Science.gov

Sample records for mixed lubrication analysis

  1. Analysis of mixed lubrication mechanism in metal-on-metal hip joint replacements.

    PubMed

    Jin, Z M

    2002-01-01

    A simple mixed lubrication model has been developed to predict the asperity contact and wear for the metal-on-metal bearing couple for total hip joint replacements. It has been shown that the femoral head radius has a large effect on the predicted asperity contact and wear depending on the lubrication regime. An increase in the femoral head radius can lead to an increase in wear under a predominantly boundary lubrication regime, but this trend can be reversed under a mixed lubrication regime towards fluid film lubrication. These observations are consistent with the recent experimental findings from hip simulator studies by Smith and co-workers.

  2. Tribological Behavior of Aqueous Copolymer Lubricant in Mixed Lubrication Regime.

    PubMed

    Ta, Thi D; Tieu, A Kiet; Zhu, Hongtao; Zhu, Qiang; Kosasih, Prabouno B; Zhang, Jie; Deng, Guanyu

    2016-03-01

    Although a number of experiments have been attempted to investigate the lubrication of aqueous copolymer lubricant, which is applied widely in metalworking operations, a comprehensive theoretical investigation at atomistic level is still lacking. This study addresses the influence of loading pressure and copolymer concentration on the structural properties and tribological performance of aqueous copolymer solution of poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO) at mixed lubrication using a molecular dynamic (MD) simulation. An effective interfacial potential, which has been derived from density functional theory (DFT) calculations, was employed for the interactions between the fluid's molecules and iron surface. The simulation results have indicated that the triblock copolymer is physisorption on iron surface. Under confinement by iron surfaces, the copolymer molecules form lamellar structure in aqueous solution and behave differently from its bulk state. The lubrication performance of aqueous copolymer lubricant increases with concentration, but the friction reduction is insignificant at high loading pressure. Additionally, the plastic deformation of asperity is dependent on both copolymer concentration and loading pressure, and the wear behavior shows a linear dependence of friction force on the number of transferred atoms between contacting asperities. PMID:26828119

  3. Experimental Analysis of Damping and Tribological Characteristics of Nano-CuO Particle Mixed Lubricant in Ball Bearings

    NASA Astrophysics Data System (ADS)

    Prakash, E.; Sivakumar, K.

    2015-12-01

    Experimental analysis of damping capacity and tribological characteristics of nano CuO added Servosystem 68 lubricant is attempted. CuO nano particles were synthesized by aqueous precipitation method and characterized. Prior to dispersion into lubricant, CuO nano particles were coated with 0.2 wt.% surfactant (Span-80) to stabilize the nano fluid. Tribological characteristics of particle added lubricant were tested in ASTM D 4172 four ball wear tester. Scanning electron microscopy test results of worn surfaces of nano CuO particle added lubricant were smoother than base lubricant. The particle added lubricant was applied in a new ball bearing and three defected ball bearings. When particle added lubricant was used, the ball defected bearing's vibration amplitude was reduced by 21.94% whereas it was 16.46% for new bearing and was ≤ 11% for other defected bearings. The formation of protection film of CuO over ball surface and regime of full film lubrication near the ball zone were observed to be reason for improved damping of vibrations.

  4. The effect of refrigerants in the mixed lubrication regime

    SciTech Connect

    Mizuhara, Kazuyuki; Tomimoto, Makoto

    1997-12-31

    Because of environmental concerns, CFC (chlorofluorocarbon) refrigerants must be replaced with HFCs (hydrofluorocarbons). As a result, many tribological problems are caused especially in rotary piston compressors. To solve the problem, the effects of refrigerants on friction and wear characteristics of the oil and refrigerant mixtures at the mixed lubrication regime are investigated. The difference in refrigerants are clearly observed not only in boundary but also in the mixed lubrication regime. The effects of operating conditions on sliding conditions and experimental results are also discussed. It is concluded that for practical application where long life is essential, experiments must be conducted under the mixed lubrication regime. Also, the importance of defining the lubrication regime in terms of film parameter is emphasized.

  5. Spectroscopic Analysis of Perfluoropolyether Lubricant Degradation During Boundary Lubrication

    NASA Technical Reports Server (NTRS)

    Herrera-Fierro, Pilar; Shogrin, Bradley A.; Jones, William R., Jr.

    1996-01-01

    The degradation of a branched perfluoropolyether (PFPE) under boundary lubrication conditions was studied using mu-FTIR and mu-Raman spectroscopies. Stainless steel (440C) discs coated with thin (600A), uniform films of the PFPE were tested in a ball-on-disc apparatus until various levels of friction coefficient were attained. Discs were then examined using the above techniques. When the friction coefficient surpassed the value obtained with an un-lubricated control, the lubricant film had either been physically displaced or partially transformed in to a 'friction polymer'. Infrared analysis of this 'friction polymer' indicated the presence of a polymeric fluorinated acid species (R(sub f)COOH). Raman spectroscopy indicated the presence of amorphous carbon in the wear track and in the friction polymer. Some reaction mechanisms are suggested to explain the results.

  6. Mixed film lubrication with biobased oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most tribological processes (e.g. metalworking), occur in the mixed film regime where the boundary and hydrodynamic properties of the oils play critical roles. In the work described here, the boundary and hydrodynamic properties of various biobased oils were evaluated. The oils were then investiga...

  7. Mixed lubrication after rewetting of blotted pleural mesothelium.

    PubMed

    Bodega, Francesca; Sironi, Chiara; Porta, Cristina; Pecchiari, Matteo; Zocchi, Luciano; Agostoni, Emilio

    2013-01-15

    Coefficient of kinetic friction (μ) of pleural mesothelium blotted with filter paper, and rewetted with Ringer solution markedly increases; this increase is removed if a sufficient amount of sialomucin or hyaluronan is added to Ringer (Bodega et al., 2012. Respiratory Physiology and Neurobiology 180, 34-39). In this research we found that μ of pleural mesothelium blotted, rewetted, and sliding at physiological velocities and loads, decreased with increase of velocity, mainly at low velocities. Despite this decrease, μ at highest velocity was still double that before blotting. With small concentration of sialomucin or hyaluronan μ was markedly smaller at each velocity, decreased less with increase of velocity, and at highest velocity approached preblotting value. These findings indicate a regime of mixed lubrication in post-blotting Ringer, at variance with boundary lubrication occurring before blotting or postblotting with sufficient macromolecule addition. Greater roughness of mesothelial surface, caused by blotting, likely induces zones of elastohydrodynamic lubrication, which increase with velocity, while contact area decreases.

  8. The Chevron Foil Thrust Bearing: Improved Performance Through Passive Thermal Management and Effective Lubricant Mixing

    NASA Technical Reports Server (NTRS)

    Bruckner, Robert

    2013-01-01

    An improved foil thrust bearing is described that eliminates or reduces the need for forced cooling of the bearing foils while at the same time improves the load capacity of the bearing, enhances damping, provides overload tolerance, and eliminates the high speed load capacity drop-off that plagues the current state of the art. The performance improvement demonstrated by the chevron foil thrust bearing stems from a novel trailing edge shape that splays the hot lubricant in the thin film radially, thus preventing hot lubricant carry-over into the ensuing bearing sector. Additionally, the chevron shaped trailing edge induces vortical mixing of the hot lubricant with the gas that is naturally resident within the inter-pad region of a foil thrust bearing. The elimination of hot gas carry-over in combination with the enhanced mixing has enabled a completely passive thermally managed foil bearing design. Laboratory testing at NASA has confirmed the original analysis and reduced this concept to practice.

  9. Thermohydrodynamic analysis for laminar lubricating films

    NASA Technical Reports Server (NTRS)

    Elrod, H. G.; Brewe, D. E.

    1986-01-01

    A Galerkin-type analysis to include thermal effects in laminar lubricating films was performed. The lubricant properties were assumed constant except for a temperature-dependent Newtonian viscosity. The cross-film temperature profile is established by collocation at the film boundaries and two interior Lobatto points. The interior temperatures are determined by requiring that the zeroth and first moment of the energy equation be satisfied across the film. The fluidity is forced to conform to a third--degree polynomial appropriate to the Lobatto-point temperatures. Preliminary indications are that the use of just two such sampling points enables satisfactory prediction of bearing performance even in the presence of substantial viscosity variation.

  10. Two methodologies for optical analysis of contaminated engine lubricants

    NASA Astrophysics Data System (ADS)

    Aghayan, Hamid; Bordatchev, Evgueni; Yang, Jun

    2012-01-01

    The performance, efficiency and lifetime of modern combustion engines significantly depend on the quality of the engine lubricants. However, contaminants, such as gasoline, moisture, coolant and wear particles, reduce the life of engine mechanical components and lubricant quality. Therefore, direct and indirect measurements of engine lubricant properties, such as physical-mechanical, electro-magnetic, chemical and optical properties, are intensively utilized in engine condition monitoring systems and sensors developed within the last decade. Such sensors for the measurement of engine lubricant properties can be used to detect a functional limit of the in-use lubricant, increase drain interval and reduce the environmental impact. This paper proposes two new methodologies for the quantitative and qualitative analysis of the presence of contaminants in the engine lubricants. The methodologies are based on optical analysis of the distortion effect when an object image is obtained through a thin random optical medium (e.g. engine lubricant). The novelty of the proposed methodologies is in the introduction of an object with a known periodic shape behind a thin film of the contaminated lubricant. In this case, an acquired image represents a combined lubricant-object optical appearance, where an a priori known periodic structure of the object is distorted by a contaminated lubricant. In the object shape-based optical analysis, several parameters of an acquired optical image, such as the gray scale intensity of lubricant and object, shape width at object and lubricant levels, object relative intensity and width non-uniformity coefficient are newly proposed. Variations in the contaminant concentration and use of different contaminants lead to the changes of these parameters measured on-line. In the statistical optical analysis methodology, statistical auto- and cross-characteristics (e.g. auto- and cross-correlation functions, auto- and cross-spectrums, transfer function

  11. Waste lubricating oil removal in a batch reactor by mixed bacterial consortium: a kinetic study.

    PubMed

    Bhattacharya, Munna; Guchhait, Sugata; Biswas, Dipa; Datta, Sriparna

    2015-11-01

    The growth kinetics and biodegradation of two waste lubricating oil samples including waste engine oil (WEO) and waste transformer oil (WTO) were studied using pure isolates and mixed culture of Ochrobactrum sp. C1 and Bacillus sp. K1. The mixed culture significantly influenced degradation efficiency of the pure isolates through bioaugmentation process. In particular, the mixed culture was capable of growing on various n-alkanes and polycyclic aromatic hydrocarbons and was able to tolerate unusually high concentrations of waste lubricants (WEO-86.0 g/L and WTO-81.5 g/L). The initial concentration of waste lubricating oils has been varied in the range of 1-10 % (v/v). Under this experimental range, the bacterial growth has been observed to follow Haldane-type kinetics characterizing the presence of substrate inhibition. Haldane model was used to fit the exponential growth data and the following kinetic parameters were obtained: μ max = 0.078 h(-1), K S = 23.101 g/L, K i = 43.844 g/L for WEO; and μ max = 0.044 h(-1), K S = 10.662 g/L, K i = 58.310 g/L for WTO. The values of intrinsic kinetic parameters, like specific growth rate μ max, half saturation constant, K S, inhibition constant, K i and the maximum substrate concentration, S max and growth yield coefficient Y x/s , have been determined using each model hydrocarbon and their mixture as limiting substrate. Relative changes in the values of the kinetic parameters have been correlated to the number of carbon atoms present in n-alkanes. The metabolites from degradation of model hydrocarbon compounds have been identified by GC-MS to elucidate the possible pathway of waste lubricating oil degradation process.

  12. Tribological performance analysis of textured steel surfaces under lubricating conditions

    NASA Astrophysics Data System (ADS)

    Singh, R. C.; Pandey, R. K.; Rooplal; Ranganath, M. S.; Maji, S.

    2016-09-01

    The tribological analysis of the lubricated conformal contacts formed between the smooth/textured surfaces of steel discs and smooth surface of steel pins under sliding conditions have been considered. Roles of dimples’ pitch of textured surfaces have been investigated experimentally to understand the variations of coefficient of friction and wear at the tribo-contacts under fully flooded lubricated conditions. Substantial reductions in coefficient of friction and wear at the tribo-interfaces have been observed in presence of textures on the rotating discs for both fully flooded and starved conditions in comparison to the corresponding lubricating conditions of the interfaces formed between the smooth surfaces of disc and pin. In presence of surface texture, the coefficient of friction reduces considerable at elevated sliding speeds (>2 m/s) and unit loads (>0.5 MPa) for the set of operating parameters considered in the analysis.

  13. Industrial Lubricants

    NASA Astrophysics Data System (ADS)

    Kajdas, C.; Karpińska, A.; Kulczycki, A.

    'Industrial lubricant' gaseous, liquid and solid products cover many applications. A new systems analysis approach is used combining heterogeneous catalysis and tribochemistry. Bearing lubricant applications are discussed in terms of the bearing film thickness and tribological regimes, for liquid and solid lubricants. Compressor and vacuum pump lubricant applications are described. The various classes of hydraulic fluids for industrial applications are explained. The properties, applications and selection of various industrial lubricants for different gears are described. Steam and industrial gas turbine lubricant formulations are discussed and the effects of their degradation products, particularly for valves and filters, are presented. Metalworking lubricant applications are divided into cutting and forming operations and their actions are described. Speciality applications such as process, textile, food-grade, slideway, cylinder and wire rope lubricants are explained.

  14. Lubrication background

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    Surface topography, including the various physical methods of measuring surfaces, and the various lubrication regimes (hydrodynamic, elastohydrodynamic, boundary, and mixed) are discussed. The historical development of elastohydrodynamic lubrication is outlined. The major accomplishments in four periods, the pre-1950's, the 1950's, the 1960's, and the 1970's are presented.

  15. Gear Lubrication and Cooling Experiment and Analysis

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Akin, L. S.

    1983-01-01

    A gear tooth temperature analysis was performed using a finite element method combined with a calculated heat input, a calculated oil jet impingement depth, and estimated heat transfer coefficients for the different parts of the gear tooth that are oil cooled and air cooled. Experimental measurements of gear tooth average surface temperature and gear tooth instantaneous surface temperature were made with a fast response, infrared, radiometric microscope. Increasing oil pressure has a significant effect on both average surface temperature and peak surface temperature at loads above 1895 N/cm(1083 lb/in) and speeds of 10,000 and 7500 rpm. Both increasing speed (from 5000 to 10,000 rpm) at constant speed cause a significant rise in the average surface temperature and in the instantaneous peak surface temperatures on the gear teeth. The oil jet pressure required to provide the best cooling for gears is the pressure required to obtain full gear tooth impingement. Calculated results for gear tooth temperatures were close to experimental results for various oil jet impingement depths for identical operating conditions.

  16. Analysis of elastohydrodynamic lubrication in McKee-Farrar metal-on-metal hip joint replacement.

    PubMed

    Yew, A; Udofia, I; Jagatia, M; Jin, Z M

    2004-01-01

    An elastohydrodynamic lubrication (EHL) analysis was carried out in this study for a typical McKee-Farrar metal-on-metal hip prosthesis under a simple steady state rotation. The finite element method was used initially to investigate the effect of the cement and bone on the predicted contact pressure distribution between the two articulating surfaces under dry conditions, and subsequently to determine the elastic deformation of both the femoral and the acetabular components required for the lubrication analysis. Both Reynolds equation and the elasticity equation were coupled and solved numerically using the finite difference method. Important features in reducing contact stresses and promoting fluid-film lubrication associated with the McKee-Farrar metal-on-metal hip implant were identified as the large femoral head and the thin acetabular cup. For the typical McKee-Farrar metal-on-metal hip prosthesis considered under typical walking conditions, an increase in the femoral head radius from 14 to 17.4 mm (for a fixed radial clearance of 79 microm) was shown to result in a 25 per cent decrease in the maximum dry contact pressure and a 60 per cent increase in the predicted minimum film thickness. Furthermore, the predicted maximum contact pressure considering both the cement and the bone was found to be decreased by about 80 per cent, while the minimum film thickness was predicted to be increased by 50 per cent. Despite a significant increase in the predicted minimum lubricating film thickness due to the large femoral head and the thin acetabular cup, a mixed lubrication regime was predicted for the McKee-Farrar metal-on-metal hip implant under estimated in vivo steady state walking conditions, depending on the surface roughness of the bearing surfaces. This clearly demonstrated the important influences of the material, design and manufacturing parameters on the tribological performance of these hard-on-hard hip prostheses. Furthermore, in the present contact

  17. Hypernated supercritical fluid chromatography: potential application for car lubricant analysis.

    PubMed

    Lavison-Bompard, Gwenaelle; Bertoncini, Fabrice; Thiébaut, Didier; Beziau, Jean-François; Carrazé, Bernadette; Valette, Pascale; Duteurtre, Xavier

    2012-12-28

    Car lubricant additives are added to mineral or synthetic base stocks to improve viscosity and resistance to oxidation of the lubricant and to limit wear of engines. In previous papers related to this purpose, it was demonstrated that SFC allows the elution of common low molecular weight additives. Since their total resolution could not be achieved owing to the limited peak capacity of packed columns, the hyphenation of selective and informative detectors, atomic emission and mass spectrometry, were also carried out for identification. This paper describes the final implementation of a packed column SFC/FID-UV-AED-FTIR-MS system to contribute to the characterisation of both the base stock, mineral or semi-synthetic, and the low molecular weight additives. SFC/FID-UV-FTIR ensures the easy confirmation of the presence of esters in the base stock. Reference additives are used to demonstrate the performances of the multi hyphenated system prior to its implementation for their identification in packages and in formulated lubricants. Identification and partial structure elucidation of additives and families of additives in package and formulated car lubricants are presented: using combined information obtained from AED traces and FTIR chemigrams, chemical families of additives can be deduced. Then, the mass spectra can be interpreted in the elution zone of interest in order to go further in the determination of the additive molecular structure. The hypernated SFC system was also employed to follow the ageing of car lubricants.

  18. Ellipsometric surface analysis of wear tracks produced by different lubricants

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.; Marxer, N.; Jones, W. R., Jr.

    1985-01-01

    A scanning ellipsometer with high spatial resolution was used to analyze wear tracks generated on M-50 surfaces operated in several lubricant formulations. These formulations included a pure ester base stock of trimethyol propane triheptanoate with additives of either benzotriazole (BTZ), dioctyldiphenylamine (DODPA), or tricresylphosphate (TCP). Results indicated that BTZ and TCP produced patchy oxide surface films consisting mainly of Fe304. DOPDA produced a much more uniform oxide film. These findings may explain the tendency of lubricant formulations containing TCP to scuff more readily than those containing only antioxidants.

  19. Ellipsometric surface analysis of wear tracks produced by different lubricants

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.; Marxer, N.; Jones, W. R., Jr.

    1985-01-01

    Ellipsometric analyses of wear tracks in berings of M-50 steel were carried out after operation under severe conditions with different lubricant additives. The base lubricant was a synthetic ester. It was found that the surface and wear additives benzotirazole and tricresylyphosphate produced very patchy oxide layers. Dioctyldiphenylamine, a common antioxidant, on the other hand produced smoother films. The analyses were performed with a specially designed and constructed ellipsometer of very high (20 micron) spatial resolution. The results are consistent with data obtained by Auger electron spectroscopy.

  20. Analysis of a thioether lubricant by infrared Fourier microemission spectrophotometry

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Morales, W.; Lauer, J. L.

    1986-01-01

    An infrared Fourier microemission spectrophotometer is used to obtain spectra (wavenumber range, 630 to 1230 0.1 cm) from microgram quantities of thioether lubricant samples deposited on aluminum foil. Infrared bands in the spectra are reproducible and could be identified as originating from aromatic species (1,3-disubstituted benzenes). Spectra from all samples (neat and formulated, used and unused) are very similar. Additives (an acid and a phosphinate) present in low concentration (0.10 percent) in the formulated fluid are not detected. This instrument appears to be a viable tool in helping to identify lubricant components separated by liquid chromatography.

  1. Simulation of automotive wrist pin joint and tribological studies of tin coated Al-Si alloy, metal matrix composites and nitrogen ceramics under mixed lubrication

    NASA Astrophysics Data System (ADS)

    Wang, Qian

    Development of automotive engines with high power output demands the application of high strength materials with good tribological properties. Metal matrix composites (MMC's) and some nitrogen ceramics are of interest to replace some conventional materials in the piston/pin/connecting rod design. A simulation study has been developed to explore the possibility to employ MMC's as bearing materials and ceramics as journal materials, and to investigate the related wear mechanisms and the possible journal bearing failure mechanisms. Conventional tin coated Al-Si alloy (Al-Si/Sn) have been studied for the base line information. A mixed lubrication model for journal bearing with a soft coating has been developed and applied to the contact and temperature analysis of the Al-Si/Sn bearing. Experimental studies were performed to reveal the bearing friction and wear behavior. Tin coating exhibited great a advantage in friction reduction, however, it suffered significant wear through pitting and debonding. When the tin wore out, the Al-Si/steel contact experienced higher friction. A cast and P/M MMC's in the lubricated contact with case hardened steel and ceramic journals were studied experimentally. Without sufficient material removal in the conformal contact situation, MMC bearings in the MMC/steel pairs gained weight due to iron transfer and surface tribochemical reactions with the lubricant additives and contact failure occurred. However, the MMC/ceramic contacts demonstrated promising tribological behavior with low friction and high wear resistance, and should be considered for new journal bearing design. Ceramics are wear resistant. Ceramic surface roughness is very crucial when the journals are in contact with the tin coated bearings. In contact with MMC bearings, ceramic surface quality and fracture toughness seem to play some important roles in affecting the friction coefficient. The wear of silicon nitride and beta sialon (A) journals is pitting due to grain

  2. Mixed waste analysis

    SciTech Connect

    Reynolds, J.J.; Turner, C.A.

    1993-12-31

    Improved superpower relations followed by the Soviet Union`s collapse acted as catalysts for changing the mission at Rocky Flats. Now, environmental concerns command as much attention as production capability. As a result, laboratory instruments once dedicated to plutonium production have a new purpose - the analysis of mixed wastes. Waste drums destined for WIPP require headspace analysis by GS/MS (gas chromatography/mass spectrometry) for volatile and semi-volatile organic compounds (VOC and SVOC). Flame AA analysis provides information on inorganic constituents. EPA guidelines for waste analysis (SW-846) overlook the obstacles of glove box manipulations. Sometimes, SW-846 guidelines conflict with the Rocky Flats waste minimization effort. However, the EPA encourages SW-846 adaptations if experimental data confirms the results. For water and soil samples, AA analysis of laboratory control samples show method capability inside a glove box. Non-radioactive drum headspace samples use a revised version of USEPA compendium method TO-14. Radioactive drum headspace samples require new instrumentation and change to SW-846 methods.

  3. Failure Analysis and Regeneration Performances Evaluation on Engine Lubricating Oil

    NASA Astrophysics Data System (ADS)

    Wang, X. L.; Zhang, G. N.; Zhang, J. Y.; Yin, Y. L.; Xu, Y.

    To investigate the behavior of failure and recycling of lubricating oils, three sorts of typical 10w-40 lubricating oils used in heavy-load vehicle including the new oil, waste oil and regeneration oil regenerated by self-researched green regeneration technology were selected. The tribology properties were tested by four-ball friction wear tester as well. The results indicated that the performance of anti-extreme pressure of regeneration oil increase by 34.1% compared with the waste one and its load- carrying ability is close to the new oil; the feature of wear spot are better than those of the waste oil and frictional coefficient almost reach the level of the new oil's. As a result, the performance of anti-wear and friction reducing are getting better obviously.

  4. Transient elastohydrodynamic lubrication analysis of metal-on-metal hip implant under simulated walking conditions.

    PubMed

    Liu, F; Jin, Z M; Hirt, F; Rieker, C; Roberts, P; Grigoris, P

    2006-01-01

    The transient elastohydrodynamic lubrication (EHL) analysis was performed in this study for a typical metal-on-metal bearing employing a polyethylene backing underneath a metallic cup inlay under dynamic operating conditions of load and speed representative of normal walking. A ball-in-socket configuration was adopted to represent the articulation between the femoral head and the acetabular cup. The governing Reynolds and elasticity equations were solved simultaneously by using both finite difference and finite element methods. The predicted transient film thickness from the present study was compared with the estimation based on the quasi-static analysis. It was found that the polyethylene backing employed in the typical metal-on-metal hip bearing, combined with dynamic squeeze-film action, significantly improved the transient lubricant film thickness under cyclic walking and consequently a fluid film lubrication regime was possible for smooth bearing surfaces with an average roughness less than 0.005 microm.

  5. Lubrication Flows.

    ERIC Educational Resources Information Center

    Papanastasiou, Tasos C.

    1989-01-01

    Discusses fluid mechanics for undergraduates including the differential Navier-Stokes equations, dimensional analysis and simplified dimensionless numbers, control volume principles, the Reynolds lubrication equation for confined and free surface flows, capillary pressure, and simplified perturbation techniques. Provides a vertical dip coating…

  6. XPS analysis of 440C steel surfaces lubricated with perfluoropolyethers under sliding conditions in high vacuum

    NASA Technical Reports Server (NTRS)

    Herrera-Fierro, Pilar; Masuko, Masabumi; Jones, William R., Jr.; Pepper, Stephen V.

    1994-01-01

    This work presents the results of the X-Ray Photoelectron Spectroscopy (XPS) analysis of AISI 440C ball surfaces lubricated with perfluoropolyether (PFPE) oils after friction experiments under sliding conditions at high load in air and vacuum environments. The PFPE lubricants tested were Demnum S100, Fomblin Z-25, and Krytox 143AB. It was found that all the PFPE lubricants were degraded by sliding contact causing the formation of inorganic fluorides on the metallic surfaces and a layer of organic decomposition products. KRYTOX 143AB was the least reactive of the three lubricants tested. It was also found that metal fluoride formed at off-scar areas. This suggests the formation of reactive species, such as COF2 or R(sub f)COF, during sliding experiments, which can diffuse through the lubricant film and react with the metallic surfaces away from the contact region. Comparison of reference specimens before sliding with those that had undergone the sliding tests showed that the amount of non-degraded PFPE remaining on the surface of the balls after the sliding experiments was greater than that of the balls without sliding.

  7. Mixing order of glidant and lubricant--influence on powder and tablet properties.

    PubMed

    Pingali, Kalyana; Mendez, Rafael; Lewis, Daniel; Michniak-Kohn, Bozena; Cuitino, Alberto; Muzzio, Fernando

    2011-05-16

    The main objective of the present work was to study the effect of mixing order of Cab-O-Sil (CS) and magnesium stearate (MgSt) and microlayers during mixing on blend and tablet properties. A first set of pharmaceutical blend containing Avicel PH200, Pharmatose and micronized acetaminophen was prepared with three mixing orders (mixing order-1: CS added first; mixing order-2: MgSt added first; mixing order-3: CS and MgSt added together). All the blends were subjected to a shear rate of 80 rpm and strain of 40, 160 and 640 revolutions in a controlled shear environment resulting in nine different blends. A second set of nine blends was prepared by replacing Avicel PH200 with Avicel PH102. A total of eighteen blends thus prepared were tested for powder hydrophobicity, powder flow, tablet weight, tablet hardness and tablet dissolution. Results indicated that powder hydrophobicity increased significantly for mixing order-1. Intermediate hydrophobic behavior was found for mixing order-3. Additionally, mixing order 1 resulted in improved powder flow properties, low weight variability, higher average tablet weight and slow drug release rates. Dissolution profiles obtained were found to be strongly dependent not only on the mixing order of flowing agents, but also on the strain and the resulting hydrophobicity.

  8. Mixing order of glidant and lubricant – Influence on powder and tablet properties

    PubMed Central

    Pingali, Kalyana; Mendez, Rafael; Lewis, Daniel; Michniak-Kohn, Bozena; Cuitino, Alberto; Muzzio, Fernando

    2014-01-01

    The main objective of the present work was to study the effect of mixing order of Cab-O-Sil (CS) and magnesium stearate (MgSt) and microlayers during mixing on blend and tablet properties. A first set of pharmaceutical blend containing Avicel PH200, Pharmatose and micronized acetaminophen was prepared with three mixing orders (mixing order-1: CS added first; mixing order-2: MgSt added first; mixing order-3: CS and MgSt added together). All the blends were subjected to a shear rate of 80 rpm and strain of 40, 160 and 640 revolutions in a controlled shear environment resulting in nine different blends. A second set of nine blends was prepared by replacing Avicel PH200 with Avicel PH102. A total of eighteen blends thus prepared were tested for powder hydrophobicity, powder flow, tablet weight, tablet hardness and tablet dissolution. Results indicated that powder hydrophobicity increased significantly for mixing order-1. Intermediate hydrophobic behavior was found for mixing order-3. Additionally, mixing order 1 resulted in improved powder flow properties, low weight variability, higher average tablet weight and slow drug release rates. Dissolution profiles obtained were found to be strongly dependent not only on the mixing order of flowing agents, but also on the strain and the resulting hydrophobicity. PMID:21356286

  9. Testing the ecotoxicology of vegetable versus mineral based lubricating oils: 2. Induction of mixed function oxidase enzymes in barramundi, Lates calcarifer, a tropical fish species.

    PubMed

    Mercurio, Philip; Burns, Kathryn A; Cavanagh, Joanne

    2004-05-01

    An increasing number of vegetable-based oils are being developed as environmentally friendly alternatives to petroleum products. However, toxicity towards key tropical marine species has not been investigated. In this study we used laboratory-based biomarker induction experiments to compare the relative stress of a vegetable-based lubricating oil for marine 2-stroke engines with its mineral oil-based counterpart on tropical fish. The sub-lethal stress of 2-stoke outboard lubricating oils towards the fish Lates calcarifer (barramundi) was examined using liver microsomal mixed function oxidase (MFO) induction assays. This study is the first investigation into the use of this key commercial species in tropical North Queensland, Australia in stress assessment of potential hydrocarbon pollution using ethoxyresorufin O-deethylase (EROD) induction. Our results indicated that barramundi provide a wide range of inducible rates of EROD activity in response to relevant organic stressors. The vegetable- and mineral-based lubricants induced significant EROD activity at 1.0 mg kg(-1) and there was no significant difference between the two oil treatments at that concentration. At increasing concentrations of 2 and 3 mg kg(-1), the mineral-based lubricant resulted in slightly higher EROD activity than the vegetable-based lubricant. The EROD activity of control and treated barramundi are found to be within ranges for other species from temperate and tropical environments. These results indicate that vegetable-based lubricants may be less stressful to barramundi than their mineral counterparts at concentrations of lubricant > or =2 mg kg(-1). There is great potential for this species to be used in the biomonitoring of waterways around tropical North Queensland and SE Asia.

  10. Analysis of a spacecraft instrument ball bearing assembly lubricated by a perfluoroalkylether

    NASA Technical Reports Server (NTRS)

    Morales, W.; Jones, W. R., Jr.; Buckley, D. H.

    1986-01-01

    An analysis of a spacecraft instrument ball bearing assembly, subjected to a scanning life test, was performed to determine the possible case of rotational problems involving these units aboard several satellites. The analysis indicated an ineffective transfer of a fluorinated liquid lubricant from a phenolic retainer to the bearing balls. Part of the analysis led to a novel HPLC separation method employing a fluorinated mobile phase in conjunction with silica based size exclusion columns.

  11. PEEK (Polyether-ether-ketone) Based Cervical Total Disc Arthroplasty: Contact Stress and Lubrication Analysis

    PubMed Central

    Xin, H; Shepherd, DET; Dearn, KD

    2012-01-01

    This paper presents a theoretical analysis of the maximum contact stress and the lubrication regimes for PEEK (Polyether-ether-ketone) based self-mating cervical total disc arthroplasty. The NuNec® cervical disc arthroplasty system was chosen as the study object, which was then analytically modelled as a ball on socket joint. A non-adhesion Hertzian contact model and elastohydrodynamic lubrication theory were used to predict the maximum contact stress and the minimum film thickness, respectively. The peak contact stress and the minimum film thickness between the bearing surfaces were then determined, as the radial clearance or lubricant was varied. The obtained results show that under 150 N loading, the peak contact stress was in the range 5.9 – 32.1 MPa, well below the yield and fatigue strength of PEEK; the calculated minimum film thickness ranged from 0 to 0.042 µm and the corresponding lambda ratio range was from 0 to 0.052. This indicates that the PEEK based cervical disc arthroplasty will operate under a boundary lubrication regime, within the natural angular velocity range of the cervical spine. PMID:22670159

  12. Ionic Liquids as Novel Lubricants and /or Lubricant Additives

    SciTech Connect

    Qu, J.; Viola, M. B.

    2013-10-31

    This ORNL-GM CRADA developed ionic liquids (ILs) as novel lubricants or oil additives for engine lubrication. A new group of oil-miscible ILs have been designed and synthesized with high thermal stability, non-corrosiveness, excellent wettability, and most importantly effective anti-scuffing/anti-wear and friction reduction characteristics. Mechanistic analysis attributes the superior lubricating performance of IL additives to their physical and chemical interactions with metallic surfaces. Working with a leading lubricant formulation company, the team has successfully developed a prototype low-viscosity engine oil using a phosphonium-phosphate IL as an anti-wear additive. Tribological bench tests of the IL-additized formulated oil showed 20-33% lower friction in mixed and elastohydrodynamic lubrication and 38-92% lower wear in boundary lubrication when compared with commercial Mobil 1 and Mobil Clean 5W-30 engine oils. High-temperature, high load (HTHL) full-size engine tests confirmed the excellent anti-wear performance for the IL-additized engine oil. Sequence VID engine dynamometer tests demonstrated an improved fuel economy by >2% for this IL-additized engine oil benchmarked against the Mobil 1 5W-30 oil. In addition, accelerated catalyst aging tests suggest that the IL additive may potentially have less adverse impact on three-way catalysts compared to the conventional ZDDP. Follow-on research is needed for further development and optimization of IL chemistry and oil formulation to fully meet ILSAC GF-5 specifications and further enhance the automotive engine efficiency and durability.

  13. Principles of ESCA and applications to metal corrosion, coating and lubrication. [Electron Spectroscopy for Chemical Analysis

    NASA Technical Reports Server (NTRS)

    Wheeler, D. R.

    1978-01-01

    The principles of ESCA (electron spectroscopy for chemical analysis) are described by comparison with other spectroscopic techniques. The advantages and disadvantages of ESCA as compared to other surface sensitive analytical techniques are evaluated. The use of ESCA is illustrated by actual applications to oxidation of steel and Rene 41, the chemistry of lubricant additives on steel, and the composition of sputter deposited hard coatings. Finally, a bibliography of material that is useful for further study of ESCA is presented and commented upon.

  14. The quantitative surface analysis of an antioxidant additive in a lubricant oil matrix by desorption electrospray ionization mass spectrometry

    PubMed Central

    Da Costa, Caitlyn; Reynolds, James C; Whitmarsh, Samuel; Lynch, Tom; Creaser, Colin S

    2013-01-01

    RATIONALE Chemical additives are incorporated into commercial lubricant oils to modify the physical and chemical properties of the lubricant. The quantitative analysis of additives in oil-based lubricants deposited on a surface without extraction of the sample from the surface presents a challenge. The potential of desorption electrospray ionization mass spectrometry (DESI-MS) for the quantitative surface analysis of an oil additive in a complex oil lubricant matrix without sample extraction has been evaluated. METHODS The quantitative surface analysis of the antioxidant additive octyl (4-hydroxy-3,5-di-tert-butylphenyl)propionate in an oil lubricant matrix was carried out by DESI-MS in the presence of 2-(pentyloxy)ethyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate as an internal standard. A quadrupole/time-of-flight mass spectrometer fitted with an in-house modified ion source enabling non-proximal DESI-MS was used for the analyses. RESULTS An eight-point calibration curve ranging from 1 to 80 µg/spot of octyl (4-hydroxy-3,5-di-tert-butylphenyl)propionate in an oil lubricant matrix and in the presence of the internal standard was used to determine the quantitative response of the DESI-MS method. The sensitivity and repeatability of the technique were assessed by conducting replicate analyses at each concentration. The limit of detection was determined to be 11 ng/mm2 additive on spot with relative standard deviations in the range 3–14%. CONCLUSIONS The application of DESI-MS to the direct, quantitative surface analysis of a commercial lubricant additive in a native oil lubricant matrix is demonstrated. © 2013 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons, Ltd. PMID:24097398

  15. Analysis of wear properties of aluminium based journal bearing alloys with and without lubrication.

    NASA Astrophysics Data System (ADS)

    Mathavan, J. Joy; Patnaik, Amar

    2016-09-01

    Apart from classical bearing materials, Aluminium alloys are used as bearing materials these days because of their superior quality. In this analysis, new Aluminium based bearing materials, with filler metals Si, Ni, and Cr are prepared by metal mould casting in burnout furnace machine, and tribological properties of these alloys with and without lubrication were tested. The experiments for wear with lubrication are conducted on multiple specimen tester and experiments without lubrication is conducted on Pin on disk tribometer. The disc material used was SAE 1050 steel. Wear tests were conducted at a sliding speed of 0.785 m/s and at a normal load of 20 N. Coefficient of friction values, temperature changes and wear of the specimens were plotted on graph according to the above mentioned working conditions. Hardness and weight losses of the specimens were calculated. The obtained results demonstrate how the friction and wear properties of these samples have changed with the % addition of Silicon, Chromium and Nickel to the base metal aluminium.

  16. Solar Alpha Rotary Joint (SARJ) Lubrication Interval Test and Evaluation (LITE). Post-Test Grease Analysis

    NASA Technical Reports Server (NTRS)

    Golden, Johnny L.; Martinez, James E.; Devivar, Rodrigo V.

    2015-01-01

    The Solar Alpha Rotary Joint (SARJ) is a mechanism of the International Space Station (ISS) that orients the solar power generating arrays toward the sun as the ISS orbits our planet. The orientation with the sun must be maintained to fully charge the ISS batteries and maintain all the other ISS electrical systems operating properly. In 2007, just a few months after full deployment, the starboard SARJ developed anomalies that warranted a full investigation including ISS Extravehicular Activity (EVA). The EVA uncovered unexpected debris that was due to degradation of a nitride layer on the SARJ bearing race. ISS personnel identified the failure root-cause and applied an aerospace grease to lubricate the area associated with the anomaly. The corrective action allowed the starboard SARJ to continue operating within the specified engineering parameters. The SARJ LITE (Lubrication Interval Test and Evaluation) program was initiated by NASA, Lockheed Martin, and Boeing to simulate the operation of the ISS SARJ for an extended time. The hardware was designed to test and evaluate the exact material components used aboard the ISS SARJ, but in a controlled area where engineers could continuously monitor the performance. After running the SARJ LITE test for an equivalent of 36+ years of continuous use, the test was opened to evaluate the metallography and lubrication. We have sampled the SARJ LITE rollers and plate to fully assess the grease used for lubrication. Chemical and thermal analysis of these samples has generated information that has allowed us to assess the location, migration, and current condition of the grease. The collective information will be key toward understanding and circumventing any performance deviations involving the ISS SARJ in the years to come.

  17. Advanced in aerospace lubricant and wear metal analysis

    SciTech Connect

    Saba, C.S.; Centers, P.W.

    1995-09-01

    Wear metal analysis continues to play an effective diagnostic role for condition monitoring of gas turbine engines. Since the early 1960s the United States` military services have been using spectrometric oil analysis program (SOAP) to monitor the condition of aircraft engines. The SOAP has proven to be effective in increasing reliability, fleet readiness and avoiding losses of lives and machinery. Even though historical data have demonstrated the success of the SOAP in terms of detecting imminent engine failure verified by maintenance personnel, the SOAP is not a stand-alone technique and is limited in its detection of large metallic wear debris. In response, improved laboratory, portable, in-line and on-line diagnostic techniques to perfect SOAP and oil condition monitoring have been sought. The status of research and development as well as the direction of future developmental activities in oil analysis due to technological opportunities, advanced in engine development and changes in military mission are reviewed and discussed. 54 refs.

  18. Elastohydrodynamic lubrication analysis of metal-on-metal hip prostheses under steady state entraining motion.

    PubMed

    Jagatia, M; Jin, Z M

    2001-01-01

    The elastohydrodynamic lubrication problem of metal-on-metal hip joint replacements was considered in this study. A simple ball-in-socket configuration was used to represent the hip prosthesis. The Reynolds equation in a spherical coordinate was adopted for the fluid-film lubrication analysis, to account for the ball-in-socket geometry. The corresponding elastic deformation was calculated by means of the finite element method in order to consider the complex ball-in-socket geometry as well as the backing materials underneath the acetabular cup. Both the Reynolds and the elasticity equations were solved simultaneously using the Newton-Raphson finite difference method. The general methodology developed was then applied to a recent experimental prototype metal-on-metal hip implant. It was shown that the backing materials underneath the acetabular cup had little influence on the predicted contact pressure and the elastic deformation at the bearing surfaces for this particular example. Both the film thickness and the hydrodynamic pressure distributions were obtained under various loads up to 2500 N. The predicted minimum lubricating film thickness from the present study was compared with a simple estimation using the Hamrock and Dowson formulae based upon an equivalent ball-on-plane model and excellent agreement was found. However, it was pointed out that for some forms of metal-on-metal hip prostheses with a thin acetabular cup, a polyethylene inlay underneath a metallic bearing insert or a taper connection between a bearing insert and a fixation shell, the general methodology developed in the present study should be used and this will be considered in future studies.

  19. Solid lubricants

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1991-01-01

    The state of knowledge of solid lubricants is reviewed. The results of research on solid lubricants from the 1940's to the present are presented from a historical perspective. Emphasis is placed largely, but not exclusively, on work performed at NASA Lewis Research Center with a natural focus on aerospace applications. However, because of the generic nature of the research, the information presented in this review is applicable to most areas where solid lubricant technology is useful.

  20. Pipe flow of pumping wet shotcrete based on lubrication layer.

    PubMed

    Chen, Lianjun; Liu, Guoming; Cheng, Weimin; Pan, Gang

    2016-01-01

    Wet shotcrete can reduce dust and improve supporting strength, however, safe and efficient pipage is a key technical part of wet shotcrete process. The paper studied the pipe flow law of wet shotcrete based on lubrication layer by build the experimental pumping circuit of wet shotcrete that can carry out a number of full-scale pumping tests. The experimental results show there was a linear relationship between pressure loss and flow rate. Combined with the Buckingham rheological equation, the computing equations of the yield shear stress and plastic viscosity were deduced through linear regression. A simple analytical method allowing for a rough estimation of the pumping pressure was proposed and used when considering the lubrication layer of wet shotcrete in pipes. In addition, two kinds of particulate distributive models were established along the time axial to analyze the formation of lubrication layer which is related with particles migration. By computational fluid dynamics simulation, the lubrication layer thickness of different mix proportions was estimated. A new method for measuring the thickness of lubrication layer was proposed to verify it by binarization processing. Finally, according to the comparative analysis of experiments, simulation and computed value, it can be seen that the lubrication layer plays a key role in the process of wet shotcrete flow and with the increase of lubrication layer thickness pipe pressure declines gradually.

  1. Pipe flow of pumping wet shotcrete based on lubrication layer.

    PubMed

    Chen, Lianjun; Liu, Guoming; Cheng, Weimin; Pan, Gang

    2016-01-01

    Wet shotcrete can reduce dust and improve supporting strength, however, safe and efficient pipage is a key technical part of wet shotcrete process. The paper studied the pipe flow law of wet shotcrete based on lubrication layer by build the experimental pumping circuit of wet shotcrete that can carry out a number of full-scale pumping tests. The experimental results show there was a linear relationship between pressure loss and flow rate. Combined with the Buckingham rheological equation, the computing equations of the yield shear stress and plastic viscosity were deduced through linear regression. A simple analytical method allowing for a rough estimation of the pumping pressure was proposed and used when considering the lubrication layer of wet shotcrete in pipes. In addition, two kinds of particulate distributive models were established along the time axial to analyze the formation of lubrication layer which is related with particles migration. By computational fluid dynamics simulation, the lubrication layer thickness of different mix proportions was estimated. A new method for measuring the thickness of lubrication layer was proposed to verify it by binarization processing. Finally, according to the comparative analysis of experiments, simulation and computed value, it can be seen that the lubrication layer plays a key role in the process of wet shotcrete flow and with the increase of lubrication layer thickness pipe pressure declines gradually. PMID:27386389

  2. Process for preparing lubricating oil from used waste lubricating oil

    DOEpatents

    Whisman, Marvin L.; Reynolds, James W.; Goetzinger, John W.; Cotton, Faye O.

    1978-01-01

    A re-refining process is described by which high-quality finished lubricating oils are prepared from used waste lubricating and crankcase oils. The used oils are stripped of water and low-boiling contaminants by vacuum distillation and then dissolved in a solvent of 1-butanol, 2-propanol and methylethyl ketone, which precipitates a sludge containing most of the solid and liquid contaminants, unspent additives, and oxidation products present in the used oil. After separating the purified oil-solvent mixture from the sludge and recovering the solvent for recycling, the purified oil is preferably fractional vacuum-distilled, forming lubricating oil distillate fractions which are then decolorized and deodorized to prepare blending stocks. The blending stocks are blended to obtain a lubricating oil base of appropriate viscosity before being mixed with an appropriate additive package to form the finished lubricating oil product.

  3. Fourier emission infrared microspectrophotometer for surface analysis. I - Application to lubrication problems

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.; King, V. W.

    1979-01-01

    A far-infrared interferometer was converted into an emission microspectrophotometer for surface analysis. To cover the mid-infrared as well as the far-infrared the Mylar beamsplitter was made replaceable by a germanium-coated salt plate, and the Moire fringe counting system used to locate the moveable Michelson mirror was improved to read 0.5 micron of mirror displacement. Digital electronics and a dedicated minicomputer were installed for data collection and processing. The most critical element for the recording of weak emission spectra from small areas was, however, a reflecting microscope objective and phase-locked signal detection with simultaneous referencing to a blackbody source. An application of the technique to lubrication problems is shown.

  4. Lubricating oil analysis for wear monitoring (citations from the NTIS Data Base). Report for 1964-April 1980

    SciTech Connect

    Cavagnaro, D.M.

    1980-04-01

    The topics pertain to the chemical analysis of lubricating oils to determine and monitor the wear of engines or transmissions. The purpose of this analysis is to predict failure before it occurs in order to allow time to undertake corrective maintenance. Many of these reports are part of the Army's Spectrometric Oil Analysis Program (SOAP). Various detectors and analytical methods are cited as well as their implementation. (This updated bibliography contains 172 abstracts, 11 of which are new entries to the previous edition.)

  5. Multiscale analysis of liquid lubrication trends from industrial machines to micro-electrical-mechanical systems.

    PubMed

    Brenner, Donald W; Irving, Douglas L; Kingon, Angus I; Krim, Jacqueline; Padgett, Clifford W

    2007-08-28

    An analytic multiscale expression is derived that yields conditions for effective liquid lubrication of oscillating contacts via surface flow over multiple time and length scales. The expression is a logistics function that depends on two quantities, the fraction of lubricant removed at each contact and a scaling parameter given by the logarithm of the ratio of the contact area to the product of the lubricant diffusion coefficient and the cycle time. For industrial machines the expression confirms the need for an oil mist. For magnetic disk drives, the expression predicts that existing lubricants are sufficient for next-generation data storage. For micro-electrical-mechanical systems, the expression predicts that a bound + mobile lubricant composed of tricresyl phosphate on an octadecyltrichlorosilane self-assembled monolayer will be effective only for temperatures greater than approximately 200 K and up to approximately MHz oscillation frequencies. PMID:17661501

  6. Lubrication analysis of interacting rigid cylindrical particles in confined shear flow

    SciTech Connect

    Cardinaels, R.; Stone, H. A.

    2015-07-15

    Lubrication analysis is used to determine analytical expressions for the elements of the resistance matrix describing the interaction of two rigid cylindrical particles in two-dimensional shear flow in a symmetrically confined channel geometry. The developed model is valid for non-Brownian particles in a low-Reynolds-number flow between two sliding plates with thin gaps between the two particles and also between the particles and the walls. Using this analytical model, a comprehensive overview of the dynamics of interacting cylindrical particles in shear flow is presented. With only hydrodynamic interactions, rigid particles undergo a reversible interaction with no cross-streamline migration, irrespective of the confinement value. However, the interaction time of the particle pair substantially increases with confinement, and at the same time, the minimum distance between the particle surfaces during the interaction substantially decreases with confinement. By combining our purely hydrodynamic model with a simple on/off non-hydrodynamic attractive particle interaction force, the effects of confinement on particle aggregation are qualitatively mapped out in an aggregation diagram. The latter shows that the range of initial relative particle positions for which aggregation occurs is increased substantially due to geometrical confinement. The interacting particle pair exhibits tangential and normal lubrication forces on the sliding plates, which will contribute to the rheology of confined suspensions in shear flow. Due to the combined effects of the confining walls and the particle interaction, the particle velocities and resulting forces both tangential and perpendicular to the walls exhibit a non-monotonic evolution as a function of the orientation angle of the particle pair. However, by incorporating appropriate scalings of the forces, velocities, and doublet orientation angle with the minimum free fraction of the gap height and the plate speed, master curves for

  7. Lubrication and friction prediction in metal-on-metal hip implants

    NASA Astrophysics Data System (ADS)

    Wang, F. C.; Brockett, C.; Williams, S.; Udofia, I.; Fisher, J.; Jin, Z. M.

    2008-03-01

    A general methodology of mixed lubrication analysis and friction prediction for a conforming spherical bearing in hip implants was developed, with particular reference to a typical metal-on-metal hip replacement. Experimental measurement of frictional torque for a similar implant was carried out to validate the theoretical prediction. A ball-in-socket configuration was adopted to represent the articulation between the femoral head and the acetabular cup under cyclic operating conditions of representative load and motion. The mixed lubrication model presented in this study was first applied to identify the contact characteristics on the bearing surfaces, consisting of both fluid-film and boundary lubricated regions. The boundary lubricated contact was assumed to occur when the predicted fluid film thickness was less than a typical boundary protein layer absorbed on the bearing surfaces. Subsequently, the friction was predicted from the fluid-film lubricated region with viscous shearing due to both Couette and Poiseuille flows and the boundary protein layer contact region with a constant coefficient of friction. The predicted frictional torque of the typical metal-on-metal hip joint implant was compared with the experimental measurement conducted in a functional hip simulator and a reasonably good agreement was found. The mixed lubrication regime was found to be dominant for the conditions considered. Although the percentage of the boundary lubricated region was quite small, the corresponding contribution to friction was quite large and the resultant friction factor was quite high.

  8. Lubrication and friction prediction in metal-on-metal hip implants.

    PubMed

    Wang, F C; Brockett, C; Williams, S; Udofia, I; Fisher, J; Jin, Z M

    2008-03-01

    A general methodology of mixed lubrication analysis and friction prediction for a conforming spherical bearing in hip implants was developed, with particular reference to a typical metal-on-metal hip replacement. Experimental measurement of frictional torque for a similar implant was carried out to validate the theoretical prediction. A ball-in-socket configuration was adopted to represent the articulation between the femoral head and the acetabular cup under cyclic operating conditions of representative load and motion. The mixed lubrication model presented in this study was first applied to identify the contact characteristics on the bearing surfaces, consisting of both fluid-film and boundary lubricated regions. The boundary lubricated contact was assumed to occur when the predicted fluid film thickness was less than a typical boundary protein layer absorbed on the bearing surfaces. Subsequently, the friction was predicted from the fluid-film lubricated region with viscous shearing due to both Couette and Poiseuille flows and the boundary protein layer contact region with a constant coefficient of friction. The predicted frictional torque of the typical metal-on-metal hip joint implant was compared with the experimental measurement conducted in a functional hip simulator and a reasonably good agreement was found. The mixed lubrication regime was found to be dominant for the conditions considered. Although the percentage of the boundary lubricated region was quite small, the corresponding contribution to friction was quite large and the resultant friction factor was quite high.

  9. Marine Lubricants

    NASA Astrophysics Data System (ADS)

    Carter, B. H.; Green, D.

    Marine diesel engines are classified by speed, either large (medium speed) or very large (slow speed) with high efficiencies and burning low-quality fuel. Slow-speed engines, up to 200 rpm, are two-stroke with separate combustion chamber and sump connected by a crosshead, with trunk and system oil lubricants for each. Medium-speed diesels, 300-1500 rpm, are of conventional automotive design with one lubricant. Slow-speed engines use heavy fuel oil of much lower quality than conventional diesel with problems of deposit cleanliness, acidity production and oxidation. Lubricants are mainly SAE 30/40/50 monogrades using paraffinic basestocks. The main types of additives are detergents/dispersants, antioxidants, corrosion inhibitors, anti-wear/load-carrying/ep, pour-point depressants and anti-foam compounds. There are no simple systems for classifying marine lubricants, as for automotive, because of the wide range of engine design, ratings and service applications they serve. There are no standard tests; lubricant suppliers use their own tests or the Bolnes 3DNL, with final proof from field tests. Frequent lubricant analyses safeguard engines and require standard sampling procedures before determination of density, viscosity, flash point, insolubles, base number, water and wear metal content.

  10. Numerical analysis of the effects of material parameters on the lubrication mechanism for knee prosthesis.

    PubMed

    Di Paolo, J; Berli, M E

    2006-04-01

    The tibial component of current knee prostheses made of ultra high molecular weight polyethylene (UHMWPE) has a high degree of wear that causes knee inflammation, prosthesis loosening and subsequent replacement in not more than 15 years. In order to know which UHMWPE material properties have more influence on wear, a steady state lubrication model with non-Newtonian synovial fluid has been studied through numerical solution. The results show that UHMWPE has a very high elastic modulus that makes difficult a well lubricated artificial joint and induces the formation of very thin lubricating films between the moving surfaces with the same magnitude of roughness components. This study shows that the use of deformable porous materials in the tibial component could cause the lubricating film thickness to be higher than the average roughness and the pressure levels to be lower than the one predicted for UHMWPE. These two facts imply friction and wear reduction.

  11. Predictive modelling of fatigue failure in concentrated lubricated contacts.

    PubMed

    Evans, H P; Snidle, R W; Sharif, K J; Bryant, M J

    2012-01-01

    Reducing frictional losses in response to the energy agenda will require use of less viscous lubricants causing hydrodynamically-lubricated bearings to operate with thinner films leading to "mixed lubrication" conditions in which a degree of direct interaction occurs between surfaces protected only by boundary tribofilms. The paper considers the consequences of thinner films and mixed lubrication for concentrated contacts such as those occurring between the teeth of power transmission gears and in rolling element bearings. Surface fatigue in gears remains a serious problem in demanding applications, and its solution will become more pressing with the tendency towards thinner oils. The particular form of failure examined here is micropitting, which is identified as a fatigue phenomenon occurring at the scale of the surface roughness asperities. It has emerged recently as a systemic difficulty in the operation of large scale wind turbines where it occurs in both power transmission gears and their support bearings. Predictive physical modelling of these contacts requires a transient mixed lubrication analysis for conditions in which the predicted lubricant film thickness is of the same order or significantly less than the height of surface roughness features. Numerical solvers have therefore been developed which are able to deal with situations in which transient solid contacts occur between surface asperity features under realistic engineering conditions. Results of the analysis, which reveal the detailed time-varying behaviour of pressure and film clearance, have been used to predict fatigue and damage accumulation at the scale of surface asperity features with the aim of improving understanding of the micropitting phenomenon. The possible consequences on fatigue of residual stress fields resulting from plastic deformation of surface asperities is also considered.

  12. Predictive modelling of fatigue failure in concentrated lubricated contacts.

    PubMed

    Evans, H P; Snidle, R W; Sharif, K J; Bryant, M J

    2012-01-01

    Reducing frictional losses in response to the energy agenda will require use of less viscous lubricants causing hydrodynamically-lubricated bearings to operate with thinner films leading to "mixed lubrication" conditions in which a degree of direct interaction occurs between surfaces protected only by boundary tribofilms. The paper considers the consequences of thinner films and mixed lubrication for concentrated contacts such as those occurring between the teeth of power transmission gears and in rolling element bearings. Surface fatigue in gears remains a serious problem in demanding applications, and its solution will become more pressing with the tendency towards thinner oils. The particular form of failure examined here is micropitting, which is identified as a fatigue phenomenon occurring at the scale of the surface roughness asperities. It has emerged recently as a systemic difficulty in the operation of large scale wind turbines where it occurs in both power transmission gears and their support bearings. Predictive physical modelling of these contacts requires a transient mixed lubrication analysis for conditions in which the predicted lubricant film thickness is of the same order or significantly less than the height of surface roughness features. Numerical solvers have therefore been developed which are able to deal with situations in which transient solid contacts occur between surface asperity features under realistic engineering conditions. Results of the analysis, which reveal the detailed time-varying behaviour of pressure and film clearance, have been used to predict fatigue and damage accumulation at the scale of surface asperity features with the aim of improving understanding of the micropitting phenomenon. The possible consequences on fatigue of residual stress fields resulting from plastic deformation of surface asperities is also considered. PMID:23285624

  13. Bonded Lubricants

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Another spinoff to the food processing industry involves a dry lubricant developed by General Magnaplate Corp. of Linden, N.J. Used in such spacecraft as Apollo, Skylab and Viking, the lubricant is a coating bonded to metal surfaces providing permanent lubrication and corrosion resistance. The coating lengthens equipment life and permits machinery to be operated at greater speed, thus increasing productivity and reducing costs. Bonded lubricants are used in scores of commercia1 applications. They have proved particularly valuable to food processing firms because, while increasing production efficiency, they also help meet the stringent USDA sanitation codes for food-handling equipment. For example, a cookie manufacturer plagued production interruptions because sticky batter was clogging the cookie molds had the brass molds coated to solve the problem. Similarly, a pasta producer faced USDA action on a sanitation violation because dough was clinging to an automatic ravioli-forming machine; use of the anti-stick coating on the steel forming plates solved the dual problem of sanitation deficiency and production line downtime.

  14. Importance of head diameter, clearance, and cup wall thickness in elastohydrodynamic lubrication analysis of metal-on-metal hip resurfacing prostheses.

    PubMed

    Liu, Feng; Jin, Zhongmin; Roberts, P; Grigoris, P

    2006-08-01

    The main design features of metal-on-metal (MOM) hip resurfacing prostheses in promoting elastohydrodynamic lubrication were investigated in the present study, including the femoral head diameter, the clearance, and the cup wall thickness. Simplified conceptual models were developed, based on equivalent uniform wall thicknesses for both the cup and the head as well as the support materials representing bone and cement, and subsequently used for elastohydrodynamic lubrication analysis. Both typical first- and second-generation MOM hip resurfacing prostheses with different clearances and cup wall thicknesses were considered with a fixed large bearing diameter of 50 mm, as well as a 28 mm diameter MOM total hip replacement bearing for the purpose of comparison. The importance of the head diameter and the clearance in promoting elastohydrodynamic lubrication was confirmed. Furthermore, it was also predicted that a relatively thin acetabular cup in the more recently introduced second-generation MOM hip resurfacing prostheses would be capable of improving elastohydrodynamic lubrication even further.

  15. A Thermal Equilibrium Analysis of Line Contact Hydrodynamic Lubrication Considering the Influences of Reynolds Number, Load and Temperature.

    PubMed

    Yu, Xiaoli; Sun, Zheng; Huang, Rui; Zhang, Yu; Huang, Yuqi

    2015-01-01

    Thermal effects such as conduction, convection and viscous dissipation are important to lubrication performance, and they vary with the friction conditions. These variations have caused some inconsistencies in the conclusions of different researchers regarding the relative contributions of these thermal effects. To reveal the relationship between the contributions of the thermal effects and the friction conditions, a steady-state THD analysis model was presented. The results indicate that the contribution of each thermal effect sharply varies with the Reynolds number and temperature. Convective effect could be dominant under certain conditions. Additionally, the accuracy of some simplified methods of thermo-hydrodynamic analysis is further discussed.

