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1

Simple modeling of hydrostatic bearings  

NASA Astrophysics Data System (ADS)

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

Hull, Charlie

2014-07-01

2

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

E-print Network

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

Rothenhöfer, Gerald S. (Gerald Sven)

2007-01-01

3

Hydrostatic bearings for a turbine fluid flow metering device  

DOEpatents

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

Fincke, James R. (Rigby, ID)

1982-01-01

4

Hydrostatic bearings for a turbine fluid flow metering device  

DOEpatents

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

Fincke, J.R.

1982-05-04

5

Hydrostatic bearings for a turbine fluid flow metering device  

DOEpatents

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

Fincke, J.R.

1980-05-02

6

A hydrostatic rotary bearing with angled surface self-compensation  

Microsoft Academic Search

A design for a low profile hydrostatic rotary bearing is presented that utilizes a new type of self-compensation that allows a large number of bearing pockets to be present with only a few precision round parts, thus allowing high hydrostatic averaging with relatively low design complexity. A key feature of this design is that it does not use capillaries or

N. R. Kane; J. Sihler; A. H. Slocum

2003-01-01

7

A Porous Hydrostatic Gas Bearing for Use in Miniature Turbomachinery  

Microsoft Academic Search

An analytical program was conducted to establish recommended types of gas-lubricated journal bearings for use in miniature cryogenic turbomachinery. Very high rotative speeds, and the limiting damping properties of gas, indicated that fractional frequency whirl is prevalent, and the most difficult problem to overcome. Of the many journal bearing types investigated, the tilting pad hydro-dynamic and porous hydrostatic journal bearings

S. Heller; W. Shapiro; O. Decker

1971-01-01

8

Hybrid hydrostatic/ball bearings in high-speed turbomachinery  

NASA Technical Reports Server (NTRS)

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

Nielson, C. E.

1983-01-01

9

Laminar flow in a recess of a hydrostatic bearing  

NASA Technical Reports Server (NTRS)

The flow in a recess of a hydrostatic journal bearing is studied in detail. The Navier-Stokes equations for the laminar flow of an incompressible liquid are solved numerically in a two-dimensional plane of a typical bearing recess. Pressure- and shear-induced flows, as well as a combination of these two flow conditions, are analyzed. Recess friction, pressure-ram effects at discontinuities in the flow region, and film entrance pressure loss effects are calculated. Entrance pressure loss coefficients over a forward-facing step are presented as functions of the mean flow Reynolds number for pure-pressure and shear-induced laminar flows.

San Andres, Luis A.; Velthuis, Johannes F. M.

1992-01-01

10

Tribological study on hydrostatic slipper bearing with annular orifice damper for water hydraulic axial piston motor  

Microsoft Academic Search

Hydrostatic slipper bearing is an effective way to maintain a fluid film between slipper pad and swash plate that slide against each other, and thereby mitigate direct surface-to-surface contact in water hydraulic axial piston motor (WHAPM). The hydrostatic slipper bearing with an annular orifice damper is proposed, and the reaction force of the bearing in WHAPM is investigated. The effects

S. L. Nie; G. H. Huang; Y. P. Li

2006-01-01

11

An analysis of the 70-meter antenna hydrostatic bearing by means of computer simulation  

NASA Technical Reports Server (NTRS)

Recently, the computer program 'A Computer Solution for Hydrostatic Bearings with Variable Film Thickness,' used to design the hydrostatic bearing of the 70-meter antennas, was modified to improve the accuracy with which the program predicts the film height profile and oil pressure distribution between the hydrostatic bearing pad and the runner. This article presents a description of the modified computer program, the theory upon which the computer program computations are based, computer simulation results, and a discussion of the computer simulation results.

Bartos, R. D.

1993-01-01

12

Research on performance of slide-valve in water hydraulic servo-valve with hydrostatic bearing  

Microsoft Academic Search

In order to optimize the motion characteristics of slide-valve in water hydraulic servo-valve. Hydrostatic bearing technology has been used between valve core and sleeve. The research on performance about the static characteristics of slide-valve in water hydraulic servo-valve with hydrostatic bearing structure and traditional throttle with fixed orifice has been carried. The mathematical model of the pressure-flow characteristics, the pressure

Wang Xinhua; Zheng Jian; Sun Shuwen; Li Wei; Chang Jiaqing

2010-01-01

13

Clearance sensing hydrostatic bearing restrictor for the homopolar generator systems tester  

SciTech Connect

This work documents the development of an advanced hydrostatic bearing system for the subcritical operation of the Homopolar Generator Systems Tester. Since this Systems Tester is unique in that it was built with stationary shaft bearings, several new hydrostatic bearing ideas were developed. First, a new clearance sensing variable restrictor was developed to accommodate the almost five fold increase in radial bearing clearance intrinsic to the machine geometry encountered during each machine cycle. A new dynamic hydrostatic thrust-bearing model was developed that permits tilt about any axis perpendicular to the axis of rotation as well as axial motion. These bearings are well instrumented providing data to verify the models both at rest and during operation. In addition to the bearing advances, overall machine design decisions, as well as the factors which influenced them, are examined. Magnetic effects are discussed with respect to both rotor dynamic effects and thrust bearing loading. Bearing sump and sealing philosophies are also discussed. Decisions concerning rotor geometry are similarly reviewed. Finally, the results of the experiment are evaluated in terms of the future impact on not only homopolar generators, but on rotating machinery in general.

Vaughn, M.R.

1985-01-01

14

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

NASA Astrophysics Data System (ADS)

The hydraulic circuit, through which the mineral oil is brought, is an important part of hydrostatic bearings. The annular hydrostatic thrust bearing consists of two sliding plates divided by a layer of mineral oil. In the lower plate, there are oil grooves which distribute the liquid between the sliding areas. The hydraulic circuit is made of two basic parts: the energy source and the controlling part. The hydraulic pump, which brings the liquid into the sliding bearing, is the source of the pressure energy. The sliding bearing is weighted down by axial force, which can be changed during the process. That's why in front of the particular oil grooves control components adjusting pressure and flow size are located. This paper deals with a project of a hydraulic circuit for regulation of fluid layer in the annular hydrostatic thrust bearing and the testing equipment for measuring its physical properties. It will include the issue of measuring loading capacity and height of the fluid layer in the annular hydrostatic thrust bearing.

Kozdera, Michal; Drábková, Sylva; Bojko, Marian

2014-03-01

15

Mixed Lubrication Simulation of Hydrostatic Spherical Bearings for Hydraulic Piston Pumps and Motors  

NASA Astrophysics Data System (ADS)

Mixed and fluid film lubrication characteristics of hydrostatic spherical bearings for swash-plate-type axial piston pumps and motors are studied theoretically under non-steady-state conditions. The basic equations incorporating interference and contact of surface roughness are derived fundamentally through combination of the GW and PC models. Furthermore, a programming code that is applicable to the caulked-socket-type and open-socket-type bearings is developed. Effects of caulking, operating conditions, and the bearing dimension on the motion of the sphere and tribological performance of the bearings are examined. Salient conclusions are the following: The sphere's eccentricity increases in the low supply pressure period. The time-lag of the load change engenders greater motion of the sphere. Caulking of the bearing socket suppresses the sphere's motion. The bearing stiffness increases and power loss decreases for smaller recess angles. Minimum power loss is given under the condition that the bearing socket radius nearly equals the equivalent load radius.

Kazama, Toshiharu

16

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

17

Dynamic force response of spherical hydrostatic journal bearing for cryogenic applications  

NASA Technical Reports Server (NTRS)

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

Sanandres, Luis

1994-01-01

18

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

E-print Network

Hybrid (combination hydrostatic and hydrodynamic) bearings have been proposed for use as a support element in cryogenic high speed turbomachinery for primary and auxiliary space power applications because of their long lifetime, low friction...

Mosher, Phillip Andrew

1993-01-01

19

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

NASA Technical Reports Server (NTRS)

A facility and apparatus are described which determine stiffness, damping, and added-mass rotordynamic coefficients plus steady-state operating characteristics of high speed hydrostatic journal bearings. The apparatus has a current top speed of 29,800 rpm with a bearing diameter of 7.62 cm (3 in.). Purified warm water, 55 C (130 F), is used as a test fluid to achieve elevated Reynolds numbers during operation. The test-fluid pump yields a bearing maximum inlet pressure of 6.9 Mpa (1000 psi). Static load on the bearing is independently controlled and measured. Orthogonally mounted external shakers are used to excite the test stator in the direction of, and perpendicular to, the static load. The apparatus can independently calculate all rotordynamic coefficients at a given operating condition.

Childs, Dara; Hale, Keith

1994-01-01

20

Oil pocket's bearing capacity analysis of liquid hydrostatic worktable in Gantry Moving Milling Center  

NASA Astrophysics Data System (ADS)

Durning the design process of hydrostatic rotary worktable, the processing and assembly tolerance, (the offset of worktable and the gap of the oil film's thickness) is ignored. But it will cause that the real bearing of oil pocket deviates from the initial design value, and then the performance of rotary worktable will be reduced significantly. Up to now, no effort is found toward the research of influence of the processing and assembly tolerance on the performance of the rotary worktable. So the hydrostatic oil film is assumed as the elastomer in this paper, and then the bearing capacity of the oil pocket is studied with and without the mass offset of the worktable by taking an expression between the bearing capacity and the oil film's thickness of the oil pocket as the deform compatibility equation. The influence of the processing tolerance of the oil sealing belt's gap on the bearing capacity of the oil pocket is analyzed. In the light of the liquid hydrostatic worktable of Gantry Moving Milling Center using on the scene, the oil pocket's pressure of the worktable is tested using Rotary Worktable Test System under the circumstance of the mass offset of the worktable and the gap tolerance of the oil sealing belt, and then the equivalent offset of worktable, the average pressure of the oil pocket and the actual thickness of the oil film are analyzed respectively. The test results show that the bearing capacity component of the oil pocket caused by G is consistent, and the component caused by M is relative to the position of the oil pocket. When the oil sealing belt's gap is larger than the theoretical value, the bearing capacity of the oil pocket is smaller than the others; whereas the bearing capacity of the oil pocket is larger than the others. The maximum and minimum equivalent offsets are 0.256 4 mm and 0.047 5 mm, respectively, and the average oil pocket pressure varies from 0.345 MPa to 0.460 MPa, the maximum and minimum value of the actual oil film thickness are 109.976 ?m (No. 7 oil pocket) and 93.467 ?m (No. 10 oil pocket), respectively. The research results can be used to detect the offset of the worktable and the actual thickness of the oil film under processing and assembly tolerance, and provides a basis way for detecting the processing and assembly tolerance of rotary worktable signing reasonably of Gantry Moving Milling Center.

Zhao, Jianhua; Liang, Yingna; Gao, Dianrong

2014-09-01

21

A fully coupled variable properties thermohydraulic model for a cryogenic hydrostatic journal bearing  

NASA Technical Reports Server (NTRS)

The goal set forth here is to continue the work started by Braun et al. (1984-1985) and present an integrated analysis of the behavior of the two row, 20 staggered pockets, hydrostatic cryogenic bearing used by the turbopumps of the Space Shuttle main engine. The variable properties Reynolds equation is fully coupled with the two-dimensional fluid film energy equation. The three-dimensional equations of the shaft and bushing model the boundary conditions of the fluid film energy equation. The effects of shaft eccentricity, angular velocity, and inertia pressure drops at pocket edge are incorporated in the model. Their effects on the bearing fluid properties, load carrying capacity, mass flow, pressure, velocity, and temperature form the ultimate object of this paper.

Braun, M. J.; Wheeler, R. L., III; Hendricks, R. C.

1986-01-01

22

Characteristics of hydrostatic bearing\\/seal parts for water hydraulic pumps and motors. Part 1: Experiment and theory  

Microsoft Academic Search

In this study, the characteristics of disk-type hydrostatic thrust bearings supporting concentric loads, simulating the major bearing\\/seal parts of water hydraulic pumps and motors, are presented. The bearing is made up of a combination of stainless steel\\/stainless steel and stainless steel\\/plastics. The characteristics are evaluated by studying the relationships among the load-carrying capacity, pocket pressure, film thickness, and leakage flow

X. Wang; A. Yamaguchi

2002-01-01

23

High Speed, High Temperature, Fault Tolerant Operation of a Combination Magnetic-Hydrostatic Bearing Rotor Support System for Turbomachinery  

NASA Technical Reports Server (NTRS)

Closed loop operation of a single, high temperature magnetic radial bearing to 30,000 RPM (2.25 million DN) and 540 C (1000 F) is discussed. Also, high temperature, fault tolerant operation for the three axis system is examined. A novel, hydrostatic backup bearing system was employed to attain high speed, high temperature, lubrication free support of the entire rotor system. The hydrostatic bearings were made of a high lubricity material and acted as journal-type backup bearings. New, high temperature displacement sensors were successfully employed to monitor shaft position throughout the entire temperature range and are described in this paper. Control of the system was accomplished through a stand alone, high speed computer controller and it was used to run both the fault-tolerant PID and active vibration control algorithms.

Jansen, Mark; Montague, Gerald; Provenza, Andrew; Palazzolo, Alan

2004-01-01

24

Characteristics of hydrostatic bearing\\/seal parts for water hydraulic pumps and motors. Part 2: On eccentric loading and power losses  

Microsoft Academic Search

In this paper, the load-carrying capacity, power losses and stiffness of disk-type hydrostatic thrust bearings including the case of eccentric loading are discussed theoretically. The numerical analysis method is established based on a two-dimensional elastohydrostatic problem with an elastic deformation model, which is extended to adapt it for a non-axisymmetric load acting on the thrust bearing. The bearing is made

X. Wang; A. Yamaguchi

2002-01-01

25

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

E-print Network

practice in current damper seal technology for cryogenic turbo pumps. Annular seals acting as Lomakin bearings have potential as support elements (damping bearings) in high speed cryogenic turbo pumps as well in process fluid applications. Figure 3 7... power cryogenic turbo-pumps (TP) are compact, operate at high speeds, and require of externally pressurized fluid film bearings to support radial and thrust loads. Hybrid thrust & radial bearings enable smaller and lighter turbopumps with no DN...

San Andres, Luis

2009-01-01

26

Hotfire testing of a SSME HPOTP with an annular hydrostatic bearing  

NASA Technical Reports Server (NTRS)

A new fluid film bearing package has been tested in the Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbopump (HPOTP). This fluid film element functions as both the pump end bearing and the preburner pump rear wear ring seal. Most importantly, it replaces a duplex ball bearing package which has been the primary life limiting component in the turbopump. The design and predicted performance of the turbopump are reviewed. Results are presented for measured pump and bearing performance during testing on the NASA Technology Test Bed (TTB) Engine located at MSFC. The most significant results were obtained from proximity probes located in the bearing bore which revealed large subsynchronous precession at ten percent of shaft speed during engine start which subsided prior to mainstage power levels and reappeared during engine shutdown at equivalent power levels below 65% of nominal. This phenomenon has been attributed to rotating stall in the diffuser. The proximity probes also revealed the location of the bearing in the bore for different operating speeds. Pump vibration characteristics were improved as compared to pumps tested with ball bearings. After seven starts and more than 700 seconds of testing, the pump showed no signs of performance degradation.

Nolan, Steven A.; Hibbs, Robert I.; Genge, Gary G.

1994-01-01

27

The 3,6 m Indo-Belgian Devasthal Optical Telescope: the hydrostatic azimuth bearing  

NASA Astrophysics Data System (ADS)

AMOS SA has been awarded of the contract for the design, manufacturing, assembly, tests and on site installation (Devasthal, Nainital in central Himalayan region) of the 3.6 m Indo-Belgian Devasthal Optical Telescope (IDOT). The telescope has a Ritchey-Chrétien optical configuration with a Cassegrain focus equipped with one axial port and two side ports. The primary mirror is a meniscus active mirror. The mount is an Alt-Az type with for the azimuth axis a 5 m diameter hydrostatic track. This paper presents the solution adopted by AMOS to meet the specific requirements for the azimuth axis. The track is designed to be able to control the positioning of the telescope around the azimuth axis with an accuracy of 0.05 arc second for all tracking configurations. The challenge came from this tight accuracy with a mass in rotation weighting 125 tons. The azimuth track was mounted and tested in AMOS workshop; the tests and performances are also discussed.

de Ville, Jonathan; Piérard, Maxime; Bastin, Christian

2012-09-01

28

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

E-print Network

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

Esser, Paul R.

2011-08-08

29

The combined effects of the centripetal inertia and the surface roughness on the hydrostatic thrust spherical bearings performance  

Microsoft Academic Search

This paper deals with the surface roughness and the predominant centripetal inertia terms due to the shaft rotation of the externally pressurized thrust spherical bearings. The solutions are presented for the fitted type of bearings, un-recessed and recessed hemispherical and partial hemispherical seats, with capillary tube and orifice restrictors. On the basis of the stochastic theory, Reynolds equation is developed.

Ahmad W. Yacout; Ashraf S. Ismaeel; Sadek Z. Kassab

2007-01-01

30

Bears  

NSDL National Science Digital Library

What are the characteristics of grizzly/brown bears and black bears? As you view the websites, please use this chart to record what you are learning about grizzly bears and black bears. For each bear, you should list 5 characteristics. Grizzly Bear and Black Bear Chart We will first begin by learning about black bears. Please go to these websites to learn some important facts about black bears. Black Bears Facts and Image Black Bear Facts for Kids Now that you have learned ...

Miss Bledsoe

2011-04-07

31

Bears, Bears, Bears!  

NSDL National Science Digital Library

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

Ms.Beason

2011-04-16

32

Dynamic modeling of hydrostatic guideway considering compressibility and inertia effect  

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

33

Hydrostatic, quasi-hydrostatic, and nonhydrostatic ocean modeling  

Microsoft Academic Search

Ocean models based on consistent hydrostatic, quasi-hydrostatic, and nonhydrostatic equation sets are formulated and discussed. The quasi-hydrostatic and nonhydrostatic sets are more accurate than the widely used hydrostatic primitive equations. Quasi-hydrostatic models relax the precise balance between gravity and pressure gradient forces by including in a consistent manner cosine-of-latitude Coriolis terms which are neglected in primitive equation models. Nonhydrostatic models

John Marshall; Chris Hill; Lev Perelman; Alistair Adcroft

1997-01-01

34

Hydrostatic fluid bearing gyro. [temperature control  

NASA Technical Reports Server (NTRS)

The design, fabrication, and testing are described of a thermal control assembly capable of precisely controlling the LDG-540 Gyro case temperature at 50 C over an ambient environment range of 23 C and atmosphere pressure to 5 C and a vacuum of 0.00001 torr. The thermal control assembly is a hermetically sealed enclosure about the LDG-540 Gyro with envelope dimensions not to exceed those of the Saturn K8-AB5 Gyro. The heaters are capable of delivery 30 watts at 28 V.D.C. and have dual temperature sensors rated at 750 ohms at 50 C. All six (6) LGD-540 Gyros will be equipped with a fine control heater and a resistance thermometer to monitor the gyro cast temperature. All six gyros will be interchangeable in the thermal control assembly by means of simply assembly techniques.

Brello, E. Y.

1975-01-01

35

Rotordynamic evaluation of a tangential-injection hybrid bearing  

E-print Network

: : Issued also on microfiche from Lange Micrographics. For future high-speed cryogenic turbomachinery, ball bearings will be replaced by hybrid bearings that combine hydrostatic and hydrodynamic effects. Hybrid bearings develop cross...

Laurant, Franck Jean

1998-01-01

36

Rotordynamic evaluation of a roughened-land hybrid bearing  

E-print Network

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

Fayolle, Patrice Gerard

1997-01-01

37

Hydrostatic actuation in MEMS  

NASA Astrophysics Data System (ADS)

Hydrostatic actuation is a novel method of actuation in Micro Electro Mechanical Systems (MEMS) and provides advantages over other actuation techniques in current use. Hydrostatic actuation utilises a contained pressurised medium to straighten a bent hollow beam, similar to the Bourdon tube used to measure pressure in the macro world. Research has commenced at RMIT University to design and fabricate a microgripper prototype to validate this work. To simplify the design of this microgripper a virtual prototype has been initiated. This paper looks at the work carried out and verification of this virtual prototype using mathematical and finite element modelling. Further work to be undertaken will also be discussed.

Mutzenich, Simon; Vinay, Thurai; Rosengarten, Gary

2002-11-01

38

BIOMACROMOLECULES UNDER HIGH HYDROSTATIC PRESSURE  

E-print Network

BIOMACROMOLECULES UNDER HIGH HYDROSTATIC PRESSURE A Dissertation Presented to the Faculty HIGH HYDROSTATIC PRESSURE Nozomi Ando, Ph.D. Cornell University 2009 Protein pressure denaturation denaturation studies. Recent studies imply that the mechanism of pressure denaturation is the penetration

Gruner, Sol M.

39

Hybrid bearings for turbopumps and the like  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

40

Hydrostatic drive arrangement  

SciTech Connect

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

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

1986-04-22

41

Lift-off performance in flexure pivot pad and hybrid bearings  

E-print Network

Three flexure pivot pad bearings (FPBs) with different preloads are evaluated for use in high performance applications by comparing them to a hybrid hydrostatic bearing (HHB). One application of these bearings is in turbopumps for liquid rocket...

Mertz, David Hunter

2009-05-15

42

A bulk-flow model of angled injection Lomakin bearings  

E-print Network

to dimensionless fields 1 1. INTRODUCTION Current trends in high-performance turbomachinery drive towards higher operational speeds and pressures to increase their power. In particular, in cryogenic turbopumps, hydrostatic annular seals along with hydrostatic... features; and thus, could be an effective alternative to hydrostatic journal bearings in cryogenic turbopumps for aero-space applications. Indeed, experimental measurements conducted on tangential-against-rotation injection Lomakin bearings demonstrate...

Soulas, Thomas Antoine Theo

2001-01-01

43

Hydrostatic continuously variable transmission  

SciTech Connect

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

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

1989-05-09

44

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

45

Computing Flows In Turbine End Bearings  

NASA Technical Reports Server (NTRS)

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

Smith, Tyn S.

1990-01-01

46

SSME Long-life Bearings  

NASA Technical Reports Server (NTRS)

Hybrid hydrostatic/ball bearings for LH2 and LO2 service in turbopumps were studied as a means of improving speed and life capabilities. Four hybrid bearing configurations were designed with emphasis on achieving maximum stiffness and damping. Parallel load bearings were tested at steady-state and transient conditions with LH2 (externally fed) and LN2 (internally fed). The hydrostatic elements were tested with Freon 113 for empirical determination of dynamic characteristics. Tests using an eccentric journal for loading showed the externally and internally fed hydrostatic bearings to have significant separated coefficients of direct stiffness and damping. For the internally fed bearing, the strongly speed-dependent cross-coupling stiffness arising from fluid swirl, along with significant cross-coupling damping, resulted in low net effective stiffness and damping. The test method used can produce separated coefficients with a sufficiently elliptic journal orbit; otherwise, only net effective coefficients combining direct and cross-coupling terms can be determined. Testing with nonsynchronous excitation is recommended to avoid this restriction. Investigation of hard materials, including ceramics, is recommended as a means of eliminating the need for the rolling bearing for startup and shutdown support. The testing was performed in 1984 (LH2), 1985 (LN2) and 1985-86 (Freon).

Butner, M. F.; Murphy, B. T.

1986-01-01

47

High-temperature ''hydrostatic'' extrusion  

NASA Technical Reports Server (NTRS)

Quasi-fluids permit hydrostatic extrusion of solid materials. The use of sodium chloride, calcium fluoride, or glasses as quasi-fluids reduces handling, corrosion, and sealing problems, these materials successfully extrude steel, molybdenum, ceramics, calcium carbonate, and calcium oxide. This technique also permits fluid-to-fluid extrusion.

Hunt, J. G.; Rice, R. W.

1970-01-01

48

Deep water hydrostatic head control  

SciTech Connect

Hydrostatic head control in the marine riser or sub-sea BOP stack of a deep water drilling unit is maintained through use of an eductor, or similar means, connected to the sub-sea BOP stack choke line for drawing salt water from the sea or mud from the sub-sea BOP stack kill line.

Sykora, J.H.

1984-01-24

49

Deep water hydrostatic head control  

Microsoft Academic Search

Hydrostatic head control in the marine riser or sub-sea BOP stack of a deep water drilling unit is maintained through use of an eductor, or similar means, connected to the sub-sea BOP stack kill line for drawing salt water from the sea or mud from the sub-sea BOP stack choke line.

Sykora

1985-01-01

50

Deep water hydrostatic head control  

SciTech Connect

Hydrostatic head control in the marine riser or sub-sea BOP stack of a deep water drilling unit is maintained through use of an eductor, or similar means, connected to the sub-sea BOP stack kill line for drawing salt water from the sea or mud from the sub-sea BOP stack choke line.

Sykora, J. H.

1985-01-29

51

Deep water hydrostatic head control  

Microsoft Academic Search

Hydrostatic head control in the marine riser or sub-sea BOP stack of a deep water drilling unit is maintained through use of an eductor, or similar means, connected to the sub-sea BOP stack choke line for drawing salt water from the sea or mud from the sub-sea BOP stack kill line.

Sykora

1984-01-01

52

Worm Gear With Hydrostatic Engagement  

NASA Technical Reports Server (NTRS)

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

Chaiko, Lev I.

1994-01-01

53

ANSYS Modeling of Hydrostatic Stress Effects  

NASA Technical Reports Server (NTRS)

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

Allen, Phillip A.

1999-01-01

54

Hydrostatic Hyperbaric Chamber Ventilation System  

NASA Technical Reports Server (NTRS)

The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications, including the treatment of medical conditions. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy available in the developing world for the treatment of a variety of medical conditions. Specifically, hyperbaric oxygen therapy is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. Hyperbaric oxygen therapy is simply too expensive and too dangerous to implement in the developing world using standard equipment. The hydrostatic hyperbaric chamber technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system that will provide controlled pressurization of the system, and provide adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware, supports sustainability.

Sargusingh, Miriam M.

2011-01-01

55

Switching skeletons: hydrostatic support in molting crabs  

NASA Technical Reports Server (NTRS)

Skeletal support systems are essential for support, movement, muscular antagonism, and locomotion. Crustaceans shed their rigid exoskeleton at each molt yet are still capable of forceful movement. We hypothesize that the soft water-inflated body of newly molted crabs may rely on a hydrostatic skeleton, similar to that of worms and polyps. We measured internal hydrostatic pressure and the force exerted during claw adduction and observed a strong correlation between force and hydrostatic pressure, consistent with hydrostatic skeletal support. This alternation between the two basic skeletal types may be widespread among arthropods.

Taylor, Jennifer R A.; Kier, William M.; Walker, I. D. (Principal Investigator)

2003-01-01

56

Mechanical response of collagen molecule under hydrostatic compression.  

PubMed

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials. PMID:25687001

Saini, Karanvir; Kumar, Navin

2015-04-01

57

49 CFR 178.814 - Hydrostatic pressure test.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Hydrostatic pressure test. 178.814 Section 178.814...Testing of IBCs § 178.814 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2010-10-01

58

49 CFR 178.814 - Hydrostatic pressure test.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Hydrostatic pressure test. 178.814 Section 178.814...Testing of IBCs § 178.814 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2013-10-01

59

49 CFR 178.605 - Hydrostatic pressure test.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Hydrostatic pressure test. 178.605 Section 178.605...and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2013-10-01

60

49 CFR 178.814 - Hydrostatic pressure test.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Hydrostatic pressure test. 178.814 Section 178.814...Testing of IBCs § 178.814 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2011-10-01

61

49 CFR 178.605 - Hydrostatic pressure test.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Hydrostatic pressure test. 178.605 Section 178.605...and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2012-10-01

62

49 CFR 178.814 - Hydrostatic pressure test.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Hydrostatic pressure test. 178.814 Section 178.814...Testing of IBCs § 178.814 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2012-10-01

63

49 CFR 178.605 - Hydrostatic pressure test.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Hydrostatic pressure test. 178.605 Section 178.605...and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2011-10-01

64

49 CFR 178.605 - Hydrostatic pressure test.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Hydrostatic pressure test. 178.605 Section 178.605...and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2014-10-01

65

49 CFR 178.814 - Hydrostatic pressure test.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Hydrostatic pressure test. 178.814 Section 178.814...Testing of IBCs § 178.814 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the...

2014-10-01

66

Hydrostatic Hyperbaric Chamber Ventilation System  

NASA Technical Reports Server (NTRS)

The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy (HBOT) available in the developing world for the treatment of a variety of medical conditions. Specifically, HBOT is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. HBOT is simply too expensive and too dangerous to implement in the developing world using standard equipment. The HHC technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system to provide controlled pressurization and adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware, supports sustainability.

Sarguisingh, Miriam J.

