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1

Accelerated life time testing of fused silica for DUV laser applications revised  

NASA Astrophysics Data System (ADS)

We report on the continuation of a comparative study of different fused silica materials for ArF laser applications. After selecting potentially suited fused silica materials from their laser induced absorption and compaction obtained by a short time testing procedure, accelerated life time tests have been undertaken by sample irradiating at liquid nitrogen temperature and subsequent direct absorption measurements using the laser induced deflection (LID) technique. The obtained degradation acceleration strongly differs between fused silica materials showing high and low OH contents, respectively. As a result, a difference in the absorption degradation mechanism between high and low OH containing fused silica is proposed. Consequently two different scenarios for an acceleration of the absorption degradation are derived.

Mühlig, Christian; Bublitz, Simon

2013-11-01

2

Accelerated test modeling  

NASA Technical Reports Server (NTRS)

Cycle life regression model, cycle life prediction model, and acceleration factors are discussed. A method was presented to: (1) select a mathematical model; (2) determine model coefficients using accelerated test data; (3) test model fit of the accelerated test data; and (4) predict normal packs.

Schwartz, D.

1978-01-01

3

Test-to-Failure of a Two-Grid, 30-cm-dia. Ion Accelerator System  

NASA Technical Reports Server (NTRS)

To determine the failure mechanism and erosion characteristics of an ion accelerator system due to erosion by charge-exchange ions a test was performed in which a 30-cm-diameter, 2-grid ion accelerator system was tested to failure. The erosion charcteristics observed in this test, however, imply significantly shorter accelerator grid life times than typically stated in the literature. Finally, the test suggests that structural failure is probably not the most likely first failure mechanism for the accelerator grid.

Brophy, J. R.; Polk, J. E.; Pless, L. C.

1993-01-01

4

Testing the Accelerating Universe  

NASA Astrophysics Data System (ADS)

Type Ia supernovae provide evidence for an accelerating universe: an extraordinary result that needs to be rigorously tested. The two chief alternatives to a cosmological source for the observed shape of the high-z Hubble diagram {z >= 0.4} are dust that absorbs, but does not redden much, and intrinsic changes in the luminosity of distant supernovae due to the age of the stellar population or the chemical composition of the progenitor stars. We propose to test the generic predictions of composition models and the specific predictions of dust models through very wide wavelength coverage UBVRI observations of 7 supernovae near z = 0.5. These observations, with precise restframe UBVR from HST and restframe I from large groundbased telescopes, will provide enough information for a definitive test of the ``grey'' dust proposal, while they also place the most stringent constraints on differences that could be attributed to chemical differences or age differences between nearby and distant samples of SN Ia. The unique restframe U-band observations proposed here will be especially important in comparing SN Ia at z=0, where we have a sample, and z=0.5, where we don't, and in interpreting the data from very high redshift supernovae with z>=1. Our goal is cosmology, our measuring tool is supernovae, and we need precise, wide wavelength measurements at z=0.5 to test the quality of this yardstick.

Schmidt, Brian

2000-07-01

5

Accelerated testing of space batteries  

NASA Technical Reports Server (NTRS)

An accelerated life test program for space batteries is presented that fully satisfies empirical, statistical, and physical criteria for validity. The program includes thermal and other nonmechanical stress analyses as well as mechanical stress, strain, and rate of strain measurements.

Mccallum, J.; Thomas, R. E.; Waite, J. H.

1973-01-01

6

Thin Film Accelerated Life Tests.  

National Technical Information Service (NTIS)

The purpose of this program was to study, investigate and develop test and measurement techniques for controllably accelerating the aging processes in tantalum thin film R-C networks, and to investigate the physics of failure associated with the networks....

M. J. Walker M. Sharp

1966-01-01

7

RESULTS OF A ROUND ROBIN ON ACCELERATED TESTING OF ABSORBER SURFACE DURABILITY  

Microsoft Academic Search

From April '97 to June '97 a round robin test on accelerated life time testing of absorber coatings was performed by three different laboratories. This investigation was undertaken within a project of the working group 'Materials in Solar Thermal Collectors (MSTC)' of the International Energy Agency - Solar Heating and Cooling Programme (IEA - SHCP). The tests where performed according

S. BRUNOLD; U. FREI; B. CARLSSON; K. MÖLLER; M. KÖHL

1997-01-01

8

Accelerated Testing Validation  

SciTech Connect

The DOE Fuel Cell technical team recommended ASTs were performed on 2 different MEAs (designated P5 and HD6) from Ballard Power Systems. These MEAs were also incorporated into stacks and operated in fuel cell bus modules that were either operated in the field (three P5 buses) in Hamburg, or on an Orange county transit authority drive cycle in the laboratory (HD6 bus module). Qualitative agreement was found in the degradation mechanisms and rates observed in the AST and in the field. The HD6 based MEAs exhibited lower voltage degradation rates (due to catalyst corrosion) and slower membrane degradation rates in the field as reflected by their superior performance in the high potential hold and open-circuit potential AST tests. The quantitative correlation of the degradation rates will have to take into account the various stressors in the field including temperature, relative humidity, start/stops and voltage cycles.