  16. A Thermal Equilibrium Analysis of Line Contact Hydrodynamic Lubrication Considering the Influences of Reynolds Number, Load and Temperature

    PubMed Central

    Yu, Xiaoli; Sun, Zheng; Huang, Rui; Zhang, Yu; Huang, Yuqi

    2015-01-01

    Thermal effects such as conduction, convection and viscous dissipation are important to lubrication performance, and they vary with the friction conditions. These variations have caused some inconsistencies in the conclusions of different researchers regarding the relative contributions of these thermal effects. To reveal the relationship between the contributions of the thermal effects and the friction conditions, a steady-state THD analysis model was presented. The results indicate that the contribution of each thermal effect sharply varies with the Reynolds number and temperature. Convective effect could be dominant under certain conditions. Additionally, the accuracy of some simplified methods of thermo-hydrodynamic analysis is further discussed. PMID:26244665

  17. Tethered Lubricants

    SciTech Connect

    Archer, Lynden

    2010-09-15

    We have performed extensive experimental and theoretical studies of interfacial friction, relaxation dynamics, and thermodynamics of polymer chains tethered to points, planes, and particles. A key result from our tribology studies using lateral force microscopy (LFM) measurements of polydisperse brushes of linear and branched chains densely grafted to planar substrates is that there are exceedingly low friction coefficients for these systems. Specific project achievements include: (1) Synthesis of three-tiered lubricant films containing controlled amounts of free and pendent PDMS chains, and investigated the effect of their molecular weight and volume fraction on interfacial friction. (2.) Detailed studies of a family of hairy particles termed nanoscale organic hybrid materials (NOHMs) and demonstration of their use as lubricants.

  18. Space Station long term lubrication analysis. Phase 1 preliminary tribological survey

    NASA Technical Reports Server (NTRS)

    Dufrane, K. F.; Kannel, J. W.; Lowry, J. A.; Montgomery, E. E.

    1990-01-01

    Increases in the size, complexity, and life requirements of satellites and space vehicles have put increasing demands on the lubrication requirements for trouble-free service. Since the development costs of large systems are high, long lives with minimum maintenance are dictated. The Space Station represents the latest level of size and complexity in satellite development; it will be nearly 100 meters in major dimensions and will have a life requirement of thirty years. It will have numerous mechanisms critical to its success, some of which will be exposed to the space environment. Designing long-life lubrication systems and choosing appropriate lubricants for these systems will be necessary for their meeting the requirements and for avoiding failures with associated dependent mechanisms. The purpose of this program was to identify the various critical mechanisms and review their designs during the overall design and development stage so that problem areas could be avoided or minimized prior to the fabrication of hardware. The specific objectives were fourfold: (1) to perform a tribology survey of the Space Station for the purpose of documenting each wear point as to materials involved, environmental conditions, and operating characteristics; (2) to review each wear point (point of relative motion) as to the lubrication used and substrate materials selected in the context of its operating characteristics and the environmental conditions imposed; (3) to make recommendations for improvement in areas where the lubricant chosen and/or where the substrate (materials of the wear couple) are not considered optimum for the application; and (4) to make or recommend simulated or full scale tests in tribological areas where the state-of-the-art is being advanced, in areas where new designs are obviously being employed and a critical review would indicate that problems are a strong possibility, and/or where excessive wear, a malfunction, or excessive leakage would create fluid

  19. Space Station long term lubrication analysis. Phase 1 preliminary tribological survey

    NASA Astrophysics Data System (ADS)

    Dufrane, K. F.; Kannel, J. W.; Lowry, J. A.; Montgomery, E. E.

    1990-09-01

    Increases in the size, complexity, and life requirements of satellites and space vehicles have put increasing demands on the lubrication requirements for trouble-free service. Since the development costs of large systems are high, long lives with minimum maintenance are dictated. The Space Station represents the latest level of size and complexity in satellite development; it will be nearly 100 meters in major dimensions and will have a life requirement of thirty years. It will have numerous mechanisms critical to its success, some of which will be exposed to the space environment. Designing long-life lubrication systems and choosing appropriate lubricants for these systems will be necessary for their meeting the requirements and for avoiding failures with associated dependent mechanisms. The purpose of this program was to identify the various critical mechanisms and review their designs during the overall design and development stage so that problem areas could be avoided or minimized prior to the fabrication of hardware. The specific objectives were fourfold: (1) to perform a tribology survey of the Space Station for the purpose of documenting each wear point as to materials involved, environmental conditions, and operating characteristics; (2) to review each wear point (point of relative motion) as to the lubrication used and substrate materials selected in the context of its operating characteristics and the environmental conditions imposed; (3) to make recommendations for improvement in areas where the lubricant chosen and/or where the substrate (materials of the wear couple) are not considered optimum for the application; and (4) to make or recommend simulated or full scale tests in tribological areas where the state-of-the-art is being advanced, in areas where new designs are obviously being employed and a critical review would indicate that problems are a strong possibility, and/or where excessive wear, a malfunction, or excessive leakage would create fluid

  20. Liquid lubrication for space applications

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.; Khonsari, Michael M.

    1992-01-01

    Reviewed here is the state of the art of liquid lubrication for space applications. The areas discussed are types of liquid lubrication mechanisms, space environmental effects on lubrication, classification of lubricants, liquid lubricant additives, grease lubrication, mechanism materials, bearing anomalies and failures, lubricant supply techniques, and application types and lubricant needs for those applications.

  1. Solid lubrication design methodology, phase 2

    NASA Technical Reports Server (NTRS)

    Pallini, R. A.; Wedeven, L. D.; Ragen, M. A.; Aggarwal, B. B.

    1986-01-01

    The high temperature performance of solid lubricated rolling elements was conducted with a specially designed traction (friction) test apparatus. Graphite lubricants containing three additives (silver, phosphate glass, and zinc orthophosphate) were evaluated from room temperature to 540 C. Two hard coats were also evaluated. The evaluation of these lubricants, using a burnishing method of application, shows a reasonable transfer of lubricant and wear protection for short duration testing except in the 200 C temperature range. The graphite lubricants containing silver and zinc orthophosphate additives were more effective than the phosphate glass material over the test conditions examined. Traction coefficients ranged from a low of 0.07 to a high of 0.6. By curve fitting the traction data, empirical equations for slope and maximum traction coefficient as a function of contact pressure (P), rolling speed (U), and temperature (T) can be developed for each lubricant. A solid lubricant traction model was incorporated into an advanced bearing analysis code (SHABERTH). For comparison purposes, preliminary heat generation calculations were made for both oil and solid lubricated bearing operation. A preliminary analysis indicated a significantly higher heat generation for a solid lubricated ball bearing in a deep groove configuration. An analysis of a cylindrical roller bearing configuration showed a potential for a low friction solid lubricated bearing.

  2. Glass microsphere lubrication

    NASA Technical Reports Server (NTRS)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

  3. Investigations of lubricant rheology as applied to elastohydrodynamic lubrication

    NASA Technical Reports Server (NTRS)

    Carlson, S.; Turchina, V.; Jakobsen, J.; Sanborn, D. M.; Winer, W. O.

    1973-01-01

    The pressure viscometer was modified to permit the measurement of viscosity at elevated pressures and shear stresses up to 5 x 10 to the 6th power N/sq m (720 psi). This shear stress is within a factor of three of the shear stress occurring in a sliding ehd point contact such as occurs in the ehd simulator. Viscosity data were taken on five lubricant samples, and it was found that viscous heating effects on the viscosity were predominant and not non-Newtonian behavior at the high shear stresses. The development of the infrared temperature measuring technique for the ehd simulator was completed, and temperature data for a set of operating conditions and one lubricant are reported. The numerical analysis of the behavior of nonlinear lubricants in the lubrication of rollers is reported.

  4. Engine Lubricant

    NASA Technical Reports Server (NTRS)

    1993-01-01

    PS 212, a plasma-sprayed coating developed by NASA, is used to coat valves in a new rotorcam engine. The coating eliminates the need for a liquid lubricant in the rotorcam, which has no crankshaft, flywheel, distributor or water pump. Developed by Murray United Development Corporation, it is a rotary engine only 10 inches long with four cylinders radiating outward from a central axle. Company officials say the engine will be lighter, more compact and cheaper to manufacture than current engines and will feature cleaner exhaust emissions. A licensing arrangement with a manufacturer is under negotiation. Primary applications are for automobiles, but the engine may also be used in light aircraft.

  5. Steady-state elastohydrodynamic lubrication analysis of a metal-on-metal hip implant employing a metallic cup with an ultra-high molecular weight polyethylene backing.

    PubMed

    Liu, F; Wang, F C; Jin, Z M; Hirt, F; Rieker, C; Grigoris, P

    2004-01-01

    The elastohydrodynamic lubrication (EHL) analysis was carried out in this study for a 28 mm diameter metal-on-metal hip prosthesis employing a metallic cup with an ultra-high molecular weight polyethylene (UHMWPE) backing under a simple steady state rotation representing the flexion/extension during walking. Both Reynolds and elasticity equations were coupled and solved numerically by the finite difference method. The elastic deformation was determined by means of the fast Fourier transform (FFT) technique using the displacement coefficients obtained from the finite element method. Excellent agreement of the predicted elastic deformation was obtained between the FFT technique and the conventional direct summation method. The number of grid points used in the lubrication analysis was found to be important in predicting accurate film thicknesses, particularly at low viscosities representative of physiological lubricants. The effect of the clearance between the femoral head and the acetabular cup on the predicted lubricant film thickness was shown to be significant, while the effect of load was found to be negligible. Overall, the UHMWPE backing was found not only to reduce the contact pressure as identified in a previous study by the authors (Liu et al., 2003) but also significantly to increase the lubricant film thickness for the 28 mm diameter metal-on-metal hip implant, as compared with a metallic mono-block cup.

  6. MIXING QUANTIFICATION BY VISUAL IMAGING ANALYSIS

    EPA Science Inventory

    This paper reports on development of a method for quantifying two measures of mixing, the scale and intensity of segregation, through flow visualization, video recording, and software analysis. This non-intrusive method analyzes a planar cross section of a flowing system from an ...

  7. DOE mixed waste treatment capacity analysis

    SciTech Connect

    Ross, W.A.; Wehrman, R.R.; Young, J.R.; Shaver, S.R.

    1994-06-01

    This initial DOE-wide analysis compares the reported national capacity for treatment of mixed wastes with the calculated need for treatment capacity based on both a full treatment of mixed low-level and transuranic wastes to the Land Disposal Restrictions and on treatment of transuranic wastes to the WIPP waste acceptance criteria. The status of treatment capacity is reported based on a fifty-element matrix of radiation-handling requirements and functional treatment technology categories. The report defines the classifications for the assessment, describes the models used for the calculations, provides results from the analysis, and includes appendices of the waste treatment facilities data and the waste stream data used in the analysis.

  8. Analysis of the gas-lubricated flat-sector-pad thrust bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    A flat sector-shaped pad geometry for a gas-lubricated thrust bearing is analyzed considering both the pitch and roll of the pad. It is shown that maximum load capacity is achieved when the pad is tilted so as to create uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves, and a comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

  9. Elastohydrodynamic lubrication theory

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1982-01-01

    The isothermal elastohydrodynamic lubrication (EHL) of a point contact was analyzed numerically by simultaneously solving the elasticity and Reynolds equations. In the elasticity analysis the contact zone was divided into equal rectangular areas, and it was assumed that a uniform pressure was applied over each area. In the numerical analysis of the Reynolds equation, a phi analysis (where phi is equal to the pressure times the film thickness to the 3/2 power) was used to help the relaxation process. The EHL point contact analysis is applicable for the entire range of elliptical parameters and is valid for any combination of rolling and sliding within the contact.

  10. An online debris sensor system with vibration resistance for lubrication analysis

    NASA Astrophysics Data System (ADS)

    Ding, Yongbin; Wang, Yanxue; Xiang, Jiawei

    2016-02-01

    The health condition of the lubricated systems can be directly indicated by the concentration and material type of the abrasive particles, which may provide very early warnings of faults/failures and benefit the condition based maintenance. Oil debris particle detecting techniques are thus important for machinery condition monitoring and fault diagnosis. This work proposes a new structure of online debris sensor (ODS), which applies the radial magnetic field, different from the traditional axial magnetic field. The designed ODS can effectively reduce the interferences of the background noise and the vibration of the machine in operation. Moreover, in order to optimally determine the number of turns of an inductive coil and the current of the drive coils, two methods are developed respectively in this work which can ensure sensitivity and anti-vibration features of the ODS. The instrumentation circuit system for detecting debris particles and sensing signals has been also designed to extract and to record the signatures of particles. The designed ODS device is then applied to analyze micro debris particles in the lubricating system on a test rig. Experimental results have demonstrated that ODS can successfully detect the 120 μm(H) ferrous particles and 500 μm(H) non-ferrous particles under vibration conditions.

  11. Spectroscopic analysis of the tribological behavior of a model boundary layer lubricant.

    PubMed

    Nichols, A; Street, S C

    2001-08-01

    Highly ordered alkanethiol self-assembled monolayers (SAMs) on gold substrates are suitable models of boundary layer lubricants and may be used in actual nanoscale device applications. Here, such monolayers were studied by spectroscopic methods as a function of tribological wear (rubbing) using a pin-on-disk microtribometer. The coefficient of friction (COF) (ratio of the frictional force to the load) was measured with the tribometer, and reflectance infrared spectra and X-ray photoelectron spectra were obtained as the monolayer film failed and the COF changed. The results show that it is possible to correlate disorder in the monolayer film with tribological failure of the film, and that continued rubbing produces a chemical change in the monolayer film. Disorder in the monolayer is distinct from the influence of wear in the underlying gold substrate. Aged SAMs, having sulfonate rather than thiol headgroups and initially less well ordered, behave differently to the well-ordered freshly prepared SAMs. Interestingly, they show a lower COF over many more cycles of exposure to the rubbing pin. The impact of the mechanism of film failure in boundary layer lubrication is discussed.

  12. An online debris sensor system with vibration resistance for lubrication analysis.

    PubMed

    Ding, Yongbin; Wang, Yanxue; Xiang, Jiawei

    2016-02-01

    The health condition of the lubricated systems can be directly indicated by the concentration and material type of the abrasive particles, which may provide very early warnings of faults/failures and benefit the condition based maintenance. Oil debris particle detecting techniques are thus important for machinery condition monitoring and fault diagnosis. This work proposes a new structure of online debris sensor (ODS), which applies the radial magnetic field, different from the traditional axial magnetic field. The designed ODS can effectively reduce the interferences of the background noise and the vibration of the machine in operation. Moreover, in order to optimally determine the number of turns of an inductive coil and the current of the drive coils, two methods are developed respectively in this work which can ensure sensitivity and anti-vibration features of the ODS. The instrumentation circuit system for detecting debris particles and sensing signals has been also designed to extract and to record the signatures of particles. The designed ODS device is then applied to analyze micro debris particles in the lubricating system on a test rig. Experimental results have demonstrated that ODS can successfully detect the 120 μm(H) ferrous particles and 500 μm(H) non-ferrous particles under vibration conditions.

  13. Comparison of friction and lubrication of different hip prostheses.

    PubMed

    Scholes, S C; Unsworth, A

    2000-01-01

    It is well documented that an important cause of osteolysis and subsequent loosening of replacement hip joints is polyethylene wear debris. To avoid this, interest has been renewed in metal-on-metal and ceramic-on-ceramic prostheses. Various workers have assessed the lubrication modes of different joints by measuring the friction at the bearing surfaces, using different lubricants. Measurements of friction factors of a series of hip prostheses were undertaken using carboxymethyl cellulose (CMC) fluids, silicone fluids, synovial fluid and different concentrations of bovine serum as the lubricant. The experimental results were compared with theoretical predictions of film thicknesses and lubrication modes. A strong correlation was observed between experiment and theory when employing CMC fluids or silicone fluids as the lubricant. Mixed lubrication was found to occur in the metal-on-metal (CoCrMo/CoCrMo) joints with all lubricants at a viscosity within the physiological range. This was also the case for the metal-on-plastic (CoCrMo/ultra-high molecular weight polyethylene) joints. The ceramic-on-ceramic (Al2O3/Al2O3) joints, however, exhibited full fluid film lubrication with the synthetic lubricants but mixed lubrication with the biological lubricants. Employing a biological fluid as the lubricant affected the friction to varying degrees when compared with the synthetic lubricants. In the case of the ceramic-on-ceramic joints it acted to increase the friction factor tenfold; however, for the metal-on-metal joints, biological fluids gave slightly lower friction than the synthetic lubricants did. This suggests that, when measuring friction and wear of artificial joints, a standard lubricant should be used.

  14. Analysis of DRIRU bearings and lubricant from solar max repair mission

    NASA Technical Reports Server (NTRS)

    Uber, J. M.

    1985-01-01

    The Solar Maximum Repair Mission (SMRM) by the shuttle astronauts in April 1984, returned to Earth the Delta Redundant Inertial Reference Unit 2 (DRIRU 2) from the Solar Maximum satellite. The DRIRU 2 included three gyroscopes. The gyroscope, S/N 094, in position 2 was disassembled by Teledyne Systems personnel of Northridge, California, and the bearings were returned to Goddard Space Flight Center for examination. The Solar Max Satellite was in orbit for 4 years with the bearings running continuously at 6000 rpm. The ball bearings, had sufficient remaining lubrication and had runs successfully for over the last 4 years. As a result of these findings, the bearings should have lasted their predicted life of 5 years with no problems.

  15. The role of thermal and lubricant boundary layers in the transient thermal analysis of spur gears

    NASA Technical Reports Server (NTRS)

    El-Bayoumy, L. E.; Akin, L. S.; Townsend, D. P.; Choy, F. C.

    1989-01-01

    An improved convection heat-transfer model has been developed for the prediction of the transient tooth surface temperature of spur gears. The dissipative quality of the lubricating fluid is shown to be limited to the capacity extent of the thermal boundary layer. This phenomenon can be of significance in the determination of the thermal limit of gears accelerating to the point where gear scoring occurs. Steady-state temperature prediction is improved considerably through the use of a variable integration time step that substantially reduces computer time. Computer-generated plots of temperature contours enable the user to animate the propagation of the thermal wave as the gears come into and out of contact, thus contributing to better understanding of this complex problem. This model has a much better capability at predicting gear-tooth temperatures than previous models.

  16. Complex frictional analysis of self-lubricant W-S-C/Cr coating.

    PubMed

    Polcar, Tomas; Gustavsson, Fredrik; Thersleff, Thomas; Jacobson, Staffan; Cavaleiro, Albano

    2012-01-01

    Transition metal dichalcogenides belong to one of the most developed classes of materials for solid lubrication. However, one of the main drawbacks of most of the self-lubricating coatings is their low load-bearing capacity, particularly in terrestrial atmospheres. In our previous work, alloying thin films based on tungsten disulfide with non-metallic interstitial elements, such as carbon or nitrogen, has been studied in order to improve tribological performance in different environments. Excellent results were reached with the deposited coatings hardness, in some cases, more than one order of magnitude higher than single W-S films. In this work, W-S-C films were deposited with increasing Cr contents by co-sputtering chromium and composite WS2-C and targets. Two films were prepared with approx. 7 and 13 at.% of Cr. Alloying with chromium led to dense films with amorphous microstructure; the hardness and adhesion was improved. Sliding tests were carried out in dry and humid air using a pin-on-disc tribometer with 100Cr6 steel balls as a counterpart. To analyse the sliding process, the surfaces in the contact were investigated by X-ray photoelectron spectroscopy (bonding), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Surface and sub-surface structural modification of the coating and composition of the transferred tribolayer are discussed in detail. High friction in humid air was attributed to the absence of a well-ordered WS2 sliding interface. On the other hand, the existence of such an interface explained the very low friction observed in dry air. PMID:23285640

  17. Complex frictional analysis of self-lubricant W-S-C/Cr coating.

    PubMed

    Polcar, Tomas; Gustavsson, Fredrik; Thersleff, Thomas; Jacobson, Staffan; Cavaleiro, Albano

    2012-01-01

    Transition metal dichalcogenides belong to one of the most developed classes of materials for solid lubrication. However, one of the main drawbacks of most of the self-lubricating coatings is their low load-bearing capacity, particularly in terrestrial atmospheres. In our previous work, alloying thin films based on tungsten disulfide with non-metallic interstitial elements, such as carbon or nitrogen, has been studied in order to improve tribological performance in different environments. Excellent results were reached with the deposited coatings hardness, in some cases, more than one order of magnitude higher than single W-S films. In this work, W-S-C films were deposited with increasing Cr contents by co-sputtering chromium and composite WS2-C and targets. Two films were prepared with approx. 7 and 13 at.% of Cr. Alloying with chromium led to dense films with amorphous microstructure; the hardness and adhesion was improved. Sliding tests were carried out in dry and humid air using a pin-on-disc tribometer with 100Cr6 steel balls as a counterpart. To analyse the sliding process, the surfaces in the contact were investigated by X-ray photoelectron spectroscopy (bonding), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Surface and sub-surface structural modification of the coating and composition of the transferred tribolayer are discussed in detail. High friction in humid air was attributed to the absence of a well-ordered WS2 sliding interface. On the other hand, the existence of such an interface explained the very low friction observed in dry air.

  18. Top-of-Rail lubricant

    SciTech Connect

    Alzoubi, M. F.; Fenske, G. R.; Erck, R. A.; Boparai, A. S.

    2000-07-14

    Analysis of the volatile and semivolatile fractions collected after use of the TOR lubricant indicated that other than contaminants in the collection laboratory, no compounds on the EPA's Target Compound Lists (Tables 2 and 5) were detected in these fractions. The data of these qualitative analyses, given in the various tables in the text, indicate only the relative amounts of the tentatively identified compounds. The authors recommend that quantitative analysis be performed on the volatile and semivolatile fractions to allow confirmation of the tentatively identified compounds and to obtain absolute amounts of the detected compounds. Additionally, the semivolatile fraction should be analyzed by liquid chromatography/mass spectrometry to identify compounds that are not chromatographable under the temperature program used for determination of semivolatile compounds. Introducing the top-of-rail (TOR) lubricant into the wheel/rail interface results in a reduction of almost 60% of lateral friction force over the forces encountered under dry conditions. This reveals good potential for energy savings, as well as wear reduction, for railroad companies. In TOR lubrication, an increase in the angle of attack and axle load results in increased lateral friction and rate of lubricant consumption. The most efficient TOR lubricant quantity to be used in the wheel/rail interface must be calculated precisely according to the number of cars, axle loads, train speed, and angle of attack.

  19. Study on a Miniature Mixed-gases Joule-Thomson Cooler Driven by an Oil-lubricated Mini-compressor for 120 K Temperature Ranges

    NASA Astrophysics Data System (ADS)

    Gong, M. Q.; Wu, J. F.; Yan, B.; Zou, X.; Zhuang, X. R.; Hu, Q. G.

    In this paper, a miniature J-T cooler using multicomponent mixtures was developed and tested, in which an oil-lubricated mini-compressor was used. Experimental tests on the performance of the miniature J-T cooler were carried out with two kinds of recuperative heat exchangers. One is a shell-and-tube heat exchanger, and the other is a plate-fin type recuperative heat exchanger with whereas a micro-channel configuration fabricated by the wire-electrode cutting method. The former one gave a no-load minimum temperature of 140 K, while the later one showsbetter performance. No-load minimum temperature of 110 K and about 4 W cooling capacity at 118 K were achieved with the plate-fin micro J-T cooler. Such miniature J-T coolers driven by oil-lubricated mini-compressors show good prospects in many applications.

  20. Analysis of Human Rotavirus Mixed Electropherotypes

    PubMed Central

    Spencer, Eugenio G.; Avendaño, Luis F.; García, Bernardo I.

    1983-01-01

    Mixed human rotavirus electropherotypes were detected in stool samples from patients with acute gastroenteritis in Santiago, Chile. These electropherotypes accounted for 10% of 149 samples studied. The finding of extra RNA fragments with respect to the regular 11 genome segments suggests the possibility of simultaneous or sequential infection by more than one electropherotype in a single diarrhea event or occurrence of modification in the length of the RNA segments during an infection. These possibilities arose from gel electrophoretic analysis of unique and sequential samples of human rotavirus genome RNA. Images PMID:6299944

  1. Lubrication with solids.

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Johnson, R. L.

    1972-01-01

    Brief discussion of the historical background, variety range, chemistry, physics, and other properties of solid lubricants, and review of their current uses. The widespread use of solid lubricants did not occur until about 1947. At present, they are the object of such interest that a special international conference on their subject was held in 1971. They are used at temperatures beyond the useful range of conventional lubricating oils and greases. Their low volatility provides them with the capability of functioning effectively in vacuum and invites their use in space applications. Their high load carrying ability makes them useful with heavily loaded components. Solid lubricants, however, do lack some of the desirable properties of conventional lubricants. Unlike oils and greases, which have fluidity and can continuously be carried back into contact with lubricated surfaces, solid lubricants, because of their immobility, have finite lives. Also, oils and greases can carry away frictional heat from contacting surfaces, while solid lubricants cannot.

  2. Solid Lubricant For Alumina

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Pepper, Stephen V.; Honecy, Frank S.

    1993-01-01

    Outer layer of silver lubricates, while intermediate layer of titanium ensures adhesion. Lubricating outer films of silver deposited on thin intermediate films of titanium on alumina substrates found to reduce sliding friction and wear. Films provide effective lubrication for ceramic seals, bearings, and other hot sliding components in advanced high-temperature engines.

  3. Numerical analysis of micro-/nanoscale gas-film lubrication of sliding surface with complicated structure

    SciTech Connect

    Kawagoe, Yoshiaki; Isono, Susumu; Takeno, Takanori; Yonemura, Shigeru; Takagi, Toshiyuki; Miki, Hiroyuki

    2014-12-09

    It has been reported that the friction between a partially polished diamond-coated surface and a metal surface was drastically reduced to zero when they are slid at a few m/s. Since the sliding was noiseless, it seems that the diamond-coated surface was levitated over the counter surface and the sliding mechanism was the gas film lubrication. Recently, the mechanism of levitation of a slider with a micro/nanoscale surface structure on a rotating disk was theoretically clarified [S. Yonemura et al., Tribol. Lett., (2014), doi:10.1007/s11249-014-0368-2]. Probably, the partially polished diamond-coated surface may be levitated by high gas pressure generated by the micro/nanoscale surface structure on it. In this study, in order to verify our deduction, we performed numerical simulations of sliding of partially polished diamond-coated surface by reproducing its complicated surface structure using the data measured by an atomic force microscope (AFM). As a result, we obtained the lift force which is large enough to levitate the slider used in the experiment.

  4. [Identification of automotive lubricants and other heavy oils by isotachophoresis].

    PubMed

    Ishizawa, F; Misawa, S

    1989-06-01

    Automotive lubricants were analysed by isotachophoresis for the purpose of identification of lubricants and suspected stains adhered to victims in traffic accidents. As the results, it was found that each lubricant showed a characteristic isotachophreogram even if they were manufactured by the same maker, and that the isotachopherogram of the lubricant changed in proportion to the running distance of an automobile. Each lubricant had its own changing rate. Moreover, A, B, C heavy oils, asphalt, soy sauce and sauce, which apparently resembled lubricants when they adhered to victims, were analysed with this method. They were found to be clearly different from lubricants in isotachopherogram and they could be discriminated from lubricants. Therefore, it was found that lubricants could be easily identified or discriminated from other lubricants such as engine oils, gear oils and other oils by comparing their isotachopherograms obtained with this method in a short time. It was, however, difficult to suggest the maker of a lubricant from isotachopherogram. We conclude from these observations that isotachophoresis method is useful for the analysis of lubricants in case of traffic accidents.

  5. 3D Two-way coupled TEHD analysis on the lubricating characteristics of thrust bearings in pump-turbine units by combining CFD and FEA

    NASA Astrophysics Data System (ADS)

    Zhai, Liming; Luo, Yongyao; Wang, Zhengwei; Liu, Xin

    2016-01-01

    The thermal elastic hydro dynamic (TEHD) lubrication analysis for the thrust bearing is usually conducted by combining Reynolds equation with finite element analysis (FEA). But it is still a problem to conduct the computation by combining computational fluid dynamics (CFD) and FEA which can simulate the TEHD more accurately. In this paper, by using both direct and separate coupled solutions together, steady TEHD lubrication considering the viscosity-temperature effect for a bidirectional thrust bearing in a pump-turbine unit is simulated combining a 3D CFD model for the oil film with a 3D FEA model for the pad and mirror plate. Cyclic symmetry condition is used in the oil film flow as more reasonable boundary conditions which avoids the oil temperature assumption at the leading and trailing edge. Deformations of the pad and mirror plate are predicted and discussed as well as the distributions of oil film thickness, pressure, temperature. The predicted temperature shows good agreement with measurements, while the pressure shows a reasonable distribution comparing with previous studies. Further analysis of the three-coupled-field reveals the reason of the high pressure and high temperature generated in the film. Finally, the influence of rotational speed of the mirror plate on the lubrication characteristics is illustrated which shows the thrust load should be balanced against the oil film temperature and pressure in optimized designs. This research proposes a thrust bearing computation method by combining CFD and FEA which can do the TEHD analysis more accurately.

  6. The O-glycomap of Lubricin, a Novel Mucin Responsible for Joint Lubrication, Identified by Site-specific Glycopeptide Analysis*

    PubMed Central

    Ali, Liaqat; Flowers, Sarah A.; Jin, Chunsheng; Bennet, Eric Paul; Ekwall, Anna-Karin H.; Karlsson, Niclas G.

    2014-01-01

    The lubricative, heavily glycosylated mucin-like synovial glycoprotein lubricin has previously been observed to contain glycosylation changes related to rheumatoid and osteoarthritis. Thus, a site-specific investigation of the glycosylation of lubricin was undertaken, in order to further understand the pathological mechanisms involved in these diseases. Lubricin contains an serine/threonine/proline (STP)-rich domain composed of imperfect tandem repeats (EPAPTTPK), the target for O-glycosylation. In this study, using a liquid chromatography–tandem mass spectrometry approach, employing both collision-induced and electron-transfer dissociation fragmentation methods, we identified 185 O-glycopeptides within the STP-rich domain of human synovial lubricin. This showed that adjacent threonine residues within the central STP-rich region could be simultaneously and/or individually glycosylated. In addition to core 1 structures responsible for biolubrication, core 2 O-glycopeptides were also identified, indicating that lubricin glycosylation may have other roles. Investigation of the expression of polypeptide N-acetylgalactosaminyltransferase genes was carried out using cultured primary fibroblast-like synoviocytes, a cell type that expresses lubricin in vivo. This analysis showed high mRNA expression levels of the less understood polypeptide N-acetylgalactosaminyltransferase 15 and 5 in addition to the ubiquitously expressed polypeptide N-acetylgalactosaminyltransferase 1 and 2 genes. This suggests that there is a unique combination of transferase genes important for the O-glycosylation of lubricin. The site-specific glycopeptide analysis covered 82% of the protein sequence and showed that lubricin glycosylation displays both micro- and macroheterogeneity. The density of glycosylation was shown to be high: 168 sites of O-glycosylation, predominately sialylated, were identified. These glycosylation sites were focused in the central STP-rich region, giving the domain a

  7. The O-glycomap of lubricin, a novel mucin responsible for joint lubrication, identified by site-specific glycopeptide analysis.

    PubMed

    Ali, Liaqat; Flowers, Sarah A; Jin, Chunsheng; Bennet, Eric Paul; Ekwall, Anna-Karin H; Karlsson, Niclas G

    2014-12-01

    The lubricative, heavily glycosylated mucin-like synovial glycoprotein lubricin has previously been observed to contain glycosylation changes related to rheumatoid and osteoarthritis. Thus, a site-specific investigation of the glycosylation of lubricin was undertaken, in order to further understand the pathological mechanisms involved in these diseases. Lubricin contains an serine/threonine/proline (STP)-rich domain composed of imperfect tandem repeats (EPAPTTPK), the target for O-glycosylation. In this study, using a liquid chromatography-tandem mass spectrometry approach, employing both collision-induced and electron-transfer dissociation fragmentation methods, we identified 185 O-glycopeptides within the STP-rich domain of human synovial lubricin. This showed that adjacent threonine residues within the central STP-rich region could be simultaneously and/or individually glycosylated. In addition to core 1 structures responsible for biolubrication, core 2 O-glycopeptides were also identified, indicating that lubricin glycosylation may have other roles. Investigation of the expression of polypeptide N-acetylgalactosaminyltransferase genes was carried out using cultured primary fibroblast-like synoviocytes, a cell type that expresses lubricin in vivo. This analysis showed high mRNA expression levels of the less understood polypeptide N-acetylgalactosaminyltransferase 15 and 5 in addition to the ubiquitously expressed polypeptide N-acetylgalactosaminyltransferase 1 and 2 genes. This suggests that there is a unique combination of transferase genes important for the O-glycosylation of lubricin. The site-specific glycopeptide analysis covered 82% of the protein sequence and showed that lubricin glycosylation displays both micro- and macroheterogeneity. The density of glycosylation was shown to be high: 168 sites of O-glycosylation, predominately sialylated, were identified. These glycosylation sites were focused in the central STP-rich region, giving the domain a

  8. Lubricant rheology applied to elastohydrodynamic lubrication

    NASA Technical Reports Server (NTRS)

    Winer, W. O.; Sanborn, D. M.

    1977-01-01

    Viscosity measurements in a high pressure rheometer, elastohydrodynamic simulator studies (including the development of a temperature measuring technique), and analytical fluid modeling for elastohydrodynamic contacts are described. The more recent research which is described concerns infrared temperature measurements in elastohydrodynamic contacts and the exploration of the glassy state of lubricants. A correlation, of engineering significance, was made between transient surface temperature measurements and surface roughness profiles. Measurements of glass transitions of lubricants and the study of the effect of rate processes on materials lead to the conclusion that typical lubricants go into the glassy state as they pass through the contact region of typical elastohydrodynamic contacts.

  9. Tolerance analysis of a micro-optical detection system for on-line monitoring of lubricant oils

    NASA Astrophysics Data System (ADS)

    Van Overmeire, S.; Ottevaere, H.; Mignani, A. G.; Ciaccheri, L.; Desmet, G.; Thienpont, H.

    2010-10-01

    We present a functional prototype of a micro-optical detection unit for both absorbance and laser-induced fluorescence analysis in fused silica capillaries. Absorbance detection allows concentration measurements ranging from 0.6 µM to 12 mM, whereas fluorescence detection enables concentration measurements from 6 pM up to 0.6 mM. We make use of non-sequential optical ray tracing simulations combined with statistical design methodology to perform a complete tolerance analysis for manufacturability and we demonstrate experimentally that the efficiency of the system is insensitive to reasonable misalignment and fabrication errors of its building blocks. The possibility of using standard fabrication techniques to prototype and replicate this miniaturized plastic detection system, as well as its wide measurement range make it a good candidate for applications where low-cost and portable systems are needed to measure small volumes of liquid samples with low-level concentrations. As an example we demonstrate the use of the system for the optical characterization and differentiation of nanoliter volumes of lubricant oils.

  10. Chemical and thermal stability of refrigerant-lubricant mixtures with metals

    SciTech Connect

    Huttenlocher, D.F.

    1992-07-10

    This report presents completed sealed tube stability test results for the following eight refrigerant/lubricant mixtures: R-22/mineral oil; R-124/alkylbenzene; R-134a/pentaerythritol (PE) ester (mixed acid); R- 134a/PE (branched acid); R-134a/ PE (100 cSt viscosity); R- 142b/alkylbenzene; R-143a/ PE (branched acid); R-152a/alkylbenzene. Partial results are shown for an additional eight refrigerant-lubricant mixtures. Though work is in progress, no data are available at this point in time for the five remaining test mixtures. Reported are: visual observations on aged sealed tubes, gas chromatographic analyses on the vapor phase contents of the tubes, chloride ion contents of HCFC containing mixtures or fluoride ion contents of HFC mixtures, and total acid number values and infrared analysis results for mixtures containing ester lubricants.

  11. Tribology and energy efficiency: from molecules to lubricated contacts to complete machines.

    PubMed

    Taylor, Robert Ian

    2012-01-01

    The impact of lubricants on energy efficiency is considered. Molecular details of base oils used in lubricants can have a great impact on the lubricant's physical properties which will affect the energy efficiency performance of a lubricant. In addition, molecular details of lubricant additives can result in significant differences in measured friction coefficients for machine elements operating in the mixed/boundary lubrication regime. In single machine elements, these differences will result in lower friction losses, and for complete systems (such as cars, trucks, hydraulic circuits, industrial gearboxes etc.) lower fuel consumption or lower electricity consumption can result.

  12. Experimental study and analysis of lubricants dispersed with nano Cu and TiO2 in a four-stroke two wheeler

    PubMed Central

    2011-01-01

    The present investigation summarizes detailed experimental studies with standard lubricants of commercial quality known as Racer-4 of Hindustan Petroleum Corporation (India) dispersed with different mass concentrations of nanoparticles of Cu and TiO2. The test bench is fabricated with a four-stroke Hero-Honda motorbike hydraulically loaded at the rear wheel with proper instrumentation to record the fuel consumption, the load on the rear wheel, and the linear velocity. The whole range of data obtained on a stationery bike is subjected to regression analysis to arrive at various relationships between fuel consumption as a function of brake power, linear velocity, and percentage mass concentration of nanoparticles in the lubricant. The empirical relation correlates with the observed data with reasonable accuracy. Further, extension of the analysis by developing a mathematical model has revealed a definite improvement in brake thermal efficiency which ultimately affects the fuel economy by diminishing frictional power in the system with the introduction of nanoparticles into the lubricant. The performance of the engine seems to be better with nano Cu-Racer-4 combination than the one with nano TiO2. PMID:21711765

  13. Experimental study and analysis of lubricants dispersed with nano Cu and TiO2 in a four-stroke two wheeler

    NASA Astrophysics Data System (ADS)

    Sarma, Pullela K.; Srinivas, Vadapalli; Rao, Vedula Dharma; Kumar, Ayyagari Kiran

    2011-12-01

    The present investigation summarizes detailed experimental studies with standard lubricants of commercial quality known as Racer-4 of Hindustan Petroleum Corporation (India) dispersed with different mass concentrations of nanoparticles of Cu and TiO2. The test bench is fabricated with a four-stroke Hero-Honda motorbike hydraulically loaded at the rear wheel with proper instrumentation to record the fuel consumption, the load on the rear wheel, and the linear velocity. The whole range of data obtained on a stationery bike is subjected to regression analysis to arrive at various relationships between fuel consumption as a function of brake power, linear velocity, and percentage mass concentration of nanoparticles in the lubricant. The empirical relation correlates with the observed data with reasonable accuracy. Further, extension of the analysis by developing a mathematical model has revealed a definite improvement in brake thermal efficiency which ultimately affects the fuel economy by diminishing frictional power in the system with the introduction of nanoparticles into the lubricant. The performance of the engine seems to be better with nano Cu-Racer-4 combination than the one with nano TiO2.

  14. Experimental study and analysis of lubricants dispersed with nano Cu and TiO2 in a four-stroke two wheeler.

    PubMed

    Sarma, Pullela K; Srinivas, Vadapalli; Rao, Vedula Dharma; Kumar, Ayyagari Kiran

    2011-01-01

    The present investigation summarizes detailed experimental studies with standard lubricants of commercial quality known as Racer-4 of Hindustan Petroleum Corporation (India) dispersed with different mass concentrations of nanoparticles of Cu and TiO2. The test bench is fabricated with a four-stroke Hero-Honda motorbike hydraulically loaded at the rear wheel with proper instrumentation to record the fuel consumption, the load on the rear wheel, and the linear velocity. The whole range of data obtained on a stationery bike is subjected to regression analysis to arrive at various relationships between fuel consumption as a function of brake power, linear velocity, and percentage mass concentration of nanoparticles in the lubricant. The empirical relation correlates with the observed data with reasonable accuracy. Further, extension of the analysis by developing a mathematical model has revealed a definite improvement in brake thermal efficiency which ultimately affects the fuel economy by diminishing frictional power in the system with the introduction of nanoparticles into the lubricant. The performance of the engine seems to be better with nano Cu-Racer-4 combination than the one with nano TiO2. PMID:21711765

  15. Lubrication of Nitinol 60

    NASA Technical Reports Server (NTRS)

    Pepper, Stephen V.; DellaCorte, Christopher; Glennon, Glenn

    2010-01-01

    The mechanical properties of Nitinol 60, 60 wt% Ni, 40 wt% Ti (55 at.% Ni, 45 at.% Ti) are sufficiently attractive to warrant its consideration as a lubricated triboelement. Triboelements are always run lubricated. The ability to lubricate Nitinol 60 by the oils usually used on spacecraft mechanisms--Pennzane 2001A, Krytox 143AC and Castrol 815Z--was experimentally determined. These oils were run in the boundary lubrication regime for Nitinol 60 balls running against Nitinol 60 counterfaces in the vacuum spiral orbit tribometer. Test results consisting of the coefficient of friction versus time (friction traces) and relative degradation rates of the oils are presented. Contrary to the inability to successfully lubricate other metal alloys with high titanium content, it was found that Nitinol 60 is able to be lubricated by these oils. Overall, the results presented here indicate that Nitinol 60 is a credible candidate material for bearing applications.

  16. Boundary lubrication: Revisited

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.

    1982-01-01

    A review of the various lubrication regimes, with particular, emphasis on boundary lubrication, is presented. The types of wear debris and extent of surface damage is illustrated for each regime. The role of boundary surface films along with their modes of formation and important physical properties are discussed. In addition, the effects of various operating parameters on friction and wear in the boundary lubrication regime are considered.

  17. Fundamentals of fluid lubrication

    NASA Technical Reports Server (NTRS)

    Hamrock, Bernard J.

    1991-01-01

    The aim is to coordinate the topics of design, engineering dynamics, and fluid dynamics in order to aid researchers in the area of fluid film lubrication. The lubrication principles that are covered can serve as a basis for the engineering design of machine elements. The fundamentals of fluid film lubrication are presented clearly so that students that use the book will have confidence in their ability to apply these principles to a wide range of lubrication situations. Some guidance on applying these fundamentals to the solution of engineering problems is also provided.

  18. DIESEL FUEL LUBRICATION

    SciTech Connect

    Qu, Jun

    2012-01-01

    The diesel fuel injector and pump systems contain many sliding interfaces that rely for lubrication upon the fuels. The combination of the poor fuel lubricity and extremely tight geometric clearance between the plunger and bore makes the diesel fuel injector vulnerable to scuffing damage that severely limits the engine life. In order to meet the upcoming stricter diesel emission regulations and higher engine efficiency requirements, further fuel refinements that will result in even lower fuel lubricity due to the removal of essential lubricating compounds, more stringent operation conditions, and tighter geometric clearances are needed. These are expected to increase the scuffing and wear vulnerability of the diesel fuel injection and pump systems. In this chapter, two approaches are discussed to address this issue: (1) increasing fuel lubricity by introducing effective lubricity additives or alternative fuels, such as biodiesel, and (2) improving the fuel injector scuffing-resistance by using advanced materials and/or surface engineering processes. The developing status of the fuel modification approach is reviewed to cover topics including fuel lubricity origins, lubricity improvers, alternative fuels, and standard fuel lubricity tests. The discussion of the materials approach is focused on the methodology development for detection of the onset of scuffing and evaluation of the material scuffing characteristics.

  19. Lubrication of Machine Elements

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.

    1984-01-01

    The understanding of hydrodynamic lubrication began with the classical experiments of Tower and Petrov. Reynolds used a reduced form of the Navier-Stokes equations and the continuity equation to generate a second order differential equation for the pressure in the narrow, converging gap of a bearing contact. Such a pressure enables a load to be transmitted between the surfaces with very low friction since the surfaces are completely separated by a film of fluid. In such a situation it is the physical properties of the lubricant, notably the dynamic viscosity, that dictate the behavior of the contact. The understanding of boundary lubrication is normally attributed to Hardy and Doubleday. In boundary lubrication it is the physical and chemical properties of thin films of molecular proportions and the surfaces to which they are attached that determine contact behavior. The lubricant viscosity is not an influential parameter. Research is devoted to a better understanding and more precise definition of other lubrication regimes between these extremes. One such regime, elastohydrodynamic lubrication, occurs in nonconformal contacts, where the pressures are high and the bearing surfaces deform elastically. In this situation the viscosity of the lubricant may raise considerably, and this further assists the formation of an effective fluid film. The science of these three lubrication regimes (hydrodynamic, elastohydrodynamic, and boundary) are described and the manner in which this science is used in the design of machine elements is examined.

  20. Theoretical analysis of mixing in liquid clouds - Part 3: Inhomogeneous mixing

    NASA Astrophysics Data System (ADS)

    Pinsky, M.; Khain, A.; Korolev, A.

    2015-11-01

    An idealized model of time-dependent mixing between cloud and non-cloud volumes is analyzed. Initial droplet size distribution (DSD) in cloud volume is assumed to be monodisperse. Both analytical investigation and parcel model investigation are used to study mixing processes and solve diffusion-evaporation equations. It is shown that the evolution of microphysical variables and the final equilibrium stage are unambiguously determined by two non-dimensional parameters. The first parameter, R, which is proportional to the ratio of the saturation deficit to the liquid water content in a cloud volume, determines whether the equilibrium stage is reached at 100 % relative humidity, or, rather, leads to a full evaporation of cloud droplets. The second parameter, Da, is the Damkölher number, which is equal to the ratio of the characteristic mixing time and phase relaxation time. This parameter (together with parameter R) determines whether mixing takes place according to a homogeneous or an inhomogeneous scenario. An analysis of the results obtained within a wide range of parameters R and Da is presented. It is shown that there is no pure homogeneous mixing, since the first stage of mixing is always inhomogeneous. Turbulent mixing between different volumes always starts as inhomogeneous and the mixing type can change during the mixing process. At any values of governing parameters, mixing leads to the formation of a tail of small droplets in the DSD and therefore to DSD broadening. The broadening depends onDa and the final DSD dispersion can be as large as 0.2 at large Da. The total duration of the mixing process varies from several to one hundred phase relaxation times, depending on R and Da. Delimitation between the types of mixing on the Da-R plane is carried out. The definitions of homogeneous and inhomogeneous mixings are reconsidered and clarified. The paper also compares the results of the current study with those obtained with classical mixing concepts.

  1. Ocean Spray Lubricates Winds

    ERIC Educational Resources Information Center

    Journal of College Science Teaching, 2005

    2005-01-01

    According to a new study by two University of California, Berkeley, mathematicians and their Russian colleague, the water droplets kicked up by rough seas serve to lubricate the swirling winds of hurricanes and cyclones, letting them build to speeds approaching 200 miles per hour. Without the lubricating effect of the spray, the mathematicians…

  2. Sporting Good Lubricants

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Sun Coast Chemicals was originally contracted by Lockheed Martin Space Operations to formulate a spray lubricant free of environmental drawbacks for the Mobile Launch Platform used to haul the Space Shuttle from the Kennedy Space Center Vehicle Assembly Building to a launch pad. From this work, Sun Coast introduced Train Track Lubricant, Penetrating Spray Lube, and Biodegradable Hydraulic Fluid. Based on the original lubricant work, two more products have also been introduced. First, the X-1R Super Gun Cleaner and Lubricant protects guns from rust and corrosion caused by environmental conditions. Second, the X-1R Tackle Pack, endorsed by both fresh and saltwater guides and certain reel manufacturers, penetrates, cleans, reduces friction, lubricates, and provides extra protection against rust and corrosion.

  3. Formulation of Automotive Lubricants

    NASA Astrophysics Data System (ADS)

    Atkinson, D.; Brown, A. J.; Jilbert, D.; Lamb, G.

    The formulation of lubricants for current light- and heavy-duty vehicles (passenger cars and trucks) and also motorcycles/small engines is described in terms of engine types and meeting European, US and Japanese emission control requirements. Trends in the formulation of lubricants are discussed and the importance of high and low 'SAPS' for future developments emphasised. Specification and evaluation of lubricant performance for light-vehicle gasoline and diesel, and also heavy-duty diesel engines are described. Emphasis is given to diesel engine cleanliness by soot and deposit control and the effect of emission controls on lubricant formulation. The lubricant requirements for motorcycle and small engines, primarily two-stroke cycle, and their specifications are described.

  4. Global analysis of fermion mixing with exotics

    NASA Technical Reports Server (NTRS)

    Nardi, Enrico; Roulet, Esteban; Tommasini, Daniele

    1991-01-01

    The limits are analyzed on deviation of the lepton and quark weak-couplings from their standard model values in a general class of models where the known fermions are allowed to mix with new heavy particles with exotic SU(2) x U(1) quantum number assignments (left-handed singlets or right-handed doublets). These mixings appear in many extensions of the electroweak theory such as models with mirror fermions, E(sub 6) models, etc. The results update previous analyses and improve considerably the existing bounds.

  5. Microfog lubrication for aircraft engine bearings

    NASA Technical Reports Server (NTRS)

    Rosenlieb, J. W.

    1976-01-01

    An analysis and system study was performed to provide design information regarding lubricant and coolant flow rates and flow paths for effective utilization of the lubricant and coolant in a once through bearing oil mist (microfog) and coolant air system. Both static and dynamic tests were performed. Static tests were executed to evaluate and calibrate the mist supply system. A total of thirteen dynamic step speed bearing tests were performed using four different lubricants and several different mist and air supply configurations. The most effective configuration consisted of supplying the mist and the major portion of the cooling air axially through the bearing. The results of these tests have shown the feasibility of using a once through oil mist and cooling air system to lubricate and cool a high speed, high temperature aircraft engine mainshaft bearing.

  6. Analysis and design of a cantilever-mounted resilient-pad gas-lubricated thrust bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    A thrust bearing consisting of pads mounted on resilient, metallic, cantilever beams is described and analyzed. Compliance and stiffness of the bearing assembly are discussed, and the effects of bearing design parameters on performance are shown. After the general analysis, a design example is presented for a flat sector-shaped gas bearing. A special case where zero axial movement of the runner can be obtained is pointed out.

  7. Tribometer for Lubrication Studies in Vacuum

    NASA Technical Reports Server (NTRS)

    Pepper, Stephen V.

    1998-01-01

    The NASA Lewis Research Center has developed a new way to evaluate the liquid lubricants used in ball bearings in space mechanisms. For this evaluation, a liquid lubricant is exercised in the rolling contact vacuum tribometer shown in the photo. This tribometer, which is essentially a thrust bearing with three balls and flat races, has contact stresses similar to those in a typical preloaded, angular contact ball bearing. The rotating top plate drives the balls in an outward-winding spiral orbit instead of a circular path. Upon contact with the "guide plate," the balls are forced back to their initial smaller orbit radius; they then repeat this spiral orbit thousands of times. The orbit rate of the balls is low enough, 2 to 5 rpm, to allow the system to operate in the boundary lubrication regime that is most stressful to the liquid lubricant. This system can determine the friction coefficient, lubricant lifetime, and species evolved from the liquid lubricant by tribodegradation. The lifetime of the lubricant charge is only few micrograms, which is "used up" by degradation during rolling. The friction increases when the lubricant is exhausted. The species evolved by the degrading lubricant are determined by a quadrupole residual gas analyzer that directly views the rotating elements. The flat races (plates) and 0.5-in.-diameter balls are of a configuration and size that permit easy post-test examination by optical and electron microscopy and the full suite of modern surface and thin-film chemical analytical techniques, including infrared and Raman microspectroscopy and x-ray photoelectron spectroscopy. In addition, the simple sphere-on-a-flat-plate geometry allows an easy analysis of the contact stresses at all parts of the ball orbit and an understanding of the frictional energy losses to the lubricant. The analysis showed that when the ball contacts the guide plate, gross sliding occurs between the ball and rotating upper plate as the ball forced back to a smaller

  8. Dairy Equipment Lubrication

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Lake To Lake Dairy Cooperative, Manitowoc, Wisconsin, operates four plants in Wisconsin for processing milk, butter and cheese products from its 1,300 member farms. The large co-op was able to realize substantial savings by using NASA information for improved efficiency in plant maintenance. Under contract to Marshall Space Flight Center, Midwest Research Institute compiled a handbook consolidating information about commercially available lubricants. The handbook details chemical and physical properties, applications, specifications, test procedures and test data for liquid and solid lubricants. Lake To Lake's plant engineer used the handbook to effect savings in maintenance labor and materials costs by reducing the number of lubricants used on certain equipment. Strict U.S. Department of Agriculture and Food and Drug Administration regulations preclude lubrication changes n production equipment, but the co-op's maintenance chief was able to eliminate seven types of lubricants for ancillary equipment, such as compressors and high pressure pumps. Handbook data enabled him to select comparable but les expensive lubricants in the materials consolidation process, and simplified lubrication schedules and procedures. The handbook is in continuing use as a reference source when a new item of equipment is purchased.

  9. Analysis of quality of aviation lubricating oils by means of liquid and gas-liquid chromatography

    SciTech Connect

    Kholostova, G.G.; Bakunin, V.N.; Shimonaev, G.S.

    1987-01-01

    The authors examine the basic methodological aspects of chromatographic analysis of the quality of oils for aircraft gas turbine engines, and certain relationships in oil aging that have been established on this basis. A commercial ester (designated PEE) was selected for investigation of pentaerythritol and C/sub 5/-C/sub 9/ synthetic fatty acids (SFA) which serves as the synthetic base stock for a number of aviation oils. The changes in PEE composition upon oxidation, with or without additives, were evaluated by means of gas-liquid chromatography in a Tsvet-100 chromatograph with a flame ionization detector. The results from examination of the original and oxidized PEE samples by means of gas and liquid chromatography are presented.

  10. X-ray fluorescence analysis of wear metals in used lubricating oils

    NASA Technical Reports Server (NTRS)

    Maddox, W. E.; Kelliher, W. C.

    1986-01-01

    Used oils from several aircraft at NASA's Langley Research Center were analyzed over a three year period using X-ray fluorescence (XRF) and atomic emission spectrometry. The results of both analyses are presented and comparisons are made. Fe and Cu data for oil from four internal combustion engines are provided and XRF and atomic emission spectrometry measurements were found to be in perfect agreement. However, distributions were found in the case of oil from a jet aircraft engine whereby the latter method gave values for total iron concentration in the oil and did not distinguish between suspended particles and oil additives. XRF does not have these particle-size limitations; moreover, it is a faster process. It is concluded that XRF is the preferred method in the construction of a man-portable oil wear analysis instrument.

  11. Quantifying chemical reactions by using mixing analysis.

    PubMed

    Jurado, Anna; Vázquez-Suñé, Enric; Carrera, Jesús; Tubau, Isabel; Pujades, Estanislao

    2015-01-01

    This work is motivated by a sound understanding of the chemical processes that affect the organic pollutants in an urban aquifer. We propose an approach to quantify such processes using mixing calculations. The methodology consists of the following steps: (1) identification of the recharge sources (end-members) and selection of the species (conservative and non-conservative) to be used, (2) identification of the chemical processes and (3) evaluation of mixing ratios including the chemical processes. This methodology has been applied in the Besòs River Delta (NE Barcelona, Spain), where the River Besòs is the main aquifer recharge source. A total number of 51 groundwater samples were collected from July 2007 to May 2010 during four field campaigns. Three river end-members were necessary to explain the temporal variability of the River Besòs: one river end-member is from the wet periods (W1) and two are from dry periods (D1 and D2). This methodology has proved to be useful not only to compute the mixing ratios but also to quantify processes such as calcite and magnesite dissolution, aerobic respiration and denitrification undergone at each observation point.

  12. Driveline Fundamentals and Lubrication

    NASA Astrophysics Data System (ADS)

    Joseph, I.

    The various gear types and automotive transmissions in drive trains are described. The need for automotive differential axle gears is demonstrated. SAE gear lubricant classifications are related to performance specifications. Automatic transmission fluids, ATFs, are described together with agricultural and off-highway fluids. Generic formulations of driveline fluids are discussed in terms of their tribology and performance and also the contribution of various additive classes to that performance. The main functions of manual gearbox, automatic transmission and axle lubricants are described. General trends and emerging technologies in drive train components are discussed in terms of the requirements placed on the lubricant, evolution in transmission technologies and relative market penetration.

  13. Processing and Formulation of Lithium Lubricating Greases

    NASA Astrophysics Data System (ADS)

    Delgado, M. A.; Franco, J. M.; Valencia, C.; Moreno, G.; Gallegos, C.

    2006-05-01

    The effects that soap concentration, base oil viscosity and additives exert on the rheology of lubricating greases have been studied. Also, changes in both microstructure and rheology of lithium lubricating greases during their manufacturing process have been evaluated. With this aim, different lithium lubricating grease formulations were manufactured by modifying the concentration of lithium 12-hydroxystearate, base oil viscosity and processing conditions or using different polymeric additives. The manufacturing process was followed through the mixing rheometry technique by measuring the evolution of torque with processing time, and samples of incipient and finished greases were taken from the stirred tank at different processing times. Rheological (small-amplitude oscillatory shear (SAOS)) and scanning electronic microscopy (SEM) observations were carried out on each sample. The experimental results obtained demonstrate that the values of the linear viscoelasticity functions and the mechanical behaviour of lubricating grease strongly depend on the processing variables and grease composition. Also, it has been found that the structural skeleton (size and shape of the disperse phase particles) is highly influenced by the base oil viscosity. These results have been explained taking into account the balance between the solvency of the thickener in the base oil and the level of entanglements formed by soap fibres, which influence the lubricating grease network.

  14. Analysis of mixing zone length using methane as fuel

    SciTech Connect

    Brasoveanu, D.; Gupta, A.K.

    1998-07-01

    The distributions of pressure, temperature and velocity, and correlation between radial and axial gradients of fuel mass fraction in an axisymmetric combustor are examined. A model for methane-air mixing in non-flammable mixtures, based on the ideal gas law and the equation of continuity, is described. High axial gradients of fuel mass fraction are required to produce a short mixing zone. Results show that high pressures and temperatures reduce the axial gradients of fuel, while high gradients of pressure and temperature can reduce the length of the mixing zone. High radial gradients of fuel mass fraction in conjunction with a large ratio of radial and axial velocity also shorten the mixing. Mixing is enhanced most by velocity divergence and temperature gradients. Analysis of the length of the mixing zone provides guidelines for the development of compact, high intensity, high efficiency and low emission combustors.

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

    NASA Technical Reports Server (NTRS)

    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.

  16. Chemical and thermal stability of refrigerant-lubricant mixtures with metals. Quarterly report, 1 April 1992--30 June 1992

    SciTech Connect

    Huttenlocher, D.F.

    1992-07-10

    This report presents completed sealed tube stability test results for the following eight refrigerant/lubricant mixtures: R-22/mineral oil; R-124/alkylbenzene; R-134a/pentaerythritol (PE) ester (mixed acid); R- 134a/PE (branched acid); R-134a/ PE (100 cSt viscosity); R- 142b/alkylbenzene; R-143a/ PE (branched acid); R-152a/alkylbenzene. Partial results are shown for an additional eight refrigerant-lubricant mixtures. Though work is in progress, no data are available at this point in time for the five remaining test mixtures. Reported are: visual observations on aged sealed tubes, gas chromatographic analyses on the vapor phase contents of the tubes, chloride ion contents of HCFC containing mixtures or fluoride ion contents of HFC mixtures, and total acid number values and infrared analysis results for mixtures containing ester lubricants.

  17. Characterization of Spray Lubricants for the Die Casting Process

    SciTech Connect

    Sabau, Adrian S

    2008-01-01

    During the die casting process, lubricants are sprayed in order to cool the dies and facilitate the ejection of the casting. The cooling effects of the die lubricant were investigated using Thermogravimetric analysis (TGA), heat flux sensors (HFS), and infrared imaging. The evolution of the heat flux and pictures taken using a high speed infrared camera revealed that lubricant application was a transient process. The short time response of the HFS allows the monitoring and data acquisition of the surface temperature and heat flux without additional data processing. A similar set of experiments was performed with deionized water in order to assess the lubricant effect. The high heat flux obtained at 300 C was attributed to the wetting and absorbant properties of the lubricant. Pictures of the spray cone and lubricant flow on the die were also used to explain the heat flux evolution.