2012-01-01

67

Operation of a Microfabricated High Speed Gas Bearing  

NASA Astrophysics Data System (ADS)

As with large scale engines, the MIT microfabricated gas turbine engine requires high speed rotating components to achieve useful levels of power density and efficiency. The gas bearing flows in this microengine have much larger Mach and Reynolds numbers than conventional scale gas bearing flows. Due to microfabrication constraints, the aspect ratio of this bearing also differs significantly from the common design space. A microfabricated test device has been designed and fabricated to study gas lubricated bearings on the microscale. The bearing test device consists of a bonded stack of five silicon wafers. A 4 mm diameter, 450 ?m thick rotor is captured within the device. The rotor is driven by an air turbine. Hydrostatic thrust bearings support the rotor axially; a coupled hydrostatic/hydrodynamic journal bearing supports the rotor radially. A rotation rate of 500,000 rpm has been achieved in initial tests. Results from operation of this microbearing test device will be presented.

Jacobson, S. A.; Ehrich, F. F.; Fréchette, L. G.; Lin, C. C.; Breuer, K. S.

1999-11-01

68

Marshall Space Flight Center High Speed Turbopump Bearing Test Rig  

NASA Technical Reports Server (NTRS)

The Marshall Space Flight Center has a unique test rig that is used to test and develop rolling element bearings used in high-speed cryogenic turbopumps. The tester is unique in that it uses liquid hydrogen as the coolant for the bearings. This test rig can simulate speeds and loads experienced in the Space Shuttle Main Engine turbopumps. With internal modifications, the tester can be used for evaluating fluid film, hydrostatic, and foil bearing designs. At the present time, the test rig is configured to run two ball bearings or a ball and roller bearing, both with a hydrostatic bearing. The rig is being used to evaluate the lifetimes of hybrid bearings with silicon nitride rolling elements and steel races.

Gibson, Howard; Moore, Chip; Thom, Robert

2000-01-01

69

Polar Bears  

NSDL National Science Digital Library

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

Mr. Thomas

2010-09-27

70

Micro gas bearings fabricated by deep X-ray lithography D. Kim, S. Lee, Y. Jin, Y. Desta, M. D. Bryant, J. Goettert  

E-print Network

] demonstrated an electrostatic induction motor supported by externally pressurized hydrostatic gas bearingsMicro gas bearings fabricated by deep X-ray lithography D. Kim, S. Lee, Y. Jin, Y. Desta, M. D, frictionless bearings are needed, and in practice, micro gas bearings approach the ideal. Typically, bearings

Bryant, Michael D.

71

Bearing system  

DOEpatents

A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

Kapich, Davorin D. (Carlsbad, CA)

1987-01-01

72

Thermohydrodynamic analysis of cryogenic liquid turbulent flow fluid film bearings  

NASA Technical Reports Server (NTRS)

A thermohydrodynamic analysis is presented and a computer code developed for prediction of the static and dynamic force response of hydrostatic journal bearings (HJB's), annular seals or damper bearing seals, and fixed arc pad bearings for cryogenic liquid applications. The study includes the most important flow characteristics found in cryogenic fluid film bearings such as flow turbulence, fluid inertia, liquid compressibility and thermal effects. The analysis and computational model devised allow the determination of the flow field in cryogenic fluid film bearings along with the dynamic force coefficients for rotor-bearing stability analysis.

Andres, Luis San

1993-01-01

73

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

74

Polar Bear Polar Bear  

NSDL National Science Digital Library

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

Kelly Burgess

2012-09-11

75

Bear Scratch  

USGS Multimedia Gallery

When looking for a place to set up a trapping location, scientists look for existing bear sign such as scratches on trees and bear scat. Sometimes traps are set in areas that have no obvious bear sign to determine if indeed bears are present....

76

Demagnetization of terrestrial and extraterrestrial rocks under hydrostatic pressure up to 1.2 GPa  

NASA Astrophysics Data System (ADS)

We carried out hydrostatic pressure demagnetization experiments up to 1.24 GPa on samples of terrestrial and extraterrestrial rocks and minerals of different lithologies as well as on synthetic samples. The magnetic remanence of samples was measured directly under pressure using a non-magnetic high-pressure cell of piston-cylinder type that was inserted into a high sensitivity SQUID magnetometer. In order to bring light on the pressure demagnetization effect, we investigated 50 samples with different magnetic mineralogies, remanent coercivities ( Bcr) and hysteresis parameters. The samples consisted of pyrrhotite-, magnetite- and titanomagnetite-bearing Martian meteorites, taenite-, tetrataenite- and kamacite-bearing ordinary chondrites and pyrrhotite-bearing Rumuruti chondrite; magnetite- and titanomagnetite-bearing basalts, andesites, ignimbrites, obsidians and granites; a variety of pyrrhotite- and hematite-bearing rocks and minerals (jasper, schist, rhyolite, radiolarite); samples of goethite and greigite as well as synthetic samples of dispersed powders of magnetite, hematite, pyrrhotite and native iron set into epoxy resin. Under hydrostatic pressure of 1.24 GPa, applied in a low magnetic field (<5 ?T), the samples lost up to 84% of their initial saturation isothermal remanent magnetization (SIRM) without any changes in their intrinsic magnetic properties. We found that the efficiency of the pressure demagnetization is not exclusively controlled by the magnetic hardness of the samples ( Bcr), but that it is strongly dependent on their magnetic mineralogy. For a given magnetic mineralogy the resistance to hydrostatic pressure is roughly proportional to ln( Bcr). It was shown that there is no simple equivalence between pressure demagnetization and alternating field demagnetization effects. The pressure demagnetization was shown to be time-independent but repeated application of the same pressure level resulted in further demagnetization.

Bezaeva, Natalia S.; Gattacceca, Jérôme; Rochette, Pierre; Sadykov, Ravil A.; Trukhin, Vladimir I.

2010-03-01

77

Failure strength of the bovine caudal disc under internal hydrostatic pressure.  

PubMed

The structure of the disc is both complex and inhomogeneous, and it functions as a successful load-bearing organ by virtue of the integration of its various structural regions. These same features also render it impossible to assess the failure strength of the disc from isolated tissue samples, which at best can only yield material properties. This study investigated the intrinsic failure strength of the intact bovine caudal disc under a simple mode of internal hydrostatic pressure. Using a hydraulic actuator, coloured hydrogel was injected under monitored pressure into the nucleus through a hollow screw insert which passed longitudinally through one of the attached vertebrae. Failure did not involve vertebra/endplate structures. Rather, failure of the disc annulus was indicated by the simultaneous manifestation of a sudden loss of gel pressure, a flood of gel colouration appearing in the outer annulus and audible fibrous tearing. A mean hydrostatic failure pressure of 18+/-3 MPa was observed which was approximated as a thick-wall hoop stress of 45+/-7 MPa. The experiment provides a measurement of the intrinsic strength of the disc using a method of internal hydrostatic loading which avoids any disruption of the complex architecture of the annular wall. Although the disc in vivo is subjected to a much more complex pattern of loading than is achieved using simple hydrostatic pressurization, this latter mode provides a useful tool for investigating alterations in intrinsic disc strength associated with prior loading history or degeneration. PMID:15964006

Schechtman, Helio; Robertson, Peter A; Broom, Neil D

2006-01-01

78

Polar Bear  

NSDL National Science Digital Library

This site from the World Wildlife Fund (WWF) International provides general information about polar bears as well as data on the movements of two radio-collared bears, along with the ice status, through a series of online maps.

2007-01-01

79

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

SciTech Connect

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

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

2014-04-28

80

Coal-fired Stirling engine hydrostatic locomotive  

SciTech Connect

In view of the increasing price of diesel oil, there is a need to consider alternative fuels, such as coal, which is available in relative abundance and lower costs. A case is made to establish a 1000 hp 80 ton 2 bogie 4-axle coal-burning free-piston Stirling engine hydrostatic locomotive for shunting duty.

Srinivasan, V.; Walker, C.; Fauvel, R.

1982-01-01

81

Hydrostatic transmission development for wave energy converters  

Microsoft Academic Search

innovative approach for electric power conversion from the vast ocean wave energy. Here, a floating-buoy wave energy converter (WEC) using hydrostatic transmission (HST), which is shortened as HSTWEC, is proposed and designed to enhance the wave energy generation task during wave fluctuations. In this HSTWEC structure, the power take-off system (PTO) is a combination of the designed HST circuit and

Hoang Huu Tien; Dinh Quang Truong; Kyoung Kwan Ahn

2011-01-01

82

Food Processing by High Hydrostatic Pressure  

Microsoft Academic Search

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

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

2002-01-01

83

High hydrostatic pressure effects on Spirostomum ambiguum  

Microsoft Academic Search

The effects of hydrostatic pressure on the ciliateSpirostomum ambiguum, when the organism is uncalcified in the early stage of culture and when it is calcified after periods of time are described. Uncalcified cells are sensitive to pressure, becoming quiescent at 250 atm, distorting at 300 atm and disrupting at 550 atm. In contrast, the mature calcified animals show no changes

Saul M. Bien

1967-01-01

84

Railcar waste transfer system hydrostatic test report  

SciTech Connect

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

Ellingson, S.D.

1997-04-03

85

46 CFR 61.30-10 - Hydrostatic test.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

86

46 CFR 61.30-10 - Hydrostatic test.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

87

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

E-print Network

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

Wilde, Deborah Anne

2002-01-01

88

A Multipurpose Device for Some Hydrostatics Questions  

ERIC Educational Resources Information Center

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

Ganci, Salvatore

2008-01-01

89

Polar Bear  

USGS Publications Warehouse

Polar bears are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.

Amstrup, S.D.; DeMaster

1988-01-01

90

Magnetic Bearing  

NASA Technical Reports Server (NTRS)

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

1996-01-01

91

Polar Bear  

NSDL National Science Digital Library

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

2009-01-01

92

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

93

Improving hydrostatic performance of 1-3 piezocomposites  

Microsoft Academic Search

Type 1-3 piezocomposites consist of aligned piezoelectric rods embedded in a passive polymer matrix and have better hydrostatic behavior than single-phase piezoelectric materials. The improved hydrostatic performance of 1-3 piezocomposites comes from two major effects: the axial stress amplification and the lateral stress reduction in the piezoelectric rods. An improved micromechanical model has been developed to predict the hydrostatic response

L. Li; N. R. Sottos

1995-01-01

94

Bobbie Bear  

NSDL National Science Digital Library

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

Illuminations National Council of Teachers of Mathematics

2009-03-06

95

Foil bearings  

NASA Technical Reports Server (NTRS)

The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

Elrod, David A.

1993-01-01

96

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

97

Hydrostatic compression in glycerinated rabbit muscle fibers.  

PubMed Central

Glycerinated muscle fibers isolated from rabbit psoas muscle, and a number of other nonmuscle elastic fibers including glass, rubber, and collagen, were exposed to hydrostatic pressures of up to 10 MPa (100 Atm) to determine the pressure sensitivity of their isometric tension. The isometric tension of muscle fibers in the relaxed state (passive tension) was insensitive to increased pressure, whereas the muscle fiber tension in rigor state increased linearly with pressure. The tension of all other fiber types (except rubber) also increased with pressure; the rubber tension was pressure insensitive. The pressure sensitivity of rigor tension was 2.3 kN/m2/MPa and, in comparison with force/extension relation determined at atmospheric pressure, the hydrostatic compression in rigor muscle fibers was estimated to be 0.03% Lo/MPa. As reported previously, the active muscle fiber tension is depressed by increased pressure. The possible underlying basis of the different pressure-dependent tension behavior in relaxed, rigor, and active muscle is discussed. PMID:2275960

Ranatunga, K W; Fortune, N S; Geeves, M A

1990-01-01

98

Mechanical design problems associated with turbopump fluid film bearings  

NASA Technical Reports Server (NTRS)

Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.

Evces, Charles R.

1990-01-01

99

Cave Bear  

NSDL National Science Digital Library

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

American Association for the Advancement of Science (; )

2005-08-15

100

The hydrostatic stiffness of flexible floating structures for linear hydroelasticity  

Microsoft Academic Search

The formulation of the hydrostatic stiffness for linear rigid body hydrodynamics is well known. An explicit formulation for an analogous hydrostatic stiffness in linear hydroelasticity, which is applicable to both rigid body and flexible displacement, is not as well-known. Three such formulations have been proposed previously in the literature, none of which is quite correct; all produce an unsymmetric stiffness

L. L. Huang; H. R. Riggs

2000-01-01

101

75 FR 48728 - The Hydrostatic Testing Provision of the Portable Fire Extinguishers Standard; Extension of the...  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-08-11

102

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-11-25

103

Extreme events in solutions of hydrostatic and non-hydrostatic climate models.  

PubMed

Initially, this paper reviews the mathematical issues surrounding hydrostatic primitive equations (HPEs) and non-hydrostatic primitive equations (NPEs) that have been used extensively in numerical weather prediction and climate modelling. A new impetus has been provided by a recent proof of the existence and uniqueness of solutions of viscous HPEs on a cylinder with Neumann-like boundary conditions on the top and bottom. In contrast, the regularity of solutions of NPEs remains an open question. With this HPE regularity result in mind, the second issue examined in this paper is whether extreme events are allowed to arise spontaneously in their solutions. Such events could include, for example, the sudden appearance and disappearance of locally intense fronts that do not involve deep convection. Analytical methods are used to show that for viscous HPEs, the creation of small-scale structures is allowed locally in space and time at sizes that scale inversely with the Reynolds number. PMID:21320911

Gibbon, J D; Holm, D D

2011-03-28

104

Infrared spectroscopy of biphenyl under hydrostatic pressure  

NASA Astrophysics Data System (ADS)

Changes in the conformations of conjugated molecules affect the optical and electronic properties significantly. Hydrostatic pressure has been used to probe the conformations of biphenyl (C12H10) and deuterated biphenyl (C12D10) at liquid-helium temperatures. Infrared (IR) spectra of these materials have been taken up to a pressure of 2 GPa. A disappearance of certain IR absorption peaks has been found to occur between 0.07 and 0.45 GPa, due to the phase transition from a twisted to a planar conformation. Numerical simulations together with group-theoretical analysis have been performed to identify the nature of the vibrational modes that lose IR activity upon planarization.

Zhuravlev, K. K.; McCluskey, M. D.

2002-08-01

105

Hydrostatic meniscus between two eccentric circular cylinders.  

PubMed

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

Pozrikidis, C

2010-09-01

106

Bearing monitoring  

Microsoft Academic Search

At Ford Motor Company, thrust bearing in drill motors is often damaged by metal chips. Since the vibration frequency is several Hz only, it is very difficult to use accelerometers to pick up the vibration signals. Under the support of Ford and NASA, we propose to use a piezo film as a sensor to pick up the slow vibrations of

Roger Xu; Mark W. Stevenson; Chiman Kwan; Leonard S. Haynes

2001-01-01

107

Bear Bones  

NSDL National Science Digital Library

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

Science Update

2004-03-08

108

Hydrostatic Stress Effect On the Yield Behavior of Inconel 100  

NASA Technical Reports Server (NTRS)

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

Allen, Phillip A.; Wilson, Christopher D.

2002-01-01

109

Tooling Converts Stock Bearings To Custom Bearings  

NASA Technical Reports Server (NTRS)

Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.

Fleenor, E. N., Jr.

1983-01-01

110

Advances In Magnetic Bearings  

NASA Technical Reports Server (NTRS)

NASA technical memorandum reviews state of technology of magnetic bearings, focusing mainly on attractive bearings rather than repulsive, eddy-current, or Lorentz bearings. Attractive bearings offer greater load capacities and preferred for aerospace machinery.

Fleming, David P.

1994-01-01

111

Hydrostatic Hamiltonian particle-mesh (HPM) methods for atmospheric modeling.  

E-print Network

10, D-14469 Potsdam, Germany CWI, P.O. Box 94079, 1090 GB Amsterdam, the Netherlands 1 #12;such Sebastian Reich Jason Frank August 19, 2011 Abstract We develop a hydrostatic Hamiltonian particle-mesh (HPM

Reich, Sebastian

112

Designing a high-efficiency hydrostatic bicycle transmission  

E-print Network

Hydrostatic bicycle drives use a working fluid instead of the common roller-chain to transmit power to the drive wheel. These transmissions are typically considered too inefficient for human power applications. An experiment ...

Socks, Matthew T. (Matthew Tristram)

2006-01-01

113

Hydrostatic pressure-regulated ion transport in bladder uroepithelium  

E-print Network

Bridges, and Gerard Apodaca. Hydrostatic pressure-regulated ion transport in bladder uroepithelium. Am J-Myung Lee,1 John P. Johnson,1 Thomas R. Kleyman,1,2 Robert Bridges,2 and Gerard Apodaca1,2 1 Renal

Apodaca, Gerard

114

Effects of magnetic field and hydrostatic pressure on martensitic transformation  

Microsoft Academic Search

Effects of magnetic field and hydrostatic pressure on martensitic transformations in some ferrous and nonferrous alloys have\\u000a been studied. The studies clarified the effects of magnetic field and hydrostatic pressure on martensitic transformation start\\u000a temperature, magnetoelastic martensitic transformation, morphology of martensites and transformation kinetics of athermal\\u000a and isothermal transformations. That is, transformation start temperatures of all the ferrous alloys examined

Tomoyuki Kakeshita; Toshio Saburi

1997-01-01

115

Characterization and measurement of hybrid gas journal bearings  

NASA Astrophysics Data System (ADS)

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

Lawrence, Tom Marquis

116

Hydrostatic Pressure Influences HIF-2 Alpha Expression in Chondrocytes  

PubMed Central

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

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

2015-01-01

117

Cryogenic turbopump bearing materials  

NASA Technical Reports Server (NTRS)

Materials used for modern cryogenic turbopump bearings must withstand extreme conditions of loads and speeds under marginal lubrication. Naturally, these extreme conditions tend to limit the bearing life. It is possible to significantly improve the life of these bearings, however, by improving the fatigue and wear resistance of bearing alloys, and improving the strength, liquid oxygen compatibility and lubricating ability of the bearing cage materials. Improved cooling will also help to keep the bearing temperatures low and hence prolong the bearing life.

Bhat, Biliyar N.

1989-01-01

118

Magnetic bearings for free-piston Stirling engines  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

119

Magnetic bearings for free-piston Stirling engines  

NASA Astrophysics Data System (ADS)

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

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

1992-08-01

120

Magnetic bearings for free-piston Stirling engines  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

121

An In-Vitro Traumatic Model To Evaluate the Response of Myelinated Cultures to Sustained Hydrostatic Compression Injury  

PubMed Central

Abstract While a variety of in-vitro models have been employed to investigate the response of load-bearing tissues to hydrostatic pressure, long-term studies are limited by the need to provide for adequate gas exchange during pressurization. Applying compression in vitro may alter the equilibrium of the system and thereby disrupt the gas exchange kinetics. To address this, several sophisticated compression chamber designs have been developed. However, these systems are limited in the magnitude of pressure that can be applied and may require frequent media changes, thereby eliminating critical autocrine and paracrine signaling factors. To better isolate the cellular response to long-term compression, we created a model that features continuous gas flow through the chamber during pressurization, and a negative feedback control system to rigorously control dissolved oxygen levels. Monitoring dissolved oxygen continuously during pressurization, we find that the ensuing response exhibits characteristics of a second- or higher-order system which can be mathematically modeled using a second-order differential equation. Finally, we use the system to model chronic nerve compression injuries, such as carpal tunnel syndrome and spinal nerve root stenosis, with myelinated neuron-Schwann cell co-cultures. Cell membrane integrity assay results show that co-cultures respond differently to hydrostatic pressure, depending on the magnitude and duration of stimulation. In addition, we find that myelinated Schwann cells proliferate in response to applied hydrostatic compression. PMID:19645529

Frieboes, Laura R.

2009-01-01

122

Deep Levels in Semiconductors Under Hydrostatic Pressure  

NASA Astrophysics Data System (ADS)

Photoluminescence (PL) studies of deep and shallow donor levels in bulk Al_{0.3} Ga_{0.7}As and GaAs-Al_{0.3}Ga _{0.7}As(40A/80A) multiple quantum wells (MQW) under hydrostatic pressure are presented in the pressure range from 0 to 70kbar and temperatures from 15 to 125^circK. The samples used were grown by molecular beam epitaxy (MBE) on a GaAs substrate, where the PL was excited using principally 5145A radiation from an Ar^+ laser. A new trap center is reported for the first time in both bulk Al_{0.3}Ga _{0.7}As and GaAs-Al _{0.3}Ga_{0.7 }As(40A/80A) MQW. This center forms an efficient electron trap, and produces a pressure induced hysteresis in the PL intensity. A large lattice relaxation model is implied by the strong pressure induced hysteresis. The energy of the center is higher than that of the X conduction band (CB) at ambient pressures, and it is neither the DX nor the shallow donor (SD) centers. The center has an unusually high emission barrier E_{ rm e} > 26meV, much larger than the DX or SD centers. A new characteristic of this center is observed at 15 and 40^circK in the MQW, where the BE^{rm X} is seen to channel to the FE^ {rm X} at ~ 40kbar, and recovery of the BE^{rm X} is not observed upon cycling the pressure. Pressure coefficients for levels associated with the Gamma and X-CB's from both samples are reported. Activation energies (E_{ rm a}) from Arrhenius plots of the temperature dependence of the PL from bulk Al_{0.3 }Ga_{0.7}As is discussed along with proposed scattering mechanisms and an energy level diagram for both shallow and deep donor states at selected pressures between 0 to 44kbar. Broadening of the E_sp{1{rm h} }{Gamma} in the MQW sample is observed below and above the Gamma -X crossover. Below crossover, broadening is attributed to many body effects related to heavily doped MQW's. Above the crossover, mixing of the Gamma and X states causes asymmetric and broadened Fano lineshapes.

Roach, William Patrick

123

Hydrostatic Water Level Systems At Homestake DUSEL  

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

124

Hydrostatic Microextrusion of Steel and Copper  

SciTech Connect

The paper presents an experimental investigation based on hydrostatic micro extrusion of billets in low carbon steel and commercially pure copper, and the relevant results. The starting billets have a diameter of 0.3 mm and are 5 mm long; a high pressure generator consisting of a manually operated piston screw pump is used to pressurize the fluid up to 4200 bar, the screw pump is connected through a 3-way distribution block to the extrusion die and to a strain gauge high pressure sensor. The sensor has a full scale of 5000 bar and the extrusion pressure is acquired at a sampling rate of 2 kHz by means of an acquisition program written in the LabVIEW environment. Tests have been conducted at room temperature and a lubricant for wire drawing (Chemetall Gardolube DO 338) acts both as the pressurizing fluid and lubricant too. In addition, billets were graphite coated. Different fluid pressures and process durations have been adopted, resulting in different extrusion lengths. The required extrusion pressure is much higher than in non-micro forming operations (this effect is more evident for steel). On the cross section of the extruded parts, hardness and grain size distribution have been measured, the former through Vickers micro hardness (10 g load) tests. In the case of the extrusion of copper, the material behaves as in microdrawing process. In the case of the extrusion of steel, the hardness increases from the core to the surface as in the drawing process, but with lower values. The analysis evidenced the presence of the external layer, but its thickness is about 1/3 of the external layer in the drawn wire and the grains appear smaller than in the layer of the drawn wire. The extruding force required along the extruding direction is higher (22-24 N) than the drawing force along the same direction (12 N): being the material, the reduction ratio, the die sliding length the same in both cases, the higher extrusion force should be caused by a higher tangential friction force and/or a higher redundant work of deformation and/or a different material behaviour. Which is the real mechanism is not clear at present, but surface layer grains in extrusion are more deformed than in wire drawing. For this reason the deformation inhomogeneity increases in extrusion and the material under the highly deformed surface layer should be subjected to lower strains, strain hardening and finally resulting in lower hardness.

Berti, Guido; Monti, Manuel [University of Padua, DTG, Stradella San Nicola 3, I-36100 Vicenza (Italy); D'Angelo, Luciano [University of Ferrara, Dept. of Engineering, via Saragat 3, 44100 Ferrara (Italy)

2011-05-04

125

Hydrostatic Stress Effect on the Yield Behavior of Inconel 100  

NASA Technical Reports Server (NTRS)

Classical metal plasticity theory assumes that hydrostatic stress has negligible effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of various geometries. Fatigue tests and nonlinear finite element analyses (FEA) of Inconel 100 (IN100) equal-arm bend specimens and new monotonic tests and nonlinear finite element analyses of IN100 smooth tension, smooth compression, and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions were performed. A new FEA constitutive model was developed that incorporates a pressure-dependent yield function with combined multilinear kinematic and multilinear isotropic hardening using the ABAQUS user subroutine (UMAT) utility. In all monotonic tensile test cases, the von Mises constitutive model, overestimated the load for a given displacement or strain. Considering the failure displacements or strains for the DENT specimen, the Drucker-Prager FEM s predicted loads that were approximately 3% lower than the von Mises values. For the failure loads, the Drucker Prager FEM s predicted strains that were up to 35% greater than the von Mises values. Both the Drucker-Prager model and the von Mises model performed equally-well in simulating the equal-arm bend fatigue test.

Allen, Phillip A.; Wilson, Christopher D.

2003-01-01

126

Optimal Synchronizability of Bearings  

E-print Network

Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with ...

Seybold, Hansjorg

127

A hydrostatic stress-dependent anisotropic model of viscoplasticity  

NASA Technical Reports Server (NTRS)

A hydrostatic stress-dependent, anisotropic model of viscoplasticity is formulated as an extension of Bodner's model. This represents a further extension of the isotropic Bodner model over that made to anisotropy by Robinson and MitiKavuma. Account is made of the inelastic deformation that can occur in metallic composites under hydrostatic stress. A procedure for determining the material parameters is identified that is virtually identical to the established characterization procedure for the original Bodner model. Characterization can be achieved using longitudinal/transverse tensile and shear tests and hydrostatic stress tests; alternatively, four off-axis tensile tests can be used. Conditions for a yield stress minimum under off-axis tension are discussed. The model is applied to a W/Cu composite; characterization is made using off-axis tensile data generated at NASA Lewis Research Center (LeRC).

Robinson, D. N.; Tao, Q.; Verrilli, M. J.

1994-01-01

128

Liquid crystalline fiber optic colorimeter for hydrostatic pressure measurement  

NASA Astrophysics Data System (ADS)

This paper presents results of tests performed on a fiber optic system of liquid crystalline transducer for hydrostatic pressure monitoring based on properties of colorimetry. The system employs pressure-induced deformations occurring in liquid crystalline (LC) cells configured in a homogeneous Frederiks geometry. The sensor is compared of a round LC cell placed inside a specially designed pressure chamber. As a light source we used a typical diode operating at red wavelength and modulated using standard techniques. The pressure transducer was connected to a computer with a specially designed interface built on the bas of advanced ADAM modules. Results indicate that the system offers high response to pressure with reduced temperature sensitivity and, depending on the LC cell used, can be adjusted for monitoring of low hydrostatic pressures up to 6 MPa. These studies have demonstrated the feasibility of fiber optic liquid crystal colorimeter for hydrostatic pressure sensing specially dedicated to pipe- lines, mining instrumentation, and process-control technologies.

Wolinski, Tomasz R.; Bajdecki, Waldemar K.; Domanski, Andrzej W.; Karpierz, Miroslaw A.; Konopka, Witold; Nasilowski, T.; Sierakowski, Marek W.; Swillo, Marcin; Dabrowski, Roman S.; Nowinowski-Kruszelnicki, Edward; Wasowski, Janusz

2001-08-01

129

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

130

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

E-print Network

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

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

2005-01-01

131

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

NASA Astrophysics Data System (ADS)

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

Campbell, Marvin F.

2014-07-01

132

Accurate pressure gradient calculations in hydrostatic atmospheric models  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

133

Pairwise association of neopentane as a function of hydrostatic pressure  

NASA Astrophysics Data System (ADS)

It is shown that the contact-minimum configuration of two neopentane molecules is favoured on increasing hydrostatic pressure over the range 1-4000 atm, at room temperature, in line with the methane results (Graziano, 2014). This is due to the decrease in water accessible surface area accompanying the association, that leads to a gain in configurational/translational entropy of water molecules, whose magnitude increases with hydrostatic pressure. Of course, the strengthening of pairwise hydrophobic interaction cannot shed light on the pressure-induced denaturation of globular proteins.

Graziano, Giuseppe

2014-11-01

134

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

135

Design and fabrication of gas bearings for Brayton cycle rotating unit  

NASA Technical Reports Server (NTRS)

Analysis, design, and testing of two types of pivoted pad journal bearings and a spiral-grooved thrust bearing suitable for direct installation into the NASA 2 to 15 KW Brayton Cycle Rotating Unit (BRU) have been accomplished. Both types of tilting pad bearing assemblies are of the preloaded type, consisting of three pads with one pad flexibly mounted. One type utilizes a non-conforming pivot, while the other replaces the conventional spherical pivot with a cruciform flexible member. The thrust bearing is flexure mounted to accommodate static machine mislinement. Test results indicate that both types of journal bearings should satisfy the requirements imposed by the BRU. Hydrostatic tests of the spiral-grooved thrust bearing showed it to be free of pneumatic hammer with as many as 24 orifices over the BRU pressure and load range.

