, Daning
2017-02-01
In current bearing dynamic models, the displacement coordinate relations are usually utilized to approximately obtain the contact deformations between the rolling element and raceways, and then the nonlinear restoring forces of the rolling bearing could be calculated accordingly. Although the calculation efficiency is relatively higher, the accuracy is lower as the contact deformations should be solved through iterative analysis. Thus, an improved nonlinear dynamic model is presented in this paper. Considering the preload condition, surface waviness, Hertz contact and elastohydrodynamic lubrication, load distribution analysis is solved iteratively to more accurately obtain the contact deformations and angles between the rolling balls and raceways. The bearing restoring forces are then obtained through iteratively solving the load distribution equations at every time step. Dynamic tests upon a typical rotor system supported by two angular contact ball bearings are conducted to verify the model. Through comparisons, the differences between the nonlinear dynamic model and current models are also pointed out. The effects of axial preload, rotor eccentricity and inner/outer waviness amplitudes on the dynamic response are discussed in detail.
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Finite element analysis of thrust angle contact ball slewing bearing
NASA Astrophysics Data System (ADS)
Deng, Biao; Guo, Yuan; Zhang, An; Tang, Shengjin
2017-12-01
In view of the large heavy slewing bearing no longer follows the rigid ring hupothesis under the load condition, the entity finite element model of thrust angular contact ball bearing was established by using finite element analysis software ANSYS. The boundary conditions of the model were set according to the actual condition of slewing bearing, the internal stress state of the slewing bearing was obtained by solving and calculation, and the calculated results were compared with the numerical results based on the rigid ring assumption. The results show that more balls are loaded in the result of finite element method, and the maximum contact stresses between the ball and raceway have some reductions. This is because the finite element method considers the ferrule as an elastic body. The ring will produce structure deformation in the radial plane when the heavy load slewing bearings are subjected to external loads. The results of the finite element method are more in line with the actual situation of the slewing bearing in the engineering.
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van Stralen, R A; Heesterbeek, P J C; Wymenga, A B
2015-11-01
In anteroposterior (AP)-gliding mobile-bearing total knee arthroplasty (TKA), the femoral component can theoretically slide forward resulting in a more anterior contact point, causing pain due to impingement. A lower lever arm of the extensor apparatus can also attribute to higher patella pressures and pain. The goal of this study was to determine the contact point in a cohort of mobile- and fixed-bearing TKAs, to determine whether the contact point lies more anteriorly in mobile-bearing TKA and to confirm whether this results in anterior knee pain. We used 38 fixed-bearing TKA and 40 mobile-bearing TKA from a randomized trial with straight lateral knee X-rays and measured the contact point. The functional outcome was measured by Knee Society Score at 12 months postoperatively. Pain scores were analysed using a VAS score (0-100 mm) in all patients at rest and when moving. Difficulty at rising up out of a chair was also assessed using a VAS score. The contact point in mobile-bearing TKA was situated at 59.5 % of the AP distance of the tibia and in the fixed-bearing TKA group at 66.1 % (P< 0.05). Patients with mobile- and fixed-bearing TKAs had similar knee scores, pain scores and difficulty in chair rise. No significant correlation was found between contact point and knee pain. The hypothesis of a more anterior contact point in the mobile-bearing cohort was confirmed but no correlation with functional and pain scores in this cohort could be found. The tibiofemoral contact point could not be correlated with a different clinical outcome and higher incidence of anterior knee pain. This study further adds to the knowledge on possible differences between mobile- and fixed-bearing prostheses. Next to that, bad outcomes could not be explained by CP. Case series, Level IV.
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Ball to separator contact forces in angular contact ball bearings under thrust and radial loads
NASA Technical Reports Server (NTRS)
Nypan, L. J.
1978-01-01
Experimental data are reported on ball to cage contact forces in a 110 mm bore ball bearing operating at speeds to 12,000 rpm under radial and thrust loads. Information is also reported on cage to inner race land contact force, cage to inner race land clearance, and cage to shaft speed ratios.
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Ball to separator contact forces in angular contact ball bearings under thrust and radial loads
NASA Technical Reports Server (NTRS)
Nypan, L. J.
1977-01-01
Experimental data is reported on ball to cage contact forces in a 110 mm bore ball bearing operating at speeds to 12000 rpm under radial and thrust loads. Information is also reported on cage to inner race land contact force, cage to inner race land clearance, and cage to shaft speed ratios.
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Estimation of bearing contact angle in-situ by X-ray kinematography
NASA Technical Reports Server (NTRS)
Fowler, P. H.; Manders, F.
1982-01-01
The mounted, preloaded contact angle of the structural bearings in the assembled design mechanical assembly was measured. A modification of the Turns method is presented, based upon the clarity and definition of moving parts achieved with X-ray technique and cinematic display. Contact angle is estimated by counting the number of bearings passing a given point as a function of number of turns of the shaft. Ball and pitch diameter variations are discussed. Ball train and shaft angle uncertainties are also discussed.
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Contact angle adjustment in equation-of-state-based pseudopotential model
NASA Astrophysics Data System (ADS)
Hu, Anjie; Li, Longjian; Uddin, Rizwan; Liu, Dong
2016-05-01
The single component pseudopotential lattice Boltzmann model has been widely applied in multiphase simulation due to its simplicity and stability. In many studies, it has been claimed that this model can be stable for density ratios larger than 1000. However, the application of the model is still limited to small density ratios when the contact angle is considered. The reason is that the original contact angle adjustment method influences the stability of the model. Moreover, simulation results in the present work show that, by applying the original contact angle adjustment method, the density distribution near the wall is artificially changed, and the contact angle is dependent on the surface tension. Hence, it is very inconvenient to apply this method with a fixed contact angle, and the accuracy of the model cannot be guaranteed. To solve these problems, a contact angle adjustment method based on the geometry analysis is proposed and numerically compared with the original method. Simulation results show that, with our contact angle adjustment method, the stability of the model is highly improved when the density ratio is relatively large, and it is independent of the surface tension.
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Contact angle adjustment in equation-of-state-based pseudopotential model.
Hu, Anjie; Li, Longjian; Uddin, Rizwan; Liu, Dong
2016-05-01
The single component pseudopotential lattice Boltzmann model has been widely applied in multiphase simulation due to its simplicity and stability. In many studies, it has been claimed that this model can be stable for density ratios larger than 1000. However, the application of the model is still limited to small density ratios when the contact angle is considered. The reason is that the original contact angle adjustment method influences the stability of the model. Moreover, simulation results in the present work show that, by applying the original contact angle adjustment method, the density distribution near the wall is artificially changed, and the contact angle is dependent on the surface tension. Hence, it is very inconvenient to apply this method with a fixed contact angle, and the accuracy of the model cannot be guaranteed. To solve these problems, a contact angle adjustment method based on the geometry analysis is proposed and numerically compared with the original method. Simulation results show that, with our contact angle adjustment method, the stability of the model is highly improved when the density ratio is relatively large, and it is independent of the surface tension.
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Angular-contact ball-bearing internal load estimation algorithm using runtime adaptive relaxation
NASA Astrophysics Data System (ADS)
Medina, H.; Mutu, R.
2017-07-01
An algorithm to estimate internal loads for single-row angular contact ball bearings due to externally applied thrust loads and high-operating speeds is presented. A new runtime adaptive relaxation procedure and blending function is proposed which ensures algorithm stability whilst also reducing the number of iterations needed to reach convergence, leading to an average reduction in computation time in excess of approximately 80%. The model is validated based on a 218 angular contact bearing and shows excellent agreement compared to published results.
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NASA Astrophysics Data System (ADS)
Zhang, Jinhua; Fang, Bin; Hong, Jun; Wan, Shaoke; Zhu, Yongsheng
2017-12-01
The combined angular contact ball bearings are widely used in automatic, aerospace and machine tools, but few researches on the combined angular contact ball bearings have been reported. It is shown that the preload and stiffness of combined bearings are mutual influenced rather than simply the superposition of multiple single bearing, therefore the characteristic calculation of combined bearings achieved by coupling the load and deformation analysis of a single bearing. In this paper, based on the Jones quasi-static model and stiffness analytical model, a new iterative algorithm and model are proposed for the calculation of combined bearings preload and stiffness, and the dynamic effects include centrifugal force and gyroscopic moment have to be considered. It is demonstrated that the new method has general applicability, the preload factors of combined bearings are calculated according to the different design preloads, and the static and dynamic stiffness for various arrangements of combined bearings are comparatively studied and analyzed, and the influences of the design preload magnitude, axial load and rotating speed are discussed in detail. Besides, the change rule of dynamic contact angles of combined bearings with respect to the rotating speed is also discussed. The results show that bearing arrangement modes, rotating speed and design preload magnitude have a significant influence on the preload and stiffness of combined bearings. The proposed formulation provides a useful tool in dynamic analysis of the complex bearing-rotor system.
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Analysis of rolling contact spall life in 440 C steel bearing rims
NASA Technical Reports Server (NTRS)
Bastias, P. C.; Bhargava, V.; Bower, A. P.; Du, J.; Gupta, V.; Hahn, G. T.; Kulkarni, S. M.; Kumar, A. M.; Leng, X.; Rubin, C. A.
1991-01-01
The results of a two year study of the mechanisms of spall failure in the HPOTP bearings are described. The objective was to build a foundation for detailed analyses of the contact life in terms of: cyclic plasticity, contact mechanics, spall nucleation, and spall growth. Since the laboratory rolling contact testing is carried out in the 3 ball/rod contact fatigue testing machine, the analysis of the contacts and contact lives produced in this machine received attention. The results from the experimentally observed growth lives are compared with calculated predictions derived from the fracture mechanics calculations.
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-10-24
... Regulations To Prohibit Public Contact With Big Cats, Bears, and Nonhuman Primates AGENCY: Animal and Plant... into direct or physical contact with big cats, bears, or nonhuman primates of any age, to define the... coming. FOR FURTHER INFORMATION CONTACT: Dr. Barbara Kohn, DVM, Senior Staff Officer, USDA, APHIS, Animal...
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The properties of thin-section, four-point-contact ball bearings in space
NASA Technical Reports Server (NTRS)
Rowntree, R. A.
1985-01-01
Thin section, four-point-contact ball bearings are increasinly employed in spacecraft mechanisms because of the potential advantages they offer. However, litte was previously known of their torque, thermal conductance and stiffness properties at conditions anticipated for their use in space. An investigation of these properties are described. It was found that frictional (Coulomb) torque, thermal conductance and stiffness all show marked dependence on the bearing preload, the housing design, the bearing external fit (i.e., free fit or interference) and on the thermal gradient across the races. Optimum bearing performance is achieved only if these properties are well understood. The necessary data to understand these properties are provided.
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Oh, Won Seok; Lee, Yong Seuk; Kim, Byung Kak; Sim, Jae Ang; Lee, Beom Koo
2016-06-01
To analyze the contact mechanics of the femoral component and polyethylene of the Low Contact Stress rotating platform (LCS-RP) in nonweight bearing and weight bearing conditions using full flexion lateral radiographs. From May 2009 to December 2013, 58 knees in 41 patients diagnosed with osteoarthritis and treated with total knee arthroplasty (TKA) were included in this study. TKA was performed using an LCS-RP knee prosthesis. Full flexion lateral radiographs in both weight bearing and nonweight bearing condition were taken at least one month postoperatively (average, 28.8 months). Translation of femoral component was determined by the contact point between the femoral component and polyethylene. Maximum flexion was measured as the angle between the lines drawn at the midpoint of the femur and tibia. Posterior shift of the contact point in LCS-RP TKA was observed under weight bearing condition, which resulted in deeper flexion compared to LCS-RP TKA under nonweight bearing condition. In the LCS-RP TKA, the contact point between the femoral component and polyethylene moved posteriorly under weight bearing condition, and the joint was more congruent and maximum flexion increased with weight bearing.
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Measurement of separator contact forces in ball bearings using a derotation prism
NASA Technical Reports Server (NTRS)
Nypan, L. J.
1978-01-01
A derotation prism was used to produce a stationary image of balls deflecting a portion of the separator. Ball to cage contact forces in a 110 mm bearing at speeds to 12,000 rpm were found to be 25 N (five lb) maximum. Inner race land contact force was found to vary up to 20 N (four lb).
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Assessment of the Applicability of Hertzian Contact Theory to Edge-Loaded Prosthetic Hip Bearings
Sanders, Anthony P.; Brannon, Rebecca M.
2011-01-01
The components of prosthetic hip bearings may experience in-vivo subluxation and edge loading on the acetabular socket as a result of joint laxity, causing abnormally high, damaging contact stresses. In this research, edge-loaded contact of prosthetic hips is examined analytically and experimentally in the most commonly used categories of material pairs. In edge-loaded ceramic-on-ceramic hips, Hertzian contact theory yields accurate (conservatively, <10% error) predictions of the contact dimensions. Moreover, Hertzian theory successfully captures slope and curvature trends in the dependence of contact patch geometry on the applied load. In an edge-loaded ceramic-on-metal pair, a similar degree of accuracy is observed in the contact patch length; however, the contact width is less accurately predicted due to the onset of subsurface plasticity, which is predicted for loads >400 N. Hertzian contact theory is shown to be ill-suited to edge-loaded ceramic-on-polyethylene pairs due to polyethylene’s nonlinear material behavior. This work elucidates the methods and the accuracy of applying classical contact theory to edge-loaded hip bearings. The results help to define the applicability of Hertzian theory to the design of new components and materials to better resist severe edge loading contact stresses. PMID:21962465
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Quantifying oil filtration effects on bearing life
NASA Technical Reports Server (NTRS)
Needelman, William M.; Zaretsky, Erwin V.
1991-01-01
Rolling-element bearing life is influenced by the number, size, and material properties of particles entering the Hertzian contact of the rolling element and raceway. In general, rolling-element bearing life increases with increasing level of oil filtration. Based upon test results, two equations are presented which allow for the adjustment of bearing L(sub 10) or catalog life based upon oil filter rating. It is recommended that where no oil filtration is used catalog life be reduced by 50 percent.
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Martinelli, Nicolo; Baretta, Silvia; Pagano, Jenny; Bianchi, Alberto; Villa, Tomaso; Casaroli, Gloria; Galbusera, Fabio
2017-11-25
Mobile-bearing ankle implants with good clinical results continued to increase the popularity of total ankle arthroplasty to address endstage ankle osteoarthritis preserving joint movement. Alternative solutions used fixed-bearing designs, which increase stability and reduce the risk of bearing dislocation, but with a theoretical increase of contact stresses leading to a higher polyethylene wear. The purpose of this study was to investigate the contact stresses, pressure and area in the polyethylene component of a new total ankle replacement with a fixed-bearing design, using 3D finite element analysis. A three-dimensional finite element model of the Zimmer Trabecular Metal Total Ankle was developed and assembled based on computed tomography images. Three different sizes of the polyethylene insert were modeled, and a finite element analysis was conducted to investigate the contact pressure, the von Mises stresses and the contact area of the polyethylene component during the stance phase of the gait cycle. The peak value of pressure was found in the anterior region of the articulating surface, where it reached 19.8 MPa at 40% of the gait cycle. The average contact pressure during the stance phase was 6.9 MPa. The maximum von Mises stress of 14.1 MPa was reached at 40% of the gait cycle in the anterior section. In the central section, the maximum von Mises stress of 10.8 MPa was reached at 37% of the gait cycle, whereas in the posterior section the maximum stress of 5.4 MPa was reached at the end of the stance phase. The new fixed-bearing total ankle replacement showed a safe mechanical behavior and many clinical advantages. However, advanced models to quantitatively estimate the wear are need. To the light of the clinical advantages, we conclude that the presented prosthesis is a good alternative to the other products present in the market.
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Danion, Anne; Arsenault, Isabelle; Vermette, Patrick
2007-09-01
In vitro methods to evaluate antibacterial activity were used with contact lenses bearing levofloxacin-loaded liposomes developed for the prevention and treatment of bacterial ocular infections such as keratitis. Levofloxacin was incorporated into liposomes before these intact liposomes were immobilized onto the surfaces of soft contact lenses using a multilayer immobilization strategy. The release of levofloxacin from contact lenses bearing 2, 5, and 10 layers of liposomes into a saline buffer at 37 degrees C was monitored by fluorescence. The levofloxacin release, as a function of time, was described by a mechanism taking into account two independent first-order kinetic models. The total release of levofloxacin from the contact lenses was completed within 6 days. The release of levofloxacin from contact lenses bearing 10 layers of liposomes and subsequently soaked overnight in a levofloxacin solution was also studied and compare to that of dried contact lenses without any chemical modification rehydrated in a levofloxacin solution. The antibacterial activity of the liposome-coated contact lenses against Staphylococcus aureus was evaluated by measuring (i) the diameters of the inhibition zone on an agar plate and (ii) the optical density using a broth assay. The liposome-coated lenses showed an antibacterial activity both on agar and in broth following 24 h. When initial bacteria inocula were equal or below 10(6) CFU/mL, all the bacteria were inhibited within 2 h. When using initial bacteria inocula of 10(8) CFU/mL, an initial burst release provided by soaking the liposomal lenses was required for the first hours to inhibit bacteria growth. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.
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NASA Astrophysics Data System (ADS)
Tanaka, Y.; Endo, M.; Moriyama, S.
2017-05-01
Delamination failure is one of the most important engineering problems. This failure can frequently be detrimental to rolling contact machine elements such as bearings, gear wheels, etc. This phenomenon, called rolling contact fatigue, has a close relationship not only with opening-mode but also with shear-mode fatigue crack growth. The crack face interference is known to significantly affect the shear-mode fatigue crack propagation and its threshold behavior. Quantitative investigation on friction and wear at fatigue crack faces in the material is essentially impossible. Previously, thus, a novel ring-on-ring test by making use of fatigue testing machine was proposed to simulate a cyclic reciprocating sliding contact of crack surfaces. However, this test procedure had some problems. For instance, in order to achieve the uniform contact at the start of test, the rubbing of specimens must be conducted in advance. By this treatment, the specimen surfaces were already damaged before the test. In this study, an improvement of experimental method was made to perform the test using the damage-free specimens. The friction and wear properties for heat-treated high carbon-chromium bearing steel were investigated with this new method and the results were compared to the results obtained by using the initially damaged specimens.
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Kapich, Davorin D.
1987-01-01
A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.
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Rolling contact fatigue life of chromium ion plated 440C bearing steel
NASA Technical Reports Server (NTRS)
Bhat, B. N.; Davis, J. H.
1985-01-01
Rolling contact fatigue (RCF) test specimens of heat treated 440C bearing steel were chromium ion plated in thicknesses from 0.1 to 8.0 micron and tested in RCF tester using 700 ksi maximum Hertzian stress. Heavy coatings, greater than about 5 micron in thickness, peeled off or spalled readily, whereas thin coatings, less than 3 micron thick, were tenacious and did not come off. Furthermore, significant improvement in RCF life was obtained with thin chromium ion plated test specimens. The average increase in B10 life was 75% compared with unplated 440C. These preliminary results indicate that ion plating is a promising way to improve bearing life.
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NASA Technical Reports Server (NTRS)
Aggarwal, Arun K.
1993-01-01
Spherical roller bearings have typically been used in applications with speeds limited to about 5000 rpm and loads limited for operation at less than about 0.25 million DN. However, spherical roller bearings are now being designed for high load and high speed applications including aerospace applications. A computer program, SASHBEAN, was developed to provide an analytical tool to design, analyze, and predict the performance of high speed, single row, angular contact (including zero contact angle), spherical roller bearings. The material presented is the mathematical formulation and analytical methods used to develop computer program SASHBEAN. For a given set of operating conditions, the program calculates the bearings ring deflections (axial and radial), roller deflections, contact areas stresses, depth and magnitude of maximum shear stresses, axial thrust, rolling element and cage rotational speeds, lubrication parameters, fatigue lives, and rates of heat generation. Centrifugal forces and gyroscopic moments are fully considered. The program is also capable of performing steady-state and time-transient thermal analyses of the bearing system.
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Bearing tester data compilation, analysis, and reporting and bearing math modeling
NASA Technical Reports Server (NTRS)
1983-01-01
The Shaberth bearing analysis computer program was developed for the analysis of jet engine shaft/bearing systems operating above room temperature with normal hydrocarbon lubricants. It is also possible to use this tool to evaluate the shaft bearing systems operating in cryogenics. Effects such as fluid drag, radial temperature gradients, outer race misalignments and clearance changes were simulated and evaluated. In addition, the speed and preload effects on bearing radial stiffness was evaluated. The Shaberth program was also used to provide contact stresses from which contact geometry was calculated to support other analyses such as the determination of cryogenic fluid film thickness in the contacts and evaluation of surface and subsurface stresses necessary for bearing failure evaluation. This program was a vital tool for the thermal analysis of the bearing in that it provides the heat generation rates at the rolling element/race contacts for input into a thermal model of the bearing/shaft assembly.
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Parenting Stress, Alliance, Child Contact, and Adjustment of Imprisoned Mothers and Fathers
ERIC Educational Resources Information Center
Loper, Ann Booker; Carlson, L. Wrenn; Levitt, Lacey; Scheffel, Kathryn
2009-01-01
The present study contrasted the parenting stress and adjustment patterns of 100 mothers and 111 fathers incarcerated in one of 11 U.S. prisons. In comparison to inmate mothers, fathers had less contact with children, higher levels of parenting stress, and poorer alliance with caregivers. For inmate mothers, higher levels of contact with…
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Ho, Kai-Yu; Epstein, Ryan; Garcia, Ron; Riley, Nicole; Lee, Szu-Ping
2017-02-01
Study Design Controlled laboratory study. Background Although it has been theorized that patellofemoral joint (PFJ) taping can correct patellar malalignment, the effects of PFJ taping techniques on patellar alignment and contact area have not yet been studied during weight bearing. Objective To examine the effects of 2 taping approaches (Kinesio and McConnell) on PFJ alignment and contact area. Methods Fourteen female subjects with patellofemoral pain and PFJ malalignment participated. Each subject underwent a pretaping magnetic resonance imaging (MRI) scan session and 2 MRI scan sessions after the application of the 2 taping techniques, which aimed to correct lateral patellar displacement. Subjects were asked to report their pain level prior to each scan session. During MRI assessment, subjects were loaded with 25% of body weight on their involved/more symptomatic leg at 0°, 20°, and 40° of knee flexion. The outcome measures included patellar lateral displacement (bisect-offset [BSO] index), mediolateral patellar tilt angle, patellar height (Insall-Salvati ratio), contact area, and pain. Patellofemoral joint alignment and contact area were compared among the 3 conditions (no tape, Kinesio, and McConnell) at 3 knee angles using a 2-factor, repeated-measures analysis of variance. Pain was compared among the 3 conditions using the Friedman test and post hoc Wilcoxon signed-rank tests. Results Our data did not reveal any significant effects of either McConnell or Kinesio taping on the BSO index, patellar tilt angle, Insall-Salvati ratio, or contact area across the 3 knee angles, whereas knee angle had a significant effect on the BSO index and contact area. A reduction in pain was observed after the application of the Kinesio taping technique. Conclusion In a weight-bearing condition, this preliminary study did not support the use of PFJ taping as a medial correction technique to alter the PFJ contact area or alignment of the patella. J Orthop Sports Phys Ther 2017
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NASA Technical Reports Server (NTRS)
Vranish, John M. (Inventor)
1998-01-01
A spin bearing assembly including, a pair of mutually opposing complementary bearing support members having mutually spaced apart bearing support surfaces which may be, for example, bearing races and a set of spin bearings located therebetween. Each spin bearing includes a pair of end faces, a central rotational axis passing through the end faces, a waist region substantially mid-way between the end faces and having a first thickness dimension, and discrete side surface regions located between the waist region and the end faces and having a second thickness dimension different from the first thickness dimension of the waist region and wherein the side surface regions further have respective curvilinear contact surfaces adapted to provide a plurality of bearing contact points on the bearing support members.
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NASA Technical Reports Server (NTRS)
Pinel, Stanley I.; Signer, Hans R.; Zaretsky, Erwin V.
2001-01-01
Parametric tests were conducted with an optimized 35-mm-bore-angular-contact ball bearing on a high-speed, high-temperature bearing tester. Results from both air-oil mist lubrication and oil-jet lubrication systems used to lubricate the bearing were compared to speeds of 2.5 x 10(exp 6) DN. The maximum obtainable speed with air-oil mist lubrication is 2.5 x 10(exp 6) DN. Lower bearing temperatures and higher power losses are obtained with oil-jet lubrication than with air-oil mist lubrication. Bearing power loss is a direct function of oil flow to the bearing and independent of oil delivery system. For a given oil-flow rate, bearing temperature and power loss increase with increases in speed. Bearing life is an inverse function of temperature, the difference in temperature between the individual bearing ring components, and the resultant elastohydrodynamic (EHD) film thicknesses. Bearing life is independent of the oil delivery system except as it affects temperature. Cage slip increased with increases in speed. Cage slip as high as 7 percent was measured and was generally higher with air-oil mist lubrication than with oil-jet lubrication.
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Effect of speed and press fit on fatigue life of roller-bearing inner-race contact
NASA Technical Reports Server (NTRS)
Coe, H. H.; Zaretsky, E. V.
1985-01-01
An analysis was performed to determine the effects of inner ring speed and press fit on the rolling element fatigue life of a roller bearing inner race contact. The effects of the resultant hoop and radial stresses on the principal stresses were considered. The maximum shear stresses below the Hertzian contact were determined for different conditions of inner ring speed, load, and geometry and were applied to a conventional ring life analysis. The race contact fatigue life was reduced by more than 90 percent for some conditions when speed and press fit were considered. The depth of the maximum shear stress remained virtually unchanged.
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Tooling Converts Stock Bearings To Custom Bearings
NASA Technical Reports Server (NTRS)
Fleenor, E. N., Jr.
1983-01-01
Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.
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NASA Technical Reports Server (NTRS)
Hamrock, Bernard J.; Dowson, Duncan
1981-01-01
Load-deflection relationships for different types of elliptical contacts such as those found in a ball bearing are developed. Simplified expressions that allow quick calculations of deformation to be made simply from a knowledge of the applied load, the material properties, and the geometry of the contacting elements are presented. Ball bearings subjected to radial, thrust and combined ball loads are analyzed. A design criterion for fatigue life of ball bearings is developed. The section of a satisfactory lubricant, as well as describing systems that provide a constant flow of lubricant to the contact, is considered.
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NASA Technical Reports Server (NTRS)
DellaCorte, Christopher; Howard, S. Adam; Thomas, Fransua; Stanford, Malcolm K.
2016-01-01
Rolling element bearings made from highly-elastic intermetallic materials (HIM)s, such as 60NiTi, are under development for applications that require superior corrosion and shock resistance. Compared to steel, intermetallics have been shown to have much lower rolling contact fatigue (RCF) stress capability in simplified 3-ball on rod (ASTM STP 771) fatigue tests. In the 3-ball tests, poor material quality and microstructural flaws negatively affect fatigue life but such relationships have not been established for full-scale 60NiTi bearings. In this paper, 3-ball-on-rod fatigue behavior of two quality grades of 60NiTi are compared to the fatigue life of full-scale 50mm bore ball bearings made from the same materials. 60NiTi RCF rods with material or microstructural flaws suffered from infant mortality failures at all tested stress levels while high quality 60NiTi rods exhibited no failures at lower stress levels. Similarly, tests of full-scale bearings made from flawed materials exhibited early surface fatigue and through crack type failures while bearings made from high quality material did not fail even in long-term tests. Though the full-scale bearing test data is yet preliminary, the results suggest that the simplified RCF test is a good qualitative predictor of bearing performance. These results provide guidance for materials development and to establish minimum quality levels required for successful bearing operation and life.
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Contact sheet recording with a self-acting negative air bearing
NASA Technical Reports Server (NTRS)
Muftu , Sinan (Inventor); Hinteregger, Hans F (Inventor)
2000-01-01
A flat head and a tape transport arrangement impart a wrap angle to the tape at the upstream corner of the head. The wrap angle, corner sharpness and tape stiffness are sufficient to cause a moving tape to form a hollow bump at the upstream corner, thereby creating a hollow into which entrained air can expand, causing a subambient pressure within and downstream of the bump. This pressure keeps the tape in contact with the head. It is created without the need for a groove or complex pressure relief slot(s). No contact pressure arises at the signal exchange site due to media wrap. The highest contact pressures are developed at a wrapped upstream corner. For a tape drive, traveling in both forward and reverse, the wrap can be at both the upstream and downstream (which is the reverse upstream) corners. Heads that are not flat can also be used, if the wrap angle relative to a main surface is sufficient and not too large. The wrapped head can also be used with rotating media, such as disks (floppy and hard) and rotating heads, such as helical wound heads for video recording. Multiple flat tape bearing surfaces can be separated by grooves and/or angles. Each flat can carry heads along one or more gap lines. Multiple adjacent narrow tracks can thus be written for extreme high track density recording.
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Rolling contact fatigue behavior of Cu and TiN coatings on bearing steel substrates
NASA Technical Reports Server (NTRS)
Hochman, R. F.; Erdemir, A.; Dolan, F. J.; Thom, R. L.
1985-01-01
The resistance of copper and TiN coatings on various bearing substrates to high-load rolling contact fatigue (RCF) is investigated. Special attention is given to the lubricating characteristics of copper deposited by ion plating, and the wear resistant characteristics of TiN deposited by ion plating and magnetron sputtering techniques. RCF samples of 440C and AMS 5749 bearing steels were coated. Sputter deposited and ion plated films were on the RCF samples in a range of thickness from about 2000 A to 2 microns. Results showed a marked improvement of the RCF for pure copper tested on 440C, but a degradation for copper on AMS 5749. It is also found that the 2000 A TiN films behave favorably on the 440C and AMS 5749 bearing steels at RCF stress levels of 786 ksi. Scanning electron microscopy, X-ray diffraction, and electron spectroscopy for chemical analysis were used during the investigation.
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SSME turbopump bearing analytical study
NASA Technical Reports Server (NTRS)
Kannel, J. W.; Merriman, T.
1980-01-01
Three shuttle pump bearings operating under severe overspeed and shut-down conditions are evaluated. The specific parameters investigated include outer race stresses, cage stresses, cage-race drag, bearing heating, and crush loading. A quasi-dynamic version of the BASDAP computer code was utilized which involved the calculation of ball-race forces (inner and outer), contact pressures, contact dimensions, and contact angles as a function of (1) axial load, (2) radial load, and (3) centrifugal load on the bearing. Generally, radial loads on the order of 13,300 N (3000 pounds) per bearing or 26,700 N (6000 pounds) per bearing pair, could be expected to cause severe problems to any of the bearings with a 17,800 N (4000 pounds) axial load. Further, when possible temperature excursions are considered, even a load of 8900 N (2000 pounds) may be excessive. However, high momentary radial loads with a 3800 N (850 pounds) axial load would not be anticipated to cause catastrophic failure of the fuel pump bearing.
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NASA Astrophysics Data System (ADS)
Chen, Junxun; Cheng, Longsheng; Yu, Hui; Hu, Shaolin
2018-01-01
ABSTRACTSFor the timely identification of the potential faults of a rolling <span class="hlt">bearing</span> and to observe its health condition intuitively and accurately, a novel fault diagnosis and health assessment model for a rolling <span class="hlt">bearing</span> based on the ensemble empirical mode decomposition (EEMD) method and the <span class="hlt">adjustment</span> Mahalanobis-Taguchi system (AMTS) method is proposed. The specific steps are as follows: First, the vibration signal of a rolling <span class="hlt">bearing</span> is decomposed by EEMD, and the extracted features are used as the input vectors of AMTS. Then, the AMTS method, which is designed to overcome the shortcomings of the traditional Mahalanobis-Taguchi system and to extract the key features, is proposed for fault diagnosis. Finally, a type of HI concept is proposed according to the results of the fault diagnosis to accomplish the health assessment of a <span class="hlt">bearing</span> in its life cycle. To validate the superiority of the developed method proposed approach, it is compared with other recent method and proposed methodology is successfully validated on a vibration data-set acquired from seeded defects and from an accelerated life test. The results show that this method represents the actual situation well and is able to accurately and effectively identify the fault type.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970012935','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970012935"><span>Computerized Design and Generation of Gear Drives With a Localized <span class="hlt">Bearing</span> <span class="hlt">Contact</span> and a Low Level of Transmission Errors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, F.; Chen, J.; Seol, I.; Kim, D.; Lu, J.; Zhao, X.; Handschuh, R.</p> <p>1996-01-01</p> <p>A general approach developed for the computerized simulation of loaded gear drives is presented. In this paper the methodology used to localize the <span class="hlt">bearing</span> <span class="hlt">contact</span>, provide a parabolic function of transmission errors, and simulate meshing and <span class="hlt">contact</span> of unloaded gear drives is developed. The approach developed is applied to spur and helical gears, spiral bevel gears, face-gear drives, and worm-gear drives with cylindrical worms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170002297','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170002297"><span>Microstructural and Material Quality Effects on Rolling <span class="hlt">Contact</span> Fatigue of Highly Elastic Intermetallic NiTi Ball <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dellacorte, Christopher; Howard, S. Adam; Thomas, Fransua; Stanford, Malcolm K.</p> <p>2017-01-01</p> <p>Rolling element <span class="hlt">bearings</span> made from highly-elastic intermetallic materials (HIM)s, such as 60NiTi, are under development for applications that require superior corrosion and shock resistance. Compared to steel, intermetallics have been shown to have much lower rolling <span class="hlt">contact</span> fatigue (RCF) stress capability in simplified 3-ball on rod (ASTM STP 771) fatigue tests. In the 3-ball tests, poor material quality and microstructural flaws negatively affect fatigue life but such relationships have not been established for full-scale 60NiTi <span class="hlt">bearings</span>. In this paper, 3-ball-on-rod fatigue behavior of two quality grades of 60NiTi are compared to the fatigue life of full-scale 50mm bore ball <span class="hlt">bearings</span> made from the same materials. 60NiTi RCF rods with material or microstructural flaws suffered from infant mortality failures at all tested stress levels while high quality 60NiTi rods exhibited no failures at lower stress levels. Similarly, tests of full-scale <span class="hlt">bearings</span> made from flawed materials exhibited early surface fatigue and through crack type failures while <span class="hlt">bearings</span> made from high quality material did not fail even in long-term tests. Though the full-scale <span class="hlt">bearing</span> test data is yet preliminary, the results suggest that the simplified RCF test is a good qualitative predictor of <span class="hlt">bearing</span> performance. These results provide guidance for materials development and to establish minimum quality levels required for successful <span class="hlt">bearing</span> operation and life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........94T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........94T"><span><span class="hlt">Contact</span> Mechanics and Failure Modes of Compliant Polymeric <span class="hlt">Bearing</span> Materials for Knee Cartilage Replacement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tohfafarosh, Mariya Shabbir</p> <p></p> <p> control samples. However, chemical spectra of electron beam sterilized samples revealed minor changes, which were absent in unsterilized and gamma sterilized samples. Upon successful sterilization evaluation, both polycarbonate urethane and the novel hydrogel were investigated for the <span class="hlt">contact</span> mechanics of compliant-on-compliant artificial knee <span class="hlt">bearings</span> using a finite element analysis approach. A simplified, axisymmetric, finite element model of a medial knee compartment was developed and validated, and a design of simulation experiments was carried out to evaluate the effect of implant conformity, implant thickness and material properties on the <span class="hlt">contact</span> mechanics of compliant knee <span class="hlt">bearings</span> under normal walking and stair climbing loads. All input parameters, namely, implant conformity, implant thickness and material properties, significantly (p<0.001) affected the maximum principal stress, Von Mises stress, maximum shear stress, maximum principal strain, maximum <span class="hlt">contact</span> pressure and <span class="hlt">contact</span> area. The knee implant <span class="hlt">contact</span> mechanics demonstrated sensitivity to all the three design factors, and a correlation between resulting stresses and implant conformity as well as thickness was observed. However, the conformity had the highest effect-size on the <span class="hlt">contact</span> mechanics. The maximum principal stress value halves and the <span class="hlt">contact</span> area doubles when ≥ 95% implant conformity (i.e. the ratio of femoral to tibial surface’s radii of curvature) and ≥ 3mm thickness was used, hence, these parameters were recommended for the design of compliant knee <span class="hlt">bearings</span>. Finally, a battery of mechanical tests was carried out to evaluate the failure criteria of the proposed compliant polymers under physiological loads and strain rates. Uniaxial tests, including tension and unconfined compression, and biaxial tests, such as plane strain compression, were carried out to characterize the mechanical behavior of different material formulations at physiologically relevant testing rates. The materials</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790000259&hterms=23447&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2526%252323447','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790000259&hterms=23447&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2526%252323447"><span>Lash-free spherical <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hein, L. A.; Myers, W. N.</p> <p>1979-01-01</p> <p>Grooved and chamfered spherical <span class="hlt">bearing</span> can maintain close <span class="hlt">contact</span> between its ball and race, even when it is vibrated. <span class="hlt">Bearing</span> thus eliminates major cause of wear and loosening in spherical <span class="hlt">bearings</span>: pounding of ball on race under vibration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930019221','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930019221"><span>Nucleation and growth of rolling <span class="hlt">contact</span> failure of 440C <span class="hlt">bearing</span> steel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gupta, V.; Bastias, P. C.; Hahn, G. T.; Rubin, C. A.</p> <p>1992-01-01</p> <p>A 'two-body' elasto-plastic finite element model of 2-dimensional rolling and rolling-plus-sliding was developed to treat the effect of surface irregularities. The model consists of a smooth cylinder in <span class="hlt">contact</span> with a semi-infinite half-space that is either smooth or fitted with one of 0.4 microns deep or 7 microns deep groove, or a 0.4 microns high ridge-like asperity. The model incorporates elastic-linear-kinematic hardening-plastic (ELKP) and non-linear-kinematic hardening-plastic (NLKP) material constitutive relations appropriate for hardened <span class="hlt">bearing</span> steel and the 440C grade. The calculated <span class="hlt">contact</span> pressure distribution is Hertzian for smooth body <span class="hlt">contact</span>, and it displays intense, stationary, pressure spikes superposed on the Hertzian pressure for <span class="hlt">contact</span> with the grooved and ridged surface. The results obtained for the 0.4 microns deep groove compare well with those reported by Elsharkawy and Hamrock for an EHD lubricated <span class="hlt">contact</span>. The effect of translating the counterface on the half space as opposed to indenting the half space with the counter face with no translation is studied. The stress and strain values near the surface are found to be similar for the two cases, whereas they are significantly different in the subsurface. It is seen that when tiny shoulders are introduced at the edge of the groove in the finite element model, the incremental plasticity and residual stresses are significantly higher in the vicinity of the right shoulder (rolling direction is from left to right) than at the left shoulder. This may explain the experimental observation that the spall nucleation occurs at the exit end of the artificially planted indents. Pure rolling calculations are compared with rolling + sliding calculations. For a coefficient of friction, mu = 0.1, the effect of friction is found to be small. Efforts were made to identify the material constitutive relations which best describe the deformation characteristics of the <span class="hlt">bearing</span> steels in the initial few cycles</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940009972','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940009972"><span>Computer program for analysis of high speed, single row, angular <span class="hlt">contact</span>, spherical roller <span class="hlt">bearing</span>, SASHBEAN. Volume 1: User's guide</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aggarwal, Arun K.</p> <p>1993-01-01</p> <p>The computer program SASHBEAN (Sikorsky Aircraft Spherical Roller High Speed <span class="hlt">Bearing</span> Analysis) analyzes and predicts the operating characteristics of a Single Row, Angular <span class="hlt">Contact</span>, Spherical Roller <span class="hlt">Bearing</span> (SRACSRB). The program runs on an IBM or IBM compatible personal computer, and for a given set of input data analyzes the <span class="hlt">bearing</span> design for it's ring deflections (axial and radial), roller deflections, <span class="hlt">contact</span> areas and stresses, induced axial thrust, rolling element and cage rotation speeds, lubrication parameters, fatigue lives, and amount of heat generated in the <span class="hlt">bearing</span>. The dynamic loading of rollers due to centrifugal forces and gyroscopic moments, which becomes quite significant at high speeds, is fully considered in this analysis. For a known application and it's parameters, the program is also capable of performing steady-state and time-transient thermal analyses of the <span class="hlt">bearing</span> system. The steady-state analysis capability allows the user to estimate the expected steady-state temperature map in and around the <span class="hlt">bearing</span> under normal operating conditions. On the other hand, the transient analysis feature provides the user a means to simulate the 'lost lubricant' condition and predict a time-temperature history of various critical points in the system. The <span class="hlt">bearing</span>'s 'time-to-failure' estimate may also be made from this (transient) analysis by considering the <span class="hlt">bearing</span> as failed when a certain temperature limit is reached in the <span class="hlt">bearing</span> components. The program is fully interactive and allows the user to get started and access most of its features with a minimal of training. For the most part, the program is menu driven, and adequate help messages were provided to guide a new user through various menu options and data input screens. All input data, both for mechanical and thermal analyses, are read through graphical input screens, thereby eliminating any need of a separate text editor/word processor to edit/create data files. Provision is also available to select</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29806422','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29806422"><span>[<span class="hlt">Contact</span> characteristics research of acetabular weight-<span class="hlt">bearing</span> area with different internal fixation methods after compression fracture of acetabular dome].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Bowen; Zhang, Qingsong; An, Siqi; Pei, Baorui; Wu, Xiaobo</p> <p>2017-08-01</p> <p>To establish the model of compression fracture of acetabular dome, and to measure the <span class="hlt">contact</span> characteristics of acetabular weight-<span class="hlt">bearing</span> area of acetabulum after 3 kinds of internal fixation. Sixteen fresh adult half pelvis specimens were randomly divided into 4 groups, 4 specimens each group. Group D was the complete acetabulum (control group), and the remaining 3 groups were prepared acetabular dome compression fracture model. The fractures were fixed with reconstruction plate in group A, antegrade raft screws in group B, and retrograde raft screws in group C. The pressure sensitive films were attached to the femoral head, and the axial compression test was carried out on the inverted single leg standing position. The weight-<span class="hlt">bearing</span> area, average stress, and peak stress were measured in each group. Under the loading of 500 N, the acetabular weight-<span class="hlt">bearing</span> area was significantly higher in group D than in other 3 groups ( P <0.05), and the average stress and peak stress were significantly lower than in other 3 groups ( P <0.05). The acetabular weight-<span class="hlt">bearing</span> area were significantly higher in group B and group C than in group A, and the average stress and peak stress were significantly lower than in group A ( P <0.05). There was no significant difference in the above indexes between group B and group C ( P >0.05). For the compression fracture of the acetabular dome, the <span class="hlt">contact</span> characteristics of the weight-<span class="hlt">bearing</span> area can not restore to the normal level, even if the anatomical reduction and rigid internal fixation were performed; compared with the reconstruction plate fixation, antegrade and retrograde raft screws fixations can increase the weight-<span class="hlt">bearing</span> area, reduce the average stress and peak stress, and reduce the incidence of traumatic arthritis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017FrME..tmp...97S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017FrME..tmp...97S"><span>Review of the damage mechanism in wind turbine gearbox <span class="hlt">bearings</span> under rolling <span class="hlt">contact</span> fatigue</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Su, Yun-Shuai; Yu, Shu-Rong; Li, Shu-Xin; He, Yan-Ni</p> <p>2017-12-01</p> <p>Wind turbine gearbox <span class="hlt">bearings</span> fail with the service life is much shorter than the designed life. Gearbox <span class="hlt">bearings</span> are subjected to rolling <span class="hlt">contact</span> fatigue (RCF) and they are observed to fail due to axial cracking, surface flaking, and the formation of white etching areas (WEAs). The current study reviewed these three typical failure modes. The underlying dominant mechanisms were discussed with emphasis on the formation mechanism of WEAs. Although numerous studies have been carried out, the formation of WEAs remains unclear. The prevailing mechanism of the rubbing of crack faces that generates WEAs was questioned by the authors. WEAs were compared with adiabatic shear bands (ASBs) generated in the high strain rate deformation in terms of microstructural compositions, grain refinement, and formation mechanism. Results indicate that a number of similarities exist between them. However, substantial evidence is required to verify whether or not WEAs and ASBs are the same matters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000120368','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000120368"><span>Design and Operating Characteristics of High-Speed, Small-Bore Cylindrical-Roller <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pinel, Stanley, I.; Signer, Hans R.; Zaretsky, Erwin V.</p> <p>2000-01-01</p> <p>The computer program SHABERTH was used to analyze 35-mm-bore cylindrical roller <span class="hlt">bearings</span> designed and manufactured for high-speed turbomachinery applications. Parametric tests of the <span class="hlt">bearings</span> were conducted on a high-speed, high-temperature <span class="hlt">bearing</span> tester and the results were compared with the computer predictions. <span class="hlt">Bearings</span> with a channeled inner ring were lubricated through the inner ring, while <span class="hlt">bearings</span> with a channeled outer ring were lubricated with oil jets. Tests were run with and without outer-ring cooling. The predicted <span class="hlt">bearing</span> life decreased with increasing speed because of increased <span class="hlt">contact</span> stresses caused by centrifugal load. Lower temperatures, less roller skidding, and lower power losses were obtained with channeled inner rings. Power losses calculated by the SHABERTH computer program correlated reasonably well with the test results. The Parker formula for XCAV (used in SHABERTH as a measure of oil volume in the <span class="hlt">bearing</span> cavity) needed to be <span class="hlt">adjusted</span> to reflect the prevailing operating conditions. The XCAV formula will need to be further refined to reflect roller <span class="hlt">bearing</span> lubrication, ring design, cage design, and location of the cage-controlling land.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1943b0013A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1943b0013A"><span>Selection of <span class="hlt">contact</span> <span class="hlt">bearing</span> couple materials for hip prosthesis using finite element analysis under static conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arirajan, K. A.; Chockalingam, K.; Vignesh, C.</p> <p>2018-04-01</p> <p>Implants are the artificial parts to replace the missing bones or joints in human anatomy to give mechanical support. Hip joint replacement is an important issue in orthopaedic surgery. The main concern limiting the long-run success of the total hip replacement is the limited service life. Hip replacement technique is widely used in replacing the femur head and acetabular cup by materials that are highly biocompatible. The success of the artificial hip replacement depends upon proper material selection, structure, and shape of the hip prosthesis. Many orthopaedic analyses have been tried with different materials, but ended with partial success on the application side. It is a critical task for selecting the best material pair in the hip prosthesis design. This work develops the finite element analysis of an artificial hip implant to study highest von Mises stress, <span class="hlt">contact</span> pressure and elastic strain occurs for the dissimilar material combination. The different <span class="hlt">bearing</span> couple considered for the analysis are Metal on Metal, Metal on Plastic, Metal on Ceramic, Ceramic on Plastic, Ceramic on Ceramic combinations. The analysis is carried out at different static positions of a human (i.e) standing, sitting. The results reveals that the combination with metal in <span class="hlt">contact</span> with plastic (i.e) Titanium femoral head paired with Ultra High Molecular Weight Poly Ethylene acetabular cup reduces maximum von Mises stress and also it gives lowest <span class="hlt">contact</span> pressure than other combination of <span class="hlt">bearing</span> couples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770005460','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770005460"><span>Roller <span class="hlt">bearing</span> geometry design</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Savage, M.; Pinkston, B. H. W.</p> <p>1976-01-01</p> <p>A theory of kinematic stabilization of rolling cylinders is extended and applied to the design of cylindrical roller <span class="hlt">bearings</span>. The kinematic stabilization mechanism puts a reverse skew into the rolling elements by changing the roller taper. Twelve basic <span class="hlt">bearing</span> modification designs are identified amd modeled. Four have single transverse convex curvature in their rollers while eight have rollers which have compound transverse curvature made up of a central cylindrical band surrounded by symmetric bands with slope and transverse curvature. The <span class="hlt">bearing</span> designs are modeled for restoring torque per unit axial displacement, <span class="hlt">contact</span> stress capacity, and <span class="hlt">contact</span> area including dynamic loading, misalignment sensitivity and roller proportion. Design programs are available which size the single transverse curvature roller designs for a series of roller slopes and load separations and which design the compound roller <span class="hlt">bearings</span> for a series of slopes and transverse radii of curvature. The compound rollers are proportioned to have equal <span class="hlt">contact</span> stresses and minimum size. Design examples are also given.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_3 --> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950019654','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950019654"><span>Computerized Design and Generation of Low-Noise Gears with Localized <span class="hlt">Bearing</span> <span class="hlt">Contact</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, Faydor L.; Chen, Ningxin; Chen, Jui-Sheng; Lu, Jian; Handschuh, Robert F.</p> <p>1995-01-01</p> <p>The results of research projects directed at the reduction of noise caused by misalignment of the following gear drives: double-circular arc helical gears, modified involute helical gears, face-milled spiral bevel gears, and face-milled formate cut hypoid gears are presented. Misalignment in these types of gear drives causes periodic, almost linear discontinuous functions of transmission errors. The period of such functions is the cycle of meshing when one pair of teeth is changed for the next. Due to the discontinuity of such functions of transmission errors high vibration and noise are inevitable. A predesigned parabolic function of transmission errors that is able to absorb linear discontinuous functions of transmission errors and change the resulting function of transmission errors into a continuous one is proposed. The proposed idea was successfully tested using spiral bevel gears and the noise was reduced a substantial amount in comparison with the existing design. The idea of a predesigned parabolic function is applied for the reduction of noise of helical and hypoid gears. The effectiveness of the proposed approach has been investigated by developed TCA (tooth <span class="hlt">contact</span> analysis) programs. The <span class="hlt">bearing</span> <span class="hlt">contact</span> for the mentioned gears is localized. Conditions that avoid edge <span class="hlt">contact</span> for the gear drives have been determined. Manufacturing of helical gears with new topology by hobs and grinding worms has been investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..322d2011D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..322d2011D"><span>Integral finite element analysis of turntable <span class="hlt">bearing</span> with flexible rings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deng, Biao; Liu, Yunfei; Guo, Yuan; Tang, Shengjin; Su, Wenbin; Lei, Zhufeng; Wang, Pengcheng</p> <p>2018-03-01</p> <p>This paper suggests a method to calculate the internal load distribution and <span class="hlt">contact</span> stress of the thrust angular <span class="hlt">contact</span> ball turntable <span class="hlt">bearing</span> by FEA. The influence of the stiffness of the <span class="hlt">bearing</span> structure and the plastic deformation of <span class="hlt">contact</span> area on the internal load distribution and <span class="hlt">contact</span> stress of the <span class="hlt">bearing</span> is considered. In this method, the load-deformation relationship of the rolling elements is determined by the finite element <span class="hlt">contact</span> analysis of a single rolling element and the raceway. Based on this, the nonlinear <span class="hlt">contact</span> between the rolling elements and the inner and outer ring raceways is same as a nonlinear compression spring and <span class="hlt">bearing</span> integral finite element analysis model including support structure was established. The effects of structural deformation and plastic deformation on the built-in stress distribution of slewing <span class="hlt">bearing</span> are investigated on basis of comparing the consequences of load distribution, inner and outer ring stress, <span class="hlt">contact</span> stress and other finite element analysis results with the traditional <span class="hlt">bearing</span> theory, which has guiding function for improving the design of slewing <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1115768','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1115768"><span>Rolling Element <span class="hlt">Bearing</span> Stiffness Matrix Determination (Presentation)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Guo, Y.; Parker, R.</p> <p>2014-01-01</p> <p>Current theoretical <span class="hlt">bearing</span> models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/<span class="hlt">contact</span> mechanics model is developed for rolling element <span class="hlt">bearings</span> with the focus of obtaining accurate <span class="hlt">bearing</span> stiffness for a wide range of <span class="hlt">bearing</span> types and parameters. A combined surface integral and finite element method is used to solve for the <span class="hlt">contact</span> mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the <span class="hlt">bearing</span> <span class="hlt">contact</span> due to the orbital motion of the rolling elements. A numerical method is developed to determine the full <span class="hlt">bearing</span> stiffness matrix corresponding tomore » two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between <span class="hlt">bearing</span> radial, axial, and tilting <span class="hlt">bearing</span> deflections.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......450A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......450A"><span>Evolution of mechanical properties of M50 <span class="hlt">bearing</span> steel due to rolling <span class="hlt">contact</span> fatigue</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Allison, Bryan D.</p> <p></p> <p>Current <span class="hlt">bearing</span> life models significantly under predict the life of <span class="hlt">bearings</span> made of modern ultra-clean steels. New life models that include the constitutive response of the material are needed. However, the constitutive response of <span class="hlt">bearing</span> steel is known to change during <span class="hlt">bearing</span> operation. In the current study, the evolution of the mechanical properties of M50 <span class="hlt">bearing</span> steel due to rolling <span class="hlt">contact</span> fatigue (RCF) was investigated. A combination of M50 balls and rods were subjected to RCF testing under various conditions (e.g. number of RCF cycles, applied Hertzian stress, and interacting material). Additionally, some of the balls tested went through a proprietary mechanical process to induce compressive residual stresses over the first several hundred microns into the depth of the ball prior to RCF testing. After RCF testing, the specimens were subjected to a number of tests. First, the residual stresses within the subsurface RCF affected region were measured via x-ray diffraction. The residual stresses within the mechanically processed (MP) balls were found to not significantly change due to RCF, while a linear relationship was found between the maximum residual stress with the RCF affected zone and the Hertzian stress for the unprocessed balls. Then, the specimens were sectioned, polished, and chemically etched to study the evolution of the microstructure due to RCF. A similar relationship was found between the size of the dark etching region (DER) and the Hertzian stress. Formation of a light etching region (LER) is demonstrated to not correlate with a decrease in material strength and hardness, but it does serve as a predictor for failure due to spall. Micro-indentation was performed within subsurface to estimate the local yield stress. Micro-indentation is not able to provide information about the stress-strain response, only the yield strength. Hence, a novel method to extract and test miniature compression specimens from within the RCF affected regions of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850018566','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850018566"><span>Development of new materials for turbopump <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maurer, R. E.; Pallini, R. A.</p> <p>1985-01-01</p> <p>The life requirement for the angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span> in the Space Shuttle Main Engine (SSME) high pressure oxygen turbopump (HPOTP) is 7.5 hours. In actual operation, significantly shorter service life was experienced. The objective is to identify <span class="hlt">bearing</span> materials and/or materials processing techniques offering signficant potential for extending HPOTP <span class="hlt">bearing</span> performance life. Interactive thermomechanical analysis of the HPOTP <span class="hlt">bearing</span>-shaft system was performed with the SHABERTH computer program. <span class="hlt">Bearing</span> fatigue life, ball-race <span class="hlt">contact</span> stress, heat generation rate, bulk ring temperatures and circumferential stress in the inner rings were quantified as functions of radial load, thrust load and ball-race <span class="hlt">contact</span> friction. Criteria established from the output of this analysis are being used for material candidate selection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29724557','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29724557"><span>Analysis of flexural strength and <span class="hlt">contact</span> pressure after simulated chairside <span class="hlt">adjustment</span> of pressed lithium disilicate glass-ceramic.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ramadhan, Ali; Thompson, Geoffrey A; Maroulakos, Georgios; Berzins, David</p> <p>2018-04-30</p> <p>Research evaluating load-to-failure of pressed lithium disilicate glass-ceramic (LDGC) with a clinically validated test after <span class="hlt">adjustment</span> and repair procedures is scarce. The purpose of this in vitro study was to investigate the effect of the simulated chairside <span class="hlt">adjustment</span> of the intaglio surface of monolithic pressed LDGC and procedures intended to repair damage. A total of 423 IPS e.max Press (Ivoclar Vivadent AG) disks (15 mm diameter, 1 mm height) were used in the study. The material was tested by using an equibiaxial loading arrangement (n≥30/group) and a <span class="hlt">contact</span> pressure test (n≥20/group). Specimens were assigned to 1 of 14 groups. One-half was assigned to the equibiaxial load test and the other half underwent <span class="hlt">contact</span> pressure testing. Testing was performed in 2 parts, before glazing and after glazing. Before-glazing specimens were devested and entered in the test protocol, while after-glazing specimens were devested and glazed before entering the test protocol. Equibiaxial flexure test specimens were placed on a ring-on-ring apparatus and loaded until failure. <span class="hlt">Contact</span> pressure specimens were cemented to epoxy resin blocks with a resin cement and loaded with a 50-mm diameter hemisphere until failure. Tests were performed on a universal testing machine with a crosshead speed of 0.5 mm/min. Weibull statistics and likelihood ratio contour plots determined intergroup differences (95% confidence bounds). Before glazing, the equibiaxial flexural strength test and the Weibull and likelihood ratio contour plots demonstrated a significantly higher failure strength for 1EC (188 MPa) than that of the damaged and/or repaired groups. Glazing following diamond-<span class="hlt">adjustment</span> (1EGG) was the most beneficial post-damage procedure (176 MPa). Regarding the <span class="hlt">contact</span> pressure test, the Weibull and likelihood ratio contour plots revealed no significant difference between the 1PC (98 MPa) and 1PGG (98 MPa) groups. Diamond-<span class="hlt">adjustment</span>, without glazing (1EG and 1PG), resulted in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......280P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......280P"><span>A microstructure sensitive study of rolling <span class="hlt">contact</span> fatigue in <span class="hlt">bearing</span> steels: A numerical and experimental approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pandkar, Anup Surendra</p> <p></p> <p><span class="hlt">Bearings</span> are an integral part of machine components that transmit rotary power such as cars, motors, engines etc. Safe <span class="hlt">bearing</span> operation is essential to avoid serious failures and accidents, which necessitates their timely replacement. This calls for an accurate <span class="hlt">bearing</span> life prediction methods. Based on the Lundberg-Palmgen (LP) model, current life models consistently under predict <span class="hlt">bearings</span> lives. Improvement in life prediction requires understanding of the <span class="hlt">bearing</span> failure mechanism i.e. Rolling <span class="hlt">Contact</span> Fatigue (RCF). The goal of this research is to develop a mechanistic framework required for an improved <span class="hlt">bearing</span> life prediction model. Such model should account for metal plasticity, influence of microstructural features and cyclically evolving stressstrain fields induced during RCF. To achieve this, elastic-plastic finite element (FE) study is undertaken to investigate the response of M50-NiL <span class="hlt">bearing</span> steel during RCF. Specifically, a microstructure sensitive study of the influence of non-metallic inclusions on RCF response of <span class="hlt">bearings</span> is presented. M50-NiL microstructure consists of carbides which are orders of magnitude smaller than <span class="hlt">bearing</span> dimensions. To account for this size difference, a multi-scale FE modeling approach is employed. The FE results reveal that hard carbide particles act as local stress risers, alter surrounding stressstrain fields and cause micro-scale yielding of steel matrix. Moreover, they introduce a shear stress cycle with non-zero mean stress, which promotes micro-plastic strain accumulation via ratcheting mechanism. Localized ratcheting is primarily responsible for cyclic hardening within the RCF affected region. Such evolution of subsurface hardness can be used to quantify RCF induced damage. To investigate this further, cyclic hardening response of the RCF affected region is simulated. The results show good agreement with the experimental observations. The cyclic stress-strain fields obtained from these simulations and the knowledge of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720013820','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720013820"><span>Arched-outer-race ball-<span class="hlt">bearing</span> analysis considering centrifugal forces</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamrock, B. J.; Anderson, W. J.</p> <p>1972-01-01</p> <p>A first-order thrust load analysis that considers centrifugal forces but which neglects gyroscopics, elastohydrodynamics, and thermal effects was performed. The analysis was applied to a 150-mm-bore angular-<span class="hlt">contact</span> ball <span class="hlt">bearing</span>. Fatigue life, <span class="hlt">contact</span> loads, and <span class="hlt">contact</span> angles are shown for conventional and arched <span class="hlt">bearings</span>. The results indicate that an arched <span class="hlt">bearing</span> is highly desirable for high-speed applications. In particular, at an applied load of 4448 n (1000 lb) and a DN value of 3 million (20,000 rpm) the arched <span class="hlt">bearing</span> shows an improvement in life of 306 percent over that of a conventional <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4261988','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/4261988"><span>THRUST <span class="hlt">BEARING</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Heller, P.R.</p> <p>1958-09-16</p> <p>A thrust <span class="hlt">bearing</span> suitable for use with a rotor or blower that is to rotate about a vertical axis is descrihed. A centrifagal jack is provided so thnt the device may opernte on one hearing at starting and lower speeds, and transfer the load to another <span class="hlt">bearing</span> at higher speeds. A low viscosity fluid is used to lubricate the higher speed operation <span class="hlt">bearing</span>, in connection with broad hearing -surfaces, the ability to withstand great loads, and a relatively high friction loss, as contraated to the lower speed operatio;n <span class="hlt">bearing</span> which will withstand only light thrust loads but is sufficiently frictionfree to avoid <span class="hlt">bearing</span> seizure during slow speed or startup operation. An axially aligned shaft pin provides the <span class="hlt">bearing</span> surface for low rotational speeds, but at higher speed, weights operating against spring tension withdraw nthe shaft pin into the <span class="hlt">bearing</span> proper and the rotor shaft comes in <span class="hlt">contact</span> with the large <span class="hlt">bearing</span> surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950020758','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950020758"><span>Effect of Hoop Stress on Ball <span class="hlt">Bearing</span> Life Prediction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, Erwin V.; August, Richard; Coe, Harold H.</p> <p>1995-01-01</p> <p>A finite-element analysis (FEA) of a generic, dimensionally normalized inner race of an angular-<span class="hlt">contact</span> ball <span class="hlt">bearing</span> was performed under varying conditions of speed and the press (or interference) fit of the inner-race bore on a journal. The FEA results at the ball-race <span class="hlt">contact</span> were used to derive an equation from which was obtained the radius of an equivalent cylindrical <span class="hlt">bearing</span> race with the same or similar hoop stress. The radius of the equivalent cylinder was used to obtain a generalized closed-form approximation of the hoop stresses at the ball-inner-race <span class="hlt">contact</span> in an angular-<span class="hlt">contact</span> ball <span class="hlt">bearing</span>. A life analysis was performed on both a 45- and a 120-mm-bore, angular-<span class="hlt">contact</span> ball <span class="hlt">bearing</span>. The predicted lives with and without hoop stress were compared with experimental endurance results obtained at 12000 and 25000 rpm with the 120-mm-bore ball <span class="hlt">bearing</span>. A life factor equation based on hoop stress is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030105670','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030105670"><span>Fault Tolerant Homopolar Magnetic <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert</p> <p>2003-01-01</p> <p>Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic <span class="hlt">bearing</span> is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which <span class="hlt">adjust</span> the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher <span class="hlt">bearing</span> <span class="hlt">contact</span> following pole failures and (b) re-levitation off of the catcher <span class="hlt">bearings</span> following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100036589','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100036589"><span>Frictionless <span class="hlt">Bearing</span> Uses Permanent Magnets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1965-01-01</p> <p>The purpose of this innovation was to develop a frictionless <span class="hlt">bearing</span> for high speed, light load applications. The device involves the incorporation of permanent magnets in the <span class="hlt">bearing</span> design. The repulsion of like magnetic poles provides concentric support of the inner member so that no metallic <span class="hlt">contact</span> occurs between the <span class="hlt">bearing</span> surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950015288','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950015288"><span>Modeling of rolling element <span class="hlt">bearing</span> mechanics. Theoretical manual</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Merchant, David H.; Greenhill, Lyn M.</p> <p>1994-01-01</p> <p>This report documents the theoretical basis for the Rolling Element <span class="hlt">Bearing</span> Analysis System (REBANS) analysis code which determines the quasistatic response to external loads or displacement of three types of high-speed rolling element <span class="hlt">bearings</span>: angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span>; duplex angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span>; and cylindrical roller <span class="hlt">bearings</span>. The model includes the effects of <span class="hlt">bearing</span> ring and support structure flexibility. It is comprised of two main programs: the Preprocessor for <span class="hlt">Bearing</span> Analysis (PREBAN) which creates the input files for the main analysis program; and Flexibility Enhanced Rolling Element <span class="hlt">Bearing</span> Analysis (FEREBA), the main analysis program. A companion report addresses the input instructions for and features of the computer codes. REBANS extends the capabilities of the SHABERTH (Shaft and <span class="hlt">Bearing</span> Thermal Analysis) code to include race and housing flexibility, including such effects as dead band and preload springs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910009666','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910009666"><span>Mechanical design problems associated with turbopump fluid film <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Evces, Charles R.</p> <p>1990-01-01</p> <p>Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller <span class="hlt">contact</span> <span class="hlt">bearings</span> for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make <span class="hlt">bearing</span> wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, <span class="hlt">bearings</span> must currently be replaced after 2 missions. One solution to the <span class="hlt">bearing</span> wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film <span class="hlt">bearings</span> in lieu of continuous <span class="hlt">contact</span> <span class="hlt">bearings</span>. Hydrostatic, hydrodynamic, and damping seal <span class="hlt">bearings</span> are all replacement candidates for <span class="hlt">contact</span> <span class="hlt">bearings</span> in rocket engine high speed turbomachinery. These three types of fluid film <span class="hlt">bearings</span> have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, <span class="hlt">bearing</span> wear inspection and measurement, and <span class="hlt">bearing</span> fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) <span class="hlt">bearing</span>, but the results are pertinent to high-speed cryogenic turbomachinery in general.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090043144','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090043144"><span>Anti-backlash gear <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vranish, John M. (Inventor)</p> <p>2009-01-01</p> <p>A gear <span class="hlt">bearing</span> having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and <span class="hlt">bearing</span> functions simultaneously. The gears are moving at substantially the same speed at their <span class="hlt">contact</span> points. The gears may be roller gear <span class="hlt">bearings</span> or phase-shifted gear <span class="hlt">bearings</span>, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear <span class="hlt">bearing</span> movement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050175860','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050175860"><span>Effect of Silicon Nitride Balls and Rollers on Rolling <span class="hlt">Bearing</span> Life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, Erwin V.; Vlcek, Brian L.; Hendricks, Robert C.</p> <p>2005-01-01</p> <p>Three decades have passed since the introduction of silicon nitride rollers and balls into conventional rolling-element <span class="hlt">bearings</span>. For a given applied load, the <span class="hlt">contact</span> (Hertz) stress in a hybrid <span class="hlt">bearing</span> will be higher than an all-steel rolling-element <span class="hlt">bearing</span>. The silicon nitride rolling-element life as well as the lives of the steel races were used to determine the resultant <span class="hlt">bearing</span> life of both hybrid and all-steel <span class="hlt">bearings</span>. Life factors were determined and reported for hybrid <span class="hlt">bearings</span>. Under nominal operating speeds, the resultant calculated lives of the deep-groove, angular-<span class="hlt">contact</span>, and cylindrical roller hybrid <span class="hlt">bearings</span> with races made of post-1960 <span class="hlt">bearing</span> steel increased by factors of 3.7, 3.2, and 5.5, respectively, from those calculated using the Lundberg-Palmgren equations. An all-steel <span class="hlt">bearing</span> under the same load will have a longer life than the equivalent hybrid <span class="hlt">bearing</span> under the same conditions. Under these conditions, hybrid <span class="hlt">bearings</span> are predicted to have a lower fatigue life than all-steel <span class="hlt">bearings</span> by 58 percent for deep-groove <span class="hlt">bearings</span>, 41 percent for angular-<span class="hlt">contact</span> <span class="hlt">bearings</span>, and 28 percent for cylindrical roller <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080001446','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080001446"><span>Reexamination of Ball-Race Conformity Effects on Ball <span class="hlt">Bearing</span> Life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, Erwin V.; Poplawski, Joseph V.; Root, Lawrence E.</p> <p>2007-01-01</p> <p>The analysis in this report considers the life of the ball set as well as the respective lives of the races to reassess the effect of ball-race conformity on ball <span class="hlt">bearing</span> life. The related changes in ball <span class="hlt">bearing</span> life are incorporated in life factors that can be used to modify the <span class="hlt">bearing</span> predicted life using the Lundberg-Palmgren equations and the ANSI/ABMA and ISO Standards. Two simple algebraic relationships were established to calculate life factors LF(sub c) to determine the effect of inner- and outer-race conformity combinations on <span class="hlt">bearing</span> L(sub 10) life for deepgroove and angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span>, respectively. Depending on the <span class="hlt">bearing</span> type and series as well as conformity combinations, the calculated life for deep-groove ball <span class="hlt">bearings</span> can be over 40 percent less than that calculated by the Lundberg-Palmgren equations. For angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span>, the life can vary between +16 and -39 percent from that calculated by the Lundberg-Palmgren equations. Comparing the two ball <span class="hlt">bearing</span> types, the life factors LF(sub c) for the deep-groove <span class="hlt">bearings</span> can be as much as 40 percent lower than that for angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/868269','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/868269"><span>Positive <span class="hlt">contact</span>, self retaining <span class="hlt">bearing</span> seals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Johnson, Bruce H.; Larsen, Lawrence E.; Welch, Edmund F.</p> <p>1992-05-05</p> <p>An ultra-low friction <span class="hlt">bearing</span> including an inner race, an outer race, <span class="hlt">bearing</span> elements engaged between the inner and outer races and a seal between the inner and outer races is disclosed. The seal includes first and second sealing washers. The first washer has an outer diameter greater than an inner diameter of the outer race and an inner diameter greater than the outer diameter of the inner race. The second washer has an inner diameter less than the outer diameter of the inner race and an outer diameter less than the inner diameter of the outer race. The first washer slidably engages the outer race, the second washer slidably engages the inner race and the washers overlap and slidably engage one another. One of the washers snap fits into its respective inner or outer race while the other washer engages a stepped surface of the other of the inner and outer races. The grooved and stepped surface are offset from one another in a longitudinal direction of the races such that the washers are conically loaded thus providing a seal between the inner and outer races sufficient to prevent lubricant and contaminating particles from passing therethrough. The washers are made from a non-metallic semi-flexible low-modulus material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890008254','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890008254"><span>Stress analysis method for clearance-fit joints with <span class="hlt">bearing</span>-bypass loads</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Naik, R. A.; Crews, J. H., Jr.</p> <p>1989-01-01</p> <p>Within a multi-fastener joint, fastener holes may be subjected to the combined effects of <span class="hlt">bearing</span> loads and loads that bypass the hole to be reacted elsewhere in the joint. The analysis of a joint subjected to search combined <span class="hlt">bearing</span> and bypass loads is complicated by the usual clearance between the hole and the fastener. A simple analysis method for such clearance-fit joints subjected to <span class="hlt">bearing</span>-bypass loading has been developed in the present study. It uses an inverse formulation with a linear elastic finite-element analysis. Conditions along the bolt-hole <span class="hlt">contact</span> arc are specified by displacement constraint equations. The present method is simple to apply and can be implemented with most general purpose finite-element programs since it does not use complicated iterative-incremental procedures. The method was used to study the effects of <span class="hlt">bearing</span>-bypass loading on bolt-hole <span class="hlt">contact</span> angles and local stresses. In this study, a rigid, frictionless bolt was used with a plate having the properties of a quasi-isotropic graphite/epoxy laminate. Results showed that the <span class="hlt">contact</span> angle as well as the peak stresses around the hole and their locations were strongly influenced by the ratio of <span class="hlt">bearing</span> and bypass loads. For single <span class="hlt">contact</span>, tension and compression <span class="hlt">bearing</span>-bypass loading had opposite effects on the <span class="hlt">contact</span> angle. For some compressive <span class="hlt">bearing</span>-bypass loads, the hole tended to close on the fastener leading to dual <span class="hlt">contact</span>. It was shown that dual <span class="hlt">contact</span> reduces the stress concentration at the fastener and would, therefore, increase joint strength in compression. The results illustrate the general importance of accounting for bolt-hole clearance and <span class="hlt">contact</span> to accurately compute local bolt-hole stresses for combined <span class="hlt">bearings</span> and bypass loading.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD0643756','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD0643756"><span>FEASIBILITY STUDY OF AIR <span class="hlt">BEARING</span> ROCKET SLED SLIPPERS</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p></p> <p>a simple self-acting type of <span class="hlt">bearing</span> can support a typical monorail rocket sled, without <span class="hlt">contact</span> between the slipper and the rail, at speeds between...slipper <span class="hlt">bearing</span> is capable of preventing slipper-rail <span class="hlt">contact</span> over the entire speed range of typical monorail and dual rail sleds. However, the weight and</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880009549','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880009549"><span>Computer-aided design analysis of 57-mm, angular-<span class="hlt">contact</span>, cryogenic turbopump <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Armstrong, Elizabeth S.; Coe, Harold H.