  18. Lubrication of Articular Cartilage.

    PubMed

    Jahn, Sabrina; Seror, Jasmine; Klein, Jacob

    2016-07-11

    The major synovial joints such as hips and knees are uniquely efficient tribological systems, able to articulate over a wide range of shear rates with a friction coefficient between the sliding cartilage surfaces as low as 0.001 up to pressures of more than 100 atm. No human-made material can match this. The means by which such surfaces maintain their very low friction has been intensively studied for decades and has been attributed to fluid-film and boundary lubrication. Here, we focus especially on the latter: the reduction of friction by molecular layers at the sliding cartilage surfaces. In particular, we discuss such lubrication in the light of very recent advances in our understanding of boundary effects in aqueous media based on the paradigms of hydration lubrication and of the synergism between different molecular components of the synovial joints (namely hyaluronan, lubricin, and phospholipids) in enabling this lubrication.

  19. Origins of hydration lubrication.

    PubMed

    Ma, Liran; Gaisinskaya-Kipnis, Anastasia; Kampf, Nir; Klein, Jacob

    2015-01-14

    Why is friction in healthy hips and knees so low? Hydration lubrication, according to which hydration shells surrounding charges act as lubricating elements in boundary layers (including those coating cartilage in joints), has been invoked to account for the extremely low sliding friction between surfaces in aqueous media, but not well understood. Here we report the direct determination of energy dissipation within such sheared hydration shells. By trapping hydrated ions in a 0.4-1 nm gap between atomically smooth charged surfaces as they slide past each other, we are able to separate the dissipation modes of the friction and, in particular, identify the viscous losses in the subnanometre hydration shells. Our results shed light on the origins of hydration lubrication, with potential implications both for aqueous boundary lubricants and for biolubrication.

  20. Liquid lubrication in space

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1990-01-01

    The requirement for long-term, reliable operation of aerospace mechanisms has, with a few exceptions, pushed the state of the art in tribology. Space mission life requirements in the early 1960s were generally 6 months to a year. The proposed U.S. space station schedule to be launched in the 1990s must be continuously usable for 10 to 20 years. Liquid lubrication systems are generally used for mission life requirements longer than a year. Although most spacecraft or satellites have reached their required lifetimes without a lubrication-related failure, the application of liquid lubricants in the space environment presents unique challenges. The state of the art of liquid lubrication in space as well as the problems and their solutions are reviewed.

  1. Solid lubrication design methodology

    NASA Technical Reports Server (NTRS)

    Aggarwal, B. B.; Yonushonis, T. M.; Bovenkerk, R. L.

    1984-01-01

    A single element traction rig was used to measure the traction forces at the contact of a ball against a flat disc at room temperature under combined rolling and sliding. The load and speed conditions were selected to match those anticipated for bearing applications in adiabatic diesel engines. The test program showed that the magnitude of traction forces were almost the same for all the lubricants tested; a lubricant should, therefore, be selected on the basis of its ability to prevent wear of the contact surfaces. Traction vs. slide/roll ratio curves were similar to those for liquid lubricants but the traction forces were an order of magnitude higher. The test data was used to derive equations to predict traction force as a function of contact stress and rolling speed. Qualitative design guidelines for solid lubricated concentrated contacts are proposed.

  2. Effect of fullerene containing lubricants on wear resistance of machine components in boundary lubrication

    NASA Astrophysics Data System (ADS)

    Titov, Andriy

    Fullerenes, a new form of carbon nanomaterials, possess unique physical and mechanical properties that make their use as additives to liquid lubricants potentially beneficial. The goal of this study was to investigate the effect of fullerene containing lubricants on wear resistance of steel-bronze couples operating under boundary lubrication conditions. A mathematical model of deformed asperity contact was built to calculate real contact area and real contact pressure. Computer controlled wear friction testing methodology and equipment were designed, developed and implemented for obtaining reliable and objective experimental data. In addition, optical and scanning electron microscopy and standard surface texture analysis were employed. Heavy duty motor oil SAE 10 was modified by admixing fullerenes C60, a fullerene mixture of C60 and C70, fullerene containing soot, and graphite powder. The experiments showed that all of the selected fullerene additives dissolved in liquid lubricants reduce wear of the tested materials. In addition, it was found that despite improvements in wear resistance, the selected modified lubricants did not significantly change friction characteristics. Improvement of wear resistance of contact surfaces operating with fullerene modified lubricants can be explained by the presence of fullerenes in real contact while the liquid lubricant is squeezed out. Fullerenes are considered to function as minute hard particles that do not break down under applied normal force, and tend to separate direct contact of functional surfaces of selected materials.

  3. A Rolling Element Tribometer for the Study of Liquid Lubricants in Vacuum

    NASA Technical Reports Server (NTRS)

    Pepper, Stephen V.; Ebihara, Ben T.; Kingsbury, Edward

    1996-01-01

    A tribometer for the evaluation of liquid lubricants in vacuum is described. This tribometer is essentially a thrust bearing with three balls and flat races having contact stresses and ball motions similar to those in an angular contact ball bearing operating in the boundary lubrication regime. The friction coefficient, lubrication lifetime, and species evolved from the liquid lubricant by tribodegradation can be determined. A complete analysis of the contact stresses and energy dissipation together with experimental evidence supporting the analysis are presented.

  4. Boundary lubrication in vivo.

    PubMed

    Hills, B A

    2000-01-01

    Evidence is reviewed for the concept that the body employs essentially the same lubrication system in many sites in the body where tissues slide over each other with such ease. This system consists of fluid adjacent to surfaces coated with an oligolamellar lining of surface-active phospholipid (SAPL) acting as a back-up boundary lubricant wherever the fluid film fails to support the load--a likely event at physiological velocities. Particular attention is paid to the load-bearing joints, where the issue of identifying the vital active ingredient in synovial fluid is reviewed, coming down--perhaps predictably--in favour of SAPL. It is also explained how Lubricin and hyaluronic acid (HA) could have 'carrier' functions for the highly insoluble SAPL, while HA has good wetting properties needed to promote hydrodynamic lubrication of a very hydrophobic articular surface by an aqueous fluid wherever the load permits. In addition to friction and wear, release is included as another major role of boundary lubricants, especially relevant in environments where proteins are found, many having adhesive properties. The discussion is extended to a mention of the lubrication of prosthetic implants and to disease states where a deficiency of boundary lubricant is implicated, particular attention being paid to osteoarthritis.

  5. Lubrication by glycoprotein brushes.

    NASA Astrophysics Data System (ADS)

    Zappone, Bruno; Ruths, Marina; Greene, George W.; Israelachvili, Jacob

    2006-03-01

    Grafted polyelectrolyte brushes show excellent lubricating properties under water and have been proposed as a model to study boundary lubrication in biological system. Lubricin, a glycoprotein of the synovial fluid, is considered the major boundary lubricant of articular joints. Using the Surface Force Apparatus, we have measured normal and friction forces between model surfaces (negatively charged mica, positively charged poly-lysine and aminothiol, hydrophobic alkanethiol) bearing adsorbed layers of lubricin. Lubricin layers acts like a versatile anti-adhesive, adsorbing on all the surfaces considered and creating a repulsion similar to the force between end-grafted polymer brushes. Analogies with polymer brushes also appear from bridging experiment, where proteins molecules are end-adsorbed on two opposing surfaces at the same time. Lubricin `brushes' show good lubricating ability at low applied pressures (P<0.5MPa), especially on negatively charged surfaces like mica. At higher load, the adsorbed layers wears and fails lubricating the surfaces, while still protecting the underlying substrate from wearing. Lubricin might thus be a first example of biological polyelectrolytes providing `brush-like' lubrication and wear-protection.

  6. Auxiliary lubrication pump apparatus

    SciTech Connect

    Glesmann, H.C.; Thomas, R.G.

    1987-02-10

    This patent describes an auxiliary lubrication pump apparatus for use with a towing vehicle having an engine switch, a battery, and an interior compartment, and a towed vehicle having an automatic transmission which requires forced lubrication while being towed. The apparatus comprises: (a) a lubrication pump; (b) a transmission to pump hose connected between the automatic transmission and the lubrication pump; (c) a valve having at least one signal output and two inputs: (d) a hose means for connecting an output of the lubrication pump to one of the inputs of the valve; (e) a first outflow hose for connecting the automatic transmission to another input of the valve; (f) a second output hose for connecting the output of the valve to the automatic transmission; (g) pressure sensing means positioned to sense pressure as regards the second outflow hose; and (h) control means responsive to the pressure sensing means and having switch means for providing electricity to the lubrication pump and to provide an alarm whenever the control means detects through the pressure sensing means that inadequate pressure exists.

  7. Methods to improve lubricity of fuels and lubricants

    SciTech Connect

    Erdemir, Ali

    2009-06-16

    A method for providing lubricity in fuels and lubricants includes adding a boron compound to a fuel or lubricant to provide a boron-containing fuel or lubricant. The fuel or lubricant may contain a boron compound at a concentration between about 30 ppm and about 3,000 ppm and a sulfur concentration of less than about 500 ppm. A method of powering an engine to minimize wear, by burning a fuel containing boron compounds. The boron compounds include compound that provide boric acid and/or BO.sub.3 ions or monomers to the fuel or lubricant.

  8. Biofluid lubrication for artificial joints

    NASA Astrophysics Data System (ADS)

    Pendleton, Alice Mae

    This research investigated biofluid lubrication related to artificial joints using tribological and rheological approaches. Biofluids studied here represent two categories of fluids, base fluids and nanostructured biofluids. Base fluids were studied through comparison of synthetic fluids (simulated body fluid and hyaluronic acid) as well as natural biofluids (from dogs, horses, and humans) in terms of viscosity and fluid shear stress. The nano-structured biofluids were formed using molecules having well-defined shapes. Understanding nano-structured biofluids leads to new ways of design and synthesis of biofluids that are beneficial for artificial joint performance. Experimental approaches were utilized in the present research. This includes basic analysis of biofluids' property, such as viscosity, fluid shear stress, and shear rate using rheological experiments. Tribological investigation and surface characterization were conducted in order to understand effects of molecular and nanostructures on fluid lubrication. Workpiece surface structure and wear mechanisms were investigated using a scanning electron microscope and a transmission electron microscope. The surface topography was examined using a profilometer. The results demonstrated that with the adding of solid additives, such as crown ether or fullerene acted as rough as the other solids in the 3-body wear systems. In addition, the fullerene supplied low friction and low wear, which designates the lubrication purpose of this particular particle system. This dissertation is constructed of six chapters. The first chapter is an introduction to body fluids, as mentioned earlier. After Chapter II, it examines the motivation and approach of the present research, Chapter III discusses the experimental approaches, including materials, experimental setup, and conditions. In Chapter IV, lubrication properties of various fluids are discussed. The tribological properties and performance nanostructured biofluids are

  9. Mixing model analysis of telescopic lunar spectra

    NASA Astrophysics Data System (ADS)

    Lucey, Paul G.; Clark, Beth C.; Hawke, B. Ray

    1993-03-01

    We have analyzed very high quality reflectance spectra of the lunar surface from the University of Hawaii lunar spectral data collection using a spectral mixing model. The spectra analyzed are those of 45 mare sites and 75 highland sites. The spectra were selected on the basis of very high signal to noise ratios based on error bars and point to point scatter, and on quality of removal of telluric water bands. The spectral mixing model used 7 components, not all of which were used in each fit. Four of the components were mineral spectra of the orthopyroxene, a clinopyroxene, an olivine and an anorthite, measured at the Brown University's RELAB. All of the minerals were 45-90 micron splits. Lunar soil contains other components which have the effect of reddening and darkening the soil as well as reducing spectral contrast. In addition, lunar soil contains spectral neutral bright material (likely very fine grained feldspar) which serves to reduce spectral contrast and brighten soils. Early attempts to fit many of the spectra pointed out the need for a component which has a very broad smooth absorption feature centered near 1.1 microns. Glass is a good candidate for this component. For the bright component we used a flat reflectance of 70 percent to represent fine grained feldspar. For the 'glass' component we used a telescopic spectrum of a pyroclastic glass present on the Aristarchus plateau which is characterized by a strong smooth band centered at 1.07 microns. In addition to exhibiting the glass band this spectrum is very red and has a low albedo. On the assumption that the dark component and the red component are agglutinates, which is reasonable but not necessarily true, we sought a dark red component. To derive its properties we modelled the spectrum of an Apollo 16 soil (16xxx) and assumed the dark red component to comprise 60 percent of the soil, appropriate to agglutinate abundance in mature soil. We adjusted the albedo and slope of a straight line

  10. Mixing model analysis of telescopic lunar spectra

    NASA Technical Reports Server (NTRS)

    Lucey, Paul G.; Clark, Beth C.; Hawke, B. Ray

    1993-01-01

    We have analyzed very high quality reflectance spectra of the lunar surface from the University of Hawaii lunar spectral data collection using a spectral mixing model. The spectra analyzed are those of 45 mare sites and 75 highland sites. The spectra were selected on the basis of very high signal to noise ratios based on error bars and point to point scatter, and on quality of removal of telluric water bands. The spectral mixing model used 7 components, not all of which were used in each fit. Four of the components were mineral spectra of the orthopyroxene, a clinopyroxene, an olivine and an anorthite, measured at the Brown University's RELAB. All of the minerals were 45-90 micron splits. Lunar soil contains other components which have the effect of reddening and darkening the soil as well as reducing spectral contrast. In addition, lunar soil contains spectral neutral bright material (likely very fine grained feldspar) which serves to reduce spectral contrast and brighten soils. Early attempts to fit many of the spectra pointed out the need for a component which has a very broad smooth absorption feature centered near 1.1 microns. Glass is a good candidate for this component. For the bright component we used a flat reflectance of 70 percent to represent fine grained feldspar. For the 'glass' component we used a telescopic spectrum of a pyroclastic glass present on the Aristarchus plateau which is characterized by a strong smooth band centered at 1.07 microns. In addition to exhibiting the glass band this spectrum is very red and has a low albedo. On the assumption that the dark component and the red component are agglutinates, which is reasonable but not necessarily true, we sought a dark red component. To derive its properties we modelled the spectrum of an Apollo 16 soil (16xxx) and assumed the dark red component to comprise 60 percent of the soil, appropriate to agglutinate abundance in mature soil. We adjusted the albedo and slope of a straight line

  11. In vitro friction and lubrication of large bearing hip prostheses.

    PubMed

    Flanagan, S; Jones, E; Birkinshaw, C

    2010-01-01

    New material combinations and designs of artificial hip implants are being introduced in an effort to improve proprioception and functional longevity. Larger joints in particular are being developed to improve joint stability, and it is thought that these larger implants will be more satisfactory for younger and more physically active patients. The study detailed here used a hip friction simulator to assess the friction and lubrication properties of large-diameter hip bearings of metal-on-metal and ceramic-on-reinforced-polymer couplings. Joints of different diameters were evaluated to determine what effect, if any, bearing diameter had on lubrication. In addition, the effects of lubricant type are considered, using carboxymethyl cellulose and bovine calf serum, and the physiological lubricant is shown to be considerably more effective at reducing friction. The frictional studies showed that the metal-on-metal joints worked under a mixed lubrication regime, producing similar friction factor values to each other. The addition of bovine calf serum (BCS) reduced the friction. The ceramic-on-reinforced-polymer samples were shown to operate with high friction factors and mixed lubrication. When tested with BCS, the larger-diameter bearings showed a decrease in friction compared with the smaller-size bearings, and the addition of BCS resulted in an increase in friction, unlike the metal-on-metal system. The study demonstrated that the component's diameter had little or no influence on the lubrication and friction of the large bearing combinations tested.

  12. Using EMMA and MIX analysis to assess mixing ratios and to identify hydrochemical reactions in groundwater.

    PubMed

    Tubau, Isabel; Vàzquez-Suñé, Enric; Jurado, Anna; Carrera, Jesús

    2014-02-01

    This study presents a methodology using an end-member mixing analysis (EMMA) and MIX to compute mixing ratios and to identify hydrochemical reactions in groundwater. The methodology consists of (1) identifying the potential sources of recharge, (2) characterising recharge sources and mixed water samples using hydrogeochemistry, (3) selecting chemical species to be used in the analysis and (4) calculating mixing ratios and identification of hydrochemical reactions in groundwater. This approach has been applied in the Besòs River Delta area, where we have collected 51 groundwater samples and a long data register of the hydrogeochemistry of the Besòs River created by the Catalan Water Agency is also available. The EMMA performed in the Besòs River suggests that 3 end-members are required to explain its temporal variability, accounting for the species chloride, sulphate, sodium, bicarbonate, calcium, magnesium, potassium, ammonium, total nitrogen, and electrical conductivity. One river end-member is from the wet periods (W1), and two are from dry periods (D1 and D2). These end-members have been used to compute mixing ratios in groundwater samples because the Besòs River is considered the main recharge source for the aquifer. Overall, dry season end-members dominated over the wet season end-member, in a proportion of 4:1. Moreover, when departures from the mixing line exist, geochemical processes might be identified. Redox processes, carbonate dissolution/precipitation and ion exchange processes may occur in Besòs Delta aquifer.

  13. Power system with an integrated lubrication circuit

    DOEpatents

    Hoff, Brian D.; Akasam, Sivaprasad; Algrain, Marcelo C.; Johnson, Kris W.; Lane, William H.

    2009-11-10

    A power system includes an engine having a first lubrication circuit and at least one auxiliary power unit having a second lubrication circuit. The first lubrication circuit is in fluid communication with the second lubrication circuit.

  14. Lubrication of Space Systems (c)

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1995-01-01

    This article presents an overview of the current state-of-the-art tribology, some current and future perceived space lubrication problem areas, and some potential new lubrication technologies. It is the author's opinion that tribology technology, in general, has not significantly advanced over the last 20 to 30 years, even though some incremental improvements in the technology have occurred. There is a better understanding of elasto-hydrodynamic lubrication, some new lubricating and wear theories have been developed, and some new liquid and solid lubricants have been formulated. However, the important problems of being able to lubricate reliably at high temperatures or at cryogenic temperatures have not been adequately address.

  15. Linkage analysis with an alternative formulation for the mixed model of inheritance: The finite polygenic mixed model

    SciTech Connect

    Stricker, C.; Fernando, R.L.; Elston, R.C.

    1995-12-01

    This paper presents an extension of the finite polygenic mixed model of Fernando et al. to linkage analysis. The finite polygenic mixed model, extended for linkage analysis, leads to a likelihood that can be calculated using efficient algorithms developed for oligogenic models. For comparison, linkage analysis of 5 simulated 4021-member pedigrees was performed using the usual mixed model of inheritance, approximated by Hasstedt, and the finite polygenic mixed model extended for linkage analysis presented here. Maximum likelihood estimates of the finite polygenic mixed model could be inferred to be closer to the simulated values in these pedigrees. 31 refs., 2 tabs.

  16. Linkage Analysis with an Alternative Formulation for the Mixed Model of Inheritance: The Finite Polygenic Mixed Model

    PubMed Central

    Stricker, C.; Fernando, R. L.; Elston, R. C.

    1995-01-01

    This paper presents an extension of the finite polygenic mixed model of FERNANDO et al. (1994) to linkage analysis. The finite polygenic mixed model, extended for linkage analysis, leads to a likelihood that can be calculated using efficient algorithms developed for oligogenic models. For comparison, linkage analysis of 5 simulated 4021-member pedigrees was performed using the usual mixed model of inheritance, approximated by HASSTEDT (1982), and the finite polygenic mixed model extended for linkage analysis presented here. Maximum likelihood estimates of the finite polygenic mixed model could be inferred to be closer to the simulated values in these pedigrees. PMID:8601502

  17. Life Cycle Cost Analysis of Ready Mix Concrete Plant

    NASA Astrophysics Data System (ADS)

    Topkar, V. M.; Duggar, A. R.; Kumar, A.; Bonde, P. P.; Girwalkar, R. S.; Gade, S. B.

    2013-11-01

    India, being a developing nation is experiencing major growth in its infrastructural sector. Concrete is the major component in construction. The requirement of good quality of concrete in large quantities can be fulfilled by ready mix concrete batching and mixing plants. The paper presents a technique of applying the value engineering tool life cycle cost analysis to a ready mix concrete plant. This will help an investor or an organization to take investment decisions regarding a ready mix concrete facility. No economic alternatives are compared in this study. A cost breakdown structure is prepared for the ready mix concrete plant. A market survey has been conducted to collect realistic costs for the ready mix concrete facility. The study establishes the cash flow for the ready mix concrete facility helpful in investment and capital generation related decisions. Transit mixers form an important component of the facility and are included in the calculations. A fleet size for transit mixers has been assumed for this purpose. The life cycle cost has been calculated for the system of the ready mix concrete plant and transit mixers.

  18. Elastohydrodynamic lubrication analysis of a functionally graded layered bearing surface, with particular reference to 'cushion form bearings' for artificial knee joints.

    PubMed

    Virdee, S S; Wang, F C; Xu, H; Jin, Z M

    2003-01-01

    Elastohydrodynamic lubrication of a functionally graded layered (FGL) bearing surface, whose elastic modulus increases with depth from the bearing surface, was investigated in this study. The finite difference method was employed to solve the Reynolds equation, simultaneously with the elasticity equation of the bearing surface, under circular point contacts. The finite element method was adopted to solve the elasticity equation for the FGL bearing surface. The displacement coefficients thus obtained were used to calculate the elastic deformation of the bearing surface, required for the elastohydrodynamic lubrication analysis. Good agreement of the predicted film thickness and pressure distribution was obtained, between the present method and a previous study for a single layered bearing surface with a uniform elastic modulus. The general numerical methodology was then applied to an FGL bearing surface with both linear and exponential variations in elastic modulus, with particular reference to the 'cushion form bearing' for artificial knee joints. The predicted film thickness and pressure distribution were shown to be quite close to those obtained for a single layer under typical operating conditions representative of artificial knee joints, provided that the elastic modulus of the single layer was chosen to be the average elastic modulus of the graded layer.

  19. Commercial scale validation of a process scale-up model for lubricant blending of pharmaceutical powders.

    PubMed

    Kushner, Joseph; Schlack, Holger

    2014-11-20

    An experimental study was conducted to verify that lubrication mixing in commercial-scale bin blenders can be described by a previously-reported lubrication blending process scale-up model. Specifically, the mixing of two placebo formulations (2:1 MCC:lactose, and 2:1 MCC:DCP) with 1% magnesium stearate in 100, 400, and 2000 L bin blenders at 30% and 70% blend fill levels for several extents of lubricant mixing was examined. The lubricated powder blends were assessed for bulk/tapped density and powder flow, as measured by Hausner's ratio. The blends were then compressed into tablets and evaluated for tensile strength, friability, and disintegration. It was observed that the lubrication rate constant, γ, for tablet tensile strength and for bulk specific volume were similar. Furthermore, powder flow, as measured by Hausner's ratio, improved with increased extent of lubrication. Tablet disintegration and tablet friability were both minimally affected as a result of extended lubrication for the placebos blends evaluated in this study. The results of this study confirm that the lubrication mixing model can be applied to scale-up the lubrication blending process from batches made in 30 mL bottle blenders to batches made in 2000 L bin blenders, which is a range of nearly five orders of magnitude.

  20. Optical diagnostic techniques in tribological analysis: Applications to wear film characterization, solid lubricant chemical transition, and electrical sliding contacts

    NASA Astrophysics Data System (ADS)

    Windom, Bret C.

    Friction and wear have undisputedly huge macroscopic effects on the cost and lifetime of many mechanical systems. The cost to replace parts and the cost to overcome the energy losses associated with friction, although small in nature, can be enormous over long operating times. The understanding of wear and friction begins with the understanding of the physics and chemistry between the reacting surfaces on a microscopic level. Light as a diagnostic tool is a good candidate to perform the very sensitive microscopic measurements needed to help understand the fundamental science occurring in friction/wear systems. Light's small length scales provide the capabilities to characterize very local surface phenomena, including thin transfer films and surface chemical transitions. Light-based diagnostic techniques provide nearly instantaneous results, enabling one to make in situ/real time measurements which could be used to track wear events and associated chemical kinetics. In the present study, two optical diagnostic techniques were investigated for the analysis of tribological systems. The first technique employed was Raman spectroscopy. Raman spectroscopy was investigated as a possible means for in situ measurement of thin transfer films in order to track the wear kinetics and structural transitions of bulk polymers. A micro-Raman system was designed, built, and characterized to track fresh wear films created from a pin-on-disk tribometer. The system proved capable of characterizing and tracking wear film thicknesses of ˜2 mum and greater. In addition, the system provided results indicating structural changes in the wear film as compared to the bulk when sliding speeds were increased. The spectral changes due to the altering of molecular vibrations can be attributed to the increase in temperature during high sliding speeds. Raman spectroscopy was also used to characterize the oxidation of molybdenum disulphide, a solid lubricant used in many applications, including high

  1. Fluid lubricated bearing assembly

    DOEpatents

    Boorse, Henry A.; Boeker, Gilbert F.; Menke, John R.

    1976-01-01

    1. A support for a loaded rotatable shaft comprising in combination on a housing having a fluid-tight cavity encasing an end portion of said shaft, a thrust bearing near the open end of said cavity for supporting the axial thrust of said shaft, said thrust bearing comprising a thrust plate mounted in said housing and a thrust collar mounted on said shaft, said thrust plate having a central opening the peripheral portion of which is hermetically sealed to said housing at the open end of said cavity, and means for supplying a fluid lubricant to said thrust bearing, said thrust bearing having a lubricant-conducting path connecting said lubricant supplying means with the space between said thrust plate and collar intermediate the peripheries thereof, the surfaces of said plate and collar being constructed and arranged to inhibit radial flow of lubricant and, on rotation of said thrust collar, to draw lubricant through said path between the bearing surfaces and to increase the pressure therebetween and in said cavity and thereby exert a supporting force on said end portion of said shaft.

  2. Computational Chemistry and Lubrication

    NASA Technical Reports Server (NTRS)

    Zehe, Michael J.

    1998-01-01

    Members of NASA Lewis Research Center's Tribology and Surface Science Branch are applying high-level computational chemistry techniques to the development of new lubrication systems for space applications and for future advanced aircraft engines. The next generation of gas turbine engines will require a liquid lubricant to function at temperatures in excess of 350 C in oxidizing environments. Conventional hydrocarbon-based lubricants are incapable of operating in these extreme environments, but a class of compounds known as the perfluoropolyether (PFAE) liquids (see the preceding illustration) shows promise for such applications. These commercially available products are already being used as lubricants in conditions where low vapor pressure and chemical stability are crucial, such as in satellite bearings and composite disk platters. At higher temperatures, however, these compounds undergo a decomposition process that is assisted (catalyzed) by metal and metal oxide bearing surfaces. This decomposition process severely limits the applicability of PFAE's at higher temperatures. A great deal of laboratory experimentation has revealed that the extent of fluid degradation depends on the chemical properties of the bearing surface materials. Lubrication engineers would like to understand the chemical breakdown mechanism to design a less vulnerable PFAE or to develop a chemical additive to block this degradation.

  3. Space Station lubrication considerations

    NASA Technical Reports Server (NTRS)

    Leger, Lubert J.; Dufrane, Keith

    1987-01-01

    Future activities in space will require the use of large structures and high power availability in order to fully exploit opportunities in Earth and stellar observations, space manufacturing and the development of optimum space transportation vehicles. Although these large systems will have increased capabilities, the associated development costs will be high, and will dictate long life with minimum maintenance. The Space Station provides a concrete example of such a system; it is approximately one hundred meters in major dimensions and has a life requirement of thirty years. Numerous mechanical components will be associated with these systems, a portion of which will be exposed to the space environment. If the long life and low maintenance goals are to be satisfied, lubricants and lubrication concepts will have to be carefully selected. Current lubrication practices are reviewed with the intent of determining acceptability for the long life requirements. The effects of exposure of lubricants and lubricant binders to the space environment are generally discussed. Potential interaction of MoS2 with atomic oxygen, a component of the low Earth orbit environment, appears to be significant.

  4. Engine lubricating system

    SciTech Connect

    Kurio, N.; Yoshimi, H.; Shigemura, T.; Shono, Y.

    1988-10-04

    This patent describes engine lubricating system comprising a lubricating oil supply means having a plunger member adapted to be reciprocated in the axial direction in response to an engine output shaft to discharge lubricating oil, a control pin which is adapted to abut against the plunger member and is movable to change the stroke of the plunger member, thereby changing the amount of the lubricating oil to be discharged in each stroke of the plunger member, and an electric actuator which moves the control pin to change the stroke of the plunger member; a control means which receives the electric signal from the operating condition detecting means and outputs an electric control signal for controlling the electric actuator; the actuator comprising a stepping motor and the control means outputting an electric control signal representing the number of steps by which the stepping motor is to be operated; the operating condition detecting means comprising an intake volume detecting means which detects the amount of intake air introduced into the cylinder of the engine per one engine revolution, and the control means outputs and electric signal to the stepping motor which controls the stepping motor to drive the control pin to increase the amount of the lubricating oil to be discharged in each stroke of the plunger member as the amount of intake air increases.

  5. A general elastohydrodynamic lubrication analysis of artificial hip joints employing a compliant layered socket under steady state rotation.

    PubMed

    Wang, F C; Liu, F; Jin, Z M

    2004-01-01

    A general numerical methodology was developed in the present study to analyse the elastohydrodynamic lubrication problem of a compliant layered socket against a rigid ball under steady state rotation representing flexion and extension during walking, with particular reference to artificial hip joint replacements. The general numerical methodology consisted of using the Newton-Raphson method to solve the Reynolds equation, simultaneously with the full elasticity equation using the finite element method in combination with the fast Fourier transform technique. Two specific types of acetabular cup were considered, one with ultra-high molecular weight polyethylene used in current total hip joint replacements, and one with polyurethane proposed for compliant layered 'cushion form bearings' for future developments. The film thickness and the pressure distribution for both cups were obtained under a wide range of operating conditions. The predicted central or average film thicknesses within the contact conjunction were compared with those estimated from various simplified theories available in the literature. A simple analytical methodology was consequently established to estimate the lubricating film thickness in a compliant layered socket, based on the corresponding ball-on-plane model and the consideration of the curvature effect.

  6. Modeling and Analysis of Mixed Synchronous/Asynchronous Systems

    NASA Technical Reports Server (NTRS)

    Driscoll, Kevin R.; Madl. Gabor; Hall, Brendan

    2012-01-01

    Practical safety-critical distributed systems must integrate safety critical and non-critical data in a common platform. Safety critical systems almost always consist of isochronous components that have synchronous or asynchronous interface with other components. Many of these systems also support a mix of synchronous and asynchronous interfaces. This report presents a study on the modeling and analysis of asynchronous, synchronous, and mixed synchronous/asynchronous systems. We build on the SAE Architecture Analysis and Design Language (AADL) to capture architectures for analysis. We present preliminary work targeted to capture mixed low- and high-criticality data, as well as real-time properties in a common Model of Computation (MoC). An abstract, but representative, test specimen system was created as the system to be modeled.

  7. Mixed time integration methods for transient thermal analysis of structures

    NASA Technical Reports Server (NTRS)

    Liu, W. K.

    1982-01-01

    The computational methods used to predict and optimize the thermal structural behavior of aerospace vehicle structures are reviewed. In general, two classes of algorithms, implicit and explicit, are used in transient thermal analysis of structures. Each of these two methods has its own merits. Due to the different time scales of the mechanical and thermal responses, the selection of a time integration method can be a different yet critical factor in the efficient solution of such problems. Therefore mixed time integration methods for transient thermal analysis of structures are being developed. The computer implementation aspects and numerical evaluation of these mixed time implicit-explicit algorithms in thermal analysis of structures are presented. A computationally useful method of estimating the critical time step for linear quadrilateral element is also given. Numerical tests confirm the stability criterion and accuracy characteristics of the methods. The superiority of these mixed time methods to the fully implicit method or the fully explicit method is also demonstrated.

  8. Basic lubrication equations

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    Lubricants, usually Newtonian fluids, are assumed to experience laminar flow. The basic equations used to describe the flow are the Navier-Stokes equation of motion. The study of hydrodynamic lubrication is, from a mathematical standpoint, the application of a reduced form of these Navier-Stokes equations in association with the continuity equation. The Reynolds equation can also be derived from first principles, provided of course that the same basic assumptions are adopted in each case. Both methods are used in deriving the Reynolds equation, and the assumptions inherent in reducing the Navier-Stokes equations are specified. Because the Reynolds equation contains viscosity and density terms and these properties depend on temperature and pressure, it is often necessary to couple the Reynolds with energy equation. The lubricant properties and the energy equation are presented. Film thickness, a parameter of the Reynolds equation, is a function of the elastic behavior of the bearing surface. The governing elasticity equation is therefore presented.

  9. Fluid lubricated bearing construction

    DOEpatents

    Dunning, John R.; Boorse, Henry A.; Boeker, Gilbert F.

    1976-01-01

    1. A fluid lubricated thrust bearing assembly comprising, in combination, a first bearing member having a plain bearing surface, a second bearing member having a bearing surface confronting the bearing surface of said first bearing member and provided with at least one spiral groove extending inwardly from the periphery of said second bearing member, one of said bearing members having an axial fluid-tight well, a source of fluid lubricant adjacent to the periphery of said second bearing member, and means for relatively rotating said bearing members to cause said lubricant to be drawn through said groove and to flow between said bearing surfaces, whereby a sufficient pressure is built up between said bearing surfaces and in said well to tend to separate said bearing surfaces.

  10. Inserts Automatically Lubricate Ball Bearings

    NASA Technical Reports Server (NTRS)

    Hager, J. A.

    1983-01-01

    Inserts on ball-separator ring of ball bearings provide continuous film of lubricant on ball surfaces. Inserts are machined or molded. Small inserts in ball pockets provide steady supply of lubricant. Technique is utilized on equipment for which maintenance is often poor and lubrication interval is uncertain, such as household appliances, automobiles, and marine engines.

  11. Environmental Capability of Liquid Lubricants

    NASA Technical Reports Server (NTRS)

    Beerbower, A.

    1973-01-01

    The methods available for predicting the properties of liquid lubricants from their structural formulas are discussed. The methods make it possible to design lubricants by forecasting the results of changing the structure and to determine the limits to which liquid lubricants can cope with environmental extremes. The methods are arranged in order of their thermodynamic properties through empirical physical properties to chemical properties.

  12. Solvent dewaxing of lubricating oils

    SciTech Connect

    Sequeira, A. Jr.

    1991-04-09

    This paper describes improvement in a process for producing a dewaxed lubricating oil from a wax-bearing mineral oil by the steps comprising; mixing the oil with a dewaxing solvent thereby forming an oil-solvent mixture, chilling the oil-solvent mixture to a dewaxing temperature thereby crystallizing the wax and forming an oil-solvent crystalline wax mixture, separating the oil-solvent-crystalline wax mixture to form a dewaxed oil-solvent mixture and crystalline wax, steam stripping the dewaxed oil-solvent mixture at a temperature of 300{degrees}F to 600{degrees}F and pressure of 1 atm to 3 atm, to yield a solvent free dewaxed oil.

  13. Vapor/Mist Used to Lubricate Gears After Loss of Primary Lubrication System

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Morales, Wilfredo

    2001-01-01

    Loss of lubrication in rotorcraft drive systems is a demanding requirement placed on drive system manufacturers. The drive system must operate for at least 30 minutes once the primary lubrication system has failed. This test is a military requirement that must be passed prior to certification of the aircraft. As new aircraft engines, operating at higher speeds, are fielded, the requirements for the drive system become increasingly more difficult. Also, the drive system must be lightweight, which minimizes the opportunity to use the gear bodies to absorb the tremendous amount of heating that takes place. In many cases, the amount of heat generated because of the high speed and load requires an emergency lubrication system that negatively impacts the aircraft's weight, complexity, and cost. A single mesh spur gear test rig is being used at the NASA Glenn Research Center to investigate possible emergency lubrication system improvements that will minimize the impact of having these systems onboard rotorcraft. A technique currently being investigated uses a vapor/mist system to lubricate the contacting surfaces after the primary lubrication system has been shut down. A number of tests were conducted in which the vapor/mist used the same lubricant as the primary system, but at a greatly reduced flow rate. Each test was initiated with the primary lubrication system operational and at steady-state conditions for a given speed and load. Then the primary lubrication system was shut down, and the vapor/mist lubrication system was initiated. An example of the tests conducted is shown in the figures. These preliminary tests have uncovered a mechanism that provides a lubricious, carbonaceous solid on the surface that actually reduces the surface temperature of the meshing gear teeth during operation. Surface analysis of the carbonaceous solid revealed it was graphitic. This mechanism is the synthetic lubricant "coking" on the active profile of the gears, which reduces the

  14. LUBRICATED TRANSPORT OF VISCOUS FLUIDS

    SciTech Connect

    JOSEPH, DANIEL D

    2004-06-21

    We became the acknowledged world leaders in the science fundamentals of the technology of water lubricated pipelines focusing on stability, numerical and experimental studies. We completed the first direct numerical simulation of axisymmetric core flow. We showed that the pressure at the front of the wave is large (the fluid enters a converging region) and it pushes the interface in, steepening the wave at its front. At the backside of the wave, behind the crest, the pressure is low (diverging flow) and it pulls the interface to the wall, smoothing the backside of the wave. The steepening of the wave can be regarded as a shock up by inertia and it shows that dynamics works against the formation of long waves which are often assumed but not justified in the analysis of such problems. We showed that the steep wave persists even as the gap between the core and the wall decreases to zero. The wave length also decreases in proportion, so that the wave shape is preserved in this limit. This leads to the first mathematical solution giving rise sharkskin. The analysis also showed that there is a threshold Reynolds number below which the total force reckoned relative to a zero at the wave crest is negative, positive above, and we conjectured, therefore that inertia is required to center a density matched core and to levitate the core off the wall when the density is not matched. Other work relates to self-lubricated transport of bitumen froth and self-lubricated transport of bitumen froth.

  15. Rheological effects on friction in elastohydrodynamic lubrication

    NASA Technical Reports Server (NTRS)

    Trachman, E. G.; Cheng, H. S.

    1973-01-01

    An analytical and experimental investigation is presented of the friction in a rolling and sliding elastohydrodynamic lubricated contact. The rheological behavior of the lubricant is described in terms of two viscoelastic models. These models represent the separate effects of non-Newtonian behavior and the transient response of the fluid. A unified description of the non-Newtonian shear rate dependence of the viscosity is presented as a new hyperbolic liquid model. The transient response of viscosity, following the rapid pressure rise encountered in the contact, is described by a compressional viscoelastic model of the volume response of a liquid to an applied pressure step. The resulting momentum and energy equations are solved by an iterative numerical technique, and a friction coefficient is calculated. The experimental study was performed, with two synthetic paraffinic lubricants, to verify the friction predictions of the analysis. The values of friction coefficient from theory and experiment are in close agreement.

  16. Electrophoretically-deposited solid film lubricants

    SciTech Connect

    Dugger, M.T.; Panitz, J.K.J.; Vanecek, C.W.

    1995-04-01

    An aqueous-based process that uses electrophoresis to attract powdered lubricant in suspension to a charged target was developed. The deposition process yields coatings with low friction, complies with environmental safety regulations, requires minimal equipment, and has several advantages over processes involving organic binders or vacuum techniques. This work focuses on development of the deposition process, includes an analysis of the friction coefficient of the material in sliding contact with stainless steel under a range of conditions, and a functional evaluation of coating performance in a precision mechanical device application. Results show that solid lubricant films with friction coefficients as low as 0.03 can be produced. A 0.03 friction coefficient is superior to solid lubricants with binder systems and is comparable to friction coefficients generated with more costly vacuum techniques.

  17. JET MIXING ANALYSIS FOR SRS HIGH-LEVEL WASTE RECOVERY

    SciTech Connect

    Lee, S.

    2011-07-05

    The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four slurry pumps located within the tank liquid. The slurry pump may be fixed in position or they may rotate depending on the specific mixing requirements. The high-level waste in Tank 48 contains insoluble solids in the form of potassium tetraphenyl borate compounds (KTPB), monosodium titanate (MST), and sludge. Tank 48 is equipped with 4 slurry pumps, which are intended to suspend the insoluble solids prior to transfer of the waste to the Fluidized Bed Steam Reformer (FBSR) process. The FBSR process is being designed for a normal feed of 3.05 wt% insoluble solids. A chemical characterization study has shown the insoluble solids concentration is approximately 3.05 wt% when well-mixed. The project is requesting a Computational Fluid Dynamics (CFD) mixing study from SRNL to determine the solids behavior with 2, 3, and 4 slurry pumps in operation and an estimate of the insoluble solids concentration at the suction of the transfer pump to the FBSR process. The impact of cooling coils is not considered in the current work. The work consists of two principal objectives by taking a CFD approach: (1) To estimate insoluble solids concentration transferred from Tank 48 to the Waste Feed Tank in the FBSR process and (2) To assess the impact of different combinations of four slurry pumps on insoluble solids suspension and mixing in Tank 48. For this work, several different combinations of a maximum of four pumps are considered to determine the resulting flow patterns and local flow velocities which are thought to be associated with sludge particle mixing. Two different elevations of pump nozzles are used for an assessment of the flow patterns on the tank mixing. Pump design and operating parameters used for the analysis are summarized in Table 1. The baseline

  18. A new solid lubricant

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.; Sliney, H. E.

    1969-01-01

    Friction and wear life studies on burnished films of the compound graphite fluoride have demonstrated its potential as a solid lubricant material. It is effective in moist air, dry air, or in dry argon at temperatures up to approximately 400 degrees C.

  19. Estolides: biobased lubricants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estolides were originally developed as a cost effective derivative from vegetable oil sources to overcome the problems associated with standard vegetable oils as lubricants. Classic estolides are formed by the formation of a carbocation at the site of unsaturation that can undergo nucleophilic addi...

  20. Biobased lubricant additives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fully biobased lubricants are those formulated using all biobased ingredients, i.e. biobased base oils and biobased additives. Such formulations provide the maximum environmental, safety, and economic benefits expected from a biobased product. Currently, there are a number of biobased base oils that...

  1. A thermodynamic analysis of charged mixed micelles in water.

    PubMed

    Maeda, Hiroshi

    2005-08-25

    A thermodynamic analysis is presented for electrically charged mixed micelles in water on the basis of the Gibbs-Duhem relation proposed by Hall in combination with the information on the degree of counterion binding. The proposed analyses are shown to work well for both ionic/nonionic mixed micelles and those consisting of ionic surfactants of like charges. Conclusions for ionic/nonionic mixed micelles are as follows. (1) The contribution from counterions is significant. (2) In media of low ionic strengths, the counterion concentration varies with the micellar mole fraction of the ionic species x. The dependency of the activity coefficients and the excess free energy on x is significantly influenced by this effect, but it can be corrected to a large extent in terms of the Corrin-Harkins relation. (3) The regular solution theory (RST) is not always valid even when the excess free energy is described well with the RST expression unless the observed range of the micelle composition is wide enough. (4) The RST overestimates x and underestimates the activity coefficient of the ionic species when applied to the mixed micelles to which it is inapplicable. For the ionic mixed micelles consisting of surfactants of like charges, the Lange-Shinoda approach is shown to be consistent with the present analysis in terms of the Gibbs-Duhem relation, but Motomura's approach is found to be not exact but approximate.

  2. Views of Effective College Faculty: A Mixed Analysis

    ERIC Educational Resources Information Center

    Slate, John R.; LaPrairie, Kimberly Nichols; Schulte, Don P.; Onwuegbuzie, Anthony J.

    2011-01-01

    A mixed analysis of the perceived characteristics of effective college faculty members was conducted through surveying 615 students, predominantly Hispanic, enrolled in courses at two southwest Hispanic-serving universities. Beliefs were identified that led to 29 prevailing themes: Knowledgeable; Understanding; Communication; Teaches Well; Caring;…

  3. Sensitivity Analysis of Mixed Models for Incomplete Longitudinal Data

    ERIC Educational Resources Information Center

    Xu, Shu; Blozis, Shelley A.

    2011-01-01

    Mixed models are used for the analysis of data measured over time to study population-level change and individual differences in change characteristics. Linear and nonlinear functions may be used to describe a longitudinal response, individuals need not be observed at the same time points, and missing data, assumed to be missing at random (MAR),…

  4. Discriminant Analysis Using Mixed Continuous, Dichotomous, and Ordered Categorical Variables

    ERIC Educational Resources Information Center

    Lee, Sik-Yum; Song, Xin-Yuan; Lu, Bin

    2007-01-01

    This article proposes an intuitive approach for predictive discriminant analysis with mixed continuous, dichotomous, and ordered categorical variables that are defined via an underlying multivariate normal distribution with a threshold specification. The classification rule is based on the comparison of the observed data logarithm probability…

  5. An Experimental Measurement of Lubrication Behavior of Piston Rings in a Spark Ignition Engine

    NASA Astrophysics Data System (ADS)

    Cho, Sungwoo; Choi, Sangmin; Bae, Choongsik

    Friction forces of a piston ring pack for a typical SI engine were measured using a floating liner system, in which the effects of cylinder pressure, oil starvation and piston secondary motion were excluded. Friction patterns of each individual ring, represented by measured friction forces, were classified into five frictional modes with regard to the combination of predominant lubrication regimes (boundary, mixed and hydrodynamic lubrication) and stroke regions (mid-stroke and dead centers). Those modes were identified on a Stribeck diagram of the dimensionless bearing parameter and friction coefficients; the coefficients were evaluated at mid-stroke and at dead centers. Frictional modes were evaluated by varying operation parameters (such as engine speed and cylinder wall temperature). Compression rings operated in the mode in which hydrodynamic lubrication was dominant at mid-stroke, while mixed lubrication was dominant at dead centers in steady conditions. However, oil control rings operated in the mode in which mixed lubrication was dominant throughout the entire stroke.

  6. Lubrication handbook for the space industry. Part A: Solid lubricants. Part B: Liquid lubricants

    NASA Technical Reports Server (NTRS)

    Mcmurtrey, E. L.

    1985-01-01

    This handbook is intended to provide a ready reference for many of the solid and liquid lubricants used in the space industry. Lubricants and lubricant properties are arranged systematically so that designers, engineers, and maintenance personnel can conveniently locate data needed for their work. This handbook is divided into two major parts (A and B). Part A is a compilation of solid lubricant suppliers information on chemical and physical property of data of more than 250 solid lubricants, bonded solid lubricants, dispersions, and composites. Part B is a compilation of chemical and physical porperty data of more then 250 liquid lubricants, greases, oils, compounds, and fluids. The listed materials cover a broad spectrum from manufacturing and ground support to hardware applications of spacecraft.

  7. Evaluation of mixed-population flood-frequency analysis

    USGS Publications Warehouse

    Murphy, P.J.

    2001-01-01

    A mixed population of flood flows was shown to cause quality-of-fit problems if a single-population flood-frequency distribution was used to describe the flood data. The three populations in this mix were "ordinary," tropical cyclone, and ice-jam-release floods. Parametric descriptions of the single and separated flood populations were evaluated using probability-plot correlation-coefficient tests. These tests quantified how well the flood-probability distributions agreed with plotting-position descriptions of the data and quantified the differences due to the mixed-population analysis. High outliers caused the high skewness found in the single- population analyses. The tropical cyclone component was underestimated by single-population analyses at gauging stations in Massachusetts that had little data.

  8. Lubrication Handbook For The Space Industry

    NASA Technical Reports Server (NTRS)

    Mcmurtrey, Ernest L.

    1988-01-01

    A 458-page handbook covers many of solid and liquid lubricants used in space industry. Also useful reference in industrial and military applications of lubricants. Part A of handbook compilation of data on chemical and physical properties of over 250 solid lubricants, including bonded solid lubricants, dispersions, and composites. Part B covers over 250 liquid lubricants, greases, oils, compounds, and fluids.

  9. Lubrication, adsorption, and rheology of aqueous polysaccharide solutions.

    PubMed

    Stokes, Jason R; Macakova, Lubica; Chojnicka-Paszun, Agnieszka; de Kruif, Cornelis G; de Jongh, Harmen H J

    2011-04-01

    Aqueous lubrication is currently at the forefront of tribological research due to the desire to learn and potentially mimic how nature lubricates biotribological contacts. We focus here on understanding the lubrication properties of naturally occurring polysaccharides in aqueous solution using a combination of tribology, adsorption, and rheology. The polysaccharides include pectin, xanthan gum, gellan, and locus bean gum that are all widely used in food and nonfood applications. They form rheologically complex fluids in aqueous solution that are both shear thinning and elastic, and their normal stress differences at high shear rates are found to be characteristic of semiflexible/rigid molecules. Lubrication is studied using a ball-on-disk tribometer with hydrophobic elastomer surfaces, mimicking biotribological contacts, and the friction coefficient is measured as a function of speed across the boundary, mixed, and hydrodynamic lubrication regimes. The hydrodynamic regime, where the friction coefficient increases with increasing lubricant entrainment speed, is found to depend on the viscosity of the polysaccharide solutions at shear rates of around 10(4) s(-1). The boundary regime, which occurs at the lowest entrainment speeds, depends on the adsorption of polymer to the substrate. In this regime, the friction coefficient for a rough substrate (400 nm rms roughness) is dependent on the dry mass of polymer adsorbed to the surface (obtained from surface plasmon resonance), while for a smooth substrate (10 nm rms roughness) the friction coefficient is strongly dependent on the hydrated wet mass of adsorbed polymer (obtained from quartz crystal microbalance, QCM-D). The mixed regime is dependent on both the adsorbed film properties and lubricant's viscosity at high shear rates. In addition, the entrainment speed where the friction coefficient is a minimum, which corresponds to the transition between the hydrodynamic and mixed regime, correlates linearly with the ratio

  10. Wide-temperature-spectrum self-lubricating coatings prepared by plasma spraying

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1979-01-01

    Self-lubricating, multicomponent coatings, which lubricate over a wide range of operating conditions, are described. The coatings were successfully applied by plasma-spraying mixed powders onto superalloy substrates. They were evaluated in friction and wear experiments, and in sliding contact bearing tests. These coatings are wear resistant by virtue of their self lubricating characteristics rather than because of extreme hardness; a further benefit is low friction. Experiments with simple pin on disk sliding specimens and oscillating plain cylindrical bearing tests were performed to evaluate the tribological properties of the coatings. It was shown that coatings of nichrome, glass and calcium fluoride are self-lubricating from about 500 to 900 C, but give high friction at the lower temperatures. The addition of silver to the coating composition improved the low temperature bearing properties and resulted in coatings which are self-lubricating from cryogenic temperatures to at least 870 C; they are therefore, wide temperature spectrum, self-lubricating compositions.

  11. Solid film lubricants and thermal control coatings flown aboard the EOIM-3 MDA sub-experiment

    SciTech Connect

    Murphy, T.J.; David, K.E.; Babel, H.W.

    1995-02-01

    Additional experimental data were desired to support the selection of candidate thermal control coatings and solid film lubricants for the McDonnell Douglas Aerospace (MDA) Space Station hardware. The third Evaluation of Oxygen Interactions With Materials Mission (EOIM-3) flight experiment presented an opportunity to study the effects of the low Earth orbit environment on thermal control coatings and solid film lubricants. MDA provided five solid film lubricants and two anodic thermal control coatings for EOIM-3. The lubricant sample set consisted of three solid film lubricants with organic binders one solid film lubricant with an inorganic binder, and one solid film lubricant with no binder. The anodize coating sample set consisted of undyed sulfuric acid anodize and cobalt sulfide dyed sulfuric acid anodize, each on two different substrate aluminum alloys. The organic and inorganic binders in the solid film lubricants experienced erosion, and the lubricating pigments experienced oxidation. MDA is continuing to assess the effect of exposure to the low Earth orbit environment on the life and friction properties of the lubricants. Results to date support the design practice of shielding solid film lubricants from the low Earth orbit environment. Post-flight optical property analysis of the anodized specimens indicated that there were limited contamination effects and some atomic oxygen and ultraviolet radiation effects. These effects appeared to be within the values predicted by simulated ground testing and analysis of these materials, and they were different for each coating and substrate.

  12. Solid film lubricants and thermal control coatings flown aboard the EOIM-3 MDA sub-experiment

    NASA Technical Reports Server (NTRS)

    Murphy, Taylor J.; David, Kaia E.; Babel, Hank W.

    1995-01-01

    Additional experimental data were desired to support the selection of candidate thermal control coatings and solid film lubricants for the McDonnell Douglas Aerospace (MDA) Space Station hardware. The third Evaluation of Oxygen Interactions With Materials Mission (EOIM-3) flight experiment presented an opportunity to study the effects of the low Earth orbit environment on thermal control coatings and solid film lubricants. MDA provided five solid film lubricants and two anodic thermal control coatings for EOIM-3. The lubricant sample set consisted of three solid film lubricants with organic binders one solid film lubricant with an inorganic binder, and one solid film lubricant with no binder. The anodize coating sample set consisted of undyed sulfuric acid anodize and cobalt sulfide dyed sulfuric acid anodize, each on two different substrate aluminum alloys. The organic and inorganic binders in the solid film lubricants experienced erosion, and the lubricating pigments experienced oxidation. MDA is continuing to assess the effect of exposure to the low Earth orbit environment on the life and friction properties of the lubricants. Results to date support the design practice of shielding solid film lubricants from the low Earth orbit environment. Post-flight optical property analysis of the anodized specimens indicated that there were limited contamination effects and some atomic oxygen and ultraviolet radiation effects. These effects appeared to be within the values predicted by simulated ground testing and analysis of these materials, and they were different for each coating and substrate.

  13. Lubrication of space systems

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1994-01-01

    NASA has many high-technology programs plannned for the future, such as the space station, Mission to Planet Earth (a series of Earth-observing satellites), space telescopes, and planetary orbiters. These missions will involve advanced mechanical moving components, space mechanisms that will need wear protection and lubrication. The tribology practices used in space today are primarily based on a technology that is more than 20 years old. The question is the following: Is this technology base good enough to meet the needs of these future long-duration NASA missions? This paper examines NASA's future space missions, how mechanisms are currently lubricated, some of the mechanism and tribology challenges that may be encountered in future missions, and some potential solutions to these future challenges.

  14. Buckyball additives improve lubrication

    SciTech Connect

    1996-08-31

    When researchers discovered the buckminsterfullerene molecule in 1985, it was considered the ideal candidate for reducing friction between tiny moving components. However, subsequently buckyballs were discovered not to be particularly good lubricators. Now, a team of chemical engineers and chemists has discovered that C60 molecules dissolved in the organic solvent toluene greatly reduce the friction between the liquid and the surface across which it flows.

  15. Shearing stability of lubricants

    NASA Technical Reports Server (NTRS)

    Shiba, Y.; Gijyutsu, G.

    1984-01-01

    Shearing stabilities of lubricating oils containing a high mol. wt. polymer as a viscosity index improver were studied by use of ultrasound. The oils were degraded by cavitation and the degradation generally followed first order kinetics with the rate of degradation increasing with the intensity of the ultrasonic irradiation and the cumulative energy applied. The shear stability was mainly affected by the mol. wt. of the polymer additive and could be determined in a short time by mechanical shearing with ultrasound.

  16. Stability of mixed time integration schemes for transient thermal analysis

    NASA Technical Reports Server (NTRS)

    Liu, W. K.; Lin, J. I.

    1982-01-01

    A current research topic in coupled-field problems is the development of effective transient algorithms that permit different time integration methods with different time steps to be used simultaneously in various regions of the problems. The implicit-explicit approach seems to be very successful in structural, fluid, and fluid-structure problems. This paper summarizes this research direction. A family of mixed time integration schemes, with the capabilities mentioned above, is also introduced for transient thermal analysis. A stability analysis and the computer implementation of this technique are also presented. In particular, it is shown that the mixed time implicit-explicit methods provide a natural framework for the further development of efficient, clean, modularized computer codes.

  17. Mixed time integration methods for transient thermal analysis of structures

    NASA Technical Reports Server (NTRS)

    Liu, W. K.

    1983-01-01

    The computational methods used to predict and optimize the thermal-structural behavior of aerospace vehicle structures are reviewed. In general, two classes of algorithms, implicit and explicit, are used in transient thermal analysis of structures. Each of these two methods has its own merits. Due to the different time scales of the mechanical and thermal responses, the selection of a time integration method can be a difficult yet critical factor in the efficient solution of such problems. Therefore mixed time integration methods for transient thermal analysis of structures are being developed. The computer implementation aspects and numerical evaluation of these mixed time implicit-explicit algorithms in thermal analysis of structures are presented. A computationally-useful method of estimating the critical time step for linear quadrilateral element is also given. Numerical tests confirm the stability criterion and accuracy characteristics of the methods. The superiority of these mixed time methods to the fully implicit method or the fully explicit method is also demonstrated.

  18. Selective Surface Modification on Lubricant Retention

    NASA Astrophysics Data System (ADS)

    Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A.

    2016-11-01

    While surface patterns are effective in improving tribological properties, nevertheless they alter the surface wettability, which will in turn affect the surface-lubricant interactions. When there is a shortage of lubricant on a patterned surface, the lubricant stored inside the cavities will be extracted to compensate the surface lubricant dissipation. Additionally, the lubricant retention effect provided by the cavities is competing with the release of the lubricant. With weak surface-lubricant interaction, the retention is limited. Therefore, the lubrication will have a sudden failure, giving a dramatic transition to abrasive wear. To improve the performance of polar lubricants on hydrophobic polymer surfaces, both topographical and selective surface modifications were incorporated on injection molded polypropylene surfaces. Distinctive lubrication improvement was observed when the surface structure density for the lubricant storage was high, and the release of the lubricant was controlled by the interaction with the selectively modified surfaces.

  19. Piezoviscous effects in nonconformal contacts lubricated hydrodynamically

    NASA Technical Reports Server (NTRS)

    Jeng, Y. R.; Hamrock, B. J.; Brewe, D. E.

    1985-01-01

    The analysis is concerned with the piezoviscous-rigid regime of lubrication for the general case of elliptical contacts. In this regime several formulas of the lubricant film thickness have been proposed by Hamrock and Dowson, by Dowson et al., and more recently by Houpert. However, either they do not include the load parameter W, which has a strong effect on film thickness, or they overestimate the film thickness by using the Barus formula for pressure-viscosity characteristics. The Roelands formula was used for the pressure-viscosity relationship. The effects of the dimensionless load, speed, and materials parameters, the radius ratio, and the lubricant entrainment direction were investigated. The dimensionless load parameter was varied over a range of one order of magnitude. The dimensionless speed parameter was varied by 5.6 times the lowest value. Conditions corresponding to the use of solid materials of steel, bronze, and silicon nitride and lubricants of paraffinic and naphthenic mineral oil were considered in obtaining the exponent in the dimensionless materials parameter. The radius ratio was varied from 0.2 to 64 (a configuration approaching a line contact). Forty-one cases were used in obtaining a minimum film thickness formula. Contour plots indicate in detail the pressure developed between the contacting solids.

  20. Lubrication handbook for use in the space industry. Part A: Solid lubricants. Part B: Liquid lubricants

    NASA Technical Reports Server (NTRS)

    Campbell, M. E.; Thompson, M. B.

    1972-01-01

    This handbook provides a ready reference for many of the solid and liquid lubricants used in the space industry. Lubricants and lubricant properties are arranged systematically so that designers, engineers, and maintenance personnel in the space industry can conveniently locate data needed for their work. The handbook is divided into two major parts. Part A is a compilation of chemical and physical property data of more than 250 solid lubricants, bonded solid lubricants, dispersions and composites. Part B is a compilation of chemical and physical property data of more than 250 liquid lubricants, greases, oils, compounds and fluids. The listed materials cover a broad spectrum, from manufacturing and ground support to hardware applications for missiles and spacecraft.