Frost, A.; Tessarzik, J. M.; Arwas, E. B.; Waldron, W. D. (editor)

1973-01-01

136

Bearings for Your Whirligig  

NSDL National Science Digital Library

Experiment with friction and make bearings for a whirligig! This activity is a nice introduction to friction and bearings and demonstrates why bearings are useful for spinning. A related video show Vollis Simpson, an artist who creates kinetic sculptures and whirligigs, explain how he uses bearings in all of his spinning pieces so that they move smoothly.

Science Musuem of Minnesota

1995-01-01

137

Passive magnetic bearing configurations  

DOEpatents

A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

Post, Richard F. (Walnut Creek, CA)

2011-01-25

138

Getting Your Bearings  

NSDL National Science Digital Library

In this activity, learners explore the concept of friction and how ball bearings reduce friction. Learners investigate different uses for ball bearings, how the design has changed over time to incorporate roller bearings, test friction using marbles, and identify the use of ball bearings in everyday items.

IEEE

2013-08-30

139

Theory versus experimental results and comparisons for five orifice-compensated hybrid bearing configurations  

E-print Network

supply pressures enhance the hydrostatic centering efl'ect of 42 200 Baseline Bearing z Q 150 M K g 100 Q CG 50 Supply Pressure: 7. 0 MPa Speed: 24, 600 CPM 0. 0 0. 1 0. 2 0. 3 0. 4 0. 5 Eccentricity Ratio Fig. 19. Baseline Bearing Direct... for Five Orifice-Compensated Hybrid Bearing Configurations. (December 1992) Nancy Marie Franchek, B. S. , Texas AlkM University Chair of Advisory Committee: Dr. Dara Childs In many high-speed rotordynamic applications, hardware such as seals...

Franchek, Nancy Marie

1992-01-01

140

Comparison of hydrostatic and hydrodynamic pressure to inactivate foodborne viruses  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effect of high hydrostatic pressure (HPP) and hydrodynamic pressure (HDP), in combination with chemical treatments, was evaluated for inactivation of foodborne viruses and non-pathogenic surrogates in a pork sausage product. Sausages were immersed in water, 100 ppm EDTA, or 2 percent lactoferrin...

141

Hydrostatic Hamiltonian particle mesh (HPM) methods for atmospheric modeling.  

E-print Network

Sebastian Reich Jason Frank March 17, 2011 Abstract We develop a hydrostatic Hamiltonian particle mesh (HPM such as Universit¨at Potsdam, Institut f¨ur Mathematik, Am Neuen Palais 10, D-14469 Potsdam, Germany CWI, P.O. Box

Frank, Jason

142

Calculation of PETN molecular crystal vibrational frequencies under hydrostatic pressure  

NASA Astrophysics Data System (ADS)

First-principles calculations of the effects of hydrostatic pressure on pentaerythritol tetranitrate (PETN) are performed using the all-electron CRYSTAL03 program. The procedure for applying hydrostatic pressure by performing a series of volumetric changes coincident with lattice constant and internal coordinate optimization using various scripts and support programs is described. Once the optimized internal coordinates and lattice constants have been obtained for a given hydrostatic pressure, a separate algorithm consisting of additional scripts and programs is employed for performing a complete normal-mode analysis, with analytic first derivatives and numeric second derivatives of the total energy. The eigenvalues obtained provide the vibrational frequencies and the eigenvectors are used for mode identification. The role of the Gaussian basis sets chosen and the exchange-correlation potential used is discussed. The vibrational frequencies obtained at ambient pressure are shown to compare well with experiment and gas-phase calculations. The shift of the vibrational frequencies under hydrostatic pressure is compared with experiment.

Perger, Warren; Zhao, Jijun

2005-03-01

143

Wind resource assessment with a mesoscale non-hydrostatic model  

E-print Network

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

Boyer, Edmond

144

Ab initio calculation of hydrostatic absolute deformation potential of semiconductors  

E-print Network

an approach to calculate the hydrostatic ADP of Si, GaAs, and ZnSe using an ab initio all-electron method in heterostructure quantum wells and nanocrystals;11­13 thus, it is crucial to have a reliable method to obtain on the wavefunction characters of the energy levels.3 It is now well accepted that the difference of the volume

Gong, Xingao

145

A Correction in Viscometry due to Varying Hydrostatic Head  

Microsoft Academic Search

The varying hydrostatic head in viscometers gives rise to a correction to the viscosity if the latter is calculated from the applied pressure only. This has been worked out in general and the special cases of viscometers with cylindrical and biconical bulbs and cylindrical bulbs with conical ends have been considered in detail.

J E Caffyn

1948-01-01

146

High Hydrostatic Pressure Processing of Fruit and Vegetable Products  

Microsoft Academic Search

High hydrostatic pressure (HHP) as a minimal thermal technology is a valuable tool for microbiologically safe and shelf-stable fruit and vegetable production. Microorganisms and deteriorative enzymes can be inhibited or inactivated depending on the amount of pressure and time applied to the product. The resistance of microorganisms and enzymes to pressure in fruit and vegetable products also is dependent on

José A. Guerrero-Beltrán; Gustavo V. Barbosa-Cánovas; Barry G. Swanson

2005-01-01

147

Modification of whey protein concentrate hydrophobicity by high hydrostatic pressure  

Microsoft Academic Search

The objective of this study was to evaluate the influence of high hydrostatic pressure (HHP) treatments on hydrophobicity of whey protein concentrate (WPC). An increase in binding affinity or decrease in apparent dissociation constant indicates increased hydrophobicity, which is positively correlated with functional properties. The effects of HHP treatment (600 MPa, 50 °C, 0 to 30 min) on intrinsic fluorescence

Xiaoming Liu; Joseph R. Powers; Barry G. Swanson; Herbet H. Hill; Stephanie Clark

2005-01-01

148

Responses of Mytilus edulis Larvæ to Increases in Hydrostatic Pressure  

Microsoft Academic Search

Knight-Jones and Qasim1 have reported that a number of marine planktonic animals are sensitive to small changes in hydrostatic pressure. These animals included crustacean and polychæte larvæ, which tended to become more active and swim upwards when submitted to increased pressures. The value of such a response to a planktonic organism of high specific gravity must be very great.

B. L. Bayne

1963-01-01

149

Punching Tests on Disks of Rock Under Hydrostatic Pressure  

Microsoft Academic Search

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

J. C. Jaeger

1962-01-01

150

SENSORY PROFILE OF PINEAPPLE JUICE PROCESSED BY HIGH HYDROSTATIC PRESSURE  

Microsoft Academic Search

Heat leads to quality changes in sensory and nutritional characteristics of foods. High hydrostatic pressure is being investigated, as a processing that may destroy undesired microorganisms, while preserving sensory and nutritional characteristics. One of the most promising segments in Brazil is fruit juice, and evaluating its sensory profile is a valuable tool to improve the juice quality. The objective of

Aline M. de Barros; Rosires Deliza; Lúcia H. E. S. Laboissière; Amauri Rosenthal; Helena M. A. Bolini

151

Feedback linearization PID control for electro-hydrostatic actuator  

Microsoft Academic Search

To solve the problem induced by serious nonlinear characteristic of the electro-hydrostatic actuator (EHA), and realize exact control of EHA, the mathematical model of EHA was derived, an exact linearization control law was obtained via nonlinear coordinate transformation and state feedback. The complicated nonlinear object was transformed into a simple linear system using the feedback linearization control strategy. Furthermore, the

Qian Zhang; Bingqiang Li

2011-01-01

152

Technology and equipment for hydrostatic treatment of materials  

Microsoft Academic Search

The main requirements of the quality of products are the homogeneity of technological and service properties, the improved characteristics of strength and plasticity, endurance and brittle failure resistance. In recent years many investigations into developing the High Hydrostatic Pressure Technologies (HHPT) and equipment to meet these requirements have been carried out by scientific schools of Academicians, L. F. Vereshchagin, G.

B. I. Beresnev; V. G. Synkov

1989-01-01

153

Cryogenic foil bearing turbopumps  

NASA Technical Reports Server (NTRS)

Cryogenic foil bearing turbopumps offer high reliability and low cost. The fundamental cryogenic foil bearing technology has been validated in both liquid hydrogen and liquid oxygen. High load capacity, excellent rotor dynamics, and negligible bearing wear after over 100 starts and stops, and over many hours of testing, were observed in both fluids. An experimental liquid hydrogen foil bearing turbopump was also successfully demonstrated. The results indicate excellent stability, high reliability, wide throttle-ability, low bearing cooling flow, and two-phase bearing operability. A liquid oxygen foil bearing turbopump has been built and is being tested at NASA MSFC.

Gu, Alston L.

1993-01-01

154

Rolling-Element Bearings  

NASA Technical Reports Server (NTRS)

Rolling element bearings are a precision, yet simple, machine element of great utility. A brief history of rolling element bearings is reviewed and the type of rolling element bearings, their geometry and kinematics, as well as the materials they are made from and the manufacturing processes they involve are described. Unloaded and unlubricated rolling element bearings, loaded but unlubricated rolling element bearings and loaded and lubricated rolling element bearings are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element bearings.

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

1983-01-01

155

Introduction to ball bearings  

NASA Technical Reports Server (NTRS)

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

Hamrock, B. J.; Dowson, D.

1981-01-01

156

High efficiency magnetic bearings  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

157

Fatigue of specimens subjected to combined loading. Role of hydrostatic pressure  

Microsoft Academic Search

Tests have been carried out on smooth and notched specimens submitted to cyclic combined loading. The role of the hydrostatic pressure has been clarified using a volumetric approach. The average hydrostatic pressure and the shear stress have been computed in the fatigue process volume. An elliptical dependence between the effective shear stress and the hydrostatic pressure has been shown.

G Qilafku; N Kadi; J Dobranski; Z Azari; M Gjonaj; G Pluvinage

2001-01-01

158

Thickness dependence of hydrostatic piezoelectric properties of 1–3 piezoelectric composites  

Microsoft Academic Search

Thickness dependence of hydrostatic piezoelectric properties of 1–3 piezoelectric composites was studied. PZT rods with square cross section were used as piezoelectric active components. Epoxy resin was used as matrix. The volume fraction of piezoelectric ceramic was about 25%. The hydrostatic piezoelectric properties dh, gh and hydrostatic figure of merit dh gh are all dependent on the ratio of width

Li Denghua; Yao Xi

1999-01-01

159

Optimization of hydrodynamic and hydrostatic steering control system based on GA-PID  

Microsoft Academic Search

As the tracked vehicles often run in harsh environments, a certain type of tracked vehicles with hydrodynamic and hydrostatic steering mechanism often have a big pressure fluctuation in the hydrostatic system in the steering process and the steering properties are seriously affected. In order to smoothly match the hydrodynamic and hydrostatic steering mechanism, we implemented the electro-hydraulic proportional valves instead

Taotao Jin; Pingkang Li; Lice Zhao; Xiuxia Du; Xiaofeng Ma

2010-01-01

160

Hydrostatic compression of Fe(1-x)O wuestite  

NASA Technical Reports Server (NTRS)

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

Jeanloz, R.; Sato-Sorensen, Y.

1986-01-01

161

Mechanical spin bearings  

NASA Technical Reports Server (NTRS)

A spin bearing assembly including, a pair of mutually opposing complementary bearing support members having mutually spaced apart bearing support surfaces which may be, for example, bearing races and a set of spin bearings located therebetween. Each spin bearing includes a pair of end faces, a central rotational axis passing through the end faces, a waist region substantially mid-way between the end faces and having a first thickness dimension, and discrete side surface regions located between the waist region and the end faces and having a second thickness dimension different from the first thickness dimension of the waist region and wherein the side surface regions further have respective curvilinear contact surfaces adapted to provide a plurality of bearing contact points on the bearing support members.

Vranish, John M. (Inventor)

1998-01-01

162

Tracking Polar Bears  

NSDL National Science Digital Library

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

2008-01-17

163

High hydrostatic pressure treatment of finfish to inactivate Anisakis simplex.  

PubMed

High hydrostatic pressure has been demonstrated to be a useful technique for treating food to reduce the number of pathogenic organisms and to extend shelf life. Most research in this area has focused on bacteria. However, a concern in the sashimi (raw fish) industry is that nematode worms such as Anisakis simplex occur naturally in cold-water marine fish. The objectives of this research were to perform a pilot study to determine the effect of high hydrostatic pressure on the viability of Anisakis simplex larvae, commonly found in king salmon and arrowtooth flounder, and to evaluate the effects of high hydrostatic pressure on the color and texture of the fish fillets. Pieces of fish (ca. 100 g per bag) containing 13 to 118 larvae were exposed to pressures of up to 80,000 lb/in2 (552 MPa) for up to 180 s. The times and pressures required to kill 100% of the larvae were as follows: 30 to 60 s at 60,000 lb/in2 (414 MPa), 90 to 180 s at 40,000 lb/in2 (276 MPa), and 180 s at 30,000 lb/in2 (207 MPa). For all salmon treatments that killed 100% of the larvae, a significant increase in the whiteness of the flesh was observed. Although high hydrostatic pressure was effective in killing A. simplex larvae in raw fish fillets, its significant effect on the color and overall appearance of the fillet may limit its application to the processing of fish for raw-fish markets. PMID:14572234

Dong, Faye M; Cook, Allison R; Herwig, Russell P

2003-10-01

164

Polar Bears Change Diet  

NSDL National Science Digital Library

This radio broadcast from 2001 explains how polar bears have adjusted their diet due to the climate warming around Hudson Bay, Canada. The ringed seals that polar bears normally eat have been harder for polar bears to get to, due to disappearing ice. This has forced polar bears to begin eating harbor seals and bearded seals. The clip is 4 minutes and 15 seconds in length.

Doug Schneider

2007-12-12

165

Axial Halbach Magnetic Bearings  

NASA Technical Reports Server (NTRS)

Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

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

2008-01-01

166

Tracking Polar Bears  

USGS Multimedia Gallery

Movements of 9 satellite-collared adult female polar bears were tracked in February, 2010 by satellite telemetry. Bears were collared in 2007, 2008, and 2009 on the spring-time sea ice of the southern Beaufort Sea or on the autumn pack ice in 2009. Polar bear satellite telemetry data are shown with ...

167

Grizzly bears and forestry  

Microsoft Academic Search

Today's growing demand for timber is increasing road development in once roadless forest ecosystems. Roads create both local changes in plant communities and landscape-level changes in forest connectivity. Roads also increase human access, which can be detrimental to species such as grizzly bears. Because most grizzly bear mortalities occur near roads, we examined grizzly bear attractants near roads, which could

C. L. Roever; M. S. Boyce; G. B. Stenhouse

2008-01-01

168

1-Way Bearing  

NASA Technical Reports Server (NTRS)

A one-way bearing is provided having sprags and rolling bearings both disposed between an inner and an outer race. The sprags may comprise three-dimensional sprags for preventing rotation in a non-preferential direction. The roll- ing bearings may comprise thrust rollers for transmitting axial, tilt, and radial loads between the inner and outer races.

Vranish, John M. (Inventor)

2003-01-01

169

Cryogenic Hybrid Magnetic Bearing  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

170

Bulk-Flow Analysis of Hybrid Thrust Bearings for Advanced Cryogenic Turbopumps  

NASA Technical Reports Server (NTRS)

A bulk-flow analysis and computer program for prediction of the static load performance and dynamic force coefficients of angled injection, orifice-compensated hydrostatic/hydrodynamic thrust bearings have been completed. The product of the research is an efficient computational tool for the design of high-speed thrust bearings for cryogenic fluid turbopumps. The study addresses the needs of a growing technology that requires of reliable fluid film bearings to provide the maximum operating life with optimum controllable rotordynamic characteristics at the lowest cost. The motion of a cryogenic fluid on the thin film lands of a thrust bearing is governed by a set of bulk-flow mass and momentum conservation and energy transport equations. Mass flow conservation and a simple model for momentum transport within the hydrostatic bearing recesses are also accounted for. The bulk-flow model includes flow turbulence with fluid inertia advection, Coriolis and centrifugal acceleration effects on the bearing recesses and film lands. The cryogenic fluid properties are obtained from realistic thermophysical equations of state. Turbulent bulk-flow shear parameters are based on Hirs' model with Moody's friction factor equations allowing a simple simulation for machined bearing surface roughness. A perturbation analysis leads to zeroth-order nonlinear equations governing the fluid flow for the thrust bearing operating at a static equilibrium position, and first-order linear equations describing the perturbed fluid flow for small amplitude shaft motions in the axial direction. Numerical solution to the zeroth-order flow field equations renders the bearing flow rate, thrust load, drag torque and power dissipation. Solution to the first-order equations determines the axial stiffness, damping and inertia force coefficients. The computational method uses well established algorithms and generic subprograms available from prior developments. The Fortran9O computer program hydrothrust runs on a Windows 95/NT personal computer. The program, help files and examples are licensed by Texas A&M University Technology License Office. The study of the static and dynamic performance of two hydrostatic/hydrodynamic bearings demonstrates the importance of centrifugal and advection fluid inertia effects for operation at high rotational speeds. The first example considers a conceptual hydrostatic thrust bearing for an advanced liquid hydrogen turbopump operating at 170,000 rpm. The large axial stiffness and damping coefficients of the bearing should provide accurate control and axial positioning of the turbopump and also allow for unshrouded impellers, therefore increasing the overall pump efficiency. The second bearing uses a refrigerant R134a, and its application in oil-free air conditioning compressors is of great technological importance and commercial value. The computed predictions reveal that the LH2 bearing load capacity and flow rate increase with the recess pressure (i.e. increasing orifice diameters). The bearing axial stiffness has a maximum for a recess pressure rati of approx. 0.55. while the axial damping coefficient decreases as the recess pressure ratio increases. The computer results from three flow models are compared. These models are a) inertialess, b) fluid inertia at recess edges only, and c) full fluid inertia at both recess edges and film lands. The full inertia model shows the lowest flow rates, axial load capacity and stiffness coefficient but on the other hand renders the largest damping coefficients and inertia coefficients. The most important findings are related to the reduction of the outflow through the inner radius and the appearance of subambient pressures. The performance of the refrigerant hybrid thrust bearing is evaluated at two operating speeds and pressure drops. The computed results are presented in dimensionless form to evidence consistent trends in the bearing performance characteristics. As the applied axial load increases, the bearing film thickness and flow rate decrease while the recess pressure increases. The a

SanAndres, Luis

1998-01-01

171

Nonaxisymmetric incompressible hydrostatic pressure effects in radial face seals  

NASA Technical Reports Server (NTRS)

A flat seal having an angular misalinement is analyzed, taking into account the radial variations in seal clearance. An analytical solution for axial force, tilting moment, and leakage is presented that covers the whole range from zero to full angular misalinement. Nonaxisymmetric hydrostatic pressures due to the radial variations in the film thickness have a considerable effect on seal stability. When the high pressure is on the outer periphery of the seal, both the axial force and the tilting moment are nonrestoring. The case of high-pressure seals where cavitation is eliminated is discussed, and the possibility of dynamic instability is pointed out.

Etsion, I.

1976-01-01

172

Hydrostatic extrusion of Cu-Ag melt spun ribbon  

DOEpatents

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

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

1998-09-08

173

Hydrostatic extrusion of Cu-Ag melt spun ribbon  

DOEpatents

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

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

1998-01-01

174

Microelectrodes suitable for use in cells with high hydrostatic pressure.  

PubMed

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

Ernau, M C

1974-05-01

175

Steel pressure vessels for hydrostatic pressures to 50 kilobars.  

PubMed

Cylindrical steel pressure vessels are described that can be used for hydrostatic pressures up to 50 kilobars. Monoblock vessels of 350 maraging steel can be used to 40 kilobars and compound vessels with an inner vessel of 350 maraging steel and an outer vessel of 300 maraging steel to 50 kilobars. Neither requires the cylinder to be end loaded, and so they are much easier to use than the more usual compound vessels with a tungsten carbide inner and steel outer vessel. PMID:18699223

Lavergne, A; Whalley, E

1978-07-01

176

Injection by hydrostatic pressure in conjunction with electrokinetic force on a microfluidic chip.  

PubMed

A simple method was developed for injecting a sample on a cross-form microfluidic chip by means of hydrostatic pressure combined with electrokinetic forces. The hydrostatic pressure was generated simply by adjusting the liquid level in different reservoirs without any additional driven equipment such as a pump. Two dispensing strategies using a floating injection and a gated injection, coupled with hydrostatic pressure loading, were tested. The fluorescence observation verified the feasibility of hydrostatic pressure loading in the separation of a mixture of fluorescein sodium salt and fluorescein isothiocyanate. This method was proved to be effective in leading cells to a separation channel for single cell analysis. PMID:15213989

Gai, Hongwei; Yu, Linfen; Dai, Zhongpeng; Ma, Yinfa; Lin, Bingcheng

2004-06-01

177

Bearings: Technology and needs  

NASA Technical Reports Server (NTRS)

A brief status report on bearing technology and present and near-term future problems that warrant research support is presented. For rolling element bearings a material with improved fracture toughness, life data in the low Lambda region, a comprehensive failure theory verified by life data and incorporated into dynamic analyses, and an improved corrosion resistant alloy are perceived as important needs. For hydrodynamic bearings better definition of cavitation boundaries and pressure distributions for squeeze film dampers, and geometry optimization for minimum power loss in turbulent film bearings are needed. For gas film bearings, foil bearing geometries that form more nearly optimum film shapes for maximum load capacity, and more effective surface protective coatings for high temperature operation are needed.

Anderson, W. J.

1982-01-01

178

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

179

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

NASA Astrophysics Data System (ADS)

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

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

1992-06-01

180

The Incredible Water Bear  

NSDL National Science Digital Library

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

Martin Mach

181

Bearing restoration by grinding  

NASA Technical Reports Server (NTRS)

A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

1976-01-01

182

Linear magnetic bearing  

NASA Technical Reports Server (NTRS)

A linear magnetic bearing system having electromagnetic vernier flux paths in shunt relation with permanent magnets, so that the vernier flux does not traverse the permanent magnet, is described. Novelty is believed to reside in providing a linear magnetic bearing having electromagnetic flux paths that bypass high reluctance permanent magnets. Particular novelty is believed to reside in providing a linear magnetic bearing with a pair of axially spaced elements having electromagnets for establishing vernier x and y axis control. The magnetic bearing system has possible use in connection with a long life reciprocating cryogenic refrigerator that may be used on the space shuttle.

Studer, P. A. (inventor)

1983-01-01

183

A practical magnetic bearing  

NASA Technical Reports Server (NTRS)

A small compact magnetic bearing design developed and tested features a bearing capable of supporting over ten times its own weight, dimensioned 8 cm diam by 3.75 cm, with rare-earth cobalt magnets. Only 1% of the device payload figures as part of the magnetic suspension. The design is servoed in two axes and exhibits inherent stability in three more degrees of freedom, with full rotational freedom in the desired axis. Capacitive radial gap sensing allows stiff servoing of the rotation axis. Differential sensing and EM control linearize control functions. Low power drain, simple fabrication and assembly, and larger clearances than in air bearings or ball bearings are reported

Studer, P. A.

1977-01-01

184

Photomultiplier tube failure under hydrostatic pressure in future neutrino detectors  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

185

Stress response of Escherichia coli to elevated hydrostatic pressure.  

PubMed Central

The response of exponentially growing cultures of Escherichia coli to abrupt shifts in hydrostatic pressure was studied. A pressure upshift to 546 atm (55,304 kPa) of hydrostatic pressure profoundly perturbed cell division, nucleoid structure, and the total rate of protein synthesis. The number of polypeptides synthesized at increased pressure was greatly reduced, and many proteins exhibited elevated rates of synthesis relative to total protein synthesis. We designated the latter proteins pressure-induced proteins (PIPs). The PIP response was transient, with the largest induction occurring approximately 60 to 90 min postshift. Fifty-five PIPs were identified. Many of these proteins are also induced by heat shock or cold shock. The PIP demonstrating the greatest pressure induction was a basic protein of 15.6 kDa. High pressure inhibits growth but does not inhibit the synthesis of stringently controlled proteins. Cold shock is the only additional signal which has been found to elicit this type of response. These data indicate that elevated pressure induces a unique stress response in E. coli, the further characterization of which could be useful in delineating its inhibitory nature. Images PMID:8226663

Welch, T J; Farewell, A; Neidhardt, F C; Bartlett, D H

1993-01-01

186

Glycine Insertion Makes Yellow Fluorescent Protein Sensitive to Hydrostatic Pressure  

PubMed Central

Fluorescent protein-based indicators for intracellular environment conditions such as pH and ion concentrations are commonly used to study the status and dynamics of living cells. Despite being an important factor in many biological processes, the development of an indicator for the physicochemical state of water, such as pressure, viscosity and temperature, however, has been neglected. We here found a novel mutation that dramatically enhances the pressure dependency of the yellow fluorescent protein (YFP) by inserting several glycines into it. The crystal structure of the mutant showed that the tyrosine near the chromophore flipped toward the outside of the ?-can structure, resulting in the entry of a few water molecules near the chromophore. In response to changes in hydrostatic pressure, a spectrum shift and an intensity change of the fluorescence were observed. By measuring the fluorescence of the YFP mutant, we succeeded in measuring the intracellular pressure change in living cell. This study shows a new strategy of design to engineer fluorescent protein indicators to sense hydrostatic pressure. PMID:24014139

Watanabe, Tomonobu M.; Imada, Katsumi; Yoshizawa, Keiko; Nishiyama, Masayoshi; Kato, Chiaki; Abe, Fumiyoshi; Morikawa, Takamitsu J.; Kinoshita, Miki; Fujita, Hideaki; Yanagida, Toshio

2013-01-01

187

Power transmission arrangement for a hydrostatically driven vehicle  

SciTech Connect

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

Tokunga, N.

1986-03-25

188

Microbial Growth Modification by Compressed Gases and Hydrostatic Pressure  

PubMed Central

Studies of the growth-modifying actions for Escherichia coli, Saccharomyces cerevisiae, and Tetrahymena thermophila of helium, nitrogen, argon, krypton, xenon, and nitrous oxide led to the conclusion that there are two definable classes of gases. Class 1 gases, including He, N2, and Ar, are not growth inhibitors; in fact, they can reverse the growth inhibitory action of hydrostatic pressures. Class 2 gases, including Kr, Xe, and N2O, are potent growth inhibitors at low pressures. For example, at 24°C, 50% growth-inhibitory pressures of N2O were found to be ca. 1.7 MPa for E. coli, 1.0 MPa for S. cerevisiae, and 0.5 MPa for T. thermophila. Class 1 gases could act as potentiators for growth inhibition by N2O, O2, Kr, or Xe. Hydrostatic pressure alone is known to reverse N2O inhibition of growth, but we found that it did not greatly alter oxygen toxicity. Therefore, potentiation by class 1 gases appeared to be a gas effect rather than a pressure effect. The temperature profile for growth inhibition of S. cerevisiae by N2O revealed an optimal temperature for cell resistance of ca. 24°C, with lower resistance at higher and lower temperatures. Overall, it appeared that microbial growth modification by hyperbaric gases could not be related to their narcotic actions but reflected definably different physiological actions. PMID:16346516

Thom, Stephen R.; Marquis, Robert E.

1984-01-01

189

Effect of Eccentricity on the Static and Dynamic Performance of a Turbulent Hybrid Bearing  

NASA Technical Reports Server (NTRS)

The effect of journal eccentricity on the static and dynamic performance of a water lubricated, 5-recess hybrid bearing is presented in detail. The hydrostatic bearing has been designed to operate at a high speed and with a large level of external pressurization. The operating conditions determine the flow in the bearing to be highly turbulent and strongly dominated by fluid inertia effects. The analysis covers the spectrum of journal center displacements directed towards the middle of a recess and towards the mid-land portion between two consecutive recesses. Predicted dynamic force coefficients are uniform for small to moderate eccentricities. For large journal center displacements, fluid cavitation and recess position determine large changes in the bearing dynamic performance. The effect of fluid inertia force coefficients on the threshold speed of instability and whirl ratio of a single mass flexible rotor is discussed.

Sanandres, Luis A.

1991-01-01

190

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

NASA Astrophysics Data System (ADS)

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

Dubos, Thomas; Voitus, Fabrice

2014-05-01

191

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

NASA Technical Reports Server (NTRS)

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

Sanandres, Luis

1994-01-01

192

Bearing servicing tool  

NASA Technical Reports Server (NTRS)

A tool for removing and/or replacing bearings in situ is presented. The tool is comprised of a brace having a first end adapted to engage a first end of the bearing housing, and a second end adapted to engage a second end of the bearing housing. If the two ends of the bearing housing are different in configuration, then the respective ends of the brace are configured accordingly. An elongate guide member integral with the brace has two parts, each projecting endwise from a respective end of the brace. A removable pressure plate can be mounted on either part of the guide member for longitudinal movement therealong and has first and second ends of different configurations adapted to engage the first and second ends of the bearing. A threaded-type drive is cooperative between the guide and the pressure plate to move the pressure plate longitudinally along the guide and apply a force to the bearing, either to remove the bearing from its housing, or to emplace a new bearing in the housing.

