Sample records for hydrostatic bearings

  1. Simple modeling of hydrostatic bearings

    NASA Astrophysics Data System (ADS)

    Hull, Charlie

    2014-07-01

    Hydrostatic bearings are a key component for many large telescopes due to their high load bearing capacity, stiffness and low friction. A simple technique is presented to model these bearings to understand the effects of geometry, oil viscosity, flow control, temperature, etc. on the bearings behavior.

  2. Design of a low cost hydrostatic bearing

    E-print Network

    Wong, Anthony Raymond

    2012-01-01

    This thesis presents the design and manufacturing method for a new surface self compensating hydrostatic bearing. A lumped resistance model was used to analyze the performance of the bearing and provide guidance on laying ...

  3. Control Method of Heavy Hydrostatic Thrust Bearing

    Microsoft Academic Search

    Guihua Han; Jianying Li; Yuhong Dong; Junpeng Shao

    2009-01-01

    A hybrid fuzzy control scheme was applied to improve the rigidity of hydrostatic thrust bearing. The bearing oil film control was realized by coupling oil film thickness of four controllable chambers. The chamber flow can be regulated by electro hydraulic servo valve-control variable pump according to the surface roughness, load, cutting force, and thermal effects of worktable. The nonlinear hybrid

  4. Active hydrostatic bearing with magnetorheological fluid

    NASA Astrophysics Data System (ADS)

    Hesselbach, J.; Abel-Keilhack, C.

    2003-05-01

    Special bearings based on magnetic fluids are well known in literature. These bearings use the magnetic pressure inside a ferrofluid that is exposed to a magnetic field. The biggest disadvantage of this principle is the small load that can be supported. In one reference [B. M. Berkovsky, V. F. Medvedev, and M. S. Krakov, Magnetic Fluids, Engineering Applications (Oxford University Press, Oxford, 1993)], the specific load is specified as 1 N cm-2. To support heavy loads very large support areas are needed. We will present a completely different concept for bearings with magnetorheological fluids. Hydrostatic bearings get their load bearing capacity from the hydrostatic pressure produced by an external pump and should not be confused with hydrodynamic bearings presented in another reference [R. Patzwald, M. S. thesis, Institute für Werkzeugmaschinen und Fabrikbetrieb, Technische Universität, Berlin (2001)]. The main disadvantage of hydrostatic bearings is that the bearing gap varies with the payload. Conventional systems compensate for these variations with a change of the oil flow rate, that is done, for example, by external valves. Our contribution will present a hydrostatic bearing that uses magnetorheological fluids. Due to the fact that magnetorheological fluids change their rheological properties with the change of an external magnetic field, it is possible to achieve a constant bearing gap even if the payload changes. The great advantage of this system compared to valve based systems is the short response time to payload changes, because the active element (i.e., the fluid) acts directly inside the bearing gap, and not outside like in the case of valves.

  5. Design, dynamic modeling, simulation and feedback control of hydrostatic bearing

    E-print Network

    Rothenhöfer, Gerald S. (Gerald Sven)

    2007-01-01

    A hydrostatic bearing carriage (Hydrocline) that uses an open face linear motor to drive the carriage as well as to preload the hydrostatic bearings has been developed by Professor Alexander Slocum and Gerald Rothenhöfer ...

  6. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, James R. (Rigby, ID)

    1982-01-01

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  7. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, J.R.

    1982-05-04

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion. 3 figs.

  8. Hydrostatic bearings for a turbine fluid flow metering device

    Microsoft Academic Search

    Fincke

    1980-01-01

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between

  9. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, J.R.

    1980-05-02

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  10. Hybrid hydrostatic/ball bearings in high-speed turbomachinery

    NASA Technical Reports Server (NTRS)

    Nielson, C. E.

    1983-01-01

    A high speed, high pressure liquid hydrogen turbopump was designed, fabricated, and tested under a previous contract. This design was then modified to incorporate hybrid hydrostatic/ball bearings on both the pump end and turbine end to replace the original conventional ball bearing packages. The design, analysis, turbopump modification, assembly, and testing of the turbopump with hybrid bearings is presented here. Initial design considerations and rotordynamic performance analysis was made to define expected turbopump operating characteristics and are reported. The results of testing the turbopump to speeds of 9215 rad/s (88,000 rpm) using a wide range of hydrostatic bearing supply pressures are presented. The hydrostatic bearing test data and the rotordynamic behavior of the turbopump was closely analyzed and are included in the report. The testing of hybrid hydrostatic/ball bearings on a turbopump to the high speed requirements has indicated the configuration concept is feasible. The program has presented a great deal of information on the technology requirements of integrating the hybrid bearing into high speed turbopump designs for improved bearing life.

  11. Analysis of hydrostatic journal bearings with end seals

    NASA Astrophysics Data System (ADS)

    San Andres, L. A.

    1992-10-01

    An approximate analysis for the pressure field and dynamic force coefficients in turbulent flow, centered hydrostatic journal bearings (HJBs) with fluid inertia and liquid compressibility effects is presented. Results from the analysis show that HJBs with end seals have increased damping, better dynamic stability characteristics, as well as lower flow rates, than conventional HJBs. However, hydrostatic (direct) stiffness may be lost if excessively tight end seals are used. End seals are shown to compensate for the effect of liquid compressibility within the recess volume, and prescribe a net reduction in the whirl frequency ratio for hybrid operation. Hydrostatic squeeze film dampers (HSFD) with end seals are shown to be a viable alternative in applications where a tight control of the bearing leakage is important such as in jet-engines. Furthermore, HSFDs with end seals could be used as an active device to control the available damping in a typical application.

  12. Experimental equipment for measuring physical properties of the annular hydrostatic thrust bearing

    NASA Astrophysics Data System (ADS)

    Kozdera, Michal; Drábková, Sylva; Bojko, Marian

    2014-03-01

    The hydraulic circuit, through which the mineral oil is brought, is an important part of hydrostatic bearings. The annular hydrostatic thrust bearing 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 bearing, is the source of the pressure energy. The sliding bearing 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 adjusting 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 bearing 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 bearing.

  13. A parameter identification method for the rotordynamic coefficients of a high Reynolds number hydrostatic bearing

    NASA Technical Reports Server (NTRS)

    Rouvas, C.; Childs, D. W.

    1993-01-01

    In identifying the rotordynamic coefficients of a high-Reynolds-number hydrostatic bearing, fluid-flow induced forces present a unique problem, in that they provide an unmeasureable and uncontrollable excitation to the bearing. An analysis method is developed that effectively eliminates the effects of fluid-flow induced excitation on the estimation of the bearing rotordynamic coefficients, by using power spectral densities. In addition to the theoretical development, the method is verified experimentally by single-frequency testing, and repeatability tests. Results obtained for a bearing are the twelve rotordynamic coefficients (stiffness, damping, and inertia coefficients) as functions of eccentricity ratio, speed, and supply pressure.

  14. A test apparatus and facility to identify the rotordynamic coefficients of high-speed hydrostatic bearings

    Microsoft Academic Search

    Dara Childs; Keith Hale

    1994-01-01

    A facility and apparatus are described which determine stiffness, damping, and added-mass rotordynamic coefficients plus steady-state operating characteristics of high speed hydrostatic journal bearings. The apparatus has a current top speed of 29,800 rpm with a bearing diameter of 7.62 cm (3 in.). Purified warm water, 55 C (130 F), is used as a test fluid to achieve elevated Reynolds

  15. Hardware-in-loop simulation on hydrostatic thrust bearing worktable pose

    Microsoft Academic Search

    Gui-hua Han; Jun-peng Shao; Bai Qin; Yu-hong Dong

    2008-01-01

    A controllable hydrostatic thrust bearing was presented to improve rigidity. The bearing worktable poses were controlled by\\u000a coupling oilfilm thickness of four controllable chambers. The chamber flow can be regulated by electro hydraulic servo valve-control\\u000a variable pump according to the surface roughness, load, cutting force, and thermal effects of worktable. The mathematical\\u000a models of the controllable chamber flow, servo variable

  16. Investigation of a hydrostatic azimuth thrust bearing for a large steerable antenna

    NASA Technical Reports Server (NTRS)

    Rumbarger, J.; Castelli, V.; Rippel, H.

    1972-01-01

    The problems inherent in the design and construction of a hydrostatic azimuth thrust bearing for a tracking antenna of very large size were studied. For a load of 48,000,000 lbs., it is concluded that the hydrostatic bearing concept is feasible, provided that a particular multiple pad arrangement, high oil viscosity, and a particular load spreading arrangement are used. Presently available computer programs and techniques are deemed to be adequate for a good portion of the design job but new integrated programs will have to be developed in the area of the computation of the deflections of the supporting bearing structure. Experimental studies might also be indicated to ascertain the life characteristics of grouting under cyclic loading, and the optimization of hydraulic circuits and pipe sizes to insure the long life operation of pumps with high viscosity oil while avoiding cavitation.

  17. Dynamic force response of spherical hydrostatic journal bearing for cryogenic applications

    NASA Technical Reports Server (NTRS)

    Sanandres, Luis

    1994-01-01

    Hydrostatic Journal Bearings (HJB's) are reliable and resilient fluid film rotor support elements ideal to replace roller bearings in cryogenic turbomachinery. HJB' will be used for primary space-power applications due to their long lifetime, low friction and wear, large load capacity, large direct stiffness, and damping force coefficients. An analysis for the performance characteristics of turbulent flow, orifice compensated, spherical hydrostatic journal bearings (HJB's) is presented. Spherical bearings allow tolerance for shaft misalignment without force performance degradation and have also the ability to support axial loads. The spherical HJB combines these advantages to provide a bearing design which could be used efficiently on high performance turbomachinery. The motion of a barotropic liquid on the thin film bearing lands is described by bulk-flow mass and momentum equations. These equations are solved numerically using an efficient CFD method. Numerical predictions of load capacity and force coefficients for a 6 recess, spherical HJB in a LO2 environment are presented. Fluid film axial forces and force coefficients of a magnitude about 20% of the radial load capacity are predicted for the case analyzed. Fluid inertia effects, advective and centrifugal, are found to affect greatly the static and dynamic force performance of the bearing studied.

  18. Development of a polymetric grout for the hydrostatic bearing at DSS 14

    NASA Technical Reports Server (NTRS)

    Mcclung, C. E.; Schwendeman, J. L.; Ball, G. L., III; Jenkins, G. H.; Casperson, R. D.; Gale, G. P.; Riewe, A. A.

    1981-01-01

    Results of an investigation into the causes of the deterioration and premature failure of the grout under the hydrostatic bearing runner at DSS 14 are reported. Generic types of materials were screened and tested to find a grout material more resistive to the causes of grout failure. Emphasis was placed on the physical properties, strength, modulus of elasticity, and resistance to erosion and chemical attack by oil and unique requirements imposed by each material for mixing, placing, compacting, and cooling. The polymetric grout developed to replace the dry grout is described.

  19. Three Dimensional Flow and Pressure Patterns in a Hydrostatic Journal Bearing

    NASA Technical Reports Server (NTRS)

    Braun, M. Jack; Dzodzo, Milorad B.

    1996-01-01

    The flow in a hydrostatic journal bearing (HJB) is described by a mathematical model that uses the three dimensional non-orthogonal form of the Navier-Stokes equations. Using the u, v, w, and p, as primary variables, a conservative formulation, finite volume multi-block method is applied through a collocated, body fitted grid. The HJB has four shallow pockets with a depth/length ratio of 0.067. This paper represents a natural extension to the two and three dimensional studies undertaken prior to this project.

  20. Non-Newtonian temperature and pressure effects of a lubricant slurry in a rotating hydrostatic step bearing

    SciTech Connect

    Peterson, J.; Finn, W.E.; Dareing, D.W. [Univ. of Florida, Gainsville, FL (United States)]|[Univ. of Southwestern Louisiana, Lafayette, LA (United States)

    1994-10-01

    The purpose of this research was to investigate the pressure and temperature effects of graphite powder lubricant when added to a Newtonian carrier fluid and applied in a rotating hydrostatic step bearing. Temperature and pressure profiles were determined both analytically and experimentally. The rheological behavior of the non-Newtonian lubricant was modeled using a power law model previously shown to approximate experimental data for this fluid. Ethylene glycol was used as the Newtonian lubricant, providing a check on the test apparatus and a base line for comparison with the non-Newtonian graphite slurry. Data revealed a temperature increase with bearing rotational speed for both fluids and compared favorably with the mathematical predictions. A significantly higher temperature rise was seen in the non- Newtonian lubricant due to the higher shear rates. The pressure profile was not directly dependent on bearing rotational speed in the mathematical model, but experimental data demonstrated a reduction in pressure at higher rotation speeds. This loss was greater for the non-Newtonian lubricant and attributed to temperature dependence of power law constants. It was concluded that the effects of operating speed and temperature on a non-Newtonian lubricant should be considered as well as their greater load-carrying capacity.

  1. Three Dimensional Flow and Pressure Patterns in a Single Pocket of a Hydrostatic Journal Bearing

    NASA Technical Reports Server (NTRS)

    Braun, M. Jack; Dzodzo, Milorad B.

    1996-01-01

    The flow in a hydrostatic pocket is described by a mathematical model that uses the three dimensional Navier-Stokes equations written in terms of the primary variables, u, v, w, and p. Using a conservative formulation, a finite volume multi-block method is applied through a collocated, body fitted grid. The flow is simulated in a shallow pocket with a depth/length ratio of 0.02. The flow structures obtained and described by the authors in their previous two dimensional models are made visible in their three dimensional aspect for the Couette flow. It has been found that the flow regimes formed central and secondary vortical cells with three dimensional corkscrew-like structures that lead the fluid on an outward bound path in the axial direction of the pocket. The position of the central vortical cell center is at the exit region of the capillary restrictor feedline. It has also been determined that a fluid turn around zone occupies all the upstream space between the floor of the pocket and the runner, thus preventing any flow exit through the upstream port. The corresponding pressure distribution under the shaft presented as well. It was clearly established that for the Couette dominated case the pressure varies significantly in the pocket in the circumferential direction, while its variation is less pronounced axially.

  2. Bearing misalignment effects on the hydrostatic and hydrodynamic behaviour of gears in fixed clearance end plates

    NASA Astrophysics Data System (ADS)

    Koc, E.

    1994-04-01

    Lubrication and sealing mechanisms of fixed clearance end plates in high-pressure pumps have been analysed theoretically and experimentally. Bearing misalignment was found to be the main lubrication mechanism, and it was effective in determining the gear position between two end plates. The minimum film thickness between the gear end and end plate has been found to depend on the magnitude of the relative tilt of the surfaces and the position of the maximum clearance. The theory developed can predict the film thickness between the end plate and gear end face, and this corresponds very closely to the clearances measured experimentally under a variety of operating conditions.

  3. Measurements versus Predictions for a Hybrid (Hydrostatic plus Hydrodynamic Thrust Bearing for a Range of Orifice Diameters

    E-print Network

    Esser, Paul R.

    2011-08-08

    A fixed geometry hybrid thrust bearing is investigated with three different supply orifice diameters. The test rig uses a face-to-face thrust bearing design, with the test bearing acting as the rotor loading mechanism. A hydraulic shaker applies...

  4. Effect of design parameter variations on hybrid (combination hydrostatic and hydrodynamic) bearings for use in high speed turbomachinery 

    E-print Network

    Mosher, Phillip Andrew

    1993-01-01

    . The resulting net pressure distribution on the journal produces a force directly opposing the load on the bearing and thereby supports the journal. As the journal speed increases, the viscous shear forces developed within the land area (non-recess area..., particularly in the area of hybrid-journal-bearing rotordynamic behavior. OB JECTIVES The first objective of this thesis is to examine the behavior of hybrid bearings as the following design parameters are varied: radial clearance, concentric recess...

  5. Effect of design parameter variations on hybrid (combination hydrostatic and hydrodynamic) bearings for use in high speed turbomachinery

    E-print Network

    Mosher, Phillip Andrew

    1993-01-01

    . The resulting net pressure distribution on the journal produces a force directly opposing the load on the bearing and thereby supports the journal. As the journal speed increases, the viscous shear forces developed within the land area (non-recess area..., particularly in the area of hybrid-journal-bearing rotordynamic behavior. OB JECTIVES The first objective of this thesis is to examine the behavior of hybrid bearings as the following design parameters are varied: radial clearance, concentric recess...

  6. Bears, Bears, Bears!

    NSDL National Science Digital Library

    Ms.Beason

    2011-04-16

    What are some things you learned about bears? Use these websites to find out about bears: Parts of a Bear Polar Bears Real Story of the Three Bears The truth about bears Brown Bears Now fill in your chart! Bear Fact Sheet Listen to your teacher for further instruction on completing a book about bears! ...

  7. Dynamic modeling of hydrostatic guideway considering compressibility and inertia effect

    NASA Astrophysics Data System (ADS)

    Du, Yikang; Mao, Kuanmin; Zhu, Yaming; Wang, Fengyun; Mao, Xiaobo; Li, Bin

    2015-03-01

    Hydrostatic guideways are used as an alternative to contact bearings due to high stiffness and high damping in heavy machine tools. To improve the dynamic characteristic of bearing structure, the dynamic modeling of the hydrostatic guidway should be accurately known. This paper presents a "mass-spring-Maxwell" model considering the effects of inertia, squeeze, compressibility and static bearing. To determine the dynamic model coefficients, numerical simulation of different cases between displacement and dynamic force of oil film are performed with fluent code. Simulation results show that hydrostatic guidway can be taken as a linear system when it is subjected to a small oscillation amplitude. Based on a dynamic model and numerical simulation, every dynamic model's parameters are calculated by the Levenberg-Marquardt algorithm. Identification results show that "mass-spring-damper" model is the most appropriate dynamic model of the hydrostatic guidway. This paper provides a reference and preparation for the analysis of the dynamic model of the similar hydrostatic bearings.

  8. Rotordynamic evaluation of a roughened-land hybrid bearing 

    E-print Network

    Fayolle, Patrice Gerard

    1997-01-01

    Hybrid bearings (combinations of hydrostatic and hydrodynamic bearings) represent an attractive alternative to ball bearings for use in high-speed cryogenic turbopumps. However, the internally-developed cross-coupled forces can generate...

  9. Performance of gas-lubricated nonconforming pivoted-pad journal bearings and a flexibly mounted spiral-groove thrust bearing

    NASA Technical Reports Server (NTRS)

    Ream, L. W.

    1973-01-01

    A test program was conducted to determine the performance characteristics of gas-lubricated nonconforming pivoted-pad journal bearings and a spiral-groove thrust bearing designed for the Brayton cycle rotating unit (BRU). Hydrostatic, hybrid (simultaneously hydrostatic and hydrodynamic), and hydrodynamic tests were conducted in argon gas at ambient pressure and temperature ranges representative of hydrostatic operation up to the 10.5-kWe BRU power-generating level. Performance of the gas lubricated bearings is presented, including hydrostatic gas flow rates, bearing clearances, bearing temperatures, and transient performance.

  10. Optimal speed sharing characteristics of a series-hybrid bearing

    NASA Technical Reports Server (NTRS)

    Nypan, L. J.; Scibbe, H. W.; Hamrock, B. J.

    1972-01-01

    A series-hybrid bearing assembly consisting of a conical hydrostatic fluid-film bearing and a ball bearing is described. Computer studies are used to predict friction torque and life characteristics of a 150-millimeter ball bearing. A conical hydrostatic fluid-film bearing is designed for minimum friction and maximum speed reduction of the ball-bearing component of the series-hydrid bearing. At a thrust load of 4000 pounds and speeds corresponding to DN (bearing bore in millimeters times shaft speed in rpm) values of 3 and 4 million, ball-bearing speed may be reduced by 30 percent. This speed reduction corresponds to ball-bearing fatigue life improvement factors of 3.4 at 3 million DN and 5.9 at 4 million DN. An oil flow rate of 18.2 pounds per minute is required to maintain a fluid-film thickness of 0.001 inch in the hydrostatic bearing.

  11. Hybrid bearings for turbopumps and the like

    NASA Technical Reports Server (NTRS)

    Justak, John F. (inventor); Owens, Gregg R. (inventor)

    1994-01-01

    In rocket engines power is usually obtained by burning fuel and oxidizer which are mixed, pressurized, and directed to a combustion chamber by means of turbopumps. Roller bearings are generally used in these turbopumps, but because of bearing demands hydrostatic bearings were proposed. The use of such bearings is quite feasible because during flight hydrostatic lubrication can reduce roller bearing wear. A disadvantage of such proposals is that during startup, acceleration, and shutdown high pressure fluids are not available for hydrostatic bearings. The fluid lubrication film is not always present in bearings of turbopumps. During these periods a second bearing is required to carry the load. This requirement suggests the use of hybrid bearings in rocket engine turbopumps. Such duplex bearings were provided, but when their inner races are keyed to the shaft or journal two of them are required. And such duplex bearings do not wear evenly. A hybrid hydrostatic-rolling element bearing was provided wherein the rolling element bearing is locked on the stationary housing rather than on the rotating journal.

  12. Hydrostatic drive arrangement

    SciTech Connect

    Hoashi, K.; Morita, K.; Matsuda, K.

    1986-04-22

    A hydrostatic drive arrangement is described for a vehicle which consists of: a pair of variable speed hydrostatic transmissions each having a hydraulic pump, a hydraulic motor and a closed loop hydraulic circuit interconnecting the pump and the motor for communicating fluid therebetween; synchronizing valve means interconnected between the hydraulic circuits of the transmissions normally permitting interflow of fluid through first passage means between the hydraulic circuits for synchronizing the output speeds of the transmissions when the fluid pressure in the hydraulic circuits is below a predetermined value, the synchronizing valve means being responsive to fluid pressures in the hydraulic circuits to restrict interflow therebetween through restricted second passage means when the fluid pressure in one of the hydraulic circuits exceeds the predetermined value; a hydraulic charge pump connected with the closed loop hydraulic circuits for replenishing fluid lost from the hydraulic circuits; and selector valve means disposed between the hydraulic charge pump and the synchronizing valve means for selectively communicating the synchronizing valve means normally blocking communication between the synchronizing valve means and the hydraulic charge pump and establishing communication between the synchronizing valve means and the drain thereby permitting interflow of fluid between the hydraulic circuits, and means responsive to a steering operation of the vehicle to establish communication between the synchronizing valve means and the hydraulic charge pump thereby blocking interflow of fluid between the hydraulic circuits.

  13. 46 CFR 64.83 - Hydrostatic test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Hydrostatic test. 64.83 Section 64.83...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...SYSTEMS Periodic Inspections and Tests of MPTs § 64.83 Hydrostatic test. (a) The hydrostatic...

  14. 46 CFR 64.83 - Hydrostatic test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Hydrostatic test. 64.83 Section 64.83...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...SYSTEMS Periodic Inspections and Tests of MPTs § 64.83 Hydrostatic test. (a) The hydrostatic...

  15. 46 CFR 64.83 - Hydrostatic test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Hydrostatic test. 64.83 Section 64.83...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...SYSTEMS Periodic Inspections and Tests of MPTs § 64.83 Hydrostatic test. (a) The hydrostatic...

  16. 46 CFR 64.83 - Hydrostatic test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Hydrostatic test. 64.83 Section 64.83...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...SYSTEMS Periodic Inspections and Tests of MPTs § 64.83 Hydrostatic test. (a) The hydrostatic...

  17. 46 CFR 64.83 - Hydrostatic test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Hydrostatic test. 64.83 Section 64.83...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...SYSTEMS Periodic Inspections and Tests of MPTs § 64.83 Hydrostatic test. (a) The hydrostatic...

  18. Orbit transfer vehicle engine technology program. Task B-6 high speed turbopump bearings

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Bearing types were evaluated for use on the Orbit Transfer Vehicle (OTV) high pressure fuel pump. The high speed, high load, and long bearing life requirements dictated selection of hydrostatic bearings as the logical candidate for this engine. Design and fabrication of a bearing tester to evaluate these cryogenic hydrostatic bearings was then conducted. Detailed analysis, evaluation of bearing materials, and design of the hydrostatic bearings were completed resulting in fabrication of Carbon P5N and Kentanium hydrostatic bearings. Rotordynamic analyses determined the exact bearing geometry chosen. Instrumentation was evaluated and data acquisition methods were determined for monitoring shaft motion up to speeds in excess of 200,000 RPM in a cryogenic atmosphere. Fabrication of all hardware was completed, but assembly and testing was conducted outside of this contract.

  19. Computing Flows In Turbine End Bearings

    NASA Technical Reports Server (NTRS)

    Smith, Tyn S.

    1990-01-01

    Computer program implements mathematical model of flow through turbine and bearings of high-pressure-oxygen turbopump of Space Shuttle main engine. Intended to determine rate of flow and margin before vaporization in these bearings for various types of geometries. Effects of hydrostatic damper and/or back-pressure seal included. Modified for application to other turbomachines and fluids other than oxygen.

  20. Hydrostatic continuously variable transmission

    SciTech Connect

    Hayashi, T.; Saito, M.; Matsuto, T.; Nakajima, Y.; Sakakibara, K.; Yakigaya, N.; Nakamura, K.

    1989-05-09

    A hydrostatic continuously variable transmission is described, comprising: a swashplate type hydraulic pump having a pump swashplate and annularly arranged pump plungers whose suction and discharge strokes are provided by the pump swashplate; a swashplate type hydraulic motor having a motor swashplate and annularly arranged motor plungers whose expansion and shrinkage strokes are provided by the motor swashplate; and a hydraulic closed circuit formed between the hydraulic pump and the hydraulic motor. The transmission has at least one of a relationship that a middle point of a discharge region of the hydraulic pump is angularly delayed at a given angle in a direction of rotation of the hydraulic pump relative to a tilting axis of the pump swashplate and a relationship that a middle point of an expansion region of the hydraulic motor is angularly advanced at a given angle in a direction of rotation of the hydraulic motor relative to a tilting axis of the motor swashplate, wherein the transmission has at least one of a relationship that a suction region of the hydraulic pump is set at an angle larger than that of the discharge region thereof and a relationship that a shrinkage region of the hydraulic motor is set at an angle larger than that of the expansion region of the motor.

  1. The diversity of hydrostatic skeletons.

    PubMed

    Kier, William M

    2012-04-15

    A remarkably diverse group of organisms rely on a hydrostatic skeleton for support, movement, muscular antagonism and the amplification of the force and displacement of muscle contraction. In hydrostatic skeletons, force is transmitted not through rigid skeletal elements but instead by internal pressure. Functioning of these systems depends on the fact that they are essentially constant in volume as they consist of relatively incompressible fluids and tissue. Contraction of muscle and the resulting decrease in one of the dimensions thus results in an increase in another dimension. By actively (with muscle) or passively (with connective tissue) controlling the various dimensions, a wide array of deformations, movements and changes in stiffness can be created. An amazing range of animals and animal structures rely on this form of skeletal support, including anemones and other polyps, the extremely diverse wormlike invertebrates, the tube feet of echinoderms, mammalian and turtle penises, the feet of burrowing bivalves and snails, and the legs of spiders. In addition, there are structures such as the arms and tentacles of cephalopods, the tongue of mammals and the trunk of the elephant that also rely on hydrostatic skeletal support but lack the fluid-filled cavities that characterize this skeletal type. Although we normally consider arthropods to rely on a rigid exoskeleton, a hydrostatic skeleton provides skeletal support immediately following molting and also during the larval stage for many insects. Thus, the majority of animals on earth rely on hydrostatic skeletons. PMID:22442361

  2. Worm Gear With Hydrostatic Engagement

    NASA Technical Reports Server (NTRS)

    Chaiko, Lev I.

    1994-01-01

    In proposed worm-gear transmission, oil pumped at high pressure through meshes between teeth of gear and worm coil. Pressure in oil separates meshing surfaces slightly, and oil reduces friction between surfaces. Conceived for use in drive train between gas-turbine engine and rotor of helicopter. Useful in other applications in which weight critical. Test apparatus simulates and measures some loading conditions of proposed worm gear with hydrostatic engagement.

  3. The Hydrostatic Gas Noncontact Seal

    Microsoft Academic Search

    Tadashi Koga; Takuya Fujita

    1986-01-01

    Hydrostatic gas noncontact seals are becoming more widely used as high-speed shaft seals for gas turbomachinery. Previous work for incompressible flow has been adapted to cover the gas flow dynamics of a hybrid taper\\/flat face seal, and the equivalent annular arrangement.The seal gap stability is discussed, along with various tests to confirm performance. The gas flow characteristics based on analysis

  4. Polar Bears

    NSDL National Science Digital Library

    Mr. Thomas

    2010-09-27

    Use the following websites to answer questions about the rapid disappearance of polar bears in the Arctic region. Polar Bear picture Polar Bear Tracker 1: What region in the world has the fewest polar bears? 2: Using the internet as a resource, provide some reasons as to why this region is suffering from the most polar bear differences? Polar Bears Change Diet 1: Why are polar bears having to change their diets? 2: List some other factors (besides diet) in the ...

  5. Bearing system

    DOEpatents

    Kapich, Davorin D. (Carlsbad, CA)

    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.

  6. ANSYS Modeling of Hydrostatic Stress Effects

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.

    1999-01-01

    Classical metal plasticity theory assumes that hydrostatic pressure has no effect on the yield and postyield behavior of metals. Plasticity textbooks, from the earliest to the most modem, infer that there is no hydrostatic effect on the yielding of metals, and even modem finite element programs direct the user to assume the same. The object of this study is to use the von Mises and Drucker-Prager failure theory constitutive models in the finite element program ANSYS to see how well they model conditions of varying hydrostatic pressure. Data is presented for notched round bar (NRB) and "L" shaped tensile specimens. Similar results from finite element models in ABAQUS are shown for comparison. It is shown that when dealing with geometries having a high hydrostatic stress influence, constitutive models that have a functional dependence on hydrostatic stress are more accurate in predicting material behavior than those that are independent of hydrostatic stress.

  7. PELLISSIER H5 HYDROSTATIC LEVEL

    SciTech Connect

    Imfeld, Hans L.

    2003-05-01

    Conventional spirit leveling using double scale invar rods has been in use at SLAC for some time as the standard method of obtaining very precise height difference information. Typical accuracy of {+-} 100 {micro}m and better can routinely be achieved. Procedures and software have evolved to the point where the method is relatively fast and reliable. However, recent projects such as the Final Focus Test Beam have pushed the requested vertical positioning tolerances for alignment of quadrupoles to the 30 {mu}m level. It is apparent that conventional spirit leveling cannot achieve this level of accuracy. To meet the challenge, the alignment group contracted with Pellissier, Inc. to develop a portable hydrostatic leveling system. The H5 grew out of this development effort and is expected to provide the needed accuracy and ease of use required for such vertical positioning projects. The H5 hydrostatic level is a portable instrument that under ideal operating conditions will provide elevation differences with an accuracy of +/- 5 {mu}m over double leg closed loop surveys. The H5 incorporates several features that eliminate problems common with hydrostatic leveling, primarily errors due to thermal gradients along the fluid tube. It utilizes self-checking software and automatic water level detection to reduce observational errors. Design features also have made the instrument reasonably quick and easy to operate when used on a flat surface. The instrument can be adapted for use in a wide variety of environments by using support fixtures and brackets. The H5 is robust and operators require little training to become proficient in its use. It has been successfully employed on several projects including the FFTB project at SLAC, as well as the Green Bank Telescope project for the NRAO and the SSC project in Texas.

  8. Fault Tolerant Magnetic Bearing Testing and Conical Magnetic Bearing Development for Extreme Temperature Environments

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Clark, Daniel

    2004-01-01

    During the six month tenure of the grant, activities included continued research of hydrostatic bearings as a viable backup-bearing solution for a magnetically levitated shaft system in extreme temperature environments (1000 F), developmental upgrades of the fault-tolerant magnetic bearing rig at the NASA Glenn Research Center, and assisting in the development of a conical magnetic bearing for extreme temperature environments, particularly turbomachinery. It leveraged work from the ongoing Smart Efficient Components (SEC) and the Turbine-Based Combined Cycle (TBCC) program at NASA Glenn Research Center. The effort was useful in providing technology for more efficient and powerful gas turbine engines.

  9. Polar Bear Polar Bear

    NSDL National Science Digital Library

    Kelly Burgess

    2012-09-11

    In this lesson, students will listen for key details in a nonfiction text about polar bears. They will work at completing a graphic organizer with the teacher to help organize their thinking and understanding of key details about a text. They will also complete an independent assignment where they will draw or write two things that they learned about the topic.

  10. Hydrostatic compaction of Microtherm HT.

    SciTech Connect

    Broome, Scott Thomas; Bauer, Stephen J.

    2010-09-01

    Two samples of jacketed Microtherm{reg_sign}HT were hydrostatically pressurized to maximum pressures of 29,000 psi to evaluate both pressure-volume response and change in bulk modulus as a function of density. During testing, each of the two samples exhibited large irreversible compactive volumetric strains with only small increases in pressure; however at volumetric strains of approximately 50%, the Microtherm{reg_sign}HT stiffened noticeably at ever increasing rates. At the maximum pressure of 29,000 psi, the volumetric strains for both samples were approximately 70%. Bulk modulus, as determined from hydrostatic unload/reload loops, increased by more than two-orders of magnitude (from about 4500 psi to over 500,000 psi) from an initial material density of {approx}0.3 g/cc to a final density of {approx}1.1 g/cc. An empirical fit to the density vs. bulk modulus data is K = 492769{rho}{sup 4.6548}, where K is the bulk modulus in psi, and {rho} is the material density in g/cm{sup 3}. The porosity decreased from 88% to {approx}20% indicating that much higher pressures would be required to compact the material fully.

  11. Hydrostatic Effects in a Mechanical Face Seal

    Microsoft Academic Search

    T. G. Doust; A. Parmar

    1986-01-01

    In a mechanical face seal, the total applied load is supported by hydrostatic and hydrodynamic fluid pressures and often by partial contact of the seal faces. Hydrostatic load support is affected by the initial seal interface geometry and the modification of this geometry due to component distortions. A model developed for static (non-rotating) conditions demonstrates effects of face convergence, spring

  12. Magnetic bearings for free-piston Stirling engines

    Microsoft Academic Search

    P. W. Curwen; D. P. Fleming; D. K. Rao; D. S. Wilson

    1992-01-01

    The feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are

  13. Hydrostatic Modeling of Buoyant Plumes

    NASA Astrophysics Data System (ADS)

    Stroman, A.; Dewar, W. K.; Wienders, N.; Deremble, B.

    2014-12-01

    The Deepwater Horizon oil spill in the Gulf of Mexico has led to increased interest in understanding point source convection dynamics. Most of the existing oil plume models use a Lagrangian based approach, which computes integral measures such as plume centerline trajectory and plume radius. However, this approach doesn't account for feedbacks of the buoyant plume on the ambient environment. Instead, we employ an Eulerian based approach to acquire a better understanding of the dynamics of buoyant plumes. We have performed a series of hydrostatic modeling simulations using the MITgcm. Our results show that there is a dynamical response caused by the presence of the buoyant plume, in that there is a modification of the background flow. We find that the buoyant plume becomes baroclinically unstable and sheds eddies at the neutral buoyancy layer. We also explore different scenarios to determine the effect of the buoyancy source and the temperature stratification on the evolution of buoyant plumes.

  14. Experimental response of gas hybrid bearings for high speed oil-free turbomachinery 

    E-print Network

    Wilde, Deborah Anne

    2002-01-01

    conducted on a small rotor supported on three lobed hybrid (hydrostatic/hydrodynamic) rigid gas bearings. The rigid bearings are made up of preloaded 120? lobes with minute feed holes for external pressurization that are fed, for example, by bleed off from...

  15. Foil bearings

    Microsoft Academic Search

    David A. Elrod

    1993-01-01

    The rolling element bearings (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 contact within the bearing 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

  16. Polar Bear

    USGS Publications Warehouse

    Amstrup, S.D.; DeMaster

    1988-01-01

    Polar bears 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 bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.

  17. Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

    SciTech Connect

    Xiao, Jianwei; Du, Jinglian; Wen, Bin, E-mail: wenbin@ysu.edu.cn; Zhang, Xiangyi [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)] [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Melnik, Roderick [M2NeT Lab, Wilfrid Laurier University, Waterloo25, 75 University Ave. West, Ontario, Canada N2L 3C5 (Canada)] [M2NeT Lab, Wilfrid Laurier University, Waterloo25, 75 University Ave. West, Ontario, Canada N2L 3C5 (Canada); Kawazoe, Yoshiyuki [New Industry Creation Hatchery Center, Tohoku University, 6-6-4 Aramaki-aza-Aoba, Aoba-ku, Sendai 980-8579, Japan and Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, 1, Lavyrentyev Avenue, Novosibirsk 630090 (Russian Federation)] [New Industry Creation Hatchery Center, Tohoku University, 6-6-4 Aramaki-aza-Aoba, Aoba-ku, Sendai 980-8579, Japan and Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, 1, Lavyrentyev Avenue, Novosibirsk 630090 (Russian Federation)

    2014-04-28

    Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ?1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode.

  18. Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    1996-01-01

    AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

  19. Polar Bear

    NSDL National Science Digital Library

    2009-01-01

    In this episode of the Podcast of Life, host Ari Daniel Shapiro relates two close calls with polar bears. Listen as Heather Cray recalls how, dumped by a storm on a small Arctic island without a shotgun, she got an unexpected wake-up call. And when researcher Steve Amstrup accidentally crashed through the roof of a polar bear’s den, no one could predict what happened next. Also included is a Learn More section that provides background information on the scientists recorded in the podcast, lessons, images, and cool facts.

  20. Railcar waste transfer system hydrostatic test report

    SciTech Connect

    Ellingson, S.D.

    1997-04-03

    This Acceptance Test Report (ATR) documents for record purposes the field results, acceptance, and approvals of the completed acceptance test per HNF-SD-W417-ATP-001, ''Rail car Waste Transfer System Hydrostatic Test''. The test was completed and approved without any problems or exceptions.

  1. Railcar waste transfer system hydrostatic test

    SciTech Connect

    Ellingson, S.D.

    1997-03-31

    Recent modifications have been performed on the T-Plant Railcar Waste Transfer System, This Acceptance Test Procedure (ATP) has been prepared to demonstrate that identified piping welds and mechanical connections incorporated during the modification are of high integrity and are acceptable for service. This will be achieved by implementation of a hydrostatic leak test.

  2. Food Processing by High Hydrostatic Pressure

    Microsoft Academic Search

    M. F. San Martín; G. V. Barbosa-Cánovas; B. G. Swanson

    2002-01-01

    The use of high hydrostatic pressures (HHP) for food processing is finding increased application within the food industry. One of the advantages of this technology is that because it does not use heat, sensory, and nutritional attributes of the product remain virtually unaffected, thus yielding products with better quality than those processed traditional methods. HHP have the ability to inactivate

  3. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...INSPECTIONS Tests and Inspections of Fired Thermal Fluid Heaters § 61.30-10 Hydrostatic test. All new installations of thermal fluid heaters must be given a hydrostatic...accessible parts under pressure. The thermal fluid may be used as the hydrostatic...

  4. The performance and application of high speed long life LH2 hybrid bearings for reusable rocket engine turbomachinery

    NASA Technical Reports Server (NTRS)

    Hannum, N. P.; Nielson, C. E.

    1983-01-01

    Data are presented for two different experimental programs which were conducted to investigate the characteristics of a hybrid (hydrostatic/ball) bearing operating in liquid hydrogen. The same bearing design was used in both programs. Analytical predictions were made of the bearing characteristics and are compared with the experimental results when possible. The first program used a bearing tester to determine the steady state, transient, and cyclic life characteristics of the bearing over a wide range of operating conditions. The second program demonstrated the feasibility of applying hybrid bearings to an actual high speed turbopump by retrofitting and then testing an existing liquid hydrogen turbopump with the bearings.

  5. Bobbie Bear

    NSDL National Science Digital Library

    Illuminations National Council of Teachers of Mathematics

    2009-03-06

    Using a virtual manipulative, children construct combinations of different colored shirts and pants to help Bobbie Bear, who is planning a vacation and wants to know how many different outfits he will be able to make from these combinations.

  6. Foil bearings

    NASA Technical Reports Server (NTRS)

    Elrod, David A.

    1993-01-01

    The rolling element bearings (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 contact within the bearing 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 bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (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 bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, 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.

  7. Parameter identification of a rotor supported in a pressurized bearing lubricated with water

    NASA Technical Reports Server (NTRS)

    Grant, John W.; Muszynska, Agnes; Bently, Donald E.

    1994-01-01

    A rig for testing an externally pressurized (hydrostatic), water-lubricated bearing was developed. Applying a nonsynchronous sweep frequency, rotating perturbation force with a constant amplitude as an input, rotor vibration response data was acquired in Bode and Dynamic Stiffness formats. Using this data, the parameters of the rotor/bearing system were identified. The rotor/bearing model was represented by the generalized (modal) parameters of the first lateral mode, with the rotational character of the fluid force taken into account.

  8. Dynamic Whirl in Well-Aligned, Liquid-Lubricated End-Face Seals with Hydrostatic Tilt Instability

    Microsoft Academic Search

    R. Metcalfe

    1982-01-01

    Dynamic whirl in well-aligned, fully liquid-lubricated end-face seals is analyzed and tested. As with whirl of journal bearings, seal whirl occurs under lightly loaded conditions, in this case controlled by balance ratio.The two common seal arrangements are analyzed, including effects of the elastomer secondary sealing elements. Whirling is found to be induced by hydrostatic tilt instability and controlled hydrodynamically. Elastomer

  9. Dynamic whirl in well-aligned, liquid-lubricated end-face seals with hydrostatic tilt instability

    Microsoft Academic Search

    Metcalfe

    1980-01-01

    Dynamic whirl in well-aligned, fully liquid-lubricated end-face seals is analyzed and tested. As with whirl of journal bearings, seal whirl occurs under lightly loaded conditions, in this case controlled by balance ratio. The two common seal arrangements are analyzed, including effects of the elastomer secondary sealing elements. Whirling is found to be induced by hydrostatic tilt instability and controlled hydrodynamically.