  1. Fluid-film lubrication with an application to piston rings

    NASA Astrophysics Data System (ADS)

    Esfahanian, Mohsen

    1994-04-01

    This dissertation consists of four related studies. The first part provides dimensionless film thickness equations for four fluid-fllm lubrication regimes found for nonconformal surfaces while considering side-leakage effects. These regimes are isoviscous rigid, piezoviscous rigid, isoviscous elastic, and piezoviscous elastic. The influence or lack of influence of elastic effects from the solid surfaces and pressure-viscosity effects from the lubricant is a factor that distinguishes these regimes. Results are presented as a map of the lubrication regimes for four values of the ellipticity parameter. The second part deals with integrating artificial intelligence and conventional numerical design techniques to aid in tribological design. The study concentrates on the application of contact stresses. The result is a computer code, the Design Expert for Contact Stress, which incorporates and combines an expert system with numerical analysis techniques to aid the user in designing machine elements. This menu-driven program also performs a design compatibility analysis, which evaluates the compatibility between the specifications and the design, provides a rating on the overall design, lists reasons for the evaluation, and gives suggestions for improvements. The third part investigates the rheological effects in elastohydrodynamic lubrication. In this study the effects on fluid viscosity of pressure, temperature, shear strain rate, shear stress, and time are examined. A number of non-Newtonian models are introduced. The effects of pressure on fluid density are described. The role of solidification pressure on the density of the lubricants is also examined. The possible influence of a lubricant's viscoelastic behavior on its viscosity is considered. Finally, the influence of rheological effects on elastohydrodynamic lubrication is explained. The last part describes fundamental research into the basic mechanisms involved in piston ring lubrication. A recently developed

  2. RO1 Funding for Mixed Methods Research: Lessons learned from the Mixed-Method Analysis of Japanese Depression Project

    PubMed Central

    Arnault, Denise Saint; Fetters, Michael D.

    2013-01-01

    Mixed methods research has made significant in-roads in the effort to examine complex health related phenomenon. However, little has been published on the funding of mixed methods research projects. This paper addresses that gap by presenting an example of an NIMH funded project using a mixed methods QUAL-QUAN triangulation design entitled “The Mixed-Method Analysis of Japanese Depression.” We present the Cultural Determinants of Health Seeking model that framed the study, the specific aims, the quantitative and qualitative data sources informing the study, and overview of the mixing of the two studies. Finally, we examine reviewer's comments and our insights related to writing mixed method proposal successful for achieving RO1 level funding. PMID:25419196

  3. KSC lubricant testing program. [lubrication characteristics and corrosion resistance

    NASA Technical Reports Server (NTRS)

    Lockhart, B. J.; Bryan, C. J.

    1973-01-01

    A program was conducted to evaluate the performance of various lubricants in use and considered for use at Kennedy Space Center (KSC). The overall objectives of the program were to: (1) determine the lubrication characteristics and relative corrosion resistance of lubricants in use and proposed for use at KSC; (2) identify materials which may be equivalent to or better than KELF-90 and Krytox 240 AC greases; and (3) identify or develop an improved lubricating oil suitable for use in liquid oxygen (LOX) pumps at KSC. It was concluded that: (1) earth gel thickened greases are very poor corrosion preventive materials in the KSC environment; (2) Halocarbon 25-5S and Braycote 656 were suitable substiutes for KELF-90 and Krytox 240 AC respectively; and (3) none of the oils evaluated possessed the necessary inertness, lubricity, and corrosion prevention characteristics for the KSC LOX pumping systems in their present configuration.

  4. Thermal elastohydrodynamic lubrication of spur gears

    NASA Technical Reports Server (NTRS)

    Wang, K. L.; Cheng, H. S.

    1980-01-01

    An analysis and computer program called TELSGE were developed to predict the variations of dynamic load, surface temperature, and lubricant film thickness along the contacting path during the engagement of a pair of involute spur gears. The analysis of dynamic load includes the effect of gear inertia, the effect of load sharing of adjacent teeth, and the effect of variable tooth stiffness which are obtained by a finite-element method. Results obtained from TELSGE for the dynamic load distributions along the contacting path for various speeds of a pair of test gears show patterns similar to that observed experimentally. Effects of damping ratio, contact ratio, tip relief, and tooth error on the dynamic load were examined. In addition, two dimensionless charts are included for predicting the maximum equilibrium surface temperature, which can be used to estimate directly the lubricant film thickness based on well established EHD analysis.

  5. Use of high pressure liquid chromatography in the study of liquid lubricant oxidation

    NASA Technical Reports Server (NTRS)

    Morales, W.

    1982-01-01

    The general principles of classical liquid chromatography and high-pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analysis of a C-ether liquid lubricant by each technique is illustrated. An analysis by size exclusion chromatography of an ester lubricant, which had been degraded using a micro-oxidation apparatus, is illustrated to show how HPLC can be used in the study of high-temperature lubricant degradation.

  6. Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

    SciTech Connect

    Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

    2007-01-30

    The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 1013 to 1015 n/cm2. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 1015 to 1016 n/cm2 with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

  7. Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

    NASA Astrophysics Data System (ADS)

    Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

    2007-01-01

    The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 1013 to 1015 n/cm2. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 1015 to 1016 n/cm2 with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

  8. Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

    NASA Technical Reports Server (NTRS)

    Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

    2007-01-01

    The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 10(exp 13) to 10(exp 15) n per square centimeters. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 10(exp 15) to 10(exp 16) n per square centimeters with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

  9. Evaluating Solid-Lubricant Films

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1988-01-01

    Report describes experimental techniques for measuring properties of solid-lubricant films. Discusses experimental parameters. Reviews basic pin-on-disk configurations and methods of preparing disks and applying solid lubricants. Techniques for constant-temperature testing, low-contact-stress testing, and temperature-versus-time testing presented. Suggests methods of measuring pin-wear volume and recommends ways of presenting data.

  10. Boundary lubrication by associative mucin.

    PubMed

    Wang, Xiang; Du, Miao; Han, Hongpeng; Song, Yihu; Zheng, Qiang

    2015-04-28

    Mucus lubricants are widely distributed in living organisms. Such lubricants consist of a gel structure constructed by associative mucin. However, limited tribological studies exist on associative mucin fluids. The present research is the first to investigate the frictional behavior of a typical intact vertebrate mucin (loach skin mucin), which can recover the gel structure of mucus via hydrophobic association under physiological conditions (5-10 mg/mL loach skin mucin dissolved in water). Both rough hydrophobic and hydrophilic polydimethylsiloxane (PDMS) rubber plates were used as friction substrates. Up to 10 mg/mL loach skin mucin dissolved in water led to a 10-fold reduction in boundary friction of the two substrates. The boundary-lubricating ability for hydrophilic PDMS decreased with rubbing time, whereas that for hydrophobic PDMS remained constant. The boundary-lubricating abilities of the mucin on hydrophobic PDMS and hydrophilic PDMS showed almost similar responses toward changing concentration or sodium dodecyl sulfate (SDS). The mucin fluids reduced boundary friction coefficients (μ) only at concentrations (c) in which intermucin associations were formed, with a relationship shown as μ ∼ c(-0.7). Destroying intermucin associations by SDS largely impaired the boundary-lubricating ability. Results reveal for the first time that intermolecular association of intact mucin in bulk solution largely enhances boundary lubrication, whereas tightly adsorbed layer plays a minor role in the lubrication. This study indicates that associated mucin should contribute considerably to the lubricating ability of biological mucus in vivo. PMID:25843576

  11. Lubricant Coating Process

    NASA Technical Reports Server (NTRS)

    1989-01-01

    "Peen Plating," a NASA developed process for applying molybdenum disulfide, is the key element of Techniblast Co.'s SURFGUARD process for applying high strength solid lubricants. The process requires two machines -- one for cleaning and one for coating. The cleaning step allows the coating to be bonded directly to the substrate to provide a better "anchor." The coating machine applies a half a micron thick coating. Then, a blast gun, using various pressures to vary peening intensities for different applications, fires high velocity "media" -- peening hammers -- ranging from plastic pellets to steel shot. Techniblast was assisted by Rural Enterprises, Inc. Coating service can be performed at either Techniblast's or a customer's facility.

  12. Radiograph and passive data analysis using mixed variable optimization

    DOEpatents

    Temple, Brian A.; Armstrong, Jerawan C.; Buescher, Kevin L.; Favorite, Jeffrey A.

    2015-06-02

    Disclosed herein are representative embodiments of methods, apparatus, and systems for performing radiography analysis. For example, certain embodiments perform radiographic analysis using mixed variable computation techniques. One exemplary system comprises a radiation source, a two-dimensional detector for detecting radiation transmitted through a object between the radiation source and detector, and a computer. In this embodiment, the computer is configured to input the radiographic image data from the two-dimensional detector and to determine one or more materials that form the object by using an iterative analysis technique that selects the one or more materials from hierarchically arranged solution spaces of discrete material possibilities and selects the layer interfaces from the optimization of the continuous interface data.

  13. MIXING MODELING ANALYSIS FOR SRS SALT WASTE DISPOSITION

    SciTech Connect

    Lee, S.

    2011-01-18

    Nuclear waste at Savannah River Site (SRS) waste tanks consists of three different types of waste forms. They are the lighter salt solutions referred to as supernate, the precipitated salts as salt cake, and heavier fine solids as sludge. The sludge is settled on the tank floor. About half of the residual waste radioactivity is contained in the sludge, which is only about 8 percentage of the total waste volume. Mixing study to be evaluated here for the Salt Disposition Integration (SDI) project focuses on supernate preparations in waste tanks prior to transfer to the Salt Waste Processing Facility (SWPF) feed tank. The methods to mix and blend the contents of the SRS blend tanks were evalutaed to ensure that the contents are properly blended before they are transferred from the blend tank such as Tank 50H to the SWPF feed tank. The work consists of two principal objectives to investigate two different pumps. One objective is to identify a suitable pumping arrangement that will adequately blend/mix two miscible liquids to obtain a uniform composition in the tank with a minimum level of sludge solid particulate in suspension. The other is to estimate the elevation in the tank at which the transfer pump inlet should be located where the solid concentration of the entrained fluid remains below the acceptance criterion (0.09 wt% or 1200 mg/liter) during transfer operation to the SWPF. Tank 50H is a Waste Tank that will be used to prepare batches of salt feed for SWPF. The salt feed must be a homogeneous solution satisfying the acceptance criterion of the solids entrainment during transfer operation. The work described here consists of two modeling areas. They are the mixing modeling analysis during miscible liquid blending operation, and the flow pattern analysis during transfer operation of the blended liquid. The modeling results will provide quantitative design and operation information during the mixing/blending process and the transfer operation of the blended

  14. JTMIX - CRYOGENIC MIXED FLUID JOULE-THOMSON ANALYSIS PROGRAM

    NASA Technical Reports Server (NTRS)

    Jones, J. A.

    1994-01-01

    JTMIX was written to allow the prediction of both ideal and realistic properties of mixed gases in the 65-80K temperature range. It allows mixed gas J-T analysis for any fluid combination of neon, nitrogen, various hydrocarbons, argon, oxygen, carbon monoxide, carbon dioxide, and hydrogen sulfide. When used in conjunction with the NIST computer program DDMIX, JTMIX has accurately predicted order-of-magnitude increases in J-T cooling capacities when various hydrocarbons are added to nitrogen, and it predicts nitrogen normal boiling point depressions to as low as 60K when neon is added. JTMIX searches for heat exchanger "pinch points" that can result from insolubility of various components in each other. These points result in numerical solutions that cannot exist. The length of the heat exchanger is searched for such points and, if they exist, the user is warned and the temperatures and heat exchanger effectiveness are corrected to provide a real solution. JTMIX gives very good correlation (within data accuracy) to mixed gas data published by the USSR and data taken by APD for the U.S. Naval Weapons Lab. Data taken at JPL also confirms JTMIX for all cases tested. JTMIX is written in Turbo C for IBM PC compatible computers running MS-DOS. The National Institute of Standards and Technology's (NIST, Gaithersburg, MD, 301-975-2208) computer code DDMIX is required to provide mixed-fluid enthalpy data which is input into JTMIX. The standard distribution medium for this program is a 5.25 inch 360K MS-DOS format diskette. JTMIX was developed in 1991 and is a copyrighted work with all copyright vested in NASA.

  15. An asymptotic analysis of supersonic reacting mixing layers

    NASA Technical Reports Server (NTRS)

    Jackson, T. L.; Hussaini, M. Y.

    1987-01-01

    The purpose of this paper is to present an asymptotic analysis of the laminar mixing of the simultaneous chemical reaction between parallel supersonic streams of two reacting species. The study is based on a one-step irreversible Arrhenius reaction and on large activation energy asymptotics. Essentially it extends the work of Linan and Crespo to include the effect of free shear and Mach number on the ignition regime, the deflagration regime and the diffusion flame regime. It is found that the effective parameter is the product of the characteristic Mach number and a shear parameter.

  16. 183-H Basin Mixed Waste Analysis and Testing Report

    SciTech Connect

    1995-04-01

    The purpose of this sampling and analysis report is to provide data necessary to support treatment and disposal options for the low-level mixed waste from the 183-H solar evaporation ponds. In 1973, four of the 16 flocculation and sedimentation basins were designated for use as solar evaporation basins to provide waste reduction by natural evaporation of liquid chemical wastes from the 300 Area fuel fabrication facilities. The primary purpose of this effort is to gather chemical and bulk property data for the waste in the drums/boxes of sediment removed from the basin at Central Waste Complex.

  17. Program For Joule-Thomson Analysis Of Mixed Cryogens

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Lund, Alan

    1994-01-01

    JTMIX computer program predicts ideal and realistic properties of mixed gases at temperatures between 65 and 80 K. Performs Joule-Thomson analysis of any gaseous mixture of neon, nitrogen, various hydrocarbons, argon, oxygen, carbon monoxide, carbon dioxide, and hydrogen sulfide. When used in conjunction with DDMIX computer program of National Institute of Standards and Technology (NIST), JTMIX accurately predicts order-of-magnitude increases in Joule-Thomson cooling capacities occuring when various hydrocarbons added to nitrogen. Also predicts boiling temperature of nitrogen depressed from normal value to as low as 60 K upon addition of neon. Written in Turbo C.

  18. In vitro tests of substitute lubricants for wear testing orthopaedic biomaterials.

    PubMed

    Scholes, Susan C; Joyce, Thomas J

    2013-06-01

    Bovine serum is the lubricant recommended by several international standards for the wear testing of orthopaedic biomaterials; however, there are issues over its use due to batch variation, degradation, cost and safety. For these reasons, alternative lubricants were investigated. A 50-station Super-CTPOD (circularly translating pin-on-disc) wear test rig was used, which applied multidirectional motion to ultra-high-molecular-weight polyethylene test pins rubbing against cobalt chromium discs. Thirteen possible alternative lubricants were tested. The use of soy protein as a lubricant gave statistically higher wear, while soya oil, olive oil, Channel Island milk, whole milk, whey, wheatgerm oil, 11 mg/mL egg white, albumin/globulin mix and albumin/globulin/chondroitin sulphate mix all gave statistically lower wear than bovine serum. The lubricants giving the closest wear results to bovine serum were 20 and 40 mg/mL egg white solutions. A light absorbance assay found that these egg white solutions suffered from a high degradation rate that increased with increasing protein content. While egg white solutions offer the best alternative lubricant to bovine serum due to the wear volumes produced, cost-effectiveness and safety of handling, protein degradation will still occur, leading to the need for regular lubricant replacement. Of the lubricants tested in this study, none were found to be superior to bovine serum.

  19. Succinimide lubricating oil dispersant

    SciTech Connect

    Wisotsky, M.J.; Bloch, R.; Brownwell, D.W.; Chen, F.J.; Gutierrez, A.

    1987-08-11

    A lubricating oil composition is described exhibiting improved dispersancy in both gasoline and diesel engines comprising a major amount of lubricating oil and 0.5 to 10 weight percent of a dispersant, the dispersant being prepared in a sequential process comprising the steps of: (a) in a first step reacting an oil-soluble polyolefin succinic anhydride, the olefin being a C/sub 3/ or C/sub 4/ olefin and an alkylene polyamine of the formula H/sub 2/N(CH/sub 2/)/sub n/(NH(CH/sub 2/)/sub n/)/sub m/sup -// NH/sub 2/ wherein n is 2 or 3 and m is 0 to 10, in a molar ratio of about 1.0 to 2.2 moles of polyolefin succinic anhydride per mole of polyamine, and (b) reacting the product of step (a) with dicarboxylic acid anhydride selected from the group consisting of maleic anhydride and succinic anhydride in sufficient molar proportions to provide a total mole ratio of about 2,3 to 3.0 moles of anhydride compounds per mole of polyamine.

  20. Potentiometer, constant tension and lubrication device

    NASA Technical Reports Server (NTRS)

    Smith, H. J.

    1972-01-01

    Wiper assembly is described for feedback potentiometers which provides self cleaning, self lubrication, and tension within controlled limits. Each end of the assembly contains loose fitting leather pad thoroughly soaked in wiper lubricating fluid. Cleaning and lubrication of potentiometer resulting from use of lubrication soaked leather accomplishes noise free operation.

  1. Interdisciplinary Approach to Liquid Lubricant Technology

    NASA Technical Reports Server (NTRS)

    Ku, P. M. (Editor)

    1973-01-01

    The proceedings of a conference of liquid lubricant technology are presented. The subjects discussed are: (1) requirements and functions of liquid lubricants, (2) mineral oils, (3) greases, (4) theory of rheology, (5) mechanics and thermodynamics in lubrication, (6) environmental capability of liquid lubricants, and (7) wear corrosion and erosion.

  2. Automotive gear oil lubricant from soybean oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of lubricants that are based on renewable materials is rapidly increasing. Vegetable oils have good lubricity, wear protection and low volatility which are desired properties for automotive gear lubricant applications. Soybean oil is used widely in the lubricant industry due to its properti...

  3. Re-analysis procedure based on the mixed formulation

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Peters, Jeanne M.

    1987-01-01

    An analysis procedure is presented for large-scale structural systems, with large numbers of degrees of freedom and design variables. The procedure uses a mixed formulation with the fundamental unknowns consisting of both stress and displacement parameters. Other elements of the procedure include: (1) lumping the design variables into a single tracing parameter; (2) operator splitting or additive decomposition of different arrays in the finite element equations into the corresponding arrays of the original structure plus correction terms; and (3) application of a reduction method through the use of the finite element method and the classical Bubnov-Galerkin technique. The re-analysis procedure is applied to the linear static and free vibration problems of plate and shell structures.

  4. Mixed Spectrum Analysis on fMRI Time-Series.

    PubMed

    Kumar, Arun; Lin, Feng; Rajapakse, Jagath C

    2016-06-01

    Temporal autocorrelation present in functional magnetic resonance image (fMRI) data poses challenges to its analysis. The existing approaches handling autocorrelation in fMRI time-series often presume a specific model of autocorrelation such as an auto-regressive model. The main limitation here is that the correlation structure of voxels is generally unknown and varies in different brain regions because of different levels of neurogenic noises and pulsatile effects. Enforcing a universal model on all brain regions leads to bias and loss of efficiency in the analysis. In this paper, we propose the mixed spectrum analysis of the voxel time-series to separate the discrete component corresponding to input stimuli and the continuous component carrying temporal autocorrelation. A mixed spectral analysis technique based on M-spectral estimator is proposed, which effectively removes autocorrelation effects from voxel time-series and identify significant peaks of the spectrum. As the proposed method does not assume any prior model for the autocorrelation effect in voxel time-series, varying correlation structure among the brain regions does not affect its performance. We have modified the standard M-spectral method for an application on a spatial set of time-series by incorporating the contextual information related to the continuous spectrum of neighborhood voxels, thus reducing considerably the computation cost. Likelihood of the activation is predicted by comparing the amplitude of discrete component at stimulus frequency of voxels across the brain by using normal distribution and modeling spatial correlations among the likelihood with a conditional random field. We also demonstrate the application of the proposed method in detecting other desired frequencies.

  5. Theoretical analysis of mixing in liquid clouds - Part 3: Inhomogeneous mixing

    NASA Astrophysics Data System (ADS)

    Pinsky, Mark; Khain, Alexander; Korolev, Alexei

    2016-07-01

    An idealized diffusion-evaporation model of time-dependent mixing between a cloud volume and a droplet-free volume is analyzed. The initial droplet size distribution (DSD) in the cloud volume is assumed to be monodisperse. It is shown that evolution of the microphysical variables and the final equilibrium state are unambiguously determined by two non-dimensional parameters. The first one is the potential evaporation parameter R, proportional to the ratio of the saturation deficit to the liquid water content in the cloud volume, that determines whether the equilibrium state is reached at 100 % relative humidity, or is characterized by a complete evaporation of cloud droplets. The second parameter Da is the Damkölher number equal to the ratio of the characteristic mixing time to the phase relaxation time. Parameters R and Da determine the type of mixing.The results are analyzed within a wide range of values of R and Da. It is shown that there is no pure homogeneous mixing, since the first mixing stage is always inhomogeneous. The mixing type can change during the mixing process. Any mixing type leads to formation of a tail of small droplets in DSD and, therefore, to DSD broadening that depends on Da. At large Da, the final DSD dispersion can be as large as 0.2. The total duration of mixing varies from several to 100 phase relaxation time periods, depending on R and Da.The definitions of homogeneous and inhomogeneous types of mixing are reconsidered and clarified, enabling a more precise delimitation between them. The paper also compares the results obtained with those based on the classic mixing concepts. >

  6. Lubricant Rheology in Concentrated Contacts

    NASA Technical Reports Server (NTRS)

    Jacobson, B. O.

    1984-01-01

    Lubricant behavior in highly stressed situtations shows that a Newtonian model for lubricant rheology is insufficient for explanation of traction behavior. The oil film build up is predicted by using a Newtonian lubricant model except at high slide to roll ratios and at very high loads, where the nonNewtonian behavior starts to be important already outside the Hertzian contact area. Static and dynamic experiments are reported. In static experiments the pressure is applied to the lubricant more than a million times longer than in an EHD contact. Depending on the pressure-temperature history of the experiment the lubricant will become a crystallized or amorphous solid at high pressures. In dynamic experiments, the oil is in an amorphous solid state. Depending on the viscosity, time scale, elasticity of the oil and the bearing surfaces, the oil film pressure, shear strain rate and the type of lubricant, different properties of the oil are important for prediction of shear stresses in the oil. The different proposed models for the lubricant, which describe it to a Newtonian liquid, an elastic liquid, a plastic liquid and an elastic-plastic solid.

  7. Analysis of mixed model in gear transmission based on ADAMS

    NASA Astrophysics Data System (ADS)

    Li, Xiufeng; Wang, Yabin

    2012-09-01

    The traditional method of mechanical gear driving simulation includes gear pair method and solid to solid contact method. The former has higher solving efficiency but lower results accuracy; the latter usually obtains higher precision of results while the calculation process is complex, also it is not easy to converge. Currently, most of the researches are focused on the description of geometric models and the definition of boundary conditions. However, none of them can solve the problems fundamentally. To improve the simulation efficiency while ensure the results with high accuracy, a mixed model method which uses gear tooth profiles to take the place of the solid gear to simulate gear movement is presented under these circumstances. In the process of modeling, build the solid models of the mechanism in the SolidWorks firstly; Then collect the point coordinates of outline curves of the gear using SolidWorks API and create fit curves in Adams based on the point coordinates; Next, adjust the position of those fitting curves according to the position of the contact area; Finally, define the loading conditions, boundary conditions and simulation parameters. The method provides gear shape information by tooth profile curves; simulates the mesh process through tooth profile curve to curve contact and offer mass as well as inertia data via solid gear models. This simulation process combines the two models to complete the gear driving analysis. In order to verify the validity of the method presented, both theoretical derivation and numerical simulation on a runaway escapement are conducted. The results show that the computational efficiency of the mixed model method is 1.4 times over the traditional method which contains solid to solid contact. Meanwhile, the simulation results are more closely to theoretical calculations. Consequently, mixed model method has a high application value regarding to the study of the dynamics of gear mechanism.

  8. A Case Study of a Mixed Methods Study Engaged in Integrated Data Analysis

    ERIC Educational Resources Information Center

    Schiazza, Daniela Marie

    2013-01-01

    The nascent field of mixed methods research has yet to develop a cohesive framework of guidelines and procedures for mixed methods data analysis (Greene, 2008). To support the field's development of analytical frameworks, this case study reflects on the development and implementation of a mixed methods study engaged in integrated data analysis.…

  9. Solid Lubrication Fundamentals and Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2001-01-01

    Solid Lubrication Fundamentals and Applications description of the adhesion, friction, abrasion, and wear behavior of solid film lubricants and related tribological materials, including diamond and diamond-like solid films. The book details the properties of solid surfaces, clean surfaces, and contaminated surfaces as well as discussing the structures and mechanical properties of natural and synthetic diamonds; chemical-vapor-deposited diamond film; surface design and engineering toward wear-resistant, self-lubricating diamond films and coatings. The author provides selection and design criteria as well as applications for synthetic and natural coatings in the commercial, industrial and aerospace industries..

  10. Lubricant effects on bearing life

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1986-01-01

    Lubricant considerations for rolling-element bearings have within the last two decades taken on added importance in the design and operation of mechanical systems. The phenomenon which limits the useful life of bearings is rolling-element or surface pitting fatigue. The elastohydrodynamic (EHD) film thickness which separates the ball or roller surface from those of the raceways of the bearing directly affects bearing life. Chemical additives added to the lubricant can also significantly affect bearings life and reliability. The interaction of these physical and chemical effects is important to the design engineer and user of these systems. Design methods and lubricant selection for rolling-element bearings are presented and discussed.

  11. Characteristics of wax extracted from lubricant basestocks

    SciTech Connect

    Guzauskas, J.F.; Abbott, F.P.; Baumgartner, N.R.

    1994-04-01

    This report describes a process for characterizing wax extracted from lubricant basestocks. The authors chose seven basestocks coming from different global regions and having a wide range of low-temperature properties. The wax was extracted from each basestock at-40{degrees}C using a cold-filtering method. Gas chromatography/mass spectroscopy (GC/MS), differential scanning calorimetry (DSC), thermal mechanical analysis (TMA), and optical microscopy (OM) were used to characterize these waxes. These data were compared to each basestock/s viscosity, pour point, and borderline pumping temperature, and some correlations were found between the wax characteristics and the cold temperature properties of the basestocks. This method of characterization can be useful when trying to select the optimal pour point depressant for engine lubricants. 10 refs., 24 figs., 5 tabs.

  12. Water lubricates hydrogen-bonded molecular machines

    NASA Astrophysics Data System (ADS)

    Panman, Matthijs R.; Bakker, Bert H.; den Uyl, David; Kay, Euan R.; Leigh, David A.; Buma, Wybren Jan; Brouwer, Albert M.; Geenevasen, Jan A. J.; Woutersen, Sander

    2013-11-01

    The mechanical behaviour of molecular machines differs greatly from that of their macroscopic counterparts. This applies particularly when considering concepts such as friction and lubrication, which are key to optimizing the operation of macroscopic machinery. Here, using time-resolved vibrational spectroscopy and NMR-lineshape analysis, we show that for molecular machinery consisting of hydrogen-bonded components the relative motion of the components is accelerated strongly by adding small amounts of water. The translation of a macrocycle along a thread and the rotation of a molecular wheel around an axle both accelerate significantly on the addition of water, whereas other protic liquids have much weaker or opposite effects. We tentatively assign the superior accelerating effect of water to its ability to form a three-dimensional hydrogen-bond network between the moving parts of the molecular machine. These results may indicate a more general phenomenon that helps explain the function of water as the ‘lubricant of life’.

  13. Water lubricates hydrogen-bonded molecular machines.

    PubMed

    Panman, Matthijs R; Bakker, Bert H; den Uyl, David; Kay, Euan R; Leigh, David A; Buma, Wybren Jan; Brouwer, Albert M; Geenevasen, Jan A J; Woutersen, Sander

    2013-11-01

    The mechanical behaviour of molecular machines differs greatly from that of their macroscopic counterparts. This applies particularly when considering concepts such as friction and lubrication, which are key to optimizing the operation of macroscopic machinery. Here, using time-resolved vibrational spectroscopy and NMR-lineshape analysis, we show that for molecular machinery consisting of hydrogen-bonded components the relative motion of the components is accelerated strongly by adding small amounts of water. The translation of a macrocycle along a thread and the rotation of a molecular wheel around an axle both accelerate significantly on the addition of water, whereas other protic liquids have much weaker or opposite effects. We tentatively assign the superior accelerating effect of water to its ability to form a three-dimensional hydrogen-bond network between the moving parts of the molecular machine. These results may indicate a more general phenomenon that helps explain the function of water as the 'lubricant of life'.

  14. Prediction of lubrication regimes in wrist implants with spherical bearing surfaces.

    PubMed

    Pylios, T; Shepherd, D E T

    2004-03-01

    The wrist joint is frequently affected by rheumatoid arthritis, resulting in wrist pain, deformity and ultimately loss of function. Artificial wrist implants have been introduced to treat the rheumatoid wrist, to attempt to alleviate pain and restore some function to the joint. The aim of this study was to predict the likely lubrication regimes that occur in wrist implants with spherical bearing surfaces. The implant was modelled as an equivalent ball-on-plane. Elastohydrodynamic lubrication theory was used to determine the minimum film thickness for the implant under different load, entraining velocity, lubricant viscosity, size of implant and material combinations. The results show that the highest film thickness is found in large implants, with high viscosity, high entraining velocity and low load. Hard-on-soft material combinations will operate with a boundary lubrication regime. Material combinations involving ceramic bearing surfaces have the potential to operate with a mixed lubrication regime.

  15. Ultrasmooth submicrometer carbon spheres as lubricant additives for friction and wear reduction.

    PubMed

    Alazemi, Abdullah A; Etacheri, Vinodkumar; Dysart, Arthur D; Stacke, Lars-Erik; Pol, Vilas G; Sadeghi, Farshid

    2015-03-11

    Ultrasmooth submicrometer carbon spheres are demonstrated as an efficient additive for improving the tribological performance of lubricating oils. Carbon spheres with ultrasmooth surfaces are fabricated by ultrasound assisted polymerization of resorcinol and formaldehyde followed by controlled heat treatment. The tribological behavior of the new lubricant mixture is investigated in the boundary and mixed lubrication regimes using a pin-on-disk apparatus and cylinder-on-disk tribometer, respectively. The new lubricant composition containing 3 wt % carbon spheres suspended in a reference SAE 5W30 engine oil exhibited a substantial reduction in friction and wear (10-25%) compared to the neat oil, without change in the viscosity. Microscopic and spectroscopic investigation of the carbon spheres after the tribological experiments illustrated their excellent mechanical and chemical stability. The significantly better tribological performance of the hybrid lubricant is attributed to the perfectly spherical shape and ultrasmooth surface of carbon sphere additive filling the gap between surfaces and acting as a nanoscale ball bearing.

  16. Optical microsystem for analyzing engine lubricants

    NASA Astrophysics Data System (ADS)

    Scott, Andrew J.; Mabesa, Jose R., Jr.; Gorsich, David; Rathgeb, Brian; Said, Ali A.; Dugan, Mark; Haddock, Tom F.; Bado, Philippe W.

    2004-12-01

    It is possible to dramatically improve the performance, reliability, and maintainability of vehicles and other similarly complex equipment if improved sensing and diagnostics systems are available. Each year military and commercial maintenance personnel unnecessarily replace, at scheduled intervals, significant amounts of lubricant fluids in vehicles, weapon systems, and supporting equipment. Personnel draw samples of fluids and send them to test labs for analysis to determine if replacement is necessary. Systematic use of either on-board (embedded) lubricant quality analysis capabilities will save millions of dollars each year in avoided fluid changes, saved labor, prevented damage to mechanical components while providing associated environmental benefits. This paper discusses the design, the manufacturing, and the evaluation of robust optical sensors designed to monitor the condition of industrial fluids. The sensors reported are manufactured from bulk fused silica substrates. They incorporate three-dimensional micro fluidic circuitry side-by-side with three-dimensional wave guided optical networks. The manufacturing of the optical waveguides are completed using a direct-write process based on the use of femtosecond laser pulses to locally alter the structure of the glass substrate at the nano-level. The microfluidic circuitry is produced using the same femtosecond laser based process, followed by an anisotropic wet chemical etching step. Data will be presented regarding the use of these sensors to monitor the quality of engine oil and possibly some other vehicle lubricants such as hydraulic oil.

  17. Dielectric analysis of heterogeneous biological tissues based on mixing rule.

    PubMed

    Zhang, Liang; Liu, Peiguo; Dong, Xiuzhen; Zhou, Dongming; Shi, Xuetao

    2015-01-01

    Thus far, the measurement of dielectric properties of biological tissues has been achieved on the assumption that the biological tissues are homogeneous. In fact, most tissues should be heterogeneous because there are many small structures included in these tissues, such as blood vessel, nerve fiber and so on. When the dielectric properties of these tissues are measured by conventional sensor, the results are not the dielectric properties of tissues but the effective dielectric properties of the mixture. In this paper, the influence of the inclusion in tissues on the measurement of dielectric properties of heterogeneous biological tissues is studied and the analysis of the effective dielectric properties of heterogeneous tissues based on the mixing rule is proposed. When the coaxial probe is used to measure the dielectric properties of tissue, the results are relative to the dielectric properties of inclusion, dielectric properties of background tissue and the effective volume fraction of inclusion. Therefore, the dielectric properties of inclusion could be calculated according to mixing rule, after the effective dielectric properties are measured and the effective volume fraction of inclusion is estimated.

  18. Validity of moyers mixed dentition analysis for Saudi population

    PubMed Central

    Al-Dlaigan, Yousef H.; Alqahtani, Nasser D.; Almoammar, Khalid; Al-Jewair, Thikriat; Salamah, Fahad Bin; Alswilem, Mohamme; Albarakati, Sahar F.

    2015-01-01

    Objectives: To evaluate the applicability of Moyers probability tables and to formulate more accurate mixed dentition prediction tables in the Saudi population. Methods: A cross-sectional study was conducted at the College of Dentistry, Kind Saud University, Saudi Arabia. The data were collected from 410 (203 males and 207 females) orthodontic study models, which had erupted mandibular permanent incisors, maxillary, mandibular canines and premolars. The mesiodistal widths were measured using a digital caliper with an accuracy of 0.01 mm. Student’s paired t-test was used to compare the mean width values derived from this study with the values derived using the Moyers table. Simple linear regression was used to evaluate the linear relationship between the combined mesiodistal widths of the mandibular permanent incisors and the canine-premolar segments in each dental arch. Results: The regression equations for the maxillary canine-premolar segment (males: Y=10.27+0.48X; females: Y=11.71 + 0.39X) and the mandibular canine-premolar segment (males: Y=9.71 + 0.40X; females: 11.28 + 0.39X) were used to formulate new probability tables on the Moyers pattern. Statistically significant differences were observed between predicted widths in our subjects and the widths obtained using Moyers tables. Conclusions: The new prediction tables derived in this study provided a more precise mixed dentition space analysis than Moyers prediction tables in estimating tooth dimensions in the Saudi population. PMID:26870104

  19. Dielectric analysis of heterogeneous biological tissues based on mixing rule.

    PubMed

    Zhang, Liang; Liu, Peiguo; Dong, Xiuzhen; Zhou, Dongming; Shi, Xuetao

    2015-01-01

    Thus far, the measurement of dielectric properties of biological tissues has been achieved on the assumption that the biological tissues are homogeneous. In fact, most tissues should be heterogeneous because there are many small structures included in these tissues, such as blood vessel, nerve fiber and so on. When the dielectric properties of these tissues are measured by conventional sensor, the results are not the dielectric properties of tissues but the effective dielectric properties of the mixture. In this paper, the influence of the inclusion in tissues on the measurement of dielectric properties of heterogeneous biological tissues is studied and the analysis of the effective dielectric properties of heterogeneous tissues based on the mixing rule is proposed. When the coaxial probe is used to measure the dielectric properties of tissue, the results are relative to the dielectric properties of inclusion, dielectric properties of background tissue and the effective volume fraction of inclusion. Therefore, the dielectric properties of inclusion could be calculated according to mixing rule, after the effective dielectric properties are measured and the effective volume fraction of inclusion is estimated. PMID:26406034

  20. Analysis of monoclonal antibody oxidation by simple mixed mode chromatography.

    PubMed

    Pavon, Jorge Alexander; Li, Xiaojuan; Chico, Steven; Kishnani, Umesh; Soundararajan, Soundara; Cheung, Jason; Li, Huijuan; Richardson, Daisy; Shameem, Mohammed; Yang, Xiaoyu

    2016-01-29

    Analysis of oxidation of monoclonal antibodies (mAbs) in most cases relies on peptide mapping and LC-MS, which is time consuming and labor-intensive. A robust chromatography based method that is able to resolve and quantitate mAb oxidation variants due to oxidized methionine or tryptophan is highly desired. Here we developed a novel mixed mode chromatography method using the unique property of Sepax Zenix SEC-300MK column to analyze mAb oxidation levels. The separation of oxidized species relied upon the mixed mode of size exclusion and hydrophobic interaction between the resin and antibodies. The chromatography was performed in a regular SEC mobile phase, PBS, containing NaCl at a concentration (0-2.4M) specific for individual antibodies. This method was able to resolve and quantitate the oxidized antibodies as prepeaks, of either methionine-oxidized species induced by the common oxidants TBHP, tryptophan-oxidized species triggered by AAPH, or oxidized species by UV photo-irradiation. The prepeaks were further characterized by SEC-MALLS as monomers and confirmed by LC-MS as oxidized antibody variants with a mass increase of 16 or 32Da. This method has been successfully applied to monitor multiple monoclonal antibodies of IgG1, IgG2, and IgG4 subclasses. PMID:26774436

  1. Emergency and microfog lubrication and cooling of bearings for Army helicopters

    NASA Technical Reports Server (NTRS)

    Rosenlieb, J. W.

    1978-01-01

    An analysis and system study was performed to provide design information regarding lubricant and coolant flow rates and flow paths for effective utilization of the lubricant and coolant in a once-through oil-mist (microfog) and coolant air system. A system was designed, manufactured, coupled with an existing rig and evaluation tests were performed using 46 mm bore split-inner angular-contact ball bearings under 1779N (400 lb.) thrust load. An emergency lubrication aspirator system was also manufactured and tested under lost lubricant conditions. The testing demonstrated the feasibility of using a mist oil and cooling air system to lubricate and cool a high speed helicopter engine mainshaft bearing. The testing also demonstrated the feasibility of using an emergency aspirator lubrication system as a viable survivability concept for helicopter mainshaft engine bearing for periods as long as 30 minutes.

  2. Analysis of mixed-layer clay mineral structures

    USGS Publications Warehouse

    Bradley, W.F.

    1953-01-01

    Among the enormously abundant natural occurrences of clay minerals, many examples are encountered in which no single specific crystallization scheme extends through a single ultimate grain. The characterization of such assemblages becomes an analysis of the distribution of matter within such grains, rather than the simple identification of mineral species. It having become established that the particular coordination complex typified by mica is a common component of many natural subcrystalline assemblages, the opportunity is afforded to analyze scattering from random associations of these complexes with other structural units. Successful analyses have been made of mixed hydration states of montmorillonite, of montmorillonite with mica, of vermiculite with mica, and of montmorillonite with chlorite, all of which are variants of the mica complex, and of halloysite with hydrated halloysite.

  3. Environmentally friendly and biobased lubricants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biobased and environmentally friendly lubricants are finding applications in many areas ranging from hydraulic fluids to grease. They offer excellent biodegradability and very low ecotoxicity; high viscosity index; improved tribological properties; lower volatility and flash points relative to petro...

  4. Friction laws for lubricated nanocontacts

    NASA Astrophysics Data System (ADS)

    Buzio, R.; Boragno, C.; Valbusa, U.

    2006-09-01

    We have used friction force microscopy to probe friction laws for nanoasperities sliding on atomically flat substrates under controlled atmosphere and liquid environment, respectively. A power law relates friction force and normal load in dry air, whereas a linear relationship, i.e., Amontons' law, is observed for junctions fully immersed in model lubricants, namely, octamethylciclotetrasiloxane and squalane. Lubricated contacts display a remarkable friction reduction, with liquid and substrate specific friction coefficients. Comparison with molecular dynamics simulations suggests that load-bearing boundary layers at junction entrance cause the appearance of Amontons' law and impart atomic-scale character to the sliding process; continuum friction models are on the contrary of limited predictive power when applied to lubrication effects. An attempt is done to define general working conditions leading to the manifestation of nanoscale lubricity due to adsorbed boundary layers.

  5. Structural lubricity under ambient conditions

    PubMed Central

    Cihan, Ebru; İpek, Semran; Durgun, Engin; Baykara, Mehmet Z.

    2016-01-01

    Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (∼4,000–130,000 nm2) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold–graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro- and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions. PMID:27350035

  6. Self-lubricating composite materials

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1980-01-01

    The mechanical properties of two types of self lubricating composites (polymer matrix composites and inorganic composites) are discussed. Specific emphasis is given to the applicability of these composites in the aerospace industry.

  7. Aviation-fuel lubricity evaluation

    SciTech Connect

    Not Available

    1988-07-01

    Fuel-system components have experienced problems with the slipperiness or lubricity of the fuel back to the early 1960's. As a consequence of the level of refinement necessary for the PWA 523 fuel (now designated MIL-T-38219 grade JP-7) to obtain its high-temperature stability, many of the polar compounds contributing to lubricity had been removed, resulting in abnormal hydraulic fuel-pump wear. A lubricity-enhancing compound was developed (PWA 536) to eliminate the wear problem. High-pressure piston-type fuel pumps were one of the first parts of the engine fuel system to exhibit problems related to fuel properties. One early problem manifested itself as corrosion of silver-plated slipper pads and was related to carryover of residual-chlorides fuel. Fuel controls were another part of the engine fuel system susceptible to fuel properties. Lack of lubricity agents caused fuel control sliding servo valves to stick.

  8. Structural lubricity under ambient conditions

    NASA Astrophysics Data System (ADS)

    Cihan, Ebru; Ipek, Semran; Durgun, Engin; Baykara, Mehmet Z.

    2016-06-01

    Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (~4,000-130,000 nm2) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold-graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro- and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions.

  9. Structural lubricity under ambient conditions.

    PubMed

    Cihan, Ebru; İpek, Semran; Durgun, Engin; Baykara, Mehmet Z

    2016-01-01

    Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (∼4,000-130,000 nm(2)) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold-graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro- and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions. PMID:27350035

  10. Determination of physical and chemical states of lubricants in concentrated contacts, part 2

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.

    1981-01-01

    Infrared emission spectroscopy through a window in an operating bearing continued to provide most of the information gathered on the state of lubricants subjected to elastohydrodynamic (EHD) conditions. Other measurements were traction, scanning electron microscopy and elemental surface analysis X-rays. A very significant finding was the decomposition of a naphthenic oil lubricant in the presence of small concentrations of an organic chloride. Olefins and aromatics were formed in ever increasing amounts prior to total lubricant failure. An aromatic fluid also failed in the presence of chloride. A correlation was found between changes of the alignment of lubricant molecules evidence by infrared polarization and changes of traction under varying EHD stresses.

  11. Method for lubricating contacting surfaces

    SciTech Connect

    Dugger, Michael T.; Ohlhausen, James A.; Asay, David B.; Kim, Seong H.

    2011-12-06

    A method is provided for tribological lubrication of sliding contact surfaces, where two surfaces are in contact and in motion relative to each other, operating in a vapor-phase environment containing at least one alcohol compound at a concentration sufficiently high to provide one monolayer of coverage on at least one of the surfaces, where the alcohol compound continuously reacts at the surface to provide lubrication.

  12. Mixed-culture transcriptome analysis reveals the molecular basis of mixed-culture growth in Streptococcus thermophilus and Lactobacillus bulgaricus.

    PubMed

    Sieuwerts, Sander; Molenaar, Douwe; van Hijum, Sacha A F T; Beerthuyzen, Marke; Stevens, Marc J A; Janssen, Patrick W M; Ingham, Colin J; de Bok, Frank A M; de Vos, Willem M; van Hylckama Vlieg, Johan E T

    2010-12-01

    Many food fermentations are performed using mixed cultures of lactic acid bacteria. Interactions between strains are of key importance for the performance of these fermentations. Yogurt fermentation by Streptococcus thermophilus and Lactobacillus bulgaricus (basonym, Lactobacillus delbrueckii subsp. bulgaricus) is one of the best-described mixed-culture fermentations. These species are believed to stimulate each other's growth by the exchange of metabolites such as folic acid and carbon dioxide. Recently, postgenomic studies revealed that an upregulation of biosynthesis pathways for nucleotides and sulfur-containing amino acids is part of the global physiological response to mixed-culture growth in S. thermophilus, but an in-depth molecular analysis of mixed-culture growth of both strains remains to be established. We report here the application of mixed-culture transcriptome profiling and a systematic analysis of the effect of interaction-related compounds on growth, which allowed us to unravel the molecular responses associated with batch mixed-culture growth in milk of S. thermophilus CNRZ1066 and L. bulgaricus ATCC BAA-365. The results indicate that interactions between these bacteria are primarily related to purine, amino acid, and long-chain fatty acid metabolism. The results support a model in which formic acid, folic acid, and fatty acids are provided by S. thermophilus. Proteolysis by L. bulgaricus supplies both strains with amino acids but is insufficient to meet the biosynthetic demands for sulfur and branched-chain amino acids, as becomes clear from the upregulation of genes associated with these amino acids in mixed culture. Moreover, genes involved in iron uptake in S. thermophilus are affected by mixed-culture growth, and genes coding for exopolysaccharide production were upregulated in both organisms in mixed culture compared to monocultures. The confirmation of previously identified responses in S. thermophilus using a different strain combination

  13. Simulation Analysis for HB-Line Dissolver Mixing

    SciTech Connect

    Lee, S

    2006-03-22

    In support of the HB-Line Engineering agitator mixing project, flow pattern calculations have been made for a 90{sup o} apart and helical pitch agitator submerged in a flat tank containing dissolver baskets. The work is intended to determine maximum agitator speed to keep the dissolver baskets from contacting the agitator for the nominal tank liquid level. The analysis model was based on one dissolver basket located on the bottom surface of the flat tank for a conservative estimate. The modeling results will help determine acceptable agitator speeds and tank liquid levels to ensure that the dissolver basket is kept from contacting the agitator blade during HB-Line dissolver tank operations. The numerical modeling and calculations have been performed using a computational fluid dynamics approach. Three-dimensional steady-state momentum and continuity equations were used as the basic equations to estimate fluid motion driven by an agitator with four 90{sup o} pitched blades or three flat blades. Hydraulic conditions were fully turbulent (Reynolds number about 1 x 10{sup 5}). A standard two-equation turbulence model ({kappa},{var_epsilon}), was used to capture turbulent eddy motion. The commercial finite volume code, Fluent [5], was used to create a prototypic geometry file with a non-orthogonal mesh. Hybrid meshing was used to fill the computational region between the round-edged tank bottom and agitator regions. The nominal calculations and a series of sensitivity runs were made to investigate the impact of flow patterns on the lifting behavior of the dissolver basket. At high rotational speeds and low tank levels, local turbulent flow reaches the critical condition for the dissolver basket to be picked up from the tank floor and to touch the agitator blades during the tank mixing operations. This is not desirable in terms of mixing performance. The modeling results demonstrate that the flow patterns driven by the agitators considered here are not strong enough to

  14. Bisexuality, poverty and mental health: A mixed methods analysis.

    PubMed

    Ross, Lori E; O'Gorman, Laurel; MacLeod, Melissa A; Bauer, Greta R; MacKay, Jenna; Robinson, Margaret

    2016-05-01

    Bisexuality is consistently associated with poor mental health outcomes. In population-based data, this is partially explained by income differences between bisexual people and lesbian, gay, and/or heterosexual individuals. However, the interrelationships between bisexuality, poverty, and mental health are poorly understood. In this paper, we examine the relationships between these variables using a mixed methods study of 302 adult bisexuals from Ontario, Canada. Participants were recruited using respondent-driven sampling to complete an internet-based survey including measures of psychological distress and minority stress. A subset of participants completed a semi-structured qualitative interview to contextualize their mental health experiences. Using information regarding household income, number of individuals supported by the income and geographic location, participants were categorized as living below or above the Canadian Low Income Cut Off (LICO). Accounting for the networked nature of the sample, participants living below the LICO had significantly higher mean scores for depression and posttraumatic stress disorder symptoms and reported significantly more perceived discrimination compared to individuals living above the LICO. Grounded theory analysis of the qualitative interviews suggested four pathways through which bisexuality and poverty may intersect to impact mental health: through early life experiences linked to bisexuality or poverty that impacted future financial stability; through effects of bisexual identity on employment and earning potential; through the impact of class and sexual orientation discrimination on access to communities of support; and through lack of access to mental health services that could provide culturally competent care. These mixed methods data help us understand the income disparities associated with bisexual identity in population-based data, and suggest points of intervention to address their impact on bisexual mental

  15. Bisexuality, poverty and mental health: A mixed methods analysis.

    PubMed

    Ross, Lori E; O'Gorman, Laurel; MacLeod, Melissa A; Bauer, Greta R; MacKay, Jenna; Robinson, Margaret

    2016-05-01

    Bisexuality is consistently associated with poor mental health outcomes. In population-based data, this is partially explained by income differences between bisexual people and lesbian, gay, and/or heterosexual individuals. However, the interrelationships between bisexuality, poverty, and mental health are poorly understood. In this paper, we examine the relationships between these variables using a mixed methods study of 302 adult bisexuals from Ontario, Canada. Participants were recruited using respondent-driven sampling to complete an internet-based survey including measures of psychological distress and minority stress. A subset of participants completed a semi-structured qualitative interview to contextualize their mental health experiences. Using information regarding household income, number of individuals supported by the income and geographic location, participants were categorized as living below or above the Canadian Low Income Cut Off (LICO). Accounting for the networked nature of the sample, participants living below the LICO had significantly higher mean scores for depression and posttraumatic stress disorder symptoms and reported significantly more perceived discrimination compared to individuals living above the LICO. Grounded theory analysis of the qualitative interviews suggested four pathways through which bisexuality and poverty may intersect to impact mental health: through early life experiences linked to bisexuality or poverty that impacted future financial stability; through effects of bisexual identity on employment and earning potential; through the impact of class and sexual orientation discrimination on access to communities of support; and through lack of access to mental health services that could provide culturally competent care. These mixed methods data help us understand the income disparities associated with bisexual identity in population-based data, and suggest points of intervention to address their impact on bisexual mental

  16. Fire hazard analysis of the radioactive mixed waste trenchs

    SciTech Connect

    McDonald, K.M.

    1995-04-27

    This Fire Hazards Analysis (FHA) is intended to assess comprehensively the risk from fire associated with the disposal of low level radioactive mixed waste in trenches within the lined landfills, provided by Project W-025, designated Trench 31 and 34 of the Burial Ground 218-W-5. Elements within the FHA make recommendations for minimizing risk to workers, the public, and the environment from fire during the course of the operation`s activity. Transient flammables and combustibles present that support the operation`s activity are considered and included in the analysis. The graded FHA contains the following elements: description of construction, protection of essential safety class equipment, fire protection features, description of fire hazards, life safety considerations, critical process equipment, high value property, damage potential--maximum credible fire loss (MCFL) and maximum possible fire loss (MPFL), fire department/brigade response, recovery potential, potential for a toxic, biological and/or radiation incident due to a fire, emergency planning, security considerations related to fire protection, natural hazards (earthquake, flood, wind) impact on fire safety, and exposure fire potential, including the potential for fire spread between fire areas. Recommendations for limiting risk are made in the text of this report and printed in bold type. All recommendations are repeated in a list in Section 18.0.

  17. Mixed-effects Poisson regression analysis of adverse event reports

    PubMed Central

    Gibbons, Robert D.; Segawa, Eisuke; Karabatsos, George; Amatya, Anup K.; Bhaumik, Dulal K.; Brown, C. Hendricks; Kapur, Kush; Marcus, Sue M.; Hur, Kwan; Mann, J. John

    2008-01-01

    SUMMARY A new statistical methodology is developed for the analysis of spontaneous adverse event (AE) reports from post-marketing drug surveillance data. The method involves both empirical Bayes (EB) and fully Bayes estimation of rate multipliers for each drug within a class of drugs, for a particular AE, based on a mixed-effects Poisson regression model. Both parametric and semiparametric models for the random-effect distribution are examined. The method is applied to data from Food and Drug Administration (FDA)’s Adverse Event Reporting System (AERS) on the relationship between antidepressants and suicide. We obtain point estimates and 95 per cent confidence (posterior) intervals for the rate multiplier for each drug (e.g. antidepressants), which can be used to determine whether a particular drug has an increased risk of association with a particular AE (e.g. suicide). Confidence (posterior) intervals that do not include 1.0 provide evidence for either significant protective or harmful associations of the drug and the adverse effect. We also examine EB, parametric Bayes, and semiparametric Bayes estimators of the rate multipliers and associated confidence (posterior) intervals. Results of our analysis of the FDA AERS data revealed that newer antidepressants are associated with lower rates of suicide adverse event reports compared with older antidepressants. We recommend improvements to the existing AERS system, which are likely to improve its public health value as an early warning system. PMID:18404622

  18. Solid Lubrication Fundamentals and Applications. Chapter 1; Introduction and Background

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1996-01-01

    This chapter presents an introduction and historical background to the field of tribology, especially solid lubrication and lubricants and sets them in the perspective of techniques and materials in lubrication. Also, solid and liquid lubrication films are defined and described.

  19. Solid Lubrication Fundamentals and Applications: Introduction and Background. Revision 1

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1998-01-01

    This chapter presents an introduction and historical background to the field of tribology, especially solid lubrication and lubricants and sets them in the perspective of techniques and materials in lubrication. Also, solid and liquid lubrication films are defined and described.

  20. The Structure of Mixed Method Studies in Educational Research: A Content Analysis

    ERIC Educational Resources Information Center

    Bryant, Lauren H.

    2011-01-01

    Educational researchers are beginning to use mixed methods designs to answer complex research questions. This content analysis investigates the structure and use of mixed methods in educational research in order to work toward a more standardized presentation. I used a concurrent mixed methods approach to analyze 30 studies from three prominent…

  1. Analysis of injury types for mixed martial arts athletes.

    PubMed

    Ji, MinJoon

    2016-05-01

    [Purpose] The purpose of the present study was to examine the types of injuries associated with mixed martial arts and their location in order to provide substantial information to help reduce the risk of these injuries during mixed martial arts. [Subjects and Methods] Data were collected from 455 mixed martial arts athletes who practiced mixed martial arts or who participated in mixed martial arts competitions in the Seoul Metropolitan City and Gyeongnam Province of Korea between June 3, 2015, and November 6, 2015. Questionnaires were used to collect the data. The convenience sampling method was used, based on the non-probability sampling extraction method. [Results] The arm, neck, and head were the most frequent locations of the injuries; and lacerations, concussions, and contusions were the most frequently diagnosed types of injuries in the mixed martial arts athletes in this study. [Conclusion] Reducing the risk of injury by establishing an alert system and preventing critical injuries by incorporating safety measures are important.

  2. Effects of Water in Synthetic Lubricant Systems and Clathrate Formation: A Literature Search and Review

    SciTech Connect

    Rohatgi, Ngoc Dung T.

    2001-08-08

    An extensive literature search and a confidential survey were critically analyzed to determine the effects of water on the stability of hydrofluorocarbon/synthetic lubricant systems and to identify key areas requiring further investigation. Following are highlights from the analysis: Clathrate hydrates are solid solutions formed when water molecules are linked through hydrogen bonding creating cavities that can enclose various guest molecules from hydrate formers, such as hydrofluorocarbons R-32, R-125, R-134a, R-407C and R-410A. The four methods for preventing clathrate formation were drying the gas, heating it, reducing its pressure, or using inhibitors. The hydrolysis of polyolester lubricants was mostly acid-catalyzed and its reaction rate constant typically followed the Arrhenius equation of an activated process. Hydrolytic stability improved with hindered molecular structures, and with the presence of acid catcher additives and desiccants. Water vapor can effect the adsorption of long-chain fatty acids and the chemistry of formation of protective oxide film. However, these effects on lubrication can be either positive or negative. Fifty to sixty percent of the moisture injected into an air-conditioning system remained in the refrigerant and the rest mixed with the compressor oil. In an automotive air-conditioning system using R-134a, ice would form at 0 C evaporating temperature when the water content in the vapor refrigerant on the low-pressure side was more than 350 ppm. Moisture would cause the embrittlement of polyethylene terephthalate and the hydrolysis of polyesters, but would reduce the effect of amine additives on fluoroelastomer rubbers. The reactions of water with refrigerants and lubricants would cause formicary and large-pit corrosion in copper tubes, as well as copper plating and sludge formation. Moreover, blockage of capillary tubes increased rapidly in the presence of water. Twenty-four companies responded to the survey. From the responses

  3. Engine lubrication circuit including two pumps

    DOEpatents

    Lane, William H.

    2006-10-03

    A lubrication pump coupled to the engine is sized such that the it can supply the engine with a predetermined flow volume as soon as the engine reaches a peak torque engine speed. In engines that operate predominately at speeds above the peak torque engine speed, the lubrication pump is often producing lubrication fluid in excess of the predetermined flow volume that is bypassed back to a lubrication fluid source. This arguably results in wasted power. In order to more efficiently lubricate an engine, a lubrication circuit includes a lubrication pump and a variable delivery pump. The lubrication pump is operably coupled to the engine, and the variable delivery pump is in communication with a pump output controller that is operable to vary a lubrication fluid output from the variable delivery pump as a function of at least one of engine speed and lubrication flow volume or system pressure. Thus, the lubrication pump can be sized to produce the predetermined flow volume at a speed range at which the engine predominately operates while the variable delivery pump can supplement lubrication fluid delivery from the lubrication pump at engine speeds below the predominant engine speed range.

  4. Piston ring thermal transient effects on lubricant temperatures in advanced engines

    SciTech Connect

    Boisclair, M.E.; Hoult, D.P.; Wong, V.W. )

    1989-07-01

    One class of advanced diesel engines operates with low heat rejection and high operating temperatures; piston-ring/linear lubrication is a major problem for these engines. This study attempts to illustrate the time-dependent thermal environment around the top piston ring and lubricant in these advanced engines. Particular emphasis is passed on the maximum lubricant temperature. The analysis starts with a standard cycle simulation and a global finite-element analysis of the piston and liner in relative motion. A more detailed finite-element model, which considers variable oil film thickness on the linear, focuses on the top ring and lubricant and uses the grove and linear temperatures generated in the global analysis as boundary conditions. Results for different heat rejection engine configurations are presented. The authors observe that because of major transient effects, high lubricant temperature is experienced not only at top ring reversal but also down the linear to bottom ring reversal.

  5. F-AREA PUMP TANK 1 MIXING ANALYSIS

    SciTech Connect

    Tamburello, D; Richard Dimenna, R; Si Lee, S

    2008-11-05

    The F-area pump tanks are used to transfer supernate, sludge, and other materials. In any transfer, the solution must stay well mixed without allowing particulate matter to settle out of the liquid and, thus, accumulate in the bottom of the pump tank. Recently, the pulse jet mixing in F-area Pump Tank 1 (FPT1) has been decommissioned. An analysis of the liquid transfer through FPT1 has been performed using computational fluid dynamics (CFD) methods to assess whether or not the velocities throughout the tank will remain high enough to keep all particulate suspended using only transfer and recirculation pumps. The following paragraph is an abbreviated synopsis of the transfer procedure for FPT1 [1, 2]. Prior to a transfer, FPT1 begins to be filled with inhibited water through the inlet transfer line (TI). When the tank liquid level reaches 52.5 inches above the absolute tank bottom, the recirculation pump (RI and RO) is activated. At a tank liquid level of 72.5 inches above the absolute tank bottom, the outlet transfer line (TO) is activated to reduce the liquid level in FPT1 and transfer inhibited water to H-area Pump Tank 7 (HPT7). The liquid level is reduced down to 39.5 inches, with an allowable range from 37.5 to 41.5 inches above the absolute tank bottom. HPT7 goes through a similar procedure as FPT1 until both have tank liquid levels of approximately 39.5 inches above the absolute tank bottom. The transfer of inhibited water continues until a steady-state has been reached in both pump tanks. At this point, the supernate/sludge transfer begins with a minimum flow rate of 70 gpm and an average flow rate of 150 gpm. After the transfer is complete, the pump tanks (both FPT1 and HPT7) are pumped down to between 20.5 and 22.5 inches (above absolute bottom) and then flushed with 25,000 gallons of inhibited water to remove any possible sludge heal. After the flushing, the pump tanks are emptied. Note that the tank liquid level is measured using diptubes. Figure 2

  6. Fabrication and Wear Behavior Analysis on AlCrFeNi High Entropy Alloy Coating Under Dry Sliding and Oil Lubrication Test Conditions

    NASA Astrophysics Data System (ADS)

    Tang, Yipin; Wang, Shouren; Sun, Bin; Wang, Yan; Qiao, Yang

    2016-03-01

    In this paper, AlCrFeNi high entropy alloy coating was fabricated on the surface of Q235 steel using hot pressing sintering process. The coating has the controlled thickness size and excellent mechanical properties. Scanning electron microscopy (SEM), XRD and hardness testing method were used to study the morphology, phase structure and hardness of high entropy alloys coating. The lattice distortion plays a significant role in increasing the hardness. Coating formation mechanism caused by the element diffusion under the hot pressing effect is also discussed in the paper. Simultaneously, the dry sliding and oil lubrication wear tests, wear morphology observation and wear mechanism discussion were completed. As the result shows, AlCrFeNi high entropy alloys coating exhibits superior wear resistance either at dry sliding or oil lubrication tests owing to its hard high entropy solid solution structure.