Boyce, Rex A. (inventor)

1992-01-01

193

Bearing fatigue investigation 3  

NASA Technical Reports Server (NTRS)

The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

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

1982-01-01

194

Grizzly bears and forestry  

Microsoft Academic Search

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

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

2004-01-01

195

Grizzly bears and forestry  

Microsoft Academic Search

Timber harvesting and oil and gas extraction create ecological change beyond just the footprint of the resource extraction. These activities also create a permanent network of roads that can have lasting effects on forest ecology. Grizzly bears (Ursus arctos) suffer higher mortality when in close proximity to roads, yet bears in the foothills of west-central Alberta, continue to use these

C. L. Roever; M. S. Boyce; G. B. Stenhouse

2008-01-01

196

ALASKAN POLAR BEAR DENNING  

Microsoft Academic Search

Abstract: Information on 35 overwinter maternity dens of Alaskan polar bears (Ursus maritimnus Phipps) and on 101 female polar bears with cubs, recently emerged from dens, was obtained by aerial and ground surveys, interviews with Arctic coast residents, and literature review. Pregnant females form snow dens in October and November and give birth in December and January. Females and cubs

Jack W. Lentfer; Richard J. Hensel

197

Magnetic bearing applications & economics  

Microsoft Academic Search

Magnetic bearings offer a myriad of operational advantages and efficiency improvement over traditional oil lubricated bearings. They have been in use for the past thirty years, but for several reasons, including cost, have been limited to niche applications (such as high-speed turbomachines) that required their unique capabilities. Recent advances in the technology are making it more practical to apply these

D. Eaton; J. Rama; S. Singhal

2010-01-01

198

Study of Catcher Bearings for High Temperature Magnetic Bearing Application  

E-print Network

temperature permanent magnet based magnetic bearings. The magnetic bearings are made of high temperature resistant permanent magnets (up to 1000 degrees F). A test rig has been developed to test these magnetic bearings. The test rig mainly consists of two...

Narayanaswamy, Ashwanth

2011-08-08

199

A 2D Unified (Non) Hydrostatic Model of the Atmosphere with a Discontinuous Galerkin Method  

Microsoft Academic Search

A two dimensional mesoscale atmospheric model is presented based on two systems of dynamical equations, the non-hydrostatic compressible Euler equations and the corresponding hydrostatic system. Both equation systems are discretized with a discontinuous Galerkin method in space and a linear semi-implicit multistep method in time. To cover elementwise polynomial spaces up to order four, exact quadrature rules are used. The

Matthias Lauter; Francis X. Giraldo; Sebastian Reich; Marco Restelli; Dorthe Handorf; Klaus Dethloff

200

Application of high hydrostatic pressure to control enzyme related fresh seafood texture deterioration  

Microsoft Academic Search

Enzyme extracts from two fish species, bluefish and sheephead, were subjected to hydrostatic pressure treatments ranging between 1000–3000 atm for various durations and the residual activities of cathepsin C, collagenase, chymotrypsin- and trypsin-like enzymes compared with those of their bovine counterparts. The fish enzymes were generally more susceptible to hydrostatic pressure inactivation than their mammalian counterparts. Fresh fish muscle tissues

I. N. A. Ashie; B. K. Simpson

1996-01-01

201

Mechanoluminescence of ZnS:Mn phosphors excited by hydrostatic pressure steps and pressure pulses  

NASA Astrophysics Data System (ADS)

When a hydrostatic pressure step is applied rapidly on ZnS:Mn phosphor introduced into a pressure cell as oil suspension, initially the mechanoluminescence (ML) intensity increases linearly with time, attains a peak value for a particular time, and then it decreases with time (G. Alzetta, N. Minnaja, S. Santucci, Nuovo Cimento 23, 1962, 910). When a hydrostatic pressure pulse is applied onto ZnS:Mn phosphor, then two ML pulses of equal intensity are emitted; one during the application of pressure and the other during the release of pressure. In case of ZnS:Mn phosphor, at low hydrostatic pressure the energy produced during the electron-hole recombination excites the Mn2+ centres; however, at high hydrostatic pressure, the impact of accelerated electrons with the Mn2+ centres causes the light emission. Considering the piezoelectrically-induced detrapping model of ML at low pressure and the piezoelectrically-induced impact excitation model of ML at high pressure, expressions are derived for different characteristics of ML, in which a good agreement is found between the theoretical and experimental results. At low hydrostatic pressure in the range from 3 MPa to 40 MPa, piezoelectrically-induced detrapping model of ML becomes applicable in ZnS:Mn phosphors; while at high hydrostatic pressure beyond 40 MPa, the piezoelectrically-induced impact excitation model of ML becomes applicable. The ML induced by hydrostatic pressure can be used for sensing both the magnitude and rise time of applied hydrostatic pressure.

Chandra, V. K.; Chandra, B. P.; Jha, Piyush

2014-11-01

202

The effect of high hydrostatic pressure on the anthocyanins of raspberry ( Rubus idaeus)  

Microsoft Academic Search

The colour stability of fruit puree made from raspberries (Rubus idaeus), which were subjected to high hydrostatic pressure, was studied by measuring the anthocyanin content. High hydrostatic pressure is an alternative method of food preservation to heat treatment. In this study, we assess the impact of high pressure on the colour molecules in raspberries. Fruit samples were pressured under 200,

Winai Suthanthangjai; Paul Kajda; Ioannis Zabetakis

2005-01-01

203

Touchdown Ball-Bearing System for Magnetic Bearings  

NASA Technical Reports Server (NTRS)

The torque-limited touchdown bearing system (TLTBS) is a backup mechanical-bearing system for a high-speed rotary machine in which the rotor shaft is supported by magnetic bearings in steady-state normal operation. The TLTBS provides ball-bearing support to augment or supplant the magnetic bearings during startup, shutdown, or failure of the magnetic bearings. The TLTBS also provides support in the presence of conditions (in particular, rotational acceleration) that make it difficult or impossible to control the magnetic bearings or in which the magnetic bearings are not strong enough (e.g., when the side load against the rotor exceeds the available lateral magnetic force).

Kingsbury, Edward P.; Price, Robert; Gelotte, Erik; Singer, Herbert B.

2003-01-01

204

Ball and Roller Bearings. A Teaching Reference.  

ERIC Educational Resources Information Center

The manual provides a subject reference for ball and roller bearings. The following topics are included: (1) bearing nomenclature, (2) bearing uses, (3) bearing capacities, (4) shop area working conditions, (5) bearing removal, (6) bearing cleaning and inspection, (7) bearing replacement, (8) bearing lubrication, (9) bearing installation, (10)…

American Association for Vocational Instructional Materials, Athens, GA.

205

Magnetically-controlled bearing lubrication  

NASA Technical Reports Server (NTRS)

Proposed magnetic-lubricant ball-bearing assembly has permanently-magnetized bearing retainer fabricated of porous material. Pores of retainer are filled with ferrolubricant. Surface tension causes retainer to deliver sufficient lubricant to nonmagnetic ball bearings.

Whitaker, A. F.

1977-01-01

206

Effect of hydrostatic pressure on elastic properties of ZDTP tribofilms  

E-print Network

Previous studies have shown that the elastic properties of Zinc Dialkyl-dithiophosphate (ZDTP) tribofilms measured by nanoindentation increase versus applied pressure (Anvil effect) [1, 2]. The aim of this paper is to demonstrate that, up to 8 GPa, this increase is a reversible phenomenon. A ZDTP tribofilm has been produced on "AISI 52100" steel substrate using a Cameron-Plint tribometer. After its formation, a hydrostatic pressure of about 8 GPa was applied during one minute on the tribofilm using a large radius steel ball ("Brinell-like" test). Nanoindentation tests were performed with a Berkovich tip on pads in order to measure and compare the mechanical properties of the tribofilm inside and outside the macroscopic plastically deformed area. Careful AFM observations have been carried out on each indent in order to take into account actual contact area. No difference in elastic properties was observed between the two areas: tribofilm modulus and pressure sensitivity are the same inside and outside the resi...

Demmou, Karim; Loubet, Jean-Luc

2007-01-01

207

Hydrometer calibration by hydrostatic weighing with automated liquid surface positioning  

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

208

Effect of hydrostatic pressure on ligand binding to hemoglobin.  

PubMed

Increase in hydrostatic pressure to 1000 atm increased the affinity of human and menhaden (Brevoortia tyrannus) hemoglobins for oxygen. With necessary assumptions about the form of the equilibrium curve, and after correction for changes in pH and volume due to pressure, the increase in affinity is about 2-fold for both hemoglobins. At pH 6.5, Hill's n for menhaden hemoglobin is near 1, and it is believed to remain in the T state, whereas human hemoglobin undergoes a T to R transition. This suggests that the R-T equilibrium is not disturbed by pressure. In direct experiments the binding of a fluorescent effector (8 hydroxy-1,3,6-pyrene (trisulfonic acid) to deoxyhemoglobin was not changed by pressure. The binding of n-butylisocyanide to hemoglobin and to myoglobin is also greater at high pressures, similarly suggesting that the R-T transition is not involved in the pressure effect. PMID:16924

Carey, F G; Knowles, F; Gibson, Q H

1977-06-25

209

Damage Characterization in Copper Deformed Under Hydrostatic Stress - Experimental Analysis  

NASA Astrophysics Data System (ADS)

This paper presents an experimental investigation to characterize the effect of damage created by hydrostatic tensile loading on the properties of copper. Three metallurgical conditions were investigated: half-hard OFHC copper in the as worked, annealed 2hr at 400°C (˜40 micron grain diameter), and annealed 2hr at 800^ oC (˜80 micron grain diameter). Quasi-static testing of each condition included uniaxial tension and compression, round notched bar tension, and flat tapered bar tension. Dynamic properties under uniaxial tension and compression were tested using a split-Hopkinson pressure bar. Damaged structures were created employing Taylor impact tests and rod-on-rod impact experiments. The resulting damage was characterized employing optical and scanning electron microscopy. Quasi-static compression samples machined from recovered samples were tested to determine the influence of damage on deformation behavior and elastic modulus. The compression experimental results will be discussed in relationship to the starting microstructure and subsequent damaged material.

Flater, Philip; de Angelis, Robert; House, Joel

2005-07-01

210

Role of osmotic and hydrostatic pressures in bacteriophage genome ejection  

NASA Astrophysics Data System (ADS)

A critical step in the bacteriophage life cycle is genome ejection into host bacteria. The ejection process for double-stranded DNA phages has been studied thoroughly in vitro, where after triggering with the cellular receptor the genome ejects into a buffer. The experimental data have been interpreted in terms of the decrease in free energy of the densely packed DNA associated with genome ejection. Here we detail a simple model of genome ejection in terms of the hydrostatic and osmotic pressures inside the phage, a bacterium, and a buffer solution or culture medium. We argue that the hydrodynamic flow associated with the water movement from the buffer solution into the phage capsid and further drainage into the bacterial cytoplasm, driven by the osmotic gradient between the bacterial cytoplasm and culture medium, provides an alternative mechanism for phage genome ejection in vivo; the mechanism is perfectly consistent with phage genome ejection in vitro.

Lemay, Serge G.; Panja, Debabrata; Molineux, Ian J.

2013-02-01

211

Role of osmotic and hydrostatic pressures in bacteriophage genome ejection  

E-print Network

A critical step in the bacteriophage life cycle is genome ejection into host bacteria. The ejection process for double-stranded DNA phages has been studied thoroughly \\textit{in vitro}, where after triggering with the cellular receptor the genome ejects into a buffer. The experimental data have been interpreted in terms of the decrease in free energy of the densely packed DNA associated with genome ejection. Here we detail a simple model of genome ejection in terms of the hydrostatic and osmotic pressures inside the phage, a bacterium, and a buffer solution/culture medium. We argue that the hydrodynamic flow associated with the water movement from the buffer solution into the phage capsid and further drainage into the bacterial cytoplasm, driven by the osmotic gradient between the bacterial cytoplasm and culture medium, provides an alternative mechanism for phage genome ejection \\textit{in vivo}; the mechanism is perfectly consistent with phage genome ejection \\textit{in vitro}.

Serge G. Lemay; Debabrata Panja; Ian J. Molineux

2013-02-21

212

Role of osmotic and hydrostatic pressures in bacteriophage genome ejection  

E-print Network

A critical step in the bacteriophage life cycle is genome ejection into host bacteria. The ejection process for double-stranded DNA phages has been studied thoroughly \\textit{in vitro}, where after triggering with the cellular receptor the genome ejects into a buffer. The experimental data have been interpreted in terms of the decrease in free energy of the densely packed DNA associated with genome ejection. Here we detail a simple model of genome ejection in terms of the hydrostatic and osmotic pressures inside the phage, a bacterium, and a buffer solution/culture medium. We argue that the hydrodynamic flow associated with the water movement from the buffer solution into the phage capsid and further drainage into the bacterial cytoplasm, driven by the osmotic gradient between the bacterial cytoplasm and culture medium, provides an alternative mechanism for phage genome ejection \\textit{in vivo}; the mechanism is perfectly consistent with phage genome ejection \\textit{in vitro}.

Lemay, Serge G; Molineux, Ian J

2012-01-01

213

Hydrostatic factors affect the gravity responses of algae and roots  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

214

Cell Membranes Under Hydrostatic Pressure Subjected to Micro-Injection  

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

215

Ultrahigh hydrostatic pressure extraction of flavonoids from Epimedium koreanum Nakai  

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

216

The Polar Bear Tracker  

NSDL National Science Digital Library

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

217

Ball Bearing Mechanics  

NASA Technical Reports Server (NTRS)

Load-deflection relationships for different types of elliptical contacts such as those found in a ball bearing are developed. Simplified expressions that allow quick calculations of deformation to be made simply from a knowledge of the applied load, the material properties, and the geometry of the contacting elements are presented. Ball bearings subjected to radial, thrust and combined ball loads are analyzed. A design criterion for fatigue life of ball bearings is developed. The section of a satisfactory lubricant, as well as describing systems that provide a constant flow of lubricant to the contact, is considered.

Hamrock, B. J.; Dowson, D.

1981-01-01

218

Assessment of the non-hydrostatic effect on the upper atmosphere using a general circulation model (GCM)  

Microsoft Academic Search

Under hydrostatic equilibrium, a typical assumption used in global thermosphere ionosphere models, the pressure gradient in the vertical direction is exactly balanced by the gravity force. Using the non-hydrostatic Global Ionosphere Thermosphere Model (GITM), which solves the complete vertical momentum equation, the primary characteristics of non-hydrostatic effects on the upper atmosphere are investigated. Our results show that after a sudden

Yue Deng; Arthur D. Richmond; Aaron J. Ridley; Han-Li Liu

2008-01-01

219

Roller bearing geometry design  

NASA Technical Reports Server (NTRS)

A theory of kinematic stabilization of rolling cylinders is extended and applied to the design of cylindrical roller bearings. The kinematic stabilization mechanism puts a reverse skew into the rolling elements by changing the roller taper. Twelve basic bearing modification designs are identified amd modeled. Four have single transverse convex curvature in their rollers while eight have rollers which have compound transverse curvature made up of a central cylindrical band surrounded by symmetric bands with slope and transverse curvature. The bearing designs are modeled for restoring torque per unit axial displacement, contact stress capacity, and contact area including dynamic loading, misalignment sensitivity and roller proportion. Design programs are available which size the single transverse curvature roller designs for a series of roller slopes and load separations and which design the compound roller bearings for a series of slopes and transverse radii of curvature. The compound rollers are proportioned to have equal contact stresses and minimum size. Design examples are also given.

Savage, M.; Pinkston, B. H. W.

1976-01-01

220

Protecting Bear While Tranqualized  

USGS Multimedia Gallery

The kerchief over the bear's eyes protects it from dust and debris and reduces visual stimulation. The small tubing in its nose, known as a nasal cannula, delivers oxygen to the animal while it is tranquilized....

221

PCs and Polar Bears  

NSDL National Science Digital Library

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

Jessica Fries-Gaither

2011-01-01

222

Optimal Synchronizability of Bearings  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

223

Investigation of Pressurized Wave Bearings  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

224

Gear bearing drive  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

225

Load responsive hydrodynamic bearing  

DOEpatents

A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular bearing bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the bearing, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.

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

2002-01-01

226

Climate Drives Polar Bear Origins  

Technology Transfer Automated Retrieval System (TEKTRAN)

In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

227

American Black Bear: Ursus americanus  

E-print Network

3/21/2011 1 USFWS American Black Bear: Ursus americanus www.bear.org LDWF Historic Distribution Bear: Ursus americanus Louisiana Florida Eastern Olympic New Mexico California Cinnamon Mexican: Ursus americanus luteolus American black bear Historically abundant in Louisiana, eastern Texas

Gray, Matthew

228

Externally Pressurized Porous Thrust Bearings  

Microsoft Academic Search

The use of porous material in the bearing surface of externally pressurized thrust bearings leads to a compact design by eliminating the need for an external restrictor and has other potential advantages.An experimental and theoretical investigation of the performance of such bearings, using liquid lubricants is described: the investigation is limited to static conditions but considers the effect of bearing

R. B. Howarth

1976-01-01

229

Microstructure evolution in age-hardenable aluminium alloy during processing by hydrostatic extrusion.  

PubMed

In the present work, scanning and transmission electron microscopy were used to investigate the microstructural evolution occurring during the hydrostatic extrusion of an age-hardenable aluminium alloy. It was shown that processing by hydrostatic extrusion leads to grain refinement to 95 nm in equivalent diameter. Hydrostatic extrusion also influences the geometrical parameters of two different types of particle: intermetallic inclusions and precipitates. The intermetallic inclusions slightly decrease in mean equivalent diameter, but their size remains at the micrometre level. The precipitates are fragmented to nanoscale spherical particles, and their evolution delays the process of grain refinement. PMID:17100901

Lewandowska, M

2006-10-01

230

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

NASA Astrophysics Data System (ADS)

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

Wang, Zhaogang; Zhang, Wentao; Li, Fang

2013-09-01

231

Vertical Discretization of Hydrostatic Primitive Equations with Finite Element Method  

NASA Astrophysics Data System (ADS)

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

Yi, Tae-Hyeong; Park, Ja-Rin

2014-05-01

232

Partial tooth gear bearings  

NASA Technical Reports Server (NTRS)

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

Vranish, John M. (Inventor)

2010-01-01

233

Radial Halbach Magnetic Bearings  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

234

Low hydrostatic head electrolyte addition to fuel cell stacks  

DOEpatents

A fuel cell and system for supply electrolyte, as well as fuel and an oxidant to a fuel cell stack having at least two fuel cells, each of the cells having a pair of spaced electrodes and a matrix sandwiched therebetween, fuel and oxidant paths associated with a bipolar plate separating each pair of adjacent fuel cells and an electrolyte fill path for adding electrolyte to the cells and wetting said matrices. Electrolyte is flowed through the fuel cell stack in a back and forth fashion in a path in each cell substantially parallel to one face of opposite faces of the bipolar plate exposed to one of the electrodes and the matrices to produce an overall head uniformly between cells due to frictional pressure drop in the path for each cell free of a large hydrostatic head to thereby avoid flooding of the electrodes. The bipolar plate is provided with channels forming paths for the flow of the fuel and oxidant on opposite faces thereof, and the fuel and the oxidant are flowed along a first side of the bipolar plate and a second side of the bipolar plate through channels formed into the opposite faces of the bipolar plate, the fuel flowing through channels formed into one of the opposite faces and the oxidant flowing through channels formed into the other of the opposite faces.

Kothmann, Richard E. (Churchill Boro, PA)

1983-01-01

235

Creep of wet gypsum aggregates under hydrostatic loading conditions  

NASA Astrophysics Data System (ADS)

Gypsum-dominated evaporite sequences are known to play an important role in controlling the mechanics of foreland thrust and nappe tectonics, as well as occasionally forming large-scale halokinetic structures associated with oil and gas accumulations. However, relatively little is known regarding the relevant deformation mechanisms and mechanical behaviour of gypsum. In this study, attention is focused on determining the compaction creep behaviour of wet granular gypsum aggregates with the aim of assessing the importance of pressure solution. Hydrostatic compaction experiments were performed at room temperature and applied effective pressures in the range 0.4-3.9 MPa, using grain sizes ranging from 15 to 125 ?m. The microstructure of the wet-tested samples showed that compaction occurred by a process of dissolution within grain contacts and precipitation on pore walls. In addition, for most of the range of conditions investigated, the mechanical data were found to be broadly consistent with models for interface-reaction-controlled grain boundary diffusional pressure solution. Combining the mechanical data with kinetic data taken from the crystal growth / dissolution literature it is suggested that for the bulk of conditions studied, creep of our wet granular gypsum aggregates was probably rate-limited by precipitation on the pore walls. This is in sharp contrast to the diffusion-controlled pressure solution creep behaviour recently reported for highly soluble salts, such as NaCl and NaNO 3, under similar conditions.

de Meer, Siese; Spiers, Christopher J.

1995-05-01

236

Scaling of the hydrostatic skeleton in the earthworm Lumbricus terrestris.  

PubMed

The structural and functional consequences of changes in size or scale have been well studied in animals with rigid skeletons, but relatively little is known about scale effects in animals with hydrostatic skeletons. We used glycol methacrylate histology and microscopy to examine the scaling of mechanically important morphological features of the earthworm Lumbricus terrestris over an ontogenetic size range from 0.03 to 12.89 g. We found that L. terrestris becomes disproportionately longer and thinner as it grows. This increase in the length to diameter ratio with size means that, when normalized for mass, adult worms gain ~117% mechanical advantage during radial expansion, compared with hatchling worms. We also found that the cross-sectional area of the longitudinal musculature scales as body mass to the ~0.6 power across segments, which is significantly lower than the 0.66 power predicted by isometry. The cross-sectional area of the circular musculature, however, scales as body mass to the ~0.8 power across segments, which is significantly higher than predicted by isometry. By modeling the interaction of muscle cross-sectional area and mechanical advantage, we calculate that the force output generated during both circular and longitudinal muscle contraction scales near isometry. We hypothesize that the allometric scaling of earthworms may reflect changes in soil properties and burrowing mechanics with size. PMID:24871920

Kurth, Jessica A; Kier, William M

2014-06-01

237

MHD Kelvin-Helmholtz instability in non-hydrostatic equilibrium  

NASA Astrophysics Data System (ADS)

The present work deals with the linear stability of a magnetohydrodynamic shear flow so that a stratified inviscid fluid rotating about a vertical axis when a uniform magnetic field is applied in the direction of the streaming or zonal flow. In geophysical flow, the stability of the flow is determined by taking into account the nonhydrostatic condition depending on Richardson number Ri and the deviation ? from hydrostatic equilibrium. According to Stone (Stone P H 1971 J. Fluid. Mech. 45 659), it is shown that such deviation ? decreases the growth rates of three kinds of instability which can appear as geostrophic (G), symmetric (S) and Kelvin-Helmholtz (K-H) instabilities. To be specific, the evolution of the flow is therefore considered in the light of the influence of magnetic field, particularly, on K-H instability. The results of this study are presented by the linear stability of a magnetohydrodynamic, with horizontal free-shear flow of stratified fluid, subject to rotation about the vertical axis and uniform magnetic field in the zonal direction. Results are discussed and compared to previous works as Chandrasekhar (Chandrasekhar S 1961 Hydrodynamic and hydromagnetic stability (Oxford: Clarendon Press) chapter 11 pp 481-513) and Stone [1].

Laghouati, Y.; Bouabdallah, A.; Zizi, M.; Alemany, A.

2007-04-01

238

High hydrostatic pressure-induced inactivation of bacterial spores.  

PubMed

High hydrostatic pressure (HHP) is the most-widely adopted novel non-thermal technology for the commercial pasteurization of foods. However, HHP-induced inactivation of bacterial spores remains a challenge due to spore resistance to the treatment limits of currently available industrial HHP units (i.e. ~650 MPa and 50 °C). Several reports have demonstrated that high pressure can modulate the germination machinery of bacterial spores, rendering them susceptible to subsequent inactivation treatments. Unfortunately, high pressure-induced germination is a unique phenomenon for spores of the genus Bacillus but not of Clostridium. Alternative strategies to inactivate bacterial spores at commercially available pressure and temperature levels include promoting the germination step by inclusion of known germinants into the food formulation to increase the lethality of HHP treatments on bacterial spores. The aim of this review is to provide an overview of the molecular basis involved in pressure-triggered germination of bacterial spores and of novel strategies to inactivate bacterial spores with HHP treatments. PMID:23631742

Sarker, Mahfuzur R; Akhtar, Saeed; Torres, J Antonio; Paredes-Sabja, Daniel

2015-02-01

239

HIGH HYDROSTATIC PRESSURE PROCESSING: A POTENTIAL SOLUTION FOR SHELLFISH-BORNE VIRUSES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Molluscan shellfish bioconcentrate enteric viruses from human wastes that are present in the growing waters. Consequently, the consumption of raw shellfish poses considerable risk for contracting illnesses associated with these viruses. High hydrostatic pressure is a new nonthermal sanitizing proc...

240

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

ERIC Educational Resources Information Center

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

Edge, R. D., Ed.

1984-01-01

241

High-pressure resistivity technique for quasi-hydrostatic compression experiments.  

PubMed

Diamond anvil cell techniques are now well established and powerful methods for measuring materials properties to very high pressure. However, high pressure resistivity measurements are challenging because the electrical contacts attached to the sample have to survive to extreme stress conditions. Until recently, experiments in a diamond anvil cell were mostly limited to non-hydrostatic or quasi-hydrostatic pressure media other than inert gases. We present here a solution to the problem by using focused ion beam ultrathin lithography for a diamond anvil cell loaded with inert gas (Ne) and show typical resistivity data. These ultrathin leads are deposited on the culet of the diamond and are attaching the sample to the anvil mechanically, therefore allowing for measurements in hydrostatic or nearly hydrostatic conditions of pressure using noble gases like Ne or He as pressure transmitting media. PMID:23822353

Rotundu, C R; ?uk, T; Greene, R L; Shen, Z-X; Hemley, Russell J; Struzhkin, V V

2013-06-01

242

The hydrostatic corer Selcore--a tool for sediment sampling and geophysical site characterization  

E-print Network

hydrostatic power to drive the sampling tube into the seabed released all the energy in a single burst Marine: +47 55583660. E-mail address: yngve.kristoffersen@geo.uib.no (Y. Kristoffersen). 0025-3227/$ - see

Kristoffersen, Yngve

243

Electronic structure computation and differential capacitance profile in ?-doped FET as a function of hydrostatic pressure  

SciTech Connect

In this work we present the results obtained from the calculation of the level structure of a n-type delta-doped well Field Effect Transistor when is subjected to hydrostatic pressure. We study the energy level structure as a function of hydrostatic pressure within the range of 0 to 6 kbar for different Schottky barrier height (SBH). We use an analytical expression for the effect of hydrostatic pressure on the SBH and the pressure dependence of the basic parameters of the system as the effective mass m(P) and the dielectric constant ?(P) of GaAs. We found that due to the effects of hydrostatic pressure, in addition to electronic level structure alteration, the profile of the differential capacitance per unit area C{sup ?2} is affected.

Carlos-Pinedo, C.; Rodríguez-Vargas, I.; Martínez-Orozco, J. C. [Unidad Académica de Física. Universidad Autónoma de Zacatecas. Calzada Solidaridad Esquina con Paseo la Bufa S/N. C.P. 98060, Zacatecas, Zac. (Mexico)

2014-05-15

244

Blood Pump Bearing System  

NASA Technical Reports Server (NTRS)

An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

Aber, Gregory S. (Inventor)

2000-01-01

245

Blood Pump Bearing System  

NASA Technical Reports Server (NTRS)

Methods and apparatus are provided for a blood pump bearing system within a pump housing to support long-term high-speed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the shaft to support high speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

Aber, Gregory S. (Inventor)

1999-01-01

246

Modular gear bearings  

NASA Technical Reports Server (NTRS)

A gearing system using modular gear bearing components. Each component is composed of a core, one or more modules attached to the core and two or more fastening modules rigidly attaching the modules to the core. The modules, which are attached to the core, may consist of gears, rollers or gear bearing components. The core orientation affects the orientation of the modules attached to the core. This is achieved via the keying arrangement of the core and the component modules that attach to the core. Such an arrangement will also facilitate the phase tuning of gear modules with respect to the core and other gear modules attached to the core.