  10. Cave Bear

    NSDL National Science Digital Library

    American Association for the Advancement of Science (; )

    2005-08-15

    Decoding an ancient cave bear. A two-ton, thirteen-foot cave bear, extinct for ten thousand years, has just experienced a rebirth of sorts. From a tooth and a bone, scientists have recovered its entire genetic code.Eddy Rubin, director of the Department of Energy's Joint Genome Institute, says finding genuine cave bear DNA was like looking for a needle in a haystack. The haystack were all the other organisms that were living in the bones and in the tooth of this ancient creature. And the needle was the little bit of the ancient creature's genome DNA, or genes.They used state-of-the-art computer technology to separate the bear genes from the clutter. Jurassic Park fans should note that they can't clone a new cave bear, nor can they recover DNA from creatures as old as the dinosaurs. But they do hope to reconstruct the genetic code of Neanderthals, our closest non-human relatives, to better understand how our own species evolved. This resource contains detailed text description of the research as well as likes for further inquiry.

  11. A Multipurpose Device for Some Hydrostatics Questions

    Microsoft Academic Search

    Salvatore Ganci

    2008-01-01

    A number of well-known hydrostatics problems dealing with Archimedes' principle concern a loaded boat floating in a pool.1-4 Examples of this sort of problem include: 1. (a) If a stone is thrown overboard from a boat floating in a pool, does the water level in the pool rise, fall, or remain unchanged? (b) If a hole is made in the

  12. Hydrostatic Adjustment in Vertically Stratified Atmospheres

    NASA Technical Reports Server (NTRS)

    Duffy, Dean G.

    2000-01-01

    Hydrostatic adjustment due to diabatic heat in two nonisothermal atmospheres is examined. In the first case the temperature stratification is continuous; in the second case the atmosphere is composed of a warm, isothermal troposphere and a colder, isothermal semi-infinitely deep stratosphere.In both cases hydrostatic adjustment, to a good approximation, follows the pattern found in the Lamb problem (semi-infinitely deep. isothermal atmosphere): Initially we have acoustic waves with the kinetic energy increasing or decreasing at the expense of available elastic energy. After this initial period the acoustic waves evolve into acoustic-gravity waves with the kinetic, available potential and available elastic energies interacting with each other. Relaxation to hydrostatic balance occurs within a few oscillations. Stratification in an atmosphere with a continuous temperature profile affects primarily the shape and amplitude of the disturbances. In the two-layer atmosphere, a certain amount of energy is trapped in the tropospheric waveguide as disturbances reflect off the tropopause and back into the troposphere. With each internal reflection a portion of this trapped energy escapes and radiates to infinity.

  13. Bear Bones

    NSDL National Science Digital Library

    Science Update

    2004-03-08

    An estimated ten million Americans have osteoporosis, an age-related disease in which the bones gradually become brittle and weak. Now, scientists are looking to animals for clues on how to combat this condition. This resource describes the study of sustaining bone strength of hibernating bears.

  14. Seismic evaluation of a large nuclear pump bearing using non-linear dynamic analysis

    SciTech Connect

    Huber, K.A.; Hugins, M.S.

    1983-01-01

    Hydrostatic bearings of a large vertical pump using sodium as the lubricant were critically examined to determine their ability to withstand seismic loads. Initial linear dynamics analyses predicted journal displacements to exceed bearing clearance by a ratio of 3:1. Equivalent time-history excitations were then developed from the response spectra to determine the number, magnitude, and duration of the bearing impact loads. Predicted loads were further reduced by 50% by modeling non-linear bearing characteristics normally present but not generally included in conventional linear analyses. Results are presented of the comprehensive design evaluation performed, based on these non-linear predictions, that assess stress, wear, and fatigue to demonstrate hydrostatic bearing integrity.

  15. Compression of ?-cristobalite under different hydrostatic conditions

    NASA Astrophysics Data System (ADS)

    Cernok, Ana; Marquardt, Katharina; Bykova, Elena; Liermann, Hanns-Peter; Dubrovinsky, Leonid

    2015-04-01

    The response of ?-cristobalite to high-pressure has been a subject of numerous experimental and theoretical studies for more than two decades. The results indicated prolific polymorphism under high pressures, yet no consensus has emerged on what is the sequence of these pressure-induced transformations. In particular, the structure of the high-pressure polymorph that appears above ~10 GPa (hereafter cristobalite X-I), which is believed to be a direct link between the low-pressure (silicon in SiO4 tetrahedra) and the high-pressure (SiO6 octahedra) forms of silica remained elusive. This study examined the response of ?-cristobalite when compressed at different levels of hydrostaticity, with the special focus on formation and stability of cristobalite X-I. The structural behavior of cristobalite under pressure was investigated up to ~80 GPa and at ambient temperature. We investigated behavior of single crystals and powders, in either (quasy)-hydrostatic or non-hydrostatic environment. In situ high pressure transformation path and structural behavior was studied by means of Raman spectroscopy and synchrotron X-ray diffraction (XRD). The samples recovered after pressure release were additionally investigated by transmission electron microscopy (TEM). Low- or ?-cristobalite responds differently to high pressure depending on the degree of the hydrostaticity. The highest attainable hydrostaticity preserves the initial structure of cristobalite at least up to ~15 GPa. When the crystal experiences even slight stresses during an experiment, transformation sequence leads to cristobalite X-I - a monoclinic polymorph with silicon in octahedral coordination. This polymorph belongs to the family of the high-pressure silica phases that are comprised of distorted close-packed array of oxygen ions in which silicon atoms fully or partially occupy octahedral sites. The reflections collected on a single crystal at ~11 GPa can be indexed by a monoclinic unit cell a=6.658(9) Å, b=4.1077(6) Å, c=6.8947(11) Å, ?=98.31(4)° , V=186.6(3) Å3 (Z=8 and ?=4.28 g/cm3). The structure was solved in P 21/n space group and refined at this pressure with the final R1 indices of 9% for 209 unique reflections. The increase in coordination number of silicon from cristobalite to its six-fold coordinated polymorph does not require any thermal activation; however the high-pressure polymorph cannot be preserved at ambient conditions. No other silica polymorph was found to transform to an octahedra-based structure on cold compression at such low pressures (~11 GPa). This structure could be accommodated in (quasi)-hydrostatic environment where temperature is not sufficient to form stishovite. In non-hydrostatic conditions in the presence of uniaxial stress, cristobalite eventually transforms to seifertite-like SiO2, which is quenchable. Presence of seifertite might not always require the minimum shock pressures equal to that of thermodynamic equilibrium (~80 GPa) as it can be clearly formed at much lower pressures in an environment of uniaxial compression (e.g. dynamic event).

  16. System for testing bearings

    NASA Technical Reports Server (NTRS)

    Gibson, John C. (inventor)

    1993-01-01

    Disclosed here is a system for testing bearings wherein a pair of spaced bearings provides support for a shaft on which is mounted a bearing to be tested, this bearing being mounted in a bearing holder spaced from and in alignment with the pair of bearings. The bearing holder is provided with an annular collar positioned in an opening in the bearing holder for holding the bearing to be tested. A screw threaded through the bearing holder into engagement with the annular collar can be turned to force the collar radially out of alignment with the pair of bearings to apply a radial load to the bearing.

  17. Dilatonic Equation of Hydrostatic Equilibrium and Neutron Star Structure

    E-print Network

    S. H. Hendi; G. H. Bordbar; B. Eslam Panah; M. Najafi

    2015-06-30

    In this paper, we present a new hydrostatic equilibrium equation related to dilaton gravity. We consider a spherical symmetric metric to obtain the hydrostatic equilibrium equation of stars in $4$-dimensions, and generalize TOV equation to the case of regarding a dilaton field. Then, we calculate the structure properties of neutron star using our obtained hydrostatic equilibrium equation employing the modern equations of state of neutron star matter derived from microscopic calculations. We show that the maximum mass of neutron star depends on the parameters of dilaton field and cosmological constant. In other words, by setting the parameters of new hydrostatic equilibrium equation, we calculate the maximum mass of neutron star.

  18. Hydrostatic piezoelectric effect in lead titanate ceramics

    SciTech Connect

    Lopatin, S.S.; Lupeiko, T.G.; Zvyagintsev, B.I. [Rostov State Univ. (Russian Federation)] [and others

    1994-10-01

    The hydrostatic piezoelectric characteristics of Pb{sub 0.955-x}Sm{sub 2x/3}Bi{sub 0.03}Ti{sub 0.98}Mn{sub 0.02}O{sub 3} ceramics were studied. Within the range of at least 25 to 70 degrees C and at high hydrostaic and uniaxial pressures of 0.1-60 MPa, a high stability of the no-load piezoelectric voltage coefficient for the material with x=0.09-0.15 was found.

  19. 78 FR 70324 - Thy Hydrostatic Testing Provision of the Portable Fire Extinguishers Standard; Extension of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-25

    ...Hydrostatic Testing Provision of the Portable Fire Extinguishers Standard; Extension of the...Hydrostatic Testing provision of the Portable Fire Extinguishers Standard for General Industry...Hydrostatic Testing Provision of the Portable Fire Extinguishers Standard are necessary...

  20. Characterization and measurement of hybrid gas journal bearings

    NASA Astrophysics Data System (ADS)

    Lawrence, Tom Marquis

    This thesis concentrates on the study of hybrid gas journal bearings (bearings with externally pressurized mass addition). It differs from most work in that it goes back to "basics" to explore the hydrodynamic phenomena in the bearing gap. The thesis compares geometrically identical bearings with 2 configurations of external pressurization, porous liners where mass-addition compensation is varied by varying the liner's permeability, and bushings with 2 rows of 6 feedholes where the mass-addition compensation is varied by the feedhole diameter. Experimentally, prototype bearings with mass-addition compensation that spans 2 orders of magnitude with differing clearances are built and their aerostatic properties and mass addition characteristics are thoroughly tested. The fundamental equations for compressible, laminar, Poiseuille flow are used to suggest how the mass flow "compensation" should be mathematically modeled. This is back-checked against the experimental mass flow measurements and is used to determine a mass-addition compensation parameter (called Kmeas) for each prototype bushing. In so doing, the methodology of modeling and measuring the mass addition in a hybrid gas bearing is re-examined and an innovative, practical, and simple method is found that makes it possible to make an "apples-to-apples" comparison between different configurations of external pressurization. This mass addition model is used in conjunction with the Reynolds equation to perform theory-based numerical analysis of virtual hybrid gas journal bearings (CFD experiments). The first CFD experiments performed use virtual bearings modeled to be identical to the experimental prototypes and replicate the experimental work. The results are compared and the CFD model is validated. The ontological significance of appropriate dimensionless similitude parameters is re-examined and a, previously lacking, complete set of similitude factors is found for hybrid bearings. A new practical method is developed to study in unprecedented detail the aerostatic component of the hybrid bearings. It is used to definitively compare the feedhole bearings to the porous liner bearings. The hydrostatic bearing efficiency (HBE) is defined and it is determined that the maximum achievable hydrostatic bearing efficiency (MAHBE) is determined solely by the bearing's mass addition configuration. The MAHBE of the porous liner bearings is determined to be over 5 times that of the feedhole bearings. The method also presents a means to tune the Kmeas to the clearance to achieve the MAHBE as well as giving a complete mapping of the hitherto misunderstood complex shapes of aerostatic load versus radial deflection curves. This method also rediscovers the obscure phenomenon of static instability which is called in this thesis the "near surface effect" and appears to be the first work to present a practical method to predict the range of static instability and quantify its resultant stiffness fall-off. It determines that porous liner type bearings are not subject to the phenomenon which appears for feedhole type bearings when the clearance exceeds a critical value relative to its mass-addition compensation. The standing pressure waves of hydrostatic and hybrid bearings with the 2 configurations of external pressurization as well as a geometrically identical hydrodynamic bearing are studied in detail under the methodology of the "CFD microscope". This method is used to characterize and identify the development, growth, and movement of the pressure wave extrema with increased hydrodynamic action (either increasing speed or increasing eccentricity). This method is also used to determine the "cause" of the "near surface effect". A gedanken experiment is performed based on these results which indicates that a bearing with a "stronger aerostatic strength" component should be more stable than one with a low aerostatic strength component. Numerical instability "speed limits" are found that are also relate

  1. Hydrostatic tank gauges accurately measure mass, volume, and level

    Microsoft Academic Search

    Berto

    1990-01-01

    Hydrostatic tank gauging (HTG) systems accurately measure the hydrostatic pressure of material in atmospheric and pressurized storage tanks, and use the results to determine the mass, liquid density, volume, and level of the material in the tank. The systems are suitable for automatic tank-gauging applications. Detailed specifications describing a new method for measuring the mass, volume, or level of the

  2. Hydrostatic meniscus between two eccentric circular cylinders.

    PubMed

    Pozrikidis, C

    2010-09-01

    A numerical method is implemented for computing the shape of a three-dimensional hydrostatic meniscus extending between two arbitrary closed contact lines under the restriction that the projections of the contact lines in a horizontal plane are eccentric circles. In a physical realization, the contact lines are attached to vertical circular cylinders, spherical particles or containers. The Laplace-Young equation determining the meniscus shape is solved in bipolar coordinates generated by conformal mapping using a finite-difference method, and the capillary force and torque exerted on the cylinders are evaluated. Numerical results are presented for a meniscus extending between two circular horizontal contact lines. The horizontal component of the capillary force at each contact line is found to increase monotonically with the cylinder center offset, favoring the concentric configuration. PMID:20609847

  3. Magnetic bearings for free-piston Stirling engines

    NASA Technical Reports Server (NTRS)

    Curwen, P. W.; Fleming, D. P.; Rao, D. K.; Wilson, D. S.

    1992-01-01

    The feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.

  4. Magnetic bearings for free-piston Stirling engines

    NASA Astrophysics Data System (ADS)

    Curwen, P. W.; Flemig, D. P.; Rao, D. K.; Wilson, D. S.

    The feasibility and efficiency of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficieny points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.

  5. Motor bearing fluting

    Microsoft Academic Search

    J. A. Lawson

    1993-01-01

    Electrical motor bearing fluting has been defined as damage due to electrical current discharge through a motor bearing. Bearing race metal is electroplated onto the bearing balls. Close inspection reveals microscopic pits on bearing ball and race surfaces. A DC motor frame was completely isolated from ground except by a single grounding conductor with applied armature and field voltage. No

  6. Hydrostatic Stress Effect On the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2002-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has no effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of notched geometries. New experiments and nonlinear finite element analyses (FEA) of Inconel 100 (IN 100) equal-arm bend and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions was performed. In all test cases, the von Mises constitutive model, which is independent of hydrostatic pressure, overestimated the load for a given displacement or strain. Considering the failure displacements or strains, the Drucker-Prager FEMs predicted loads that were 3% to 5% lower than the von Mises values. For the failure loads, the Drucker Prager FEMs predicted strains that were 20% to 35% greater than the von Mises values. The Drucker-Prager yield function seems to more accurately predict the overall specimen response of geometries with significant internal hydrostatic stress influence.

  7. Measurement of hydrostatic pressures during simulated post cementation.

    PubMed

    Morando, G; Leupold, R J; Meiers, J C

    1995-12-01

    Tooth sensitivity and fracture after cementation of posts for endodontically treated teeth have been a problem. This investigation developed an in vitro method of measuring intraradicular hydrostatic pressures created during simulated post cementation. The testing apparatus consisted of a pressure transducer and brush recorder connected to precision milled post spaces in a Plexiglas block. Cast post and cores were fabricated and cemented with three different luting agents: resinous cement, glass ionomer cement, and zinc phosphate cement. Mean hydrostatic pressures (psi) recorded during post cementation were zinc phosphate cement, 22.67; resinous cement, 19.77; and glass ionomer cement, 17.66. Zinc phosphate cement created substantially greater hydrostatic pressures than either the resinous or glass ionomer cements. This in vitro system was capable of discriminating intraradicular hydrostatic pressures among different classes of luting agents. PMID:8778381

  8. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Hydrostatic test. 61.30-10 Section 61.30-10...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PERIODIC TESTS AND INSPECTIONS Tests and Inspections of Fired Thermal...

  9. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Hydrostatic test. 61.30-10 Section 61.30-10...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PERIODIC TESTS AND INSPECTIONS Tests and Inspections of Fired Thermal...

  10. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Hydrostatic test. 61.30-10 Section 61.30-10...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PERIODIC TESTS AND INSPECTIONS Tests and Inspections of Fired Thermal...

  11. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Hydrostatic test. 61.30-10 Section 61.30-10...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PERIODIC TESTS AND INSPECTIONS Tests and Inspections of Fired Thermal...

  12. Hydrostatic pressure and aquatic plant growth: a laboratory study

    Microsoft Academic Search

    H. M. Dale

    1984-01-01

    A method was tested for growing aquatic vascular plants at elevated hydrostatic pressure so that the influence of other factors\\u000a will not mask the specific plant-pressure interaction.\\u000a \\u000a Eighteen species of submersed vascular plants, belonging to twelve families and several distinct growth forms, were subjected\\u000a to series of hydrostatic pressures including those well in excess of those encountered by the species

  13. Hydrostatic pressure influences HIF-2 alpha expression in chondrocytes.

    PubMed

    Inoue, Hiroaki; Arai, Yuji; Kishida, Tsunao; Terauchi, Ryu; Honjo, Kuniaki; Nakagawa, Shuji; Tsuchida, Shinji; Matsuki, Tomohiro; Ueshima, Keiichirou; Fujiwara, Hiroyoshi; Mazda, Osam; Kubo, Toshikazu

    2015-01-01

    Hypoxia-inducible factor (HIF)-2? is considered to play a major role in the progression of osteoarthritis. Recently, it was reported that pressure amplitude influences HIF-2? expression in murine endothelial cells. We examined whether hydrostatic pressure is involved in expression of HIF-2? in articular chondrocytes. Chondrocytes were cultured and stimulated by inflammation or hydrostatic pressure of 0, 5, 10, or 50 MPa. After stimulation, heat shock protein (HSP) 70, HIF-2?, nuclear factor kappa B (NF-?B), matrix metalloproteinase (MMP)-13, MMP-3, and vascular endothelial growth factor (VEGF) gene expression were evaluated. The levels of all gene expression were increased by inflammatory stress. When chondrocytes were exposed to a hydrostatic pressure of 5 MPa, HIF-2?, MMP-13, and MMP-3 gene expression increased significantly although those of HSP70 and NF-?B were not significantly different from the control group. In contrast, HIF-2? gene expression did not increase under a hydrostatic pressure of 50 MPa although HSP70 and NF-?B expression increased significantly compared to control. We considered that hydrostatic pressure of 5 MPa could regulate HIF-2? independent of NF-?B, because the level of HIF-2? gene expression increased significantly without upregulation of NF-?B expression at 5 MPa. Hydrostatic pressure may influence cartilage degeneration, inducing MMP-13 and MMP-3 expression through HIF-2?. PMID:25569085

  14. Hydrostatic Pressure Influences HIF-2 Alpha Expression in Chondrocytes

    PubMed Central

    Inoue, Hiroaki; Arai, Yuji; Kishida, Tsunao; Terauchi, Ryu; Honjo, Kuniaki; Nakagawa, Shuji; Tsuchida, Shinji; Matsuki, Tomohiro; Ueshima, Keiichirou; Fujiwara, Hiroyoshi; Mazda, Osam; Kubo, Toshikazu

    2015-01-01

    Hypoxia-inducible factor (HIF)-2? is considered to play a major role in the progression of osteoarthritis. Recently, it was reported that pressure amplitude influences HIF-2? expression in murine endothelial cells. We examined whether hydrostatic pressure is involved in expression of HIF-2? in articular chondrocytes. Chondrocytes were cultured and stimulated by inflammation or hydrostatic pressure of 0, 5, 10, or 50 MPa. After stimulation, heat shock protein (HSP) 70, HIF-2?, nuclear factor kappa B (NF-?B), matrix metalloproteinase (MMP)-13, MMP-3, and vascular endothelial growth factor (VEGF) gene expression were evaluated. The levels of all gene expression were increased by inflammatory stress. When chondrocytes were exposed to a hydrostatic pressure of 5 MPa, HIF-2?, MMP-13, and MMP-3 gene expression increased significantly although those of HSP70 and NF-?B were not significantly different from the control group. In contrast, HIF-2? gene expression did not increase under a hydrostatic pressure of 50 MPa although HSP70 and NF-?B expression increased significantly compared to control. We considered that hydrostatic pressure of 5 MPa could regulate HIF-2? independent of NF-?B, because the level of HIF-2? gene expression increased significantly without upregulation of NF-?B expression at 5 MPa. Hydrostatic pressure may influence cartilage degeneration, inducing MMP-13 and MMP-3 expression through HIF-2?. PMID:25569085

  15. Angled Injection: Turbulent Flow Hybrid Bearings Comparison to Test Results

    NASA Technical Reports Server (NTRS)

    SanAndres, Luis; Childs, Dara

    1997-01-01

    Hydrostatic/hydrodynamic (hybrid) journal bearings handling process liquids have limited dynamic stability characteristics and their application as support elements to high speed flexible rotating systems is severely restricted. Measurements on water hybrid bearings with angled orifice injection have demonstrated improved rotordynamic performance with virtual elimination of cross-coupled stiffness coefficients and null or negative whirl frequency ratios. A bulk-flow model for prediction of the static performance and force coefficients of hybrid bearings with angled orifice injection is advanced. The analysis reveals that the fluid momentum exchange at the orifice discharge produces a pressure rise in the hydrostatic recess retards the shear flow induced by journal rotation, and thus, reduces cross-coupling forces. The predictions from the model are compared with experimental measurements for a 45 deg. angled orifice injection, 5 recess water hybrid bearing operating at 10.2, 17.4, and 24.6 krpm and with supply pressures of 4, 5.5, and 7 MPa. The correlations include recess pressures, flow rates, and rotordynamic force coefficients at the journal centered position.

  16. AURALISATION OF ROLLING BEARINGS

    Microsoft Academic Search

    Michael Vorländer; João Henrique; Diniz Guimarães

    Monitoring the operating conditions of rolling bearings and prediction of the remaining lifetime of bearings is one of the most crucial tasks in machine diagnosis. This work presents the results of the auralization of structure-borne sound in bearings and the transmission in machines. These signals correspond to the vibration measured on the machine's housing generated by cylindrical and ball bearings

  17. Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Anderson, W. J.

    1983-01-01

    Rolling element bearings are a precision, yet simple, machine element of great utility. A brief history of rolling element bearings is reviewed and the type of rolling element bearings, 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 bearings, loaded but unlubricated rolling element bearings and loaded and lubricated rolling element bearings are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element bearings.

  18. Introduction to ball bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    The purpose of a ball bearing 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 bearings) the purpose can be expanded to include rotational freedom with practically no wear in the bearing. This condition can be achieved by separating the bearing parts with a coherent film of fluid known as an elastohydrodynamic film. This film can be maintained not only when the bearing carries the load on a shaft, but also when the bearing is preloaded to position the shaft to within micro- or nano-inch accuracy and stability. Background information on ball bearings is provided, different types of ball bearings and their geometry and kinematics are defined, bearing materials, manufacturing processes, and separators are discussed. It is assumed, for the purposes of analysis, that the bearing carries no load.

  19. High efficiency magnetic bearings

    NASA Technical Reports Server (NTRS)

    Studer, Philip A.; Jayaraman, Chaitanya P.; Anand, Davinder K.; Kirk, James A.

    1993-01-01

    Research activities concerning high efficiency permanent magnet plus electromagnet (PM/EM) pancake magnetic bearings at the University of Maryland are reported. A description of the construction and working of the magnetic bearing is provided. Next, parameters needed to describe the bearing are explained. Then, methods developed for the design and testing of magnetic bearings are summarized. Finally, a new magnetic bearing which allows active torque control in the off axes directions is discussed.

  20. Notes 12. (a) Annular pressure (damper) seals, and (b) Hydrostatic journal bearings 

    E-print Network

    San Andres, Luis

    2009-01-01

    Seals Seals in a Multistage Centrifugal Pump or Compressor Radial seals (annular, labyrinth or honeycomb) separate regions of high pressure and low pressure and their principal function is to minimize the leakage (secondary flow); thus improving.../c) Compressors and 1st Mode Shapes Due to their relative...

  1. Wheel drives for large telescopes: save the cost and keep the performance over hydrostatic bearings

    NASA Astrophysics Data System (ADS)

    Campbell, Marvin F.

    2014-07-01

    The use of steel wheels on steel tracks has been around since steel was invented, and before that it was iron wheels on iron tracks. Not to be made obsolete by the passage of time, this approach for moving large objects is still valid, even optimal, but the detailed techniques for achieving high performance and long life have been much improved. The use of wheel-and-track designs has been very popular in radio astronomy for the largest of the large radio telescopes (RT), including such notables as the 305m Arecibo RT, the 100m telescopes at Effelsberg, Germany (at 3600 tonnes) and the Robert C. Byrd, Greenbank Telescope (GBT, 7600 tonnes) at Greenbank, West Virginia. Of course, the 76m Lovell Telescope at Jodrell Bank is the grandfather of all large aperture radio telescopes that use wheel drives. Smaller sizes include NRAO's Very Long Baseline Array (VLBA) telescopes at 25m and others. Wheel drives have also been used on large radars of significance such as the 410 tonne Ground Based Radar-Prototype (GBR-P) and the 150 foot (45.7m) Altair Radar, and the 2130 tonne Sea Based X-Band Radar (SBX). There are also many examples of wheel driven communications antennas of 18 meters and larger. All of these instruments have one thing in common: they all use steel wheels that run in a circle on one or more flat, level, steel tracks. This paper covers issues related to designing for wheel driven systems. The intent is for managing motion to sub arc-second levels, and for this purpose it is primary for the designer to manage measurement and alignment errors, and to establish repeatability through dimensional control, structural and drive stiffness management, adjustability and error management. In a practical sense, there are very few, if any, fabricators that can machine structural and drive components to sufficiently small decimal places to matter. In fact, coming within 2-3 orders of magnitude of the precision needed is about the best that can be expected. Further, it is incumbent on the design team to develop the servo control system features, correction algorithms and structural features in concert with each other. Telescope designers are generally adept at many of these practices, so the scope of this paper is not that, but is limited to those items that pertain to a precision wheel driven system.

  2. Theory for hydrostatic gas journal bearings for micro-electro-mechanical systems

    E-print Network

    Liu, Lixian, Ph. D. Massachusetts Institute of Technology

    2005-01-01

    The goal of the MIT micro-engine project is to develop high-speed rotating Power MEMS (Micro-Electro-Mechanical Systems) using computer chip fabrication technologies. To produce high power (10-50 W) in a small volume (less ...

  3. Orbital transfer vehicle oxygen turbopump technology. Volume 1: Design, fabrication, and hydrostatic bearing testing

    NASA Technical Reports Server (NTRS)

    Buckmann, P. S.; Hayden, W. R.; Lorenc, S. A.; Sabiers, R. L.; Shimp, N. R.

    1990-01-01

    The design, fabrication, and initial testing of a rocket engine turbopump (TPA) for the delivery of high pressure liquid oxygen using hot oxygen for the turbine drive fluid are described. This TPA is basic to the dual expander engine which uses both oxygen and hydrogen as working fluids. Separate tasks addressed the key issue of materials for this TPA. All materials selections emphasized compatibility with hot oxygen. The OX TPA design uses a two-stage centrifugal pump driven by a single-stage axial turbine on a common shaft. The design includes ports for three shaft displacement/speed sensors, various temperature measurements, and accelerometers.

  4. Orbital transfer vehicle oxygen turbopump technology. Volume 1: Design, fabrication, and hydrostatic bearing testing. Final Report

    SciTech Connect

    Buckmann, P.S.; Hayden, W.R.; Lorenc, S.A.; Sabiers, R.L.; Shimp, N.R.

    1990-12-01

    The design, fabrication, and initial testing of a rocket engine turbopump (TPA) for the delivery of high pressure liquid oxygen using hot oxygen for the turbine drive fluid are described. This TPA is basic to the dual expander engine which uses both oxygen and hydrogen as working fluids. Separate tasks addressed the key issue of materials for this TPA. All materials selections emphasized compatibility with hot oxygen. The OX TPA design uses a two-stage centrifugal pump driven by a single-stage axial turbine on a common shaft. The design includes ports for three shaft displacement/speed sensors, various temperature measurements, and accelerometers.

  5. Hydrostatic pressure mimics gravitational pressure in characean cells

    NASA Technical Reports Server (NTRS)

    Staves, M. P.; Wayne, R.; Leopold, A. C.

    1992-01-01

    Hydrostatic pressure applied to one end of a horizontal Chara cell induces a polarity of cytoplasmic streaming, thus mimicking the effect of gravity. A positive hydrostatic pressure induces a more rapid streaming away from the applied pressure and a slower streaming toward the applied pressure. In contrast, a negative pressure induces a more rapid streaming toward and a slower streaming away from the applied pressure. Both the hydrostatic pressure-induced and gravity-induced polarity of cytoplasmic streaming respond identically to cell ligation, UV microbeam irradiation, external Ca2+ concentrations, osmotic pressure, neutral red, TEA Cl-, and the Ca2+ channel blockers nifedipine and LaCl3. In addition, hydrostatic pressure applied to the bottom of a vertically-oriented cell can abolish and even reverse the gravity-induced polarity of cytoplasmic streaming. These data indicate that both gravity and hydrostatic pressure act at the same point of the signal transduction chain leading to the induction of a polarity of cytoplasmic streaming and support the hypothesis that characean cells respond to gravity by sensing a gravity-induced pressure differential between the cell ends.

  6. Hydrostatic Water Level Systems At Homestake DUSEL

    NASA Astrophysics Data System (ADS)

    Stetler, L. D.; Volk, J. T.

    2009-12-01

    Two arrays of Fermilab-style hydrostatic water level sensors have been installed in the former Homestake gold mine in Lead, SD, the site of the new Deep Underground Science and Engineering Laboratory (DUSEL). Sensors were constructed at Fermilab from 8.5 cm diameter PVC pipe (housing) that was sealed on the ends and fit with a proximity sensor. The instrument have a height of 10 cm. Two ports in each sensor housing provide for connectivity, the upper port for air and the bottom port for water. Multiple instruments connected in series provide a precise water level and differences in readings between successive sensors provide for ground tilt to be resolved. Sensor resolution is 5 ?m per count and has a range of approximately 1.25 cm. Data output from each sensor is relayed to a Fermilab-constructed readout card that also has temperature/relative humidity and barometric pressure sensors connected. All data are relayed out of the mine by fiber optic cable and can be recorded by Ethernet at remote locations. The current arrays have been installed on the 2000-ft level (610 m) and consist of six instruments in each array. Three sensors were placed in a N-S oriented drift and three in an E-W oriented drift. Using this orientation, it is anticipated that tilt direction may be resolved in addition to overall tilt magnitude. To date the data show passage of earth tides and frequency analysis has revealed five components to this signal, three associated with the semi-diurnal (~12.4 hr) and two with the diurnal (~24.9 hr) tides. Currently, installation methods are being analyzed between concrete pillar and rib-mounting using the existing setup on the 2000-ft level. Using these results, two additional arrays of Fermilab instruments will be installed on the 4550-ft and 4850-ft levels (1387 and 1478 m, respectively). In addition to Fermilab instruments, several high resolution Budker tiltmeters (1 ?m resolution) will be installed in the mine workings in the near future, some correlated to Fermilab instruments (for comparative analysis) and others in independent arrays. All tiltmeter data will be analyzed with water reduction data (currently being collected from the #6 winze as the mine is dewatered) and data from rock stress/fracture experiments to document net ground settling due to dewatering, potential collapse of stope areas and renewed excavation activities.

  7. Hydrostatic equilibrium and deceleration of the earth's rotation

    NASA Astrophysics Data System (ADS)

    Bursa, M.

    1984-12-01

    The discrepancies between the polar flattening (alpha) and deceleration of the earth predicted by hydrostatic theory (e.g., O'Keefe, 1966) and the measured alpha and deceleration are investigated analytically. It is pointed out that the alpha difference is of the order of alpha squared; i.e., of the accuracy of the hydrostatic model. It is found that the deceleration difference cannot be explained by the alpha discrepancy but could be accounted for by a small decrease of the maximum principal moment of inertia or by a decrease in alpha with time as d(alpha)/dt = -3.5 x 10 to the -9th/cy. The decrease in the absolute value of the second zonal Stokes constant observed in Lageos data by Yoder et al. (1983) is attributed to a tendency to renew (rather than deviate from) the previous hydrostatic equilibrium state.

  8. Tracking Polar Bears

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2008-01-17

    In this interactive activity adapted from the USGS Alaska Science Center, track the movements of a polar bear as it migrates across the changing Arctic sea ice and compare the paths of four different polar bears.

  9. Accurate pressure gradient calculations in hydrostatic atmospheric models

    NASA Technical Reports Server (NTRS)

    Carroll, John J.; Mendez-Nunez, Luis R.; Tanrikulu, Saffet

    1987-01-01

    A method for the accurate calculation of the horizontal pressure gradient acceleration in hydrostatic atmospheric models is presented which is especially useful in situations where the isothermal surfaces are not parallel to the vertical coordinate surfaces. The present method is shown to be exact if the potential temperature lapse rate is constant between the vertical pressure integration limits. The technique is applied to both the integration of the hydrostatic equation and the computation of the slope correction term in the horizontal pressure gradient. A fixed vertical grid and a dynamic grid defined by the significant levels in the vertical temperature distribution are employed.

  10. A model for hydrostatic consolidation of Pierre shale

    USGS Publications Warehouse

    Savage, W.Z.; Braddock, W.A.

    1991-01-01

    This paper presents closed-form solutions for consolidation of transversely isotropic porous media under hydrostatic stress. The solutions are applied to model the time variation of pore pressure, volume strain and strains parallel and normal to bedding, and to obtain coefficients of consolidation and permeability, as well as other properties, and the bulk modulus resulting from hydrostatic consolidation of Pierre shale. It is found that the coefficients consolidation and permeability decrease and the bulk moduli increase with increasing confining pressure, reflecting the closure of voids in the rock. ?? 1991.

  11. Axial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings 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 bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  12. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Hydrostatic tests (modifies 137.4). 56.97-30 Section... PIPING SYSTEMS AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4). (a) Provision of...

  13. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Hydrostatic tests (modifies 137.4). 56...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4)....

  14. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Hydrostatic tests (modifies 137.4). 56...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4)....

  15. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Hydrostatic tests (modifies 137.4). 56...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4)....

  16. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Hydrostatic tests (modifies 137.4). 56...GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING...AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4)....

  17. Cryogenic Hybrid Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  18. Punching Tests on Disks of Rock Under Hydrostatic Pressure

    Microsoft Academic Search

    J. C. Jaeger

    1962-01-01

    A simple apparatus for making punching tests on disks of rock subjected to an additional hydrostatic pressure is described. Experiments have been made on marble, slate, and sandstone. They give an approximate value for the variation of shear strength with con- fining pressure. For marble and slate, confining pressure has a considerable strengthening effect, but for sandstone this effect is

  19. ANALYTICAL SOLUTIONS FOR THE FREE SURFACE HYDROSTATIC EULER EQUATIONS

    E-print Network

    Paris-Sud XI, Université de

    ANALYTICAL SOLUTIONS FOR THE FREE SURFACE HYDROSTATIC EULER EQUATIONS A.-C. BOULANGER , M.-O. BRISTEAU , AND J. SAINTE-MARIE Abstract. In this paper we propose a large set of analytical solutions concern free surface flows but partially free surface flows are also considered. These analytical

  20. Altered Golgi apparatus in hydrostatically loaded articular cartilage chondrocytes.

    PubMed Central

    Parkkinen, J J; Lammi, M J; Pelttari, A; Helminen, H J; Tammi, M; Virtanen, I

    1993-01-01

    OBJECTIVES: Articular cartilage proteoglycan content is controlled by joint loading. This study aimed to elucidate the role of hydrostatic pressure in this regulation. METHODS: Primary cultures of chondrocytes from bovine articular cartilage, grown on coverslips, were subjected to 5, 15, or 30 MPa hydrostatic pressure, applied continuously or cyclically at 0.125 or 0.05 Hz. The Golgi apparatus was visualised either by a fluorochrome coupled wheat germ agglutinin or by transmission electron microscopy. Proteoglycan synthesis was studied by the incorporation of sulphur-35 labelled sulphate. RESULTS: After 30 MPa continuous hydrostatic pressure, the Golgi apparatus was observed in a compact form with a concomitant decrease in proteoglycan synthesis. The normal stacked appearance of the Golgi apparatus was no more visible in the electron microscopy preparation of the pressurised chondrocytes. This effect was reversible and was also noticed after 15 MPa continuous load, though to a minor extent. Cyclic pressures (5-30 MPa) caused no apparent change in the Golgi apparatus. The shape of some cells changed to a more retracted form after 30 MPa continuous pressure. Nocodazole, which causes disassembly of the microtubules, blocked the compacting influence of pressurisation on the Golgi apparatus, and reduced proteoglycan synthesis to about half of the control level. CONCLUSIONS: The packing of the Golgi apparatus is dependent on microtubules and may contribute to the inhibition of proteoglycan synthesis observed in articular cartilage subjected to high hydrostatic pressure. Images PMID:8484671

  1. Non-equilibration of hydrostatic pressure in blebbing cells

    E-print Network

    Mahadevan, L.

    in animal cells focus on cytoskeleton-based mechanisms, where localized protrusion is driven by local pressure4­6 . For hydrostatic pressure to drive localized protrusion in animal cells7,8 , it would have to be initiated by rupture of the plasma membrane from the underlying cytoskeleton (Supplementary Fig. 3

  2. Hydrometer calibration by hydrostatic weighing with automated liquid surface positioning

    Microsoft Academic Search

    Jesus Aguilera; John D Wright; Vern E Bean

    2008-01-01

    We describe an automated apparatus for calibrating hydrometers by hydrostatic weighing (Cuckow's method) in tridecane, a liquid of known, stable density, and with a relatively low surface tension and contact angle against glass. The apparatus uses a laser light sheet and a laser power meter to position the tridecane surface at the hydrometer scale mark to be calibrated with an

  3. Wind resource assessment with a mesoscale non-hydrostatic model

    E-print Network

    Boyer, Edmond

    Wind resource assessment with a mesoscale non- hydrostatic model Vincent Guénard, Center for Energy is developed for assessing the wind resource and its uncertainty. The work focuses on an existing wind farm mast measurements. The wind speed and turbulence fields are discussed. It is shown that the k

  4. The Incredible Water Bear

    NSDL National Science Digital Library

    Martin Mach

    This image-rich Micscape Magazine article explores how water bears can be found almost everywhere yet are still unknown to almost everybody, why there are relatively few light microscope photographs of water bears in the literature and on the Web, and how light microscopy can outperform scanning electron microscopy when viewing these animals. It includes a list of historical references, early sketches, and colorful images of water bears, also known as tardigrades.

  5. Bear Spray Safety Program

    USGS Publications Warehouse

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  6. A feasibility assessment of magnetic bearings for free-piston Stirling space power converters

    NASA Technical Reports Server (NTRS)

    Curwen, Peter W.; Rao, Dantam K.; Wilson, Donald R.

    1992-01-01

    This report describes a design and analysis study performed by Mechanical Technology Incorporated (MTI) under NASA Contract NAS3-26061. The objective of the study was to assess the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery of the type currently being evaluated for possible use in long-term space missions. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) system consisting of two 25-kWe free-piston Stirling engine modules. Two different versions of the RSSPC engine modules have been defined under NASA Contract NAS3-25463. These modules currently use hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Results of this study show that active magnetic bearings of the attractive electromagnetic type are technically feasible for RSSPC application provided that wire insulation with 60,000-hr life capability at 300 C can be developed for the bearing coils. From a design integration standpoint, both versions of the RSSPC were found to be conceptually amenable to magnetic support of the power piston assembly. However, only one version of the RSSPC was found to be amendable to magnetic support of the displacer assembly. Unacceptable changes to the basic engine design would be required to incorporate magnetic displacer bearings into the second version. Complete magnetic suspension of the RSSPC can potentially increase overall efficiency of the Stirling cycle power converter by 0.53 to 1.4 percent (0.15 to 0.4 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. However, these advantages are accompanied by a 5 to 8 percent increase in specific mass of the RSSPC, depending on the RSSPC version employed. Additionally, magnetic bearings are much more complex, both mechanically and particularly electronically, than hydrostatic bearings. Accordingly, long-term stability and reliability represent areas of uncertainty for magnetic bearings. Considerable development effort will be required to establish the long-term suitability of these bearings for Stirling space power applications.

  7. Hydrostatic compression of Fe(1-x)O wuestite

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.; Sato-Sorensen, Y.

    1986-01-01

    Hydrostatic compression measurements on Fe(0.95)O wuestite up to 12 GPa yield a room temperature value for the isothermal bulk modulus of K(ot) = 157 (+ or - 10) GPa at zero pressure. This result is in accord with previous hydrostatic and nonhydrostatic measurements of K(ot) for wuestites of composition: 0.89 = Fe/O 0.95. Dynamic measurements of the bulk modulus by ultrasonic, shock-wave and neutron-scattering experiments tend to yield a larger value: K(ot) approximately 180 GPa. The discrepancy between static and dynamic values cannot be explained by the variation of K(ot) with composition, as has been proposed. This conclusion is based on high-precision compression data and on theoretical models of the effects of defects on elastic constants. Barring serious errors in the published measurements, the available data suggest that wuestite exhibits a volume relaxation under pressure.