</p> <p>1988-01-01</p> <p>The Space Shuttle main engine high-pressure oxygen turbopumps have not experienced the sevice life required of them. This insufficiency has been due in part to the shortened life of the <span class="hlt">bearings</span>. To improve the life of the existing turbopump <span class="hlt">bearings</span>, an effort is under way to investigate <span class="hlt">bearing</span> modifications that could be retrofitted into the present <span class="hlt">bearing</span> cavity. Several <span class="hlt">bearing</span> parameters were optimized using the computer program SHABERTH, which performs a thermomechanical simulation of a load support system. The computer analysis showed that improved <span class="hlt">bearing</span> performance is feasible if low friction coefficients can be attained. <span class="hlt">Bearing</span> geometries were optimized considering heat generation, equilibrium temperatures, and relative life. Thermal gradients through the <span class="hlt">bearings</span> were found to be lower with liquid lubrication than with solid film lubrication, and a liquid oxygen coolant flowrate of approximately 4.0 kg/s was found to be optimal. This paper describes the analytical modeling used to determine these feasible modifications to improve <span class="hlt">bearing</span> performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840011748','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840011748"><span>First order ball <span class="hlt">bearing</span> kinematics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kingbury, E.</p> <p>1984-01-01</p> <p>Two first order equations are given connecting geometry and internal motions in an angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span>. Total speed, kinematic equivalence, basic speed ratio, and modal speed ratio are defined and discussed; charts are given for the speed ratios covering all <span class="hlt">bearings</span> and all rotational modes. Instances where specific first order assumptions might fail are discussed, and the resulting effects on <span class="hlt">bearing</span> performance reviewed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930000329&hterms=powder+metallurgy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpowder%2Bmetallurgy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930000329&hterms=powder+metallurgy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpowder%2Bmetallurgy"><span>Powder-Metallurgical <span class="hlt">Bearings</span> For Turbopumps</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bhat, B. N.; Humphries, T. S.; Thom, R. L.; Moxson, V.; Friedman, G. I.; Dolan, F. J.; Shipley, R. J.</p> <p>1993-01-01</p> <p><span class="hlt">Bearings</span> fabricated by powder metallurgy developed for use in machines subjected to extremes of temperature, rolling-<span class="hlt">contact</span> cyclic stresses, and oxidizing or otherwise corrosive fluids. <span class="hlt">Bearings</span> also extend operating lives of other machines in which <span class="hlt">bearings</span> required to resist extreme thermal, mechanical, and chemical stresses. One alloy exhibiting outstanding properties was MRC-2001. Resistance to fatigue, stress corrosion cracking, and wear found superior to that of 440C stainless steel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MSSP...96..104W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MSSP...96..104W"><span>New LMI based gain-scheduling control for recovering <span class="hlt">contact</span>-free operation of a magnetically levitated rotor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, M.; Cole, M. O. T.; Keogh, P. S.</p> <p>2017-11-01</p> <p>A new approach for the recovery of <span class="hlt">contact</span>-free levitation of a rotor supported by active magnetic <span class="hlt">bearings</span> (AMB) is assessed through control strategy design, system modelling and experimental verification. The rotor is considered to make <span class="hlt">contact</span> with a touchdown <span class="hlt">bearing</span> (TDB), which may lead to entrapment in a bi-stable nonlinear response. A linear matrix inequality (LMI) based gain-scheduling H∞ control technique is introduced to recover the rotor to a <span class="hlt">contact</span>-free state. The controller formulation involves a time-varying effective stiffness parameter, which can be evaluated in terms of forces transmitted through the TDB. Rather than measuring these forces directly, an observer is introduced with a model of the base structure to transform base acceleration signals using polytopic coordinates for controller <span class="hlt">adjustment</span>. Force transmission to the supporting base structure will occur either through an AMB alone without <span class="hlt">contact</span>, or through the AMB and TDB with <span class="hlt">contact</span> and this must be accounted for in the observer design. The controller is verified experimentally in terms of (a) non-<span class="hlt">contact</span> robust stability and vibration suppression performance; (b) control action for <span class="hlt">contact</span>-free recovery at typical running speeds with various unbalance and TDB misalignment conditions; and (c) coast-down experimental tests. The results demonstrate the effectiveness of the AMB control action whenever it operates within its dynamic load capacity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110000529','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110000529"><span>Interference-Fit Life Factors for Ball <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.</p> <p>2010-01-01</p> <p>The effect of hoop stresses on the rolling-element fatigue life of angular-<span class="hlt">contact</span> and deep-groove ball <span class="hlt">bearings</span> was determined for common inner-ring interference fits at the ABEC-5 tolerance level. The analysis was applied to over 1150 <span class="hlt">bearing</span> configurations and load cases. Hoop stresses were superimposed on the Hertzian principal stresses created by the applied <span class="hlt">bearing</span> load to calculate the inner-race maximum shearing stress. The resulting fatigue life of the <span class="hlt">bearing</span> was recalculated through a series of equations. The reduction in the fatigue life is presented as life factors that are applied to the unfactored <span class="hlt">bearing</span> life. The life factors found in this study ranged from 1.00 (no life reduction)--where there was no net interface pressure--to a worst case of 0.38 (a 62-percent life reduction). For a given interference fit, the reduction in life is different for angular-<span class="hlt">contact</span> and deep-groove ball <span class="hlt">bearings</span>. Interference fits also affect the maximum Hertz stress-life relation. Experimental data of Czyzewski, showing the effect of interference fit on rolling-element fatigue life, were reanalyzed to determine the shear stress-life exponent. The Czyzewski data shear stress-life exponent c equals 8.77, compared with the assumed value of 9. Results are presented as tables and charts of life factors for angular-<span class="hlt">contact</span> and deep-groove ball <span class="hlt">bearings</span> with light, normal, and heavy loads and interference fits ranging from extremely light to extremely heavy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750021356','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750021356"><span>Operating limitations of high speed jet lubricated ball <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, E. V.; Signer, H.; Bamberger, E. N.</p> <p>1975-01-01</p> <p>A parametric study was performed with 120-mm bore angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> having a nominal <span class="hlt">contact</span> angle of 20 degrees. The <span class="hlt">bearings</span> had either an inner- or an outer-race land riding cage, and lubrication was by recirculating oil jets which had either a single or dual orifice. Thrust load, speed, and lubricant flow rate were varied. Test results were compared with those previously reported and obtained from <span class="hlt">bearings</span> of the same design which were under-race lubricated but run under the same conditions. Jet lubricated ball <span class="hlt">bearings</span> were limited to speeds less than 2,500,000 DN, and <span class="hlt">bearings</span> having inner-race land riding cages produced lower temperatures than <span class="hlt">bearings</span> with outer-race land riding cages. For a given lubricant flow rate dual orifice jets produced lower <span class="hlt">bearing</span> temperatures than single orifice jets, but under-race lubrication produced lower <span class="hlt">bearing</span> temperatures under all conditions of operation with no apparent <span class="hlt">bearing</span> speed limitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..202a2098L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..202a2098L"><span>Investigation of the Influence of Shapes-Texture on Surface Deformation of UHMWPE as a <span class="hlt">Bearing</span> Material in Static Normal Load and Rolling <span class="hlt">Contact</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lestari, W. D.; Ismail, R.; Jamari, J.; Bayuseno, A. P.</p> <p>2017-05-01</p> <p>Surface texture is a common method for improving wear properties of a tribo-pair of soft and hard <span class="hlt">bearing</span> material. The reduction of wear rates on the <span class="hlt">contacting</span> surface material is becoming important issues. In the present study, analysis of the <span class="hlt">contact</span> pressure on the flat surface of UHMWPE (Ultra High Molecular Weight Polyethylene) under the static- and rolling motion with the surface of steel ball used the 3D finite element method (FEM) (the ABAQUS software version 6.12). Five shaped-texture models (square, circle, ellipse, triangle, and chevron) were presented on the flat surface for analysis. The normal load of 17, 30 and 50 N was deliberately set-up for static and rolling <span class="hlt">contact</span> analysis. The <span class="hlt">contact</span> pressure was determined to predict the wear behavior of the shaped-texture on the flat surface of UHMWPE. The results have shown that the static normal load yielded the lowest von-Mises stress distribution on the shaped-texture of the ellipse for all values applied a load, while the square shape experienced the highest stress distribution. Under rolling <span class="hlt">contact</span>, however, the increasing load yielded the increasing von Mises stress distribution for the texture with a triangle shape. Moreover, the texture shapes for circle, ellipse, and chevron respectively, may undergo the lowest stress distribution for all load. The wear calculation provided that the circle and square shape may undergo the highest wear rates. Obviously, the surface texture of circle, ellipse, and chevron may experience the lowest wear rates and is potential for use in the surface engineering of <span class="hlt">bearing</span> materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860014468','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860014468"><span><span class="hlt">Bearing</span> tester data compilation, analysis, and reporting and <span class="hlt">bearing</span> math modeling</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1986-01-01</p> <p>A test condition data base was developed for the <span class="hlt">Bearing</span> and Seal Materials Tester (BSMT) program which permits rapid retrieval of test data for trend analysis and evaluation. A model was developed for the Space shuttle Main Engine (SSME) Liquid Oxygen (LOX) turbopump shaft/<span class="hlt">bearing</span> system. The model was used to perform parametric analyses to determine the sensitivity of <span class="hlt">bearing</span> operating characteristics and temperatures to variations in: axial preload, <span class="hlt">contact</span> friction, coolant flow and subcooling, heat transfer coefficients, outer race misalignments, and outer race to isolator clearances. The <span class="hlt">bearing</span> program ADORE (Advanced Dynamics of Rolling Elements) was installed on the UNIVAC 1100/80 computer system and is operational. ADORE is an advanced FORTRAN computer program for the real time simulation of the dynamic performance of rolling <span class="hlt">bearings</span>. A model of the 57 mm turbine-end <span class="hlt">bearing</span> is currently being checked out. Analyses were conducted to estimate flow work energy for several flow diverter configurations and coolant flow rates for the LOX BSMT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910000063&hterms=ren&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dren','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910000063&hterms=ren&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dren"><span>Lubrication Of Nonconformal <span class="hlt">Contacts</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jeng, Yeau-Ren</p> <p>1991-01-01</p> <p>Report discusses advances in knowledge of lubrication of nonconformal <span class="hlt">contacts</span> in <span class="hlt">bearings</span> and other machine elements. Reviews previous developments in theory of lubrication, presents advances in theory of lubrication to determine minimum film thickness, and describes experiments designed to investigate one of regimes of lubrication for ball <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940000464&hterms=Magnet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DMagnet','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940000464&hterms=Magnet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DMagnet"><span>Permanent-Magnet Meissner <span class="hlt">Bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Robertson, Glen A.</p> <p>1994-01-01</p> <p>Permanent-magnet meissner <span class="hlt">bearing</span> features inherently stable, self-centering conical configuration. <span class="hlt">Bearing</span> made stiffer or less stiff by selection of magnets, springs, and spring <span class="hlt">adjustments</span>. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1135721','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1135721"><span>Centrifugally decoupling touchdown <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Post, Richard F</p> <p>2014-06-24</p> <p>Centrifugally decoupling mechanical <span class="hlt">bearing</span> systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures <span class="hlt">contact</span> (or near-<span class="hlt">contact</span>) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical <span class="hlt">contact</span> with the shaft. They still remain, however, in position to act as a touchdown <span class="hlt">bearing</span> in case of abnormally high transverse accelerations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780009446','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780009446"><span><span class="hlt">Bearing</span>, gearing, and lubrication technology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, W. J.</p> <p>1978-01-01</p> <p>Results of selected NASA research programs on rolling-element and fluid-film <span class="hlt">bearings</span>, gears, and elastohydrodynamic lubrication are reported. Advances in rolling-element <span class="hlt">bearing</span> material technology, which have resulted in a significant improvement in fatigue life, and which make possible new applications for rolling <span class="hlt">bearings</span>, are discussed. Research on whirl-resistant, fluid-film <span class="hlt">bearings</span>, suitable for very high-speed applications, is discussed. An improved method for predicting gear pitting life is reported. An improved formula for calculating the thickness of elastohydrodynamic films (the existence of which help to define the operating regime of concentrated <span class="hlt">contact</span> mechanisms such as <span class="hlt">bearings</span>, gears, and cams) is described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730029537&hterms=race&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drace','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730029537&hterms=race&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drace"><span>Analysis of an arched outer-race ball <span class="hlt">bearing</span> considering centrifugal forces.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamrock, B. J.; Anderson, W. J.</p> <p>1972-01-01</p> <p>Thrust-load analysis of a 150-mm angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span>, taking into account centrifugal forces but omitting gyroscopics, elastohydrodynamics, and thermal effects. A Newton-Raphson method of iteration is used to evaluate the radial and axial projection of the distance between the ball center and the outer raceway groove curvature center. Fatigue life of the <span class="hlt">bearing</span> is evaluated. Results for life, <span class="hlt">contact</span> loads, and angles are given for a conventional <span class="hlt">bearing</span> and two arched <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040171628','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040171628"><span>Conical Magnetic <span class="hlt">Bearing</span> Development and Magnetic <span class="hlt">Bearing</span> Testing for Extreme Temperature Environments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keith, Theo G., Jr.; Jansen, Mark</p> <p>2004-01-01</p> <p>The main proposed research of this grant were: to design a high-temperature, conical magnetic <span class="hlt">bearing</span> facility, to test the high-temperature, radial magnetic <span class="hlt">bearing</span> facility to higher speeds, to investigate different backup <span class="hlt">bearing</span> designs and materials, to retrofit the high-temperature test facility with a magnetic thrust <span class="hlt">bearing</span>, to evaluate test <span class="hlt">bearings</span> at various conditions, and test several lubricants using a spiral orbit tribometer. A high-temperature, conical magnetic <span class="hlt">bearing</span> facility has been fully developed using Solidworks. The facility can reuse many of the parts of the current high-temperature, radial magnetic <span class="hlt">bearing</span>, helping to reduce overall build costs. The facility has the ability to measure <span class="hlt">bearing</span> force capacity in the X, Y, and Z directions through a novel <span class="hlt">bearing</span> mounting design. The high temperature coils and laminations, a main component of the facility, are based upon the current radial design and can be fabricated at Texas A&M University. The coil design was highly successful in the radial magnetic <span class="hlt">bearing</span>. Vendors were <span class="hlt">contacted</span> about fabrication of the high temperature lamination stack. Stress analysis was done on the laminations. Some of the components were procured, but due to budget cuts, the facility build up was stopped.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020081123','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020081123"><span>Transient Vibration Prediction for Rotors on Ball <span class="hlt">Bearings</span> Using Load-dependent Non-linear <span class="hlt">Bearing</span> Stiffness</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fleming, David P.; Poplawski, J. V.</p> <p>2002-01-01</p> <p>Rolling-element <span class="hlt">bearing</span> forces vary nonlinearly with <span class="hlt">bearing</span> deflection. Thus an accurate rotordynamic transient analysis requires <span class="hlt">bearing</span> forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate <span class="hlt">bearing</span> transient forces (accounting for non-linear speed and load dependent <span class="hlt">bearing</span> stiffness) as compared to conventional use of average rolling-element <span class="hlt">bearing</span> stiffness. <span class="hlt">Bearing</span> forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller <span class="hlt">Bearing</span> Analysis - Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running 5 degree-of-freedom computer code able to calculate high speed rolling-element <span class="hlt">bearing</span> load-displacement data for radial and angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span> and also for cylindrical and tapered roller beatings. Results show that use of nonlinear <span class="hlt">bearing</span> characteristics is essential for accurate prediction of rotordynamic behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950015275','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950015275"><span>Modeling of rolling element <span class="hlt">bearing</span> mechanics. Computer program user's manual</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greenhill, Lyn M.; Merchant, David H.</p> <p>1994-01-01</p> <p>This report provides the user's manual for the Rolling Element <span class="hlt">Bearing</span> Analysis System (REBANS) analysis code which determines the quasistatic response to external loads or displacement of three types of high-speed rolling element <span class="hlt">bearings</span>: angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span>, duplex angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span>, and cylindrical roller <span class="hlt">bearings</span>. The model includes the defects of <span class="hlt">bearing</span> ring and support structure flexibility. It is comprised of two main programs: the Preprocessor for <span class="hlt">Bearing</span> Analysis (PREBAN) which creates the input files for the main analysis program, and Flexibility Enhanced Rolling Element <span class="hlt">Bearing</span> Analysis (FEREBA), the main analysis program. This report addresses input instructions for and features of the computer codes. A companion report addresses the theoretical basis for the computer codes. REBANS extends the capabilities of the SHABERTH (Shaft and <span class="hlt">Bearing</span> Thermal Analysis) code to include race and housing flexibility, including such effects as dead band and preload springs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012MSSP...29...19K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012MSSP...29...19K"><span><span class="hlt">Contact</span> dynamic phenomena in rotating machines: Active/passive considerations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keogh, Patrick S.</p> <p>2012-05-01</p> <p>There are machine operating regimes in which rotor/stator interactions may lead to problematic rotor dynamic behavior. For example, dynamic heat sources arising from seals, <span class="hlt">bearings</span> and other rubbing stator components may cause rotor thermal bend instability. In active magnetic <span class="hlt">bearing</span> (AMB) systems, the rotor may experience forward and backward whirl rubs with touchdown <span class="hlt">bearings</span> (TDBs). In abnormal cases, rotor transient and bounce interactions with such <span class="hlt">bearings</span> may involve highly localized and short duration <span class="hlt">contacts</span>. This paper discusses certain <span class="hlt">contact</span> phenomena that may occur in passive and active systems. For example, the rub induced spiral behavior arises from a combination of unbalance and a thermal input that moves slowly around the rotor, typically in passive rotor-<span class="hlt">bearing</span> systems. However, the instability can be regarded as if arising from a closed-loop feedback system. Hence it is possible to analyze the phenomenon using techniques that have been developed for active control systems. Rotors levitated by AMBs are truly active, but there are fundamental issues that may arise when <span class="hlt">contact</span> with TDBs occurs. AMB control and <span class="hlt">contact</span> interactions are discussed together with the benefits for making the TDB an active element. The reason for this lies in the potential ability to control the <span class="hlt">contact</span> dynamics and associated mechanical and thermal stresses. A prototype system is described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940017107','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940017107"><span>Detailed study of oxidation/wear mechanism in lox turbopump <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chase, T. J.; Mccarty, J. P.</p> <p>1993-01-01</p> <p>Wear of 440C angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span> of the phase 2 high pressure oxygen turbopump (HPOTP) of the space shuttle main engine (SSME) has been studied by means of various advanced nondestructive techniques (NDT) and modeled with reference to all known material, design, and operation variables. Three modes dominating the wear scenario were found to be the adhesive/sheer peeling (ASP), oxidation, and abrasion. <span class="hlt">Bearing</span> wear was modeled in terms of the three modes. Lacking a comprehensive theory of rolling <span class="hlt">contact</span> wear to date, each mode is modeled after well-established theories of sliding wear, while sliding velocity and distance are related to microsliding in ball-to-ring <span class="hlt">contacts</span>. Microsliding, stress, temperature, and other <span class="hlt">contact</span> variables are evaluated with analytical software packages of SHABERTH(TM)/SINDA(TM) and ADORE(TM). Empirical constants for the models are derived from NIST experiments by applying the models to the NIST wear data. The <span class="hlt">bearing</span> wear model so established precisely predicts quite well the average ball wear rate for the HPOTP <span class="hlt">bearings</span>. The wear rate has been statistically determined for the entire population of flight and development <span class="hlt">bearings</span> based on Rocketdyne records to date. Numerous illustrations are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910020289','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910020289"><span><span class="hlt">Bearing</span> Tester Data Compilation Analysis, and Reporting and <span class="hlt">Bearing</span> Math Modeling</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1985-01-01</p> <p>The magnitude and direction of fluid induced torques and forces on the 57 mm <span class="hlt">bearing</span> cage is considered to be a contributing factor in possible cage instabilities that can produce intermittent high heating in the <span class="hlt">bearing</span>. Analyses of the fluid forces and torques are presented. Heat generated by viscous fluid work was estimated for two flow diverter configurations and a coolant flow of 10 lbs/sec to support the thermal evaluation of the LOX <span class="hlt">Bearing</span> Materials Tester. Results of the analysis of the LOX turbopump turbine end <span class="hlt">bearings</span> are discussed. Coolant velocities for the no. 4 LOX turbopump turbine end <span class="hlt">bearings</span> were estimated as a function of shaft speed and coolant flow rate. <span class="hlt">Contact</span> angles and track width data were developed for the 57 mm <span class="hlt">bearing</span> as functions of shaft speed, and axial and radial loads. The Advanced Dynamics of Rolling Elements (ADORE) computer program was installed on the MSFC UNIVAC 1100 and a test case successfully run. Both the text output and the plotting output were verified. The <span class="hlt">Bearing</span> Seal and Materials Tester - Test Condition Data Base was developed. The parametric analysis of the operating characteristics of the LOX turbopump pump end <span class="hlt">bearing</span> using the 45 mm <span class="hlt">bearing</span> thermal model was begun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840016978','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840016978"><span><span class="hlt">Bearing</span> tester data compilation, analysis and reporting and <span class="hlt">bearing</span> math modeling, volume 1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marshall, D. D.; Montgomery, E. E.; New, L. S.; Stone, M. A.; Tiller, B. K.</p> <p>1984-01-01</p> <p>Thermal and mechanical models of high speed angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span> operating in LOX and LN2 were developed and verified with limited test data in an effort to further understand the parameters that determine or effect the SSME turbopump <span class="hlt">bearing</span> operational characteristics and service life. The SHABERTH <span class="hlt">bearing</span> analysis program which was adapted to evaluate shaft <span class="hlt">bearing</span> systems in cryogenics is not capable of accommodating varying thermal properties and two phase flow. A <span class="hlt">bearing</span> model with this capability was developed using the SINDA thermal analyzer. Iteration between the SHABERTH and the SINDA models enable the establishment of preliminary bounds for stable operation in LN2. These limits were established in terms of fluid flow, fluid inlet temperature, and axial load for a shaft speed of 30,000 RPM.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA285311','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA285311"><span>Development of a Ceramic Rolling <span class="hlt">Contact</span> <span class="hlt">Bearing</span> for High Temperature Use</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1961-07-11</p> <p>operation) suspended in a gas stream was suprlied sufficient hardness, stability, and strength in through a tube in the <span class="hlt">bearing</span> housing and was ex- an...and microfine MOS2, dried and screened, was supplied radial <span class="hlt">bearing</span> mounting surfaces was less than to the <span class="hlt">bearing</span> at an average rate of about 0.16...L.UBRICANT B ATMOSPHERE I".LlT TUBE DRILL TS5.ULAiT. INT. SEAL B TAP ONE KOLE I*G1-TEtMPjRAIUNE AS 45- TO SHEAR PIN SLOT FOR TTREAO END FLOW FOR HEATINM OP</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25775930','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25775930"><span>Introgressive hybridization: brown <span class="hlt">bears</span> as vectors for polar <span class="hlt">bear</span> alleles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hailer, Frank</p> <p>2015-03-01</p> <p>The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar <span class="hlt">bears</span>, eight brown <span class="hlt">bears</span> and one American black <span class="hlt">bear</span>. Polar <span class="hlt">bear</span> alleles are found to be introgressed into brown <span class="hlt">bears</span> not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene <span class="hlt">contact</span> zone. Compared to a previous study on the ABC Island population in which an Alaskan brown <span class="hlt">bear</span> served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown <span class="hlt">bear</span> as admixture baseline. This approach reveals that brown <span class="hlt">bears</span> have been impacted by introgression from polar <span class="hlt">bears</span> to a larger extent (up to 8.8% of their genome), than previously known, including the <span class="hlt">bear</span> that had previously served as admixture baseline. No evidence for introgression of brown <span class="hlt">bear</span> into polar <span class="hlt">bear</span> is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown <span class="hlt">bear</span> evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. © 2015 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1260343','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1260343"><span>Gearbox Reliability Collaborative Investigation of High-Speed-Shaft <span class="hlt">Bearing</span> Loads</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Keller, Jonathan; Guo, Yi</p> <p>2016-06-01</p> <p>The loads and <span class="hlt">contact</span> stresses in the <span class="hlt">bearings</span> of the high speed shaft section of the Gearbox Reliability Collaborative gearbox are examined in this paper. The loads were measured though strain gauges installed on the <span class="hlt">bearing</span> outer races during dynamometer testing of the gearbox. Loads and stresses were also predicted with a simple analytical model and higher-fidelity commercial models. The experimental data compared favorably to each model, and <span class="hlt">bearing</span> stresses were below thresholds for <span class="hlt">contact</span> fatigue and axial cracking.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002PhDT........34F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002PhDT........34F"><span>"Null-E" magnetic <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Filatov, Alexei Vladimirovich</p> <p>2002-09-01</p> <p>Using electromagnetic forces to suspend rotating objects (rotors) without mechanical <span class="hlt">contact</span> is often an appealing technical solution. Magnetic suspensions are typically required to have adequate load capacity and stiffness, and low rotational loss. Other desired features include low price, high reliability and manufacturability. With recent advances in permanent-magnet materials, the required forces can often be obtained by simply using the interaction between permanent magnets. While a magnetic <span class="hlt">bearing</span> based entirely on permanent magnets could be expected to be inexpensive, reliable and easy to manufacture, a fundamental physical principle known as Earnshaw's theorem maintains that this type of suspension cannot be statically stable. Therefore, some other physical mechanisms must be included. One such mechanism employs the interaction between a conductor and a nonuniform magnetic field in relative motion. Its advantages include simplicity, reliability, wide range of operating temperature and system autonomy (no external wiring and power supplies are required). The disadvantages of the earlier embodiments were high rotational loss, low stiffness and load capacity. This dissertation proposes a novel type of magnetic <span class="hlt">bearing</span> stabilized by the field-conductor interaction. One of the advantages of this <span class="hlt">bearing</span> is that no electric field, E, develops in the conductor during the rotor rotation when the system is in no-load equilibrium. Because of this we refer to it as the Null-E <span class="hlt">Bearing</span>. Null-E <span class="hlt">Bearings</span> have potential for lower rotational loss and higher load capacity and stiffness than other <span class="hlt">bearings</span> utilizing the field-conductor interaction. Their performance is highly insensitive to manufacturing inaccuracies. The Null-E <span class="hlt">Bearing</span> in its basic form can be augmented with supplementary electronics to improve its performance. Depending on the degree of the electronics involvement, a variety of magnetic <span class="hlt">bearings</span> can be developed ranging from a completely passive to an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993asee.nasa.....E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993asee.nasa.....E"><span>Foil <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elrod, David A.</p> <p>1993-11-01</p> <p>The rolling element <span class="hlt">bearings</span> (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding <span class="hlt">contact</span> within the <span class="hlt">bearing</span> has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball <span class="hlt">bearings</span> limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil <span class="hlt">bearing</span> (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of <span class="hlt">bearing</span> stiffness and damping coefficients. The two basic types of CFB are the tension-dominated <span class="hlt">bearing</span> and the bending-dominated <span class="hlt">bearing</span>. Many investigators have analyzed and measured characteristics of tension-dominated foil <span class="hlt">bearings</span>, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25995583','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25995583"><span>The effect of weight-<span class="hlt">bearing</span> exercise and non-weight-<span class="hlt">bearing</span> exercise on gait in rats with sciatic nerve crush injury.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Ki-Hyun; Hwangbo, Gak; Kim, Seong-Gil</p> <p>2015-04-01</p> <p>[Purpose] The purpose of this study was to access the effect of weight <span class="hlt">bearing</span> exercise (treadmill exercise) and non-weight-<span class="hlt">bearing</span> exercise (swimming exercise) on gait in the recovery process after a sciatic nerve crush injury. [Subjects and Methods] Rats were randomly divided into a swimming group (n=3) with non-weight-<span class="hlt">bearing</span> exercise after a sciatic nerve crush and a treadmill group (n=3) with weight <span class="hlt">bearing</span> exercise after a sciatic nerve crush. Dartfish is a program that can analyze and interpret motion through video images. The knee lateral epicondyle, lateral malleolus, and metatarsophalangeal joint of the fifth toe were marked by black dots before recording. [Results] There were significant differences in TOK (knee angle toe off) and ICK (knee angle at initial <span class="hlt">contact</span>) in the swimming group and in TOK, ICA (ankle angle at initial <span class="hlt">contact</span>), and ICK in the treadmill group. In comparison between groups, there were significant differences in TOA (ankle angle in toe off) and ICA at the 7th day. [Conclusion] There was no difference between weight <span class="hlt">bearing</span> and non-weight-<span class="hlt">bearing</span> exercise in sciatic nerve damage, and both exercises accelerated the recovery process in this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160000341','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160000341"><span>Effect of Roller Geometry on Roller <span class="hlt">Bearing</span> Load-Life Relation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.</p> <p>2015-01-01</p> <p>Cylindrical roller <span class="hlt">bearings</span> typically employ roller profile modification to equalize load distribution, minimize stress concentration at roller ends and allow for a small amount of misalignment. The 1947 Lundberg-Palmgren analysis reported an inverse fourth power relation between load and life for roller <span class="hlt">bearings</span> with line <span class="hlt">contact</span>. In 1952, Lundberg and Palmgren changed their load-life exponent to 10/3 for roller <span class="hlt">bearings</span>, assuming mixed line and point <span class="hlt">contact</span>. The effect of roller-crown profile was reanalyzed in this paper to determine the actual load-life relation for modified roller profiles. For uncrowned rollers (line <span class="hlt">contact</span>), the load-life exponent is p = 4, in agreement with the 1947 Lundberg-Palmgren value but crowning reduces the value of the exponent, p. The lives of modern roller <span class="hlt">bearings</span> made from vacuum-processed steels significantly exceed those predicted by the Lundberg-Palmgren theory. The Zaretsky rolling-element <span class="hlt">bearing</span> life model of 1996 produces a load-life exponent of p = 5 for flat rollers, which is more consistent with test data. For the Zaretsky model with fully crowned rollers p = 4.3. For an aerospace profile and chamfered rollers, p = 4.6. Using the 1952 Lundberg-Palmgren value p = 10/3, the value incorporated in ANSI/ABMA and ISO <span class="hlt">bearing</span> standards, can create significant life calculation errors for roller <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..281a2038Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..281a2038Z"><span>Working Performance Analysis of Rolling <span class="hlt">Bearings</span> Used in Mining Electric Excavator Crowd Reducer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y. H.; Hou, G.; Chen, G.; Liang, J. F.; Zheng, Y. M.</p> <p>2017-12-01</p> <p>Refer to the statistical load data of digging process, on the basis of simulation analysis of crowd reducer system dynamics, the working performance simulation analysis of rolling <span class="hlt">bearings</span> used in crowd reducer of large mining electric excavator is completed. The contents of simulation analysis include analysis of internal load distribution, rolling elements <span class="hlt">contact</span> stresses and rolling <span class="hlt">bearing</span> fatigue life. The internal load characteristics of rolling elements in cylindrical roller <span class="hlt">bearings</span> are obtained. The results of this study identified that all rolling <span class="hlt">bearings</span> satisfy the requirements of <span class="hlt">contact</span> strength and fatigue life. The rationality of <span class="hlt">bearings</span> selection and arrangement is also verified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/866723','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/866723"><span>Precision <span class="hlt">adjustable</span> stage</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Cutburth, Ronald W.; Silva, Leonard L.</p> <p>1988-01-01</p> <p>An improved mounting stage of the type used for the detection of laser beams is disclosed. A stage center block is mounted on each of two opposite sides by a pair of spaced ball <span class="hlt">bearing</span> tracks which provide stability as well as simplicity. The use of the spaced ball <span class="hlt">bearing</span> pairs in conjunction with an <span class="hlt">adjustment</span> screw which also provides support eliminates extraneous stabilization components and permits maximization of the area of the center block laser transmission hole.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..227a2071K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..227a2071K"><span>Effects of friction reduction of micro-patterned array of rough slider <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, M.; Lee, D. W.; Jeong, J. H.; Chung, W. S.; Park, J. K.</p> <p>2017-08-01</p> <p>Complex micro-scale patterns have attracted interest because of the functionality that can be created using this type of patterning. This study evaluates the frictional reduction effects of various micro patterns on a slider <span class="hlt">bearing</span> surface which is operating under mixed lubrication. Due to the rapid growth of <span class="hlt">contact</span> area under mixed lubrication, it has become important to study the phenomenon of asperity <span class="hlt">contact</span> in <span class="hlt">bearings</span> with a heavy load. New analysis using the modified Reynolds equation with both the average flow model and the <span class="hlt">contact</span> model of asperities is conducted for the rough slider <span class="hlt">bearing</span>. A numerical analysis is performed to determine the effects of surface roughness on a lubricated <span class="hlt">bearing</span>. Several dented patterns such as, dot pattern, dashed line patterns are used to evaluate frictional reduction effects. To verify the analytical results, friction test for the micro-patterned samples are performed. From comparing the frictional reduction effects of patterned arrays, the design of them can control the frictional loss of <span class="hlt">bearings</span>. Our results showed that the design of pattern array on the <span class="hlt">bearing</span> surface was important to the friction reduction of <span class="hlt">bearings</span>. To reduce frictional loss, the longitudinal direction of them was better than the transverse direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140004920','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140004920"><span>Resilient and Corrosion-Proof Rolling Element <span class="hlt">Bearings</span> Made from Superelastic Ni-Ti Alloys for Aerospace</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dellacorte, Christopher</p> <p>2014-01-01</p> <p>Mechanical components (<span class="hlt">bearings</span>, gears, mechanisms) typically utilize hardened construction materials to minimize wear and attain long life. In such components, loaded <span class="hlt">contact</span> points (e.g., meshing gear teeth, <span class="hlt">bearing</span> balls-raceway <span class="hlt">contacts</span>) experience high <span class="hlt">contact</span> stresses. The combination of high hardness and high elastic modulus often leads to damaging <span class="hlt">contact</span> stress and denting, particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this webinar, Dr. DellaCorte will introduce the results of a research project that employs a superelastic alloy, Ni-Ti for rolling element <span class="hlt">bearing</span> applications. <span class="hlt">Bearings</span> and components made from such alloys can alleviate many problems encountered in advanced aerospace applications and may solve many terrestrial applications as well</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110014764','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110014764"><span>Ball <span class="hlt">Bearings</span> Equipped for In Situ Lubrication on Demand</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marchetti, Mario; Jones, William R., Jr.; Pepper, Stephen V.; Jansen, Mark; Predmore, Roamer</p> <p>2005-01-01</p> <p>In situ systems that provide fresh lubricants to ball/race <span class="hlt">contacts</span> on demand have been developed to prolong the operational lives of ball <span class="hlt">bearings</span>. These systems were originally intended to be incorporated into ball <span class="hlt">bearings</span> in mechanisms that are required to operate in outer space for years, in conditions in which lubricants tend to deteriorate and/or evaporate. These systems may also be useful for similarly prolonging <span class="hlt">bearing</span> lifetimes on Earth. Reservoirs have been among the means used previously to resupply lubricants. Lubricant- resupply reservoirs are bulky and add complexity to <span class="hlt">bearing</span> assemblies. In addition, such a reservoir cannot be turned on or off as needed: it supplies lubricant continuously, often leading to an excess of lubricant in the <span class="hlt">bearing</span>. A lubricator of the present type includes a porous ring cartridge attached to the inner or the outer ring of a ball <span class="hlt">bearing</span> (see Figure 1). Oil is stored in the porous cartridge and is released by heating the cartridge: Because the thermal expansion of the oil exceeds that of the cartridge, heating causes the ejection of some oil. A metal film can be deposited on a face of the cartridge to serve as an electrical-resistance heater. The heater can be activated in response to a measured increase in torque that signals depletion of oil from the <span class="hlt">bearing</span>/race <span class="hlt">contacts</span>. Because the oil has low surface tension and readily wets the <span class="hlt">bearing</span>-ring material, it spreads over the <span class="hlt">bearing</span> ring and eventually reaches the ball/race <span class="hlt">contacts</span>. The Marangoni effect (a surface-tension gradient associated with a temperature gradient) is utilized to enhance the desired transfer of lubricant to the ball/race <span class="hlt">contacts</span> during heating. For a test, a ball <span class="hlt">bearing</span> designed for use at low speed was assembled without lubricant and equipped with a porous-ring lubricator, the resistance heater of which consumed a power of less than 1 W when triggered on by a torque-measuring device. In the test, a load of 20 lb (.89 N) was applied and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840018974','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840018974"><span>Spin analysis of concentrated traction <span class="hlt">contacts</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Loewenthal, S. H.</p> <p>1983-01-01</p> <p>Spin, the result of a mismatch in <span class="hlt">contact</span> radii on either side of the point of rolling, has a detrimental effect on traction <span class="hlt">contact</span> performance. It occurs in concentrated <span class="hlt">contacts</span> having conical or contoured rolling elements, such as those in traction drives or angular <span class="hlt">contact</span> <span class="hlt">bearings</span>, and is responsible for an increase in <span class="hlt">contact</span> heating and power loss. The kinematics of spin producing <span class="hlt">contact</span> geometries and the subsequent effect on traction and power loss are investigated. The influence of lubricant traction characteristics and <span class="hlt">contact</span> geometries that minimize spin are also addressed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1888787','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1888787"><span>Joint <span class="hlt">Contact</span> Stress</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Brand, Richard A</p> <p>2005-01-01</p> <p>A joint's normal mechanical history contributes to the maintenance of articular cartilage and underlying bone. Loading facilitates the flow of nutrients into cartilage and waste products away, and additionally provides the mechanical signals essential for normal cell and tissue maintenance. Deleteriously low or high <span class="hlt">contact</span> stresses have been presumed to result in joint deterioration, and particular aspects of the mechanical environment may facilitate repair of damaged cartilage. For decades, investigators have explored static joint <span class="hlt">contact</span> stresses (under some more or less arbitrary condition) as a surrogate of the relevant mechanical history. <span class="hlt">Contact</span> stresses have been estimated in vitro in many joints and in a number of species, although only rarely in vivo. Despite a number of widely varying techniques (and spatial resolutions) to measure these <span class="hlt">contact</span> stresses, reported ranges of static peak normal stresses are relatively similar from joint to joint across species, and in the range of 0.5 to 5.0 MPa. This suggests vertebrate diarthrodial joints have evolved to achieve similar mechanical design criteria. Available evidence also suggests some disorders of cartilage deterioration are associated with somewhat higher peak pressures ranging from 1-20 MPa, but overlapping the range of normal pressures. Some evidence and considerable logic suggests static <span class="hlt">contact</span> stresses per se do not predict cartilage responses, but rather temporal aspects of the <span class="hlt">contact</span> stress history. Static <span class="hlt">contact</span> stresses may therefore not be a reasonable surrogate for biomechanical studies. Rather, temporal and spatial aspects of the loading history undoubtedly induce beneficial and deleterious biological responses. Finally, since all articular cartilage experiences similar stresses, the concept of a "weight-<span class="hlt">bearing</span>" versus a "non-weight-<span class="hlt">bearing</span>" joint seems flawed, and should be abandoned. PMID:16089079</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100019595','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100019595"><span>Ceramic Rail-Race Ball <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Balzer, Mark A.; Mungas, Greg S.; Peters, Gregory H.</p> <p>2010-01-01</p> <p>Non-lubricated ball <span class="hlt">bearings</span> featuring rail races have been proposed for use in mechanisms that are required to function in the presence of mineral dust particles in very low-pressure, dry environments with extended life. Like a conventional ball <span class="hlt">bearing</span>, the proposed <span class="hlt">bearing</span> would include an inner and an outer ring separated by balls in rolling <span class="hlt">contact</span> with the races. However, unlike a conventional ball <span class="hlt">bearing</span>, the balls would not roll in semi-circular or gothic arch race grooves in the rings: instead, the races would be shaped to form two or more rails (see figure). During operation, the motion of the balls would push dust particles into the spaces between the rails where the particles could not generate rolling resistance for the balls</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.......134M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.......134M"><span>Analytical and experimental investigation of microstructural alterations in <span class="hlt">bearing</span> steel in rolling <span class="hlt">contact</span> fatigue</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mobasher Moghaddam, Sina</p> <p></p> <p>Rolling <span class="hlt">Contact</span> Fatigue (RCF) is one the most common failure modes in <span class="hlt">bearings</span>. RCF is usually associated with particular microstructural alterations. Such alterations (i.e. white etching cracks, butterflies, etc.) which lead to RCF failure are known to be among the most concerning matters to <span class="hlt">bearing</span> industry. In the current work, an analytical as well as experimental approaches are used to investigate "butterfly wing" formation, crack initiation and propagation from inclusions. A new damage evolution equation coupled with a FE model is employed to account for the effect of mean stresses and alternating stresses simultaneously to investigate butterfly formation. The proposed damage evolution law matches experimentally observed butterfly orientation, shape, and size successfully. The model is used to obtain S-N results for butterfly formation at different Hertzian load levels. The results corroborate well with the experimental data available in the open literature. The model is used to predict debonding at the inclusion/matrix interface and the most vulnerable regions for crack initiation on butterfly/matrix interface. A new variable called butterfly formation index (BFI) is introduced to manifest the dependence of wing formation on depth. The value of critical damage inside the butterfly wings was obtained experimentally and was then used to simulate damage evolution. Voronoi tessellation was used to develop the FEM domains to capture the effect of microstructural randomness on butterfly wing formation, crack initiation and propagation. Then, the effects of different inclusion characteristics such as size, depth, and stiffness on RCF life are studied. The results show that stiffness of an inclusion and its location has a significant effect on the RCF life: stiffer inclusions and inclusions located at the depth of maximum shear stress reversal are more detrimental to the RCF life. Stress concentrations are not significantly affected by inclusion size for the cases</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750004258','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750004258"><span>Operating characteristics of 120-millimeter-bore ball <span class="hlt">bearings</span> at 3 million DN</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, E. V.; Bamberger, E. N.; Signer, H.</p> <p>1974-01-01</p> <p>A parametric study was performed with split inner-race 120-mm-bore angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> at a speed of 25,000 rpm (3 million DN) at initial <span class="hlt">contact</span> angles of 20 deg and 24 deg. Provisions were made for outer- and inner-race cooling and for injection of lubricant into the <span class="hlt">bearing</span> through a number of radial holes in the split inner-race of the <span class="hlt">bearing</span>. Oil flow and coolant rate to the <span class="hlt">bearing</span> was controlled and varied for a total up to approximately 3.2 gal/min. <span class="hlt">Bearing</span> temperature was found to decrease as the total lubricant flow to the <span class="hlt">bearing</span> increased. However, at intermediate flow rates temperature began to increase with increasing flow. Power consumption increased with increasing flow rate. <span class="hlt">Bearing</span> operating temperature, differences in temperatures between the inner and outer races, and <span class="hlt">bearing</span> power consumption can be tuned to any desirable operating requirement. Cage speed increased by not more than 2 percent with increasing oil flow to the inner race.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890013541','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890013541"><span>Incorporating general race and housing flexibility and deadband in rolling element <span class="hlt">bearing</span> analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, R. R.; Vallance, C. S.</p> <p>1989-01-01</p> <p>Methods for including the effects of general race and housing compliance and outer race-to-housing deadband (clearance) in rolling element <span class="hlt">bearing</span> mechanics analysis is presented. It is shown that these effects can cause significant changes in <span class="hlt">bearing</span> stiffness characteristics, which are of major importance in rotordynamic response of turbomachinery and other rotating systems. Preloading analysis is demonstrated with the finite element/<span class="hlt">contact</span> mechanics hybrid method applied to a 45 mm angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880012103','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880012103"><span>Two gimbal <span class="hlt">bearing</span> case studies: Some lessons learned</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Loewenthal, Stuart H.</p> <p>1988-01-01</p> <p>Two troublesome, torque related problems associated with gimbal actuators are discussed. Large, thin section angular <span class="hlt">contact</span> <span class="hlt">bearings</span> can have a surprisingly high torque sensitivity to radial thermal gradients. A predictive thermal-mechanical <span class="hlt">bearing</span> analysis, as described, was helpful in establishing a safe temperature operating envelope. In the second example, end-of-travel torque limits of an oscillatory gimbal <span class="hlt">bearing</span> appoached motor stall during limit cycling life tests. <span class="hlt">Bearing</span> modifications required to restore acceptable torque performance are described. The lessons learned from these case studies should benefit designers of precision gimbals where singular <span class="hlt">bearing</span> torque related problems are not uncommon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940023411','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940023411"><span>Mechanically fastened composite laminates subjected to combined <span class="hlt">bearing</span>-bypass and shear loading</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Madenci, Erdogan</p> <p>1993-01-01</p> <p>Bolts and rivets provide a means of load transfer in the construction of aircraft. However, they give rise to stress concentrations and are often the source and location of static and fatigue failures. Furthermore, fastener holes are prone to cracks during take-off and landing. These cracks present the most common origin of structural failures in aircraft. Therefore, accurate determination of the <span class="hlt">contact</span> stresses associated with such loaded holes in mechanically fastened joints is essential to reliable strength evaluation and failure prediction. As the laminate is subjected to loading, the <span class="hlt">contact</span> region, whose extent is not known, develops between the fastener and the hole boundary through this <span class="hlt">contact</span> region, which consists of slip and no-slip zones due to friction. The presence of the unknown <span class="hlt">contact</span> stress distribution over the <span class="hlt">contact</span> region between the pin and the composite laminate, material anisotropy, friction between the pin and the laminate, pin-hole clearance, combined <span class="hlt">bearing</span>-bypass and shear loading, and finite geometry of the laminate result in a complex non-linear problem. In the case of <span class="hlt">bearing</span>-bypass loading in compression, this non-linear problem is further complicated by the presence of dual <span class="hlt">contact</span> regions. Previous research concerning the analysis of mechanical joints subjected to combined <span class="hlt">bearing</span>-bypass and shear loading is non-existent. In the case of <span class="hlt">bearing</span>-bypass loading only, except for the study conducted by Naik and Crews (1991), others employed the concept of superposition which is not valid for this non-linear problem. Naik and Crews applied a linear finite element analysis with conditions along the pin-hole <span class="hlt">contact</span> region specified as displacement constraint equations. The major shortcoming of this method is that the variation of the contract region as a function of the applied load should be known a priori. Also, their analysis is limited to symmetric geometry and material systems, and frictionless boundary conditions. Since the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890000318&hterms=text+historical&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtext%2Bhistorical','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890000318&hterms=text+historical&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtext%2Bhistorical"><span>Ceramic <span class="hlt">Bearings</span> For Gas-Turbine Engines</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, Erwin V.</p> <p>1989-01-01</p> <p>Report reviews data from three decades of research on <span class="hlt">bearings</span> containing rolling elements and possibly other components made of ceramics. Ceramic <span class="hlt">bearings</span> attractive for use in gas-turbine engines because ceramics generally retain strengths and resistances to corrosion over range of temperatures greater than typical steels used in rolling-element <span class="hlt">bearings</span>. Text begins with brief description of historical developments in field. Followed by discussion of effects of <span class="hlt">contact</span> stress on fatigue life of rolling element. Supplemented by figures and tables giving data on fatigue lives of rolling elements made of various materials. Analyzes data on effects of temperature and speed on fatigue lives for several materials and operating conditions. Followed by discussion of related topic of generation of heat in <span class="hlt">bearings</span>, with consideration of effects of <span class="hlt">bearing</span> materials, lubrication, speeds, and loads.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4229748','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/4229748"><span>SLIT <span class="hlt">ADJUSTMENT</span> CLAMP</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>McKenzie, K.R.</p> <p>1959-07-01</p> <p>An electrode support which permits accurate alignment and <span class="hlt">adjustment</span> of the electrode in a plurality of planes and about a plurality of axes in a calutron is described. The support will align the slits in the electrode with the slits of an ionizing chamber so as to provide for the egress of ions. The support comprises an insulator, a leveling plate carried by the insulator and having diametrically opposed attaching screws screwed to the plate and the insulator and diametrically opposed <span class="hlt">adjusting</span> screws for <span class="hlt">bearing</span> against the insulator, and an electrode associated with the plate for <span class="hlt">adjustment</span> therewith.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100039314','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100039314"><span>Experimental Methodology for Determining Turbomachinery Blade Damping Using Magnetic <span class="hlt">Bearing</span> Excitation and Non-<span class="hlt">Contacting</span> Optical Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Provenza, Andrew J.; Duffy, Kirsten P.</p> <p>2010-01-01</p> <p>Experiments to determine the effects of turbomachinery fan blade damping concepts such as passively shunted piezoelectric materials on blade response are ongoing at the NASA Glenn Research Center. A vertical rotor is suspended and excited with active magnetic <span class="hlt">bearings</span> (AMBs) usually in a vacuum chamber to eliminate aerodynamic forces. Electromagnetic rotor excitation is superimposed onto rotor PD-controlled support and can be fixed to either a stationary or rotating frame of reference. The rotor speed is controlled with an air turbine system. Blade vibrations are measured using optical probes as part of a Non-<span class="hlt">Contacting</span> Stress Measurement System (NSMS). Damping is calculated from these measurements. It can be difficult to get accurate damping measurements using this experimental setup and some of the details of how to obtain quality results are seemingly nontrivial. The intent of this paper is to present those details.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850000110&hterms=arm+vibration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Darm%2Bvibration','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850000110&hterms=arm+vibration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Darm%2Bvibration"><span>Air <span class="hlt">Bearing</span> for Small Planar Vibrations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wolf, M. F.</p> <p>1985-01-01</p> <p>Air-cushion device provides vibrations along axes 90 degrees apart. <span class="hlt">Bearing</span> includes movable slide sandwiched between two fixed support plates. Separation between plates <span class="hlt">adjusted</span> to standard air-<span class="hlt">bearing</span> tolerances. Pressurized air supplied to slide so it floats between plates on cushion of air. Air exhausts on top and bottom surfaces of three arms of slide. Developed for stirring crystal-growth liquids in containers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730017752','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730017752"><span>Parametric study of the lubrication of thrust loaded 120-mm bore ball <span class="hlt">bearings</span> to 3 million DN</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Signer, H.; Bamberger, E. N.; Zaretsky, E. V.</p> <p>1973-01-01</p> <p>A parametric study was performed with 120-mm bore angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> under varying thrust loads, <span class="hlt">bearing</span> and lubricant temperatures, and cooling and lubricant flow rates. <span class="hlt">Contact</span> angles were nominally 20 and 24 deg with <span class="hlt">bearing</span> speeds to 3 million DN. Endurance tests were run at 3 million DN and a temperature of 492 K (425 F) with 10 <span class="hlt">bearings</span> having a nominal 24 deg <span class="hlt">contact</span> angle at a thrust load of 22241 N (5000 lb). <span class="hlt">Bearing</span> operating temperature, differences in temperatures between the inner and outer races, and <span class="hlt">bearing</span> power consumption can be tuned to any desirable operating requirement by varying 4 parameters. These parameters are outer-race cooling, inner-race cooling, lubricant flow to the inner race, and oil inlet temperature. Preliminary endurance tests at 3 million DN and 492 K (425 F) indicate that long term <span class="hlt">bearing</span> operation can be achieved with a high degree of reliability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920024980','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920024980"><span>Wear mechanisms found in angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span> of the SSME's LOX turbopump</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chase, T. J.</p> <p>1992-01-01</p> <p>Extensive experimental investigations were carried out on used flight <span class="hlt">bearings</span> of the Phase 2 high-pressure oxygen turbopump (HPOTP) of the Space Shuttle Main Engine (SSME) in order to determine the wear mechanisms, dominant wear modes, and their extent and causes. The report shows methodology, surface analysis techniques used, result, and discussion. The mode largely responsible for heavy <span class="hlt">bearing</span> wear in LOX was identified as adhesive/shear peeling of the upper layers of <span class="hlt">bearing</span> balls and rings. The mode relies on the mechanisms of scale formation, breakdown, and removal, all of which are greatly enhanced by the heavy oxidation environment of the HPOTP. Major causes of the high wear in <span class="hlt">bearings</span> appear to be lubrication and cooling, both inadequate for the imposed conditions of operation. Numerous illustrations and evidence are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPPhy.158..575C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPPhy.158..575C"><span>Studies on Automobile Clutch Release <span class="hlt">Bearing</span> Characteristics with Acoustic Emission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Guoliang; Chen, Xiaoyang</p> <p></p> <p>Automobile clutch release <span class="hlt">bearings</span> are important automotive driveline components. For the clutch release <span class="hlt">bearing</span>, early fatigue failure diagnosis is significant, but the early fatigue failure response signal is not obvious, because failure signals are susceptible to noise on the transmission path and to working environment factors such as interference. With an improvement in vehicle design, clutch release <span class="hlt">bearing</span> fatigue life indicators have increasingly become an important requirement. <span class="hlt">Contact</span> fatigue is the main failure mode of release rolling <span class="hlt">bearing</span> components. Acoustic emission techniques in <span class="hlt">contact</span> fatigue failure detection have unique advantages, which include highly sensitive nondestructive testing methods. In the acoustic emission technique to detect a <span class="hlt">bearing</span>, signals are collected from multiple sensors. Each signal contains partial fault information, and there is overlap between the signals' fault information. Therefore, the sensor signals receive simultaneous source information integration is complete fragment rolling <span class="hlt">bearing</span> fault acoustic emission signal, which is the key issue of accurate fault diagnosis. Release <span class="hlt">bearing</span> comprises the following components: the outer ring, inner ring, rolling ball, cage. When a failure occurs (such as cracking, pitting), the other components will impact damaged point to produce acoustic emission signal. Release <span class="hlt">bearings</span> mainly emit an acoustic emission waveform with a Rayleigh wave propagation. Elastic waves emitted from the sound source, and it is through the part surface <span class="hlt">bearing</span> scattering. Dynamic simulation of rolling <span class="hlt">bearing</span> failure will contribute to a more in-depth understanding of the characteristics of rolling <span class="hlt">bearing</span> failure, because monitoring and fault diagnosis of rolling <span class="hlt">bearings</span> provide a theoretical basis and foundation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ThEng..65...93S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ThEng..65...93S"><span>Rotor Rolling over a Water-Lubricated <span class="hlt">Bearing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shatokhin, V. F.</p> <p>2018-02-01</p> <p>The article presents the results of studying the effect of forces associated with secondary damping coefficients (gyroscopic forces) on the development of asynchronous rolling of the rotor over a water-lubricated <span class="hlt">bearing</span>. The damping forces act against the background of other exciting forces in the rotor-supports system, in particular, the exciting forces of <span class="hlt">contact</span> interaction between the rotor and <span class="hlt">bearing</span>. The article considers a rotor resting on supports rubbing against the <span class="hlt">bearing</span> and the occurrence of self-excited vibration in the form of asynchronous roll-over. The rotor supports are made in the form of plain-type water-lubricated <span class="hlt">bearings</span>. The plain-type <span class="hlt">bearing</span>'s lubrication stiffness and damping forces are determined using the wellknown algorithms taking into account the physical properties of water serving as lubrication of the <span class="hlt">bearing</span>. The <span class="hlt">bearing</span> sliding pair is composed of refractory materials. The lubrication layer in such <span class="hlt">bearings</span> is thinner than that used in oil-lubricated <span class="hlt">bearings</span> with white metal lining, and there is no white metal layer in waterlubricated <span class="hlt">bearings</span>. In case of possible deviations from normal operation of the installation, the rotating rotor comes into direct <span class="hlt">contact</span> with the liner's rigid body. Unsteady vibrations are modeled using a specially developed software package for calculating the vibration of rotors that rub against the turbine (pump) stator elements. The stiffness of the <span class="hlt">bearing</span> liner with the stator support structure is specified by a dependence in the force-deformation coordinate axes. In modeling the effect of damping forces, the time moment corresponding to the onset of asynchronous rolling-over with growing vibration amplitudes is used as the assessment criterion. With a longer period of time taken for the rolling-over to develop, it becomes possible to take the necessary measures in response to actuation of the equipment set safety system, which require certain time for implementing them. It is shown that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720008684','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720008684"><span>Analysis of an arched outer-race ball <span class="hlt">bearing</span> considering centrifugal forces</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamrock, B. J.; Anderson, W. J.</p> <p>1972-01-01</p> <p>A Newton-Raphson method of iteration was used in evaluating the radial and axial projection of the distance between the ball center and the outer raceway groove curvature center (V and W). Fatigue life evaluations were made. The similar analysis of a conventional <span class="hlt">bearing</span> can be directly obtained from the arched <span class="hlt">bearing</span> analysis by simply letting the amount of arching be zero (g = 0) and not considering equations related to the unloaded half of the outer race. The analysis was applied to a 150-mm angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span>. Results for life, <span class="hlt">contact</span> loads, and angles are shown for a conventional <span class="hlt">bearing</span> (g = 0) and two arched <span class="hlt">bearings</span> (g = 0.127 mm (0.005 in.), and 0.254 mm (0.010 in.)). The results indicate that an arched <span class="hlt">bearing</span> is highly desirable for high speed applications. In particular, for a DN value of 3 million (20,000 rpm) and an applied axial load of 4448 N (1000 lb), an arched <span class="hlt">bearing</span> shows an improvement in life of 306 percent over that of a conventional <span class="hlt">bearing</span>. At 4.2 million DN (28,000 rpm), the corresponding improvement is 340 percent. It was also found for low speeds, the arched <span class="hlt">bearing</span> does not offer the advantages that it does for high speed applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20180002168','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20180002168"><span>Ni-Ti Next Generation <span class="hlt">Bearings</span> for Space Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DellaCorte, Christopher</p> <p>2018-01-01</p> <p>NASA applications challenge traditional <span class="hlt">bearing</span> materials. The rigors of launch often include heavy shock loads and exposure to corrosive environments (e.g., salt spray). Unfortunately, ball and roller <span class="hlt">bearings</span> made from hardened steels are vulnerable to Brinell denting and rust which can limit performance and life. Ceramic materials can eliminate corrosion concerns but their high stiffness and extreme hardness actually makes denting problems worse. In this presentation, an emerging superelastic alloy, NiTi, is introduced for rolling element <span class="hlt">bearing</span> applications. Through a decade of RD, NiTi alloy <span class="hlt">bearings</span> have been put through a comprehensive series of life and performance tests. Hardness, corrosion, strength, stiffness, and rolling <span class="hlt">contact</span> fatigue tests have been conducted and reported. Ball <span class="hlt">bearings</span> ranging in size from 12 to 50mm bore have been successfully engineered and operated over a wide range of speeds and test conditions including being submerged in water. The combination of high hardness, moderate elastic modulus, low density, and intrinsic corrosion immunity provide new possibilities for mechanisms that operate under extreme conditions. Recent preliminary tests indicate that <span class="hlt">bearings</span> can be made from NiTi alloys that are easily lubricated by conventional oils and greases and exhibit acceptable rolling <span class="hlt">contact</span> fatigue resistance. This presentation introduces the NiTi materials systems and shows how NASA is using it to alleviate several specific problems encountered in advanced space applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790003236','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790003236"><span>Mini-BRU/BIPS foil <span class="hlt">bearing</span> development</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dobler, F. X.; Miller, L. J.</p> <p>1978-01-01</p> <p>The analysis revealed the failure agent to be a combination of poor teflon coating adhesion, a decrease in <span class="hlt">bearing</span> sway space and, possibly, lack of flushing flow through the <span class="hlt">bearing</span>. A change in Teflon coating vendors provided substantially improved coating quality and surface finish. The sway space was increased and the cooling bleed flow was <span class="hlt">adjusted</span> to flush the <span class="hlt">bearing</span>. These changes were included in a test conducted in the WHL from 6 April to 22 May 1978 which resulted in the completion of 1006.9 hours of operation at temperature and load. Post-test inspection revealed the <span class="hlt">bearings</span> to be in excellent condition and capable of completing a much longer test.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985navy.reptR....A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985navy.reptR....A"><span>Precise <span class="hlt">bearing</span> support ditherer with piezoelectric drive means</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Assard, G. L.; Moorcroft, A. L.</p> <p>1985-06-01</p> <p>A relatively solid mounting surface, which may be part of a leveling gimbal, supports a piezoelectric <span class="hlt">bearing</span> mount which has the properties of an acoustic transducer. The transducer has electrodes thereon which are powered from multi-phase electrical sources causing the <span class="hlt">bearing</span> mount, and a <span class="hlt">bearing</span> jewel which is rigid therewith, to move so as to dither the jewel in a rotary or other preselected fashion, thereby reducing <span class="hlt">bearing</span> friction. Bandwidth, level and phasing sequence of the power sources are <span class="hlt">adjustable</span> permitting optimized average dynamic motion and corresponding increased readout accuracy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900019306','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900019306"><span><span class="hlt">Bearing</span> optimization for SSME HPOTP application</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Armstrong, Elizabeth S.; Coe, Harold H.</p> <p>1988-01-01</p> <p>The space shuttle main engine (SSME) high-pressure oxygen turbopumps (HPOTP) have not experienced the service life required of them. To improve the life of the existing turbopump <span class="hlt">bearings</span>, modifications to the <span class="hlt">bearings</span> that could be retrofitted into the present <span class="hlt">bearing</span> cavity are being investigated. Several <span class="hlt">bearing</span> parameters were optimized using the computer program SHABERTH, which performs a thermomechanical simulation of a load support system. The computer analysis showed that improved <span class="hlt">bearing</span> performance is feasible if low friction coefficients can be attained. <span class="hlt">Bearing</span> geometries were optimized considering heat generation, equilibrium temperatures, and relative life. Two sets of curvatures were selected from the optimization: an inner-raceway curvature of 0.54, an outer-raceway curvature of 0.52, and an inner-raceway curvature of 0.55, an outer-raceway curvature of 0.53. A <span class="hlt">contact</span> angle of 16 deg was also selected. Thermal gradients through the <span class="hlt">bearings</span> were found to be lower with liquid lubrication than with solid film lubrication. As the coolant flowrate through the <span class="hlt">bearing</span> increased, the ball temperature decreased but at a continuously decreasing rate. The optimum flowrate was approximately 4 kg/s. The analytical modeling used to determine these feasible modifications to improve <span class="hlt">bearing</span> performance is described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960020392&hterms=journal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Djournal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960020392&hterms=journal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Djournal"><span>Fractional Whirl Motion in Wave Journal <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dimofte, Florin; Hendricks, Robert C.</p> <p>1996-01-01</p> <p>Unloaded gas, plain journal <span class="hlt">bearings</span> experience sub-synchronous whirl motion due to fluid film instabilities and wall <span class="hlt">contact</span> usually occurs immediately after the onset of the whirl motion. An alternative is the wave journal <span class="hlt">bearing</span> which significantly improves <span class="hlt">bearing</span> stability. The predicted threshold where the sub-synchronous whirl motion starts was well confirmed by the experimental observation. In addition, both a two-wave and a three-wave journal <span class="hlt">bearing</span> can operate free of sub-synchronous whirl motion over a large range in speeds. When the sub-synchronous whirl motion occurs, both the two-wave and three-wave <span class="hlt">bearing</span> can run in a whirl orbit well within the <span class="hlt">bearing</span> clearance. At large clearances and wave amplitudes a two-wave <span class="hlt">bearing</span>, unliKe other <span class="hlt">bearings</span>, can exhibit a sub-synchronous whirl movement at both low and high speeds, but can run extremely stable and without whirl at intermediate speeds. Moreover, in these cases, the whirl frequencies are close to a quarter of the synchronous speed. The three-wave <span class="hlt">bearing</span> can exhibit sub-synchronous whirl motion only after a specific threshold when the speed increases and the whirl frequencies are close to half of the synchronous speed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1784078','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1784078"><span>Fixed or mobile-<span class="hlt">bearing</span> total knee arthroplasty</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Huang, Chun-Hsiung; Liau, Jiann-Jong; Cheng, Cheng-Kung</p> <p>2007-01-01</p> <p>Fixed and mobile-<span class="hlt">bearing</span> in total knee arthroplasty are still discussed controversially. In this article, biomechanical and clinical aspects in both fixed and mobile-<span class="hlt">bearing</span> designs were reviewed. In biomechanical aspect, the mobile-<span class="hlt">bearing</span> design has proved to provide less tibiofemoral <span class="hlt">contact</span> stresses under tibiofemoral malalignment conditions. It also provides less wear rate in in-vitro simulator test. Patients with posterior stabilized mobile-<span class="hlt">bearing</span> knees had more axial tibiofemoral rotation than patients with posterior stabilized fixed-<span class="hlt">bearing</span> knees during gait as well as in a deep knee-bend activity. However, in clinical aspect, the mid-term or long-term survivorship of mobile-<span class="hlt">bearing</span> knees has no superiority over that of fixed-<span class="hlt">bearing</span> knees. The theoretical advantages for mobile-<span class="hlt">bearing</span> design to provide a long-term durability have not been demonstrated by any outcome studies. Finally, the fixed-<span class="hlt">bearing</span> design with all-polyethylene tibial component is suggested for relatively inactive, elder people. The mobile-<span class="hlt">bearing</span> design is suggested for younger or higher-demand patients due to the potential for reduced polyethylene wear and more normal kinematics response after joint replacement. For younger surgeon, the fixed-<span class="hlt">bearing</span> design is suggested due to less demand for surgical technique. For experienced surgeon, one familiar surgical protocol and instrumentation is suggested rather than implant design, either fixed-<span class="hlt">bearing</span> or mobile-<span class="hlt">bearing</span>. PMID:17204165</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17204165','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17204165"><span>Fixed or mobile-<span class="hlt">bearing</span> total knee arthroplasty.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Chun-Hsiung; Liau, Jiann-Jong; Cheng, Cheng-Kung</p> <p>2007-01-05</p> <p>Fixed and mobile-<span class="hlt">bearing</span> in total knee arthroplasty are still discussed controversially. In this article, biomechanical and clinical aspects in both fixed and mobile-<span class="hlt">bearing</span> designs were reviewed. In biomechanical aspect, the mobile-<span class="hlt">bearing</span> design has proved to provide less tibiofemoral <span class="hlt">contact</span> stresses under tibiofemoral malalignment conditions. It also provides less wear rate in in-vitro simulator test. Patients with posterior stabilized mobile-<span class="hlt">bearing</span> knees had more axial tibiofemoral rotation than patients with posterior stabilized fixed-<span class="hlt">bearing</span> knees during gait as well as in a deep knee-bend activity. However, in clinical aspect, the mid-term or long-term survivorship of mobile-<span class="hlt">bearing</span> knees has no superiority over that of fixed-<span class="hlt">bearing</span> knees. The theoretical advantages for mobile-<span class="hlt">bearing</span> design to provide a long-term durability have not been demonstrated by any outcome studies. Finally, the fixed-<span class="hlt">bearing</span> design with all-polyethylene tibial component is suggested for relatively inactive, elder people. The mobile-<span class="hlt">bearing</span> design is suggested for younger or higher-demand patients due to the potential for reduced polyethylene wear and more normal kinematics response after joint replacement. For younger surgeon, the fixed-<span class="hlt">bearing</span> design is suggested due to less demand for surgical technique. For experienced surgeon, one familiar surgical protocol and instrumentation is suggested rather than implant design, either fixed-<span class="hlt">bearing</span> or mobile-<span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT........74K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT........74K"><span>Rolling <span class="hlt">contact</span> fatigue of low hardness steel for slewing ring application</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knuth, Jason A.</p> <p></p> <p>This thesis discusses the rolling <span class="hlt">contact</span> fatigue of steel utilized in anti-friction <span class="hlt">bearings</span>, also referred to as slewing <span class="hlt">bearings</span>. These slewing <span class="hlt">bearings</span> are utilized in cranes, excavators, wind turbines and other similar applications. Five materials composed of two different material types were tested. The two material types were high carbon steel and medium carbon alloy steel. The test specimens were processed from forged rolled rings. Two machines were evaluated a ZF-RCF and 3-Ball test machine. The evaluation was to determine which machine can best simulate the application in which the slewing <span class="hlt">bearing</span> is utilized. Initially, each specimen will be pretested to determine the appropriate testing direction from within the forged rolled rings. Pretesting is needed in order to establish consistent failure modes between samples. The primary goal of the test is to understand the life differences and failure modes between high carbon steel and medium carbon alloy steel. The high carbon steel ring was cut into two sections, one of which was stress relieved and the other was quenched and tempered. The medium carbon alloy steel was cut into three sections, all of which were quenched and tempered to different hardness levels. The test program was dynamically <span class="hlt">adjusted</span> based upon the previous sample's life and load. An S-N curve was then established from the 5 materials tested at two target loads. The samples were run until the first sign of a crack was detected by an eddy current. At the completion of the rolling <span class="hlt">contact</span> test, select sample's microstructure was evaluated for crack initiation location. The selected samples were divided into four groups which represent different maximum shear stress levels. These samples displayed indications of material deformation in which the high carbon steel experienced an increased amount of cold work when compared to medium carbon alloy steel. The life of the high carbon steel was nearly equivalent to the expected life of the medium</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026092','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026092"><span>Generated spiral bevel gears: Optimal machine-tool settings and tooth <span class="hlt">contact</span> analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, F. L.; Tsung, W. J.; Coy, J. J.; Heine, C.</p> <p>1985-01-01</p> <p>Geometry and kinematic errors were studied for Gleason generated spiral bevel gears. A new method was devised for choosing optimal machine settings. These settings provide zero kinematic errors and an improved <span class="hlt">bearing</span> <span class="hlt">contact</span>. The kinematic errors are a major source of noise and vibration in spiral bevel gears. The improved <span class="hlt">bearing</span> <span class="hlt">contact</span> gives improved conditions for lubrication. A computer program for tooth <span class="hlt">contact</span> analysis was developed, and thereby the new generation process was confirmed. The new process is governed by the requirement that during the generation process there is directional constancy of the common normal of the <span class="hlt">contacting</span> surfaces for generator and generated surfaces of pinion and gear.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970025228','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970025228"><span>A. Palmgren Revisited: A Basis for <span class="hlt">Bearing</span> Life Prediction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, Erwin V.</p> <p>1997-01-01</p> <p><span class="hlt">Bearing</span> technology, as well as the <span class="hlt">bearing</span> industry, began to develop with the invention of the bicycle in the 1850's. At the same time, high-quality steel was made possible by the Bessemer process. In 1881, H. Hertz published his <span class="hlt">contact</span> stress analysis. By 1902, R. Stribeck had published his work based on Hertz theory to calculate the maximum load of a radially loaded ball <span class="hlt">bearing</span>. By 1920, all of the rolling <span class="hlt">bearing</span> types used today were being manufactured. AISI 52100 <span class="hlt">bearing</span> steel became the material of choice for these <span class="hlt">bearings</span>. Beginning in 1918, engineers directed their attention to predicting the lives of these <span class="hlt">bearings</span>. In 1924, A. Palmgren published a paper outlining his approach to <span class="hlt">bearing</span> life prediction. This paper was the basis for the Lundberg-Palmgren life theory published in 1947. A critical review of the 1924 Palmgren paper is presented here together with a discussion of its effect on <span class="hlt">bearing</span> life prediction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25980556','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25980556"><span>Prediction of <span class="hlt">contact</span> mechanics in metal-on-metal Total Hip Replacement for parametrically comprehensive designs and loads.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Donaldson, Finn E; Nyman, Edward; Coburn, James C</p> <p>2015-07-16</p> <p>Manufacturers and investigators of Total Hip Replacement (THR) <span class="hlt">bearings</span> require tools to predict the <span class="hlt">contact</span> mechanics resulting from diverse design and loading parameters. This study provides <span class="hlt">contact</span> mechanics solutions for metal-on-metal (MoM) <span class="hlt">bearings</span> that encompass the current design space and could aid pre-clinical design optimization and evaluation. Stochastic finite element (FE) simulation was used to calculate the head-on-cup <span class="hlt">contact</span> mechanics for five thousand combinations of design and loading parameters. FE results were used to train a Random Forest (RF) surrogate model to rapidly predict the <span class="hlt">contact</span> patch dimensions, <span class="hlt">contact</span> area, pressures and plastic deformations for arbitrary designs and loading. In addition to widely observed polar and edge <span class="hlt">contact</span>, FE results included ring-polar, asymmetric-polar, and transitional categories which have previously received limited attention. Combinations of design and load parameters associated with each <span class="hlt">contact</span> category were identified. Polar <span class="hlt">contact</span> pressures were predicted in the range of 0-200 MPa with no permanent deformation. Edge loading (with subluxation) was associated with pressures greater than 500 MPa and induced permanent deformation in 83% of cases. Transitional-edge <span class="hlt">contact</span> (with little subluxation) was associated with intermediate pressures and permanent deformation in most cases, indicating that, even with ideal anatomical alignment, <span class="hlt">bearings</span> may face extreme wear challenges. Surrogate models were able to accurately predict <span class="hlt">contact</span> mechanics 18,000 times faster than FE analyses. The developed surrogate models enable rapid prediction of MoM <span class="hlt">bearing</span> <span class="hlt">contact</span> mechanics across the most comprehensive range of loading and designs to date, and may be useful to those performing <span class="hlt">bearing</span> design optimization or evaluation. Published by Elsevier Ltd.