  7. Molecular-Scale Lubricants for Micromachine Applications: Final Report

    SciTech Connect

    Burns, A.R.; Dugger, M.T.; Houston, J.E.; Lopez, G.P.; Mayer, T.M.; Michalske, T.A.; Miller, S.L.; Sniegowski, J.J.; Stevens, M.J.; Zhou, Y.

    1998-12-01

    The nature of this work was to develop the physics and chemistry base for understanding molecular-scale lubricants used to reduce of friction- and adhesion-induced failure in silicon micromachines (MEMS). We acquired this new knowledge by tailoring the molecular properties of the lubricants, applying local probes that can directly monitor the response of lubricants in contact conditions, and evaluating the performance of model lubricants MEMS devices. Model lubricants under investigation were the silane coupling agents that form monolayer films on native oxide silicon surfaces, which is the substrate in MEMS. These molecules bind via strong surface bonds and produce a layer of hydro- or fluoro-carbon chains normal to the substrate. "Tailoring" the lubricants entails modifying the chain length, the chain chemical reactivity (H or F), and the density of chain structures. Thus much effort went into understanding the surface chemistry of silane-silicon oxide coupling. With proximal probes such as atomic force microscopy (AFM), interracial force microscopy (FM), and shear force microscopy in combination with IFM, we examined the frictional and adhesive properties of the silane films with very high spatial resolution (< 100 nm) and sensitivity. MEMS structures are treated with silanes under identical conditions, and examined for friction and adhesion under operating conditions. Proper assessment of the lubricants required quantitative analysis of MEMS performance at high speeds and long operating times. Our proximal probe measurements and WS performance analyses form a very important link for future molecular dynamics simulations, that, in turn, should be able to predict MEMS performance under all conditions.

  8. Obesity in social media: a mixed methods analysis.

    PubMed

    Chou, Wen-Ying Sylvia; Prestin, Abby; Kunath, Stephen

    2014-09-01

    The escalating obesity rate in the USA has made obesity prevention a top public health priority. Recent interventions have tapped into the social media (SM) landscape. To leverage SM in obesity prevention, we must understand user-generated discourse surrounding the topic. This study was conducted to describe SM interactions about weight through a mixed methods analysis. Data were collected across 60 days through SM monitoring services, yielding 2.2 million posts. Data were cleaned and coded through Natural Language Processing (NLP) techniques, yielding popular themes and the most retweeted content. Qualitative analyses of selected posts add insight into the nature of the public dialogue and motivations for participation. Twitter represented the most common channel. Twitter and Facebook were dominated by derogatory and misogynist sentiment, pointing to weight stigmatization, whereas blogs and forums contained more nuanced comments. Other themes included humor, education, and positive sentiment countering weight-based stereotypes. This study documented weight-related attitudes and perceptions. This knowledge will inform public health/obesity prevention practice.

  9. MIXREGLS: A Program for Mixed-Effects Location Scale Analysis.

    PubMed

    Hedeker, Donald; Nordgren, Rachel

    2013-03-01

    MIXREGLS is a program which provides estimates for a mixed-effects location scale model assuming a (conditionally) normally-distributed dependent variable. This model can be used for analysis of data in which subjects may be measured at many observations and interest is in modeling the mean and variance structure. In terms of the variance structure, covariates can by specified to have effects on both the between-subject and within-subject variances. Another use is for clustered data in which subjects are nested within clusters (e.g., clinics, hospitals, schools, etc.) and interest is in modeling the between-cluster and within-cluster variances in terms of covariates. MIXREGLS was written in Fortran and uses maximum likelihood estimation, utilizing both the EM algorithm and a Newton-Raphson solution. Estimation of the random effects is accomplished using empirical Bayes methods. Examples illustrating stand-alone usage and features of MIXREGLS are provided, as well as use via the SAS and R software packages. PMID:23761062

  10. MIXREGLS: A Program for Mixed-Effects Location Scale Analysis

    PubMed Central

    Hedeker, Donald; Nordgren, Rachel

    2013-01-01

    MIXREGLS is a program which provides estimates for a mixed-effects location scale model assuming a (conditionally) normally-distributed dependent variable. This model can be used for analysis of data in which subjects may be measured at many observations and interest is in modeling the mean and variance structure. In terms of the variance structure, covariates can by specified to have effects on both the between-subject and within-subject variances. Another use is for clustered data in which subjects are nested within clusters (e.g., clinics, hospitals, schools, etc.) and interest is in modeling the between-cluster and within-cluster variances in terms of covariates. MIXREGLS was written in Fortran and uses maximum likelihood estimation, utilizing both the EM algorithm and a Newton-Raphson solution. Estimation of the random effects is accomplished using empirical Bayes methods. Examples illustrating stand-alone usage and features of MIXREGLS are provided, as well as use via the SAS and R software packages. PMID:23761062

  11. Cost-Cutting Powdered Lubricant

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Scientists at NASA's Glenn Research Center developed a high-temperature, solid lubricant coating material that is saving the manufacturing industry millions of dollars. The material came out of 3 decades of tribological research, work studying high-temperature friction, lubrication, and the wearing of interacting surfaces that are in relative motion. It was developed as a shaft coating deposited by thermal spraying to protect foil air bearings used in oil-free turbomachinery, like gas turbines, and is meant to be part of a larger project: an oil-free aircraft engine capable of operating at high temperatures with increased reliability, lowered weight, reduced maintenance requirements, and increased power. This advanced coating, PS300, is a self-lubricating bearing material containing chromium oxide, with additions of a low-temperature start up lubricant (silver) and a high-temperature lubricant, making it remarkably stable at high temperatures, and better suited than previously available materials for high-stress conditions. It improves efficiency, lowers friction, reduces emissions, and has been used by NASA in advanced aeropropulsion engines, refrigeration compressors, turbochargers, and hybrid electrical turbogenerators. PS300 is ideal in any application where lowered weight and reduced maintenance are desired, and high-temperature uses and heavy operating speeds are expected. It has notable uses for the Space Agency, but it has even further-reaching potential for the industrial realm.

  12. The effect of lubrication on the friction and wear of Biolox®delta.

    PubMed

    Ma, L; Rainforth, W M

    2012-07-01

    The performance of total hip-joint replacements depends strongly on the state of lubrication in vivo. In order to test candidate prosthetic materials, in vitro wear testing requires a lubricant that behaves in the same manner as synovial fluid. The current study investigated three lubricants and looked in detail at the lubrication conditions and the consequent effect on ball-on-flat reciprocating wear mechanisms of Biolox®delta against alumina. Biolox®delta, the latest commercial material for artificial hip-joint replacements, is an alumina-matrix composite with improved mechanical properties through the addition of zirconia and other mixed oxides. Three commonly used laboratory lubricants, ultra pure water, 25 vol.% new-born calf serum solution and 1 wt.% carboxymethyl cellulose sodium salt (CMC-Na) solution, were used for the investigation. The lubrication regimes were defined by constructing Stribeck curves. Full fluid-film lubrication was observed for the serum solution whereas full fluid-film and mixed lubrications were observed in both water and the CMC-Na solution. The wear rates in the CMC-Na and new-born calf serum were similar, but were an order of magnitude higher in water. The worn surfaces all exhibited pitting, which is consistent with the transition from mild wear to severe or "stripe" wear. The extent of pitting was greatest in the serum solution, but least in the water. On all worn surfaces, the zirconia appeared to have fully transformed from tetragonal to monoclinic symmetry. However, there was no evidence of microcracking associated with the transformed zirconia. Nevertheless, AFM indicated that zirconia was lost preferentially to the alumina grains during sliding. Thus, the current study has shown conclusively that the wear mechanisms for Biolox®delta clearly depend on the lubricant used, even where wear rates were similar.

  13. Study of turbocharger shaft motion by means of non-invasive optical techniques: Application to the behaviour analysis in turbocharger lubrication failures

    NASA Astrophysics Data System (ADS)

    Pastor, J. V.; Serrano, J. R.; Dolz, V.; López, M. A.; Bouffaud, F.

    2012-10-01

    This paper presents a novel non-invasive technique to estimate the turbocharger shaft whirl motion. The aim of this article is to present a system for monitoring the shaft motion of a turbocharger, which will be used in turbocharger destructive testing. To achieve this, a camera and a light source were installed in a turbocharger test bench with a controlled lubrication circuit. An image recording methodology and a process algorithm have been developed, in order to estimate the shaft motion. This processing consists on differentiating specific zones of the image, in order to obtain their coordinates. Two reference points have been configured on the compressor side, which help to calculate the relative position of the shaft, avoiding the errors due to structural vibrations. Maximum eccentricity of the turbocharger has been determined and it has been compared with shaft motion when it is spinning in different conditions. A luminosity study has been also done, in order to improve the process and to obtain locus of shaft position in a picture exposition time period. The technique has been applied to diagnosis of a lubrication failure test and the main results will be presented in this article: like shaft motion figures; thermodynamic variables and pictures of the shaft while it is spinning at abnormal lubrication conditions. The measuring components used in this technique have the ability to withstand the catastrophic failure of the turbocharger in this type of test.

  14. Investigations of lubricant rheology as applied to elastohydrodynamic lubrication

    NASA Technical Reports Server (NTRS)

    Bair, S.; Winer, W. O.

    1978-01-01

    Measurements of lubricant shear rheological behavior in the amorphous solid region and near the liquid-solid transition are reported. Elastic, plastic and viscous behavior was observed. A shear rheological model based on primary laboratory data is proposed for concentrated contact lubrication. The model is a Maxwell model modified with a limiting shear stress. Three material properties are required: low shear stress viscosity, limiting elastic shear modulus, and the limiting shear stress the material can withstand. All three are functions of temperature and pressure. In applying the model to EHD contacts the predicted response possesses the characteristics expected from several experiments reported in the literature.

  15. Lubricant composition of improved friction reducing properties

    SciTech Connect

    Malec, R.E.

    1980-05-06

    Lubricating oil is disclosed for use as a crankcase lubricant in internal combustion engines containing a friction-reducing amount of a sulfurized fatty acid amide, ester or ester-amide of an oxyalkylated amine.

  16. Metalworking corrosion inhibition/drawing lubricant

    SciTech Connect

    Lipinski, H.F.; Wantling, S.J.

    1980-05-06

    A metalworking lubricant composition is disclosed which is effective as both a corrosion inhibitor and drawing lubricant and comprises a mineral oil and an additive combination of barium lanolate soap and barium sulfonate.

  17. Linear mixed-effects modeling approach to FMRI group analysis

    PubMed Central

    Chen, Gang; Saad, Ziad S.; Britton, Jennifer C.; Pine, Daniel S.; Cox, Robert W.

    2013-01-01

    Conventional group analysis is usually performed with Student-type t-test, regression, or standard AN(C)OVA in which the variance–covariance matrix is presumed to have a simple structure. Some correction approaches are adopted when assumptions about the covariance structure is violated. However, as experiments are designed with different degrees of sophistication, these traditional methods can become cumbersome, or even be unable to handle the situation at hand. For example, most current FMRI software packages have difficulty analyzing the following scenarios at group level: (1) taking within-subject variability into account when there are effect estimates from multiple runs or sessions; (2) continuous explanatory variables (covariates) modeling in the presence of a within-subject (repeated measures) factor, multiple subject-grouping (between-subjects) factors, or the mixture of both; (3) subject-specific adjustments in covariate modeling; (4) group analysis with estimation of hemodynamic response (HDR) function by multiple basis functions; (5) various cases of missing data in longitudinal studies; and (6) group studies involving family members or twins. Here we present a linear mixed-effects modeling (LME) methodology that extends the conventional group analysis approach to analyze many complicated cases, including the six prototypes delineated above, whose analyses would be otherwise either difficult or unfeasible under traditional frameworks such as AN(C)OVA and general linear model (GLM). In addition, the strength of the LME framework lies in its flexibility to model and estimate the variance–covariance structures for both random effects and residuals. The intraclass correlation (ICC) values can be easily obtained with an LME model with crossed random effects, even at the presence of confounding fixed effects. The simulations of one prototypical scenario indicate that the LME modeling keeps a balance between the control for false positives and the

  18. CFD analysis of jet mixing in low NOx flametube combustors

    NASA Technical Reports Server (NTRS)

    Talpallikar, M. V.; Smith, C. E.; Lai, M. C.; Holdeman, J. D.

    1991-01-01

    The Rich-burn/Quick-mix/Lean-burn (RQL) combustor was identified as a potential gas turbine combustor concept to reduce NO(x) emissions in High Speed Civil Transport (HSCT) aircraft. To demonstrate reduced NO(x) levels, cylindrical flametube versions of RQL combustors are being tested at NASA Lewis Research Center. A critical technology needed for the RQL combustor is a method of quickly mixing by-pass combustion air with rich-burn gases. Jet mixing in a cylindrical quick-mix section was numerically analyzed. The quick-mix configuration was five inches in diameter and employed twelve radial-inflow slots. The numerical analyses were performed with an advanced, validated 3-D Computational Fluid Dynamics (CFD) code named REFLEQS. Parametric variation of jet-to-mainstream momentum flux ratio (J) and slot aspect ratio was investigated. Both non-reacting and reacting analyses were performed. Results showed mixing and NO(x) emissions to be highly sensitive to J and slot aspect ratio. Lowest NO(x) emissions occurred when the dilution jet penetrated to approximately mid-radius. The viability of using 3-D CFD analyses for optimizing jet mixing was demonstrated.

  19. Numerical analysis of mixing enhancement for micro-electroosmotic flow

    NASA Astrophysics Data System (ADS)

    Tang, G. H.; He, Y. L.; Tao, W. Q.

    2010-05-01

    Micro-electroosmotic flow is usually slow with negligible inertial effects and diffusion-based mixing can be problematic. To gain an improved understanding of electroosmotic mixing in microchannels, a numerical study has been carried out for channels patterned with wall blocks, and channels patterned with heterogeneous surfaces. The lattice Boltzmann method has been employed to obtain the external electric field, electric potential distribution in the electrolyte, the flow field, and the species concentration distribution within the same framework. The simulation results show that wall blocks and heterogeneous surfaces can significantly disturb the streamlines by fluid folding and stretching leading to apparently substantial improvements in mixing. However, the results show that the introduction of such features can substantially reduce the mass flow rate and thus effectively prolongs the available mixing time when the flow passes through the channel. This is a non-negligible factor on the effectiveness of the observed improvements in mixing efficiency. Compared with the heterogeneous surface distribution, the wall block cases can achieve more effective enhancement in the same mixing time. In addition, the field synergy theory is extended to analyze the mixing enhancement in electroosmotic flow. The distribution of the local synergy angle in the channel aids to evaluate the effectiveness of enhancement method.

  20. Analysis of lithology: Vegetation mixes in multispectral images

    NASA Technical Reports Server (NTRS)

    Adams, J. B.; Smith, M.; Adams, J. D.

    1982-01-01

    Discrimination and identification of lithologies from multispectral images is discussed. Rock/soil identification can be facilitated by removing the component of the signal in the images that is contributed by the vegetation. Mixing models were developed to predict the spectra of combinations of pure end members, and those models were refined using laboratory measurements of real mixtures. Models in use include a simple linear (checkerboard) mix, granular mixing, semi-transparent coatings, and combinations of the above. The use of interactive computer techniques that allow quick comparison of the spectrum of a pixel stack (in a multiband set) with laboratory spectra is discussed.

  1. Analysis of Compressible Mixing Layers Using Dilatational Covariances Model

    NASA Technical Reports Server (NTRS)

    Thangam, S.; Zhou, Y.; Ristorcelli, J. R.

    1996-01-01

    Compressible mixing layers are analyzed using a dilatational covariances model based on a pseudo-sound constitutive relation. The calculations are used to evaluate the different physical phenomena affecting compressible mixing layers. The rate of growth of the mixing layer is retarded by both the compressible dissipation and the pressure-dilatational covariances. The pressure-dilatational, essentially a nonequilibrium effect, reduces the amount of excess production over dissipation available for the turbulence energy growth. The pseudo-sound model also includes a history dependent portion: this is also investigated. All constants in the model and used in these computations are predicted by the theory.

  2. Tethered Lubricants for Small Systems

    SciTech Connect

    Lynden A. Archer

    2006-01-09

    The objective of this research project is two-fold. First, to fundamentally understand friction and relaxation dynamics of polymer chains near surfaces; and second, to develop novel self-lubricated substrates suitable for MEMS devices. During the three-year performance period of this study the PI and his students have shown using theory and experiments that systematic introduction of disorder into tethered lubricant coatings (e.g. by using self-assembled monolayer (SAM) mixtures or SAMs with nonlinear, branched architectures) can be used to significantly reduce the friction coefficient of a surface. They have also developed a simple procedure based on dielectric spectroscopy for quantifying the effect of surface disorder on molecular relaxation in lubricant coatings. Details of research accomplishments in each area of the project are described in the body of the report.

  3. Engineering Lubrication in Articular Cartilage

    PubMed Central

    McNary, Sean M.; Athanasiou, Kyriacos A.

    2012-01-01

    Despite continuous progress toward tissue engineering of functional articular cartilage, significant challenges still remain. Advances in morphogens, stem cells, and scaffolds have resulted in enhancement of the bulk mechanical properties of engineered constructs, but little attention has been paid to the surface mechanical properties. In the near future, engineered tissues will be able to withstand and support the physiological compressive and tensile forces in weight-bearing synovial joints such as the knee. However, there is an increasing realization that these tissue-engineered cartilage constructs will fail without the optimal frictional and wear properties present in native articular cartilage. These characteristics are critical to smooth, pain-free joint articulation and a long-lasting, durable cartilage surface. To achieve optimal tribological properties, engineered cartilage therapies will need to incorporate approaches and methods for functional lubrication. Steady progress in cartilage lubrication in native tissues has pushed the pendulum and warranted a shift in the articular cartilage tissue-engineering paradigm. Engineered tissues should be designed and developed to possess both tribological and mechanical properties mirroring natural cartilage. In this article, an overview of the biology and engineering of articular cartilage structure and cartilage lubrication will be presented. Salient progress in lubrication treatments such as tribosupplementation, pharmacological, and cell-based therapies will be covered. Finally, frictional assays such as the pin-on-disk tribometer will be addressed. Knowledge related to the elements of cartilage lubrication has progressed and, thus, an opportune moment is provided to leverage these advances at a critical step in the development of mechanically and tribologically robust, biomimetic tissue-engineered cartilage. This article is intended to serve as the first stepping stone toward future studies in functional

  4. Engineering lubrication in articular cartilage.

    PubMed

    McNary, Sean M; Athanasiou, Kyriacos A; Reddi, A Hari

    2012-04-01

    Despite continuous progress toward tissue engineering of functional articular cartilage, significant challenges still remain. Advances in morphogens, stem cells, and scaffolds have resulted in enhancement of the bulk mechanical properties of engineered constructs, but little attention has been paid to the surface mechanical properties. In the near future, engineered tissues will be able to withstand and support the physiological compressive and tensile forces in weight-bearing synovial joints such as the knee. However, there is an increasing realization that these tissue-engineered cartilage constructs will fail without the optimal frictional and wear properties present in native articular cartilage. These characteristics are critical to smooth, pain-free joint articulation and a long-lasting, durable cartilage surface. To achieve optimal tribological properties, engineered cartilage therapies will need to incorporate approaches and methods for functional lubrication. Steady progress in cartilage lubrication in native tissues has pushed the pendulum and warranted a shift in the articular cartilage tissue-engineering paradigm. Engineered tissues should be designed and developed to possess both tribological and mechanical properties mirroring natural cartilage. In this article, an overview of the biology and engineering of articular cartilage structure and cartilage lubrication will be presented. Salient progress in lubrication treatments such as tribosupplementation, pharmacological, and cell-based therapies will be covered. Finally, frictional assays such as the pin-on-disk tribometer will be addressed. Knowledge related to the elements of cartilage lubrication has progressed and, thus, an opportune moment is provided to leverage these advances at a critical step in the development of mechanically and tribologically robust, biomimetic tissue-engineered cartilage. This article is intended to serve as the first stepping stone toward future studies in functional

  5. Lubrication of rolling-element bearings

    NASA Technical Reports Server (NTRS)

    Parker, R. J.

    1980-01-01

    The lubrication of rolling element bearings is surveyed. Emphasis is on the critical design aspects related to speed, temperature, and ambient pressure environment. Types of lubrication including grease, jets, mist, wick, and through the race are discussed. The historical development, present state of technology, and the future problems of rolling element bearing lubrication are discussed.

  6. Research on Liquid Lubricants for Space Mechanisms

    NASA Technical Reports Server (NTRS)

    Jones, William R., Jr.; Shogrin, Bradley A.; Jansen, Mark J.

    1999-01-01

    Four research areas at the NASA Glenn Research Center involving the tribology of space mechanisms are highlighted. These areas include: soluble boundary lubrication additives for perfluoropolyether liquid lubricants, a Pennzane dewetting phenomenon, the effect of ODC-free bearing cleaning processes on bearing lifetimes and the development of a new class of liquid lubricants based on silahydrocarbons.

  7. Dual functional star polymers for lubricants

    DOE PAGES

    Cosimbescu, Lelia; Robinson, Joshua W.; Zhou, Yan; Qu, Jun

    2016-09-12

    Star-shaped poly(alkyl methacrylate)s (PAMAs) with a three arm architecturewere designed, prepared and their performance as a dual additive (viscosity index improver and friction modifier) for engine oils was evaluated. Furthermore, the structure property relationships between the macromolecular structure and lubricant performance were studied, such as molecular weight and polarity effects on the viscosity index. Several copolymers of dodecylmethacrylate with polar methacrylates in various amounts and various topologies, were synthesized as model compounds. Star polymers with a polar content of at least 10% in a block or tapered block topology effectively reduced the friction coefficient in both mixed and boundary lubricationmore » regimes. Furthermore, a polar content of 20% was efficient in reducing friction in both random and block topologies.« less

  8. Analysis of injury types for mixed martial arts athletes

    PubMed Central

    Ji, MinJoon

    2016-01-01

    [Purpose] The purpose of the present study was to examine the types of injuries associated with mixed martial arts and their location in order to provide substantial information to help reduce the risk of these injuries during mixed martial arts. [Subjects and Methods] Data were collected from 455 mixed martial arts athletes who practiced mixed martial arts or who participated in mixed martial arts competitions in the Seoul Metropolitan City and Gyeongnam Province of Korea between June 3, 2015, and November 6, 2015. Questionnaires were used to collect the data. The convenience sampling method was used, based on the non-probability sampling extraction method. [Results] The arm, neck, and head were the most frequent locations of the injuries; and lacerations, concussions, and contusions were the most frequently diagnosed types of injuries in the mixed martial arts athletes in this study. [Conclusion] Reducing the risk of injury by establishing an alert system and preventing critical injuries by incorporating safety measures are important. PMID:27313367

  9. Analysis of injury types for mixed martial arts athletes.

    PubMed

    Ji, MinJoon

    2016-05-01

    [Purpose] The purpose of the present study was to examine the types of injuries associated with mixed martial arts and their location in order to provide substantial information to help reduce the risk of these injuries during mixed martial arts. [Subjects and Methods] Data were collected from 455 mixed martial arts athletes who practiced mixed martial arts or who participated in mixed martial arts competitions in the Seoul Metropolitan City and Gyeongnam Province of Korea between June 3, 2015, and November 6, 2015. Questionnaires were used to collect the data. The convenience sampling method was used, based on the non-probability sampling extraction method. [Results] The arm, neck, and head were the most frequent locations of the injuries; and lacerations, concussions, and contusions were the most frequently diagnosed types of injuries in the mixed martial arts athletes in this study. [Conclusion] Reducing the risk of injury by establishing an alert system and preventing critical injuries by incorporating safety measures are important. PMID:27313367

  10. National Institutes of Health: Mixed waste stream analysis

    SciTech Connect

    Kirner, N.P.; Faison, G.P.; Johnson, D.R.

    1994-08-01

    The Low-Level Radioactive Waste Policy Amendments Act of 1985 requires that the US Department of Energy (DOE) provide technical assistance to host States, compact regions, and unaffiliated States to fulfill their responsibilities under the Act. The National Low-Level Waste Management Program (NLLWMP) operated for DOE by EG&G Idaho, Inc. provides technical assistance in the development of new commercial low-level radioactive waste disposal capacity. The NLLWMP has been requested by the Appalachian Compact to help the biomedical community become better acquainted with its mixed waste streams, to help minimize the mixed waste streams generated by the biomedical community, and to provide applicable treatment technologies to those particular mixed waste streams. Mixed waste is waste that satisfies the definition of low-level radioactive waste (LLW) in the Low-Level Radioactive Waste Policy Act of 1980 (LLRWPA) and contains hazardous waste that either (a) is listed as a hazardous waste in Subpart D of 40 CFR 261, or (b) causes the LLW to exhibit any of the hazardous waste characteristics identified in 40 CFR 261. The purpose of this report is to clearly define and characterize the mixed waste streams generated by the biomedical community so that an identification can be made of the waste streams that can and cannot be minimized and treated by current options. An understanding of the processes and complexities of generation of mixed waste in the biomedical community may encourage more treatment and storage options to become available.

  11. Synthesis of new high performance lubricants and solid lubricants

    SciTech Connect

    Lagow, Richard J.

    1993-04-08

    In our second year of funding we began the testing phase of a number of new classes of lubricants. Three different testing collaborations have already begun and a fourth one is In the works with Dr. Stephen Hsu of the National Institute of Standards and Technology. Dr. Hsu also plans to test some of the same materials for us that Shell Development is studying. With Dr. Bill Jones of NASA, we are studying the effects of branching an high temperature lubricant properties in perfluoropolyethers, Initially Bill Jones is comparing the lubrication and physical properties of perfluorotetraglyme and the following two spherical perfluoropolyethers, Note that one contains a fluorocarbon chain and the other one contains a fluorocarbon ether chain. The synthesis of these was reported in the last progress report. With Professor Patricia Thiel of Iowa State University, we are working on studies of perfluoromethylene oxide ethers and have prepared a series of four of these polyethers to study in collaboration with her research group. These perfluoromethylene oxide ethers have the best low temperature properties of any known lubricants. Thiel's group is studying their interactions with metals under extreme conditions. Thirdly, we have also begun an Interaction with W. August Birke of Shell Development Company in Houston for whom we have already prepared samples of the chlorine-substituted fluorocarbon polyether lubricants whose structures appear on page 54 of our research proposal. Each of these four structures is thought to have potential as lubricant additives to motor oils. We also have underway syntheses of other fluorine-containing branched ether lubricants. These new materials which are also promising as antifriction additives for motor oils appear ahead of the perfluoro additives as Appendix I to the progress report. Additionally for Birke and Shell Development we have at their request prepared the novel compound perfluoro salicylic acid. This synthesis was suggested by the

  12. Towards an optimised sputtered MoS2 lubricant film

    NASA Technical Reports Server (NTRS)

    Roberts, E. W.

    1986-01-01

    It is shown that the tribological quality of MoS2 lubricant films formed by magnetron sputtering is determined by the choice of sputtering conditions. By selecting the appropriate conditions, films of extremely high lubricity and endurance (in vacuum), which are well suited to many space applications, are obtained. Such MoS2 films, when applied to precision ball hearings, give rise to the lowest torques (for the given test conditions) yet seen in our laboratory. While a remarkably good performance is obtained in vacuum, tests in air show a marked deterioration in lubricating qualities. It is demonstrated that this is attributable to the adsorption of water vapor on MoS2 surfaces and that the degree of deterioration is related to the partial pressure of water vapor present. Analysis of results indicates that the factors relevant to obtaining optimum films are deposition rate and film composition.

  13. Transient Shear Flow of Model Lithium Lubricating Greases

    NASA Astrophysics Data System (ADS)

    Delgado, M. A.; Franco, J. M.; Valencia, C.; Kuhn, E.; Gallegos, C.

    2008-07-01

    This work deals with the analysis of the transient shear flow behaviour of lithium lubricating greases differing in soap concentration and base oil viscosity. The shear-induced evolution of lithium grease microstructure has been studied by means of stress-growth experiments. With this aim, different lubricating grease formulations were manufactured by modifying lithium 12-hydroxystearate concentration and base oil viscosity. Different rheological parameters, related to both the elastic response and the structural breakdown of greases, have been analysed. In this sense, it has been found that the elastic properties of lithium lubricating greases were highly influenced by soap concentration and oil viscosity. Moreover, an asymptotic tendency has been found for the stress overshoot by increasing shear rate. The asymptotic values of this parameter have been correlated to the friction coefficient obtained in a ball-disc tribometer.

  14. Full Life Wind Turbine Gearbox Lubricating Fluids

    SciTech Connect

    Lutz, Glenn A.; Jungk, Manfred; Bryant, Jonathan J.; Lauer, Rebecca S.; Chobot, Anthony; Mayer, Tyler; Palmer, Shane; Kauffman, Robert E.

    2012-02-28

    the lubricating fluids performance under the most extreme conditions. The PAO Reference oil also passed its testing without any noticeable deterioration of the gear surface. However the PAO Reference oil was replaced midway through the progressive loading, as the lubricant was burned in an attempt to raise the sump temperature to the same levels as for the PFPE. Both materials experienced a decrease of viscosity during their respective run times. The viscosity index decreased for the PAO there while there was a slight increase for the PFPE. FZG laboratory gear tests and measurements of the drive motor's current during the full scale gear box trial were made to characterize the relative efficiency between the PFPE fluid and the PAO Reference oil. In the FZG laboratory efficiency test, the PFPE fluids show much higher churning losses due to their higher viscosity and density. The analysis seems to show that the efficiency correlates better to dynamic viscosity than any other of the measured metrics such as film thickness. In load stages where the load, speed and temperature are similar, the PFPE fluid has a greater film thickness and theoretical gear protection, but requires a larger current for the drive motor than the PAO. However in load stages where the film thickness is the same, the PFPE fluid's reduced dynamic viscosity gives it a slight efficiency advantage relative to the PAO reference oil. Ultimately, many factors such as temperature, rotational speed, and fluid viscosity combine in a complex fashion to influence the results. However, the PFPE's much lower change of viscosity with respect to temperature, allows variations in designing an optimum viscosity to balance efficiency versus gear protection. Economic analysis was done using Cost of Energy calculations. The results vary from 5.3% for a 'Likely Case' to 16.8% for a 'Best Case' scenario as potential cost improvement by using PFPE as the gearbox lubricating fluid. It is important to note the largest

  15. Self lubrication of bitumen froth in pipelines

    SciTech Connect

    Joseph, D.D.

    1997-12-31

    In this paper I will review the main properties of water lubricated pipelines and explain some new features which have emerged from studies of self-lubrication of Syncrudes` bitumen froth. When heavy oils are lubricated with water, the water and oil are continuously injected into a pipeline and the water is stable when in a lubricating sheath around the oil core. In the case of bitumen froth obtained from the Alberta tar sands, the water is dispersed in the bitumen and it is liberated at the wall under shear; water injection is not necessary because the froth is self-lubricating.

  16. Treatment technology analysis for mixed waste containers and debris

    SciTech Connect

    Gehrke, R.J.; Brown, C.H.; Langton, C.A.; Askew, N.M.; Kan, T.; Schwinkendorf, W.E.

    1994-03-01

    A team was assembled to develop technology needs and strategies for treatment of mixed waste debris and empty containers in the Department of Energy (DOE) complex, and to determine the advantages and disadvantages of applying the Debris and Empty Container Rules to these wastes. These rules issued by the Environmental Protection Agency (EPA) apply only to the hazardous component of mixed debris. Hazardous debris that is subjected to regulations under the Atomic Energy Act because of its radioactivity (i.e., mixed debris) is also subject to the debris treatment standards. The issue of treating debris per the Resource Conservation and Recovery Act (RCRA) at the same time or in conjunction with decontamination of the radioactive contamination was also addressed. Resolution of this issue requires policy development by DOE Headquarters of de minimis concentrations for radioactivity and release of material to Subtitle D landfills or into the commercial sector. The task team recommends that, since alternate treatment technologies (for the hazardous component) are Best Demonstrated Available Technology (BDAT): (1) funding should focus on demonstration, testing, and evaluation of BDAT on mixed debris, (2) funding should also consider verification of alternative treatments for the decontamination of radioactive debris, and (3) DOE should establish criteria for the recycle/reuse or disposal of treated and decontaminated mixed debris as municipal waste.

  17. The influence of external dynamic loads on the lifetime of rolling element bearings: Experimental analysis of the lubricant film and surface wear

    NASA Astrophysics Data System (ADS)

    Jacobs, William; Van Hooreweder, Brecht; Boonen, Rene; Sas, Paul; Moens, David

    2016-06-01

    Precise prediction of the lifetime of rolling element bearings is a crucial step towards a reliable design of many rotating machines. For bearings subjected to highly varying loads, recent research emphasises a strong reduction of the actual bearing lifetime w.r.t. the classically calculated bearing lifetime. This paper experimentally analyses the influence of external dynamic loads on the lifetime of rolling element bearings. A novel bearing test rig is introduced. The test rig is able to apply a fully controlled multi-axial static and dynamic load on a single test bearing. Also, different types and sizes of bearings can be tested. Two separate investigations are conducted. First, the behaviour of the lubricant film between the rolling elements and raceways is analysed. Increased metallic contact or breakdown of the film during dynamic excitation is investigated based on the measured electrical resistance through the bearing. The study shows that the lubricant film thickness follows the imposed variations of the load. Variations of the lubricant film thickness are similar to the variations when the magnitude of the static bearing load is changed. Second, wear of the raceway surfaces is analysed. Surface wear is investigated after a series of accelerated lifetime tests under high dynamic load. Due to sliding motion between asperities of the contacting surfaces in the bearing, polishing of the raceway honing structure occurs. This polishing is clearly observed on SEM images of the inner raceway after a test duration of only 0.5% of the calculated L10 life. Polishing wear of the surfaces, such as surface induced cracks and material delamination, is expected when the bearing is further exposed to the high dynamic load.

  18. Tetrasulfide extreme pressure lubricant additives

    SciTech Connect

    Gast, L.E.; Kenney, H.E.; Schwab, A.W.

    1980-08-19

    A novel class of compounds has been prepared comprising the tetrasulfides of /sup 18/C hydrocarbons, /sup 18/C fatty acids, and /sup 18/C fatty and alkyl and triglyceride esters. These tetrasulfides are useful as extreme pressure lubricant additives and show potential as replacements for sulfurized sperm whale oil.

  19. Lubricant Selection Manual, Phase 3

    NASA Technical Reports Server (NTRS)

    Kannel, J. W.; Lowry, J. A.; Dufrane, K. F.

    1991-01-01

    Future spacecraft must be designated to operate for very long time periods in space. For example, a target goal for the Space Station is 30 years of operation. Although the actual life may be significantly less than this optimistic goal, the life will certainly be a critical issue in design. The bearings on primary components such as the alpha and beta joints must obviously be designed and lubricated with the objective of optimum performance life. In addition to these joints, there will be numerous other tribological (rubbing or rolling) interfaced that will be required to function for the life of the spacecraft. A major key to adequate performance of tribological interface is proper lubrication. Lubricants can be divided into two basic classes: solid films and liquids. Both types have been used extensively in space applications. Both have advantages and disadvantages that must be carefully considered in their selection. The purpose here is to summarize selection criteria for liquid and solid lubricants applied to long-life spacecraft.

  20. Longevity Of Dry Film Lubricants

    NASA Technical Reports Server (NTRS)

    Kannel, J. W.; Stockwell, R. D.

    1993-01-01

    Report describes evaluation of dry film lubricants candidate for use in rotary joints of proposed Space Station. Study included experiments and theoretical analyses focused on longevity of sputtered molybdenum disulfide films and ion-plated lead films under conditions partially simulating rolling contact.

  1. Thin Film Solid Lubricant Development

    NASA Technical Reports Server (NTRS)

    Benoy, Patricia A.

    1997-01-01

    Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

  2. Solubility, viscosity and density of refrigerant/lubricant mixtures

    SciTech Connect

    Henderson, D.R.

    1993-04-01

    This report presents results for low refrigerant concentration (70, 80, 90 and 100 weight percent lubricant) mixtures of the following fluids: CFC-12/ISO 32 naphthenic mineral oil, HCFC-22/ISO 32 naphthenic mineral oil, CFC-12/ISO 100 naphthenic mineral oil, HFC-134a/ISO 22 pentaerythritol ester mixed acid, HFC-134a/ISO 32 pentaerythritol ester mixed acid [number sign]1, HFC-134a/ISO 68 pentaerythritol ester mixed acid, HFC-134a/ISO 100 pentaerythritol ester mixed acid, HFC-134a/ISO 32 pentaerythritol ester mixed acid [number sign]2, HCFC-123/ISO 32 naphthenic mineral oil, HCFC-123/ISO 100 naphthenic mineral oil, HCFC-123/150 SUS alkylbenzene, HCFC-123/300 SUS alkylbenzene. These data have been reduced to engineering form and are presented in the form of a Daniel Chart. Equations are given along with statistical measures of goodness of fit.

  3. Solid Lubricants for Oil-Free Turbomachinery

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher

    2005-01-01

    Recent breakthroughs in gas foil bearing solid lubricants and computer based modeling has enabled the development of revolulionary Oil-Free turbomachinery systems. These innovative new and solid lubricants at low speeds (start-up and shut down). Foil bearings are hydrodynamic, self acting fluid film bearings made from thin, flexible sheet metal foils. These thin foils trap a hydrodynamic lubricating air film between their surfaces and moving shaft surface. For low temperature applications, like ainrafl air cycle machines (ACM's), polymer coatings provide important solid lubrication during start-up and shut down prior to the development of the lubricating fluid film. The successful development of Oil-Free gas turbine engines requires bearings which can operate at much higher temperatures (greater than 300 C). To address this extreme solid lubrication need, NASA has invented a new family of compostie solid lubricant coatings, NASA PS300.

  4. Engine wear and lubricating oil contamination from plant oil fuels

    SciTech Connect

    Darcey, C.L.; LePori, W.A.; Yarbrough, C.M.

    1982-12-01

    Engine disassembly with wear measurements, and lubricating oil analysis were used to determine wear rates on a one cylinder diesel engine. Results are reported from short duration tests on the wear rates of various levels of processed sunflower oil, a 25% blend with diesel fuel, and processed cottonseed oil.

  5. Consent, Informal Organization and Job Rewards: A Mixed Methods Analysis

    ERIC Educational Resources Information Center

    Laubach, Marty

    2005-01-01

    This study uses a mixed methods approach to workplace dynamics. Ethnographic observations show that the consent deal underlies an informal stratification that divides the workplace into an "informal periphery," a "conventional core" and an "administrative clan." The "consent deal" is defined as an exchange of autonomy, voice and schedule…

  6. Linking Research Questions to Mixed Methods Data Analysis Procedures

    ERIC Educational Resources Information Center

    Onwuegbuzie, Anthony J.; Leech, Nancy L.

    2006-01-01

    The purpose of this paper is to discuss the development of research questions in mixed methods studies. First, we discuss the ways that the goal of the study, the research objective(s), and the research purpose shape the formation of research questions. Second, we compare and contrast quantitative research questions and qualitative research…

  7. First Generation College Student Leadership Potential: A Mixed Methods Analysis

    ERIC Educational Resources Information Center

    Hojan-Clark, Jane M.

    2010-01-01

    This mixed methods research compared the leadership potential of traditionally aged first generation college students to that of college students whose parents are college educated. A college education provides advantages to those who can obtain it (Baum & Payea, 2004; Black Issues in Higher Education, 2005; Education and the Value of Knowledge,…

  8. Lubricant Use Among Men Who Have Sex With Men Reporting Anal Intercourse in Bangkok, Thailand: Impact of HIV Status and Implications for Prevention.

    PubMed

    Thienkrua, Warunee; Todd, Catherine S; Chaikummao, Supaporn; Sukwicha, Wichuda; Yafant, Somsak; Tippanont, Narongritt; Varangrat, Anchalee; Khlaimanee, Pechpailin; Sirivongrangson, Pachara; Holtz, Timothy H

    2016-01-01

    This analysis measures prevalence and correlates of consistent lubricant use among a cohort of Thai men who have sex with men (MSM). Lubricant use was queried at the 12-month follow-up visit. Consistent lubricant use was evaluated with logistic regression. Consistent lubricant use was reported by 77.0% of men and was associated with consistent condom use with casual partners, while binge drinking, payment for sex, and inconsistent condom use with casual, and steady, partners were negatively associated. Though consistent lubricant use is common among this Thai MSM cohort, further promotion is needed with MSM engaging in risky sexual practices.

  9. Elastic-plastic mixed-iterative finite element analysis: Implementation and performance assessment

    NASA Technical Reports Server (NTRS)

    Sutjahjo, Edhi; Chamis, Christos C.

    1993-01-01

    An elastic-plastic algorithm based on Von Mises and associative flow criteria is implemented in MHOST-a mixed iterative finite element analysis computer program developed by NASA Lewis Research Center. The performance of the resulting elastic-plastic mixed-iterative analysis is examined through a set of convergence studies. Membrane and bending behaviors of 4-node quadrilateral shell finite elements are tested for elastic-plastic performance. Generally, the membrane results are excellent, indicating the implementation of elastic-plastic mixed-iterative analysis is appropriate.

  10. Mixed time integration methods for transient thermal analysis of structures, appendix 5

    NASA Technical Reports Server (NTRS)

    Liu, W. K.

    1982-01-01

    Mixed time integration methods for transient thermal analysis of structures are studied. An efficient solution procedure for predicting the thermal behavior of aerospace vehicle structures was developed. A 2D finite element computer program incorporating these methodologies is being implemented. The performance of these mixed time finite element algorithms can then be evaluated employing the proposed example problem.

  11. The Analysis of Repeated Measurements with Mixed-Model Adjusted "F" Tests

    ERIC Educational Resources Information Center

    Kowalchuk, Rhonda K.; Keselman, H. J.; Algina, James; Wolfinger, Russell D.

    2004-01-01

    One approach to the analysis of repeated measures data allows researchers to model the covariance structure of their data rather than presume a certain structure, as is the case with conventional univariate and multivariate test statistics. This mixed-model approach, available through SAS PROC MIXED, was compared to a Welch-James type statistic.…

  12. Mixing Qualitative and Quantitative Methods: Insights into Design and Analysis Issues

    ERIC Educational Resources Information Center

    Lieber, Eli

    2009-01-01

    This article describes and discusses issues related to research design and data analysis in the mixing of qualitative and quantitative methods. It is increasingly desirable to use multiple methods in research, but questions arise as to how best to design and analyze the data generated by mixed methods projects. I offer a conceptualization for such…

  13. Investigations of lubricant rheology as applied to elastohydrodynamic lubrication

    NASA Technical Reports Server (NTRS)

    Kunz, R. K.; Nagaraj, H. S.; Sanborn, D. M.; Winer, W. O.

    1975-01-01

    Traction prediction in sliding elastohydrodynamic (EHD) contacts was examined along with an elastohydrodynamic lubrication simulation of the effects of load and speed on temperatures in the EHD contact. An existing shear stress theory and lubricant rheological model were studied and evaluated by applying them to traction prediction. Results obtained using measured film thickness and surface temperature data, were compared with measured traction values. The infrared technique for measuring temperatures in an EHD contact was further developed and ball surface and fluid temperatures are reported for sliding speeds of 0.35 to 5.08 m/s at 0.52 to 2.03 GN/sq m maximum pressure and surface roughnesses of .011 to .381 micrometers c.1.a. The relationship between asperity interaction, as measured by relocation surface profilimetry and high frequency temperature measurements, and the ratio of film thickness to surface roughness was also studied.

  14. Self-adaptive surface texture design for friction reduction across the lubrication regimes

    NASA Astrophysics Data System (ADS)

    Hsu, Stephen M.; Jing, Yang; Zhao, Fei

    2016-03-01

    Surface texturing has been shown to reduce friction and improve durability in mechanical face seals and metal forming operations, and lightly loaded thrust bearings. However, the success has been limited to conformal contacts and low load high speed operating conditions, i.e. hydrodynamic lubrication dominated regime. Both experiments and numerical simulations have shown that textural patterns, under higher loading and/or slower speeds may increase friction and even cause the lubrication film collapse. Specific designs of surface texture pattern, as its shape, depth and density, are required for different lubrication regimes. Our own study has shown (Hsu et al 2014 J. Phys. D: Appl. Phys. 47 335307) that large/shallow dimple reduces friction in hydrodynamic lubrication regime, whereas small/deep dimple shows benefit in mixed/boundary lubrication regimes (if the textural designs can provides hydrodynamic/hydrostatic lift forces to reduce the machine loading). In considering an engine component typically experiences duty cycles that may cross various lubrication regimes, a multiscale surface texture design appears attractive. This type of mixed shape texturing combines textures designed for low load, high speed operating conditions and the textures that are designed for high load, low speed operations. In this paper, two types of multiscale surface texture designs are presented. Ball-on-three-flats (BOTF) wear tester (under high loading conditions) is used to evaluate the performance of these multiscale texture designs along with the baselines of un-textured surfaces under the same surface preparation procedures. Two texture designs with only a single shape dimples are included in the study. Results suggest that multiscale surface texture design not only further reduces friction in comparison to the textures with single shape dimples, but also shows the effectiveness across hydrodynamic regimes to the mixed lubrication regimes.

  15. A Mixed Methods Content Analysis of the Research Literature in Science Education

    NASA Astrophysics Data System (ADS)

    Schram, Asta B.

    2014-10-01

    In recent years, more and more researchers in science education have been turning to the practice of combining qualitative and quantitative methods in the same study. This approach of using mixed methods creates possibilities to study the various issues that science educators encounter in more depth. In this content analysis, I evaluated 18 studies from science education journals as they relate to the definition, design, and overall practice of using mixed methods. I scrutinized a purposeful sample, derived from 3 journals (the International Journal of Science Education, the Journal of Research in Science Teaching, and the Research in Science Education) in terms of the type of data collected, timing, priority, design, the mixing of the 2 data strands in the studies, and the justifications authors provide for using mixed methods. Furthermore, the articles were evaluated in terms of how well they met contemporary definitions for mixed methods research. The studies varied considerably in the use and understanding of mixed methods. A systematic evaluation of the employment of mixed methods methodology was used to identify the studies that best reflected contemporary definitions. A comparison to earlier content analyses of mixed methods research indicates that researchers' knowledge of mixed methods methodology may be increasing. The use of this strategy in science education research calls, however, for an improved methodology, especially concerning the practice of mixing. Suggestions are given on how to best use this approach.

  16. Comparison of conventional and microasperity elastohydrodynamic lubrication of a ballspinning in a nonconforming groove

    NASA Technical Reports Server (NTRS)

    Allen, C. W.; Townsend, D. P.; Zaretsky, E. V.

    1972-01-01

    An analysis was developed for the microasperity elastohydrodynamic lubrication of a ball spinning in a nonconforming groove. This analysis was compared to the conventional elastohydrodynamic analysis of a ball spinning in a nonconforming groove. Rheological models for a di-2-ethylhexyl sebacate, a super-refined naphthenic mineral oil, and a polyphenyl ether (5P4E) were constructed from spinning torque data by using both analyses. The value of the lubricant pressure-viscosity coefficient that makes the data fit the analyses of the fluids differs somewhat from published data. For all three lubricants, an exponential composite model best described the lubricant rheology. Good agreement existed with the experimental and analytical values of torque for both the conventional and microasperity elastohydrodynamic analysis for a spinning ball in a nonconforming groove.

  17. Model analysis of influences of aerosol mixing state upon its optical properties in East Asia

    NASA Astrophysics Data System (ADS)

    Han, Xiao; Zhang, Meigen; Zhu, Lingyun; Xu, Liren

    2013-07-01

    The air quality model system RAMS (Regional Atmospheric Modeling System)-CMAQ (Models-3 Community Multi-scale Air Quality) coupled with an aerosol optical/radiative module was applied to investigate the impact of different aerosol mixing states (i.e., externally mixed, half externally and half internally mixed, and internally mixed) on radiative forcing in East Asia. The simulation results show that the aerosol optical depth (AOD) generally increased when the aerosol mixing state changed from externally mixed to internally mixed, while the single scattering albedo (SSA) decreased. Therefore, the scattering and absorption properties of aerosols can be significantly affected by the change of aerosol mixing states. Comparison of simulated and observed SSAs at five AERONET (Aerosol Robotic Network) sites suggests that SSA could be better estimated by considering aerosol particles to be internally mixed. Model analysis indicates that the impact of aerosol mixing state upon aerosol direct radiative forcing (DRF) is complex. Generally, the cooling effect of aerosols over East Asia are enhanced in the northern part of East Asia (Northern China, Korean peninsula, and the surrounding area of Japan) and are reduced in the southern part of East Asia (Sichuan Basin and Southeast China) by internal mixing process, and the variation range can reach ±5 W m-2. The analysis shows that the internal mixing between inorganic salt and dust is likely the main reason that the cooling effect strengthens. Conversely, the internal mixture of anthropogenic aerosols, including sulfate, nitrate, ammonium, black carbon, and organic carbon, could obviously weaken the cooling effect.

  18. Performance of two MOV lubricants

    SciTech Connect

    Gleeson, J.B.; Cline, T.

    1996-12-01

    Recent testing at Battelle has shown that a synthetic grease (Mobil 28) provides both improved friction coefficient and lower rate-of-loading (ROL) characteristics. Duke Power nuclear plants currently use an antiseize (N5000) as a motor operated valve (MOV) stem lubricant but they are considering changing to Mobil 28. However, it is not practical to completely remove all the residual antiseize from the steam threads when changing to a new lubricant. The testing performed during this study was to determine the friction coefficient and ROL effects for Mobil 28 when applied to a valve stem with residual N5000. This testing demonstrated how mixtures of Mobil 28 and N5000 perform under varying MOV conditions.

  19. Mixed Waste Management Facility Preliminary Safety Analysis Report. Chapters 1 to 20

    SciTech Connect

    Not Available

    1994-09-01

    This document provides information on waste management practices, occupational safety, and a site characterization of the Lawrence Livermore National Laboratory. A facility description, safety engineering analysis, mixed waste processing techniques, and auxiliary support systems are included.

  20. Image analysis for Validation of Simulations of Fluid Mix Problem

    SciTech Connect

    Kamath, C; Miller, P

    2007-01-10

    As computer simulations gain acceptance for the modeling of complex physical phenomena, there is an increasing need to validate these simulation codes by comparing them to experiments. Currently, this is done qualitatively, using a visual approach. This is obviously very subjective and more quantitative metrics are needed, especially to identify simulations which are closer to experiments than other simulations. In this paper, we show how image processing techniques can be effectively used in such comparisons. Using an example from the problem of mixing of two fluids, we show that we can quantitatively compare experimental and simulation images by extracting higher level features to characterize the objects in the images.

  1. Homegrown lubricants and plastics. [Brassica

    SciTech Connect

    Senft, D.

    1988-10-01

    A small bushy lesquerella plant of the mustard family growing wild in Arizona, New Mexico, Oklahoma and Texas produces seeds that may be used to make lubricants, plastics, protective coatings, surfactants, and pharmaceuticals. The plant thrives on poor soils that receive as little as 10 inches of rain a year. Studies to date indicate that target yields can be reached with a reasonable breeding effort coupled with agronomic research.

  2. Powder-lubricated piston ring development

    NASA Astrophysics Data System (ADS)

    Heshmat, H.

    1991-06-01

    The overall objective of this program was to demonstrate the feasibility of a new particulate lubrication concept for reducing piston ring/cylinder liner wear in coal-water slurry-fueled diesels by replacing the present oil-lubricated system with powder lubrication that would utilize coal ash, either alone or in combination with another powder. The feasibility of this particular lubrication concept for reducing ring/liner wear was demonstrated in a series of experiments utilizing redesigned and properly selected components. Wear performance for suitable ring/liner materials lubricated with a powder that incorporates the abrasive ash particles was evaluated in terms of load capacity, friction, and rate of wear for the best combination of ring design, ring and liner materials, and powder constituents. In addition, the use of a powder-lubricated system in the upper portion of the cylinder isolated the particulates from the lower portions of the engine, thus further reducing engine wear.

  3. Powder-lubricated piston ring development

    SciTech Connect

    Heshmat, H.

    1991-06-01

    The overall objective of this program was to demonstrate the feasibility of a new particulate lubrication concept for reducing piston ring/cylinder liner wear in coal-water slurry-fueled diesels by replacing the present oil-lubricated system with powder lubrication that would utilize coal ash, either alone or in combination with another powder. The feasibility of this particular lubrication concept for reducing ring/liner wear was demonstrated in a series of experiments utilizing redesigned and properly selected components. Wear performance for suitable ring/liner materials lubricated with a powder that incorporates the abrasive ash particles was evaluated in terms of load capacity, friction, and rate of wear for the best combination of ring design, ring and liner materials, and powder constituents. In addition, the use of a powder-lubricated system in the upper portion of the cylinder isolated the particulates from the lower portions of the engine, thus further reducing engine wear. (VC)

  4. Elastohydrodynamic lubrication of elliptical contacts

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.

    1982-01-01

    Fully flooded, elastohydrodynamically lubricated, elliptical contacts are discussed. The relevant equations used in the elastohydrodynamic lubrication (EHL) of elliptical contacts are briefly described. Film thickness equations are developed for materials of high elastic modulus, such as metal, and for materials of low elastic modulus, such as rubber. In addition to the film thickness equations that are developed, plots of pressure and film thickness are presented. A theoretical study of the influence of lubricant starvation on film thickness and pressure in hard and soft elliptical elastohydrodynamic contacts is presented. From the results for both hard and soft EHL contacts a simple and important dimensionless inlet boundary distance is specified. It is also found that the film thickness for a starved condition can be written in dimensionless terms as a function of the inlet distance parameter and the film thickness for a fully flooded condition. contour plots of pressure and film thickness in and around the contact are shown for fully flooded and starved conditions. The theoretical findings are compared directly with results obtained experimentally.

  5. Elastohydrodynamic lubrication of elliptical contacts

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.

    1981-01-01

    The determination of the minimum film thickness within contact is considered for both fully flooded and starved conditions. A fully flooded conjunction is one in which the film thickness is not significantly changed when the amount of lubricant is increased. The fully flooded results presented show the influence of contact geometry on minimum film thickness as expressed by the ellipticity parameter and the dimensionless speed, load, and materials parameters. These results are applied to materials of high elastic modulus (hard EHL), such as metal, and to materials of low elastic modulus(soft EHL), such as rubber. In addition to the film thickness equations that are developed, contour plots of pressure and film thickness are given which show the essential features of elastohydrodynamically lubricated conjunctions. The crescent shaped region of minimum film thickness, with its side lobes in which the separation between the solids is a minimum, clearly emerges in the numerical solutions. In addition to the 3 presented for the fully flooded results, 15 more cases are used for hard EHL contacts and 18 cases are used for soft EHL contacts in a theoretical study of the influence of lubricant starvation on film thickness and pressure. From the starved results for both hard and soft EHL contacts, a simple and important dimensionless inlet boundary distance is specified. This inlet boundary distance defines whether a fully flooded or a starved condition exists in the contact. Contour plots of pressure and film thickness in and around the contact are shown for conditions.

  6. The PM-200 lubrication system

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1991-01-01

    Plasma sprayed composite coating of metal-bonded chromium carbide with additions of silver and thermochemically stable fluorides were previously reported to be lubricative in pin on desk bench tests from room temperature to 900 C. An early coating formulation of this type, designated as PS-200, was successfully tested as a cylinder coating in a Stirling engine at a TRRT of 760 C in a hydrogen atmosphere, and as a backup lubricant for gas bearings to 650 C. A subsequent optimization program has shown that tribological properties are further improved by increasing the solid lubricant content. The improved coating is designated as PS-212. The same powder formulation was used to make free-standing powder metallurgy (PM-212) parts by sintering or hot isostatic pressing. The process is very attractive for making parts that cannot be readily plasma sprayed such as bushings and cylinders that have small bore diameters and/or high length to diameter ratios. The properties of coatings and free-standing parts fabricated from these powders are reviewed.

  7. Silica Lubrication in Faults (Invited)

    NASA Astrophysics Data System (ADS)

    Rowe, C. D.; Rempe, M.; Lamothe, K.; Kirkpatrick, J. D.; White, J. C.; Mitchell, T. M.; Andrews, M.; Di Toro, G.

    2013-12-01

    Silica-rich rocks are common in the crust, so silica lubrication may be important for causing fault weakening during earthquakes if the phenomenon occurs in nature. In laboratory friction experiments on chert, dramatic shear weakening has been attributed to amorphization and attraction of water from atmospheric humidity to form a 'silica gel'. Few observations of the slip surfaces have been reported, and the details of weakening mechanism(s) remain enigmatic. Therefore, no criteria exist on which to make comparisons of experimental materials to natural faults. We performed a series of friction experiments, characterized the materials formed on the sliding surface, and compared these to a geological fault in the same rock type. Experiments were performed in the presence of room humidity at 2.5 MPa normal stress with 3 and 30 m total displacement for a variety of slip rates (10-4 - 10-1 m/s). The friction coefficient (μ) reduced from >0.6 to ~0.2 at 10-1 m/s, but only fell to ~0.4 at 10-2 - 10-4 m/s. The slip surfaces and wear material were observed using laser confocal Raman microscopy, electron microprobe, X-ray diffraction, and transmission electron microscopy. Experiments at 10-1 m/s formed wear material consisting of ≤1 μm powder that is aggregated into irregular 5-20 μm clumps. Some material disaggregated during analysis with electron beams and lasers, suggesting hydrous and unstable components. Compressed powder forms smooth pavements on the surface in which grains are not visible (if present, they are <100 nm). Powder contains amorphous material and as yet unidentified crystalline and non-crystalline forms of silica (not quartz), while the worn chert surface underneath shows Raman spectra consistent with a mixture of quartz and amorphous material. If silica amorphization facilitates shear weakening in natural faults, similar wear materials should be formed, and we may be able to identify them through microstructural studies. However, the sub

  8. Lubricating oil compositions containing organometallic additives

    SciTech Connect

    Landry, J.F.; Croudance, M.C.; On, H.P.; Shen, S.Y.

    1987-04-07

    This invention provides novel lubricating oil compositions comprising an organometallic additive, including a metal selected from Groups I, Ib, and VIII of the Periodic System of Elements, e.g. Na, K, Cu, Co, Ni or Fe, chelated with the reaction product of formaldehyde, an amino acid and a phenol, dissolved in a lubricating oil. Depending on the choice of the metal, the above organometallic additive imparts rust inhibition, sludge dispersant, wear reduction and anti-oxidant properties to the lubricating oil compositions.

  9. Effects of lubrication on the performance of high speed spur gears

    NASA Technical Reports Server (NTRS)

    Mizutani, Hachiro; Isikawa, Yuuichi; Townsend, Dennis P.