  8. Hydrostatic Pressure Sensing with High Birefringence Photonic Crystal Fibers

    PubMed Central

    Fávero, Fernando C.; Quintero, Sully M. M.; Martelli, Cicero; Braga, Arthur M.B.; Silva, Vinícius V.; Carvalho, Isabel C. S.; Llerena, Roberth W. A.; Valente, Luiz C. G.

    2010-01-01

    The effect of hydrostatic pressure on the waveguiding properties of high birefringence photonic crystal fibers (HiBi PCF) is evaluated both numerically and experimentally. A fiber design presenting form birefringence induced by two enlarged holes in the innermost ring defining the fiber core is investigated. Numerical results show that modal sensitivity to the applied pressure depends on the diameters of the holes, and can be tailored by independently varying the sizes of the large or small holes. Numerical and experimental results are compared showing excellent agreement. A hydrostatic pressure sensor is proposed and demonstrated using an in-fiber modal interferometer where the two orthogonally polarized modes of a HiBi PCF generate fringes over the optical spectrum of a broad band source. From the analysis of experimental results, it is concluded that, in principle, an operating limit of 92 MPa in pressure could be achieved with 0.0003% of full scale resolution. PMID:22163435

  9. Ordered states of URu2Si2 under hydrostatic pressure

    Microsoft Academic Search

    J. R. Jeffries; N. P. Butch; J. Paglione; M. B. Maple

    2006-01-01

    Oriented single crystalline samples of URu2Si2 have been synthesized and investigated under nearly hydrostatic pressure via electrical resistivity and ac susceptibility measurements. The heavy fermion compound URu2Si2 exhibits three distinct ordered states as a function of temperature and pressure: ``hidden order'' (HO), in which the order parameter has yet to be determined; antiferromagnetism (AFM), which seemingly develops out of the

  10. Raman characterization of carbon materials under non-hydrostatic conditions

    Microsoft Academic Search

    E. del Corro; M. Taravillo; J. González; V. G. Baonza

    2011-01-01

    Raman spectroscopy experiments on double-wall carbon nanotube and highly oriented pyrolytic graphite (HOPG) samples subjected to non-hydrostatic conditions have been conducted in anvil cells to study the effect of the pressure\\/stress on the bands assigned to defects. Typical diamond anvils used in high pressure experiments have been substituted by moissanite (6H-SiC) and sapphire (Al2O3) anvils to allow the observation of

  11. Effect of ultra-high hydrostatic pressure on hydrosoluble vitamins

    Microsoft Academic Search

    Félix Sancho; Yann Lambert; Gérard Demazeau; Alain Largeteau; Jean-Marie Bouvier; Jean-François Narbonne

    1999-01-01

    The effect of ultra-high hydrostatic pressure on selected hydrosoluble vitamins (B1, B6 and C) is studied. Vitamin retention after pressurization has been compared to that induced by several classic food processing treatments, such as pasteurization or sterilization. Ascorbate, pyridoxal, and thiamin hydrochloride, included in a multivitamin model system (mvMS), are analyzed by high performance liquid chromatography (HPLC), and under current

  12. Analysis of ?-phase RDX vibrational lattice modes under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Slough, William; Perger, Warren

    2009-06-01

    Calculations employing density functional theory are performed on ?-phase RDX using the all-electron CRYSTAL06 program. The lowest frequency infrared active lattice modes are investigated as a function of hydrostatic pressure from ambient conditions up to 3 GPa. The strength of coupling between lattice and molecular modes as a function of pressure is examined. The anharmonic deviation of each mode from simple harmonic behavior as a function of pressure is also illustrated.

  13. Dual-Core Photonic Crystal Fiber for Hydrostatic Pressure Sensing

    Microsoft Academic Search

    Daru Chen; Gufeng Hu; Lingxia Chen

    2011-01-01

    We propose a novel hydrostatic pressure sensor based on a dual-core photonic crystal fiber (DC-PCF). Two solid fiber cores separated by an air hole in the cross-section lead to two in- dependent waveguides inside the DC-PCF which accompany with mode coupling. The mode coupling of two solid fiber cores of the DC-PCFunderdifferenthydrostaticpressureisnumericallyinves- tigated. A pressure sensing system is proposed and

  14. Hydrostatic stress dependent yield of 7075-T6 aluminum

    SciTech Connect

    Benzley, S.E.; Priddy, T.G.; Soo Hoo, M.S.

    1980-03-01

    Tension and compression tests on notched cylindrical bars made of 7075-T6 aluminum have been conducted as a part of an investigation of the mechanics of ductile fracture. The compression tests showed significantly stiffer behavior in the nonlinear portion of the experiment than those found from the tension tests. This difference was accounted for by incorporating a hydrostatic stress dependent yield model in the analysis of the experiment. The model was verified by comparing finite element calculations with the actual experimental results.

  15. Magnetotransport studies of FeSe under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Tiwari, Brajesh; Jha, Rajveer; Awana, V. P. S.

    2014-06-01

    The discoveries of iron-based superconductors with relatively high transition temperature are under intense experimental and theoretical investigation. Here we present magnetotransport measurements on FeSe superconductor under hydrostatic pressure. We show that in Fe-deficient tetragonal FeSe binary compound, the onset of superconducting transition is almost doubled under 1.98 GPa pressure and the estimated upper critical field of 26.7 Tesla is increased to 47.5 Tesla.

  16. Effects of Hydrostatic Pressure on the Properties of Magnetic Materials

    Microsoft Academic Search

    R. E. Alley; V. E. Legg

    1960-01-01

    A review of the literature on hydrostatic pressure effects on magnetic materials showed a lack of information on technologically important properties such as initial permeability, and the hysteresis loop. Measurements of these properties up to 20000 psi showed that most solid materials are only slightly affected. These include tape cores of supermalloy, supermendur, 4–79 Mo-permalloy and grain-oriented Si-steel, as well

  17. Thermohydrodynamic analysis of cryogenic liquid turbulent flow fluid film bearings, phase 2

    NASA Technical Reports Server (NTRS)

    Sanandres, Luis

    1994-01-01

    The Phase 2 (1994) Annual Progress Report presents two major report sections describing the thermal analysis of tilting- and flexure-pad hybrid bearings, and the unsteady flow and transient response of a point mass rotor supported on fluid film bearings. A literature review on the subject of two-phase flow in fluid film bearings and part of the proposed work for 1995 are also included. The programs delivered at the end of 1994 are named hydroflext and hydrotran. Both codes are fully compatible with the hydrosealt (1993) program. The new programs retain the same calculating options of hydrosealt plus the added bearing geometries, and unsteady flow and transient forced response. Refer to the hydroflext & hydrotran User's Manual and Tutorial for basic information on the analysis and instructions to run the programs. The Examples Handbook contains the test bearing cases along with comparisons with experimental data or published analytical values. The following major tasks were completed in 1994 (Phase 2): (1) extension of the thermohydrodynamic analysis and development of computer program hydroflext to model various bearing geometries, namely, tilting-pad hydrodynamic journal bearings, flexure-pad cylindrical bearings (hydrostatic and hydrodynamic), and cylindrical pad bearings with a simple elastic matrix (ideal foil bearings); (2) improved thermal model including radial heat transfer through the bearing stator; (3) calculation of the unsteady bulk-flow field in fluid film bearings and the transient response of a point mass rotor supported on bearings; and (4) a literature review on the subject of two-phase flows and homogeneous-mixture flows in thin-film geometries.

  18. Bearing fatigue investigation 3

    NASA Technical Reports Server (NTRS)

    Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

    1982-01-01

    The operating characteristics of large diameter rolling-element bearings 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 bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing 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.

  19. Grizzly bears and forestry

    Microsoft Academic Search

    S. E. Nielsen; R. H. M. Munro; E. L. Bainbridge; G. B. Stenhouse; M. S. Boyce

    2004-01-01

    We assessed the occurrence and fruit production of 13 grizzly bear foods in west-central Alberta, Canada, to better understand use of clearcuts by grizzly bears. Comparisons were made between clearcuts and upland forest stands, while specific models describing food or fruit occurrence within clearcuts were developed from canopy, clearcut age, scarification, and terrain-related variables using logistic regression. Ants, Equisetum spp.,

  20. Superconducting bearings in flywheels

    Microsoft Academic Search

    T. A. Coombs; A. M. Campbell; I. Ganney; W. Lo; T. Twardowski; B. Dawson

    1998-01-01

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate Energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette™. The Pirouette™ system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will

  1. Muscular hydrostat mechanism for lip protrusion in speech

    NASA Astrophysics Data System (ADS)

    Murano, Emi Z.; Stone, Maureen; Honda, Kiyoshi

    2005-09-01

    The lip is an organ consisting mostly of muscle similar to the tongue. While the tongue is known as a muscular hydrostat, it is unclear whether the lip is also. In this paper the muscular hydrostat issue was explored from the anatomical and functional point of view using high-resolution static MRI (hr-MRI 0.125 mm/pixel) and tagged-cineMRI (t-MRI). A 3-D reconstruction of the lips and its muscles was obtained from hr-MRI during sustained vowels /i/ and /u/. The muscular geometry of the orbicularis oris, mentalis, and depressor labii inferior muscles were superimposed onto the principal strains that depicts compression and expansion of the internal tissue obtained from t-MRI. It is shown that (1) orbicularis oris muscle shape can predict both the borderline of glabrous and hairy skin and the manner in which the lips are protruded; (2) the lips volume is almost identical for both speech tasks; and (3) direction and intensity of compression of orbicularis oris and mentalis muscle bundles imply the role of these muscles in the protrusion appearance. These results indicate that the muscular architecture and volume preserving characteristics of the lips are consistent with a muscular hydrostat. [This work was supported by NIH (USA) and NiCT (Japan).

  2. Ball Bearing Mechanics

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    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.

  3. The Polar Bear Tracker

    NSDL National Science Digital Library

    This new Web site from the World Wildlife Fund (WWF) International explores how polar bears are affected by global warming. Data on the movements of two radio-collared bears can be viewed, along with the ice status, through a series of online maps. This is an interesting site with valuable information and a nice balance of maps, photos, and text. The animation of the polar bear tracking data is a really neat feature, but is best viewed by advancing through the stages manually because the rapid speed of the film makes it difficult to comprehend.

  4. The water-bearing numerical model and its operational forecasting experiments part I: the water-bearing numerical model

    NASA Astrophysics Data System (ADS)

    Xia, Daqing; Xu, Youping

    1998-06-01

    In first paper of articles, the physical and calculating schemes of the water-bearing numerical model are described. The model is developed by bearing all species of hydrometeors in a conventional numerical model in which the dynamic framework of hydrostatic equilibrium is taken. The main contributions are: the mixing ratios of all species of hydrometeors are added as the prognostic variables of model, the prognostic equations of these hydrometeors are introduced, the cloud physical framework is specially designed, some technical measures are used to resolve a series of physical, mathematical and computational problems arising from water-bearing; and so on. The various problems (in such aspects as the designs of physical and calculating schemes and the composition of computational programme) which are exposed in feasibility test, in sensibility test, and especially in operational forecasting experiments are successfully resolved using a lot of technical measures having been developed from researches and tests. Finally, the operational forecasting running of the water-bearing numerical model and its forecasting system is realized stably and reliably, and the fine forecasts are obtained. All of these mentioned above will be described in second paper.

  5. Investigation of Pressurized Wave Bearings

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Dimofte, Florin

    2003-01-01

    The wave bearing has been pioneered and developed by Dr. Dimofte over the past several years. This bearing will be the main focus of this research. It is believed that the wave bearing offers a number of advantages over the foil bearing, which is the bearing that NASA is currently pursuing for turbomachinery applications. The wave bearing is basically a journal bearing whose film thickness varies around the circumference approximately sinusoidally, with usually 3 or 4 waves. Being a rigid geometry bearing, it provides precise control of shaft centerlines. The wave profile also provides good load capacity and makes the bearing very stable. Manufacturing techniques have been devised that should allow the production of wave bearings almost as cheaply as conventional full-circular bearings.

  6. Optimal Synchronizability of Bearings

    NASA Astrophysics Data System (ADS)

    Araújo, N. A. M.; Seybold, H.; Baram, R. M.; Herrmann, H. J.; Andrade, J. S., Jr.

    2013-02-01

    Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with asymmetrically weighted couplings. Accordingly, these networks can exhibit optimal synchronization properties through fine-tuning of the local interaction strength as a function of node degree [Motter, Zhou, and Kurths, Phys. Rev. E 71, 016116 (2005)PLEEE81539-3755]. We show that, in analogy, the synchronizability of bearings can be maximized by counterbalancing the number of contacts and the inertia of their constituting rotor disks through the mass-radius relation, m˜r?, with an optimal exponent ?=?× which converges to unity for a large number of rotors. Under this condition, and regardless of the presence of a long-tailed distribution of disk radii composing the mechanical system, the average participation per disk is maximized and the energy dissipation rate is homogeneously distributed among elementary rotors.

  7. PCs and Polar Bears

    NSDL National Science Digital Library

    Jessica Fries-Gaither

    2011-01-01

    This article looks at the growing energy consumption from consumer electronics and the increases it may cause in greenhouse gases and global warming. The article appears in the free, online magazine Beyond Penguins and Polar Bears.

  8. Gear bearing drive

    NASA Technical Reports Server (NTRS)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  9. Load responsive hydrodynamic bearing

    DOEpatents

    Kalsi, Manmohan S. (Houston, TX); Somogyi, Dezso (Sugar Land, TX); Dietle, Lannie L. (Stafford, TX)

    2002-01-01

    A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing 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 bearing 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 contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing 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 bearing, 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.

  10. Hydrostatic extrusion of Cu-Ag melt spun ribbon

    DOEpatents

    Hill, Mary Ann (Los Alamos, NM); Bingert, John F. (Jemez Springs, NM); Bingert, Sherri A. (Jemez Springs, NM); Thoma, Dan J. (Los Alamos, NM)

    1998-01-01

    The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process.

  11. Hydrostatic extrusion of Cu-Ag melt spun ribbon

    DOEpatents

    Hill, M.A.; Bingert, J.F.; Bingert, S.A.; Thoma, D.J.

    1998-09-08

    The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process. 5 figs.

  12. Birdmuscles under hydrostatic high-pressure\\/temperature combinations

    Microsoft Academic Search

    F. Fernández-Martín

    2007-01-01

    Breast muscles from three different birds\\u000a were subjected to hydrostatic high-pressure (400 MPa)\\/temperature (10–75°C)\\u000a combinations, and the denaturation-induced effects on the pressurized proteins\\u000a monitored by DSC. Comparisons with parallel results from heating-alone processes\\u000a were established. Actin was the most labile moiety to pressurization and myosin\\u000a together with sarcoplasmic proteins were next in observing pressure-induced\\u000a denaturation at low temperatures. Some myosin

  13. Analysis of ?-PHASE Rdx Vibrational Lattice Modes Under Hydrostatic Pressur

    NASA Astrophysics Data System (ADS)

    Slough, W. J.; Perger, W. F.

    2009-12-01

    Calculations using the all-electron CRYSTAL06 program employing density functional theory are used to calculate the terahertz vibrational frequencies of ?-phase RDX. The lowest frequency infrared active lattice modes are investigated as a function of hydrostatic pressure from ambient conditions up to 3 GPa. A given mode may be composed of both external and internal vibration contributions, with the composition changing as a function of pressure. The anharmonic deviation of each mode from simple harmonic behavior as a function of pressure is also explored.

  14. Smart adaptronic hydrostatic guiding system for machine tool slides

    NASA Astrophysics Data System (ADS)

    Munzinger, C.; Weis, M.; Herder, S.

    2009-03-01

    Guiding systems figure amongst the central components in the flux of a machine tool. Their characteristics have a direct impact on machining accuracy. Hydrostatic guiding systems are preferably used when specific requirements are to be met with regards to accuracy, stiffness and damping. However, an active intervention in the guiding system of such conventional systems, i.e. to absorb geometrical guiding rail errors, has so far not been possible. Compared to modular, conventional systems, adaptronic systems offer considerable cost savings potentials thanks to their increased functional degree of integration [1].

  15. Microelectrodes suitable for use in cells with high hydrostatic pressure.

    PubMed

    Ernau, M C

    1974-05-01

    Microelectrodes with a 1- to 2-mum tip diameter have been made which are capable of withstanding plant cell hydrostatic pressure on impalement. Filling the electrodes with 1% agar or 5% gelatin in 2 m KCl prevents cytoplasmic contents from moving into the electrode tip on impalement and therefore prevents the irreversible increase in resistance which often occurs. The agar and gelatin electrodes were tested in two fresh water algae, Nitella translucens and Mougeotia sp., and the potentials recorded were found comparable to those recorded with standard 2 m KCl electrodes. PMID:16658787

  16. Simulation of Rolling Element Bearings

    Microsoft Academic Search

    Lars-Erik Stacke; Dag Fritzson

    Rolling bearings are high precision, low cost machine elements, used in all kinds of rotat- ing machinery. Simulations of rolling bear- ings bring increased understanding of their dy- namic behaviour, and shortens product develop- ment time. A rolling bearing simulation model called BEAST (BEAring Simulation Tool), has been developed by SKF. Due to the high demands on contact geometry description

  17. Non-hydrostatic sound-proof equations of motion for gravity-dominated compressible flows

    NASA Astrophysics Data System (ADS)

    Dubos, Thomas; Voitus, Fabrice

    2014-05-01

    Non-hydrostatic sound-proof equations of motion for gravity-dominated compressible flows Compressible non-hydrostatic equations of motion with density diagnosed from potential temperature through hydrostatic balance are derived from Hamilton's principle of least action. The corresponding local budgets of energy, potential vorticity and momentum are obtained. Slaving density to potential temperature suppresses the degrees of freedom supporting the propagation of acoustic waves and results in a sound-proof system. The linear normal modes and dispersion relationship for infinitesimal departures from an isothermal state of rest on f- and ?- planes are studied and found to be very accurate from hydrostatic to non-hydrostatic scales. Especially the Lamb wave and long Rossby waves are not distorted, unlike with anelastic or pseudo-incompressible systems. Compared to similar equations derived by Arakawa and Konor (2009), the unified system derived here possesses an additional term in the horizontal momentum budget. This apparent force is crucial for the derivation of a well-defined linear elliptic problem. Unlike with anelastic/pseudo-incompressible systems or the equations obtained by Arakawa and Konor (2009), the elliptic problem is vertically fourth-order, reflecting the fact that the hydrostatic constraint satisfied by density involves a vertical derivative. As with hydrostatic equations, vertical velocity is diagnosed through Richardson's equation. Our unified system has therefore precisely the same degrees of freedom as the hydrostatic primitive equations, while retaing accuracy from hydrostatic to non-hydrostatic scales. These equations may be useful as the basis of global non-hydrostatic numerical models. They also provide an accurate way to filter out the acoustic component from a given flow. Variational data assimilation systems may benefit from such a filter, restricting the optimization space to physically relevant motion. Similarly, filtering may be useful to prevent the transient emission of acoustic waves in a fully-compressible model at initialization or after physics parameterizations have acted.

  18. Photomultiplier tube failure under hydrostatic pressure in future neutrino detectors

    DOE PAGESBeta

    Chambliss, K.; Diwan, M.; Simos, N.; Sundaram, S. K.

    2014-10-01

    Failure of photomultiplier tubes (PMTs) under hydrostatic pressure is a concern in neutrino detection, specifically, in the proposed Long-Baseline Neutrino Experiment project. Controlled hydrostatic implosion tests were performed on prototypic PMT bulbs of 10-inch diameter and recorded using high speed filming techniques to capture failures in detail. These high-speed videos were analyzed frame-by-frame in order to identify the origin of a crack, measure the progression of individual crack along the surface of the bulb as it propagates through the glass, and estimate crack velocity. Crack velocity was calculated for each individual crack, and an average velocity was determined for allmore »measurable cracks on each bulb. Overall, 32 cracks were measured in 9 different bulbs tested. Finite element modeling (FEM) of crack formation and growth in prototypic PMT shows stress concentration near the middle section of the PMT bulbs that correlates well with our crack velocity measurements in that section. The FEM model predicts a crack velocity value that is close to the terminal crack velocity reported. Our measurements also reveal significantly reduced crack velocities compared to terminal crack velocities measured in glasses using fracture mechanics testing and reported in literature.« less

  19. Models of hydrostatic magnetar atmospheres at high luminosities

    NASA Astrophysics Data System (ADS)

    van Putten, T.; Watts, A. L.; D'Angelo, C. R.; Baring, M. G.; Kouveliotou, C.

    2013-09-01

    We investigate the possibility of Photospheric Radius Expansion (PRE) during magnetar bursts. Identification of PRE would enable a determination of the magnetic Eddington limit (which depends on field strength and neutron star mass and radius), and shed light on the burst mechanism. To do this we model hydrostatic atmospheres in a strong radial magnetic field, determining both their maximum extent and their photospheric temperatures. We find that spatially extended atmospheres cannot exist in such a field configuration: typical maximum extent for magnetar-strength fields is ˜10 m (as compared to 200 km in the non-magnetic case). Achieving balance of gravitational and radiative forces over a large range of radii, which is critical to the existence of extended atmospheres, is rendered impossible in strong fields due to the dependence of opacities on temperature and field strength. We conclude that high-luminosity bursts in magnetars do not lead to expansion and cooling of the photosphere, as in the non-magnetic case. We also find the maximum luminosity that can propagate through a hydrostatic magnetar atmosphere to be lower than previous estimates. The proximity and small extent of the photospheres associated with the two different polarization modes also call into question the interpretation of two blackbody fits to magnetar burst spectra as being due to extended photospheres.

  20. Opportunities of hydrostatically coupled dielectric elastomer actuators for haptic interfaces

    NASA Astrophysics Data System (ADS)

    Carpi, Federico; Frediani, Gabriele; De Rossi, Danilo

    2011-04-01

    As a means to improve versatility and safety of dielectric elastomer actuators (DEAs) for several fields of application, so-called 'hydrostatically coupled' DEAs (HC-DEAs) have recently been described. HC-DEAs are based on an incompressible fluid that mechanically couples a DE-based active part to a passive part interfaced to the load, so as to enable hydrostatic transmission. This paper presents ongoing developments of HC-DEAs and potential applications in the field of haptics. Three specific examples are considered. The first deals with a wearable tactile display used to provide users with tactile feedback during electronic navigation in virtual environments. The display consists of HCDEAs arranged in contact with finger tips. As a second example, an up-scaled prototype version of an 8-dots refreshable cell for dynamic Braille displays is shown. Each Braille dot consists of a miniature HC-DEA, with a diameter lower than 2 mm. The third example refers to a device for finger rehabilitation, conceived to work as a sort of active version of a rehabilitation squeezing ball. The device is designed to dynamically change its compliance according to an electric control. The three examples of applications intend to show the potential of the new technology and the prospective opportunities for haptic interfaces.

  1. Power transmission arrangement for a hydrostatically driven vehicle

    SciTech Connect

    Tokunga, N.

    1986-03-25

    A power transmission arrangement is described for a hydrostatically driven vehicle having a vehicle body and a pair of endless tracks each mounted on each side of the vehicle body. The arrangement consists of: a prime mover mounted at the rear of the vehicle; a power transmission shaft connected to the prime mover; power distributor means mounted on a front section of the vehicle body, the power distributor means having a power input connectible to the power transmission shaft and at least two power outputs; a pair of pump and motor units each unit being mounted on either side of the vehicle body relative to the power transmission shaft, intermediate the prime mover and the power distributor means, and forming a hydrostatic transmission, each unit having a power input connectible to the power output of the power distributor means and a power output; and a pair of final drive means for driving the endless tracks, each of the final drive means being connectible to a power output of the pump and motor unit.

  2. Photomultiplier tube failure under hydrostatic pressure in future neutrino detectors

    NASA Astrophysics Data System (ADS)

    Chambliss, K.; Sundaram, S. K.; Simos, N.; Diwan, M. V.

    2014-10-01

    Failure of photomultiplier tubes (PMTs) under hydrostatic pressure is a concern in neutrino detection, specifically, in the proposed Long-Baseline Neutrino Experiment (LBNE) project. Controlled hydrostatic implosion tests were performed on prototypic PMT bulbs of 10-inch diameter and recorded using high-speed filming techniques to capture failures in detail. These high-speed videos were analyzed frame-by-frame in order to identify the origin of a crack, measure the progression of individual crack along the surface of the bulb as it propagates through the glass, and estimate crack velocity. Crack velocity was calculated for each individual crack and an average velocity was determined for all measurable cracks on each bulb. Overall, 32 cracks were measured in 9 different bulbs tested. Finite element modeling (FEM) of crack formation and growth in prototypic PMT shows stress concentration near the middle section of the PMT bulbs that correlates well with our crack velocity measurements in that section. The FEM model predicts a crack velocity value that is close to the terminal crack velocity reported. Our measurements also reveal significantly reduced crack velocities compared to terminal crack velocities measured in glasses using fracture mechanics testing and reported in literature.

  3. Hydrostatic equilibrium in a magnetized, warped Galactic disc

    E-print Network

    Andrew Fletcher; Anvar Shukurov

    2001-02-22

    Hydrostatic equilibrium of the multiphase interstellar medium in the solar vicinity is reconsidered, with the regular and turbulent magnetic fields treated separately. The regular magnetic field strength required to support the gas is consistent with independent estimates provided energy equipartition is maintained between turbulence and random magnetic fields. Our results indicate that a midplane value of $B_{0}=4\\mkG$ for the regular magnetic field near the Sun leads to more attractive models than $B_{0}=2\\mkG$. The vertical profiles of both the regular and random magnetic fields contain disc and halo components whose parameters we have determined. The layer at $1\\la|z|\\la4\\kpc$ can be overpressured and an outflow at a speed of about $50\\kms$ may occur there, presumably associated with a Galactic fountain flow, if $B_{0}\\simeq 2\\mkG$. We show that hydrostatic equilibrium in a warped disc must produce asymmetric density distributions in $z$, in rough agreement with \\HI observations in the outer Galaxy. This asymmetry may be a useful diagnostic of the details of the warping mechanism in the Milky Way and other galaxies. We find indications that gas and magnetic field pressures are different above and below the warped midplane in the outer Galaxy and quantify the difference in terms of turbulent velocity and/or magnetic field strength.

  4. Photomultiplier tube failure under hydrostatic pressure in future neutrino detectors

    DOE PAGESBeta

    Chambliss, K. [Alfred Univ., Alfred, NY (United States). Multifunctional Materials Lab, Kazuo Inamori School of Engineering; Diwan, M. [Alfred Univ., Alfred, NY (United States). Multifunctional Materials Lab, Kazuo Inamori School of Engineering; Simos, N. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Sundaram, S. K. [Alfred Univ., Alfred, NY (United States). Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2014-10-01

    Failure of photomultiplier tubes (PMTs) under hydrostatic pressure is a concern in neutrino detection, specifically, in the proposed Long-Baseline Neutrino Experiment project. Controlled hydrostatic implosion tests were performed on prototypic PMT bulbs of 10-inch diameter and recorded using high speed filming techniques to capture failures in detail. These high-speed videos were analyzed frame-by-frame in order to identify the origin of a crack, measure the progression of individual crack along the surface of the bulb as it propagates through the glass, and estimate crack velocity. Crack velocity was calculated for each individual crack, and an average velocity was determined for all measurable cracks on each bulb. Overall, 32 cracks were measured in 9 different bulbs tested. Finite element modeling (FEM) of crack formation and growth in prototypic PMT shows stress concentration near the middle section of the PMT bulbs that correlates well with our crack velocity measurements in that section. The FEM model predicts a crack velocity value that is close to the terminal crack velocity reported. Our measurements also reveal significantly reduced crack velocities compared to terminal crack velocities measured in glasses using fracture mechanics testing and reported in literature.

  5. Birefringence and dispersion properties of elliptical hollow core optical fiber under hydrostatic pressure

    Microsoft Academic Search

    Ahmad Zubair; Saima Afroz Siddiqui; M. Shah Alam

    2009-01-01

    Highly birefringent elliptical hollow core optical fiber under hydrostatic pressure is analyzed in this work using finite element method. The combined effects of thermal stress generated during fabrication and external applied stress have been considered. Birefringence increases while group velocity dispersion decreases when the fiber is under hydrostatic pressure. Higher birefringence, lower material dispersion and moderate effective area can make

  6. Forcing a three-dimensional, hydrostatic, primitive-equation model for application in the surf zone

    E-print Network

    Forcing a three-dimensional, hydrostatic, primitive-equation model for application in the surf zone-dimensional (3D) wave-averaged mean circulation in the surf zone is presented. The objective is to develop-dimensional, hydrostatic, primitive-equation model for application in the surf zone: 1. Formulation, J. Geophys. Res., 112

  7. Calculation of Rdx Molecular Crystal Geometry and Vibrational Frequencies Under Hydrostatic Pressure

    NASA Astrophysics Data System (ADS)

    Slough, W. J.; Perger, W. F.

    2007-12-01

    First-principles calculations of the effects of hydrostatic pressure on RDX are performed using the all-electron CRYSTAL06 program. The lattice constants and optimized internal coordinates are simultaneously obtained at ambient pressure and hydrostatic pressure up to 2.9 GPa. The vibrational frequencies as a function of pressure are also calculated and compared with experimental results from the literature.

  8. Research on the regenerative braking control strategy for secondary regulation hydrostatic transmission excavators

    Microsoft Academic Search

    Yu Ancai; Jiang Jihai

    2009-01-01

    The secondary regulation hydrostatic transmission technology is applied to the wheel excavator walking device to improve the fuel economy and emissions. A new braking control strategy is proposed based on the analysis of the characteristics of excavator braking and high power density of hydrostatic transmission technology. As to deal with the robust control problems against parameter uncertainty and load disturbance,

  9. Partial tooth gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  10. Radial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings 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. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while minimizing it on the opposite side. The advantage of this configuration is that it makes it possible to approach the theoretical maximum force per unit area that could be exerted by a given amount of permanent-magnet material. The configuration is named after physicist Klaus Halbach, who conceived it for use in particle accelerators. Halbach arrays have also been studied for use in magnetic-levitation ("maglev") railroad trains. In a radial Halbach magnetic bearing, the basic Halbach arrangement is modified into a symmetrical arrangement of sector-shaped permanent magnets mounted on the outer cylindrical surface of a drum rotor (see Figure 2). The magnets are oriented to concentrate the magnetic field on their radially outermost surface. The stator coils are mounted in a stator shell surrounding the rotor.

  11. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing 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 bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing 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 contact 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 bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  12. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    1999-01-01

    Methods and apparatus are provided for a blood pump bearing 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 bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing 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 contact 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 bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  13. Dynamic Culturing of Cartilage Tissue: The Significance of Hydrostatic Pressure

    PubMed Central

    Pereira, Ana L.; Duarte, Ana R.C.; Frias, Ana M.; Pedro, Adriano J.; Oliveira, João T.; Sousa, Rui A.; Reis, Rui L.

    2012-01-01

    Human articular cartilage functions under a wide range of mechanical loads in synovial joints, where hydrostatic pressure (HP) is the prevalent actuating force. We hypothesized that the formation of engineered cartilage can be augmented by applying such physiologic stimuli to chondrogenic cells or stem cells, cultured in hydrogels, using custom-designed HP bioreactors. To test this hypothesis, we investigated the effects of distinct HP regimens on cartilage formation in vitro by either human nasal chondrocytes (HNCs) or human adipose stem cells (hASCs) encapsulated in gellan gum (GG) hydrogels. To this end, we varied the frequency of low HP, by applying pulsatile hydrostatic pressure or a steady hydrostatic pressure load to HNC-GG constructs over a period of 3 weeks, and evaluated their effects on cartilage tissue-engineering outcomes. HNCs (10×106 cells/mL) were encapsulated in GG hydrogels (1.5%) and cultured in a chondrogenic medium under three regimens for 3 weeks: (1) 0.4?MPa Pulsatile HP; (2) 0.4?MPa Steady HP; and (3) Static. Subsequently, we applied the pulsatile regimen to hASC-GG constructs and varied the amplitude of loading, by generating both low (0.4?MPa) and physiologic (5?MPa) HP levels. hASCs (10×106 cells/mL) were encapsulated in GG hydrogels (1.5%) and cultured in a chondrogenic medium under three regimens for 4 weeks: (1) 0.4?MPa Pulsatile HP; (2) 5?MPa Pulsatile HP; and (3) Static. In the HNC study, the best tissue development was achieved by the pulsatile HP regimen, whereas in the hASC study, greater chondrogenic differentiation and matrix deposition were obtained for physiologic loading, as evidenced by gene expression of aggrecan, collagen type II, and sox-9; metachromatic staining of cartilage extracellular matrix; and immunolocalization of collagens. We thus propose that both HNCs and hASCs detect and respond to physical forces, thus resembling joint loading, by enhancing cartilage tissue development in a frequency- and amplitude-dependant manner. PMID:22559784

  14. Bearing-Cartridge Damping Seal

    NASA Technical Reports Server (NTRS)

    Goggins, David G.; Scharrer, Joseph K.; Chen, Wei C.

    1991-01-01

    In proposed design for improved ball-bearing cartridge, damping seal in form of thin-layer fluid journal bearing incorporated into cartridge. Damping seal acts as auxiliary bearing, relieving bearing balls of significant portions of both static and dynamic bearing loads. Damping from seal reduces dynamic loads even further by reducing amplitude of vibrations in second vibrational mode of rotor, which mode occurs when rotor turning at nearly full operating speed. Intended for use in high-pressure-oxygen turbopump of Space Shuttle main engine, also applicable to other turbomachinery bearings.

  15. Embryonic stem cell-derived osteocytes are capable of responding to mechanical oscillatory hydrostatic pressure.

    PubMed

    Ehnes, D D; Price, F D; Shrive, N G; Hart, D A; Rancourt, D E; Zur Nieden, N I

    2015-07-16

    Osteoblasts can be derived from embryonic stem cells (ESCs) by a 30 day differentiation process, whereupon cells spontaneously differentiate upon removal of LIF and respond to exogenously added 1,25?(OH)2 vitamin D3 with enhanced matrix mineralization. However, bone is a load-bearing tissue that has to perform under dynamic pressure changes during daily movement, a capacity that is executed by osteocytes. At present, it is unclear whether ESC-derived osteogenic cultures contain osteocytes and whether these are capable of responding to a relevant cyclic hydrostatic compression stimulus. Here, we show that ESC-osteoblastogenesis is followed by the generation of osteocytes and then mechanically load ESC-derived osteogenic cultures in a compression chamber using a cyclic loading protocol. Following mechanical loading of the cells, iNOS mRNA was upregulated 31-fold, which was consistent with a role for iNOS as an immediate early mechanoresponsive gene. Further analysis of matrix and bone-specific genes suggested a cellular response in favor of matrix remodeling. Immediate iNOS upregulation also correlated with a concomitant increase in Ctnnb1 and Tcf7l2 mRNAs along with increased nuclear TCF transcriptional activity, while the mRNA for the repressive Tcf7l1 was downregulated, providing a possible mechanistic explanation for the noted matrix remodeling. We conclude that ESC-derived osteocytes are capable of responding to relevant mechanical cues, at least such that mimic oscillatory compression stress, which not only provides new basic understanding, but also information that likely will be important for their use in cell-based regenerative therapies. PMID:25936968

  16. 10. DETAIL VIEW OF END BEARING CONDITION SHOWING MOVEABLE BEARING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. DETAIL VIEW OF END BEARING CONDITION SHOWING MOVEABLE BEARING AT SOUTHEAST END OF LOWER ROAD LEVEL - Mahoning Avenue Pratt Double-Deck Bridge, Spanning Mill Creek at Mahoning Avenue (C.R. 319), Youngstown, Mahoning County, OH

  17. Totally frictionless magnetic bearing

    Microsoft Academic Search

    Wayne Dodakian; John Bulman

    2000-01-01

    A totally frictionless magnetic bearing has been developed which supports a rotor in a contactless manner. The rotor is held in a magnetic potential well via repulsive forces only. Vertical and lateral restoring forces are provided to the rotor passively via permanent magnets in such an arrangement so as to support the weight of the rotor and provide it with

  18. Tardigrada (Water Bears)

    NSDL National Science Digital Library

    Micrographia

    This reference page offers a brief description of Tardigrades, also known as water bears. It includes information about their physical appearance, an explanation of their name, likely habitats, internal organs and other distinguishing features, and a few images. A diagram of a common tardigrade, Macrobiotus macronyx, is also provided via an internal link.

  19. Magnetic Bearings For Turbopumps

    NASA Technical Reports Server (NTRS)

    Meeks, Crawford R.; Mendez, Antonio J.

    1995-01-01

    Report presents study of feasibility of magnetic bearings in turbopumps. Liquid-oxygen turbopump in space shuttle main engine selected for study. Other potential applications include manned and unmanned spacecraft, gas turbines for commercial and military aircraft, turbomachinery for petro-chemical and gas operations, suspension systems for precise machinery, and precise pointing and tracking systems.

  20. Bear vs Bee

    NSDL National Science Digital Library

    2012-01-01

    This interactive Java applet is a game that challenges a student to solve problems by using logic and rudimentary engineering skills. The goal in each case is to create a conveyance that gets the bear to the pot of honey, avoiding the bees. The game has 32 stages of increasing complexity.

  1. Bearings Incorporating Deadband Rollers

    NASA Technical Reports Server (NTRS)

    Gualtieri, Guy V.

    1996-01-01

    Bearings in high-pressure turbopump redesigned to incorporate rollers allowing limited axial motion within small deadband. Does not permit radial deadband motion. Axial deadband motion used for rotor-thrust-balance control. Design eliminates some nonlinearities in dynamics of pump rotor and assists in suppressing vibrations at harmonics of frequency of rotation.

  2. History of ball bearings

    NASA Technical Reports Server (NTRS)

    Dowson, D.; Hamrock, B. J.

    1981-01-01

    The familiar precision rolling-element bearings of the twentieth century are products of exacting technology and sophisticated science. Their very effectiveness and basic simplicity of form may discourage further interest in their history and development. Yet the full story covers a large portion of recorded history and surprising evidence of an early recognition of the advantages of rolling motion over sliding action and progress toward the development of rolling-element bearings. The development of rolling-element bearings is followed from the earliest civilizations to the end of the eighteenth century. The influence of general technological developments, particularly those concerned with the movement of large building blocks, road transportation, instruments, water-raising equipment, and windmills are discussed, together with the emergence of studies of the nature of rolling friction and the impact of economic factors. By 1800 the essential features of ball and rolling-element bearings had emerged and it only remained for precision manufacture and mass production to confirm the value of these fascinating machine elements.

  3. Oregon Zoo Polar Bear

    USGS Multimedia Gallery

    Tasul, an Oregon Zoo polar bear, sports a high-tech collar that will help researchers study her endangered wild counterparts in the Arctic. Photo by Michael Durham, courtesy of the Oregon Zoo. Photo by Michael Durham, courtesy of the Oregon Zoo....

  4. Cell Membranes Under Hydrostatic Pressure Subjected to Micro-Injection

    NASA Astrophysics Data System (ADS)

    Vassilev, Vassil M.; Kostadinov, Kostadin G.; Mladenov, Ivaïlo M.; Shulev, Assen A.; Stoilov, Georgi I.; Djondjorov, Peter A.

    2011-04-01

    The work is concerned with the determination of the mechanical behaviour of cell membranes under uniform hydrostatic pressure subject to micro-injections. For that purpose, assuming that the shape of the deformed cell membrane is axisymmetric a variational statement of the problem is developed on the ground of the so-called spontaneous curvature model. In this setting, the cell membrane is regarded as an axisymmetric surface in the three-dimensional Euclidean space providing a stationary value of the shape energy functional under the constraint of fixed total area and fixed enclosed volume. The corresponding Euler-Lagrange equations and natural boundary conditions are derived, analyzed and used to express the forces and moments in the membrane. Several examples of such surfaces representing possible shapes of cell membranes under pressure subjected to micro injection are determined numerically.

  5. Models of hydrostatic magnetar atmospheres at high luminosities

    E-print Network

    van Putten, T; D'Angelo, C R; Baring, M G; Kouveliotou, C

    2012-01-01

    We investigate the possibility of Photospheric Radius Expansion (PRE) during magnetar bursts. Identification of PRE would enable a determination of the magnetic Eddington limit (which depends on field strength and neutron star mass and radius), and shed light on the burst mechanism. To do this we model hydrostatic atmospheres in a strong radial magnetic field, determining both their maximum extent and photospheric temperatures. We find that spatially-extended atmospheres cannot exist in such a field configuration: typical maximum extent for magnetar-strength fields is ~ 10m (as compared to 200 km in the non-magnetic case). Achieving balance of gravitational and radiative forces over a large range of radii, which is critical to the existence of extended atmospheres, is rendered impossible in strong fields due to the dependence of opacities on temperature and field strength. We conclude that high luminosity bursts in magnetars do not lead to expansion and cooling of the photosphere, as in the non-magnetic case....

  6. Hydrometer calibration by hydrostatic weighing with automated liquid surface positioning

    NASA Astrophysics Data System (ADS)

    Aguilera, Jesus; Wright, John D.; Bean, Vern E.