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080023401','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080023401"><span>Misalignment in Gas Foil Journal <span class="hlt">Bearings</span>: An Experimental Study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Howard, Samuel A.</p> <p>2008-01-01</p> <p>As gas foil journal <span class="hlt">bearings</span> become more prevalent in production machines, such as small gas turbine propulsion systems and microturbines, system-level performance issues must be identified and quantified in order to provide for successful design practices. Several examples of system-level design parameters that are not fully understood in foil <span class="hlt">bearing</span> systems are thermal management schemes, alignment requirements, balance requirements, thrust load balancing, and others. In order to address some of these deficiencies and begin to develop guidelines, this paper presents a preliminary experimental investigation of the misalignment tolerance of gas foil journal <span class="hlt">bearing</span> systems. Using a notional gas foil <span class="hlt">bearing</span> supported rotor and a laser-based shaft alignment system, increasing levels of misalignment are imparted to the <span class="hlt">bearing</span> supports while monitoring temperature at the <span class="hlt">bearing</span> edges. The amount of misalignment that induces <span class="hlt">bearing</span> failure is identified and compared to other conventional <span class="hlt">bearing</span> types such as cylindrical roller <span class="hlt">bearings</span> and angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span>. Additionally, the dynamic response of the rotor indicates that the gas foil <span class="hlt">bearing</span> force coefficients may be affected by misalignment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=improvisation&pg=4&id=EJ997197','ERIC'); return false;" href="https://eric.ed.gov/?q=improvisation&pg=4&id=EJ997197"><span>"<span class="hlt">Contacting</span>" the Fundamentals: A New Paradigm for Pedagogy</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Munjee, Tara</p> <p>2012-01-01</p> <p><span class="hlt">Contact</span> improvisation can serve as a way to access new understandings of Bartenieff Fundamentals. Inherent elements of <span class="hlt">contact</span> improvisation such as thinking and feeling bodily in the moment, sensitivity to activated weight along with weight sharing and <span class="hlt">bearing</span>, flow, whole-body organization, and immediacy of embodied presence provide fertile…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12461373','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12461373"><span>Late dislocation of rotating platform in New Jersey Low-<span class="hlt">Contact</span> Stress knee prosthesis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Chun-Hsiung; Ma, Hon-Ming; Liau, Jiann-Jong; Ho, Fang-Yuan; Cheng, Cheng-Kung</p> <p>2002-12-01</p> <p>Five patients with late rotational dislocation of the rotating platform <span class="hlt">bearing</span> in the New Jersey Low-<span class="hlt">Contact</span> Stress total knee arthroplasty are reported. The prostheses had functioned well for 8 to 12 years before failure. Preoperative radiographs showed asymmetric femorotibial joint spaces. Entrapment of the dislocated <span class="hlt">bearing</span> in three patients and spontaneous reduction of the dislocated <span class="hlt">bearing</span> in another two patients were seen at revision. Femorotibial ligamentous instability was found after reduction. The retrieved polyethylene <span class="hlt">bearings</span> showed advanced wear and cold flow deformities and the thickness was reduced. The revision arthroplasty was accomplished by replacement with a thicker <span class="hlt">bearing</span> element. Progressive femorotibial ligament laxity and reduction of the thickness of polyethylene with wearing break down the originally well-balanced soft tissue tension of the knee. The rotational degree of the rotating platform <span class="hlt">bearing</span> is unrestricted, which may result in late dislocation. Polyethylene wear is unavoidable in knee prostheses using metal <span class="hlt">contact</span> with polyethylene even with a mobile-<span class="hlt">bearing</span> design. Efforts to reduce polyethylene wear are mandatory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA622119','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA622119"><span>Simulating Army-Relevant Spur Gear <span class="hlt">Contacts</span> with a Ball-on-Disc Tribometer</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2015-09-01</p> <p>on Steel Ceramic on Ceramic 23 amount of run in is a parameter that must be considered when simulating gear or <span class="hlt">bearing</span> <span class="hlt">contacts</span>, and can even be...minimum track diameters.......................19 Fig. 13 Hertzian <span class="hlt">contact</span> stress for steel and ceramic <span class="hlt">contacts</span> ............................21 Fig...14 <span class="hlt">Contact</span> radius for steel and ceramic <span class="hlt">contacts</span> .........................................21 Fig. 15 <span class="hlt">Contact</span> area for steel and ceramic <span class="hlt">contacts</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/874790','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/874790"><span>Load responsive hydrodynamic <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Kalsi, Manmohan S.; Somogyi, Dezso; Dietle, Lannie L.</p> <p>2002-01-01</p> <p>A load responsive hydrodynamic <span class="hlt">bearing</span> is provided in the form of a thrust <span class="hlt">bearing</span> or journal <span class="hlt">bearing</span> for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular <span class="hlt">bearing</span> bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for <span class="hlt">contact</span> with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the <span class="hlt">bearing</span> and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the <span class="hlt">bearing</span>, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790003233','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790003233"><span>Spherical <span class="hlt">bearing</span>. [to reduce vibration effects</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Myers, W. N.; Hein, L. A. (Inventor)</p> <p>1978-01-01</p> <p>A spherical <span class="hlt">bearing</span> including an inner ball with an opening for receiving a shaft and a spherical outer surface is described. Features of the <span class="hlt">bearing</span> include: (1) a circular outer race including a plurality of circumferentially spaced sections extending around the inner ball for snugly receiving the inner ball; and (2) a groove extending circumferentially around the race producing a thin wall portion which permits the opposed side portions to flex relative to the ball for maximizing the physical <span class="hlt">contact</span> between the inner surface of the race and the spherical outer surface of the ball.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960000247&hterms=tears&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dtears','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960000247&hterms=tears&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dtears"><span>Hybrid superconductor magnet <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chu, Wei-Kan</p> <p>1995-01-01</p> <p>Hybrid superconductor magnet <span class="hlt">bearings</span> (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical <span class="hlt">contact</span> between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical <span class="hlt">bearings</span> on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence <span class="hlt">bearings</span> with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such <span class="hlt">bearing</span>, capable of supporting a telescope that weighs about 3 lbs on Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110016524','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110016524"><span>Resilient and Corrosion-Proof Rolling Element <span class="hlt">Bearings</span> Made from Superelastic Ni-Ti Alloys for Aerospace Mechanism Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DellaCorte, Christopher; Noebe, Ronald D.; Stanford, Malcolm; Padula, Santo A.</p> <p>2011-01-01</p> <p>Mechanical components (<span class="hlt">bearings</span>, gears, mechanisms) typically utilize hard materials to minimize wear and attain long life. In such components, heavily loaded <span class="hlt">contact</span> points (e.g., meshing gear teeth, <span class="hlt">bearing</span> ball-raceway <span class="hlt">contacts</span>) experience high <span class="hlt">contact</span> stresses. The combination of high hardness, heavy loads and high elastic modulus often leads to damaging <span class="hlt">contact</span> stress. In addition, mechanical component materials, such as tool steel or silicon nitride exhibit limited recoverable strain (typically less than 1 percent). These material attributes can lead to Brinell damage (e.g., denting) particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this paper, a superelastic alloy, 60NiTi, is considered for rolling element <span class="hlt">bearing</span> applications. A series of Rockwell and Brinell hardness, compressive strength, fatigue and tribology tests are conducted and reported. The combination of high hardness, moderate elastic modulus, large recoverable strain, low density, and intrinsic corrosion immunity provide a path to <span class="hlt">bearings</span> largely impervious to shock load damage. It is anticipated that <span class="hlt">bearings</span> and components made from alloys with such attributes can alleviate many problems encountered in advanced aerospace applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090019112','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090019112"><span>Intermetallic Nickel-Titanium Alloys for Oil-Lubricated <span class="hlt">Bearing</span> Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DellaCorte, C.; Pepper, S. V.; Noebe, R.; Hull, D. R.; Glennon, G.</p> <p>2009-01-01</p> <p>An intermetallic nickel-titanium alloy, NITINOL 60 (60NiTi), containing 60 wt% nickel and 40 wt% titanium, is shown to be a promising candidate material for oil-lubricated rolling and sliding <span class="hlt">contact</span> applications such as <span class="hlt">bearings</span> and gears. NiTi alloys are well known and normally exploited for their shape memory behavior. When properly processed, however, NITINOL 60 exhibits excellent dimensional stability and useful structural properties. Processed via high temperature, high-pressure powder metallurgy techniques or other means, NITINOL 60 offers a broad combination of physical properties that make it unique among <span class="hlt">bearing</span> materials. NITINOL 60 is hard, electrically conductive, highly corrosion resistant, less dense than steel, readily machined prior to final heat treatment, nongalling and nonmagnetic. No other <span class="hlt">bearing</span> alloy, metallic or ceramic encompasses all of these attributes. Further, NITINOL 60 has shown remarkable tribological performance when compared to other aerospace <span class="hlt">bearing</span> alloys under oil-lubricated conditions. Spiral orbit tribometer (SOT) tests were conducted in vacuum using NITINOL 60 balls loaded between rotating 440C stainless steel disks, lubricated with synthetic hydrocarbon oil. Under conditions considered representative of precision <span class="hlt">bearings</span>, the performance (life and friction) equaled or exceeded that observed with silicon nitride or titanium carbide coated 440C <span class="hlt">bearing</span> balls. Based upon this preliminary data, it appears that NITINOL 60, despite its high titanium content, is a promising candidate alloy for advanced mechanical systems requiring superior and intrinsic corrosion resistance, electrical conductivity and nonmagnetic behavior under lubricated <span class="hlt">contacting</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740007023','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740007023"><span>Ball motion and sliding friction in an arched outer-race ball <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamrock, B. J.</p> <p>1974-01-01</p> <p>The motion of the ball and sliding friction in an arched outer-race ball <span class="hlt">bearing</span> under thrust load is analyzed. Fatigue life evaluations were made. The analysis is applied to a 150-millimeter-bore ball <span class="hlt">bearing</span>. The results indicated that for high-speed light-load applications the arched <span class="hlt">bearing</span> has significant improvement in fatigue life over that of a conventional <span class="hlt">bearing</span>. An arching of 0.254 mm (0.01 in.) was found to be optimal. Also, for an arched <span class="hlt">bearing</span> a considerable amount of spinning occurs at the outer-race <span class="hlt">contacts</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17343698','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17343698"><span>A hydrodynamically suspended, magnetically sealed mechanically noncontact axial flow blood pump: design of a hydrodynamic <span class="hlt">bearing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mitamura, Yoshinori; Kido, Kazuyuki; Yano, Tetsuya; Sakota, Daisuke; Yambe, Tomoyuki; Sekine, Kazumitsu; OKamoto, Eiji</p> <p>2007-03-01</p> <p>To overcome the drive shaft seal and <span class="hlt">bearing</span> problem in rotary blood pumps, a hydrodynamic <span class="hlt">bearing</span>, a magnetic fluid seal, and a brushless direct current (DC) motor were employed in an axial flow pump. This enabled <span class="hlt">contact</span>-free rotation of the impeller without material wear. The axial flow pump consisted of a brushless DC motor, an impeller, and a guide vane. The motor rotor was directly connected to the impeller by a motor shaft. A hydrodynamic <span class="hlt">bearing</span> was installed on the motor shaft. The motor and the hydrodynamic <span class="hlt">bearing</span> were housed in a cylindrical casing and were waterproofed by a magnetic fluid seal, a mechanically noncontact seal. Impeller shaft displacement was measured using a laser sensor. Axial and radial displacements of the shaft were only a few micrometers for motor speed up to 8500 rpm. The shaft did not make <span class="hlt">contact</span> with the <span class="hlt">bearing</span> housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mm Hg. In conclusion, the axial flow blood pump consisting of a hydrodynamic <span class="hlt">bearing</span>, a magnetic fluid seal, and a brushless DC motor provided <span class="hlt">contact</span>-free rotation of the impeller without material wear.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150018925','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150018925"><span>On Calculation Methods and Results for Straight Cylindrical Roller <span class="hlt">Bearing</span> Deflection, Stiffness, and Stress</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Krantz, Timothy L.</p> <p>2011-01-01</p> <p>The purpose of this study was to assess some calculation methods for quantifying the relationships of <span class="hlt">bearing</span> geometry, material properties, load, deflection, stiffness, and stress. The scope of the work was limited to two-dimensional modeling of straight cylindrical roller <span class="hlt">bearings</span>. Preparations for studies of dynamic response of <span class="hlt">bearings</span> with damaged surfaces motivated this work. Studies were selected to exercise and build confidence in the numerical tools. Three calculation methods were used in this work. Two of the methods were numerical solutions of the Hertz <span class="hlt">contact</span> approach. The third method used was a combined finite element surface integral method. Example calculations were done for a single roller loaded between an inner and outer raceway for code verification. Next, a <span class="hlt">bearing</span> with 13 rollers and all-steel construction was used as an example to do additional code verification, including an assessment of the leading order of accuracy of the finite element and surface integral method. Results from that study show that the method is at least first-order accurate. Those results also show that the <span class="hlt">contact</span> grid refinement has a more significant influence on precision as compared to the finite element grid refinement. To explore the influence of material properties, the 13-roller <span class="hlt">bearing</span> was modeled as made from Nitinol 60, a material with very different properties from steel and showing some potential for <span class="hlt">bearing</span> applications. The codes were exercised to compare <span class="hlt">contact</span> areas and stress levels for steel and Nitinol 60 <span class="hlt">bearings</span> operating at equivalent power density. As a step toward modeling the dynamic response of <span class="hlt">bearings</span> having surface damage, static analyses were completed to simulate a <span class="hlt">bearing</span> with a spall or similar damage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=biochemical+AND+tests&pg=5&id=ED143983','ERIC'); return false;" href="https://eric.ed.gov/?q=biochemical+AND+tests&pg=5&id=ED143983"><span>Psychological <span class="hlt">Adjustment</span> and Homosexuality.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Gonsiorek, John C.</p> <p></p> <p>In this paper, the diverse literature <span class="hlt">bearing</span> on the topic of homosexuality and psychological <span class="hlt">adjustment</span> is critically reviewed and synthesized. The first chapter discusses the most crucial methodological issue in this area, the problem of sampling. The kinds of samples used to date are critically examined, and some suggestions for improved…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T23B2946C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T23B2946C"><span>The Process and Reason of the Change of Oil-Water <span class="hlt">Contact</span> of Shahejie Formation in BZ25-1 Oilfield</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cong, F.; Liu, J.</p> <p>2015-12-01</p> <p>Due to the influence of Neo-tectonic movement, the Shahejie reservoirs in Bohai Bay Basin has undergone late-stage transformation and <span class="hlt">adjustment</span>, causing the oil-water <span class="hlt">contact</span> to change. Through studying the changing history of oil-water <span class="hlt">contact</span>, we can better restore petroleum accumulation process and analyze oil distribution pattern. Based on reservoir geochemistry theory and drilling and logging data, grains with oil inclusion was analyzed, and oil-<span class="hlt">bearing</span> property, organic extracts and biomarkers was used to determine the present and paleo-oil water <span class="hlt">contact</span> of Shahejie formation in BZ25-1 oilfield. It suggested that the paleo and present oil-water <span class="hlt">contact</span> in Shahejie formation locates in different depth, and that Shahejie formation has gone through three petroleum charging stages and has also undergone reservoir <span class="hlt">adjustment</span>. The POWC(paleo-oil-water <span class="hlt">contact</span>) of E2S2 reservoirs in BZ25-1-5 well and E2S2 reservoirs in BZ25-1-3 well is lower than OWC(present oil-water <span class="hlt">contact</span>) at least for 9m and at most for 400m, but the POWC of E2S3 reservoirs in BZ25-1-5 well is higher than OWC at least for 20m and at most for 27.5m. The petroleum accumulation process and the reason for oil-water <span class="hlt">contact</span> <span class="hlt">adjustment</span> were studied based on burial history, petroleum generation history, fault re-activation rate and petroleum charging history. It suggested that the three petroleum charging stages are Mid-Miocene(11.5Ma), Late Miocene-Pliocene(6.5-3.5Ma) and Quaternary(2.5Ma-present), among which the second~third charging episode is seen as the major petroleum accumulation stage. The re-activeted faults in several different periods not only served as preferential path for petroleum vertical migration, but also caused petroleum leakage through faults. The petroleum leakage mainly occurred in Neo-tectonic movement period(after 3.5Ma), during which petroleum vertically leaked through re-activated faults and migrated to shallow reservoirs or spilled over surface, meanwhile due to constant</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=race+AND+mixing&pg=2&id=ED148920','ERIC'); return false;" href="https://eric.ed.gov/?q=race+AND+mixing&pg=2&id=ED148920"><span>Class Racial Composition, the Friendliness of Interracial <span class="hlt">Contact</span> and Student Performance.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Patchen, Martin; And Others</p> <p></p> <p>This paper presents further evidence <span class="hlt">bearing</span> on the hypothesis that the academic performance of students is associated more closely with the friendliness or unfriendliness of interracial <span class="hlt">contact</span> than with the sheer opportunity for interracial <span class="hlt">contact</span>. In addition, evidence is presented concerning the relationship of interracial <span class="hlt">contact</span> and of…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23108270','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23108270"><span>Neuromagnetic brain activity associated with anticipatory postural <span class="hlt">adjustments</span> for bimanual load lifting.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ng, Tommy H B; Sowman, Paul F; Brock, Jon; Johnson, Blake W</p> <p>2013-02-01</p> <p>During bimanual load lifting, the brain must anticipate the effects of unloading upon the load-<span class="hlt">bearing</span> arm. Little is currently known about the neural networks that coordinate these anticipatory postural <span class="hlt">adjustments</span>. We measured neuromagnetic brain activity with whole-head magnetoencephalography while participants performed a bimanual load-lifting task. Anticipatory <span class="hlt">adjustments</span> were associated with reduction in biceps brachii muscle activity of the load-<span class="hlt">bearing</span> arm and pre-movement desynchronization of the cortical beta rhythm. Beamforming analyses localized anticipatory brain activity to the precentral gyrus, basal ganglia, supplementary motor area, and thalamus, contralateral to the load-<span class="hlt">bearing</span> arm. To our knowledge this is the first human neuroimaging study to directly investigate anticipatory postural <span class="hlt">adjustments</span> and to explicitly partition the anticipatory and volitional aspects of brain activity in bimanual load lifting. These data contribute to our understanding of the neural systems supporting anticipatory postural <span class="hlt">adjustments</span> in healthy adults. Copyright © 2012 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/869873','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/869873"><span>Process for depositing Cr-<span class="hlt">bearing</span> layer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ellis, Timothy W.; Lograsso, Thomas A.; Eshelman, Mark A.</p> <p>1995-05-09</p> <p>A method of applying a Cr-<span class="hlt">bearing</span> layer to a substrate, comprises introducing an organometallic compound, in vapor or solid powder form entrained in a carrier gas to a plasma of an inductively coupled plasma torch or device to thermally decompose the organometallic compound and <span class="hlt">contacting</span> the plasma and the substrate to be coated so as to deposit the Cr-<span class="hlt">bearing</span> layer on the substrate. A metallic Cr, Cr alloy or Cr compound such as chromium oxide, nitride and carbide can be provided on the substrate. Typically, the organometallic compound is introduced to an inductively coupled plasma torch that is disposed in ambient air so to thermally decompose the organometallic compound in the plasma. The plasma is directed at the substrate to deposit the Cr-<span class="hlt">bearing</span> layer or coating on the substrate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/46310','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/46310"><span>Process for depositing Cr-<span class="hlt">bearing</span> layer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ellis, T.W.; Lograsso, T.A.; Eshelman, M.A.</p> <p>1995-05-09</p> <p>A method of applying a Cr-<span class="hlt">bearing</span> layer to a substrate, comprises introducing an organometallic compound, in vapor or solid powder form entrained in a carrier gas to a plasma of an inductively coupled plasma torch or device to thermally decompose the organometallic compound and <span class="hlt">contacting</span> the plasma and the substrate to be coated so as to deposit the Cr-<span class="hlt">bearing</span> layer on the substrate. A metallic Cr, Cr alloy or Cr compound such as chromium oxide, nitride and carbide can be provided on the substrate. Typically, the organometallic compound is introduced to an inductively coupled plasma torch that is disposed in ambient air so to thermally decompose the organometallic compound in the plasma. The plasma is directed at the substrate to deposit the Cr-<span class="hlt">bearing</span> layer or coating on the substrate. 7 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720000626','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720000626"><span>Design criteria monograph for high-load high-speed rolling-<span class="hlt">contact</span> <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1972-01-01</p> <p>Monograph was published which summarizes and systematically orders large body of successful techniques and practices developed for design of liquid rocket engine turbopump <span class="hlt">bearings</span>. Document was written to organize and present significant experience and knowledge accumulated by NASA in development and operational programs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790015259','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790015259"><span>Two-dimensional random surface model for asperity-<span class="hlt">contact</span> in elastohydrodynamic lubrication</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coy, J. J.; Sidik, S. M.</p> <p>1979-01-01</p> <p>Relations for the asperity-<span class="hlt">contact</span> time function during elastohydrodynamic lubrication of a ball <span class="hlt">bearing</span> are presented. The analysis is based on a two-dimensional random surface model, and actual profile traces of the <span class="hlt">bearing</span> surfaces are used as statistical sample records. The results of the analysis show that transition from 90 percent <span class="hlt">contact</span> to 1 percent <span class="hlt">contact</span> occurs within a dimensionless film thickness range of approximately four to five. This thickness ratio is several times large than reported in the literature where one-dimensional random surface models were used. It is shown that low pass filtering of the statistical records will bring agreement between the present results and those in the literature.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730023643','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730023643"><span>Ball motion and sliding friction in an arched outer race ball <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamrock, B. J.</p> <p>1973-01-01</p> <p>The motion of the ball and sliding friction in an arched outer race ball <span class="hlt">bearing</span> under thrust loads is determined. Fatigue life evaluations were made. The analysis is applied to a 150 millimeter bore ball <span class="hlt">bearing</span>. The results indicated that for high speed-light load applications the arched <span class="hlt">bearing</span> has significant improvement in fatigue life over that of a conventional <span class="hlt">bearing</span>. An arching of 0.254 mm (0.01 in.) was found to be an optimal. For an arched <span class="hlt">bearing</span> it was also found that a considerable amount of spinning occurs at the outer race <span class="hlt">contacts</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750028136&hterms=race&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drace','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750028136&hterms=race&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drace"><span>Ball motion and sliding friction in an arched outer race ball <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamrock, B. J.</p> <p>1974-01-01</p> <p>The motion of the ball and sliding friction in an arched outer-race ball <span class="hlt">bearing</span> under thrust load is determined. Fatigue life evaluations were made. The analysis is applied to a 150 millimeter bore ball <span class="hlt">bearing</span>. The results indicated that for high speed-light load applications the arched <span class="hlt">bearing</span> has significant improvement in fatigue life over that of a conventional <span class="hlt">bearing</span>. An arching of 0.254 mm (0.01 in.) was found to be an optimal. For an arched <span class="hlt">bearing</span> it was also found that a considerable amount of spinning occurs at the outer race <span class="hlt">contacts</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70033667','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70033667"><span>Grizzly <span class="hlt">bear</span> density in Glacier National Park, Montana</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kendall, K.C.; Stetz, J.B.; Roon, David A.; Waits, L.P.; Boulanger, J.B.; Paetkau, David</p> <p>2008-01-01</p> <p>We present the first rigorous estimate of grizzly <span class="hlt">bear</span> (Ursus arctos) population density and distribution in and around Glacier National Park (GNP), Montana, USA. We used genetic analysis to identify individual <span class="hlt">bears</span> from hair samples collected via 2 concurrent sampling methods: 1) systematically distributed, baited, barbed-wire hair traps and 2) unbaited <span class="hlt">bear</span> rub trees found along trails. We used Huggins closed mixture models in Program MARK to estimate total population size and developed a method to account for heterogeneity caused by unequal access to rub trees. We corrected our estimate for lack of geographic closure using a new method that utilizes information from radiocollared <span class="hlt">bears</span> and the distribution of <span class="hlt">bears</span> captured with DNA sampling. <span class="hlt">Adjusted</span> for closure, the average number of grizzly <span class="hlt">bears</span> in our study area was 240.7 (95% CI = 202–303) in 1998 and 240.6 (95% CI = 205–304) in 2000. Average grizzly <span class="hlt">bear</span> density was 30 <span class="hlt">bears</span>/1,000 km2, with 2.4 times more <span class="hlt">bears</span> detected per hair trap inside than outside GNP. We provide baseline information important for managing one of the few remaining populations of grizzlies in the contiguous United States.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AcMSn..30..746L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AcMSn..30..746L"><span>Coupled lateral-torsional-axial vibrations of a helical gear-rotor-<span class="hlt">bearing</span> system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Chao-Feng; Zhou, Shi-Hua; Liu, Jie; Wen, Bang-Chun</p> <p>2014-10-01</p> <p>Considering the axial and radial loads, a mathematical model of angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span> is deduced with Hertz <span class="hlt">contact</span> theory. With the coupling effects of lateral, torsional and axial vibrations taken into account, a lumped-parameter nonlinear dynamic model of helical gearrotor-<span class="hlt">bearing</span> system (HGRBS) is established to obtain the transmission system dynamic response to the changes of different parameters. The vibration differential equations of the drive system are derived through the Lagrange equation, which considers the kinetic and potential energies, the dissipative function and the internal/external excitation. Based on the Runge-Kutta numerical method, the dynamics of the HGRBS is investigated, which describes vibration properties of HGRBS more comprehensively. The results show that the vibration amplitudes have obvious fluctuation, and the frequency multiplication and random frequency components become increasingly obvious with changing rotational speed and eccentricity at gear and <span class="hlt">bearing</span> positions. Axial vibration of the HGRBS also has some fluctuations. The <span class="hlt">bearing</span> has self-variable stiffness frequency, which should be avoided in engineering design. In addition, the <span class="hlt">bearing</span> clearance needs little attention due to its slightly discernible effect on vibration response. It is suggested that a careful examination should be made in modelling the nonlinear dynamic behavior of a helical gear-rotor-<span class="hlt">bearing</span> system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860013162','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860013162"><span>Space Shuttle Main Engine (SSME) LOX turbopump pump-end <span class="hlt">bearing</span> analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1986-01-01</p> <p>A simulation of the shaft/<span class="hlt">bearing</span> system of the Space Shuttle Main Engine Liquid Oxygen turbopump was developed. The simulation model allows the thermal and mechanical characteristics to interact as a realistic simulation of the <span class="hlt">bearing</span> operating characteristics. The model accounts for single and two phase coolant conditions, and includes the heat generation from <span class="hlt">bearing</span> friction and fluid stirring. Using the simulation model, parametric analyses were performed on the 45 mm pump-end <span class="hlt">bearings</span> to investigate the sensitivity of <span class="hlt">bearing</span> characteristics to <span class="hlt">contact</span> friction, axial preload, coolant flow rate, coolant inlet temperature and quality, heat transfer coefficients, outer race clearance and misalignment, and the effects of thermally isolating the outer race from the isolator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990108572','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990108572"><span>Blood Pump <span class="hlt">Bearing</span> System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aber, Gregory S. (Inventor)</p> <p>1999-01-01</p> <p>Methods and apparatus are provided for a blood pump <span class="hlt">bearing</span> system within a pump housing to support long-term high-speed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The <span class="hlt">bearing</span> system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The <span class="hlt">bearing</span> system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line <span class="hlt">contact</span> around the circumference of the shaft to support high speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the <span class="hlt">bearing</span>. A void defined by the <span class="hlt">bearing</span> elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the <span class="hlt">bearing</span> surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010010198','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010010198"><span>Blood Pump <span class="hlt">Bearing</span> System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aber, Gregory S. (Inventor)</p> <p>2000-01-01</p> <p>An apparatus is provided for a blood pump <span class="hlt">bearing</span> system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The <span class="hlt">bearing</span> system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The <span class="hlt">bearing</span> system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line <span class="hlt">contact</span> around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the <span class="hlt">bearing</span>. A void defined by the <span class="hlt">bearing</span> elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the <span class="hlt">bearing</span> surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940018588','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940018588"><span>A technique to measure rotordynamic coefficients in hydrostatic <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Capaldi, Russell J.</p> <p>1993-01-01</p> <p>An experimental technique is described for measuring the rotordynamic coefficients of fluid film journal <span class="hlt">bearings</span>. The <span class="hlt">bearing</span> tester incorporates a double-spool shaft assembly that permits independent control over the journal spin speed and the frequency of an <span class="hlt">adjustable</span>-magnitude circular orbit. This configuration yields data that enables determination of the full linear anisotropic rotordynamic coefficient matrices. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Some results are presented for a four-recess, oil-fed hydrostatic journal <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820021732','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820021732"><span>Evaluation of <span class="hlt">bearing</span> mounting design and excessive wear phenomena</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kannel, J. W.</p> <p>1982-01-01</p> <p>The effect of <span class="hlt">bearing</span> thermal growth on the effectiveness of the <span class="hlt">bearing</span> preload springs on the space shuttle main engine high pressure oxygen turbopump (SSME HPTOP) were examined. The SSME HPTOP turbine end <span class="hlt">bearings</span>, preload spring, and <span class="hlt">bearing</span> mounting design were evaluated relative to spalling, excessive ball wear, possible thermal problems, and cage delamination. The magnitude of the thermal stresses required to cause high levels of ball wear were calculated. Plots of maximum sheer stress and maximum reversing shear versus the axial load for the 57 mm SSME HPTOP <span class="hlt">bearing</span> were created. A plot of the <span class="hlt">bearing</span> thermal growth versus preload spring deflection was generated. It was determined that metallic wear, rather than thermal growth, caused enlargement of the <span class="hlt">contact</span> zone between ball and races, that high fatigue-inducing shear stresses are generated under increased loads, and that at temperatures between 100 and 150 deg C, the springs bottom out and very high loads are developed in the <span class="hlt">bearing</span>. Allowance for adequate spring movement after assembly is recommended.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930018380','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930018380"><span>Magnetic <span class="hlt">bearings</span> for a high-performance optical disk buffer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hockney, Richard; Hawkey, Timothy</p> <p>1993-01-01</p> <p>An optical disk buffer concept can provide gigabit-per-second data rates and terabit capacity through the use of arrays of solid state lasers applied to a stack of erasable/reusable optical disks. The RCA optical disk buffer has evoked interest by NASA for space applications. The porous graphite air <span class="hlt">bearings</span> in the rotary spindle as well as those used in the linear translation of the read/write head would be replaced by magnetic <span class="hlt">bearings</span> or mechanical (ball or roller) <span class="hlt">bearings</span>. Based upon past experience, roller or ball <span class="hlt">bearings</span> for the translation stages are not feasible. Unsatisfactory, although limited experience exists with ball <span class="hlt">bearing</span> spindles also. Magnetic <span class="hlt">bearings</span>, however, appear ideally suited for both applications. The use of magnetic <span class="hlt">bearings</span> is advantageous in the optical disk buffer because of the absence of physical <span class="hlt">contact</span> between the rotating and stationary members. This frictionless operation leads to extended life and reduced drag. The manufacturing tolerances that are required to fabricate magnetic <span class="hlt">bearings</span> would also be relaxed from those required for precision ball and gas <span class="hlt">bearings</span>. Since magnetic <span class="hlt">bearings</span> require no lubricant, they are inherently compatible with a space (vacuum) environment. Magnetic <span class="hlt">bearings</span> also allow the dynamics of the rotor/<span class="hlt">bearing</span> system to be altered through the use of active control. This provides the potential for reduced vibration, extended regions of stable operation, and more precise control of position.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960025598','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960025598"><span>The thermal conductance of solid-lubricated <span class="hlt">bearings</span> at cryogenic temperatures in vacuum</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, M. J.</p> <p>1996-01-01</p> <p>The thermal conductance of Hertzian <span class="hlt">contacts</span> is of great importance to cryogenic spacecraft mechanisms such as the Infra-Red Space Observatory (ISO) and the Far Infra-Red Space Telescope (FIRST). At cryogenic temperatures, cooling of mechanism shafts and associated components occurs via conduction through the <span class="hlt">bearings</span>. When fluid lubricants are cooled below their pour points, they no longer lubricate effectively, and it is necessary to use low shear strength solid lubricants. Currently, only very limited low temperature data exists on the thermal conductance of Hertzian <span class="hlt">contacts</span> in both unlubricated and lubricated conditions. This paper reports on measurements of thermal conductance made on stationary ball <span class="hlt">bearings</span> under cryo-vacuum conditions. Quantitative data is provided to support the development of computer models predicting the thermal conductance of Hertzian <span class="hlt">contacts</span> and solid lubricants at cryogenic temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890013549','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890013549"><span>Topology of modified helical gears and Tooth <span class="hlt">Contact</span> Analysis (TCA) program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, Faydor L.; Zhang, Jiao</p> <p>1989-01-01</p> <p>The contents of this report covers: (1) development of optimal geometries for crowned helical gears; (2) a method for their generation; (3) tooth <span class="hlt">contact</span> analysis (TCA) computer programs for the analysis of meshing and <span class="hlt">bearing</span> <span class="hlt">contact</span> of the crowned helical gears; and (4) modelling and simulation of gear shaft deflection. The developed method for synthesis was used to determine the optimal geometry for a crowned helical pinion surface and was directed to localize the <span class="hlt">bearing</span> <span class="hlt">contact</span> and guarantee favorable shape and a low level of transmission errors. Two new methods for generation of the crowned helical pinion surface are proposed. One is based on the application of a tool with a surface of revolution that slightly deviates from a regular cone surface. The tool can be used as a grinding wheel or as a shaver. The other is based on a crowning pinion tooth surface with predesigned transmission errors. The pinion tooth surface can be generated by a computer-controlled automatic grinding machine. The TCA program simulates the meshing and <span class="hlt">bearing</span> <span class="hlt">contact</span> of the misaligned gears. The transmission errors are also determined. The gear shaft deformation was modelled and investigated. It was found that the deflection of gear shafts has the same effect as gear misalignment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070006849','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070006849"><span>Development and Testing of a Radial Halbach Magnetic <span class="hlt">Bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.</p> <p>2006-01-01</p> <p>The NASA John H. Glenn Research Center has developed and tested a revolutionary Radial Halbach Magnetic <span class="hlt">Bearing</span>. The objective of this work is to develop a viable non-<span class="hlt">contact</span> magnetic <span class="hlt">bearing</span> utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help reduce harmful emissions, reduce the Nation s dependence on fossil fuels and mitigate many of the concerns and limitations encountered in conventional axial <span class="hlt">bearings</span> such as <span class="hlt">bearing</span> wear, leaks, seals and friction loss. The Radial Halbach Magnetic <span class="hlt">Bearing</span> is inherently stable and requires no active feedback control system or superconductivity as required in many magnetic <span class="hlt">bearing</span> designs. The Radial Halbach Magnetic <span class="hlt">Bearing</span> is useful for very high speed applications including turbines, instrumentation, medical applications, manufacturing equipment, and space power systems such as flywheels. Magnetic fields suspend and support a rotor assembly within a stator. Advanced technologies developed for particle accelerators, and currently under development for maglev trains and rocket launchers, served as the basis for this application. Experimental hardware was successfully designed and developed to validate the basic principles and analyses. The report concludes that the implementation of Radial Halbach Magnetic <span class="hlt">Bearings</span> can provide significant improvements in rotational system performance and reliability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060028452','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060028452"><span>Development and Testing of an Axial Halbach Magnetic <span class="hlt">Bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.</p> <p>2006-01-01</p> <p>The NASA Glenn Research Center has developed and tested a revolutionary Axial Halbach Magnetic <span class="hlt">Bearing</span>. The objective of this work is to develop a viable non-<span class="hlt">contact</span> magnetic thrust <span class="hlt">bearing</span> utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help to reduce harmful emissions, reduce the Nation s dependence on fossil fuels and mitigate many of the concerns and limitations encountered in conventional axial <span class="hlt">bearings</span> such as <span class="hlt">bearing</span> wear, leaks, seals and friction loss. The Axial Halbach Magnetic <span class="hlt">Bearing</span> is inherently stable and requires no active feedback control system or superconductivity as required in many magnetic <span class="hlt">bearing</span> designs. The Axial Halbach Magnetic <span class="hlt">Bearing</span> is useful for very high speed applications including turbines, instrumentation, medical systems, computer memory systems, and space power systems such as flywheels. Magnetic fields suspend and support a rotor assembly within a stator. Advanced technologies developed for particle accelerators, and currently under development for maglev trains and rocket launchers, served as the basis for this application. Experimental hardware was successfully designed and developed to validate the basic principles and analyses. The report concludes that the implementation of Axial Halbach Magnetic <span class="hlt">Bearings</span> can provide significant improvements in rotational system performance and reliability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930022481','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930022481"><span>Lubrication of an 85-mm ball <span class="hlt">bearing</span> with RP-1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Addy, Harold E., Jr.; Schuller, Frederick T.</p> <p>1993-01-01</p> <p>A parametric experimental investigation of an 85 millimeter bore angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span> running in RP-1 fuel was performed at speeds of 10000 to 24000 RPM. Thrust loads were varied from 4450 to 17800 Newtons (1000 to 4000 lbs.). Radial loads were varied from 1335 to 13350 Newtons (300 to 3000 lbs.). RP-1 lubrication for the <span class="hlt">bearing</span> was provided through a stationary jet ring located adjacent to the test <span class="hlt">bearing</span> outer ring. Increases in both the thrust and radial loads resulted in increased <span class="hlt">bearing</span> temperature, while increases in shaft speed resulted in much more dramatic increases in <span class="hlt">bearing</span> temperature. These trends are typical for ball <span class="hlt">bearings</span> operating under these types of conditions. Results are given for outer ring temperatures of the test <span class="hlt">bearing</span> at the various test conditions employed. In addition, the heat energy removed from the <span class="hlt">bearing</span> by the RP-1 was determined by measuring the increase in temperature as the RP-1 passed through the <span class="hlt">bearing</span>. Results showed that the amount of heat energy removed by the RP-1 increased with both shaft speed and RP-1 flow rate to the <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930069593&hterms=mm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930069593&hterms=mm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmm"><span>Lubrication of an 85-mm ball <span class="hlt">bearing</span> with RP-1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Addy, Harold E., Jr.; Schuller, Fredrick T.</p> <p>1993-01-01</p> <p>A parametric experimental investigation of an 85 millimeter bore angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span> running in RP-1 fuel was performed at speeds of 10,000 to 24,000 rpm. Thrust loads were varied from 4450 to 17,800 Newtons (1000 to 4000 lbs.). Radial loads were varied from 1335 to 13,350 Newtons (300 to 3000 lbs.). RP-1 lubrication for the <span class="hlt">bearing</span> was provided through a stationary jet ring located adjacent to the test <span class="hlt">bearing</span> outer ring. Increases in both the thrust and radial loads resulted in increased <span class="hlt">bearing</span> temperature, while increases in shaft speed resulted in much more dramatic increases in <span class="hlt">bearing</span> temperature. These trends are typical for ball <span class="hlt">bearings</span> operating under these types of conditions. Results are given for outer ring temperatures of the test <span class="hlt">bearing</span> at the various test conditions employed. In addition, the heat energy removed from the <span class="hlt">bearing</span> by the RP-1 was determined by measuring the increase in temperature as the RP-1 passed through the <span class="hlt">bearing</span>. Results showed that the amount of heat energy removed by the RP-1 increased with both shaft speed and RP-1 flow rate to the <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800009208','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800009208"><span>Simplified fatigue life analysis for traction drive <span class="hlt">contacts</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rohn, D. A.; Loewenthal, S. H.; Coy, J. J.</p> <p>1980-01-01</p> <p>A simplified fatigue life analysis for traction drive <span class="hlt">contacts</span> of arbitrary geometry is presented. The analysis is based on the Lundberg-Palmgren theory used for rolling-element <span class="hlt">bearings</span>. The effects of torque, element size, speed, <span class="hlt">contact</span> ellipse ratio, and the influence of traction coefficient are shown. The analysis shows that within the limits of the available traction coefficient, traction <span class="hlt">contacts</span> exhibit longest life at high speeds. Multiple, load-sharing roller arrangements have an advantageous effect on system life, torque capacity, power-to-weight ratio and size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790009052','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790009052"><span>High speed cylindrical roller <span class="hlt">bearing</span> analysis, SKF computer program CYBEAN. Volume 2: User's manual</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kleckner, R. J.; Pirvics, J.</p> <p>1978-01-01</p> <p>The CYBEAN (Cylindrical <span class="hlt">Bearing</span> Analysis) was created to detail radially loaded, aligned and misaligned cylindrical roller <span class="hlt">bearing</span> performance under a variety of operating conditions. Emphasis was placed on detailing the effects of high speed, preload and system thermal coupling. Roller tilt, skew, radial, circumferential and axial displacement as well as flange <span class="hlt">contact</span> were considered. Variable housing and flexible out-of-round outer ring geometries, and both steady state and time transient temperature calculations were enabled. The complete range of elastohydrodynamic <span class="hlt">contact</span> considerations, employing full and partial film conditions were treated in the computation of raceway and flange <span class="hlt">contacts</span>. Input and output architectures containing guidelines for use and a sample execution are detailed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18538328','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18538328"><span>In vivo <span class="hlt">contact</span> kinematics and <span class="hlt">contact</span> forces of the knee after total knee arthroplasty during dynamic weight-<span class="hlt">bearing</span> activities.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Varadarajan, Kartik M; Moynihan, Angela L; D'Lima, Darryl; Colwell, Clifford W; Li, Guoan</p> <p>2008-07-19</p> <p>Analysis of polyethylene component wear and implant loosening in total knee arthroplasty (TKA) requires precise knowledge of in vivo articular motion and loading conditions. This study presents a simultaneous in vivo measurement of tibiofemoral articular <span class="hlt">contact</span> forces and <span class="hlt">contact</span> kinematics in three TKA patients. These measurements were accomplished via a dual fluoroscopic imaging system and instrumented tibial implants, during dynamic single leg lunge and chair rising-sitting. The measured forces and <span class="hlt">contact</span> locations were also used to determine mediolateral distribution of axial <span class="hlt">contact</span> forces. <span class="hlt">Contact</span> kinematics data showed a medial pivot during flexion of the knee, for all patients in the study. Average axial forces were higher for lunge compared to chair rising-sitting (224% vs. 187% body weight). In this study, we measured peak anteroposterior and mediolateral forces averaging 13.3% BW during lunge and 18.5% BW during chair rising-sitting. Mediolateral distributions of axial <span class="hlt">contact</span> force were both patient and activity specific. All patients showed equitable medial-lateral loading during lunge but greater loads at the lateral compartment during chair rising-sitting. The results of this study may enable more accurate reproduction of in vivo loads and articular motion patterns in wear simulators and finite element models. This in turn may help advance our understanding of factors limiting longevity of TKA implants, such as aseptic loosening and polyethylene component wear, and enable improved TKA designs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSV...406..124W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSV...406..124W"><span>Dynamic modeling of moment wheel assemblies with nonlinear rolling <span class="hlt">bearing</span> supports</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Hong; Han, Qinkai; Luo, Ruizhi; Qing, Tao</p> <p>2017-10-01</p> <p>Moment wheel assemblies (MWA) have been widely used in spacecraft attitude control and large angle slewing maneuvers over the years. Understanding and controlling vibration of MWAs is a crucial factor to achieving the desired level of payload performance. Dynamic modeling of a MWA with nonlinear rolling <span class="hlt">bearing</span> supports is conducted. An improved load distribution analysis is proposed to more accurately obtain the <span class="hlt">contact</span> deformations and angles between the rolling balls and raceways. Then, the <span class="hlt">bearing</span> restoring forces are then obtained through iteratively solving the load distribution equations at every time step. The effects of preload condition, surface waviness, Hertz <span class="hlt">contact</span> and elastohydrodynamic lubrication could all be reflected in the nonlinear <span class="hlt">bearing</span> forces. Considering the mass imbalances of the flywheel, flexibility of supporting structures and rolling <span class="hlt">bearing</span> nonlinearity, the dynamic model of a typical MWA is established based upon the energy theorem. Dynamic tests are conducted to verify the nonlinear dynamic model. The influences of flywheel mass eccentricity and inner/outer waviness amplitudes on the dynamic responses are discussed in detail. The obtained results would be useful for the design and vibration control of the MWA system.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150021781','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150021781"><span>Development and Evaluation of Titanium Space Suit <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rhodes, Richard; Battisti, Brian; Ytuarte, Ray, Jr.; Schultz, Bradley</p> <p>2016-01-01</p> <p>The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z series of spacesuits, designed with the intent of meeting a wide variety of exploration mission objectives, including human exploration of the Martian surface. Incorporating titanium <span class="hlt">bearings</span> into the Z series space suit architecture allows us to reduce mass by an estimated 23 pounds per suit system compared to the previously used stainless steel <span class="hlt">bearing</span> designs without compromising suit functionality. There are two obstacles to overcome when using titanium for a <span class="hlt">bearing</span> race: 1) titanium is flammable when exposed to the oxygen wetted environment inside the space suit and 2) titanium's poor wear properties are often challenging to overcome in tribology applications. In order to evaluate the ignitability of a titanium space suit <span class="hlt">bearing</span>, a series of tests were conducted at White Sands Test Facility that introduced the <span class="hlt">bearings</span> to an extreme test profile, with multiple failures imbedded into the test <span class="hlt">bearings</span>. The testing showed no signs of ignition in the most extreme test cases; however, substantial wear of the <span class="hlt">bearing</span> races was observed. In order to design a <span class="hlt">bearing</span> that can last an entire exploration mission (approximately 2 years), <span class="hlt">bearing</span> test rigs were developed that allow for the quick evaluation of various <span class="hlt">bearing</span> ball loads, ball diameters, lubricants, and surface treatments. This test data will allow designers to minimize the titanium <span class="hlt">bearing</span> mass for a specific material and lubricant combination around a maximum <span class="hlt">contact</span> stress that will allow the <span class="hlt">bearing</span> to survive the life of an exploration mission. This paper reviews the current research and testing that has been performed on titanium <span class="hlt">bearing</span> races to evaluate the use of such materials in an enriched oxygen environment and to optimize the <span class="hlt">bearing</span> assembly mass and tribological properties to accommodate for the high <span class="hlt">bearing</span> cycle life for an exploration mission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010018968','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010018968"><span>Rolling <span class="hlt">Bearing</span> Life Prediction-Past, Present, and Future</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, E V; Poplawski, J. V.; Miller, C. R.</p> <p>2000-01-01</p> <p>Comparisons were made between the life prediction formulas of Lundberg and Palmgren, Ioannides and Harris, and Zaretsky and full-scale ball and roller <span class="hlt">bearing</span> life data. The effect of Weibull slope on <span class="hlt">bearing</span> life prediction was determined. Life factors are proposed to <span class="hlt">adjust</span> the respective life formulas to the normalized statistical life distribution of each <span class="hlt">bearing</span> type. The Lundberg-Palmgren method resulted in the most conservative life predictions compared to Ioannides and Harris, and Zaretsky methods which produced statistically similar results. Roller profile can have significant effects on <span class="hlt">bearing</span> life prediction results. Roller edge loading can reduce life by as much as 98 percent. The resultant predicted life not only depends on the life equation used but on the Weibull slope assumed, the least variation occurring with the Zaretsky equation. The load-life exponent p of 10/3 used in the American National Standards Institute (ANSI)/American <span class="hlt">Bearing</span> Manufacturers Association (ABMA)/International Organization for Standardization (ISO) standards is inconsistent with the majority roller <span class="hlt">bearings</span> designed and used today.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12382971','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12382971"><span>Particle size and morphology of UHMWPE wear debris in failed total knee arthroplasties--a comparison between mobile <span class="hlt">bearing</span> and fixed <span class="hlt">bearing</span> knees.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Chun-Hsiung; Ho, Fang-Yuan; Ma, Hon-Ming; Yang, Chan-Tsung; Liau, Jiann-Jong; Kao, Hung-Chan; Young, Tai-Horng; Cheng, Cheng-Kung</p> <p>2002-09-01</p> <p>Osteolysis induced by ultrahigh molecular weight polyethylene wear debris has been recognized as the major cause of long-term failure in total joint arthroplasties. In a previous study, the prevalence of intraoperatively identified osteolysis during primary revision surgery was much higher in mobile <span class="hlt">bearing</span> knee replacements (47%) than in fixed <span class="hlt">bearing</span> knee replacements (13%). We postulated that mobile <span class="hlt">bearing</span> knee implants tend to produce smaller sized particles. In our current study, we compared the particle size and morphology of polyethylene wear debris between failed mobile <span class="hlt">bearing</span> and fixed <span class="hlt">bearing</span> knees. Tissue specimens from interfacial and lytic regions were extracted during revision surgery of 10 mobile <span class="hlt">bearing</span> knees (all of the low <span class="hlt">contact</span> stress (LCS) design) and 17 fixed <span class="hlt">bearing</span> knees (10 of the porous-coated anatomic (PCA) and 7 of the Miller/Galante design). Polyethylene particles were isolated from the tissue specimens and examined using both scanning electron microscopy and light-scattering analyses. The LCS mobile <span class="hlt">bearing</span> knees produced smaller particulate debris (mean equivalent spherical diameter: 0.58 microm in LCS, 1.17 microm in PCA and 5.23 microm in M/G) and more granular debris (mean value: 93% in LCS, 77% in PCA and 15% in M/G).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JPhD...43v5301V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JPhD...43v5301V"><span>Head-disk interface nanotribology for Tbit/inch2 recording densities: near-<span class="hlt">contact</span> and <span class="hlt">contact</span> recording</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vakis, Antonis I.; Polycarpou, Andreas A.</p> <p>2010-06-01</p> <p>In the effort to achieve Tbit/inch2 recording densities, thermal fly-height control (TFC) nanotechnology was developed to effectively reduce the clearance (which is of the order of a few nanometres) at the head-disk interface (HDI) of hard-disk drives. In this work, we present a model of the HDI that can predict the dynamic flying and nanotribological <span class="hlt">contacting</span> behaviour, allowing for accurate predictions and characterization of the operating regime as a function of TFC actuation. A geometric model for TFC is presented and an improved definition of <span class="hlt">contact</span> at the interface is developed in the presence of nanoscale topographical roughness and dynamic microwaviness. A new methodology is proposed for the calculation of the nominal area of <span class="hlt">contact</span>, which affects both near- and at-<span class="hlt">contact</span> behaviour, while the stiffening of the air <span class="hlt">bearing</span> force with TFC actuation is also accounted for. Slider behaviour is analysed by quantifying the approach, jump-to-<span class="hlt">contact</span>, lubricant and solid <span class="hlt">contact</span> regimes of operation and identifying the critical and optimum TFC actuations. The feasibility of near-<span class="hlt">contact</span>, light molecularly thin lubricant <span class="hlt">contact</span> versus solid <span class="hlt">contact</span> recording is explored under the effect of the interfacial forces and stresses present at the HDI. The clearance and the state of vibrations are analysed and design guidelines are proposed for improved performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-05-04/pdf/2010-10439.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-05-04/pdf/2010-10439.pdf"><span>75 FR 23667 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-05-04</p> <p>... DEPARTMENT OF AGRICULTURE Foreign Agricultural Service Trade <span class="hlt">Adjustment</span> Assistance for Farmers... accepted a petition, and began review of a petition, for trade <span class="hlt">adjustment</span> assistance by the Prune...-0876. FOR FURTHER INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance Staff, FAS, USDA, at (202) 720-0638...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160003089','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160003089"><span>Development and Evaluation of Titanium Spacesuit <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rhodes, Richard; Battisti, Brian; Ytuarte, Raymond, Jr.; Schultz, Bradley</p> <p>2016-01-01</p> <p>The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z-series of spacesuits, designed with the intent of meeting a wide variety of exploration mission objectives, including human exploration of the Martian surface. Incorporating titanium <span class="hlt">bearings</span> into the Z-series space suit architecture allows us to reduce mass by an estimated 23 lbs per suit system compared to the previously used stainless steel <span class="hlt">bearing</span> race designs, without compromising suit functionality. There are two obstacles to overcome when using titanium for a <span class="hlt">bearing</span> race- 1) titanium is flammable when exposed to the oxygen wetted environment inside the space suit and 2) titanium's poor wear properties are often challenging to overcome in tribology applications. In order to evaluate the ignitability of a titanium space suit <span class="hlt">bearing</span>, a series of tests were conducted at White Sands Test Facility (WSTF) that introduced the <span class="hlt">bearings</span> to an extreme test profile, with multiple failures imbedded into the test <span class="hlt">bearings</span>. The testing showed no signs of ignition in the most extreme test cases; however, substantial wear of the <span class="hlt">bearing</span> races was observed. In order to design a <span class="hlt">bearing</span> that can last an entire exploration mission (approx. 3 years), design parameters for maximum <span class="hlt">contact</span> stress need to be identified. To identify these design parameters, <span class="hlt">bearing</span> test rigs were developed that allow for the quick evaluation of various <span class="hlt">bearing</span> ball loads, ball diameters, lubricants, and surface treatments. This test data will allow designers to minimize the titanium <span class="hlt">bearing</span> mass for a specific material and lubricant combination and design around a cycle life requirement for an exploration mission. This paper reviews the current research and testing that has been performed on titanium <span class="hlt">bearing</span> races to evaluate the use of such materials in an enriched oxygen environment and to optimize the <span class="hlt">bearing</span> assembly mass and tribological properties to accommodate for the high <span class="hlt">bearing</span> cycle life for an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120012857','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120012857"><span>Foil <span class="hlt">Bearing</span> Starting Considerations and Requirements for Rotorcraft Engine Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Radil, Kevin C.; DellaCorte, Christopher</p> <p>2009-01-01</p> <p>Foil gas <span class="hlt">bearings</span> under development for rotorcraft-sized, hot core engine applications have been susceptible to damage from the slow acceleration and rates typically encountered during the pre-ignition stage in conventional engines. Recent laboratory failures have been assumed to be directly linked to operating foil <span class="hlt">bearings</span> below their lift-off speed while following conventional startup procedures for the engines. In each instance, the continuous sliding <span class="hlt">contact</span> between the foils and shaft was believed to thermally overload the <span class="hlt">bearing</span> and cause the engines to fail. These failures highlight the need to characterize required acceleration rates and minimum operating speeds for these applications. In this report, startup experiments were conducted with a large, rotorcraft engine sized foil <span class="hlt">bearing</span> under moderate load and acceleration rates to identify the proper start procedures needed to avoid <span class="hlt">bearing</span> failure. The results showed that a <span class="hlt">bearing</span> under a 39.4 kPa static load can withstand a modest acceleration rate of 500 rpm/s and excessive loitering below the <span class="hlt">bearing</span> lift-off speed provided an adequate solid lubricant is present.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860010145','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860010145"><span>Effect on interference fits on roller <span class="hlt">bearing</span> fatigue life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coe, H. H.; Zaretsky, E. V.</p> <p>1986-01-01</p> <p>An analysis was performed to determine the effects of inner-ring speed and press fits on roller <span class="hlt">bearing</span> fatigue life. The effects of the resultant hoop and radial stresses on the principal stresses were considered. The maximum shear stresses below the Hertzian <span class="hlt">contact</span> were determined for different conditions of inner-ring speed and load, and were applied to a conventional roller <span class="hlt">bearing</span> life analysis. The effect of mean stress was determined using Goodman diagram approach. Hoop stresses caused by press fits and centrifugal force can reduce <span class="hlt">bearing</span> life by as much as 90 percent. Use of a Goodman diagram predicts life reductions of 20 to 30 percent. The depth of the maximum shear stress remains virtually unchanged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870050412&hterms=press+fit&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpress%2Bfit','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870050412&hterms=press+fit&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpress%2Bfit"><span>Effect of interference fits on roller <span class="hlt">bearing</span> fatigue life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coe, Harold H.; Zaretsky, Erwin V.</p> <p>1987-01-01</p> <p>An analysis was performed to determine the effects of inner-ring speed and press fits on roller <span class="hlt">bearing</span> fatigue life. The effects of the resultant hoop and radial stresses on the principal stresses were considered. The maximum shear stresses below the Hertzian <span class="hlt">contact</span> were determined for different conditions of inner-ring speed and load, and were applied to a conventional roller <span class="hlt">bearing</span> life analysis. The effect of mean stress was determined using Goodman diagram approach. Hoop stresses caused by press fits and centrifugal force can reduce <span class="hlt">bearing</span> life by as much as 90 percent. Use of a Goodman diagram predicts life reduction of 20 to 30 percent. The depth of the maximum shear stress remains virtually unchanged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-09-26/pdf/2011-24553.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-09-26/pdf/2011-24553.pdf"><span>76 FR 59483 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2011-09-26</p> <p>... the decision may be purchased by <span class="hlt">contacting</span> the Office of Public Assistance, Governmental Affairs, and...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the fourth quarter 2011 Rail Cost <span class="hlt">Adjustment</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/874969','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/874969"><span>Method of forming fluorine-<span class="hlt">bearing</span> diamond layer on substrates, including tool substrates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Chang, R. P. H.; Grannen, Kevin J.</p> <p>2002-01-01</p> <p>A method of forming a fluorine-<span class="hlt">bearing</span> diamond layer on non-diamond substrates, especially on tool substrates comprising a metal matrix and hard particles, such as tungsten carbide particles, in the metal matrix. The substrate and a fluorine-<span class="hlt">bearing</span> plasma or other gas are then <span class="hlt">contacted</span> under temperature and pressure conditions effective to nucleate fluorine-<span class="hlt">bearing</span> diamond on the substrate. A tool insert substrate is treated prior to the diamond nucleation and growth operation by etching both the metal matrix and the hard particles using suitable etchants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-06-25/pdf/2012-15407.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-06-25/pdf/2012-15407.pdf"><span>77 FR 37958 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-06-25</p> <p>..., http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the Office of Public...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the third quarter 2012 rail cost <span class="hlt">adjustment</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-09-23/pdf/2010-23814.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-09-23/pdf/2010-23814.pdf"><span>75 FR 58019 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-09-23</p> <p>..., http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the office of Public...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the fourth quarter 2010 Rail Cost <span class="hlt">Adjustment</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-12-23/pdf/2010-32366.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-12-23/pdf/2010-32366.pdf"><span>75 FR 80895 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-12-23</p> <p>..., http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the Office of Public...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the first quarter 2011 Rail Cost <span class="hlt">Adjustment</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-03-22/pdf/2011-6632.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-03-22/pdf/2011-6632.pdf"><span>76 FR 16037 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2011-03-22</p> <p>..., http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the Office of Public...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the second quarter 2011 Rail Cost <span class="hlt">Adjustment</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-06-21/pdf/2013-14876.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-06-21/pdf/2013-14876.pdf"><span>78 FR 37660 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-06-21</p> <p>..., http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the Office of Public...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board approves the third quarter 2013 Rail Cost <span class="hlt">Adjustment</span> Factor...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-06-24/pdf/2011-15781.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-06-24/pdf/2011-15781.pdf"><span>76 FR 37191 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2011-06-24</p> <p>... our Web site, http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the third quarter 2011 Rail Cost <span class="hlt">Adjustment</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-03-22/pdf/2013-06662.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-03-22/pdf/2013-06662.pdf"><span>78 FR 17764 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-03-22</p> <p>..., http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the Office of Public...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the second quarter 2013 Rail Cost <span class="hlt">Adjustment</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15384998','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15384998"><span>Concept for a new hydrodynamic blood <span class="hlt">bearing</span> for miniature blood pumps.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kink, Thomas; Reul, Helmut</p> <p>2004-10-01</p> <p>The most crucial element of a long-term implantable rotary blood pump is the rotor <span class="hlt">bearing</span>. Because of heat generation and power loss resulting from friction, seals within the devices have to be avoided. Actively controlled magnetic <span class="hlt">bearings</span>, although maintenance-free, increase the degree of complexity. Hydrodynamic <span class="hlt">bearings</span> for magnetically coupled rotors may offer an alternative solution to this problem. Additionally, for miniature pumps, the load capacity of hydrodynamic <span class="hlt">bearings</span> scales slower than that of, for example, magnetic <span class="hlt">bearings</span> because of the cube-square-law. A special kind of hydrodynamic <span class="hlt">bearing</span> is a spiral groove <span class="hlt">bearing</span> (SGB), which features an excellent load capacity. Mock-loop tests showed that SGBs do not influence the hydraulic performance of the tested pumps. Although, as of now, the power consumption of the SBG is higher than for a mechanical pivot <span class="hlt">bearing</span>, it is absolutely <span class="hlt">contact</span>-free and has an unlimited lifetime. The liftoff of the rotor occurs already at 10% of design speed. Further tests and flow visualization studies on scaled-up models must demonstrate its overall blood compatibility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16636354','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16636354"><span>Tibiofemoral <span class="hlt">contact</span> mechanics after serial medial meniscectomies in the human cadaveric knee.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Stephen J; Aadalen, Kirk J; Malaviya, Prasanna; Lorenz, Eric P; Hayden, Jennifer K; Farr, Jack; Kang, Richard W; Cole, Brian J</p> <p>2006-08-01</p> <p>There is no consensus regarding the extent of meniscectomy leading to deleterious effects on tibiofemoral <span class="hlt">contact</span> mechanics. The meniscus aids in optimizing tibiofemoral <span class="hlt">contact</span> mechanics, increasing <span class="hlt">contact</span> area, and decreasing <span class="hlt">contact</span> stress. Controlled laboratory study. Twelve fresh-frozen human cadaveric knees each underwent 15 separate testing conditions-5 serial 20-mm posterior medial meniscectomy conditions (intact, 50% radial width, 75% radial width, segmental, and total meniscectomy) at 3 flexion angles (0 degrees , 30 degrees , and 60 degrees )-under an 1800-N axial load. Tekscan sensors were used to measure total force and medial force, <span class="hlt">contact</span> area, mean <span class="hlt">contact</span> stress, and peak <span class="hlt">contact</span> stress. All posterior medial meniscectomy conditions resulted in significantly decreased <span class="hlt">contact</span> areas and increased mean and peak <span class="hlt">contact</span> stresses compared with the intact state (P < .05). The changes in <span class="hlt">contact</span> mechanics after segmental and total posterior medial meniscectomies were not statistically different (P > .05). Incremental changes in <span class="hlt">contact</span> area and mean <span class="hlt">contact</span> stress increased as more peripheral portions of the medial meniscus were removed, whereas peak <span class="hlt">contact</span> stresses exhibited similar incremental changes throughout all meniscectomy conditions. The meniscus is a crucial load-<span class="hlt">bearing</span> structure, optimizing <span class="hlt">contact</span> area and minimizing <span class="hlt">contact</span> stress. Loss of hoop tension (ie, segmental meniscectomy) is equivalent to total meniscectomy in load-<span class="hlt">bearing</span> terms. The peripheral portion of the medial meniscus provides a greater contribution to increasing <span class="hlt">contact</span> areas and decreasing mean <span class="hlt">contact</span> stresses than does the central portion, whereas peak <span class="hlt">contact</span> stresses increase proportionally to the amount of meniscus removed. Because the degree of meniscectomy leading to clinically significant outcomes is unknown, a prudent strategy is to preserve the greatest amount of meniscus possible.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970021436','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970021436"><span>High Temperature Superconducting <span class="hlt">Bearings</span> for Lunar Telescope Mounts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lamb, Mark; BuiMa, Ki; Cooley, Rodger; Mackey, Daniel; Meng, Ruling; Chu, Ching Wu; Chu, Wei Kan; Chen, Peter C.; Wilson, Thomas</p> <p>1995-01-01</p> <p>A telescope to be installed on the lunar surface in the near future must work in a cold and dusty vacuum environment for long periods without on site human maintenance. To track stars, the drive mechanism must be capable of exceedingly fine steps and repeatability. Further, the use of lightweight telescopes for obvious economic benefits burdens the requirement for stable support and rotation. Conventional <span class="hlt">contact</span> <span class="hlt">bearings</span> and gear drives have numerous failure modes under such a restrictive and harsh environment. However, hybrid superconducting magnetic <span class="hlt">bearings</span> (HSMB) fit in naturally. These <span class="hlt">bearings</span> are stable, light, passive, and essentially frictionless, allowing high precision electronic positioning control. By passive levitation, the HSMB does not wear out and requires neither maintenance nor power. A prototype illustrating the feasibility of this application is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-09-24/pdf/2012-23480.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-09-24/pdf/2012-23480.pdf"><span>77 FR 58910 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-09-24</p> <p>..., http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the Office of Public...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the fourth quarter 2012 rail cost <span class="hlt">adjustment</span> factor (RCAF...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850018570','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850018570"><span>Powder metallurgy <span class="hlt">bearings</span> for advanced rocket engines</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fleck, J. N.; Killman, B. J.; Munson, H.E.</p> <p>1985-01-01</p> <p>Traditional ingot metallurgy was pushed to the limit for many demanding applications including antifriction <span class="hlt">bearings</span>. New systems require corrosion resistance, better fatigue resistance, and higher toughness. With conventional processing, increasing the alloying level to achieve corrosion resistance results in a decrease in other properties such as toughness. Advanced powder metallurgy affords a viable solution to this problem. During powder manufacture, the individual particle solidifies very rapidly; as a consequence, the primary carbides are very small and uniformly distributed. When properly consolidated, this uniform structure is preserved while generating a fully dense product. Element tests including rolling <span class="hlt">contact</span> fatigue, hot hardness, wear, fracture toughness, and corrosion resistance are underway on eleven candidate P/M <span class="hlt">bearing</span> alloys and results are compared with those for wrought 440C steel, the current SSME <span class="hlt">bearing</span> material. Several materials which offer the promise of a significant improvement in performance were identified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740014027','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740014027"><span>Experimental ball <span class="hlt">bearing</span> dynamics study. [by high speed photography</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Signer, H. R.</p> <p>1973-01-01</p> <p>A photographic method was employed to record the kinematic performance of rolling elements in turbo machinery ball <span class="hlt">bearings</span>. The 110 mm split inner ring test <span class="hlt">bearings</span> had nominal <span class="hlt">contact</span> angles of 26 deg and 34 deg. High speed films were taken at inner ring speeds of 4,000, 8,000 and 12,000 rpm and at thrust loads of 4,448 N and 22,240 N (1,000 and 5,000 lbs). The films were measured and this data reduced to obtain separator speed, ball speed and ball spin axis orientation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA120828','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA120828"><span>Dynamic Testing with the NSWC Three-Degree-of-Freedom Gas <span class="hlt">Bearing</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1982-03-08</p> <p>aerodynamic effects caused by the rate of change of angular variables. The three- degree-of-freedom gas <span class="hlt">bearing</span> support was designed to permit the...Because the model is spinning, a mechanical Initiator woild be unduly complicated. The air jet has been found to be en entirely reliable and effective ...used for all data reduction. The only other diff 1- culty experienced was binding (intermittent stator/ rotor <span class="hlt">contact</span>) Ln the gas <span class="hlt">bear</span>- * Lug after</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-03-23/pdf/2012-7048.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-03-23/pdf/2012-7048.pdf"><span>77 FR 17121 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-03-23</p> <p>... decision may be purchased by <span class="hlt">contacting</span> the Office of Public Assistance, Governmental Affairs, and...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, Department of Transportation. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. [[Page 17122</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992TriTr..35..679S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992TriTr..35..679S"><span>A study of the transient performance of hydrostatic journal <span class="hlt">bearings</span>. I - Test apparatus and facility</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scharrer, J. K.; Tellier, J.; Hibbs, R.</p> <p>1992-10-01</p> <p>A test apparatus was developed for studies of the transient performance of hydrostatic journal <span class="hlt">bearings</span> operating in liquid nitrogen. The data obtained give the number of revolutions of the shaft <span class="hlt">contact</span> before the liftoff and after touchdown as a function of <span class="hlt">bearing</span>/shaft material combinations and operating conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820024092','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820024092"><span>High speed cylindrical roller <span class="hlt">bearing</span> analysis. SKF computer program CYBEAN. Volume 2: User's manual</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dyba, G. J.; Kleckner, R. J.</p> <p>1981-01-01</p> <p>CYBEAN (CYlindrical <span class="hlt">BEaring</span> ANalysis) was created to detail radially loaded, aligned and misaligned cylindrical roller <span class="hlt">bearing</span> performance under a variety of operating conditions. Emphasis was placed on detailing the effects of high speed, preload and system thermal coupling. Roller tilt, skew, radial, circumferential and axial displacement as well as flange <span class="hlt">contact</span> were considered. Variable housing and flexible out-of-round outer ring geometries, and both steady state and time transient temperature calculations were enabled. The complete range of elastohydrodynamic <span class="hlt">contact</span> considerations, employing full and partial film conditions were treated in the computation of raceway and flange <span class="hlt">contacts</span>. The practical and correct implementation of CYBEAN is discussed. The capability to execute the program at four different levels of complexity was included. In addition, the program was updated to properly direct roller-to-raceway <span class="hlt">contact</span> load vectors automatically in those cases where roller or ring profiles have small radii of curvature. Input and output architectures containing guidelines for use and two sample executions are detailed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18845114','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18845114"><span>Protein <span class="hlt">contact</span> dermatitis: allergens, pathogenesis, and management.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Levin, Cheryl; Warshaw, Erin</p> <p>2008-01-01</p> <p>Protein <span class="hlt">contact</span> dermatitis is an allergic skin reaction induced principally by proteins of either animal or plant origin. The clinical presentation is that of a chronic dermatitis, and it is often difficult to differentiate between allergic <span class="hlt">contact</span> dermatitis and other eczematous dermatoses. One distinguishing clinical feature is that acute flares of pruritus, urticaria, edema, or vesiculation are noted minutes after <span class="hlt">contact</span> with the causative substances. Additionally, the patch-test result is typically negative, and the scratch- or prick-test result is positive. The pathogenesis of protein <span class="hlt">contact</span> dermatitis is unclear but may involve a type I (immunoglobulin E [IgE], immediate) hypersensitivity reaction, type IV (cell-mediated delayed) hypersensitivity reaction, and/or a delayed reaction due to IgE-<span class="hlt">bearing</span> Langerhans' cells. Management involves avoidance of the allergen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880006241','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880006241"><span>The determination of equivalent <span class="hlt">bearing</span> loading for the BSMT that simulate SSME high pressure oxidizer turbopump conditions using the SHABERTH/SINDA computer programs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcdonald, Gary H.