Vranish, John M. (Inventor)

2009-01-01

247

Hydrostatic-pressure induced phase transition of phonons in single-walled nanotubes  

Microsoft Academic Search

We study the effect of the hydrostatic pressure on the phonons in single-walled carbon nanotubes (SWNTs) in a magnetic field. We calculate the magnetic moments of the phonons using a functional integral technique, and find that the phonons in SWNTs undergo a pressure-induced phase transition from the paramagnetic phase to the diamagnetic phase under hydrostatic pressure 2GPa. We explain the

Feng Peng; Meng Qingchao

2009-01-01

248

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

NASA Astrophysics Data System (ADS)

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

Perger, Warren; Slough, Wil

2007-06-01

249

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

Microsoft Academic Search

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

A. L. B. Penna; G. V. Barbosa-Cánovas

2007-01-01

250

Grinding and measuring long shafts to roundness errors of one microinch using hydrostatic spherical centers  

SciTech Connect

A replacement spindle shaft for the Diamond Turning and Grinding Machine at Livermore was ground by Whitnon Spindle Company using spherical hydrostatic centers developed by Lawrence Livermore National Laboratory. These centers made it possible to both grind the shaft round within one microinch and also measure the roundness on a commercial grinding machine. This report describes the hydrostatic center design and the procedures used to grind the spindle shaft.

Bryan, J.; Carter, D.; Clouser, R.; Stratton, F.

1986-06-16

251

Effect of cyclic hydrostatic pressure on the sacrificial anode cathodic protection  

Microsoft Academic Search

Purpose – The purpose of this paper is to study the effect of cyclic hydrostatic pressure on the protective performance of cathodic protection (CP) system consisting of Zn-Bi sacrificial anode and Ni-Cr-Mo-V steel. Design\\/methodology\\/approach – The anode and cathode polarization curves of the driving potential and current for CP were investigated in case of cyclic hydrostatic pressure (0-3.5 MPa) and

Shengnan Hu; Tao Zhang; Yawei Shao; Guozhe Meng; Fuhui Wanga

2011-01-01

252

EVOLUTION OF THE MERGER-INDUCED HYDROSTATIC MASS BIAS IN GALAXY CLUSTERS  

SciTech Connect

In this work, we examine the effects of mergers on the hydrostatic mass estimate of galaxy clusters using high-resolution Eulerian cosmological simulations. We utilize merger trees to isolate the last merger for each cluster in our sample and follow the time evolution of the hydrostatic mass bias as the systems relax. We find that during a merger, a shock propagates outward from the parent cluster, resulting in an overestimate in the hydrostatic mass bias. After the merger, as a cluster relaxes, the bias in hydrostatic mass estimate decreases but remains at a level of -5%-10% with 15%-20% scatter within r{sub 500}. We also investigate the post-merger evolution of the pressure support from bulk motions, a dominant cause of this residual mass bias. At r{sub 500}, the contribution from random motions peaks at 30% of the total pressure during the merger and quickly decays to {approx}10%-15% as a cluster relaxes. Additionally, we use a measure of the random motion pressure to correct the hydrostatic mass estimate. We discover that 4 Gyr after mergers, the direct effects of the merger event on the hydrostatic mass bias have become negligible. Thereafter, the mass bias is primarily due to residual bulk motions in the gas which are not accounted for in the hydrostatic equilibrium equation. We present a hydrostatic mass bias correction method that can recover the unbiased cluster mass for relaxed clusters with 9% scatter at r{sub 500} and 11% scatter in the outskirts, within r{sub 200}.

Nelson, Kaylea; Nagai, Daisuke [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Rudd, Douglas H.; Shaw, Laurie, E-mail: kaylea.nelson@yale.edu [Department of Physics, Yale University, New Haven, CT 06520 (United States)

2012-06-01

253

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

Microsoft Academic Search

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

Y. Paul. Handa

1990-01-01

254

Modeling mass transfer during osmotic dehydration of strawberries under high hydrostatic pressure conditions  

Microsoft Academic Search

Simultaneous application of high hydrostatic pressure (200–400MPa) during osmotic dehydration of strawberries was studied in this investigation. The high hydrostatic pressure treatment improved the diffusion coefficients of water and soluble solids compared to atmospheric pressure operation. Effects of process pressure on diffusion coefficients were achieved through an Arrhenius-type equation. Mathematical modeling of mass transfer was performed applying Newton, Henderson–Pabis, Page

Yissleen Nuñez-Mancilla; Mario Perez-Won; Antonio Vega-Gálvez; Viviana Arias; Gipsy Tabilo-Munizaga; Vilbett Briones-Labarca; Roberto Lemus-Mondaca; Karina Di Scala

2011-01-01

255

Hydrostatic pressure effects on vestibular hair cell afferents in fish and crustacea.  

PubMed

Following the discovery of a hydrostatic pressure sensor with no associated gas phase in the crab, and the knowledge that several systems of cells in culture show long term alterations to small changes in hydrostatic pressure, we show here that vestibular type II hair cells in a well known model system (the isolated elasmobranch labyrinth), are sensitive to hydrostatic pressure. This new finding for the vertebrate vestibular system may provide an explanation for low levels of resting activity in vertebrate hair cells and explain how fish without swim bladders sense hydrostatic cues. It could have implications for humans using their balancing systems in hypobaric or hyperbaric environments such as in aircraft or during space exploration. Although lacking the piston mechanism thought to operate in crab thread hairs which sense angular acceleration and hydrostatic pressure, the vertebrate system may use larger numbers of sensory cells with resultant improvement in signal to noise ratio. The main properties of the crab hydrostatic pressure sensing system are briefly reviewed and new experimental work on the isolated elasmobranch labyrinth is presented. PMID:15096667

Fraser, Peter J; Cruickshank, Stuart F; Shelmerdine, Richard L

2003-01-01

256

Hydraulic efficiency of a hydrostatic transmission with a variable displacement pump and motor  

NASA Astrophysics Data System (ADS)

Pumps and motors are commonly connected hydraulically to create hydrostatic drives, also known as hydrostatic transmissions. A typical hydrostatic transmission consists of a variable displacement pump and a fixed displacement motor. Maximum efficiency is typically created for the system when the motor operates at maximum volumetric displacement. The objective of this research is to determine if a hydrostatic transmission with a variable displacement motor can be more efficient than one with a fixed displacement motor. A work cycle for a Caterpillar 320D excavator was created and the efficiency of the hydrostatic drive system, controlling the swing circuit, with a fixed displacement motor was compared to the efficiency with a variable displacement motor. Both multiplicative and additive uncertainty analysis were performed to determine uncertainty models that could be used to analyze the robustness of the system with feedback control applied. A PID and an H? controller were designed for a position control model, as well as velocity control. It was found that while it may seem obvious to achieve maximum efficiency at maximum displacement, there are some cases where maximum efficiency is achieved at a lower displacement. It was also found that for the given work cycle, a hydrostatic transmission with a variable displacement motor can be more efficient.

Coombs, Daniel

257

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

SciTech Connect

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

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

1991-05-01

258

Lubricant effects on bearing life  

NASA Technical Reports Server (NTRS)

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.

Zaretsky, Erwin V.

1986-01-01

259

Hybrid superconductor magnet bearings  

NASA Technical Reports Server (NTRS)

Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

Chu, Wei-Kan

1995-01-01

260

Bear vs Bee  

NSDL National Science Digital Library

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

2012-01-01

261

Hybrid superconductor magnet bearings  

SciTech Connect

Hybrid superconductor magnet bearings (HSMB`s) utilize high temperature superconductors (HTS`s) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS`s, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, the authors present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

Chu, W.

1995-04-01

262

Tardigrada (Water Bears)  

NSDL National Science Digital Library

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

Micrographia

263

History of ball bearings  

NASA Technical Reports Server (NTRS)

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

Dowson, D.; Hamrock, B. J.

1981-01-01

264

Oregon Zoo Polar Bear  

USGS Multimedia Gallery

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

265

Magnetically leviated superconducting bearing  

DOEpatents

A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT)

1993-01-01

266

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

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

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

267

Renal interstitial hydrostatic pressure during pressure natriuresis in hypertension.  

PubMed

The objective of this study was to test the hypothesis that changes in renal perfusion pressure (RPP) are not fully transmitted to the renal interstitium in spontaneous hypertension in comparison with normotensive states. Okamoto spontaneously hypertensive and normotensive Wistar-Kyoto rats were used in this study. Renal interstitial hydrostatic pressure (RIHP) was measured directly and continuously via a polyethylene matrix that was implanted chronically in the left kidney 3 wk before RIHP measurement. When RPP was allowed to increase from 136 +/- 0.5 to 162 +/- 1.3 mmHg in male spontaneously hypertensive rats, RIHP was not significantly changed from 3.7 +/- 0.9 to 4.6 +/- 1.1 mmHg, and fractional excretion of sodium (FENa) increased significantly from 0.26 +/- 0.12 to 0.65 +/- 0.15% (P less than 0.05). When RPP was allowed to change from 104 +/- 0.9 to 127 +/- 1.3 mmHg in male Wistar-Kyoto rats, RIHP increased markedly from 4.0 +/- 0.3 to 7.2 +/- 0.4 mmHg (P less than 0.05), and FENa was significantly elevated from 0.27 +/- 0.08 to 2.02 +/- 0.55% (P less than 0.05). In conclusion, spontaneously hypertensive rats have a blunted increase in RIHP and pressure natriuresis response in comparison with Wistar-Kyoto rats. Thus, in Okamoto spontaneously hypertensive rats, the effect of RPP on RIHP is attenuated, leading to a blunted pressure natriuresis response. PMID:3189589

Khraibi, A A; Knox, F G

1988-11-01

268

Particle migration through sealed bearings  

SciTech Connect

Tests were performed to determine the ability of various types of shielded bearings to isolate particulate from a clean environment in support of the Direct Optical Initiation (DOI) program. In the DOI firing system, a stronglink mechanism will share the same environment with a high-powered laser which needs uncontaminated optics to perform properly. Two commercially available shielded and sealed bearings were tested along with a sealed bearing designed at Allied Signal Inc., Kansas City Division (KCD). The KCD-designed bearing proved to be the best barrier, but the torque required to function the bearing was magnitudes above the commercial bearings. The commercial sealed bearing was an effective barrier, allowing a small fraction of particles to migrate through, and had a relatively low running torque. The shielded bearing was not acceptable as a particle barrier.

Sundvold, P.D.

1993-08-01

269

Vygotsky and the Three Bears  

ERIC Educational Resources Information Center

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

Kulczewski, Peggy

2004-01-01

270

Magnetic bearings grow more attractive  

SciTech Connect

Advances in materials and electronics have enabled designers to devise simpler, smaller magnetic bearings. As a result, costs have dropped, widening the applications for these very-low-friction devices. Avcon (Advanced Controls Technology) has patented a permanent-magnet bias actively controlled bearing. Here high-energy rare earth permanent-magnet materials supply the basic bearing load levitation, while servo-driven electromagnets generate stabilization and centering forces for motion contol. Previous heavy-duty magnetic bearings used electromagnets entirely for suspension and control, which led to large bearings and control systems with higher power requirements. Avcon has developed several types of permanent-magnet bias bearings. The simplest is the radial repulsion bearing. Avcon's homopolar permanent-magnet bias active bearing is the most versatile of the company's designs.

Not Available

1993-10-01

271

A self-lubricating bearing  

NASA Technical Reports Server (NTRS)

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

Whitaker, A. F. (inventor)

1974-01-01

272

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

PubMed Central

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

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

2000-01-01

273

Carbon Nanotube Linear Bearing Nanoswitches  

E-print Network

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

Bockrath, Marc

274

Frictionless Bearing Uses Permanent Magnets  

NASA Technical Reports Server (NTRS)

The purpose of this innovation was to develop a frictionless bearing for high speed, light load applications. The device involves the incorporation of permanent magnets in the bearing design. The repulsion of like magnetic poles provides concentric support of the inner member so that no metallic contact occurs between the bearing surfaces.

1965-01-01

275

Notes 10. A thermohydrodynamic bulk-flow model for fluid film bearings  

E-print Network

important, low bulk modulues (LH2) c) Large pressure drops along axial direction with significant mass flow rates (annular damper seals & hydrostatic bearings ? up to 6,000 psig in cryogenic turbopumps) d) Large heat capacity for transport of energy along... for Cryogenic Applications," AIAA Journal of Propulsion and Power, Vol. 11, 5, pp. 964-972 San Andr?s, L., Yang, Z. and Childs, D., 1993, "Thermal Effects in Cryogenic Liquid Annular Seals, I: Theory and Approximate Solutions", ASME Journal of Tribology, Vol...

San Andres, Luis

2009-01-01

276

Passive magnetic bearing system  

DOEpatents

An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

Post, Richard F.

2014-09-02

277

Centrifugally decoupling touchdown bearings  

DOEpatents

Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

Post, Richard F

2014-06-24

278

The Polar Bear Game  

NSDL National Science Digital Library

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

2010-10-24

279

Dicey Polar Bears  

NSDL National Science Digital Library

In this Sketchpad activity, which opens on Geometer's Sketchpad and on iOS with Sketchbook Explorer (cataloged separately), 5 dice are shown and the player must determine how many polar bears are around the ice holes. The participant tries to figure out the riddle (rules of the game) by studying the dice arrangements and the answers that correspond. In this game, players also determine the number of fish and plankton.

Meehank

2011-07-03

280

Bears in a Boat  

NSDL National Science Digital Library

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

2012-06-14

281

Night of the Bear  

NSDL National Science Digital Library

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

Casey Debenham

2002-08-25

282

Highly integrated magnetic bearings  

SciTech Connect

Active Magnetic Bearings (AMB) have many advantages, compared to other bearing concepts. However, for many potential applications they are still too complicated and too expensive. In this paper the authors will present a new concept for active magnetic bearings with smaller dimensions, lower power consumption, and lower cost. To achieve this goal the system has been optimized in an overall mechatronic design. This led to new concepts for rotor, magnets, electronics and control. A single chip computer is used to reduce the number of electronic components. The switches of the voltage controlled power amplifier are driven directly by the PWM-unit of the single chip computer. Additionally, also the frequency inverter for the motor is driven directly by the PWM-unit. This leads to a minimum number of electronic components including the emergency power supply provided through energy recovered by the inverter. For development, calibration and error diagnostics a powerful serial link to a PC has been implemented. It works at a speed of 57.6 kBit/s and realizes a direct interface to MATLAB. This new configuration has been successfully applied to a small rotor system spinning at 60,000 rpm.

Buehler, P.; Siegwart, R. [ETH-Center, Zurich (Switzerland); Herzog, R. [Mecos Traxler AG, Winterthur (Switzerland)

1995-12-31

283

Anti-backlash gear bearings  

NASA Technical Reports Server (NTRS)

A gear bearing having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear bearing movement.

Vranish, John M. (Inventor)

2009-01-01

284

Bearing for liquid metal pump  

DOEpatents

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

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

1984-01-01

285

The influence and interactions of hydrostatic and osmotic pressures on the intracellular milieu of chondrocytes.  

PubMed

The intracellular milieu of chondroctyes is regulated by an array of proteins in the cell membrane which operate as transport pathways, allowing ions and nutrients such as glucose and amino acids and metabolites such as lactate to cross the plasma membrane. Here we investigated the influence of hydrostatic pressure on intracellular calcium concentrations ([Ca(2+)](i)) in isolated bovine articular chondrocytes. We found that short applications of high hydrostatic pressures led to a significant increase in [Ca(2+)](i). The pressure-induced rise was abolished for long (240 sec) but not short (30 sec) pressure applications by removal of extracellular Ca(2+). The rise in pressure was also blocked by the inhibitors neomycin and thapsigargin confirming that pressure, by generating IP(3), led to an increase in [Ca(2+)](i) by mobilising the pool of Ca(2+) ions contained within intracellular stores. We also found that intracellular [Na(+)] was affected by a rise in osmotic pressure and further affected by application of hydrostatic pressure. The effect of hydrostatic pressure on sulphate incorporation depended strongly on extracellular osmolality. Since significant gradients in extracellular osmolality exist across intact cartilage, the results imply that responses of chondrocytes to the same pressure will vary depending on location in the joint. The results also indicate that hydrostatic pressures can affect several different transporter systems thus influencing the intracellular milieu and chondrocyte metabolism. PMID:15299262

Browning, J A; Saunders, K; Urban, J P G; Wilkins, R J

2004-01-01

286

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

NASA Technical Reports Server (NTRS)

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

Navarro, Robert

1997-01-01

287

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

288

Effect of Bearing Cleaning on Long Term Bearing Life  

NASA Technical Reports Server (NTRS)

For many years chlorofluorocarbon (CFC) based solvents, such as CFC-113 and 1,1,1, trichloroethane (TCA), were used as bearing cleaning solvents for space mechanism bearings. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change requiring the use of ODC-free cleaners for precision bearing cleaning. With this change the question arises; what effect if any do these new cleaners have on long term bearing life? The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0 x 10(exp -6) torr) at a temperature of 90 C. Prior to testing the bearings were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing, the mass of each lubricated bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition, the bearings were visually examined and analyzed using an optical microscope.

Jett, Tim; Thom, R. L.

1999-01-01

289

Introgressive hybridization: brown bears as vectors for polar bear alleles.  

PubMed

The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. PMID:25775930

Hailer, Frank

2015-03-01

290

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

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

291

Practical applications of hydrostatic pressure to refold proteins from inclusion bodies for NMR structural studies.  

PubMed

Recently, the hydrostatic pressure refolding method was reported as a practical tool for solubilizing and refolding proteins from inclusion bodies; however, there have been only a few applications for protein structural studies. Here, we report the successful applications of the hydrostatic pressure refolding method to refold proteins, including the MOE-2 tandem zinc-finger, the p62 PB1 domain, the GCN2 RWD domain, and the mTOR FRB domain. Moreover, the absence of aggregation and the correct folding of solubilized protein samples were evaluated with size exclusion chromatography and NMR experiments. The analyses of NMR spectra for MOE-2 tandem zinc-finger and GCN2 RWD further led to the determination of tertiary structures, which are consistent with those from soluble fractions. Overall, our results indicate that the hydrostatic pressure method is effective for preparing samples for NMR structural studies. PMID:23525046

Ogura, Kenji; Kobashigawa, Yoshihiro; Saio, Tomohide; Kumeta, Hiroyuki; Torikai, Shinnosuke; Inagaki, Fuyuhiko

2013-06-01

292

Dialogue for Kids Wild About Bears Sleepy Bear Lesson Plan  

NSDL National Science Digital Library

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

293

High Hydrostatic Pressure for Disinfection of Bone Grafts and Biomaterials: An Experimental Study  

PubMed Central

Background: Autoclaving, heat, irradiation or chemical detergents are used to disinfect autografts, allografts and biomaterials for tissue reconstruction. These methods are often associated with deterioration of mechanical, physical, and biological properties of the bone grafts and synthetic implants. High hydrostatic pressure has been proposed as a novel method preserving biomechanical and biological properties of bone, tendon and cartilage. This is the first study to assess the inactivation of clinically relevant bacteria on biomaterials and human bone by high hydrostatic pressure. Methods: Bacterial suspensions of Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecium, implants covered with infected blood, human bone infected in vitro, and biopsies of patients with chronic osteomyelitis were subjected to different protocols of high hydrostatic pressure up to 600 MPa. Bacterial survival after high hydrostatic pressure treatment was determined and compared with bacterial growth in untreated controls. Results: S. aureus and P. aeruginosa in suspension were completely inactivated by high hydrostatic pressure (> 5log levels), whereas E. faecium showed barotolerance up to 600 MPa. Blood and adherence to metal implants did not significantly alter inactivation of bacteria, and complete disinfection was achieved with barotolerant bacteria (S. aureus and P. aeruginosa). However, osteoarthritic bone demonstrated a non-homogeneous baroprotective effect, with single bone samples resistant to treatment resulting in unaltered bacterial growth, and complete disinfection of artificially infected bone specimens was achieved in 66% for S. aureus, 60% for P. aeruginosa and 0% for E. faecium. Human bone samples of patients with chronic osteomyelitis could be completely disinfected in 2 of 37 cases. Conclusion: High hydrostatic pressure offers new perspectives for disinfection of sensitive biomaterials and bone grafts, and contamination by blood did not significantly affect bacterial inactivation rates. However, a significant baroprotective effect was demonstrated in bone. Effectiveness is currently limited to colonization and / or infection with barosensitive micro-organisms. PMID:19516918

Gollwitzer, Hans; Mittelmeier, Wolfram; Brendle, Monika; Weber, Patrick; Miethke, Thomas; Hofmann, Gunther O; Gerdesmeyer, Ludger; Schauwecker, Johannes; Diehl, Peter

2009-01-01

294

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

PubMed

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

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

2014-02-01

295

Aerospace applications of magnetic bearings  

NASA Technical Reports Server (NTRS)

Magnetic bearings have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic bearings have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.

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

1994-01-01

296

PNA bearing 5-azidomethyluracil  

PubMed Central

Fmoc- and Boc-protected modified monomers bearing 5-azidomethyluracil nucleobase were synthesized. Four different solid-phase synthetic strategies were tested in order to evaluate the application of this series of monomers for the solid-phase synthesis of modified PNA. The azide was used as masked amine for the introduction of amide-linked functional groups, allowing the production of a library of compounds starting from a single modified monomer. The azide function was also exploited as reactive group for the modification of PNA in solution via azide-alkyne click cycloaddition. PMID:22772040

Manicardi, Alex; Accetta, Alessandro; Tedeschi, Tullia; Sforza, Stefano; Marchelli, Rosangela; Corradini, Roberto

2012-01-01

297

Actively controlled superconducting bearings  

NASA Astrophysics Data System (ADS)

Actively controlled conventional radial beating using copper winding and soft magnetic material can provide only up to 200 N/sq cm of pressure. Large cryogenic pumps for space applications operating at 30,000 rpm and high rpm machines may require larger magnetic pressure. We show that using superconducting winding in the rotor and the stator of a magnetic bearing system increases the pressure by an order of magnitude. The paper addresses winding configuration, stability, ac losses, and power requirement for the superconducting winding.

Eyssa, Yehia M.; Huang, X.

298

Titan's Hydrostatic Figure and a Possible Dynamic Tidal Variation  

NASA Astrophysics Data System (ADS)

An archive of radio Doppler data from the Cassini mission can be found in NASA's PDS Atmospheres Node as a series of binary files called Orbit Data Files (ODF). We have downloaded six ODFs from the Cassini mission for six Titan gravity passes T11 (27-Feb-2006), T22 (28-Dec-2006), T33 (29-Jun-2007), T45 (31-Jul-2008), T68 (20-May-2010) and T74 (18-Feb-2011). After converting to text files with JPL space-navigation software (ODDUMP), we convert the observed Doppler shift for the Cassini spacecraft to radial velocity along the line of sight (LOS) at one-second sample interval. These data can be fit by a numerical integration of the equations of motion for the craft with respect to Titan, and a subsequent projection of the velocity so obtained along the LOS. The orbital parameters are represented by six standard Kepler elements with the plane of sky as the fundamental reference system, the system used for spectroscopic binary stars. While the systemic velocity Vs is taken as a constant for binary stars, it is represented for spacecraft by six parameters in a function developed for the Doppler detection of gravitational waves. We adopt well-determined values for the GM of Titan and Saturn and add a 13th gravity parameter C22 for an ellipsoidal hydrostatic Titan distorted by the Saturn tide and synchronous rotation (J2 = (10/3) C22). Also, we adopt the IAU definition for the pole and prime meridian of Titan in the ICRF/J2000 reference system. The interval of observation for each flyby is held to two hours, centered as closely as possible on the time of closest approach to Titan. This interval is sufficiently long for purposes of including all the detectable signal from C22, but short enough that spacecraft-generated translational forces can be neglected. By iterating on a linear least-squares system, 13 converged parameters and associated covariance matrix are found by singular-value decomposition of the least-squares design matrix for each of the six flybys. With reasonably good starting conditions from JPL's Horizons web site, convergence is achieved in about 10 iterations. The weighted mean of the six independent values of C22 is (10.479 ± 0.074) × 10-6, in good agreement with published values by the Cassini Radio Science Team, especially SOL1a at (10.121 ± 0.029) × 10-6. However, our independent analysis of the data does not result in a significantly improved fit when a 14th parameter, the Love number k2, is added to the parameter list. It seems that a dynamic tidal variation is not required in order to fit the data, even though it might very well represent a more realistic fitting model.

Anderson, J. D.; Schubert, G.

2012-12-01

299

Coexistence of Dirac and massive carriers in ?-(BEDT-TTF)2I3 under hydrostatic pressure  

NASA Astrophysics Data System (ADS)

Transport measurements were performed on the organic layered compound ?-(BEDT-TTF)2I3 under hydrostatic pressure. The carrier types, densities, and mobilities are determined from the magnetoconductance of ?-(BEDT-TTF)2I3. While evidence of high-mobility massless Dirac carriers has already been given, we report here their coexistence with low-mobility massive holes. This coexistence seems robust as it has been found up to the highest studied pressure. Our results are in agreement with recent DFT calculations of the band structure of this system under hydrostatic pressure. A comparison with graphene Dirac carriers has also been done.

Monteverde, M.; Goerbig, M. O.; Auban-Senzier, P.; Navarin, F.; Henck, H.; Pasquier, C. R.; Mézière, C.; Batail, P.

2013-06-01

300

Experimental investigation of the flow in a simplified model of water lubricated axial thrust bearing  

NASA Astrophysics Data System (ADS)

In hydropower plants the axial thrust bearing takes up the hydraulic axial thrust of the runner and, in case of vertical shafts, the entire weight of all rotating masses. The use of water lubricated bearings can eliminate the oil leakage risk possibly contaminating the environment. A complex flow is generated by the smaller film thickness due to the lower viscosity of water compared with oil. Measurements on a simplified hydrostatic axial trust bearing model were accomplished for validating CFD analysis of water lubricated bearings. In this simplified model, fixed pads are implemented and the width of the gap was enlarged to create a higher resolution in space for the measurements. Most parts of the model were manufactured from acrylic glass to get optical access for measurement with PIV. The focus of these measurements is on the flow within the space between two pads. Additional to the PIV- measurement, the pressure on the wall of the rotating disk is captured by pressure transducers. The model bearing measurement results are presented for varied operating conditions.

Kirschner, O.; Ruprecht, A.; Riedelbauch, S.

2014-12-01

301

Effect of Bearing Cleaning on Long Term Bearing Life  

NASA Technical Reports Server (NTRS)

For many years chlorofluorocarbon (CFC ) based solvents, such as Freon and 1,1,1, Trichloroethane (TCA), were used as bearing cleaning solvents for space mechanisms. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change to new ODC-free cleaners for the precision bearing cleaning. With this change the question arises what effect if any do these new cleaners have on long term bearing life. The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0* 10(exp -6) torr) at a temperature of 90C. Prior to testing the bearings were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing the mass of each lubricated bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition the bearings were visually examined and analyzed using an optical microscope.

Jett, Timothy Raymond; Thom, Robert L.

1998-01-01

302

Downhole bearing assembly  

SciTech Connect

A sealed downhole bearing assembly is described which consists of: an outer tube adapted to be connected to a first portion of a drill string; an inner tube adapted to be connected to a second portion of a drill string and disposed within the outer tube to define an enclosed annular space therebetween; at least one bearing mounted in the annular space between the outer and inner tubes to allow relative rotation therebetween; at least one high pressure seal mounted in the annular space between the outer and inner tubes to divide the annular space into first and second chambers; first and second abrasion resistant, metal-to-metal seals mounted between the inner and outer tubes to seal the first and second chambers, respectively, the first seal in fluid communication with an outer region exterior of the outer tube and the second seal in fluid communication with an inner region interior of the inner tube, the metal-to-metal seals adapted to seal effectively when in contact with drilling mud; first and second pressure balancing systems in communication with the first and second chambers, respectively, the first pressure balancing system also in communication with the outer region to balance pressure in the first chamber with respect to the outer region, the second pressure balancing system also in communication with the inner region to balance pressure in the second chamber with respect to the inner region; each of the pressure balancing systems comprising respective flexible, variable volume containers.

Lingafelter, J.

1986-06-10

303

Liquid hydrogen turbopump foil bearing  

NASA Technical Reports Server (NTRS)

Space transfer vehicles and other power and propulsion systems require long-life turbopumps. Rolling element bearings used in current turbopumps do not have sufficient life for these applications. Process fluid foil bearings have established long life, with exceptional reliability, over a wide range of temperatures and fluids in many high-speed turbomachinery applications. However, liquid hydrogen turbopumps require high-load capacity bearings. An experimental study was conducted to measure foil journal bearing load capacity in liquid hydrogen, using a bearing designed specifically for cryogenic hydrogen turbopump applications. Additional performance parameters such as power loss, stability, cooling flow requirements, and bearing life were measured. These tests showed a load capacity safety factor of approximately 10 for liquid hydrogen turbopump applictions. These tests also demonstrated good rotor stability, low power loss and cooling flow, and long life.