    2008-01-01

    We describe an automated apparatus for calibrating hydrometers by hydrostatic weighing (Cuckow's method) in tridecane, a liquid of known, stable density, and with a relatively low surface tension and contact angle against glass. The apparatus uses a laser light sheet and a laser power meter to position the tridecane surface at the hydrometer scale mark to be calibrated with an uncertainty of 0.08 mm. The calibration results have an expanded uncertainty (with a coverage factor of 2) of 100 parts in 106 or less of the liquid density. We validated the apparatus by comparisons using water, toluene, tridecane and trichloroethylene, and found agreement within 40 parts in 106 or less. The new calibration method is consistent with earlier, manual calibrations performed by NIST. When customers use calibrated hydrometers, they may encounter uncertainties of 370 parts in 106 or larger due to surface tension, contact angle and temperature effects.

  7. Hydrostatic factors affect the gravity responses of algae and roots

    NASA Technical Reports Server (NTRS)

    Staves, Mark P.; Wayne, Randy; Leopold, A. C.

    1991-01-01

    The hypothesis of Wayne et al. (1990) that plant cells perceive gravity by sensing a pressure differential between the top and the bottom of the cell was tested by subjecting rice roots and cells of Caracean algae to external solutions of various densities. It was found that increasing the density of the external medium had a profound effect on the polar ratio (PR, the ratio between velocities of the downwardly and upwardly streaming cytoplasm) of the Caracean algae cells. When these cells were placed in solutions of denser compound, the PR decreased to less than 1, as the density of the external medium became higher than that of the cell; thus, the normal gravity-induced polarity was reversed, indicating that the osmotic pressure of the medium affects the cell's ability to respond to gravity. In rice roots, an increase of the density of the solution inhibited the rate of gravitropism. These results agree with predictions of a hydrostatic model for graviperception.

  8. Ultrahigh hydrostatic pressure extraction of flavonoids from Epimedium koreanum Nakai

    NASA Astrophysics Data System (ADS)

    Hou, Lili; Zhang, Shouqin; Dou, Jianpeng; Zhu, Junjie; Liang, Qing

    2011-02-01

    Herba Epimedii is one of the most famous Chinese herbal medicines listed in the Pharmacopoeia of the People's Republic of China, as one of the representatives of traditional Chinese herb, it has been widely applied in the field of invigorate the kidney and strengthen 'Yang'. The attention to Epimedium extract has more and more increased in recent years. In this work, a novel extraction technique, ultra-high hydrostatic pressure extraction (UPE) technology was applied to extract the total flavonoids of E. koreanum. Three factors (pressure, ethanol concentration and extraction time) were chosen as the variables of extraction experiments, and the optimum UPE conditions were pressure 350 MPa; ethanol concentration 50% (v/v); extraction time 5 min. Compared with Supercritical CO2 extraction, Reflux extraction and Ultrasonic-assisted extraction, UPE has excellent advantages (shorter extraction time, higher yield, better antioxidant activity, lower energy consumption and eco-friendly).

  9. The Great Bear Rainforest Spirit Bears, Grizzlies and Ancient Forests

    E-print Network

    de Leon, Alex R.

    The Great Bear Rainforest Spirit Bears, Grizzlies and Ancient Forests September 16 ­ 22, 2015 with Dr. Wayne Lynch The temperate rainforests are one of the richest habitats on Earth; supporting more at the movies and the Great Bear Rainforest is one of the world's best places to witness this primordial drama

  10. Vygotsky and the Three Bears

    ERIC Educational Resources Information Center

    Kulczewski, Peggy

    2004-01-01

    Peggy Kulczewski, a kindergarten classroom teacher, remembers the day when students enjoyed a story she told them from the book "The Three Bears". The students' discussion about comparison of the bears was very helpful to the whole group.

  11. A self-lubricating bearing

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F. (inventor)

    1974-01-01

    An improved bearing structure is described which includes a permanently magnetized porous body filled with an interstitial magnetic lubricant for extending the operational life of self-lubricating bearings. The bearing structure is characterized by a permanently magnetized retainer formed of a porous material and filled with an interstitial magnetic lubricant, whereby the pores serve as lubricant reservoirs from which the lubricant continuously is delivered to a film disposed between contiguous bearing surfaces.

  12. Carbon Nanotube Linear Bearing Nanoswitches

    E-print Network

    Bockrath, Marc

    Carbon Nanotube Linear Bearing Nanoswitches V. V. Deshpande, H.-Y. Chiu, H. W. Ch. Postma, C. Miko-friction bearing capabilities of multiwalled carbon nanotubes (MWNTs) to realize nanoelectromechanical switches bearing capabilities3-5 of multi- and double-walled carbon nanotubes (MWNTs and DWNTs) to realize

  13. Diaphragm-based fiber optic Fabry-Perot hydrophone with hydrostatic pressure compensation

    NASA Astrophysics Data System (ADS)

    Wang, Zhaogang; Zhang, Wentao; Li, Fang

    2013-09-01

    A fiber optic Fabry-Perot (FP) hydrophone with hydrostatic pressure compensation was demonstrated. A polyimide (PI) diaphragm attached on the end of an Acrylonitrile Butadiene Styrene (ABS) tube was used as the sensing element. A pair of grooves was designed in an inner ABS tube to connect the Fabry-Perot cavity with the outside environment, which made the hydrophone hydrostatic pressure compensated. The operation principle, design and testing of polyimide diaphragm-based sensor were described. Experiment results show that it has not only high stability in different hydrostatic pressures, but also flat frequency response of about 158 ±3 dB within 300-3000 Hz.

  14. Bears in a Boat

    NSDL National Science Digital Library

    2012-06-14

    In this math activity, learners are challenged to create aluminum foil boats that will hold plastic bears until the boats sink. The lesson serves as a fun, hands-on way to collect data. Data from two attempts is collected and used to make two class box-and-whisker plots with some surprising results. This lesson guide includes questions for learners, assessment options, extensions, and reflection questions.

  15. The Polar Bear Game

    NSDL National Science Digital Library

    2010-10-24

    In this game, which is similar to Petals Around the Rose (cataloged separately), a player rolls 5 dice and asks the participants, “How many polar bears are around the ice holes?” The participants try to figure out the riddle (rules of the game) by studying the dice arrangements and the answers that correspond. This webpage extends the game to have players also determine the number of fish and plankton.

  16. Night of the Bear

    NSDL National Science Digital Library

    Casey Debenham

    2002-08-25

    The NOAA Ocean Exploration program strives to engage broad audiences to enhance America's environmental literacy through the excitement of ocean discovery. Increasing this literacy requires high-quality, effective collaborations between ocean explorers and America's teachers. NOAA is forming such collaborations to reach out in new ways to the public to improve the literacy of learners with respect to ocean issues. This site is a daily log of exploration in the Arctic and research on the Polar Bear.

  17. Grizzly bears and forestry

    Microsoft Academic Search

    Scott E. Nielsen; Mark S. Boyce; Gordon B. Stenhouse

    2004-01-01

    We examined if clearcuts were selected as habitats by grizzly bears (Ursus arctos L.) in west-central Alberta during three seasons: hypophagia, early hyperphagia, and late hyperphagia. Our objectives were to describe seasonal habitat selection of clearcuts using resource selection functions at two scales. At the first scale, we assessed patch or third-order selection by comparing use (radiotelemetry) with study area-wide

  18. Anti-backlash gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2009-01-01

    A gear bearing 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 bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, 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 bearing movement.

  19. Bearing for liquid metal pump

    DOEpatents

    Dickinson, Robert J. (Shaler Township, Allegheny County, PA); Wasko, John (Plum Borough, PA); Pennell, William E. (Unity Township, Allegheny County, PA)

    1984-01-01

    A liquid metal pump bearing support comprises a series of tangentially oriented spokes that connect the bearing cylinder to the pump internals structure. The spokes may be arranged in a plurality of planes extending from the bearing cylinder to the pump internals with the spokes in one plane being arranged alternately with those in the next plane. The bearing support structure provides the pump with sufficient lateral support for the bearing structure together with the capability of accommodating differential thermal expansion without adversely affecting pump performance.

  20. Hybrid Bearing Prognostic Test Rig

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Certo, Joseph M.; Handschuh, Robert F.; Dimofte, Florin

    2005-01-01

    The NASA Glenn Research Center has developed a new Hybrid Bearing Prognostic Test Rig to evaluate the performance of sensors and algorithms in predicting failures of rolling element bearings for aeronautics and space applications. The failure progression of both conventional and hybrid (ceramic rolling elements, metal races) bearings can be tested from fault initiation to total failure. The effects of different lubricants on bearing life can also be evaluated. Test conditions monitored and recorded during the test include load, oil temperature, vibration, and oil debris. New diagnostic research instrumentation will also be evaluated for hybrid bearing damage detection. This paper summarizes the capabilities of this new test rig.

  1. Bearing construction for refrigeration compresssor

    DOEpatents

    Middleton, Marc G. (Wyoming, MI); Nelson, Richard T. (Worthington, OH)

    1988-01-01

    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 bearing housing is secured to the central portion of the cylinder block and extends vertically along the crankshaft, where it carries a pair of roller bearings to journal the crankshaft. The crankshaft has a radially extending flange which is journaled by a thrust-type roller bearing above the bearing housing to absorb the vertical forces on the crankshaft so that all three of the roller bearings are between the crankshaft and the bearing housing to maintain and control the close tolerances required by such bearings.

  2. History of Space Shuttle Main Engine Turbopump Bearing Testing at the Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Gibson, Howard; Thom, Robert; Moore, Chip; Haluck, Dave

    2010-01-01

    The Space Shuttle is propelled into orbit by two solid rocket motors and three liquid fed main engines. After the solid motors fall away, the shuttle engines continue to run for a total time of 8 minutes. These engines are fed propellants by low and high pressure turbopumps. A critical part of the turbopump is the main shaft that supports the drive turbine and the pump inducer and impeller. Rolling element bearings hold the shaft in place during rotation. If the bearings were to fail, the shaft would move, allowing components to rub in a liquid oxygen or hydrogen environment, which could have catastrophic results. These bearings are required to spin at very high speeds, support radial and axial loads, and have high wear resistance without the benefit of a conventional means of lubrication. The Rocketdyne built Shuttle turbopumps demonstrated their capability to perform during launches; however, the seven hour life requirement was not being met. One of the limiting factors was the bearings. In the late 1970's, an engineering team was formed at the Marshall Space Flight Center (MSFC), to develop a test rig and plan for testing the Shuttle s main engine high pressure oxygen turbopump (HPOTP) bearings. The goals of the program were to better understand the operation of bearings in a cryogenic environment and to further develop and refine existing computer models used to predict the operational limits of these bearings. In 1982, testing began in a rig named the Bearing and Seal Material Tester or BSMT as it was commonly called. The first testing investigated the thermal margin and thermal runaway limits of the HPOTP bearings. The test rig was later used to explore potential bearing improvements in the area of increased race curvatures, new cage materials for better lubrication, new wear resistant rolling element materials, and other ideas to improve wear life. The most notable improvements during this tester s time was the incorporation of silicon nitride balls and bronze filled polytetrafluoroethylene (PTFE) cage inserts into the bearings and the anchoring of the SHABERTH bearing model and SINDA thermal computer model for cryogenic bearing analysis. In the mid 1990's, Pratt and Whitney (P&W) won the contract to deliver new high pressure turbopumps for the Shuttle s engines. P&W used two new bearing materials for the rings, Cronidur 30 and AISI 9310 steel and testing was needed on these new materials. A test rig had been designed and delivered to MSFC for testing hydrostatic bearings but with the need by Pratt to validate their bearings, the rig was reconfigured for testing of two ball bearings or a ball bearing and a roller bearing. The P&W bearings are larger than the Rocketdyne bearings and could not be installed in the BSMT. This new test rig was called the LH2 test rig and began operation in 1995. The LH2 test rig accumulated 75,000 seconds of run time in hydrogen. This test rig was valuable in two areas: validating the use of silicon nitride balls and rollers in Alternate Turbopump Development (ATD) bearings, which Pratt eventually used, and in proving the robustness of the balls and rollers after river marks appeared on the surface of the rolling elements. Individual test reports have been presented at conferences and symposiums throughout the years. This paper is a comprehensive report of all the bearing testing done at Marshall. It represents thousands of hours of dedication and labor in all engineering and technical fields that made this program a success.

  3. Vertical Discretization of Hydrostatic Primitive Equations with Finite Element Method

    NASA Astrophysics Data System (ADS)

    Yi, Tae-Hyeong; Park, Ja-Rin

    2014-05-01

    A vertical finite element (VFE) discretization of hydrostatic primitive equations is developed for the dynamical core of a numerical weather prediction (NWP) system at KIAPS, which is horizontally discretized by a spectral element on a cubed-sphere grid. The governing equations are discretized on a hybrid pressure-based vertical coordinate [1]. Compared with a vertical finite difference (VFD) discretization, which is only first order accurate for non-uniform grids, the VFE has many advantages such that it gives more accurate results, all variables are defined in the same full level, the level of vertical noise might be reduced [2], and it is easily coupled with existing physics packages, developed for a Lorentz staggering grid system. Due to these reasons, we adopted the VFE scheme presented by Untch [2] for the vertical discretization. Instead of using semi-Lagrangian and semi-implicit schemes of ECMWF, we use the Eulerian equations and second-order Runge-Kutta scheme as the first step in implementing the VFE for the dynamical core of the KIAPS's NWP model. Since the Eulerian hydrostatic equations are used in this study, both integral and derivative operators are required to implement the VFE using the Galerkin method with b-splines as basis functions. To compare the accuracy of the VFE with the VFD, the two-dimensional test case of mountain waves is used where physical configuration and initial conditions are the same as that of Durran [3]. In this case, the horizontal and vertical velocities obtained by the analytical solution, VFD, VFE-linear and VFE-cubic are compared to understand their numerical features and the vertical flux of horizontal momentum is also presented as the measurement of solution accuracy since it is sensitive to errors in a solution [3]. It is shown that the VFE with a cubic b-spline function is more accurate than the VFD and VFE with a linear b-spline function as the vertical flux is closer to unity, which will be presented in the conference. Reference Simmons, A. J., Burridge, D. M., 1981: An energy and angular momentum conserving vertical finite difference scheme and hybrid vertical coordinates. Mon. Wea. Rev., 109, 758-766. Untch, A., Hortal, M., 2004: A finite-element schemes for the vertical discretization of the semi-Lagrangian version of the ECMWF forecast model. Q. J. R. Meteorol. Soc., 130, 1505-1530. Durran, D. R., Klemp, J. B., 1983: A compressible model for the simulation of moist mountain waves. Mon. Wea. Rev., 111, 2341-2361.

  4. Effect of Bearing Cleaning on Long Term Bearing Life

    NASA Technical Reports Server (NTRS)

    Jett, Tim; Thom, R. L.

    1999-01-01

    For many years chlorofluorocarbon (CFC) based solvents, such as CFC-113 and 1,1,1, trichloroethane (TCA), were used as bearing cleaning solvents for space mechanism bearings. 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 bearing cleaning. With this change the question arises; what effect if any do these new cleaners have on long term bearing life? The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings 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 bearings 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 bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition, the bearings were visually examined and analyzed using an optical microscope.

  5. Efficacy of Bear Deterrent Spray in Alaska

    Microsoft Academic Search

    Tom S. Smith; Stephen Herrero; Terry D. Debruyn; James M. Wilder

    2008-01-01

    We present a comprehensive look at a sample of bear spray incidents that occurred in Alaska, USA, from 1985 to 2006. We analyzed 83 bear spray incidents involving brown bears (Ursus arctos; 61 cases, 74%), black bears (Ursus americanus; 20 cases, 24%), and polar bears (Ursus maritimus; 2 cases, 2%). Of the 72 cases where persons sprayed bears to defend

  6. String and Sticky Tape Experiments: Light Pipes, Hydrostatics, Surface Tension and a Milk Carton.

    ERIC Educational Resources Information Center

    Edge, R. D., Ed.

    1984-01-01

    Describes a demonstration of light pipes using low-cost materials, relating it to fiber optics communication. Also provides several experiments in hydrostatics and hydrodynamics using the materials for light pipe. (JM)

  7. Identifying and quantifying nonconservative energy production/destruction terms in hydrostatic Boussinesq primitive equation models

    E-print Network

    Tailleux, Remi

    Identifying and quantifying nonconservative energy production/destruction terms in hydrostatic that physical inconsistencies between thermodynamics and dynamics usually introduce nonconservative production/destruction terms in the local total energy balance equation in numerical ocean general circulation models (OGCMs

  8. High hydrostatic pressure processing on microstructure of probiotic low-fat yogurt

    Microsoft Academic Search

    A. L. B. Penna; G. V. Barbosa-Cánovas

    2007-01-01

    The effect of milk processing on the microstructure of probiotic low-fat yogurt was studied. Skim milk fortified with skim milk powder was subjected to three treatments prior to innoculation: thermal treatment at 85°C for 30min, high hydrostatic pressure at 676MPa for 5min, and combined treatments of high hydrostatic pressure (HHP) and heat. The processed milk was then fermented by using

  9. Effect of hydrostatic pressure and salinity on the stability of gas hydrates

    Microsoft Academic Search

    Y. Paul. Handa

    1990-01-01

    The distribution of gas in the hydrate and the liquid phases for the two-phase systems methane hydrate-water and methane hydrate-seawater has been calculated as a function of hydrostatic pressure. It is found that at hydrostatic pressures higher than the three-phase hydrate-liquid-gas equilibrium pressure, a two-phase hydrate-liquid equilibrium exists in which the hydrate phase is increasingly enriched in and the liquid

  10. Calculation of RDX molecular crystal geometry and vibrational frequencies under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Perger, Warren; Slough, Wil

    2007-06-01

    First-principles calculations of the effects of hydrostatic pressure on RDX are performed using the all-electron CRYSTAL06 program. The lattice constants and optimized internal co-ordinates are simulanteously obtained at ambient pressure and hydrostatic pressure up to 4 GPa. A variety of density functionals and basis sets are used and presented for comparison. The vibrational frequencies as a function of pressure are also calculated and compared with previous gas-phase calculations.

  11. Effect of hydrostatic pressure on magnetostriction and magnetocrystalline anisotropy of magnetite

    Microsoft Academic Search

    Takesi Nagata; Hazimu Kinoshita

    1967-01-01

    The saturation magnetostriction coefficients, lambda100 and lambda111, and the magnetocrystalline anisotropy constants, K1 and K2, of single crystals of magnetite are measured under the effect of hydrostatic pressure P of 0-2 kbar in range at the room temperature. Both | lambda100 | and lambda111 increase with increasing hydrostatic pressure with rate of about 15%\\/kbar, whereas both | K1 | and

  12. Effect of high hydrostatic pressure on to life of the tiny animal tardigrade

    Microsoft Academic Search

    F. Ono; M. Saigusa; T. Uozumi; Y. Matsushima; H. Ikeda; N. L. Saini; M. Yamashita

    2008-01-01

    Terrestrial tardigrade is known to show very strong anti-environmental character at a dehydrated state called “tun” state. It was reported to be alive after exposed to the hydrostatic pressure of 0.6GPa, which was almost twice higher than the limit for most bacteria and multi-organisms. However, the limit of the hydrostatic pressure above which tardigrades cannot survive is unknown. We performed

  13. Dialogue for Kids Wild About Bears Sleepy Bear Lesson Plan

    NSDL National Science Digital Library

    Each winter, bears hunker down, slow their metabolisms, and pretty much wait out the winter in the safety of some sort of den. This lesson plan, from Idaho Public Television, is a fun way to illustrate to children (probably elementary grades primarily) the process of hibernation. At this site, educators are given the complete lesson plan instructions as well as several links to all sorts of great resources, including links to information on: Bear Diet, Home Range, Reproduction, Bear Research, People and Bears, more Classroom Activities, and more. And, the great addition to the site is a link to a 30-minute video about bears. While the site is somewhat focused on Idaho-specific bear information, teachers should be able to easily integrate the lesson no matter where you are.

  14. Ordered states of URu2Si2 under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Jeffries, J. R.; Butch, N. P.; Paglione, J.; Maple, M. B.

    2006-03-01

    Oriented single crystalline samples of URu2Si2 have been synthesized and investigated under nearly hydrostatic pressure via electrical resistivity and ac susceptibility measurements. The heavy fermion compound URu2Si2 exhibits three distinct ordered states as a function of temperature and pressure: ``hidden order'' (HO), in which the order parameter has yet to be determined; antiferromagnetism (AFM), which seemingly develops out of the HO state at P <=15 kbar; and superconductivity (SC), which exists at ambient pressure. Careful measurements of the HO transition, occurring at THO˜16.5 K at ambient pressure, have been performed at several different pressures, yielding a P-T phase diagram for the HO state as a function of pressure. In addition, measurements of the superconducting critical temperature, Tc˜1.4 K at ambient pressure, and the upper critical field Hc2 have been performed at low temperatures using a ^3He-^4He dilution refrigerator, revealing the superconducting H-T-P phase diagram. Possible correlations between the HO, AFM, and SC states will be discussed. This research was supported by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Research Grant No. DE-FG52-03NA00068.

  15. Optimization of hydrostatic transmissions by means of virtual instrumentation technique

    NASA Astrophysics Data System (ADS)

    Ion Guta, Dragos Daniel; Popescu, Teodor Costinel; Dumitrescu, Catalin

    2010-11-01

    Obtaining mathematical models, as close as possible to physical phenomena which are intended to be replicated or improved, help us in deciding how to optimize them. The introduction of computers in monitoring and controlling processes caused changes in technological systems. With support from the methods for identification of processes and from the power of numerical computing equipment, researchers and designers can shorten the period for development of applications in various fields by generating a solution as close as possible to reality, since the design stage [1]. The paper presents a hybrid solution of modeling / simulation of a hydrostatic transmission with mixed adjustment. For simulation and control of the examined process we have used two distinct environments, AMESim and LabVIEW. The proposed solution allows coupling of the system's model to the software control modules developed using virtual instrumentation. Simulation network of the analyzed system was "tuned" and validated by an actual model of the process. This paper highlights some aspects regarding energy and functional advantages of hydraulic transmissions based on adjustable volumetric machines existing in their primary and secondary sectors [2].

  16. Aerospace applications of magnetic bearings

    NASA Technical Reports Server (NTRS)

    Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard

    1994-01-01

    Magnetic bearings 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 bearings 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 bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing 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 bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.

  17. Effect of Bearing Cleaning on Long Term Bearing Life

    NASA Technical Reports Server (NTRS)

    Jett, Timothy Raymond; Thom, Robert L.

    1998-01-01

    For many years chlorofluorocarbon (CFC ) based solvents, such as Freon and 1,1,1, Trichloroethane (TCA), were used as bearing 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 bearing cleaning. With this change the question arises what effect if any do these new cleaners have on long term bearing life. The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0* 10(exp -6) torr) at a temperature of 90C. Prior to testing the bearings 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 bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition the bearings were visually examined and analyzed using an optical microscope.

  18. Totally frictionless magnetic bearing

    NASA Astrophysics Data System (ADS)

    Dodakian, Wayne; Bulman, John

    2000-11-01

    A totally frictionless magnetic bearing has been developed which supports a rotor in a contactless manner. The rotor is held in a magnetic potential well via repulsive forces only. Vertical and lateral restoring forces are provided to the rotor passively via permanent magnets in such an arrangement so as to support the weight of the rotor and provide it with a high degree of lateral stability. Axial stability of the rotor is provided by the use of an electromagnet which is controlled by a PID control loop. Information on the axial position of the rotor is provided to the circuit by use of an infrared LED and IR phototransistor. To prevent unwanted oscillations of the rotor’s axial position from occurring, an oscillation sensor in the form of an inductive pick-up coil of high impedance provides signals to the oscillation sensing portion of the circuit, which in turn feeds the oscillation dampening circuit. The use of only repulsive forces in stabilizing the rotor means that there will be no eddy current losses or hysterisis losses. Such a frictionless magnetic bearing can, for example be used in rotational oscillation experiments and ultra low loss watt-hour meters, which are of great importance to utility companies. When properly tuned, the total power requirements of the circuit is a mere 40mW, which is less than the 80 mW used by present day watt-hour meters.

  19. The transition from hydrostatic to greater than hydrostatic fluid pressure in presently active continental hydrothermal systems in crystalline rock

    SciTech Connect

    Fournier, R.O. (Geological Survey, Menlo Park, CA (United States))

    1991-05-01

    Fluid flow at hydrostatic pressure (P{sub h}) is relatively common through fractures in silicic and in mafic crystalline rocks where temperatures are less than about 350-370C. In contrast, pore-fluid pressure (P{sub f}) > P{sub h} has been encountered at the bottom of 3 geothermal exploration wells that attained temperatures >370C (at Larderello, Italy, at Nesjavellir, Iceland, and at The Geysers, California). Chemical sealing by deposition of minerals in veins appears to have allowed the development of the high P{sub f} encountered in the above wells. The upper limit for the magnitude of P{sub f} that can be attained is controlled by either the onset of shear fracturing (where differential stress is relatively high) that reopens clogged veins, or the hydraulic opening of new or old fractures (at relatively low values of differential stress). The brittle-plastic transition for silicic rocks can occur at temperatures as high as 370-400C in tectonically active regions. In regions where high-temperature geothermal systems develop and persist, it appears that either strain rates commonly are in the range 10{sup {minus}12} to 10{sup {minus}13}, or that silicic rocks in the shallow crust generally behave rheologically more like wet quartz diorite than wet Westerly granite.

  20. Robust and intelligent bearing estimation

    DOEpatents

    Claassen, John P. (Albuquerque, NM)

    2000-01-01

    A method of bearing estimation comprising quadrature digital filtering of event observations, constructing a plurality of observation matrices each centered on a time-frequency interval, determining for each observation matrix a parameter such as degree of polarization, linearity of particle motion, degree of dyadicy, or signal-to-noise ratio, choosing observation matrices most likely to produce a set of best available bearing estimates, and estimating a bearing for each observation matrix of the chosen set.

  1. Primarily Pro-bear-bility

    NSDL National Science Digital Library

    2006-01-01

    In this probability lesson plan students make predictions about the color of the bear they are likely to draw from a bag, and then draw and record the color of the bear they actually draw. Students complete this activity in cooperative learning groups and take turns removing a bear, without replacing it, and seeing if their predictions become more accurate. The lesson plan includes four student activity worksheets and extension questions and suggestions (PDF).

  2. A Semi-Hydrostatic Theory of Gravity-Dominated Compressible Flow

    NASA Astrophysics Data System (ADS)

    Dubos, T.; Voitus, F.

    2014-12-01

    Compressible Euler equations support the propagation of acoustic waves. Although much progress has been achieved towards efficient and accurate solutions to the resulting numerical difficulties, it can still be desirable to identify "unified" equations of motion that would not support acoustic waves while retaining accuracy at large and small scales. Even if such equations are eventually not chosen as the basis of a numerical model, they may help identifying the independent degrees of freedom of the atmospheric flow to be modeled and how the dependent fields are related to the independent fields. From Hamilton's least action principle (HP), "semi-hydrostatic" compressible equations of motion with density diagnosed from potential temperature through hydrostatic balance are derived. Energy, potential vorticity and momentum are conserved. Slaving density to potential temperature suppresses the degrees of freedom supporting the propagation of acoustic waves and results in a sound-proof system. Scale analysis and linear normal modes analysis for an isothermal state of rest suggest that the semy-hydrostatic system is accurate from hydrostatic to non-hydrostatic scales, except for deep internal gravity waves (Figure : decimal logarithm of relative error of the frequency of internal normal modes of a non-rotating isothermal atmosphere as a function of horizontal and vertical wavenumbers k,m normalized by the scale height H). Especially the Lamb wave and long Rossby waves are not distorted, unlike with anelastic or pseudo-incompressible systems. Compared to similar equations derived by Arakawa and Konor (2009), the semi-hydrostatic system possesses an additional term in the horizontal momentum budget. This term is an apparent force resulting from the vertical coordinate not being the actual height of an air parcel, but its hydrostatic height, i.e. the hypothetical height it would have after the atmospheric column it belongs to has reached hydrostatic balance through adiabatic vertical displacements of air parcels. As with hydrostatic prmitive equations (HPE), vertical velocity is diagnosed through Richardson's equation. The semi-hydrostatic system has therefore precisely the same degrees of freedom as the HPE, while retaining much of the accuracy of the fully compressible Euler equations.

  3. Spin bearing retainer design optimization

    NASA Technical Reports Server (NTRS)

    Boesiger, Edward A.; Warner, Mark H.

    1991-01-01

    The dynamics behavior of spin bearings for momentum wheels (control-moment gyroscope, reaction wheel assembly) is critical to satellite stability and life. Repeated bearing retainer instabilities hasten lubricant deterioration and can lead to premature bearing failure and/or unacceptable vibration. These instabilities are typically distinguished by increases in torque, temperature, audible noise, and vibration induced by increases into the bearing cartridge. Ball retainer design can be optimized to minimize these occurrences. A retainer was designed using a previously successful smaller retainer as an example. Analytical methods were then employed to predict its behavior and optimize its configuration.

  4. Retinal ganglion cell line apoptosis induced by hydrostatic pressure.

    PubMed

    Agar, Ashish; Li, Shaojuan; Agarwal, Neeraj; Coroneo, Minas T; Hill, Mark A

    2006-05-01

    Cellular responses to changes in pressure are implicated in numerous disease processes. In glaucoma apoptosis of retinal ganglion cells (RGCs) is associated with elevated intra-ocular pressure, however, the exact cellular mechanisms remain unclear. We have previously shown that pressure can induce apoptosis in B35 and PC12 neuronal cell lines, using an in vitro model for pressure elevation. A novel RGC line allows us to study the effects of pressure on retinal neurons. 'RGC-5' cultures were subjected to elevated ambient hydrostatic pressure conditions in our model. Experimental pressure conditions were 100 mm Hg and 30 mm Hg, representing acute (high) and chronic (lower-pressure) glaucoma, and 15 mm Hg for normal intra-ocular pressure, set above atmospheric pressure for 2 h. Negative controls were treated identically except for the application of pressure, while positive controls were generated by treatment with a known apoptotic stimulus. Apoptosis was determined by a combination of cell morphology and specific TUNEL and Annexin V fluorescent markers. These were assessed simultaneously by laser scanning cytometry (LSC), which also enabled quantitative marker analysis. RGC-5 neurons showed a significantly increased proportion of apoptotic cells compared with controls; maximal at 100 mm Hg, moderate at 30 mm Hg and not statistically significant at 15 mm Hg. This graded response, proportionate to the level of pressure elevation, is representative of the severity of analogous clinical settings (acute, chronic glaucoma and normal). These results complement earlier findings of pressure-induced apoptosis in other neuronal cultures. They suggest the possibility of novel mechanisms of pressure-related mechanotransduction and cell death, relevant to the pathogenesis of diseases such as glaucoma. PMID:16638612

  5. Study of Catcher Bearings for High Temperature Magnetic Bearing Application 

    E-print Network

    Narayanaswamy, Ashwanth

    2011-08-08

    for catcher bearing material need to be done. A dynamic model needs to be designed for studying and simulating the rotor drop of the shaft onto the catcher bearing using a finite element approach in MATLAB. The assembly of the test rig was completed...

  6. Analysis of Bearing Incidents in Aircraft Gas Turbine Mainshaft Bearings

    Microsoft Academic Search

    B. L. Averbach; E. N. Bamberger

    1991-01-01

    An examination of approximately 200 bearing incidents in current aircraft engines has shown that damage in the bearing is initiated at the surface. Twenty-one cases were studied in detail, and five typical incidents are presented here. The initial damage was produced by abrasive particles, dents, grinding scores, skidding, large carbides and corrosion pits. The first phase of the failure mechanism

  7. A non-hydrostatic algorithm for free-surface ocean modelling

    NASA Astrophysics Data System (ADS)

    Auclair, Francis; Estournel, Claude; Floor, Jochem W.; Herrmann, Marine; Nguyen, Cyril; Marsaleix, Patrick

    An original implementation of a non-hydrostatic, free-surface algorithm based on a pressure correction method is proposed for ocean modelling. The free surface is implemented through an explicit scheme combined with a mode-spitting method but the depth-averaged velocity and the position of the free surface are updated at each non-hydrostatic iteration. The vertical momentum equation is also integrated up to the surface enabling a natural and accurate treatment of the surface layer. The consistent specification of the numerical schemes provides balanced transfers of potential and kinetic energy. This algorithm is well-suited for implementation as a non-hydrostatic kernel on originally hydrostatic free-surface ocean models such as Symphonie ( http://poc.obs-mip.fr/pages/research_topics/modelling/symphonie/symphonie.htm) for which it has originally been developed. Energy balances associated with the propagation of short surface waves and solitary waves are presented for two dedicated well-documented configurations over closed domains. The buoyancy flux, the work rate of the pressure force together with the power of the advective terms are evaluated and discussed for the generation and the propagation of these two types of waves. The dissipation rate is in particular shown to be several orders of magnitude smaller than the work rates of the hydrostatic and non-hydrostatic pressure forces confirming the necessity for the exchanges of energy to be numerically balanced. The algorithm is subsequently applied to the complex generation of non-linear solitary internal waves by surface tides over Georges Bank, in the Gulf of Maine. The generation and the propagation of the observed non-linear and non-hydrostatic features in this region are correctly reproduced.

  8. Responses of different cell lines from ocular tissues to elevated hydrostatic pressure

    PubMed Central

    Wax, M.; Tezel, G.; Kobayashi, S.; Hernandez, M

    2000-01-01

    BACKGROUND/AIMS—Mechanical forces are thought to induce cellular responses through activation of signalling pathways. Cells within the intraocular environment are exposed to constant changes in the levels of intraocular pressure. In this study, an attempt was made to determine the acute effects of elevated hydrostatic pressure on different intraocular cells grown in culture.?METHODS—Different cell lines derived from ocular tissues including non-pigmented and pigmented ciliary epithelium, trabecular meshwork, retina, and lamina cribrosa were incubated in a pressurised chamber at 50 mm Hg in a culture incubator at 37°C for up to 6 hours. Control cells were incubated at atmospheric pressure. The viability of the cells was examined using their intracellular esterase activity. The morphology and cytoskeleton of the cells were investigated using microscopy and phalloidin staining. Adenylyl cyclase activity was assessed by measuring the conversion of [3H]-cAMP from [3H]-ATP in response to elevated hydrostatic pressure for 1-6 hours. In addition, at the end of incubation period under elevated hydrostatic pressure the recovery of adenylyl cyclase activity to control levels was examined.?RESULTS—Cell viability did not change following exposure to elevated hydrostatic pressure for 6 hours. Cells subjected to elevated hydrostatic pressure demonstrated morphological differences characterised by a more rounded shape and a redistribution of actin stress fibres that was most prominent in lamina cribrosa astrocytes. A time dependent increase in basal adenylyl cyclase activity, and a decrease in maximum forskolin stimulated activity were observed in all cell lines following exposure to elevated hydrostatic pressure.?CONCLUSION—These observations demonstrate that cell lines from different ocular tissues are sensitive to changes in external pressure in vitro. They exhibit morphological and cytoskeletal changes as well as significant alterations of intracellular adenylyl cyclase activity following exposure to acute and sustained levels of elevated hydrostatic pressure of up to 6 hours' duration.?? PMID:10729303

  9. Superconducting levitating bearing

    NASA Technical Reports Server (NTRS)

    Moon, Francis C. (Inventor)

    1996-01-01

    A superconducting bearing assembly includes a coil field source that may be superconducting and a superconducting structure. The coil field source assembly and superconducting structure are positioned so as to enable relative rotary movement therebetween. The structure and coil field source are brought to a supercooled temperature before a power supply induces a current in the coil field source. A Meissner-like effect is thereby obtained and little or no penetration of the field lines is seen in the superconducting structure. Also, the field that can be obtained from the superconducting coil is 2-8 times higher than that of permanent magnets. Since the magnetic pressure is proportioned to the square of the field, magnetic pressures from 4 to 64 times higher are achieved.

  10. Introduction to magnetic bearings

    NASA Technical Reports Server (NTRS)

    Skowronski, Lori; Bisese, Anne

    1993-01-01

    Multi-axis suspension has several advantages over single axis system, in that it provides control of an object with precision in two or three orthogonal axes. In this report, we discuss the primary use of magnetic-bearing suspension and it's relevance to what was formally known as NASA's Annular Suspension and Pointing System (ASPS). This system is an experimental pointing system with applications for the space shuttle and the space station programs. The objectives behind this magnetic suspension research project are to provide insight to the use of the ASPS configuration, to control the solar panels of the space station. This is important to maintain the correct position of the panels in relation to the sun and orbiting space station for the continuous supply of solar energy. Since the panels are suspended, they can be aligned with minimum outside interference. The approach of using magnetic suspension technology guarantees mechanical isolation since there are no contacting surfaces. This isolation reduces vibration transmission and mechanical wear which in turn extends the life of the payload and of the carrier. It should be noted that ASPS has a high pointing accuracy along the line of 0.01 arc-second. This research will be done in a laboratory setting by incorporating five bearing stations and one motion control station. We will attempt to suspend an object of dead weight similar to that of a solar panel. The long term applications may include deep-space navigation, fire control in weapon systems, and an improved mass transit system.

  11. Adaptive Spindle Balancing Using Magnetically Levitated Bearings

    Microsoft Academic Search

    PATRICK S. BARNEY; JAMES P. LAUFFER; REBECCA PETTEYS; JAMES M. REDMOND; WILLIAM N. SULLIVAN

    1999-01-01

    A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The

  12. Service Lives Of Restored Bearings

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1988-01-01

    Rebuilt units last almost as long as new ones. Report describes theoretical and experiemental studies of lifetimes of restored ball and cylindrical-roller bearings. Results of this and related studies have implications of economy and safety in modern high-speed machinery, especially in aircraft industry, where inspection and rejection or replacing of bearings are new standard practice.

  13. Zero-Deadband Ball Bearings

    NASA Technical Reports Server (NTRS)

    Hine, Michael J.

    1988-01-01

    Proposed supports for ball bearings press outer races against balls without radial clearance. Diaphragm-like axially flexible springs eliminate deadband and consequent nonlinear radial vibrational response of rotor. If shaft needs two bearings at each end, they are supported independently or connected in series by U-spring. Mechanical stops limit axial travel of shaft.

  14. Polar Bears and Climate Change

    NSDL National Science Digital Library

    Andrew E. Derocher (University of Alberta, Canada; )

    2008-05-01

    The issue-focused, peer reviewed article discusses how a warming climate is altering sea ice conditions, which affects polar bears in many ways, including more difficulty in getting to and hunting prey, fewer den areas and lower cub survival, increased interactions between bears and humans, and lower survival rate of the species in general.

  15. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-26

    ...Federal Energy Regulatory Commission [Project Nos. 2710-061; 2712-078] Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and...

  16. Residual Gas Motions in the Intracluster Medium and Bias in the Hydrostatic Mass Profile

    NASA Astrophysics Data System (ADS)

    Lau, Erwin; Kravtsov, A.; Nagai, D.

    2010-01-01

    We present analysis of bulk and random gas motions in the intracluster medium using high-resolution Eulerian cosmological simulations of sixteen simulated clusters, including both very relaxed and unrelaxed systems. We investigate effects of the residual subsonic gas motions on the hydrostatic estimates of mass profiles and concentrations of galaxy clusters. In agreement with previous studies we find that the gas motions contribute up to 5%-15% of the total pressure support in relaxed clusters with contribution increasing with cluster-centric radius. The fractional pressure support is higher in unrelaxed systems. This contribution would not be accounted for in hydrostatic estimates of the total mass profile and would lead to systematic underestimate of mass. We demonstrate that total mass can be recovered accurately if pressure due to gas motions measured in simulations is explicitly taken into account in the equation of hydrostatic equilibrium. Given that the underestimate of mass is increasing at larger radii, where gas is less relaxed and contribution of gas motions to pressure is larger, the total density profile derived from hydrostatic analysis is more concentrated than the true profile. This may at least partially explain some high values of concentrations of clusters estimated from hydrostatic analysis of X-ray data.

  17. Performance of an Electro-Hydrostatic Actuator on the F-18 Systems Research Aircraft

    NASA Technical Reports Server (NTRS)

    Navarro, Robert

    1997-01-01

    An electro-hydrostatic actuator was evaluated at NASA Dryden Flight Research Center, Edwards, California. The primary goal of testing this actuator system was the flight demonstration of power-by-wire technology on a primary flight control surface. The electro-hydrostatic actuator uses an electric motor to drive a hydraulic pump and relies on local hydraulics for force transmission. This actuator replaced the F-18 standard left aileron actuator on the F-18 Systems Research Aircraft and was evaluated throughout the Systems Research Aircraft flight envelope. As of July 24, 1997 the electro-hydrostatic actuator had accumulated 23.5 hours of flight time. This paper presents the electro-hydrostatic actuator system configuration and component description, ground and flight test plans, ground and flight test results, and lessons learned. This actuator performs as well as the standard actuator and has more load capability than required by aileron actuator specifications of McDonnell- Douglas Aircraft, St. Louis, Missouri. The electro-hydrostatic actuator system passed all of its ground tests with the exception of one power-off test during unloaded dynamic cycling.

  18. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2013-10-01 2013-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  19. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 2011-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  20. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2012-10-01 2012-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  1. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 2010-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  2. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 2014-10-01 2014-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  3. Remanent magnetization and coercivity of rocks under hydrostatic pressure up to 1.4 GPa

    NASA Astrophysics Data System (ADS)

    Demory, F.; Rochette, P.; Gattacceca, J.; Gabriel, T.; Bezaeva, N. S.