</p> <p>1987-01-01</p> <p>The MSFC <span class="hlt">bearing</span> seal material tester (BSMT) can be used to evaluate the SSME high pressure oxygen turbopump (HPOTP) <span class="hlt">bearing</span> performance. The four HPOTP <span class="hlt">bearings</span> have both an imposed radial and axial load. These radial and axial loads are caused by the HPOTP's shaft, main impeller, preburner impeller, turbine and by the LOX coolant flow through the <span class="hlt">bearings</span>, respectively. These loads coupled with <span class="hlt">bearing</span> geometry and operating speed can define <span class="hlt">bearing</span> <span class="hlt">contact</span> angle, <span class="hlt">contact</span> Hertz stress, and heat generation rates. The BSMT has the capability of operating at HPOTP shaft speeds, provide proper coolant flowrates but can only apply an axial load. Due to the inability to operate the <span class="hlt">bearings</span> in the BSMT with an applied radial load, it is important to develop an equivalency between the applied axial loads and the actual HPOTP loadings. A shaft-<span class="hlt">bearing</span>-thermal computer code (SHABERTH/SINDA) is used to simulate the BSMT <span class="hlt">bearing</span>-shaft geometry and thermal-fluid operating conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730000164','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730000164"><span>Liquid metal porous matrix sliding electrical <span class="hlt">contact</span>: A concept</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ferguson, H.</p> <p>1973-01-01</p> <p>Concept utilizes porous metal or nonmetal matrix containing liquid metal in porous structure and confines liquid metal to <span class="hlt">contact</span> area between rotor and brush by capillary forces. System may also be used to lubricate <span class="hlt">bearing</span> systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-05-03/pdf/2010-10260.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-05-03/pdf/2010-10260.pdf"><span>75 FR 23227 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-05-03</p> <p>... Service (FAS), today accepted a petition, and began a review of a petition, for trade <span class="hlt">adjustment</span>... <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance Staff, FAS, USDA, at (202) 720-0638, or by e-mail at: [email protected]fas.usda.gov . Additional program information can be obtained at the Web site for the Trade <span class="hlt">Adjustment</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16938012','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16938012"><span>Openness arrangements and psychological <span class="hlt">adjustment</span> in adolescent adoptees.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Von Korff, Lynn; Grotevant, Harold D; McRoy, Ruth G</p> <p>2006-09-01</p> <p>This is the 1st national study to examine whether the level of <span class="hlt">contact</span> between adoptive and birth family members is associated with the behavioral and emotional <span class="hlt">adjustment</span> of adolescents adopted in infancy (n = 92). Adoptive family members were interviewed twice, 8 years apart, to determine the level of <span class="hlt">contact</span> taking place throughout adoptees' childhood and adolescence. The Child Behavior Checklist (T. M. Achenbach, 1991a) and Youth Self-Report (T. M. Achenbach, 1991b) were administered in adolescence. Adoptive parents' reports indicate no significant associations between openness and adolescent <span class="hlt">adjustment</span>. Adoptees experiencing long-term direct <span class="hlt">contact</span> reported significantly lower levels of externalizing than adoptees without <span class="hlt">contact</span>. Adoption policies and legal procedures will best serve families by facilitating voluntary openness agreements that accommodate openness decisions on a case-by-case basis. Copyright (c) 2006 APA, all rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24395396','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24395396"><span>Measuring polyethylene wear in total knee arthroplasty by RSA: differences between weight-<span class="hlt">bearing</span> and non-weight-<span class="hlt">bearing</span> positioning.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>van Ijsseldijk, Emiel A; Valstar, Edward R; Stoel, Berend C; de Ridder, Ruud; Nelissen, Rob G H H; Kaptein, Bart L</p> <p>2014-04-01</p> <p>Measuring the minimum-joint-space-width (mJSW) in total knee arthroplasty (TKA) in Roentgen stereophotogrammetric analysis (RSA) provides valuable information on polyethylene wear, a leading cause for TKA failure. Most existing studies use non-weight-<span class="hlt">bearing</span> (NWB) patient positioning. The latter may compromise mJSW measurements due to knee laxity with subsequent non-<span class="hlt">contact</span> between the TKA components. We investigated the difference in mJSW between weight-<span class="hlt">bearing</span> (WB) and NWB images and the association with mediolateral (ML) knee stability. At one-year follow-up, 23 TKAs were included from an ongoing RSA study, and ML stability was evaluated. For each examination, the mJSW and femoral-tibial <span class="hlt">contact</span> locations were measured. A linear regression model was used to analyze the association between the mJSW difference (NWB-WB) with the ML stability and <span class="hlt">contact</span> locations. The mean mJSW difference was 0.28 mm medially and 0.20 mm laterally. Four TKAs had medium (5-9°) and 19 TKAs had high (<5°) ML stability. A higher mJSW difference was found for TKAs with medium stability (0.36 mm, P = 0.01). In conclusion, mJSW measurements in existing (NWB) RSA studies are influenced by knee laxity, but may still provide information on wear progression based on TKA with high ML stability. A direct comparison of mJSW measurements from WB and NWB data is not possible. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70185041','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70185041"><span>Invariant polar <span class="hlt">bear</span> habitat selection during a period of sea ice loss</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wilson, Ryan R.; Regehr, Eric V.; Rode, Karyn D.; St Martin, Michelle</p> <p>2016-01-01</p> <p>Climate change is expected to alter many species' habitat. A species' ability to <span class="hlt">adjust</span> to these changes is partially determined by their ability to <span class="hlt">adjust</span> habitat selection preferences to new environmental conditions. Sea ice loss has forced polar <span class="hlt">bears</span> (Ursus maritimus) to spend longer periods annually over less productive waters, which may be a primary driver of population declines. A negative population response to greater time spent over less productive water implies, however, that prey are not also shifting their space use in response to sea ice loss. We show that polar <span class="hlt">bear</span> habitat selection in the Chukchi Sea has not changed between periods before and after significant sea ice loss, leading to a 75% reduction of highly selected habitat in summer. Summer was the only period with loss of highly selected habitat, supporting the contention that summer will be a critical period for polar <span class="hlt">bears</span> as sea ice loss continues. Our results indicate that <span class="hlt">bears</span> are either unable to shift selection patterns to reflect new prey use patterns or that there has not been a shift towards polar basin waters becoming more productive for prey. Continued sea ice loss is likely to further reduce habitat with population-level consequences for polar <span class="hlt">bears</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27534959','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27534959"><span>Invariant polar <span class="hlt">bear</span> habitat selection during a period of sea ice loss.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wilson, Ryan R; Regehr, Eric V; Rode, Karyn D; St Martin, Michelle</p> <p>2016-08-17</p> <p>Climate change is expected to alter many species' habitat. A species' ability to <span class="hlt">adjust</span> to these changes is partially determined by their ability to <span class="hlt">adjust</span> habitat selection preferences to new environmental conditions. Sea ice loss has forced polar <span class="hlt">bears</span> (Ursus maritimus) to spend longer periods annually over less productive waters, which may be a primary driver of population declines. A negative population response to greater time spent over less productive water implies, however, that prey are not also shifting their space use in response to sea ice loss. We show that polar <span class="hlt">bear</span> habitat selection in the Chukchi Sea has not changed between periods before and after significant sea ice loss, leading to a 75% reduction of highly selected habitat in summer. Summer was the only period with loss of highly selected habitat, supporting the contention that summer will be a critical period for polar <span class="hlt">bears</span> as sea ice loss continues. Our results indicate that <span class="hlt">bears</span> are either unable to shift selection patterns to reflect new prey use patterns or that there has not been a shift towards polar basin waters becoming more productive for prey. Continued sea ice loss is likely to further reduce habitat with population-level consequences for polar <span class="hlt">bears</span>. © 2016 The Author(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15160802','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15160802"><span>Health-<span class="hlt">adjusted</span> premium subsidies in the Netherlands.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>van de Ven, Wynand P M M; van Vliet, René C J A; Lamers, Leida M</p> <p>2004-01-01</p> <p>The Dutch government has decided to proceed with managed competition in health care. In this paper we report on progress made with health-based risk <span class="hlt">adjustment</span>, a key issue in managed competition. In 2004 both Diagnostic Cost Groups (DCGs) computed from hospital diagnoses only and Pharmacy-based Cost Groups (PCGs) computed from out-patient prescription drugs are used to set the premium subsidies for competing risk-<span class="hlt">bearing</span> sickness funds. These health-based risk <span class="hlt">adjusters</span> appear to be effective and complementary. Risk selection is not a major problem in the Netherlands. Despite the progress made, we are still faced with a full research agenda for risk <span class="hlt">adjustment</span> in the coming years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720000114','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720000114"><span>High speed, self-acting, face-<span class="hlt">contact</span> shaft seal has low leakage and very low wear</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zuk, J.; Ludwig, L. P.; Johnson, R. L.</p> <p>1972-01-01</p> <p>Design adds gas thrust <span class="hlt">bearing</span> to face of conventional face seal. <span class="hlt">Bearing</span> lifts seal's carbon face out of <span class="hlt">contact</span> after startup and establishes thin gas film between sealing surfaces. Operating pressure and speed capabilities are greater than those of conventional face seals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950017975','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950017975"><span>Generation and Computerized Simulation of Meshing and <span class="hlt">Contact</span> of Modified Involute Helical Gears</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, Faydor L.; Chen, Ningxin; Lu, Jian</p> <p>1995-01-01</p> <p>The design and generation of modified involute helical gears that have a localized and stable <span class="hlt">bearing</span> <span class="hlt">contact</span>, and reduced noise and vibration characteristics are described. The localization of the <span class="hlt">bearing</span> <span class="hlt">contact</span> is achieved by the mismatch of the two generating surfaces that are used for generation of the pinion and the gear. The reduction of noise and vibration will be achieved by application of a parabolic function of transmission errors that is able to absorb the almost linear function of transmission errors caused by gear misalignment. The meshing and <span class="hlt">contact</span> of misaligned gear drives can be analyzed by application of computer programs that have been developed. The computations confirmed the effectiveness of the proposed modification of the gear geometry. A numerical example that illustrates the developed theory is provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21680496','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21680496"><span>Polar <span class="hlt">bears</span> in a warming climate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Derocher, Andrew E; Lunn, Nicholas J; Stirling, Ian</p> <p>2004-04-01</p> <p>Polar <span class="hlt">bears</span> (Ursus maritimus) live throughout the ice-covered waters of the circumpolar Arctic, particularly in near shore annual ice over the continental shelf where biological productivity is highest. However, to a large degree under scenarios predicted by climate change models, these preferred sea ice habitats will be substantially altered. Spatial and temporal sea ice changes will lead to shifts in trophic interactions involving polar <span class="hlt">bears</span> through reduced availability and abundance of their main prey: seals. In the short term, climatic warming may improve <span class="hlt">bear</span> and seal habitats in higher latitudes over continental shelves if currently thick multiyear ice is replaced by annual ice with more leads, making it more suitable for seals. A cascade of impacts beginning with reduced sea ice will be manifested in reduced adipose stores leading to lowered reproductive rates because females will have less fat to invest in cubs during the winter fast. Non-pregnant <span class="hlt">bears</span> may have to fast on land or offshore on the remaining multiyear ice through progressively longer periods of open water while they await freeze-up and a return to hunting seals. As sea ice thins, and becomes more fractured and labile, it is likely to move more in response to winds and currents so that polar <span class="hlt">bears</span> will need to walk or swim more and thus use greater amounts of energy to maintain <span class="hlt">contact</span> with the remaining preferred habitats. The effects of climate change are likely to show large geographic, temporal and even individual differences and be highly variable, making it difficult to develop adequate monitoring and research programs. All ursids show behavioural plasticity but given the rapid pace of ecological change in the Arctic, the long generation time, and the highly specialised nature of polar <span class="hlt">bears</span>, it is unlikely that polar <span class="hlt">bears</span> will survive as a species if the sea ice disappears completely as has been predicted by some.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910010126','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910010126"><span>Local Synthesis and Tooth <span class="hlt">Contact</span> Analysis of Face-Milled Spiral Bevel Gears</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, Faydor L.; Zhang, Yi</p> <p>1991-01-01</p> <p>Computerized simulation of meshing and <span class="hlt">bearing</span> <span class="hlt">contact</span> for spiral bevel gears and hypoid gears is a significant achievement that could substantially improve the technology and the quality of the gears. An approach to the synthesis of face-milled spiral bevel gears and their tooth <span class="hlt">contact</span> analysis is presented. The proposed approach is based on the following ideas: application of the principle of local synthesis that provides optimal conditions of meshing and <span class="hlt">contact</span> at the mean <span class="hlt">contact</span> point, M, and in the neighborhood of M; and application of relations between principle directions and curvatures for surfaces being in line <span class="hlt">contact</span> or in point <span class="hlt">contact</span>. The developed local synthesis of gears provides the following: (1) the required gear ratio at M; (2) a localized <span class="hlt">bearing</span> <span class="hlt">contact</span> with the desired direction of the tangent to the <span class="hlt">contact</span> path on gear tooth surface and the desired length of the major axis of <span class="hlt">contact</span> ellipse at M; (3) a predesigned parabolic function of a controlled level for transmission errors which enables absorption of linear functions of transmission errors caused by misalignment and reduces the level of vibrations. The proposed approach does not require either the tilt of the head-cutter for the process of generation or modified roll for the pinion generation. Improved conditions of meshing and <span class="hlt">contact</span> of the gears can be achieved without the above mentioned parameters. A computer program for determination of basic machine-tool settings and tooth <span class="hlt">contact</span> analysis for the designed gears is presented. The approach is illustrated with a numerical example.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/880091','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/880091"><span>Improved Electrical <span class="hlt">Contact</span> For Dowhhole Drilling Networks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron</p> <p>2005-08-16</p> <p>An electrical <span class="hlt">contact</span> system for transmitting information across tool joints while minimizing signal reflections that occur at the tool joints includes a first electrical <span class="hlt">contact</span> comprising an annular resilient material. An annular conductor is embedded within the annular resilient material and has a surface exposed from the annular resilient material. A second electrical <span class="hlt">contact</span> is provided that is substantially equal to the first electrical <span class="hlt">contact</span>. Likewise, the second electrical <span class="hlt">contact</span> has an annular resilient material and an annular conductor. The two electrical <span class="hlt">contacts</span> configured to <span class="hlt">contact</span> one another such that the annular conductors of each come into physical <span class="hlt">contact</span>. The annular resilient materials of each electrical <span class="hlt">contact</span> each have dielectric characteristics and dimensions that are <span class="hlt">adjusted</span> to provide desired impedance to the electrical <span class="hlt">contacts</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20498516','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20498516"><span>A low-friction high-load thrust <span class="hlt">bearing</span> and the human hip joint.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McIlraith, A H</p> <p>2010-06-01</p> <p>A hydrostatic thrust <span class="hlt">bearing</span> operating at a pressure of 130 MPa and with a coefficient of friction rising to 0.004 in 6 days is described. It consists of interleaved oil-coated Mylar and brass sheets, each 0.1 mm thick. At this pressure, the Mylar deforms to reveal a pool of lubricant bounded by <span class="hlt">contacting</span> layers at its edges where the pressure tapers off to zero. Thus, most of the load is borne by the oil so its effective Coulomb (slip-stick) friction is very low. Expressions for the effective coefficient of friction, the area of the solid-to-solid <span class="hlt">contact</span> and the torque needed to rotate the <span class="hlt">bearing</span> are given in terms of its geometry, the viscosity of the lubricant and elapsed time. The mechanism of a <span class="hlt">bearing</span> with similar geometry and properties, the human hip joint, is compared with this plastic <span class="hlt">bearing</span>. While their low friction properties arise from the same basic cause, the different natures of their soft deformable materials lead to the hip joint having a much wider range of action. This work is an example of new engineering leading to a fresh insight into an action of Nature, which in turn suggests an improvement in engineering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930092108','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930092108"><span>Investigation of Wear and Friction Properties Under Sliding Conditions of Some Materials Suitable for Cages of Rolling-<span class="hlt">Contact</span> <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnson, Robert L; Swikert, Max A; Bisson, Edmond E</p> <p>1952-01-01</p> <p>An investigation of wear and friction properties of a number of materials sliding against SAE 52100 steel was conducted. These materials included brass, bronze, beryllium copper, monel, nichrome v, 24s-t aluminum, nodular iron, and gray cast iron. The metals investigated may be useful as possible cage (separator or retainer) materials for rolling-<span class="hlt">contact</span> <span class="hlt">bearings</span> of high-speed turbine engines. The ability of materials to form surface films that prevent welding is a most important factor in both dry friction and boundary lubrication. On the basis of wear and resistance to welding only, the cast irons were the most promising materials investigated; they showed the least wear and the least tendency to surface failure when run dry, and when boundary lubricated they showed the highest load capacity. On the basis of mechanical properties, nodular iron is superior to gray cast iron. Bronze had the lowest friction coefficient under dry sliding conditions. The results with brass, beryllium copper, and aluminum were poor and these materials do not appear, with regard to friction and wear, to be suitable for cages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17689786','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17689786"><span>Factors affecting the impingement angle of fixed- and mobile-<span class="hlt">bearing</span> total knee replacements: a laboratory study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Walker, Peter S; Yildirim, Gokce; Sussman-Fort, Jon; Roth, Jonathan; White, Brian; Klein, Gregg R</p> <p>2007-08-01</p> <p>Maximum flexion-or impingement angle-is defined as the angle of flexion when the posterior femoral cortex impacts the posterior edge of the tibial insert. We examined the effects of femoral component placement on the femur, the slope angle of the tibial component, the location of the femoral-tibial <span class="hlt">contact</span> point, and the amount of internal or external rotation. Posterior and proximal femoral placement, a more posterior femoral-tibial <span class="hlt">contact</span> point, and a more tibial slope all increased maximum flexion, whereas rotation reduced it. A mobile-<span class="hlt">bearing</span> knee gave results similar to those of the fixed-<span class="hlt">bearing</span> knee, but there was no loss of flexion in internal or external rotation if the mobile <span class="hlt">bearing</span> moved with the femur. In the absence of negative factors, a flexion angle of 150 degrees can be reached before impingement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JAMDS...2...71K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JAMDS...2...71K"><span>Mixed Lubrication Simulation of Hydrostatic Spherical <span class="hlt">Bearings</span> for Hydraulic Piston Pumps and Motors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kazama, Toshiharu</p> <p></p> <p>Mixed and fluid film lubrication characteristics of hydrostatic spherical <span class="hlt">bearings</span> for swash-plate-type axial piston pumps and motors are studied theoretically under non-steady-state conditions. The basic equations incorporating interference and <span class="hlt">contact</span> of surface roughness are derived fundamentally through combination of the GW and PC models. Furthermore, a programming code that is applicable to the caulked-socket-type and open-socket-type <span class="hlt">bearings</span> is developed. Effects of caulking, operating conditions, and the <span class="hlt">bearing</span> dimension on the motion of the sphere and tribological performance of the <span class="hlt">bearings</span> are examined. Salient conclusions are the following: The sphere's eccentricity increases in the low supply pressure period. The time-lag of the load change engenders greater motion of the sphere. Caulking of the <span class="hlt">bearing</span> socket suppresses the sphere's motion. The <span class="hlt">bearing</span> stiffness increases and power loss decreases for smaller recess angles. Minimum power loss is given under the condition that the <span class="hlt">bearing</span> socket radius nearly equals the equivalent load radius.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000120452','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000120452"><span>Computerized Generation and Simulation of Meshing and <span class="hlt">Contact</span> of New Type of Novikov-Wildhaber Helical Gears</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, Faydor L.; Feng, Pin-Hao; Lagutin, Sergei A.</p> <p>2000-01-01</p> <p>In this report, we propose a new geometry for low-noise, increased-strength helical gears of the Novikov-Wildhaber type. <span class="hlt">Contact</span> stresses are reduced as a result of their convex-concave gear tooth surfaces. The gear tooth surfaces are crowned in the profile direction to localize <span class="hlt">bearing</span> <span class="hlt">contact</span> and in the longitudinal direction to obtain a parabolic function of transmission errors. Such a function results in the reduction of noise and vibrations. Methods for the generation of the proposed gear tooth surfaces by grinding and hobbing are considered, and a tooth <span class="hlt">contact</span> analysis (TCA) computer program to simulate meshing and <span class="hlt">contact</span> is applied. The report also investigates the influence of misalignment on transmission errors and shift of <span class="hlt">bearing</span> <span class="hlt">contact</span>. Numerical examples to illustrate the developed approaches are proposed. The proposed geometry was patented by Ford/UIC (Serial Number 09-340-824, pending) on June 28, 1999.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-04-06/pdf/2010-7684.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-04-06/pdf/2010-7684.pdf"><span>75 FR 17462 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-04-06</p> <p>... decision may be purchased by <span class="hlt">contacting</span> the office of Public Assistance, Governmental Affairs, and...-2)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the second quarter 2010 Rail Cost...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSV...394..482F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSV...394..482F"><span>Influence of unbalance levels on nonlinear dynamics of a rotor-backup rolling <span class="hlt">bearing</span> system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fonseca, Cesar A.; Santos, Ilmar F.; Weber, Hans I.</p> <p>2017-04-01</p> <p>Rotor drops in magnetic <span class="hlt">bearing</span> and unbalance in rotors have been objective of study for many years. The combination of these two well-known phenomena led to an interesting chaotic response, when the rotor touches the inner race of the back-up <span class="hlt">bearing</span>. The present work explores the nonlinear rotor backup <span class="hlt">bearing</span> dynamics both theoretically and experimentally using a fully instrumented test rig, where the position of shaft, its angular velocity and the <span class="hlt">contact</span> forces between the shaft and the backup <span class="hlt">bearing</span> are sampled at 25 kHz. The test rig is built by a removable passive magnetic <span class="hlt">bearing</span>, which allows for simulation of magnetic <span class="hlt">bearing</span> failure (loss of carrying capacity and rotor fall). The rotor is studied numerically as well as experimentally. A theoretical approach is given beforehand and supplies the basis of the study. Finally the presented results are commented on the point of view of nonlinear dynamics applied to the practical use. The theoretical and numerical analyses are shown through orbit plots, phase plans, Poincaré maps, force response in time and double sided spectrum. The latter is important to characterize the condition at different levels of unbalance between forward and backward whirl. Our preliminary results indicate that for smaller amount of unbalance the rotor swings at the bottom of the <span class="hlt">bearing</span>, the more the unbalance increases, other dynamical behavior occur and some can be extremely harmful, since the rotor can be lifted from the <span class="hlt">contact</span> state and return, starting to impact innumerable times without reaching a steady state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26ES..128a2101C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26ES..128a2101C"><span>The Value Range of <span class="hlt">Contact</span> Stiffness Factor between Pile and Soil Based on Penalty Function</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Sandy H. L.; Wu, Xinliu</p> <p>2018-03-01</p> <p>The value range of <span class="hlt">contact</span> stiffness factor based on penalty function is studied when we use finite element software ANSYS to analyze <span class="hlt">contact</span> problems, take single pile and soil of a certain project for example, the normal <span class="hlt">contact</span> between pile and soil is analyzed with 2D simplified model in horizontal load. The study shows that when adopting linear elastic model to simulate soil, the maximum <span class="hlt">contact</span> pressure and penetration approach steady value as the <span class="hlt">contact</span> stiffness factor increases. The reasonable value range of <span class="hlt">contact</span> stiffness factor reduces as the underlying element thickness decreases, but the rule reverses when refers to the soil stiffness. If choose DP model to simulate soil, the stiffness factor should be magnified 100 times compares to the elastic model regardless of the soil <span class="hlt">bears</span> small force and still in elastic deformation stage or into the plastic deformation stage. When the soil <span class="hlt">bears</span> big force and into plastic deformation stage, the value range of stiffness factor relates to the plastic strain range of the soil, and reduces as the horizontal load increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860022177','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860022177"><span>Evaluation of a hybrid hydrostatic <span class="hlt">bearing</span> for cryogenic turbopump application</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spica, P. W.; Hannum, N. P.; Meyer, S. D.</p> <p>1986-01-01</p> <p>A hybrid hydrostatic <span class="hlt">bearing</span> was designed to operate in liquid hydrogen at speeds to 80,000 rpm and radial loads to 440 n (100 lbf). The <span class="hlt">bearing</span> assembly consisted of a pair of 20-mm angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> encased in a journal, which was in turn supported by a fluid film of liquid hydrogen. The size and operating conditions of the <span class="hlt">bearing</span> were selected to be compatible with the operating requirements of an advanced technology turbopump. Several test parameters were varied to characterize the <span class="hlt">bearing</span>'s steady-state operation. The rotation of the tester shaft was varied between 0 and 80,000 rpm. <span class="hlt">Bearing</span> inlet fluid pressure was varied between 2.07 and 4.48 MPa (300 and 650 psia), while the fluid sump pressure was independently varied between 0.34 and 2.07 MPa (50 and 300 psia). The maximum radial load applied to the <span class="hlt">bearing</span> was 440 N (110 lbf). Measured hybrid-hydrostatic-<span class="hlt">bearing</span> stiffness was 1.5 times greater than predicted, while the fluid flow rate through the <span class="hlt">bearing</span> was 35 to 65 percent less than predicted. Under two-phase fluid conditions, the stiffness was even greater and the flow rate was less. The optimal pressure ratio for the <span class="hlt">bearing</span> should be between 0.2 and 0.55 depending on the balance desired between <span class="hlt">bearing</span> efficiency and stiffness. Startup and shutdown cyclic tests were conducted to demonstrate the ability of the hybrid-hydrostatic-<span class="hlt">bearing</span> assembly to survive at least a 300-firing-duty cycle. For a typical cycle, the shaft was accelerated to 50,000 rpm in 1.8 sec. The <span class="hlt">bearing</span> operated for 337 start-stop cycles without failure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-10-13/pdf/2010-25647.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-10-13/pdf/2010-25647.pdf"><span>75 FR 62759 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-10-13</p> <p>... Service (FAS), denied a petition (No. 2011019) for trade <span class="hlt">adjustment</span> assistance (TAA) for Tilapia filed..., and FAS. After a review, the Administrator determined that the petition was unable to demonstrate the... INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Program Staff, Office of Trade Programs, FAS...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-12-26/pdf/2012-31024.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-12-26/pdf/2012-31024.pdf"><span>77 FR 76169 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-12-26</p> <p>....stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the Office of Public Assistance...)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board, DOT. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the AAR's proposed rebasing calculations and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860004210','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860004210"><span>Lubrication of nonconformal <span class="hlt">contacts</span>. Ph.D. Thesis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jeng, Y. R.</p> <p>1985-01-01</p> <p>Minimum film thickness results for piezoviscous-rigid regime of lubrication are developed for a compressible Newtonian fluid with Roelands viscosity. The results provide a basis for the analysis and design of a wide range of machine elements operating in the piezoviscous-rigid regime of lubrication. A new numerical method of calculating elastic deformation in <span class="hlt">contact</span> stresses is developed using a biquadratic polynomial to approximate the pressure distribution on the whole domain analyzed. The deformation of every node is expressed as a linear combination of the nodal pressures whose coefficients can be combined into an influence coefficient matrix. This approach has the advantages of improved numerical accuracy, less computing time and smaller storage size required for influence matrix. The ideal elastohydrodynamic lubrication is extended to real <span class="hlt">bearing</span> systems in order to gain an understanding of failure mechanisms in machine elements. The improved elastic deformation calculation is successfully incorporated into the EHL numerical scheme. Using this revised numerical technique and the flow factor model developed by Patir and Cheng (1978) the surface roughness effects on the elastohydrodynamic lubrication of point <span class="hlt">contact</span> is considered. Conditions typical of an EHL <span class="hlt">contact</span> in the piezoviscous-elastic regime entrained in pure rolling are investigated. Results are compared with the smooth surface solutions. Experiments are conducted to study the transient EHL effects in instrument ball <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4513606','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4513606"><span>Increased risk of revision of cementless stemmed total hip arthroplasty with metal-on-metal <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pedersen, Alma B; Mäkelä, Keijo; Eskelinen, Antti; Havelin, Leif Ivar; Furnes, Ove; Kärrholm, Johan; Garellick, Göran; Overgaard, Søren</p> <p>2015-01-01</p> <p>Background and purpose Data from the national joint registries in Australia and England and Wales have revealed inferior medium-term survivorship for metal-on-metal (MoM) total hip arthroplasty (THA) than for metal-on-polyethylene (MoP) THA. Based on data from the Nordic Arthroplasty Register Association (NARA), we compared the revision risk of cementless stemmed THA with MoM and MoP <span class="hlt">bearings</span> and we also compared MoM THA to each other. Patients and methods We identified 32,678 patients who were operated from 2002 through 2010 with cementless stemmed THA with either MoM <span class="hlt">bearings</span> (11,567 patients, 35%) or MoP <span class="hlt">bearings</span> (21,111 patients, 65%). The patients were followed until revision, death, emigration, or the end of the study period (December 31, 2011), and median follow-up was 3.6 (interquartile range (IQR): 2.4–4.8) years for MoM <span class="hlt">bearings</span> and 3.4 (IQR: 2.0–5.8) years for MoP <span class="hlt">bearings</span>. Multivariable regression in the presence of competing risk of death was used to assess the relative risk (RR) of revision for any reason (with 95% confidence interval (CI)). Results The cumulative incidence of revision at 8 years of follow-up was 7.0% (CI: 6.0–8.1) for MoM <span class="hlt">bearings</span> and 5.1% (CI: 4.7–5.6) for MoP <span class="hlt">bearings</span>. At 6 years of follow-up, the RR of revision for any reason was 1.5 (CI: 1.3–1.7) for MoM <span class="hlt">bearings</span> compared to MoP <span class="hlt">bearings</span>. The RR of revision for any reason was higher for the ASR (<span class="hlt">adjusted</span> RR = 6.4, CI: 5.0–8.1), the Conserve Plus (<span class="hlt">adjusted</span> RR = 1.7, CI: 1.1–2.5) and “other” acetabular components (<span class="hlt">adjusted</span> RR = 2.4, CI: 1.5–3.9) than for MoP THA at 6 years of follow-up. Interpretation At medium-term follow-up, the survivorship for cementless stemmed MoM THA was inferior to that for MoP THA, and metal-related problems may cause higher revision rates for MoM <span class="hlt">bearings</span> with longer follow-up. PMID:25715878</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890004967','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890004967"><span>Some composite <span class="hlt">bearing</span> and seal materials for gas turbine applications: A review</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sliney, Harold E.</p> <p>1989-01-01</p> <p>A review is made of the selection and tribological testing of materials for high-temperature <span class="hlt">bearings</span> and seals. The goal is to achieve good tribological properties over a wide range of temperatures because <span class="hlt">bearings</span> and seals must be functional from low temperature start-up conditions on up to the maximum temperatures encountered during engine operation. Plasma sprayed composite coatings with favorable tribological properties from 25 to 900 C are discussed. The performance of these coatings in simple tribological bench tests is described. Examples are also given of their performance in high-speed sliding <span class="hlt">contact</span> seals and as Stirling cylinder liner materials, and as back up lubricants for compliant foil gas <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1041796','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1041796"><span>Stability of one-stage <span class="hlt">adjustable</span> suture for the correction of horizontal strabismus.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chow, P C</p> <p>1989-01-01</p> <p>One-stage <span class="hlt">adjustable</span> suture for strabismus correction, with the whole operation done under topical anaesthesia and <span class="hlt">adjustment</span> done on the table, was performed on 45 consecutive patients. The stability of the post-<span class="hlt">adjustment</span> result was studied by comparing the post-<span class="hlt">adjustment</span> deviation on the operating table to that at six weeks and three months after operation. The stability was comparable to that following the usual two-stage <span class="hlt">adjustable</span> suture. The original angle of deviation and the fusion status were found to have no <span class="hlt">bearing</span> on the stability of the procedure. PMID:2667637</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050203794','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050203794"><span>Fail-Safe Operation of a High-Temperature Magnetic <span class="hlt">Bearing</span> Investigated for Gas Turbine Engine Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Choi, Benjamin B.; Montague, Gerald T.</p> <p>2002-01-01</p> <p>The Structural Mechanics and Dynamics Branch at the NASA Glenn Research Center has developed a three-axis high-temperature magnetic <span class="hlt">bearing</span> suspension rig to enhance the safety of the <span class="hlt">bearing</span> system up to 1000 F. This test rig can accommodate thrust and radial <span class="hlt">bearings</span> up to a 22.84 cm (9 in.) diameter with a maximum axial loading of 22.25 kN (5000 lb) and a maximum radial loading up to 4.45 kN (1000 lb). The test facility was set up to test magnetic <span class="hlt">bearings</span> under high-temperature (1100 F) and high-speed (20,000 rpm) conditions. The magnetic <span class="hlt">bearing</span> is located at the center of gravity of the rotor between two high-temperature grease-packed mechanical ball <span class="hlt">bearings</span>. The drive-end duplex angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span>, which is in full <span class="hlt">contact</span>, acts as a moment release and provides axial stability. The outboard end ball <span class="hlt">bearing</span> has a 0.015-in. radial clearance between the rotor to act as a backup <span class="hlt">bearing</span> and to compensate for axial thermal expansion. There is a 0.020-in. radial air gap between the stator pole and the rotor. The stator was wrapped with three 1-kW band heaters to create a localized hot section; the mechanical ball <span class="hlt">bearings</span> were outside this section. Eight threaded rods supported the stator. These incorporated a plunger and Bellville washers to compensate for radial thermal expansion and provide rotor-to-stator alignment. The stator was instrumented with thermocouples and a current sensor for each coil. Eight air-cooled position sensors were mounted outside the hot section to monitor the rotor. Another sensor monitored this rotation of the outboard backup <span class="hlt">bearing</span>. Ground fault circuit interrupts were incorporated into all power amplifier loops for personnel safety. All instrumentation was monitored and recorded on a LabView-based data acquisition system. Currently, this 12-pole heteropolar magnetic <span class="hlt">bearing</span> has 13 thermal cycles and over 26 hr of operation at 1000 F.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940002919&hterms=structured+systems+analysis+design&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dstructured%2Bsystems%2Banalysis%2Bdesign','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940002919&hterms=structured+systems+analysis+design&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dstructured%2Bsystems%2Banalysis%2Bdesign"><span>SHABERTH - ANALYSIS OF A SHAFT <span class="hlt">BEARING</span> SYSTEM (CRAY VERSION)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coe, H. H.</p> <p>1994-01-01</p> <p>The SHABERTH computer program was developed to predict operating characteristics of <span class="hlt">bearings</span> in a multibearing load support system. Lubricated and non-lubricated <span class="hlt">bearings</span> can be modeled. SHABERTH calculates the loads, torques, temperatures, and fatigue life for ball and/or roller <span class="hlt">bearings</span> on a single shaft. The program also allows for an analysis of the system reaction to the termination of lubricant supply to the <span class="hlt">bearings</span> and other lubricated mechanical elements. SHABERTH has proven to be a valuable tool in the design and analysis of shaft <span class="hlt">bearing</span> systems. The SHABERTH program is structured with four nested calculation schemes. The thermal scheme performs steady state and transient temperature calculations which predict system temperatures for a given operating state. The <span class="hlt">bearing</span> dimensional equilibrium scheme uses the <span class="hlt">bearing</span> temperatures, predicted by the temperature mapping subprograms, and the rolling element raceway load distribution, predicted by the <span class="hlt">bearing</span> subprogram, to calculate <span class="hlt">bearing</span> diametral clearance for a given operating state. The shaft-<span class="hlt">bearing</span> system load equilibrium scheme calculates <span class="hlt">bearing</span> inner ring positions relative to the respective outer rings such that the external loading applied to the shaft is brought into equilibrium by the rolling element loads which develop at each <span class="hlt">bearing</span> inner ring for a given operating state. The <span class="hlt">bearing</span> rolling element and cage load equilibrium scheme calculates the rolling element and cage equilibrium positions and rotational speeds based on the relative inner-outer ring positions, inertia effects, and friction conditions. The ball <span class="hlt">bearing</span> subprograms in the current SHABERTH program have several model enhancements over similar programs. These enhancements include an elastohydrodynamic (EHD) film thickness model that accounts for thermal heating in the <span class="hlt">contact</span> area and lubricant film starvation; a new model for traction combined with an asperity load sharing model; a model for the hydrodynamic rolling and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-06-23/pdf/2010-15100.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-06-23/pdf/2010-15100.pdf"><span>75 FR 35877 - Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-06-23</p> <p>... available on our Web site, http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span>...-3)] Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board. ACTION: Approval of rail cost <span class="hlt">adjustment</span> factor. SUMMARY: The Board has approved the third quarter 2010 rail cost...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JSV...420..227M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JSV...420..227M"><span>Nonlinear analysis of a rotor-<span class="hlt">bearing</span> system using describing functions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maraini, Daniel; Nataraj, C.</p> <p>2018-04-01</p> <p>This paper presents a technique for modelling the nonlinear behavior of a rotor-<span class="hlt">bearing</span> system with Hertzian <span class="hlt">contact</span>, clearance, and rotating unbalance. The rotor-<span class="hlt">bearing</span> system is separated into linear and nonlinear components, and the nonlinear <span class="hlt">bearing</span> force is replaced with an equivalent describing function gain. The describing function captures the relationship between the amplitude of the fundamental input to the nonlinearity and the fundamental output. The frequency response is constructed for various values of the clearance parameter, and the results show the presence of a jump resonance in <span class="hlt">bearings</span> with both clearance and preload. Nonlinear hardening type behavior is observed in the case with clearance and softening behavior is observed for the case with preload. Numerical integration is also carried out on the nonlinear equations of motion showing strong agreement with the approximate solution. This work could easily be extended to include additional nonlinearities that arise from defects, providing a powerful diagnostic tool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-06-11/pdf/2010-14112.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-06-11/pdf/2010-14112.pdf"><span>75 FR 33379 - Railroad Cost Recovery Procedures-Productivity <span class="hlt">Adjustment</span>; Quarterly Rail Cost <span class="hlt">Adjustment</span> Factor</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-06-11</p> <p>... information is contained in the Board's June 14, 2010 decision, which is available on our website at http://www.stb.dot.gov . Copies of the decision may be purchased by <span class="hlt">contacting</span> the office of Public... Cost <span class="hlt">Adjustment</span> Factor AGENCY: Surface Transportation Board. [[Page 33380</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24146169','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24146169"><span>Evaluation of the occlusal <span class="hlt">contact</span> of crowns fabricated with the bite impression method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Makino, Sachi; Okada, Daizo; Shin, Chiharu; Ogura, Reiko; Ikeda, Masaomi; Miura, Hiroyuki</p> <p>2013-09-30</p> <p>In prosthodontic treatment, reconstruction of a proper occlusal <span class="hlt">contact</span> relationship is very important as well as reconstruction of a proper interproximal relationship and marginal fitness. Unfortunately, occlusal relationships are sometimes lost in the process of occlusal <span class="hlt">adjustment</span> of crowns. The purpose of this study was to compare the occlusal <span class="hlt">contacts</span> of single crown fabricated by two different types of impression techniques. Nine subjects, whose molars required treatment with crown restoration, were enrolled in this study. Full cast crowns were fabricated using two types of impression techniques: the conventional impression method (CIM) and the bite impression method (BIM). The occlusal <span class="hlt">contacts</span> of crowns were precisely evaluated at the following stages: after occlusal <span class="hlt">adjustment</span> on the articulator (Step 0), before occlusal <span class="hlt">adjustment</span> in the mouth (Step 1), after occlusal <span class="hlt">adjustment</span> at the intercuspal position (Step 2), and after occlusal <span class="hlt">adjustment</span> during lateral and protrusive excursions (Step 3). The number of occlusal <span class="hlt">contacts</span> of the crowns on the functional cusps fabricated with BIM was significantly greater than that with CIM after occlusal <span class="hlt">adjustment</span>. For this reason, the crowns fabricated with BIM might have a more functionally desirable occlusal surface compared to the crowns fabricated with CIM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830011844','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830011844"><span>Corrosion of simulated <span class="hlt">bearing</span> components of three <span class="hlt">bearing</span> steels in the presence of chloride-contaminated lubricant</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, R. J.; Bamberger, E. N.; Nahm, A. H.</p> <p>1983-01-01</p> <p>Corrosion tests were run with AISI 52100, AISI M-50 and AMS 5794 under conditions that simulate the crevice corrosion found in aircraft ball and roller <span class="hlt">bearings</span> rejected at overhaul for corrosion. Test specimens were fabricated that simulated the <span class="hlt">contacts</span> of balls or rollers and the raceways. Corrosion cells were assembled in the presence of a lubricant contaminated with water and chloride ions. The cell was then thermally cycled between 339 K (150 F) and 276 K (37 F). The corrosion observed after 14 cycles was that of crevice and pitting corrosion typically found in aircraft <span class="hlt">bearings</span>. AMS 5749 showed a very slight amount of corrosion. No appreciable differences were noted between AISI 52100 and AISI M-50, but both showed much greater corrosion than AMS 5749. The corrosion pits observed in AISI M-50 appeared to be fewer in number but generally deeper and larger than in AISI 52100.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000032747','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000032747"><span>Performance and Durability of High Temperature Foil Air <span class="hlt">Bearings</span> for Oil-Free Turbomachinery</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DellaCorte, C.; Lukaszewicz, V.; Valco, M. J.; Radil, K. C.; Heshmat, H.</p> <p>2000-01-01</p> <p>The performance and durability of advanced, high temperature foil air <span class="hlt">bearings</span> are evaluated under a wide range (10-50 kPa) of loads at temperatures from 25 to 650 C. The <span class="hlt">bearings</span> are made from uncoated nickel based superalloy foils. The foil surface experiences sliding <span class="hlt">contact</span> with the shaft during initial start/stop operation. To reduce friction and wear, the solid lubricant coating, PS304, is applied to the shaft by plasma spraying. PS304 is a NiCr based Cr2O3 coating with silver and barium fluoride/calcium fluoride solid lubricant additions. The results show that the <span class="hlt">bearings</span> provide lives well in excess of 30,000 cycles under all of the conditions tested. Several <span class="hlt">bearings</span> exhibited lives in excess of 100,000 cycles. Wear is a linear function of the <span class="hlt">bearing</span> load. The excellent performance measured in this study suggests that these <span class="hlt">bearings</span> and the PS304 coating are well suited for advanced high temperature, oil-free turbomachinery applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-07-21/pdf/2010-17804.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-07-21/pdf/2010-17804.pdf"><span>75 FR 42375 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-07-21</p> <p>... Service (FAS) today accepted and began a review of a petition for trade <span class="hlt">adjustment</span> assistance filed under... cash benefits. FOR FURTHER INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Staff, FAS, USDA, by phone: (202) 720-0638, or (202) 690-0633; or by e-mail: [email protected]fas.usda.gov ; or...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-07-16/pdf/2010-17354.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-07-16/pdf/2010-17354.pdf"><span>75 FR 41432 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-07-16</p> <p>... Foreign Agricultural Service (FAS) denied a petition (No. 2010010) for trade <span class="hlt">adjustment</span> assistance (TAA... INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Staff, FAS, USDA, by phone: (202) 720-0638, or (202) 690-0633; or by e-mail: [email protected]fas.usda.gov ; or visit the TAA for Farmers' Web site...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6082466','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6082466"><span>Mounting arrangement for the drive system of an air-<span class="hlt">bearing</span> spindle on a machine tool</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Lunsford, J.S.; Crisp, D.W.; Petrowski, P.L.</p> <p>1987-12-07</p> <p>The present invention is directed to a mounting arrangement for the drive system of an air-<span class="hlt">bearing</span> spindle utilized on a machine tool such as a lathe. The mounting arrangement of the present invention comprises a housing which is secured to the casing of the air <span class="hlt">bearing</span> in such a manner that the housing position can be selectively <span class="hlt">adjusted</span> to provide alignment of the air-<span class="hlt">bearing</span> drive shaft supported by the housing and the air-<span class="hlt">bearing</span> spindle. Once this alignment is achieved the air between spindle and the drive arrangement is maintained in permanent alignment so as to overcome misalignment problems encountered in the operation of the machine tool between the air-<span class="hlt">bearing</span> spindle and the shaft utilized for driving the air-<span class="hlt">bearing</span> spindle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110014729','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110014729"><span>High-Temperature, High-Load-Capacity Radial Magnetic <span class="hlt">Bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Provenza, Andrew; Montague, Gerald; Kascak, Albert; Palazzolo, Alan; Jansen, Ralph; Jansen, Mark; Ebihara, Ben</p> <p>2005-01-01</p> <p>A radial heteropolar magnetic <span class="hlt">bearing</span> capable of operating at a temperature as high as 1,000 F (=540 C) has been developed. This is a prototype of <span class="hlt">bearings</span> for use in gas turbine engines operating at temperatures and speeds much higher than can be withstood by lubricated rolling-element <span class="hlt">bearings</span>. It is possible to increase the maximum allowable operating temperatures and speeds of rolling-element <span class="hlt">bearings</span> by use of cooling-air systems, sophisticated lubrication systems, and rotor-vibration- damping systems that are subsystems of the lubrication systems, but such systems and subsystems are troublesome. In contrast, a properly designed radial magnetic <span class="hlt">bearing</span> can suspend a rotor without <span class="hlt">contact</span>, and, hence, without need for lubrication or for cooling. Moreover, a magnetic <span class="hlt">bearing</span> eliminates the need for a separate damping system, inasmuch as a damping function is typically an integral part of the design of the control system of a magnetic <span class="hlt">bearing</span>. The present high-temperature radial heteropolar magnetic <span class="hlt">bearing</span> has a unique combination of four features that contribute to its suitability for the intended application: 1. The wires in its electromagnet coils are covered with an insulating material that does not undergo dielectric breakdown at high temperature and is pliable enough to enable the winding of the wires to small radii. 2. The processes used in winding and potting of the coils yields a packing factor close to 0.7 . a relatively high value that helps in maximizing the magnetic fields generated by the coils for a given supplied current. These processes also make the coils structurally robust. 3. The electromagnets are of a modular C-core design that enables replacement of components and semiautomated winding of coils. 4. The stator is mounted in such a manner as to provide stable support under radial and axial thermal expansion and under a load as large as 1,000 lb (.4.4 kN).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..147a2007T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..147a2007T"><span>Study on the deterioration origin of thermomechanical <span class="hlt">contact</span> fatigue</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tudose-Sandu-Ville, O. F.</p> <p>2016-08-01</p> <p>Thermomechanical wear is a complex phenomenon present in a number of industrial domains, such as rolling <span class="hlt">bearings</span>, gears, friction wheels, rolling mill rollers. In this type of surface tribological deterioration, both fundamental and some peculiar wears are combined (abrasive, adhesive, corrosive wear and <span class="hlt">contact</span> fatigue), with mechanical ant thermal causes. The present paper takes into account the <span class="hlt">contact</span> fatigue type of deterioration, with both causes in mechanical variable load and the thermal tide action on the <span class="hlt">contact</span> surface. There are some theories synthetically presented regarding the location of critical stresses in rolling <span class="hlt">contact</span> fatigue. The Jacq thermal effect is briefly presented with some considerations concerning the temperature gradient in the metallic wall. The connection between the Jacq thermal anomaly and the thermomechanical <span class="hlt">contact</span> fatigue is considered to be a new approach. Also, the same location for both mechanical and thermal critical stresses gives a strong support for the thermomechanical <span class="hlt">contact</span> fatigue primary deterioration, according to the results obtained during the author's PhD research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003368','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003368"><span>Performance of Simple Gas Foil Thrust <span class="hlt">Bearings</span> in Air</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bruckner, Robert J.</p> <p>2012-01-01</p> <p>Foil <span class="hlt">bearings</span> are self-acting hydrodynamics devices used to support high speed rotating machinery. The advantages that they offer to process fluid lubricated machines include: high rotational speed capability, no auxiliary lubrication system, non-<span class="hlt">contacting</span> high speed operation, and improved damping as compared to rigid hydrodynamic <span class="hlt">bearings</span>. NASA has had a sporadic research program in this technology for almost 6 decades. Advances in the technology and understanding of foil journal <span class="hlt">bearings</span> have enabled several new commercial products in recent years. These products include oil-free turbochargers for both heavy trucks and automobiles, high speed electric motors, microturbines for distributed power generation, and turbojet engines. However, the foil thrust <span class="hlt">bearing</span> has not received a complimentary level of research and therefore has become the weak link of oil-free turbomachinery. In an effort to both provide machine designers with basic performance parameters and to elucidate the underlying physics of foil thrust <span class="hlt">bearings</span>, NASA Glenn Research Center has completed an effort to experimentally measure the performance of simple gas foil thrust <span class="hlt">bearing</span> in air. The database includes simple bump foil supported thrust <span class="hlt">bearings</span> with full geometry and manufacturing techniques available to the user. Test conditions consist of air at ambient pressure and temperatures up to 500 C and rotational speeds to 55,000 rpm. A complete set of axial load, frictional torque, and rotational speed is presented for two different compliant sub-structures and inter-pad gaps. Data obtained from commercially available foil thrust <span class="hlt">bearings</span> both with and without active cooling is presented for comparison. A significant observation made possible by this data set is the speed-load capacity characteristic of foil thrust <span class="hlt">bearings</span>. Whereas for the foil journal <span class="hlt">bearing</span> the load capacity increases linearly with rotational speed, the foil thrust <span class="hlt">bearing</span> operates in the hydrodynamic high speed limit. In</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23613910','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23613910"><span><span class="hlt">Bear</span>-baiting may exacerbate wolf-hunting dog conflict.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bump, Joseph K; Murawski, Chelsea M; Kartano, Linda M; Beyer, Dean E; Roell, Brian J</p> <p>2013-01-01</p> <p>The influence of policy on the incidence of human-wildlife conflict can be complex and not entirely anticipated. Policies for managing <span class="hlt">bear</span> hunter success and depredation on hunting dogs by wolves represent an important case because with increasing wolves, depredations are expected to increase. This case is challenging because compensation for wolf depredation on hunting dogs as compared to livestock is less common and more likely to be opposed. Therefore, actions that minimize the likelihood of such conflicts are a conservation need. We used data from two US states with similar wolf populations but markedly different wolf/hunting dog depredation patterns to examine the influence of <span class="hlt">bear</span> hunting regulations, <span class="hlt">bear</span> hunter to wolf ratios, hunter method, and hunter effort on wolf depredation trends. Results indicated that the ratio of <span class="hlt">bear</span> hunting permits sold per wolf, and hunter method are important factors affecting wolf depredation trends in the Upper Great Lakes region, but strong differences exist between Michigan and Wisconsin related in part to the timing and duration of <span class="hlt">bear</span>-baiting (i.e., free feeding). The probability that a wolf depredated a <span class="hlt">bear</span>-hunting dog increases with the duration of <span class="hlt">bear</span>-baiting, resulting in a relative risk of depredation 2.12-7.22× greater in Wisconsin than Michigan. The net effect of compensation for hunting dog depredation in Wisconsin may also contribute to the difference between states. These results identified a potential tradeoff between <span class="hlt">bear</span> hunting success and wolf/<span class="hlt">bear</span>-hunting dog conflict. These results indicate that management options to minimize conflict exist, such as <span class="hlt">adjusting</span> baiting regulations. If reducing depredations is an important goal, this analysis indicates that actions aside from (or in addition to) reducing wolf abundance might achieve that goal. This study also stresses the need to better understand the relationship among baiting practices, the effect of compensation on hunter behavior, and depredation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780024489','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780024489"><span>Roller to separator <span class="hlt">contact</span> forces and cage to shaft speed ratios in roller <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nypan, L. J.</p> <p>1978-01-01</p> <p>Cage to roller force measurements, cage to shaft speed ratios are reported for 115- and 118-mm bore roller <span class="hlt">bearings</span> operating at speeds of 4000, 8000, and 12,000 rpm under loads ranging from 360 to 6670 N (80 to 1500 lb).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800025241','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800025241"><span>Effect of cage design on characteristics of high-speed-jet-lubricated 35-millimeter-bore ball <span class="hlt">bearing</span>. [turbojet engines</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schuller, F. T.; Pinel, S. I.; Signer, H. R.</p> <p>1980-01-01</p> <p>Parametric tests were conducted with a 35 mm bore angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span> with a double outer land guided cage. Provisions were made for jet lubrication and outer-ring cooling of the <span class="hlt">bearing</span>. Test conditions included a combined thrust and radial load at nominal shaft speeds of 48,000 rpm, and an oil-in temperature of 394 K (250 F). Successful operation of the test <span class="hlt">bearing</span> was accomplished up to 2.5 million DN. Test results were compared with those obtained with similar <span class="hlt">bearing</span> having a single outer land guided cage. Higher temperatures were generated with the double outer land guided cage <span class="hlt">bearing</span>, and <span class="hlt">bearing</span> power loss and cage slip were greater. Cooling the outer ring resulted in a decrease in overall <span class="hlt">bearing</span> operating temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-08-11/pdf/2010-19791.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-08-11/pdf/2010-19791.pdf"><span>75 FR 48642 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-08-11</p> <p>... Service (FAS) today accepted and began a review of a petition for trade <span class="hlt">adjustment</span> assistance filed under... benefits. FOR FURTHER INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Program Staff, FAS, USDA by phone: (202) 720-0638 or (202) 690- 0633; or by e-mail at: [email protected]fas.usda.gov ; or visit...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-08-16/pdf/2010-20315.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-08-16/pdf/2010-20315.pdf"><span>75 FR 49886 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-08-16</p> <p>... Service (FAS) today accepted and began a review of a petition for trade <span class="hlt">adjustment</span> assistance filed under... INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Program Staff, FAS, USDA by phone: (202) 720-0638 or (202) 690- 0633; or by e-mail at: [email protected]fas.usda.gov ; or visit [[Page 49887</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160013905','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160013905"><span>Rolling <span class="hlt">Bearing</span> Life Prediction, Theory, and Application</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, Erwin V.</p> <p>2016-01-01</p> <p> life results using the Lundberg- Palmgren equations with life <span class="hlt">adjustment</span> factors to predict <span class="hlt">bearing</span> life. That is, they had lives equal to or greater than that predicted. The Lundberg-Palmgren model was used to predict the life of a commercial turboprop gearbox. The life prediction was compared with the field lives of 64 gearboxes. From these results, the roller <span class="hlt">bearing</span> lives exhibited a load-life exponent of 5.2, which correlated with the Zaretsky model. The use of the ANSI/ABMA and ISO standards load-life exponent of 10/3 to predict roller <span class="hlt">bearing</span> life is not reflective of modern roller <span class="hlt">bearings</span> and will underpredict <span class="hlt">bearing</span> lives.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SPIE.8884E..0UD','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SPIE.8884E..0UD"><span>Comparison of <span class="hlt">contact</span> and non-<span class="hlt">contact</span> asphere surface metrology devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DeFisher, Scott; Fess, Edward M.</p> <p>2013-09-01</p> <p>Metrology of asphere surfaces is critical in the precision optics industry. Surface metrology serves as feedback into deterministic grinding and polishing platforms. Many different techniques and devices are used to qualify an asphere surface during fabrication. A <span class="hlt">contact</span> profilometer is one of the most common measurement technologies used in asphere manufacturing. A profilometer uses a fine stylus to drag a diamond or ruby tip over the surface, resulting in a high resolution curved profile. Coordinate measuring machines (CMM) apply a similar concept by touching the optic with a ruby or silicon carbine sphere. A CMM is able to move in three dimensions while collecting data points along the asphere surface. Optical interferometers use a helium-neon laser with transmission spheres to compare a reflected wavefront from an asphere surface to a reference spherical wavefront. Large departure aspheres can be measured when a computer generated hologram (CGH) is introduced between the interferometer and the optic. OptiPro Systems has developed a non-<span class="hlt">contact</span> CMM called UltraSurf. It utilizes a single point non-<span class="hlt">contact</span> sensor, and high accuracy air <span class="hlt">bearings</span>. Several different commercial non-<span class="hlt">contact</span> sensors have been integrated, allowing for the flexibility to measure a variety of surfaces and materials. Metrology of a sphere and an asphere using a profilometer, CMM, Interferometer with a CGH, and the UltraSurf will be presented. Cross-correlation of the measured surface error magnitude and shape will be demonstrated. Comparisons between the techniques and devices will be also presented with attention to accuracy, repeatability, and overall measurement time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900002717','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900002717"><span>Generation and tooth <span class="hlt">contact</span> analysis of spiral bevel gears with predesigned parabolic functions of transmission errors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, Faydor L.; Lee, Hong-Tao</p> <p>1989-01-01</p> <p>A new approach for determination of machine-tool settings for spiral bevel gears is proposed. The proposed settings provide a predesigned parabolic function of transmission errors and the desired location and orientation of the <span class="hlt">bearing</span> <span class="hlt">contact</span>. The predesigned parabolic function of transmission errors is able to absorb piece-wise linear functions of transmission errors that are caused by the gear misalignment and reduce gear noise. The gears are face-milled by head cutters with conical surfaces or surfaces of revolution. A computer program for simulation of meshing, <span class="hlt">bearing</span> <span class="hlt">contact</span> and determination of transmission errors for misaligned gear has been developed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830011861','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830011861"><span>Lubrication of 35-millimeter-bore ball <span class="hlt">bearings</span> of several designs to 2.5 million DN</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schuller, F. T.</p> <p>1983-01-01</p> <p>Parametric tests were conducted with 35mm bore, angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span> with either a single or double outer and guided cage. The <span class="hlt">bearings</span> were either lubricated by oil jets or employed inner ring lubrication. Outer ring cooling was added in selected tests. Lubricant flow to the <span class="hlt">bearing</span> ranged from 300 to 1900 cc/min. All <span class="hlt">bearings</span> were successfully run at speeds to 2.5 million DN. Increasing the lubricant flow decreased <span class="hlt">bearing</span> ring temperatures but increased <span class="hlt">bearing</span> power lines. The power loss and race temperatures of a jet lubricated with double outer land guided cage were always higher than those of the single land guided design at similar test conditions. The lowest <span class="hlt">bearing</span> operating temperatures were achieved when inner ring lubrication and outer ring cooling were combined. It is found that cage slip of a double outer land guided cage is approximately twice that of a single outer land guided cage.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4883417','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4883417"><span>Measuring Micro-Friction Torque in MEMS Gas <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fang, Xudong; Liu, Huan</p> <p>2016-01-01</p> <p>An in situ measurement of micro-friction torque in MEMS gas <span class="hlt">bearings</span>, which has been a challenging research topic for years, is realized by a system designed in this paper. In the system, a high accuracy micro-force sensor and an electronically-driven table are designed, fabricated and utilized. With appropriate installation of the sensor and <span class="hlt">bearings</span> on the table, the engine rotor can be driven to rotate with the sensor using a silicon lever beam. One end of the beam is fixed to the shaft of the gas <span class="hlt">bearing</span>, while the other end is free and in <span class="hlt">contact</span> with the sensor probe tip. When the sensor begins to rotate with the table, the beam is pushed by the sensor probe to rotate in the same direction. For the beam, the friction torque from the gas <span class="hlt">bearing</span> is balanced by the torque induced by pushing force from the sensor probe. Thus, the friction torque can be calculated as a product of the pushing force measured by the sensor and the lever arm, which is defined as the distance from the sensor probe tip to the centerline of the <span class="hlt">bearing</span>. Experimental results demonstrate the feasibility of this system, with a sensitivity of 1.285 mV/μN·m in a range of 0 to 11.76 μN·m when the lever arm is 20 mm long. The measuring range can be modified by varying the length of the lever arm. Thus, this system has wide potential applications in measuring the micro-friction torque of gas <span class="hlt">bearings</span> in rotating MEMS machines. PMID:27213377</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940006349','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940006349"><span>Application of powder metallurgy techniques to produce improved <span class="hlt">bearing</span> elements for liquid rocket engines</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moracz, D. J.; Shipley, R. J.; Moxson, V. S.; Killman, R. J.; Munson, H. E.</p> <p>1992-01-01</p> <p>The objective was to apply powder metallurgy techniques for the production of improved <span class="hlt">bearing</span> elements, specifically balls and races, for advanced cryogenic turbopump <span class="hlt">bearings</span>. The materials and fabrication techniques evaluated were judged on the basis of their ability to improve fatigue life, wear resistance, and corrosion resistance of Space Shuttle Main Engine (SSME) propellant <span class="hlt">bearings</span> over the currently used 440C. An extensive list of candidate <span class="hlt">bearing</span> alloys in five different categories was considered: tool/die steels, through hardened stainless steels, cobalt-base alloys, and gear steels. Testing of alloys for final consideration included hardness, rolling <span class="hlt">contact</span> fatigue, cross cylinder wear, elevated temperature wear, room and cryogenic fracture toughness, stress corrosion cracking, and five-ball (rolling-sliding element) testing. Results of the program indicated two alloys that showed promise for improved <span class="hlt">bearing</span> elements. These alloys were MRC-2001 and X-405. 57mm <span class="hlt">bearings</span> were fabricated from the MRC-2001 alloy for further actual hardware rig testing by NASA-MSFC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740020845','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740020845"><span>Fatigue life of high-speed ball <span class="hlt">bearings</span> with silicon nitride balls</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, R. J.; Zaretsky, E. V.</p> <p>1974-01-01</p> <p>Hot-pressed silicon nitride was evaluated as a rolling-element <span class="hlt">bearing</span> material. The five-ball fatigue tester was used to test 12.7-mm- diameter silicon nitride balls at maximum Hertz stresses ranging from 4.27 x 10 to the 9th power n/sq m to 6.21 x 10 to the 9th power n/sq m at a race temperature of 328K. The fatigue life of NC-132 hot-pressed silicon nitride was found to be equal to typical <span class="hlt">bearing</span> steels and much greater than other ceramic or cermet materials at the same stress levels. A digital computer program was used to predict the fatigue life of 120-mm- bore angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> containing either steel or silicon nitride balls. The analysis indicates that there is no improvement in the lives of <span class="hlt">bearings</span> of the same geometry operating at DN values from 2 to 4 million where silicon nitride balls are used in place of steel balls.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-08-24/pdf/2010-20918.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-08-24/pdf/2010-20918.pdf"><span>75 FR 51978 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-08-24</p> <p>... Service (FAS) today accepted and began a review of a petition for trade <span class="hlt">adjustment</span> assistance filed under... <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Program Staff, FAS, USDA by phone: (202) 720-0638 or (202) 690- 0633: or by e-mail at: [email protected]fas.usda.gov ; or visit the TAA for Farmers' Web site...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-07-21/pdf/2010-17801.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-07-21/pdf/2010-17801.pdf"><span>75 FR 42376 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-07-21</p> <p>... Service (FAS) today accepted and began a review of a petition for trade <span class="hlt">adjustment</span> assistance filed under... <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Staff, FAS, USDA, by phone: (202) 720-0638, or (202) 690-0633; or by e-mail: [email protected]fas.usda.gov ; or visit the TAA for Farmers' Web site: http:// www...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-07-21/pdf/2010-17799.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-07-21/pdf/2010-17799.pdf"><span>75 FR 42375 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-07-21</p> <p>... Service (FAS) today accepted and began a review of a petition for trade <span class="hlt">adjustment</span> assistance filed under... INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Staff, FAS, USDA, by phone: (202) 720-0638, or (202) 690-0633; or by e-mail: [email protected]fas.usda.gov ; or visit the TAA for Farmers' Web site...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120008398','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120008398"><span>Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.</p> <p>2012-01-01</p> <p>The effect of internal clearance on radially loaded deepgroove ball and cylindrical roller <span class="hlt">bearing</span> load distribution and fatigue life was determined for four clearance groups defined in the <span class="hlt">bearing</span> standards. The analysis was extended to negative clearance (interference) conditions to produce a curve of life factor versus internal clearance. Rolling-element loads can be optimized and <span class="hlt">bearing</span> life maximized for a small negative operating clearance. Life declines gradually with positive clearance and rapidly with increasing negative clearance. Relationships were found between <span class="hlt">bearing</span> life and internal clearance as a function of ball or roller diameter, <span class="hlt">adjusted</span> for load. Results are presented as life factors for radially loaded <span class="hlt">bearings</span> independent of <span class="hlt">bearing</span> size or applied load. In addition, a modified Stribeck Equation is presented that relates the maximum rolling-element load to internal <span class="hlt">bearing</span> clearance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27862307','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27862307"><span>Rescore protein-protein docked ensembles with an interface <span class="hlt">contact</span> statistics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mezei, Mihaly</p> <p>2017-02-01</p> <p>The recently developed statistical measure for the type of residue-residue <span class="hlt">contact</span> at protein complex interfaces, based on a parameter-free definition of <span class="hlt">contact</span>, has been used to define a <span class="hlt">contact</span> score that is correlated with the likelihood of correctness of a proposed complex structure. Comparing the proposed <span class="hlt">contact</span> scores on the native structure and on a set of model structures the proposed measure was shown to generally favor the native structure but in itself was not able to reliably score the native structure to be the best. <span class="hlt">Adjusting</span> the scores of redocking experiments with the <span class="hlt">contact</span> score showed that the <span class="hlt">adjusted</span> score was able to move up the ranking of the native-like structure among the proposed complexes when the native-like was not ranked the best by the respective program. Tests on docking of unbound proteins compared the <span class="hlt">contact</span> scores of the complexes with the <span class="hlt">contact</span> score of the crystal structure again showing the tendency of the <span class="hlt">contact</span> score to favor native-like conformations. The possibility of using the <span class="hlt">contact</span> score to improve the determination of biological dimers in a crystal structure was also explored. Proteins 2017; 85:235-241. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29315790','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29315790"><span>A work-for-food enrichment program increases exploration and decreases stereotypies in four species of <span class="hlt">bears</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wagman, Jason D; Lukas, Kristen E; Dennis, Patricia M; Willis, Mark A; Carroscia, Joe; Gindlesperger, Curt; Schook, Mandi W</p> <p>2018-01-01</p> <p>Zoo-housed <span class="hlt">bears</span> are prone to exhibiting stereotypic behaviors, generally considered indicators of negative welfare. We explored the effects of a variable-time feeding enrichment schedule on behavioral indicators of welfare in four <span class="hlt">bear</span> species at Cleveland Metroparks Zoo. We distributed the diets of eight <span class="hlt">bears</span> in one of five enrichment items, for two consecutive days each, and monitored behavior throughout the day. In Experiment 1, we compared variable-time to fixed-time presentation of enrichment over two, 10-day periods. Overall, <span class="hlt">bears</span> performed more exploratory behavior when enriched (p < 0.0001). Furthermore, variable-time enrichment was associated with a greater increase in exploratory behavior than fixed-time enrichment when compared to baseline (p < 0.001). Both fixed-time (p unadjusted <0.05, p <span class="hlt">adjusted</span> = 0.07) and variable-schedule (p unadjusted <0.05, p <span class="hlt">adjusted</span> = 0.09) enrichment were also associated with similar decreases in abnormal behavior compared to baseline. For Experiment 2, we tested habituation to enrichment over 30 days using multiple items and a semi-variable presentation schedule. Again during the enrichment period, <span class="hlt">bears</span> exhibited increased exploratory behavior (p < 0.0001) and decreased abnormal behaviors compared to baseline (p unadjusted = 0.05, p <span class="hlt">adjusted</span> = 0.09). We observed no habituation during the 30-day sustained enrichment period for these behaviors. Collectively, these results suggest that daily, variable-schedule feeding enrichment, with intermittent presentation of unique enrichment items, increases behavioral indicators of positive welfare and decreases behavioral indicators of negative welfare. © 2018 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870016923','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870016923"><span>Generation of spiral bevel gears with conjugate tooth surfaces and tooth <span class="hlt">contact</span> analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, Faydor L.; Tsung, Wei-Jiung; Lee, Hong-Tao</p> <p>1987-01-01</p> <p>A new method for generation of spiral bevel gears is proposed. The main features of this method are as follows: (1) the gear tooth surfaces are conjugated and can transform rotation with zero transmission errors; (2) the tooth <span class="hlt">bearing</span> <span class="hlt">contact</span> is localized; (3) the center of the instantaneous <span class="hlt">contact</span> ellipse moves in a plane that has a fixed orientation; (4) the <span class="hlt">contact</span> normal performs in the process of meshing a parallel motion; (5) the motion of the <span class="hlt">contact</span> ellipse provides improved conditions of lubrication; and (6) the gears can be manufactured by use of Gleason's equipment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPJWC..6702058K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPJWC..6702058K"><span>Experimental equipment for measuring physical properties of the annular hydrostatic thrust <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kozdera, Michal; Drábková, Sylva; Bojko, Marian</p> <p>2014-03-01</p> <p>The hydraulic circuit, through which the mineral oil is brought, is an important part of hydrostatic <span class="hlt">bearings</span>. The annular hydrostatic thrust <span class="hlt">bearing</span> consists of two sliding plates divided by a layer of mineral oil. In the lower plate, there are oil grooves which distribute the liquid between the sliding areas. The hydraulic circuit is made of two basic parts: the energy source and the controlling part. The hydraulic pump, which brings the liquid into the sliding <span class="hlt">bearing</span>, is the source of the pressure energy. The sliding <span class="hlt">bearing</span> is weighted down by axial force, which can be changed during the process. That's why in front of the particular oil grooves control components <span class="hlt">adjusting</span> pressure and flow size are located. This paper deals with a project of a hydraulic circuit for regulation of fluid layer in the annular hydrostatic thrust <span class="hlt">bearing</span> and the testing equipment for measuring its physical properties. It will include the issue of measuring loading capacity and height of the fluid layer in the annular hydrostatic thrust <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012694','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012694"><span>Analysis of Space Station Centrifuge Rotor <span class="hlt">Bearing</span> Systems: A Case Study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Poplawski, Joseph V.; Loewenthal, Stuart H.; Oswald, Fred B.; Zaretsky, Erwin V.; Morales, Wilfredo; Street, Kenneth W., Jr.</p> <p>2014-01-01</p> <p>A team of NASA <span class="hlt">bearing</span> and lubrication experts was assembled to assess the risk for the rolling-element <span class="hlt">bearings</span> used in the International Space Station (ISS) centrifuge rotor (CR) to seize or otherwise fail to survive for the required 10-year life. The CR was designed by the Japan Aerospace Exploration Agency and their subcontractor, NEC Toshiba Space Systems, Ltd. (NTSpace). The NASA team performed a design audit for the most critical rolling-element <span class="hlt">bearing</span> systems and reviewed the lubricant selected. There is uncertainty regarding the ability of the Braycote 601 grease (Castrol Limited) to reliably provide the 10-year continuous life required without relubrication of the system. The fatigue life of the Rotor Shaft Assembly (RSA) spring loaded face-to-face mount at a 99-percent probability of survival (L1 life) for the ball <span class="hlt">bearing</span> set was estimated at 700 million hours and the single ball <span class="hlt">bearing</span> (Row 3) at 58 million hours. These lives satisfy the mission requirements for fatigue. Rolling-element seizure tests on the RSA and fluid slip joint <span class="hlt">bearings</span> were found unlikely to stop the centrifuge, which can cause damage to the ISS structure. The spin motor encoder duplex angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> have a hard preload and a large number of small balls have the highest risk of failure. These <span class="hlt">bearings</span> were not tested for seizure even though they are less tolerant to debris or internal clearance reductions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/862530','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/862530"><span>Journal <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Menke, John R.; Boeker, Gilbert F.</p> <p>1976-05-11</p> <p>1. An improved journal <span class="hlt">bearing</span> comprising in combination a non-rotatable cylindrical <span class="hlt">bearing</span> member having a first <span class="hlt">bearing</span> surface, a rotatable cylindrical <span class="hlt">bearing</span> member having a confronting second <span class="hlt">bearing</span> surface having a plurality of <span class="hlt">bearing</span> elements, a source of lubricant adjacent said <span class="hlt">bearing</span> elements for supplying lubricant thereto, each <span class="hlt">bearing</span> element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said <span class="hlt">bearing</span> members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable <span class="hlt">bearing</span> member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second <span class="hlt">bearing</span> surface to cause an increase in the lubricant pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930048978&hterms=Space+Liquid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DSpace%2BLiquid','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930048978&hterms=Space+Liquid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DSpace%2BLiquid"><span>Wear modes active in angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span> operating in liquid oxygen environment of the Space Shuttle turbopumps</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chase, Thaddeus J.</p> <p>1993-01-01</p> <p>Extensive experimental investigation has been carried out on used flight <span class="hlt">bearings</span> of the high pressure oxidizer turbopumps (HPOTP) of the space shuttle main engine (SSME) in order to determine the dominant wear modes, their extent, and causes. The paper presents the methodology, various surface analysis techniques used, results, and discussion. The mode largely responsible for premature <span class="hlt">bearing</span> wear has been identified as adhesive/shear peeling of the upper layers of <span class="hlt">bearing</span> balls and rings. This mode relies upon the mechanisms of scale formation, breakdown, and removal, all of which are greatly enhanced by the heavy oxidation environment of the HPOTP. Major causes of the high wear rates appear to be lubrication and cooling, both inadequate for the imposed conditions of operation. Numerous illustrations and evidence are provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29160130','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29160130"><span>The effect of <span class="hlt">bearing</span> type on the outcome of total hip arthroplasty.