Saville, M.; Gu, A.; Capaldi, R.

1991-01-01

304

Primarily Pro-bear-bility  

NSDL National Science Digital Library

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

2006-01-01

305

Robust and intelligent bearing estimation  

DOEpatents

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

Claassen, John P. (Albuquerque, NM)

2000-01-01

306

Spin bearing retainer design optimization  

NASA Technical Reports Server (NTRS)

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

Boesiger, Edward A.; Warner, Mark H.

1991-01-01

307

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

E-print Network

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

Paris-Sud XI, Université de

308

Functional Improvement of Milk Whey Proteins Induced by High Hydrostatic Pressure  

Microsoft Academic Search

High pressure is emerging as a new processing technology that produces particular changes in the molecular structure of proteins and thus gives rise to new properties inaccessible via conventional methods of protein modification. This review deals with the main effects of high hydrostatic pressure on the physicochemical characteristics of milk whey proteins and how modifications in their structural properties contribute

Rosina López-Fandiño

2006-01-01

309

Effect of Hydrostatic Pressure Pulsing on the Inactivation of Salmonella Enteritidis in Liquid Whole Egg  

Technology Transfer Automated Retrieval System (TEKTRAN)

Salmonella in Eggs and egg-containing foods have caused numerous food-borne outbreaks and recalls. Liquid whole egg inoculated with Salmonella enteritidis at 108 CFU/ml were treated with continuous or repeating hydrostatic -pressures (300 MPa to 400 MPa) at 25C, 40C and 50C for up to 40 min. Treatme...

310

Inactivation of human norovirus in contaminated oysters and clams by high-hydrostatic pressure  

Technology Transfer Automated Retrieval System (TEKTRAN)

Human norovirus (NoV) is the most frequent causative agent of foodborne disease associated with shellfish consumption. In this study, the effect of high-hydrostatic pressure (HHP) on inactivation of NoV was determined. Genogroup I.1 (GI.1) or Genogroup II.4 (GII.4) NoV were inoculated into oyster ho...

311

Human norovirus inactivation in oysters by high hydrostatic pressure processing: A randomized double-blinded study  

Technology Transfer Automated Retrieval System (TEKTRAN)

This randomized, double-blinded, clinical trial assessed the effect of high hydrostatic pressure processing (HPP) on genogroup I.1 human norovirus (HuNoV) inactivation in virus-seeded oysters when ingested by subjects. The safety and efficacy of HPP treatments were assessed in three study phases wi...

312

Effects of high hydrostatic pressure on membrane proteins of Salmonella typhimurium  

Microsoft Academic Search

Salmonella typhimurium is a leading cause of foodborne diseases. Today high hydrostatic pressure treatments are considered as alternative methods of preservation. To select optimal conditions of treatment, we have to characterize the cell targets of pressure. In this study the action of pressure on the bacterial membrane proteins is analysed. The total membrane extract is obtained by lysis of cells

M Ritz; M Freulet; N Orange; M Federighi

2000-01-01

313

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

314

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

315

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

316

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

Microsoft Academic Search

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

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

2004-01-01

317

MCore: A non-hydrostatic atmospheric dynamical core utilizing high-order finite-volume methods  

E-print Network

discretizations so as to maintain accuracy in time and space and enforce a global CFL condition which is only-longitude grid and polar Fourier fil- tering, are no longer acceptable on large parallel systems since for discretizing the non-hydrostatic equations of motion on the sphere under the shallow-atmosphere approximation

Ullrich, Paul

318

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

319

Hydrostatic Pressure Affects In Vitro Maturation of Oocytes and Follicles and Increases Granulosa Cell Death  

PubMed Central

Objective: This study examines the effects of hydrostatic pressure on in vitro maturation (IVM) of oocytes derived from in vitro grown follicles. Materials and Methods: In this experimental study, preantral follicles were isolated from 12-day-old female NMRI mice. Each follicle was cultured individually in Alpha Minimal Essential Medium (?-MEM) under mineral oil for 12 days. Then, follicles were induced for IVM and divided into two groups, control and experiment. In the experiment group follicles were subjected to 20 mmHg pressure for 30 minutes and cultured for 24-48 hours. We assessed for viability and IVM of the oocytes. The percentage of apoptosis in cumulus cells was determined by the TUNEL assay. A comparison between groups was made using the student’s t test. Results: The percentage of metaphase II oocytes (MII) increased in hydrostatic pressuretreated follicles compared to controls (p<0.05). Cumulus cell viability reduced in hydrostatic pressure-treated follicles compared to controls (p<0.05). Exposure of follicles to pressure increased apoptosis in cumulus cells compared to controls (p<0.05). Conclusion: Hydrostatic pressure, by inducing apoptosis in cumulus cells, participates in the cumulus oocyte coupled relationship with oocyte maturation. PMID:24381852

Rashidi, Zahra; Azadbakht, Mehri; Amini, Ali; Karimi, Isac

2014-01-01

320

Transcriptomics Reveal Several Gene Expression Patterns in the Piezophile Desulfovibrio hydrothermalis in Response to Hydrostatic Pressure  

PubMed Central

RNA-seq was used to study the response of Desulfovibrio hydrothermalis, isolated from a deep-sea hydrothermal chimney on the East-Pacific Rise at a depth of 2,600 m, to various hydrostatic pressure growth conditions. The transcriptomic datasets obtained after growth at 26, 10 and 0.1 MPa identified only 65 differentially expressed genes that were distributed among four main categories: aromatic amino acid and glutamate metabolisms, energy metabolism, signal transduction, and unknown function. The gene expression patterns suggest that D. hydrothermalis uses at least three different adaptation mechanisms, according to a hydrostatic pressure threshold (HPt) that was estimated to be above 10 MPa. Both glutamate and energy metabolism were found to play crucial roles in these mechanisms. Quantitation of the glutamate levels in cells revealed its accumulation at high hydrostatic pressure, suggesting its role as a piezolyte. ATP measurements showed that the energy metabolism of this bacterium is optimized for deep-sea life conditions. This study provides new insights into the molecular mechanisms linked to hydrostatic pressure adaptation in sulfate-reducing bacteria. PMID:25215865

Amrani, Amira; Bergon, Aurélie; Holota, Hélène; Tamburini, Christian; Garel, Marc; Ollivier, Bernard; Imbert, Jean; Dolla, Alain; Pradel, Nathalie

2014-01-01

321

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

322

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

E-print Network

Non-Hydrostatic Wave Model NHWAVE User's Guide for Modeling Submarine Landslide Tsunami ( Version 1 of submarine landslide-induced tsunami waves. NHWAVE was de- veloped by Ma et al. (2012) for modeling fully landslide can be directly simulated by taking advantage of the coordinate system. The model assumes

Kirby, James T.

323

Microbiological food safety assessment of high hydrostatic pressure processing: A review  

Microsoft Academic Search

High hydrostatic pressure (HHP) processing as a novel non-thermal method has shown great potential in producing microbiologically safer products while maintaining the natural characteristics of the food items. Scientific research of the process and its industrial applications has been widespread in the past two decades with many scientific publications describing its uses, advantages and limitations. The review describes the effect

E. Rendueles; M. K. Omer; O. Alvseike; C. Alonso-Calleja; R. Capita; M. Prieto

2011-01-01

324

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

325

PERITONEAL FLUID AND TRACER ALBUMIN KINETICS IN THE RAT. EFFECTS OF INCREASES IN INTRAPERITONEAL HYDROSTATIC PRESSURE  

Microsoft Academic Search

.Objectives: To study the peritoneal fluid loss rate, the clearance (CI) of radioactive tracer albumin (RISA) eliminated from the peritoneal cavity (PC), as well as the peritoneal-to-plasma RISA clearance (CI -+ P) during acute peritoneal dialysis (PD) at large elevations in intraperitone al hydrostatic pressure (IPP). .Design: Experimental study in anesthetized Wistar rats. .Methods: The intraperitoneal volume (IPV) was assessed

EL Rasheid Zakaria; Bengt Rippe

326

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

327

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

ERIC Educational Resources Information Center

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

Pelton, Rick; Espy, John

328

The polar bear phenomena  

SciTech Connect

Results from measuring the thermal profile of polar bear pelts, reflectiveness of the pelts, and total thermal conversion data lead to the conclusion that the pelts from an ultra-efficient thermal diode for solar-thermal conversion. The transfer of the thermal energy from the surface of the fur to the skin where it is absorbed cannot be thermal, and therefore must be radiative. This process must have an efficiency of better than 90:0090 percent to account for measured values. The radiative transfer process is not known at present. To understand it, a detailed knowledge of the microscopic parameters of the pelts must be obtained. This is the current thrust of the polar solar research. If the process can be understood and synthesized,it will provide a major breakthrough in the area of solar-thermal energy conversion.

Maw, P.K. (United Kingdom Ingersoll-Rand Sales Company, Ltd., Horwich, Bolton Lancashire, BL6 6JN (GB)); Lane, M.T.

1990-02-01

329

Superconducting levitating bearing  

NASA Technical Reports Server (NTRS)

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

Moon, Francis C. (Inventor)

1996-01-01

330

Introduction to magnetic bearings  

NASA Technical Reports Server (NTRS)

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

Skowronski, Lori; Bisese, Anne

1993-01-01

331

Permanent-Magnet Meissner Bearing  

NASA Technical Reports Server (NTRS)

Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

Robertson, Glen A.

1994-01-01

332

Spherical-Bearing Analysis Program  

NASA Technical Reports Server (NTRS)

Computer program SPHERBEAN, developed to predict thermomechanical performance characteristics of double-row spherical roller bearings over wide range of operating conditions. Analysis allows six degrees of freedom for each roller and three for each half of an optionally split cage. Program capabilities provide sufficient generality to allow detailed simulation of both high-speed and conventional bearing operation.

Kleckner, R. J.

1984-01-01

333

Polar Bears and Climate Change  

NSDL National Science Digital Library

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

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

2008-05-01

334

Nonlinear control of magnetic bearings  

NASA Technical Reports Server (NTRS)

In this paper we present a variety of nonlinear controllers for the magnetic bearing that ensure both stability and robustness. We utilize techniques of discontinuous control to design novel control laws for the magnetic bearing. We present in particular sliding mode controllers, time optimal controllers, winding algorithm based controllers, nested switching controllers, fractional controllers, and synchronous switching controllers for the magnetic bearing. We show existence of solutions to systems governed by discontinuous control laws, and prove stability and robustness of the chosen control laws in a rigorous setting. We design sliding mode observers for the magnetic bearing and prove the convergence of the state estimates to their true values. We present simulation results of the performance of the magnetic bearing subject to the aforementioned control laws, and conclude with comments on design.

Pradeep, A. K.; Gurumoorthy, R.

1994-01-01

335

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

PubMed

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

Fambri, Francesco; Dumbser, Michael; Casulli, Vincenzo

2014-11-01

336

Bears, Big and Little. Young Discovery Library Series.  

ERIC Educational Resources Information Center

This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

Pfeffer, Pierre

337

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Bear orientation. 13.1236 Section 13.1236...Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

2012-07-01

338

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Bear orientation. 13.1236 Section 13.1236...Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

2013-07-01

339

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

340

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

341

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2014 CFR

... 2014-07-01 false Bear orientation. 13.1236 Section 13.1236...Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

2014-07-01

342

USGS Scientist Taking Measurements Along Bear Creek  

USGS Multimedia Gallery

USGS Scientist Taking Measurements Along Bear Creek - Photo taken by Heidi Koontz, USGS Communications, Friday, Sept. 13. USGS scientist Ben Glass conducting current profiler measurements along Bear Creek near Bear Creek Lake in Morrison, Colo....

343

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

344

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2014 CFR

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

2014-10-01

345

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

346

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

347

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

348

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Side bearings. 229.69 Section 229.69 Transportation...Requirements Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight...

2011-10-01

349

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Side bearings. 229.69 Section 229.69 Transportation...Requirements Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight...

2013-10-01

350

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

351

Magnetic Bearings at Draper Laboratory  

NASA Technical Reports Server (NTRS)

Magnetic bearings, unlike traditional mechanical bearings, consist of a series of components mated together to form a stabilized system. The correct design of the actuator and sensor will provide a cost effective device with low power requirements. The proper choice of a control system utilizes the variables necessary to control the system in an efficient manner. The specific application will determine the optimum design of the magnetic bearing system including the touch down bearing. Draper for the past 30 years has been a leader in all these fields. This paper summarizes the results carried out at Draper in the field of magnetic bearing development. A 3-D radial magnetic bearing is detailed in this paper. Data obtained from recently completed projects using this design are included. One project was a high radial load (1000 pound) application. The second was a high speed (35,000 rpm), low loss flywheel application. The development of a low loss axial magnetic bearing is also included in this paper.

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

1996-01-01

352

Random bearings and their stability.  

PubMed

Self-similar space-filling bearings have been proposed some time ago as models for the motion of tectonic plates and appearance of seismic gaps. These models have two features which, however, seem unrealistic, namely, high symmetry in the arrangement of the particles, and lack of a lower cutoff in the size of the particles. In this work, an algorithm for generating random bearings in both two and three dimensions is presented. Introducing a lower cutoff for the sizes of the particles, the instabilities of the bearing under an external force such as gravity, are studied. PMID:16384225

Mahmoodi Baram, Reza; Herrmann, Hans J

2005-11-25

353

Using a Bear Put Spread  

E-print Network

might be used when the marketer is bearish on a market to a point (i.e., the marketer believes the market has limited downside risk). An attractive feature of the bear put spread is that once the strike prices are selected and the premiums are known..., the maximum loss and net potential gain from the spread are also known. When to Use a Bear Put Spread A producer can use a bear put spread to hedge against a falling market. However, if the market falls below the strike price of the sold put op- tion...

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

2008-10-07

354

Flex bearing UUEC, volume 2  

NASA Technical Reports Server (NTRS)

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

Clapper, M. L.

1993-01-01

355

Mixed-mu superconducting bearings  

DOEpatents

A mixed-mu superconducting bearing is disclosed including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure. 9 figs.

Hull, J.R.; Mulcahy, T.M.

1998-03-03

356

Mixed-mu superconducting bearings  

DOEpatents

A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

Hull, John R. (Hinsdale, IL); Mulcahy, Thomas M. (Western Springs, IL)

1998-01-01

357

ATM CMG bearing failure analysis  

NASA Technical Reports Server (NTRS)

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

1975-01-01

358

Analytic theory of hydrostatic stress effect on switching dynamics in ferroelectrics  

NASA Astrophysics Data System (ADS)

Polarization switching of ferroelectric materials is influenced by extensive variables such as electric field, temperature and stress. Currently a variety of theoretical approaches are used to gain a deeper understanding of the influence of extensive variables on the dynamic properties of ferroelectrics. In this paper a Landau-type model for second order bulk materials is used to study the extent to which hydrostatic stress affects the switching dynamic behaviours in ferroelectric material. Exact expressions for equilibrium polarization and switching time are derived analytically and then used to examine the dynamic behaviour in regimes of high electric field and hydrostatic stress. The second aspect of this work is to determine the relationship between empirical rules used to describe dynamic behaviour with the exact expressions derived from this model.

Loh, Kok-Khuan; Ong, Lye-Hock; Chew, Khian-Hooi

2014-07-01

359

The effect of hydrostatic pressure fields on the dispersion characteristics of fluid-shell coupled system  

NASA Astrophysics Data System (ADS)

The effect of hydrostatic pressure on the vibration dispersion characteristics of fluid-shell coupled structures was studied. Both fluid-loaded cylindrical shells and fluid-filled cylindrical shells were considered. Numerical analysis was applied to solve the dispersion equations for shells filled with or loaded with fluid at various hydrostatic pressures. The results for external pressure showed that non-dimensional axial wave numbers are nearly independent when the pressure is below the critical level. The influence of internal pressure on wave numbers was found significant for the real branch s=1 and the complex branches of dispersion curves. The presence of internal pressure increased the cut on frequencies for the branch s=1 for high order wave modes.

Liu, Zhi-Zhong; Li, Tian-Yun; Zhu, Xiang; Zhang, Jun-Jie

2010-06-01

360

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

361

Enhanced Superconductivity on the Tetragonal Lattice in FeSe under Hydrostatic Pressure  

NASA Astrophysics Data System (ADS)

Superconductivity under pressure in FeSe (Tc ~ 7.5 K) has been investigated using single-crystal specimens through the measurements of DC magnetization and electrical resistivity. A characteristic three-step increase in Tc has been found under hydrostatic pressure up to ~34 K above 7 GPa. The structural transition from a tetragonal phase to an orthorhombic phase (Ts ~ 87 K) is found to disappear at P ~ 2.3 GPa, above which Tc increases rapidly, suggesting that the superconductivity is enhanced by the tetragonal environment. Under non-hydrostatic pressure, the increase in Tc is suppressed and the superconductive volume fraction is considerably reduced above 2 GPa, probably owing to the breaking of the tetragonal lattice symmetry by the uniaxial stress. The intimate correlation between the enhanced (suppressed) superconductivity and the tetragonality (orthorhombicity) in the phase diagram is a common feature of FeSe and other iron-pnictide superconductors.

Miyoshi, Kiyotaka; Morishita, Koh; Mutou, Eriko; Kondo, Masatoshi; Seida, Osamu; Fujiwara, Kenji; Takeuchi, Jun; Nishigori, Shijo

2014-01-01

362

Zinc phosphate chain length study under high hydrostatic pressure by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The aim of this study is to combine a diamond anvil cell with in-situ Raman spectroscopy to simulate and analyze the effect of pure pressure on the length of phosphate chains in an antiwear film formed in a tribological contact. In-situ Raman spectra of Zn2P2O7 glass, ?-Zn3(PO4)2, and ?-Zn2P2O7 crystals submitted to high hydrostatic pressure up to 20 GPa were recorded. Evolution of Raman spectra as a function of pressure was studied in the characteristic high frequency range of PO4 tetrahedra molecular resonance (650-1300 cm-1). When exposed to high pressure, the structure of the sample becomes less ordered. Phase transitions in ?-Zn3(PO4)2 structure are observed during compression from ambient pressure to 3 GPa. The length of the phosphate chains is conserved up to 20 GPa when samples are subjected to hydrostatic pressure.

Gauvin, M.; Dassenoy, F.; Minfray, C.; Martin, J. M.; Montagnac, G.; Reynard, B.

2007-03-01

363

Teddy Bear Line-Up  

NSDL National Science Digital Library

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

364

Lateral dampers for thrust bearings  

NASA Technical Reports Server (NTRS)

The development of lateral damping schemes for thrust bearings was examined, ranking their applicability to various engine classes, selecting the best concept for each engine class and performing an in-depth evaluation. Five major engine classes were considered: large transport, military, small general aviation, turboshaft, and non-manrated. Damper concepts developed for evaluation were: curved beam, constrained and unconstrained elastomer, hybrid boost bearing, hydraulic thrust piston, conical squeeze film, and rolling element thrust face.

Hibner, D. H.; Szafir, D. R.

1985-01-01

365

Improved Superconducting Magnetic Rotary Bearings  

NASA Technical Reports Server (NTRS)

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

Flom, Yury; Royston, James

1992-01-01

366

Testing and Lubrication for Single Race Bearings  

SciTech Connect

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.

Steinhoff, R.G.

1998-03-04

367

Cholesteric Liquid Crystal Sensing of High Hydrostatic Pressure Utilizing Optical Fibers  

Microsoft Academic Search

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

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

1991-01-01

368

Density Measurement of Tridecane by using Hydrostatic Weighing System at Density Laboratory, NML-SIRIM  

NASA Astrophysics Data System (ADS)

This paper presents the density measurement of tridecane by using hydrostatic weighing system, which is currently practised in Density Laboratory of National Metrology Laboratory (NML), SIRIM Berhad. This system weighed the crystal sphere while the crystal sphere was immersed in the tridecane. The volume and mass in air of the crystal sphere were calibrated at KRISS, Korea. The uncertainties of volume and mass in air of the crystal sphere were 4 ppm and 0.3 ppm respectively.

Nor, Mohd. Fazrul Hisyam Mohd.; Othman, Hafidzah; Abidin, Abd. Rashid Zainal

2009-07-01

369

Anisotropic Nanoclustered Carbon Phases Prepared from Fullerite C60 Under Non?hydrostatic High Pressure  

Microsoft Academic Search

We show that application of the non?hydrostatic pressure to the cluster?based molecular material, like fullerite C60, provides a new opportunity to create elastically and structurally anisotropic carbon materials, including 2D polymerized rhombohedral C60 and graphite?type (sp ) disordered atomic?based phases. The elastic anisotropy, detected by the difference in the ultrasound velocities propagating along and across the loading axis, is directly

A. G. Lyapin; V. V. Mukhamadiarov; V. V. Brazhkin; M. V. Kondrin; S. V. Popova; Ye. V. Tatyanin; S. C. Bayliss; A. V. Sapelkin

2005-01-01

370

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

SciTech Connect

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

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

2009-07-24

371

Some theoretical considerations concerning hydrostatic pressure-induced deformation in anisotropic metals  

Microsoft Academic Search

The macroscopic yielding of solid state may be described by the following yield criterion: f(Ï{sub ij}) = 0, where f is a function of the components of the stress tensor Ï{sub ij}. The Huber-Mises quadratic in the stresses criterion, being predicated upon the assumption that the superposition of hydrostatic loading Ï{sub ij} does not influence yielding âf Ï{sub ij}\\/âÏâ =

A. V. Shmakov; A. A. Kuzmenkov

1995-01-01

372

DETECTION OF A BIPOLAR MOLECULAR OUTFLOW DRIVEN BY A CANDIDATE FIRST HYDROSTATIC CORE  

SciTech Connect

We present new 230 GHz Submillimeter Array observations of the candidate first hydrostatic core Per-Bolo 58. We report the detection of a 1.3 mm continuum source and a bipolar molecular outflow, both centered on the position of the candidate first hydrostatic core. The continuum detection has a total flux density of 26.6 {+-} 4.0 mJy, from which we calculate a total (gas and dust) mass of 0.11 {+-} 0.05 M{sub Sun} and a mean number density of 2.0 {+-} 1.6 Multiplication-Sign 10{sup 7} cm{sup -3}. There is some evidence for the existence of an unresolved component in the continuum detection, but longer-baseline observations are required in order to confirm the presence of this component and determine whether its origin lies in a circumstellar disk or in the dense inner envelope. The bipolar molecular outflow is observed along a nearly due east-west axis. The outflow is slow (characteristic velocity of 2.9 km s{sup -1}), shows a jet-like morphology (opening semi-angles {approx}8 Degree-Sign for both lobes), and extends to the edges of the primary beam. We calculate the kinematic and dynamic properties of the outflow in the standard manner and compare them to several other protostars and candidate first hydrostatic cores with similarly low luminosities. We discuss the evidence both in support of and against the possibility that Per-Bolo 58 is a first hydrostatic core, and we outline future work needed to further evaluate the evolutionary status of this object.

Dunham, Michael M.; Chen Xuepeng; Arce, Hector G. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States); Bourke, Tyler L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Schnee, Scott [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Enoch, Melissa L., E-mail: michael.dunham@yale.edu [Department of Astronomy, University of California at Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States)

2011-11-20

373

The hydrostatic\\/hydrodynamic behaviour of an axial piston pump slipper with multiple lands  

Microsoft Academic Search

This study considers an analytical approach towards the understanding of the hydrostatic leakage and lift characteristic of\\u000a a flat slipper of the type used for piston\\/slipper units within an axial piston pump or motor. In particular it considers\\u000a a slipper design incorporating a groove on the slipper face and also includes the effect of motion around its associated swash\\u000a plate.

J. M. Bergada; J. Watton; J. M. Haynes; D. L. Davies

2010-01-01

374

COORDINATION OF RESPIRATORY AND HYDROSTATIC FUNCTIONS OF THE SWIMBLADDER IN THE CENTRAL MUDMINNOW, UMBRA LIMI  

Microsoft Academic Search

SUMMARY 1. Observations of behaviour and changes in buoyancy of Umbra limi, a facultative air-breathing fish, were studied to understand coordination of respiratory and hydrostatic functions of the swimbladder. 2. Fish were exposed to either normoxic or hypoxic water in either undisturbed or disturbed (simulating predator presence) conditions. Declines in swimbladder volume occurred between air-breaths as O2 was removed. These

JOHN H. GEE

375

Method for correcting laboratory model deep-well disposal system data for hydrostatic pressure effects.  

PubMed

A pressure chamber for determining the effect of increased hydrostatic pressure on growth and metabolic activities of groundwater bacteria is described. The chamber was used to show that moderate increases in pressure (to about 100 atmospheres) result in increased growth of mixed cultures of industrial-injection-well bacteria and in the more complete degradation of formate and nitrate by these bacteria, as compared with identical cultures at atmospheric pressure. PMID:16345295

Horvath, E; Elkan, G H

1978-06-01

376

M. Bahrami ENSC 283 Tutorial # 3 1 ENSC 283 Week # 4, Tutorial # 3 Hydrostatic Forces  

E-print Network

M. Bahrami ENSC 283 Tutorial # 3 1 ENSC 283 Week # 4, Tutorial # 3­ Hydrostatic Forces Problem 1: Prepare a data table Data Value Unit 4 2 Water 2 m O z x 4 m D B C A #12;M. Bahrami ENSC 283 Tutorial # 3. Bahrami ENSC 283 Tutorial # 3 3 , sin 1 12 1 2 sin 90° 5 2 0.0667 (Eq7) Note that , is calculated

Bahrami, Majid

377

A refined semi-Lagrangian vertical trajectory scheme applied to a hydrostatic atmospheric model  

NASA Astrophysics Data System (ADS)

An explicit estimate of the vertical acceleration in a hydrostatic atmospheric model is necessary in order to extend the application of the uniform acceleration two-time-level semi-Lagrangian trajectory scheme of Gospodinov et al. to the vertical direction. It has been diagnosed from the continuity equation. The trajectory scheme proposed, together with the vertical acceleration, has been tested for the so-called 'Baltic jet' case which is dominated by horizontal advection. Enhanced quality has been demonstrated.

Gospodinov, I.; Spiridonov, V.; Bénard, P.; Geleyn, J. F.

2002-01-01

378

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

Microsoft Academic Search

The efficacy of pulsed ultraviolet light (PUV) and high hydrostatic pressure (HHP) on the IgE binding to the almond extracts\\u000a was studied using sodium dodecyl sulfate polyacrylamide-gel electrophoresis, Western blot, and enzyme-linked immunosorbent\\u000a assay (ELISA) probed with human plasma containing IgE antibodies to almond allergens and a polyclonal antibody against almond\\u000a major protein. Crude almond protein extracts were treated with

Yiqiao Li; Wade Yang; Si-Yin Chung; Haiqiang Chen; Mu Ye; Arthur A. Teixeira; Jesse F. Gregory; Bruce A. Welt; Sandra Shriver

379

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

Microsoft Academic Search

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

Daniela Bermúdez-Aguirre; Gustavo V. Barbosa-Cánovas

2011-01-01

380

Order-disorder phase transition in CdAl 2S 4 under hydrostatic pressure  

Microsoft Academic Search

CdAl2S4 single crystals with the defect chalcopyrite structure have been studied by Raman spectroscopy at hydrostatic pressures up to 150 kbar. The Raman scattering spectra were found to undergo substantial changes around 60 and 100 kbar, due to an order-disorder transition in the cation sublattice, which occurs in two stages as predicted earlier. From the pressure dependence of optical phonon

I. I. Burlakov; Y. Raptis; V. V. Ursaki; E. Anastassakis; I. M. Tiginyanu

1997-01-01

381

Effect of high hydrostatic pressure on physicochemical and biochemical properties of milk  

Microsoft Academic Search

Interest in high hydrostatic pressure (HHP) applications on milk and dairy products has recently increased as HHP offers a\\u000a new technology for food preservation to the food industry. Although HHP-induced microbial destruction, rennet or acid coagulation\\u000a of milk and increase in cheese yield has been reported, the actual effect of HHP application on milk constituents still remains\\u000a to be unexplained.