    2013-08-01

    We designed an Isothermal Remanent Magnetization (IRM) acquisition system based on permanent magnets and sized to accommodate an amagnetic hydrostatic pressure cell. This pressure cell fits in a superconducting rock magnetometer, allowing for the measurement of remanent magnetization of pressurized samples. With this system, we determined the coercivity of remanence (Bcr) at different hydrostatic pressures up to 1.4 GPa for rock and dispersed mineral samples with various magnetic mineralogy and domain state. IRM and Bcr are nearly identical before compression and after decompression, indicating no permanent changes in the magnetic properties during pressure cycling. Hydrostatic pressure up to 1.4 GPa does not significantly increases IRM under pressure except for multidomain pyrrhotite and magnetite which show an increase of about 40%. Relative increase of Bcr under pressure is mild, except for a near single domain titanomagnetite where Bcr doubles.

  4. On variable hydrostatic transmission for road vehicles, powered by supply of fluid at constant pressure

    NASA Astrophysics Data System (ADS)

    Magi, M.; Freivald, A.; Andersson, I.; Ericsson, U.

    1981-05-01

    Various hydrostatic power transmission systems for automotive applications with power supply at constant pressure and unrestricted flow and with a Volvo Flygmotor variable displacement motor as the principal unit were investigated. Two most promising concepts were analyzed in detail and their main components optimized for minimum power loss at the EPA Urban Driving Cycle. The best fuel consumption is less than 10 lit. per 100 kM for a 1542 kG vehicle with a hydrostatic motor and a two speed gear box in series (braking power not recovered). Realistic system pressure affects the fuel consumption just slightly, but the package volume/weight drastically. Back pressure increases losses significantly. Special attention was paid to description of the behavior and modeling of the losses of variable displacement hydrostatic machines.

  5. Magnetic Bearings at Draper Laboratory

    NASA Technical Reports Server (NTRS)

    Kondoleon, Anthony S.; Kelleher, William P.; Possel, Peter D.

    1996-01-01

    Magnetic bearings, unlike traditional mechanical bearings, 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 bearing system including the touch down bearing. 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 bearing development. A 3-D radial magnetic bearing 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 bearing is also included in this paper.

  6. 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.

  7. Combined use of infrared and Raman spectra in the characterization of orthoclase under various hydrostatic pressures.

    PubMed

    Liu, Rui; Wang, Zhi-Hua; Xu, Qiang; Yu, Na; Cao, Miao-Cong

    2014-02-01

    Colorless and pink orthoclase from Balikun granite body, East Zhunger in Xinjiang, served as the samples for the research on hydrostatic pressure experiment. The in-situ hydrostatic pressure test for orthoclases was conducted at the room temperature and pressures from 100 to 600 MPa using cubic zirconia anvil cell, with quartz as pressure gauge. The water located in the orthoclases for the conditions of different hydrostatic pressures was characterized through the methods of Fourier transform infrared (FTIR) and Raman spectra. The results showed that there was a linear correlation between the shifting of Raman bands and hydrostatic pressure applied to the feldspar. All of vibration peaks of M-O structural groups in orthoclases, the bending vibration peaks of Si(Al(IV))-O-Si bond and tetrahedron groups of [SiO4] in Raman spectra shifted toward the higher frequency regularly, the drift distance is 2, 2.19 and less than 2 cm(-1) respectively. The spectra of FTIR suggested that there was more water in colorless orthoclases than the pink one under certain conditions of hydrostatic pressure. The intensity and integral area centered at 3420 cm(-1) in FTIR spectra increased with the rising of hydrostatic pressure. The integral area for colorless and pink feldspar in FTIR spectra rose from 120, 1383 cm(-1) under normal pressure to 1570, 2001 cm(-1) at 600 MPa respectively. The experimental results might indicate that the water in the earth crust could enter the orthoclases in certain condition of the aqueous confining pressure. PMID:24822414

  8. Numerical Simulation of Damage during Forging with Superimposed Hydrostatic Pressure by Active Media

    NASA Astrophysics Data System (ADS)

    Behrens, B.-A.; Hagen, T.; Röhr, S.; Sidhu, K. B.

    2007-05-01

    The effective reduction of energy consumption and a reasonable treatment of resources can be achieved by minimizing a component's weight using lightweight metals. In this context, aluminum alloys play a major role. Due to their material-sided restricted formability, the mentioned aluminum materials are difficult to form. The plasticity of a material is ascertained by its maximum forming limit. It is attained, when the deformation causes mechanical damage within the material. Damage of that sort is reached more rapidly, the greater the tensile strength rate in relation to total tension rate. A promising approach of handling these low ductile, high-strength aluminum alloys within a forming process, is forming with a synchronized superposition of comprehensive stress by active media such as by controlling oil pressure. The influence of superimposed hydrostatic pressure on the flow stress was analyzed as well as the formability for different procedures at different hydrostatic pressures and temperature levels. It was observed that flow stress is independent of superimposed hydrostatic pressure. Neither the superimposed pressure has an influence on the plastic deformation, nor does a pressure dependent material hardening due to increasing hydrostatic pressure take place. The formability increases with rising hydrostatic pressure. The relative gain at room temperature and increase of the superimposed pressure from 0 to 600 bar for tested materials was at least 140 % and max. 220 %. Therefore in this paper, based on these experimental observations, it is the intended to develop a numerical simulation in order to predict ductile damage that occurs in the bulk forging process with superimposed hydrostatic pressure based Lemaitre's damage model.

  9. Numerical modeling of multidimensional flow in seals and bearings used in rotating machinery

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Tam, L. T.; Przekwas, A.; Muszynska, A.; Braun, M. J.; Mullen, R. L.

    1988-01-01

    The rotordynamic behavior of turbomachinery is critically dependent on fluid dynamic rotor forces developed by various types of seals and bearings. The occurrence of self-excited vibrations often depends on the rotor speed and load. Misalignment and rotor wobbling motion associated with differential clearance were often attributed to stability problems. In general, the rotative character of the flowfield is a complex three dimensional system with secondary flow patterns that significantly alter the average fluid circumferential velocity. A multidimensional, nonorthogonal, body-fitted-grid fluid flow model is presented that describes the fluid dynamic forces and the secondary flow pattern development in seals and bearings. Several numerical experiments were carried out to demonstrate the characteristics of this complex flowfield. Analyses were performed by solving a conservation form of the three dimensional Navier-Stokes equations transformed to those for a rotating observer and using the general-purpose computer code PHOENICS with the assumptions that the rotor orbit is circular and that static eccentricity is zero. These assumptions have enabled a precise steady-state analysis to be used. Fluid injection from ports near the seal or bearing center increased fluid-film direct dynamic stiffness and, in some cases, significantly increased quadrature dynamic stiffness. Injection angle and velocity could be used for active rotordynamic control; for example, injection, when compared with no injection, increased direct dynamic stiffness, which is an important factor for hydrostatic bearings.

  10. A low-friction high-load thrust bearing and the human hip joint.

    PubMed

    McIlraith, A H

    2010-06-01

    A hydrostatic thrust bearing 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 contacting 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 contact and the torque needed to rotate the bearing are given in terms of its geometry, the viscosity of the lubricant and elapsed time. The mechanism of a bearing with similar geometry and properties, the human hip joint, is compared with this plastic bearing. 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. PMID:20498516

  11. Random Bearings and Their Stability

    NASA Astrophysics Data System (ADS)

    Baram, Reza Mahmoodi; Herrmann, Hans J.

    2005-11-01

    Self-similar space-filling bearings have been proposed some time ago as models for the motion of tectonic plates and appearance of seismic gaps. These models have two features which, however, seem unrealistic, namely, high symmetry in the arrangement of the particles, and lack of a lower cutoff in the size of the particles. In this work, an algorithm for generating random bearings in both two and three dimensions is presented. Introducing a lower cutoff for the sizes of the particles, the instabilities of the bearing under an external force such as gravity, are studied.

  12. Effect of hydrostatic pressure on the crystal structure of sodium oxalate: X-ray diffraction study and ab initio simulations

    E-print Network

    Oganov, Artem R.

    -induced phase transitions in sodium oxalate is discussed. Introduction Oxalates are widely used in the designEffect of hydrostatic pressure on the crystal structure of sodium oxalate: X-ray diffraction study diffraction structure analysis / X-ray diffraction / Sodium oxalate Abstract. Effect of hydrostatic pressures

  13. An implicit finite-element model for 3D non-hydrostatic mesoscale ocean M.A. Maidana1

    E-print Network

    Politècnica de Catalunya, Universitat

    An implicit finite-element model for 3D non-hydrostatic mesoscale ocean flows M.A. Maidana1 , J-dimensional, non-hydrostatic mesoscale ocean flows. The model considered here incorporates surface wind stress and the idea of using unstructured grids for modelling mesoscale ocean dynamics sounds very attractive given

  14. Hydrostatic Mooring System. Final Technical Report: Main Report plus Appendices A, B, and C - Volume 1 and 2

    Microsoft Academic Search

    Jens Korsgaard

    2000-01-01

    The main conclusions from the work carried out under this contract are: An ordinary seafarer can learn by training on a simulator, to moor large tanker vessels to the Hydrostatic Mooring, safely and quickly, in all weather conditions up to storms generating waves with a significant wave height of 8 m. Complete conceptual design of the Hydrostatic Mooring buoy was

  15. High-temperature bearing lubricants

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.; Parker, R. J.; Zaretsky, E. V.

    1968-01-01

    Synthetic paraffinic oil lubricates ball bearings at temperatures in the 600 degrees F range. The lubricant contains antiwear and antifoam additives, is thermally stable in the high temperature range, but requires protection from oxygen.

  16. ATM CMG bearing failure analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The cause or causes for the failure of ATM CMG S/N 5 (Skylab 1) and the anomalies associated with ATM CMG S/N 6 (Skylab 2) were investigated. Skylab telemetry data were reviewed and presented in the form of parameter distributions. The theory that the problems were caused by marginal bearing lubrication was studied along with the effects of orbital conditions on lubricants. Bearing tests were performed to investigate the effect of lubricant or lack of lubricant in the ATM CMG bearings and the dispersion and migration of the lubricant. The vacuum and weightless conditions of space were simulated in the bearing tests. Analysis of the results of the tests conducted points to inadequate lubrication as the predominant factor causing the failure of ATM CMG S/N 5 (Skylab 1) and the anomalies associated with ATM CMG S/N 6 (Skylab 2).

  17. A Passive Magnetic Bearing Flywheel

    NASA Technical Reports Server (NTRS)

    Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

    2002-01-01

    A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  18. Flex bearing UUEC, volume 2

    NASA Technical Reports Server (NTRS)

    Clapper, M. L.

    1993-01-01

    This volume, Volume 2, of this Flex Bearing UUEC Final Report documents findings and data pertaining to Team B's tasks. Team B was organized as one of two sub-teams of the Unplanned/Unintended Event or Condition (UUEC) board established per InterOffice Memorandum (IOM) A100-FY93-072. Team A determined the cause of the unacceptable unbonds (referred to as 'heat-affect' unbonds), including the initial, light rust film, in the FSM #3 flex bearing was overheating of the Forward End Ring (FER) during cure, specifically in zone 8 of the mold. Team A's findings are documented in Volume 1 of this report. Team B developed flight rationale for existing bearings, based on absence or presence of an unpropitious unbond condition like that in FSM #3's flex bearing.

  19. Testing and Lubrication for Single Race Bearings

    SciTech Connect

    Steinhoff, R.G.

    1998-03-04

    Three ES and H-compatible lubricants (Environment, Safety and Health) for single race bearing applications and one hybrid-material single race bearings were evaluated and compared against single race bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in stronglink mechanisms since 1974. Hybrid bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, bearings lubricated with titanium carbide (TiC) on the balls, bearings lubricated with sputtered MoS{sub 2} on races and retainers, and bearings lubricated with electrophoretically deposited MoS{sub 2} were evaluated. The bearings were maintained in a preloaded state in bearing cartridges during cycling and vibration tests. Bearings with electrophoretically deposited MoS{sub 2} performed as well as bearings lubricated with Vydax and were the best performing candidate. All candidates were suitable for low preload applications. Bearings with TiC coated balls and bearings lubricated with sputtered MoS{sub 2} on the races and retainers performed well at high preloads, though not as well as bearings lubricated with electrophoretic deposition of MoS{sub 2}. Bearings with silicon nitride balls were not suitable for high preload applications.

  20. Improved Superconducting Magnetic Rotary Bearings

    NASA Technical Reports Server (NTRS)

    Flom, Yury; Royston, James

    1992-01-01

    Improved magnetic rotary bearings designed by exploiting properties of type-II superconducting materials. Depending on design and application, bearing provides fixed or adjustable compensation for lateral vector component of weight or other lateral load on rotor. Allows applied magnetic field to penetrate partially in clusters of field lines, with concomitant establishment of undamped circulating electrical currents within material. Type-II superconductors have critical magnetic fields and critical temperatures greater than type-I superconductors.

  1. Teddy Bear Line-Up

    NSDL National Science Digital Library

    This problem requires children to develop logical reasoning and promotes using visualization to plan ahead. Students are presented with a line of four blue, then four red followed by four yellow and finally four green bears and are asked to rearrange them using the least number of moves so that no two bears of the same color are next to each other. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, and an idea for support and extension.

  2. Designing Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Moore, James D., Jr.

    2007-01-01

    Bearing Analysis Tool (BAT) is a computer program for designing rolling-element bearings for cryogenic turbomachines. BAT provides a graphical user interface (GUI) that guides the entry of data to develop mathematical models of bearings. The GUI breaks model data into logical subsets that are entered through logic-driven input screens. The software generates a threedimensional graphical model of a bearing as the data are entered. Most dataentry errors become immediately obvious in the graphical model. BAT provides for storage of all the data on a shaft/bearing system, enabling the creation of a library of proven designs. Data from the library can be transferred to subsequent projects by use of simple cut-and-paste routines. BAT includes a library of temperature- dependent cryogenic bearing-material properties for use in the mathematical models. BAT implements algorithms that (1) enable the user to select combinations of design and/or operating-condition parameters, and then (2) automatically optimize the design by performing trade studies over all of the parameter combinations. This feature enables optimization over a large trade space in a fraction of the time taken when using prior bearingmodel software.

  3. Roller bearings for I. C. engines

    Microsoft Academic Search

    M. Mc Kenzie; R. Lugosi

    1987-01-01

    Analyses indicate that lower heat generation, smaller friction coefficients, and thinner lubricant films will occur if roller bearings replace today's journal bearings. Results indicate that, for the conditions selected, the roller bearing operates at a lower coefficient of friction and exhibits less heat generation than the journal bearing. These benefits can conceivably be translated into significantly better cold start characteristics,

  4. Damping Seals And Bearings For A Turbomachine

    NASA Technical Reports Server (NTRS)

    Von Pragenau, George L.

    1990-01-01

    Improved design for support of rotor in turbopump integrates ball bearings with damping seals and damping bearings. Reduces radial (side) loads on ball bearings, making it possible to increase contact angles to withstand increased transient axial loads. Service lives of bearings prolonged.

  5. Customized Wavelet for Bearing Defect Detection

    Microsoft Academic Search

    Brian T. Holm-Hansen; Robert X. Gao; ASME Mem

    2004-01-01

    Rolling element bearings play a critical role in dynamic sys- tems, ranging from paper mills to aircrafts, and unexpected bear- ing failures may result in significant economic losses, even loss of lives. The significance of maintaining effective and safe bearing operations has led to the development of a wide range of bearing condition monitoring and diagnostic techniques over the past

  6. Magnetic Bearing Sets for a Flywheel System

    Microsoft Academic Search

    Guilherme Goncalves Sotelo; R. de Andrade; A. C. Ferreira

    2007-01-01

    This paper presents a magnetic bearing set developed to work in a flywheel energy storage system. The bearing set is composed of a permanent magnetic bearing (PMB) and a superconducting magnetic bearing (SMB). A new configuration of a PMB having Nd-Fe-B magnet rings and a back yoke is proposed and compared with an existing one. Finite element method (FEM) simulations

  7. 46 CFR 54.10-10 - Standard hydrostatic test (modifies UG-99).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...pressure vessel, multiplied by the ratio of the stress value “S” at the test temperature to the stress value “S” at the design temperature for...No ratio less than one shall be used. The stress resulting from the hydrostatic test...

  8. 46 CFR 54.10-10 - Standard hydrostatic test (modifies UG-99).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...pressure vessel, multiplied by the ratio of the stress value “S” at the test temperature to the stress value “S” at the design temperature for...No ratio less than one shall be used. The stress resulting from the hydrostatic test...

  9. 46 CFR 54.10-10 - Standard hydrostatic test (modifies UG-99).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...pressure vessel, multiplied by the ratio of the stress value “S” at the test temperature to the stress value “S” at the design temperature for...No ratio less than one shall be used. The stress resulting from the hydrostatic test...

  10. Non-Hydrostatic Wave Model NHWAVE User's Guide for Modeling Submarine Landslide Tsunami

    E-print Network

    Kirby, James T.

    Non-Hydrostatic Wave Model NHWAVE User's Guide for Modeling Submarine Landslide Tsunami ( Version 1 of submarine landslide-induced tsunami waves. NHWAVE was de- veloped by Ma et al. (2012) for modeling fully a surface and terrain in the sigma co- ordinate system. Tsunami waves generated by a prescribed submarine

  11. Alteration of citrine structure by hydrostatic pressure explains the accompanying spectral shift

    E-print Network

    Gruner, Sol M.

    Alteration of citrine structure by hydrostatic pressure explains the accompanying spectral shift this relationship, we have investigated a fluorescent protein, citrine, as a model system under high shift of citrine from yellow to green under these conditions. This protein is therefore highly sensitive

  12. Adaptive hydrostatic blood pressure calibration: Development of a wearable, autonomous pulse wave velocity blood pressure monitor

    Microsoft Academic Search

    Devin B. McCombie; Phillip A. Shaltis; Andrew T. Reisner; H. Harry Asada

    2007-01-01

    A technique for calibrating non-invasive peripheral arterial sensor signals to peripheral arterial blood pressure (BP) is proposed. The adaptive system identification method utilizes a measurable intra-arterial hydrostatic pressure change in the sensor outfitted appendage to identify the transduction dynamics relating the peripheral arterial blood pressure and the measured arterial sensor signal. The proposed algorithm allows identification of the calibration dynamics

  13. Using the Changes in Hydrostatic Pressure and Pulse Transit Time to Measure Arterial Blood Pressure

    Microsoft Academic Search

    Carmen C. Y. Poon; Y. T. Zhang

    2007-01-01

    The pulse transit time (PTT)-based method has been proposed as a noninvasive and cuffless alternative for monitoring blood pressure (BP). Yet, a major challenge of the technology is to overcome the requirement of individual calibration. In this study, we aim to explore the possibility of using the changes in hydrostatic pressure and PTT for estimating BP without a calibrating procedure.

  14. Nuclear Technology. Course 26: Nondestructive Examination (NDE) Techniques I. Module 26-3, Hydrostatic Tests.

    ERIC Educational Resources Information Center

    Pelton, Rick; Espy, John

    This third in a series of seven modules for a course titled Nondestructive Examination (NDE) Techniques I describes the principles and practices associated with hydrostatic testing. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to instructor/student,…

  15. The buckling of plastic oblate hemi-ellipsoidal dome shells under external hydrostatic pressure

    Microsoft Academic Search

    C. T. F. Ross; P. Youster; R. Sadler

    2001-01-01

    The paper presents a theoretical and an experimental investigation into the buckling of seven oblate hemi-ellipsoidal dome shells under external hydrostatic pressure. Four of the shells were made in glass reinforced plastic and three were made from a thermosetting plastic called solid urethane plastic. All the vessels were tested to destruction. The theoretical study was made with the aid of

  16. Hydrostatic pressure and temperature calibration based on phase diagram of bismuth

    Microsoft Academic Search

    Zhigang Wang; Yonggang Liu; Yan Bi; Wei Song; Hongsen Xie

    2012-01-01

    Under high-temperature and high pressure (HTHP) experiments, materials of small elastic modulus deform easily, and the length of the sample can be hardly predicted which lead to failure of ultrasonic velocity measurement. In this paper, a hydrostatic assembly of the sample for ultrasonic measurements is designed under HPHT, which can prevent plastic deformation. According to the abrupt change of travel

  17. OFDR DISTRIBUTED STRAIN MEASUREMENTS FOR SHM OF HYDROSTATIC STRESSED STRUCTURES: AN APPLICATION TO HIGH

    E-print Network

    Paris-Sud XI, Université de

    hydrogen storage, based on embedded optical fibres and Rayleigh OFDR. Fibre Bragg Gratings in situ strain on high resolution distributed strain profiles analysis along singlemode optical fibres embeddedOFDR DISTRIBUTED STRAIN MEASUREMENTS FOR SHM OF HYDROSTATIC STRESSED STRUCTURES: AN APPLICATION

  18. Effects of Hydrostatic Pressure on Energy Metabolism and Osmoregulation in Crab and Fish

    Microsoft Academic Search

    P Sébert; B Simon; A Péqueux

    1997-01-01

    This review will focus on the effects of hydrostatic pressure on the oxidative metabolism and on the energy production of the eel Anguilla anguilla, in comparison with the results of investigations conducted on the other powerful euryhaline species, the chinese crab Eriocheir sinensis. Anguilla and Eriocheir were chosen as being both aquatic ectotherms with comparable life modes, the eel being

  19. Production of homozygous, doubled haploid channel catfish via hydrostatic pressure and thermal treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Production of doubled haploids via mitotic gynogenesis is a useful tool for the creation of completely inbred fish. In order to produce viable doubled haploid channel catfish, we utilized hydrostatic pressure or thermal treatments on eggs fertilized with sperm that had been exposed to ultraviolet l...

  20. Critical current density in wire drawn and hydrostatically extruded Nb-Ti superconductors

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Woollam, J. A.; Collings, E. W.

    1979-01-01

    Critical current studies have been made on copper-clad Nb-Ti composite wire prepared under area reductions of 100:1 and 10,000:1 by hydrostatic extrusion (HE), wire drawing and HE plus drawing. Comparative evaluation of the thermomechanical processing equivalent of HE was performed.

  1. Inactivation of Colletotrichum gloeosporioides spores by high hydrostatic pressure combined with citral or lemongrass essential oil

    Microsoft Academic Search

    Fernando L Palhano; Thabita T. B Vilches; Reginaldo B Santos; Marcos T. D Orlando; J. Aires Ventura; Patricia M. B Fernandes

    2004-01-01

    Anthracnose, caused by the fungus Colletotrichum gloeosporioides, is the main post-harvest disease of the papaya. Inactivation of the spores of C. gloeosporioides in saline solution by the use of high hydrostatic pressure, citral oil and lemongrass oil, alone and in combination, was studied. C. gloeosporioides spores were efficiently inhibited after a pressure treatment of 350 MPa for 30 min. When

  2. Fiber optic liquid crystalline hydrostatic pressure sensor with gradient-index rod lenses

    Microsoft Academic Search

    Tomasz R. Wolinski; Leszek R. Staronski; Aleksandra Jarmolik; Andrzej W. Domanski

    1994-01-01

    A further development of the fiber optic hydrostatic pressure sensor with a liquid crystal film acting as a sensing element is presented. To enhance the amount of the optical signal entering the liquid crystal optrode gradient index (GRIN) rod lenses have been used in the pressure environment. The paper discusses the effect of stress induced birefringence in a GRIN lens,

  3. On the Modeling and Simulation of Non-Hydrostatic Dam Break Flows

    E-print Network

    Paris-Sud XI, Université de

    On the Modeling and Simulation of Non-Hydrostatic Dam Break Flows Alexandre Caboussat S´ebastien Boyaval Alexandre Masserey January 1, 2013 Abstract The numerical simulation of three-dimensional dam analytically. The numerical experiments on actual topographies, in particular the Malpasset dam break

  4. Hydrostatic pressure as the controlling factor in the depth distribution of Eurasian watermilfoil, Myriophyllum spicatum L

    Microsoft Academic Search

    H. M. Dale

    1981-01-01

    These experimental studies have shown that this plant will grow successfully at pressures encountered in water at depths as great as 17 m. When there were suitable levels of light, temperature, nutrients and aeration, the plants grown under constant hydrostatic pressure for three weeks showed variations in the measured amounts of new growth but no measure could be associated with

  5. Forcing a three-dimensional, hydrostatic, primitive-equation model for application in the surf zone

    E-print Network

    Forcing a three-dimensional, hydrostatic, primitive-equation model for application in the surf zone-equation model for application to the nearshore surf zone has been developed. This model, an extension. This combined modeling system is applied to the nearshore surf zone off Duck, North Carolina, during the DUCK94

  6. Elevated hydrostatic pressure activates sodium/hydrogen exchanger-1 in rat optic nerve head astrocytes

    PubMed Central

    Mandal, Amritlal; Shahidullah, Mohammad; Delamere, Nicholas A.; Terán, Marcos A.

    2009-01-01

    Optic nerve head astrocytes become abnormal in eyes that have elevated intraocular pressure, and cultured astrocytes display altered protein expression after being subjected for ?1 days to elevated hydrostatic pressure. Here we show that 2-h elevated hydrostatic pressure (15 or 30 mmHg) causes phosphorylation of ERK1/2, ribosomal S6 protein kinase (p90RSK), and Na/H exchanger (NHE)1 in cultured rat optic nerve head astrocytes as judged by Western blot analysis. The MEK/ERK inhibitor U0126 abolished phosphorylation of NHE1 and p90RSK as well as ERK1/2. To examine NHE1 activity, cytoplasmic pH (pHi) was measured with BCECF and, in some experiments, cells were acidified by 5-min exposure to 20 mM ammonium chloride. Although baseline pHi was unaltered, the rate of pHi recovery from acidification was fourfold higher in pressure-treated astrocytes. In the presence of either U0126 or dimethylamiloride (DMA), an NHE inhibitor, hydrostatic pressure did not change the rate of pHi recovery. The findings are consistent with NHE1 activation due to phosphorylation of ERK1/2, p90RSK, and NHE1 that occurs in response to hydrostatic pressure. These responses may precede long-term changes of protein expression known to occur in pressure-stressed astrocytes. PMID:19419999

  7. Interstitial relaxations due to hydrostatic stress in niobium--oxygen alloys

    Microsoft Academic Search

    S. N. Tewari

    1973-01-01

    Isothermal measurements at 81.6 deg C of an anelastic relaxation induced ; by hydrostatic stresses in the range from ambient to 80.0 psi have been made for ; a Nb-2.3 at. % 0 system. Analysis of the relaxation is made by considering the ; relaxation spectrum as composed of three discrete relaxation times and as a ; lognormal distribution about

  8. Effects of hydrostatic pressure, agitation and CO2 stress on Phytophthora nicotianae zoospore survival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytophthora nicotianae Breda de Haan was used as a model pathogen to investigate the effects of hydrostatic pressure, agitation, and aeration with CO2 or breathable air on the survival of Phytophthora zoospores in water. Injecting CO2 into 2 liters of zoospore-infested water for 5 min at 110.4 ml ...

  9. Release of Potential Instability: Part I. A Sequential Plume Model within a Hydrostatic Primitive Equation Model

    Microsoft Academic Search

    Carl W. Kreitzberg; Donald J. Perkey

    1976-01-01

    The release of potential instability by large-scale lifting and the subsequent interaction of cumulus convection and the hydrostatic mesoscale flow in a most complex scale-interaction process. This process is an essential part of tropical weather but it is also important in extratropical cyclones through the formation of mesoscale rainbands that contribute much of the precipitation. The purpose of this paper

  10. Release of potential instability. Part I. A sequential plume model within a hydrostatic primitive equation model

    Microsoft Academic Search

    Carl W. Kreitzberg; Donald J. Perkey

    1976-01-01

    The release of potential instability by large-scale lifting and the subsequent interaction of cumulus convection and the hydrostatic mesoscale flow is a most complex scale-interaction process. This process is an essential part of tropical weather but it is also important in extratropical cyclones through the formation of mesoscale rainbands that contribute much of the precipitation. The purpose of this paper

  11. Numerical simulation of impact and liftoff events in the hydrostatic skeleton of the leech

    E-print Network

    Bielefeld, Universität

    Numerical simulation of impact and lift­off events in the hydrostatic skeleton of the leech of the medicinal leech and consists of a sequence of hexahedral segments with elastic edges and constant internal, the medicinal leech (Hirudo medicinalis L.). Much is already known about its morphology, the structure of its

  12. Thermal fluid-solid interaction model and experimental validation for hydrostatic mechanical face seals

    NASA Astrophysics Data System (ADS)

    Huang, Weifeng; Liao, Chuanjun; Liu, Xiangfeng; Suo, Shuangfu; Liu, Ying; Wang, Yuming

    2014-09-01

    Hydrostatic mechanical face seals for reactor coolant pumps are very important for the safety and reliability of pressurized-water reactor power plants. More accurate models on the operating mechanism of the seals are needed to help improve their performance. The thermal fluid-solid interaction (TFSI) mechanism of the hydrostatic seal is investigated in this study. Numerical models of the flow field and seal assembly are developed. Based on the mechanism for the continuity condition of the physical quantities at the fluid-solid interface, an on-line numerical TFSI model for the hydrostatic mechanical seal is proposed using an iterative coupling method. Dynamic mesh technology is adopted to adapt to the changing boundary shape. Experiments were performed on a test rig using a full-size test seal to obtain the leakage rate as a function of the differential pressure. The effectiveness and accuracy of the TFSI model were verified by comparing the simulation results and experimental data. Using the TFSI model, the behavior of the seal is presented, including mechanical and thermal deformation, and the temperature field. The influences of the rotating speed and differential pressure of the sealing device on the temperature field, which occur widely in the actual use of the seal, are studied. This research proposes an on-line and assembly-based TFSI model for hydrostatic mechanical face seals, and the model is validated by full-sized experiments.

  13. Elastic properties of carbon nanotubes under hydrostatic pressure S. Reich and C. Thomsen

    E-print Network

    Nabben, Reinhard

    report an ab initio calculation of carbon nano- tube bundles under hydrostatic stress. The volume of the bulk and linear moduli of carbon nanotube bundles and individual tubes. The calculations were done and not capped. This is a good approximation to the real bundles in which the nano- tubes are of finite but very

  14. Effect of Pulsed Ultraviolet Light and High Hydrostatic Pressure on the Antigenicity of Almond Protein Extracts.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of pulsed ultraviolet light (PUV) and high hydrostatic pressure (HHP) on reducing the IgE binding to the almond extracts, was studied using SDS-PAGE, Western Blot, and ELISA probed with human plasma containing IgE antibodies to almond allergens, and a polyclonal antibody against almond ...

  15. Potential for High Hydrostatic Pressure Processing to Control Quarantine Insects in Fruit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tests were conducted to determine the potential for high hydrostatic pressure (HPP) to control codling moth, Cydia pomonella (L.) and Western cherry fruit fly, Rhagoletis indifferens Curran. Apples with larvae or eggs of codling moth were treated 24 h and 72 h, respectively, after infestation at a s...

  16. Biomechanics of a muscular hydrostat: a model of lapping by a reptilian tongue

    Microsoft Academic Search

    Hillel J. Chiel; Patrick E. Crago; Joseph M. Mansour; Kamal Hathi

    1992-01-01

    We have developed a quantitative model of an example of a muscular hydrostat, a reptilian tongue, and have used this model to study a functional movement, protrusion and retrusion, a form of lapping. The model tongue consists of a longitudinal muscle that shortens the tongue when it contracts, and a circumferential muscle wrapped around the longitudinal muscle that lengthens the

  17. A matrix converter based permanent magnet motor drive for an electro-hydrostatic aircraft actuator

    Microsoft Academic Search

    P. W. Wheeler; J. C. Clare; M. Apap; L. Empringham; K. J. Bradley; Chris Whitley; Graham Towers

    2003-01-01

    This paper describes the design, construction and testing of a matrix converter permanent magnet motor drive for an electro-hydrostatic aircraft actuator (EHA). The converter has been built using a 35Amp Eupec Matrix Converter module with closed loop vector control. The commutation time has been minimized to avoid any unnecessary waveform distortion. Practical results from the testing of this converter are

  18. Strength Differential Measured in Inconel 718: Effects of Hydrostatic Pressure Studied

    NASA Technical Reports Server (NTRS)

    Lewandowski, John J.; Wesseling, Paul; Prabhu, Nishad S.; Larose, Joel; Lissenden, Cliff J.; Lerch, Bradley A.

    2003-01-01

    Aeropropulsion components, such as disks, blades, and shafts, are commonly subjected to multiaxial stress states at elevated temperatures. Experimental results from loadings as complex as those experienced in service are needed to help guide the development of accurate viscoplastic, multiaxial deformation models that can be used to improve the design of these components. During a recent study on multiaxial deformation (ref. 1) on a common aerospace material, Inconel 718, it was shown that the material in the aged state exhibits a strength differential effect (SDE), whereby the uniaxial compressive yield and subsequent flow behavior are significantly higher than those in uniaxial tension. Thus, this material cannot be described by a standard von Mises yield formulation. There have been other formulations postulated (ref. 2) that involve other combinations of the stress invariants, including the effect of hydrostatic stress. The question remained as to which invariants are necessary in the flow model. To capture the physical mechanisms occurring during deformation and reflect them in the plasticity formulation, researchers examined the flow of Inconel 718 under various amounts of hydrostatic stress to determine whether or not hydrostatic stress is needed in the formulation. Under NASA Grant NCC3-464, monitored by the NASA Glenn Research Center, a series of tensile tests were conducted at Case Western Reserve University on aged (precipitation hardened) Inconel 718 at 650 C and with superimposed hydrostatic pressure. Dogbone shaped tensile specimens (3-mm-diameter gauge by 16-mm gauge length) and cylindrical compression specimens (3-mm-diameter gauge by 6-mm gauge length) were strain gauged and loaded in a high-pressure testing apparatus. Hydrostatic pressures were obtained with argon and ranged from 210 to 630 MPa. The aged Inconel 718 showed a pronounced difference in the tension and compression yield strength (i.e., an SDE), as previously observed. Also, there were no significant effects of hydrostatic pressure on either the tensile and compressive yield strength (see the graph) or on the magnitude of the SDE. This behavior is not consistent with the pressure-dependent theory of the SDE, which postulates that the SDE is associated with pressure-dependent and/or internal friction dependent deformation associated with non-Schmid effects at the crystal level (refs. 3 and 4). Flow in Inconel 718 appears to be independent of hydrostatic pressure, suggesting that this invariant may be removed from the phenomenological constitutive model. As part of an ongoing effort to develop advanced constitutive models, Glenn s Life Prediction Branch coordinated this work with that of research on the multiaxial deformation behavior of Inconel 718 being conducted at Pennsylvania State University under NASA Grant NCC597.

  19. Bearing Cartridge Designed To Reduce Wear

    NASA Technical Reports Server (NTRS)

    Krieg, Eric J.

    1992-01-01

    Bearing cartridge holding outer races of two ball bearings in turbopump designed to prevent unloading of bearings during operating transients. Cartridge and bearings replace two ball bearings, whose outer races mounted in cylinder called "isolator" and preloaded by single spring mount holding isolator and reacting radial loads. Cartridge slides axially in bore of isolator during transients and forces outer races to move as pair. Necessary to eliminate unloading because unloading initiates wear.

  20. Superconductor bearings, flywheels and transportation

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  1. The role of ontogeny in physiological tolerance: decreasing hydrostatic pressure tolerance with development in the northern stone crab Lithodes maja.

    PubMed

    Munro, Catriona; Morris, James P; Brown, Alastair; Hauton, Chris; Thatje, Sven

    2015-06-22

    Extant deep-sea invertebrate fauna represent both ancient and recent invasions from shallow-water habitats. Hydrostatic pressure may present a significant physiological challenge to organisms seeking to colonize deeper waters or migrate ontogenetically. Pressure may be a key factor contributing to bottlenecks in the radiation of taxa and potentially drive speciation. Here, we assess shifts in the tolerance of hydrostatic pressure through early ontogeny of the northern stone crab Lithodes maja, which occupies a depth range of 4-790 m in the North Atlantic. The zoea I, megalopa and crab I stages were exposed to hydrostatic pressures up to 30.0 MPa (equivalent of 3000 m depth), and the relative fold change of genes putatively coding for the N-methyl-d-aspartate receptor-regulated protein 1 (narg gene), two heat-shock protein 70 kDa (HSP70) isoforms and mitochondrial Citrate Synthase (CS gene) were measured. This study finds a significant increase in the relative expression of the CS and hsp70a genes with increased hydrostatic pressure in the zoea I stage, and an increase in the relative expression of all genes with increased hydrostatic pressure in the megalopa and crab I stages. Transcriptional responses are corroborated by patterns in respiratory rates in response to hydrostatic pressure in all stages. These results suggest a decrease in the acute high-pressure tolerance limit as ontogeny advances, as reflected by a shift in the hydrostatic pressure at which significant differences are observed. PMID:26041343

  2. An efficient semi-implicit method for three-dimensional non-hydrostatic flows in compliant arterial vessels.

    PubMed

    Fambri, Francesco; Dumbser, Michael; Casulli, Vincenzo

    2014-11-01

    Blood flow in arterial systems can be described by the three-dimensional Navier-Stokes equations within a time-dependent spatial domain that accounts for the elasticity of the arterial walls. In this article, blood is treated as an incompressible Newtonian fluid that flows through compliant vessels of general cross section. A three-dimensional semi-implicit finite difference and finite volume model is derived so that numerical stability is obtained at a low computational cost on a staggered grid. The key idea of the method consists in a splitting of the pressure into a hydrostatic and a non-hydrostatic part, where first a small quasi-one-dimensional nonlinear system is solved for the hydrostatic pressure and only in a second step the fully three-dimensional non-hydrostatic pressure is computed from a three-dimensional nonlinear system as a correction to the hydrostatic one. The resulting algorithm is robust, efficient, locally and globally mass conservative, and applies to hydrostatic and non-hydrostatic flows in one, two and three space dimensions. These features are illustrated on nontrivial test cases for flows in tubes with circular or elliptical cross section where the exact analytical solution is known. Test cases of steady and pulsatile flows in uniformly curved rigid and elastic tubes are presented. Wherever possible, axial velocity development and secondary flows are shown and compared with previously published results. PMID:24842268

  3. 'Dodo' and 'Baby Bear' Trenches

    NASA Technical Reports Server (NTRS)

    2008-01-01

    NASA's Phoenix Mars Lander's Surface Stereo Imager took this image on Sol 11 (June 5, 2008), the eleventh day after landing. It shows the trenches dug by Phoenix's Robotic Arm. The trench on the left is informally called 'Dodo' and was dug as a test. The trench on the right is informally called 'Baby Bear.' The sample dug from Baby Bear will be delivered to the Phoenix's Thermal and Evolved-Gas Analyzer, or TEGA. The Baby Bear trench is 9 centimeters (3.1 inches) wide and 4 centimeters (1.6 inches) deep.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  4. HYDROSTATIC GAS CONSTRAINTS ON SUPERMASSIVE BLACK HOLE MASSES: IMPLICATIONS FOR HYDROSTATIC EQUILIBRIUM AND DYNAMICAL MODELING IN A SAMPLE OF EARLY-TYPE GALAXIES

    SciTech Connect

    Humphrey, Philip J.; Buote, David A. [Department of Physics and Astronomy, University of California at Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697-4575 (United States); Brighenti, Fabrizio [Dipartimento di Astronomia, Universita di Bologna, Via Ranzani 1, Bologna 40127 (Italy); Gebhardt, Karl [Astronomy Department, University of Texas, Austin, TX 78712 (United States); Mathews, William G. [University of California Observatories, Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)

    2009-10-01

    We present new mass measurements for the supermassive black holes (SMBHs) in the centers of three early-type galaxies. The gas pressure in the surrounding, hot interstellar medium (ISM) is measured through spatially resolved spectroscopy with the Chandra X-ray Observatory, allowing the SMBH mass (M {sub BH}) to be inferred directly under the hydrostatic approximation. This technique does not require calibration against other SMBH measurement methods and its accuracy depends only on the ISM being close to hydrostatic, which is supported by the smooth X-ray isophotes of the galaxies. Combined with results from our recent study of the elliptical galaxy NGC 4649, this brings the number of galaxies with SMBHs measured in this way to four. Of these, three already have mass determinations from the kinematics of either the stars or a central gas disk, and hence join only a handful of galaxies with M {sub BH} measured by more than one technique. We find good agreement between the different methods, providing support for the assumptions implicit in both the hydrostatic and the dynamical models. The stellar mass-to-light ratios for each galaxy inferred by our technique are in agreement with the predictions of stellar population synthesis models assuming a Kroupa initial mass function (IMF). This concurrence implies that no more than {approx}10%-20% of the ISM pressure is nonthermal, unless there is a conspiracy between the shape of the IMF and nonthermal pressure. Finally, we compute Bondi accretion rates (M-dot{sub bondi}), finding that the two galaxies with the highest M-dot{sub bondi} exhibit little evidence of X-ray cavities, suggesting that the correlation with the active galactic nuclei jet power takes time to be established.

  5. Chromizing of ball bearing steels for extending bearing life

    Microsoft Academic Search

    G. N. Dubinin; G. L. Oganesyan; V. P. Zhukov; V. A. Boikov

    1986-01-01

    1.Diffusion chromizing of self-aligning bearings of steels ShKh15 and 95Kh18 enhances wear resistance and corrosion resistance of these steels.2.Diffusion chromizing makes it possible to replace stainless steel 95Kh18 by the relatively cheap steel ShKh15 with better operational properties obtained after chromizing.