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peters, Rinne M; Van Steenbergen, Liza N; Stevens, Martin; Rijk, Paul C; Bulstra, Sjoerd K; Zijlstra, Wierd P</p> <p>2018-04-01</p> <p>Background and purpose - Alternative <span class="hlt">bearing</span> surfaces such as ceramics and highly crosslinked polyethylene (HXLPE) were developed in order to further improve implant performance of total hip arthroplasties (THAs). Whether these alternative <span class="hlt">bearing</span> surfaces result in increased longevity is subject to debate. Patients and methods - Using the Dutch Arthroplasty Register (LROI), we identified all patients with a primary, non-metal-on-metal THA implanted in the Netherlands in the period 2007-2016 (n = 209,912). Cumulative incidence of revision was calculated to determine differences in survivorship of THAs according to <span class="hlt">bearing</span> type: metal-on-polyethylene (MoPE), metal-on-HXLPE (MoHXLPE), ceramic-on-polyethylene (CoPE), ceramic-on-HXLPE (CoHXLPE), ceramic-on-ceramic (CoC), and oxidized-zirconium-on-(HXL)polyethylene (Ox(HXL)PE). Multivariable Cox proportional hazard regression ratios (HRs) were used for comparisons. Results - After <span class="hlt">adjustment</span> for confounders, CoHXLPE, CoC, and Ox(HXL)PE resulted in a statistically significantly lower risk of revision compared with MoPE after 9 years follow-up (HR =0.8-0.9 respectively, compared with HR =1.0). For small (22-28 mm) femoral head THAs, lower revision rates were found for CoPE and CoHXLPE (HR =0.9). In the 36 mm femoral head subgroup, CoC-<span class="hlt">bearing</span> THAs had a lower HR compared with MoHXLPE (HR =0.7 versus 1.0). Crude revision rates in young patients (< 60 years) for CoHXLPE, CoC, and Ox(HXL)PE (HR =0.7) were lower than MoPE (HR =1.0). However, after <span class="hlt">adjustment</span> for case mix and confounders these differences were not statistically significant. Interpretation - We found a mid-term lower risk of revision for CoHXLPE, CoC, and Ox(HXL)PE <span class="hlt">bearings</span> compared with traditional MoPE-<span class="hlt">bearing</span> surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1026566','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1026566"><span>Failure Atlas for Rolling <span class="hlt">Bearings</span> in Wind Turbines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Tallian, T. E.</p> <p>2006-01-01</p> <p>This Atlas is structured as a supplement to the book: T.E. Tallian: Failure Atlas for Hertz <span class="hlt">Contact</span> Machine Elements, 2nd edition, ASME Press New York, (1999). The content of the atlas comprises plate pages from the book that contain <span class="hlt">bearing</span> failure images, application data, and descriptions of failure mode, image, and suspected failure causes. Rolling <span class="hlt">bearings</span> are a critical component of the mainshaft system, gearbox and generator in the rapidly developing technology of power generating wind turbines. The demands for long service life are stringent; the design load, speed and temperature regimes are demanding and the environmental conditions including weather,more » contamination, impediments to monitoring and maintenance are often unfavorable. As a result, experience has shown that the rolling <span class="hlt">bearings</span> are prone to a variety of failure modes that may prevent achievement of design lives. Morphological failure diagnosis is extensively used in the failure analysis and improvement of <span class="hlt">bearing</span> operation. Accumulated experience shows that the failure appearance and mode of failure causation in wind turbine <span class="hlt">bearings</span> has many distinguishing features. The present Atlas is a first effort to collect an interpreted database of specifically wind turbine related rolling <span class="hlt">bearing</span> failures and make it widely available. This Atlas is structured as a supplement to the book: T. E. Tallian: Failure Atlas for Hertz <span class="hlt">Contact</span> Machine Elements, 2d edition, ASME Press New York, (1999). The main body of that book is a comprehensive collection of self-contained pages called Plates, containing failure images, <span class="hlt">bearing</span> and application data, and three descriptions: failure mode, image and suspected failure causes. The Plates are sorted by main failure mode into chapters. Each chapter is preceded by a general technical discussion of the failure mode, its appearance and causes. The Plates part is supplemented by an introductory part, describing the appearance classification and failure</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100036219','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100036219"><span>Rotorcraft Transmission Noise Path Model, Including Distributed Fluid Film <span class="hlt">Bearing</span> Impedance Modeling</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hambric, Stephen A.; Hanford, Amanda D.; Shepherd, Micah R.; Campbell, Robert L.; Smith, Edward C.</p> <p>2010-01-01</p> <p>A computational approach for simulating the effects of rolling element and journal <span class="hlt">bearings</span> on the vibration and sound transmission through gearboxes has been demonstrated. The approach, using ARL/Penn State s CHAMP methodology, uses Component Mode Synthesis of housing and shafting modes computed using Finite Element (FE) models to allow for rapid <span class="hlt">adjustment</span> of <span class="hlt">bearing</span> impedances in gearbox models. The approach has been demonstrated on NASA GRC s test gearbox with three different <span class="hlt">bearing</span> configurations: in the first condition, traditional rolling element (ball and roller) <span class="hlt">bearings</span> were installed, and in the second and third conditions, the traditional <span class="hlt">bearings</span> were replaced with journal and wave <span class="hlt">bearings</span> (wave <span class="hlt">bearings</span> are journal <span class="hlt">bearings</span> with a multi-lobed wave pattern on the <span class="hlt">bearing</span> surface). A methodology for computing the stiffnesses and damping in journal and wave <span class="hlt">bearings</span> has been presented, and demonstrated for the journal and wave <span class="hlt">bearings</span> used in the NASA GRC test gearbox. The FE model of the gearbox, along with the rolling element <span class="hlt">bearing</span> coupling impedances, was analyzed to compute dynamic transfer functions between forces applied to the meshing gears and accelerations on the gearbox housing, including several locations near the <span class="hlt">bearings</span>. A Boundary Element (BE) acoustic model was used to compute the sound radiated by the gearbox. Measurements of the Gear Mesh Frequency (GMF) tones were made by NASA GRC at several operational speeds for the rolling element and journal <span class="hlt">bearing</span> gearbox configurations. Both the measurements and the CHAMP numerical model indicate that the journal <span class="hlt">bearings</span> reduce vibration and noise for the second harmonic of the gear meshing tones, but show no clear benefit to using journal <span class="hlt">bearings</span> to reduce the amplitudes of the fundamental gear meshing tones. Also, the numerical model shows that the gearbox vibrations and radiated sound are similar for journal and wave <span class="hlt">bearing</span> configurations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22260768','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22260768"><span>Delayed child-<span class="hlt">bearing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johnson, Jo-Ann; Tough, Suzanne</p> <p>2012-01-01</p> <p> compensate for age-related decline in fertility. (II-2A) 2. A fertility evaluation should be initiated after 6 months of unprotected intercourse without conception in women 35 to 37 years of age, and earlier in women > 37 years of age. (II-2A) 3. Prospective parents should be informed that semen quality and male fertility deteriorate with advancing age and that the risk of genetic disorders in offspring increases. (II-2A) 4. Women ≥ 35 years of age should be offered screening for fetal aneuploidy and undergo a detailed second trimester ultrasound examination to look for significant fetal birth defects (particularly cardiac defects). (II-1A) 5. Delayed child-<span class="hlt">bearing</span> is associated with increased obstetrical and perinatal complications. Care providers need to be aware of these complications and <span class="hlt">adjust</span> obstetrical management protocols to ensure optimal maternal and perinatal outcomes. (II-2A) 6. All adults of reproductive age should be aware of the obstetrical and perinatal risks of advanced maternal age so they can make informed decisions about the timing of child-<span class="hlt">bearing</span>. (II-2A) 7. Strategies to improve informed decision-making by prospective parents should be designed, implemented, and evaluated. These strategies should provide opportunity for adults to understand the potential medical, social, and economic consequences of child-<span class="hlt">bearing</span> throughout the reproductive years. (III-B) 8. Barriers to healthy reproduction, including workplace policies, should be reviewed to optimize the likelihood of healthy pregnancies. (III-C).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10499789','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10499789"><span>Multiple human exposures to a rabid <span class="hlt">bear</span> cub at a petting zoo and barnwarming--Iowa, August 1999.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p></p> <p>1999-09-03</p> <p>On August 27, 1999, a black <span class="hlt">bear</span> cub, approximately 5-6 months old, died after several hours of acute central nervous system symptoms; preliminary test results available on August 28 indicated the <span class="hlt">bear</span> had rabies. The <span class="hlt">bear</span> was part of the Swenson's Wild Midwest Exotic Petting Zoo in Clermont, Iowa (northeastern Iowa). At the petting zoo, visitors fed, wrestled, and may have been nipped by the <span class="hlt">bear</span>. The <span class="hlt">bear</span> also was taken to an August 14 barnwarming at the Tharp barn in Holy Cross, Iowa (eastern Iowa), where it reportedly nipped people. An estimated 400 people from 10 states (Arizona, California, Florida, Illinois, Iowa, Minnesota, New Mexico, New York, Ohio, and Wisconsin) and Australia had <span class="hlt">contact</span> with the <span class="hlt">bear</span> cub at either the petting zoo or the barnwarming during the 28 days before its death, during which the <span class="hlt">bear</span> may have transmitted rabies virus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3629141','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3629141"><span><span class="hlt">Bear</span>-Baiting May Exacerbate Wolf-Hunting Dog Conflict</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bump, Joseph K.; Murawski, Chelsea M.; Kartano, Linda M.; Beyer, Dean E.; Roell, Brian J.</p> <p>2013-01-01</p> <p>Background The influence of policy on the incidence of human-wildlife conflict can be complex and not entirely anticipated. Policies for managing <span class="hlt">bear</span> hunter success and depredation on hunting dogs by wolves represent an important case because with increasing wolves, depredations are expected to increase. This case is challenging because compensation for wolf depredation on hunting dogs as compared to livestock is less common and more likely to be opposed. Therefore, actions that minimize the likelihood of such conflicts are a conservation need. Methodology/Principal Findings We used data from two US states with similar wolf populations but markedly different wolf/hunting dog depredation patterns to examine the influence of <span class="hlt">bear</span> hunting regulations, <span class="hlt">bear</span> hunter to wolf ratios, hunter method, and hunter effort on wolf depredation trends. Results indicated that the ratio of <span class="hlt">bear</span> hunting permits sold per wolf, and hunter method are important factors affecting wolf depredation trends in the Upper Great Lakes region, but strong differences exist between Michigan and Wisconsin related in part to the timing and duration of <span class="hlt">bear</span>-baiting (i.e., free feeding). The probability that a wolf depredated a <span class="hlt">bear</span>-hunting dog increases with the duration of <span class="hlt">bear</span>-baiting, resulting in a relative risk of depredation 2.12–7.22× greater in Wisconsin than Michigan. The net effect of compensation for hunting dog depredation in Wisconsin may also contribute to the difference between states. Conclusions/Significance These results identified a potential tradeoff between <span class="hlt">bear</span> hunting success and wolf/<span class="hlt">bear</span>-hunting dog conflict. These results indicate that management options to minimize conflict exist, such as <span class="hlt">adjusting</span> baiting regulations. If reducing depredations is an important goal, this analysis indicates that actions aside from (or in addition to) reducing wolf abundance might achieve that goal. This study also stresses the need to better understand the relationship among baiting</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780019486','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780019486"><span>Emergency and microfog lubrication and cooling of <span class="hlt">bearings</span> for Army helicopters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rosenlieb, J. W.</p> <p>1978-01-01</p> <p>An analysis and system study was performed to provide design information regarding lubricant and coolant flow rates and flow paths for effective utilization of the lubricant and coolant in a once-through oil-mist (microfog) and coolant air system. A system was designed, manufactured, coupled with an existing rig and evaluation tests were performed using 46 mm bore split-inner angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> under 1779N (400 lb.) thrust load. An emergency lubrication aspirator system was also manufactured and tested under lost lubricant conditions. The testing demonstrated the feasibility of using a mist oil and cooling air system to lubricate and cool a high speed helicopter engine mainshaft <span class="hlt">bearing</span>. The testing also demonstrated the feasibility of using an emergency aspirator lubrication system as a viable survivability concept for helicopter mainshaft engine <span class="hlt">bearing</span> for periods as long as 30 minutes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993NaAIJ..25..168X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993NaAIJ..25..168X"><span>Relationship between rotor-<span class="hlt">bearing</span> system stability and supporting <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Longxiang; Zhu, Jun</p> <p>1993-04-01</p> <p>Results of an investigation of the relationship between the rotor-<span class="hlt">bearing</span> system stability of a large rotating machinery and the supporting <span class="hlt">bearings</span> are presented. The contribution factor of the <span class="hlt">bearings</span> to the system stability is established. The <span class="hlt">bearing</span> with the largest contribution factor yields the greatest contribution to the system stability. Rotor-<span class="hlt">bearing</span> system stability depends mainly on the dynamic characteristic performance of the sensitive <span class="hlt">bearings</span>. Appropriate readjustment in the type or design parameters of these <span class="hlt">bearings</span> will result in a significant improvement in the stability margin. Numerical examples are carried out for a model rotor-<span class="hlt">bearing</span> system with five <span class="hlt">bearings</span> in a domestic 200-MW turbine generator set; they show that the calculated results are in good agreement with those measured for some actual rotating machinery. A scheme to reconstruct the domestic 200-MW turbine generator set is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940002919&hterms=external+version&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dexternal%2Bversion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940002919&hterms=external+version&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dexternal%2Bversion"><span>SHABERTH - ANALYSIS OF A SHAFT <span class="hlt">BEARING</span> SYSTEM (CRAY VERSION)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coe, H. H.</p> <p>1994-01-01</p> <p>The SHABERTH computer program was developed to predict operating characteristics of <span class="hlt">bearings</span> in a multibearing load support system. Lubricated and non-lubricated <span class="hlt">bearings</span> can be modeled. SHABERTH calculates the loads, torques, temperatures, and fatigue life for ball and/or roller <span class="hlt">bearings</span> on a single shaft. The program also allows for an analysis of the system reaction to the termination of lubricant supply to the <span class="hlt">bearings</span> and other lubricated mechanical elements. SHABERTH has proven to be a valuable tool in the design and analysis of shaft <span class="hlt">bearing</span> systems. The SHABERTH program is structured with four nested calculation schemes. The thermal scheme performs steady state and transient temperature calculations which predict system temperatures for a given operating state. The <span class="hlt">bearing</span> dimensional equilibrium scheme uses the <span class="hlt">bearing</span> temperatures, predicted by the temperature mapping subprograms, and the rolling element raceway load distribution, predicted by the <span class="hlt">bearing</span> subprogram, to calculate <span class="hlt">bearing</span> diametral clearance for a given operating state. The shaft-<span class="hlt">bearing</span> system load equilibrium scheme calculates <span class="hlt">bearing</span> inner ring positions relative to the respective outer rings such that the external loading applied to the shaft is brought into equilibrium by the rolling element loads which develop at each <span class="hlt">bearing</span> inner ring for a given operating state. The <span class="hlt">bearing</span> rolling element and cage load equilibrium scheme calculates the rolling element and cage equilibrium positions and rotational speeds based on the relative inner-outer ring positions, inertia effects, and friction conditions. The ball <span class="hlt">bearing</span> subprograms in the current SHABERTH program have several model enhancements over similar programs. These enhancements include an elastohydrodynamic (EHD) film thickness model that accounts for thermal heating in the <span class="hlt">contact</span> area and lubricant film starvation; a new model for traction combined with an asperity load sharing model; a model for the hydrodynamic rolling and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-05-03/pdf/2010-10265.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-05-03/pdf/2010-10265.pdf"><span>75 FR 23227 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-05-03</p> <p>... cost and cash benefits. FOR FURTHER INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance Staff, FAS, USDA... in cash receipts for lilies compared to the average of the 3 preceding marketing years. If a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950065467&hterms=press+fit&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpress%2Bfit','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950065467&hterms=press+fit&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpress%2Bfit"><span>Redundant <span class="hlt">Bearing</span> Assembly</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wright, Jay M.</p> <p>1995-01-01</p> <p>Proposed redundant <span class="hlt">bearing</span> assembly consists of two modified ball or roller <span class="hlt">bearings</span>, one held by other. Outer race of inner <span class="hlt">bearing</span> press-fit into inner race of outer <span class="hlt">bearing</span>. Within each <span class="hlt">bearing</span>, side walls of inner and outer races extended radially toward each other leaving only small gap. In assembly, one <span class="hlt">bearing</span> continues to allow free rotation when other fails. <span class="hlt">Bearing</span> wear monitored by examination of gaps between races. In alternative design, inner race of outer <span class="hlt">bearing</span> and outer race of inner <span class="hlt">bearing</span> manufactured as single piece.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22029555','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22029555"><span>Predictors of sociocultural <span class="hlt">adjustment</span> among sojourning Malaysian students in Britain.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Swami, Viren</p> <p>2009-08-01</p> <p>The process of cross-cultural migration may be particularly difficult for students travelling overseas for further or higher education, especially where qualitative differences exist between the home and host nations. The present study examined the sociocultural <span class="hlt">adjustment</span> of sojourning Malaysian students in Britain. Eighty-one Malay and 110 Chinese students enrolled in various courses answered a self-report questionnaire that examined various aspects of sociocultural <span class="hlt">adjustment</span>. A series of one-way analyses of variance showed that Malay participants experienced poorer sociocultural <span class="hlt">adjustment</span> in comparison with their Chinese counterparts. They were also less likely than Chinese students to have <span class="hlt">contact</span> with co-nationals and host nationals, more likely to perceive their actual experience in Britain as worse than they had expected, and more likely to perceive greater cultural distance and greater discrimination. The results of regression analyses showed that, for Malay participants, perceived discrimination accounted for the greatest proportion of variance in sociocultural <span class="hlt">adjustment</span> (73%), followed by English language proficiency (10%) and <span class="hlt">contact</span> with host nationals (4%). For Chinese participants, English language proficiency was the strongest predictor of sociocultural <span class="hlt">adjustment</span> (54%), followed by expectations of life in Britain (18%) and <span class="hlt">contact</span> with host nationals (3%). By contrast, participants' sex, age, and length of residence failed to emerge as significant predictors for either ethnic group. Possible explanations for this pattern of findings are discussed, including the effects of Islamophobia on Malay-Muslims in Britain, possible socioeconomic differences between Malay and Chinese students, and personality differences between the two ethnic groups. The results are further discussed in relation to practical steps that can be taken to improve the sociocultural <span class="hlt">adjustment</span> of sojourning students in Britain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002748','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002748"><span>Recalibrated Equations for Determining Effect of Oil Filtration on Rolling <span class="hlt">Bearing</span> Life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Needelman, William M.; Zaretsky, Erwin V.</p> <p>2014-01-01</p> <p>In 1991, Needelman and Zaretsky presented a set of empirically derived equations for <span class="hlt">bearing</span> fatigue life (<span class="hlt">adjustment</span>) factors (LFs) as a function of oil filter ratings. These equations for life factors were incorporated into the reference book, "STLE Life Factors for Rolling <span class="hlt">Bearings</span>." These equations were normalized (LF = 1) to a 10-micrometer filter rating at Beta(sub x) = 200 (normal cleanliness) as it was then defined. Over the past 20 years, these life factors based on oil filtration have been used in conjunction with ANSI/ABMA standards and <span class="hlt">bearing</span> computer codes to predict rolling <span class="hlt">bearing</span> life. Also, additional experimental studies have been made by other investigators into the relationship between rolling <span class="hlt">bearing</span> life and the size, number, and type of particle contamination. During this time period filter ratings have also been revised and improved, and they now use particle counting calibrated to a new National Institute of Standards and Technology (NIST) reference material, NIST SRM 2806, 1997. This paper reviews the relevant <span class="hlt">bearing</span> life studies and describes the new filter ratings. New filter ratings, Beta(sub x(c)) = 200 and Beta(sub x(c)) = 1000, are benchmarked to old filter ratings, Beta(sub x) = 200, and vice versa. Two separate sets of filter LF values were derived based on the new filter ratings for roller <span class="hlt">bearings</span> and ball <span class="hlt">bearings</span>, respectively. Filter LFs can be calculated for the new filter ratings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010SMaS...19d5004M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SMaS...19d5004M"><span>Artificial muscles with <span class="hlt">adjustable</span> stiffness</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mutlu, Rahim; Alici, Gursel</p> <p>2010-04-01</p> <p>This paper reports on a stiffness enhancement methodology based on using a suitably designed <span class="hlt">contact</span> surface with which cantilevered-type conducting polymer bending actuators are in <span class="hlt">contact</span> during operation. The <span class="hlt">contact</span> surface constrains the bending behaviour of the actuators. Depending on the topology of the <span class="hlt">contact</span> surface, the resistance of the polymer actuators to deformation, i.e. stiffness, is varied. As opposed to their predecessors, these polymer actuators operate in air. Finite element analysis and modelling are used to quantify the effect of the <span class="hlt">contact</span> surface on the effective stiffness of a trilayer cantilevered beam, which represents a one-end-free, the-other-end-fixed polypyrrole (PPy) conducting polymer actuator under a uniformly distributed load. After demonstrating the feasibility of the <span class="hlt">adjustable</span> stiffness concept, experiments were conducted to determine the stiffness of bending-type conducting polymer actuators in <span class="hlt">contact</span> with a range (20-40 mm in radius) of circular <span class="hlt">contact</span> surfaces. The numerical and experimental results presented demonstrate that the stiffness of the actuators can be varied using a suitably profiled <span class="hlt">contact</span> surface. The larger the radius of the <span class="hlt">contact</span> surface is, the higher is the stiffness of the polymer actuators. The outcomes of this study suggest that, although the stiffness of the artificial muscles considered in this study is constant for a given geometric size, and electrical and chemical operation conditions, it can be changed in a nonlinear fashion to suit the stiffness requirement of a considered application. The stiffness enhancement methodology can be extended to other ionic-type conducting polymer actuators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994TriTr..37..525K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994TriTr..37..525K"><span>Structural stiffness and Coulomb damping in compliant foil journal <span class="hlt">bearings</span>: Theoretical considerations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ku, C.-P. Roger; Heshmat, Hooshang</p> <p>1994-07-01</p> <p>Compliant foil <span class="hlt">bearings</span> operate on either gas or liquid, which makes them very attractive for use in extreme environments such as in high-temperature aircraft turbine engines and cryogenic turbopumps. However, a lack of analytical models to predict the dynamic characteristics of foil <span class="hlt">bearings</span> forces the <span class="hlt">bearing</span> designer to rely on prototype testing, which is time-consuming and expensive. In this paper, the authors present a theoretical model to predict the structural stiffness and damping coefficients of the bump foil strip in a journal <span class="hlt">bearing</span> or damper. Stiffness is calculated based on the perturbation of the journal center with respect to its static equilibrium position. The equivalent viscous damping coefficients are determined based on the area of a closed hysteresis loop of the journal center motion. The authors found, theoretically, that the energy dissipated from this loop was mostly contributed by the frictional motion between <span class="hlt">contact</span> surfaces. In addition, the source and mechanism of the nonlinear behavior of the bump foil strips were examined. With the introduction of this enhanced model, the analytical tools are now available for the design of compliant foil <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/81488','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/81488"><span>Grizzly <span class="hlt">bear</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.</p> <p>2003-01-01</p> <p>The grizzly <span class="hlt">bear</span> inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other <span class="hlt">bear</span> species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar <span class="hlt">bear</span> (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly <span class="hlt">bears</span> still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly <span class="hlt">bears</span> is different from a stroll in a forest from which grizzly <span class="hlt">bears</span> have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great <span class="hlt">bear</span>. Contributing to the aura of the grizzly <span class="hlt">bear</span> is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly <span class="hlt">bear</span> as modern stories and legends (Rockwell 1991).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19381082','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19381082"><span>Design analysis and performance assessment of hybrid magnetic <span class="hlt">bearings</span> for a rotary centrifugal blood pump.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ren, Zhaohui; Jahanmir, Said; Heshmat, Hooshang; Hunsberger, Andrew Z; Walton, James F</p> <p>2009-01-01</p> <p>A hybrid magnetic <span class="hlt">bearing</span> system was designed for a rotary centrifugal blood pump being developed to provide long-term circulatory support for heart failure patients. This design consists of two compact <span class="hlt">bearings</span> to suspend the rotor in five degrees-of-freedom with single axis active control. Permanent magnets are used to provide passive radial support and electromagnets to maintain axial stability of the rotor. Characteristics of the passive radial and active thrust magnetic <span class="hlt">bearing</span> system were evaluated by the electromagnetic finite element analysis. A proportional-integral-derivative controller with force balance algorithm was implemented for closed loop control of the magnetic thrust <span class="hlt">bearing</span>. The control position is continuously <span class="hlt">adjusted</span> based on the electrical energy in the <span class="hlt">bearing</span> coils, and thus passive magnetic forces carry static thrust loads to minimize the <span class="hlt">bearing</span> current. Performance of the magnetic <span class="hlt">bearing</span> system with associated control algorithm was evaluated at different operating conditions. The <span class="hlt">bearing</span> current was significantly reduced with the force balance control method and the power consumption was below 0.5 W under various thrust loads. The <span class="hlt">bearing</span> parameters predicted by the analysis were validated by the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990075848','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990075848"><span>Effect of <span class="hlt">Bearing</span> Cleaning on Long Term <span class="hlt">Bearing</span> Life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jett, Tim; Thom, R. L.</p> <p>1999-01-01</p> <p>For many years chlorofluorocarbon (CFC) based solvents, such as CFC-113 and 1,1,1, trichloroethane (TCA), were used as <span class="hlt">bearing</span> cleaning solvents for space mechanism <span class="hlt">bearings</span>. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change requiring the use of ODC-free cleaners for precision <span class="hlt">bearing</span> cleaning. With this change the question arises; what effect if any do these new cleaners have on long term <span class="hlt">bearing</span> life? The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two <span class="hlt">bearings</span> per motor) was conducted in a high vacuum environment (2.0 x 10(exp -6) torr) at a temperature of 90 C. Prior to testing the <span class="hlt">bearings</span> were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing, the mass of each lubricated <span class="hlt">bearing</span> was measured both pre and post test. Along with mass loss measurements a profilometer trace of each <span class="hlt">bearing</span> was taken to measure post test wear of the <span class="hlt">bearings</span>. In addition, the <span class="hlt">bearings</span> were visually examined and analyzed using an optical microscope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24331553','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24331553"><span>Polar <span class="hlt">bears</span>: the fate of an icon.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fitzgerald, Kevin T</p> <p>2013-11-01</p> <p> the <span class="hlt">bears</span> are so vulnerable to the effects of climate change. Polar <span class="hlt">bears</span> have few alternatives if their habitat (the sea ice) and their access to their ringed seal prey rapidly disappear. Predictions that polar <span class="hlt">bears</span> may be able to <span class="hlt">adjust</span> and sustain themselves on alternative food sources are not based on reality. Spring breakup of the sea ice is happening much earlier as well as fall freezeup is getting later, thereby prolonging the open water period that the <span class="hlt">bears</span> are shore bound. If trends continue and the ice continues to disappear, the effect on polar <span class="hlt">bears</span> would be devastating. Veterinarians must stay involved in polar <span class="hlt">bear</span> studies and in multidisciplinary conservation studies dealing with threatened and endangered species worldwide. On account of their training, veterinarians can offer a unique skill set that can provide access to a number of technologies critical to conservation efforts. The oath veterinarians take on graduation from veterinary school charges them to be sworn to the "conservation of animal resources" and in the education of the public. We are only as good as the oaths we keep. © 2013 Published by Elsevier Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17955209','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17955209"><span>[Implant with a mobile or a fixed <span class="hlt">bearing</span> in unicompartmental knee joint replacemen].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matziolis, G; Tohtz, S; Gengenbach, B; Perka, C</p> <p>2007-12-01</p> <p>Although the goal of anatomical and functional joint reconstruction in unicompartmental knee replacement is well defined, no uniform implant design has become established. In particular, the differential indications for implantation of an implant with a mobile or a fixed <span class="hlt">bearing</span> are still not clear. The long-term results of mobile and with fixed <span class="hlt">bearings</span> are comparable, but there are significant differences in resulting knee joint kinematics, tribological properties and implant-associated complications. In unicompartmental knee replacement mobile <span class="hlt">bearings</span> restore the physiological joint kinematics better than fixed implants, although the differences to total knee arthroplasty seem minor. The decoupling of mobile <span class="hlt">bearings</span> from the tibia implant allows a high level of congruence with the femoral implant, resulting in larger <span class="hlt">contact</span> areas than with fixed <span class="hlt">bearings</span>. This fact in combination with the more physiological joint kinematics leads to less wear and a lower incidence of osteolyses with mobile <span class="hlt">bearings</span>. Disadvantages of mobile <span class="hlt">bearings</span> are the higher complication and early revision rates resulting from <span class="hlt">bearing</span> dislocation and impingement syndromes caused by suboptimal implantation technique or instability. Especially in cases with ligamentous pathology fixed <span class="hlt">bearings</span> involve a lower complication rate. It seems their use can also be beneficial in patients with a low level of activity, as problems related to wear are of minor importance for this subgroup. The data currently available allow differentiations between various indications for implants with mobile or fixed <span class="hlt">bearings</span>, so that the implants can be matched to the patient and the joint pathology in unicompartmental knee joint replacement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920019119','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920019119"><span>Replacement <span class="hlt">bearing</span> for Rocketdyne SSME HPOTPs using alternate self-lubricating retainer materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gleeson, J.; Dufrane, K.; Kannel, J.</p> <p>1992-01-01</p> <p>Research was conducted to develop replacement <span class="hlt">bearings</span> for the Rocketdyne Space Shuttle main engine (SSME) high pressure oxidizer turbopumps (HPOTPs). The replacement <span class="hlt">bearings</span> consisted of standard balls and races with a special Battelle Self-Lubricating Insert Configuration (BASIC) retainer. The BASIC retainer consists of a phosphor bronze housing with inserts consisting of a polytetrafluoretheylene (PTFE) and bronze compound. The PTFE <span class="hlt">contacts</span> the balls and the land guiding surface on the outer race. A PTFE transfer film is formed on balls and races, which lubricates the critical interfaces. The BASIC retainer is a one-to-one replacement for the current Armalon retainer, but has superior lubricating properties and is stronger over the broad temperature range anticipated for the HPOTP <span class="hlt">bearings</span>. As a part of the project 40 sets of balls and races (two sizes) and 52 BASIC retainers were shipped to NASA/MSFC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990099273&hterms=cleaner+productions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcleaner%2Bproductions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990099273&hterms=cleaner+productions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcleaner%2Bproductions"><span>Effect of <span class="hlt">Bearing</span> Cleaning on Long Term <span class="hlt">Bearing</span> Life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jett, Timothy Raymond; Thom, Robert L.</p> <p>1998-01-01</p> <p>For many years chlorofluorocarbon (CFC ) based solvents, such as Freon and 1,1,1, Trichloroethane (TCA), were used as <span class="hlt">bearing</span> cleaning solvents for space mechanisms. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change to new ODC-free cleaners for the precision <span class="hlt">bearing</span> cleaning. With this change the question arises what effect if any do these new cleaners have on long term <span class="hlt">bearing</span> life. The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two <span class="hlt">bearings</span> per motor) was conducted in a high vacuum environment (2.0* 10(exp -6) torr) at a temperature of 90C. Prior to testing the <span class="hlt">bearings</span> were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing the mass of each lubricated <span class="hlt">bearing</span> was measured both pre and post test. Along with mass loss measurements a profilometer trace of each <span class="hlt">bearing</span> was taken to measure post test wear of the <span class="hlt">bearings</span>. In addition the <span class="hlt">bearings</span> were visually examined and analyzed using an optical microscope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820388','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820388"><span>Boundary lubrication of heterogeneous surfaces and the onset of cavitation in frictional <span class="hlt">contacts</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Savio, Daniele; Pastewka, Lars; Gumbsch, Peter</p> <p>2016-01-01</p> <p>Surfaces can be slippery or sticky depending on surface chemistry and roughness. We demonstrate in atomistic simulations that regular and random slip patterns on a surface lead to pressure excursions within a lubricated <span class="hlt">contact</span> that increase quadratically with decreasing <span class="hlt">contact</span> separation. This is captured well by a simple hydrodynamic model including wall slip. We predict with this model that pressure changes for larger length scales and realistic frictional conditions can easily reach cavitation thresholds and significantly change the load-<span class="hlt">bearing</span> capacity of a <span class="hlt">contact</span>. Cavitation may therefore be the norm, not the exception, under boundary lubrication conditions. PMID:27051871</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150004052','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150004052"><span>Observations of Spacecraft <span class="hlt">Bearing</span> Lubricant Redistribution Based on Thermal Conductance Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takeuchi, Yoshimi R.; Frantz, Peter P.; Hilton, Michael R.</p> <p>2014-01-01</p> <p>The performance and life of precision ball <span class="hlt">bearings</span> are critically dependent on maintaining a quantity of oil at the ball/race interface that is sufficient to support a robust protective film. In space applications, where parched conditions are intentionally the norm, harsh operating conditions can displace the small reserves of oil, resulting in reduced film thickness and premature wear. In the past, these effects have proven difficult to model or to measure experimentally. This paper describes a study addressing this challenge, where <span class="hlt">bearing</span> thermal conductance measurements are employed to infer changes in lubricant quantity at the critical rolling interfaces. In the first part of the paper, we explain how the lubricant's presence and its quantity impacts <span class="hlt">bearing</span> thermal conductance measurements. For a stationary <span class="hlt">bearing</span>, we show that conductance is directly related to the lubricant quantity in the ball/race <span class="hlt">contacts</span>. Hence, aspects of <span class="hlt">bearing</span> performance related to oil quantity can be understood and insights improved with thermal conductance data. For a moving <span class="hlt">bearing</span>, a different mechanism of heat transfer dominates and is dependent on lubricant film thickness on the ball. In the second part of the report, we discuss lubricant quantity observations based on <span class="hlt">bearing</span> thermal conductance measurements. Lubricant quantity, and thus <span class="hlt">bearing</span> thermal conductance, depends on various initial and operating conditions and is impacted further by the run-in process. A significant effect of maximum run-in speed was also observed, with less oil remaining after obtaining higher speeds. Finally, we show that some of the lubricant that is displaced between the ball and race during run-in operation can be recovered during rest, and we measure the rate of recovery for one example.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1267177-fatigue-resistant-carbon-coatings-rolling-sliding-contacts','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1267177-fatigue-resistant-carbon-coatings-rolling-sliding-contacts"><span>Fatigue resistant carbon coatings for rolling/sliding <span class="hlt">contacts</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Singh, Harpal; Ramirez, Giovanni; Eryilmaz, Osman</p> <p>2016-06-01</p> <p>The growing demands for renewable energy production have recently resulted in a significant increase in wind plant installation. Field data from these plants show that wind turbines suffer from costly repair, maintenance and high failure rates. Often times the reliability issues are linked with tribological components used in wind turbine drivetrains. The primary failure modes in <span class="hlt">bearings</span> and gears are associated with micropitting, wear, brinelling, scuffing, smearing and macropitting all of which occur at or near the surface. Accordingly, a variety of surface engineering approaches are currently being considered to alter the near surface properties of such <span class="hlt">bearings</span> and gearsmore » to prevent these tribological failures. In the present work, we have evaluated the tribological performance of compliant highly hydrogenated diamond like carbon coating developed at Argonne National Laboratory, under mixed rolling/sliding <span class="hlt">contact</span> conditions for wind turbine drivetrain components. The coating was deposited on AISI 52100 steel specimens using a magnetron sputter deposition system. The experiments were performed on a PCS Micro-Pitting-Rig (MPR) with four material pairs at 1.79 GPa <span class="hlt">contact</span> stress, 40% slide to roll ratio and in polyalphaolefin (PAO4) basestock oil (to ensure extreme boundary conditions). The post-test analysis was performed using optical microscopy, surface profilometry, and Raman spectroscopy. The results obtained show a potential for these coatings in sliding/rolling <span class="hlt">contact</span> applications as no failures were observed with coated specimens even after 100 million cycles compared to uncoated pair in which they failed after 32 million cycles, under the given test conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29212387','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29212387"><span>Employee experience of workplace supervisor <span class="hlt">contact</span> and support during long-term sickness absence.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Buys, Nicholas J; Selander, John; Sun, Jing</p> <p>2017-12-07</p> <p>Workplace support is an important factor in promoting successful return to work. The purpose of this article is to examine relationships between supervisor <span class="hlt">contact</span>, perceived workplace support and demographic variables among employees on long-term sickness absence. Data were collected from 204 public employees at a municipality in Sweden who had been on long term sickness absence (60 days or more) using a 23 question survey instrument that collected information on demographic variables, supervisor <span class="hlt">contact</span> and perceived workplace support. Most injured employees (97%) reported having <span class="hlt">contact</span> with their supervisors during their sickness absence, with a majority (56%) reporting high levels of support, including early (58.6%) and multiple (70.7%) <span class="hlt">contacts</span>. Most were pleased with amount of <span class="hlt">contact</span> (68.9%) and the majority had discussed workplace accommodations (68.1%). Employees who self-initiated <span class="hlt">contact</span>, felt the amount of <span class="hlt">contact</span> was appropriate, had a personal meeting with their supervisors and discussed workplace <span class="hlt">adjustments</span> reported experiencing higher levels of support from supervisors. Employees on long-term sickness absence appreciate <span class="hlt">contact</span> from their supervisors and this is associated with perceived workplace support. However, the amount and employee experience of this <span class="hlt">contact</span> is important. It needs to be perceived by employees as supportive, which includes a focus on strategies (e.g., work <span class="hlt">adjustment</span>) to facilitate a return to work. Supervisor training is required in this area to support the return to work process. Implications for Rehabilitation <span class="hlt">Contact</span> and support from workplace supervisors is important to workers on long-term sickness absence. Employees appreciate frequent <span class="hlt">contact</span> from supervisors during long-terms sickness absence. Employees appreciate a personal meeting with supervisors and the opportunity to discuss issues related to return to work such as work <span class="hlt">adjustment</span>. Employers should provide training to supervisors on how to communicate and</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27645396','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27645396"><span>Plasma Skimming in a Spiral Groove <span class="hlt">Bearing</span> of a Centrifugal Blood Pump.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Murashige, Tomotaka; Sakota, Daisuke; Kosaka, Ryo; Nishida, Masahiro; Kawaguchi, Yasuo; Yamane, Takashi; Maruyama, Osamu</p> <p>2016-09-01</p> <p>Plasma skimming is a phenomenon in which discharge hematocrit is lower than feed hematocrit in microvessels. Plasma skimming has been investigated at a <span class="hlt">bearing</span> gap in a spiral groove <span class="hlt">bearing</span> (SGB), as this has the potential to prevent hemolysis in the SGB of a blood pump. However, it is not clear whether plasma skimming occurs in a blood pump with the SGB, because the hematocrit has not been obtained. The purpose of this study is to verify plasma skimming in an SGB of a centrifugal blood pump by developing a hematocrit measurement method in an SGB. Erythrocyte observation using a high-speed microscope and a <span class="hlt">bearing</span> gap measurement using a laser confocal displacement meter was performed five times. In these tests, bovine blood as a working fluid was diluted with autologous plasma to <span class="hlt">adjust</span> the hematocrit to 1.0%. A resistor was <span class="hlt">adjusted</span> to achieve a pressure head of 100 mm Hg and a flow rate of 5.0 L/min at a rotational speed of 2800 rpm. Hematocrit on the ridge region in the SGB was measured using an image analysis based on motion image of erythrocytes, mean corpuscular volume, the measured <span class="hlt">bearing</span> gap, and a cross-sectional area of erythrocyte. Mean hematocrit on the ridge region in the SGB was linearly reduced from 0.97 to 0.07% with the decreasing mean <span class="hlt">bearing</span> gap from 38 to 21 μm when the rotational speed was changed from 2250 to 3000 rpm. A maximum plasma skimming efficiency of 93% was obtained with a gap of 21 μm. In conclusion, we succeeded in measuring the hematocrit on the ridge region in the SGB of the blood pump. Hematocrit decreased on the ridge region in the SGB and plasma skimming occurred with a <span class="hlt">bearing</span> gap of less than 30 μm in the hydrodynamically levitated centrifugal blood pump. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1172764','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1172764"><span>Apparatus for a compact <span class="hlt">adjustable</span> passive compliant mechanism</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Salisbury, Curt Michael</p> <p>2015-03-17</p> <p>Various technologies described herein pertain to an <span class="hlt">adjustable</span> compliance apparatus. The <span class="hlt">adjustable</span> compliance apparatus includes a shaft, a sleeve element, and a torsion spring. The sleeve element includes a bore there through, where the shaft is positioned through the bore of the sleeve element. Further, the torsion spring includes a plurality of coils, where the shaft is positioned through the plurality of coils. Moreover, the sleeve element is slidable in an axial direction along the shaft between the torsion spring and the shaft. Accordingly, compliance of the <span class="hlt">adjustable</span> compliance apparatus is <span class="hlt">adjustable</span> based on a number of the plurality of coils in <span class="hlt">contact</span> with the sleeve element as positioned along the shaft within the torsion spring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.netl.doe.gov/File%20Library/Research/Oil-Gas/methane%20hydrates/Uchida-ICGH9-839-SUR1.pdf','USGSPUBS'); return false;" href="https://www.netl.doe.gov/File%20Library/Research/Oil-Gas/methane%20hydrates/Uchida-ICGH9-839-SUR1.pdf"><span>Numerical simulations of sand production in interbedded hydrate-<span class="hlt">bearing</span> sediments during depressurization</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Uchida, Shun; Lin, Jeen-Shang; Myshakin, Evgeniy; Seol, Yongkoo; Collett, Timothy S.; Boswell, Ray</p> <p>2017-01-01</p> <p>Geomechanical behavior of hydrate-<span class="hlt">bearing</span> sediments during gas production is complex, involving changes in hydrate-dependent mechanical properties. When interbedded clay layers are present, the complexity is more pronounced because hydrate dissociation tends to occur preferentially in the sediments adjacent to the clay layers due to clay layers acting as a heat source. This would potentially lead to shearing deformation along the sand/clay <span class="hlt">contacts</span> and may contribute to solid migration, which hindered past field-scale gas production tests. This paper presents a near-wellbore simulation of sand/clay interbedded hydrate-<span class="hlt">bearing</span> sediments that have been subjected to depressurization and discusses the effect of clay layers on sand production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750028150&hterms=Quasi+experiment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DQuasi%2Bexperiment','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750028150&hterms=Quasi+experiment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DQuasi%2Bexperiment"><span>Quasi-static analysis of foil journal <span class="hlt">bearings</span> for a Brayton cycle turboalternator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eshel, A.</p> <p>1974-01-01</p> <p>A quasi-static analysis is presented for foil journal <span class="hlt">bearings</span> designed for a NASA Brayton Cycle Turboalternator. Included in the analysis are effects of 'slack' (due to flexural rigidity of the foil), of frictionally restrained extension of the foil-length in <span class="hlt">contact</span> with cylindrical guides, of fluid inertia and compressibility, and of thermal expansion of rotor, foil and supporting structure. Comparisons are made with results of early experiments performed by Licht (1968, 1969) and recent data of Licht and Branger (1973). Variatons of film thickness, foil tension and <span class="hlt">bearing</span> stiffness are presented graphically as functions of pertinent parameters for the case of operation in zero-gravity environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MSSP...54..243K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MSSP...54..243K"><span>Toward a 3D dynamic model of a faulty duplex ball <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kogan, Gideon; Klein, Renata; Kushnirsky, Alex; Bortman, Jacob</p> <p>2015-03-01</p> <p><span class="hlt">Bearings</span> are vital components for safe and proper operation of machinery. Increasing efficiency of <span class="hlt">bearing</span> diagnostics usually requires training of health and usage monitoring systems via expensive and time-consuming ground calibration tests. The main goal of this research, therefore, is to improve <span class="hlt">bearing</span> dynamics modeling tools in order to reduce the time and budget needed to implement the health and usage monitoring approach. The proposed three-dimensional ball <span class="hlt">bearing</span> dynamic model is based on the classic dynamic and kinematic equations. Interactions between the bodies are simulated using non-linear springs combined with dampers described by Hertz-type <span class="hlt">contact</span> relation. The force friction is simulated using the hyperbolic-tangent function. The model allows simulation of a wide range of mechanical faults. It is validated by comparison to known <span class="hlt">bearing</span> behavior and to experimental results. The model results are verified by demonstrating numerical convergence. The model results for the two cases of single and duplex angular ball <span class="hlt">bearings</span> with axial deformation in the outer ring are presented. The qualitative investigation provides insight into <span class="hlt">bearing</span> dynamics, the sensitivity study generalizes the qualitative findings for similar cases, and the comparison to the test results validates model reliability. The article demonstrates the variety of the cases that the 3D <span class="hlt">bearing</span> model can simulate and the findings to which it may lead. The research allowed the identification of new patterns generated by single and duplex <span class="hlt">bearings</span> with axially deformed outer race. It also enlightened the difference between single and duplex <span class="hlt">bearing</span> manifestation. In the current research the dynamic model enabled better understanding of the physical behavior of the faulted <span class="hlt">bearings</span>. Therefore, it is expected that the modeling approach has the potential to simplify and improve the development process of diagnostic algorithms. • A deformed outer race of a single axially loaded <span class="hlt">bearing</span> is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JSV...370..394Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JSV...370..394Z"><span>EEMD-based multiscale ICA method for slewing <span class="hlt">bearing</span> fault detection and diagnosis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Žvokelj, Matej; Zupan, Samo; Prebil, Ivan</p> <p>2016-05-01</p> <p>A novel multivariate and multiscale statistical process monitoring method is proposed with the aim of detecting incipient failures in large slewing <span class="hlt">bearings</span>, where subjective influence plays a minor role. The proposed method integrates the strengths of the Independent Component Analysis (ICA) multivariate monitoring approach with the benefits of Ensemble Empirical Mode Decomposition (EEMD), which adaptively decomposes signals into different time scales and can thus cope with multiscale system dynamics. The method, which was named EEMD-based multiscale ICA (EEMD-MSICA), not only enables <span class="hlt">bearing</span> fault detection but also offers a mechanism of multivariate signal denoising and, in combination with the Envelope Analysis (EA), a diagnostic tool. The multiscale nature of the proposed approach makes the method convenient to cope with data which emanate from <span class="hlt">bearings</span> in complex real-world rotating machinery and frequently represent the cumulative effect of many underlying phenomena occupying different regions in the time-frequency plane. The efficiency of the proposed method was tested on simulated as well as real vibration and Acoustic Emission (AE) signals obtained through conducting an accelerated run-to-failure lifetime experiment on a purpose-built laboratory slewing <span class="hlt">bearing</span> test stand. The ability to detect and locate the early-stage rolling-sliding <span class="hlt">contact</span> fatigue failure of the <span class="hlt">bearing</span> indicates that AE and vibration signals carry sufficient information on the <span class="hlt">bearing</span> condition and that the developed EEMD-MSICA method is able to effectively extract it, thereby representing a reliable <span class="hlt">bearing</span> fault detection and diagnosis strategy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950058727&hterms=journal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Djournal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950058727&hterms=journal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Djournal"><span>Wave journal <span class="hlt">bearing</span> with compressible lubricant--Part 1: The wave <span class="hlt">bearing</span> concept and a comparison to the plain circular <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dimofte, Florin</p> <p>1995-01-01</p> <p>To improve hydrodynamic journal <span class="hlt">bearing</span> steady-state and dynamic performance, a new <span class="hlt">bearing</span> concept, the wave journal <span class="hlt">bearing</span>, was developed at the author's lab. This concept features a waved inner <span class="hlt">bearing</span> diameter. Compared to other alternative <span class="hlt">bearing</span> geometries used to improve <span class="hlt">bearing</span> performance such as spiral or herring-bone grooves, steps, etc., the wave <span class="hlt">bearing</span>'s design is relatively simple and allows the shaft to rotate in either direction. A three-wave <span class="hlt">bearing</span> operating with a compressible lubricant, i.e., gas is analyzed using a numerical code. Its performance is compared to a plain (truly) circular <span class="hlt">bearing</span> over a broad range of <span class="hlt">bearing</span> working parameters, e.g., <span class="hlt">bearing</span> numbers from 0.01 to 100.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10837161','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10837161"><span>Phylogeography of mitochondrial DNA variation in brown <span class="hlt">bears</span> and polar <span class="hlt">bears</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shields, G F; Adams, D; Garner, G; Labelle, M; Pietsch, J; Ramsay, M; Schwartz, C; Titus, K; Williamson, S</p> <p>2000-05-01</p> <p>We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown <span class="hlt">bears</span> from three locations in Alaska and 55 polar <span class="hlt">bears</span> from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar <span class="hlt">bears</span> and brown <span class="hlt">bears</span> as well as to test the extreme uniqueness of mitochondrial DNA types of brown <span class="hlt">bears</span> on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown <span class="hlt">bears</span> of Alaska's Kenai Peninsula in relation to other Alaskan brown <span class="hlt">bears</span> because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown <span class="hlt">bears</span> and polar <span class="hlt">bears</span> would be upheld, (2) the mtDNA uniqueness of brown <span class="hlt">bears</span> of the ABC islands would be upheld, and (3) brown <span class="hlt">bears</span> of the Kenai Peninsula would belong to either clade II or clade III of brown <span class="hlt">bears</span> of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples. Copyright 2000 Academic Press.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.sciencedirect.com/science/article/pii/S1055790399907303','USGSPUBS'); return false;" href="http://www.sciencedirect.com/science/article/pii/S1055790399907303"><span>Phylogeography of mitochondrial DNA variation in brown <span class="hlt">bears</span> and polar <span class="hlt">bears</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Shields, Gerald F.; Adams, Deborah; Garner, Gerald W.; Labelle, Martine; Pietsch, Jacy; Ramsay, Malcolm; Schwartz, Charles; Titus, Kimberly; Williamson, Scott</p> <p>2000-01-01</p> <p>We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown <span class="hlt">bears</span> from three locations in Alaska and 55 polar <span class="hlt">bears</span> from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar <span class="hlt">bears</span> and brown <span class="hlt">bears</span> as well as to test the extreme uniqueness of mitochondrial DNA types of brown <span class="hlt">bears</span> on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown <span class="hlt">bears</span> of Alaska's Kenai Peninsula in relation to other Alaskan brown <span class="hlt">bears</span> because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown <span class="hlt">bears</span> and polar <span class="hlt">bears</span> would be upheld, (2) the mtDNA uniqueness of brown <span class="hlt">bears</span> of the ABC islands would be upheld, and (3) brown <span class="hlt">bears</span> of the Kenai Peninsula would belong to either clade II or clade III of brown <span class="hlt">bears</span> of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140008620','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140008620"><span>Launch Load Resistant Spacecraft Mechanism <span class="hlt">Bearings</span> Made From NiTi Superelastic Intermetallic Materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dellacorte, Christopher; Moore, Lewis E.</p> <p>2014-01-01</p> <p>Compared to conventional <span class="hlt">bearing</span> materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50mm bore ball-<span class="hlt">bearing</span> races are measured to correlate existing flat-plate indentation load capacity data to an actual <span class="hlt">bearing</span> geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi <span class="hlt">contacts</span>; 60NiTi exhibits a static stress capability (3.1GPa) between that of 440C (2.4GPa) and REX20 (3.8GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other <span class="hlt">bearing</span> materials. To quantify this effect, a notional space mechanism, a 5kg mass reaction wheel, was modeled with respect to launch load capability when supported on 440C, 60NiTi and REX20 tool steel <span class="hlt">bearings</span>. For this application, the use of REX20 <span class="hlt">bearings</span> increased the static load capability of the mechanism by a factor of three while the use of 60NiTi <span class="hlt">bearings</span> resulted in an order of magnitude improvement compared to the baseline 440C stainless steel <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.arctic.gov/publications/related/arotus.html','USGSPUBS'); return false;" href="https://www.arctic.gov/publications/related/arotus.html"><span>Estimating the impacts of oil spills on polar <span class="hlt">bears</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Durner, George M.; Amstrup, Steven C.; McDonald, Trent L.</p> <p>2000-01-01</p> <p>The polar <span class="hlt">bear</span> is the apical predator and universal symbol of the Arctic. They occur throughout the Arctic marine environment wherever sea ice is prevalent. In the southern Beaufort Sea, polar <span class="hlt">bears</span> are most common within the area of the outer continental shelf, where the hunt for seals along persistent leads and openings in the ice. Polar <span class="hlt">bears</span> are a significant cultural and subsistence component of the lifestyles of indigenous people. They may also be one of the most important indicators of the health of the Arctic marine environment. Polar <span class="hlt">bears</span> have a late age of maturation, a long inter0brth period, and small liter sizes. These life history features make polar <span class="hlt">bear</span> populations susceptible to natural and human perturbations.Petroleum exploration and extraction have been in progress along the coast of northern Alaska for more than 25 years. Until recently, most activity has taken place on the mainland or at sites connected to the shore by a causeway. In 1999, BP Exploration-Alaska began constructing the first artificial production island designed to transport oil through sub-seafloor pipelines. Other similar projects have been proposed to begin in the next several years.The proximity of oil exploration and development to principal polar <span class="hlt">bear</span> habitats raises concerns, and with the advent of true off-shore development projects, these concerns are compounded. <span class="hlt">Contact</span> with oil and other industrial chemicals by polar <span class="hlt">bears</span>, through grooming, consumption of tainted food, or direct consumption of chemicals, may be lethal. The active ice where polar <span class="hlt">bears</span> hunt is also where spilled oil may be expected to concentrate during spring break-up and autumn freeze-up. Because of this, we could expect that an oil spill in the waters and ice of the continental shelf would have profound effects on polar <span class="hlt">bears</span>. Assessments of the effects of spills, however, have not been done. This report described a promising method for estimating the effects of oil spills on polar <span class="hlt">bears</span> in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22987581','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22987581"><span>Influence of carbon and lipid sources on variation of mercury and other trace elements in polar <span class="hlt">bears</span> (Ursus maritimus).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Routti, Heli; Letcher, Robert J; Born, Erik W; Branigan, Marsha; Dietz, Rune; Evans, Thomas J; McKinney, Melissa A; Peacock, Elizabeth; Sonne, Christian</p> <p>2012-12-01</p> <p>In the present study, the authors investigated the influence of carbon and lipid sources on regional differences in liver trace element (As, Cd, Cu, total Hg, Mn, Pb, Rb, Se, and Zn) concentrations measured in polar <span class="hlt">bears</span> (Ursus maritimus) (n = 121) from 10 Alaskan, Canadian Arctic, and East Greenland subpopulations. Carbon and lipid sources were assessed using δ(13) C in muscle tissue and fatty acid (FA) profiles in subcutaneous adipose tissue as chemical tracers. A negative relationship between total Hg and δ(13) C suggested that polar <span class="hlt">bears</span> feeding in areas with higher riverine inputs of terrestrial carbon accumulate more Hg than <span class="hlt">bears</span> feeding in areas with lower freshwater input. Mercury concentrations were also positively related to the FA 20:1n-9, which is biosynthesized in large amounts in Calanus copepods. This result raises the hypothesis that Calanus glacialis are an important link in the uptake of Hg in the marine food web and ultimately in polar <span class="hlt">bears</span>. Unadjusted total Hg, Se, and As concentrations showed greater geographical variation among polar <span class="hlt">bear</span> subpopulations compared with concentrations <span class="hlt">adjusted</span> for carbon and lipid sources. The Hg concentrations <span class="hlt">adjusted</span> for carbon and lipid sources in Bering-Chukchi Sea polar <span class="hlt">bear</span> liver tissue remained the lowest among subpopulations. Based on these findings, the authors suggest that carbon and lipid sources for polar <span class="hlt">bears</span> should be taken into account when one is assessing spatial and temporal trends of long-range transported trace elements. Copyright © 2012 SETAC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830018943','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830018943"><span>Rolling-Element <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamrock, B. J.; Anderson, W. J.</p> <p>1983-01-01</p> <p>Rolling element <span class="hlt">bearings</span> are a precision, yet simple, machine element of great utility. A brief history of rolling element <span class="hlt">bearings</span> is reviewed and the type of rolling element <span class="hlt">bearings</span>, their geometry and kinematics, as well as the materials they are made from and the manufacturing processes they involve are described. Unloaded and unlubricated rolling element <span class="hlt">bearings</span>, loaded but unlubricated rolling element <span class="hlt">bearings</span> and loaded and lubricated rolling element <span class="hlt">bearings</span> are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..302a2003V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..302a2003V"><span>Leakage Account for Radial Face <span class="hlt">Contact</span> Seal in Aircraft Engine Support</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vinogradov, A. S.; Sergeeva, T. V.</p> <p>2018-01-01</p> <p>The article is dedicated to the development of a methodology for the radial face <span class="hlt">contact</span> seal design taking into consideration the supporting elements deformations in different aircraft engine operating modes. Radial face <span class="hlt">contact</span> seals are popular in the aircraft engines <span class="hlt">bearing</span> support. However, there are no published leakage calculation methodologies of these seals. Radial face <span class="hlt">contact</span> seal leakage is determined by the gap clearance in the carbon seal ring split. In turn, the size gap clearance depends on the deformation of the seal assembly parts and from the engine operation. The article shows the leakage detection sequence in the intershaft radial face <span class="hlt">contact</span> seal of the compressor support for take-off and cruising modes. Evaluated calculated leakage values (2.4 g/s at takeoff and 0.75 g/s at cruising) go with experience in designing seals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010SuScT..23k5011A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SuScT..23k5011A"><span>Levitation properties of superconducting magnetic <span class="hlt">bearings</span> using superconducting coils and bulk superconductors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arai, Yuuki; Seino, Hiroshi; Nagashima, Ken</p> <p>2010-11-01</p> <p>We have been developing a flywheel energy storage system (FESS) with 36 MJ energy capacity for a railway system with superconducting magnetic <span class="hlt">bearings</span> (SMBs). We prepared two kinds of models using superconducting coils and bulk superconductors (SCs). One model demonstrated SMB load capacity of 20 kN and the other model proved non-<span class="hlt">contact</span> stable levitation and non-<span class="hlt">contact</span> rotation with SMBs. Combining these results, the feasibility of a 36 MJ energy capacity FESS with SMBs completely inside a cryostat has been confirmed. In this paper, we report the levitation properties of SMBs in these models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/862503','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/862503"><span>Fluid lubricated <span class="hlt">bearing</span> construction</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Dunning, John R.; Boorse, Henry A.; Boeker, Gilbert F.</p> <p>1976-01-01</p> <p>1. A fluid lubricated thrust <span class="hlt">bearing</span> assembly comprising, in combination, a first <span class="hlt">bearing</span> member having a plain <span class="hlt">bearing</span> surface, a second <span class="hlt">bearing</span> member having a <span class="hlt">bearing</span> surface confronting the <span class="hlt">bearing</span> surface of said first <span class="hlt">bearing</span> member and provided with at least one spiral groove extending inwardly from the periphery of said second <span class="hlt">bearing</span> member, one of said <span class="hlt">bearing</span> members having an axial fluid-tight well, a source of fluid lubricant adjacent to the periphery of said second <span class="hlt">bearing</span> member, and means for relatively rotating said <span class="hlt">bearing</span> members to cause said lubricant to be drawn through said groove and to flow between said <span class="hlt">bearing</span> surfaces, whereby a sufficient pressure is built up between said <span class="hlt">bearing</span> surfaces and in said well to tend to separate said <span class="hlt">bearing</span> surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/2002049','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/2002049"><span>Polar <span class="hlt">Bears</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Amstrup, Steven C.; Douglas, David C.; Reynolds, Patricia E.; Rhode, E.B.</p> <p>2002-01-01</p> <p>Polar <span class="hlt">bears</span> (Ursus maritimus) are hunted throughout most of their range. In addition to hunting polar <span class="hlt">bears</span> of the Beaufort Sea region are exposed to mineral and petroleum extraction and related human activities such as shipping road-building, and seismic testing (Stirling 1990).Little was known at the start of this project about how polar <span class="hlt">bears</span> move about in their environment, and although it was understood that many <span class="hlt">bears</span> travel across political borders, the boundaries of populations had not been delineated (Amstrup 1986, Amstrup et al. 1986, Amstrup and DeMaster 1988, Garner et al. 1994, Amstrup 1995, Amstrup et al. 1995, Amstrup 2000).As human populations increase and demands for polar <span class="hlt">bears</span> and other arctic resources escalate, managers must know the sizes and distributions of the polar <span class="hlt">bear</span> populations. Resource managers also need reliable estimates of breeding rates, reproductive intervals, litter sizes, and survival of young and adults.Our objectives for this research were 1) to determine the seasonal and annual movements of polar <span class="hlt">bears</span> in the Beaufort Sea, 2) to define the boundaries of the population(s) using this region, 3) to determine the size and status of the Beaufort Sea polar <span class="hlt">bear</span> population, and 4) to establish reproduction and survival rates (Amstrup 2000).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70131505','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70131505"><span>Contrasting past and current numbers of <span class="hlt">bears</span> visiting Yellowstone cutthroat trout streams</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Haroldson, Mark A.; Schwartz, Charles C.; Teisberg, Justin E.; Gunther, Kerry A.; Fortin, Jennifer K.; Robbins, Charles T.</p> <p>2014-01-01</p> <p>Spawning cutthroat trout (Oncorhynchus clarkii bouvieri) were historically abundant within tributary streams of Yellowstone Lake within Yellowstone National Park and were a highly digestible source of energy and protein for Yellowstone’s grizzly <span class="hlt">bears</span> (Ursus arctos) and black <span class="hlt">bears</span> (U. americanus). The cutthroat trout population has subsequently declined since the introduction of non-native lake trout (Salvelinus namaycush), and in response to effects of drought and whirling disease (Myxobolus cerebralis). The trout population, duration of spawning runs, and indices of <span class="hlt">bear</span> use of spawning streams had declined in some regions of the lake by 1997–2000. We initiated a 3-year study in 2007 to assess whether numbers of spawning fish, black <span class="hlt">bears</span>, and grizzly <span class="hlt">bears</span> within and alongside stream corridors had changed since 1997– 2000. We estimated numbers of grizzly <span class="hlt">bears</span> and black <span class="hlt">bears</span> by first compiling encounter histories of individual <span class="hlt">bears</span> visiting 48 hair-snag sites along 35 historically fished streams.We analyzed DNA encounter histories with Pradel-recruitment and Jolly-Seber (POPAN) capture-mark-recapture models. When compared to 1997–2000, the current number of spawning cutthroat trout per stream and the number of streams with cutthroat trout has decreased. We estimated that 48 (95% CI¼42–56) male and 23 (95% CI¼21–27) female grizzly <span class="hlt">bears</span> visited the historically fished tributary streams during our study. In any 1- year, 46 to 59 independent grizzly <span class="hlt">bears</span> (8–10% of estimated Greater Yellowstone Ecosystem population) visited these streams. When compared with estimates from the 1997 to 2000 study and <span class="hlt">adjusted</span> for equal effort, the number of grizzly <span class="hlt">bears</span> using the stream corridors decreased by 63%. Additionally, the number of black <span class="hlt">bears</span> decreased between 64% and 84%. We also document an increased proportion of <span class="hlt">bears</span> of both species visiting front-country (i.e., near human development) streams. With the recovery of cutthroat trout, we suggest <span class="hlt">bears</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930020429','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930020429"><span>System for testing <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gibson, John C. (Inventor)</p> <p>1993-01-01</p> <p>Disclosed here is a system for testing <span class="hlt">bearings</span> wherein a pair of spaced <span class="hlt">bearings</span> provides support for a shaft on which is mounted a <span class="hlt">bearing</span> to be tested, this <span class="hlt">bearing</span> being mounted in a <span class="hlt">bearing</span> holder spaced from and in alignment with the pair of <span class="hlt">bearings</span>. The <span class="hlt">bearing</span> holder is provided with an annular collar positioned in an opening in the <span class="hlt">bearing</span> holder for holding the <span class="hlt">bearing</span> to be tested. A screw threaded through the <span class="hlt">bearing</span> holder into engagement with the annular collar can be turned to force the collar radially out of alignment with the pair of <span class="hlt">bearings</span> to apply a radial load to the <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990nosc.rept.....Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990nosc.rept.....Z"><span>Ohmic <span class="hlt">contacts</span> to semiconducting diamond</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zeidler, James R.; Taylor, M. J.; Zeisse, Carl R.; Hewett, C. A.; Delahoussaye, Paul R.</p> <p>1990-10-01</p> <p>Work was carried out to improve the electron beam evaporation system in order to achieve better deposited films. The basic system is an ion pumped vacuum chamber, with a three-hearth, single-gun e-beam evaporator. Four improvements were made to the system. The system was thoroughly cleaned and new ion pump elements, an e-gun beam <span class="hlt">adjust</span> unit, and a more accurate crystal monitor were installed. The system now has a base pressure of 3 X 10(exp -9) Torr, and can easily deposit high-melting-temperature metals such as Ta with an accurately controlled thickness. Improved shadow masks were also fabricated for better alignment and control of corner <span class="hlt">contacts</span> for electrical transport measurements. Appendices include: A Thermally Activated Solid State Reaction Process for Fabricating Ohmic <span class="hlt">Contacts</span> to Semiconducting Diamond; Tantalum Ohmic <span class="hlt">Contacts</span> to Diamond by a Solid State Reaction Process; Metallization of Semiconducting Diamond: Mo, Mo/Au, and Mo/Ni/Au; Specific <span class="hlt">Contact</span> Resistance Measurements of Ohmic Contracts to Diamond; and Electrical Activation of Boron Implanted into Diamond.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2193379','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2193379"><span>Essential Role of Lymph Nodes in <span class="hlt">Contact</span> Hypersensitivity Revealed in Lymphotoxin-α–Deficient Mice</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rennert, Paul D.; Hochman, Paula S.; Flavell, Richard A.; Chaplin, David D.; Jayaraman, Sundararajan; Browning, Jeffrey L.; Fu, Yang-Xin</p> <p>2001-01-01</p> <p>Lymph nodes (LNs) are important sentinal organs, populated by circulating lymphocytes and antigen-<span class="hlt">bearing</span> cells exiting the tissue beds. Although cellular and humoral immune responses are induced in LNs by antigenic challenge, it is not known if LNs are essential for acquired immunity. We examined immune responses in mice that lack LNs due to genetic deletion of lymphotoxin ligands or in utero blockade of membrane lymphotoxin. We report that LNs are absolutely required for generating <span class="hlt">contact</span> hypersensitivity, a T cell–dependent cellular immune response induced by epicutaneous hapten. We show that the homing of epidermal Langerhans cells in response to hapten application is specifically directed to LNs, providing a cellular basis for this unique LN function. In contrast, the spleen cannot mediate <span class="hlt">contact</span> hypersensitivity because antigen-<span class="hlt">bearing</span> epidermal Langerhans cells do not access splenic white pulp. Finally, we formally demonstrate that LNs provide a unique environment essential for generating this acquired immune response by reversing the LN defect in lymphotoxin-α−/− mice, thereby restoring the capacity for <span class="hlt">contact</span> hypersensitivity. PMID:11390430</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AIPC.1569..242D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AIPC.1569..242D"><span>A study on the noise characteristics of polymer ball <span class="hlt">bearings</span> under various lubrication conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dinç, S. K.; Temiz, V.; Kamburoǧlu, E.</p> <p>2013-12-01</p> <p>Polymer <span class="hlt">bearings</span> are generally praised by the manufacturers for running silently. However such statements never go beyond qualitative assumptions. Therefore, studying polymer ball <span class="hlt">bearing</span> noise would have been meaningful solely on the perspective of silent running machinery. On the other hand, the service life of a polymer ball <span class="hlt">bearing</span> is unpredictable and there's no preventive maintenance practice that provides data regarding the condition of a polymer ball <span class="hlt">bearing</span>. In this study, we assume that an investigation of their noise characteristics could also reveal clues concerning their performances. The main objective of this study is to determine the noise characteristics of polymer ball <span class="hlt">bearings</span> lubricated with different lubricant greases of varying viscosity grades through experimental means. Sound pressure level measurements of SKF brand polymer <span class="hlt">bearings</span> with polypropylene rings, polypropylene cage and glass balls were made with a 1/2 inch microphone in 1/3-octave bands, at frequencies up to 12.5 kHz, under various radial loads and rotational speeds. The <span class="hlt">bearings</span> were mounted on a shaft driven by an AC motor with stepless speed control, <span class="hlt">adjustable</span> between 0 - 1400 rpm. The ball <span class="hlt">bearings</span> were running inside an acoustic chamber designed for the insulation of environmental noise and the noise of the motor at target frequencies. The resulting sound pressure level spectra were evaluated and the effects of the lubrication conditions on the noise of the ball <span class="hlt">bearing</span> and possible diagnostic insight that could be gained through studying <span class="hlt">bearing</span> noise characteristics were discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18815238','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18815238"><span>Effects of medial meniscus posterior horn avulsion and repair on tibiofemoral <span class="hlt">contact</span> area and peak <span class="hlt">contact</span> pressure with clinical implications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marzo, John M; Gurske-DePerio, Jennifer</p> <p>2009-01-01</p> <p>Avulsion of the posterior horn attachment of the medial meniscus can compromise load-<span class="hlt">bearing</span> ability, produce meniscus extrusion, and result in tibiofemoral joint-space narrowing, articular cartilage damage, and osteoarthritis. Avulsion of the posterior horn of the medial meniscus will increase peak <span class="hlt">contact</span> pressure and decrease <span class="hlt">contact</span> area in the medial compartment of the knee, and posterior horn repair will restore <span class="hlt">contact</span> area and peak <span class="hlt">contact</span> pressures to values of the control knee. Controlled laboratory study. Eight fresh-frozen human cadaveric knees had tibiofemoral peak <span class="hlt">contact</span> pressures and <span class="hlt">contact</span> area measured in the control state. The posterior horn of the medial meniscus was avulsed from its insertion and knees were retested. The meniscal avulsion was repaired by suture through a transosseous tunnel and the knees were tested a third time. Avulsion of the posterior horn attachment of the medial meniscus resulted in a significant increase in medial joint peak <span class="hlt">contact</span> pressure (from 3841 kPa to 5084 kPa) and a significant decrease in <span class="hlt">contact</span> area (from 594 mm(2) to 474 mm(2)). Repair of the avulsion resulted in restoration of the loading profiles to values equal to the control knee, with values of 3551 kPa for peak pressure and 592 mm(2) for <span class="hlt">contact</span> area. Posterior horn medial meniscal root avulsion leads to deleterious alteration of the loading profiles of the medial joint compartment and results in loss of hoop stress resistance, meniscus extrusion, abnormal loading of the joint, and early knee medial-compartment degenerative changes. The repair technique described restores the ability of the medial meniscus to absorb hoop stress and eliminate joint-space narrowing, possibly decreasing the risk of degenerative disease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970005305','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970005305"><span>Demonstration of the Feasibility of High Temperature <span class="hlt">Bearing</span> Lubrication From Carbonaceous Gases</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Blanchet, Thierry A.; Sawyer, W. Gregory</p> <p>1996-01-01</p> <p>Research has been conducted on silicon nitride pin-on-disk sliding <span class="hlt">contacts</span> at temperatures of up to 520 C, and four-ball rolling <span class="hlt">contacts</span> with silicon nitride balls and 52100 steel or silicon nitride races at 590 C. These tests were conducted in a variety of gaseous environments in order to determine the effects of simulated engine exhaust gas on the carbonaceous gas decomposition lubrication scheme. In rolling tests with steel races and exhaust gas the wear track depth was roughly half that of tests run in nitrogen gas alone. The deposition of lubricous microcrystalline graphitic carbon on the rolling surfaces, generated from the carbon monoxide within the exhaust gas mixture, was verified by microfocused Raman spectroscopy. Ten-fold reductions in rolling wear could be achieved by the exhaust gas atmosphere in cases where water vapor was removed or not present. The exhaust gas mixture alone was not found to provide any lubricating effect on silicon nitride sliding <span class="hlt">contacts</span>, where the rate of wear greatly exceeds the rate of carbon deposition. Directed admixture of acetylene (as low as 5% of the exhaust gas flow rates), has provided reductions in both wear volume and coefficient of friction by factors of 60X and 20X respectively for sliding <span class="hlt">contacts</span> during the initial 80 m of sliding distance. Exhaust gas atmosphere with the acetylene admixture provided 65OX reductions in steady state wear rate compared to that measured for sliding <span class="hlt">contacts</span> in dry N2. Such acetylene admixture also augments the ability of the exhaust gas atmosphere to lubricate high-temperature rolling <span class="hlt">contacts</span>, with up to 25-fold reductions in wear track depth compared to those measured in the presence of N2 alone. In addition to providing some lubricating benefit itself, an important potential role of the exhaust gas from rich mixtures would be to shield <span class="hlt">bearings</span> from 02. Such shielding enables surface deposition of lubricous pyrolytic carbon from the acetylene admixture, instead of combustion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910011898','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910011898"><span>Reduction in <span class="hlt">bearing</span> size due to superconductors in magnetic <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, Dantam K.; Lewis, Paul; Dill, James F.</p> <p>1991-01-01</p> <p>A design concept that reduces the size of magnetic <span class="hlt">bearings</span> is assessed. The small size will enable magnetic <span class="hlt">bearings</span> to fit into limited available <span class="hlt">bearing</span> volume of cryogenic machinery. The design concept, called SUPERC, uses (high Tc) superconductors or high-purity aluminum conductors in windings instead of copper. The relatively high-current density of these conductors reduces the slot radial thickness for windings, which reduces the size of the <span class="hlt">bearings</span>. MTI developed a sizing program called SUPERC that translates the high-current density of these conductors into smaller sized <span class="hlt">bearings</span>. This program was used to size a superconducting <span class="hlt">bearing</span> to carry a 500 lb. load. The sizes of magnetic <span class="hlt">bearings</span> needed by various design concepts are as follows: SUPERC design concept = 3.75 in.; magnet-bias design concept = 5.25 in.; and all electromagnet design concept = 7.0 in. These results indicate that the SUPERC design concept can significantly reduce the size of the <span class="hlt">bearing</span>. This reduction, in turn, reduces the weight and yields a lighter <span class="hlt">bearing</span>. Since the superconductors have inherently near-zero resistance, they are also expected to save power needed for operation considerably.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..372a2030Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..372a2030Z"><span>Application of improved wavelet total variation denoising for rolling <span class="hlt">bearing</span> incipient fault diagnosis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, W.; Jia, M. P.