    1989-01-01

    An experimental analysis was conducted to determine power loss and gear noise of high speed spur gears with long addendum under various conditions of load, speed, and oil jet pressure for into mesh lubrication. Power losses were calculated from temperature measurements of lubricating oil, gears, gear box, and oil flow rate. Furthermore, power loss was divided into windage loss, friction loss and churning loss. The results show that windage loss and churning loss were the main components of gear power loss of high gear speed. In addition, lubricating conditions had some influences on gear noise especially under low oil temperature or high viscosity.

  10. Lubrication from mixture of boric acid with oils and greases

    SciTech Connect

    Erdemir, A.

    1995-07-11

    Lubricating compositions are disclosed including crystalline boric acid and a base lubricant selected from oils, greases and the like. The lubricity of conventional oils and greases can also be improved by adding concentrates of boric acid.

  11. Lubrication from mixture of boric acid with oils and greases

    SciTech Connect

    Erdemir, Ali

    1995-01-01

    Lubricating compositions including crystalline boric acid and a base lubricant selected from oils, greases and the like. The lubricity of conventional oils and greases can also be improved by adding concentrates of boric acid.

  12. Eliciting mixed emotions: a meta-analysis comparing models, types, and measures.

    PubMed

    Berrios, Raul; Totterdell, Peter; Kellett, Stephen

    2015-01-01

    The idea that people can experience two oppositely valenced emotions has been controversial ever since early attempts to investigate the construct of mixed emotions. This meta-analysis examined the robustness with which mixed emotions have been elicited experimentally. A systematic literature search identified 63 experimental studies that instigated the experience of mixed emotions. Studies were distinguished according to the structure of the underlying affect model-dimensional or discrete-as well as according to the type of mixed emotions studied (e.g., happy-sad, fearful-happy, positive-negative). The meta-analysis using a random-effects model revealed a moderate to high effect size for the elicitation of mixed emotions (d IG+ = 0.77), which remained consistent regardless of the structure of the affect model, and across different types of mixed emotions. Several methodological and design moderators were tested. Studies using the minimum index (i.e., the minimum value between a pair of opposite valenced affects) resulted in smaller effect sizes, whereas subjective measures of mixed emotions increased the effect sizes. The presence of more women in the samples was also associated with larger effect sizes. The current study indicates that mixed emotions are a robust, measurable and non-artifactual experience. The results are discussed in terms of the implications for an affect system that has greater versatility and flexibility than previously thought. PMID:25926805

  13. Eliciting mixed emotions: a meta-analysis comparing models, types, and measures

    PubMed Central

    Berrios, Raul; Totterdell, Peter; Kellett, Stephen

    2015-01-01

    The idea that people can experience two oppositely valenced emotions has been controversial ever since early attempts to investigate the construct of mixed emotions. This meta-analysis examined the robustness with which mixed emotions have been elicited experimentally. A systematic literature search identified 63 experimental studies that instigated the experience of mixed emotions. Studies were distinguished according to the structure of the underlying affect model—dimensional or discrete—as well as according to the type of mixed emotions studied (e.g., happy-sad, fearful-happy, positive-negative). The meta-analysis using a random-effects model revealed a moderate to high effect size for the elicitation of mixed emotions (dIG+ = 0.77), which remained consistent regardless of the structure of the affect model, and across different types of mixed emotions. Several methodological and design moderators were tested. Studies using the minimum index (i.e., the minimum value between a pair of opposite valenced affects) resulted in smaller effect sizes, whereas subjective measures of mixed emotions increased the effect sizes. The presence of more women in the samples was also associated with larger effect sizes. The current study indicates that mixed emotions are a robust, measurable and non-artifactual experience. The results are discussed in terms of the implications for an affect system that has greater versatility and flexibility than previously thought. PMID:25926805

  14. Lubrication System with Tolerance for Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Portlock, Lawrence E. (Inventor); McCune, Michael E. (Inventor); Dobek, Louis J. (Inventor)

    2013-01-01

    A lubrication system includes an auxiliary lubricant tank 48, a supply conduit 58 extending from a source of lubricant 26 to the auxiliary lubricant tank. A reduced-G bypass line 108 branches from the conduit and enters the auxiliary tank at a first elevation E.sub.1. The system also includes an auxiliary tank discharge conduit 116, a portion of which resides within the tank. The resident portion has an opening 122 at least partially at a second elevation E.sub.2 higher than the first elevation.

  15. Solid Lubrication Fundamentals and Applications. Chapter 2

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1998-01-01

    This chapter describes powerful analytical techniques capable of sampling tribological surfaces and solid-film lubricants. Some of these techniques may also be used to determine the locus of failure in a bonded structure or coated substrate; such information is important when seeking improved adhesion between a solid-film lubricant and a substrate and when seeking improved performance and long life expectancy of solid lubricants. Many examples are given here and through-out the book on the nature and character of solid surfaces and their significance in lubrication, friction, and wear. The analytical techniques used include the late spectroscopic methods.

  16. 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.

  17. Lubrication of nonconformal contacts. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Jeng, Y. R.

    1985-01-01

    Minimum film thickness results for piezoviscous-rigid regime of lubrication are developed for a compressible Newtonian fluid with Roelands viscosity. The results provide a basis for the analysis and design of a wide range of machine elements operating in the piezoviscous-rigid regime of lubrication. A new numerical method of calculating elastic deformation in contact stresses is developed using a biquadratic polynomial to approximate the pressure distribution on the whole domain analyzed. The deformation of every node is expressed as a linear combination of the nodal pressures whose coefficients can be combined into an influence coefficient matrix. This approach has the advantages of improved numerical accuracy, less computing time and smaller storage size required for influence matrix. The ideal elastohydrodynamic lubrication is extended to real bearing systems in order to gain an understanding of failure mechanisms in machine elements. The improved elastic deformation calculation is successfully incorporated into the EHL numerical scheme. Using this revised numerical technique and the flow factor model developed by Patir and Cheng (1978) the surface roughness effects on the elastohydrodynamic lubrication of point contact is considered. Conditions typical of an EHL contact in the piezoviscous-elastic regime entrained in pure rolling are investigated. Results are compared with the smooth surface solutions. Experiments are conducted to study the transient EHL effects in instrument ball bearings.

  18. Bioinspired lubricating films of cellulose nanofibrils and hyaluronic acid.

    PubMed

    Valle-Delgado, Juan José; Johansson, Leena-Sisko; Österberg, Monika

    2016-02-01

    The development of materials that combine the excellent mechanical strength of cellulose nanofibrils (CNF) with the lubricating properties of hyaluronic acid (HA) is a new, promising approach to cartilage implants not explored so far. A simple, solvent-free method to produce a very lubricating, strong cellulosic material by covalently attaching HA to the surface of CNF films is described in this work. A detailed analysis of the tribological properties of the CNF films with and without HA is also presented. Surface and friction forces at micro/nanoscale between model hard surfaces (glass microspheres) and the CNF thin films were measured using an atomic force microscope and the colloid probe technique. The effect of HA attachment, the pH and the ionic strength of the aqueous medium on the forces was examined. Excellent lubrication was observed for CNF films with HA attached in conditions where the HA layer was highly hydrated. These results pave the way for the development of new nanocellulose-based materials with good lubrication properties that could be used in biomedical applications.

  19. Vapor phase lubrication of a Ni-based superalloy

    SciTech Connect

    Hanyaloglu, B.; Fedor, D.C.; Graham, E.E.

    1995-03-01

    In addition to ceramics, alloys such as tool steel and nickel- and iron-based superalloys are being considered for high temperature applications such as missile bearings and low heat rejection engines. Studies were made to lubricate a nickel-based superalloy at 500{degrees}C, by using a vaporized aryl phosphate ester, at a concentration of 0.1% in air. From deposition and wear studies it was found that it was impossible to form a good polymeric coating on the superalloy surface. Energy dispersive X-ray analyzer (EDXA) analysis showed that this was due to minute quantities of aluminum in the alloy segregating to the surface, upon being heated to 500{degrees}C, forming a passive oxide coating. It was necessary to activate the surface, in order to lubricate the material successfully. A method of activation by electrodepositing the surface with a layer of iron oxide was developed. Once activated, a good lubricous polymer was formed on the superalloy surface. Tests performed under dynamic conditions and 1 MPa pressure, using an activated specimen surface showed no wear and a coefficient of friction ({mu}) of 0.05. These results stress the importance of material selection for high temperature vapor phase lubrication. 15 refs., 13 figs., 2 tabs.

  20. Bioinspired lubricating films of cellulose nanofibrils and hyaluronic acid.

    PubMed

    Valle-Delgado, Juan José; Johansson, Leena-Sisko; Österberg, Monika

    2016-02-01

    The development of materials that combine the excellent mechanical strength of cellulose nanofibrils (CNF) with the lubricating properties of hyaluronic acid (HA) is a new, promising approach to cartilage implants not explored so far. A simple, solvent-free method to produce a very lubricating, strong cellulosic material by covalently attaching HA to the surface of CNF films is described in this work. A detailed analysis of the tribological properties of the CNF films with and without HA is also presented. Surface and friction forces at micro/nanoscale between model hard surfaces (glass microspheres) and the CNF thin films were measured using an atomic force microscope and the colloid probe technique. The effect of HA attachment, the pH and the ionic strength of the aqueous medium on the forces was examined. Excellent lubrication was observed for CNF films with HA attached in conditions where the HA layer was highly hydrated. These results pave the way for the development of new nanocellulose-based materials with good lubrication properties that could be used in biomedical applications. PMID:26674836

  1. Fuel Plume Image Mixing Analysis Formulation With Proper Treatment of Non-Constant Velocity Flowfields

    NASA Technical Reports Server (NTRS)

    Mekkes, Gregory L.

    2000-01-01

    A previously developed technique allows an estimate of integral mixing to be obtained from an image of laser scattered light from particle seeded fuel in the hypervelocity flow through a scramjet combustor. This previous mixing analysis formulation contains an assumption of a constant velocity flowfield across the plane of the fuel plume image. For high-speed scramjet combustors, the velocity flowfield is quite uniform and an assumption of constant velocity works well. Applying this same mixing analysis technique to fuel plume images obtained from a mid-speed scramjet combustor makes it desirable to remove the constant velocity assumption. This is due to the non-uniform velocity flowfields present in mid-speed scramjet combustors. A new formulation of the mixing analysis methodology is developed and presented so that the technique can be applied to a mid-speed scramjet combustor without the need to assume a constant velocity flowfield.

  2. The contribution of lubricant to the formation of particulate matter with reactivity controlled compression ignition in light-duty diesel engines

    SciTech Connect

    Storey, John Morse; Curran, Scott; Dempsey, Adam B.; Lewis, Sr., Samuel Arthur; Reitz, Rolf; Walker, N. Ryan; Wright, Chris

    2014-12-25

    Reactivity controlled compression ignition (RCCI) has been shown in single- and multi-cylinder engine research to achieve high thermal efficiencies with ultra-low NOX and soot emissions. The nature of the particulate matter (PM) produced by RCCI operation has been shown in recent research to be different than that of conventional diesel combustion and even diesel low-temperature combustion. Previous research has shown that the PM from RCCI operation contains a large amount of organic material that is volatile and semi-volatile. However, it is unclear if the organic compounds are stemming from fuel or lubricant oil. The PM emissions from dual-fuel RCCI were investigated in this study using two engine platforms, with an emphasis on the potential contribution of lubricant. Both engine platforms used the same base General Motors (GM) 1.9-L diesel engine geometry. The first study was conducted on a single-cylinder research engine with primary reference fuels (PRFs), n-heptane, and iso-octane. The second study was conducted on a four-cylinder GM 1.9-L ZDTH engine which was modified with a port fuel injection (PFI) system while maintaining the stock direct injection fuel system. Multi-cylinder RCCI experiments were run with PFI gasoline and direct injection of 2-ethylhexyl nitrate (EHN) mixed with gasoline at 5 % EHN by volume. In addition, comparison cases of conventional diesel combustion (CDC) were performed. Particulate size distributions were measured, and PM filter samples were collected for analysis of lube oil components. Triplicate PM filter samples (i.e., three individual filter samples) for both gas chromatography-mass spectroscopy (GC-MS; organic) analysis and X-ray fluorescence (XRF; metals) were obtained at each operating point and queued for analysis of both organic species and lubricant metals. Here, the results give a clear indication that lubricants do not contribute significantly to the formation of RCCI PM.

  3. The contribution of lubricant to the formation of particulate matter with reactivity controlled compression ignition in light-duty diesel engines

    DOE PAGES

    Storey, John Morse; Curran, Scott; Dempsey, Adam B.; Lewis, Sr., Samuel Arthur; Reitz, Rolf; Walker, N. Ryan; Wright, Chris

    2014-12-25

    Reactivity controlled compression ignition (RCCI) has been shown in single- and multi-cylinder engine research to achieve high thermal efficiencies with ultra-low NOX and soot emissions. The nature of the particulate matter (PM) produced by RCCI operation has been shown in recent research to be different than that of conventional diesel combustion and even diesel low-temperature combustion. Previous research has shown that the PM from RCCI operation contains a large amount of organic material that is volatile and semi-volatile. However, it is unclear if the organic compounds are stemming from fuel or lubricant oil. The PM emissions from dual-fuel RCCI weremore » investigated in this study using two engine platforms, with an emphasis on the potential contribution of lubricant. Both engine platforms used the same base General Motors (GM) 1.9-L diesel engine geometry. The first study was conducted on a single-cylinder research engine with primary reference fuels (PRFs), n-heptane, and iso-octane. The second study was conducted on a four-cylinder GM 1.9-L ZDTH engine which was modified with a port fuel injection (PFI) system while maintaining the stock direct injection fuel system. Multi-cylinder RCCI experiments were run with PFI gasoline and direct injection of 2-ethylhexyl nitrate (EHN) mixed with gasoline at 5 % EHN by volume. In addition, comparison cases of conventional diesel combustion (CDC) were performed. Particulate size distributions were measured, and PM filter samples were collected for analysis of lube oil components. Triplicate PM filter samples (i.e., three individual filter samples) for both gas chromatography-mass spectroscopy (GC-MS; organic) analysis and X-ray fluorescence (XRF; metals) were obtained at each operating point and queued for analysis of both organic species and lubricant metals. Here, the results give a clear indication that lubricants do not contribute significantly to the formation of RCCI PM.« less

  4. In situ confocal Raman spectroscopy of lubricants in a soft elastohydrodynamic tribological contact

    NASA Astrophysics Data System (ADS)

    Bongaerts, J. H. H.; Day, J. P. R.; Marriott, C.; Pudney, P. D. A.; Williamson, A.-M.

    2008-07-01

    This paper describes an experimental setup that combines friction measurements with in situ confocal Raman microscopy on a lubricating fluid film. The setup allows the determination of film thickness and shear-rate profiles, the position-dependent lubricant composition within the rubbing contact, as well as optical imaging of the contact and its surroundings. The tribological contact can be investigated at continuous rubbing conditions over a range of sliding speeds from 1×10-3to2m/s. The setup's capabilities are demonstrated for a soft poly(dimethylsiloxane) sphere pressed and rotated against a quartz flat. Friction forces are presented in the boundary, mixed, and elastohydrodynamic lubrication (EHL) regimes for both a hydrophilic and a hydrophobic flat surface. Optical images of the contact show that, for single-phase aqueous Newtonian lubricants in the EHL regime, starvation of the contact occurs above a critical value of the product of the entrainment speed and the lubricant viscosity. Starvation results in a lower film thickness and lower friction values than predicted by numerical calculations that do not take starvation into account. The capability to determine, using Raman spectroscopy, the composition of the lubricant within the contact is demonstrated for oil-in-water emulsions, stabilized by a nonionic surfactant (Tween 60). The oil concentration was found to depend on both the sliding speed and the position within the rubbing contact. For the investigated tribological conditions, the oil content within the contact was lower than that of the bulk emulsion. This is attributed to the fact that the aqueous matrix phase preferentially wets the hydrophilic quartz slide, which prevents oil droplets from entering the contact if the film thickness is of the order of the droplet size. The ability to determine friction forces, lubricant composition and film thickness, and shear-rate profiles will provide invaluable information in the pursuit of a better

  5. Spectral analysis of the turbulent mixing of two fluids

    SciTech Connect

    Steinkamp, M.J.

    1995-09-01

    We describe a spectral approach to the investigation of fluid instability, generalized turbulence, and the interpenetration of fluids across an interface. The Technique also applies to a single fluid with large variations in density. Departures of fluctuating velocity components from the local mean are far subsonic, but the mean Mach number can be large. Validity of the description is demonstrated by comparisons with experiments on turbulent mixing due to the late stages of Rayleigh-Taylor instability, when the dynamics become approximately self-similar in response to a constant body force. Generic forms for anisotropic spectral structure are described and used as a basis for deriving spectrally integrated moment equations that can be incorporated into computer codes for scientific and engineering analyses.

  6. Spectral analysis of the turbulent mixing of two fluids

    SciTech Connect

    Steinkamp, M.J.

    1996-02-01

    The authors describe a spectral approach to the investigation of fluid instability, generalized turbulence, and the interpenetration of fluids across an interface. The technique also applies to a single fluid with large variations in density. Departures of fluctuating velocity components from the local mean are far subsonic, but the mean Mach number can be large. Validity of the description is demonstrated by comparisons with experiments on turbulent mixing due to the late stages of Rayleigh-Taylor instability, when the dynamics become approximately self-similar in response to a constant body force. Generic forms for anisotropic spectral structure are described and used as a basis for deriving spectrally integrated moment equations that can be incorporated into computer codes for scientific and engineering analyses.

  7. Analysis of a mixed space-time diffusion equation

    NASA Astrophysics Data System (ADS)

    Momoniat, Ebrahim

    2015-06-01

    An energy method is used to analyze the stability of solutions of a mixed space-time diffusion equation that has application in the unidirectional flow of a second-grade fluid and the distribution of a compound Poisson process. Solutions to the model equation satisfying Dirichlet boundary conditions are proven to dissipate total energy and are hence stable. The stability of asymptotic solutions satisfying Neumann boundary conditions coincides with the condition for the positivity of numerical solutions of the model equation from a Crank-Nicolson scheme. The Crank-Nicolson scheme is proven to yield stable numerical solutions for both Dirichlet and Neumann boundary conditions for positive values of the critical parameter. Numerical solutions are compared to analytical solutions that are valid on a finite domain.

  8. Topological analysis of a mixing flow generated by natural convection

    NASA Astrophysics Data System (ADS)

    Contreras, Pablo Sebastián; de la Cruz, Luis Miguel; Ramos, Eduardo

    2016-01-01

    We use topological tools to describe the natural convective motion and the Lagrangian trajectories of a flow generated by stepwise, alternating heating and cooling protocol of opposite vertical walls of a cubic container. The working fluid considered is Newtonian and the system is in presence of the acceleration of gravity but the nonlinear terms are neglected, i.e., we study the piece-wise steady and linear problem. For this convective mixing flow, we identify invariant surfaces formed by the Lagrangian orbits of massless tracers that are topologically equivalent to spherical shells and period-1 lines with elliptic and hyperbolic segments that are located on symmetry planes. We describe the previous features as functions of the Rayleigh number in the range 3 × 104 ≤ Ra ≤ 5 × 105. We show that this system shares properties with other systems with non-toroidal invariant surfaces.

  9. Box-Cox Mixed Logit Model for Travel Behavior Analysis

    NASA Astrophysics Data System (ADS)

    Orro, Alfonso; Novales, Margarita; Benitez, Francisco G.

    2010-09-01

    To represent the behavior of travelers when they are deciding how they are going to get to their destination, discrete choice models, based on the random utility theory, have become one of the most widely used tools. The field in which these models were developed was halfway between econometrics and transport engineering, although the latter now constitutes one of their principal areas of application. In the transport field, they have mainly been applied to mode choice, but also to the selection of destination, route, and other important decisions such as the vehicle ownership. In usual practice, the most frequently employed discrete choice models implement a fixed coefficient utility function that is linear in the parameters. The principal aim of this paper is to present the viability of specifying utility functions with random coefficients that are nonlinear in the parameters, in applications of discrete choice models to transport. Nonlinear specifications in the parameters were present in discrete choice theory at its outset, although they have seldom been used in practice until recently. The specification of random coefficients, however, began with the probit and the hedonic models in the 1970s, and, after a period of apparent little practical interest, has burgeoned into a field of intense activity in recent years with the new generation of mixed logit models. In this communication, we present a Box-Cox mixed logit model, original of the authors. It includes the estimation of the Box-Cox exponents in addition to the parameters of the random coefficients distribution. Probability of choose an alternative is an integral that will be calculated by simulation. The estimation of the model is carried out by maximizing the simulated log-likelihood of a sample of observed individual choices between alternatives. The differences between the predictions yielded by models that are inconsistent with real behavior have been studied with simulation experiments.

  10. Rheology and tribology of lubricants with polymeric viscosity modifiers

    NASA Astrophysics Data System (ADS)

    Babak, LotfizadehDehkordi

    Elastohydrodynamic lubrication (EHL) theory has been used to model the lubrication state of antifriction machine elements, where initial viscosity and pressure viscosity coefficients are essential parameters in film thickness modeling. Since the pressures of lubricants in the contact zone can be very high, it is important to know the rheological properties of lubricants in these pressure and temperature regimes. The characteristics of viscosity behavior as a function of pressure are also essential for a universal definition of the pressure viscosity coefficient in order to estimate film thickness in an EHL regime. In this study, viscosities and pressure-viscosity coefficients of ten commercial engine and gear oils and seventeen laboratory-produced oil/polymer viscosity modifiers (VM) additives are measured up to 1.3 GPa at 40, 75 and 100 °C. For the first time, a sharp increase in the viscosity and piezoviscous factor is observed in both mineral-based and synthetic-based oils with different VMs. Analysis of the experimental results indicates that sharp increase in viscosity observed in these experiments are believed to arise from physical changes in the VMs, that is liquid-solid phase transition. Evidence is offered that polymer properties such as molecular weight, concentration and structure influence the onset of the phase transitions. A modified Yasutomi model, which normally describes the pressure dependence of the viscosity of lubricants very well, fails to predict the viscosity of the specimens above the onset of sharp increase in viscosity. A design of experiment (DOE) analysis using Design-Expert software indicates that pressure and temperature are the most critical parameters in the viscosity variation. Tribological tests demonstrate that wear in the contact, zone occurs at temperatures and stresses that coincides with the VM phase transitions in both commercial and laboratory synthesized oil/VMs. Tribological results also indicate that the onset of the

  11. Development of solid-lubricated ball-screws for use in space

    NASA Technical Reports Server (NTRS)

    Chiba, Masatoshi; Gyougi, Toru; Nishimura, Makoto; Seki, Katsumi

    1991-01-01

    Ball-screws lubricated by solid lubricant films containing molybdenum disulphide are developed. The ball-screws (shaft diameter: phi 25 mm, length: 667 mm) were operated under a load of 40 to 120 N at a speed of 1.5 to 200 rpm at 10(exp -5) Pa. First, ball-screws made of stainless steel SUS 440C were studied using test equipment originally designed for this study. To reduce weight, the next step taken was to develop a ball-screw made of 6Al-4V-titanium. Long wear-life of more than 1 x 10(exp 7) revolutions was achieved with solid lubricated ball-screws made of SUS 440C and 6Al-4V-titanium in a hard vacuum. According to the surface profile of the shaft measured after 1 x 10(exp 7) revolutions, more solid lubricant remained on the surface of 6Al-4V-titanium than that of stainless steel. Auger and EPMA analysis confirmed lubrication was maintained by solid lubricant on nuts and screws after the lubricant films on the balls were worn off.

  12. Application of BP Neural Network Based on Genetic Algorithm in Quantitative Analysis of Mixed GAS

    NASA Astrophysics Data System (ADS)

    Chen, Hongyan; Liu, Wenzhen; Qu, Jian; Zhang, Bing; Li, Zhibin

    Aiming at the problem of mixed gas detection in neural network and analysis on the principle of gas detection. Combining BP algorithm of genetic algorithm with hybrid gas sensors, a kind of quantitative analysis system of mixed gas is designed. The local minimum of network learning is the main reason which affects the precision of gas analysis. On the basis of the network study to improve the learning algorithms, the analyses and tests for CO, CO2 and HC compounds were tested. The results showed that the above measures effectively improve and enhance the accuracy of the neural network for gas analysis.

  13. Analysis and testing of high entrainment single nozzle jet pumps with variable mixing tubes

    NASA Technical Reports Server (NTRS)

    Hickman, K. E.; Hill, P. G.; Gilbert, G. B.

    1972-01-01

    An analytical model was developed to predict the performance characteristics of axisymmetric single-nozzle jet pumps with variable area mixing tubes. The primary flow may be subsonic or supersonic. The computer program uses integral techniques to calculate the velocity profiles and the wall static pressures that result from the mixing of the supersonic primary jet and the subsonic secondary flow. An experimental program was conducted to measure mixing tube wall static pressure variations, velocity profiles, and temperature profiles in a variable area mixing tube with a supersonic primary jet. Static pressure variations were measured at four different secondary flow rates. These test results were used to evaluate the analytical model. The analytical results compared well to the experimental data. Therefore, the analysis is believed to be ready for use to relate jet pump performance characteristics to mixing tube design.

  14. Influence of liquid lubricant properties on their performance

    NASA Technical Reports Server (NTRS)

    Wedeven, V.

    1972-01-01

    The influence of lubricant properties on performance is considered in connection with various mechanisms of lubrication. The effects of temperature and pressure on viscosity, which is important in hydrodynamic and elastohydrodynamic lubrication, is presented using a correlation postulated by Roelands. Under elastohydrodynamic conditions it is important to distinguish between the influence of lubricant properties within the inlet region and the Hertz region since each performs different functions. The role of lubricant transport properties such as surface tension is considered in connection with lubricant starvation. Since the lubrication of practical surfaces usually involves boundary as well as hydrodynamic mechanisms, both the chemical and physical properties significantly influence the lubricant's performance.

  15. Tribological Properties of CrN Coating Under Lubrication Conditions

    NASA Astrophysics Data System (ADS)

    Lubas, Janusz

    2012-08-01

    The paper presents research results of the influence of CrN coating on the friction parameters in friction pairs under lubricated friction conditions. The formed CrN homogeneous coating and CrN-steel 46Cr2 "ring" structure coating was matched under test conditions with a counterpart made from SAE-48 and SAE-783 bearing alloys. Tested sliding pairs were lubricated with 5W/40 Lotos synthetic engine oil. The tribological test was conducted on block-on-ring tester. The applied modification technologies of the surface layer of steel allowed for obtaining construction materials with pre-determined tribological characteristics required for the elements of friction pairs in lubricated contact. The results of the tests proved the possibility of implementing CrN coating in friction pairs, which work under mixed friction conditions. The results showed differences in the wear of bearing alloy, as the effect of the interaction between the co-operating surface layers and of the physiochemical changes of their surfaces, induced by external forces. The smallest wear of the bearing alloy occurs during the cooperation with the nitrided layer, whereas the largest wear occurs during the cooperation with the homogenous CrN coating. The CrN coating-46Cr2 steel "ring structure" decreases friction resistance during the start-up of the sliding pair, as well as lowers the level of the friction force and temperature in the friction area during co-operation with SAE-783 bearing alloys.

  16. Self-lubricating polymer composites and polymer transfer film lubrication for space applications

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1990-01-01

    The use of self-lubricating polymers and polymer composites in space is somewhat limited today. In general, they are only used when other methods are inadequate. There is potential, however, for these materials to make a significant impact on future space missions if properly utilized. Some of the different polymers and fillers used to make self-lubricating composites are surveyed. The mechanisms of composite lubrication and wear, the theory behind transfer film lubricating mechanisms, and some factors which affect polymer composite wear and transfer are examined. In addition, some of the current space tribology application areas for self-lubricating polymer composites and polymer transfer are mentioned.

  17. Fuel and lubricant additives from acid treated mixtures of vegetable oil derived amides and esters

    SciTech Connect

    Bonazza, B.R.; Devault, A.N.

    1981-05-26

    Vegetable oils such as corn oil, peanut oil, and soy oil are reacted with polyamines to form a mixture containing amides, imides, half esters, and glycerol with subsequent treatment with a strong acid such as sulfonic acid to produce a product mix that has good detergent properties in fuels and lubricants.

  18. ANALYSIS OF TURBULENT MIXING JETS IN LARGE SCALE TANK

    SciTech Connect

    Lee, S; Richard Dimenna, R; Robert Leishear, R; David Stefanko, D

    2007-03-28

    Flow evolution models were developed to evaluate the performance of the new advanced design mixer pump for sludge mixing and removal operations with high-velocity liquid jets in one of the large-scale Savannah River Site waste tanks, Tank 18. This paper describes the computational model, the flow measurements used to provide validation data in the region far from the jet nozzle, the extension of the computational results to real tank conditions through the use of existing sludge suspension data, and finally, the sludge removal results from actual Tank 18 operations. A computational fluid dynamics approach was used to simulate the sludge removal operations. The models employed a three-dimensional representation of the tank with a two-equation turbulence model. Both the computational approach and the models were validated with onsite test data reported here and literature data. The model was then extended to actual conditions in Tank 18 through a velocity criterion to predict the ability of the new pump design to suspend settled sludge. A qualitative comparison with sludge removal operations in Tank 18 showed a reasonably good comparison with final results subject to significant uncertainties in actual sludge properties.

  19. Water sources and mixing in riparian wetlands revealed by tracers and geospatial analysis

    NASA Astrophysics Data System (ADS)

    Lessels, Jason S.; Tetzlaff, Doerthe; Birkel, Christian; Dick, Jonathan; Soulsby, Chris

    2016-01-01

    Mixing of waters within riparian zones has been identified as an important influence on runoff generation and water quality. Improved understanding of the controls on the spatial and temporal variability of water sources and how they mix in riparian zones is therefore of both fundamental and applied interest. In this study, we have combined topographic indices derived from a high-resolution Digital Elevation Model (DEM) with repeated spatially high-resolution synoptic sampling of multiple tracers to investigate such dynamics of source water mixing. We use geostatistics to estimate concentrations of three different tracers (deuterium, alkalinity, and dissolved organic carbon) across an extended riparian zone in a headwater catchment in NE Scotland, to identify spatial and temporal influences on mixing of source waters. The various biogeochemical tracers and stable isotopes helped constrain the sources of runoff and their temporal dynamics. Results show that spatial variability in all three tracers was evident in all sampling campaigns, but more pronounced in warmer dryer periods. The extent of mixing areas within the riparian area reflected strong hydroclimatic controls and showed large degrees of expansion and contraction that was not strongly related to topographic indices. The integrated approach of using multiple tracers, geospatial statistics, and topographic analysis allowed us to classify three main riparian source areas and mixing zones. This study underlines the importance of the riparian zones for mixing soil water and groundwater and introduces a novel approach how this mixing can be quantified and the effect on the downstream chemistry be assessed.

  20. Water sources and mixing in riparian wetlands revealed by tracers and geospatial analysis

    PubMed Central

    Tetzlaff, Doerthe; Birkel, Christian; Dick, Jonathan; Soulsby, Chris

    2016-01-01

    Abstract Mixing of waters within riparian zones has been identified as an important influence on runoff generation and water quality. Improved understanding of the controls on the spatial and temporal variability of water sources and how they mix in riparian zones is therefore of both fundamental and applied interest. In this study, we have combined topographic indices derived from a high‐resolution Digital Elevation Model (DEM) with repeated spatially high‐resolution synoptic sampling of multiple tracers to investigate such dynamics of source water mixing. We use geostatistics to estimate concentrations of three different tracers (deuterium, alkalinity, and dissolved organic carbon) across an extended riparian zone in a headwater catchment in NE Scotland, to identify spatial and temporal influences on mixing of source waters. The various biogeochemical tracers and stable isotopes helped constrain the sources of runoff and their temporal dynamics. Results show that spatial variability in all three tracers was evident in all sampling campaigns, but more pronounced in warmer dryer periods. The extent of mixing areas within the riparian area reflected strong hydroclimatic controls and showed large degrees of expansion and contraction that was not strongly related to topographic indices. The integrated approach of using multiple tracers, geospatial statistics, and topographic analysis allowed us to classify three main riparian source areas and mixing zones. This study underlines the importance of the riparian zones for mixing soil water and groundwater and introduces a novel approach how this mixing can be quantified and the effect on the downstream chemistry be assessed. PMID:27478256

  1. Renewable Fuels and Lubricants Laboratory (Fact Sheet)

    SciTech Connect

    Not Available

    2014-08-01

    This fact sheet describes the Renewable Fuels and Lubricants (ReFUEL) Laboratory at the U.S. Department of Energy National Renewable Energy Laboratory (NREL) is a state-of-the-art research and testing facility for advanced fuels and vehicles. Research and development aims to improve vehicle efficiency and overcome barriers to the increased use of renewable diesel and other nonpetroleum-based fuels, such as biodiesel and synthetic diesel derived from biomass. The ReFUEL Laboratory features a chassis dynamometer for vehicle performance and emissions research, two engine dynamometer test cells for advanced fuels research, and precise emissions analysis equipment. As a complement to these capabilities, detailed studies of fuel properties, with a focus on ignition quality, are performed at NREL's Fuel Chemistry Laboratory.

  2. [Development of an Excel spreadsheet for meta-analysis of indirect and mixed treatment comparisons].

    PubMed

    Tobías, Aurelio; Catalá-López, Ferrán; Roqué, Marta

    2014-01-01

    Meta-analyses in clinical research usually aimed to evaluate treatment efficacy and safety in direct comparison with a unique comparator. Indirect comparisons, using the Bucher's method, can summarize primary data when information from direct comparisons is limited or nonexistent. Mixed comparisons allow combining estimates from direct and indirect comparisons, increasing statistical power. There is a need for simple applications for meta-analysis of indirect and mixed comparisons. These can easily be conducted using a Microsoft Office Excel spreadsheet. We developed a spreadsheet for indirect and mixed effects comparisons of friendly use for clinical researchers interested in systematic reviews, but non-familiarized with the use of more advanced statistical packages. The use of the proposed Excel spreadsheet for indirect and mixed comparisons can be of great use in clinical epidemiology to extend the knowledge provided by traditional meta-analysis when evidence from direct comparisons is limited or nonexistent.

  3. Automated Static Culture System Cell Module Mixing Protocol and Computational Fluid Dynamics Analysis

    NASA Technical Reports Server (NTRS)

    Kleis, Stanley J.; Truong, Tuan; Goodwin, Thomas J,

    2004-01-01

    This report is a documentation of a fluid dynamic analysis of the proposed Automated Static Culture System (ASCS) cell module mixing protocol. The report consists of a review of some basic fluid dynamics principles appropriate for the mixing of a patch of high oxygen content media into the surrounding media which is initially depleted of oxygen, followed by a computational fluid dynamics (CFD) study of this process for the proposed protocol over a range of the governing parameters. The time histories of oxygen concentration distributions and mechanical shear levels generated are used to characterize the mixing process for different parameter values.

  4. Discrimination of benign versus malignant mixed tumors of the salivary gland using digital image analysis.

    PubMed

    Layfield, L J; Hall, T L; Fu, Y S

    1989-03-01

    Seven benign and four malignant mixed tumors of the salivary gland, biopsied using fine-needle aspiration, were analyzed using digital image analysis. Mean nuclear form factor, perimeter, and area were significantly increased in malignant cases. Better separation between diagnostic categories, however, was achieved by utilizing the coefficient of variation (CV) within a case rather than mean value. Form factor CV alone divided cases into nonoverlapping diagnostic categories. This quantitative analog of "pleomorphism" provided a useful marker for malignancy in mixed tumors.

  5. 14 CFR 33.39 - Lubrication system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.39 Lubrication system. (a) The lubrication system of the engine must be designed and constructed so that it...

  6. Glass molding process with mold lubrication

    DOEpatents

    Davey, Richard G.

    1978-06-27

    Improvements are provided in glass forming processes of the type wherein hot metal blank molds are employed by using the complementary action of a solid film lubricant layer, of graphite dispersed in a cured thermoset organopolysiloxane, along with an overspray of a lubricating oil.

  7. Positive commandable oiler for satellite bearing lubrication

    NASA Technical Reports Server (NTRS)

    James, G. E.

    1977-01-01

    On-orbit commandable lubrication of ball bearings accomplished by direct oil application to the moving ball surfaces was studied. Test results for the lubricant applicator portion of the system are presented in conjunction with a design approach for the reservoir and metering components.

  8. Pressure-viscosity coefficient of biobased lubricants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Film thickness is an important tribological property that is dependent on the combined effect of lubricant properties, material property of friction surfaces, and the operating conditions of the tribological process. Pressure-viscosity coefficient (PVC) is one of the lubricant properties that influe...

  9. 30 CFR 56.14204 - Machinery lubrication.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Machinery lubrication. 56.14204 Section 56... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Machinery and Equipment Safety Practices and Operational Procedures § 56.14204 Machinery lubrication. Machinery...

  10. 30 CFR 57.14204 - Machinery lubrication.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Machinery lubrication. 57.14204 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Machinery and Equipment Safety Practices and Operational Procedures § 57.14204 Machinery lubrication. Machinery...

  11. 40 CFR 1065.740 - Lubricants.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Engine Fluids, Test Fuels, Analytical Gases and Other Calibration Standards § 1065.740 Lubricants... engine in use. (b) You may use lubrication additives, up to the levels that the additive...

  12. Biobased, environmentally friendly lubricants for processing plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetable oil based lubricants have excellent lubricity, biodegradability, good viscosity temperature characteristics and low evaporation loss, but poor thermos-oxidative stability and cold flow properties. This paper presents a systematic approach to improve the oxidative and cold flow behavior of...

  13. Control Methods of Operational Properties of Lubricants

    NASA Astrophysics Data System (ADS)

    Lysyannikova, N.; Kovalski, B.; Bezborodov, Yu; Lysyannikov, A.; Kravtsova, Ye; Shram, V.; Kovaleva, M.

    2016-06-01

    Some results of thermal-oxidation and temperature stability testing of motor oils are presented. The catalytic influence of metals on oxidizing processes in lubricants with use of steel 45 was determined. The parameters for identification of oils by groups of operational properties and quantity indicators of the influence of metals on oxidizing processes of lubricants are offered.

  14. Solubility, viscosity and density of refrigerant/lubricant mixtures

    SciTech Connect

    Henderson, D.R.

    1993-01-01

    This report presents results on low refrigerant concentration (70, 80, 90, and 100 weight percent lubricant) mixtures of the following fluids: CFC-12/ISO 32 naphthenic mineral oil; HCFC-22/ISO 32 naphthenic mineral oil; and HFC-134a/ISO 32 pentaerythritol ester mixed acid. These data have been reduced to engineering form and are presented in the form of a Daniel Chart. Scatter diagrams are given for the first fluid listed above, with the intent of illustrating the quality of data as well as providing the rationale for selecting the particular functional forms chosen to represent the experimental data. Equations are given along with statistical measures of goodness of fit.

  15. Bearing, gearing, and lubrication technology

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.

    1978-01-01

    Results of selected NASA research programs on rolling-element and fluid-film bearings, gears, and elastohydrodynamic lubrication are reported. Advances in rolling-element bearing material technology, which have resulted in a significant improvement in fatigue life, and which make possible new applications for rolling bearings, are discussed. Research on whirl-resistant, fluid-film bearings, suitable for very high-speed applications, is discussed. An improved method for predicting gear pitting life is reported. An improved formula for calculating the thickness of elastohydrodynamic films (the existence of which help to define the operating regime of concentrated contact mechanisms such as bearings, gears, and cams) is described.

  16. A High Temperature Vapor Phase Lubrication Study Utilizing a Thioether Liquid Lubricant

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo; Graham, E. Earl; Galvin, Thomas

    1997-01-01

    Much of the experimental work on vapor phase lubrication has employed certain organo phosphorous compounds as the vapor phase lubricant. Graham and Klaus, for instance, used tricresyl phosphate (TCP) and tributyl phosphate to vapor phase lubricate a four-ball wear tester using M50 steel balls at 370 C. Makki and Graham were able to vapor phase lubricate a reciprocating pin on plate tribometer using 1018 steel at 280 C with TCP vapor. Although a few organo phosphorous compounds, such as TCP, have been successfully used as vapor phase lubricants in many laboratory experiments, many problems remain unsolved. Two areas of concern relate to the 'durability' of phosphate deposited films and to the ability of the lubricating system to "self-recover" when vapor phase lubricated with an organo phosphorous compound. Durability refers to the ability of the deposited film to provide effective lubrication, for a period of time, after the vapor flow to the lubricating surfaces has been interrupted. Vapor phase lubrication tests, conducted at Cleveland State University with their high temperature tribometer, revealed that when TCP vapor flow to the lubricating surfaces was interrupted the frictional coefficient of the system rapidly increased from a value less than 0.1 to a value of 0.3 which was selected as our failure point. Self-recovery means the ability of the vapor phase lubricant to reduce the frictional coefficient of the lubricating system back down to value less than 0.1 after startup of the interrupted vapor flow. Lubrication tests conducted at Cleveland State University revealed that the high temperature tribometer could not self-recover after startup of the interrupted TCP vapor flow.

  17. Effective Teachers as Viewed by Students at a 2 Year College: A Multistage Mixed Analysis

    ERIC Educational Resources Information Center

    Wang, Jinhao; Gibson, Angela M.; Slate, John R.

    2007-01-01

    A multi-stage mixed analysis was used to examine stories from 423, primarily Hispanic, undergraduate students in the United States regarding their best and poorest K-12 teachers, along with responses to 10 Likert format survey items. In the quantitative analysis phase, participants expressed strong agreement with items derived from the literature…

  18. Generalized Path Analysis and Generalized Simultaneous Equations Model for Recursive Systems with Responses of Mixed Types

    ERIC Educational Resources Information Center

    Tsai, Tien-Lung; Shau, Wen-Yi; Hu, Fu-Chang

    2006-01-01

    This article generalizes linear path analysis (PA) and simultaneous equations models (SiEM) to deal with mixed responses of different types in a recursive or triangular system. An efficient instrumental variable (IV) method for estimating the structural coefficients of a 2-equation partially recursive generalized path analysis (GPA) model and…

  19. A procedure to estimate proximate analysis of mixed organic wastes.

    PubMed

    Zaher, U; Buffiere, P; Steyer, J P; Chen, S

    2009-04-01

    In waste materials, proximate analysis measuring the total concentration of carbohydrate, protein, and lipid contents from solid wastes is challenging, as a result of the heterogeneous and solid nature of wastes. This paper presents a new procedure that was developed to estimate such complex chemical composition of the waste using conventional practical measurements, such as chemical oxygen demand (COD) and total organic carbon. The procedure is based on mass balance of macronutrient elements (carbon, hydrogen, nitrogen, oxygen, and phosphorus [CHNOP]) (i.e., elemental continuity), in addition to the balance of COD and charge intensity that are applied in mathematical modeling of biological processes. Knowing the composition of such a complex substrate is crucial to study solid waste anaerobic degradation. The procedure was formulated to generate the detailed input required for the International Water Association (London, United Kingdom) Anaerobic Digestion Model number 1 (IWA-ADM1). The complex particulate composition estimated by the procedure was validated with several types of food wastes and animal manures. To make proximate analysis feasible for validation, the wastes were classified into 19 types to allow accurate extraction and proximate analysis. The estimated carbohydrates, proteins, lipids, and inerts concentrations were highly correlated to the proximate analysis; correlation coefficients were 0.94, 0.88, 0.99, and 0.96, respectively. For most of the wastes, carbohydrate was the highest fraction and was estimated accurately by the procedure over an extended range with high linearity. For wastes that are rich in protein and fiber, the procedure was even more consistent compared with the proximate analysis. The new procedure can be used for waste characterization in solid waste treatment design and optimization.

  20. Asperity lubrication and cavitation in face seals

    NASA Technical Reports Server (NTRS)

    Walowitt, J. A.

    1974-01-01

    The basic aspect of parallel-surface lubrication that distinguishes it from other areas of lubrication technology is that classical lubrication theory does not predict the existence of a stable hydrodynamic film for steady-state, isothermal, incompressible flow between smooth, parallel surfaces. Hydrodynamic films between apparently parallel surfaces have been observed in practice and are often essential for the reliable performance of thrust bearings and seals. In order to account for this fortunate discrepancy between classical theory and experiment, load-support mechanisms relating to accidential features characteristic of seal performance, which relax one or more of the assumptions in the classical theory and permit the theoretical prediction of load support are proposed. Some of the features that have been analyzed are vibratory effects such as wobble and bounce, surface waviness, nonsymmetric rotation resulting from various types of misalignment, lubricant density change, non-Newtonian lubricant effects, and surface roughness.

  1. Studying Mixing in Non-Newtonian Blue Maize Flour Suspensions Using Color Analysis

    PubMed Central

    Trujillo-de Santiago, Grissel; Rojas-de Gante, Cecilia; García-Lara, Silverio; Ballescá-Estrada, Adriana; Alvarez, Mario Moisés

    2014-01-01

    Background Non-Newtonian fluids occur in many relevant flow and mixing scenarios at the lab and industrial scale. The addition of acid or basic solutions to a non-Newtonian fluid is not an infrequent operation, particularly in Biotechnology applications where the pH of Non-Newtonian culture broths is usually regulated using this strategy. Methodology and Findings We conducted mixing experiments in agitated vessels using Non-Newtonian blue maize flour suspensions. Acid or basic pulses were injected to reveal mixing patterns and flow structures and to follow their time evolution. No foreign pH indicator was used as blue maize flours naturally contain anthocyanins that act as a native, wide spectrum, pH indicator. We describe a novel method to quantitate mixedness and mixing evolution through Dynamic Color Analysis (DCA) in this system. Color readings corresponding to different times and locations within the mixing vessel were taken with a digital camera (or a colorimeter) and translated to the CIELab scale of colors. We use distances in the Lab space, a 3D color space, between a particular mixing state and the final mixing point to characterize segregation/mixing in the system. Conclusion and Relevance Blue maize suspensions represent an adequate and flexible model to study mixing (and fluid mechanics in general) in Non-Newtonian suspensions using acid/base tracer injections. Simple strategies based on the evaluation of color distances in the CIELab space (or other scales such as HSB) can be adapted to characterize mixedness and mixing evolution in experiments using blue maize suspensions. PMID:25401332

  2. Ion-beam mixing of Fe/B layers for tribological applications

    SciTech Connect

    Fenske, G.R.; Hu, R.; Baldo, P.M.; Erck, R.A.; Erdemir, A.; Lee, R.H.; Busch, D.E.; Nichols, F.A.; Rehn, L.E.

    1990-01-01

    Ion-beam mixing of iron and boron deposited layers was investigated as a technique to produce improved tribological coatings on steel substrates. Analysis of the kinetics of the ion-mixing process indicated that processing temperatures between 300 and 450{degree}C were required to achieve mixing of iron and boron multilayered coatings. During film deposition, it is critical to avoid deposition processes such as rf sputtering that trap large quantities of inert gases in the growing films and form blisters during subsequent ion mixing at elevated temperatures. Tribological evaluation of annealed and ion-mixed coatings indicated that the major effect of the ion mixing is formation of hard, wear-resistant, polycrystalline Fe{sub 2}B and Fe{sub 3}B phases at 450{degree}C and amorphous layers at 300{degree}C. Under partially lubricated conditions, the hard phases increase the duration of a low-friction (coefficient of friction <0.2) regime by reducing wear, thereby maintaining a low surface roughness. Under boundary-lubrication conditions, reduced wear was observed in tests on ion-mixed samples and was found to be dependent on the humidity in the test environment. 16 refs., 9 figs., 3 tabs.

  3. A New Antiwear Additive/Surface Pretreatment for PFPE Liquid Lubricants

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo; Fusaro, Robert L.; Siebert, Mark; Keith, Theo; Jansen, Ralph; Herrera-Fierro, Pilar

    1995-01-01

    Pin-on-disk tribology experiments were conducted on a perfluoroalkylelher (PFPE) liquid lubricant with and without a new PFPE lubricant antiwear additive material, a silane. It was found that the silane provided moderate improvement in the antiwear performance of the PFPE lubricant when applied to the metallic surface as a surface coating or when added to the PFPE as a dispersion (emulsion). Slightly better results were obtained by using the combination of a surface coating and an emulsion of the silane. The silane emulsions or coatings did not affect the friction properties of the lubricant. Micro-Fourier transformation infrared (muFTIR) spectroscopy analysis was performed to study silane transfer films and the degradation of the PFPE. The silane was found to mitigate degradation of the PFPE which may have been the major reason for the improved antiwear performance observed.

  4. Evaluation of replacement thread lubricants for red lead and graphite in mineral oil

    SciTech Connect

    Jungling, T.L.; Rauth, D.R.; Goldberg, D.

    1998-04-30

    Eight commercially available thread lubricants were evaluated to determine the best replacement for Red Lead and Graphite in Mineral Oil (RLGMO). The evaluation included coefficient of friction testing, high temperature anti-seizing testing, room temperature anti-galling testing, chemical analysis for detrimental impurities, corrosion testing, off-gas testing, and a review of health and environmental factors. The coefficient of friction testing covered a wide variety of factors including stud, nut, and washer materials, sizes, manufacturing methods, surface coatings, surface finishes, applied loads, run-in cycles, and relubrication. Only one lubricant, Dow Corning Molykote P37, met all the criteria established for a replacement lubricant. It has a coefficient of friction range similar to RLGMO. Therefore, it can be substituted directly for RLGMO without changing the currently specified fastener torque values for the sizes, materials and conditions evaluated. Other lubricants did not perform as well as Molykote P37 in one or more test or evaluation categories.

  5. Automated acid and base number determination of mineral-based lubricants by fourier transform infrared spectroscopy: commercial laboratory evaluation.

    PubMed

    Winterfield, Craig; van de Voort, F R

    2014-12-01

    The Fluid Life Corporation assessed and implemented Fourier transform infrared spectroscopy (FTIR)-based methods using American Society for Testing and Materials (ASTM)-like stoichiometric reactions for determination of acid and base number for in-service mineral-based oils. The basic protocols, quality control procedures, calibration, validation, and performance of these new quantitative methods are assessed. ASTM correspondence is attained using a mixed-mode calibration, using primary reference standards to anchor the calibration, supplemented by representative sample lubricants analyzed by ASTM procedures. A partial least squares calibration is devised by combining primary acid/base reference standards and representative samples, focusing on the main spectral stoichiometric response with chemometrics assisting in accounting for matrix variability. FTIR(AN/BN) methodology is precise, accurate, and free of most interference that affects ASTM D664 and D4739 results. Extensive side-by-side operational runs produced normally distributed differences with mean differences close to zero and standard deviations of 0.18 and 0.26 mg KOH/g, respectively. Statistically, the FTIR methods are a direct match to the ASTM methods, with superior performance in terms of analytical throughput, preparation time, and solvent use. FTIR(AN/BN) analysis is a viable, significant advance for in-service lubricant analysis, providing an economic means of trending samples instead of tedious and expensive conventional ASTM(AN/BN) procedures.

  6. Low voltage reversible electrowetting exploiting lubricated polymer honeycomb substrates

    NASA Astrophysics Data System (ADS)

    Bormashenko, Edward; Pogreb, Roman; Bormashenko, Yelena; Grynyov, Roman; Gendelman, Oleg

    2014-04-01

    Low-voltage electrowetting-on-dielectric scheme realized with lubricated honeycomb polymer surfaces is reported. Polycarbonate honeycomb reliefs manufactured with the breath-figures self-assembly were impregnated with silicone and castor oils. The onset of the reversible electrowetting for silicone oil impregnated substrates occurred at 35 V, whereas for castor oil impregnated ones it took place at 80 V. The semi-quantitative analysis of electrowetting of impregnated surfaces is proposed.

  7. Method for calculation of storage life of packaged lubricating greases

    SciTech Connect

    Petrova, L.N.; Nazarov, V.I.; Podvigina, O.A.; Sazonova, N.S.; Viktorova, Y.S.

    1983-11-01

    The allowable term of storage of lubricating greases is determined by an intuitive-logical analysis called ''expert evaluations'' in which a successive comparison of quality indexes is measured and ranked according to technical standardization documentation. The properties that change the most of the viscosity, yield stress, colloidal stability and content of free alkali. These quality indexes were used as the basis for developing a procedure for predicting the storage life of greases, which is described.

  8. 32P-postlabelling analysis of DNA adducts in the skin of mice treated with petrol and diesel engine lubricating oils and exhaust condensates.

    PubMed

    Schoket, B; Hewer, A; Grover, P L; Phillips, D H

    1989-08-01

    Samples of unused or used petrol and diesel engine lubricating oils were applied to the shaved dorsal skin of 4- to 6-week-old male Parkes mice, either as a single treatment (50 microliters/mouse) or as four consecutive daily treatments (50 microliters/application). DNA isolated from the skin 24 h after the final treatment was digested to 3'-mononucleotides and analysed by 32P-postlabelling for the presence of aromatic adducts. Enhancement of sensitivity using butanol extraction or nuclease P1 digestion of the DNA hydrolysates led to the detection of up to eight adduct spots on polyethyleneimine-cellulose thin-layer chromatograms with samples of DNA from skin treated with used engine oils, at levels of 40-150 amol total adducts/micrograms DNA. Multiple treatments with the used oils gave rise to similar patterns of adducts in lung DNA. A single treatment of mouse skin with petrol engine exhaust condensate (50 microliters), or diesel engine exhaust condensate (50 microliters), containing 20 and 46 micrograms benzo[a]pyrene (BaP)/g respectively, gave rise to approximately 75 amol total adducts/micrograms DNA in skin. A significant proportion, 31 and 48% respectively, of the adducts formed by the petrol and diesel engine exhaust condensates co-chromatographed with the major BaP-DNA adduct, but with the used engine oils, only petrol engine oil, and not diesel engine oil, produced significant amounts of an adduct (22% of total) that corresponded to the BaP-DNA adduct.

  9. CFD mixing analysis of axially opposed rows of jets injected into confined crossflow

    NASA Technical Reports Server (NTRS)

    Bain, D. B.; Smith, C. E.; Holdeman, J. D.

    1993-01-01

    A computational fluid dynamics (CFD) parametric study was performed to analyze axially opposed rows of jets mixing with crossflow in a rectangular duct. Isothermal analysis was conducted to determine the influence of lateral geometric arrangement on mixing. Two lateral arrangements were analyzed: (1) inline (jets' centerlines aligned with each other on top and bottom walls), and (2) staggered (jets' centerlines offset with each other on top and bottom walls). For a jet-to-mainstream mass flow ratio (MR) of 2.0, design parameters were systematically varied for jet-to-mainstream momentum-flux ratios (J) between 16 and 64 and orifice spacing-to-duct height ratios (S/H) between 0.125 and 1.5. Comparisons were made between geometries optimized for S/H at a specified J. Inline configurations had a unique spacing for best mixing at a specified J. In contrast, staggered configurations had two 'good mixing' spacings for each J, one corresponding to optimum inline spacing and the other corresponding to optimum non-impinging jet spacing. The inline configurations, due to their smaller orifice size at optimum S/H, produced better initial mixing characteristics. At downstream locations (e.g. x/H of 1.5), the optimum non-impinging staggered configuration produced better mixing than the optimum inline configuration for J of 64; the opposite results were observed for J of 16. Increasing J resulted in better mixing characteristics if each configuration was optimized with respect to orifice spacing. Mixing performance was shown to be similar to results from previous dilution jet mixing investigations (MR less than 0.5).

  10. CFD Analysis of Mixing Characteristics of Several Fuel Injectors at Hypervelocity Flow Conditions

    NASA Technical Reports Server (NTRS)

    Drozda, Tomasz G.; Drummond, J. Philip; Baurle, Robert A.

    2016-01-01

    CFD analysis is presented of the mixing characteristics and performance of three fuel injectors at hypervelocity flow conditions. The calculations were carried out using the VULCAN-CFD solver and Reynolds-Averaged Simulations (RAS). The high Mach number flow conditions match those proposed for the planned experiments conducted as a part of the Enhanced Injection and Mixing Project (EIMP) at the NASA Langley Research Center. The EIMP aims to investigate scramjet fuel injection and mixing physics, improve the understanding of underlying physical processes, and develop enhancement strategies and functional relationships relevant to flight Mach numbers greater than eight. Because of the high Mach number flow considered, the injectors consist of a fuel placement device, a strut; and a fluidic vortical mixer, a ramp. These devices accomplish the necessary task of distributing and mixing fuel into the supersonic cross-flow albeit via different strategies. Both of these devices were previously studied at lower flight Mach numbers where they exhibited promising performance in terms of mixing efficiency and total pressure recovery. For comparison, a flush-wall injector is also included. This type of injector generally represents the simplest method of introducing fuel into a scramjet combustor, however, at high flight Mach number conditions, the dynamic pressure needed to induce sufficient fuel penetration may be difficult to achieve along with other requirements such as achieving desired levels of fuel-to-air mixing at the required equivalence ratio. The three injectors represent the baseline configurations planned for the experiments. The current work discusses the mixing flow field behavior and differences among the three fuel injectors, mixing performance as described by the mixing efficiency and the total pressure recovery, and performance considerations based on the thrust potential.

  11. Differentiation of mixed biological traces in sexual assaults using DNA fragment analysis

    PubMed Central

    Apostolov, Аleksandar

    2014-01-01

    During the investigation of sexual abuse, it is not rare that mixed genetic material from two or more persons is detected. In such cases, successful profiling can be achieved using DNA fragment analysis, resulting in individual genetic profiles of offenders and their victims. This has led to an increase in the percentage of identified perpetrators of sexual offenses. The classic and modified genetic models used, allowed us to refine and implement appropriate extraction, polymerase chain reaction and electrophoretic procedures with individual assessment and approach to conducting research. Testing mixed biological traces using DNA fragment analysis appears to be the only opportunity for identifying perpetrators in gang rapes. PMID:26019514

  12. Solid lubricant materials for high temperatures: A review

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1985-01-01

    Solid lubricants that can be used above 300 C in air are discussed, including coatings and self-lubricating composite bearing materials. The lubricants considered are representative dichalcogenides, graphite, graphite fluoride, polyimides, soft oxides, oxidatively stable fluorides, and hard coating materials. A few general design considerations revelant to solid lubrication are interspersed.

  13. Testing of nuclear grade lubricants and their effects on A540 B24 and A193 B7 bolting materials

    SciTech Connect

    Czajkowski, C.J.

    1985-01-01

    An investigation was performed on eleven commonly used lubricants by the nuclear power industry. The investigation included EDS analysis of the lubricants, notched-tensile constant extension rate testing of bolting materials with the lubricants, frictional testing of the lubricants and weight loss testing of a bonded solid film lubricant. The report generally concludes that there is a significant amount of variance in the mechanical properties of common bolting materials; that MoS/sub 2/ can hydrolyze to form H/sub 2/S at 100/sup 0/C and cause stress corrosion cracking (SCC) of bolting materials, and that the use of copper-containing lubricants can be potentially detrimental to high strength steels in an aqueous environment. Additionally, the testing of various lubricants disclosed that some lubricants contain potentially detrimental elements (e.g. S, Sb) which can promote SCC of the common bolting materials. One of the most significant findings of this report is the observation that both A193 B7 and A540 B24 bolting materials are susceptible to transgranular stress corrosion cracking in demineralized H/sub 2/O at 280/sup 0/C in notched tensile tests.