  6. Predicting bearing states in three dimensions

    E-print Network

    D. V. Stäger; N. A. M. Araújo; H. J. Herrmann

    2015-05-27

    Bichromatic bearings have an infinite number of sliding-free states, so called bearing states. For three-dimensional bichromatic bearings whose bearing states have four degrees of freedom, we show how the bearing state can be analytically predicted from the initial state without any information about the nature of the contact forces. We provide a systematic way of constructing such bearings and also show how the bearing state is modified by blocking a single sphere and that any bearing state can be induced by controlling the angular velocities of only two spheres. Furthermore, we show that it is possible to determine the total mass and the center of mass of the bearing by analyzing its response to changes of the angular velocities of at most two spheres.

  7. Gradient Tempering Of Bearing Races

    NASA Technical Reports Server (NTRS)

    Parr, Richardson A.

    1991-01-01

    Gradient-tempering process increases fracture toughness and resistance to stress-corrosion cracking of ball-bearing races made of hard, strong steels and subject to high installation stresses and operation in corrosive media. Also used in other applications in which local toughening of high-strength/low-toughness materials required.

  8. Radiation tolerance in water bears

    Microsoft Academic Search

    D. D. Horikawa; T. Sakashita; C. Katagiri; M. Watanabe; Y. Nakahara; T. Okuda; N. Hamada; S. Wada; T. Funayama; Y. Kobayashi

    2006-01-01

    Tardigrades water bears are tiny invertebrates forming a phylum and inhabit various environments on the earth Terrestrial tardigrades enter a form called as anhydrobiosis when the surrounding water disappears Anhyydrobiosis is defined as an ametabolic dry state and followed by recovering their activity when rehydrated Anhydrobiotic tardigrades show incredible tolerance to a variety of extreme environmental conditions such as temperatures

  9. Hydrostatic pressure and magnetic field effects on donor states in pyramidal quantum dots

    NASA Astrophysics Data System (ADS)

    Tiriba, G. C.; Niculescu, E. C.; Burileanu, L. M.

    2014-11-01

    The simultaneous effects of the hydrostatic pressure and magnetic field on the ground state of impurity confined by a GaAs pyramid-shaped QD are investigated within the effective mass approximation. By using a variational method, the binding energy and the extent of the electron wavefunction in the structure are examined for different dot sizes and impurity positions. The influence of above mentioned parameters on the diamagnetic shift of the impurity energy is also discussed. We found that the diamagnetic coefficient could be appreciably tuned by a proper tailoring of the heterostructure parameters (dot size, impurity position) as well as by changing the hydrostatic pressure and/or the magnetic field strength.

  10. Function and hydrostatics in the telson of the Burgess Shale arthropod Burgessia

    PubMed Central

    Lin, Jih-Pai

    2009-01-01

    Burgessia bella is a characteristic Burgess Shale arthropod (508?Ma), but the unusual preservation of its telson in both straight and bent modes leads to contradictory interpretations of its function. A reinvestigation of the fossil material, including burial attitudes, combined with a comparison with the decay sequence and mechanics of the telson in living Limulus, demonstrates that the telson of Burgessia was flexible in its relaxed state but could be stiffened in life. Evidence of fluid within the telson indicates that this manoeuvrability was achieved by changes in hydrostatic pressure and muscular control. The dual mode in the Burgessia telson is, to my knowledge, the first documented among fossil arthropods. It indicates that the requirement for a rigid telson, which is resolved by a thick sclerotized cuticle in most arthropods, may first have been achieved by hydrostatic means. PMID:19324649

  11. Quantifying hydrostatic pressure in plant cells by using indentation with an atomic force microscope.

    PubMed

    Beauzamy, Léna; Derr, Julien; Boudaoud, Arezki

    2015-05-19

    Plant cell growth depends on a delicate balance between an inner drive-the hydrostatic pressure known as turgor-and an outer restraint-the polymeric wall that surrounds a cell. The classical technique to measure turgor in a single cell, the pressure probe, is intrusive and cannot be applied to small cells. In order to overcome these limitations, we developed a method that combines quantification of topography, nanoindentation force measurements, and an interpretation using a published mechanical model for the pointlike loading of thin elastic shells. We used atomic force microscopy to estimate the elastic properties of the cell wall and turgor pressure from a single force-depth curve. We applied this method to onion epidermal peels and quantified the response to changes in osmolality of the bathing solution. Overall our approach is accessible and enables a straightforward estimation of the hydrostatic pressure inside a walled cell. PMID:25992723

  12. Optical chamber system designed for microscopic observation of living cells under extremely high hydrostatic pressure.

    PubMed

    Koyama, S; Miwa, T; Sato, T; Aizawa, M

    2001-12-01

    A novel pressure chamber system has been developed for the study of living cells under conditions of extremely high hydrostatic pressure up to 100 MPa (1 atm = 0.101325 MPa). The temperature in the chamber is thermostatically controlled in the range from 2 degrees to 80 degrees C. Two high-pressure pumps are employed for continuous perfusion of the chamber with culture medium and a chemical solution under high hydrostatic pressure conditions. The chamber has a 2-mm-thick glass window 2 mm in diameter, with a minimum working distance of 3.8 mm. The chamber system is designed to be adaptable to a variety of microscopic and imaging techniques. Using this chamber system, we successfully carried out real-time observations of elongated Escherichia coli and rounded HeLa cells under pressure. PMID:11778842

  13. The effect of hydrostatic vs. shock pressure treatment on plant seeds

    NASA Astrophysics Data System (ADS)

    Mustey, Adrian; Leighs, James; Appleby-Thomas, Gareth; Wood, David; Hazael, Rachael; McMillan, Paul; Hazell, Paul

    2013-06-01

    The hydrostatic pressure and shock response of plant seeds have both been previously investigated (primarily driven by an interest in reducing bacterial contamination of crops and the theory of panspermia respectively). However, comparisons have not previously been made between these two methods of applying pressure to plant seeds. Here such a comparison has been undertaken based on the premise that any correlations in such data may provide a route to inform understanding of damage mechanisms in the seeds under test. In this work two varieties of plant seeds were subjected to hydrostatic pressure via a non-end-loaded piston cylinder set-up and shock compression via employment of a 50-mm bore, single stage gas gun using the flyer-plate technique. Results from germination tests of recovered seed samples have been compared and contrasted, and initial conclusions made regarding causes of trends in the resultant data-set.

  14. Bacterial inactivation by high-pressure homogenisation and high hydrostatic pressure

    Microsoft Academic Search

    Elke Y Wuytack; Ann M. J Diels; Chris W Michiels

    2002-01-01

    The resistance of five gram-positive bacteria, Enterococcus faecalis, Staphylococcus aureus, Lactobacillus plantarum, Listeria innocua and Leuconostoc dextranicum, and six gram-negative bacteria, Salmonella enterica serovar typhimurium, Shigella flexneri, Yersinia enterocolitica, Pseudomonas fluorescens and two strains of Escherichia coli, to high-pressure homogenisation (100–300 MPa) and to high hydrostatic pressure (200–400 MPa) was compared in this study. Within the group of gram-positive bacteria

  15. The effects of defects on copper melting under hydrostatic and shock loading

    SciTech Connect

    Luo, Shengnian [Los Alamos National Laboratory; An, Qi [Los Alamos National Laboratory; Germann, Timothy C [Los Alamos National Laboratory; Han, Li - Bo [USTC

    2009-07-24

    With molecular dynamics (MD) simulations, we investigate the effects of defects on Cu melting under hydrostatic and shock wave loading. We explore preexistent defects including vacancies, stacking faults and grain boundaries, as well as shock-induced defects. Depending on defect characteristics (energy and concentration), defects may have negligible or considerable effects on melting at MD scales However, it is expected that defects have more pronounced effects at heating rates lower than the MD rates.

  16. Modernization of the Hydrostatic Drive of Lower Gate Locks in Waterworks Gabcikovo

    NASA Astrophysics Data System (ADS)

    Stra?ár, Karol

    2011-12-01

    This paper deals with analysis of the combined load on hydraulic cylinder. Based on measurements of the parameters of the hydraulic cylinder and accurate calculations conclusions were drawn. Measurements were made on the lower hydrostatic drive gate locks at the waterworks Gabcikovo. Method of fixation of the hydraulic cylinder creates added bending torques which causes deformation of piston rod. The results are an effort to find relationship between dimensions, loading and safe operation.

  17. WEIGHING GALAXY CLUSTERS WITH GAS. I. ON THE METHODS OF COMPUTING HYDROSTATIC MASS BIAS

    SciTech Connect

    Lau, Erwin T.; Nagai, Daisuke [Department of Physics, Yale University, New Haven, CT 06520 (United States); Nelson, Kaylea, E-mail: erwin.lau@yale.edu [Department of Astronomy, Yale University, New Haven, CT 06520 (United States)

    2013-11-10

    Mass estimates of galaxy clusters from X-ray and Sunyeav-Zel'dovich observations assume the intracluster gas is in hydrostatic equilibrium with their gravitational potential. However, since galaxy clusters are dynamically active objects whose dynamical states can deviate significantly from the equilibrium configuration, the departure from the hydrostatic equilibrium assumption is one of the largest sources of systematic uncertainties in cluster cosmology. In the literature there have been two methods for computing the hydrostatic mass bias based on the Euler and the modified Jeans equations, respectively, and there has been some confusion about the validity of these two methods. The word 'Jeans' was a misnomer, which incorrectly implies that the gas is collisionless. To avoid further confusion, we instead refer these methods as 'summation' and 'averaging' methods respectively. In this work, we show that these two methods for computing the hydrostatic mass bias are equivalent by demonstrating that the equation used in the second method can be derived from taking spatial averages of the Euler equation. Specifically, we identify the correspondences of individual terms in these two methods mathematically and show that these correspondences are valid to within a few percent level using hydrodynamical simulations of galaxy cluster formation. In addition, we compute the mass bias associated with the acceleration of gas and show that its contribution is small in the virialized regions in the interior of galaxy clusters, but becomes non-negligible in the outskirts of massive galaxy clusters. We discuss future prospects of understanding and characterizing biases in the mass estimate of galaxy clusters using both hydrodynamical simulations and observations and their implications for cluster cosmology.

  18. Effects of solutes on solubilization and refolding of proteins from inclusion bodies with high hydrostatic pressure

    Microsoft Academic Search

    SEUNG-HYUN LEE; JOHN F. CARPENTER; BYEONG S. CHANG; THEODORE W. RANDOLPH; YONG-SUNG KIM

    2006-01-01

    High hydrostatic pressure (HHP)-mediated solubilization and refolding of five inclusion bodies (IBs) produced from bacteria, three Gram-negative binding proteins (GNBP1, GNBP2, and GNBP3) from Drosophila, and two phosphatases from human were investigated in combination of a redox-shuffling agent (2 mM DTT and 6 mM GSSG) and various additives. HHP (200 MPa) combined with the redox- shuffling agent resulted in solubilization

  19. Microbiological quality of mechanically recovered poultry meat treated with high hydrostatic pressure and nisin

    Microsoft Academic Search

    J. Yuste; M. Mor-Mur; M. Capellas; B. Guamis; R. Pla

    1998-01-01

    The combined effect of high hydrostatic pressure processing, addition of nisin and acidification on aerobic mesophilic and psychrotrophic bacterial populations of mechanically recovered poultry meat (MRPM) kept under refrigeration (2°C) was evaluated 1, 15 and 30 days after pressurization. Nisin (0, 12.055, 100 and 200 ppm) and glucono-delta-lactone (GdL; 0 and 1%) were added to MRPM. Vacuum-packaged samples were treated

  20. Cholesteric Liquid Crystal Sensing of High Hydrostatic Pressure Utilizing Optical Fibers

    Microsoft Academic Search

    T. R. Woli?ski; W. J. Bock

    1991-01-01

    A new method of sensing high hydrostatic pressure utilizing cholesteric liquid crystals (ChLCs) as a sensing element and optical fibers for communication with the high-pressure region is proposed and demonstrated the concept exploits the effect of pressure-induced changes in the peak light-reflection wavelength observed in ChLCs. Measurements were performed on an encapsulated ChLC sample obtained by dispersion of a mixture

  1. Effect of High Hydrostatic Pressure on Physicochemical and Structural Properties of Rice Starch

    Microsoft Academic Search

    Wenhao Li; Yunfei Bai; Saleh A. S. Mousaa; Qing Zhang; Qun Shen

    Rice starch–water suspension (20%) were subjected to high hydrostatic pressure (HHP) treatment at 120, 240, 360, 480, and\\u000a 600 MPa for 30 min. Polarizing light microscope, scanning electron microscopy (SEM), rapid visco analyzer (RVA), differential\\u000a scanning calorimeter (DSC), and X-ray diffraction were used to investigate the physicochemical and structural changes of starch.\\u000a Microscopy studies showed that the treatment of starch with HHP

  2. Transformation of luminescence centers in CVD ZnS films subjected to a high hydrostatic pressure

    Microsoft Academic Search

    N. K. Morozova; I. A. Karetnikov; V. G. Plotnichenko; E. M. Gavrishchuk; É. V. Yashina; V. B. Ikonnikov

    2004-01-01

    The cathodoluminescence and optical-transmission spectra of ZnS were analyzed to study the effect of a high hydrostatic gas\\u000a pressure (1500 atm at 1000C) on the equilibrium between intrinsic point defects in zinc sulfide grown by chemical vapor deposition\\u000a (CVD) with an excess of zinc. The cathodoluminescence spectra were measured at 80–300 K and excitation levels of 1022 and 1026 cm?3

  3. Effect of hydrostatic extrusion on passivity breakdown on 303 austenitic stainless steel in chloride solution

    Microsoft Academic Search

    M. Pisarek; P. K?dzierzawski; M. Janik-Czachor; K. J. Kurzyd?owski

    2009-01-01

    The stability of the passive film formed on austenitic 303 stainless steel in the as-received state and after severe plastic\\u000a deformation by hydrostatic extrusion (HE) leading to nanostructurization was investigated in an aggressive environment containing\\u000a Cl? ions by anodic polarization. Transmission electron microscopy (TEM) and stereological image analysis were used to examine\\u000a structural changes introduced by HE. Surface analytical techniques

  4. Occludin Independently Regulates Permeability under Hydrostatic Pressure and Cell Division in Retinal Pigment Epithelial Cells

    PubMed Central

    Phillips, Brett E.; Cancel, Limary; Tarbell, John M.; Antonetti, David A.

    2008-01-01

    Purpose The aim of this study was to determine the function of the tight junction protein occludin in the control of permeability, under diffusive and hydrostatic pressures, and its contribution to the control of cell division in retinal pigment epithelium. Methods Occludin expression was inhibited in the human retinal pigment epithelial cell line ARPE-19 by siRNA. Depletion of occludin was confirmed by Western blot, confocal microscopy, and RT-PCR. Paracellular permeability of cell monolayers to fluorescently labeled 70 kDa dextran, 10 kDa dextran, and 467 Da tetramethylrhodamine (TAMRA) was examined under diffusive conditions or after the application of 10 cm H2O transmural pressure. Cell division rates were determined by tritiated thymidine incorporation and Ki67 immunoreactivity. Cell cycle inhibitors were used to determine whether changes in cell division affected permeability. Results Occludin depletion increased diffusive paracellular permeability to 467 Da TAMRA by 15%, and permeability under hydrostatic pressure was increased 50% compared with control. Conversely, depletion of occludin protein with siRNA did not alter diffusive permeability to 70 kDa and 10 kDa RITC-dextran, and permeability to 70 kDa dextran was twofold lower in occludin-depleted cells under hydrostatic pressure conditions. Occludin depletion also increased thymidine incorporation by 90% and Ki67-positive cells by 50%. Finally, cell cycle inhibitors did not alter the effect of occludin siRNA on paracellular permeability. Conclusions The data suggest that occludin regulates tight junction permeability in response to changes in hydrostatic pressure. Furthermore, these data suggest that occludin also contributes to the control of cell division, demonstrating a novel function for this tight junction protein. PMID:18263810

  5. HYDROSTATIC WEIGHING SYSTEM AT THE INRiM FOR CALIBRATING HYDROMETERS

    Microsoft Academic Search

    Hydrometers are simple but effective instruments fo r measuring the density of liquids. In this work, we present the new hydrostatic weighing system developed at the INRiM, formerly IMGC - CNR, for the calibration of hydrometers in the range 500 kg.m -3 to 2000 kg.m -3 . The apparatus which uses a method to automatically align specific scale-marks for the

  6. Proteolysis of type III collagen by collagenase and cathepsin B under high hydrostatic pressure

    Microsoft Academic Search

    Eric Dufour; Michèle Dalgalarrondo; Guy Hervé; René Goutefongea; Tomasz Haertlé

    1996-01-01

    The effects of high hydrostatic pressures on the kinetics of hydrolysis of type III collagen from calf skin by collagenase and cathepsin B were studied. Collagen hydrolysates sampled at different time intervals (0–90 min) and at different pressures (0.1–300 MPa) were analysed by reverse-phase high pressure liquid chromatography. The rate of collagen hydrolysis decreased up to 300 MPa for both

  7. An Update on High Hydrostatic Pressure, from the Laboratory to Industrial Applications

    Microsoft Academic Search

    Daniela Bermúdez-Aguirre; Gustavo V. Barbosa-Cánovas

    2011-01-01

    High hydrostatic pressure has become an industrial reality, and although there are still many aspects under research, today\\u000a it is possible to buy high-pressurized products in many countries. Indeed, pasteurization of food products using elevated\\u000a pressure at room temperature has been accepted by regulatory agencies for commercial use. The quality displayed in such products\\u000a includes better nutritional retention, fresh-like flavor,

  8. Recovery of Escherichia coli ATCC 25922 in phosphate buffered saline after treatment with high hydrostatic pressure

    Microsoft Academic Search

    Shigenobu Koseki; Kazutaka Yamamoto

    2006-01-01

    Escherichia coli ATCC 25922 in phosphate buffered saline solution (PBS, pH 7.1, 108 CFU\\/ml) was inactivated by high hydrostatic pressure (HHP, 400 to 600 MPa) treatment at 25 °C for 10 min. Colonies of E. coli were not detected on non-selective plate count agar immediately after a HHP-treatment of at least 550 MPa. E. coli subjected to at least 500 MPa in PBS were incubated at

  9. Simulation of Storm Surge by a Depth-integrated Non-hydrostatic Nested-gird Model

    NASA Astrophysics Data System (ADS)

    Tsai, Yu-Lin; Wu, Tso-Ren; Terng, Chuen-Teyr; Cheung, Mei-Hui

    2015-04-01

    This paper presents COMCOT-SS (COrnell Multi-grid Coupled of Tsunami Model - Storm Surge) operational model, a depth integrated non-hydrostatic storm surge model developed for the Central Weather Bureau (CWB) in Taiwan. This model is based on the widely-validated COMCOT tsunami model. However, the governing equations were modified to be a depth-integrated vertical momentum equation, and the nonlinear shallow water equations including extra terms, such as the non-hydrostatic pressure, weather forcing, and tidal terms. The non-hydrostatic term enables the model to simulate relatively steep waves in the near-shore region. The conventional features in COMCOT, such as the nested-grid system, spherical and Cartesian coordinate systems, and the moving boundary scheme for inundation prediction were preserved. In this study, we carefully validated the model with analytic solutions for wind shear stress and pressure gradient terms. TWRF (Typhoon Weather Research and Forecasting) model was coupled for providing the meteorological forces generated by typhoons. Besides, parametric typhoon models such as Holland model (1980) and CWB model were also coupled with COMCOT-SS in which the drag coefficient was advised by Large and Pond (1981) and Powell (2003). Astronomical tide provided by the TPXO global tidal model was imported from the domain boundaries. As for the model performance, COMCOT-SS spends less than 30 minutes to finish a 48-hrs forecasting with a large computational domain which covers Taiwan Strait and most parts of Western Pacific Ocean and South China Sea and satisfies the requirement of early warning. In this paper, we also presented the results of nine typical typhoon routes defined by CWB in Taiwan for the model verification. The simulation results accompanied with the non-hydrostatic effect presented good agreement with observation data. Detailed results and discussion will be presented in EGU, 2015.

  10. Crossed-feedback control of dual-redundancy permanent magnetic brushless dc servo system used in electro-hydrostatic actuator

    Microsoft Academic Search

    Zhou Qixun; Li Shengjin; Lu Gang; Zhou Yong

    2008-01-01

    Integrated electro-hydrostatic actuation system has the advantages of both small size and high power density. Dual-redundancy permanent magnet brushless DC motor (BLDCM) as the actuation component in electro-hydrostatic actuator (EHA) improves system reliability. But unequal electromagnetic torque in different redundant motor is a severe problem. It may impact the performance of the motor, even damage it. In this paper the

  11. High Temperature, Permanent Magnet Biased Magnetic Bearings 

    E-print Network

    Gandhi, Varun R.

    2010-07-14

    The Electron Energy Corporation (EEC) along with the National Aeronautics and Space Administration (NASA) is researching magnetic bearings. The purpose of this research was to design and develop a high-temperature (1000?F) magnetic bearing system...

  12. Hunting for 'bears' in the backyard

    NSDL National Science Digital Library

    Dave Walker

    This Micscape Magazine article offers practical hints about how to collect and study tardigrades, or water bears, from mosses in your backyard. It features a general introduction of water bears, a video, and a section of references for further reading.

  13. Bear-inflicted human injury and fatality.

    PubMed

    Floyd, T

    1999-01-01

    This review attempts to summarize credible scientific information, and to dispel myths, regarding bear attacks. Publications in the scientific literature were sought through a Medline search and by reviewing the bibliographies of related books and scientific articles. Personal experience and interviews with authorities were also used in preparation of this review, although only published articles or books are cited. This is a summary of case series reported or observed elsewhere. Bear-inflicted human injury and death is rare. Brown bear attacks tend to be severe and to occur suddenly, without provocation. Black bear attacks usually result in minor injuries and tend to be predacious. Polar bear attacks are exceedingly rare, and the ferocity of polar bears has probably been overemphasized. Bear-inflicted wounds should be treated as major trauma in accordance with advanced trauma life support guidelines. This information may be useful in counseling patients with regard to prevention of injury or death from bear attack. PMID:10442155

  14. Rolling Element Bearing Stiffness Matrix Determination (Presentation)

    SciTech Connect

    Guo, Y.; Parker, R.

    2014-01-01

    Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to 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 bearing radial, axial, and tilting bearing deflections.

  15. Artificial induction of mito-gynogenetic diploids in large yellow croaker ( Pseudosciaena crocea) by hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Cai, Mingyi; Wu, Qingming; Liu, Xiande; Yao, Cuiluan; Chen, Qingkai; Wang, Zhiyong

    2010-07-01

    The present study investigated conditions for inducing mito-gynogenetic (endomitosis) diploids by hydrostatic pressure in the large yellow croaker Pseudosciaena crocea. In haploid control groups, the development of eggs was activated with ultraviolet radiated semen. All fry presented typical haploid syndrome in the haploid control groups, and were verified as haploids using cytometry. After hydrostatic pressure treatment, morphologically normal fry reappeared at different frequencies according to the intensity and time of pressure shock. Fry with normal appearance in the pressure treated groups were verified as gynogenetic double haploids (GDHs), containing only one allele from the female parent at all four diagnostic microsatellite loci. For a fixed duration of 3 min, the optimal intensity of blocking the first mitosis was determined to be 40 Mpa, which was similar to that of blocking the second meiosis. There was a “window” of starting time, from 36.1 min to 38.1 min post-insemination at 25.0±1.0°C, within which the production of GDHs was not significantly different. Maximum production of morphologically normal fries, 9.36%±2.97% of developed eggs, was found when the eggs were shocked with hydrostatic pressure at 40 Mpa for 3 min, starting from 38.1 min post insemination at 25.0±1.0°C.

  16. Hyporheic flow path response to hydraulic jumps at river steps: Hydrostatic model simulations

    NASA Astrophysics Data System (ADS)

    Endreny, T.; Lautz, L.; Siegel, D.

    2011-02-01

    This research examined hydrostatic groundwater model (MODFLOW) predictive adequacy and sensitivity in simulating hyporheic flow paths across a river step with a hydraulic jump. In a companion paper, we used flume and hydrodynamic model analysis to develop a refined conceptual model depicting these flow paths with zones of downwelling and upstream-directed flux below the step. The previous coarse conceptual model predicted uniform downstream-directed upwelling below the step. The hydrostatic model accurately predicted the downwelling and upstream-directed fluxes beneath the wave and jump but failed to predict the plunge pool downwelling, which is driven by dynamic pressures. Sensitivity tests varied riverbed topography and water surface profile geometry for a river with 1% slopes, 10 cm flow depths, and 50-150 cm long jets and jumps. The flow paths below the jet-jump region were driven by hydrostatic pressures and were highly sensitive to water surface profile and riverbed topography parameters. Failure to simulate the hydraulic jump caused errors in hyporheic flow path predictions beneath the jump region (˜1 m long by ˜0.5 m deep). If the jump was poorly parameterized, several meters of riverbed flow paths could be erroneously modeled as pointing upstream. The hyporheic zone may contain a spatial mosaic of aerobic and anaerobic waters regulating nutrient transformations and biologic productivity. Accurate parameterization of hydraulic jumps in hyporheic simulation has the potential to improve predictions and explain heterogeneous subsurface flow paths and associated nutrient patterns and ecosystem functions.

  17. Optimal dispersion with minimized Poisson equations for non-hydrostatic free surface flows

    NASA Astrophysics Data System (ADS)

    Cui, Haiyang; Pietrzak, J. D.; Stelling, G. S.

    2014-09-01

    A non-hydrostatic shallow-water model is proposed to simulate the wave propagation in situations where the ratio of the wave length to the water depth is small. It exploits the reduced-size stencil in the Poisson pressure solver to make the model less expensive in terms of memory and CPU time. We refer to this new technique as the minimized Poisson equations formulation. In the simplest case when the method applied to a two-layer model, the new model requires the same computational effort as depth-integrated non-hydrostatic models, but can provide a much better description of dispersive waves. To allow an easy implementation of the new method in depth-integrated models, the governing equations are transformed into a depth-integrated system, in which the velocity difference serves as an extra variable. The non-hydrostatic shallow-water model with minimized Poisson equations formulation produces good results in a series of numerical experiments, including a standing wave in a basin, a non-linear wave test, solitary wave propagation in a channel and a wave propagation over a submerged bar.

  18. A hydrostatic weighing method using total lung capacity and a small tank.

    PubMed Central

    Warner, J G; Yeater, R; Sherwood, L; Weber, K

    1986-01-01

    The purpose of this study was to establish the validity and reliability of a hydrostatic weighing method using total lung capacity (measuring vital capacity with a respirometer at the time of weighing) the prone position, and a small oblong tank. The validity of the method was established by comparing the TLC prone (tank) method against three hydrostatic weighing methods administered in a pool. The three methods included residual volume seated, TLC seated and TLC prone. Eighty male and female subjects were underwater weighed using each of the four methods. Validity coefficients for per cent body fat between the TLC prone (tank) method and the RV seated (pool), TLC seated (pool) and TLC prone (pool) methods were .98, .99 and .99, respectively. A randomised complete block ANOVA found significant differences between the RV seated (pool) method and each of the three TLC methods with respect to both body density and per cent body fat. The differences were negligible with respect to HW error. Reliability of the TLC prone (tank) method was established by weighing twenty subjects three different times with ten-minute time intervals between testing. Multiple correlations yielded reliability coefficients for body density and per cent body fat values of .99 and .99, respectively. It was concluded that the TLC prone (tank) method is valid, reliable and a favourable method of hydrostatic weighing. PMID:3697596

  19. A new numerical calculation method for the characteristics of hydrostatic slide

    NASA Astrophysics Data System (ADS)

    Hou, Guoan; Sun, Tao; Zhou, Jingbo; Qi, Enbing

    2012-10-01

    In the design and manufacture of the ultra-precision machine tools, hydrostatic slides have been applied frequently, in the state-of-the-art technology. They can provide extremely smooth and accurate motion and positioning. At design stage, the carrying capacity and the stiffness of hydrostatic slide is an important value. But, the traditional calculation method of slide stiffness used in engineering is an approximate solution, the accuracy is low. In this paper, finding an accurate calculation method of slide stiffness is present, to improve modeling accuracy. Reynolds equation is the basic equation of calculating performance of hydrostatic slide, oil film pressure distribution can be obtained by solving the Reynolds equation. But Reynolds equation is a second-order partial differential equations, it is difficult to directly solve the equation using analytic methods. Therefore, a discrete model is developed to solve the problem. A method that has been widely used is finite element analysis (FEA). Matlab PDE Toolbox provides a convenient way to solving the partial differential equations based the FEA. But it can only directly solve the partial differential equations with standard form. It is discussed how to transform the Reynolds equation into elliptic partial differential equation with standard form. Then combined with the specific boundary conditions, obtain the oil film pressure distribution through Matlab PDE toolbox, and then write program to achieve high-precision calculation of carrying capacity and stiffness of the slide.

  20. Calpain: a molecule to induce AIF-mediated necroptosis in RGC-5 following elevated hydrostatic pressure

    PubMed Central

    2014-01-01

    Background RIP3 (Receptor-interacting protein 3) pathway was mainly described as the molecular mechanism of necroptosis (programmed necrosis). But recently, non-RIP3 pathways were found to mediate necroptosis. We deliberate to investigate the effect of calpain, a molecule to induce necroptosis as reported (Cell Death Differ 19:245–256, 2012), in RGC-5 following elevated hydrostatic pressure. Results First, we identified the existence of necroptosis of RGC-5 after insult by using necrostatin-1 (Nec-1, necroptosis inhibitor) detected by flow cytometry. Immunofluorescence staining and western blot were used to detect the expression of calpain. Western blot analysis was carried out to describe the truncated AIF (tAIF) expression with or without pretreatment of ALLN (calpain activity inhibitor). Following elevated hydrostatic pressure, necroptotic cells pretreated with or without ALLN was stained by Annexin V/PI, The activity of calpain was also examined to confirm the inhibition effect of ALLN. The results showed that after cell injury there was an upregulation of calpain expression. Upon adding ALLN, the calpain activity was inhibited, and tAIF production was reduced upon injury along with the decreased number of necroptosis cells. Conclusion Our study found that calpain may induce necroptosis via tAIF-modulation in RGC-5 following elevated hydrostatic pressure. PMID:24884644

  1. Effects of high hydrostatic pressure on coastal bacterial community abundance and diversity.

    PubMed

    Marietou, Angeliki; Bartlett, Douglas H

    2014-10-01

    Hydrostatic pressure is an important parameter influencing the distribution of microbial life in the ocean. In this study, the response of marine bacterial populations from surface waters to pressures representative of those under deep-sea conditions was examined. Southern California coastal seawater collected 5 m below the sea surface was incubated in microcosms, using a range of temperatures (16 to 3°C) and hydrostatic pressure conditions (0.1 to 80 MPa). Cell abundance decreased in response to pressure, while diversity increased. The morphology of the community also changed with pressurization to a predominant morphotype of small cocci. The pressure-induced community changes included an increase in the relative abundance of Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, and Flavobacteria largely at the expense of Epsilonproteobacteria. Culturable high-pressure-surviving bacteria were obtained and found to be phylogenetically similar to isolates from cold and/or deep-sea environments. These results provide novel insights into the response of surface water bacteria to changes in hydrostatic pressure. PMID:25063663

  2. Effects of High Hydrostatic Pressure on Coastal Bacterial Community Abundance and Diversity

    PubMed Central

    Marietou, Angeliki

    2014-01-01

    Hydrostatic pressure is an important parameter influencing the distribution of microbial life in the ocean. In this study, the response of marine bacterial populations from surface waters to pressures representative of those under deep-sea conditions was examined. Southern California coastal seawater collected 5 m below the sea surface was incubated in microcosms, using a range of temperatures (16 to 3°C) and hydrostatic pressure conditions (0.1 to 80 MPa). Cell abundance decreased in response to pressure, while diversity increased. The morphology of the community also changed with pressurization to a predominant morphotype of small cocci. The pressure-induced community changes included an increase in the relative abundance of Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, and Flavobacteria largely at the expense of Epsilonproteobacteria. Culturable high-pressure-surviving bacteria were obtained and found to be phylogenetically similar to isolates from cold and/or deep-sea environments. These results provide novel insights into the response of surface water bacteria to changes in hydrostatic pressure. PMID:25063663

  3. Hydrostatic pressure induced transition from ?TC to ?? pinning mechanism in MgB2

    NASA Astrophysics Data System (ADS)

    Shabbir, Babar; Wang, X. L.; Ghorbani, S. R.; Dou, S. X.; Xiang, Feixiang

    2015-05-01

    The impact of hydrostatic pressure up to 1.2 GPa on the critical current density (Jc) and the nature of the pinning mechanism in MgB2 have been investigated within the framework of the collective theory. We found that the hydrostatic pressure can induce a transition from the regime where pinning is controlled by spatial variation in the critical transition temperature (? {{T}c}) to the regime controlled by spatial variation in the mean free path (? \\ell ). Furthermore, critical temperature (Tc) and low field Jc are slightly reduced, although the Jc drops more quickly at high fields than at ambient pressure. We found that the pressure raises the anisotropy and reduces the coherence length, resulting in weak interaction of the vortex cores with the pinning centres. Moreover, the hydrostatic pressure can reduce the density of states [Ns(E)], which, in turn, leads to a reduction in the Tc from 39.7 K at P = 0 GPa to 37.7 K at P = 1.2 GPa.

  4. Bearing fault diagnosis based on rough set

    Microsoft Academic Search

    Chen Xin; Yuhua Chen; Guofeng Wang; Hu Dong

    2010-01-01

    Bearing defects were categorized as localized and distributed. For on-line bearing fault diagnosis, in this paper, the time-domain kurtosis calculation and the frequency domain wavelet analysis were used to extract the transitory features of non-stationary vibration signal produced by the bearing distributed defects. To distributed defects, bearing fault diagnosis was built on the reducing decision based on rough set. According

  5. Notes 16. Analysis of tilting pad bearings

    E-print Network

    San Andres, Luis

    2010-01-01

    installed to carry a static load on a pad (LOP) or a static load in between pads (LBP). Commercial tilting pad bearings have various pivot designs such as rocker pivots (line contact), spherical pivots (point contact) and flexure supported pivots.... Figure 1. Schematic view of a four pad tilting pad bearing, Ref. [1] Accurate prediction of tilting pad bearing forces and force coefficients is essential to design and predict the dynamic performance of rotor-bearing systems. Parameters affecting...

  6. Effects of bearing deadbands on bearing loads and rotor stability

    NASA Technical Reports Server (NTRS)

    1984-01-01

    A generic model of a turbopump, simplified to bring out these effects is examined. This model demonstrates that bearing deadbands which are of the same order of magnitude or larger than the center-of-mass offset of a rotor due to mass imbalances cause significantly different dynamic behavior than would be expected of a linear, dynamical system. This fundamentally nonlinear behavior yields altered stability characteristics and altered bearing loading tendencies. It is shown that side forces can enhance system stability in the small, i.e., as long as the mass imbalance does not exceed some thresholds value or as long as no large, impulsive disturbances cause the motion to depart significantly from the region of stability. Limit cycles are investigated in this report and techniques for determining these limit cycles are developed. These limit cycles are the major source of bearing loading and appear in both synchronous and nonsynchronous forms. The synchronous limit cycles are driven by rotor imbalances. The nonsynchronous limit cycles (also called subsynchronous whirls) are self-excited and are the sources of instability.

  7. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  8. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  9. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  10. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  11. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  12. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  13. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  14. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  15. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  16. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  17. Induction Motors Bearing Failures Detection and Diagnosis

    E-print Network

    Boyer, Edmond

    331 1 Induction Motors Bearing Failures Detection and Diagnosis Using a RBF ANN Park Pattern Based Method I. Y. Önel, I. enol and M. E. H. Benbouzid Abstract--This paper deals with the problem of bearing detection and diagnosis process. Experimental tests with artificial bearing damages results show

  18. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  19. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  20. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  1. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  2. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  3. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  4. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  5. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  6. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  7. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  8. CURIOSITY IN THE AMERICAN BLACK BEAR

    Microsoft Academic Search

    ELLIS S. BACON

    American black bears (Ursus americanus) were tested to quantify their response to novel objects placed in their environment. The results indicate that the level of orientation may be greater in the black bear than in other North American carnivores. The exploration of objects by the black bear is characterized by a high degree of contact with the objects. This contact

  9. Hydrology of the Bear Lake Basin, Utah

    Microsoft Academic Search

    Patsy Palacios; Chris Luecke; Justin Robinson

    2007-01-01

    Bear Lake’s natural watershed is made up of relatively low mountains covered with sagebrush at lower elevations and southern exposures and fir-aspen forests at higher elevations and northern exposures. The basin is traversed by the Bear River that begins high in the Unita Mountains and flows through Utah, Idaho, and Wyoming before feeding the Great Salt Lake. The Bear River

  10. Passive Thermal Management of Foil Bearings

    NASA Technical Reports Server (NTRS)

    Bruckner, Robert J. (Inventor)

    2015-01-01

    Systems and methods for passive thermal management of foil bearing systems are disclosed herein. The flow of the hydrodynamic film across the surface of bearing compliant foils may be disrupted to provide passive cooling and to improve the performance and reliability of the foil bearing system.

  11. Hybrid air foil bearing with external pressurization 

    E-print Network

    Park, Soongook

    2009-05-15

    Foil bearings are widely used for oil-free micro turbomachinery. One of the critical technical issues related to reliability of the foil bearings is a coating wear on the top foil and rotor during start/stops. Bearing cooling is also mandatory...

  12. FOSTERING BLACK BEAR CUBS IN THE WILD

    Microsoft Academic Search

    STEPHEN H. CLARKE; CHARLES HACKFORD

    Three black bear (Ursus americanus) cubs were abandoned, at approximately 2 weeks of age, on 4 February 1976, in New York State's Catskill region. The dens of 4 radio-telemetered adult female bears were located by the Department of Environmental Conservation during research on the black bear population in the Catskills. Two of the abandoned cubs were placed in the only

  13. Dare to Care for a Grizzly Bear

    NSDL National Science Digital Library

    2008-10-31

    Using the Nature episode “The Good, The Bad and the Grizzly,” students will be able to articulate the complex and competing perspectives on how to best handle the growing bear population, and they will investigate the factors contributing to the destabilization of the bear’s Yellowstone ecosystem.

  14. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Bear orientation. 13.1236 Section 13...Brooks Camp Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

  15. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Bear orientation. 13.1236 Section 13...Brooks Camp Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

  16. Rolling element bearing design through genetic algorithms

    Microsoft Academic Search

    Indraneel Chakraborty; Vinay Kumar; Shivashankar B. Nair; Rajiv Tiwari

    2003-01-01

    The design of rolling element bearings has been a challenging task in the field of mechanical engineering. While most of the real aspects of the design are never disclosed by bearing manufacturers, the common engineer is left with no other alternative than to refer to standard tables and charts containing the bearing performance characteristics. This paper presents a more viable

  17. Fault tolerant control of active magnetic bearings

    Microsoft Academic Search

    P. Schroder; A. J. Chipperfield; P. J. Fleming; N. Grum

    1998-01-01

    A nonlinear model of a Rolls-Royce turbomachine's rotor supported by active magnetic bearings (AMBs) is presented. The model has the capability to model magnetic bearing systems of a variety of different configurations. A multiobjective genetic algorithm (MOGA) is used to design PID controllers for the AMB system with five different bearing configurations. A centralised fault compensation scheme is demonstrated and

  18. Superconducting magnetic bearings for energy storage flywheels

    Microsoft Academic Search

    T. Coombs; A. M. Campbell; R. Storey; R. Weller

    1999-01-01

    We are investigating the use of flywheels for energy storage. Flywheel devices need to be of high efficiency and an important source of losses is the bearings. In addition, the requirement is for the devices to have long lifetimes with minimal or no maintenance. Conventional rolling element bearings can and have been used, but a noncontact bearing, such as a

  19. Cool Polar Bears: Dabbing on the Texture

    ERIC Educational Resources Information Center

    O'Connell, Jean

    2011-01-01

    In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

  20. Minimizing electric bearing currents in ASD systems

    Microsoft Academic Search

    P. J. Link

    1999-01-01

    During recent years, an increase in bearing failures has been seen in ASD-fed electric motors, as well as in gearboxes, and other connected machinery, caused by electric current flow through such bearings. The theories presented in this paper focus on bearing currents in ASDs of the voltage source pulse width modulated (PWM) type, for use with AC induction motors, although

  1. White-etching matter in bearing steel Part 2: Distinguishing cause and eect in bearing steel

    E-print Network

    Cambridge, University of

    White-etching matter in bearing steel Part 2: Distinguishing cause and eect in bearing steel of Cambridge, U.K Abstract The premature failure of large bearings of the type used in wind turbines, possibly as reported observations on real bearings. Evidence suggests that the formation mechanism of the white

  2. Automated Assistance for Designing Active Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Imlach, Joseph

    2008-01-01

    MagBear12 is a computer code that assists in the design of radial, heteropolar active magnetic bearings (AMBs). MagBear12 was developed to help in designing the system described in "Advanced Active-Magnetic-Bearing Thrust-Measurement System". Beyond this initial application, MagBear12 is expected to be useful for designing AMBs for a variety of rotating machinery. This program incorporates design rules and governing equations that are also implemented in other, proprietary design software used by AMB manufacturers. In addition, this program incorporates an advanced unpublished fringing-magnetic-field model that increases accuracy beyond that offered by the other AMB-design software.

  3. Computing Thermal Performances Of Shafts And Bearings

    NASA Technical Reports Server (NTRS)

    Woods, Claudia M.