</p> <p>2018-06-01</p> <p>When incipient fault appear in the rolling <span class="hlt">bearing</span>, the fault feature is too small and easily submerged in the strong background noise. In this paper, wavelet total variation denoising based on kurtosis (Kurt-WATV) is studied, which can extract the incipient fault feature of the rolling <span class="hlt">bearing</span> more effectively. The proposed algorithm contains main steps: a) establish a sparse diagnosis model, b) represent periodic impulses based on the redundant wavelet dictionary, c) solve the joint optimization problem by alternating direction method of multipliers (ADMM), d) obtain the reconstructed signal using kurtosis value as criterion and then select optimal wavelet subbands. This paper uses overcomplete rational-dilation wavelet transform (ORDWT) as a dictionary, and <span class="hlt">adjusts</span> the control parameters to achieve the concentration in the time-frequency plane. Incipient fault of rolling <span class="hlt">bearing</span> is used as an example, and the result shows that the effectiveness and superiority of the proposed Kurt- WATV <span class="hlt">bearing</span> fault diagnosis algorithm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19337675','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19337675"><span>Sociocultural <span class="hlt">adjustment</span> among sojourning Malaysian students in Britain: a replication and path analytic extension.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Swami, Viren; Arteche, Adriane; Chamorro-Premuzic, Tomas; Furnham, Adrian</p> <p>2010-01-01</p> <p>The present study examined the sociocultural <span class="hlt">adjustment</span> of 249 sojourning Malaysian undergraduates in Britain. One-hundred and ten Malay and 139 Chinese students enrolled in various courses answered a self-report questionnaire that examined various aspects of sociocultural <span class="hlt">adjustment</span> and socio-demographics. Overall, Malay students reported significantly poorer sociocultural <span class="hlt">adjustment</span> than Chinese students, as well as more negative outcomes on a range of predictors. Path analysis for the total sample showed that higher family income led to greater sociocultural <span class="hlt">adjustment</span>, but partially because it led to more <span class="hlt">contact</span> with host and conationals, better language proficiency, lower perceived cultural differences and less perceived discrimination. Moreover, participants with higher English proficiency were better adapted, but partially because they perceived less cultural differences as well as having more <span class="hlt">contact</span> with host nationals. Additionally, individuals reporting better sociocultural <span class="hlt">adjustment</span> also reported better health statuses. The same model was equally useful at predicting sociocultural <span class="hlt">adjustment</span> for both Malay and Chinese participants. These results are discussed in terms of the role played by income in buffering against the negative aspects of sociocultural <span class="hlt">adjustment</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013RScI...84k3901A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013RScI...84k3901A"><span>Spear-anvil point-<span class="hlt">contact</span> spectroscopy in pulsed magnetic fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arnold, F.; Yager, B.; Kampert, E.; Putzke, C.; Nyéki, J.; Saunders, J.</p> <p>2013-11-01</p> <p>We describe a new design and experimental technique for point-<span class="hlt">contact</span> spectroscopy in non-destructive pulsed magnetic fields up to 70 {T}. Point-<span class="hlt">contact</span> spectroscopy uses a quasi-dc four-point measurement of the current and voltage across a spear-anvil point-<span class="hlt">contact</span>. The <span class="hlt">contact</span> resistance could be <span class="hlt">adjusted</span> over three orders of magnitude by a built-in fine pitch threaded screw. The first measurements using this set-up were performed on both single-crystalline and exfoliated graphite samples in a 150 {ms}, pulse length 70 {T} coil at 4.2 {K} and reproduced the well known point-<span class="hlt">contact</span> spectrum of graphite and showed evidence for a developing high field excitation above 35 T, the onset field of the charge-density wave instability in graphite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29868570','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29868570"><span>Foot Placement Modulation Diminishes for Perturbations Near Foot <span class="hlt">Contact</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vlutters, Mark; Van Asseldonk, Edwin H F; van der Kooij, Herman</p> <p>2018-01-01</p> <p>Whenever a perturbation occurs during walking we have to maintain our balance using the recovery strategies that are available to us. Foot placement <span class="hlt">adjustment</span> is often considered an important recovery strategy. However, because this strategy takes time it is likely a poor option if the foot is close to <span class="hlt">contact</span> at the instant a perturbation occurs. The main goal of this study is to gain a better understanding of how humans deal with balance perturbations during walking if foot placement <span class="hlt">adjustments</span> are constrained by time. Ten healthy subjects walked on an instrumented treadmill and received mediolateral and anteroposterior pelvis perturbations at various instances during the single support phase. The results show that foot placement modulation in the first recovery step following anteroposterior perturbations is fairly invariant of the perturbation magnitude and direction, regardless of the onset instance. For mediolateral perturbations, foot placement <span class="hlt">adjustments</span> strongly modulate with the perturbation magnitude and direction, but these effects diminish when the perturbation onset is closer to the instant of foot <span class="hlt">contact</span>. For most perturbations the first recovery step was consistent across subjects for all onset instances. However, in the second step various strategies arose that were not consistent across subjects, nor within subjects, especially for perturbations applied close to foot <span class="hlt">contact</span>. Despite these different strategies, the COP location following foot <span class="hlt">contact</span> strongly related to the COM velocity throughout these strategies. The results show that humans have various ways to compensate for limited availability of a foot placement strategy, with strategy selection highly dependent on the instant during the gait phase at which the perturbation is applied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhDT.......204L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhDT.......204L"><span>Critical flaw size in silicon nitride ball <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Levesque, George Arthur</p> <p></p> <p>Aircraft engine and <span class="hlt">bearing</span> manufacturers have been aggressively pursuing advanced materials technology systems solutions to meet main shaft-<span class="hlt">bearing</span> needs of advanced military aircraft engines. Ceramic silicon nitride hybrid <span class="hlt">bearings</span> are being developed for such high performance applications. Though silicon nitride exhibits many favorable properties such as high compressive strength, high hardness, a third of the density of steel, low coefficient of thermal expansion, and high corrosion and temperature resistance, they also have low fracture toughness and are susceptible to failure from fatigue spalls emanating from pre-existing surface flaws that can grow under rolling <span class="hlt">contact</span> fatigue (RCF). Rolling elements and raceways are among the most demanding components in aircraft engines due to a combination of high cyclic <span class="hlt">contact</span> stresses, long expected component lifetimes, corrosive environment, and the high consequence of fatigue failure. The cost of these rolling elements increases exponentially with the decrease in allowable flaw size for service applications. Hence the range of 3D non-planar surface flaw geometries subject to RCF is simulated to determine the critical flaw size (CFS) or the largest allowable flaw that does not grow under service conditions. This dissertation is a numerical and experimental investigation of surface flaws in ceramic balls subjected to RCF and has resulted in the following analyses: Crack Shape Determination: the nucleation of surface flaws from ball impact that occurs during the manufacturing process is simulated. By examining the subsurface Hertzian stresses between <span class="hlt">contacting</span> spheres, their applicability to predicting and characterizing crack size and shape is established. It is demonstrated that a wide range of cone and partial cone cracks, observed in practice, can be generated using the proposed approaches. RCF Simulation: the procedure and concerns in modeling nonplanar 3D cracks subject to RCF using FEA for stress intensity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150004049','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150004049"><span>Launch Load Resistant Spacecraft Mechanism <span class="hlt">Bearings</span> Made From NiTi Superelastic Intermetallic Materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DellaCorte, Christopher; Moore, Lewis E., III</p> <p>2014-01-01</p> <p>Compared to conventional <span class="hlt">bearing</span> materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50-mm-bore ball <span class="hlt">bearing</span> races are measured to correlate existing flat-plate indentation load capacity data to an actual <span class="hlt">bearing</span> geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi <span class="hlt">contacts</span>; 60NiTi exhibits a static stress capability (approximately 3.1 GPa) between that of 440C (2.4 GPa) and REX20 (3.8 GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other <span class="hlt">bearing</span> materials. To quantify this effect, a notional space mechanism, a 5-kg mass reaction wheel, was modeled with respect to launch load capability when supported on standard (catalogue geometry) design 440C; 60NiTi and REX20 tool steel <span class="hlt">bearings</span>. For this application, the use of REX20 <span class="hlt">bearings</span> increased the static load capability of the mechanism by a factor of three while the use of 60NiTi <span class="hlt">bearings</span> resulted in an order of magnitude improvement compared to the baseline 440C stainless steel <span class="hlt">bearings</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9650668','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9650668"><span>Performance of a continuous flow ventricular assist device: magnetic <span class="hlt">bearing</span> design, construction, and testing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Allaire, P; Hilton, E; Baloh, M; Maslen, E; Bearnson, G; Noh, D; Khanwilkar, P; Olsen, D</p> <p>1998-06-01</p> <p>A new centrifugal continuous flow ventricular assist device, the CFVAD III, which is fully magnetic <span class="hlt">bearing</span> suspended, has been developed. It has only one moving part (the impeller), has no <span class="hlt">contact</span> (magnetic suspension), is compact, and has minimal heating. A centrifugal impeller of 2 inch outer diameter is driven by a permanent magnet brushless DC motor. This paper discusses the design, construction, testing, and performance of the magnetic <span class="hlt">bearings</span> in the unit. The magnetic suspension consists of an inlet side magnetic <span class="hlt">bearing</span> and an outlet side magnetic <span class="hlt">bearing</span>, each divided into 8 pole segments to control axial and radial displacements as well as angular displacements. The magnetic actuators are composed of several different materials to minimize size and weight while having sufficient load capacity to support the forces on the impeller. Flux levels in the range of 0.1 T are employed in the magnetic <span class="hlt">bearings</span>. Self sensing electronic circuits (without physical sensors) are employed to determine the impellar position and provide the feedback control signal needed for the magnetic <span class="hlt">bearing</span> control loops. The sensors provide position sensitivity of approximately 0.025 mm. A decentralized 5 axis controller has been developed using modal control techniques. Proportional integral derivative controls are used for each axis to levitate the magnetically supported impeller.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29134173','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29134173"><span>Associations of lifetime walking and weight <span class="hlt">bearing</span> exercise with accelerometer-measured high impact physical activity in later life.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Elhakeem, Ahmed; Hannam, Kimberly; Deere, Kevin C; Hartley, April; Clark, Emma M; Moss, Charlotte; Edwards, Mark H; Dennison, Elaine; Gaysin, Tim; Kuh, Diana; Wong, Andrew; Fox, Kenneth R; Cooper, Cyrus; Cooper, Rachel; Tobias, Jon H</p> <p>2017-12-01</p> <p>High impact physical activity (PA) is thought to benefit bone. We examined associations of lifetime walking and weight <span class="hlt">bearing</span> exercise with accelerometer-measured high impact and overall PA in later life. Data were from 848 participants (66.2% female, mean age = 72.4 years) from the Cohort for Skeletal Health in Bristol and Avon, Hertfordshire Cohort Study and MRC National Survey of Health and Development. Acceleration peaks from seven-day hip-worn accelerometer recordings were used to derive counts of high impact and overall PA. Walking and weight <span class="hlt">bearing</span> exercise up to age 18, between 18-29, 30-49 and since age 50 were recalled using questionnaires. Responses in each age category were dichotomised and cumulative scores derived. Linear regression was used for analysis. Greater lifetime walking was related to higher overall, but not high impact PA, whereas greater lifetime weight <span class="hlt">bearing</span> exercise was related to higher overall and high impact PA. For example, fully-<span class="hlt">adjusted</span> differences in log-overall and log-high impact PA respectively for highest versus lowest lifetime scores were: walking [0.224 (0.087, 0.362) and 0.239 (- 0.058, 0.536)], and weight <span class="hlt">bearing</span> exercise [0.754 (0.432, 1.076) and 0.587 (0.270, 0.904)]. For both walking and weight <span class="hlt">bearing</span> exercise, associations were strongest in the 'since age 50' category. Those reporting the most walking and weight <span class="hlt">bearing</span> exercise since age 50 had highest overall and high impact PA, e.g. fully-<span class="hlt">adjusted</span> difference in log-high impact PA versus least walking and weight <span class="hlt">bearing</span> exercise = 0.588 (0.226, 0.951). Promoting walking and weight <span class="hlt">bearing</span> exercise from midlife may help increase potentially osteogenic PA levels in later life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70044427','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70044427"><span>Stable isotopes to detect food-conditioned <span class="hlt">bears</span> and to evaluate human-<span class="hlt">bear</span> management</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hopkins, John B.; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.</p> <p>2012-01-01</p> <p>We used genetic and stable isotope analysis of hair from free-ranging black <span class="hlt">bears</span> (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify <span class="hlt">bears</span> that consume human food, 2) estimate the diets of these <span class="hlt">bears</span>, and 3) evaluate the Yosemite human–<span class="hlt">bear</span> management program. Specifically, we analyzed the isotopic composition of hair from <span class="hlt">bears</span> known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether <span class="hlt">bears</span> with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC <span class="hlt">bears</span>. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–<span class="hlt">bear</span> management, and discussed new metrics to evaluate the overall human–<span class="hlt">bear</span> management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown <span class="hlt">bears</span> sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC <span class="hlt">bears</span> likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to <span class="hlt">bears</span>. In contrast, reactive management was not successful in changing the management status of known FC <span class="hlt">bears</span> to NFC <span class="hlt">bears</span>, or in reducing the contribution of human food to the diets of FC <span class="hlt">bears</span>. Nine known FC <span class="hlt">bears</span> were recaptured on 14 occasions from 2001 to 2007; all <span class="hlt">bears</span> were classified as FC during subsequent recaptures, and human–<span class="hlt">bear</span> management did not reduce the amount of human food in the diets of FC <span class="hlt">bears</span>. Based on our results, we suggest Yosemite continue implementing proactive human–<span class="hlt">bear</span> management, reevaluate reactive management, and consider removing problem <span class="hlt">bears</span> (those involved in repeated <span class="hlt">bear</span> incidents) from the population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830009411','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830009411"><span>Surface profile changes of scuffed <span class="hlt">bearing</span> surfaces. [before and after acid treatment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lauer, J. L.; Fung, S. S.; Jones, W. R., Jr.</p> <p>1982-01-01</p> <p>A phase locked interference microscope capable of resolving depth differences to 30 A and planar displacements of 6000 A was constructed for the examination of the profiles of <span class="hlt">bearing</span> surfaces without physical <span class="hlt">contact</span>. This instrument was used to determine surface chemical reactivity by applying a drop of dilute alcoholic hydrochloric acid and measuring the profile of the solid surface before and after application of this probe. Scuffed <span class="hlt">bearing</span> surfaces reacted much faster than unscuffed ones, but <span class="hlt">bearing</span> surfaces which had been previously exposed to lubricants containing an organic chloride reacted much more slowly. In a separate series of experiments, a number of stainless steel plates were heated in a nitrogen atmosphere to different temperatures and their reactivity examined later at room temperature. The change of surface contour as a result of the probe reaction followed an Arrhenius type relation with respect to heat treatment temperature. This result could have implications on the scuffing mechanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28216586','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28216586"><span>State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-<span class="hlt">Bearing</span> System: An Extension of <span class="hlt">Bearing</span> Diagnostics to <span class="hlt">Bearing</span> Prognostics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tse, Peter W; Wang, Dong</p> <p>2017-02-14</p> <p><span class="hlt">Bearings</span> are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-<span class="hlt">bearing</span> system have been widely analyzed for <span class="hlt">bearing</span> diagnostics. Numerous methods have been proposed to identify different <span class="hlt">bearing</span> faults. However, these methods are unable to predict the future health conditions of <span class="hlt">bearings</span>. To extend <span class="hlt">bearing</span> diagnostics to <span class="hlt">bearing</span> prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-<span class="hlt">bearing</span> system in order to intelligently predict <span class="hlt">bearing</span> remaining useful life (RUL). Firstly, analyses of nonlinear vibration responses were conducted to construct a <span class="hlt">bearing</span> health indicator (BHI) so as to assess the current <span class="hlt">bearing</span> health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict <span class="hlt">bearing</span> RUL. Lastly, a new <span class="hlt">bearing</span> acceleration life testing setup was designed to collect natural <span class="hlt">bearing</span> degradation data, which were used to validate the effectiveness of the proposed <span class="hlt">bearing</span> prognostic method. Results show that the prediction accuracy of the proposed <span class="hlt">bearing</span> prognostic method is promising and the proposed <span class="hlt">bearing</span> prognostic method is able to reflect future <span class="hlt">bearing</span> health conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5335936','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5335936"><span>State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-<span class="hlt">Bearing</span> System: An Extension of <span class="hlt">Bearing</span> Diagnostics to <span class="hlt">Bearing</span> Prognostics</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tse, Peter W.; Wang, Dong</p> <p>2017-01-01</p> <p><span class="hlt">Bearings</span> are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-<span class="hlt">bearing</span> system have been widely analyzed for <span class="hlt">bearing</span> diagnostics. Numerous methods have been proposed to identify different <span class="hlt">bearing</span> faults. However, these methods are unable to predict the future health conditions of <span class="hlt">bearings</span>. To extend <span class="hlt">bearing</span> diagnostics to <span class="hlt">bearing</span> prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-<span class="hlt">bearing</span> system in order to intelligently predict <span class="hlt">bearing</span> remaining useful life (RUL). Firstly, analyses of nonlinear vibration responses were conducted to construct a <span class="hlt">bearing</span> health indicator (BHI) so as to assess the current <span class="hlt">bearing</span> health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict <span class="hlt">bearing</span> RUL. Lastly, a new <span class="hlt">bearing</span> acceleration life testing setup was designed to collect natural <span class="hlt">bearing</span> degradation data, which were used to validate the effectiveness of the proposed <span class="hlt">bearing</span> prognostic method. Results show that the prediction accuracy of the proposed <span class="hlt">bearing</span> prognostic method is promising and the proposed <span class="hlt">bearing</span> prognostic method is able to reflect future <span class="hlt">bearing</span> health conditions. PMID:28216586</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050180250','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050180250"><span>Effect of Rolling <span class="hlt">Bearing</span> Refurbishment and Restoration on <span class="hlt">Bearing</span> Life and Reliability</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, Erwin V.; Branzai, Emanuel V.</p> <p>2005-01-01</p> <p>For nearly four decades it has been a practice in commercial and military aircraft application that rolling-element <span class="hlt">bearings</span> removed at maintenance or overhaul be reworked and returned to service. The work presented extends previously reported <span class="hlt">bearing</span> life analysis to consider the depth (Z(45)) to maximum shear stress (45) on stressed volume removal and the effect of replacing the rolling elements with a new set. A simple algebraic relationship was established to determine the L(10) life of <span class="hlt">bearing</span> races subject to <span class="hlt">bearing</span> rework. Depending on the extent of rework and based upon theoretical analysis, representative life factors (LF) for <span class="hlt">bearings</span> subject to rework ranged from 0.87 to 0.99 the lives of new <span class="hlt">bearings</span>. Based on <span class="hlt">bearing</span> endurance data, 92 percent of the <span class="hlt">bearing</span> sets that would be subject to rework would result in L(10) lives equaling and/or exceeding that predicted for new <span class="hlt">bearings</span> with the remaining 8 percent having the potential to achieve the analytically predicted life of new <span class="hlt">bearings</span> when one of the rings is replaced at rework.. The potential savings from <span class="hlt">bearing</span> rework varies from 53 to 82 percent that of new <span class="hlt">bearings</span> depending on the cost, size and complexity of the <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22590723-contact-area-rough-spheres-large-scale-simulations-simple-scaling-laws','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22590723-contact-area-rough-spheres-large-scale-simulations-simple-scaling-laws"><span><span class="hlt">Contact</span> area of rough spheres: Large scale simulations and simple scaling laws</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Pastewka, Lars, E-mail: lars.pastewka@kit.edu; Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218; Robbins, Mark O., E-mail: mr@pha.jhu.edu</p> <p>2016-05-30</p> <p>We use molecular simulations to study the nonadhesive and adhesive atomic-scale <span class="hlt">contact</span> of rough spheres with radii ranging from nanometers to micrometers over more than ten orders of magnitude in applied normal load. At the lowest loads, the interfacial mechanics is governed by the <span class="hlt">contact</span> mechanics of the first asperity that touches. The dependence of <span class="hlt">contact</span> area on normal force becomes linear at intermediate loads and crosses over to Hertzian at the largest loads. By combining theories for the limiting cases of nominally flat rough surfaces and smooth spheres, we provide parameter-free analytical expressions for <span class="hlt">contact</span> area over the wholemore » range of loads. Our results establish a range of validity for common approximations that neglect curvature or roughness in modeling objects on scales from atomic force microscope tips to ball <span class="hlt">bearings</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA614145','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA614145"><span>A Primer on Vibrational Ball <span class="hlt">Bearing</span> Feature Generation for Prognostics and Diagnostics Algorithms</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2015-03-01</p> <p>Atlas -Marks (Cone-Shaped Kernel) ........................................................36 8.7.7 Hilbert-Huang Transform...<span class="hlt">bearing</span> surface and eventually progress to the surface where the material will separate. Also known as pitting, spalling, or flaking. • Wear ...normal degradation caused by dirt and foreign particles causing abrasion of the <span class="hlt">contact</span> surfaces over time resulting in alterations in the raceway and</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26736252','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26736252"><span>Evaluation of erythrocyte flow at a <span class="hlt">bearing</span> gap in a hydrodynamically levitated centrifugal blood pump.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Murashige, Tomotaka; Kosaka, Ryo; Sakota, Daisuke; Nishida, Masahiro; Kawaguchi, Yasuo; Yamane, Takashi; Maruyama, Osamu</p> <p>2015-01-01</p> <p>We have developed a hydrodynamically levitated centrifugal blood pump for extracorporeal circulatory support. In the blood pump, a spiral groove <span class="hlt">bearing</span> was adopted for a thrust <span class="hlt">bearing</span>. In the spiral groove <span class="hlt">bearing</span>, separation of erythrocytes and plasma by plasma skimming has been postulated to occur. However, it is not clarified that plasma skimming occurs in a spiral groove <span class="hlt">bearing</span>. The purpose of this study is to verify whether plasma skimming occurs in the spiral groove <span class="hlt">bearing</span> of a hydrodynamically levitated centrifugal blood pump. For evaluation of plasma skimming in the spiral groove <span class="hlt">bearing</span>, an impeller levitation performance test using a laser focus displacement meter and a microscopic visualization test of erythrocyte flow using a high-speed microscope were conducted. Bovine blood diluted with autologous plasma to <span class="hlt">adjust</span> hematocrit to 1.0% was used as a working fluid. Hematocrit on the ridge region in the spiral groove <span class="hlt">bearing</span> was estimated using image analysis. As a result, hematocrits on the ridge region with gaps of 45 μm, 31 μm, and 25 μm were calculated as 1.0%, 0.6%, and 0.3%, respectively. Maximum skimming efficiency in this study was calculated as 70% with a gap of 25 μm. We confirmed that separation of erythrocyte and plasma occurred in the spiral groove <span class="hlt">bearing</span> with decrease in <span class="hlt">bearing</span> gap in a hydrodynamically levitated centrifugal blood pump.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770014497','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770014497"><span>Performance of large-bore tapered-roller <span class="hlt">bearings</span> under combined radial and thrust load at shaft speeds to 15,000 rpm</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, R. J.; Signer, H. R.</p> <p>1977-01-01</p> <p>The performance of 120.65-mm bore tapered roller <span class="hlt">bearings</span> was investigated at shaft speeds up to 15,000 rpm. Temperature distribution and <span class="hlt">bearing</span> heat generation were determined as a function of shaft speed, radial and thrust loads, lubricant flow rate, and lubricant inlet temperature. Lubricant was supplied by either jets or by a combination of holes through the cone directly to the cone-rib <span class="hlt">contact</span> and jets at the roller small-end side. Cone-rib lubrication significantly improved high-speed tapered-roller <span class="hlt">bearing</span> performance, yielding lower cone-face temperatures and lower power loss and allowing lower lubricant flow rates for a given speed condition. <span class="hlt">Bearing</span> temperatures increased with increased shaft speed and decreased with increased lubricant flow rate. <span class="hlt">Bearing</span> power loss increased with increased shaft speed and increased lubricant flow rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010033258','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010033258"><span>Experimental Evaluation of Journal <span class="hlt">Bearing</span> Stability and New Gas <span class="hlt">Bearing</span> Material</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keith, Theo G., Jr.; Dimofte, Florin</p> <p>2001-01-01</p> <p>It has been estimated that the noise levels in aircraft engine transmissions can be reduced by as much as 10 dB through the use of journal <span class="hlt">bearings</span>. The potential benefits of lower noise levels include reduced wear, longer gear life and enhanced comfort for passengers and crew. Based on this concept the journal-thrust wave <span class="hlt">bearing</span> was analyzed and its performance was evaluated. Numerical codes, developed over the past 30 years by Dr. Dimofte, were used to predict the performance of the <span class="hlt">bearing</span>. The wave <span class="hlt">bearing</span> is a fluid film <span class="hlt">bearing</span> and therefore was analyzed using the Reynolds pressure equation. The formulation includes turbulent flow concepts and possesses a viscosity-temperature correction. The centrifugal growth of the <span class="hlt">bearing</span> diameter and the deformation of the <span class="hlt">bearing</span> under gear loads were also incorporated into the code. An experimental rig was developed to test the journal-thrust wave <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26264178','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26264178"><span>Comparison of Alignment Correction Angles Between Fixed-<span class="hlt">Bearing</span> and Mobile-<span class="hlt">Bearing</span> UKA.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Inoue, Atsuo; Arai, Yuji; Nakagawa, Shuji; Inoue, Hiroaki; Yamazoe, Shoichi; Kubo, Toshikazu</p> <p>2016-01-01</p> <p>Good outcomes have been reported with both fixed-<span class="hlt">bearing</span> and mobile-<span class="hlt">bearing</span> unicompartmental knee arthroplasty (UKA). However, overcorrected alignment could induce the progression of arthritis on the non-arthroplasty side. Changes of limb alignment after UKA with both types of <span class="hlt">bearings</span> (fixed <span class="hlt">bearing</span>: 24 knees, mobile <span class="hlt">bearing</span>: 28 knees) were investigated. The mean difference between the preoperative standing femoral-tibial angle (FTA) and postoperative standing FTA was significantly larger in mobile <span class="hlt">bearing</span> UKA group. In fixed-<span class="hlt">bearing</span> UKA, there must be some laxity in MCL tension so that a 2-mm tension gauge can be inserted. In mobile-<span class="hlt">bearing</span> UKA, appropriate MCL tension is needed to prevent <span class="hlt">bearing</span> dislocation. This difference in MCL tension may have caused the difference in the correction angle between the groups. Copyright © 2016 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS1016a2015Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS1016a2015Y"><span>Simulation study on dynamics model of two kinds of on-orbit soft-<span class="hlt">contact</span> mechanism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ye, X.; Dong, Z. H.; Yang, F.</p> <p>2018-05-01</p> <p>Aiming at the problem that the operating conditions of the space manipulator is harsh and the space manipulator could not <span class="hlt">bear</span> the large collision momentum, this paper presents a new concept and technical method, namely soft <span class="hlt">contact</span> technology. Based on ADAMS dynamics software, this paper compares and simulates the mechanism model of on-orbit soft-<span class="hlt">contact</span> mechanism based on the bionic model and the integrated double joint model. The main purpose is to verify the path planning ability and the momentum buffering ability based on the different design concept mechanism. The simulation results show that both the two mechanism models have the path planning function before the space target <span class="hlt">contact</span>, and also has the momentum buffer and controllability during the space target <span class="hlt">contact</span> process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70021142','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70021142"><span>Chlorine-<span class="hlt">bearing</span> amphiboles from the Fraser mine, Sudbury, Ontario, Canada: Description and crystal chemistry</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McCormick, K.A.; McDonald, A.M.</p> <p>1999-01-01</p> <p>Three chemically distinct populations of Cl-<span class="hlt">bearing</span> amphibole have been recognized in association with <span class="hlt">contact</span> Ni-Cu ore deposits in Footwall Breccia at the Fraser mine, Sudbury, Ontario. The first population, defined as halogen-poor (700 ppm) and F (2500 ppm). These rocks thus may have been a significant contributor to the fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/tem/0339/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/tem/0339/report.pdf"><span>Preliminary summary review of thorium-<span class="hlt">bearing</span> mineral occurrences in Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bates, Robert G.; Wedow, Helmuth</p> <p>1952-01-01</p> <p>Thorium-<span class="hlt">bearing</span> minerals are known at 47 localities in Alaska. At these localities the thorium occurs as a major constituent or in minor amounts as an impurity in one or more of the following 12 minerals: allanite, columbite, ellsworthite, eschynite, gummite, monazite, orangite, parisite, thorianite, thorite, xenotime, and zircon. In addition other minerals, such as biotite and sphene, are radioactive and may contain thorium. Several unidentified columbate minerals with uranium or thorium and uranium as major constituents have been recognized at some localities. The distribution, by type of deposit, of the 57 thorium occurrences is as follows: lode - 3, lode and placer - 1, granitic rock - 3, granitic rock and related placer - 14, and placer - 26. Of the four lode occurrences only the radioactive veins at Salmon Bay in southeastern Alaska and the <span class="hlt">contact</span> metamorphic deposit in the Nixon Fork area of central Alaska warrant further consideration, although insufficient data are available to determine whether these two deposits have commercial possibilities. The remaining occurrences of thorium-<span class="hlt">bearing</span> minerals in Alaska are limited to placer deposits and disseminations of accessory minerals in granitic rocks. In most of these occurrences the thorium-<span class="hlt">bearing</span> minerals occur in only trace amounts and consequently warrent little further consideration. More data are needed to determine the possibilities of byproduct recovery of thorium-<span class="hlt">bearing</span> minerals from several of the gold and tin placers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21655893','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21655893"><span>Comparison of the low <span class="hlt">contact</span> stress and press fit condylar rotating-platform mobile-<span class="hlt">bearing</span> prostheses in total knee arthroplasty: a prospective randomized study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Young-Hoo; Kim, Jun-Shik; Park, Jang-Won; Joo, Jong-Hwan</p> <p>2011-06-01</p> <p>To our knowledge, no study to date has compared the clinical results of posterior cruciate-sacrificing mobile-<span class="hlt">bearing</span> total knee replacements with those of posterior-stabilized mobile-<span class="hlt">bearing</span> total knee replacements in the same patients. The purpose of the present study was to compare the clinical and radiographic results of these two designs. We hypothesized that the results would be better for knees treated with the posterior-stabilized mobile-<span class="hlt">bearing</span> prosthesis. The present study consisted of a consecutive series of 107 female patients (mean age, 66.8 years) who underwent bilateral simultaneous total knee arthroplasty at the same surgical setting. All of these patients received a posterior cruciate-sacrificing mobile-<span class="hlt">bearing</span> prosthesis in one knee and a posterior-stabilized mobile-<span class="hlt">bearing</span> prosthesis in the contralateral knee. At the time of each follow-up (mean, 7.4 years; range, seven to 7.6 years), the patients were assessed clinically. The mean postoperative Knee Society knee score (96 compared with 97 points) and Hospital for Special Surgery knee score (93 compared with 94 points) were similar between the two groups. At the time of the latest follow-up, the average range of motion was 127.7° (range, 70° to 150°) in the knees with a posterior cruciate-sacrificing mobile-<span class="hlt">bearing</span> prosthesis and 132.4° (range, 90° to 150°) in the knees with a posterior-stabilized mobile-<span class="hlt">bearing</span> prosthesis. With a margin of error of the manual measurement of 5°, this difference was not significant. The estimated survival rate was 97.2% (95% confidence interval, 91% to 99%) at seven years in the posterior-cruciate sacrificing mobile-<span class="hlt">bearing</span> prosthesis group and 98.1% (95% confidence interval, 92% to 99%) at seven years in the posterior-stabilized mobile-<span class="hlt">bearing</span> prosthesis group. After a minimum duration of follow-up of seven years, we found no significant differences between the two groups with regard to the clinical and radiographic results, including knee range of motion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070003749','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070003749"><span><span class="hlt">Bearing</span>-Load Modeling and Analysis Study for Mechanically Connected Structures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Knight, Norman F., Jr.</p> <p>2006-01-01</p> <p><span class="hlt">Bearing</span>-load response for a pin-loaded hole is studied within the context of two-dimensional finite element analyses. Pin-loaded-hole configurations are representative of mechanically connected structures, such as a stiffener fastened to a rib of an isogrid panel, that are idealized as part of a larger structural component. Within this context, the larger structural component may be idealized as a two-dimensional shell finite element model to identify load paths and high stress regions. Finite element modeling and analysis aspects of a pin-loaded hole are considered in the present paper including the use of linear and nonlinear springs to simulate the pin-<span class="hlt">bearing</span> <span class="hlt">contact</span> condition. Simulating pin-connected structures within a two-dimensional finite element analysis model using nonlinear spring or gap elements provides an effective way for accurate prediction of the local effective stress state and peak forces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26634122','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26634122"><span>Modeling workplace <span class="hlt">contact</span> networks: The effects of organizational structure, architecture, and reporting errors on epidemic predictions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Potter, Gail E; Smieszek, Timo; Sailer, Kerstin</p> <p>2015-09-01</p> <p>Face-to-face social <span class="hlt">contacts</span> are potentially important transmission routes for acute respiratory infections, and understanding the <span class="hlt">contact</span> network can improve our ability to predict, contain, and control epidemics. Although workplaces are important settings for infectious disease transmission, few studies have collected workplace <span class="hlt">contact</span> data and estimated workplace <span class="hlt">contact</span> networks. We use <span class="hlt">contact</span> diaries, architectural distance measures, and institutional structures to estimate social <span class="hlt">contact</span> networks within a Swiss research institute. Some <span class="hlt">contact</span> reports were inconsistent, indicating reporting errors. We <span class="hlt">adjust</span> for this with a latent variable model, jointly estimating the true (unobserved) network of <span class="hlt">contacts</span> and duration-specific reporting probabilities. We find that <span class="hlt">contact</span> probability decreases with distance, and that research group membership, role, and shared projects are strongly predictive of <span class="hlt">contact</span> patterns. Estimated reporting probabilities were low only for 0-5 min <span class="hlt">contacts</span>. <span class="hlt">Adjusting</span> for reporting error changed the estimate of the duration distribution, but did not change the estimates of covariate effects and had little effect on epidemic predictions. Our epidemic simulation study indicates that inclusion of network structure based on architectural and organizational structure data can improve the accuracy of epidemic forecasting models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4663701','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4663701"><span>Modeling workplace <span class="hlt">contact</span> networks: The effects of organizational structure, architecture, and reporting errors on epidemic predictions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Potter, Gail E.; Smieszek, Timo; Sailer, Kerstin</p> <p>2015-01-01</p> <p>Face-to-face social <span class="hlt">contacts</span> are potentially important transmission routes for acute respiratory infections, and understanding the <span class="hlt">contact</span> network can improve our ability to predict, contain, and control epidemics. Although workplaces are important settings for infectious disease transmission, few studies have collected workplace <span class="hlt">contact</span> data and estimated workplace <span class="hlt">contact</span> networks. We use <span class="hlt">contact</span> diaries, architectural distance measures, and institutional structures to estimate social <span class="hlt">contact</span> networks within a Swiss research institute. Some <span class="hlt">contact</span> reports were inconsistent, indicating reporting errors. We <span class="hlt">adjust</span> for this with a latent variable model, jointly estimating the true (unobserved) network of <span class="hlt">contacts</span> and duration-specific reporting probabilities. We find that <span class="hlt">contact</span> probability decreases with distance, and that research group membership, role, and shared projects are strongly predictive of <span class="hlt">contact</span> patterns. Estimated reporting probabilities were low only for 0–5 min <span class="hlt">contacts</span>. <span class="hlt">Adjusting</span> for reporting error changed the estimate of the duration distribution, but did not change the estimates of covariate effects and had little effect on epidemic predictions. Our epidemic simulation study indicates that inclusion of network structure based on architectural and organizational structure data can improve the accuracy of epidemic forecasting models. PMID:26634122</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001SPIE.4389..216X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001SPIE.4389..216X"><span><span class="hlt">Bearing</span> monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Roger; Stevenson, Mark W.; Kwan, Chi-Man; Haynes, Leonard S.</p> <p>2001-07-01</p> <p>At Ford Motor Company, thrust <span class="hlt">bearing</span> in drill motors is often damaged by metal chips. Since the vibration frequency is several Hz only, it is very difficult to use accelerometers to pick up the vibration signals. Under the support of Ford and NASA, we propose to use a piezo film as a sensor to pick up the slow vibrations of the <span class="hlt">bearing</span>. Then a neural net based fault detection algorithm is applied to differentiate normal <span class="hlt">bearing</span> from bad <span class="hlt">bearing</span>. The first step involves a Fast Fourier Transform which essentially extracts the significant frequency components in the sensor. Then Principal Component Analysis is used to further reduce the dimension of the frequency components by extracting the principal features inside the frequency components. The features can then be used to indicate the status of <span class="hlt">bearing</span>. Experimental results are very encouraging.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26744604','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26744604"><span>Total <span class="hlt">contact</span> cast wall load in patients with a plantar forefoot ulcer and diabetes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Begg, Lindy; McLaughlin, Patrick; Vicaretti, Mauro; Fletcher, John; Burns, Joshua</p> <p>2016-01-01</p> <p>The total <span class="hlt">contact</span> cast (TCC) is an effective intervention to reduce plantar pressure in patients with diabetes and a plantar forefoot ulcer. The walls of the TCC have been indirectly shown to <span class="hlt">bear</span> approximately 30 % of the plantar load. A new direct method to measure inside the TCC walls with capacitance sensors has shown that the anterodistal and posterolateral-distal regions of the lower leg <span class="hlt">bear</span> the highest load. The objective of this study was to directly measure these two regions in patients with Diabetes and a plantar forefoot ulcer to further understand the mechanism of pressure reduction in the TCC. A TCC was applied to 17 patients with Diabetes and a plantar forefoot ulcer. TCC wall load (<span class="hlt">contact</span> area, peak pressure and max force) at the anterodistal and posterolateral-distal regions of the lower leg were evaluated with two capacitance sensor strips measuring 90 cm(2) (pliance®, novel GmbH, Germany). Plantar load (<span class="hlt">contact</span> area, peak pressure and max force) was measured with a capacitance sensor insole (pedar®, novel GmbH, Germany) placed inside the TCC. Both pedar® and pliance® collected data simultaneously at a sampling rate of 50Hz synchronised to heel strike. The magnitude of TCC wall load as a proportion of plantar load was calculated. The TCC walls were then removed to determine the differences in plantar loading between the TCC and the cut down shoe-cast for the whole foot, rearfoot, midfoot and forefoot (region of interest). TCC wall load was substantial. The anterodistal lower leg recorded 48 % and the posterolateral-distal lower leg recorded 34 % of plantar <span class="hlt">contact</span> area. The anterodistal lower leg recorded 28 % and the posterolateral-distal lower leg recorded 12 % of plantar peak pressure. The anterodistal lower leg recorded 12 % and the posterolateral-distal lower leg recorded 4 % of plantar max force. There were significant differences in plantar load between the TCC and the cut down shoe-cast for the whole foot, rearfoot, midfoot and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890066887&hterms=chromium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dchromium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890066887&hterms=chromium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dchromium"><span>Tribological composition optimization of chromium-carbide-based solid lubricant coatings for foil gas <span class="hlt">bearings</span> at temperatures to 650 C</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dellacorte, Christopher</p> <p>1988-01-01</p> <p>The determination of the tribilogically optimum composition of chromium-carbide-based solid lubricant coatings using a foil gas <span class="hlt">bearing</span> test apparatus is described. The coatings contain a wear resistant chromium carbide `base stock' with the lubricant additives silver and BaF2-CaF2 eutectic. The coating composition is optimized for air-lubricated foil gas <span class="hlt">bearings</span> at temperatures ranging from 25 to 650 C. The various compositions were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized Ni-Cr alloy foils, and the test <span class="hlt">bearings</span> were subjected to repeated start-stop cycles under a <span class="hlt">bearing</span> unit of 14 kPa. Sliding <span class="hlt">contact</span> between the coated journal and the smooth foil occurs during <span class="hlt">bearing</span> start-up before lift-off or hydrodynamic lubrication by the air film and during <span class="hlt">bearing</span> coast-down. The <span class="hlt">bearings</span> were tested for 9000 start-stop cycles or until specimen reached a predetermined failure level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..307a2045E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..307a2045E"><span>Influence of repeated quenching-tempering on spheroidized carbide area in JIS SUJ2 <span class="hlt">bearing</span> steel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Egawa, K.; Yoshida, I.; Yoshida, H.; Mizobe, K.; Kida, K.</p> <p>2018-02-01</p> <p>High-carbon high-strength JIS-SUJ2 <span class="hlt">bearing</span> steel is mainly used for rolling <span class="hlt">contact</span> applications which require high fatigue strength. We had applied repeated quenching which refine the prior austenite grains to this steel. In this work, we prepared JIS SUJ2 <span class="hlt">bearing</span> steel bar specimens which were quenched three times (Q3T1) and quenched-tempered three times (QTQTQT) in order to investigate the influence of tempering before quenching on the microstructure. The specimens were etched by picral to observe the microstructure. We found that the spheroidized carbide area was important for the prior austenite grain formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910033676&hterms=moving+stress&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmoving%2Bstress','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910033676&hterms=moving+stress&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmoving%2Bstress"><span>Three-dimensional stress intensity factor analysis of a surface crack in a high-speed <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ballarini, Roberto; Hsu, Yingchun</p> <p>1990-01-01</p> <p>The boundary element method is applied to calculate the stress intensity factors of a surface crack in the rotating inner raceway of a high-speed roller <span class="hlt">bearing</span>. The three-dimensional model consists of an axially stressed surface cracked plate subjected to a moving Hertzian <span class="hlt">contact</span> loading. A multidomain formulation and singular crack-tip elements were employed to calculate the stress intensity factors accurately and efficiently for a wide range of configuration parameters. The results can provide the basis for crack growth calculations and fatigue life predictions of high-performance rolling element <span class="hlt">bearings</span> that are used in aircraft engines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920007117','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920007117"><span>User's manual for tooth <span class="hlt">contact</span> analysis of face-milled spiral bevel gears with given machine-tool settings</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litvin, Faydor L.; Zhang, YI; Chen, Jui-Sheng</p> <p>1991-01-01</p> <p>Research was performed to develop a computer program that will: (1) simulate the meshing and <span class="hlt">bearing</span> <span class="hlt">contact</span> for face milled spiral beval gears with given machine tool settings; and (2) to obtain the output, some of the data is required for hydrodynamic analysis. It is assumed that the machine tool settings and the blank data will be taken from the Gleason summaries. The theoretical aspects of the program are based on 'Local Synthesis and Tooth <span class="hlt">Contact</span> Analysis of Face Mill Milled Spiral Bevel Gears'. The difference between the computer programs developed herein and the other one is as follows: (1) the mean <span class="hlt">contact</span> point of tooth surfaces for gears with given machine tool settings must be determined iteratively, while parameters (H and V) are changed (H represents displacement along the pinion axis, V represents the gear displacement that is perpendicular to the plane drawn through the axes of the pinion and the gear of their initial positions), this means that when V differs from zero, the axis of the pionion and the gear are crossed but not intersected; (2) in addition to the regular output data (transmission errors and <span class="hlt">bearing</span> <span class="hlt">contact</span>), the new computer program provides information about the <span class="hlt">contacting</span> force for each <span class="hlt">contact</span> point and the sliding and the so-called rolling velocity. The following topics are covered: (1) instructions for the users as to how to insert the input data; (2) explanations regarding the output data; (3) numerical example; and (4) listing of the program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24845695','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24845695"><span>Kinetic and kinematic <span class="hlt">adjustments</span> during perturbed walking across visible and camouflaged drops in ground level.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Müller, Roy; Tschiesche, Kevin; Blickhan, Reinhard</p> <p>2014-07-18</p> <p>Walking in even the most familiar environment posesses a challenge to humans due to continuously changing surface conditions such as compliance, slip, or level. These changes can be visible or invisible due to camouflage. In order to prevent falling, camouflaged changes in the ground level in particular require a quick response of the locomotor system. For ten subjects we investigated kinematics and ground reaction forces of two consecutive <span class="hlt">contacts</span> while they were walking across visible (drops of 0, -5 and -10 cm at second <span class="hlt">contact</span>) and camouflaged (drops of 0 or -5 cm, and drops of 0 or -10 cm at second <span class="hlt">contact</span>) changes in the ground level. For both situations we found significant kinetic and kinematic <span class="hlt">adjustments</span> during the perturbed second <span class="hlt">contact</span> but also one step earlier, in the preparatory first <span class="hlt">contact</span>. During walking across visible changes in the ground level, second peak ground reaction force at first <span class="hlt">contact</span> decreased whereas the drop height increased at the second <span class="hlt">contact</span>. In addition, at the end of this first <span class="hlt">contact</span> the ankle and knee were more flexed and the trunk was more erect compared to level walking. During the perturbed second <span class="hlt">contact</span>, first peak ground reaction force increased with drop height, whereas kinematic <span class="hlt">adjustments</span> at touchdown were less. The visual perception of the perturbation facilitated prior adaptations. During walking across camouflaged changes in ground level such a visually guided preadaptation was not possible and the adaptations prior to the perturbation were less than those observed during walking across visible changes in the ground. However, when stepping into a camouflaged drop, the kinetic and kinematic <span class="hlt">adjustments</span> became more obvious and they increased with increasing camouflaged drop height. Copyright © 2014 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25446818','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25446818"><span>Measles-mumps-rubella vaccination and respiratory syncytial virus-associated hospital <span class="hlt">contact</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sørup, Signe; Benn, Christine Stabell; Stensballe, Lone Graff; Aaby, Peter; Ravn, Henrik</p> <p>2015-01-01</p> <p>The live measles vaccine has been associated with lower non-measles mortality and admissions in low-income countries. The live measles-mumps-rubella vaccine has also been associated with lower rate of admissions with any type of infection in Danish children; the association was strongest for admissions with lower respiratory infections. To examine whether measles, mumps, and rubella (MMR) vaccination was associated with reduced rate of hospital <span class="hlt">contact</span> related to respiratory syncytial virus (RSV) in a high-income country. Nationwide cohort study of laboratory-confirmed RSV hospital <span class="hlt">contacts</span> at age 14-23 months in all children born in Denmark 1997-2002 who had already received the vaccine against diphtheria, tetanus, pertussis (acellular), polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) at the recommended ages of 3, 5, and 12 months. The study included 888 RSV hospital <span class="hlt">contacts</span> in 128,588 person years of follow up (rate 6.8/1000 person years). Having MMR as the most recent vaccine was associated with a reduced rate of RSV hospital <span class="hlt">contacts</span> compared with having DTaP-IPV-Hib as the most recent vaccine (Incidence rate ratio (IRR), 0.75; 95% confidence interval (CI), 0.63-0.89). After <span class="hlt">adjustment</span> for potential confounders including exact age in days the IRR was 0.78 (95% CI, 0.66-0.93). The <span class="hlt">adjusted</span> IRR was 0.74 (95% CI, 0.60-0.92) in males and 0.84 (95% CI, 0.66-1.06) in females (P Interaction, 0.42). There was no association in the first month after MMR vaccination (<span class="hlt">adjusted</span> IRR, 0.97; 95% CI, 0.76-1.24) but the <span class="hlt">adjusted</span> IRR was 0.70 (95% CI, 0.58-0.85) from one month after MMR vaccination. MMR vaccination was associated with reduced rate of hospital <span class="hlt">contacts</span> related to laboratory-confirmed RSV infection. Further research on the association between MMR vaccination and other unrelated pathogens are warranted. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760022500','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760022500"><span>Thrust <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, W. J. (Inventor)</p> <p>1976-01-01</p> <p>A gas lubricated thrust <span class="hlt">bearing</span> is described which employs relatively rigid inwardly cantilevered spokes carrying a relatively resilient annular member or annulus. This annulus acts as a beam on which are mounted <span class="hlt">bearing</span> pads. The resilience of the beam mount causes the pads to accept the load and, with proper design, responds to a rotating thrust-transmitting collar by creating a gas film between the pads and the thrust collar. The <span class="hlt">bearing</span> may be arranged for load equalization thereby avoiding the necessity of gimbal mounts or the like for the <span class="hlt">bearing</span>. It may also be arranged to respond to rotation in one or both directions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24477675','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24477675"><span>Molecular phylogeny and SNP variation of polar <span class="hlt">bears</span> (Ursus maritimus), brown <span class="hlt">bears</span> (U. arctos), and black <span class="hlt">bears</span> (U. americanus) derived from genome sequences.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cronin, Matthew A; Rincon, Gonzalo; Meredith, Robert W; MacNeil, Michael D; Islas-Trejo, Alma; Cánovas, Angela; Medrano, Juan F</p> <p>2014-01-01</p> <p>We assessed the relationships of polar <span class="hlt">bears</span> (Ursus maritimus), brown <span class="hlt">bears</span> (U. arctos), and black <span class="hlt">bears</span> (U. americanus) with high throughput genomic sequencing data with an average coverage of 25× for each species. A total of 1.4 billion 100-bp paired-end reads were assembled using the polar <span class="hlt">bear</span> and annotated giant panda (Ailuropoda melanoleuca) genome sequences as references. We identified 13.8 million single nucleotide polymorphisms (SNP) in the 3 species aligned to the polar <span class="hlt">bear</span> genome. These data indicate that polar <span class="hlt">bears</span> and brown <span class="hlt">bears</span> share more SNP with each other than either does with black <span class="hlt">bears</span>. Concatenation and coalescence-based analysis of consensus sequences of approximately 1 million base pairs of ultraconserved elements in the nuclear genome resulted in a phylogeny with black <span class="hlt">bears</span> as the sister group to brown and polar <span class="hlt">bears</span>, and all brown <span class="hlt">bears</span> are in a separate clade from polar <span class="hlt">bears</span>. Genotypes for 162 SNP loci of 336 <span class="hlt">bears</span> from Alaska and Montana showed that the species are genetically differentiated and there is geographic population structure of brown and black <span class="hlt">bears</span> but not polar <span class="hlt">bears</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770040627&hterms=potential+action&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpotential%2Baction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770040627&hterms=potential+action&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpotential%2Baction"><span>The dual action gas thrust <span class="hlt">bearing</span> - A new high load <span class="hlt">bearing</span> concept</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Etsion, I.</p> <p>1976-01-01</p> <p>The principle of utilizing hydrodynamic effects in diverging films for improving load capacity in gas thrust <span class="hlt">bearings</span> is discussed. A new concept of dual action <span class="hlt">bearing</span> based on that principle is described and analyzed. The potential of the new <span class="hlt">bearing</span> is demonstrated both analytically for an infinitely long slider and by numerical solution for a flat sector shaped thrust <span class="hlt">bearing</span>. It is shown that the dual action <span class="hlt">bearing</span> can extend substantially the range of load carrying capacity in gas lubricated thrust <span class="hlt">bearings</span> and improve their efficiency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860057928&hterms=advanced+aerospace+materials&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dadvanced%2Baerospace%2Bmaterials','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860057928&hterms=advanced+aerospace+materials&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dadvanced%2Baerospace%2Bmaterials"><span>Advanced <span class="hlt">bearing</span> materials for cryogenic aerospace engine turbopump requirements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Friedman, G.; Bhat, B. N.</p> <p>1986-01-01</p> <p>The properties of eleven alloys were investigated to select an improved <span class="hlt">bearing</span> material for the High Pressure Oxygen Turbo Pump which delivers liquid oxygen to the Space Shuttle Main Engine. The alloys, selected through detailed literature analysis, X 405, MRC-2001, T440V, 14-4/6V, D-5, V-M Pyromet 350, Stellite 3, FerroTic CS-40, Tribaloy 800, WD-65, and CBS-600. The alloys were tested in hardness, corrosion resistance, wear resistance, fatigue resistance, and fracture toughness tests, and their performance was compared with the baseline 440C test alloy. As a result, five alloys were eliminated, leaving the remaining six (X 405, MRC-2001, T440V, 14-4/6V, D-5, and WD-65 to be evaluated in the next phase of NASA tests which will include fracture toughness, rolling <span class="hlt">contact</span> fatigue, wear resistance, and corrosion resistance. From these, three alloys will be selected, which will be made into ninety <span class="hlt">bearings</span> for subsequent testing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870011119','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870011119"><span>Flexibility effects on tooth <span class="hlt">contact</span> location in spiral bevel gear transmissions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Altidis, P. C.; Savage, M.</p> <p>1987-01-01</p> <p>An analytical method to predict the shift of the <span class="hlt">contact</span> ellipse between the meshing teeth in a spiral bevel gear set is presented in this report. The <span class="hlt">contact</span> ellipse shift of interest is the motion of the nominal tooth <span class="hlt">contact</span> location on each tooth from the ideal pitch point to the point of <span class="hlt">contact</span> between the two teeth considering the elastic motions of the gears and their supporting shafts. This is the shift of the pitch point from the ideal, unloaded position on each tooth to the nominal <span class="hlt">contact</span> location on the tooth when the gears are fully loaded. It is assumed that the major contributors of this motion are the elastic deflections of the gear shafts, the slopes of the shafts under load and the radial deflections of the four gear shaft <span class="hlt">bearings</span>. The motions of the two pitch point locations on the pinion and the gear tooth surfaces are calculated in a FORTRAN program which also calculates the size and orientation of the Hertzian <span class="hlt">contact</span> ellipse on the tooth faces. Based on the curvatures of the two spiral bevel gear teeth and the size of the <span class="hlt">contact</span> ellipse, the program also predicts the basic dynamic capacity of the tooth pair. A complete numerical example is given to illustrate the use of the program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22965816','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22965816"><span>An analytical method for computing atomic <span class="hlt">contact</span> areas in biomolecules.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mach, Paul; Koehl, Patrice</p> <p>2013-01-15</p> <p>We propose a new analytical method for detecting and computing <span class="hlt">contacts</span> between atoms in biomolecules. It is based on the alpha shape theory and proceeds in three steps. First, we compute the weighted Delaunay triangulation of the union of spheres representing the molecule. In the second step, the Delaunay complex is filtered to derive the dual complex. Finally, <span class="hlt">contacts</span> between spheres are collected. In this approach, two atoms i and j are defined to be in <span class="hlt">contact</span> if their centers are connected by an edge in the dual complex. The <span class="hlt">contact</span> areas between atom i and its neighbors are computed based on the caps formed by these neighbors on the surface of i; the total area of all these caps is partitioned according to their spherical Laguerre Voronoi diagram on the surface of i. This method is analytical and its implementation in a new program Ball<span class="hlt">Contact</span> is fast and robust. We have used Ball<span class="hlt">Contact</span> to study <span class="hlt">contacts</span> in a database of 1551 high resolution protein structures. We show that with this new definition of atomic <span class="hlt">contacts</span>, we generate realistic representations of the environments of atoms and residues within a protein. In particular, we establish the importance of nonpolar <span class="hlt">contact</span> areas that complement the information represented by the accessible surface areas. This new method <span class="hlt">bears</span> similarity to the tessellation methods used to quantify atomic volumes and <span class="hlt">contacts</span>, with the advantage that it does not require the presence of explicit solvent molecules if the surface of the protein is to be considered. © 2012 Wiley Periodicals, Inc. Copyright © 2012 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810009867','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810009867"><span>Introduction to ball <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamrock, B. J.; Dowson, D.</p> <p>1981-01-01</p> <p>The purpose of a ball <span class="hlt">bearing</span> is to provide a relative positioning and rotational freedom while transmitting a load between two structures, usually a shaft and a housing. For high rotational speeds (e.g., in gyroscope ball <span class="hlt">bearings</span>) the purpose can be expanded to include rotational freedom with practically no wear in the <span class="hlt">bearing</span>. This condition can be achieved by separating the <span class="hlt">bearing</span> parts with a coherent film of fluid known as an elastohydrodynamic film. This film can be maintained not only when the <span class="hlt">bearing</span> carries the load on a shaft, but also when the <span class="hlt">bearing</span> is preloaded to position the shaft to within micro- or nano-inch accuracy and stability. Background information on ball <span class="hlt">bearings</span> is provided, different types of ball <span class="hlt">bearings</span> and their geometry and kinematics are defined, <span class="hlt">bearing</span> materials, manufacturing processes, and separators are discussed. It is assumed, for the purposes of analysis, that the <span class="hlt">bearing</span> carries no load.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760011411','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760011411"><span>Endurance and failure characteristics of main-shaft jet engine <span class="hlt">bearings</span> at 3x10 to the 6th power DN</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bamberger, E. N.; Zaretsky, E. V.; Signer, H.</p> <p>1976-01-01</p> <p>Groups of thirty 120-mm bore angular <span class="hlt">contact</span> ball <span class="hlt">bearings</span> were endurance tested at a speed of 12,000 and 25,000 rpm and a thrust load of 66 721 N. The <span class="hlt">bearings</span> were manufactured from a single heat of VIM-VAR AISI M-50 steel. At 1.44X1 million and 3.0x1 million DN, 84 483 and 74 800 <span class="hlt">bearing</span> test hours were accumulated, respectively. Test results were compared with similar <span class="hlt">bearings</span> made from CVM AISI M-50 steel run under the same conditions. <span class="hlt">Bearing</span> lives at speeds of 3x1 million DN with the VIM-VAR AISI M-50 steel were nearly equivalent to those obtained at lower speeds. A combined processing and material life factor of 44 was found for VIM-VAR AISI M-50 steel. Continuous running after a spall has occurred at 3.0x1 million DN can result in a destructive fracture of the <span class="hlt">bearing</span> inner race.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20180003005','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20180003005"><span>The Design & Development of the Ocean Color Instrument Precision Superduplex Hybrid <span class="hlt">Bearing</span> Cartridge</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schepis, Joseph; Woodard, Timothy; Hakun, Claef; Bergandy, Konrad; Church, Joseph; Ward, Peter; Lee, Michael; Conti, Alfred; Guzek, Jeffrey</p> <p>2018-01-01</p> <p>A high precision, high-resolution Ocean Color Imaging (OCI) instrument is under development for the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission which requires a pair of medium speed mechanisms to scan the ocean surface continuously. The design of the rotating telescope (RT) mechanism operating at 360 RPM and the half-angle mirror (HAM) mechanism synchronized at 180 RPM was concern for maintaining pointing precision over the required life and continuous operations. An effort was undertaken with the manufacturer to design and analyze a special <span class="hlt">bearing</span> configuration to minimize axial and radial runout, minimize torque, and maintain nominal <span class="hlt">contact</span> stresses and stiffness over the operating temperature range and to maximize life. The <span class="hlt">bearing</span> design, development effort, analysis and testing will be discussed as will the technical challenges that this specific design imposed upon the mechanism engineers. <span class="hlt">Bearing</span> performance, runout as achieved and verified during encoder installation and operating torque will be described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22503076','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22503076"><span>Adolescent leisure dimensions, psychosocial <span class="hlt">adjustment</span>, and gender effects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bradley, Graham L; Inglis, Brad C</p> <p>2012-10-01</p> <p>Leisure provides the context for much of adolescent behaviour and development. While both theory and research point to the benefits of participation in leisure activities that are highly structured, the association between structured leisure and psychosocial <span class="hlt">adjustment</span> is not uniformly high. This paper presents a model of adolescent leisure comprising three dimensions: structure, effort, and social <span class="hlt">contact</span>. Adolescent <span class="hlt">adjustment</span> is hypothesized to increase with participation in activities characterized by each of these attributes. <span class="hlt">Adjustment</span> is also predicted to vary with gender, and with the interaction of gender and leisure participation. These propositions were tested in a questionnaire-based study of 433 Australian adolescents. Results revealed majority support for hypotheses pertaining to the positive effects of the leisure dimensions, and for gender differences in leisure participation and <span class="hlt">adjustment</span>. Evidence was also obtained of gender-differentiated effects of leisure on <span class="hlt">adjustment</span>, with social leisure predicting <span class="hlt">adjustment</span> more strongly in females than males. Copyright © 2012 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850018567','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850018567"><span><span class="hlt">Bearings</span> working group</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1985-01-01</p> <p>The service life of the Space Shuttle Main Engine (SSME) turbomachinery <span class="hlt">bearings</span> was a predominant factor in engine durability and maintenance problems. Recent data has indicated that <span class="hlt">bearing</span> life is about one order of magnitude lower than the goal of seven and one-half hours particularly those in the High Pressure Oxidizer Turbopump (HPOTP). <span class="hlt">Bearing</span> technology, primarily cryogenic turbomachinery <span class="hlt">bearing</span> technology, is expanded by exploring the life and performance effects of design changes; design concept changes; materials changes; manufacturing technique changes; and lubrication system changes. Each variation is assessed against the current <span class="hlt">bearing</span> design in full scale cryogenic tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11768451','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11768451"><span><span class="hlt">Bear</span> mauling: a descriptive review.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dieter, R A; Dieter, D L; Dieter, R A; Forbes, B</p> <p>2001-11-01</p> <p>Provide a descriptive review of <span class="hlt">bear</span> and human interactions in the United States. Descriptive review. The <span class="hlt">bear</span> population in the United States includes the grizzly <span class="hlt">bear</span>, the polar <span class="hlt">bear</span>, and the black <span class="hlt">bear</span>, including the glacier phase or blue <span class="hlt">bear</span>. As the human population grew and remote or wilderness access improved, the <span class="hlt">bear</span> population suffered both in total numbers and safe habitat. Conservation efforts, such as hunting restrictions and habitat enhancement, have helped to increase the total numbers of <span class="hlt">bears</span> on the North American continent. The chance of a human encountering a <span class="hlt">bear</span> increases as the remote <span class="hlt">bear</span> territory diminishes. <span class="hlt">Bear</span> incidents are widely publicized, though few serious incidents occur. The authors have direct knowledge of these <span class="hlt">bear</span>-human encounters in Alaska. Serious human injuries from black <span class="hlt">bears</span>, or maulings, including fatalities are uncommon. Grizzly <span class="hlt">bears</span> when trapped or stimulated may be very dangerous. The polar <span class="hlt">bear</span> sees everything that moves or has color, as potential food, and therefore, will attack seemingly unprovoked. The chance of a human encountering a <span class="hlt">bear</span> increases as the remote <span class="hlt">bear</span> territory diminishes. <span class="hlt">Bear</span> incidents are widely publicized, though few serious incidents occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4037503','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/4037503"><span><span class="hlt">Adjustable</span> extender for instrument module</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Sevec, J.B.; Stein, A.D.</p> <p>1975-11-01</p> <p>A blank extender module used to mount an instrument module in front of its console for repair or test purposes has been equipped with a rotatable mount and means for locking the mount at various angles of rotation for easy accessibility. The rotatable mount includes a horizontal conduit supported by <span class="hlt">bearings</span> within the blank module. The conduit is spring-biased in a retracted position within the blank module and in this position a small gear mounted on the conduit periphery is locked by a fixed pawl. The conduit and instrument mount can be pulled into an extended position with the gear clearing the pawl to permit rotation and <span class="hlt">adjustment</span> of the instrument.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9803E..4IL','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9803E..4IL"><span>Analysis of longitudinal seismic response of bridge with magneto-rheological elastomeric <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Rui; Li, Xi; Wu, Yueyuan; Chen, Shiwei; Wang, Xiaojie</p> <p>2016-04-01</p> <p>As the weakest part in the bridge system, traditional bridge <span class="hlt">bearing</span> is incapable of isolating the impact load such as earthquake. A magneto-rheological elastomeric <span class="hlt">bearing</span> (MRB) with <span class="hlt">adjustable</span> stiffness and damping parameters is designed, tested and modeled. The developed Bouc-Wen model is adopted to represent the constitutive relation and force-displacement behavior of an MRB. Then, the lead rubber <span class="hlt">bearing</span> (LRB), passive MRB and controllable MRB are modeled by finite element method (FEM). Furthermore, two typical seismic waves are adopted as inputs for the isolation system of bridge seismic response. The experiments are carried out to investigate the different response along the bridge with on-off controlled MRBs. The results show that the isolating performance of MRB is similar to that of traditional LRB, which ensures the fail-safe capability of bridge with MRBs under seismic excitation. In addition, the controllable bridge with MRBs demonstrated the advantage of isolating capacity and energy dissipation, because it restrains the acceleration peak of bridge beam by 33.3%, and the displacement of <span class="hlt">bearing</span> decrease by 34.1%. The shear force of the pier top is also alleviated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-07-26/pdf/2010-17807.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-07-26/pdf/2010-17807.pdf"><span>75 FR 43485 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-07-26</p> <p>.... The Administrator of the Foreign Agricultural Service (FAS) today accepted and began a review of a... cash benefits. FOR FURTHER INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Staff, FAS, USDA, by phone: (202) 720-0638, or (202) 690-0633; or by e-mail: [email protected]fas.usda.gov ; or...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/939500-anodic-behaviour-high-nitrogen-bearing-steel-pemfc-environments','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/939500-anodic-behaviour-high-nitrogen-bearing-steel-pemfc-environments"><span>Anodic Behaviour of High Nitrogen-<span class="hlt">Bearing</span> Steel in PEMFC Environments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wang, H.; Turner, J. A.</p> <p>2008-02-01</p> <p>High nitrogen-<span class="hlt">bearing</span> stainless steels, AISI Type 201 and AL219, were investigated in simulated polymer electrolyte membrane fuel cell (PEMFC) environments to assess the use of these materials in fuel cell bipolar plate applications. Both steels exhibit better corrosion behavior than 316L steel in the same environments. Type 201 steel shows similar but lower interfacial <span class="hlt">contact</span> resistance (ICR) than 316L, while AL219 steel shows higher ICR than 316L. X-ray photoelectron spectroscopy (XPS) analysis shows that the air-formed films on Type 201 and AL219 are composed of iron oxides, chromium oxide, and manganese oxide. Iron oxides dominate the composition of the air-formedmore » film, specially the outer layer. Chromium oxide dominates passive films. Surface film thicknesses were estimated. The results suggest that high nitrogen-<span class="hlt">bearing</span> stainless steels are promising materials for PEMFC bipolar plates.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4103522','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/4103522"><span>GAS <span class="hlt">BEARING</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Skarstrom, C.W.</p> <p>1960-09-01</p> <p>A gas lubricated <span class="hlt">bearing</span> for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a <span class="hlt">bearing</span> block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the <span class="hlt">bearing</span> block when the assembly is in operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JPhCS..97a2283D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JPhCS..97a2283D"><span>A double-superconducting axial <span class="hlt">bearing</span> system for an energy storage flywheel model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deng, Z.; Lin, Q.; Ma, G.; Zheng, J.; Zhang, Y.; Wang, S.; Wang, J.</p> <p>2008-02-01</p> <p>The bulk high temperature superconductors (HTSCs) with unique flux-pinning property have been applied to fabricate two superconducting axial <span class="hlt">bearings</span> for an energy storage flywheel model. The two superconducting axial <span class="hlt">bearings</span> are respectively fixed at two ends of the vertical rotational shaft, whose stator is composed of seven melt-textured YBa2Cu3O7-x (YBCO) bulks with diameter of 30 mm, height of 18 mm and rotor is made of three cylindrical axial-magnetized NdFeB permanent magnets (PM) by superposition with diameter of 63 mm, height of 27 mm. The experimental results show the total levitation and lateral force produced by the two superconducting <span class="hlt">bearings</span> are enough to levitate and stabilize the 2.4 kg rotational shaft. When the two YBCO stators were both field cooled to the liquid nitrogen temperature at respective axial distances above or below the PM rotor, the shaft could be automatically levitated between the two stators without any <span class="hlt">contact</span>. In the case of a driving motor, it can be stably rotated along the central axis besides the resonance frequency. This double-superconducting axial <span class="hlt">bearing</span> system can be used to demonstrate the flux-pinning property of bulk HTSC for stable levitation and suspension and the principle of superconducting flywheel energy storage system to visitors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090041695','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090041695"><span>Low-Friction, High-Stiffness Joint for Uniaxial Load Cell</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lewis, James L.; Le, Thang; Carroll, Monty B.</p> <p>2007-01-01</p> <p>A universal-joint assembly has been devised for transferring axial tension or compression to a load cell. To maximize measurement accuracy, the assembly is required to minimize any moments and non-axial forces on the load cell and to exhibit little or no hysteresis. The requirement to minimize hysteresis translates to a requirement to maximize axial stiffness (including minimizing backlash) and a simultaneous requirement to minimize friction. In practice, these are competing requirements, encountered repeatedly in efforts to design universal joints. Often, universal-joint designs represent compromises between these requirements. The improved universal-joint assembly contains two universal joints, each containing two <span class="hlt">adjustable</span> pairs of angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span>. One might be tempted to ask why one could not use simple ball-and-socket joints rather than something as complex as universal joints containing <span class="hlt">adjustable</span> pairs of angularcontact ball <span class="hlt">bearings</span>. The answer is that ball-and-socket joints do not offer sufficient latitude to trade stiffness versus friction: the inevitable result of an attempt to make such a trade in a ball-and-socket joint is either too much backlash or too much friction. The universal joints are located at opposite ends of an axial subassembly that contains the load cell. The axial subassembly includes an axial shaft, an axial housing, and a fifth <span class="hlt">adjustable</span> pair of angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> that allows rotation of the axial housing relative to the shaft. The preload on each pair of angular-<span class="hlt">contact</span> ball <span class="hlt">bearings</span> can be <span class="hlt">adjusted</span> to obtain the required stiffness with minimal friction, tailored for a specific application. The universal joint at each end affords two degrees of freedom, allowing only axial force to reach the load cell regardless of application of moments and non-axial forces. The rotational joint on the axial subassembly affords a fifth degree of freedom, preventing application of a torsion load to the load cell.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.jstor.org/stable/3061185','USGSPUBS'); return false;" href="http://www.jstor.org/stable/3061185"><span>Extirpations of grizzly <span class="hlt">bears</span> in the contiguous United States of America, 1850-2000</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mattson, David J.; Merrill, Troy</p> <p>2002-01-01</p> <p>We investigated factors associated with the distribution of grizzly <span class="hlt">bears</span> (Ursus arctos horribilis) in 1850 and their extirpation during 1850–1920 and 1920–1970 in the contiguous United States. We used autologistic regression to describe relations between grizzly <span class="hlt">bear</span> range in 1850, 1920, and 1970 and potential explanatory factors specified for a comprehensive grid of cells, each 900 km2 in size. We also related persistence, 1920–1970, to range size and shape. Grizzly <span class="hlt">bear</span> range in 1850 was positively related to occurrence in mountainous ecoregions and the ranges of oaks (Quercus spp.), piñon pines (Pinus edulis and P. monophylla), whitebark pine (P. albicaulis), and bison (Bos bison) and negatively related to occurrence in prairie and hot desert ecoregions. Relations with salmon (Oncorynchus spp.) range and human factors were complex. Persistence of grizzly <span class="hlt">bear</span> range, 1850–1970, was positively related to occurrence in the Rocky Mountains, whitebark pine range, and local size of grizzly <span class="hlt">bear</span> range at the beginning of each period, and negatively related to number of humans and the ranges of bison, salmon, and piñon pines. We speculate that foods affected persistence primarily by influencing the frequency of <span class="hlt">contact</span> between humans and <span class="hlt">bears</span>. With respect to current conservation, grizzly <span class="hlt">bears</span> survived from 1920 to 1970 most often where ranges at the beginning of this period were either larger than 20,000 km2 or larger than 7,000 km2 but with a ratio of perimeter to area of <2. Without reductions in human lethality after 1970, there would have been no chance that core grizzly <span class="hlt">bear</span> range would be as extensive as it is now. Although grizzly <span class="hlt">bear</span> range in the Yellowstone region is currently the most robust of any to potential future increases in human lethality, <span class="hlt">bears</span> in this region are threatened by the loss of whitebark pine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040082393','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040082393"><span>An Experimental Investigation Into the Temperature Profile of a Compliant Foil Air <span class="hlt">Bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Radil, Kevin; Zeszotek, Michelle</p> <p>2004-01-01</p> <p>A series of tests was performed to determine the internal temperature profile in a compliant bump-type foil journal air <span class="hlt">bearing</span> operating at room temperature under various speeds and load conditions. The temperature profile was collected by instrumenting a foil <span class="hlt">bearing</span> with nine, type K thermocouples arranged in the center and along the <span class="hlt">bearing</span> s edges in order to measure local temperatures and estimate thermal gradients in the axial and circumferential directions. To facilitate the measurement of maximum temperatures from viscous shearing in the air film, the thermocouples were tack welded to the backside of the bumps that were in direct <span class="hlt">contact</span> with the top foil. The mating journal was coated with a high temperature solid lubricant that, together with the <span class="hlt">bearing</span>, underwent high temperature start-stop cycles to produce a smooth, steady-state run-in surface. Tests were conducted at speeds from 20 to 50 krpm and loads ranging from 9 to 222 N. The results indicate that, over the conditions tested, both journal rotational speed and radial load are responsible for heat generation with speed playing a more significant role in the magnitude of the temperatures. The temperature distribution was nearly symmetric about the <span class="hlt">bearing</span> center at 20 and 30 krpm but became slightly skewed toward one side at 40 and 50 krpm. Surprisingly, the maximum temperatures did not occur at the <span class="hlt">bearing</span> edge where the minimum film thickness is expected but rather in the middle of the <span class="hlt">bearing</span> where analytical investigations have predicted the air film to be much thicker. Thermal gradients were common during testing and were strongest in the axial direction from the middle of the <span class="hlt">bearing</span> to its edges, reaching 3.78 8C/mm. The temperature profile indicated the circumferential thermal gradients were negligible.