  14. Reduction and avoidance of lubricant mist demands an integrated assessment approach.

    PubMed

    Wahlmüller, E; Neubauer, H; Höflinger, W

    1999-08-01

    A case study to identify major factors for lubricant mist exposure covered 15 metal machining sites. The investigation included milling, turning, drilling and grinding applications. Systematic analysis considered all relevant data concerning the machine tool, the lubricant and the suction plant. The efficiency of the implemented maintenance program at the installed filter systems was checked by concentration measurements immediately before and after service. All performed measurements of lubricant aerosol and vapor loads upstream and downstream of the installed filter systems were carried out according to VDI 2066 and BIA 3110, respectively. The selection criteria for the sites to be investigated, the systematic nature of the data acquisition and the procedure of the analysis are demonstrated in detail by performing comparisons between selected applications using emulsions and those employing straight oil for lubrication. The results of the study identify recirculation of ventilated air as the major source of workplace exposure to airborne lubricant emissions. More than 60% of the demisters investigated emit air at total lubricant loads (aerosols and vapor) above the limit of 20 mg m-3 at any time of operation; which also means immediately after service. A common reason for exceeded aerosol loads in recirculated air is e.g. the fact that the type of filter system applied is often not suitable for the separation problem. Loads of lubricant vapor are usually higher at the processes which use water emulsions as lubricant. In a quarter of the cases the limits were exceeded solely due to high vapor loads even immediately after service. The exposure can be reduced by replacing the lubricant, installation of a vapor separation plant or avoiding air recirculation. Maintenance time of the demisting system and aerosol separation efficiency of state-of-the-art demisting systems can be expanded by implementation of enhanced preliminary filter stages. This study confirms that

  15. Reduction and avoidance of lubricant mist demands an integrated assessment approach.

    PubMed

    Wahlmüller, E; Neubauer, H; Höflinger, W

    1999-08-01

    A case study to identify major factors for lubricant mist exposure covered 15 metal machining sites. The investigation included milling, turning, drilling and grinding applications. Systematic analysis considered all relevant data concerning the machine tool, the lubricant and the suction plant. The efficiency of the implemented maintenance program at the installed filter systems was checked by concentration measurements immediately before and after service. All performed measurements of lubricant aerosol and vapor loads upstream and downstream of the installed filter systems were carried out according to VDI 2066 and BIA 3110, respectively. The selection criteria for the sites to be investigated, the systematic nature of the data acquisition and the procedure of the analysis are demonstrated in detail by performing comparisons between selected applications using emulsions and those employing straight oil for lubrication. The results of the study identify recirculation of ventilated air as the major source of workplace exposure to airborne lubricant emissions. More than 60% of the demisters investigated emit air at total lubricant loads (aerosols and vapor) above the limit of 20 mg m-3 at any time of operation; which also means immediately after service. A common reason for exceeded aerosol loads in recirculated air is e.g. the fact that the type of filter system applied is often not suitable for the separation problem. Loads of lubricant vapor are usually higher at the processes which use water emulsions as lubricant. In a quarter of the cases the limits were exceeded solely due to high vapor loads even immediately after service. The exposure can be reduced by replacing the lubricant, installation of a vapor separation plant or avoiding air recirculation. Maintenance time of the demisting system and aerosol separation efficiency of state-of-the-art demisting systems can be expanded by implementation of enhanced preliminary filter stages. This study confirms that

  16. Double angle seal forming lubricant film

    DOEpatents

    Ernst, William D.

    1984-01-01

    A lubricated piston rod seal which inhibits gas leaking from a high pressure chamber on one side of the seal to a low pressure chamber on the other side of the seal. A liquid is supplied to the surface of the piston rod on the low pressure side of the seal. This liquid acts as lubricant for the seal and provides cooling for the rod. The seal, which can be a plastic, elastomer or other material with low elastic modulus, is designed to positively pump lubricant through the piston rod/seal interface in both directions when the piston rod is reciprocating. The capacity of the seal to pump lubricant from the low pressure side to the high pressure side is less than its capacity to pump lubricant from the high pressure side to the low pressure side which ensures that there is zero net flow of lubricant to the high pressure side of the seal. The film of lubricant between the seal and the rod minimizes any sliding contact and prevents the leakage of gas. Under static conditions gas leakage is prevented by direct contact between the seal and the rod.

  17. Mechanism of lubrication by tricresylphosphate (TCP)

    NASA Technical Reports Server (NTRS)

    Faut, O. D.; Wheeler, D. R.

    1983-01-01

    A pin-on-disk tribometer equipped with an induction heater was used to study the coefficient of friction as a function of temperature for tricresylphosphate (TCP) on continuous vacuum melted (CVM) M-50 tool steel when the TCP was present in a liquid reservoir (bulk lubrication), and when it was applied as a liquid layer directly to the disk (limited lubrication). Under limited lubrication conditions, experiments were performed in dry ( 100 ppm H2O) air, dry ( 20 ppm H2O) nitrogen, dry nitrogen with the disks heated to 700 C then cooled to room temperature before the TCP was applied and the measurements made (preheated disks), and moist nitrogen using preheated disks. When the coefficient of friction was plotted as a function of the disk temperature, the friction decreased at a characteristic temperature, T sub r whose observed values were 265 C for bulk lubrication conditions in dry air, 225 C for limited lubrication conditions in dry air, and 215 C for limited lubrication conditions in dry nitrogen. No decrease in friction was observed with preheated disks; instead a sharp failure temperature was observed at 218 C, which was taken as the temperature about which the behavior of TCP should be judged, X-ray photoelectron spectroscopy confirmed the presence of phosphate on the surface of the iron pins used in the tribometer under TCP lubrication. Depth profile studies support the idea that a chemical reaction occurs between the TCP and the metal surface at T sub r.

  18. Robust and Drain Resistant Lubricated Omniphobic Fabrics

    NASA Astrophysics Data System (ADS)

    Kido, Cassidee; Damle, Viraj; Sun, Xiaoda; Roopesh, Ajay; Doudrick, Kyle; Rykaczewski, Konrad

    2014-11-01

    The implications of omniphobic fabrics range from stainproof clothing to civilian and military protection from chemical weapons. The challenge comes in developing a product that remains effective in repelling droplets of liquids with a wide range of surface tensions even after being subjected to various stimuli imposed by human use. Omniphobic fabrics can be made by infusing hydrophobic nanoparticle coated fibers with a low surface energy lubricant. These types of lubricant impregnated surfaces can shed large deposited droplets as well as condensed microdroplets of variety of low surface tension liquids. However, here we show that lubricated omniphobic fabrics can easily lose their properties due to degradation of the nanostructure coating or drainage of the lubricant upon contact with a porous surface. We also demonstrate that this issue can be resolved with use of cross-linked polymer coated fibers that are swollen with the lubricant. Use of flexible polymers avoids structure degradation due to fabric deformation, while swelling of the polymer with lubricant minimizes lubricant drainage upon contact maintaining the omniphobic characteristics of the fabric. KR acknowledges startup funding from ASU and collaborative effort with Dr. Tim Burgin and James R. Lee from Naval Surface Warfare Center Dahlgren Division.

  19. Metastasizing mixed tumor of salivary glands. A clinicopathologic and flow cytometric analysis.

    PubMed

    Wenig, B M; Hitchcock, C L; Ellis, G L; Gnepp, D R

    1992-09-01

    Among salivary gland neoplasms are a group of rare tumors that are histologically identical to benign mixed tumors that inexplicably metastasize; they have been called metastasizing mixed tumor (MZMT) of salivary glands. We report the clinicopathologic features and flow cytometric findings for 11 cases of MZMT. At the time of discovery of metastatic disease, the patients, six women and five men, ranged in age from 20 to 83 years. Primary sites of involvement included the parotid gland (eight cases), submandibular gland (two cases), and the nasal septum (one case). With one exception, all the patients had at least a single recurrences of their primary mixed tumor, but two or more recurrences were the norm before development of metastatic foci. The metastases were discovered from six to 52 years following the occurrence of the primary tumor. Metastatic deposits were identified in bone, lung, regional lymph nodes, skin, kidney, retroperitoneum, oral cavity, pharynx, calvarium, and central nervous system. The metastases either occurred simultaneously with an episode of recurrent mixed tumor (n = 5) or from 5 to 29 years after a recurrence (n = 6). The treatment of the primary, recurrent, and metastatic neoplasms was surgical excision. Follow-up, ranging from 8 months to 16 years following the diagnosis of MZMT, revealed seven patients to be alive without disease (64%) and two dead of causes unrelated to metastatic disease (18%). Two patients (18%) died as a direct result of metastatic tumor at 3 and 2 years after metastasis of their mixed tumors. Flow cytometric analysis revealed a diploid DNA cell population in the primary and/or metastatic tumors in nine cases. Aneuploid DNA cell content was identified in two of the cases. DNA ploidy levels and cell proliferation rates were compared with those of conventional benign mixed tumors and also with malignant mixed tumors. Retrospective analysis of histologic parameters (mitotic rate, cellular pleomorphism, infiltrative

  20. GAS MIXING ANALYSIS IN A LARGE-SCALED SALTSTONE FACILITY

    SciTech Connect

    Lee, S

    2008-05-28

    Computational fluid dynamics (CFD) methods have been used to estimate the flow patterns mainly driven by temperature gradients inside vapor space in a large-scaled Saltstone vault facility at Savannah River site (SRS). The purpose of this work is to examine the gas motions inside the vapor space under the current vault configurations by taking a three-dimensional transient momentum-energy coupled approach for the vapor space domain of the vault. The modeling calculations were based on prototypic vault geometry and expected normal operating conditions as defined by Waste Solidification Engineering. The modeling analysis was focused on the air flow patterns near the ventilated corner zones of the vapor space inside the Saltstone vault. The turbulence behavior and natural convection mechanism used in the present model were benchmarked against the literature information and theoretical results. The verified model was applied to the Saltstone vault geometry for the transient assessment of the air flow patterns inside the vapor space of the vault region using the potential operating conditions. The baseline model considered two cases for the estimations of the flow patterns within the vapor space. One is the reference nominal case. The other is for the negative temperature gradient between the roof inner and top grout surface temperatures intended for the potential bounding condition. The flow patterns of the vapor space calculated by the CFD model demonstrate that the ambient air comes into the vapor space of the vault through the lower-end ventilation hole, and it gets heated up by the Benard-cell type circulation before leaving the vault via the higher-end ventilation hole. The calculated results are consistent with the literature information. Detailed results and the cases considered in the calculations will be discussed here.

  1. Modelling of heavily loaded lubricated contacts

    NASA Astrophysics Data System (ADS)

    Sadeghi, Farshid; McClug, William D., Jr.; Kim, Kyung-Hoon; Osborn, Kevin; Lance, Brian

    1992-02-01

    Thermal elastohydrodynamic (EHD) lubrication of rolling/sliding line contacts is investigated to develop an interactive computer program for prediction of lubrication system performance. The user inputs lubricant and mechanical system physical properties as well as operating conditions of load and speed for calculation of contact zone pressure, temperature, traction, and stresses. This program is one of the first to include thermal effects in calculations and, therefore, can more accurately assess the critical tribological performance parameters at high load and speed conditions than previous prediction models. The program is written in the FORTRAN language and utilizes a UNIX operating system for high quality graphic output allowing easy visualization of results.

  2. Prediction of lubrication regimes in two-piece metacarpophalangeal prostheses.

    PubMed

    Joyce, Thomas J

    2007-01-01

    Various designs of two-piece finger prosthesis with conforming spherical surfaces have been proposed. These were compared by calculating the lubrication regime for the material combinations and operating conditions expected at the metacarpophalangeal joints of the fingers. Consideration was given to a range of loads from 2 to 50 N, a range of entraining velocities from 0 to 30 mm/s, and a range of prosthesis radii from 3 to 10 mm. This theoretical lubrication analysis indicated that the optimum material combination of those available for two-piece metacarpophalangeal prostheses is in the order: ceramic-on-ceramic; metal-on-metal; pyrocarbon-on-pyrocarbon; and metal-on-polymer. However, it should be recognised that other factors may take precedence when choosing a material combination for a design of finger prosthesis.

  3. Piezoelectrically-induced ultrasonic lubrication by way of Poisson effect

    NASA Astrophysics Data System (ADS)

    Dong, Sheng; Dapino, Marcelo J.

    2012-04-01

    It has been shown that the coefficient of dynamic friction between two surfaces decreases when ultrasonic vibra- tions are superimposed on the macroscopic sliding velocity. Instead of longitudinal vibrations, this paper focuses on the lateral contractions and expansions of an object in and around the half wavelength node region. This lateral motion is due to the Poisson effect (ratio of lateral strain to longitudinal strain) present in all materials. We numerically and experimentally investigate the Poisson-effect ultrasonic lubrication. A motor effect region is identified in which the effective friction force becomes negative as the vibratory waves drive the motion of the interface. Outside of the motor region, friction lubrication is observed with between 30% and 60% friction force reduction. A "stick-slip" contact model associated with horn kinematics is presented for simulation and analysis purposes. The model accurately matches the experiments for normal loads under 120 N.

  4. Evaluating lubricant performance by 3D profilometry of wear scars

    NASA Astrophysics Data System (ADS)

    Georgescu, C.; Deleanu, L.; Pirvu, C.

    2016-08-01

    Due to improvement in analysing surface texture and optical instruments for investigating the texture surface, the authors propose to evaluate the lubricant performance by analysing the change in several 3D parameters in comparison to an analysis on 2D profile. All the surface of the wear scar generated on the four ball machine is investigated and the conclusion is that from the tribological point of view, the 3D parameters reflect better the surface quality evolution after testing. Investigation was done on the wear scars generated on the three fixed balls, for five lubricants: a non-additivated transmission mineral oil (T90), two grades of rapeseed oil (coarse degummed and refined) and two grades of soybean oil (coarse and degummed).

  5. Factors affecting the forensic examination of automotive lubricating oils.

    PubMed

    Hibbard, Ryan; Goodpaster, John V; Evans, Michelle R

    2011-05-01

    Lubricating oil comparisons impact a variety of forensic investigations, including cases where oil was transferred from a suspect vehicle to the crime scene or victim. In this study, high-temperature gas chromatography/mass spectrometry was used to examine the influence of oil mixtures and oil changes over time on the comparison of known and questioned lubricating oils. Varying concentrations of oil mixtures were prepared and showed the potential for identifying individual components. Motor oils from 18 automobiles monitored over a 2-month period did not demonstrate significant changes in the chromatographic data. Chemometric analysis of motor oil mass spectral data provided little information regarding differentiation of, or changes in, the samples. Power steering fluid (PSF) from a naturally occurring leak collected from several locations was consistent with the PSF in the automobile's reservoir, and the PSF composition did not change over time. PMID:21361948

  6. Isothermal elastohydrodynamic lubrication of point contacts. 1: Theoretical formulation

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1975-01-01

    The isothermal elastohydrodynamic lubrication (EHL) of a point contact was analyzed numerically by simultaneously solving the elasticity and Reynolds equations. In the elasticity analysis the contact zone was divided into equal rectangular areas, and it was assumed that a uniform pressure was applied over each area. In the numerical analysis of the Reynolds equation, a phi analysis (where phi is equal to the pressure times the film thickness of the 3/2 power) was used to help the relaxation process. The EHL point contact analysis is applicable for the entire range of elliptical parameters and is valid for any combination of rolling and sliding within the contact.

  7. Elastohydrodynamic Lubrication with Polyolester Lubricants and HFC Refrigerants, Final Report, Volume 2

    SciTech Connect

    Gunsel, Selda; Pozebanchuk, Michael

    1999-04-01

    Lubrication properties of refrigeration lubricants were investigated in high pressure nonconforming contacts under different conditions of temperature, rolling speed, and refrigerant concentration. The program was based upon the recognition that the lubrication regime in refrigeration compressors is generally elastohydrodynamic or hydrodynamic, as determined by the operating conditions of the compressor and the properties of the lubricant. Depending on the compressor design, elastohydrodynamic lubrication conditions exist in many rolling and sliding elements of refrigeration compressors such as roller element bearings, gears, and rotors. The formation of an elastohydrodynamic film separating rubbing surfaces is important in preventing the wear and failure of compressor elements. It is, therefore, important to predict the elastohydrodynamic (EHD) performance of lubricants under realistic tribocontact renditions. This is, however, difficult as the lubricant properties that control film formation are critically dependent upon pressure and shear, and cannot be evaluated using conventional laboratory instruments. In this study, the elastohydrodynamic behavior of refrigeration lubricants with and without the presence of refrigerants was investigated using the ultrathin film EHD interferometry technique. This technique enables very thin films, down to less than 5 nm, to be measured accurately within an EHD contact under realistic conditions of temperature, shear, and pressure. The technique was adapted to the study of lubricant refrigerant mixtures. Film thickness measurements were obtained on refrigeration lubricants as a function of speed, temperature, and refrigerant concentration. The effects of lubricant viscosity, temperature, rolling speed, and refrigerant concentration on EHD film formation were investigated. From the film thickness measurements, effective pressure-viscosity coefficients were calculated. The lubricants studied in this project included two

  8. Contribution of unburned lubricating oil and diesel fuel to particulate emission from passenger cars

    NASA Astrophysics Data System (ADS)

    Brandenberger, Sandro; Mohr, Martin; Grob, Koni; Neukom, Hans Peter

    In this study we determined particle-bound paraffins in the exhaust of six light-duty diesel vehicles on a chassis dynamometer for different driving cycles and ambient temperatures. The filters containing particulate matter were extracted with dichloromethane in a Soxhlet apparatus, and the paraffin analysis was performed using two-dimensional normal phase high-pressure liquid chromatography (HPLC) coupled on-line to gas chromatography-flame ionization detection (GC-FID). The different molecular mass of lubricant and diesel paraffins facilitated the distinction between diesel and lubricant contribution to the emission. Although all vehicles were certified according to the same emission class, there were considerable variations between vehicles. The study showed that under cold-start conditions the organic mass fraction ranged from 10% to 30% with respect to particle mass and the paraffins from 30% to 60% with respect to the organic mass. With cold engine, falling ambient temperature increased the emission of unburned diesel fuel, whereas that from unburned lubricating oil was less affected. Under warm-start conditions, the ambient temperature had less impact on the emission of paraffins. The emissions were also affected by the operating conditions of the engine: driving cycles with higher mean load tend towards higher emissions of lubricant. The operating conditions also affected the distribution of paraffins: the emission of light paraffins seemed to be lower with higher load in the driving cycle. With an urban and a highway cycle, roughly 40% and 80% w/w, respectively, of unburned paraffins were contributed by the lubricant. Measurements of polycyclic aromatic hydrocarbons (PAH) in lubricating oil showed lubricant to be a sink for PAHs. As lubricant significantly contributes to the organic emission, as shown in this study, it can be assumed that it is also a significant source of PAH emissions.

  9. Starved elastohydrodynamic lubricated elliptical contacts

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.

    1980-01-01

    A theoretical study of the influence of lubricant starvation on film thickness and pressure in hard and soft elliptical elastohydrodynamic contacts is presented. From the results for both hard and soft EHL contacts a simple and important dimensionless inlet boundary distance is specified. This inlet boundary defines whether a fully flooded or a starved condition exists in the contact. Furthermore it is found that the film thickness for a starved condition could be written in dimensionless terms as a function of the inlet distance parameter and the film thickness for a fully flooded condition. Contour plots of pressure and film thickness in and around the contact are shown for fully flooded and starved conditions. The theoretical findings are compared directly with results obtained experimentally.

  10. Coatings for wear and lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1978-01-01

    Recent advances in the tribological uses of rf-sputtered and ion plated films of solid film lubricants (laminar solids, soft metals, organic polymers) and wear resistant refractory compounds (carbides, nitrides, silicides) are reviewed. The sputtering and ion plating potentials and the corresponding coatings formed were evaluated relative to the friction coefficient, wear endurance life and mechanical properties. The tribological and mechanical properties for each kind of film are discussed in terms of film adherence, coherence, density, grain size, morphology, internal stresses, thickness, and substrate conditions such as temperature, topography, chemistry and dc-biasing. The ion plated metallic films in addition to improved tribological properties also have better mechanical properties such as tensile strength and fatigue life.

  11. Ionic Liquids as Novel Lubricants and Additives for Diesel Engine Applications

    SciTech Connect

    Qu, Jun; Blau, Peter Julian; Dai, Sheng; Luo, Huimin; Meyer III, Harry M

    2009-01-01

    The lubricating properties of two ionic liquids with the same anion but different cations, one ammonium IL [C8H17]3NH.Tf2N and one imidazolium IL C10mim.Tf2N, were evaluated both in neat form and as oil additives. Experiments were conducted using a standardized reciprocating sliding test using a segment of a Cr-plated diesel engine piston ring against a grey cast iron flat specimen with simulated honing marks as on the engine cylinder liner. The selected ionic liquids were benchmarked against conventional hydrocarbon oils. Substantial friction and wear reductions, up to 55% and 34%, respectively, were achieved for the neat ionic liquids compared to a fully-formulated 15W40 engine oil. Adding 5 vol% ILs into mineral oil has demonstrated significant improvement in the lubricity. One blend even outperformed the 15W40 engine oil with 9% lower friction and 34% less wear. Lubrication regime modeling, worn surface morphology examination, and surface chemical analysis were conducted to help understand the lubricating mechanisms for ionic liquids. Results suggest great potential for using ionic liquids as base lubricants or lubricant additives for diesel engine applications.

  12. Production variability analysis of hot-mixed asphalt concrete containing reclaimed asphalt pavement. Final research report

    SciTech Connect

    Solaimanian, M.; Kennedy, T.W.

    1995-02-01

    A research project was undertaken to evaluate the production and construction variability of Hot Mix Asphalt Concrete (HMAC) containing high quantities of reclaimed asphalt pavement (RAP) material. Four construction projects were selected for this purpose. Two of the projects used 35 percent RAP material (both type-C mixes), while the other two used 40 percent (a type-B mix) and 50 percent (a type-D mix) of the RAP material, respectively. The projects differed in sizes, with total construction tonnage ranging from 10.9 million kg to 27.2 million kg (12,000 to 30,000 tons). In all cases, dedicated stockpiles of RAP material were used. Analysis was performed on the results obtained from the tests. The gradation and asphalt content deviations, air voids, penetration and viscosities, and stabilities, were included in the analysis. Pay adjustment factors were determined for gradation and asphalt content deviation, as well as for air voids (based on TxDOT Specification 3007). In general, these high-percent RAP projects indicated a variability higher than that of a typical HMAC without RAP. The pay adjustment factors for gradation and asphalt content deviation were lower than typical values. The construction gradations were finer than the job-mix formula target gradations, possibly a result of aggregate crushing during the milling operation.

  13. Students' Stories of Their Best and Poorest K-5 Teachers: A Mixed Data Analysis

    ERIC Educational Resources Information Center

    Slate, John R.; Capraro, Mary Margaret; Onwuegbuzie, Anthony J.

    2007-01-01

    In this study, a multi-stage mixed analysis was used to examine stories from 72 undergraduate teacher education students regarding their best and poorest K-5 teachers, alongside responses to Likert-format survey items. Participants expressed strong agreement with items derived from the literature concerning characteristics of effective teachers…

  14. A Mixed Methods Content Analysis of the Research Literature in Science Education

    ERIC Educational Resources Information Center

    Schram, Asta B.

    2014-01-01

    In recent years, more and more researchers in science education have been turning to the practice of combining qualitative and quantitative methods in the same study. This approach of using mixed methods creates possibilities to study the various issues that science educators encounter in more depth. In this content analysis, I evaluated 18…

  15. Hispanic College Students' Views of Effective Middle-School Teachers: A Multi-Stage Mixed Analysis

    ERIC Educational Resources Information Center

    Schulte, Don P.; Slate, John R.; Onwuegbuzie, Anthony J.

    2011-01-01

    In this multi-stage mixed-analysis study, the views of 437 Hispanic college students enrolled at two Hispanic-Serving Institutions in the Southwest of the USA were obtained concerning characteristics of effective middle-school teachers. Through the method of constant comparison (qualitative phase), 38 themes were determined to be present in…

  16. A note on joint versus gene-specific mixed model analysis of microarray gene expression data.

    PubMed

    Hoeschele, Ina; Li, Hua

    2005-04-01

    Currently, linear mixed model analyses of expression microarray experiments are performed either in a gene-specific or global mode. The joint analysis provides more flexibility in terms of how parameters are fitted and estimated and tends to be more powerful than the gene-specific analysis. Here we show how to implement the gene-specific linear mixed model analysis as an exact algorithm for the joint linear mixed model analysis. The gene-specific algorithm is exact, when the mixed model equations can be partitioned into unrelated components: One for all global fixed and random effects and the others for the gene-specific fixed and random effects for each gene separately. This unrelatedness holds under three conditions: (1) any gene must have the same number of replicates or probes on all arrays, but these numbers can differ among genes; (2) the residual variance of the (transformed) expression data must be homogeneous or constant across genes (other variance components need not be homogeneous) and (3) the number of genes in the experiment is large. When these conditions are violated, the gene-specific algorithm is expected to be nearly exact.

  17. Using Mixed-Method Design and Network Analysis to Measure Development of Interagency Collaboration

    ERIC Educational Resources Information Center

    Cross, Jennifer Eileen; Dickmann, Ellyn; Newman-Gonchar, Rebecca; Fagan, Jesse Michael

    2009-01-01

    In recent years, there has been increasing attention to the importance of interagency collaboration for improving community well-being, environmental and public health, and educational outcomes. This article uses a mixed-methods approach including network analysis to examine the changes in interagency collaboration in one site funded by the Safe…

  18. Doctoral Students' Reasons for Reading Empirical Research Articles: A Mixed Analysis

    ERIC Educational Resources Information Center

    Burgess, Melissa L.; Benge, Cindy; Onwuegbuzie, Anthony J.; Mallette, Marla H.

    2012-01-01

    Little is known about reading ability among doctoral students. Thus, we used a fully mixed concurrent equal status design (Leech & Onwuegbuzie, 2009) to examine 205 doctoral students in the College of Education and their reasons for reading research articles. A thematic analysis revealed 5 themes (subsumed by 2 meta-themes) explaining reasons…

  19. The basics of powder lubrication in high-temperature powder-lubricated dampers

    SciTech Connect

    Heshmat, H.; Walton, J.F. )

    1993-04-01

    The objective of this investigation is to develop a novel powder-lubricated rotor bearing system damper concept for use in high-temperature, high-speed rotating machinery such as advanced aircraft gas turbine engines. The approach discussed herein consists of replacing a conventional oil lubrication or frictional damper system with a powder lubrication system that uses the process particulates or externally fed powder lubricant. Unlike previous work in this field, this approach is based on the postulate of the quasi-hydrodynamic nature of powder lubrication. This postulate is deduced from past observation and present verification that there are a number of basic features of powder flow in narrow interfaces that have the characteristic behavior of fluid film lubrication. In addition to corroborating the basic mechanism of powder lubrication, the conceptual and experimental work performed in this program provides guidelines for selection of the proper geometries, materials, and powders suitable for this tribological process. The present investigation describes the fundamentals of quasi-hydrodynamic powder lubrication and defines the rationale underlying the design of the test facility. The performance and the results of the experimental program present conclusions reached regarding design requirements as well as the formulation of a proper model of quasi-hydrodynamic powder lubrication.

  20. Personal Breathing Zone Exposures among Hot-Mix Asphalt Paving Workers; Preliminary Analysis for Trends and Analysis of Work Practices That Resulted in the Highest Exposure Concentrations

    PubMed Central

    Osborn, Linda V.; Snawder, John E.; Kriech, Anthony J.; Cavallari, Jennifer M.; McClean, Michael D.; Herrick, Robert F.; Blackburn, Gary R.; Olsen, Larry D.

    2015-01-01

    An exposure assessment of hot-mix asphalt (HMA) paving workers was conducted to determine which of four exposure scenarios impacted worker exposure and dose. Goals of this report are to present the personal-breathing zone (PBZ) data, discuss the impact of substituting the releasing/cleaning agent, and discuss work practices that resulted in the highest exposure concentration for each analyte. One-hundred-seven PBZ samples were collected from HMA paving workers on days when diesel oil was used as a releasing/cleaning agent. An additional 36 PBZ samples were collected on days when B-100 (100% biodiesel, containing no petroleum-derived products) was used as a substitute releasing/cleaning agent. Twenty-four PBZ samples were collected from a reference group of concrete workers, who also worked in outdoor construction but had no exposure to asphalt emissions. Background and field blank samples were also collected daily. Total particulates and the benzene soluble fraction were determined gravimetrically. Total organic matter was determined using gas chromatography (GC) with flame ionization detection and provided qualitative information about other exposure sources contributing to worker exposure besides asphalt emissions. Thirty-three individual polycyclic aromatic compounds (PACs) were determined using GC with time-offlight mass spectrometry; results were presented as either the concentration of an individual PAC or a summation of the individual PACs containing either 2- to 3-rings or 4- to 6-rings. Samples were also screened for PACs containing 4- to 6-rings using fluorescence spectroscopy. Arithmetic means, medians, and box plots of the PBZ data were used to evaluate trends in the data. Box plots illustrating the diesel oil results were more variable than the B-100. Also, the highest diesel oil results were much higher in concentration than the highest B-100 results. An analysis of the highest exposure results and field notes revealed a probable association between

  1. Compatibility of refrigerants and lubricants with elastomers

    SciTech Connect

    Hamed, G.R.; Seiple, R.H.

    1992-07-01

    Information contained in this reporters designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. Swell measurements have been made on approximately 50% of the proposed elastomers (94 total)in both the lubricant (7 total) and refrigerant (10 total) materials. Swell behavior in the these fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 hours and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

  2. Liquid lubricants for advanced aircraft engines

    NASA Technical Reports Server (NTRS)

    Loomis, William R.; Fusaro, Robert L.

    1992-01-01

    An overview of liquid lubricants for use in current and projected high performance turbojet engines is discussed. Chemical and physical properties are reviewed with special emphasis placed on the oxidation and thermal stability requirements imposed upon the lubrication system. A brief history is given of the development of turbine engine lubricants which led to the present day synthetic oils with their inherent modification advantages. The status and state of development of some eleven candidate classes of fluids for use in advanced turbine engines are discussed. Published examples of fundamental studies to obtain a better understanding of the chemistry involved in fluid degradation are reviewed. Alternatives to high temperature fluid development are described. The importance of continuing work on improving current high temperature lubricant candidates and encouraging development of new and improved fluid base stocks are discussed.

  3. Fundamental considerations for future solid lubricants

    NASA Technical Reports Server (NTRS)

    Johnson, R. L.; Sliney, H. E.

    1969-01-01

    Properties important to the performance of solid lubricants are discussed. Those properties include shear characteristics, coherence between particles, resistance to cold flow, adherence to the substrate, applicable chemical thermodynamics and kinetics of materials and environments, polymorphism, and rheology. The following generalizations are made: (1) chemical thermodynamics and kinetics are powerful tools for use in determining the useful environments and methods of application for solid film lubricants; (2) the primary requirement for a solid lubricant is low shear strength; (3) the rheology of solid film constituents and formulations is likely to be of vital importance to performance and life; and (4) adherence and mobility of surface films is another primary requirement for long lived solid lubricants.

  4. High-Temperature Solid Lubricant Coating

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Edmonds, Brian J.

    2010-01-01

    NASA PS400 is a solid lubricant coating invented for high-temperature tribological applications. This plasma-sprayed coating is a variant of the previously patented PS304 coating, and has been formulated to provide higher density, smoother surface finish, and better dimensional stability. This innovation is a new composite material that provides a means to reduce friction and wear in mechanical components. PS400 is a blend of a nickel-molybdenum binder, chrome oxide hardener, silver lubricant, and barium fluoride/calcium fluoride eutectic lubricant that can either be sprayed or deposited by other means, such as powder metallurgy. The resulting composite material is then finished by grinding and polishing to produce a smooth, self-lubricating surface.

  5. Dry lubricant films for aluminum forming.

    SciTech Connect

    Wei, J.; Erdemir, A.; Fenske, G. R.

    1999-03-30

    During metal forming process, lubricants are crucial to prevent direct contact, adhesion, transfer and scuffing of workpiece materials and tools. Boric acid films can be firmly adhered to the clean aluminum surfaces by spraying their methanol solutions and provide extremely low friction coefficient (about 0.04). The cohesion strengths of the bonded films vary with the types of aluminum alloys (6061, 6111 and 5754). The sheet metal forming tests indicate that boric acid films and the combined films of boric acid and mineral oil can create larger strains than the commercial liquid and solid lubricants, showing that they possess excellent lubricities for aluminum forming. SEM analyses indicate that boric acid dry films separate the workpiece and die materials, and prevent their direct contact and preserve their surface qualities. Since boric acid is non-toxic and easily removed by water, it can be expected that boric acid films are environmentally friendly, cost effective and very efficient lubricants for sheet aluminum cold forming.

  6. Lubrication and cooling for high speed gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.

    1985-01-01

    The problems and failures occurring with the operation of high speed gears are discussed. The gearing losses associated with high speed gearing such as tooth mesh friction, bearing friction, churning, and windage are discussed with various ways shown to help reduce these losses and thereby improve efficiency. Several different methods of oil jet lubrication for high speed gearing are given such as into mesh, out of mesh, and radial jet lubrication. The experiments and analytical results for the various methods of oil jet lubrication are shown with the strengths and weaknesses of each method discussed. The analytical and experimental results of gear lubrication and cooling at various test conditions are presented. These results show the very definite need of improved methods of gear cooling at high speed and high load conditions.

  7. Potential of vegetable oils for lubricants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetable oils offer significant advantages in terms of resource renewability, biodegradability, and comparable performance properties to petroleum-based products. The petroleum-based lubricants render unfavorable impact on the environment. With the growing environmental concerns, seed oils are find...

  8. Overview of liquid lubricants for advanced aircraft

    NASA Technical Reports Server (NTRS)

    Loomis, W. R.

    1982-01-01

    An overall status report on liquid lubricants for use in high-performance turbojet engines is presented. Emphasis is placed on the oxidation and thermal stability requirements imposed upon the lubrication system. A brief history is iven of the development of turbine engine lubricants which led to synthetic oils with their inherent modification advantages. The status and state of development of some nine candidate classes of fluids for use in advanced turbine engines are discussed. Published examples of fundamental studies to obtain a better understanding of the chemistry involved in fluid degradation are reviewed. Also, alternatives to high temperature fluid development are described. The importance of of continuing work on improving high temperature lubricant candidates and encouraging development of fluid base stocks is discussed.

  9. Mixed thermal convection: fundamental issues and analysis of the planar case.

    PubMed

    Padet, Jacques; Cotta, Renato M; Mladin, Emilia C; Padet, Colette

    2015-09-01

    This paper aims to renew interest on mixed thermal convection research and to emphasize three issues that arise from the present analysis: (i) a clear definition of the reference temperature in the Boussinesq approximation; (ii) a practical delimitation of the three convective modes, which are the forced convection (FC), mixed convection (MC) and natural (or free) convection (NC); (iii) and, finally, a uniform description of the set FC/MC/NC in the similarity framework. The planar case, for which analytical solutions are available, allows a detailed illustration of the answers here advanced to the above issues.

  10. The characteristic analysis of a hybrid multifluid turbulent-mix model

    SciTech Connect

    Cheng, B.; Cranfill, C.W.

    1998-07-13

    A thorough analysis of the characteristics of a multifluid turbulent mix model in the case of one-dimensional two phase flows is presented under various physical circumstances. It has been found that the new hybrid multifluid turbulent mix model has all real characteristics if either real or turbulent viscosity is present. When real viscosity vanishes, the model still has all real characteristics for zero relative motion between fluids. For nonzero relative motions between fluids, the model will have all real characteristics if the disordered motions and turbulent viscosity together are generated with the nonzero relative motions simultaneously. The implications of the results are further discussed.

  11. New Lubricants Protect Machines and the Environment

    NASA Technical Reports Server (NTRS)

    2007-01-01

    In 1994, NASA and Lockheed Martin Space Operations commissioned Sun Coast Chemicals of Daytona Inc to develop a new type of lubricant that would be safe for the environment and help "grease the wheels" of the shuttle-bearing launcher platform. Founded in 1989, Sun Coast Chemicals is known amongst the racing circuit for effective lubricants that help overcome engine and transmission problems related to heat and wear damage. In a matter of weeks, Sun Coast Chemical produced the biodegradable, high-performance X-1R Crawler Track Lube. In 1996, Sun Coast Chemical determined there was a market for this new development, and introduced three derivative products, Train Track Lubricant, Penetrating Spray Lubricant, and Biodegradable Hydraulic Fluid, and then quickly followed with a gun lubricant/cleaner and a fishing rod and reel lubricant. Just recently, Sun Coast introduced the X-1R Corporation, which folds the high-performance, environmentally safe benefits into a full line of standard automotive and specially formulated racing products. The entire X-1R automotive product line has stood up to rigorous testing by groups such as the American Society of Mechanical Engineers, the Swedish National Testing and Research Institute, the Department of Mechanical Engineering at Oakland University (Rochester, Michigan), and Morgan-McClure Motorsports (Abingdon, Virginia). The X-1R Corporation also markets "handy packs" for simple jobs around the house, consisting of a multi-purpose, multi-use lubricant and grease. In 2003, The X-1R Corporation teamed up with Philadelphia-based Penn Tackle Manufacturing Co., a leading manufacturer of fishing tackle since 1932, to jointly develop and market a line of advanced lubrication products for saltwater and freshwater anglers

  12. Advanced lubrication systems and materials. Final report

    SciTech Connect

    Hsu, S.

    1998-05-07

    This report described the work conducted at the National Institute of Standards and Technology under an interagency agreement signed in September 1992 between DOE and NIST for 5 years. The interagency agreement envisions continual funding from DOE to support the development of fuel efficient, low emission engine technologies in terms of lubrication, friction, and wear control encountered in the development of advanced transportation technologies. However, in 1994, the DOE office of transportation technologies was reorganized and the tribology program was dissolved. The work at NIST therefore continued at a low level without further funding from DOE. The work continued to support transportation technologies in the development of fuel efficient, low emission engine development. Under this program, significant progress has been made in advancing the state of the art of lubrication technology for advanced engine research and development. Some of the highlights are: (1) developed an advanced high temperature liquid lubricant capable of sustaining high temperatures in a prototype heat engine; (2) developed a novel liquid lubricant which potentially could lower the emission of heavy duty diesel engines; (3) developed lubricant chemistries for ceramics used in the heat engines; (4) developed application maps for ceramic lubricant chemistry combinations for design purpose; and (5) developed novel test methods to screen lubricant chemistries for automotive air-conditioning compressors lubricated by R-134a (Freon substitute). Most of these findings have been reported to the DOE program office through Argonne National Laboratory who manages the overall program. A list of those reports and a copy of the report submitted to the Argonne National Laboratory is attached in Appendix A. Additional reports have also been submitted separately to DOE program managers. These are attached in Appendix B.

  13. Polymer Lubricants For Use In Vacuum

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1989-01-01

    Report describes tests of lubricating properties of 10 polymer-based materials - in particular, polyimides - in vacuum. Commercially available materials, in forms of solid bodies and films on metals, were tested on pin-on-disk apparatus in vacuum. Best low-wear, low-friction material was 80 PMDA/20 BTDA solid-body polyimide. Friction and wear properties of most polyimides so good in vacuum that solid-lubricant additives not necessary.

  14. Anti-friction additives for lubricating oils

    SciTech Connect

    Karol, T.J.; Magaha, H.S.; Schlicht, R.C.

    1987-03-03

    A lubricating oil composition is described comprising (i) a major portion of lubricant oil; and (ii) from about 0.05 to about 10.0 wt.% of, as an additive, a product prepared by reacting a natural oil selected from the group consisting of coconut, babassu, palm, palm kernel, olive, castor, peanut, beef tallow and lard, with a (C/sub 2/-C/sub 10/) hydroxy acid and a polyamine.

  15. Materials as additives for advanced lubrication

    DOEpatents

    Pol, Vilas G.; Thackeray, Michael M.; Mistry, Kuldeep; Erdemir, Ali

    2016-09-13

    This invention relates to carbon-based materials as anti-friction and anti-wear additives for advanced lubrication purposes. The materials comprise carbon nanotubes suspended in a liquid hydrocarbon carrier. Optionally, the compositions further comprise a surfactant (e.g., to aid in dispersion of the carbon particles). Specifically, the novel lubricants have the ability to significantly lower friction and wear, which translates into improved fuel economies and longer durability of mechanical devices and engines.

  16. Tribology experiment. [journal bearings and liquid lubricants

    NASA Technical Reports Server (NTRS)

    Wall, W. A.

    1981-01-01

    A two-dimensional concept for Spacelab rack 7 was developed to study the interaction of liquid lubricants and surfaces under static and dynamic conditions in a low-gravity environment fluid wetting and spreading experiments of a journal bearing experiments, and means to accurately measure and record the low-gravity environment during experimentation are planned. The wetting and spreading process of selected commercial lubricants on representative surface are to the observes in a near-zero gravity environment.

  17. A comparison of the heat transfer and pressure drop performance of R-134a-lubricant mixtures in different diameter smooth tubes and micro-fin tubes

    SciTech Connect

    Eckels, S.J.; Doerr, T.M.; Pate, M.B.

    1998-10-01

    The average heat transfer coefficients and pressure drops during evaporation and condensation are reported for mixtures of R-134a and an ester lubricant in tubes of 12.7 mm (1/2 in.) outer diameter. The objective of this paper is to evaluate the performance of the R-134a-lubricant mixtures in these tubes and determine the performance benefits of the micro-fin tube. The performance benefits of the tubes with 12.7 mm (1/2 in.) outer diameter are compared to those of smaller tubes with 9.52 mm (3/8 in.) outer diameter. The lubricant used was a 169 SUS penta erythritol ester mixed-acid lubricant. The lubricant concentration was varied from 0--5.1% in the mixture. The average heat transfer coefficients in the 12.7 mm (1/2 in.) micro-fin tube were 50--150% higher than those for the 12.7 mm (1/2 in.) smooth tube, while pressure drops in the micro-fin tube were 5% to 50% higher than in the smooth tube. The addition of lubricant degraded the average heat transfer coefficients in all cases except during evaporation at low lubricant concentrations. Pressure drops were always increased with the addition of lubricant. The experimental results also indicate that tube diameter has some effect on the performance benefits of the micro-fin tube over that of the smooth tube.

  18. Tribological characteristics of polyethylene glycol (PEG) as a lubricant for wear resistance of ultra-high-molecular-weight polyethylene (UHMWPE ) in artificial knee join.

    PubMed

    Kobayashi, Masanori; Koide, Takayuki; Hyon, Suong-Hyu

    2014-10-01

    For the longevity of total knee joint prostheses, we have developed an artificial lubricant using polyethylene glycol (PEG) for the prevention of wear of ultra-high-molecular-weight polyethylene (UHMWPE). In the present study, the lubricative function of this PEG lubricant was evaluated by a wear test using Co-Cr alloy and UHMWPE counter surface samples. As a result, human synovial fluid including the PEG lubricant showed good result regarding the wear volume and a worn surface of UHMWPE. Considering its lubrication mechanism, it is suspected that interaction between the PEG molecules and the proteins in synovial fluid was involved. Since PE molecules are also organic compounds having a hydroxyl group at one or both ends, the albumin and PEG molecule complex would have bound more strongly to the metal oxide surface and UHMWPE surfaces might enhance and stabilize the lubricating film between the contact surfaces under the boundary lubrication. This study suggests that PEG lubricant as an intra-articular viscous supplement has the potential to prevent wear of UHMWPE by mixing with synovial fluid and to contribute to the longevity of knee joint prostheses.

  19. Foaming characteristics of refigerant/lubricant mixtures

    SciTech Connect

    Goswami, D.Y.; Shah, D.O.; Jotshi, C.K.; Bhagwat, S.; Leung, M.; Gregory, A.

    1997-04-01

    The air-conditioning and refrigeration industry has moved to HFC refrigerants which have zero ozone depletion and low global warming potential due to regulations on CFC and HCFC refrigerants and concerns for the environment. The change in refrigerants has prompted the switch from mineral oil and alkylbenzene lubricants to polyolester-based lubricants. This change has also brought about a desire for lubricant, refrigerant and compressor manufacturers to understand the foaming properties of alternative refrigerant/ lubricant mixtures, as well as the mechanisms which affect these properties. The objectives of this investigation are to experimentally determine the foaming absorption and desorption rates of HFC and blended refrigerants in polyolester lubricant and to define the characteristics of the foam formed when the refrigerant leaves the refrigerant/ lubricant mixture after being exposed to a pressure drop. The refrigerants being examined include baseline refrigerants: CFC-12 (R-12) and HCFC-22 (R-22); alternative refrigerants: HFC-32 (R-32), R-125, R-134a, and R-143a; and blended refrigerants: R-404A, R-407C, and R-410A. The baseline refrigerants are tested with ISO 32 (Witco 3GS) and ISO 68 (4GS) mineral oils while the alternative and blended refrigerants are tested with two ISO 68 polyolesters (Witco SL68 and ICI RL68H).

  20. Real Longitudinal Data Analysis for Real People: Building a Good Enough Mixed Model

    PubMed Central

    Cheng, Jing; Edwards, Lloyd J.; Maldonado-Molina, Mildred M.; Komro, Kelli A.; Muller, Keith E.

    2009-01-01

    Summary Mixed effect models have become very popular, especially for the analysis of longitudinal data. One challenge is how to build a good enough mixed effects model. In this paper, we suggest a systematic strategy for addressing this challenge and introduce easily implemented practical advice to build mixed effect models. A general discussion of scientific strategies motivates the recommended five step procedure for model fitting. The need to model both the mean structure (the fixed effects) and the covariance structure (the random effects and residual error) creates the fundamental flexibility and complexity. Some very practical recommendations help conquer the complexity. Centering, scaling, and full-rank coding all predictor variables radically improves the chances of convergence, computing speed, and numerical accuracy. Applying computational and assumption diagnostics from univariate linear models to mixed model data greatly helps detect and solve related computational problems. Applying computational and assumption diagnostics from univariate linear models to mixed model data can radically improve the chances of convergence, computing speed, and numerical accuracy. The approach helps fit more general covariance models, a crucial step in selecting a credible covariance model needed for defensible inference. A detailed demonstration of the recommended strategy is based on data from a published study of a randomized trial of a multicomponent intervention to prevent young adolescents' alcohol use. The discussion highlights a need for additional covariance and inference tools for mixed models. The discussion also highlights the need for improving how scientists and statisticians teach and review the process of finding a good enough mixed model. PMID:20013937

  1. Computer analysis of a high-speed film of the plane turbulent mixing layer

    NASA Astrophysics Data System (ADS)

    Hernan, M. A.; Jimenez, J.

    1982-06-01

    To evaluate the usefulness of digital image analysis in extracting quantitative information from flow pictures we have studied a 16 mm cine film of a turbulent mixing layer. A sequence of 373 frames is digitized and analyzed to isolate and measure the concentration eddies that constitute the large structure and to follow their individual evolution in time. As a result, statistics are given on the life history of the eddies, the structure of the amalgamation process and the amount of entrainment, as measured by area change, due to amalgamation as compared to the total. It is found that most of the entrainment occurs during the normal life of eddies and not during pairing. Mixing intermittency is computed from the observed shape of the eddies and seen to compare well with previous measurements. The significance of these results in modelling the mixing layer is discussed briefly and some comments are given on the general usefulness of the techniques presented.

  2. Transient modeling/analysis of hyperbolic heat conduction problems employing mixed implicit-explicit alpha method

    NASA Technical Reports Server (NTRS)

    Tamma, Kumar K.; D'Costa, Joseph F.

    1991-01-01

    This paper describes the evaluation of mixed implicit-explicit finite element formulations for hyperbolic heat conduction problems involving non-Fourier effects. In particular, mixed implicit-explicit formulations employing the alpha method proposed by Hughes et al. (1987, 1990) are described for the numerical simulation of hyperbolic heat conduction models, which involves time-dependent relaxation effects. Existing analytical approaches for modeling/analysis of such models involve complex mathematical formulations for obtaining closed-form solutions, while in certain numerical formulations the difficulties include severe oscillatory solution behavior (which often disguises the true response) in the vicinity of the thermal disturbances, which propagate with finite velocities. In view of these factors, the alpha method is evaluated to assess the control of the amount of numerical dissipation for predicting the transient propagating thermal disturbances. Numerical test models are presented, and pertinent conclusions are drawn for the mixed-time integration simulation of hyperbolic heat conduction models involving non-Fourier effects.

  3. The advantages and disadvantages of mixing methods: an analysis of combining traditional and autoethnographic approaches.

    PubMed

    O'Byrne, Patrick

    2007-12-01

    Although mixed- and multiple-method research designs are currently gaining momentum and popularity, it is essential that researchers undertake a critical analysis of the process of mixing "mainstream" research designs with newer methods before commencing. In ethnography, not only are there multiple approaches to data collection, but each approach also spans the competing paradigms, thus making the term mainstream ambiguous because these mainstream techniques are reasonably different from one another. When critically appraising the combination of ethnography and autoethnography, researchers must evaluate paradigmatic philosophies and methods of inquiry for commensurability and delineate the advantages and disadvantages of combining methods as they relate to each paradigm. The author's goal in this article is to demarcate the methodologies of both ethnography and autoethnography and then to identify the (dis)advantages that might arise from undertaking multiple-method and/or mixed-method research that uses these approaches concurrently. PMID:18000077

  4. The advantages and disadvantages of mixing methods: an analysis of combining traditional and autoethnographic approaches.

    PubMed

    O'Byrne, Patrick

    2007-12-01

    Although mixed- and multiple-method research designs are currently gaining momentum and popularity, it is essential that researchers undertake a critical analysis of the process of mixing "mainstream" research designs with newer methods before commencing. In ethnography, not only are there multiple approaches to data collection, but each approach also spans the competing paradigms, thus making the term mainstream ambiguous because these mainstream techniques are reasonably different from one another. When critically appraising the combination of ethnography and autoethnography, researchers must evaluate paradigmatic philosophies and methods of inquiry for commensurability and delineate the advantages and disadvantages of combining methods as they relate to each paradigm. The author's goal in this article is to demarcate the methodologies of both ethnography and autoethnography and then to identify the (dis)advantages that might arise from undertaking multiple-method and/or mixed-method research that uses these approaches concurrently.

  5. Accelerated aging of solid lubricants for the W76-1 TSL : effects of polymer outgassing.

    SciTech Connect

    Dugger, Michael Thomas; Wallace, William O.; Huffman, Elizabeth M.

    2006-09-01

    The behavior of MoS{sub 2} lubricants intended for the W76-1 TSL was evaluated after 17 and 82 thermal cycles, each lasting seven days and including a low temperature of -35 C and a high temperature of 93 C, in a sealed container containing organic materials. The MoS{sub 2} was applied by tumbling with MoS{sub 2} powder and steel pins (harperized), or by spraying with a resin binder (AS Mix). Surface composition measurements indicated an uptake of carbon and silicon on the lubricant surfaces after aging. Oxidation of the MoS{sub 2} on harperized coupons, where enough MoS{sub 2} was present at the surface to result in significant Mo and S concentrations, was found to be minimal for the thermal cycles in an atmosphere of primarily nitrogen. Bare steel surfaces showed a reduction in friction for exposed coupons compared to control coupons stored in nitrogen, at least for the initial cycles of sliding until the adsorbed contaminants were worn away. Lubricated surfaces showed no more than a ten percent increase in steady-state friction coefficient after exposure. Initial coefficient of friction was up to 250 percent higher than steady-state for AS Mix films on H950 coupons after 82 thermal cycles. However, the friction coefficient exhibited by lubricated coupons was never greater than 0.25, and more often less than 0.15, even after the accelerated aging exposures.

  6. Method of analysis for compressible flow through mixed-flow centrifugal impellers of arbitrary design

    NASA Technical Reports Server (NTRS)

    Hamrick, Joseph T; Ginsburg, Ambrose; Osborn, Walter M

    1952-01-01

    A method is presented for analysis of the compressible flow between the hub and the shroud of mixed-flow impellers of arbitrary design. Axial symmetry was assumed, but the forces in the meridional (hub to shroud) plane, which are derived from tangential pressure gradients, were taken into account. The method was applied to an experimental mixed-flow impeller. The analysis of the flow in the meridional plane of the impeller showed that the rotational forces, the blade curvature, and the hub-shroud profile can introduce severe velocity gradients along the hub and the shroud surfaces. Choked flow at the impeller inlet as determined by the analysis was verified by experimental results.

  7. Krytox Lubrication Tape Study. [fluorinated lubricating oil for video tape recorders

    NASA Technical Reports Server (NTRS)

    Lee, F.

    1978-01-01

    The use of Krytox, a fluorinated oil, as a tape surface lubricant was studied for a wideband video tape recorder. In spite of the 5 to 1 head wear reduction credited to the surface lubricant, the resultant head life fell short of the 1500 hour goal.

  8. 41 CFR 101-26.602-1 - Procurement of lubricating oils, greases, and gear lubricants.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-26.602-1 Procurement of lubricating oils, greases, and gear lubricants. (a) The Defense Fuel Supply... submit requests to: Commander, Defense Fuel Supply Center, Attn: DFSC:PG, Cameron Station, Alexandria, VA 22314, on or before the requirement due dates specified in § 101-26.602-1(a). Submission of...

  9. Reduced Need of Lubricity Additives in Soybean Oil Blends Under Boundary Lubrication Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Converging prices of vegetable oils and petroleum, along with increased focus on renewable resources, gave more momentum to vegetable oil lubricants. Boundary lubrication properties of four Extreme Pressure (EP) additive blends in conventional Soy Bean Oil (SBO) and Paraffinic Mineral Oil (PMO) of ...

  10. Compatibility of lubricant additives with HFC refrigerants and synthetic lubricants. Final report, Part 1

    SciTech Connect

    Cavestri, R.C.

    1997-07-01

    Part one of this research provides manufacturers of components of air-conditioning and refrigeration equipment with a useful list of lubricant additives, sources, functional properties and chemical species. The list in part one is comprised of domestic lubricant additive suppliers and the results of a literature search that was specifically targeted for additives reported to be useful in polyolester chemistry.

  11. Frequency, Patterns and Preferences of Lubricant Use During Anal Intercourse Within Male Sexual Partnerships in Lima, Peru: Implications for a Rectal Microbicide HIV Prevention Intervention

    PubMed Central

    Clark, J; Salvatierra, Hector Javier; Segura, Eddy Roberto; Salazar, Ximena; Konda, Kelika; Galea, Jerome; Klausner, Jeffrey D; Coates, Thomas; Caceres, Carlos Fernando

    2012-01-01

    Understanding current practices of lubricant use during anal intercourse can help to assess the contexts for the introduction of topical rectal microbicides as an HIV prevention tool for men who have sex with men (MSM). We used quantitative and qualitative methods to assess: current patterns of lubricant use; preferred characteristics of commercial lubricant formulations; and social and behavioral contexts of lubricant use within male sexual partnerships in Lima, Peru. Between 2007 and 2008, we conducted a quantitative behavioral survey with 547 MSM followed by qualitative individual and group interviews with 36 MSM from Lima, Peru. Approximately half of all participants in the quantitative survey (50.3%) reported using commercial lubricant during intercourse occasionally or consistently during the preceding two months, with lack of availability at the time of intercourse the most commonly reported reason for non-use. No clear preferences regarding the color, smell, taste, or viscosity of commercial lubricants were identified, and all participants who reported using a commercial lubricant used the same product (“Love-Lub”). In the qualitative analysis, participants characterized lubricant use as a sexual practice consistently controlled by the receptive partner, who typically obtained and applied lubricant independently, with or without the consent of the insertive partner. Quantitative findings supported this differential pattern of lubricant use, with men who reported sexual identities or roles consistent with receptive anal intercourse, including unprotected receptive intercourse, more likely to report lubricant use than MSM who claimed an exclusively insertive sexual role. Given the social, behavioral, and biological factors contributing to increased vulnerability for HIV and STI acquisition by the receptive partner in anal intercourse, delivery of a topical rectal microbicide as a lubricant formulation could provide an important HIV prevention resource for

  12. Effect of bearing geometry and structure support on transient elastohydrodynamic lubrication of metal-on-metal hip implants.

    PubMed

    Liu, Feng; Jin, Zhongming; Roberts, Paul; Grigoris, Peter

    2007-01-01

    An effective lubrication can significantly reduce wear of metal-on-metal artificial hip joints. The improvement of the lubrication can be achieved through the optimisation of the bearing geometry in terms of a small clearance and/or the structural support such as a polyethylene backing underneath a metallic bearing in a sandwich acetabular cup form. The separate effects of these two factors on fluid film lubrication of 28 mm diameter metal-on-metal total hip joints under walking conditions were numerically investigated in this paper. The results show that a larger lubricant film due to the polyethylene backing can be significantly enhanced by the transient squeeze-film action, particularly during the stance phase, and a similar lubricant film can be developed for both the monolithic cup relying on the smaller clearance and the sandwich cup benefiting from the polyethylene backing. Both cup systems can function in a wide range of lubrication regimes, covering both mixed and fluid film, under the current design and manufacture conditions.

  13. Surface roughness effects with solid lubricants dispersed in mineral oils

    NASA Technical Reports Server (NTRS)

    Cusano, C.; Goglia, P. R.; Sliney, H. E.

    1983-01-01

    The lubricating effectiveness of solid-lubricant dispersions are investigated in both point and line contacts using surfaces with both random and directional roughness characteristics. Friction and wear data obtained at relatively low speeds and at room temperature, indicate that the existence of solid lubricants such as graphite, MoS2, and PTFE in a plain mineral oil generally will not improve the effectiveness of the oil as a lubricant for such surfaces. Under boundary lubrication conditions, the friction force, as a function of time, initially depends upon the directional roughness properties of the contacting surfaces irrespective of whether the base oil or dispersions are used as lubricants.

  14. Lubrication study for Single Point Incremental Forming of Copper

    NASA Astrophysics Data System (ADS)

    Jawale, Kishore; Ferreira Duarte, José; Reis, Ana; Silva, M. B.

    2016-08-01

    In conventional machining and sheet metal forming processes, in general, lubrication assists to increase the quality of the final product. Similarly it is observed that there is a positive effect of the use of lubrication in Single point incremental forming, namely in the surface roughness. This study is focused on the investigation of the most appropriate lubricant for incremental forming of copper sheet. The study involves the selection of the best lubricant from a range of several lubricants that provides the best surface finishing. The influence of the lubrication on other parameters such as the maximum forming angle, the fracture strains and the deformed profile are also studied for Copper.

  15. Influence of liquid lubricant properties on their performance.

    NASA Technical Reports Server (NTRS)

    Wedeven, V.

    1972-01-01

    The influence of lubricant properties on performance is considered in connection with various mechanisms of lubrication. The effects of temperature and pressure on viscosity, which is important in hydrodynamic and elastohydrodynamic lubrication, is presented using a correlation postulated by Roelands. Under elastohydrodynamic conditions it is important to distinguish between the influence of lubricant properties within the inlet region and the Hertz region since each performs different functions. The role of lubricant transport properties such as surface tension is considered in connection with lubricant starvation.

  16. Towards Solving the Mixing Problem in the Decomposition of Geophysical Time Series by Independent Component Analysis

    NASA Technical Reports Server (NTRS)

    Aires, Filipe; Rossow, William B.; Chedin, Alain; Hansen, James E. (Technical Monitor)

    2000-01-01

    The use of the Principal Component Analysis technique for the analysis of geophysical time series has been questioned in particular for its tendency to extract components that mix several physical phenomena even when the signal is just their linear sum. We demonstrate with a data simulation experiment that the Independent Component Analysis, a recently developed technique, is able to solve this problem. This new technique requires the statistical independence of components, a stronger constraint, that uses higher-order statistics, instead of the classical decorrelation a weaker constraint, that uses only second-order statistics. Furthermore, ICA does not require additional a priori information such as the localization constraint used in Rotational Techniques.

  17. Development of mixed time partition procedures for thermal analysis of structures

    NASA Technical Reports Server (NTRS)

    Liu, W. K.

    1982-01-01

    The computational methods used to predict and optimize the thermal-structural behavior of aerospace vehicle structures are reviewed. In general, two classes of algorithms, implicit and explicit, are used in transient thermal analysis of structures. Each of these two methods has its own merits. Due to the different time scales of the mechanical and thermal responses, the selection of a time integration method can be a difficult yet critical factor in the efficient solution of such problems. Therefore mixed time integration methods for transient thermal analysis of structures are being developed. This proposed methodology would be readily adaptable to existing computer programs for structural thermal analysis.