    1992-01-01

    SHABERTH computer program developed to predict steady-state and transient thermal performance of multi-bearing shaft system operating with either wet or dry friction. Calculates loads, torques, temperatures, and fatigue lives for ball and/or roller bearings on single shaft. Enables study of many causes of instabilities in bearings. Also provides for analysis of reaction of system to termination of supply of lubricant to bearings and other lubricated mechanical elements. Valuable software tool in design and analysis of shaft bearing systems. Written in FORTRAN IV.

  4. Polar Bears International : Wrangel Island, Russia

    NSDL National Science Digital Library

    2007-12-12

    This site describes the ongoing research of the polar bears in the Russian High Arctic. Wrangel Island with neighboring small island, Herald Island, are the key reproductive areas for the Chukchi-Alaskan polar bear population. Marine areas and Wrangel and Herald islands provide optimum foraging habitats for polar bears, and polar bear densities in these marine habitats are high all year round. Approximately 350-500 pregnant female polar bears construct their maternity dens on Wrangel and Herald islands every fall, emerging with their cubs in spring. The research is described in terms of goals and objectives, structure, methods, equipment, staff, and implementations.

  5. Foil bearing research at Penn State

    NASA Astrophysics Data System (ADS)

    Carpino, Marc

    1993-11-01

    Foil journal bearings consist of a compliant metal shell or foil which supports a rigid journal by means of a fluid film. Foil bearings are considered to be a potential alternative to rolling element or traditional rigid surface bearings in cryogenic turbomachinery applications. The prediction of foil bearing performance requires the coupled solution of the foil deflection and the fluid flow in the bearing clearance between the rotor and the foil. The investigations being conducted in the Department of Mechanical Engineering at Penn State are focused in three areas: theoretical prediction of steady state bearing performance, modeling of the dynamic bearing characteristics to determine performance in rotor systems, and experimental verification of analysis codes. The current status and results from these efforts will be discussed.

  6. Design review of fluid film bearing testers

    NASA Technical Reports Server (NTRS)

    Scharrer, Joseph K.

    1993-01-01

    The designs of three existing testers (Hybrid Bearing Tester, OTV Bearing Tester, and Long Life Bearing Tester) owned by NASA were reviewed for their capability to serve as a multi-purpose cryogenic fluid film bearing tester. The primary tester function is the validation of analytical predictions for fluid film bearing steady state and dynamic performance. Evaluation criteria were established for test bearing configurations, test fluids, instrumentation, and test objectives. Each tester was evaluated with respect to these criteria. A determination was made of design improvements which would allow the testers to meet the stated criteria. The cost and time required to make the design changes were estimated. A recommendation based on the results of this study was made to proceed with the Hybrid Bearing Tester.

  7. Public attitudes towards brown bears ( Ursus arctos) in Slovenia

    Microsoft Academic Search

    Petra Kaczensky; Mateja Blazic; Hartmut Gossow

    2004-01-01

    In northern Slovenia a radical change in brown bear (Ursus arctos) management – from a policy of bear suppression to a policy of bear protection – resulted in a sharp increase in sheep predation by bears. In the bear core area in southern Slovenia, on the other hand, bears have always been present, cause little damage and are an important

  8. Turbocharger bearing retention and lubrication system

    SciTech Connect

    Gutknecht, D.A.

    1991-12-31

    This patent describes exhausts gas driven turbocharger. It comprises a housing, a shaft within the housing having a longitudinal axis of rotation and a pair of ends, a compressor wheel mounted within the housing on one end of the shaft for rotation therewith, a turbine wheel mounted within the housing on the other end of the shaft for rotation therewith, means for communicating air to the compressor wheel, means for communicating exhaust gas to the turbine wheel to cause the latter to rotate the shaft and the compressor wheel mounted thereon to compress the air communicated to the compressor wheel, and bearing means mounting the shaft for rotation relative to the housing, the bearing means including a bearing outer ring, a bearing inner ring, and ball bearing elements supporting the bearing outer ring on the bearing inner ring, a bearing locating aperture in the bearing outer ring, and an elongated bearing location pin having a longitudinal axis of symmetry extending transversely to the longitudinal axis of the shaft.

  9. Current Status of Hybrid Bearing Damage Detection

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Certo, Joseph M.; Morales, Wilfredo

    2004-01-01

    Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high pressure oxidizer turbopump, on the space shuttle main engine, led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si3N4 balls. The aerospace industry is currently studying the use of hybrid bearings and naturally the failure modes of these bearings become an issue in light of the limited data available. In today s turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Since the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure. The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris, in oil, using a commercial particle counter.

  10. Interference Fit Life Factors for Roller Bearings

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2008-01-01

    The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner ring interference fit. Calculations were performed for up to seven interference fit classes for each of ten bearing sizes. Each fit was taken at tightest, average and loosest values within the fit class for RBEC-5 tolerance, thus requiring 486 separate analyses. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. The method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings based on interference fit. All calculated lives are for zero initial bearing internal clearance. Any reduction in bearing clearance due to interference fit was compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate and heavy loads and interference fits ranging from extremely light to extremely heavy and for bearing accuracy class RBEC 5 (ISO class 5). Interference fits on the inner bearing ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference fit life factors for a particular fit. The tightest fit at the high end of the RBEC-5 tolerance band defined in ANSI/ABMA shaft fit tables produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

  11. Therapeutic Vaccination against Adjuvant Arthritis Using Autoimmune T Cells Treated with Hydrostatic Pressure

    NASA Astrophysics Data System (ADS)

    Lider, Ofer; Karin, Nathan; Shinitzky, Meir; Cohen, Irun R.

    1987-07-01

    An ideal treatment for autoimmune diseases would be a nontoxic means of specifically neutralizing the autoreactive lymphocytes responsible for the disease. This goal has been realized in experimental autoimmunity models by immunizing rats or mice against their own autoimmune cells such that the animals generate an immune response specifically repressive to the disease-producing lymphocytes. This maneuver, termed lymphocyte vaccination, was demonstrated to be effective using some, but not all, autoimmune helper T-lymphocyte lines. We now report that T lymphocytes, otherwise incapable of triggering an immune response, can be transformed into effective immunogens by treating the cells in vitro with hydrostatic pressure. Clone A2b, as effector clone that recognized cartilage proteoglycan and caused adjuvant arthritis in Lewis rats, is such a cell. Untreated A2b could not trigger an immune response, but inoculating rats with pressure-treated A2b induced early remission of established adjuvant arthritis as well as resistance to subsequent disease. Specific resistance to arthritis was associated with anti-idiotypic T-cell reactivity to clone A2b and could be transferred from vaccinated rats to naive recipients using donor lymphoid cells. Aggregation of T-lymphocyte membrane components appeared to be important for an immune response because the effects of hydrostatic pressure could be reproduced by treatment of A2b with chemical cross-linkers or with agents disrupting the cytoskeleton. Populations of lymph node cells from antigen-primed rats, when treated with hydrostatic pressure, could also induce suppression of disease. Thus, effective vaccines can be developed without having to isolate the autoimmune T lymphocytes as lines or clones. These results demonstrate that effector T lymphocytes suitably treated may serve as agents for specifically controlling the immune system.

  12. Thermal influence of the Couette flow in a hydrostatic spindle on the machining precision

    NASA Astrophysics Data System (ADS)

    Chen, Dongju; Fan, Jinwei; Li, Haiyong; Wang, Xiaofeng; Zhang, Feihu

    2013-05-01

    Hydrostatic spindles are increasingly used in precision machine tools. Thermal error is the key factor affecting the machining accuracy of the spindle, and research has focused on spindle thermal errors through examination of the influence of the temperature distribution, thermal deformation and spindle mode. However, seldom has any research investigated the thermal effects of the associated Couette flow. To study the heat transfer mechanism in spindle systems, the criterion of the heat transfer direction according to the temperature distribution of the Couette flow at different temperatures is deduced. The method is able to deal accurately with the significant phenomena occurring at every place where thermal energy flowed in such a spindle system. The variation of the motion error induced by thermal effects on a machine work-table during machining is predicated by establishing the thermo-mechanical error model of the hydrostatic spindle for a high precision machine tool. The flow state and thermal behavior of a hydrostatic spindle is analyzed with the evaluated heat power and the coefficients of the convective heat transfer over outer surface of the spindle are calculated, and the thermal influence on the oil film stiffness is evaluated. Thermal drift of the spindle nose is measured with an inductance micrometer, the thermal deformation data 1.35 ?m after running for 4 h is consistent with the value predicted by the finite element analysis's simulated result 1.28 ?m, and this demonstrates that the simulation method is feasible. The thermal effects on the processing accuracy from the flow characteristics of the fluid inside the spindle are analyzed for the first time.

  13. Effects of hydrostatic pressure on biosynthetic activity during chondrogenic differentiation of MSCs in hybrid scaffolds.

    PubMed

    Karkhaneh, Akbar; Naghizadeh, Ziba; Shokrgozar, Mohammad Ali; Bonakdar, Shahin; Solouk, Atefeh; Haghighipour, Nooshin

    2014-02-01

    The objective of this study was to determine the effects of hydrostatic pressure (HP) on the biochemical properties and gene expression of mesenchymal stem cells (MSCs) on scaffolds for cartilage tissue engineering composed of poly(caprolactone) (PCL) poly(vinyl alcohol) (PVA) gelatin (GEL) semi interpenetrating polymer network (semi-IPN). The MSCs were cultured on PCL-PVA-GEL semi-IPN scaffolds in two groups (A and B) for 7 and 21 days, respectively, and then loaded with hydrostatic pressure (5 MPa, 0.5 Hz) for 2 h per day for the period of 7 days and compared with two non-loaded groups (C and D) as controls. DMMB and real-time PCR analysis for assaying cartilage-specific extracellular matrix (ECM) gene markers were carried out. According to the results, there were no significant differences in GAG amounts between the loaded and non-loaded constructs were observed after 14 days. However, significant and considerable increases in the expression amount of type II collagen mRNA levels in group A ( from 2.43 × 10-4 ± 5.32 × 10-5 to 2.09 × 10-3 ± 1.07 × 10-4 time), and in group B (from 3.04 × 10-4 ± 4.31 × 10-5 to 2.08 × 10-3 ± 1.59 × 10-4 time) in comparison with non-loaded groups (C and D) were observed, respectively. Results showed the beneficial role of hydrostatic pressure on the increase of type II collagen mRNA levels in articular cartilage tissue engineering. PMID:24619897

  14. Monitoring grizzly bear population trends

    USGS Publications Warehouse

    Eberhardt, L.L.; Knight, R.R.; Blanchard, B.M.

    1986-01-01

    A simple different equation model was developed to provide additional perspective on observed mortality and trend data on Yellowstone grizzly bears (Ursus arctos horribilis). Records of mortalities of adult females from 1959 to 1985 were utilized, in conjunction with data on females with cubs. The overall downward trend of observed numbers of females with cubs generally agrees with the model calculations but does not adequately reflect mortality from 1970 to 1974. The model may be useful in developing a composite index of population trend.

  15. Using a Bear Put Spread 

    E-print Network

    Bevers, Stan; Amosson, Stephen H.; Waller, Mark L.; Dhuyvetter, Kevin C.

    2008-10-07

    a bear put spread. In this example, assume the current Chicago Board of Trade December Corn contract is trad- ing at $6.00 per bushel. The associated December put option premiums are listed in Table 1. The producer begins the strategy by buying a... put op- tion near the money, in this case a $6.00 put op- tion for $0.90 per bushel ($4,500 per 5,000-bushel contract). At the same time, he also writes (sells) a put option with a strike price below the put option. In our example, he writes a $5...

  16. Residual Gas Motions in the Intracluster Medium and Bias in Hydrostatic Measurements of Mass Profiles of Clusters

    NASA Astrophysics Data System (ADS)

    Lau, Erwin T.; Kravtsov, Andrey V.; Nagai, Daisuke

    2009-11-01

    We present analysis of bulk and random gas motions in the intracluster medium using high-resolution Eulerian cosmological simulations of 16 simulated clusters, including both very relaxed and unrelaxed systems and spanning a virial mass range of 5 × 1013-2\\times 10^{15}\\,h^{-1}\\,{\\it\\, M_{\\odot }}. We investigate effects of the residual subsonic gas motions on the hydrostatic estimates of mass profiles and concentrations of galaxy clusters. In agreement with previous studies, we find that the gas motions contribute up to ?5%-15% of the total pressure support in relaxed clusters with contribution increasing with the cluster-centric radius. The fractional pressure support is higher in unrelaxed systems. This contribution would not be accounted for in hydrostatic estimates of the total mass profile and would lead to systematic underestimate of mass. We demonstrate that total mass can be recovered accurately if pressure due to gas motions measured in simulations is explicitly taken into account in the equation of hydrostatic equilibrium. Given that the underestimate of mass is increasing at larger radii, where gas is less relaxed and contribution of gas motions to pressure is larger, the total density profile derived from hydrostatic analysis is more concentrated than the true profile. This may at least partially explain some high values of concentrations of clusters estimated from hydrostatic analysis of X-ray data.

  17. A New Experimental System for the Extended Application of Cyclic Hydrostatic Pressure to Cell Culture

    PubMed Central

    Maul, Timothy M.; Hamilton, Douglas W.; Nieponice, Alejandro; Soletti, Lorenzo

    2007-01-01

    Mechanical forces have been shown to be important stimuli for the determination and maintenance of cellular phenotype and function. Many cells are constantly exposed in vivo to cyclic pressure, shear stress, and/or strain. Therefore, the ability to study the effects of these stimuli in vitro is important for understanding how they contribute to both normal and pathologic states. While there exist commercial as well as custom-built devices for the extended application of cyclic strain and shear stress, very few cyclic pressure systems have been reported to apply stimulation longer than 48 h. However, pertinent responses of cells to mechanical stimulation may occur later than this. To address this limitation, we have designed a new cyclic hydrostatic pressure system based upon the following design variables: minimal size, stability of pressure and humidity, maximal accessibility, and versatility. Computational fluid dynamics (CFD) was utilized to predict the pressure and potential shear stress within the chamber during the first half of a 1.0 Hz duty cycle. To biologically validate our system, we tested the response of bone marrow progenitor cells (BMPCs) from Sprague Dawley rats to a cyclic pressure stimulation of 120/80 mm Hg, 1.0 Hz for 7 days. Cellular morphology was measured using Scion Image, and cellular proliferation was measured by counting nuclei in ten fields of view. CFD results showed a constant pressure across the length of the chamber and no shear stress developed at the base of the chamber where the cells are cultured. BMPCs from Sprague Dawley rats demonstrated a significant change in morphology versus controls by reducing their size and adopting a more rounded morphology. Furthermore, these cells increased their proliferation under cyclic hydrostatic pressure. We have demonstrated that our system imparts a single mechanical stimulus of cyclic hydrostatic pressure and is capable of at least 7 days of continuous operation without affecting cellular viability. Furthermore, we have shown for the first time that BMPCs respond to cyclic hydrostatic pressure by alterations in morphology and increased proliferation. PMID:17227105

  18. Wormgear geometry adopted for implementing hydrostatic lubrication and formulation of the lubrication problem

    NASA Astrophysics Data System (ADS)

    Sun, D. C.; Yuan, Qin

    1995-01-01

    The geometrical parameters for a wormgear intended to be used as the transmission in advanced helicopters are finalized. The resulting contact pattern of the meshing tooth surfaces is suitable for the implementation of hydrostatic lubrication Fluid film lubrication of the contact is formulated considering external pressurization as well as hydrodynamic wedge and squeeze actions. The lubrication analysis is aimed at obtaining the oil supply pressure needed to separate the worm and gear surfaces by a prescribed minimum film thickness. The procedure of solving the mathematical problem is outlined.

  19. Hydrostatic level sensors as high precision ground motion instrumentation for Tevatron and other energy frontier accelerators

    NASA Astrophysics Data System (ADS)

    Volk, J.; Hansen, S.; Johnson, T.; Jostlein, H.; Kiper, T.; Shiltsev, V.; Chupyra, A.; Kondaurov, M.; Medvedko, A.; Parkhomchuk, V.; Singatulin, S.; Stetler, L.; Van Beek, J.; Fratta, D.; Roberts, J.; Wang, H.

    2012-01-01

    Particle accelerators require very tight tolerances on the alignment and stability of their elements: magnets, accelerating cavities, vacuum chambers, etc. In this article we describe the Hydrostatic Level Sensors (HLS) for very low frequency measurements used in a variety of facilities at Fermilab. We present design features of the sensors, outline their technical parameters, describe their test and calibration procedures, discuss different regimes of operation and give few illustrative examples of the experimental data. Detail experimental results of the ground motion measurements with these detectors will be presented in subsequent papers.

  20. Hydrostatic Level Sensors as High Precision Ground Motion Instrumentation for Tevatron and Other Energy Frontier Accelerators

    SciTech Connect

    Volk, James; Hansen, Sten; Johnson, Todd; Jostlein, Hans; Kiper, Terry; Shiltsev, Vladimir; Chupyra, Andrei; Kondaurov, Mikhail; Medvedko, Anatoly; Parkhomchuk, Vasily; Singatulin, Shavkat

    2012-01-01

    Particle accelerators require very tight tolerances on the alignment and stability of their elements: magnets, accelerating cavities, vacuum chambers, etc. In this article we describe the Hydrostatic Level Sensors (HLS) for very low frequency measurements used in a variety of facilities at Fermilab. We present design features of the sensors, outline their technical parameters, describe their test and calibration procedures, discuss different regimes of operation and give few illustrative examples of the experimental data. Detail experimental results of the ground motion measurements with these detectors will be presented in subsequent papers.

  1. Fiber optic liquid crystalline hydrostatic pressure sensor with gradient-index rod lenses

    NASA Astrophysics Data System (ADS)

    Wolinski, Tomasz R.; Staronski, Leszek R.; Jarmolik, Aleksandra; Domanski, Andrzej W.

    1994-11-01

    A further development of the fiber optic hydrostatic pressure sensor with a liquid crystal film acting as a sensing element is presented. To enhance the amount of the optical signal entering the liquid crystal optrode gradient index (GRIN) rod lenses have been used in the pressure environment. The paper discusses the effect of stress induced birefringence in a GRIN lens, its influence on defocusing phenomena under pressure and the optimized configuration of the fiber optic liquid crystal sensor preset for a required range of pressure.

  2. A High Precision Double Tubed Hydrostatic Leveling System for Accelerator Alignment Applications

    SciTech Connect

    Singatulin, Shavkat; Volk, J.; Shiltsev, V.; Chupyra, A.; Medvedko, A.; Kondaurov, M.

    2006-09-01

    Since 1998 several hydrostatic leveling systems (HLS) have been installed in different locations at Fermilab. This work was in collaboration with Budker Institute and SLAC. All systems were either half-filled pipe (HF) or full-filled pipe (FF). Issues assembling HLS are covered in this article. An improved and cost-effective water system with temperature stabilized of water media is presented. This proposal is a double-tube full-filled DT-FF system. Examples of hardware configurations are included for systems located at Fermilab.

  3. Cell compressibility studies utilizing noncontact hydrostatic pressure measurements on single living cells in a microchamber

    NASA Astrophysics Data System (ADS)

    Lin, L. A. G.; Liu, A. Q.; Yu, Y. F.; Zhang, C.; Lim, C. S.; Ng, S. H.; Yap, P. H.; Gao, H. J.

    2008-06-01

    A micro-optical-fluidic system (MOFS), which integrates a force generating device and an optical detector, is designed to measure the bulk modulus of a single living cell in real time under a controlled hydrostatic pressure. In this design, the accuracy of the bulk modulus measurement is improved because neither the force generating device nor the optical detector needs to be in contact with the cells. The MOFS device has been used to investigate the mechanotransduction of THP-1 human acute monocytic leukemia cells and the effects of the toxin lipopolysaccharide and colchicine on various properties of these cells.

  4. The dual action gas thrust bearing - A new high load bearing concept

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    The principle of utilizing hydrodynamic effects in diverging films for improving load capacity in gas thrust bearings is discussed. A new concept of dual action bearing based on that principle is described and analyzed. The potential of the new bearing is demonstrated both analytically for an infinitely long slider and by numerical solution for a flat sector shaped thrust bearing. It is shown that the dual action bearing can extend substantially the range of load carrying capacity in gas lubricated thrust bearings and improve their efficiency.

  5. Magnetic bearings - State of the art

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    1993-01-01

    Magnetic bearings have existed for many years, at least in theory. Earnshaw's theorem, formulated in 1842, concerns stability of magnetic suspensions, and states that not all axes of a bearing can be stable without some means of active control. In Beam's widely referenced experiments, a tiny (1/64 in diameter) rotor was rotated to the astonishing speed of 800,000 rps while it was suspended in a magnetic field. Despite a long history, magnetic bearings have only begun to see practical application since about 1980. The development that finally made magnetic bearings practical was solid state electronics, enabling power supplies and controls to be reduced in size to where they are now comparable in volume to the bearings themselves. An attempt is made to document the current (1991) state of the art of magnetic bearings. The referenced papers are large drawn from two conferences publications published in 1988 and 1990 respectively.

  6. Magnetic bearings-state of the art

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    1991-01-01

    Magnetic bearings have existed for many years, at least in theory. Earnshaw's theorem, formulated in 1842, concerns stability of magnetic suspensions, and states that not all axes of a bearing can be stable without some means of active control. In Beam's widely referenced experiments, a tiny (1/64 in diameter) rotor was rotated to the astonishing speed of 800,000 rps while it was suspended in a magnetic field. Despite a long history, magnetic bearings have only begun to see practical application since about 1980. The development that finally made magnetic bearings practical was solid state electronics, enabling power supplies and controls to be reduced in size to where they are now comparable in volume to the bearings themselves. An attempt is made to document the current (1991) state of the art of magnetic bearings. The referenced papers are large drawn from two conferences publications published in 1988 and 1990 respectively.

  7. hydrostatic pressurisation

    E-print Network

    Paris-Sud XI, Université de

    -II flow heat exchanger disks with blades 10-4 10-3 10-2 10-6 10-5 10-4 k-5/3 kz /2 E(kz)[m2 s-1 ] 10-5 10 turbulence PACS 67.57.De ­ Superflow and hydrodynamics in quantum fluids and solids: liquid and solid helium Abstract ­ Turbulence in superfluid helium is unusual and presents a challenge to fluid dynam- icists

  8. Rocketdyne LOX bearing tester program

    NASA Technical Reports Server (NTRS)

    Keba, J. E.; Beatty, R. F.

    1988-01-01

    The cause, or causes, for the Space Shuttle Main Engine ball wear were unknown, however, several mechanisms were suspected. Two testers were designed and built for operation in liquid oxygen to empirically gain insight into the problems and iterate solutions in a timely and cost efficient manner independent of engine testing. Schedules and test plans were developed that defined a test matrix consisting of parametric variations of loading, cooling or vapor margin, cage lubrication, material, and geometry studies. Initial test results indicated that the low pressure pump thrust bearing surface distress is a function of high axial load. Initial high pressure turbopump bearing tests produced the wear phenomenon observed in the turbopump and identified an inadequate vapor margin problem and a coolant flowrate sensitivity issue. These tests provided calibration data of analytical model predictions to give high confidence in the positive impact of future turbopump design modification for flight. Various modifications will be evaluated in these testers, since similar turbopump conditions can be produced and the benefit of the modification will be quantified in measured wear life comparisons.

  9. Effect of Rolling Bearing Refurbishment and Restoration on Bearing Life and Reliability

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.; Branzai, Emanuel V.

    2005-01-01

    For nearly four decades it has been a practice in commercial and military aircraft application that rolling-element bearings removed at maintenance or overhaul be reworked and returned to service. The work presented extends previously reported bearing 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 bearing races subject to bearing rework. Depending on the extent of rework and based upon theoretical analysis, representative life factors (LF) for bearings subject to rework ranged from 0.87 to 0.99 the lives of new bearings. Based on bearing endurance data, 92 percent of the bearing sets that would be subject to rework would result in L(10) lives equaling and/or exceeding that predicted for new bearings with the remaining 8 percent having the potential to achieve the analytically predicted life of new bearings when one of the rings is replaced at rework.. The potential savings from bearing rework varies from 53 to 82 percent that of new bearings depending on the cost, size and complexity of the bearing.

  10. Quantifying oil filtration effects on bearing life

    Microsoft Academic Search

    W. M. Needelman; E. V. Zaretsky

    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 Lââ or catalog life based upon oil filter rating.

  11. Notes 16. Analysis of tilting pad bearings 

    E-print Network

    San Andres, Luis

    2010-01-01

    NOTES 16. STATIC AND DYNAMIC FORCED PERFORMANCE OF TILTING PAD BEARINGS: ANALYSIS INCLUDING PIVOT STIFFNESS Dr. Luis San Andr?s Mast-Childs Professor August 2010 SUMMARY Work in progress ? still a lot of be done Introduction... Figure 1 shows a tilting pad journal bearing comprised of four pads. Each pad tilts about its pivot making a hydrodynamic film that generates a pressure reacting to the static load applied on the spinning journal. This type of bearing is typically...

  12. Cantilever mounted resilient pad gas bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I. (inventor)

    1978-01-01

    A gas-lubricated bearing is described, employing at least one pad mounted on a rectangular cantilever beam to produce a lubricating wedge between the face of the pad and a moving surface. The load-carrying and stiffness characteristics of the pad are related to the dimensions and modulus of elasticity of the beam. The bearing is applicable to a wide variety of types of hydrodynamic bearings.

  13. Hybrid air foil bearing with external pressurization

    E-print Network

    Park, Soongook

    2009-05-15

    . Heshmat [8], calculated load carrying capacity using Finite Difference (FD) and Finite Element (FE) Method for better design of foil bearings. Peng and Khonsari [9] presented thermohydrodynamic analyses on temperature distribution of the air film... and compared with experimental results. DellaCorte [10] presented a rule of thumb-based analytical formula predicting comparative load capacities of various air foil bearings, and provides design guidelines of air foil bearing. Kim and San Andr?s [11...

  14. Static forces in a superconducting magnet bearing

    SciTech Connect

    Stoye, P.; Fuchs, G. [Institut fuer Festkoerper- und Werkstofforschung, Dresden (Germany)] [Institut fuer Festkoerper- und Werkstofforschung, Dresden (Germany); Gawalek, W.; Goernert, P. [Institut fuer Physikalische Hochtechnologie, Jena (Germany)] [Institut fuer Physikalische Hochtechnologie, Jena (Germany); Gladun, A. [Technische Univ., Dresden (Germany)] [Technische Univ., Dresden (Germany)

    1995-11-01

    Static levitation forces and stiffnesses in a superconducting bearing consisting of concentric ring magnets and a superconducting YBaCuO ring are investigated. In the field-cooled mode a levitation force of 20 N has been achieved. The axial and radial stiffnesses have values of 15 N/mm and 10 N/mm, respectively. An arrangement with two bearings supporting a high speed shaft is now under development. A possible application of superconducting magnetic bearings is flywheels for energy storage.

  15. Fractional Whirl Motion in Wave Journal Bearings

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin; Hendricks, Robert C.

    1996-01-01

    Unloaded gas, plain journal bearings experience sub-synchronous whirl motion due to fluid film instabilities and wall contact usually occurs immediately after the onset of the whirl motion. An alternative is the wave journal bearing which significantly improves bearing 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 bearing 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 bearing can run in a whirl orbit well within the bearing clearance. At large clearances and wave amplitudes a two-wave bearing, unliKe other bearings, 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 bearing 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.

  16. Polar Bears International: Vital Maternity Den Study

    NSDL National Science Digital Library

    This report describes a journalist's participation in a study of polar bear denning sites in the Alaska National Wildlife Refuge (ANWR). It is thought that cubs born in those dens play an important role in maintaining the Beaufort Sea population of polar bears. Prior to the study, no complete map existed pinpointing the ANWR's denning areas. The study data will be available to manage human activities, thus protecting the sensitive areas in which a mother polar bear may den. The study will also provide baseline data to assess how climate change may alter the distribution of polar-bear denning habitat.

  17. Effects of hydrostatic pressure on the electrical properties of hexagonal Ge2Sb2Te5: Experimental and theoretical approaches

    NASA Astrophysics Data System (ADS)

    Xu, B.; Su, Y.; Liu, Z. G.; Zhang, C. H.; Xia, Y. D.; Yin, J.; Xu, Z.; Ren, W. C.; Xiang, Y. H.

    2011-04-01

    A combination of experiments and first-principles method calculations has been applied to investigate the influence of the hydrostatic pressure on the electrical properties of the phase-change material hexagonal Ge2Sb2Te5 (h-GST). Experimentally, it is found that the resistance of h-GST declines monotonically with increasing hydrostatic pressure up to 0.7 GPa. Theoretically, the band-structure calculations revealed that the electronic band gap also decreases with the pressure. The hydrostatic pressure increases the conductivity of h-GST by reducing the electronic band gap. The dEg/dP obtained from theoretical calculations and the d ln ? /dP by experimental result are in the same order of magnitude.

  18. 63 FR 40878 - Antifriction Bearings (Other Than Tapered Roller Bearings) and Parts Thereof From Italy, Romania...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1998-07-31

    ...Bearings) and Parts Thereof From Italy, Romania, and the United Kingdom; Amended Final...from France, Germany, Italy, Japan, Romania, Singapore, Sweden, and the United...with regard to ball bearings from Italy, Romania and the United Kingdom. Based on...

  19. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    NASA Technical Reports Server (NTRS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1993-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing 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 bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  20. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    NASA Technical Reports Server (NTRS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing 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 bearings including auxiliary bearings. 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 bearing when one coil fails is studied.

  1. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    NASA Astrophysics Data System (ADS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-06-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing 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 bearings including auxiliary bearings. 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 bearing when one coil fails is studied.

  2. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    NASA Astrophysics Data System (ADS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing 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 bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  3. Hydrostatic deformation potentials and the question of exciton binding energies and splittings in aluminium nitride

    NASA Astrophysics Data System (ADS)

    Gil, Bernard

    2010-05-01

    By comparing a series of optical experiments performed on bulk aluminum nitride crystals and heteroepitaxial films, we determine the hydrostatic excitonic deformation potentials of AlN. The agreement between the whole available experimental data and our analysis consolidates this determination. Using the previously determined values of the valence-band deformation potentials which account for the strain-induced variation in the crystal-field splitting: d3=-8.19eV and d4=4.10eV we obtain values of -6.04 and 2.15 eV for the hydrostatic excitonic deformation potentials a1 and a2 in the context of the quasicubic approximation. This constitutes the first series of values coherent with the whole set of experimental data. The experimental value of 1s-2s splitting disagrees with the theory of excitons in anisotropic semiconductors. This disagreement, we attribute it to our poor knowledge of the valence-band dispersion relations of AlN and to the difficulty we face for including in the calculation plausible values for the anisotropic hole effective mass, dielectric constant.

  4. Effects of Hydrostatic Loading on a Self-Aggregating, Suspension Culture–Derived Cartilage Tissue Analog

    PubMed Central

    Kraft, Jeffrey J.; Jeong, Changhoon; Novotny, John E.; Seacrist, Thomas; Chan, Gilbert; Domzalski, Marcin; Turka, Christina M.; Richardson, Dean W.; Dodge, George R.

    2011-01-01

    Objective: Many approaches are being taken to generate cartilage replacement materials. The goal of this study was to use a self-aggregating suspension culture model of chondrocytes with mechanical preconditioning. Design: Our model differs from others in that it is based on a scaffold-less, self-aggregating culture model that produces a cartilage tissue analog that has been shown to share many similarities with the natural cartilage phenotype. Owing to the known loaded environment under which chondrocytes function in vivo, we hypothesized that applying force to the suspension culture–derived chondrocyte biomass would improve its cartilage-like characteristics and provide a new model for engineering cartilage tissue analogs. Results: In this study, we used a specialized hydrostatic pressure bioreactor system to apply mechanical forces during the growth phase to improve biochemical and biophysical properties of the biomaterial formed. We demonstrated that using this high-density suspension culture, a biomaterial more consistent with the hyaline cartilage phenotype was produced without any foreign material added. Unpassaged chondrocytes responded to a physiologically relevant hydrostatic load by significantly increasing gene expression of critical cartilage molecule collagen and aggrecan along with other cartilage relevant genes, CD44, perlecan, decorin, COMP, and iNOS. Conclusions: This study describes a self-aggregating bioreactor model without foreign material or scaffold in which chondrocytes form a cartilage tissue analog with many features similar to native cartilage. This study represents a promising scaffold-less, methodological advancement in cartilage tissue engineering with potential translational applications to cartilage repair.

  5. Fourier analysis for hydrostatic pressure sensing in a polarization-maintaining photonic crystal fiber

    SciTech Connect

    Childs, Paul; Wong, Allan C. L.; Fu, H. Y.; Liao, Yanbiao; Tam, Hwayaw; Lu Chao; Wai, P. K. A.

    2010-12-20

    .We measured the hydrostatic pressure dependence of the birefringence and birefringent dispersion of a Sagnac interferometric sensor incorporating a length of highly birefringent photonic crystal fiber using Fourier analysis. Sensitivity of both the phase and chirp spectra to hydrostatic pressure is demonstrated. Using this analysis, phase-based measurements showed a good linearity with an effective sensitivity of 9.45nm/MPa and an accuracy of {+-}7.8kPa using wavelength-encoded data and an effective sensitivity of -55.7cm{sup -1}/MPa and an accuracy of {+-}4.4kPa using wavenumber-encoded data. Chirp-based measurements, though nonlinear in response, showed an improvement in accuracy at certain pressure ranges with an accuracy of {+-}5.5kPa for the full range of measured pressures using wavelength-encoded data and dropping to within {+-}2.5kPa in the range of 0.17 to 0.4MPa using wavenumber-encoded data. Improvements of the accuracy demonstrated the usefulness of implementing chirp-based analysis for sensing purposes.

  6. Dynamic hydrostatic pressure enhances differentially the chondrogenesis of meniscal cells from the inner and outer zone.

    PubMed

    Zellner, J; Mueller, M; Xin, Y; Krutsch, W; Brandl, A; Kujat, R; Nerlich, M; Angele, P

    2015-06-01

    This study analyses the influence of dynamic hydrostatic pressure on chondrogenesis of human meniscus-derived fibrochondrocytes and explores the differences in chondrogenic differentiation under loading conditions between cells derived from the avascular inner zone and vascularized outer region of the meniscus. Aggregates of human fibrochondrocytes with cell origin from the inner region or with cell origin from the outer region were generated. From the two groups of either cell origin, aggregates were treated with dynamic hydrostatic pressure (1Hz for 4h; 0.55-5.03MPa, cyclic sinusoidal) from day 1 to day 7. The other aggregates served as unloaded controls. At day 0, 7, 14 and 21 aggregates were harvested for evaluation including histology, immunostaining and ELISA analysis for glycosaminoglycan (GAG) and collagen II. Loaded aggregates were found to be macroscopically larger and revealed immunohistochemically enhanced chondrogenesis compared to the corresponding controls. Loaded or non-loaded meniscal cells from the outer zone showed a higher potential and earlier onset of chondrogenesis compared to the cells from the inner part of the meniscus. This study suggests that intrinsic factors like cell properties in the different areas of the meniscus and their reaction on mechanical load might play important roles in designing Tissue Engineering strategies for meniscal repair in vivo. PMID:25698240

  7. Hydrostatically coupled dielectric elastomer actuators for tactile displays and cutaneous stimulators

    NASA Astrophysics Data System (ADS)

    Carpi, Federico; Frediani, Gabriele; De Rossi, Danilo

    2010-04-01

    Hydrostatic coupling has been recently reported as a means to improve versatility and safety of dielectric elastomer (DE) actuators. Hydrostatically coupled DE actuators rely on an incompressible fluid that mechanically couples a DE-based active part to a passive part interfaced to the load. In this paper, we present ongoing development of bubble-like versions of such transducers, made of silicone and oil. In particular, the paper describes millimeter-scale actuators, currently being developed as soft, light, acoustically silent and cheap devices for two types of applications: tactile displays and cutaneous stimulators. In both cases, the most significant advantages of the proposed technology are represented by high versatility for design (due to the fluid based transmission mechanism), tailorable stiffness perceived by the user (obtained by adjusting the internal fluid pressure), and suitable electrical safety (enabled by both a passive interface with the user and the insulating internal fluid). Millimeter-scale prototypes showed a resonance frequency of about 250 Hz, which represents the value at which Pacinian cutaneous mechanoreceptors exhibit maximum sensitivity; this provides an optimum condition to eventually code tactile information dynamically, either in combination or as an alternative to static driving.

  8. Development and evaluation of a hydrostatic dynamical core using the spectral element/discontinuous Galerkin methods

    NASA Astrophysics Data System (ADS)

    Choi, S.-J.; Giraldo, F. X.

    2014-06-01

    In this paper, we present a dynamical core for the atmospheric primitive hydrostatic equations using a unified formulation of spectral element (SE) and discontinuous Galerkin (DG) methods in the horizontal direction with a finite difference (FD) method in the radial direction. The CG and DG horizontal discretization employs high-order nodal basis functions associated with Lagrange polynomials based on Gauss-Lobatto-Legendre (GLL) quadrature points, which define the common machinery. The atmospheric primitive hydrostatic equations are solved on the cubed-sphere grid using the flux form governing equations in a three-dimensional (3-D) Cartesian space. By using Cartesian space, we can avoid the pole singularity problem due to spherical coordinates and this also allows us to use any quadrilateral-based grid naturally. In order to consider an easy way for coupling the dynamics with existing physics packages, we use a FD in the radial direction. The models are verified by conducting conventional benchmark test cases: the Rossby-Haurwitz wavenumber 4, Jablonowski-Williamson tests for balanced initial state and baroclinic instability, and Held-Suarez tests. The results from those tests demonstrate that the present dynamical core can produce numerical solutions of good quality comparable to other models.

  9. Crystallization of a Li2O2SiO2 Glass under High Hydrostatic Pressures

    NASA Technical Reports Server (NTRS)

    Fuss, T.; Day, D. E.; Lesher, C. E.; Ray, C. S.

    2004-01-01

    The crystallization behavior of a Li2O.2SiO2 (LS2) glass subjected to a uniform hydrostatic pressure of 4.5 or 6 GPa was investigated between 550 and 800 C using XRD, IR, Raman, TEM, NMR, and DTA. The density of the glass subjected to 6 GPa was between 2.52 plus or minus 0.01 and 2.57 plus or minus 0.01 grams per cubic centimeters, depending upon the processing temperatures, and was higher than that of the stoichiometric LS2 crystals, 2.46 plus or minus 0.01 grams per cubic centimeter. Thus, crystallization in 6 GPa glass occurred in a condition of negative volume dilatation, deltaV = V(sub glass) - V(sub crystal), while that for the 4.5 GPa glass occurred in the condition deltaV greater than 0. For deltaV greater than 0, which also includes the control glass at ambient (one atmosphere) pressure, the glasses always crystallize Li2Si2O5 (orthorhombic, Ccc2) crystals, but for deltaV less than 0 (6 GPa), the glasses crystallize Li2SiO3 crystals with a slightly deformed structure. The crystal growth rate vs. temperature curve moved to higher temperature with increasing pressure, and was independent of the sign of deltaV. These results for the effect of hydrostatic pressure on the crystallization of LS2 glass were discussed from thermodynamic considerations.

  10. Microstructure and mechanical properties of duplex stainless steel subjected to hydrostatic extrusion

    SciTech Connect

    Maj, P., E-mail: Piotr.maj@inmat.pw.edu.pl [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wo?oska 141, 02-507 Warsaw (Poland); Adamczyk-Cie?lak, B.; Mizera, J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wo?oska 141, 02-507 Warsaw (Poland); Pachla, W. [High Pressure Research Center, Polish Academy of Sciences, Soko?owska 29, 01-142 Warsaw (Poland); Kurzyd?owski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wo?oska 141, 02-507 Warsaw (Poland)

    2014-07-01

    The nanostructure and mechanical properties of ferritic-austenitic duplex stainless steel subjected to hydrostatic extrusion were examined. The refinement of the structure in the initial state and in the two deformation states (? = 1.4 and ? = 3.8) was observed in an optical microscope (OM) and a transmission electron microscope (TEM). The results indicate that the structure evolved from microcrystalline with a grain size of about 4 ?m to nanocrystalline with a grain size of about 150 nm in ferrite and 70 nm in austenite. The material was characterized mechanically by tensile tests performed in the two deformation states. The ultimate strength appeared to increase significantly compared to that in the initial deformation stages, which can be attributed to the grain refinement and plastic deformation. The heterogeneity observed in microregions results from the dual-phase structure of the steel. The results indicate that hydrostatic extrusion is a highly potential technology suitable for improving the properties of duplex steels. - Highlights: • Duplex stainless steel was hydro extruded to a total strain of 3.8 • After the last stage of deformation heterogeneous structure was obtained in the material • As a result of stresses non-diffusive transformation ???’ occurred in the material • Nanometric (sub)grains were obtained in the austenite regions.

  11. Failure assessment of aluminum liner based filament-wound hybrid riser subjected to internal hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Dikshit, Vishwesh; Seng, Ong Lin; Maheshwari, Muneesh; Asundi, A.

    2015-03-01

    The present study describes the burst behavior of aluminum liner based prototype filament-wound hybrid riser under internal hydrostatic pressure. The main objective of present study is to developed an internal pressure test rig set-up for filament-wound hybrid riser and investigate the failure modes of filament-wound hybrid riser under internal hydrostatic burst pressure loading. The prototype filament-wound hybrid riser used for burst test consists of an internal aluminum liner and outer composite layer. The carbon-epoxy composites as part of the filament-wound hybrid risers were manufactured with [±55o] lay-up pattern with total composite layer thickness of 1.6 mm using a CNC filament-winding machine. The burst test was monitored by video camera which helps to analyze the failure mechanism of the fractured filament-wound hybrid riser. The Fiber Bragg Grating (FBG) sensor was used to monitor and record the strain changes during burst test of prototype filament-wound hybrid riser. This study shows good improvements in burst strength of filament-wound hybrid riser compared to the monolithic metallic riser. Since, strain measurement using FBG sensors has been testified as a reliable method, we aim to further understand in detail using this technique.