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JMiMi..28f5002C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JMiMi..28f5002C"><span>Development of an aerostatic <span class="hlt">bearing</span> system for roll-to-roll printed electronics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Shasha; Chen, Weihai; Liu, Jingmeng; Chen, Wenjie; Jin, Yan</p> <p>2018-06-01</p> <p>Roll-to-roll printed electronics is proved to be an effective way to fabricate electrical devices on various substrates. High precision overlay alignment plays a key role to create multi-layer electrical devices. Multiple rollers are adopted to support and transport the substrate web. In order to eliminate the negative effect of the machining error and assembling error of the roller, a whole roll-to-roll system including two aerostatic <span class="hlt">bearing</span> devices with arrayed restrictors is proposed in this paper. Different to the conventional roller, the aerostatic <span class="hlt">bearing</span> device can create a layer of air film between the web and the device to realize non-<span class="hlt">contact</span> support and transport. Based on simplified Navier–Stokes equations, the theoretical model of the air film is established. Moreover, the pressure distribution of the whole flow field and single restrictor in different positions are modeled by conducting numerical simulation with computational fluid dynamics (CFD) software FLUENT. The load capacity curves and stiffness curves are generated to provide guidance for optimizing the structure of the device. A prototype of the aerostatic <span class="hlt">bearing</span> system is set up and the experiment tests are carried out. For the proposed aerostatic <span class="hlt">bearing</span> roller with a diameter of 100 mm and length of 200 mm, the experimental results show the aerostatic <span class="hlt">bearing</span> method can achieve the position accuracy in a range of 1 μm in the vertical direction of the web, which is much better than that using existing methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-07-16/pdf/2010-17336.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-07-16/pdf/2010-17336.pdf"><span>75 FR 41430 - Trade <span class="hlt">Adjustment</span> Assistance for Farmers</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-07-16</p> <p>.... The Administrator of the Foreign Agricultural Service (FAS) has denied a petition (No. 2010014) for... FURTHER INFORMATION <span class="hlt">CONTACT</span>: Trade <span class="hlt">Adjustment</span> Assistance for Farmers Staff, FAS, USDA, by phone: (202) 720-0638, or (202) 690-0633; or by e-mail: [email protected]fas.usda.gov ; or visit the TAA for Farmers' Web...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7896649','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7896649"><span>Significance of touch for perceptions of parenting and psychological <span class="hlt">adjustment</span> among adolescents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pearce, C M; Martin, G; Wood, K</p> <p>1995-02-01</p> <p>This pilot study set out to investigate whether a relationship exists between differential quality and quantity of physical <span class="hlt">contact</span> experience and perceptions of parenting, psychological <span class="hlt">adjustment</span>, and suicidal behavior among adolescents. A self-report questionnaire assessed individuals' perceptions of how frequently they experienced pleasant (positive) and unpleasant (negative) touch from family and friends. Together with the Achenbach Youth Self-Report and the Parental Bonding Instrument, this questionnaire was administered to 142 male and 129 female students aged between 13 and 15 years (mean = 13.54, SD = 0.56) attending a randomly chosen metropolitan state high school and a coeducational private school. The major findings indicated that differential quality and quantity of physical <span class="hlt">contact</span> experience was related to perceptions of parenting, psychological <span class="hlt">adjustment</span>, and suicidal behavior, although a gender difference was observed. The findings suggest that physical <span class="hlt">contact</span> experiences may reflect different parenting styles and may be a vulnerability factor for a range of difficulties among adolescents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4409089','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4409089"><span>Genomic evidence of geographically widespread effect of gene flow from polar <span class="hlt">bears</span> into brown <span class="hlt">bears</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth</p> <p>2015-01-01</p> <p>Polar <span class="hlt">bears</span> are an arctic, marine adapted species that is closely related to brown <span class="hlt">bears</span>. Genome analyses have shown that polar <span class="hlt">bears</span> are distinct and genetically homogeneous in comparison to brown <span class="hlt">bears</span>. However, these analyses have also revealed a remarkable episode of polar <span class="hlt">bear</span> gene flow into the population of brown <span class="hlt">bears</span> that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar <span class="hlt">bear</span> and brown <span class="hlt">bear</span> genomes that includes brown <span class="hlt">bears</span> from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar <span class="hlt">bear</span> DNA found within the genomes of brown <span class="hlt">bears</span> living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown <span class="hlt">bear</span> genomes contain up to 8.8% polar <span class="hlt">bear</span> ancestry, polar <span class="hlt">bear</span> genomes appear to be devoid of brown <span class="hlt">bear</span> ancestry, suggesting the presence of a barrier to gene flow in that direction. PMID:25490862</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25490862','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25490862"><span>Genomic evidence of geographically widespread effect of gene flow from polar <span class="hlt">bears</span> into brown <span class="hlt">bears</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth</p> <p>2015-03-01</p> <p>Polar <span class="hlt">bears</span> are an arctic, marine adapted species that is closely related to brown <span class="hlt">bears</span>. Genome analyses have shown that polar <span class="hlt">bears</span> are distinct and genetically homogeneous in comparison to brown <span class="hlt">bears</span>. However, these analyses have also revealed a remarkable episode of polar <span class="hlt">bear</span> gene flow into the population of brown <span class="hlt">bears</span> that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar <span class="hlt">bear</span> and brown <span class="hlt">bear</span> genomes that includes brown <span class="hlt">bears</span> from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar <span class="hlt">bear</span> DNA found within the genomes of brown <span class="hlt">bears</span> living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown <span class="hlt">bear</span> genomes contain up to 8.8% polar <span class="hlt">bear</span> ancestry, polar <span class="hlt">bear</span> genomes appear to be devoid of brown <span class="hlt">bear</span> ancestry, suggesting the presence of a barrier to gene flow in that direction. © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040004324','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040004324"><span>Investigation of Pressurized Wave <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keith, Theo G., Jr.; Dimofte, Florin</p> <p>2003-01-01</p> <p>The wave <span class="hlt">bearing</span> has been pioneered and developed by Dr. Dimofte over the past several years. This <span class="hlt">bearing</span> will be the main focus of this research. It is believed that the wave <span class="hlt">bearing</span> offers a number of advantages over the foil <span class="hlt">bearing</span>, which is the <span class="hlt">bearing</span> that NASA is currently pursuing for turbomachinery applications. The wave <span class="hlt">bearing</span> is basically a journal <span class="hlt">bearing</span> whose film thickness varies around the circumference approximately sinusoidally, with usually 3 or 4 waves. Being a rigid geometry <span class="hlt">bearing</span>, it provides precise control of shaft centerlines. The wave profile also provides good load capacity and makes the <span class="hlt">bearing</span> very stable. Manufacturing techniques have been devised that should allow the production of wave <span class="hlt">bearings</span> almost as cheaply as conventional full-circular <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780000413&hterms=thrust+bearing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dthrust%2Bbearing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780000413&hterms=thrust+bearing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dthrust%2Bbearing"><span>Improved gas thrust <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, W. J.; Etsion, I.</p> <p>1979-01-01</p> <p>Two variations of gas-lubricated thrust <span class="hlt">bearings</span> extend substantially load-carrying range over existing gas <span class="hlt">bearings</span>. Dual-Action Gas Thrust <span class="hlt">Bearing</span>'s load-carrying capacity is more than ninety percent greater than that of single-action <span class="hlt">bearing</span> over range of compressibility numbers. Advantages of Cantilever-mounted Thrust <span class="hlt">Bearing</span> are greater tolerance to dirt ingestion, good initial lift-off characteristics, and operational capability over wide temperature range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1050766','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1050766"><span>Combined Effects of Gravity, Bending Moment, <span class="hlt">Bearing</span> Clearance, and Input Torque on Wind Turbine Planetary Gear Load Sharing: Preprint</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Guo, Y.; Keller, J.; LaCava, W.</p> <p>2012-09-01</p> <p>This computational work investigates planetary gear load sharing of three-mount suspension wind turbine gearboxes. A three dimensional multibody dynamic model is established, including gravity, bending moments, fluctuating mesh stiffness, nonlinear tooth <span class="hlt">contact</span>, and <span class="hlt">bearing</span> clearance. A flexible main shaft, planetary carrier, housing, and gear shafts are modeled using reduced degrees-of-freedom through modal compensation. This drivetrain model is validated against the experimental data of Gearbox Reliability Collaborative for gearbox internal loads. Planet load sharing is a combined effect of gravity, bending moment, <span class="hlt">bearing</span> clearance, and input torque. Influences of each of these parameters and their combined effects on the resulting planetmore » load sharing are investigated. Bending moments and gravity induce fundamental excitations in the rotating carrier frame, which can increase gearbox internal loads and disturb load sharing. Clearance in carrier <span class="hlt">bearings</span> reduces the <span class="hlt">bearing</span> load carrying capacity and thus the bending moment from the rotor can be transmitted into gear meshes. With <span class="hlt">bearing</span> clearance, the bending moment can cause tooth micropitting and can induce planet <span class="hlt">bearing</span> fatigue, leading to reduced gearbox life. Planet <span class="hlt">bearings</span> are susceptible to skidding at low input torque.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840016982&hterms=contact+area&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcontact%2Barea','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840016982&hterms=contact+area&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcontact%2Barea"><span>Lubricant Rheology in Concentrated <span class="hlt">Contacts</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jacobson, B. O.</p> <p>1984-01-01</p> <p>Lubricant behavior in highly stressed situtations shows that a Newtonian model for lubricant rheology is insufficient for explanation of traction behavior. The oil film build up is predicted by using a Newtonian lubricant model except at high slide to roll ratios and at very high loads, where the nonNewtonian behavior starts to be important already outside the Hertzian <span class="hlt">contact</span> area. Static and dynamic experiments are reported. In static experiments the pressure is applied to the lubricant more than a million times longer than in an EHD <span class="hlt">contact</span>. Depending on the pressure-temperature history of the experiment the lubricant will become a crystallized or amorphous solid at high pressures. In dynamic experiments, the oil is in an amorphous solid state. Depending on the viscosity, time scale, elasticity of the oil and the <span class="hlt">bearing</span> surfaces, the oil film pressure, shear strain rate and the type of lubricant, different properties of the oil are important for prediction of shear stresses in the oil. The different proposed models for the lubricant, which describe it to a Newtonian liquid, an elastic liquid, a plastic liquid and an elastic-plastic solid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990115440&hterms=curvature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcurvature','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990115440&hterms=curvature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcurvature"><span>Determination of Principal Curvatures and <span class="hlt">Contact</span> Ellipse for Profile Crowned Helical Gears</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Feng, P.-H.; Litvin, F. L.; Townsend, D. P.; Handschuh, R. F.</p> <p>1999-01-01</p> <p>Helical gears with localized <span class="hlt">bearing</span> <span class="hlt">contact</span> of tooth surfaces achieved by profile crowning of tooth surfaces are considered. Profile crowning is provided by application of two imaginary rack-cutters with mismatched surfaces. The goal is to determine the dimensions and orientation of the instantaneous <span class="hlt">contact</span> ellipse that requires the determination of principle curvatures of pinion-gear tooth surfaces. A simplified solution to this problem is proposed based on the approach development for correlation of principal curvatures and directions of generating and generated tooth surfaces. The obtained equations are applied for profile crowning where the normal profiles of the rack-cutters are either a circular arc or a straight line.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MSSP...85..445F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MSSP...85..445F"><span>Enhanced model of gear transmission dynamics for condition monitoring applications: Effects of torque, friction and <span class="hlt">bearing</span> clearance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fernandez-del-Rincon, A.; Garcia, P.; Diez-Ibarbia, A.; de-Juan, A.; Iglesias, M.; Viadero, F.</p> <p>2017-02-01</p> <p>Gear transmissions remain as one of the most complex mechanical systems from the point of view of noise and vibration behavior. Research on gear modeling leading to the obtaining of models capable of accurately reproduce the dynamic behavior of real gear transmissions has spread out the last decades. Most of these models, although useful for design stages, often include simplifications that impede their application for condition monitoring purposes. Trying to filling this gap, the model presented in this paper allows us to simulate gear transmission dynamics including most of these features usually neglected by the state of the art models. This work presents a model capable of considering simultaneously the internal excitations due to the variable meshing stiffness (including the coupling among successive tooth pairs in <span class="hlt">contact</span>, the non-linearity linked with the <span class="hlt">contacts</span> between surfaces and the dissipative effects), and those excitations consequence of the <span class="hlt">bearing</span> variable compliance (including clearances or pre-loads). The model can also simulate gear dynamics in a realistic torque dependent scenario. The proposed model combines a hybrid formulation for calculation of meshing forces with a non-linear variable compliance approach for <span class="hlt">bearings</span>. Meshing forces are obtained by means of a double approach which combines numerical and analytical aspects. The methodology used provides a detailed description of the meshing forces, allowing their calculation even when gear center distance is modified due to shaft and <span class="hlt">bearing</span> flexibilities, which are unavoidable in real transmissions. On the other hand, forces at <span class="hlt">bearing</span> level were obtained considering a variable number of supporting rolling elements, depending on the applied load and clearances. Both formulations have been developed and applied to the simulation of the vibration of a sample transmission, focusing the attention on the transmitted load, friction meshing forces and <span class="hlt">bearing</span> preloads.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030054466','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030054466"><span>Control Study for Five-axis Dynamic Spin Rig Using Magnetic <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Choi, Benjamin; Johnson, Dexter; Provenza, Andrew; Morrison, Carlos; Montague, Gerald</p> <p>2003-01-01</p> <p>The NASA Glenn Research Center (GRC) has developed a magnetic <span class="hlt">bearing</span> system for the Dynamic Spin Rig (DSR) with a fully suspended shaft that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic <span class="hlt">bearings</span> and a thrust magnetic <span class="hlt">bearing</span> and the associated control system were integrated into the DSR to provide magnetic excitation as well as non-<span class="hlt">contact</span> mag- netic suspension of a 15.88 kg (35 lb) vertical rotor with blades to induce turbomachinery blade vibration. For rotor levitation, a proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, more blade vibration amplitude, and energy savings for the system. The test results of a variety of controllers that were demonstrated up to 10.000 rpm are shown. Furthermore, rotor excitation operation and conceptual study of active blade vibration control are addressed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA025420','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA025420"><span><span class="hlt">Bearing</span> Restoration by Grinding</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1976-05-21</p> <p>lIng of <span class="hlt">bearings</span> prior to installation, installing a contaminated <span class="hlt">bearing</span>, manufacturing defects, ring growth in service, and corrosion. Nonmetallic...operation of rolling-elemsnt <span class="hlt">bearings</span> is growth of the <span class="hlt">bearing</span> race rings. As an example, the inner or outer races, can grow due to metallurgical...transformations or due to hoop stresses during operation This growth results in the <span class="hlt">bearing</span> being not reusable after removal from its application. For aircraft</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21446527','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21446527"><span>The evaluation of the micro-tracks and micro-dimples on the tribological characteristics of thrust ball <span class="hlt">bearings</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Amanov, Auezhan; Pyoun, Young-Shik; Cho, In-Shik; Lee, Chang-Soon; Park, In-Gyu</p> <p>2011-01-01</p> <p>One of the primary remedies for tribological problems is surface modification. The reduction of the friction between the ball and the raceway of <span class="hlt">bearings</span> is a very important goal of the development of <span class="hlt">bearing</span> technology. A low friction has a positive effect in terms of the extension of the fatigue life, avoidance of a temperature rise, and prevention of premature failure of <span class="hlt">bearings</span>. Therefore, this research sought to investigate the effects of micro-tracks and micro-dimples on the tribological characteristics at the <span class="hlt">contact</span> point between the ball and the raceway of thrust ball <span class="hlt">bearings</span> (TBBs). The ultrasonic nanocrystal surface modification (UNSM) technology was applied using different intervals (feed rates) to the TBB raceway surface to create micro-tracks and micro-dimples. The friction coefficient after UNSM at 50 microm intervals showed marked sensitivity and a significant reduction of 30%. In this study, the results showed that more micro-dimples yield a lower friction coefficient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JSV...319.1150R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JSV...319.1150R"><span>Nonlinear dynamic modeling of surface defects in rolling element <span class="hlt">bearing</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rafsanjani, Ahmad; Abbasion, Saeed; Farshidianfar, Anoushiravan; Moeenfard, Hamid</p> <p>2009-01-01</p> <p>In this paper an analytical model is proposed to study the nonlinear dynamic behavior of rolling element <span class="hlt">bearing</span> systems including surface defects. Various surface defects due to local imperfections on raceways and rolling elements are introduced to the proposed model. The <span class="hlt">contact</span> force of each rolling element described according to nonlinear Hertzian <span class="hlt">contact</span> deformation and the effect of internal radial clearance has been taken into account. Mathematical expressions were derived for inner race, outer race and rolling element local defects. To overcome the strong nonlinearity of the governing equations of motion, a modified Newmark time integration technique was used to solve the equations of motion numerically. The results were obtained in the form of time series, frequency responses and phase trajectories. The validity of the proposed model verified by comparison of frequency components of the system response with those obtained from experiments. The classical Floquet theory has been applied to the proposed model to investigate the linear stability of the defective <span class="hlt">bearing</span> rotor systems as the parameters of the system changes. The peak-to-peak frequency response of the system for each case is obtained and the basic routes to periodic, quasi-periodic and chaotic motions for different internal radial clearances are determined. The current study provides a powerful tool for design and health monitoring of machine systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70033919','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70033919"><span>Geology and geomorphology of <span class="hlt">Bear</span> Lake Valley and upper <span class="hlt">Bear</span> River, Utah and Idaho</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Reheis, M.C.; Laabs, B.J.C.; Kaufman, D.S.</p> <p>2009-01-01</p> <p><span class="hlt">Bear</span> Lake, on the Idaho-Utah border, lies in a fault-bounded valley through which the <span class="hlt">Bear</span> River flows en route to the Great Salt Lake. Surficial deposits in the <span class="hlt">Bear</span> Lake drainage basin provide a geologic context for interpretation of cores from <span class="hlt">Bear</span> Lake deposits. In addition to groundwater discharge, <span class="hlt">Bear</span> Lake received water and sediment from its own small drainage basin and sometimes from the <span class="hlt">Bear</span> River and its glaciated headwaters. The lake basin interacts with the river in complex ways that are modulated by climatically induced lake-level changes, by the distribution of active Quaternary faults, and by the migration of the river across its fluvial fan north of the present lake. The upper <span class="hlt">Bear</span> River flows northward for ???150 km from its headwaters in the northwestern Uinta Mountains, generally following the strike of regional Laramide and late Cenozoic structures. These structures likely also control the flow paths of groundwater that feeds <span class="hlt">Bear</span> Lake, and groundwater-fed streams are the largest source of water when the lake is isolated from the <span class="hlt">Bear</span> River. The present configuration of the <span class="hlt">Bear</span> River with respect to <span class="hlt">Bear</span> Lake Valley may not have been established until the late Pliocene. The absence of Uinta Range-derived quartzites in fluvial gravel on the crest of the <span class="hlt">Bear</span> Lake Plateau east of <span class="hlt">Bear</span> Lake suggests that the present headwaters were not part of the drainage basin in the late Tertiary. Newly mapped glacial deposits in the <span class="hlt">Bear</span> River Range west of <span class="hlt">Bear</span> Lake indicate several advances of valley glaciers that were probably coeval with glaciations in the Uinta Mountains. Much of the meltwater from these glaciers may have reached <span class="hlt">Bear</span> Lake via groundwater pathways through infiltration in the karst terrain of the <span class="hlt">Bear</span> River Range. At times during the Pleistocene, the <span class="hlt">Bear</span> River flowed into <span class="hlt">Bear</span> Lake and water level rose to the valley threshold at Nounan narrows. This threshold has been modified by aggradation, downcutting, and tectonics. Maximum lake</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPIE10448E..1BD','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPIE10448E..1BD"><span>Advancements in non-<span class="hlt">contact</span> metrology of asphere and diffractive optics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DeFisher, Scott</p> <p>2017-11-01</p> <p>Advancements in optical manufacturing technology allow optical designers to implement steep aspheric or high departure surfaces into their systems. Measuring these surfaces with profilometers or CMMs can be difficult due to large surface slopes or sharp steps in the surface. OptiPro has developed UltraSurf to qualify the form and figure of steep aspheric and diffractive optics. UltraSurf is a computer controlled, non-<span class="hlt">contact</span> coordinate measuring machine. It incorporates five air-<span class="hlt">bearing</span> axes, linear motors, high-resolution feedback, and a non-<span class="hlt">contact</span> probe. The measuring probe is scanned over the optical surface while maintaining perpendicularity and a constant focal offset. Multiple probe technologies are available on UltraSurf. Each probe has strengths and weaknesses relative to the material properties, surface finish, and figure error of an optical component. The measuring probes utilize absolute distance to resolve step heights and diffractive surface patterns. The non-<span class="hlt">contact</span> scanning method avoids common pitfalls with stylus <span class="hlt">contact</span> instruments. Advancements in measuring speed and precision has enabled fast and accurate non-<span class="hlt">contact</span> metrology of diffractive and steep aspheric surfaces. The benefits of data sampling with twodimensional profiles and three-dimensional topography maps will be presented. In addition, accuracy, repeatability, and machine qualification will be discussed with regards to aspheres and diffractive surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24387464','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24387464"><span>Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element <span class="hlt">bearing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Z; Hong, J; Zhang, J; Wang, M Y; Zhu, Y</p> <p>2013-12-01</p> <p>The rotational performance of high-precision rolling <span class="hlt">bearings</span> is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision <span class="hlt">bearings</span> of machine tools under working conditions was developed. In this instrument, a high-precision (error motion < 0.15 μm) and high-stiffness (2600 N axial loading capacity) aerostatic spindle was applied to spin the test <span class="hlt">bearing</span>. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-<span class="hlt">bearing</span> subjected to non-<span class="hlt">contact</span> and precise loaded axial forces. The measurement results on axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test <span class="hlt">bearing</span> which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the <span class="hlt">bearing</span> at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements' repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930018385','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930018385"><span>High efficiency magnetic <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Studer, Philip A.; Jayaraman, Chaitanya P.; Anand, Davinder K.; Kirk, James A.</p> <p>1993-01-01</p> <p>Research activities concerning high efficiency permanent magnet plus electromagnet (PM/EM) pancake magnetic <span class="hlt">bearings</span> at the University of Maryland are reported. A description of the construction and working of the magnetic <span class="hlt">bearing</span> is provided. Next, parameters needed to describe the <span class="hlt">bearing</span> are explained. Then, methods developed for the design and testing of magnetic <span class="hlt">bearings</span> are summarized. Finally, a new magnetic <span class="hlt">bearing</span> which allows active torque control in the off axes directions is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120012907','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120012907"><span>Static Indentation Load Capacity of the Superelastic 60NiTi for Rolling Element <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.</p> <p>2012-01-01</p> <p>The nickel-rich, binary nickel-titanium alloys, such as 60NiTi (60Ni-40Ti by wt%), are emerging as viable materials for use in mechanical components like rolling element <span class="hlt">bearings</span> and gears. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx.100 GPa). These properties result in the potential to endure extremely high indentation loads such as those encountered in <span class="hlt">bearings</span>, gears and other mechanical components. In such applications, quantifying the load that results in permanent deformation that can affect component performance and life is important. In this paper, the static load capacity is measured by conducting indentation experiments in which 12.7 mm diameter balls made from the ceramic Si3N4 are pressed into highly polished, hardened 60NiTi flat plates. Hertz stress calculations are used to estimate <span class="hlt">contact</span> stress. The results show that the 60NiTi surface can withstand an approximately 3400 kN load before significant denting (>0.6 microns deep) occurs. This load capacity is approximately twice that of high performance <span class="hlt">bearing</span> steels suggesting that the potential exists to make highly resilient <span class="hlt">bearings</span> and components from such materials.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790024381','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790024381"><span>Comparison of predicted and measured elastohydrodynamic film thickness in a 20-millimeter-bore ball <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coy, J. J.; Gorla, R. S. R.; Townsend, D. P.</p> <p>1979-01-01</p> <p>Elastohydrodynamic film thicknesses were measured for a 20-mm bore ball <span class="hlt">bearing</span> using the capacitance technique. The <span class="hlt">bearing</span> was thrust loaded to 90, 445, and 778 N (20, 100, and 175 lb). The corresponding maximum <span class="hlt">contact</span> stress on the inner race was 1.28, 2.09, and 2.45 GPa (185 000, 303,000, and 356, 000 psi). Test speeds ranged from 400 to 15,000 rpm. Measurements were taken with four different lubricants: (1) synthetic paraffinic; (2) synthetic paraffinic with additives; (3) synthetic type II aircraft oil; and (4) synthetic cycloaliphatic hydrocarbon traction fluid. The test <span class="hlt">bearing</span> was mist lubricated. Test temperatures were 27, 65, and 121 C (80, 150, and 250 F). The measured results for the various test parameters were compared to theoretical predictions from computer programs. Also the data were plotted on dimensionless coordinates and compared to several classical isothermal theories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120013868','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120013868"><span>Vibration Propagation of Gear Dynamics in a Gear-<span class="hlt">Bearing</span>-Housing System Using Mathematical Modeling and Finite Element Analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, Robert G.; Guo, Yi; Eritenel, Tugan; Ericson, Tristan M.</p> <p>2012-01-01</p> <p>Vibration and noise caused by gear dynamics at the meshing teeth propagate through power transmission components to the surrounding environment. This study is devoted to developing computational tools to investigate the vibro-acoustic propagation of gear dynamics through a gearbox using different <span class="hlt">bearings</span>. Detailed finite element/<span class="hlt">contact</span> mechanics and boundary element models of the gear/<span class="hlt">bearing</span>/housing system are established to compute the system vibration and noise propagation. Both vibration and acoustic models are validated by experiments including the vibration modal testing and sound field measurements. The effectiveness of each <span class="hlt">bearing</span> type to disrupt vibration propagation is speed-dependent. Housing plays an important role in noise radiation .It, however, has limited effects on gear dynamics. <span class="hlt">Bearings</span> are critical components in drivetrains. Accurate modeling of rolling element <span class="hlt">bearings</span> is essential to assess vibration and noise of drivetrain systems. This study also seeks to fully describe the vibro-acoustic propagation of gear dynamics through a power-transmission system using rolling element and fluid film wave <span class="hlt">bearings</span>. Fluid film wave <span class="hlt">bearings</span>, which have higher damping than rolling element <span class="hlt">bearings</span>, could offer an energy dissipation mechanism that reduces the gearbox noise. The effectiveness of each <span class="hlt">bearing</span> type to disrupt vibration propagation in explored using multi-body computational models. These models include gears, shafts, rolling element and fluid film wave <span class="hlt">bearings</span>, and the housing. Radiated noise is mapped from the gearbox surface to surrounding environment. The effectiveness of rolling element and fluid film wave <span class="hlt">bearings</span> in breaking the vibro-acoustic propagation path from the gear to the housing is investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18288549','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18288549"><span>Cumulative hip <span class="hlt">contact</span> stress predicts osteoarthritis in DDH.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mavcic, Blaz; Iglic, Ales; Kralj-Iglic, Veronika; Brand, Richard A; Vengust, Rok</p> <p>2008-04-01</p> <p>Hip stresses are generally believed to influence whether a hip develops osteoarthritis (OA); similarly, various osteotomies have been proposed to reduce <span class="hlt">contact</span> stresses and the risk of OA. We asked whether elevated hip <span class="hlt">contact</span> stress predicted osteoarthritis in initially asymptomatic human hips. We identified 58 nonoperatively treated nonsubluxated hips with developmental dysplasia (DDH) without symptoms at skeletal maturity; the control group included 48 adult hips without hip disease. The minimum followup was 20 years (mean, 29 years; range, 20-41 years). Peak <span class="hlt">contact</span> stress was computed with the HIPSTRESS method using anteroposterior pelvic radiographs at skeletal maturity. The cumulative <span class="hlt">contact</span> stress was determined by multiplying the peak <span class="hlt">contact</span> stress by age at followup. We compared WOMAC scores and radiographic indices of OA. Dysplastic hips had higher mean peak <span class="hlt">contact</span> and higher mean cumulative <span class="hlt">contact</span> stress than normal hips. Mean WOMAC scores and percentage of asymptomatic hips in the study group (mean age 51 years) were similar to those in the control group (mean age 68 years). After <span class="hlt">adjusting</span> for gender and age, the cumulative <span class="hlt">contact</span> stress, Wiberg center-edge angle, body mass index, but not the peak <span class="hlt">contact</span> stress, independently predicted the final WOMAC score in dysplastic hips but not in normal hips. Cumulative <span class="hlt">contact</span> stress predicted early hip OA better than the Wiberg center-edge angle. Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18002872','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18002872"><span>Improvement of hemolysis in a centrifugal blood pump with hydrodynamic <span class="hlt">bearings</span> and semi-open impeller.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kosaka, Ryo; Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Yada, Toru; Saito, Sakae; Hirai, Shusaku</p> <p>2007-01-01</p> <p>We have developed a centrifugal blood pump with hydrodynamic <span class="hlt">bearings</span> and semi-open impeller, and evaluated the levitation performance test and the hemolysis test. This pump is operated without any complicated control circuit and displacement-sensing module. The casing diameter is 74 mm and the height is 38 mm including flanges for volts. The weight is 251 g and the volume is 159 cm3. By changing the stator relative position against the rotor, the levitation characteristics of the impeller can be <span class="hlt">adjusted</span>. The diameter of impeller is 36 mm and the height is 25 mm. The impeller is levitated by the thrust <span class="hlt">bearing</span> of spiral groove type and a radial <span class="hlt">bearing</span> of herringbone type. The pump performance was evaluated through the levitation performance test and the hemolysis test. As a result, the normalized index of hemolysis (NIH) was reduced from 0.72 g/100 L to 0.024 g/100 L corresponding to the changes of the groove direction of the hydrodynamic <span class="hlt">bearing</span> and the expansion of the <span class="hlt">bearing</span> gap. During these studies, we confirmed that the hemolytic property was improved by balancing the fluid dynamic force and the magnetic force.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title10-vol4/pdf/CFR-2010-title10-vol4-sec903-11.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title10-vol4/pdf/CFR-2010-title10-vol4-sec903-11.pdf"><span>10 CFR 903.11 - Advance announcement of rate <span class="hlt">adjustment</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 10 Energy 4 2010-01-01 2010-01-01 false Advance announcement of rate <span class="hlt">adjustment</span>. 903.11 Section 903.11 Energy DEPARTMENT OF ENERGY POWER AND TRANSMISSION RATES Procedures for Public Participation in... announcement may be through direct <span class="hlt">contact</span> with customers, at public meetings, by press release, by newspaper...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSV...410...35B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSV...410...35B"><span>Radiation noise of the <span class="hlt">bearing</span> applied to the ceramic motorized spindle based on the sub-source decomposition method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bai, X. T.; Wu, Y. H.; Zhang, K.; Chen, C. Z.; Yan, H. P.</p> <p>2017-12-01</p> <p>This paper mainly focuses on the calculation and analysis on the radiation noise of the angular <span class="hlt">contact</span> ball <span class="hlt">bearing</span> applied to the ceramic motorized spindle. The dynamic model containing the main working conditions and structural parameters is established based on dynamic theory of rolling <span class="hlt">bearing</span>. The sub-source decomposition method is introduced in for the calculation of the radiation noise of the <span class="hlt">bearing</span>, and a comparative experiment is adopted to check the precision of the method. Then the comparison between the contribution of different components is carried out in frequency domain based on the sub-source decomposition method. The spectrum of radiation noise of different components under various rotation speeds are used as the basis of assessing the contribution of different eigenfrequencies on the radiation noise of the components, and the proportion of friction noise and impact noise is evaluated as well. The results of the research provide the theoretical basis for the calculation of <span class="hlt">bearing</span> noise, and offers reference to the impact of different components on the radiation noise of the <span class="hlt">bearing</span> under different rotation speed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910012219','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910012219"><span>Evaluation of <span class="hlt">bearing</span> configurations using the single <span class="hlt">bearing</span> tester in liquid nitrogen</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jett, T.; Hall, P.; Thom, R.</p> <p>1991-01-01</p> <p>Various <span class="hlt">bearing</span> configurations were tested using the Marshall Space Flight Center single <span class="hlt">bearing</span> tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore <span class="hlt">bearing</span>. The <span class="hlt">bearing</span> configurations that were tested included a Salox/M cage configuration, a silicon nitride ball configuration, an elongated cage configuration, and a Bray 601 grease configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70034122','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70034122"><span>Estimating black <span class="hlt">bear</span> density using DNA data from hair snares</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Gardner, B.; Royle, J. Andrew; Wegan, M.T.; Rainbolt, R.E.; Curtis, P.D.</p> <p>2010-01-01</p> <p>DNA-based mark-recapture has become a methodological cornerstone of research focused on <span class="hlt">bear</span> species. The objective of such studies is often to estimate population size; however, doing so is frequently complicated by movement of individual <span class="hlt">bears</span>. Movement affects the probability of detection and the assumption of closure of the population required in most models. To mitigate the bias caused by movement of individuals, population size and density estimates are often <span class="hlt">adjusted</span> using ad hoc methods, including buffering the minimum polygon of the trapping array. We used a hierarchical, spatial capturerecapture model that contains explicit components for the spatial-point process that governs the distribution of individuals and their exposure to (via movement), and detection by, traps. We modeled detection probability as a function of each individual's distance to the trap and an indicator variable for previous capture to account for possible behavioral responses. We applied our model to a 2006 hair-snare study of a black <span class="hlt">bear</span> (Ursus americanus) population in northern New York, USA. Based on the microsatellite marker analysis of collected hair samples, 47 individuals were identified. We estimated mean density at 0.20 <span class="hlt">bears</span>/km2. A positive estimate of the indicator variable suggests that <span class="hlt">bears</span> are attracted to baited sites; therefore, including a trap-dependence covariate is important when using bait to attract individuals. Bayesian analysis of the model was implemented in WinBUGS, and we provide the model specification. The model can be applied to any spatially organized trapping array (hair snares, camera traps, mist nests, etc.) to estimate density and can also account for heterogeneity and covariate information at the trap or individual level. ?? The Wildlife Society.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950026271','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950026271"><span>Dynamic modelling and response characteristics of a magnetic <span class="hlt">bearing</span> rotor system with auxiliary <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Free, April M.; Flowers, George T.; Trent, Victor S.</p> <p>1995-01-01</p> <p>Auxiliary <span class="hlt">bearings</span> are a critical feature of any magnetic <span class="hlt">bearing</span> system. They protect the soft iron core of the magnetic <span class="hlt">bearing</span> during an overload or failure. An auxiliary <span class="hlt">bearing</span> typically consists of a rolling element <span class="hlt">bearing</span> or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic <span class="hlt">bearings</span> including auxiliary <span class="hlt">bearings</span>. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic <span class="hlt">bearing</span> when one coil fails is studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22517859','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22517859"><span>Nuclear genomic sequences reveal that polar <span class="hlt">bears</span> are an old and distinct <span class="hlt">bear</span> lineage.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hailer, Frank; Kutschera, Verena E; Hallström, Björn M; Klassert, Denise; Fain, Steven R; Leonard, Jennifer A; Arnason, Ulfur; Janke, Axel</p> <p>2012-04-20</p> <p>Recent studies have shown that the polar <span class="hlt">bear</span> matriline (mitochondrial DNA) evolved from a brown <span class="hlt">bear</span> lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black <span class="hlt">bears</span>. Bayesian coalescent analyses place polar <span class="hlt">bears</span> outside the brown <span class="hlt">bear</span> clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar <span class="hlt">bear</span> evolution and confirms previous suggestions that polar <span class="hlt">bears</span> carry introgressed brown <span class="hlt">bear</span> mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730013700','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730013700"><span>Effects of vibration and shock on the performance of gas-<span class="hlt">bearing</span> space-power Brayton cycle turbomachinery. 2: Sinusoidal and random vibration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tessarzik, J. M.; Chiang, T.; Badgley, R. H.</p> <p>1973-01-01</p> <p>The vibration response of a gas-<span class="hlt">bearing</span> rotor-support system was analyzed experimentally documented for sinusoidal and random vibration environments. The NASA Brayton Rotating Unit (BRU), 36,000 rpm; 10 KWe turbogenerator; was subjected in the laboratory to sinusoidal and random vibrations to evaluate the capability of the BRU to (1) survive the vibration levels expected to be encountered during periods of nonoperation and (2) operate satisfactorily (that is, without detrimental <span class="hlt">bearing</span> surface <span class="hlt">contacts</span>) at the vibration levels expected during normal BRU operation. Response power spectral density was calculated for specified input random excitation, with particular emphasis upon the dynamic motions of the thrust <span class="hlt">bearing</span> runner and stator. A three-mass model with nonlinear representation of the engine isolator mounts was used to calculate axial rotor-<span class="hlt">bearing</span> shock response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900010081','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900010081"><span>A parametric heat transfer study for cryogenic ball <span class="hlt">bearings</span> in SSME HPOTP</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chyu, Mingking K.</p> <p>1989-01-01</p> <p>A numerical modeling is to examine the effects of coolant convective heat transfer coefficient and frictional heating on the local temperature characteristics of a ball element in Space Shuttle Main Engine (SSME) High Pressure Oxidizer Turbopump (HPOTP) <span class="hlt">bearing</span>. The present modeling uses a control-volume based, finite-difference method to solve the non-dimensionalized heat conduction equation in spherical coordinate system. The dimensionless temperature is found as a function of Biot number, heat flux ratio between the two race <span class="hlt">contacts</span>, and location in the ball. The current results show that, for a given cooling capability, the ball temperature generally increases almost linearly with the heat input from the race-<span class="hlt">contacts</span>. This increase is always very high at one of the two <span class="hlt">contacts</span>. An increase in heat transfer coefficient generally reduces the ball temperature and alleviates the temperature gradient, except for the regions very close to the race <span class="hlt">contacts</span>. For a 10-fold increase of heat transfer coefficient, temperature decrease is 35 percent for the average over entire ball, and 10 percent at the inner-race <span class="hlt">contact</span>. The corresponding change of temperature gradient displays opposing trends between the regions immediately adjacent to the <span class="hlt">contacts</span> and the remaining portion of the ball. The average temperature gradient in the vicinity of both <span class="hlt">contacts</span> increases approximately 70 to 100 percent. A higher temperature gradient produces excessive thermal stress locally which may be detrimental to the material integrity. This, however, is the only unfavorable issue for an increase of heat transfer coefficient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1725b0091T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1725b0091T"><span>Influence of superoleophobic layer on the lubrication performance of partially textured <span class="hlt">bearing</span> including cavitation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tauviqirrahman, M.; Bayuseno, A. P.; Muchammad, Jamari, J.</p> <p>2016-04-01</p> <p>Surfaces with high superoleophobicity have attracted important attention because of their potential applications in scientific and industrial field. Especially classical metal <span class="hlt">bearing</span> are faced with lubrication problem, because metal surface shows typically oleophilicity. The development of superolephobic metal surfaces which repel oil liquid droplet have significant applications in preventing the stiction. In addition, for classical <span class="hlt">bearing</span> with texturing, the cavitation occurence is often considered as the main cause of the deterioration of the lubrication performance and thus shorten the lifetime of the <span class="hlt">bearing</span>. In the present study, the exploration of the influence of adding the superoleophobic layer on the improvement of the performance of partially textured <span class="hlt">bearing</span> in preventing the cavitation was performed. Navier slip model was used to model the behavior of the superoleophobic layer. A formulation of the modified Reynolds equation with mass-conserving boundary conditions was derived and the pressure distribution was of particular interest. The equations of lubrication were discretized using a finite volume method and solved using a tri-diagonal-matrix-algortihm. In this calculation, it was shown that after introducing the superoleophobic layer at the leading edge of the <span class="hlt">contact</span>, the cavitation occurence can be prevented and thus the increased hydrodynamic pressure is found. However, the results showed that for deeper texture, the deterioration of the load support is noted. This findings may have useful implications to extend the life time of textured <span class="hlt">bearing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=contact&pg=5&id=EJ1011435','ERIC'); return false;" href="https://eric.ed.gov/?q=contact&pg=5&id=EJ1011435"><span>Electronic Communications Technologies and the Transition to College: Links to Parent-Child Attachment and <span class="hlt">Adjustment</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Sarigiani, Pamela A.; Trumbell, Jill M.; Camarena, Phame M.</p> <p>2013-01-01</p> <p>Electronic communications technologies (ECTs) help college students and parents remain in <span class="hlt">contact</span>. Because recent reports have emphasized a link between ECTs, helicopter parenting, and autonomy issues, this study focused on the significance of <span class="hlt">contact</span> patterns for attachment and student <span class="hlt">adjustment</span>. First-semester college students (199 female, 81…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820018803','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820018803"><span><span class="hlt">Bearings</span>: Technology and needs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, W. J.</p> <p>1982-01-01</p> <p>A brief status report on <span class="hlt">bearing</span> technology and present and near-term future problems that warrant research support is presented. For rolling element <span class="hlt">bearings</span> a material with improved fracture toughness, life data in the low Lambda region, a comprehensive failure theory verified by life data and incorporated into dynamic analyses, and an improved corrosion resistant alloy are perceived as important needs. For hydrodynamic <span class="hlt">bearings</span> better definition of cavitation boundaries and pressure distributions for squeeze film dampers, and geometry optimization for minimum power loss in turbulent film <span class="hlt">bearings</span> are needed. For gas film <span class="hlt">bearings</span>, foil <span class="hlt">bearing</span> geometries that form more nearly optimum film shapes for maximum load capacity, and more effective surface protective coatings for high temperature operation are needed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1411172-capillary-spreading-contact-line-over-sinking-sphere','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1411172-capillary-spreading-contact-line-over-sinking-sphere"><span>Capillary spreading of <span class="hlt">contact</span> line over a sinking sphere</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kim, Seong Jin; Fezzaa, Kamel; An, Jim</p> <p></p> <p>The <span class="hlt">contact</span> line dynamics over a sinking solid sphere are investigated in comparison with classical spreading theories. Experimentally, high-speed imaging systems with optical light or x-ray illumination are employed to accurately measure the spreading motion and dynamic <span class="hlt">contact</span> angle of the <span class="hlt">contact</span> line. Millimetric spheres are controlled to descend with a constant speed ranging from 7.3 × 10-5 to 0.79 m/s. We observed three different spreading stages over a sinking sphere, which depends on the <span class="hlt">contact</span> line velocity and <span class="hlt">contact</span> angle. These stages consistently showed the characteristics of capillarity-driven spreading as the <span class="hlt">contact</span> line spreads faster with a higher contactmore » angle. The <span class="hlt">contact</span> line velocity is observed to follow a classical capillary-viscous model at a high Ohnesorge number (> 0.02). For the cases with a relatively low Ohnesorge number (< 0.02), the <span class="hlt">contact</span> line velocity is significantly lower than the speed predicted by the capillary-viscous balance. This indicates the existence of an additional opposing force (inertia) for a decreasing Ohnesorge number. The capillary-inertial balance is only observed at the very beginning of the capillary rise, in which the maximum velocity is independent of the sphere’s sinking speed. Additionally, we observed the linear relation between the <span class="hlt">contact</span> line velocity and the sphere sinking speed during the second stage, which represents capillary <span class="hlt">adjustment</span> by dynamic <span class="hlt">contact</span> angle.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950016796','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950016796"><span>Dynamic modelling and response characteristics of a magnetic <span class="hlt">bearing</span> rotor system including auxiliary <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Free, April M.; Flowers, George T.; Trent, Victor S.</p> <p>1993-01-01</p> <p>Auxiliary <span class="hlt">bearings</span> are a critical feature of any magnetic <span class="hlt">bearing</span> system. They protect the soft iron core of the magnetic <span class="hlt">bearing</span> during an overload or failure. An auxiliary <span class="hlt">bearing</span> typically consists of a rolling element <span class="hlt">bearing</span> or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotor-dynamic model and assess the dynamic behavior of a magnetic <span class="hlt">bearing</span> rotor system which includes the effects of auxiliary <span class="hlt">bearings</span>. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic <span class="hlt">bearing</span>. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23125409','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23125409"><span>Genetic relationships of extant brown <span class="hlt">bears</span> (Ursus arctos) and polar <span class="hlt">bears</span> (Ursus maritimus).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cronin, Matthew A; MacNeil, Michael D</p> <p>2012-01-01</p> <p>Polar <span class="hlt">bears</span> (Ursus maritimus) and brown <span class="hlt">bears</span> (Ursus arctos) are closely related species for which extensive mitochondrial and nuclear phylogenetic comparisons have been made. We used previously published genotype data for 8 microsatellite DNA loci from 930 brown <span class="hlt">bears</span> in 19 populations and 473 polar <span class="hlt">bears</span> in 16 populations to compare the population genetic relationships of extant populations of the species. Genetic distances (Nei standard distance = 1.157), the proportion of private alleles (52% of alleles are not shared by the species), and Bayesian cluster analysis are consistent with morphological and life-history characteristics that distinguish polar <span class="hlt">bears</span> and brown <span class="hlt">bears</span> as different species with little or no gene flow among extant populations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830009609','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830009609"><span><span class="hlt">Bearing</span> fatigue investigation 3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nahm, A. H.; Bamberger, E. N.; Signer, H. R.</p> <p>1982-01-01</p> <p>The operating characteristics of large diameter rolling-element <span class="hlt">bearings</span> in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at <span class="hlt">bearing</span> speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, <span class="hlt">bearings</span> lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short <span class="hlt">bearing</span> lives were observed when this fluid was used with AISI M50 <span class="hlt">bearings</span> in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized <span class="hlt">bearing</span> to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale <span class="hlt">bearing</span> tests of a 120 mm bore ball <span class="hlt">bearing</span> at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28615939','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28615939"><span>Effect of carbon ion implantation on the tribology of metal-on-metal <span class="hlt">bearings</span> for artificial joints.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Koseki, Hironobu; Tomita, Masato; Yonekura, Akihiko; Higuchi, Takashi; Sunagawa, Sinya; Baba, Koumei; Osaki, Makoto</p> <p>2017-01-01</p> <p>Metal-on-metal (MoM) <span class="hlt">bearings</span> have become popular due to a major advantage over metal-on-polymer <span class="hlt">bearings</span> for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII) may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM <span class="hlt">bearings</span> in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo) alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding <span class="hlt">contact</span> tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated <span class="hlt">contact</span> pressure of 38.5 MPa (max: 57.8 MPa), a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated <span class="hlt">bearings</span> had lower friction coefficients, higher resistance to catastrophic damage, and prevented the adhesion of wear debris. The results of this study suggest that the CII surface stabilizes the wear status due to the low friction coefficient and low infiltration of partner materials, and these properties also prevent the adhesion of wear debris and inhibit excessive wear. Carbon is considered to be biologically inert; therefore, CII is anticipated to be applicable to the <span class="hlt">bearing</span> surfaces of MoM prostheses.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5459953','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5459953"><span>Effect of carbon ion implantation on the tribology of metal-on-metal <span class="hlt">bearings</span> for artificial joints</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Koseki, Hironobu; Tomita, Masato; Yonekura, Akihiko; Higuchi, Takashi; Sunagawa, Sinya; Baba, Koumei; Osaki, Makoto</p> <p>2017-01-01</p> <p>Metal-on-metal (MoM) <span class="hlt">bearings</span> have become popular due to a major advantage over metal-on-polymer <span class="hlt">bearings</span> for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII) may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM <span class="hlt">bearings</span> in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo) alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding <span class="hlt">contact</span> tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated <span class="hlt">contact</span> pressure of 38.5 MPa (max: 57.8 MPa), a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated <span class="hlt">bearings</span> had lower friction coefficients, higher resistance to catastrophic damage, and prevented the adhesion of wear debris. The results of this study suggest that the CII surface stabilizes the wear status due to the low friction coefficient and low infiltration of partner materials, and these properties also prevent the adhesion of wear debris and inhibit excessive wear. Carbon is considered to be biologically inert; therefore, CII is anticipated to be applicable to the <span class="hlt">bearing</span> surfaces of MoM prostheses. PMID:28615939</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1012916','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1012916"><span>Passive magnetic <span class="hlt">bearing</span> configurations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Post, Richard F [Walnut Creek, CA</p> <p>2011-01-25</p> <p>A journal <span class="hlt">bearing</span> provides vertical and radial stability to a rotor of a passive magnetic <span class="hlt">bearing</span> system when the rotor is not rotating and when it is rotating. In the passive magnetic <span class="hlt">bearing</span> system, the rotor has a vertical axis of rotation. Without the journal <span class="hlt">bearing</span>, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70127572','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70127572"><span>Cannibalism and predation on black <span class="hlt">bears</span> by grizzly <span class="hlt">bears</span> in the Yellowstone ecosystem, 1975-1990</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mattson, D.J.; Knight, R.R.; Blanchard, B.M.</p> <p>1992-01-01</p> <p>We documented one instance of an adult male grizzly <span class="hlt">bear</span> preying upon a black <span class="hlt">bear</span> and four instances where circumstantial evidence suggested that grizzly <span class="hlt">bears</span> (two cubs-of-the-year, one yearling female that was injured, and one adult male) had been preyed upon by conspecifics. We also examined feces of grizzly <span class="hlt">bears</span> for <span class="hlt">bear</span> remains. Remains of <span class="hlt">bears</span> tended to be more common in spring feces and did not differ in frequency between early and late years of the study. Our observations generally support existing hypotheses concerning cannibalism among <span class="hlt">bears</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22220229-nano-level-instrumentation-analyzing-dynamic-accuracy-rolling-element-bearing','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22220229-nano-level-instrumentation-analyzing-dynamic-accuracy-rolling-element-bearing"><span>Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element <span class="hlt">bearing</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Yang, Z.; Hong, J.; Zhang, J.</p> <p>2013-12-15</p> <p>The rotational performance of high-precision rolling <span class="hlt">bearings</span> is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision <span class="hlt">bearings</span> of machine tools under working conditions was developed. In this instrument, a high-precision (error motion < 0.15 μm) and high-stiffness (2600 N axial loading capacity) aerostatic spindle was applied to spin the test <span class="hlt">bearing</span>. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-<span class="hlt">bearing</span> subjected to non-<span class="hlt">contact</span> and precise loaded axial forces. The measurement results onmore » axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test <span class="hlt">bearing</span> which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the <span class="hlt">bearing</span> at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements’ repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.bearbiology.com/index.php?id=ursvol7','USGSPUBS'); return false;" href="http://www.bearbiology.com/index.php?id=ursvol7"><span>Arkansas black <span class="hlt">bear</span> hunter survey</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pharris, Larry D.; Clark, Joseph D.</p> <p>1987-01-01</p> <p>Questionnaires were mailed to black <span class="hlt">bear</span> (Ursus americanus) hunters in Arkansas following the 1980-84 <span class="hlt">bear</span> seasons to determine participation, hunter success, and number of <span class="hlt">bears</span> observed by hunters. Man-days of hunting to harvest a <span class="hlt">bear</span> ranged from 148 to 671 and hunter success ranged from 0.4% to 2.2%. With the exception of 1980, number of permits issued, man-days of <span class="hlt">bear</span> hunting, and <span class="hlt">bears</span> harvested appear affected by hunting permit cost. </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940031330','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940031330"><span>Aerospace applications of magnetic <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard</p> <p>1994-01-01</p> <p>Magnetic <span class="hlt">bearings</span> have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic <span class="hlt">bearings</span> have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic <span class="hlt">bearings</span> in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic <span class="hlt">bearings</span> programs at SatCon Technology Corporation. The magnetic <span class="hlt">bearing</span> programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic <span class="hlt">bearings</span> for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic <span class="hlt">bearing</span> system for an airborne telescope, and magnetic <span class="hlt">bearings</span> for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic <span class="hlt">bearing</span> technologies to the point where magnetic <span class="hlt">bearings</span> can be truly useful, reliable, and well tested components for the aerospace community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994mst..symp....3D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994mst..symp....3D"><span>Aerospace applications of magnetic <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard</p> <p>1994-05-01</p> <p>Magnetic <span class="hlt">bearings</span> have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic <span class="hlt">bearings</span> have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic <span class="hlt">bearings</span> in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic <span class="hlt">bearings</span> programs at SatCon Technology Corporation. The magnetic <span class="hlt">bearing</span> programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic <span class="hlt">bearings</span> for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic <span class="hlt">bearing</span> system for an airborne telescope, and magnetic <span class="hlt">bearings</span> for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic <span class="hlt">bearing</span> technologies to the point where magnetic <span class="hlt">bearings</span> can be truly useful, reliable, and well tested components for the aerospace community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS51C..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS51C..02P"><span>The Role of Natural Hydrate on the Strength of Sands: Load-<span class="hlt">bearing</span> or Cementing?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Priest, J. A.; Hayley, J. L.</p> <p>2017-12-01</p> <p>The strength of hydrate <span class="hlt">bearing</span> sands is a key parameter for simulating the long-term performance of hydrate reservoirs during gas production and assessing reservoir and wellbore stability. Historically this parameter has been determined from testing synthesized hydrate sand samples, which has led to significant differences in measured strength that appears to reflect different formation methods adopted. At present, formation methods can be grouped into either those that form hydrate at grain <span class="hlt">contacts</span> leading to a high strength `cemented' sand, or those where the hydrate forms a `load-<span class="hlt">bearing</span>' structure in which the hydrate grains reside in the pore space resulting in more subtle changes in strength. Recovered natural hydrate-<span class="hlt">bearing</span> cores typically exhibit this `load-<span class="hlt">bearing</span>' behavior, although these cores have generally undergone significant changes in temperature and pressure during recovery, which may have altered the structure of the hydrate and sediment. Recent drilling expeditions using pressure coring, such as NGHP2 offshore India, have enabled intact hydrate <span class="hlt">bearing</span> sediments to be recovered that have maintained hydrostatic stresses minimizing any changes in the hydrate structure within the core. Triaxial testing on these samples highlight enhanced strength even at zero effective stresses. This suggests that the hydrate forms a connected framework within the pore space apparently `cementing' the sand grains in place: we differentiate here between true cementation where hydrate is sintered onto the sand grains and typical observed behavior for cemented sands (cohesion, peak strength, post-peak strain softening). This inter-connected hydrate, and its ability to increase strength of the sands, appears to occur even at hydrate saturations as low as 30%, where typical `load-<span class="hlt">bearing</span>' hydrates just start to increase strength. The results from pressure cores suggest that hydrate formation techniques that lead to `load-<span class="hlt">bearing</span>' behavior may not capture the true</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080005559','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080005559"><span>Conceptual Design and Feasibility of Foil <span class="hlt">Bearings</span> for Rotorcraft Engines: Hot Core <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Howard, Samuel A.</p> <p>2007-01-01</p> <p>Recent developments in gas foil <span class="hlt">bearing</span> technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil <span class="hlt">bearings</span> into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas <span class="hlt">bearings</span> throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust <span class="hlt">bearing</span> load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element <span class="hlt">bearing</span> with a gas foil <span class="hlt">bearing</span> many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil <span class="hlt">bearings</span> in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil <span class="hlt">bearing</span> supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil <span class="hlt">bearing</span> core section. In addition, system level foil <span class="hlt">bearing</span> testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MSSP...72..105C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MSSP...72..105C"><span>Fault detection in rotor <span class="hlt">bearing</span> systems using time frequency techniques</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chandra, N. Harish; Sekhar, A. S.</p> <p>2016-05-01</p> <p>Faults such as misalignment, rotor cracks and rotor to stator rub can exist collectively in rotor <span class="hlt">bearing</span> systems. It is an important task for rotor dynamic personnel to monitor and detect faults in rotating machinery. In this paper, the rotor startup vibrations are utilized to solve the fault identification problem using time frequency techniques. Numerical simulations are performed through finite element analysis of the rotor <span class="hlt">bearing</span> system with individual and collective combinations of faults as mentioned above. Three signal processing tools namely Short Time Fourier Transform (STFT), Continuous Wavelet Transform (CWT) and Hilbert Huang Transform (HHT) are compared to evaluate their detection performance. The effect of addition of Signal to Noise ratio (SNR) on three time frequency techniques is presented. The comparative study is focused towards detecting the least possible level of the fault induced and the computational time consumed. The computation time consumed by HHT is very less when compared to CWT based diagnosis. However, for noisy data CWT is more preferred over HHT. To identify fault characteristics using wavelets a procedure to <span class="hlt">adjust</span> resolution of the mother wavelet is presented in detail. Experiments are conducted to obtain the run-up data of a rotor <span class="hlt">bearing</span> setup for diagnosis of shaft misalignment and rotor stator rubbing faults.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050180239','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050180239"><span>Gas Wave <span class="hlt">Bearings</span>: A Stable Alternative to Journal <span class="hlt">Bearings</span> for High-Speed Oil-Free Machines</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dimofte, Florin</p> <p>2005-01-01</p> <p>To run both smoothly and efficiently, high-speed machines need stable, low-friction <span class="hlt">bearings</span> to support their rotors. In addition, an oil-free <span class="hlt">bearing</span> system is a common requirement in today's designs. Therefore, self-acting gas film <span class="hlt">bearings</span> are becoming the <span class="hlt">bearing</span> of choice in high-performance rotating machinery, including that used in the machine tool industry. Although plain journal <span class="hlt">bearings</span> carry more load and have superior lift and land characteristics, they suffer from instability problems. Since 1992, a new type of fluid film <span class="hlt">bearing</span>, the wave <span class="hlt">bearing</span>, has been under development at the NASA Lewis Research Center in Cleveland, Ohio, by Dr. Florin Dimofte, a Senior Research Associate of the University of Toledo. One unique characteristic of the waved journal <span class="hlt">bearing</span> that gives it improved capabilities over conventional journal <span class="hlt">bearings</span> is the low-amplitude waves of its inner diameter surface. The radial clearance is on the order of one thousandth of the shaft radius, and the wave amplitude is nominally up to one-half the clearance. This <span class="hlt">bearing</span> concept offers a load capacity which is very close to that of a plain journal <span class="hlt">bearing</span>, but it runs more stably at nominal speeds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28667383','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28667383"><span>Comparison of fixed-<span class="hlt">bearing</span> and mobile-<span class="hlt">bearing</span> total knee arthroplasty after high tibial osteotomy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hernigou, Philippe; Huys, Maxime; Pariat, Jacques; Roubineau, François; Flouzat Lachaniette, Charles Henri; Dubory, Arnaud</p> <p>2018-02-01</p> <p>There is no information comparing the results of fixed-<span class="hlt">bearing</span> total knee replacement and mobile-<span class="hlt">bearing</span> total knee replacement in the same patients previously treated by high tibial osteotomy. The purpose was therefore to compare fixed-<span class="hlt">bearing</span> and mobile-<span class="hlt">bearing</span> total knee replacements in patients treated with previous high tibial osteotomy. We compared the results of 57 patients with osteoarthritis who had received a fixed-<span class="hlt">bearing</span> prosthesis after high tibial osteotomy with the results of 41 matched patients who had received a rotating platform after high tibial osteotomy. The match was made for length of follow-up period. The mean follow-up was 17 years (range, 15-20 years). The patients were assessed clinically and radiographically. The pre-operative knee scores had no statistically significant differences between the two groups. So was the case with the intra-operative releases, blood loss, thromboembolic complications and infection rates in either group. There was significant improvement in both groups of knees, and no significant difference was observed between the groups (i.e., fixed-<span class="hlt">bearing</span> and mobile-<span class="hlt">bearing</span> knees) for the mean Knee Society knee clinical score (95 and 92 points, respectively), or the Knee Society knee functional score (82 and 83 points, respectively) at the latest follow-up. However, the mean post-operative knee motion was higher for the fixed-<span class="hlt">bearing</span> group (117° versus 110°). In the fixed-<span class="hlt">bearing</span> group, one knee was revised because of periprosthetic fracture. In the rotating platform mobile-<span class="hlt">bearing</span> group, one knee was revised because of aseptic loosening of the tibial component. The Kaplan-Meier survivorship for revision at ten years of follow-up was 95.2% for the fixed <span class="hlt">bearing</span> prosthesis and 91.1% for the rotating platform mobile-<span class="hlt">bearing</span> prosthesis. Although we did manage to detect significant differences mainly in clinical and radiographic results between the two groups, we found no superiority or inferiority of the mobile-<span class="hlt">bearing</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5794087','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5794087"><span>The role of human outdoor recreation in shaping patterns of grizzly <span class="hlt">bear</span>-black <span class="hlt">bear</span> co-occurrence</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Steenweg, Robin; Shepherd, Brenda; Boyce, Mark S.</p> <p>2018-01-01</p> <p>Species’ distributions are influenced by a combination of landscape variables and biotic interactions with other species, including people. Grizzly <span class="hlt">bears</span> and black <span class="hlt">bears</span> are sympatric, competing omnivores that also share habitats with human recreationists. By adapting models for multi-species occupancy analysis, we analyzed trail camera data from 192 trail camera locations in and around Jasper National Park, Canada to estimate grizzly <span class="hlt">bear</span> and black <span class="hlt">bear</span> occurrence and intensity of trail use. We documented (a) occurrence of grizzly <span class="hlt">bears</span> and black <span class="hlt">bears</span> relative to habitat variables (b) occurrence and intensity of use relative to competing <span class="hlt">bear</span> species and motorised and non-motorised recreational activity, and (c) temporal overlap in activity patterns among the two <span class="hlt">bear</span> species and recreationists. Grizzly <span class="hlt">bears</span> were spatially separated from black <span class="hlt">bears</span>, selecting higher elevations and locations farther from roads. Both species co-occurred with motorised and non-motorised recreation, however, grizzly <span class="hlt">bears</span> reduced their intensity of use of sites with motorised recreation present. Black <span class="hlt">bears</span> showed higher temporal activity overlap with recreational activity than grizzly <span class="hlt">bears</span>, however differences in <span class="hlt">bear</span> daily activity patterns between sites with and without motorised and non-motorised recreation were not significant. Reduced intensity of use by grizzly <span class="hlt">bears</span> of sites where motorised recreation was present is a concern given off-road recreation is becoming increasingly popular in North America, and can negatively influence grizzly <span class="hlt">bear</span> recovery by reducing foraging opportunities near or on trails. Camera traps and multi-species occurrence models offer non-invasive methods for identifying how habitat use by animals changes relative to sympatric species, including humans. These conclusions emphasise the need for integrated land-use planning, access management, and grizzly <span class="hlt">bear</span> conservation efforts to consider the implications of continued access for motorised</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29389939','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29389939"><span>The role of human outdoor recreation in shaping patterns of grizzly <span class="hlt">bear</span>-black <span class="hlt">bear</span> co-occurrence.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ladle, Andrew; Steenweg, Robin; Shepherd, Brenda; Boyce, Mark S</p> <p>2018-01-01</p> <p>Species' distributions are influenced by a combination of landscape variables and biotic interactions with other species, including people. Grizzly <span class="hlt">bears</span> and black <span class="hlt">bears</span> are sympatric, competing omnivores that also share habitats with human recreationists. By adapting models for multi-species occupancy analysis, we analyzed trail camera data from 192 trail camera locations in and around Jasper National Park, Canada to estimate grizzly <span class="hlt">bear</span> and black <span class="hlt">bear</span> occurrence and intensity of trail use. We documented (a) occurrence of grizzly <span class="hlt">bears</span> and black <span class="hlt">bears</span> relative to habitat variables (b) occurrence and intensity of use relative to competing <span class="hlt">bear</span> species and motorised and non-motorised recreational activity, and (c) temporal overlap in activity patterns among the two <span class="hlt">bear</span> species and recreationists. Grizzly <span class="hlt">bears</span> were spatially separated from black <span class="hlt">bears</span>, selecting higher elevations and locations farther from roads. Both species co-occurred with motorised and non-motorised recreation, however, grizzly <span class="hlt">bears</span> reduced their intensity of use of sites with motorised recreation present. Black <span class="hlt">bears</span> showed higher temporal activity overlap with recreational activity than grizzly <span class="hlt">bears</span>, however differences in <span class="hlt">bear</span> daily activity patterns between sites with and without motorised and non-motorised recreation were not significant. Reduced intensity of use by grizzly <span class="hlt">bears</span> of sites where motorised recreation was present is a concern given off-road recreation is becoming increasingly popular in North America, and can negatively influence grizzly <span class="hlt">bear</span> recovery by reducing foraging opportunities near or on trails. Camera traps and multi-species occurrence models offer non-invasive methods for identifying how habitat use by animals changes relative to sympatric species, including humans. These conclusions emphasise the need for integrated land-use planning, access management, and grizzly <span class="hlt">bear</span> conservation efforts to consider the implications of continued access for motorised</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADB137279','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADB137279"><span>Improved Fatigue Life <span class="hlt">Bearing</span> Development</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1989-06-01</p> <p>lubricating conditions: (1) oil sump, with the bottom rolling element half submerged in oil; (2) oil vapor, with the <span class="hlt">bearings</span> bathed in oil vapor rising from...the life of <span class="hlt">bearings</span> operating at speeds up to 3 MDN. A 40-rnm thrust <span class="hlt">bearing</span> (Fafnir 2AAM 208WO MBR ) was selected for the preliminary tests. <span class="hlt">Bearings</span>...Bore Ball <span class="hlt">Bearing</span> Test Rig. 56 P- Aft. C9) 57 The test <span class="hlt">bearings</span> (Fafnir 2AAM 208W0 MBR ) were manufactured out of VIM-VAR M50. Initial testing was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030068294','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030068294"><span>Unbalance Response Prediction for Rotors on Ball <span class="hlt">Bearings</span> Using Speed and Load Dependent Nonlinear <span class="hlt">Bearing</span> Stiffness</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fleming, David P.; Poplawski, J. V.</p> <p>2003-01-01</p> <p>Rolling-element <span class="hlt">bearing</span> forces vary nonlinearly with <span class="hlt">bearing</span> deflection. Thus an accurate rotordynamic analysis requires that <span class="hlt">bearing</span> forces corresponding to the actual <span class="hlt">bearing</span> deflection be utilized. For this work <span class="hlt">bearing</span> forces were calculated by COBRA-AHS, a recently developed rolling-element <span class="hlt">bearing</span> analysis code. <span class="hlt">Bearing</span> stiffness was found to be a strong function of <span class="hlt">bearing</span> deflection, with higher deflection producing markedly higher stiffness. Curves fitted to the <span class="hlt">bearing</span> data for a range of speeds and loads were supplied to a flexible rotor unbalance response analysis. The rotordynamic analysis showed that vibration response varied nonlinearly with the amount of rotor imbalance. Moreover, the increase in stiffness as critical speeds were approached caused a large increase in rotor and <span class="hlt">bearing</span> vibration amplitude over part of the speed range compared to the case of constant <span class="hlt">bearing</span> stiffness. Regions of bistable operation were possible, in which the amplitude at a given speed was much larger during rotor acceleration than during deceleration. A moderate amount of damping will eliminate the bistable region, but this damping is not inherent in ball <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.polarbearsinternational.org/sites/default/files/ursus_16_-_bears_habituation_humans.pdf','USGSPUBS'); return false;" href="http://www.polarbearsinternational.org/sites/default/files/ursus_16_-_bears_habituation_humans.pdf"><span>Alaskan brown <span class="hlt">bears</span>, humans, and habituation</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Smith, Thomas; Herrero, Stephen; DeBruyn, Terry D.</p> <p>2005-01-01</p> <p>We present a new paradigm for understanding habituation and the role it plays in brown <span class="hlt">bear</span> (Ursus arctos) populations and interactions with humans in Alaska. We assert that 3 forms of habituation occur in Alaska: <span class="hlt">bear-to-bear</span>, <span class="hlt">bear</span>-to-human, and human-to-<span class="hlt">bear</span>. We present data that supports our theory that <span class="hlt">bear</span> density is an important factor influencing a bear’s overt reaction distance (ORD); that as <span class="hlt">bear</span> density increases, overt reaction distance decreases, as does the likelihood of bear– human interactions. We maintain that the effects of <span class="hlt">bear-to-bear</span> habituation are largely responsible for not only shaping <span class="hlt">bear</span> aggregations but also for creating the relatively safe environment for <span class="hlt">bear</span> viewing experienced at areas where there are high densities of brown <span class="hlt">bears</span>. By promoting a better understanding of the forces that shape <span class="hlt">bear</span> social interactions within populations and with humans that mingle with them, we can better manage human activities and minimize bear–human conflict.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950020865','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950020865"><span>Effects of <span class="hlt">bearing</span> cleaning and lube environment on <span class="hlt">bearing</span> performance</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ward, Peter C.</p> <p>1995-01-01</p> <p>Running torque data of SR6 ball <span class="hlt">bearings</span> are presented for different temperatures and speeds. The data are discussed in contrast to generally used torque prediction models and point out the need to obtain empirical data in critical applications. Also, the effects of changing <span class="hlt">bearing</span> washing techniques from old, universally used CFC-based systems to CFC-free aqueous/alkaline solutions are discussed. Data on wettability, torque and lubricant life using SR3 ball <span class="hlt">bearings</span> are presented. In general, performance is improved using the new aqueous washing techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28786800','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28786800"><span>Diabetes increases the risk of recent-transmission tuberculosis in household <span class="hlt">contacts</span> in São Paulo, Brazil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rajan, J V; Ferrazoli, L; Waldman, E A; Simonsen, V; Ferreira, P; Telles, M A; Riley, L W</p> <p>2017-08-01</p> <p>A cohort of household <span class="hlt">contacts</span> of tuberculosis (TB) index cases from four public health clinics in São Paulo, Brazil. To measure the association between diabetes mellitus (DM) among household <span class="hlt">contacts</span> and recent-transmission TB (RT TB). Index TB cases (n = 263) identified from 2001 to 2002 in São Paulo, whose household <span class="hlt">contacts</span> (n = 1383) were monitored for active TB until December 2010. From 2001 to 2010, there were 29 cases of RT TB among household <span class="hlt">contacts</span> (cumulative incidence 2.1%, 95%CI 1.4-2.9). DM in household <span class="hlt">contacts</span> was associated with RT TB (OR 3.96, 95%CI 1.33-11.79) even after <span class="hlt">adjustment</span> for human immunodeficiency virus (HIV) status, smoking and alcohol use (<span class="hlt">adjusted</span> OR [aOR] 3.21, 95%CI 1.01-10.19). HIV infection was also associated with RT TB (OR 6.40, 95%CI 1.40-29.40; aOR 4.81, 95%CI 0.96-24.18). Household <span class="hlt">contact</span> DM was not associated with non-RT TB (OR 1.27, 95%CI 0.30-5.40). The time to diagnosis of TB was shorter in household <span class="hlt">contacts</span> with and without DM (P = 0.035) and in household <span class="hlt">contacts</span> with and without HIV (P = 0.0002). Household <span class="hlt">contact</span> DM was associated with an increased risk of RT TB in a cohort in Brazil, lending support to the active screening of household <span class="hlt">contacts</span> with DM for TB in Brazil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/866469','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/866469"><span><span class="hlt">Bearing</span> construction for refrigeration compresssor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Middleton, Marc G.; Nelson, Richard T.