  18. Mechanisms of lubrication and wear of a bonded solid lubricant film

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1980-01-01

    To obtain a better understanding of how bonded solid lubricant films lubricate and wear (in general), the tribological properties of polyimide-bonded graphite fluoride films were studied (in specific). A pin-on-disk type of testing apparatus was used; but in addition to sliding a hemispherically tipped rider, a rider with a 0.95 mm diameter flat area was slid against the film. This was done so that a lower, less variable contact stress could be achieved. Two stages of lubrication occurred. In the first, the film supported the load. The lubricating mechanism consisted of the shear of a thin surface layer (of the film) between the rider and the bulk of the film. The second occurred after the bonded film had worn to the substrate, and consisted of the shear of very thin lubricant films between the rider and flat plateaus generated on the metallic substrate asperities. The film wear mechanism was strongly dependent on contact stress.

  19. Effect of wear of bearing surfaces on elastohydrodynamic lubrication of metal-on-metal hip implants.

    PubMed

    Liu, F; Jin, Z M; Hirt, F; Rieker, C; Roberts, P; Grigoris, P

    2005-09-01

    The effect of geometry change of the bearing surfaces owing to wear on the elastohydrodynamic lubrication (EHL) of metal-on-metal (MOM) hip bearings has been investigated theoretically in the present study. A particular MOM Metasul bearing (Zimmer GmbH) was considered, and was tested in a hip simulator using diluted bovine serum. The geometry of the worn bearing surface was measured using a coordinate measuring machine (CMM) and was modelled theoretically on the assumption of spherical geometries determined from the maximum linear wear depth and the angle of the worn region. Both the CMM measurement and the theoretical calculation were directly incorporated into the elastohydrodynamic lubrication analysis. It was found that the geometry of the original machined bearing surfaces, particularly of the femoral head with its out-of-roundness, could lead to a large reduction in the predicted lubricant film thickness and an increase in pressure. However, these non-spherical deviations can be expected to be smoothed out quickly during the initial running-in period. For a given worn bearing surface, the predicted lubricant film thickness and pressure distribution, based on CMM measurement, were found to be in good overall agreement with those obtained with the theoretical model based on the maximum linear wear depth and the angle of the worn region. The gradual increase in linear wear during the running-in period resulted in an improvement in the conformity and consequently an increase in the predicted lubricant film thickness and a decrease in the pressure. For the Metasul bearing tested in an AMTI hip simulator, a maximum total linear wear depth of approximately 13 microm was measured after 1 million cycles and remained unchanged up to 5 million cycles. This resulted in a threefold increase in the predicted average lubricant film thickness. Consequently, it was possible for the Metasul bearing to achieve a fluid film lubrication regime during this period, and this was

  20. Experimental investigations of elastohydrodynamic lubrication

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1983-01-01

    Various experimental studies of elastohydrodynamic lubrication have been reviewed. The various types of machines used in these investigations, such as the disc, two and four ball, crossed-cylinders, and crossed-axes rolling disc machine, are described. The measurement of the most important parameters, such as film shape, film thickness, pressure, temperature, and traction, is considered. Determination of the film thickness is generally the most important of these effects since it dictates the extent to which the asperities on opposing surfaces can come into contact and thus has a direct bearing on wear and fatigue failure of the contacting surfaces. Several different techniques for measuring film thickness have been described, including electrical resistance, capacitance, X-ray, optical interferometry, laser beam diffraction, strain gage, and spring dynamometer methods. An attempt has been made to describe the basic concepts and limitations of each of these techniques. These various methods have been used by individual researchers, but there is no universally acceptable technique for measuring elastohydrodynamic film thickness. Capacitance methods have provided most of the reliable data for nominal line or rectangular conjunctions, but optical interferometry has proved to be the most effective procedure for elliptical contacts. Optical interferometry has the great advantage that it reveals not only the film thickness, but also details of the film shape over the complete area of the conjunction.

  1. Technoeconomic Analysis of a Lignocellulosic Biomass Indirect Gasification Process to Make Ethanol via Mixed Alcohols Synthesis

    SciTech Connect

    Phillips, S. D.

    2007-01-01

    A technoeconomic analysis of a 2000 tonne/day lignocellulosic biomass conversion process to make mixed alcohols via gasification and catalytic synthesis was completed. The process, modeled using ASPEN Plus process modeling software for mass and energy calculations, included all major process steps to convert biomass into liquid fuels, including gasification, gas cleanup and conditioning, synthesis conversion to mixed alcohols, and product separation. The gas cleanup area features a catalytic fluidized-bed steam reformer to convert tars and hydrocarbons into syngas. Conversions for both the reformer and the synthesis catalysts were based on research targets expected to be achieved by 2012 through ongoing research. The mass and energy calculations were used to estimate capital and operating costs that were used in a discounted cash flow rate of return analysis for the process to calculate a minimum ethanol selling price of $0.267/L ($1.01/gal) ethanol (U.S.$2005).

  2. MTG2: an efficient algorithm for multivariate linear mixed model analysis based on genomic information

    PubMed Central

    Lee, S. H.; van der Werf, J. H. J.

    2016-01-01

    Summary: We have developed an algorithm for genetic analysis of complex traits using genome-wide SNPs in a linear mixed model framework. Compared to current standard REML software based on the mixed model equation, our method is substantially faster. The advantage is largest when there is only a single genetic covariance structure. The method is particularly useful for multivariate analysis, including multi-trait models and random regression models for studying reaction norms. We applied our proposed method to publicly available mice and human data and discuss the advantages and limitations. Availability and implementation: MTG2 is available in https://sites.google.com/site/honglee0707/mtg2. Contact: hong.lee@une.edu.au Supplementary information: Supplementary data are available at Bioinformatics online. PMID:26755623

  3. Capturing complexity: Mixing methods in the analysis of a European tobacco control policy network

    PubMed Central

    Weishaar, Heide; Amos, Amanda; Collin, Jeff

    2015-01-01

    Social network analysis (SNA), a method which can be used to explore networks in various contexts, has received increasing attention. Drawing on the development of European smoke-free policy, this paper explores how a mixed method approach to SNA can be utilised to investigate a complex policy network. Textual data from public documents, consultation submissions and websites were extracted, converted and analysed using plagiarism detection software and quantitative network analysis, and qualitative data from public documents and 35 interviews were thematically analysed. While the quantitative analysis enabled understanding of the network's structure and components, the qualitative analysis provided in-depth information about specific actors' positions, relationships and interactions. The paper establishes that SNA is suited to empirically testing and analysing networks in EU policymaking. It contributes to methodological debates about the antagonism between qualitative and quantitative approaches and demonstrates that qualitative and quantitative network analysis can offer a powerful tool for policy analysis. PMID:26185482

  4. The Multilevel Mixed Intact Group Analysis: A Mixed Method to Seek, Detect, Describe, and Explain Differences Among Intact Groups

    ERIC Educational Resources Information Center

    Schoonenboom, Judith

    2016-01-01

    Educational innovations often involve intact subgroups, such as school classes or university departments. In small-scale educational evaluation research, typically involving 1 to 20 subgroups, differences among these subgroups are often neglected. This article presents a mixed method from a qualitative perspective, in which differences among…

  5. MIXED DENTITION SPACE ANALYSIS OF A SOUTHERN ITALIAN POPULATION: NEW REGRESSION EQUATIONS FOR UNERUPTED TEETH.

    PubMed

    Cirulli, N; Ballini, A; Cantore, S; Farronato, D; Inchingolo, F; Dipalma, G; Gatto, M R; Alessandri Bonetti, G

    2015-01-01

    Mixed dentition analysis forms a critical aspect of early orthodontic treatment. In fact an accurate space analysis is one of the important criteria in determining whether the treatment plan may involve serial extraction, guidance of eruption, space maintenance, space regaining or just periodic observation of the patients. The aim of the present study was to calculate linear regression equations in mixed dentition space analysis, measuring 230 dental casts mesiodistal tooth widths, obtained from southern Italian patients (118 females, 112 males, mean age 15±3 years). Student’s t-test or Wilcoxon test for independent and paired samples were used to determine right/left side and male/female differences. On the basis of the sum of the mesiodistal diameters of the 4 mandibular incisors as predictors for the sum of the widths of the canines and premolars in the mandibular mixed dentition, a new linear regression equation was found: y = 0.613x+7.294 (r= 0.701) for both genders in a southern Italian population. To better estimate the size of leeway space, a new regression equation was found to calculate the mesiodistal size of the second premolar using the sum of the four mandibular incisors, canine and first premolar as a predictor. The equation is y = 0.241x+1.224 (r= 0.732). In conclusion, new regression equations were derived for a southern Italian population.

  6. MIXED DENTITION SPACE ANALYSIS OF A SOUTHERN ITALIAN POPULATION: NEW REGRESSION EQUATIONS FOR UNERUPTED TEETH.

    PubMed

    Cirulli, N; Ballini, A; Cantore, S; Farronato, D; Inchingolo, F; Dipalma, G; Gatto, M R; Alessandri Bonetti, G

    2015-01-01

    Mixed dentition analysis forms a critical aspect of early orthodontic treatment. In fact an accurate space analysis is one of the important criteria in determining whether the treatment plan may involve serial extraction, guidance of eruption, space maintenance, space regaining or just periodic observation of the patients. The aim of the present study was to calculate linear regression equations in mixed dentition space analysis, measuring 230 dental casts mesiodistal tooth widths, obtained from southern Italian patients (118 females, 112 males, mean age 15±3 years). Student’s t-test or Wilcoxon test for independent and paired samples were used to determine right/left side and male/female differences. On the basis of the sum of the mesiodistal diameters of the 4 mandibular incisors as predictors for the sum of the widths of the canines and premolars in the mandibular mixed dentition, a new linear regression equation was found: y = 0.613x+7.294 (r= 0.701) for both genders in a southern Italian population. To better estimate the size of leeway space, a new regression equation was found to calculate the mesiodistal size of the second premolar using the sum of the four mandibular incisors, canine and first premolar as a predictor. The equation is y = 0.241x+1.224 (r= 0.732). In conclusion, new regression equations were derived for a southern Italian population. PMID:26122245

  7. Fully-coupled analysis of jet mixing problems. Three-dimensional PNS model, SCIP3D

    NASA Technical Reports Server (NTRS)

    Wolf, D. E.; Sinha, N.; Dash, S. M.

    1988-01-01

    Numerical procedures formulated for the analysis of 3D jet mixing problems, as incorporated in the computer model, SCIP3D, are described. The overall methodology closely parallels that developed in the earlier 2D axisymmetric jet mixing model, SCIPVIS. SCIP3D integrates the 3D parabolized Navier-Stokes (PNS) jet mixing equations, cast in mapped cartesian or cylindrical coordinates, employing the explicit MacCormack Algorithm. A pressure split variant of this algorithm is employed in subsonic regions with a sublayer approximation utilized for treating the streamwise pressure component. SCIP3D contains both the ks and kW turbulence models, and employs a two component mixture approach to treat jet exhausts of arbitrary composition. Specialized grid procedures are used to adjust the grid growth in accordance with the growth of the jet, including a hybrid cartesian/cylindrical grid procedure for rectangular jets which moves the hybrid coordinate origin towards the flow origin as the jet transitions from a rectangular to circular shape. Numerous calculations are presented for rectangular mixing problems, as well as for a variety of basic unit problems exhibiting overall capabilities of SCIP3D.

  8. Two-colour chewing gum mixing ability: digitalisation and spatial heterogeneity analysis.

    PubMed

    Weijenberg, R A F; Scherder, E J A; Visscher, C M; Gorissen, T; Yoshida, E; Lobbezoo, F

    2013-10-01

    Many techniques are available to assess masticatory performance, but not all are appropriate for every population. A proxy suitable for elderly persons suffering from dementia was lacking, and a two-colour chewing gum mixing ability test was investigated for this purpose. A fully automated digital analysis algorithm was applied to a mixing ability test using two-coloured gum samples in a stepwise increased number of chewing cycles protocol (Experiment 1: n = 14; seven men, 19-63 years), a test-retest assessment (Experiment 2: n = 10; four men, 20-49 years) and compared to an established wax cubes mixing ability test (Experiment 3: n = 13; 0 men, 21-31 years). Data were analysed with repeated measures anova (Experiment 1), the calculation of the intraclass correlation coefficient (ICC; Experiment 2) and Spearman's rho correlation coefficient (Experiment 3). The method was sensitive to increasing numbers of chewing cycles (F5,65 = 57·270, P = 0·000) and reliable in the test-retest (ICC value of 0·714, P = 0·004). There was no significant correlation between the two-coloured gum test and the wax cubes test. The two-coloured gum mixing ability test was able to adequately assess masticatory function and is recommended for use in a population of elderly persons with dementia.

  9. Two-colour chewing gum mixing ability: digitalisation and spatial heterogeneity analysis.

    PubMed

    Weijenberg, R A F; Scherder, E J A; Visscher, C M; Gorissen, T; Yoshida, E; Lobbezoo, F

    2013-10-01

    Many techniques are available to assess masticatory performance, but not all are appropriate for every population. A proxy suitable for elderly persons suffering from dementia was lacking, and a two-colour chewing gum mixing ability test was investigated for this purpose. A fully automated digital analysis algorithm was applied to a mixing ability test using two-coloured gum samples in a stepwise increased number of chewing cycles protocol (Experiment 1: n = 14; seven men, 19-63 years), a test-retest assessment (Experiment 2: n = 10; four men, 20-49 years) and compared to an established wax cubes mixing ability test (Experiment 3: n = 13; 0 men, 21-31 years). Data were analysed with repeated measures anova (Experiment 1), the calculation of the intraclass correlation coefficient (ICC; Experiment 2) and Spearman's rho correlation coefficient (Experiment 3). The method was sensitive to increasing numbers of chewing cycles (F5,65 = 57·270, P = 0·000) and reliable in the test-retest (ICC value of 0·714, P = 0·004). There was no significant correlation between the two-coloured gum test and the wax cubes test. The two-coloured gum mixing ability test was able to adequately assess masticatory function and is recommended for use in a population of elderly persons with dementia. PMID:23927753

  10. Enhancement of Perfluoropolyether Boundary Lubrication Performance

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Ajayi, O. O.; Wedeven, L. D.

    1996-01-01

    A ball bearing simulator operating under starved conditions was used to perform screening tests to evaluate the boundary lubrication performance of a branched perfluoropolyether (PFPE), K-143 AB. Several approaches to enhance boundary lubrication were studied. These included: (1) soluble boundary additives, (2) bearing surface modifications, (3) 'run-in' surface films, and (4) ceramic bearing components. In addition, results were compared with two non-perfluorinated liquid lubricant formulations. Based on these tests, the following tentative conclusions can be made: (1) Substantial improvements in boundary lubrication performance were observed with a beta-diketone boundary additive and a tricresyl phosphate (TCP) liquid surface pretreatment, (2) the use of rough Si3N4 balls (R(sub a) = 40 micro-inch) also provided increases in test duration, but with concomitant abrasive wear, (3) moderate improvements were seen with two boundary additives (a phosphine and a phosphatriazine) and a neat (100%) fluid (a carboxylic acid terminated PFPE); and small improvements with surface pretreatments with synthetic hydrocarbons, a polytetrafluoroethylene (PTFE) coating, and TiC coated 440 C and smooth Si3N4 balls (R(sub a) = 1 micro-inch), and (4) two non-PFPE lubricant formulations (a polyalphaolefin (PAO) and synthetic hydrocarbon) yielded substantial improvements.

  11. Lubrication regimes in lumbar total disc arthroplasty.

    PubMed

    Shaheen, A; Shepherd, D E T

    2007-08-01

    A number of total disc arthroplasty devices have been developed. Some concern has been expressed that wear may be a potential failure mode for these devices, as has been seen with hip arthroplasty. The aim of this paper was to investigate the lubrication regimes that occur in lumbar total disc arthroplasty devices. The disc arthroplasty was modelled as a ball-and-socket joint. Elastohydrodynamic lubrication theory was used to calculate the minimum film thickness of the fluid between the bearing surfaces. The lubrication regime was then determined for different material combinations, size of implant, and trunk velocity. Disc arthroplasties with a metal-polymer or metal-metal material combination operate with a boundary lubrication regime. A ceramic-ceramic material combination has the potential to operate with fluid-film lubrication. Disc arthroplasties with a metal-polymer or metal-metal material combination are likely to generate wear debris. In future, it is worth considering a ceramic-ceramic material combination as this is likely to reduce wear.

  12. Solid Lubrication Fundamentals and Applications. Chapter 6

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2000-01-01

    This chapter focuses attention on the friction and wear properties of selected solid lubricating films to aid users in choosing the best lubricant, deposition conditions, and operational variables. For simplicity, discussion of the tribological properties of concern is separated into two parts. The first part of the chapter discusses the different solid lubricating films selected for study including commercially developed solid film lubricants: (1) bonded molybdenum disulfide (MoS2), (2) magnetron-sputtered MoS2, (3) ion-plated silver, (4) ion-plated lead, (5) magnetron-sputtered diamondlike carbon (MS DLC), and (6) plasma-assisted, chemical-vapor-deposited diamondlike carbon (PACVD DEC) films. Marked differences in the friction and wear properties of the different films resulted from the different environmental conditions (ultrahigh vacuum, humid air, and dry nitrogen) and the solid film lubricant materials. The second part of the chapter discusses the physical and chemical characteristics, friction behavior, and endurance life of the magnetron-sputtered MoS2 films. The role of interface species and the effects of applied load, film thickness, oxygen pressure, environment, and temperature on the friction and wear properties are considered.

  13. Analysis of mixed cell cultures with quantitative digital holographic phase microscopy

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Wibbeling, Jana; Ketelhut, Steffi

    2014-05-01

    In order to study, for example, the influence of pharmaceuticals or pathogens on different cell types under identical measurement conditions and to analyze interactions between different cellular specimens a minimally-invasive quantitative observation of mixed cell cultures is of particular interest. Quantitative phase microscopy (QPM) provides high resolution detection of optical path length changes that is suitable for stain-free minimally-invasive live cell analysis. Due to low light intensities for object illumination, QPM minimizes the interaction with the sample and is in particular suitable for long term time-lapse investigations, e.g., for the detection of cell morphology alterations due to drugs and toxins. Furthermore, QPM has been demonstrated to be a versatile tool for the quantification of cellular growth, the extraction morphological parameters and cell motility. We studied the feasibility of QPM for the analysis of mixed cell cultures. It was explored if quantitative phase images provide sufficient information to distinguish between different cell types and to extract cell specific parameters. For the experiments quantitative phase imaging with digital holographic microscopy (DHM) was utilized. Mixed cell cultures with different types of human pancreatic tumor cells were observed with quantitative DHM phase contrast up to 35 h. The obtained series of quantitative phase images were evaluated by adapted algorithms for image segmentation. From the segmented images the cellular dry mass and the mean cell thickness were calculated and used in the further analysis as parameters to quantify the reliability the measurement principle. The obtained results demonstrate that it is possible to characterize the growth of cell types with different morphologies in a mixed cell culture separately by consideration of specimen size and cell thickness in the evaluation of quantitative DHM phase images.

  14. Stability analysis of Markovian jumping stochastic Cohen-Grossberg neural networks with mixed time delays.

    PubMed

    Zhang, H; Wang, Y

    2008-02-01

    In this letter, the global asymptotical stability analysis problem is considered for a class of Markovian jumping stochastic Cohen-Grossberg neural networks (CGNNs) with mixed delays including discrete delays and distributed delays. An alternative delay-dependent stability analysis result is established based on the linear matrix inequality (LMI) technique, which can easily be checked by utilizing the numerically efficient Matlab LMI toolbox. Neither system transformation nor free-weight matrix via Newton-Leibniz formula is required. Two numerical examples are included to show the effectiveness of the result.

  15. Friction of self-lubricating surfaces by ion beam techniques. Final technical report

    SciTech Connect

    Bhattacharya, R.S.; Rai, A.K.

    1992-05-01

    UES, Inc. conducted a research and development program designed to establish conditions for ion implantation/mixing of suitable additives into the surfaces of bulk ceramics and metals for obtaining self-lubricating low friction and wear characteristics. The substrates considered were ZrO{sub 2}, Al{sub 2}O{sub 3}, Si{sub 3}N{sub 4}, steel and Ni-base superalloy. The lubricant additives chosen were BaF{sub 2}/CaF{sub 2}Ag, MoS{sub 2}, WS{sub 2}and B{sub 2}O{sub 3}. The initial tasks of the program were to synthesis these lubricant compounds by co-implantation of constituent elements if sufficient beams of desired elements were obtained. The final tasks were to investigate high energy (MeV) ion mixing of deposited coatings as well as to investigate ion beam assisted deposition using low energy ion beams. It was shown that MoS{sub 2} can be synthesized by co-implantation of Mo{sup +} and S{sup +} in ceramic materials with appropriate choice of energies to obtain nearly overlapping depth profiles. The sliding life of DC magnetron sputtered MoS{sub 2} films of thicknesses {approximately}7500{Angstrom} on ceramic materials such as sapphire, Si{sub 3}N{sub 4} and ZrO{sub 3} were improved by ten to thousand fold after 2 Mev Ag{sup +} ion mixing. Ion beam assisted deposition (IBAD) and ion beam mixing were utilized to fabricate self-lubricating coatings of CaF{sub 2}/Ag and BaF/CaF{sub 2}/Ag composites.

  16. Mechanics of a gaseous film barrier to lubricant wetting of elastohydrodynamically lubricated conjunctions

    NASA Technical Reports Server (NTRS)

    Prahl, J. M.; Hamrock, B. J.

    1985-01-01

    Two analytical models, one based on simple hydrodynamic lubrication and the other on soft elastohydrodynamic lubrication, are presented and compared to delineate the dominant physical parameters that govern the mechanics of a gaseous film between a small droplet of lubricant and the outer race of a ball bearing. Both models are based on the balance of gravity forces, air drag forces, and air film lubrication forces and incorporate a drag coefficient C sub D and a lubrication coefficient C sub L to be determined from experiment. The soft elastohydrodynamic lubrication (EHL) model considers the effects of droplet deformation and solid-surface geometry; the simpler hydrodynamic lubrication (HL) model assumes that the droplet remains essentially spherical. The droplet's angular position depended primarily on the ratio of gas inertia to droplet gravity forces and on the gas Reynolds number and weakly on the ratio of droplet gravity forces to surface tension forces (Bond number) and geometric ratios for the soft EHL. An experimental configuration in which an oil droplet is supported by an air film on the rotating outer race of a ball bearing within a pressure-controlled chamber produced measurements of droplet angular position as a function of outer-race velocity droplet size and type, and chamber pressure.

  17. Effects of nanoscale surface texture and lubricant molecular structure on boundary lubrication in liquid.

    PubMed

    Al-Azizi, Ala' A; Eryilmaz, Osman; Erdemir, Ali; Kim, Seong H

    2013-11-01

    Nanoconfinement effects of boundary lubricants can significantly affect the friction behavior of textured solid interfaces. These effects were studied with nanotextured diamond-like carbon (DLC) surfaces using a reciprocating ball-on-flat tribometer in liquid lubricants with different molecular structures: n-hexadecane and n-pentanol for linear molecular structure and poly(α-olefin) and heptamethylnonane for branched molecular structure. It is well-known that liquid lubricants with linear molecular structures can readily form a long-range ordered structure upon nanoconfinement between flat solid surfaces. This long-range ordering, often called solidification, causes high friction in the boundary lubrication regime. When the solid surface deforms elastically due to the contact pressure and this deformation depth is larger than the surface roughness, even rough surfaces can exhibit the nanoconfinement effects. However, the liquid entrapped in the depressed region of the nanotextured surface would not solidify, which effectively reduces the solidified lubricant area in the contact region and decreases friction. When liquid lubricants are branched, the nanoconfinement-induced solidification does not occur because the molecular structure is not suitable for the long-range ordering. Surface texture, therefore, has an insignificant effect on the boundary lubrication of branched molecules.

  18. Effects of nanoscale surface texture and lubricant molecular structure on boundary lubrication in liquid.

    PubMed

    Al-Azizi, Ala' A; Eryilmaz, Osman; Erdemir, Ali; Kim, Seong H

    2013-11-01

    Nanoconfinement effects of boundary lubricants can significantly affect the friction behavior of textured solid interfaces. These effects were studied with nanotextured diamond-like carbon (DLC) surfaces using a reciprocating ball-on-flat tribometer in liquid lubricants with different molecular structures: n-hexadecane and n-pentanol for linear molecular structure and poly(α-olefin) and heptamethylnonane for branched molecular structure. It is well-known that liquid lubricants with linear molecular structures can readily form a long-range ordered structure upon nanoconfinement between flat solid surfaces. This long-range ordering, often called solidification, causes high friction in the boundary lubrication regime. When the solid surface deforms elastically due to the contact pressure and this deformation depth is larger than the surface roughness, even rough surfaces can exhibit the nanoconfinement effects. However, the liquid entrapped in the depressed region of the nanotextured surface would not solidify, which effectively reduces the solidified lubricant area in the contact region and decreases friction. When liquid lubricants are branched, the nanoconfinement-induced solidification does not occur because the molecular structure is not suitable for the long-range ordering. Surface texture, therefore, has an insignificant effect on the boundary lubrication of branched molecules. PMID:24156745

  19. Practical Applications and Uses of Solid Lubricant Films

    NASA Technical Reports Server (NTRS)

    Stupp, B. C.

    1984-01-01

    Practical applications are illustrated with discussions covering the reasons for use of solid lubricants, required performance, lubricant selection, and results obtained for the various examples shown. The applications described cover a broad range of solid lubricants. Included are soft lamellar compounds, organic polymers, soft elemental metals, oxides and compounds for high temperature use. The illustrations selected cover a broad range of lubricant application techniques delineating the reasons for the different processing procedures which include bonded films, plasma spraying, sputtering, ion plating and electrodeposition.

  20. High temperature solid lubricants: When and where to use them

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1973-01-01

    The state of the art of solid lubrication for moderate to extremely high temperature lubrication (to 1600 F) is reviewed. Lubricating characteristics, stability in various environments, and relevant machine design considerations are discussed. Lubricating materials discussed include the layer lattice compounds: MoS2, WS2, graphite and graphite fluoride, the high temperature polyimide polymer, and calcium fluoride based coating and composites. The scope of the information includes results from wear testers, ball bearing, and journal bearings.

  1. High temperature solid lubricants - When and where to use them.

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1973-01-01

    This paper reviews the state of the art of solid lubrication for moderate to extremely high temperature lubrication (to 1600 F). Lubricating characteristics, stability in various environments, and relevant machine design considerations are discussed. Lubricating materials discussed include MoS2, WS2, graphite, graphite fluoride, the high temperature polymide polymer, and calcium fluoride based coatings and composites. The scope of the information includes results from wear testers, ball bearings, and journal bearings.

  2. A computer solution for the dynamic load, lubricant film thickness and surface temperatures in spiral bevel gears

    NASA Technical Reports Server (NTRS)

    Chao, H. C.; Cheng, H. S.

    1987-01-01

    A complete analysis of spiral bevel gear sets is presented. The gear profile is described by the movements of the cutting tools. The contact patterns of the rigid body gears are investigated. The tooth dynamic force is studied by combining the effects of variable teeth meshing stiffness, speed, damping, and bearing stiffness. The lubrication performance is also accomplished by including the effects of the lubricant viscosity, ambient temperature, and gear speed. A set of numerical results is also presented.

  3. Analysis of operating costs a Low-Level Mixed Waste Incineration Facility

    SciTech Connect

    Loghry, S.L.; Salmon, R.; Hermes, W.H.

    1995-12-31

    By definition, mixed wastes contain both chemically hazardous and radioactive components. These components make the treatment and disposal of mixed wastes expensive and highly complex issues because the different regulations which pertain to the two classes of contaminants frequently conflict. One method to dispose of low-level mixed wastes (LLMWs) is by incineration, which volatizes and destroys the organic (and other) hazardous contaminants and also greatly reduces the waste volume. The US Department of Energy currently incinerates liquid LLMW in its Toxic Substances Control Act (TSCA) Incinerator, located at the K-25 Site in Oak Ridge, Tennessee. This incinerator has been fully permitted since 1991 and to date has treated approximately 7 {times} 10{sup 6} kg of liquid LLMW. This paper presents an analysis of the budgeted operating costs by category (e.g., maintenance, plant operations, sampling and analysis, and utilities) for fiscal year 1994 based on actual operating experience (i.e., a ``bottoms-up`` budget). These costs provide benchmarking guidelines which could be used in comparing incinerator operating costs with those of other technologies designed to dispose of liquid LLMW. A discussion of the current upgrade status and future activities are included in this paper. Capital costs are not addressed.

  4. ATOMIC DIFFUSION AND MIXING IN OLD STARS. III. ANALYSIS OF NGC 6397 STARS UNDER NEW CONSTRAINTS

    SciTech Connect

    Nordlander, T.; Korn, A. J.; Richard, O.; Lind, K.

    2012-07-01

    We have previously reported on chemical abundance trends with evolutionary state in the globular cluster NGC 6397 discovered in analyses of spectra taken with FLAMES at the Very Large Telescope. Here, we reinvestigate the FLAMES-UVES sample of 18 stars, ranging from just above the turnoff point to the red giant branch below the bump. Inspired by new calibrations of the infrared flux method, we adopt a set of hotter temperature scales. Chemical abundances are determined for six elements (Li, Mg, Ca, Ti, Cr, and Fe). Signatures of cluster-internal pollution are identified and corrected for in the analysis of Mg. On the modified temperature scales, evolutionary trends in the abundances of Mg and Fe are found to be significant at the 2{sigma} and 3{sigma} levels, respectively. The detailed evolution of abundances for all six elements agrees with theoretical isochrones, calculated with effects of atomic diffusion and a weak to moderately strong efficiency of turbulent mixing. The age of these models is compatible with the external determination from the white dwarf cooling sequence. We find that the abundance analysis cannot be reconciled with the strong turbulent-mixing efficiency inferred elsewhere for halo field stars. A weak mixing efficiency reproduces observations best, indicating a diffusion-corrected primordial lithium abundance of log {epsilon}(Li) = 2.57 {+-} 0.10. At 1.2{sigma}, this value agrees well with Wilkinson Microwave Anisotropy Probe calibrated big bang nucleosynthesis predictions.

  5. Analysis and testing of two-dimensional slot nozzle ejectors with variable area mixing sections

    NASA Technical Reports Server (NTRS)

    Gilbert, G. B.; Hill, P. G.

    1973-01-01

    Finite difference computer techniques have been used to calculate the detailed performance of air to air two-dimensional ejectors with symmetric variable area mixing sections and coaxial coverging primary nozzles. The analysis of the primary nozzle assumed correct expansion of the flow and is suitable for subsonic and slightly supersonic velocity levels. The variation of the mixing section channel walls is assumed to be gradual so that the static pressure can be assumed uniform on planes perpendicular to the axis. A test program was run to provide two-dimensional ejector test data for verification of the computer analysis. A primary converging nozzle with a discharge geometry of 0.125 inch x 8.0 inch was supplied with 600 SCFM of air at about 35 psia and 180 F. This nozzle was combined with two mixing section geometries with throat sizes of 1.25 inch x 8.0 inch and 1.875 inch x 8.0 inch and was tested at a total of 11 operating points.

  6. Compatibility of refrigerants and lubricants with elastomers

    SciTech Connect

    Hamed, G.R.; Seiple, R.H.

    1993-01-01

    The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on availability of additional R-32. Swell behavior in the fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

  7. Sputtering technology in solid film lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1978-01-01

    Potential and present sputtering technology is discussed as it applies to the deposition of solid film lubricants particularly MoS2, WS2, and PTFE. Since the sputtered films are very thin, the selection of the sputtering parameters and substrate condition is very critical as reflected by the lubricating properties. It was shown with sputtered MoS2 films that the lubricating characteristics are directly affected by the selected sputtering parameters (power density, pressure, sputter etching, dc-biasing, etc.) and the substrate temperature, chemistry, topography and the environmental conditions during the friction tests. Electron microscopy and other surface sensitive analytical techniques illustrate the resulting changes in sputtered MoS2 film morphology and chemistry which directly influence the film adherence and frictional properties.

  8. NASA Lessons Learned from Space Lubricated Mechanisms

    NASA Technical Reports Server (NTRS)

    Predmore, Roamer E.

    2000-01-01

    This document reviews the lessons learned from short-life and long life lubricated space mechanisms. A short-life lubricated mechanisms complete their life test qualification requirements after a few cycles. The mechanisms include the hinges, motors and bearings for deployment, release mechanisms, latches, release springs and support shops. Performance testing can be difficult and expensive but must be accomplished. A long-life lubricated mechanisms requires up to 5 years of life testing, or 10 to 100 years of successful flight. The long-life mechanisms include reaction wheels, momentum wheels, antenna gimbals, solar array drives, gyros and despin mechanisms. Several instances of how a mechanisms failed either in test, or in space use, and the lessons learned from these failures are reviewed. The effect of the movement away from CFC-113 cleaning solvent to ODC (Ozone-Depleting Chemical) -free is reviewed, and some of the alternatives are discussed.

  9. Miscibility of lubricants with refrigerants, Phase 1

    SciTech Connect

    Pate, M.B.; Zoz, S.C.; Berkenbosch, L.J. . Dept. of Agricultural Engineering)

    1992-10-01

    Miscibility data have been obtained for a variety of non-CFC refrigerants and their potential lubricants. Ten different refrigerants and seven different lubricants were investigated. Experiments are being performed in two phases: Phase I, reported herein, focuses on performing screening tests for miscibility and Phase II consists of developing miscibility plots. The miscibility tests are being performed in a test facility consisting of a series of miniature test cells submerged in a constant temperature bath. The bath temperature can be precisely controlled over a temperature range of -50 C to 90C(-58 F to 194 F). The test cells are constructed to allow for complete visibility of lubricant-refrigerant mixtures under all test conditions.

  10. Used lubricating oil recycling using hydrocarbon solvents.

    PubMed

    Hamad, Ahmad; Al-Zubaidy, Essam; Fayed, Muhammad E

    2005-01-01

    A solvent extraction process using new hydrocarbon solvents was employed to treat used lubricant oil. The solvents used were liquefied petroleum gas (LPG) condensate and stabilized condensate. A demulsifier was used to enhance the treatment process. The extraction process using stabilized condensate demonstrated characteristics that make it competitive with existing used oil treatment technologies. The process is able to reduce the asphaltene content of the treated lubricating oil to 0.106% (w/w), the ash content to 0.108%, and the carbon residue to 0.315% with very low levels of contaminant metals. The overall yield of oil is 79%. The treated used oil can be recycled as base lubricating oil. The major disadvantage of this work is the high temperature of solvent recovery. Experimental work and results are presented in detail. PMID:15627468

  11. Compatibility of refrigerants and lubricants with elastomers

    SciTech Connect

    Hamed, G.R.; Seiple, R.H.

    1992-10-01

    Information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on the availability of additional quantities of R-32. Swell behavior in the fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 hours and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

  12. Additives for high-temperature liquid lubricants

    NASA Technical Reports Server (NTRS)

    Lawton, Emil A.; Yavrouian, Andre H.; Repar, John

    1988-01-01

    A preliminary research program was conducted to demonstrate a new concept for additives to liquid lubricants. It was demonstrated that suspensions of o-phthalonitrile and a substituted 1,2-maleonitrile in mineral oil and dilute solutions of o-phthalonitrile and tetrafluoro-o-phthalonitrile extended the lifetime of bearings under boundary lubricating conditions. The solutions exhibited coefficients of friction under high loads of 0.02-0.03. These results were consistent with the hypothesis that these compounds react with the hot metal surface to form a planar lubricating film by means of a metal or metal oxide template reaction. Also, the adherence was very strong due to the chelating action of the planar macrocycles postulated to form under the experimental conditions.

  13. Materials compatibility and lubricants research on CFC-refrigerant substitute: Miscibility of lubricants with refrigerants

    SciTech Connect

    Pate, M.B.; Zoz, S.; Berkenbosch, L. . Dept. of Mechanical Engineering)

    1992-04-01

    During this reporting period, modifications were made to the experimental apparatus in preparation for performing the experiments required in this project. In addition, new procedures for charging the lubricant and refrigerant into the cells for high temperature tests have been adopted. All of the refrigerants (10 different types) and lubricants (seven different types) have been ordered from the manufacturers. To date, the data obtained includes that for R-134a and four lubricants, namely, two esters and two polypropylene glycols (PAGs). Methods for quantifying immiscibility based on observation by different lab workers have been developed.

  14. Fully-coupled analysis of jet mixing problems. Part 1. Shock-capturing model, SCIPVIS

    NASA Technical Reports Server (NTRS)

    Dash, S. M.; Wolf, D. E.

    1984-01-01

    A computational model, SCIPVIS, is described which predicts the multiple cell shock structure in imperfectly expanded, turbulent, axisymmetric jets. The model spatially integrates the parabolized Navier-Stokes jet mixing equations using a shock-capturing approach in supersonic flow regions and a pressure-split approximation in subsonic flow regions. The regions are coupled using a viscous-characteristic procedure. Turbulence processes are represented via the solution of compressibility-corrected two-equation turbulence models. The formation of Mach discs in the jet and the interactive analysis of the wake-like mixing process occurring behind Mach discs is handled in a rigorous manner. Calculations are presented exhibiting the fundamental interactive processes occurring in supersonic jets and the model is assessed via comparisons with detailed laboratory data for a variety of under- and overexpanded jets.

  15. Development of mixed-waste analysis capability for graphite furnace atomic absorption spectrophotometry

    SciTech Connect

    Bass, D.A.; TenKate, L.B.; Wroblewski, A.

    1995-03-01

    Graphite furnace atomic absorption spectrophotometer (GFAAS) are typically configured with ventilation to capture potentially toxic and corrosive gases emitted from the vaporization of sample aliquots. When radioactive elements are present, additional concerns (such as meeting safety guidelines and ALARA principles) must be addressed. This report describes a modification to a GFAAS that provides additional containment of vaporized sample aliquots. The modification was found to increase containment by a factor of 80, given expected operating conditions. The use of the modification allows more mixed-waste samples to be analyzed, permits higher levels of radioactive samples to be analyzed, or exposes the analyst to less airborne radioactivity. The containment apparatus was attached to a Perkin-Elmer Zeeman 5000 spectrophotometer for analysis of mixed-waste samples; however, it could also be used on other systems and in other applications where greater containment of vaporized material is desired.

  16. Robust passivity analysis for discrete-time recurrent neural networks with mixed delays

    NASA Astrophysics Data System (ADS)

    Huang, Chuan-Kuei; Shu, Yu-Jeng; Chang, Koan-Yuh; Shou, Ho-Nien; Lu, Chien-Yu

    2015-02-01

    This article considers the robust passivity analysis for a class of discrete-time recurrent neural networks (DRNNs) with mixed time-delays and uncertain parameters. The mixed time-delays that consist of both the discrete time-varying and distributed time-delays in a given range are presented, and the uncertain parameters are norm-bounded. The activation functions are assumed to be globally Lipschitz continuous. Based on new bounding technique and appropriate type of Lyapunov functional, a sufficient condition is investigated to guarantee the existence of the desired robust passivity condition for the DRNNs, which can be derived in terms of a family of linear matrix inequality (LMI). Some free-weighting matrices are introduced to reduce the conservatism of the criterion by using the bounding technique. A numerical example is given to illustrate the effectiveness and applicability.

  17. A three-dimensional approach for analysis of sidewall injector mixing and combustion

    NASA Technical Reports Server (NTRS)

    Quan, Victor; Smith, Donald M.; Mathur, Atul B.; Edelman, Raymond B.

    1990-01-01

    A three-dimensional (3-D) analytical approach to calculate the mixing and combustion efficiency along engine combustors that use sidewall fuel injectors is described. The analysis consists of three parts: (1) an empirical correlation for fuel penetration, (2) application of integral conservation laws following jet turning and pressure equilibration, and (3) an analytical solution for the simplified three-dimensional partial differential equations to describe the downstream mixing and combustion process. Numerical results are compared to some empirical and experimental work, and favorable agreements are shown. The importance of including anisotropic turbulence and three-dimensional effects are illustrated by comparison with data and other less comprehensive analyses. The analytical solution is suitable for rapid estimates of engine performance and parametric studies of combustor designs containing transverse or angled injector ports arranged in rows and/or columns.

  18. Analysis of the forward-backward trajectory solution for the mixed quantum-classical Liouville equation.

    PubMed

    Hsieh, Chang-Yu; Kapral, Raymond

    2013-04-01

    Mixed quantum-classical methods provide powerful algorithms for the simulation of quantum processes in large and complex systems. The forward-backward trajectory solution of the mixed quantum-classical Liouville equation in the mapping basis [C.-Y. Hsieh and R. Kapral, J. Chem. Phys. 137, 22A507 (2012)] is one such scheme. It simulates the dynamics via the propagation of forward and backward trajectories of quantum coherent state variables, and the propagation of bath trajectories on a mean-field potential determined jointly by the forward and backward trajectories. An analysis of the properties of this solution, numerical tests of its validity and an investigation of its utility for the study of nonadiabtic quantum processes are given. In addition, we present an extension of this approximate solution that allows one to systematically improve the results. This extension, termed the jump forward-backward trajectory solution, is analyzed and tested in detail and its various implementations are discussed. PMID:23574211

  19. Carbon-based tribofilms from lubricating oils.

    PubMed

    Erdemir, Ali; Ramirez, Giovanni; Eryilmaz, Osman L; Narayanan, Badri; Liao, Yifeng; Kamath, Ganesh; Sankaranarayanan, Subramanian K R S

    2016-08-01

    Moving mechanical interfaces are commonly lubricated and separated by a combination of fluid films and solid 'tribofilms', which together ensure easy slippage and long wear life. The efficacy of the fluid film is governed by the viscosity of the base oil in the lubricant; the efficacy of the solid tribofilm, which is produced as a result of sliding contact between moving parts, relies upon the effectiveness of the lubricant's anti-wear additive (typically zinc dialkyldithiophosphate). Minimizing friction and wear continues to be a challenge, and recent efforts have focused on enhancing the anti-friction and anti-wear properties of lubricants by incorporating inorganic nanoparticles and ionic liquids. Here, we describe the in operando formation of carbon-based tribofilms via dissociative extraction from base-oil molecules on catalytically active, sliding nanometre-scale crystalline surfaces, enabling base oils to provide not only the fluid but also the solid tribofilm. We study nanocrystalline catalytic coatings composed of nitrides of either molybdenum or vanadium, containing either copper or nickel catalysts, respectively. Structurally, the resulting tribofilms are similar to diamond-like carbon. Ball-on-disk tests at contact pressures of 1.3 gigapascals reveal that these tribofilms nearly eliminate wear, and provide lower friction than tribofilms formed with zinc dialkyldithiophosphate. Reactive and ab initio molecular-dynamics simulations show that the catalytic action of the coatings facilitates dehydrogenation of linear olefins in the lubricating oil and random scission of their carbon-carbon backbones; the products recombine to nucleate and grow a compact, amorphous lubricating tribofilm. PMID:27488799

  20. FY2013 Progress Report for Fuel & Lubricant Technologies

    SciTech Connect

    none,

    2014-02-01

    Annual progress report for Fuel & Lubricant Technologies. The Fuel & Lubricant Technologies Program supports fuels and lubricants research and development (R&D) to provide vehicle manufacturers and users with cost-competitive options that enable high fuel economy with low emissions, and contribute to petroleum displacement.

  1. 7 CFR 2902.43 - Chain and cable lubricants.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Chain and cable lubricants. 2902.43 Section 2902.43... Items § 2902.43 Chain and cable lubricants. (a) Definition. Products designed to provide lubrication in such applications as bar and roller chains, sprockets, and wire ropes and cables. Products may...

  2. Hard-on-Hard Lubrication in the Artificial Hip under Dynamic Loading Conditions

    PubMed Central

    Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S.; Heitzmann, Daniel W. W.; Kretzer, J. Philippe

    2013-01-01

    The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal. PMID:23940772

  3. Role of uppermost superficial surface layer of articular cartilage in the lubrication mechanism of joints

    PubMed Central

    KUMAR, P.; OKA, M.; TOGUCHIDA, J.; KOBAYASHI, M.; UCHIDA, E.; NAKAMURA, T.; TANAKA, K.

    2001-01-01

    The uppermost superficial surface layer of articular cartilage, the ‘lamina splendens’ which provides a very low friction lubrication surface in articular joints, was investigated using atomic force microscopy (AFM). Complementary specimens were also observed under SEM at −10 °C without dehydration or sputter ion coating. Fresh adult pig osteochondral specimens were prepared from the patellas of pig knee joints and digested with the enzymes, hyaluronidase, chondroitinase ABC and alkaline protease. Friction coefficients between a pyrex glass plate and the osteochondral specimens digested by enzymes as well as natural (undigested) specimens were measured, using a thrust collar apparatus. Normal saline, hyaluronic acid (HA) and a mixture of albumin, globulin, HA (AGH) were used as lubrication media. The surface irregularities usually observed in SEM studies were not apparent under AFM. The articular cartilage surface was resistant to hyaluronidase and also to chondroitinase ABC, but a fibrous structure was exhibited in alkaline protease enzymes-digested specimens. AFM analysis revealed that the thickness of the uppermost superficial surface layer of articular cartilage was between 800 nm and 2 μm in adult pig articular cartilage. The coefficient of friction (c.f.) was significantly higher in chondroitinase ABC and alkaline protease enzymes digested specimens. Generally, in normal saline lubrication medium, c.f. was higher in comparison to HA and AGH lubrication media. The role of the uppermost, superficial surface layer of articular cartilage in the lubrication mechanism of joints is discussed. PMID:11554503

  4. Role of uppermost superficial surface layer of articular cartilage in the lubrication mechanism of joints.

    PubMed

    Kumar, P; Oka, M; Toguchida, J; Kobayashi, M; Uchida, E; Nakamura, T; Tanaka, K

    2001-09-01

    The uppermost superficial surface layer of articular cartilage, the 'lamina splendens' which provides a very low friction lubrication surface in articular joints, was investigated using atomic force microscopy (AFM). Complementary specimens were also observed under SEM at -10 degrees C without dehydration or sputter ion coating. Fresh adult pig osteochondral specimens were prepared from the patellas of pig knee joints and digested with the enzymes, hyaluronidase, chondroitinase ABC and alkaline protease. Friction coefficients between a pyrex glass plate and the osteochondral specimens digested by enzymes as well as natural (undigested) specimens were measured, using a thrust collar apparatus. Normal saline, hyaluronic acid (HA) and a mixture of albumin, globulin, HA (AGH) were used as lubrication media. The surface irregularities usually observed in SEM studies were not apparent under AFM. The articular cartilage surface was resistant to hyaluronidase and also to chondroitinase ABC, but a fibrous structure was exhibited in alkaline protease enzymes-digested specimens. AFM analysis revealed that the thickness of the uppermost superficial surface layer of articular cartilage was between 800 nm and 2 microm in adult pig articular cartilage. The coefficient of friction (c.f.) was significantly higher in chondroitinase ABC and alkaline protease enzymes digested specimens. Generally, in normal saline lubrication medium, c.f. was higher in comparison to HA and AGH lubrication media. The role of the uppermost, superficial surface layer of articular cartilage in the lubrication mechanism of joints is discussed. PMID:11554503

  5. Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

    PubMed

    Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S; Heitzmann, Daniel W W; Kretzer, J Philippe

    2013-01-01

    The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

  6. Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

    PubMed

    Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S; Heitzmann, Daniel W W; Kretzer, J Philippe

    2013-01-01

    The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal. PMID:23940772

  7. MEMS Lubrication by In-Situ Tribochemical Reactions From the Vapor Phase.

    SciTech Connect

    Dugger, Michael Thomas; Asay, David B.; Kim, Seong H.

    2008-01-01

    Vapor Phase Lubrication (VPL) of silicon surfaces with pentanol has been demonstrated. Two potential show stoppers with respect to application of this approach to real MEMS devices have been investigated. Water vapor was found to reduce the effectiveness of VPL with alcohol for a given alcohol concentration, but the basic reaction mechanism observed in water-free environments is still active, and devices operated much longer in mixed alcohol and water vapor environments than with chemisorbed monolayer lubricants alone. Complex MEMS gear trains were successfully lubricated with alcohol vapors, resulting in a factor of 104 improvement in operating life without failure. Complex devices could be made to fail if operated at much higher frequencies than previously used, and there is some evidence that the observed failure is due to accumulation of reaction products at deeply buried interfaces. However, if hypothetical reaction mechanisms involving heated surfaces are valid, then the failures observed at high frequency may not be relevant to operation at normal frequencies. Therefore, this work demonstrates that VPL is a viable approach for complex MEMS devices in conventional packages. Further study of the VPL reaction mechanisms are recommended so that the vapor composition may be optimized for low friction and for different substrate materials with potential application to conventionally fabricated, metal alloy parts in weapons systems. Reaction kinetics should be studied to define effective lubrication regimes as a function of the partial pressure of the vapor phase constituent, interfacial shear rate, substrate composition, and temperature.

  8. Rotor self-lubricating axial stop

    NASA Technical Reports Server (NTRS)

    Blount, Dale H.

    1988-01-01

    A series of lubricating plugs is located in the stationary backup face adjacent to the axial stop face of a rotating impeller mounted in a turbopump for pumping liquid oxygen or liquid hydrogen. The stop face and the backup face are those surfaces which engage when the axial load on the impeller exceeds the load balancing capability. The plugs have a truncated conical configuration so as to be trapped in the backup face, and are placed at varying radii on the face to provide complete surface lubrication. The plugs may be formed from Teflon, Kel-F or bronze filled Teflon.

  9. Rotor self-lubricating axial stop

    NASA Technical Reports Server (NTRS)

    Blount, Dale H. (Inventor)

    1989-01-01

    A plurality of lubricating plugs are disposed in the stationary backup face adjacent to the axial stop face of a rotating impeller mounted in a turbopump for pumping liquid oxygen or liquid hydrogen. The stop face and the backup face are those surfaces which engage when the axial load on the impeller exceeds the load balancing capability. The plugs have a truncated conical configuration so as to be trapped in the backup face, and are disposed at varying radii on the face to provide complete surface lubrication. The plugs may be formed from Teflon, Kel-F or bronze filled Teflon.

  10. Ionic liquid lubrication at electrified interfaces

    NASA Astrophysics Data System (ADS)

    Kong, Lingling; Huang, Wei; Wang, Xiaolei

    2016-06-01

    The lubrication performances of ionic liquids at electrified interfaces have been investigated by using a reciprocating sliding tribometer. Experimental results indicated that the lubricity of the confined ionic liquids was markedly affected by the application of external electric field and strong interface electric field strength could result in high friction. The influence was more pronounced for the ionic liquid with a shorter alkyl side chain in particular. The main reason of the friction increment might be ascribed to the electrically influenced surface adsorption where the charged ions were structured to form robust and ordered layers.

  11. Method for reclaiming waste lubricating oils

    DOEpatents

    Whisman, Marvin L.; Goetzinger, John W.; Cotton, Faye O.

    1978-01-01

    A method for purifying and reclaiming used lubricating oils containing additives such as detergents, antioxidants, corrosion inhibitors, extreme pressure agents and the like and other solid and liquid contaminants by preferably first vacuum distilling the used oil to remove water and low-boiling contaminants, and treating the dried oil with a solvent mixture of butanol, isopropanol and methylethyl ketone which causes the separation of a layer of sludge containing contaminants, unspent additives and oxidation products. After solvent recovery, the desludged oil is then subjected to conventional lubricating oil refining steps such as distillation followed by decolorization and deodorization.

  12. Sputtering technology in solid film lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1978-01-01

    Current and potential sputtering technology is reviewed as it applies primarily to the deposition of MoS2, though such lubricants as WS2 and PTFE are also considered. It is shown by electron microscopy and surface sensitive analytical techniques that the lubricating properties of sputtered MoS2 films are directly influenced by the sputtering parameters selected (i.e., power density, pressure, sputter etching, dc-biasing, etc.), substrate temperature, chemistry, topography, and environmental conditions during the friction test. Electron micrographs and diffractograms of sputtered MoS2 films clearly show the resultant changes in film morphology which affect film adherence and frictional properties.

  13. Materials Compatibility and Lubricants Research on CFC-refrigerant substitutes. Quarterly MCLR Program technical progress report, July 1--September 30, 1995

    SciTech Connect

    Szymurski, S.R.; Hourahan, G.C.; Godwin, D.S.; Amrane, K.

    1995-10-01

    The Materials Compatibility and Lubricants Research (MCLR) program supports critical research to accelerate the introduction of CFC and HCFC refrigerant substitutes. The MCLR program addresses refrigerant and lubricant properties and materials compatibility. The primary elements of the work include data collection and dissemination, materials compatibility testing, and methods development. This report summarizes the research conducted during the third quarter of calendar year 1995 on the following projects: Thermophysical properties of HCFC alternatives; Compatibility of manufacturing process fluids with HFC refrigerants and ester lubricants; Compatibility of motor materials used in air-conditioning for retrofits with alternative refrigerants and lubricants; Compatibility of lubricant additives with HFC refrigerants and synthetic lubricants; Products of motor burnouts; Accelerated test methods for predicting the life of motor materials exposed to refrigerant-lubricant mixtures; Investigation of flushing and clean-out methods; Investigation into the fractionation of refrigerant blends; Lean flammability limits as a fundamental refrigerant property; Effect of selected contaminants in AC and R equipment; Study of foaming characteristics; Study of lubricant circulation in systems; Evaluation of HFC-245ca for commercial use in low pressure chillers; Infrared analysis of refrigerant mixtures; Refrigerant database; Refrigerant toxicity survey; Thermophysical properties of HFC-32, HFC-123, HCFC-124 and HFC-125; Thermophysical properties of HFC-143a and HFC-152a; Theoretical evaluations of R-22 alternative fluids; Chemical and thermal stability of refrigerant-lubricant mixtures with metals; Miscibility of lubricants with refrigerants; Viscosity, solubility and density measurements of refrigerant-lubricant mixtures; Electrohydrodynamic enhancement of pool and in-tube boiling of alternative refrigerants; Accelerated screening methods; and more.

  14. An in-depth longitudinal analysis of mixing patterns in a small scientific collaboration network

    SciTech Connect

    Rodriguez, Marko A; Pepe, Alberto

    2009-01-01

    Many investigations of scientific collaboration are based on large-scale statistical analyses of networks constructed from bibliographic repositories. These investigations often rely on a wealth of bibliographic data, but very little or no other information about the individuals in the network, and thus, fail to illustate the broader social and academic landscape in which collaboration takes place. In this article, we perform an in-depth longitudinal analysis of a small-scale network of scientific collaboration (N = 291) constructed from the bibliographic record of a research center involved in the development and application of sensor network technologies. We perform a preliminary analysis of selected structural properties of the network, computing its range, configuration and topology. We then support our preliminary statistical analysis with an in-depth temporal investigation of the assortativity mixing of these node characteristics: academic department, affiliation, position, and country of origin of the individuals in the network. Our qualitative analysis of mixing patterns offers clues as to the nature of the scientific community being modeled in relation to its organizational, disciplinary, institutional, and international arrangements of collaboration.

  15. Analysis and testing of two-dimensional vented Coanda ejectors with asymmetric variable area mixing sections

    NASA Technical Reports Server (NTRS)

    Maroti, L. A.; Hill, P. G.; Armstrong, R. L.; Haines, D. M.

    1976-01-01

    The analysis of asymmetric, curved (Coanda) ejector flow has been completed using a finite difference technique and a quasi-orthogonal streamline coordinate system. The boundary layer type jet mixing analysis accounts for the effect of streamline curvature in pressure gradients normal to the streamlines and on eddy viscosities. The analysis assured perfect gases, free of pressure discontinuities and flow separation and treated three compound flows of supersonic and subsonic streams. Flow parameters and ejector performance were measured in a vented Coanda flow geometry for the verification of the computer analysis. A primary converging nozzle with a discharge geometry of 0.003175 m x 0.2032 m was supplied with 0.283 cu m/sec of air at about 241.3 KPa absolute stagnation pressure and 82 C stagnation temperature. One mixing section geometry was used with a 0.127 m constant radius Coanda surface. Eight tests were run at spacing between the Coanda surface and primary nozzle 0.01915 m and 0.318 m and at three angles of Coanda turning: 22.5 deg, 45.0 deg, and 75.0 deg. The wall static pressures, the loci of maximum stagnation pressures, and the stagnation pressure profiles agree well between analytical and experimental results.

  16. Collaboration in sensor network research: an in-depth longitudinal analysis of assortative mixing patterns.

    PubMed

    Pepe, Alberto; Rodriguez, Marko A

    2010-09-01

    Many investigations of scientific collaboration are based on statistical analyses of large networks constructed from bibliographic repositories. These investigations often rely on a wealth of bibliographic data, but very little or no other information about the individuals in the network, and thus, fail to illustrate the broader social and academic landscape in which collaboration takes place. In this article, we perform an in-depth longitudinal analysis of a relatively small network of scientific collaboration (N = 291) constructed from the bibliographic record of a research centerin the development and application of wireless and sensor network technologies. We perform a preliminary analysis of selected structural properties of the network, computing its range, configuration and topology. We then support our preliminary statistical analysis with an in-depth temporal investigation of the assortative mixing of selected node characteristics, unveiling the researchers' propensity to collaborate preferentially with others with a similar academic profile. Our qualitative analysis of mixing patterns offers clues as to the nature of the scientific community being modeled in relation to its organizational, disciplinary, institutional, and international arrangements of collaboration.

  17. Effectiveness of solid lubricant coatings for friction in hard vacuum (10-9 tor)

    NASA Technical Reports Server (NTRS)

    Verkin, B. I.; Lyubraskiy, I. M.; Udovenko, V. F.; Sentyurikhina, L. N.

    1974-01-01

    A study was made of the efficiency of solid lubricating coatings, based on MoS2 with various binders, during friction and under highvacuum conditions. Mass spectrometry was used for an analysis of the composition of the gas evolved from the coatings in the friction process. It is shown that the vacuum level, loading, and sliding velocity influence coating effectiveness. In the friction process the solid lubricant coatings yield characteristic decay products associated with the chemical nature of the binders. The mechanism of coating breakdown during friction is associated with the binder breakdown mechanism.

  18. Lubricants or lubricant additives composed of ionic liquids containing ammonium cations

    DOEpatents

    Qu, Jun [Knoxville, TN; Truhan, Jr; John, J [Cookeville, TN; Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN; Blau, Peter J [Knoxville, TN

    2010-07-13

    A lubricant or lubricant additive is an ionic liquid alkylammonium salt. The alkylammonium salt has the structure R.sub.xNH.sub.(4-x).sup.+,[F.sub.3C(CF.sub.2).sub.yS(O).sub.2].sub.2N.sup- .- where x is 1 to 3, R is independently C.sub.1 to C.sub.12 straight chain alkyl, branched chain alkyl, cycloalkyl, alkyl substituted cycloalkyl, cycloalkyl substituted alkyl, or, optionally, when x is greater than 1, two R groups comprise a cyclic structure including the nitrogen atom and 4 to 12 carbon atoms, and y is independently 0 to 11. The lubricant is effective for the lubrication of many surfaces including aluminum and ceramics surfaces.

  19. Introduction to Studies in Granular Mixing

    ERIC Educational Resources Information Center

    Llusa, Marcos; Muzzio, Fernando

    2008-01-01

    This article describes a hands-on educational activity designed to introduce students (or industrial employees) in the pharmaceutical arena to some of the most common problems in the mixing of solids: Active Pharmaceutical Ingredient (API) and lubricant (i.e. magnesium stearate) homogenization, characterization of segregation tendencies, and…

  20. The use of screening tests in spacecraft lubricant evaluation

    NASA Technical Reports Server (NTRS)

    Kalogeras, Chris; Hilton, Mike; Carre, David; Didziulis, Stephen; Fleischauer, Paul

    1993-01-01

    A lubricant screening test fixture has been devised in order to satisfy the need to obtain lubricant performance data in a timely manner. This fixture has been used to perform short-term tests on potential lubricants for several spacecraft applications. The results of these tests have saved time by producing qualitative performance rankings of lubricant selections prior to life testing. To date, this test fixture has been used to test lubricants for 3 particular applications. The qualitative results from these tests have been verified by life test results and have provided insight into the function of various anti-wear additives.