  12. Prediction of acid lactic-bacteria growth in turkey ham processed by high hydrostatic pressure

    PubMed Central

    Mathias, S.P.; Rosenthal, A.; Gaspar, A.; Aragão, G.M.F.; Slongo-Marcusi, A.

    2013-01-01

    High hydrostatic pressure (HHP) has been investigated and industrially applied to extend shelf life of meat-based products. Traditional ham packaged under microaerophilic conditions may sometimes present high lactic acid bacteria population during refrigerated storage, which limits shelf life due to development of unpleasant odor and greenish and sticky appearance. This study aimed at evaluating the shelf life of turkey ham pressurized at 400 MPa for 15 min and stored at 4, 8 and 12 °C, in comparison to the non pressurized product. The lactic acid bacteria population up to 107 CFU/g of product was set as the criteria to determine the limiting shelf life According to such parameter the pressurized sample achieved a commercial viability within 75 days when stored at 4 °C while the control lasted only 45 days. Predictive microbiology using Gompertz and Baranyi and Roberts models fitted well both for the pressurized and control samples. The results indicated that the high hydrostatic pressure treatment greatly increased the turkey ham commercial viability in comparison to the usual length, by slowing down the growth of microorganisms in the product. PMID:24159279

  13. Non-Hydrostatic Modelling of Waves and Currents over Subtle Bathymetric Features

    NASA Astrophysics Data System (ADS)

    Gomes, E.; Mulligan, R. P.; McNinch, J.

    2014-12-01

    Localized areas with high rates of shoreline erosion on beaches, referred to as erosional hotspots, can occur near clusters of relict shore-oblique sandbars. Wave transformation and wave-driven currents over these morphological features could provide an understanding of the hydrodynamic-morphologic coupling mechanism that connects them to the occurrence of erosional hotspots. To investigate this, we use the non-hydrostatic SWASH model that phase-resolves the free surface and fluid motions throughout the water column, allowing for high resolution of wave propagation and breaking processes. In this study we apply a coupled system of nested models including SWAN over a large domain of the North Carolina shelf with smaller nested SWASH domains in areas of interest to determine the hydrodynamic processes occurring over shore oblique bars. In this presentation we focus on a high resolution grid (10 vertical layers, 10 m horizontal resolution) applied to the Duck region with model validation from acoustic wave and current data, and observations from the Coastal Lidar And Radar Imaging System (CLARIS). By altering the bathymetry input for each model run based on bathymetric surveys and comparing the predicted and observed wave heights and current profiles, the effects of subtle bathymetric perturbations have on wave refraction, wave breaking, surf zone currents and vorticity are investigated. The ability to predict wave breaking and hydrodynamics with a non-hydrostatic model may improve our understanding of surf zone dynamics in relation to morphologic conditions.

  14. Lens intracellular hydrostatic pressure is generated by the circulation of sodium and modulated by gap junction coupling

    PubMed Central

    Gao, Junyuan; Sun, Xiurong; Moore, Leon C.; White, Thomas W.; Brink, Peter R.

    2011-01-01

    We recently modeled fluid flow through gap junction channels coupling the pigmented and nonpigmented layers of the ciliary body. The model suggested the channels could transport the secretion of aqueous humor, but flow would be driven by hydrostatic pressure rather than osmosis. The pressure required to drive fluid through a single layer of gap junctions might be just a few mmHg and difficult to measure. In the lens, however, there is a circulation of Na+ that may be coupled to intracellular fluid flow. Based on this hypothesis, the fluid would cross hundreds of layers of gap junctions, and this might require a large hydrostatic gradient. Therefore, we measured hydrostatic pressure as a function of distance from the center of the lens using an intracellular microelectrode-based pressure-sensing system. In wild-type mouse lenses, intracellular pressure varied from ?330 mmHg at the center to zero at the surface. We have several knockout/knock-in mouse models with differing levels of expression of gap junction channels coupling lens fiber cells. Intracellular hydrostatic pressure in lenses from these mouse models varied inversely with the number of channels. When the lens’ circulation of Na+ was either blocked or reduced, intracellular hydrostatic pressure in central fiber cells was either eliminated or reduced proportionally. These data are consistent with our hypotheses: fluid circulates through the lens; the intracellular leg of fluid circulation is through gap junction channels and is driven by hydrostatic pressure; and the fluid flow is generated by membrane transport of sodium. PMID:21624945

  15. Evaluation of bearing configurations using the single bearing tester in liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Jett, T.; Hall, P.; Thom, R.

    1991-01-01

    Various bearing configurations were tested using the Marshall Space Flight Center single bearing tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore bearing. The bearing 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.

  16. Improvement of the subgrid vertical mixing parameterization in operational hydrostatic models at Météo-France

    NASA Astrophysics Data System (ADS)

    Bouteloup, Y.; Bazile, E.; Bouyssel, F.; Marquet, P.

    2009-09-01

    A global variable mesh model (ARPEGE), an hydrostatic limited area model (ALADIN) with a 9.5km resolution over several regions of the world and a non-hydrostatic 2.5km resolution model (AROME) over France are used operationally at Météo-France for weather forecasting. Important modifications of the subgrid vertical mixing parameterization used in the hydrostatic models became operational in February 2009. The turbulence scheme (Louis, 1979) associated to a pseudo-shallow convection parameterization (Geleyn, 1987) has been replaced by a prognostic Turbulent Kinetic Energy scheme (TKE) associated to a mass flux shallow convection scheme. This development is characterised by a broad convergence between the parameterizations used in hydrostatic models with those of the operational non-hydrostatic model AROME. The prognostic TKE scheme (Cuxart et al, 2000) is used with the tuning coefficients of AROME. The mixing length is computed using the formulation of Bougeault and Lacarrère (1989) (BL89) but with a modified combination between Lup and ldown. To improve the representation of stratocumulus, the scheme uses a top-Planetary Boundary Layer (PBL) entrainment parameterization following the ideas of Grenier and Bretherton (2001), with a modified integral formulation. The shallow convection mass flux scheme is described in Bechtold et al. (2001). To solve a problem of too strong wind in the tropical PBL, it was found beneficial to amend both the mixing length and the TKE, following the approach of Lock and Mailhot (2006). The main idea of the connection between the shallow convection scheme and the turbulence scheme is to suppose that in a PBL, where occurs shallow convection, the turbulent mixing is enhanced by the presence of clouds. First, a thermal production term of TKE coming from the shallow convection scheme is computed. Secondly, a local modification of the BL89 mixing length is used. The BL89 mixing length is computed using the dry buoyancy and doesn't take into account the phase changes of water. In a cloud layer the result is an underestimation of the mixing length. The new approach consists of getting the thickness of the cloud from the shallow convection parameterization. When a shallow convection cloud is present upward (Lup) and downward (Ldown) computed mixing lengths are now taken at least equal to the distance between the current level and the top (respectively the bottom) of the cloud. 1:Bechtold, P., Bazile, E., Guichard, F., Mascart, P. and Richard, E., 2001 : A mass-flux convection scheme for regional and global models. Quart. J. R. Met. Soc., 127, p.869-886. 2. Bougeault, Ph., and Lacarrère, P., 1989 : Parameterization of orography-induced in meso-beta-scale model. Mon. Wea. Rev., 117, p.1872-1891. 3. Cuxart, J., Bougeault, Ph. And Redelsperger, J-L., 2000 : A turbulence scheme allowing for mesoscale and large-eddy simulations. Quart. J. R. Met. Soc., 126, p.1-30. 4. Geleyn, J.F., 1987 : Use of a modified Richardson number for parameterizing the effect of shallow convection. Short-and Medium-Range Numerical Weather Prediction (also WMO/IUGG NWP Symposium special issue), Tokyo, 4-8 August 1986). Special Volume of J. Meteor. Soc. Japan, T. Matsumo ed., p.141-149. 5. Grenier, H., and Bretherton, C. S., 2001 : A moist PBL parameterization for large scale models and its application ti subtropical cloud-topped marine boundary layers. Mon. Wea. Rev., 129, p.357-377. 6. Lock, A. and Mailhot, J. 2006 : Combining non-local scalings with a tke closure for mixing in boundary-layer clouds. Bound.-Layer Meteor., 121, p 313-338. 7. Louis, J.F., 1979 : A parametric model of vertical eddy fluxes in the atmosphere. Bound. Layer Meteor., 17, p.187-202.

  17. Simultaneous measurement of temperature, hydrostatic pressure and acoustic signal using a single distributed Bragg reflector fiber laser

    NASA Astrophysics Data System (ADS)

    Tan, Yan-Nan; Zhang, Yang; Guan, Bai-Ou

    2011-05-01

    A fiber-optic sensor based on a dual polarization fiber grating laser for simultaneous measurement of temperature, hydrostatic pressure and acoustic signal is proposed and experimentally demonstrated. The acoustic wave induces a frequency modulation (FM) of the carrier in radio frequency (RF) range generated by the fiber laser and can be easily extracted by using the FM demodulation technique. The temperature can be determined by the laser wavelength. The hydrostatic pressure can be determined by monitoring the static shift of the carrier frequency and deducting the effect of the temperature.

  18. Unstable polar mode and minimum of the dielectric constant in cubic BaSnO3 under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Bévillon, Émile; Geneste, Grégory

    2007-06-01

    From first-principles density-functional theory calculations, we show that above a given hydrostatic pressure, an unstable TO mode appears in the cubic perovskite barium stannate (BaSnO3) at ? . Below this critical pressure, we predict an interesting lowering of the dielectric response of this compound due to a change in the sign of this TO mode effective charge. The results are compared to recent calculations on perovskites under high pressure (titanates, zirconates, and niobates), which exhibit a different mechanism at the origin of the soft mode, and to magnesium silicate (MgSiO3) that does not undergo any ferroelectric transition under hydrostatic pressure.

  19. 61 FR 60679 - Antifriction Bearings (Other than Tapered Roller Bearings) and Parts Thereof from Romania...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1996-11-29

    ...Roller Bearings) and Parts Thereof from Romania; Preliminary Results of Antidumping Duty...bearings) and parts thereof (AFBs), from Romania. The review covers shipments of the subject...on ball bearings and parts thereof from Romania. On June 22, 1994 (59 FR...

  20. 62 FR 32292 - Antifriction Bearings (Other Than Tapered Roller Bearings) and Parts Thereof From Romania; Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1997-06-13

    ...Roller Bearings) and Parts Thereof From Romania; Final Results of Antidumping Duty Administrative...bearings) and parts thereof (AFBs), from Romania. The period of review (POR) is May...duty order on BBs and parts thereof from Romania. See Antifriction Bearings (Other...

  1. Unbalance Response Prediction for Rotors on Ball Bearings Using Speed and Load Dependent Nonlinear Bearing Stiffness

    NASA Technical Reports Server (NTRS)

    Fleming, David P.; Poplawski, J. V.

    2003-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic analysis requires that bearing forces corresponding to the actual bearing deflection be utilized. For this work bearing forces were calculated by COBRA-AHS, a recently developed rolling-element bearing analysis code. Bearing stiffness was found to be a strong function of bearing deflection, with higher deflection producing markedly higher stiffness. Curves fitted to the bearing 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 bearing vibration amplitude over part of the speed range compared to the case of constant bearing 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 bearings.

  2. Remote Detection of Bearing Fatigue Spalls via the Dynamic Response of Bearings on the Same Shaft

    Microsoft Academic Search

    David Tow; Sean Marble

    2007-01-01

    Turbine engine bearing failures are the leading mechanical cause of class-A failures. The most common mode of bearing failure in turbine engine applications is fatigue spalling. This paper describes a sensor capable of monitoring multiple bearings on a common shaft for the presence of fatigue spalls. Experimental data is presented demonstrating the ability of a single sensor installed on one

  3. Gearbox Reliability Collaborative Bearing Calibration

    SciTech Connect

    van Dam, J.

    2011-10-01

    NREL has initiated the Gearbox Reliability Collaborative (GRC) to investigate the root cause of the low wind turbine gearbox reliability. The GRC follows a multi-pronged approach based on a collaborative of manufacturers, owners, researchers and consultants. The project combines analysis, field testing, dynamometer testing, condition monitoring, and the development and population of a gearbox failure database. At the core of the project are two 750kW gearboxes that have been redesigned and rebuilt so that they are representative of the multi-megawatt gearbox topology currently used in the industry. These gearboxes are heavily instrumented and are tested in the field and on the dynamometer. This report discusses the bearing calibrations of the gearboxes.

  4. Grizzly Bear Creek Flooding May 2015, SD

    USGS Multimedia Gallery

    Grizzly Bear Creek in Keystone, SD, on May 24, 2015. USGS streamgage 06403850 (Grizzly Bear Creek near Keystone, SD) showed the creek was more than one-half foot above flood stage on May 24. This streamgage is operated in cooperation with the METWARN (Rapid City/Pennington County Emer...

  5. Methods and systems for micro bearings

    DOEpatents

    Stalford, Harold L.

    2012-10-09

    A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

  6. Air-Bearing Table for Machine Shops

    NASA Technical Reports Server (NTRS)

    Ambrisco, D.

    1986-01-01

    Frequent workpiece repositioning made easier. Air-bearing table facilitates movement of heavy workpiece during machining or between repeated operations at different positions. Table assembly consists of workpiece supporting fixture riding on air bearing. Table especially useful for inertia welding, in which ease of mobility is important.

  7. Electrorheological fluid-controlled 'smart' journal bearings

    NASA Astrophysics Data System (ADS)

    Dimarogonas, Andrew D.; Kollias, Alexander

    1992-10-01

    The controllability of the stability properties of electrorheological (ER) fluid bearings is investigated using a specially developed solution of the lubricating equation for ER fluids. It was found that the properties of ER fluid bearings can be changed considerably by an applied electric field and that the stability region can be extended substantially.

  8. Pneumatic power is transmitted through air bearing

    NASA Technical Reports Server (NTRS)

    Johnson, H. I.; Wobig, O. A.

    1964-01-01

    A more efficient method for supplying high pressure air to an air bearing and pneumatic equipment mounted on it has been developed. The system uses a conventional air bearing and an air-supported sphere with a central passage. High pressure air is channeled through it into the pneumatic equipment on the sphere.

  9. Self-adjusting magnetic bearing systems

    DOEpatents

    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.

  10. The greening of polar bears in zoos

    Microsoft Academic Search

    Ralph A. Lewin

    1979-01-01

    POLAR BEARS (Thalarctos maritimus) normally have creamy-white fur, presumably an adaptation for camouflage in a snowy environment. However, during the summer of 1978, the fur on the back and sides of three adults in the San Diego Zoo turned green, though the animals remained otherwise healthy. (Of these bears, one female was born in the zoo in Calgary, Alberta, Canada,

  11. A flexible cruciform journal bearing mount

    NASA Technical Reports Server (NTRS)

    Frost, A. E.; Geiger, W. A.

    1973-01-01

    Flexible mount achieves low roll, pitch and yaw stiffnesses while maintaining high radial stiffness by holding bearing pad in fixed relationship to deep web cruciform member and holding this member in fixed relationship to bearing support. This mount has particular application in small, high performance gas turbines.

  12. Characteristics of shaft voltage and bearing currents

    Microsoft Academic Search

    D. Busse; J. Erdman; R. Kerkman; D. Schlegel; G. Skibinski

    1997-01-01

    This article reviews investigations into reduced bearing life due to voltage source adjustable speed drive (ASD) AC motor operation. Relevant bearing failure mechanisms and indicators are discussed. dv\\/dt and electric discharge machining (EDM) contributions are discussed and experimental data presented showing the voltage levels on motor shafts when operating with ASDs. Finally, techniques to reduce shaft voltage are discussed, along

  13. Measuring Bearing Wear Via Weight Loss

    NASA Technical Reports Server (NTRS)

    Keba, John E.; Moore, Richard S.

    1989-01-01

    Wear in critical parts of bearings measured via amounts of weight lost during use. Technique applicable in general to bearings made of nonporous materials. Weight-loss measurements easier, faster, more precise, and less likely to damage measured parts. Weight-loss measurements performed in clean rooms and under constraint of extreme cleanliness for compatability with liquid oxygen.

  14. The Bearing Strength of Fiber Metal Laminates

    Microsoft Academic Search

    R. G. J. Van Rooijen; J. Sinke; T. J. De Vries; S. Van Der Zwaag

    2006-01-01

    The bearing strength, in particular the edge distance sensitivity, of several fiber metal laminates of the GLARE family is experimentally evaluated. The behavior of the fiber layer is investigated in detail to obtain a better understanding of its failure mode. Parallel with these experiments, the bearing behavior is studied using a finite element (FE) model. The plasticity in the metal

  15. Corrosion of plain bearings in diesel engines

    Microsoft Academic Search

    B. M. Bunakov; G. P. Belyanchikov; A. L. Chudinovskikh; M. A. Grigorev

    1983-01-01

    The serviceability of plain bearings depends on many factors, in particular the engine operating temperatures and loads, the bearing design and conditions of assembly, the type of antifriction layer and break-in coating, the design features of the engine lubrication system, and the quality of the engine oil. Demonstrates that the corrosivity of modern oils for high-performance diesel engines depends on

  16. Precision instrumentation for rolling element bearing characterization

    SciTech Connect

    Marsh, Eric R.; Vigliano, Vincent C.; Weiss, Jeffrey R.; Moerlein, Alex W.; Vallance, R. Ryan [Machine Dynamics Research Laboratory, Pennsylvania State University, 331 Reber Building University Park, Pennsylvania 16802 (United States); Precision Systems Laboratory, George Washington University, 738 Phillips Hall 801 22nd Street, N.W. Washington, D.C., 20052 (United States)

    2007-03-15

    This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings.

  17. Magnetic perturbation inspection of inner bearing races

    NASA Technical Reports Server (NTRS)

    Barton, J. R.; Lankford, J.

    1972-01-01

    Approximately 100 inner race bearings were inspected nondestructively prior to endurance testing. Two of the bearings which failed during testing spalled at the sites of subsurface inclusions previously detected by using magnetic field perturbation. At other sites initially judged to be suspect, subsurface inclusion-nucleated cracking was observed. Inspection records and metallurgical sectioning results are presented and discussed.

  18. CHANGES IN MORTALITY OF YELLOWSTONE'S GRIZZLY BEARS

    Microsoft Academic Search

    DAVID J. MATTSON

    Records of grizzly bear (Ursus arctos) deaths are currently used by managers to indicate trends in actual grizzly bear mortality and to judge the effectiveness of management. Two assumptions underlie these current uses: first, that recorded mortality is an unbiased indicator of actual mortality, and second, that changes in mortality after implementation of management strategies are sufficient grounds to infer

  19. Diffusion of Water with Gummy Bears

    NSDL National Science Digital Library

    Mary Harris

    2003-01-01

    In this activity, learners investigate the movement of water into and out of a polymer. Learners test the diffusion of water through gummy bears, which are made of sugar and gelatin (a polymer). Learners compare what happens when gummy bears are submerged in tap water versus distilled water.

  20. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Navigable Waters 1 2010-07-01 2010-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable...REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draws of the Baltimore County...

  1. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Navigable Waters 1 2011-07-01 2011-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable...REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draws of the Baltimore County...

  2. Adaptive prognostics for rolling element bearing condition

    Microsoft Academic Search

    Y. Li; S. Billington; C. Zhang; T. Kurfess; S. Danyluk; S. Liang

    1999-01-01

    Rolling element bearing failure is one of the foremost causes of breakdown in rotating machinery. This paper proposes a remaining life adaptation methodology based on mechanistic modeling and parameter tuning. Vibration measurement is used to estimate defect severity by monitoring the signals generated from rotating bearings. Through a defect propagation model and defect diagnostic model, an adaptive algorithm is developed

  3. Distributed bearing estimation via matrix completion

    Microsoft Academic Search

    Andrew Waters; Volkan Cevher

    2010-01-01

    We consider bearing estimation of multiple narrow-band plane waves impinging on an array of sensors. For this problem, bearing estimation algorithms such as minimum variance distortionless response (MVDR), multiple signal classification, and maximum likelihood generally require the array covariance matrix as sufficient statistics. Interestingly, the rank of the array covariance matrix is approximately equal to the number of the sources,

  4. Long-wearing TFE/metal bearings

    NASA Technical Reports Server (NTRS)

    Brass, R. A.; Gillon, W. A., Jr.

    1980-01-01

    Method for making metal/polytetrafluoroethylene (TFE) bearing surfaces embeds long-wearing layer of TFE in microscopic pits in metal. Technique has potential applications in automotive gears, ball joints, and roller chain components. Other applications are in use of unlubricated bearings in chemical, pharmaceutical, and food-processing equipment.

  5. Inbreeding depression in brown bear Ursus arctos

    Microsoft Academic Search

    Linda Laikre; Robert Andrén; Hans-Ove Larsson; Nils Ryman

    1996-01-01

    This note reports the occurrence of inbreeding depression in a captive brown bear Ursus arctos population. We analyzed studbook records of brown bears bred in Nordic zoos and found a significant reduction in litter size following an increase of inbreeding. In addition, albinism is associated with inbreeding in this population. The amount of depression is compared to that found in

  6. Rotor and bearing system for a turbomachine

    DOEpatents

    Lubell, Daniel; Weissert, Dennis

    2006-09-26

    A rotor and bearing system for a turbomachine. The turbomachine includes a drive shaft, an impeller positioned on the drive shaft, and a turbine positioned on the drive shaft proximate to the impeller. The bearing system comprises one gas journal bearing supporting the drive shaft between the impeller and the turbine. The area between the impeller and the turbine is an area of increased heat along the drive shaft in comparison to other locations along the drive shaft. The section of the drive shaft positioned between impeller and the turbine is also a section of the drive shaft that experiences increased stressed and load in the turbomachine. The inventive bearing machine system positions only one radial bearing in this area of increased stress and load.

  7. Ball bearing tests to evaluate Duroid replacements

    NASA Astrophysics Data System (ADS)

    Anderson, M. J.

    2001-09-01

    ESTL has completed a programme to identify and qualify a self-lubricating material to replace RT/duroid 5813 ("Duroid"), for ball bearing cage applications in space mechanisms. Following literature reviews, material evaluations, friction and wear testing and a ball bearing screening test programme, PGM-HT (a PTFE/MoS2/glass fibre composite) was selected for evaluation in ball bearings. PGM-HT cages were tested extensively in conditions representative of that experienced by a selection of current mechanism applications. Different types (and sizes) of ball bearings and cages were tested over a range of operating speeds, loads (contact stresses) and under different environments. From these tests, it was concluded that the torque behaviour of PGM-HT lubricated bearings was identical to that of Duroid. A design guide was then prepared to summarise the findings and assist designers with torque and lifetime predictions.

  8. Status of understanding for bearing materials

    SciTech Connect

    Bamberger, E.N.

    1984-04-01

    The structural materials and potential failure modes for high technology aircraft gas turbine bearings are reviewed. Among the failure modes discussed for iron-base through-hardened bearing materials are fatigue, surface distress, and corrosion. It is shown that the sub-surface initiated rolling-contact fatigue failure mode is reasonably well understood and in most cases can be controlled by proper material selection and design. Current bearing materials provide long life and high reliability in existing applications. A new generation of materials are being developed which will provide improved fracture toughness, better corrosion resistance, and a further extension of bearing fatigue life. Bearing problems due to surface distress, caused by a variety of surface and near surface anomalies, are less well understood. This area will require the implementation of an interdisciplinary effort to improve the level of understanding of metallic surface-lubricant reactions and interactions.

  9. Flywheel energy storage with superconductor magnetic bearings

    SciTech Connect

    Weinberger, B.R.; Lynds, L. Jr.

    1993-06-01

    A system for storing energy in a flywheel suspended by magnetic levitation in a vacuum vessel is described comprising: a rotatable member having a rotation axis in a central shaft said shaft having first and second magnetic tips formed from permanent magnets on opposite ends thereof, superconductor magnetic bearings, positioned to support said first and second magnetic tips and supported in turn by bearing support means, said superconductor magnetic bearings having a main direction of lift; cooling means in thermal contact with said bearing support means; and energy transfer means, connected to said rotatable member, for transferring energy into and extracting energy from said rotatable member, characterized in that: at least one of said superconducting bearings includes a lifting portion comprising melt-processed, directionally solidified material structure having a crystal structure C-axis oriented parallel to said main direction of lift.

  10. Hydrodynamic air lubricated compliant surface bearing for an automotive gas turbine engine. 1: Journal bearing performance

    NASA Technical Reports Server (NTRS)

    Ruscitto, D.; Mccormick, J.; Gray, S.

    1978-01-01

    A 38.1 mm (1.5 inch) diameter Hydresil Compliant Surface Air Lubricated Journal Bearing was designed and tested to obtain bearing performance characteristics at both room temperature and 315 C (600 F). Testing was performed at various speeds up to 60,000 rpm with varying loads. Rotating sensors provided an opportunity to examine the film characteristics of the compliant surface bearing. In addition to providing minimum film thickness values and profiles, many other insights into bearing operation were gained such as the influence of bearing fabrication accuracy and the influence of smooth foil deflection between the bumps.

  11. Effect of hydrostatic pressure on water penetration and rotational dynamics in phospholipid-cholesterol bilayers.

    PubMed Central

    Bernsdorff, C; Wolf, A; Winter, R; Gratton, E

    1997-01-01

    The effect of high hydrostatic pressure on the lipid bilayer hydration, the mean order parameter, and rotational dynamics of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) cholesterol vesicles has been studied by time-resolved fluorescence spectroscopy up to 1500 bar. Whereas the degree of hydration in the lipid headgroup and interfacial region was assessed from fluorescence lifetime data using the probe 1-(4-trimethylammonium-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH), the corresponding information in the upper acyl chain region was estimated from its effect on the fluorescence lifetime of and 3-(diphenylhexatrienyl)propyl-trimethylammonium (TMAP-DPH). The lifetime data indicate a greater level of interfacial hydration for DPPC bilayers than for POPC bilayers, but there is no marked difference in interchain hydration of the two bilayer systems. The addition of cholesterol at levels from 30 to 50 mol% to DPPC has a greater effect on the increase of hydrophobicity in the interfacial region of the bilayer than the application of hydrostatic pressure of several hundred to 1000 bar. Although the same trend is observed in the corresponding system, POPC/30 mol% cholesterol, the observed effects are markedly less pronounced. Whereas the rotational correlation times of the fluorophores decrease in passing the pressure-induced liquid-crystalline to gel phase transition of DPPC, the wobbling diffusion coefficient remains essentially unchanged. The wobbling diffusion constant of the two fluorophores changes markedly upon incorporation of 30 mol% cholesterol, and increases at higher pressures, also in the case of POPC/30 mol% cholesterol. The observed effects are discussed in terms of changes in the rotational characteristics of the fluorophores and the phase-state of the lipid mixture. The results demonstrate the ability of cholesterol to adjust the structural and dynamic properties of membranes composed of different phospholipid components, and to efficiently regulate the motional freedom and hydrophobicity of membranes, so that they can withstand even drastic changes in environmental conditions, such as high external hydrostatic pressure. PMID:9138572

  12. 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.

  13. Simultaneous measurement of temperature, hydrostatic pressure and acoustic signal using a single distributed Bragg reflector fiber laser

    Microsoft Academic Search

    Yan-Nan Tan; Yang Zhang; Bai-Ou Guan

    2011-01-01

    A fiber-optic sensor based on a dual polarization fiber grating laser for simultaneous measurement of temperature, hydrostatic pressure and acoustic signal is proposed and experimentally demonstrated. The acoustic wave induces a frequency modulation (FM) of the carrier in radio frequency (RF) range generated by the fiber laser and can be easily extracted by using the FM demodulation technique. The temperature

  14. Lagrangean transport due to internal gravity waves simulated by a non-hydrostatic and compressible 2D numerical model

    Microsoft Academic Search

    K. Goya; M. Takamine; S. Miyahara

    2003-01-01

    Lagrangean transport due to internal gravity waves (IGWs), propagating throughout the middle atmosphere and generated by a localized tropospheric dry convection system, is reported using a non-hydrostatic, compressible and nonlinear two-dimensional numerical model. It is shown that (1) vertical displacement depth of isentropic surfaces in the upper middle atmosphere becomes of the order of several km because of the exponential

  15. Non-hydrostatic behavior of KBr as a pressure medium in diamond anvil cells up to 5.63 GPa.

    PubMed

    Zhao, Jing; Ross, Nancy L

    2015-05-13

    Non-hydrostatic stresses of KBr acting as a pressure-transmitting medium have been investigated by examining their effect on a single crystal of quartz in a diamond anvil cell (DAC). The lattice strains or distortions were measured by single-crystal x-ray diffraction methods, and the non-hydrostatic deviatoric stresses for KBr were determined up to 5.63(2) GPa. The experimental results show that differences between axial stress components in the direction normal to the DAC culet face and the radial stress components in directions parallel to the DAC culet face are about 0.063(24) GPa at pressures below 2.14 GPa, and the pressure-transmitting medium can therefore be considered as quasi-hydrostatic up to this pressure. However above 2.14 GPa, after the phase transition pressure of KBr during which it converts from the B1 phase to the B2 phase, the deviatoric stresses constantly increase with increasing pressure. At the maximum pressure of this study, 5.63(2) GPa, the difference between axial stress and radial stress components reaches 0.93(9) GPa. Different variations in the non-hydrostatic deviatoric stresses were observed during both compression and decompression of the DAC, and are mainly ascribed to the phase-transition-induced volume change of KBr. PMID:25880344

  16. Respiratory Response of the Deep-Sea Amphipod Stephonyx biscayensis Indicates Bathymetric Range Limitation by Temperature and Hydrostatic Pressure

    Microsoft Academic Search

    Alastair Brown; Sven Thatje

    2011-01-01

    Depth zonation of fauna on continental margins is well documented. Whilst increasing hydrostatic pressure with depth has long been considered a factor contributing significantly to this pattern, discussion of the relative significance of decreasing temperature with depth has continued. This study investigates the physiological tolerances of fed and starved specimens of the bathyal lysianassoid amphipod Stephonyx biscayensis at varying temperature

  17. Investigation of thermal processes in the hot hydrostatic pressing of parts from nickel heat-resisting alloy powders. Part I

    Microsoft Academic Search

    E. I. Starovoitenko; G. S. Garibov; V. I. Kostyukov; E. P. Kratt; I. V. Molchanov

    1980-01-01

    In the work described below an experimental investigation was carried out of the heating of pressure units before hydrostatic pressing and, on the basis of the results obtained, a suitable heating technique and a practical methodofcalculat ing the duration of heating were developed. From an earlier study of the thermophysicalproperties ofanickelheat-re sistingalloypowd erinafiller [4] itwas known that the effective values

  18. Weighing galaxy clusters with gas. II. On the origin of hydrostatic mass bias in ?CDM galaxy clusters

    SciTech Connect

    Nelson, Kaylea; Nagai, Daisuke; Yu, Liang [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Lau, Erwin T.; Rudd, Douglas H., E-mail: kaylea.nelson@yale.edu [Department of Physics, Yale University, New Haven, CT 06520 (United States)

    2014-02-20

    The use of galaxy clusters as cosmological probes hinges on our ability to measure their masses accurately and with high precision. Hydrostatic mass is one of the most common methods for estimating the masses of individual galaxy clusters, which suffer from biases due to departures from hydrostatic equilibrium. Using a large, mass-limited sample of massive galaxy clusters from a high-resolution hydrodynamical cosmological simulation, in this work we show that in addition to turbulent and bulk gas velocities, acceleration of gas introduces biases in the hydrostatic mass estimate of galaxy clusters. In unrelaxed clusters, the acceleration bias is comparable to the bias due to non-thermal pressure associated with merger-induced turbulent and bulk gas motions. In relaxed clusters, the mean mass bias due to acceleration is small (? 3%), but the scatter in the mass bias can be reduced by accounting for gas acceleration. Additionally, this acceleration bias is greater in the outskirts of higher redshift clusters where mergers are more frequent and clusters are accreting more rapidly. Since gas acceleration cannot be observed directly, it introduces an irreducible bias for hydrostatic mass estimates. This acceleration bias places limits on how well we can recover cluster masses from future X-ray and microwave observations. We discuss implications for cluster mass estimates based on X-ray, Sunyaev-Zel'dovich effect, and gravitational lensing observations and their impact on cluster cosmology.

  19. High Hydrostatic Pressure Modification of Whey Protein Concentrate for Improved Body and Texture of Lowfat Ice Cream

    Microsoft Academic Search

    S.-Y. Lim; B. G. Swanson; C. F. Ross; S. Clark

    2008-01-01

    Previous research demonstrated that application of high hydrostatic pressure (HHP), particularly at 300 MPa for 15 min, can enhance foaming properties of whey protein concentrate (WPC). The purpose of this research was to determine the practical impact of HHP- treated WPC on the body and texture of lowfat ice cream. Washington State University (WSU)-WPC was produced by ultrafiltration of fresh

  20. Genes that are involved in high hydrostatic pressure treatments in a Listeria monocytogenes Scott A ctsR deletion mutant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a food-borne pathogen of significant threat to public health. High Hydrostatic Pressure (HHP) treatment can be used to control L. monocytogenes in food. The CtsR (class three stress gene repressor) protein negatively regulates the expression of class III heat shock genes....

  1. Characterization of the effects of hydrostatic extrusion on grain size, surface composition and the corrosion resistance of austenitic stainless steels

    Microsoft Academic Search

    Marcin Pisarek; Piotr K?dzierzawski; Tomasz P?oci?ski; Maria Janik-Czachor; Krzysztof J. Kurzyd?owski

    2008-01-01

    Passivity breakdown on austenitic Types 303 and 316 stainless steels in the as-received state, and after heavy plastic deformation by hydrostatic extrusion (HE), was investigated in an aggressive environment containing Cl? ions. Microscopic, surface analytical and electrochemical methods were used to characterize changes in structure and chemistry of the surface of austenitic stainless steels introduced by HE. TEM and stereological

  2. Effect of Cytoskeletal Disruption on Mechanotransduction of Hydrostatic Pressure by C3H10T1/2 Murine Fibroblasts

    PubMed Central

    Shim, Joon W; Wise, Dwayne A; Elder, Steven H

    2008-01-01

    Cyclic hydrostatic pressure of physiological magnitude (< 10 MPa) stimulates chondrogenic differentiation of mesenchymal stem cells, but mechanotransduction mechanisms are not well understood. It was hypothesized that an intact cytoskeleton would be required for uninhibited mechanotransduction of hydrostatic pressure. Therefore we examined the effects of drugs which selectively interfere with actin and tubulin polymerization on pressure-induced upregulation of aggrecan and col2a1 (type II collagen) mRNA expression. C3H10T1/2 cells were cultured as pellets in either 4µM cytochalasin D or 4µM nocodazole and subjected to 3 days of cyclic hydrostatic compression (1 Hz, 5 MPa, 2 h per day). Phalloidin staining and indirect immunostaining with anti ?-tubulin antibody confirmed disruption of microfilament and microtubule assemblies, respectively. Real time RT-PCR revealed that both drugs substantially lowered the basal level of aggrecan and col2a1 mRNA, but that neither drug prevented a pressure-stimulated increase in gene expression relative to the altered basal state. Thus upregulation of macromolecular gene expression by cyclic hydrostatic pressure did not require a completely intact cytoskeleton. PMID:19478938

  3. High hydrostatic pressure effects on mold flora, citrinin mycotoxin, hydroxytyrosol, oleuropein phenolics and antioxidant activity of black table olives

    Microsoft Academic Search

    Özlem Toku?o?lu; Hami Alpas; Faruk Bozo?lu

    2010-01-01

    High hydrostatic pressure (HHP) as a non-thermal technology is an effective tool for microbiologically safe and shelf-stable fruits. Mycotoxin citrinin (CIT) is a toxic secondary metabolite, especially produced from filamentous fungus Penicillium citrinum and is also produced by other species of Penicillium, Aspergillus, and Monascus that are able to develop on olive after harvest, during brine and storage of olives.

  4. Effects of hydrostatic pressure on the nonlinear optical properties of a donor impurity in a GaAs quantum ring

    NASA Astrophysics Data System (ADS)

    Restrepo, R. L.; Barseghyan, M. G.; Mora-Ramos, M. E.; Duque, C. A.

    2013-06-01

    The effects of hydrostatic pressure, size quantization and impurity position on the binding energies of a hydrogenic-like donor impurity in a two-dimensional GaAs quantum ring and together with the linear and nonlinear intraband optical absorption and the relative refractive index changes are studied using the variational method and effective-mass approximation. The binding energies of 1s and 2s states are examined as functions of the structure (inner and outer radii), impurity position and hydrostatic pressure. We have also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients and relative index changes as a function of incident photon energy for different geometric configurations, hydrostatic pressure and impurity position. It is found that the variation of distinct sizes of the structure and impurity position leads to either a redshift and/or a blueshift of the resonant peaks of the intraband optical absorption and relative refractive index change spectrum. In addition we have found that the application of a hydrostatic pressure leads to a blueshift.

  5. Evaluation of the Growth Environment of a Hydrostatic Force Bioreactor for Preconditioning of Tissue-Engineered Constructs

    PubMed Central

    Reinwald, Yvonne; Leonard, Katherine H.L.; Henstock, James R.; Whiteley, Jonathan P.; Osborne, James M.; Waters, Sarah L.; Levesque, Philippe

    2015-01-01

    Bioreactors have been widely acknowledged as valuable tools to provide a growth environment for engineering tissues and to investigate the effect of physical forces on cells and cell-scaffold constructs. However, evaluation of the bioreactor environment during culture is critical to defining outcomes. In this study, the performance of a hydrostatic force bioreactor was examined by experimental measurements of changes in dissolved oxygen (O2), carbon dioxide (CO2), and pH after mechanical stimulation and the determination of physical forces (pressure and stress) in the bioreactor through mathematical modeling and numerical simulation. To determine the effect of hydrostatic pressure on bone formation, chick femur skeletal cell-seeded hydrogels were subjected to cyclic hydrostatic pressure at 0–270?kPa and 1?Hz for 1?h daily (5 days per week) over a period of 14 days. At the start of mechanical stimulation, dissolved O2 and CO2 in the medium increased and the pH of the medium decreased, but remained within human physiological ranges. Changes in physiological parameters (O2, CO2, and pH) were reversible when medium samples were placed in a standard cell culture incubator. In addition, computational modeling showed that the distribution and magnitude of physical forces depends on the shape and position of the cell-hydrogel constructs in the tissue culture format. Finally, hydrostatic pressure was seen to enhance mineralization of chick femur skeletal cell-seeded hydrogels. PMID:24967717

  6. 19 CFR 133.21 - Articles bearing counterfeit trademarks.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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  7. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

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  8. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Tailshaft clearance; bearing weardown. 61.20-23 Section 61.20-23...Equipment § 61.20-23 Tailshaft clearance; bearing weardown. (a) Water lubricated bearings, other than rubber, must be rebushed as...

  9. 12 CFR 330.16 - Noninterest-bearing transaction accounts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 false Noninterest-bearing transaction accounts. 330.16 Section...COVERAGE § 330.16 Noninterest-bearing transaction accounts. (a) Separate...depositor's funds in a “noninterest-bearing transaction account” (as...

  10. 14 CFR 71.7 - Bearings, radials, and mileages.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2011-01-01 2011-01-01 false Bearings, radials, and mileages. 71.7 Section...ROUTES; AND REPORTING POINTS § 71.7 Bearings, radials, and mileages. All bearings and radials in this part are true and are...

  11. 14 CFR 71.7 - Bearings, radials, and mileages.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 2010-01-01 2010-01-01 false Bearings, radials, and mileages. 71.7 Section...ROUTES; AND REPORTING POINTS § 71.7 Bearings, radials, and mileages. All bearings and radials in this part are true and are...

  12. 14 CFR 71.7 - Bearings, radials, and mileages.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Bearings, radials, and mileages. 71.7 Section...ROUTES; AND REPORTING POINTS § 71.7 Bearings, radials, and mileages. All bearings and radials in this part are true and are...

  13. 12 CFR 330.16 - Noninterest-bearing transaction accounts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 false Noninterest-bearing transaction accounts. 330.16 Section...COVERAGE § 330.16 Noninterest-bearing transaction accounts. (a) Separate...depositor's funds in a “noninterest-bearing transaction account” (as...

  14. 12 CFR 745.14 - Noninterest-bearing transaction accounts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

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  15. 12 CFR 330.16 - Noninterest-bearing transaction accounts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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  16. 12 CFR 330.16 - Noninterest-bearing transaction accounts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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  17. 12 CFR 745.14 - Noninterest-bearing transaction accounts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

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  18. 12 CFR 745.14 - Noninterest-bearing transaction accounts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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  19. 14 CFR 71.7 - Bearings, radials, and mileages.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Bearings, radials, and mileages. 71.7 Section...ROUTES; AND REPORTING POINTS § 71.7 Bearings, radials, and mileages. All bearings and radials in this part are true and are...

  20. 19 CFR 133.21 - Articles bearing counterfeit trademarks.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Articles bearing counterfeit trademarks. 133.21 ...NAMES, AND COPYRIGHTS Importations Bearing Registered and/or Recorded Trademarks...Recorded Trade Names § 133.21 Articles bearing counterfeit trademarks. (a)...