Ergin Murat Altuner; Hami Alpas; Yasar Kemal Erdem; Faruk Bozoglu

2006-01-01

382

Responses of Some Marine Plankton Animals to Changes in Hydrostatic Pressure  

Microsoft Academic Search

IT has generally been thought that aquatic animals, which lack gas-filled spaces in their bodies, would not perceive variations in hydrostatic pressure due to small changes in depth, since their bodies are permeated with fluid of very slight compressibility1. Only animals possessing gas-filled spaces, such as fishes, with their swim bladders2, and certain aquatic insects, with special pressure gauges connected

E. W. Knight-Jones; S. Z. Qasim

1955-01-01

383

The Effect of Size and Species on Lens Intracellular Hydrostatic Pressure  

PubMed Central

Purpose. Previous experiments showed that mouse lenses have an intracellular hydrostatic pressure that varied from 335 mm Hg in central fibers to 0 mm Hg in surface cells. Model calculations predicted that in larger lenses, all else equal, pressure should increase as the lens radius squared. To test this prediction, lenses of different radii from different species were studied. Methods. All studies were done in intact lenses. Intracellular hydrostatic pressures were measured with a microelectrode-manometer–based system. Membrane conductances were measured by frequency domain impedance analysis. Intracellular Na+ concentrations were measured by injecting the Na+-sensitive dye sodium-binding benzofuran isophthalate. Results. Intracellular hydrostatic pressures were measured in lenses from mice, rats, rabbits, and dogs with radii (cm) 0.11, 0.22, 0.49, and 0.57, respectively. In each species, pressure varied from 335 ± 6 mm Hg in central fiber cells to 0 mm Hg in surface cells. Further characterization of transport in lenses from mice and rats showed that the density of fiber cell gap junction channels was approximately the same, intracellular Na+ concentrations varied from 17 mM in central fiber cells to 7 mM in surface cells, and intracellular voltages varied from ?45 mV in central fiber cells to ?60 mV in surface cells. Fiber cell membrane conductance was a factor of 2.7 times larger in mouse than in rat lenses. Conclusions. Intracellular hydrostatic pressure is an important physiological parameter that is regulated in lenses from these different species. The most likely mechanism of regulation is to reduce the density of open Na+-leak channels in fiber cells of larger lenses. PMID:23211824

Gao, Junyuan; Sun, Xiurong; Moore, Leon C.; Brink, Peter R.; White, Thomas W.; Mathias, Richard T.

2013-01-01

384

Induction of Shiga Toxin-Converting Prophage in Escherichia coli by High Hydrostatic Pressure  

Microsoft Academic Search

Since high hydrostatic pressure is becoming increasingly important in modern food preservation, its potential effects on microorganisms need to be thoroughly investigated. In this context, mild pressures (<200 MPa) have recently been shown to induce an SOS response in Escherichia coli MG1655. Due to this response, we observed a RecA- and LexA-dependent induction of lambda prophage upon treating E. coli

Abram Aertsen; David Faster; Chris W. Michiels

2005-01-01

385

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

SciTech Connect

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

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

2013-11-10

386

Disinfection Procedure for Water Distribution Pipelines Drinking water contamination can be prevented by hydrostatic testing and disinfection of  

E-print Network

Disinfection Procedure for Water Distribution Pipelines Drinking water contamination can be prevented by hydrostatic testing and disinfection of potable water distribution pipelines before connecting pipeline connections to the system, and respond to requests for drinking water assessments. And, any

de Lijser, Peter

387

Hydrostatic pressure induced splitting of recombination luminescence band in KTaO 3 : Manifestation of charge transfer vibronic exciton phase  

NASA Astrophysics Data System (ADS)

Hydrostatic pressure induced splitting of luminescence transitions under UV photoexcitation was observed in KTaO 3 crystal. Two additional satellite bands of recombination luminescence arise at lower and higher energies with approximately the same shift with respect to the initial central band position. After the appearance of satellites at elevated hydrostatic pressures (1.9-6.1 GPa), the luminescence band shape does not exhibit any significant change with further increasing of the applied pressure up to 12.7 GPa. This effect is explained by light-induced occupation of Charge Transfer Vibronic Exciton (CTVE) ferroelectric phase. CTVE-phase occupation increases with hydrostatic pressure up to its proximity to the free CTVE level. Saturated ferroelectric order parameter of this phase splits the recombination luminescence band with two satellites' appearance. Hydrostatic pressure induced satellites in recombination luminescence can be considered as the CTVE-phase manifestation for KTaO 3 crystal.

Vikhnin, V. S.; Kutsenko, A. B.; Kapphan, S. E.

2006-12-01

388

The effect of hydrostatic pressure on the combustion synthesis of Y 2O 3:Bi nanophosphor  

NASA Astrophysics Data System (ADS)

The effects of pressurized Ar environments during the solution combustion synthesis (SCS) of Y 2O 3:Bi nanophosphor were investigated. Three fuels were used urea, glycine and hexamethylenetetramine (HMT) and the nanopowders were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence, fluorescence lifetime, and thermoluminescence measurements. The dominant crystallographic phase was cubic, with crystallite size being insensitive to the hydrostatic pressure but increasing for fuels with higher heat of combustion. At least for nanopowders obtained using fuels with higher heats of combustion, higher Ar hydrostatic pressures lead to lower photoluminescence output. Fluorescence lifetime measurements on HMT-prepared samples yielded lifetimes of 330 and 900 ns for Bi 3+ ions in S 6 and C 2 sites, respectively, and no variation in these values was observed for hydrostatic pressures from 0.1 to 9.7 MPa. Shorter lifetime values than reported for conventional SCS are likely related to higher concentration of quenching defects. In agreement with these results, thermoluminescence measurements showed that higher concentrations of electronic traps are present in samples synthesized under higher pressures.

Jacobsohn, L. G.; Tappan, B. C.; Tornga, S. C.; Blair, M. W.; Luther, E. P.; Mason, B. A.; Bennett, B. L.; Muenchausen, R. E.

2010-03-01

389

Hydrostatic pressure effect on micro air bubbles deposited on surfaces with a retreating tip.  

PubMed

The effect of hydrostatic pressure on 6 ?L air bubbles formed on micropillar structured PDMS and silicone surfaces using a 2 mm diameter stainless steel tip retreated at 1 mm/s was investigated. Dimensional analysis of the tip retraction process showed the experiments to be conducted in the condition where fluid inertial forces are comparable in magnitude with surface tension forces, while viscous forces were lower. Larger bubbles could be left behind on the structured PDMS surface. For hydrostatic pressures in excess of 20 mm H2O (196 Pa), the volume of bubble deposited was found to decrease progressively with pressure increase. The differences in width of the deposited bubbles (in contact with the substrate) were significant at any particular pressure but marginal in height. The attainable height before rupture reduced with pressure increase, thereby accounting for the reducing dispensed volume characteristic. On structured PDMS, the gaseous bridge width (in contact with the substrate) was invariant with tip retraction, while on silicone it was initially reducing before becoming invariant in the lead up to rupture. With silicone, hence, reductions in the contact width and height were both responsible for reduced volumes with pressure increase. Increased hydrostatic pressure was also found to restrict the growth in contact width on silicone during the stage when air was injected in through the tip. The ability to effect bubble size in such a simple manner may already be harnessed in nature and suggests possibilities in technological applications. PMID:24810460

Huynh, So Hung; Wang, Jingming; Yu, Yang; Ng, Tuck Wah

2014-06-01

390

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

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

391

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

PubMed Central

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

Marietou, Angeliki

2014-01-01

392

Stability of finite journal bearings from bearings--linear and nonlinear bearing forces  

NASA Astrophysics Data System (ADS)

The paper investigates the relationship between the stability contour determined from the nonlinear simulation and that from the linear theory. The nonlinear bearing forces are directly obtained from the bearing pressure distribution which is solved from the Reynolds equation at each journal position. It is found that the critical speeds in the case of nonlinear bearing forces are the same as those predicted by the linear theory, although the whirl loci under large dynamic excitations are significantly different from those arising from the linear bearing forces. Typical whirling trajectories under impact excitation, positionperturbation and synchronous unbalance excitations are simulated and presented to explain the stable, critical and unstable phenomena. The whirl displacement signals are also transformed to the frequency domain, and their whirling frequencies are analyzed according to their frequency characteristics.

Tieu, A. K.; Qiu, Z. L.

1995-07-01

393

Journal gas bearing for curved surfaces  

NASA Technical Reports Server (NTRS)

Optimizing bearing length and permissible axis curvature alleviates distortion of film gap of gas lubricated journal bearing in deployment mechanisms. Required bearing length is divided into two shorter bearings interconnected by links which allow satisfactory conformity with the bent, load-carrying member.

Redmon, J. W.

1969-01-01

394

Ball-and-Socket-Bearing Wear Test  

NASA Technical Reports Server (NTRS)

Series of experiments to measure wear life of spherical bearing summarized. Report designed to establish clearance, contour, finish, and lubricant parameters for highly-loaded, compact plain spherical bearing. Information useful in design of bearings for helicopter control linkages, business machines, nuclear reactor, and rotor bearings.

Graham, W. G.

1984-01-01

395

Cryogenic Magnetic Bearing Test Facility (CMBTF)  

NASA Technical Reports Server (NTRS)

The Cryogenic Magnetic Bearing Test Facility (CMBTF) was designed and built to evaluate compact, lightweight magnetic bearings for use in the SSME's (space shuttle main engine) liquid oxygen and liquid hydrogen turbopumps. State of the art and tradeoff studies were conducted which indicated that a hybrid permanent magnet bias homopolar magnetic bearing design would be smaller, lighter, and much more efficient than conventional industrial bearings. A test bearing of this type was designed for the test rig for use at both room temperature and cryogenic temperature (-320 F). The bearing was fabricated from state-of-the-art materials and incorporated into the CMBTF. Testing at room temperature was accomplished at Avcon's facility. These preliminary tests indicated that this magnetic bearing is a feasible alternative to older bearing technologies. Analyses showed that the hybrid magnetic bearing is one-third the weight, considerably smaller, and uses less power than previous generations of magnetic bearings.

1992-01-01

396

Superconductor bearings, flywheels and transportation  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

397

Magnetic bearings with zero bias  

NASA Technical Reports Server (NTRS)

A magnetic bearing operating without a bias field has supported a shaft rotating at speeds up to 12,000 rpm with the usual four power supplies and with only two. A magnetic bearing is commonly operated with a bias current equal to half of the maximum current allowable in its coils. This linearizes the relation between net force and control current and improves the force slewing rate and hence the band width. The steady bias current dissipates power, even when no force is required from the bearing. The power wasted is equal to two-thirds of the power at maximum force output. Examined here is the zero bias idea. The advantages and disadvantages are noted.

Brown, Gerald V.; Grodsinsky, Carlos M.

1991-01-01

398

The Great Bear Rainforest Spirit Bears, Grizzlies and Ancient Forests  

E-print Network

-old western red cedars. 22 conted.ucalgary.ca/travelprograms|403.220.2952 #12;Orientation The orientation's sea lions, and the biological complexity of the intertidal zone. Itinerary Three meals daily private 12-passenger boat to search for grizzly bears fishing for salmon, an amusing and entertaining

de Leon, Alex R.

399

Wave Journal Bearing. Part 1: Analysis  

NASA Technical Reports Server (NTRS)

A wave journal bearing concept features a waved inner bearing diameter of the non-rotating bearing side and it is an alternative to the plain journal bearing. The wave journal bearing has a significantly increased load capacity in comparison to the plain journal bearing operating at the same eccentricity. It also offers greater stability than the plain circular bearing under all operating conditions. The wave bearing's design is relatively simple and allows the shaft to rotate in either direction. Three wave bearings are sensitive to the direction of an applied stationary side load. Increasing the number of waves reduces the wave bearing's sensitivity to the direction of the applied load relative to the wave. However, the range in which the bearing performance can be varied decreases as the number of waves increases. Therefore, both the number and the amplitude of the waves must be properly selected to optimize the wave bearing design for a specific application. It is concluded that the stiffness of an air journal bearing, due to hydrodynamic effect, could be doubled and made to run stably by using a six or eight wave geometry with a wave amplitude approximately half of the bearing radial clearance.

Dimofte, Florin

1995-01-01

400

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

401

Efficacy and safety of hydrostatic balloon dilatation of ileocolonic Crohn's strictures: a prospective longterm analysis.  

PubMed Central

Preliminary reports have suggested that dilatation using hydrostatic through the scope balloons may be useful for the treatment of Crohn's strictures, A prospective longterm follow up (mean (SD) 33.6 (11.2) months) was carried out in 55 Crohn's patients with 59 ileocolonic strictures submitted to 78 dilatation procedures. Hydrostatic balloons were used (Rigiflator, Microvasive) with a diameter of 18 mm on inflation. As soon as the balloons became available dilatation up to a diameter of 20 and 25 mm was attempted. The dilatations were performed under general anaesthesia using propofol (Diprivan). The patients were kept for one night in the hospital after dilatation. Seventy (90%) procedures were technically successful and passage of the stricture with a 13.6 mm diameter colonoscope was possible after 73% of the dilatations. Complications occurred in six patients (11%; 8% of procedures), including sealed perforations (n = 2), retroperitoneal perforations (n = 2), and intraperitoneal perforations (n = 2). Two of the patients were treated surgically with a one stage resection of the stricture and recovered uneventfully. Four patients were treated conservatively with intravenous fluids and antibiotics. There was no mortality. Dilatation completely relieved obstructive symptoms in 20 patients after one procedure, in another 14 patients after two (n = 13) or three (n = 1) dilatations. Total longterm success rate was 34 of 55 patients (62%). Nineteen patients (38%) were operated on because of persistent obstructive symptoms. The data show that endoscopic dilatation using the through the scope hydrostatic balloon system relieves obstructive symptoms resulting from ileocolonic Crohn's strictures. The procedure, however, carries a definite risk of perforation. PMID:7737567

Couckuyt, H; Gevers, A M; Coremans, G; Hiele, M; Rutgeerts, P

1995-01-01

402

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

403

Nonlinear mode coupling in a birefringent microstructured fiber tuned by externally applied hydrostatic pressure  

NASA Astrophysics Data System (ADS)

We studied the effect of power coupling between two linearly polarized modes, which occurs during nonlinear propagation in an externally tuned birefringent microstructured fiber. We investigated both experimentally and numerically the possibility of measuring hydrostatic pressure by tracking the nonlinear power coupling between the fiber polarization modes. We analyzed the impact of the fiber length exposed to pressure and the input polarization state on the coupling efficiency. We also revealed that the observation of nonlinear power coupling between the polarization modes is limited by linear coupling occurring in the leadthroughs to the pressure chamber. Moreover, we demonstrated that the power coupling shifts the position and gain of the scalar modulation instability process.

Tarnowski, K.; Anuszkiewicz, A.; Mergo, P.; Frisquet, B.; Kibler, B.; Urbanczyk, W.

2015-03-01

404

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

NASA Technical Reports Server (NTRS)

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.

Sun, D. C.; Yuan, Qin

1995-01-01

405

THE EFFECTS OF HIGH HYDROSTATIC PRESSURE ON THE MICROTUBULES OF TETRAHYMENA PYRIFORMIS  

PubMed Central

Exposure of Tetrahymena pyriformis to 7,500 or 10,000 psi of hydrostatic pressure for 2, 5, or 10 min intervals results in a change in cell shape and ciliary activity. Shape changes occur concurrently with a degradation of longitudinal microtubules in a posterior to anterior direction. High pressure also causes a disruption of ciliary activity. Fine structural analysis reveals a breakdown (presumably microtubule depolymerization) of the central ciliary microtubules. The depolymerization begins at the junction of the central ciliary microtubules with the axosome and progresses distally along the ciliary shaft for a distance of about 0.5 µ. PMID:5497538

Kennedy, John R.; Zimmerman, Arthur M.

1970-01-01

406

Antiferromagnetic critical pressure in URu2Si2 under hydrostatic conditions  

NASA Astrophysics Data System (ADS)

The onset of antiferromagnetic order in URu2Si2 has been studied via neutron diffraction in a helium pressure medium, which most closely approximates hydrostatic conditions. The antiferromagnetic critical pressure is 0.80 GPa, considerably higher than values previously reported. Complementary electrical resistivity measurements imply that the hidden-order-antiferromagnetic bicritical point falls between 1.3 and 1.5 GPa. Moreover, the redefined pressure-temperature phase diagram suggests that the superconducting and antiferromagnetic phase boundaries actually meet at a common critical pressure at zero temperature.

Butch, Nicholas P.; Jeffries, Jason R.; Chi, Songxue; Leão, Juscelino Batista; Lynn, Jeffrey W.; Maple, M. Brian

2010-08-01

407

Electrical resistance of Fe-Zr and Fe-Ni-Zr amorphous alloys under hydrostatic pressure  

NASA Astrophysics Data System (ADS)

The effect of pressure on the electrical resistance of Fe 90Zr 10 and (Fe 0.96Ni 0.04) 90Zr 10 amorphous alloys has been investigated. The minimum point in the electrical resistance versus temperature curve shifts toward lower temperature range with increasing hydrostatic pressure, corresponding to the shift of the Curie temperature. The decrement of the electrical resistance below the Curie temperature Tc is about twice that above Tc, suggesting a large compressibility in the ferromagnetic state of the amorphous Invar alloys.

Shirakawa, K.; Fukamichi, K.; Kaneko, T.; Masumoto, T.

1983-08-01

408

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

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

409

In situ tuning the single photon emission from single quantum dots through hydrostatic pressure  

SciTech Connect

We demonstrate that exciton emission wavelength in InAs/GaAs quantum dots (QDs) can be shifted up to 160?nm using hydrostatic pressure (0.4–4?GPa) in situ in an optical cryostat through an improved diamond anvil cell driven by piezoelectric actuator. It is confirmed that the high pressure does not destroy the photon anti-bunching properties of single QD emitter. Exciton emission intensity is not obviously weakened under the pressure range of 0–4?GPa. Such a tunable QD single photon emitter enables a flexibly tuned source for quantum optical experiments.

Wu, Xuefei; Dou, Xiuming; Ding, Kun; Zhou, Pengyu; Ni, Haiqiao; Niu, Zhichuan; Jiang, Desheng; Sun, Baoquan, E-mail: bqsun@semi.ac.cn [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)] [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2013-12-16

410

Three-Dimensional Digital Image Correlation of a Composite Overwrapped Pressure Vessel During Hydrostatic Pressure Tests  

NASA Technical Reports Server (NTRS)

Ambient temperature hydrostatic pressurization tests were conducted on a composite overwrapped pressure vessel (COPV) to understand the fiber stresses in COPV components. Two three-dimensional digital image correlation systems with high speed cameras were used in the evaluation to provide full field displacement and strain data for each pressurization test. A few of the key findings will be discussed including how the principal strains provided better insight into system behavior than traditional gauges, a high localized strain that was measured where gages were not present and the challenges of measuring curved surfaces with the use of a 1.25 in. thick layered polycarbonate panel that protected the cameras.

Revilock, Duane M., Jr.; Thesken, John C.; Schmidt, Timothy E.

2007-01-01

411

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

SciTech Connect

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

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

2006-09-01

412

Theoretical Study of Structural Changes in DNA under High External Hydrostatic Pressure.  

PubMed

The study of DNA under high hydrostatic pressure provides fundamental insights into the nature of interactions responsible for its structure and its remarkable stability in extreme conditions. We have investigated the structural changes in DNA under 2000 bar external pressure using electronic structure calculations and molecular dynamics simulations. Both these methods predict very small distortions in the structure; notably, the change in hydrogen bond lengths is an order of magnitude smaller than previously reported experimental values using NMR. The large discrepancy suggests further investigation into the analysis of the experimental data obtained from NMR. PMID:25611549

Kumar, P Sudheer; Mukherjee, Arnab; Hazra, Anirban

2015-02-26

413

THE EFFECTS OF HIGH HYDROSTATIC PRESSURE ON THE MICROTUBULES OF TETR AHYMENA PYRIFORMIS  

E-print Network

Exposure of Tetrahymena pyriformis to 7,500 or 10,000 psi of hydrostatic pressure for 2, 5, or 10 min intervals results in a change in cell shape and ciliary activity. Shape changes occur concurrently with a degradation of longitudinal microtubules in a posterior to anterior direction. High pressure also causes a disruption of ciliary activity. Fine structural analysis reveals a breakdown (presumably microtubule depolymerization) of the central ciliary microtubules. The depolymerization begins at the junction of the central ciliary microtubules with the axosome and progresses distally along the ciliary shaft for a distance of about 0.5 µ.

John R Kennedy; Arthur M Zimmerman

414

Bearing Strength of Lunar Soil  

Microsoft Academic Search

Bearing load vs penetration curves have been measured on a 1.3 g sample of lunar soil from the scoop of the Surveyor 3 soil mechanics surface sampler, using a circular indentor 2 mm in diameter. Measurements were made in an Earth laboratory, in air. This sample provided a unique opportunity to evaluate earlier, remotely controlled, in-situ measurements of lunar surface

L. D. Jaffe

1971-01-01

415

Bearing strength of lunar soil  

Microsoft Academic Search

Bearing load vs penetration curves have been measured on a 1.3 g sample of lunar soil from the scoop of the Surveyor 3 soil mechanics surface sampler, using a circular indentor 2 mm in diameter. Measurements were made in an Earth laboratory, in air. This sample provided a unique opportunity to evaluate earlier, remotely controlled, in-situ measurements of lunar surface

L. D. Jaffe

1971-01-01

416

Fuzzy control of magnetic bearings  

NASA Technical Reports Server (NTRS)

The use of an adaptive fuzzy control algorithm implemented on a VLSI chip for the control of a magnetic bearing was considered. The architecture of the adaptive fuzzy controller is similar to that of a neural network. The performance of the fuzzy controller is compared to that of a conventional controller by computer simulation.

Feeley, J. J.; Niederauer, G. M.; Ahlstrom, D. J.

1991-01-01

417

Tardigrades: Bears of the Moss  

NSDL National Science Digital Library

This online PowerPoint presentation is dedicated to the phylum Tardigrada. It discusses distinguishing characteristics of Tardigrades (also known as water bears), their relationship to arthropods and nematodes, internal structures, life stages, cryptobiosis, research opportunities, classification, identification, habitat, distribution, ease of study in the lab, and more. Each slide contains illustrations and descriptions of the microscopic animal.

William Miller

418

Intelligent Engine Systems: Bearing System  

NASA Technical Reports Server (NTRS)

The overall requirements necessary for sensing bearing distress and the related criteria to select a particular rotating sensor were established during the phase I. The current phase II efforts performed studies to evaluate the Robustness and Durability Enhancement of the rotating sensors, and to design, and develop the Built-in Telemetry System concepts for an aircraft engine differential sump. A generic test vehicle that can test the proposed bearing diagnostic system was designed, developed, and built. The Timken Company, who also assisted with testing the GE concept of using rotating sensors for the differential bearing diagnostics during previous phase, was selected as a subcontractor to assist General Electric (GE) for the design, and procurement of the test vehicle. A purchase order was prepared to define the different sub-tasks, and deliverables for this task. The University of Akron was selected to provide the necessary support for installing, and integrating the test vehicle with their newly designed test facility capable of simulating the operating environment for the planned testing. The planned testing with good and damaged bearings will be on hold pending further continuation of this effort during next phase.

Singh, Arnant P.

2008-01-01

419

High performance rolling element bearing  

NASA Technical Reports Server (NTRS)

A high performance rolling element bearing (5) which is particularly suitable for use in a cryogenically cooled environment, comprises a composite cage (45) formed from glass fibers disposed in a solid lubricant matrix of a fluorocarbon polymer. The cage includes inserts (50) formed from a mixture of a soft metal and a solid lubricant such as a fluorocarbon polymer.

Bursey, Jr., Roger W. (Inventor); Olinger, Jr., John B. (Inventor); Owen, Samuel S. (Inventor); Poole, William E. (Inventor); Haluck, David A. (Inventor)

1993-01-01

420

Toxicity of Polar Bear Liver  

Microsoft Academic Search

ACCORDING to information from the Eskimos, and records from Arctic travellers, bad effects may follow the consumption, by men and dogs, of the livers of polar bear, bearded seal, Greenland fox and Eskimo huskies, whereas livers of other Arctic mammals can usually be eaten without injury.

Kaare Rodahl

1949-01-01

421

Gradient Tempering Of Bearing Races  

NASA Technical Reports Server (NTRS)

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

Parr, Richardson A.

1991-01-01

422

Satellite monitoring of black bear.  

NASA Technical Reports Server (NTRS)

Description of a feasibility experiment recently performed to test the use of a satellite system for telemetering environmental and physiological data from the winter den of a 'hibernating' black bear, Ursus americanus. The instrumentation procedure and evaluations of the equipment performance and sensory data obtained are discussed in detail.

Craighead, J. J.; Craighead, F. C., Jr.; Varney, J. R.; Cote, C. E.

1971-01-01

423

Robust and intelligent bearing estimation  

SciTech Connect

As the monitoring thresholds of global and regional networks are lowered, bearing estimates become more important to the processes which associate (sparse) detections and which locate events. Current methods of estimating bearings from observations by 3-component stations and arrays lack both accuracy and precision. Methods are required which will develop all the precision inherently available in the arrival, determine the measurability of the arrival, provide better estimates of the bias induced by the medium, permit estimates at lower SNRs, and provide physical insight into the effects of the medium on the estimates. Initial efforts have focused on 3-component stations since the precision is poorest there. An intelligent estimation process for 3-component stations has been developed and explored. The method, called SEE for Search, Estimate, and Evaluation, adaptively exploits all the inherent information in the arrival at every step of the process to achieve optimal results. In particular, the approach uses a consistent and robust mathematical framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, and to withdraw metrics helpful in choosing the best estimate(s) or admitting that the bearing is immeasurable. The approach is conceptually superior to current methods, particular those which rely on real values signals. The method has been evaluated to a considerable extent in a seismically active region and has demonstrated remarkable utility by providing not only the best estimates possible but also insight into the physical processes affecting the estimates. It has been shown, for example, that the best frequency at which to make an estimate seldom corresponds to the frequency having the best detection SNR and sometimes the best time interval is not at the onset of the signal. The method is capable of measuring bearing dispersion, thereby withdrawing the bearing bias as a function of frequency. The lowest measurable frequency in the dispersion pattern is often a near error free bearing. These latter features should be helpful in calibrating the stations for frequency dependent biases induced by the earth. Future efforts will enhance the SEE algorithm and will also evaluate it using larger station data sets.

Claassen, J.P.

1998-07-01

424

Theoretical studies of optical gain tuning by hydrostatic pressure in GaInNAs/GaAs quantum wells  

SciTech Connect

In order to describe theoretically the tuning of the optical gain by hydrostatic pressure in GaInNAs/GaAs quantum wells (QWs), the optical gain calculations within kp approach were developed and applied for N-containing and N-free QWs. The electronic band structure and the optical gain for GaInNAs/GaAs QW were calculated within the 10-band kp model which takes into account the interaction of electron levels in the QW with the nitrogen resonant level in GaInNAs. It has been shown that this interaction increases with the hydrostatic pressure and as a result the optical gain for GaInNAs/GaAs QW decreases by about 40% and 80% for transverse electric and transverse magnetic modes, respectively, for the hydrostatic pressure change from 0 to 40 kilobars. Such an effect is not observed for N-free QWs where the dispersion of electron and hole energies remains unchanged with the hydrostatic pressure. This is due to the fact that the conduction and valence band potentials in GaInAs/GaAs QW scale linearly with the hydrostatic pressure.

Gladysiewicz, M.; Wartak, M. S. [Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw, Wybrzeze Wyspianskiego 27 (Poland); Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); Kudrawiec, R. [Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw, Wybrzeze Wyspianskiego 27 (Poland)

2014-01-21

425

Journal and Wave Bearing Impedance Calculation Software  

NASA Technical Reports Server (NTRS)

The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

Hanford, Amanda; Campbell, Robert

2012-01-01

426

Rubber bearings for precision positioning systems  

E-print Network

In this thesis we investigate the use of thin rubber sheets or laminates of metal and rubber sheets as bearings in precision positioning systems. Such bearings have the potential to replace more conventional flexures ...

Barton Martinelli, Augusto E

2005-01-01

427

A Preliminary Foil Gas Bearing Performance Map  

NASA Technical Reports Server (NTRS)

Recent breakthrough improvements in foil gas bearing load capacity, high temperature tribological coatings and computer based modeling have enabled the development of increasingly larger and more advanced Oil-Free Turbomachinery systems. Successful integration of foil gas bearings into turbomachinery requires a step wise approach that includes conceptual design and feasibility studies, bearing testing, and rotor testing prior to full scale system level demonstrations. Unfortunately, the current level of understanding of foil gas bearings and especially their tribological behavior is often insufficient to avoid developmental problems thereby hampering commercialization of new applications. In this paper, a new approach loosely based upon accepted hydrodynamic theory, is developed which results in a "Foil Gas Bearing Performance Map" to guide the integration process. This performance map, which resembles a Stribeck curve for bearing friction, is useful in describing bearing operating regimes, performance safety margins, the effects of load on performance and limiting factors for foil gas bearings.

DellaCorte, Christopher; Radil, Kevin C.; Bruckner, Robert J.; Howard, S. Adam

2006-01-01

428

Rolling Element Bearing Stiffness Matrix Determination (Presentation)  

SciTech Connect

Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

Guo, Y.; Parker, R.

2014-01-01

429

High Temperature, Permanent Magnet Biased Magnetic Bearings  

E-print Network

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

Gandhi, Varun R.