</p> <p>1988-01-01</p> <p>A hermetic refrigeration compressor has a cylinder block and a crankshaft rotatable about a vertical axis to reciprocate a piston in a cylinder on the cylinder block. A separate <span class="hlt">bearing</span> housing is secured to the central portion of the cylinder block and extends vertically along the crankshaft, where it carries a pair of roller <span class="hlt">bearings</span> to journal the crankshaft. The crankshaft has a radially extending flange which is journaled by a thrust-type roller <span class="hlt">bearing</span> above the <span class="hlt">bearing</span> housing to absorb the vertical forces on the crankshaft so that all three of the roller <span class="hlt">bearings</span> are between the crankshaft and the <span class="hlt">bearing</span> housing to maintain and control the close tolerances required by such <span class="hlt">bearings</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25379661','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25379661"><span>Occlusal <span class="hlt">contact</span> of fixed implant prostheses using functional bite impression technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Suzuki, Yasunori; Shimpo, Hidemasa; Ohkubo, Chikahiro</p> <p>2015-02-01</p> <p>Functional bite impression (FBI) has been described as a definitive impression made under occlusal force after functional generated path (FGP) recording. This study compared the accuracy of occlusal <span class="hlt">contact</span> of implant-fixed prostheses using the FBI technique and the conventional impression technique. Twelve subjects, each missing a single premolar or molar, were selected for this study. The conditions of the occlusal <span class="hlt">contacts</span> were identified by the modified transillumination method. The occlusal <span class="hlt">contact</span> condition was determined by comparing the rate of change in the occlusal <span class="hlt">contact</span> area of the implant-fixed prostheses and both adjacent teeth before and after occlusal <span class="hlt">adjustment</span>. The rate of change in the occlusal <span class="hlt">contact</span> area using the FBI technique was 96%, and the rate using the conventional technique was 54%. The occlusal <span class="hlt">contact</span> of implant prostheses using the FBI technique revealed better accuracy than that of the conventional technique. Regarding the FBI technique, a precise and functional prosthesis could be produced by completing the maxillomandibular registration, impression, and FGP at the same time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MSSP..104..384K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MSSP..104..384K"><span>A semi-analytical <span class="hlt">bearing</span> model considering outer race flexibility for model based <span class="hlt">bearing</span> load monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kerst, Stijn; Shyrokau, Barys; Holweg, Edward</p> <p>2018-05-01</p> <p>This paper proposes a novel semi-analytical <span class="hlt">bearing</span> model addressing flexibility of the <span class="hlt">bearing</span> outer race structure. It furthermore presents the application of this model in a <span class="hlt">bearing</span> load condition monitoring approach. The <span class="hlt">bearing</span> model is developed as current computational low cost <span class="hlt">bearing</span> models fail to provide an accurate description of the more and more common flexible size and weight optimized <span class="hlt">bearing</span> designs due to their assumptions of rigidity. In the proposed <span class="hlt">bearing</span> model raceway flexibility is described by the use of static deformation shapes. The excitation of the deformation shapes is calculated based on the modelled rolling element loads and a Fourier series based compliance approximation. The resulting model is computational low cost and provides an accurate description of the rolling element loads for flexible outer raceway structures. The latter is validated by a simulation-based comparison study with a well-established <span class="hlt">bearing</span> simulation software tool. An experimental study finally shows the potential of the proposed model in a <span class="hlt">bearing</span> load monitoring approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4199141','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4199141"><span><span class="hlt">Contact</span> mechanics of modular metal-on-polyethylene total hip replacement under adverse edge loading conditions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hua, Xijin; Li, Junyan; Wang, Ling; Jin, Zhongmin; Wilcox, Ruth; Fisher, John</p> <p>2014-01-01</p> <p>Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the <span class="hlt">contact</span> mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP <span class="hlt">bearing</span>. Different cup inclination angles and head lateral microseparation were modelled and their effect on the <span class="hlt">contact</span> mechanics of the modular MoP hip replacement were examined. The results showed that lateral microseparation caused loading of the head on the rim of the cup, which produced substantial increases in the maximum von Mises stress in the polyethylene liner and the maximum <span class="hlt">contact</span> pressure on both the articulating surface and backside surface of the liner. Plastic deformation of the liner was observed under both standard conditions and microseparation conditions, however, the maximum equivalent plastic strain in the liner under microseparation conditions of 2000 µm was predicted to be approximately six times that under standard conditions. The study has indicated that correct positioning the components to avoid edge loading is likely to be important clinically even for hard-on-soft <span class="hlt">bearings</span> for THR. PMID:25218504</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16797994','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16797994"><span>Mobile vs. fixed <span class="hlt">bearing</span> unicondylar knee arthroplasty: A randomized study on short term clinical outcomes and knee kinematics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Ming G; Yao, Felix; Joss, Brendan; Ioppolo, James; Nivbrant, Bo; Wood, David</p> <p>2006-10-01</p> <p>The literature contains limited yet controversial information regarding whether a fixed or a mobile <span class="hlt">bearing</span> implant should be used in unicompartmental knee arthroplasty (UKA). This randomized study was to further document the performance and comparison of the two designs. Fifty-six knees in 48 patients (mean age of 72 years) undergoing medial UKA were randomized into a fixed <span class="hlt">bearing</span> (Miller/Galante) or a mobile <span class="hlt">bearing</span> (Oxford) UKA. The 2 year clinical outcomes (clinical scores), radiographic findings, and weight <span class="hlt">bearing</span> knee kinematics (assessed using RSA) were compared between the two groups. The mobile <span class="hlt">bearing</span> knees displayed a larger and an incrementally increased tibial internal rotation (4.3 degrees, 7.6 degrees, 9.5 degrees vs. 3.0 degrees, 3.0 degrees, 4.2 degrees respectively at 30 degrees, 60 degrees, 90 degrees of knee flexion) compared to the fixed ones. The medial femoral condyle in the mobile <span class="hlt">bearing</span> knees remained 2 mm from the initial position vs. a 4.2 mm anterior translation in the fixed <span class="hlt">bearing</span> knees during knee flexion. The <span class="hlt">contact</span> point in the mobile <span class="hlt">bearing</span> implant moved 2 mm posteriorly vs. a 6 mm anterior movement in the other group. The mobile <span class="hlt">bearing</span> knees had a lower incidence of radiolucency at the bone implant interface (8% vs. 37%, p < 0.05). The incidence of lateral compartment OA and progression of OA at patello-femoral joint were equal. No differences were found regarding Knee Society Scores, WOMAC, and SF-36 scores (p > 0.05). This study indicates that mobile <span class="hlt">bearing</span> knees had a better kinematics, a lower incidence of radiolucency but not yet a better knee function at 2 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..278a2162Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..278a2162Y"><span>Structure design and simulation research of active magnetic <span class="hlt">bearing</span> for helium centrifugal cold compressor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Y Zhang, S.; Pan, W.; Wei, C. B.; Wu, J. H.</p> <p>2017-12-01</p> <p>Helium centrifugal cold compressors are utilized to pump gaseous helium from saturated liquid helium tank to obtain super-fluid helium in cryogenic refrigeration system, which is now being developed at TIPC, CAS. Active magnetic <span class="hlt">bearing</span> (AMB) is replacing traditional oil-fed <span class="hlt">bearing</span> as the optimal supporting assembly for cold compressor because of its many advantages: free of <span class="hlt">contact</span>, high rotation speed, no lubrication and so on. In this paper, five degrees of freedom for AMB are developed for the helium centrifugal cold compressor application. The structure parameters of the axial and radial magnetic <span class="hlt">bearings</span> as well as hardware and software of the electronic control system is discussed in detail. Based on modal analysis and critical speeds calculation, a control strategy combining PID arithmetic with other phase compensators is proposed. Simulation results demonstrate that the control method not only stables AMB system but also guarantees good performance of closed-loop behaviour. The prior research work offers important base and experience for test and application of AMB experimental platform for system centrifugal cold compressor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930084939','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930084939"><span>Stress-life relation of the rolling-<span class="hlt">contact</span> fatigue spin rig</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Butler, Robert H; Carter, Thomas L</p> <p>1957-01-01</p> <p>The rolling-<span class="hlt">contact</span> fatigue spin rig was used to test groups of SAE 52100 9.16-inch-diameter balls lubricated with a mineral oil at 600,000-, 675,000-, and 750,000-psi maximum Hertz stress. Cylinders of AISI M-1 vacuum and commercial melts and MV-1 (AISI M-50) were used as race specimens. Stress-life exponents produced agree closely with values accepted in industry. The type of failure obtained in the spin rig was similar to the subsurface fatigue spells found in <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26743161','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26743161"><span>Effect of <span class="hlt">contact</span> lens use on Computer Vision Syndrome.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tauste, Ana; Ronda, Elena; Molina, María-José; Seguí, Mar</p> <p>2016-03-01</p> <p>To analyse the relationship between Computer Vision Syndrome (CVS) in computer workers and <span class="hlt">contact</span> lens use, according to lens materials. Cross-sectional study. The study included 426 civil-service office workers, of whom 22% were <span class="hlt">contact</span> lens wearers. Workers completed the Computer Vision Syndrome Questionnaire (CVS-Q) and provided information on their <span class="hlt">contact</span> lenses and exposure to video display terminals (VDT) at work. CVS was defined as a CVS-Q score of 6 or more. The covariates were age and sex. Logistic regression was used to calculate the association (crude and <span class="hlt">adjusted</span> for age and sex) between CVS and individual and work-related factors, and between CVS and <span class="hlt">contact</span> lens type. <span class="hlt">Contact</span> lens wearers are more likely to suffer CVS than non-lens wearers, with a prevalence of 65% vs 50%. Workers who wear <span class="hlt">contact</span> lenses and are exposed to the computer for more than 6 h day(-1) are more likely to suffer CVS than non-lens wearers working at the computer for the same amount of time (aOR = 4.85; 95% CI, 1.25-18.80; p = 0.02). Regular <span class="hlt">contact</span> lens use increases CVS after 6 h of computer work. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-10-09/pdf/2012-24673.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-10-09/pdf/2012-24673.pdf"><span>77 FR 61423 - Notice of <span class="hlt">Adjustment</span> of Statewide Per Capita Impact Indicator</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-10-09</p> <p>... DEPARTMENT OF HOMELAND SECURITY Federal Emergency Management Agency Notice of <span class="hlt">Adjustment</span> of Statewide Per Capita Impact Indicator AGENCY: Federal Emergency Management Agency, DHS. ACTION: Notice... FURTHER INFORMATION <span class="hlt">CONTACT</span>: William Roche, Recovery Directorate, Federal Emergency Management Agency, 500...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950015987','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950015987"><span>Wave Journal <span class="hlt">Bearing</span>. Part 1: Analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dimofte, Florin</p> <p>1995-01-01</p> <p>A wave journal <span class="hlt">bearing</span> concept features a waved inner <span class="hlt">bearing</span> diameter of the non-rotating <span class="hlt">bearing</span> side and it is an alternative to the plain journal <span class="hlt">bearing</span>. The wave journal <span class="hlt">bearing</span> has a significantly increased load capacity in comparison to the plain journal <span class="hlt">bearing</span> operating at the same eccentricity. It also offers greater stability than the plain circular <span class="hlt">bearing</span> under all operating conditions. The wave <span class="hlt">bearing</span>'s design is relatively simple and allows the shaft to rotate in either direction. Three wave <span class="hlt">bearings</span> are sensitive to the direction of an applied stationary side load. Increasing the number of waves reduces the wave <span class="hlt">bearing</span>'s sensitivity to the direction of the applied load relative to the wave. However, the range in which the <span class="hlt">bearing</span> performance can be varied decreases as the number of waves increases. Therefore, both the number and the amplitude of the waves must be properly selected to optimize the wave <span class="hlt">bearing</span> design for a specific application. It is concluded that the stiffness of an air journal <span class="hlt">bearing</span>, due to hydrodynamic effect, could be doubled and made to run stably by using a six or eight wave geometry with a wave amplitude approximately half of the <span class="hlt">bearing</span> radial clearance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/87173','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/87173"><span>Polar <span class="hlt">Bear</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Amstrup, S.D.; ,; Lentfer, J.W.</p> <p>1988-01-01</p> <p>Polar <span class="hlt">bears</span> are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar <span class="hlt">bear</span> populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17611851','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17611851"><span>Quantification of polyethylene degradation in mobile <span class="hlt">bearing</span> knees: a retrieval analysis of the Anterior-Posterior-Glide (APG) and Rotating Platform (RP) Low <span class="hlt">Contact</span> Stress (LCS) knee.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kop, Alan M; Swarts, Eric</p> <p>2007-06-01</p> <p>Routine qualitative observations of more than 850 polyethylene fixed and mobile <span class="hlt">bearings</span> at our institution have noted minimal wear of mobile <span class="hlt">bearings</span>. The APG mobile <span class="hlt">bearing</span> is the most recent design variant of the LCS knee, allows multi-directional movement at the tibiofemoral articulation, and is posterior cruciate sparing. Even though it is difficult to perform, quantitative wear measurement is important in determining the likely longevity of new arthroplasty devices, and is especially relevant because of increasing numbers of new mobile <span class="hlt">bearing</span> designs. We analyzed 10 retrieved APG and 7 retrieved RP tibial <span class="hlt">bearings</span> (De Puy) with a mean implantation period of 33 (9-70) months. We used coordinate-measuring techniques to quantitatively determine linear penetration, and optical and scanning electron microscopy to assess wear mechanisms qualitatively. The mean total volume loss (superior and inferior articulations) of the APG and RP designs was 85 mm((3))/year and 77 mm((3))/year, respectively. Burnishing was the predominant wear mechanism, and to a lesser extent scratching, abrasion and pitting. Multidirectional scratching and abrasion were noted on the APG inserts inferiorly, whereas there was circumferential scratching on the RP inserts. Our short-term results for the APG and RP mobile <span class="hlt">bearing</span> designs are similar and compare more than favorably with reported values for fixed-<span class="hlt">bearing</span> designs. However, increased backside wear due to multidirectional movement may predispose the APG design to greater wear in the long term.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090011264','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090011264"><span>Axial Halbach Magnetic <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.</p> <p>2008-01-01</p> <p>Axial Halbach magnetic <span class="hlt">bearings</span> have been investigated as part of an effort to develop increasingly reliable noncontact <span class="hlt">bearings</span> for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic <span class="hlt">bearings</span> are passive in the sense that unlike most other magnetic <span class="hlt">bearings</span> that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26037546','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26037546"><span>Higher forgotten joint score for fixed-<span class="hlt">bearing</span> than for mobile-<span class="hlt">bearing</span> total knee arthroplasty.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thienpont, E; Zorman, D</p> <p>2016-08-01</p> <p>To compare the postoperative subjective outcome for fixed- and mobile-<span class="hlt">bearing</span> total knee arthroplasty (TKA) by using the forgotten joint score (FJS-12), a new patient-reported outcome score of 12 questions evaluating the potential of a patient to forget about his operated joint. The hypothesis of this study was that a mobile-<span class="hlt">bearing</span> TKA would have a higher level of forgotten joint than a fixed-<span class="hlt">bearing</span> model of the same design. A retrospective cohort study was conducted in 100 patients who underwent TKA at least 1 year [mean (SD) 18 (5) months] before with either a fixed-<span class="hlt">bearing</span> (N = 50) or a mobile-<span class="hlt">bearing</span> (N = 50) TKA from the same implant family. Clinical outcome was evaluated with the knee society score and patient-reported outcome with the forgotten joint score. No difference was observed for demographics in between both study groups. The mean (SD) postoperative FJS-12 for the fixed-<span class="hlt">bearing</span> TKA was 71 (28) compared to a mean (SD) of 56.5 (30) for the mobile-<span class="hlt">bearing</span> TKA. The clinical relevance of the present retrospective study is that it shows for the first time a significant difference between fixed- and mobile-<span class="hlt">bearing</span> TKA by using a new patient-reported outcome score. The hypothesis that mobile-<span class="hlt">bearing</span> TKA would have a higher degree of forgotten joint than a fixed-<span class="hlt">bearing</span> TKA could not be confirmed. A level I prospective study should be set up to objectivise these findings. IV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.843a2030R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.843a2030R"><span>Experimental and numerical investigation of crack initiation and propagation in silicon nitride ceramic under rolling and cyclic <span class="hlt">contact</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raga, Rahul; Khader, Iyas; Zdeněk, Chlup; Kailer, Andreas</p> <p>2017-05-01</p> <p>The focus of the work was to investigate crack initiation and propagation mechanisms in silicon nitride undergoing non-conforming hybrid <span class="hlt">contact</span> under various tribological conditions. In order to understand the prevailing modes of damage in silicon nitride, two distinct model experiments were proposed, namely, rolling <span class="hlt">contact</span> and cyclic <span class="hlt">contact</span> experiments. The rolling <span class="hlt">contact</span> experiment was designed in order to mimic the <span class="hlt">contact</span> conditions appearing in hybrid <span class="hlt">bearings</span> at <span class="hlt">contact</span> pressures ranging from 3 to 6 GPa. On the other hand, cyclic <span class="hlt">contact</span> experiments with stresses ranging from 4 to 15 GPa under different media were carried out to study damage under localised stresses. In addition, the experimentally observed cracks were implemented in a finite element model to study the stress redistribution and correlate the generated stresses with the corresponding mechanisms. Crack propagation under rolling <span class="hlt">contact</span> was attributed to two different mechanisms, namely, fatigue induced fracture and lubricant driven crack propagation. The numerical simulations shed light on the tensile stress driven surface and subsurface crack propagation mechanisms. On the other hand, the cyclic <span class="hlt">contact</span> experiments showed delayed crack formation for lubricated cyclic <span class="hlt">contact</span>. Ceramographic cross-sectional analysis showed crack patterns similar to Hertzian crack propagation under cyclic <span class="hlt">contact</span> load.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4197462','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4197462"><span>Non-smooth Hopf-type bifurcations arising from impact–friction <span class="hlt">contact</span> events in rotating machinery</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mora, Karin; Budd, Chris; Glendinning, Paul; Keogh, Patrick</p> <p>2014-01-01</p> <p>We analyse the novel dynamics arising in a nonlinear rotor dynamic system by investigating the discontinuity-induced bifurcations corresponding to collisions with the rotor housing (touchdown <span class="hlt">bearing</span> surface interactions). The simplified Föppl/Jeffcott rotor with clearance and mass unbalance is modelled by a two degree of freedom impact–friction oscillator, as appropriate for a rigid rotor levitated by magnetic <span class="hlt">bearings</span>. Two types of motion observed in experiments are of interest in this paper: no <span class="hlt">contact</span> and repeated instantaneous <span class="hlt">contact</span>. We study how these are affected by damping and stiffness present in the system using analytical and numerical piecewise-smooth dynamical systems methods. By studying the impact map, we show that these types of motion arise at a novel non-smooth Hopf-type bifurcation from a boundary equilibrium bifurcation point for certain parameter values. A local analysis of this bifurcation point allows us a complete understanding of this behaviour in a general setting. The analysis identifies criteria for the existence of such smooth and non-smooth bifurcations, which is an essential step towards achieving reliable and robust controllers that can take compensating action. PMID:25383034</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770004461','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770004461"><span><span class="hlt">Bearing</span> restoration by grinding</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.</p> <p>1976-01-01</p> <p>A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element <span class="hlt">bearings</span> which are currently being discarded at aircraft engine and transmission overhaul. Three <span class="hlt">bearing</span> types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No <span class="hlt">bearing</span> failures occurred related to the restoration by grinding process. The risk and cost of a <span class="hlt">bearing</span> restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-10-28/pdf/2013-25333.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-10-28/pdf/2013-25333.pdf"><span>78 FR 64232 - Notice of <span class="hlt">Adjustment</span> of Statewide Per Capita Impact Indicator</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-10-28</p> <p>... DEPARTMENT OF HOMELAND SECURITY Federal Emergency Management Agency Notice of <span class="hlt">Adjustment</span> of Statewide Per Capita Impact Indicator AGENCY: Federal Emergency Management Agency, DHS. ACTION: Notice... INFORMATION <span class="hlt">CONTACT</span>: William Roche, Recovery Directorate, Federal Emergency Management Agency, 500 C Street SW...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870006034','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870006034"><span>Lubricant effects on <span class="hlt">bearing</span> life</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zaretsky, Erwin V.</p> <p>1986-01-01</p> <p>Lubricant considerations for rolling-element <span class="hlt">bearings</span> have within the last two decades taken on added importance in the design and operation of mechanical systems. The phenomenon which limits the useful life of <span class="hlt">bearings</span> is rolling-element or surface pitting fatigue. The elastohydrodynamic (EHD) film thickness which separates the ball or roller surface from those of the raceways of the <span class="hlt">bearing</span> directly affects <span class="hlt">bearing</span> life. Chemical additives added to the lubricant can also significantly affect <span class="hlt">bearings</span> life and reliability. The interaction of these physical and chemical effects is important to the design engineer and user of these systems. Design methods and lubricant selection for rolling-element <span class="hlt">bearings</span> are presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910000596&hterms=Startups&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DStartups','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910000596&hterms=Startups&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DStartups"><span>Flexure <span class="hlt">Bearing</span> Reduces Startup Friction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Clingman, W. Dean</p> <p>1991-01-01</p> <p>Design concept for ball <span class="hlt">bearing</span> incorporates small pieces of shim stock, wire spokes like those in bicycle wheels, or other flexing elements to reduce both stiction and friction slope. In flexure <span class="hlt">bearing</span>, flexing elements placed between outer race of ball <span class="hlt">bearing</span> and outer ring. Elements flex when ball <span class="hlt">bearings</span> encounter small frictional-torque "bumps" or even larger ones when <span class="hlt">bearing</span> balls encounter buildups of grease on inner or outer race. Flexure of elements reduce high friction slopes of "bumps", helping to keep torque between outer ring and inner race low and more nearly constant. Concept intended for <span class="hlt">bearings</span> in gimbals on laser and/or antenna mirrors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=283733','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=283733"><span>Climate Drives Polar <span class="hlt">Bear</span> Origins</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>In their provocative analysis of northern <span class="hlt">bears</span> (“Nuclear genomic sequences reveal that polar <span class="hlt">bears</span> are an old and distinct <span class="hlt">bear</span> lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar <span class="hlt">bears</span> originated during the middle Pleistocene, rather than during t...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=e+AND+sport&pg=5&id=EJ833758','ERIC'); return false;" href="https://eric.ed.gov/?q=e+AND+sport&pg=5&id=EJ833758"><span>Cultural Orientations, Daily Activities, and <span class="hlt">Adjustment</span> in Mexican American Youth</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>McHale, Susan M.; Updegraff, Kimberly A.; Kim, Ji-Yeon; Cansler, Emily</p> <p>2009-01-01</p> <p>The links between youth's daily activities and <span class="hlt">adjustment</span> and the role of cultural practices and values in these links were studied in 469 youth from 237 Mexican American families. In home interviews, data on mothers', fathers', and two adolescent-age siblings' cultural practices (language use, social <span class="hlt">contacts</span>) and values (for familism, for…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1943b0021B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1943b0021B"><span>Shock load analysis of rotor for rolling element <span class="hlt">bearings</span> and gas foil <span class="hlt">bearings</span>: A comparative study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhore, Skylab Paulas</p> <p>2018-04-01</p> <p>In this paper, a comparative study on the shock load analysis of rotor supported by rolling element <span class="hlt">bearings</span> and gas foil journal <span class="hlt">bearings</span> is presented. The rotor <span class="hlt">bearing</span> system is modeled using finite element method. Timoshenko beam element with 4 degree of freedom at each node is used. The shock load is represented by half sine pulse and applied to the base of the rotor <span class="hlt">bearing</span> system. The stiffness and damping coefficient of the <span class="hlt">bearings</span> are incorporated in the model. The generalized equation of motion of rotor <span class="hlt">bearing</span> system is solved by Newmark beta method and responses of rotor at <span class="hlt">bearing</span> position are predicted. It is observed that the responses are sensitive to the direction of applied excitation and its magnitude and pulse duration. The amplitude of responses of rotor supported on gas foil <span class="hlt">bearings</span> are significantly less than that of rolling element <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19152615','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19152615"><span>Effect of tibial tuberosity advancement on femorotibial <span class="hlt">contact</span> mechanics and stifle kinematics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Stanley E; Pozzi, Antonio; Banks, Scott A; Conrad, Bryan P; Lewis, Daniel D</p> <p>2009-01-01</p> <p>Objective- To evaluate the effects of tibial tuberosity advancement (TTA) on femorotibial <span class="hlt">contact</span> mechanics and 3-dimensional kinematics in cranial cruciate ligament (CrCL)-deficient stifles of dogs. Study Design- In vitro biomechanical study. Animals- Unpaired pelvic limbs from 8 dogs, weighing 28-35 kg. Methods- Digital pressure sensors placed subjacent to the menisci were used to measure femorotibial <span class="hlt">contact</span> force, <span class="hlt">contact</span> area, peak and mean <span class="hlt">contact</span> pressure, and peak pressure location with the limb under an axial load of 30% body weight and a stifle angle of 135 degrees . Three-dimensional static poses of the stifle were obtained using a Microscribe digitizing arm. Each specimen was tested under normal, CrCL-deficient, and TTA-treated conditions. Repeated measures analysis of variance with a Tukey post hoc test (P<.05) was used for statistical comparison. Results- Significant disturbances to all measured <span class="hlt">contact</span> mechanic parameters were evident after CrCL transection, which corresponded to marked cranial tibial subluxation and internal tibial rotation in the CrCL-deficient stifle. No significant differences in any <span class="hlt">contact</span> mechanic and kinematic parameters were detected between normal and TTA-treated stifles. Conclusion- TTA eliminates craniocaudal stifle instability during simulated weight-<span class="hlt">bearing</span> and concurrently restores femorotibial <span class="hlt">contact</span> mechanics to normal. Clinical Relevance- TTA may mitigate the progression of stifle osteoarthritis in dogs afflicted with CrCL insufficiency by eliminating cranial tibial thrust while preserving the normal orientation of the proximal tibial articulating surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12485633','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12485633"><span>The development of <span class="hlt">contact</span> force construction in the dynamic-<span class="hlt">contact</span> task of cycling [corrected].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brown, Nicholas A T; Jensen, Jody L</p> <p>2003-01-01</p> <p>Purposeful movement requires that an individual produce appropriate joint torques to accelerate segments, and when environmental <span class="hlt">contact</span> is involved, to develop task-appropriate <span class="hlt">contact</span> forces. Developmental research has been confined largely to the mastery of unconstrained movement skills (pointing, kicking). The purpose of this study was to study the developmental progression that characterizes the interaction of muscular and non-muscular forces in tasks constrained by <span class="hlt">contact</span> with the environment. Seven younger children (YC, 6-8 years), 7 older children (OC, 9-11 years) and 7 adults (AD) pedaled an ergometer (80 rpm) at an anthropometrically scaled cycling power. Resultant forces measured at the pedal's surface were decomposed into muscle, inertia and gravity components. Muscle pedal forces were further examined in terms of the underlying lower extremity joint torques and kinematic weights that constitute the muscular component of the pedal force. Data showed children applied muscle forces to the pedal in a significantly different manner compared to adults, and that this was due to the children's lower segmental mass and inertia. The children <span class="hlt">adjusted</span> the contribution of the proximal joint muscle torques to compensate for reduced contributions to the resultant pedal force by gravitational and inertial components. These data show that smaller segmental mass and inertia limit younger children's ability to construct the dynamic-<span class="hlt">contact</span> task of cycling in an adult-like form. On the basis of these results, however, the children's response was not "immature". Rather, the results show a task-appropriate adaptation to lower segmental mass and inertia. Copyright 2002 Elsevier Science Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ASPC..409..157A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ASPC..409..157A"><span>Arcturus and the <span class="hlt">Bears</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Antonello, E.</p> <p>2009-08-01</p> <p>Arcturus is the brightest star in Bootes. The ancient Greek name Arktouros means <span class="hlt">Bear</span> Guard. The star, however, is not close to Ursa Maior (Big She-<span class="hlt">Bear</span>) and Ursa Minor (Little She-<span class="hlt">Bear</span>), as the name would suggest. This curious discrepancy could be explained by the star proper motion, assuming the name <span class="hlt">Bear</span> Guard is a remote cultural heritage. The proper motion analysis could allow us to get an insight also into an ancient myth regarding Ursa Maior. Though we cannot explain scientifically such a myth, some interesting suggestions can be obtained about its possible origin, in the context of the present knowledge of the importance of the cult of the <span class="hlt">bear</span> both during the Palaeolithic times and for several primitive populations of modern times, as shown by the ethnological studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730016789','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730016789"><span>Fluorine lubricated <span class="hlt">bearing</span> technology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mallaire, F. R.</p> <p>1973-01-01</p> <p>An experimental program was conducted to evaluate and select materials for ball <span class="hlt">bearings</span> intended for use in liquid fluorine and/or FLOX. The ability of three different ball-separator materials, each containing nickel, to form and transfer a nickel fluoride film to provide effective lubrication at the required areas of a ball <span class="hlt">bearing</span> operating in liquid fluorine was evaluated. In addition, solid lubrication of a ball <span class="hlt">bearing</span> operating in liquid fluorine by either a fused fluoride coating applied to all surfaces of the ball separator or by a fluoride impregnation of porous sintered material ball separators was evaluated. Less <span class="hlt">bearing</span> wear occurred when tests were conducted in the less reactive FLOX. <span class="hlt">Bearings</span> fabricated from any of the materials tested would have relatively short wear lives and would require frequent replacement in a reusable engine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040172619&hterms=ferris&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dferris','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040172619&hterms=ferris&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dferris"><span>Running in the real world: <span class="hlt">adjusting</span> leg stiffness for different surfaces</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ferris, D. P.; Louie, M.; Farley, C. T.</p> <p>1998-01-01</p> <p>A running animal coordinates the actions of many muscles, tendons, and ligaments in its leg so that the overall leg behaves like a single mechanical spring during ground <span class="hlt">contact</span>. Experimental observations have revealed that an animal's leg stiffness is independent of both speed and gravity level, suggesting that it is dictated by inherent musculoskeletal properties. However, if leg stiffness was invariant, the biomechanics of running (e.g. peak ground reaction force and ground <span class="hlt">contact</span> time) would change when an animal encountered different surfaces in the natural world. We found that human runners <span class="hlt">adjust</span> their leg stiffness to accommodate changes in surface stiffness, allowing them to maintain similar running mechanics on different surfaces. These results provide important insight into mechanics and control of animal locomotion and suggest that incorporating an <span class="hlt">adjustable</span> leg stiffness in the design of hopping and running robots is important if they are to match the agility and speed of animals on varied terrain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MeScT..29e5102J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MeScT..29e5102J"><span>Visual method for detecting critical damage in railway <span class="hlt">contact</span> strips</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Judek, S.; Skibicki, J.</p> <p>2018-05-01</p> <p>Ensuring an uninterrupted supply of power in the electric traction is vital for the safety of this important transport system. For this purpose, monitoring and diagnostics of the technical condition of the vehicle’s power supply elements are becoming increasingly common. This paper presents a new visual method for detecting <span class="hlt">contact</span> strip damage, based on measurement and analysis of the movement of the overhead <span class="hlt">contact</span> line (OCL) wire. A measurement system configuration with a 2D camera was proposed. The experimental method has shown that <span class="hlt">contact</span> strips damage can be detected by transverse displacement signal analysis. It has been proven that the velocity signal numerically established on that basis has a comparable level in the case of identical damage, regardless of its location on the surface of the <span class="hlt">contact</span> strip. The proposed method belongs to the group of <span class="hlt">contact</span>-less measurements, so it does not require interference with the structure of the catenary network nor the mounting of sensors in its vicinity. Measurement of displacements of the <span class="hlt">contact</span> wire in 2D space makes it possible to combine the functions of existing diagnostic stands assessing the correctness of the mean <span class="hlt">contact</span> force control <span class="hlt">adjustment</span> of the current collector with the elements of the <span class="hlt">contact</span> strip diagnostics, which involves detecting their damage which may result in overhead <span class="hlt">contact</span> line rupture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950017197','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950017197"><span>Finite-Difference Solutions of the Alternate Turbopump Development High-Pressure Oxidizer Turbopump Pump-End Ball-<span class="hlt">Bearing</span> Cavity Flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benjamin, Theodore G.; Garcia, Roberto; Mcconnaughey, Paul K.; Wang, Ten-See; Vu, Bruce T.; Dakhoul, Youssef</p> <p>1993-01-01</p> <p>These analyses were undertaken to aid in the understanding of flow phenomena in the Alternate Turbopump Development (ATD) High-pressure Oxidizer Turbopump (HPOTP) Pump-end ball <span class="hlt">bearing</span> (PEBB) cavities and their roles in turbopump vibration initiation and <span class="hlt">bearing</span> distress. This effort was being performed to provide timely support to the program in a decision as to whether or not the program should be continued. In the first case, it was determined that a change in <span class="hlt">bearing</span> through flow had no significant effect on axial preload. This was a follow-on to a previous study which had resulted in a redesign of the <span class="hlt">bearing</span> exit cavity which virtually eliminated <span class="hlt">bearing</span> axial loading. In the second case, a three-dimensional analysis of the inner-race-guided cage configuration was performed so as to determine the pressure distribution on the outer race when the shaft is 0.0002 inches off-center. The results indicate that there is virtually no circumferential pressure difference caused by the offset to contribute to <span class="hlt">bearing</span> tilt. In the third case, axisymmetric analyses were performed on an outer-race guided cage configuration to determine the magnitude of tangential flow entering the <span class="hlt">bearing</span>. The removed-shoulder case was analyzed as was the static diverter case. A third analysis where the preload spring was shielded by a sheet of metal for the baseline case was also performed. It was determined that the swirl entering the <span class="hlt">bearing</span> was acceptable and the project decided to use the outer-race-guided cage configuration. In the fourth case, more <span class="hlt">bearing</span> configurations were analyzed. These analyses included thermal modeling so as to determine the added benefit of injecting colder fluid directly onto the <span class="hlt">bearing</span> inner-race <span class="hlt">contact</span> area. The results of these analyses contributed to a programmatic decision to include coolant injection in the design.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28053282','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28053282"><span>Psychological <span class="hlt">Adjustment</span> of Siblings of Children with Autism Spectrum Disorder in Hong Kong.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chan, J Yn; Lai, K Yc</p> <p>2016-12-01</p> <p>Findings about the psychological <span class="hlt">adjustment</span> of siblings of children with autism spectrum disorder have been inconsistent in western literature and little is known among non-western societies. This study explored the psychological <span class="hlt">adjustment</span> of siblings of children with autism spectrum disorder in Hong Kong. A total of 116 families with siblings of children with autism spectrum disorders co-morbid with learning disability were included in the study. Parents completed questionnaires about sibling emotional and behavioural <span class="hlt">adjustment</span>, and their own mental well-being, quality of life, and family functioning. Siblings completed a questionnaire on their relationship with the autistic proband. Parent ratings did not reveal any significant negative impact on the emotional and behavioural <span class="hlt">adjustment</span> of the typically developing siblings of children with autism spectrum disorder, but there were concerns about their peer relationships and weak prosocial behaviours. When cut-off scores were used to screen for risk of mental health problems, a quarter of the siblings warranted further assessment. Parents' quality of life and family functioning were significant predictors of sibling <span class="hlt">adjustment</span>. In managing children with autism spectrum disorder, it is necessary to <span class="hlt">bear</span> in mind the <span class="hlt">adjustment</span> of their siblings, especially their peer relationships and prosocial behaviour. Adopting a holistic approach to address the psychosocial needs of the parents can facilitate sibling <span class="hlt">adjustment</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24220205','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24220205"><span>Comparison of plantar pressures and <span class="hlt">contact</span> area between normal and cavus foot.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fernández-Seguín, Lourdes M; Diaz Mancha, Juan Antonio; Sánchez Rodríguez, Raquel; Escamilla Martínez, Elena; Gómez Martín, Beatriz; Ramos Ortega, Javier</p> <p>2014-02-01</p> <p>In pes cavus, the medial longitudinal arch elevation reduces the <span class="hlt">contact</span> surface area and consequently increases the corresponding plantar pressure measurements. This poor distribution of loads may produce associated pathology and pain in this or other areas of the body. Normal reference values need to be established in order to determine which patterns are prone to pathology. To compare the plantar pressures and weight-<span class="hlt">bearing</span> surface in a population with pes cavus to a population with neutral feet. The sample comprised 68 adults, 34 with pes cavus and 34 with neutral feet. The Footscan USB Gait Clinical System(®) was used as a platform to measure the total <span class="hlt">contact</span> area and plantar pressure under the forefoot, midfoot, hindfoot, each metatarsal head, and the overall metatarsal area. A statistical analysis of the data was performed using Student's t-test for independent samples. The pes cavus subjects showed a significant reduction in their weight-<span class="hlt">bearing</span> area [neutral feet: 165.04 ( ± 20.68) cm(2); pes cavus: 118.26 ( ± 30.31) cm(2); p < 0.001] and significantly increased pressures under all zones of the forefoot except the fifth metatarsal [metatarsal pressure: in neutral feet 503,797 ( ± 9.32) kPa; in pes cavus 656.12 ( ± 22.39) kPa; p < 0.001]. Compared to neutral feet, pes cavus feet show a reduction in total <span class="hlt">contact</span> surface and the load under the first toe. A significant increase is present in the load under the metatarsal areas, but the relative distribution of this load is similar in both groups. Copyright © 2013 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3827271','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3827271"><span>Ancestral Polymorphisms and Sex-Biased Migration Shaped the Demographic History of Brown <span class="hlt">Bears</span> and Polar <span class="hlt">Bears</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nakagome, Shigeki; Mano, Shuhei; Hasegawa, Masami</p> <p>2013-01-01</p> <p>Recent studies have reported discordant gene trees in the evolution of brown <span class="hlt">bears</span> and polar <span class="hlt">bears</span>. Genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal DNA (aDNA) and matrilineal mitochondrial DNA (mtDNA). Based on multi-locus genomic sequences from aDNA and mtDNA, we inferred the population demography of brown and polar <span class="hlt">bears</span> and found that brown <span class="hlt">bears</span> have 6 times (aDNA) or more than 14 times (mtDNA) larger population sizes than polar <span class="hlt">bears</span> and that polar <span class="hlt">bear</span> lineage is derived from within brown <span class="hlt">bear</span> diversity. In brown <span class="hlt">bears</span>, the effective population size ratio of mtDNA to aDNA was at least 0.62, which deviated from the expected value of 0.25, suggesting matriarchal population due to female philopatry and male-biased migration. These results emphasize that ancestral polymorphisms and sex-biased migration may have contributed to conflicting branching patterns in brown and polar <span class="hlt">bears</span> across aDNA genes and mtDNA. PMID:24236053</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24236053','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24236053"><span>Ancestral polymorphisms and sex-biased migration shaped the demographic history of brown <span class="hlt">bears</span> and polar <span class="hlt">bears</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakagome, Shigeki; Mano, Shuhei; Hasegawa, Masami</p> <p>2013-01-01</p> <p>Recent studies have reported discordant gene trees in the evolution of brown <span class="hlt">bears</span> and polar <span class="hlt">bears</span>. Genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal DNA (aDNA) and matrilineal mitochondrial DNA (mtDNA). Based on multi-locus genomic sequences from aDNA and mtDNA, we inferred the population demography of brown and polar <span class="hlt">bears</span> and found that brown <span class="hlt">bears</span> have 6 times (aDNA) or more than 14 times (mtDNA) larger population sizes than polar <span class="hlt">bears</span> and that polar <span class="hlt">bear</span> lineage is derived from within brown <span class="hlt">bear</span> diversity. In brown <span class="hlt">bears</span>, the effective population size ratio of mtDNA to aDNA was at least 0.62, which deviated from the expected value of 0.25, suggesting matriarchal population due to female philopatry and male-biased migration. These results emphasize that ancestral polymorphisms and sex-biased migration may have contributed to conflicting branching patterns in brown and polar <span class="hlt">bears</span> across aDNA genes and mtDNA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/864847','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/864847"><span><span class="hlt">Bearing</span> for liquid metal pump</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Dickinson, Robert J.; Wasko, John; Pennell, William E.</p> <p>1984-01-01</p> <p>A liquid metal pump <span class="hlt">bearing</span> support comprises a series of tangentially oriented spokes that connect the <span class="hlt">bearing</span> cylinder to the pump internals structure. The spokes may be arranged in a plurality of planes extending from the <span class="hlt">bearing</span> cylinder to the pump internals with the spokes in one plane being arranged alternately with those in the next plane. The <span class="hlt">bearing</span> support structure provides the pump with sufficient lateral support for the <span class="hlt">bearing</span> structure together with the capability of accommodating differential thermal expansion without adversely affecting pump performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26552964','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26552964"><span>Fast-moving dislocations trigger flash weakening in carbonate-<span class="hlt">bearing</span> faults during earthquakes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Spagnuolo, Elena; Plümper, Oliver; Violay, Marie; Cavallo, Andrea; Di Toro, Giulio</p> <p>2015-11-10</p> <p>Rupture fronts can cause fault displacement, reaching speeds up to several ms(-1) within a few milliseconds, at any distance away from the earthquake nucleation area. In the case of silicate-<span class="hlt">bearing</span> rocks the abrupt slip acceleration results in melting at asperity <span class="hlt">contacts</span> causing a large reduction in fault frictional strength (i.e., flash weakening). Flash weakening is also observed in experiments performed in carbonate-<span class="hlt">bearing</span> rocks but evidence for melting is lacking. To unravel the micro-physical mechanisms associated with flash weakening in carbonates, experiments were conducted on pre-cut Carrara marble cylinders using a rotary shear apparatus at conditions relevant to earthquakes propagation. In the first 5 mm of slip the shear stress was reduced up to 30% and CO2 was released. Focused ion beam, scanning and transmission electron microscopy investigations of the slipping zones reveal the presence of calcite nanograins and amorphous carbon. We interpret the CO2 release, the formation of nanograins and amorphous carbon to be the result of a shock-like stress release associated with the migration of fast-moving dislocations. Amorphous carbon, given its low friction coefficient, is responsible for flash weakening and promotes the propagation of the seismic rupture in carbonate-<span class="hlt">bearing</span> fault patches.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4639853','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4639853"><span>Fast-moving dislocations trigger flash weakening in carbonate-<span class="hlt">bearing</span> faults during earthquakes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Spagnuolo, Elena; Plümper, Oliver; Violay, Marie; Cavallo, Andrea; Di Toro, Giulio</p> <p>2015-01-01</p> <p>Rupture fronts can cause fault displacement, reaching speeds up to several ms−1 within a few milliseconds, at any distance away from the earthquake nucleation area. In the case of silicate-<span class="hlt">bearing</span> rocks the abrupt slip acceleration results in melting at asperity <span class="hlt">contacts</span> causing a large reduction in fault frictional strength (i.e., flash weakening). Flash weakening is also observed in experiments performed in carbonate-<span class="hlt">bearing</span> rocks but evidence for melting is lacking. To unravel the micro-physical mechanisms associated with flash weakening in carbonates, experiments were conducted on pre-cut Carrara marble cylinders using a rotary shear apparatus at conditions relevant to earthquakes propagation. In the first 5 mm of slip the shear stress was reduced up to 30% and CO2 was released. Focused ion beam, scanning and transmission electron microscopy investigations of the slipping zones reveal the presence of calcite nanograins and amorphous carbon. We interpret the CO2 release, the formation of nanograins and amorphous carbon to be the result of a shock-like stress release associated with the migration of fast-moving dislocations. Amorphous carbon, given its low friction coefficient, is responsible for flash weakening and promotes the propagation of the seismic rupture in carbonate-<span class="hlt">bearing</span> fault patches. PMID:26552964</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011MSSP...25..521R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011MSSP...25..521R"><span>The possibility of evaluating turbo-set <span class="hlt">bearing</span> misalignment defects on the basis of <span class="hlt">bearing</span> trajectory features</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rybczyński, Józef</p> <p>2011-02-01</p> <p>This paper presents the results of computer simulation of <span class="hlt">bearing</span> misalignment defects in a power turbogenerator. This malfunction is typical for great multi-rotor and multi-<span class="hlt">bearing</span> rotating machines and very common in power turbo-sets. Necessary calculations were carried out by the computer code system MESWIR, developed and used at the IFFM in Gdansk for calculating dynamics of rotors supported on oil <span class="hlt">bearings</span>. The results are presented in the form of a set of journal and bush trajectories of all turbo-set <span class="hlt">bearings</span>. Our analysis focuses on the vibrational effects of displacing the two most vulnerable machine <span class="hlt">bearings</span> in horizontal and vertical directions by the maximum acceptable range calculated with regard to <span class="hlt">bearing</span> vibration criterion. This assumption required preliminary assessment of the maximum values for the permissible <span class="hlt">bearing</span> dislocations. We show the relations between the attributes of the particular <span class="hlt">bearing</span> trajectories and the <span class="hlt">bearing</span> displacements in relation to their base design position. The shape and dimensions of <span class="hlt">bearing</span> trajectories are interpreted based on the theory of hydrodynamic lubrication of oil <span class="hlt">bearings</span>. It was shown that the relative journal trajectories and absolute bush trajectories carry much important information about the dynamic state of the machine, indicating also the way in which <span class="hlt">bearings</span> are loaded. Therefore, trajectories can be a source of information about the position and direction of <span class="hlt">bearing</span> misalignments. This article indicates the potential of using trajectory patterns for diagnosing misalignment defects in rotating machines and suggests including sets of trajectory patterns to the knowledge base of a machine diagnostic system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/11261','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/11261"><span>Watchable Wildlife: The Black <span class="hlt">Bear</span></span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Lynn L. Rogers</p> <p>1992-01-01</p> <p>Black <span class="hlt">bears</span> are the <span class="hlt">bears</span> people most often encounter. Black <span class="hlt">bears</span> live in forests over much of North America, unlike grizzlies that live only in Alaska, northern and western Canada, and the northern Rocky Mountains. This brochure presents the latest information on black <span class="hlt">bear</span> life and how this species responds to an ever-increasing number of campers, hikers, and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29722859','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29722859"><span><span class="hlt">Contact</span> force with magnetic-guided catheter ablation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bessière, Francis; Zikry, Christopher; Rivard, Lena; Dyrda, Katia; Khairy, Paul</p> <p>2018-05-01</p> <p>Achieving adequate catheter tip-tissue <span class="hlt">contact</span> is essential for delivering robust radiofrequency (RF) ablation lesions. We measured the <span class="hlt">contact</span> force generated by a remote magnetic-guided catheter navigation system. A plexiglass model with an integrated scale was fashioned to mimic transvenous and retrograde access to sites in the right atrium and right and left ventricles. An 8 Fr RF ablation catheter was steered by remote magnetic guidance at fields of 0.08 and 0.10 T, with and without a long sheath positioned at the entrance of the chamber. Ten <span class="hlt">contact</span> force readings were taken at each setting, with the scale recalibrated prior to each measurement. Generalized estimating equations were used to compare <span class="hlt">contact</span> force measurements while <span class="hlt">adjusting</span> for the non-independent data structure. A total of 240 <span class="hlt">contact</span> force measurements were taken. Without a long sheath, <span class="hlt">contact</span> forces with magnetic fields of 0.10 T (n = 60) and 0.08 T (n = 60) were similar (6.1 ± 1.4 g vs. 6.0 ± 1.3 g, P = 0.089). <span class="hlt">Contact</span> forces were not significantly different with simulated transvenous (n = 80) and retrograde aortic (n = 40) approaches (6.2 ± 1.4 g vs. 5.7 ± 1.2 g, P = 0.132). The <span class="hlt">contact</span> force increased substantially with a long sheath (P < 0.001) and was significantly higher with 0.10 T (n = 60) vs. 0.08 T (n = 60) fields (20.4 ± 0.6 g vs. 18.0 ± 0.5 g, P < 0.001). Magnetic fields of 0.08 and 0.10 T provide stable catheter <span class="hlt">contact</span> forces, as reflected by the small variability between measurements. The average <span class="hlt">contact</span> force is approximately 6 g without a sheath and increases to 20 g with a long sheath positioned at the entrance of the chamber of interest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22053824','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22053824"><span>Surface <span class="hlt">contact</span> stimulates the just-in-time deployment of bacterial adhesins.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Guanglai; Brown, Pamela J B; Tang, Jay X; Xu, Jing; Quardokus, Ellen M; Fuqua, Clay; Brun, Yves V</p> <p>2012-01-01</p> <p>The attachment of bacteria to surfaces provides advantages such as increasing nutrient access and resistance to environmental stress. Attachment begins with a reversible phase, often mediated by surface structures such as flagella and pili, followed by a transition to irreversible attachment, typically mediated by polysaccharides. Here we show that the interplay between pili and flagellum rotation stimulates the rapid transition between reversible and polysaccharide-mediated irreversible attachment. We found that reversible attachment of Caulobacter crescentus cells is mediated by motile cells <span class="hlt">bearing</span> pili and that their <span class="hlt">contact</span> with a surface results in the rapid pili-dependent arrest of flagellum rotation and concurrent stimulation of polar holdfast adhesive polysaccharide. Similar stimulation of polar adhesin production by surface <span class="hlt">contact</span> occurs in Asticcacaulis biprosthecum and Agrobacterium tumefaciens. Therefore, single bacterial cells respond to their initial <span class="hlt">contact</span> with surfaces by triggering just-in-time adhesin production. This mechanism restricts stable attachment to intimate surface interactions, thereby maximizing surface attachment, discouraging non-productive self-adherence, and preventing curing of the adhesive. © 2011 Blackwell Publishing Ltd.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920021920','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920021920"><span>Cryogenic Magnetic <span class="hlt">Bearing</span> Test Facility (CMBTF)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1992-01-01</p> <p>The Cryogenic Magnetic <span class="hlt">Bearing</span> Test Facility (CMBTF) was designed and built to evaluate compact, lightweight magnetic <span class="hlt">bearings</span> for use in the SSME's (space shuttle main engine) liquid oxygen and liquid hydrogen turbopumps. State of the art and tradeoff studies were conducted which indicated that a hybrid permanent magnet bias homopolar magnetic <span class="hlt">bearing</span> design would be smaller, lighter, and much more efficient than conventional industrial <span class="hlt">bearings</span>. A test <span class="hlt">bearing</span> of this type was designed for the test rig for use at both room temperature and cryogenic temperature (-320 F). The <span class="hlt">bearing</span> was fabricated from state-of-the-art materials and incorporated into the CMBTF. Testing at room temperature was accomplished at Avcon's facility. These preliminary tests indicated that this magnetic <span class="hlt">bearing</span> is a feasible alternative to older <span class="hlt">bearing</span> technologies. Analyses showed that the hybrid magnetic <span class="hlt">bearing</span> is one-third the weight, considerably smaller, and uses less power than previous generations of magnetic <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_8/Mattson_8.pdf','USGSPUBS'); return false;" href="http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_8/Mattson_8.pdf"><span>Human impacts on <span class="hlt">bear</span> habitat use</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mattson, David J.</p> <p>1990-01-01</p> <p>: Human effects on <span class="hlt">bear</span> habitat use are mediated through food biomass changes, <span class="hlt">bear</span> tolerance of humans and their impacts, and human tolerance of <span class="hlt">bears</span>. Large-scale changes in <span class="hlt">bear</span> food biomass have been caused by conversion of wildlands and waterways to intensive human use, and by the introduction of exotic pathogens. <span class="hlt">Bears</span> consume virtually all human foods that have been established in former wildlands, but <span class="hlt">bear</span> use has been limited by access. Air pollution has also affected <span class="hlt">bear</span> food biomass on a small scale and is likely to have major future impacts on <span class="hlt">bear</span> habitat through climatic warming. Major changes in disturbance cycles and landscape mosaics wrought by humans have further altered temporal and spatial pulses of <span class="hlt">bear</span> food production. These changes have brought short-term benefits in places, but have also added long-term stresses to most <span class="hlt">bear</span> populations. Although <span class="hlt">bears</span> tend to avoid humans, they will also use exotic and native foods in close proximity to humans. Subadult males and adult females are more often impelled to forage closer to humans because of their energetic predicament and because more secure sites are often preempted by adult males. Although male <span class="hlt">bears</span> are typically responsible for most livestock predation, adult females and subadult males are more likely to be habituated to humans because they tend to forage closer to humans. Elimination of human-habituated <span class="hlt">bears</span> predictably reduces effective carrying capacity and is more likely to be a factor in preserving <span class="hlt">bear</span> populations where humans are present in moderate-to-high densities. If humans desire to preserve viable <span class="hlt">bear</span> populations, they will either have to accept increased risk of injury associated with preserving habituated animals, or continue to crop habituated <span class="hlt">bears</span> while at the same time preserving large tracts of wildlands free from significant human intrusion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26803551','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26803551"><span>Active magnetic <span class="hlt">bearings</span> used as exciters for rolling element <span class="hlt">bearing</span> outer race defect diagnosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Yuanping; Di, Long; Zhou, Jin; Jin, Chaowu; Guo, Qintao</p> <p>2016-03-01</p> <p>The active health monitoring of rotordynamic systems in the presence of <span class="hlt">bearing</span> outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical <span class="hlt">bearings</span> and an active magnetic <span class="hlt">bearing</span> (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear <span class="hlt">bearing</span>-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge-Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element <span class="hlt">bearing׳s</span> incipient outer race defect. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23205234','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23205234"><span>Comparison of the clinical outcomes after total knee arthroplasty with the LCS rotating platform mobile <span class="hlt">bearing</span> knee system and the PFC Sigma RP-F mobile <span class="hlt">bearing</span> knee system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kwak, Ju-Yeong; Jeong, Jae-Heon; Lee, Sang-Hak; Jung, Ho-Joong; Jung, Young-Bok</p> <p>2012-12-01</p> <p>We compared clinical outcomes after total knee arthroplasty with the Low <span class="hlt">Contact</span> Stress (LCS) rotating platform mobile <span class="hlt">bearing</span> knee system and the Press Fit Condylar Sigma rotating platform high flexion (PFC Sigma RP-F) mobile <span class="hlt">bearing</span> knee system. Fifty cases of total knee arthroplasty were performed with the PFC Sigma RP-F mobile <span class="hlt">bearing</span> knee system and sixty-one cases were performed with the LCS mobile <span class="hlt">bearing</span> total knee arthroplasty. The average duration of follow-up was 2.9 years. The mean Hospital for Special Surgery (HSS) knee score was 62.1 (range, 52 to 75) in the LCS group and 61.9 (range, 50 to 74) in the Sigma RP-F group preoperatively, and 90.1 (range, 84 to 100) in the LCS group and 89.8 (range, 83 to 100) in the Sigma RP-F group at the final follow-up. The mean preoperative flexion contracture was 6.7° (range, 0° to 10°) in the LCS group and 9.3° (range, 0° to 15°) in the Sigma RP-F group preoperatively. The mean range of motion was 124.6° (range, 105° to 150°) in the LCS group and 126.1° (range, 104° to 145°) in the Sigma RP-F group at the final follow-up. After a minimum duration of follow-up of two years, we found no significant differences between the two groups with regard to the range of knee motion or the clinical or radiographic results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70175950','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70175950"><span>The <span class="hlt">bear</span> that never was</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Smith, T.S.; Amstrup, Steven C.; Herrero, Stephen</p> <p>2005-01-01</p> <p>From campfire stories to sensational books detailing gory attacks, Alaska's <span class="hlt">bears</span> have long been maligned as deadly marauders capable of acquiring a taste for human flesh. Tall tales make for good storytelling but force bad reputations on the <span class="hlt">bears</span>. When myth is compared to fact, the three North American's leading <span class="hlt">bear</span> experts show that Alaska's three <span class="hlt">bear</span> species are not the huge, unpredictable monsters they often are made out to be. Here, Smith, Amstrup, and Herrero examine the conventional wisdom people often hear regarding <span class="hlt">bears</span> in the Great Land.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AcMSn..32..891R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AcMSn..32..891R"><span><span class="hlt">Contact</span> force and mechanical loss of multistage cable under tension and bending</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ru, Yanyun; Yong, Huadong; Zhou, Youhe</p> <p>2016-10-01</p> <p>A theoretical model for calculating the stress and strain states of cabling structures with different loadings has been developed in this paper. We solve the problem for the first- and second-stage cable with tensile or bending strain. The <span class="hlt">contact</span> and friction forces between the strands are presented by two-dimensional <span class="hlt">contact</span> model. Several theoretical models have been proposed to verify the results when the triplet subjected to the tensile strain, including <span class="hlt">contact</span> force, <span class="hlt">contact</span> stresses, and mechanical loss. It is found that loadings will affect the friction force and the mechanical loss of the triplet. The results show that the <span class="hlt">contact</span> force and mechanical loss are dependent on the twist pitch. A shorter twist pitch can lead to higher <span class="hlt">contact</span> force, while the trend of mechanical loss with twist pitch is complicated. The mechanical loss may be reduced by <span class="hlt">adjusting</span> the twist pitch reasonably. The present model provides a simple analysis method to investigate the mechanical behaviors in multistage-structures under different loads.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19650015804','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19650015804"><span>Study Program to Determine the Acceleration Environment Capability of the GG159C Gas- <span class="hlt">Bearing</span> Spinmotor Final Report</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Erickson, G. J.</p> <p>1964-01-01</p> <p>The goal of this contract was to determine the g environment under which the GC159C Gas-<span class="hlt">Bearing</span> Spinmotor (GBSM) could reliably operate. This was fulfilled by building and testing of four GBSM's, a test fixture, and a "dummy" gyro. The test program was divided into two phases when a gas <span class="hlt">bearing</span> improvement was required to withstand JPL shock requirement of 200 g. Phase I determined existing g capabilities and performance of the GC159C GBSM and gimbal-case structure. Phase II increased GBSM capability to meet required JPL g environments. Life tests were run on two GBSM's which were shocked at a high level to obtain <span class="hlt">bearing</span> <span class="hlt">contact</span> while rotating at their operating speed of 23,000 rpm. A third (nonoperating) GBSM was exposed to JPL maximum shock levels, and a fourth (nonoperating) GBSM was exposed to random vibration. Both nonoperating GBSM's were then subjected to life testing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930094474','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930094474"><span>Tests of Lead-bronze <span class="hlt">Bearings</span> in the DVL <span class="hlt">Bearing</span>-testing Machine</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fischer, G</p> <p>1940-01-01</p> <p>The lead-bronze <span class="hlt">bearings</span> tested in the DVL machine have proven themselves very sensitive to load changes as in comparison with <span class="hlt">bearings</span> of light metal. In order to prevent surface injuries and consequently running interruptions, the increase of the load has to be made in small steps with sufficient run-in time between steps. The absence of lead in the running surface, impurities in the alloy (especially iron) and surface irregularities (pores) decreases the load-carrying capacity of the <span class="hlt">bearing</span> to two or three times that of the static load.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Nanot..29e5501L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Nanot..29e5501L"><span>Multidirectional flexible force sensors based on confined, self-<span class="hlt">adjusting</span> carbon nanotube arrays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, J.-I.; Pyo, Soonjae; Kim, Min-Ook; Kim, Jongbaeg</p> <p>2018-02-01</p> <p>We demonstrate a highly sensitive force sensor based on self-<span class="hlt">adjusting</span> carbon nanotube (CNT) arrays. Aligned CNT arrays are directly synthesized on silicon microstructures by a space-confined growth technique which enables a facile self-<span class="hlt">adjusting</span> <span class="hlt">contact</span>. To afford flexibility and softness, the patterned microstructures with the integrated CNTs are embedded in polydimethylsiloxane structures. The sensing mechanism is based on variations in the <span class="hlt">contact</span> resistance between the facing CNT arrays under the applied force. By finite element analysis, proper dimensions and positions for each component are determined. Further, high sensitivities up to 15.05%/mN of the proposed sensors were confirmed experimentally. Multidirectional sensing capability could also be achieved by designing multiple sets of sensing elements in a single sensor. The sensors show long-term operational stability, owing to the unique properties of the constituent CNTs, such as outstanding mechanical durability and elasticity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3689268','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3689268"><span>Comparison of metabolic responses of United States Military Academy men and women in acute military load <span class="hlt">bearing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stauffer, R W; McCarter, M; Campbell, J L; Wheeler, L F</p> <p>1987-11-01</p> <p>Twenty-four first year United States Military Academy (USMA) men and women were studied to compare metabolic response differences in seven horizontal walking velocities, under three military load <span class="hlt">bearing</span> conditions. The treadmill protocol consisted of walking or jogging on a horizontal treadmill surface for 3-min intervals at velocities of 3, 3.5, 4, 4.5, 5, 5.5, and 6 mph. The three military load <span class="hlt">bearing</span> conditions weighed 5, 12, and 20 kg. Metabolic measurements taken at each speed in each of the military load <span class="hlt">bearing</span> conditions were: minute volume, tidal volume, respiratory rate, absolute and relative to body weight oxygen consumption, and respiratory quotient. Two three-way analyses of variance for repeated measures tests with main effects of gender, military load, and speed revealed that USMA men and women metabolically respond to different military load <span class="hlt">bearing</span> conditions; they metabolically respond to different walking and jogging velocities under military load <span class="hlt">bearing</span> conditions; and they have identifiable and quantifiable metabolic response differences to military load <span class="hlt">bearing</span>. This study was designed to improve USMA physical and military training programs by providing information to equally and uniformly administer the USMA Doctrine of Comparable Training to men and women alike; and additionally to clarify the "...minimal essential <span class="hlt">adjustments</span>...required because of physiological differences between male and female individuals ..." portion of Public Law 94-106 providing for the admission of women to America's Service Academies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960052905','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960052905"><span>Magnetic <span class="hlt">Bearings</span> at Draper Laboratory</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kondoleon, Anthony S.; Kelleher, William P.; Possel, Peter D.</p> <p>1996-01-01</p> <p>Magnetic <span class="hlt">bearings</span>, unlike traditional mechanical <span class="hlt">bearings</span>, consist of a series of components mated together to form a stabilized system. The correct design of the actuator and sensor will provide a cost effective device with low power requirements. The proper choice of a control system utilizes the variables necessary to control the system in an efficient manner. The specific application will determine the optimum design of the magnetic <span class="hlt">bearing</span> system including the touch down <span class="hlt">bearing</span>. Draper for the past 30 years has been a leader in all these fields. This paper summarizes the results carried out at Draper in the field of magnetic <span class="hlt">bearing</span> development. A 3-D radial magnetic <span class="hlt">bearing</span> is detailed in this paper. Data obtained from recently completed projects using this design are included. One project was a high radial load (1000 pound) application. The second was a high speed (35,000 rpm), low loss flywheel application. The development of a low loss axial magnetic <span class="hlt">bearing</span> is also included in this paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19152614','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19152614"><span>Effect of tibial plateau leveling osteotomy on femorotibial <span class="hlt">contact</span> mechanics and stifle kinematics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Stanley E; Pozzi, Antonio; Banks, Scott A; Conrad, Bryan P; Lewis, Daniel D</p> <p>2009-01-01</p> <p>To evaluate the effects of tibial plateau leveling osteotomy (TPLO) on femorotibial <span class="hlt">contact</span> mechanics and 3-dimensional (3D) kinematics in cranial cruciate ligament (CrCL)-deficient stifles of dogs. In vitro biomechanical study. Unpaired pelvic limbs from 8 dogs, weighing 28-35 kg. Digital pressure sensors placed subjacent to the menisci were used to measure femorotibial <span class="hlt">contact</span> force, <span class="hlt">contact</span> area, peak and mean <span class="hlt">contact</span> pressure, and peak pressure location with the limb under an axial load of 30% body weight and a stifle angle of 135 degrees. Three-dimensional static poses of the stifle were obtained using a Microscribe digitizing arm. Each specimen was tested under normal, CrCL-deficient, and TPLO-treated conditions. Repeated measures analysis of variance with a Tukey post hoc test (P<.05) was used for statistical comparison. Significant disturbances to all measured <span class="hlt">contact</span> mechanical variables were evident after CrCL transection, which corresponded to marked cranial tibial subluxation and increased internal tibial rotation in the CrCL-deficient stifle. No significant differences in 3D femorotibial alignment were observed between normal and TPLO-treated stifles; however, femorotibial <span class="hlt">contact</span> area remained significantly smaller and peak <span class="hlt">contact</span> pressures in both medial and lateral stifle compartments were positioned more caudally on the tibial plateau, when compared with normal. Whereas TPLO eliminates craniocaudal stifle instability during simulated weight <span class="hlt">bearing</span>, the procedure fails to concurrently restore femorotibial <span class="hlt">contact</span> mechanics to normal. Progression of stifle osteoarthritis in dogs treated with TPLO may be partly the result of abnormal stifle <span class="hlt">contact</span> mechanics induced by altering the orientation of the proximal tibial articulating surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29471451','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29471451"><span>Genomic Evidence of Widespread Admixture from Polar <span class="hlt">Bears</span> into Brown <span class="hlt">Bears</span> during the Last Ice Age.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cahill, James A; Heintzman, Peter D; Harris, Kelley; Teasdale, Matthew D; Kapp, Joshua; Soares, Andre E R; Stirling, Ian; Bradley, Daniel; Edwards, Ceiridwen J; Graim, Kiley; Kisleika, Aliaksandr A; Malev, Alexander V; Monaghan, Nigel; Green, Richard E; Shapiro, Beth</p> <p>2018-05-01</p> <p>Recent genomic analyses have provided substantial evidence for past periods of gene flow from polar <span class="hlt">bears</span> (Ursus maritimus) into Alaskan brown <span class="hlt">bears</span> (Ursus arctos), with some analyses suggesting a link between climate change and genomic introgression. However, because it has mainly been possible to sample <span class="hlt">bears</span> from the present day, the timing, frequency, and evolutionary significance of this admixture remains unknown. Here, we analyze genomic DNA from three additional and geographically distinct brown <span class="hlt">bear</span> populations, including two that lived temporally close to the peak of the last ice age. We find evidence of admixture in all three populations, suggesting that admixture between these species has been common in their recent evolutionary history. In addition, analyses of ten fossil <span class="hlt">bears</span> from the now-extinct Irish population indicate that admixture peaked during the last ice age, whereas brown <span class="hlt">bear</span> and polar <span class="hlt">bear</span> ranges overlapped. Following this peak, the proportion of polar <span class="hlt">bear</span> ancestry in Irish brown <span class="hlt">bears</span> declined rapidly until their extinction. Our results support a model in which ice age climate change created geographically widespread conditions conducive to admixture between polar <span class="hlt">bears</span> and brown <span class="hlt">bears</span>, as is again occurring today. We postulate that this model will be informative for many admixing species pairs impacted by climate change. Our results highlight the power of paleogenomics to reveal patterns of evolutionary change that are otherwise masked in contemporary data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150004053','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150004053"><span>A Study on the Effects of Ball Defects on the Fatigue Life in Hybrid <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tang, Ching-Yao; Foerster, Chad E.; O'Brien, Michael J.; Hardy, Brian S.; Goyal, Vinay K.; Nelson, Benjamin A.; Robinson, Ernest Y.; Ward, Peter C.; Hilton, Michael R.</p> <p>2014-01-01</p> <p>Hybrid ball <span class="hlt">bearings</span> using silicon nitride ceramic balls with steel rings are increasingly being used in space mechanism applications due to their high wear resistance and long rolling <span class="hlt">contact</span> fatigue life. However, qualitative and quantitative reports of the effects of ball defects that cause early fatigue failure are rare. We report on our approach to study these effects. Our strategy includes characterization of defects encountered in use, generation of similar defects in a laboratory setting, execution of full-scale <span class="hlt">bearing</span> tests to obtain lifetimes, post-test characterization, and related finite-element modeling to understand the stress concentration of these defects. We have confirmed that at least one type of defect of appropriate size can significantly reduce fatigue life. Our method can be used to evaluate other defects as they occur or are encountered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760007379','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760007379"><span>Investigations of a <span class="hlt">bearing</span> fault detector for railroad <span class="hlt">bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, D. S.; Frarey, J. L.</p> <p>1975-01-01</p> <p>The laboratory tests are described which were conducted on new and damaged <span class="hlt">bearings</span> to determine the feasibility of using high-frequency vibration as a diagnostic tool. A high-frequency band pass filter and demodulator was assembled to permit field measurements of the high-frequency vibrations. Field tests were conducted on an actual truck and on an axle assembly run in a grease test rig. These field tests were directed toward demonstration of the suitability and capabilities of the high-frequency technique for field application. Two specific areas of field application were identified as being cost effective for railroad use. One area is the examination of railroad roller <span class="hlt">bearings</span> at a derailment site, and the second is as a wayside detector to supplement present hot box detectors for defective roller <span class="hlt">bearings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950065489&hterms=knife&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dknife','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950065489&hterms=knife&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dknife"><span>Supertough Stainless <span class="hlt">Bearing</span> Steel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Olson, Gregory B.</p> <p>1995-01-01</p> <p>Composition and processing of supertough stainless <span class="hlt">bearing</span> steel designed with help of computer-aided thermodynamic modeling. Fracture toughness and hardness of steel exceeds those of other <span class="hlt">bearing</span> steels like 440C stainless <span class="hlt">bearing</span> steel. Developed for service in fuel and oxidizer turbopumps on Space Shuttle main engine. Because of strength and toughness, also proves useful in other applications like gears and surgical knives.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11206987','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11206987"><span>Musculoskeletal system of the neck of the polar <span class="hlt">bear</span> (Ursus maritimus) and the Malayan <span class="hlt">bear</span> (Helarctos malayanus).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Endo, H; Kakegawa, Y; Taru, H; Sasaki, M; Hayashi, Y; Yamamoto, M; Arishima, K</p> <p>2001-01-01</p> <p>The gross anatomical study was undertaken in the musculoskeletal system of the neck of the polar <span class="hlt">bear</span>, and the findings were compared with those of the Malayan <span class="hlt">bear</span>. The Musculus splenius and the M. trapezius were well-developed in the polar <span class="hlt">bear</span>. The long neck of the polar <span class="hlt">bear</span> consisted mainly of the M. splenius with the M. biventer cervicis and the M. complexus lying tightly underneath. The cervical vertebrae possessed huge ventral tubercle in the ventral part of the transverse process in the polar <span class="hlt">bear</span>. These morphological characteristics suggest that the polar <span class="hlt">bear</span> may rotate and bend the skull and the long cervical vertebrae. We postulate that the polar <span class="hlt">bear</span> has evolved the high-mobility long neck to adapt for swimming. Unlike the polar <span class="hlt">bear</span>, the Malayan <span class="hlt">bear</span> has not specialized in the neck structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950015988','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950015988"><span>Wave Journal <span class="hlt">Bearing</span>. Part 2: Experimental Pressure Measurements and Fractional Frequency Whirl Threshold for Wave and Plain Journal <span class="hlt">Bearings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Walker, James F.; Dimofte, Florin; Addy, Harold E., Jr.</p> <p>1995-01-01</p> <p>A new hydrodynamic <span class="hlt">bearing</span> concept, the wave journal <span class="hlt">bearing</span>, is being developed because it has better stability characteristics than plain journal <span class="hlt">bearings</span> while maintaining similar load capacity. An analysis code to predict the steady state and dynamic performance of the wave journal <span class="hlt">bearing</span> is also part of the development. To verify numerical predictions and contrast the wave journal <span class="hlt">bearing</span>'s stability characteristics to a plain journal <span class="hlt">bearing</span>, tests were conducted at NASA Lewis Research Center using an air <span class="hlt">bearing</span> test rig. <span class="hlt">Bearing</span> film pressures were measured at 16 ports located around the <span class="hlt">bearing</span> circumference at the middle of the <span class="hlt">bearing</span> length. The pressure measurements for both a plain journal <span class="hlt">bearing</span> and a wave journal <span class="hlt">bearing</span> compared favorably with numerical predictions. Both <span class="hlt">bearings</span> were tested with no radial load to determine the speed threshold for self-excited fractional frequency whirl. The plain journal <span class="hlt">bearing</span> started to whirl immediately upon shaft start-up. The wave journal did not incur self-excited whirl until 800 to 900 rpm as predicted by the analysis. Furthermore, the wave <span class="hlt">bearing</span>'s geometry limited the whirl orbit to less than the <span class="hlt">bearing</span>'s clearance. In contrast, the plain journal <span class="hlt">bearing</span> did not limit the whirl orbit, causing it to rub.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3087620','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3087620"><span>Exposure to Electrical <span class="hlt">Contact</span> Currents and the Risk of Childhood Leukemia</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Does, Monique; Scélo, Ghislaine; Metayer, Catherine; Selvin, Steve; Kavet, Robert; Buffler, Patricia</p> <p>2011-01-01</p> <p>The objectives of this study were to examine the association between <span class="hlt">contact</span> current exposure and the risk of childhood leukemia and to investigate the relationship between residential <span class="hlt">contact</span> currents and magnetic fields. Indoor and outdoor <span class="hlt">contact</span> voltage and magnetic-field measurements were collected for the diagnosis residence of 245 cases and 269 controls recruited in the Northern California Childhood Leukemia Study (2000–2007). Logistic regression techniques produced odds ratios (OR) <span class="hlt">adjusted</span> for age, sex, Hispanic ethnicity, mother’s race and household income. No statistically significant associations were seen between childhood leukemia and indoor <span class="hlt">contact</span> voltage level [exposure ≥90th percentile (10.5 mV): OR = 0.83, 95% confidence interval (CI): 0.45, 1.54], outdoor <span class="hlt">contact</span> voltage level [exposure ≥90th percentile (291.2 mV): OR = 0.89, 95% CI: 0.48, 1.63], or indoor magnetic-field levels (>0.20 μT: OR = 0.76, 95% CI: 0.30, 1.93). <span class="hlt">Contact</span> voltage was weakly correlated with magnetic field; correlation coefficients were r = 0.10 (P = 0.02) for indoor <span class="hlt">contact</span> voltage and r = 0.15 (P = 0.001) for outdoor <span class="hlt">contact</span> voltage. In conclusion, in this California population, there was no evidence of an association between childhood leukemia and exposure to <span class="hlt">contact</span> currents or magnetic fields and a weak correlation between measures of <span class="hlt">contact</span> current and magnetic fields. PMID:21388283</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.elsevier.com/books/encyclopedia-of-marine-mammals/wursig/978-0-12-804327-1','USGSPUBS'); return false;" href="https://www.elsevier.com/books/encyclopedia-of-marine-mammals/wursig/978-0-12-804327-1"><span>Polar <span class="hlt">bears</span>, Ursus maritimus</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rode, Karyn D.; Stirling, Ian</p> <p>2017-01-01</p> <p>Polar <span class="hlt">bears</span> are the largest of the eight species of <span class="hlt">bears</span> found worldwide and are covered in a pigment-free fur giving them the appearance of being white. They are the most carnivorous of <span class="hlt">bear</span> species consuming a high-fat diet, primarily of ice-associated seals and other marine mammals. They range throughout the circumpolar Arctic to the southernmost extent of seasonal pack ice.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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