2010-07-14

430

Self-bearing motor design & control  

E-print Network

This thesis presents the design, implementation and control of a new class of self-bearing motors. The primary thesis contributions include the design and experimental demonstration of hysteresis self-bearing motors, novel ...

Imani Nejad, Mohammad

2013-01-01

431

Hunting for 'bears' in the backyard  

NSDL National Science Digital Library

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

Dave Walker

432

Stable isotopes to detect food-conditioned bears and to evaluate human-bear management  

USGS Publications Warehouse

We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

Hopkins, John B., III; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

2012-01-01

433

Effects of bearing deadbands on bearing loads and rotor stability  

NASA Technical Reports Server (NTRS)

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

1984-01-01

434

True-slime-mould-inspired hydrostatically coupled oscillator system exhibiting versatile behaviours.  

PubMed

Behavioural diversity is an indispensable attribute of living systems, which makes them intrinsically adaptive and responsive to the demands of a dynamically changing environment. In contrast, conventional engineering approaches struggle to suppress behavioural diversity in artificial systems to reach optimal performance in given environments for desired tasks. The goals of this research include understanding the essential mechanism that endows living systems with behavioural diversity and implementing the mechanism in robots to exhibit adaptive behaviours. For this purpose, we have focused on an amoeba-like unicellular organism: the plasmodium of true slime mould. Despite the absence of a central nervous system, the plasmodium exhibits versatile spatiotemporal oscillatory patterns and switches spontaneously among these patterns. By exploiting this behavioural diversity, it is able to exhibit adaptive behaviour according to the situation encountered. Inspired by this organism, we built a real physical robot using hydrostatically coupled oscillators that produce versatile oscillatory patterns and spontaneous transitions among the patterns. The experimental results show that exploiting physical hydrostatic interplay—the physical dynamics of the robot—allows simple phase oscillators to promote versatile behaviours. The results can contribute to an understanding of how a living system generates versatile and adaptive behaviours with physical interplays among body parts. PMID:23981517

Umedachi, Takuya; Idei, Ryo; Ito, Kentaro; Ishiguro, Akio

2013-09-01

435

Characterization of polyphenols from green tea leaves using a high hydrostatic pressure extraction.  

PubMed

A new extraction technique, high hydrostatic pressure extraction (HHPE), was used to obtain polyphenols from green tea leaves. Various experimental conditions, such as different solvents (acetone, methanol, ethanol and water), pressure (100, 200, 300, 400, 500, 600 MPa), holding time (1, 4, 7, 10 min), ethanol concentration (0-100% mL/mL), and liquid/solid ratio (10:1 to 25:1 mL/g) for the HHPE procedure, were investigated to optimize the extraction. The optimal conditions were as follows: 50% (mL/mL) of ethanol concentration, 20:1 (mL/g) of liquid/solid ratio and 500 MPa of high hydrostatic pressure for 1 min. Under such conditions the extraction yield of polyphenols was up to 30+/-1.3%. The extraction yields of polyphenols with HHPE for only 1 min were the same as those of extraction at room temperature for 20 h, ultrasonic extraction for 90 min and heat reflux extraction for 45 min, respectively. On the basis of the extraction yields of polyphenols, extraction time and the percentages of polyphenols in extracts, the HHPE is more effective than the conventional extraction methods studied. PMID:19715745

Xi, Jun; Shen, Deji; Zhao, Shou; Lu, Bingbing; Li, Ye; Zhang, Rui

2009-12-01

436

Effect of high hydrostatic pressure on the barrier properties of polyamide-6 films.  

PubMed

Little is known about the barrier properties of polymer films during high pressure processing of prepackaged foods. In order to learn more about this, we examined the influence of high hydrostatic pressure on the permeation of raspberry ketone (dissolved in ethanol/water) through polyamide-6 films at temperatures between 20 and 60 degrees C. Permeation was lowered by increasing pressure at all temperatures. At 23 degrees C, the increasing pressure sequence 0.1, 50, 100, 150, and 200 MPa correlated with the decreasing permeation coefficients P/(10(9) cm(2) s-1) of 6.2, 3.8, 3.0, 2.2, and 1.6. Analysis of the permeation kinetics indicated that this effect was due to a reduced diffusion coefficient. Pressure and temperature acted antagonistically to each other. The decrease in permeation at 200 MPa was compensated for by a temperature increase of 20 degrees C. After release of pressure, the former permeation coefficients were recovered, which suggests that this 'pressure effect' is reversible. Taken together, our data revealed no detrimental effects of high hydrostatic pressure on the barrier properties of polymer films. PMID:16082471

Schmerder, A; Richter, T; Langowski, H-C; Ludwig, H

2005-08-01

437

Crystallization of a Li2O2SiO2 Glass under High Hydrostatic Pressures  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

438

TESTING MODELS FOR MOLECULAR GAS FORMATION IN GALAXIES: HYDROSTATIC PRESSURE OR GAS AND DUST SHIELDING?  

SciTech Connect

Stars in galaxies form in giant molecular clouds that coalesce when the atomic hydrogen is converted into molecules. There are currently two dominant models based on the property of the galactic disk that determines its molecular fraction: either hydrostatic pressure driven by the gravity of gas and stars, or a combination of gas column density and metallicity. To assess the validity of these models, we compare theoretical predictions to the observed atomic gas content of low-metallicity dwarf galaxies with high stellar densities. The extreme conditions found in these systems are optimal for distinguishing the two models, otherwise degenerate in nearby spirals. Locally, on scales <100 pc, we find that the state of the interstellar medium is mostly sensitive to the gas column density and metallicity rather than hydrostatic pressure. On larger scales where the average stellar density is considerably lower, both pressure and shielding models reproduce the observations, even at low metallicity. We conclude that models based on gas and dust shielding more closely describe the process of molecular formation, especially at the high resolution that can be achieved in modern galaxy simulations or with future radio/millimeter arrays.

Fumagalli, Michele; Krumholz, Mark R. [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Hunt, Leslie K., E-mail: mfumagalli@ucolick.or [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze (Italy)

2010-10-10

439

High resolution non-hydrostatic GCM simulations of Venus polar vortices  

NASA Astrophysics Data System (ADS)

Non-hydrostatic general circulation model of the Venus atmosphere is capable of reproducing both superrotatoin and subsolar-antisolar circulation, providing proper parameterization of the peculiar heat balance. Using high resolution (0.7 (o) in longitude and latitude, 250 m in height) simulations from the bottom to 120 km, we explore the response of the circulation system to perturbation of heating and cooling rates in the polar regions. It is shown that diurnal tide results in off-axis displacement of the polar vortex external part at the upper cloud level, consistent with the patterns retrieved from cloud tracking observations. On the other hand, minor (3 (o) -7 (o) ) displacement of the polar vortex central part constrains the diurnal variations of the heating/cooling rates within main cloud deck. Based on the recently developed radiative transfer code, we simulate heat balance in the polar Venus atmosphere, that results in realistic circulation pattern. It is shown that Hadley cell circulation provides extra heating above the clouds, resulting in the effective damping of superrotation and development of subsolar-antisolar circulation at higher altitudes. In turin high slant opacity of the polar atmosphere within the clouds provides the effective cooling near the pole, that causes non-hydrostatic downwelling flow, manifested as a core of the observed polar vortex. The work has been supported by the Ministry of Education and Science of Russian Federation grant #11.G34.31.0074

Rodin, Alexander V.; Orlov, Konstantin; Mingalev, Igor

440

Prediction of acid lactic-bacteria growth in turkey ham processed by high hydrostatic pressure  

PubMed Central

High hydrostatic pressure (HHP) has been investigated and industrially applied to extend shelf life of meat-based products. Traditional ham packaged under microaerophilic conditions may sometimes present high lactic acid bacteria population during refrigerated storage, which limits shelf life due to development of unpleasant odor and greenish and sticky appearance. This study aimed at evaluating the shelf life of turkey ham pressurized at 400 MPa for 15 min and stored at 4, 8 and 12 °C, in comparison to the non pressurized product. The lactic acid bacteria population up to 107 CFU/g of product was set as the criteria to determine the limiting shelf life According to such parameter the pressurized sample achieved a commercial viability within 75 days when stored at 4 °C while the control lasted only 45 days. Predictive microbiology using Gompertz and Baranyi and Roberts models fitted well both for the pressurized and control samples. The results indicated that the high hydrostatic pressure treatment greatly increased the turkey ham commercial viability in comparison to the usual length, by slowing down the growth of microorganisms in the product. PMID:24159279

Mathias, S.P.; Rosenthal, A.; Gaspar, A.; Aragão, G.M.F.; Slongo-Marcusi, A.

2013-01-01

441

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

NASA Astrophysics Data System (ADS)

The hydrostatic pressure and shock response of plant seeds has been investigated antecedently, primarily driven by interest in reducing bacterial contamination of crops and the theory of panspermia, respectively. However, comparisons have not previously been made between these two methods ofapplying pressure to plant seeds. Here such a comparison has been undertaken based on the premise that any correlations in collected data may provide a route to inform understanding of damage mechanisms in the seeds under test. In this work two varieties of plant seeds were subjected to hydrostatic pressure via a non-end-loaded piston cylinder setup and shock compression via employment of a 50 mm bore, single stage gas gun using the flyer plate technique. Results from germination tests of recovered seed samples have been compared and contrasted, and initial conclusions made regarding causes of trends in the resultant data-set. Data collected has shown that cress seeds are extremely resilient to static loading, whereas the difference in the two forms of loading is negligible for lettuce seeds. Germination time has been seen to extend dramatically following static loading of cress seeds to greater than 0.4 GPa. In addition, the cut-off pressure previously seen to cause 0% germination in dynamic experiments performed on cress seeds has now also been seen in lettuce seeds.

Mustey, A.; Leighs, J. A.; Appleby-Thomas, G. J.; Wood, D. C.; Hazael, R.; McMillan, P. F.; Hazell, P. J.

2014-05-01

442

Nonlocal integral-equation approximations. I. The zeroth order (hydrostatic) approximation with applications  

SciTech Connect

A formally exact nonlocal density-functional expansion procedure for direct correlation functions developed earlier by Stell for a homogeneous system, and extended by Blum and Stell, Sullivan and Stell, and ourselves to various inhomogeneous systems, is used here to derive nonlocal integral-equation approximations. Two of the simplest of these approximations (zeroth order), which we shall characterize here as the hydrostatic Percus--Yevick (HPY) approximation and the hydrostatic hypernetted-chain (HHNC) approximation, respectively, are shown to be capable of accounting for wetting transitions on the basis of general theoretical considerations. Before turning to such transitions, we investigate in this first paper of a series the case of homogeneous hard-sphere fluids and hard spheres near a hard wall as well as the case of hard spheres inside a slit pore. Numerical results show that the HHNC approximation is better than the HNC approximation for both the homogeneous and inhomogeneous systems considered here while the HPY approximation appears to overcorrect the PY approximation.

Zhou, Y. (Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794 (USA)); Stell, G. (Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY (USA) Department of Mechanical Engineering, State University of New York at Stony Brook, Stony Brook, NY (USA))

1990-05-01

443

Cartridge Bearing System for Space Applications  

NASA Technical Reports Server (NTRS)

Conventional spin axis ball bearings have been unreliable in spacecraft, often failing by two heretofore uncontrolled processes: ball retainer instability and lubricant breakdown. The Space Cartridge Bearing System (SCBS) addresses each of these mechanisms directly, leading to a bearing system with absolute freedom from retainer instability and negligible lubricant degradation rate. The result is a reliable plug-in bearing cartridge with a definite design life.

Kingsbury, Edward P.; Hanson, Robert A.; Jones, William R.; Mohr, Terry W.

1999-01-01

444

Mercury in polar bears from Alaska  

SciTech Connect

Alaskan polar bear (Ursus maritimus) muscle and liver samples collected in 1972 were analyzed for total mercury. Bears north of Alaska had more mercury than bears west of Alaska. The only difference between young and adult animals was in the northern area where adults had more mercury in liver tissue than young animals. Levels were probably not high enough to be a serious threat to bears.

Lentfer, J.W.; Galster, W.A.

1987-04-01

445

Predation of Svalbard reindeer by polar bears  

Microsoft Academic Search

Polar bears (Ursus maritimus) are believed to be obligate predators on marine mammals, and particularly, on two species of seals. This paper reports on\\u000a observations of polar bears preying (n=7) and scavenging (n=6) on Svalbard reindeer (Rangifer tarandus platyrhyncus). Similar to their closest evolutionary ancestor, the brown bear (U. arctos), polar bears are opportunistic and will prey on ungulates. Reindeer

Andrew E. Derocher; Øystein Wiig; Georg Bangjord

2000-01-01

446

Improvement of the subgrid vertical mixing parameterization in operational hydrostatic models at Météo-France  

NASA Astrophysics Data System (ADS)

A global variable mesh model (ARPEGE), an hydrostatic limited area model (ALADIN) with a 9.5km resolution over several regions of the world and a non-hydrostatic 2.5km resolution model (AROME) over France are used operationally at Météo-France for weather forecasting. Important modifications of the subgrid vertical mixing parameterization used in the hydrostatic models became operational in February 2009. The turbulence scheme (Louis, 1979) associated to a pseudo-shallow convection parameterization (Geleyn, 1987) has been replaced by a prognostic Turbulent Kinetic Energy scheme (TKE) associated to a mass flux shallow convection scheme. This development is characterised by a broad convergence between the parameterizations used in hydrostatic models with those of the operational non-hydrostatic model AROME. The prognostic TKE scheme (Cuxart et al, 2000) is used with the tuning coefficients of AROME. The mixing length is computed using the formulation of Bougeault and Lacarrère (1989) (BL89) but with a modified combination between Lup and ldown. To improve the representation of stratocumulus, the scheme uses a top-Planetary Boundary Layer (PBL) entrainment parameterization following the ideas of Grenier and Bretherton (2001), with a modified integral formulation. The shallow convection mass flux scheme is described in Bechtold et al. (2001). To solve a problem of too strong wind in the tropical PBL, it was found beneficial to amend both the mixing length and the TKE, following the approach of Lock and Mailhot (2006). The main idea of the connection between the shallow convection scheme and the turbulence scheme is to suppose that in a PBL, where occurs shallow convection, the turbulent mixing is enhanced by the presence of clouds. First, a thermal production term of TKE coming from the shallow convection scheme is computed. Secondly, a local modification of the BL89 mixing length is used. The BL89 mixing length is computed using the dry buoyancy and doesn't take into account the phase changes of water. In a cloud layer the result is an underestimation of the mixing length. The new approach consists of getting the thickness of the cloud from the shallow convection parameterization. When a shallow convection cloud is present upward (Lup) and downward (Ldown) computed mixing lengths are now taken at least equal to the distance between the current level and the top (respectively the bottom) of the cloud. 1:Bechtold, P., Bazile, E., Guichard, F., Mascart, P. and Richard, E., 2001 : A mass-flux convection scheme for regional and global models. Quart. J. R. Met. Soc., 127, p.869-886. 2. Bougeault, Ph., and Lacarrère, P., 1989 : Parameterization of orography-induced in meso-beta-scale model. Mon. Wea. Rev., 117, p.1872-1891. 3. Cuxart, J., Bougeault, Ph. And Redelsperger, J-L., 2000 : A turbulence scheme allowing for mesoscale and large-eddy simulations. Quart. J. R. Met. Soc., 126, p.1-30. 4. Geleyn, J.F., 1987 : Use of a modified Richardson number for parameterizing the effect of shallow convection. Short-and Medium-Range Numerical Weather Prediction (also WMO/IUGG NWP Symposium special issue), Tokyo, 4-8 August 1986). Special Volume of J. Meteor. Soc. Japan, T. Matsumo ed., p.141-149. 5. Grenier, H., and Bretherton, C. S., 2001 : A moist PBL parameterization for large scale models and its application ti subtropical cloud-topped marine boundary layers. Mon. Wea. Rev., 129, p.357-377. 6. Lock, A. and Mailhot, J. 2006 : Combining non-local scalings with a tke closure for mixing in boundary-layer clouds. Bound.-Layer Meteor., 121, p 313-338. 7. Louis, J.F., 1979 : A parametric model of vertical eddy fluxes in the atmosphere. Bound. Layer Meteor., 17, p.187-202.

Bouteloup, Y.; Bazile, E.; Bouyssel, F.; Marquet, P.

2009-09-01

447

Lens intracellular hydrostatic pressure is generated by the circulation of sodium and modulated by gap junction coupling  

PubMed Central

We recently modeled fluid flow through gap junction channels coupling the pigmented and nonpigmented layers of the ciliary body. The model suggested the channels could transport the secretion of aqueous humor, but flow would be driven by hydrostatic pressure rather than osmosis. The pressure required to drive fluid through a single layer of gap junctions might be just a few mmHg and difficult to measure. In the lens, however, there is a circulation of Na+ that may be coupled to intracellular fluid flow. Based on this hypothesis, the fluid would cross hundreds of layers of gap junctions, and this might require a large hydrostatic gradient. Therefore, we measured hydrostatic pressure as a function of distance from the center of the lens using an intracellular microelectrode-based pressure-sensing system. In wild-type mouse lenses, intracellular pressure varied from ?330 mmHg at the center to zero at the surface. We have several knockout/knock-in mouse models with differing levels of expression of gap junction channels coupling lens fiber cells. Intracellular hydrostatic pressure in lenses from these mouse models varied inversely with the number of channels. When the lens’ circulation of Na+ was either blocked or reduced, intracellular hydrostatic pressure in central fiber cells was either eliminated or reduced proportionally. These data are consistent with our hypotheses: fluid circulates through the lens; the intracellular leg of fluid circulation is through gap junction channels and is driven by hydrostatic pressure; and the fluid flow is generated by membrane transport of sodium. PMID:21624945

Gao, Junyuan; Sun, Xiurong; Moore, Leon C.; White, Thomas W.; Brink, Peter R.

2011-01-01

448

Hydrology of the Bear Lake Basin, Utah  

Microsoft Academic Search

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

Patsy Palacios; Chris Luecke; Justin Robinson

2007-01-01

449

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

450

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

451

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

452

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

453

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

454

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

455

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

456

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

457

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

458

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

459

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

460

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

461

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

462

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

463

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

464

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

465

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

466

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

467

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

468

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

469

Active magnetic bearings applied to industrial compressors  

Microsoft Academic Search

The design and shop test results are given for a high-speed eight-stage centrifugal compressor supported by active magnetic bearings. A brief summary of the basic operation of active magnetic bearings and the required rotor dynamics analysis are presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofits of magnetic bearings in existing machinery are

R. G. Kirk; J. F. Hustak; K. A. Schoeneck

1993-01-01

470

Cool Polar Bears: Dabbing on the Texture  

ERIC Educational Resources Information Center

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

O'Connell, Jean

2011-01-01

471

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2010 CFR

... Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not...than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run in contact unless designed to...

2010-10-01

472

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2012 CFR

... Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not...than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run in contact unless designed to...

2012-10-01

473

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2014 CFR

... Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not...than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run in contact unless designed to...

2014-10-01

474

Simultaneous measurement of temperature, hydrostatic pressure and acoustic signal using a single distributed Bragg reflector fiber laser  

NASA Astrophysics Data System (ADS)

A fiber-optic sensor based on a dual polarization fiber grating laser for simultaneous measurement of temperature, hydrostatic pressure and acoustic signal is proposed and experimentally demonstrated. The acoustic wave induces a frequency modulation (FM) of the carrier in radio frequency (RF) range generated by the fiber laser and can be easily extracted by using the FM demodulation technique. The temperature can be determined by the laser wavelength. The hydrostatic pressure can be determined by monitoring the static shift of the carrier frequency and deducting the effect of the temperature.

Tan, Yan-Nan; Zhang, Yang; Guan, Bai-Ou

2011-05-01

475

Neutron scattering study of a quasi-2D spin-1/2 dimer system Piperazinium Hexachlorodicuprate under hydrostatic pressure  

SciTech Connect

We report inelastic neutron scattering study of a quasi-two-dimensional S=1/2 dimer system piperazinium hexachlorodicuprate under hydrostatic pressure. The spin gap {Delta} becomes softened with the increase of the hydrostatic pressure up to P = 9.0 kbar. The observed threefold degenerate triplet excitation at P = 6.0 kbar is consistent with the theoretical prediction and the bandwidth of the dispersion relation is unaffected within the experimental uncertainty. At P = 9.0 kbar the spin gap is reduced to {Delta} = 0.55 meV from {Delta} = 1.0 meV at ambient pressure.

Hong, Tao [ORNL; Stock, C. [NIST Center for Neutron Research (NCRN), Gaithersburg, MD; Cabrera, I. [Johns Hopkins University; Broholm, C. [Johns Hopkins University; Qiu, Y. [National Institute of Standards and Technology (NIST); Leao, J. B. [National Institute of Standards and Technology (NIST); Poulton, S. J. [National Institute of Standards and Technology (NIST); Copley, J.R.D. [National Institute of Standards and Technology (NIST)

2010-01-01

476

Thin film superconductor magnetic bearings  

DOEpatents

A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

Weinberger, Bernard R. (Avon, CT)

1995-12-26

477

Rolling element bearings in space  

NASA Technical Reports Server (NTRS)

Some of the advances in tribology that have been associated with aerospace mechanisms are discussed. The needs of aerospace have been the dominant forces leading to improvements in understanding and applying tribology technology. In the past two decades improvements in understanding bearing torque, elastohydrodynamic lubrication, lubricant distribution, cage stability, and transfer film lubricants have been made. It is anticipated that further developments will be made in response to future aerospace requirements.

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

1986-01-01

478

Bearing capacity of desiccated tailings  

Microsoft Academic Search

The development of matric suctions in soils contributes to their shear strength, resulting in an enhanced factor of safety against bearing-capacity failure. In this paper, matric suction profiles of desiccated mine tailings are predicted from a steady-state solution for evaporative conditions, and from an isothermal mathematical model that simulates liquid and vapor water flow through soils. The shear-strength envelope with

Daud W. Rassam; David J. Williams

1999-01-01

479

Bearing strength of lunar soil.  

NASA Technical Reports Server (NTRS)

Bearing load vs penetration curves have been measured on a 1.3 g sample of lunar soil from the scoop of the Surveyor 3 soil mechanics surface sampler, using a circular indentor 2 mm in diameter. Measurements were made in an Earth laboratory, in air. This sample provided a unique opportunity to evaluate earlier, remotely controlled, in-situ measurements of lunar surface bearing properties. Bearing capacity, measured at a penetration equal to the indentor diameter, varied from 0.02-0.04 N/sq cm at bulk densities of 1.15 g/cu cm to 30-100 N/sq cm at 1.9 g/cu cm. Deformation was by compression directly below the indentor at bulk densities below 1.61 g/cu cm, by outward displacement at bulk densities over 1.62 g/cu cm. Preliminary comparison of in-situ remote measurements with those on returned material indicates good agreement if the lunar regolith at Surveyor 3 has a bulk density of 1.6 g/cu cm at 2.5 cm depth.

Jaffe, L. D.

1971-01-01

480

Fault Tolerant Homopolar Magnetic Bearings  

NASA Technical Reports Server (NTRS)

Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.

Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert

2003-01-01

481

Polar Bears International: Wrangel Island, Russia  

NSDL National Science Digital Library

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

482

Heuristic explanation of journal bearing instability  

NASA Technical Reports Server (NTRS)

A fluid-filled journal bearing is viewed as a powerful pump circulating fluid around the annular space between the journal and the bearing. A small whirling motion of the journal generates a wave of thickness variation progressing around the channel. The hypothesis that the fluid flow drives the whirl whenever the mean of the pumped fluid velocity is greater than the peripheral speed of the thickness variation wave is discussed and compared with other simple explanations of journal bearing instability. It is shown that for non-cavitation long bearings the hypothesis predicts instability onset correctly for unloaded bearings but gradually overpredicts the onset speed as the load is increased.

Crandall, S. H.

1982-01-01

483

Polar Bears International : Wrangel Island, Russia  

NSDL National Science Digital Library

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

2007-12-12

484

Automated Assistance for Designing Active Magnetic Bearings  

NASA Technical Reports Server (NTRS)

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

Imlach, Joseph

2008-01-01

485

Effect of high hydrostatic pressure pretreatment on drying kinetics, antioxidant activity, firmness and microstructure of Aloe vera ( Aloe barbadensis Miller) gel  

Microsoft Academic Search

The effect of High Hydrostatic Pressure (HHP) and other pretreatments on the drying kinetics, antioxidant activity, firmness and microstructure of Aloe vera gel was investigated during convective drying at 70 °C. The pretreatments analyzed were high hydrostatic pressure, blanching, enzymatic and microwaves. Simulation of drying curves was studied through the application of several mathematical models such as Newton, Henderson and Pabis,

Antonio Vega-Gálvez; Elsa Uribe; Mario Perez; Gipsy Tabilo-Munizaga; Judith Vergara; Purificación Garcia-Segovia; Elena Lara; Karina Di Scala

2011-01-01

486

Lubrication for high load duplex bearings  

SciTech Connect

Three ES and H-compatible lubricants (Environment, Safety and Health) for high load duplex bearing applications were evaluated and compared against 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. Bearings with Supercritical CO{sub 2} deposition of PTFE extracted from Vydax AR/IPA, bearings with titanium carbide coated balls, and bearings with diamond-like carbon races and retainers were evaluated. Bearings with Supercritical CO{sub 2} deposition of PTFE from Vydax AR/IPA performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax.

Steinhoff, R.G.

1997-08-01

487

Design review of fluid film bearing testers  

NASA Technical Reports Server (NTRS)

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

Scharrer, Joseph K.

1993-01-01

488

Pratt and Whitney cryogenic turbopump bearing experience  

NASA Technical Reports Server (NTRS)

Successful, reusable bearings require lubrication, traditionally, a transfer film from sacrificial cage wear. Early testing included materials screening programs to identify suitable cryogenic cage materials. A specially developed element tester that simulated the function of a ball bearing cage was used. Suitable materials must provide lubrication with an acceptably low wear rate, without abrading contacting surfaces. The most promising materials were tested in full scale bearings at speeds up to 4 MDN. Teflon, filled with 40 percent bronze powder, was the best performing material. A variety of bearings were designed and successfully tested in LH2 and LOX. Bearings with bronze filled Teflon cages were successfully tested for 150 hrs. In overload tests, the same design was tested for 5 hrs at maximum Hertz stresses above 450 ksi and an additional 5 hrs with a maximum Hertz stress exceeding 500 ksi. Four bearings were tested in LOX for 25 hrs, with a maximum time per bearing of 10 hrs.

Poole, W. E.; Bursey, R. W., Jr.

1988-01-01

489

Towards an energy-conserving quasi-hydrostatic deep-atmosphere dynamical core  

NASA Astrophysics Data System (ADS)

Towards an energy-conserving quasi-hydrostatic deep-atmosphere dynamical core Marine Tort1 & Thomas Dubos1 1 Laboratoire Météorologique Dynamique, Ecole Polytechnique, Palaiseau, FRANCE Atmosphere dynamics of our planet is quite well described by traditional primitive equations based on the so-called shallow-atmosphere approximation. Thus, the model is dynamically consistent (in the sense that it possesses conservation principles for mass, energy, potential vorticity and angular momentum) when certain metric terms and the cos? Coriolis terms are neglected (Phillips, 1966). Nevertheless, to simulate planetary atmospheres, the shallow-atmosphere approximation should be relaxed because of the low planet radius (such as Titan) or the depth of their atmospheres (such as Jupiter or Saturne). Non-traditional terms have some dynamical effects (Gerkema and al., 2008) but they are little-known and rarely integrated into general circulation dynamical cores (Wood and Staniforth, 2002). As an example, the french GCM of the Laboratoire Météorologique Dynamique (LMD-Z) integrates the traditional primitive equations discretized from their curl (vector-invariant) form based on a finite different scheme whose conserves exactly potential vorticity (Sadourny, 1975a,b). We considered an orthogonal curvilinear system and we first derived a curl form of global, deep-atmosphere quasi-hydrostatic model in which prognostic variable is absolute axial momentum instead of relative velocity vector. Given the close relationship between the curl form and Hamiltonian formulation of the previous equations, we generalized Sadourny's energy-conserving formulation by discretizing the Poisson bracket and the energy themselves (Salmon, 1983; Gassmann, 2013). The substantial computing infrastructure of the dynamical core is the same but the modification of the hydrostatic balance requires a mass-based vertical coordinate (Wood and Staniforth, 2003). The new discretization has been implemented into LMD-Z on a longitude-latitude horizontal grid and test cases (Held and Suarez, 1994; Ullrich et al., 2013) have been performed considering an idealized deep atmosphere (small like-Earth). They validate the accuracy and the numerical stability of the new dynamical core.

Tort, Marine; Dubos, Thomas

2014-05-01

490

Public attitudes towards brown bears ( Ursus arctos) in Slovenia  

Microsoft Academic Search

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

Petra Kaczensky; Mateja Blazic; Hartmut Gossow

2004-01-01

491