Mukundan, Rangachary; James, Greg; Davey, John; Langlois, David; Torraco, Dennis; Yoon, Wonseok; Weber, Adam Z; Borup, Rodney L.

2011-07-01

9

Designing Accelerated Tests Of Electromigration  

NASA Technical Reports Server (NTRS)

Method for design of accelerated tests of electromigration (as in microscopic conductors in integrated circuits) based partly on simplified mathematical model of electromigration and partly on error analysis. Objective to determine quickly operating life of tested components under normal operating conditions by extrapolation from lifetime measurements at operating stresses greater than normal. Involves compromise between reducing testing time by increasing stresses and reducing uncertainty in extrapolated lifetime by decreasing stresses.

Buehler, Martin G.

1991-01-01

10

NON DESTRUCTIVE TESTING AND EVALUATION OF HETEROGENEOUS SOLIDS USING NON LINEAR ULTRASONICS AND ACOUSTIC EMISSION: TOWARDS THE ASSESSMENT OF THE MATERIAL REMAINING LIFE TIME  

Microsoft Academic Search

Damage is induced in composite plates with integrated ultrasonic transducers using creep and three points bending tests experiments respectively. In situ measurements of the Acoustic Emission (AE) generated by the created damage and the non linear acoustic vibration of the samples are performed. Concerning creep experiment, recorded strain and AE rates exhibit both a power -law acceleration before global failure.

Mourad Bentahar; Hanane Nechad; Anne Marec; Jean-Hugh Thomas

11

Accelerated life testing of spacecraft subsystems  

NASA Technical Reports Server (NTRS)

The rationale and requirements for conducting accelerated life tests on electronic subsystems of spacecraft are presented. A method for applying data on the reliability and temperature sensitivity of the parts contained in a sybsystem to the selection of accelerated life test parameters is described. Additional considerations affecting the formulation of test requirements are identified, and practical limitations of accelerated aging are described.

Wiksten, D.; Swanson, J.

1972-01-01

12

Accelerated testing of space mechanisms  

NASA Technical Reports Server (NTRS)

This report contains a review of various existing life prediction techniques used for a wide range of space mechanisms. Life prediction techniques utilized in other non-space fields such as turbine engine design are also reviewed for applicability to many space mechanism issues. The development of new concepts on how various tribological processes are involved in the life of the complex mechanisms used for space applications are examined. A 'roadmap' for the complete implementation of a tribological prediction approach for complex mechanical systems including standard procedures for test planning, analytical models for life prediction and experimental verification of the life prediction and accelerated testing techniques are discussed. A plan is presented to demonstrate a method for predicting the life and/or performance of a selected space mechanism mechanical component.

Murray, S. Frank; Heshmat, Hooshang

1995-01-01

13

Design considerations and test facilities for accelerated radiation effects testing  

NASA Technical Reports Server (NTRS)

Test design parameters for accelerated dose rate radiation effects tests for spacecraft parts and subsystems used in long term mission (years) are detailed. A facility for use in long term accelerated and unaccelerated testing is described.

Price, W. E.; Miller, C. G.; Parker, R. H.

1972-01-01

14

Protocol Techniques for Testing Radiotherapy Accelerators  

Microsoft Academic Search

The nature of radiotherapy accelerators is briefly explained. It is ar- gued that these complex safety-critical systems need a systematic basis for testing their software. The paper describes a novel application of protocol specification and testing methods to radiotherapy accelerators. An outline specification is given in L OTOS (Language Of Temporal Ordering Specification) of the accelerator con- trol system. It

Kenneth J. Turner; Qian Bing

2002-01-01

15

Test stands for testing serial XFEL accelerator modules  

NASA Astrophysics Data System (ADS)

The superconducting accelerator module is the key component of the European X-ray Free Electron Laser (XFEL) project to be built at DESY Hamburg. The XFEL linear accelerator will consist of 100 accelerator modules in order to produce pulsed electron beam with the energy of 17.5 GeV. All accelerator modules have to be tested after the assembly and before being installed in the accelerator tunnel. The tests will take place in the Accelerator Module Test Facility (AMTF) being constructed at DESY. Besides test stands for testing superconducting cavities and magnets constituting the accelerator modules, AMTF will come with three test stands for testing the completed accelerator modules. This paper describes layout of the test stands within the AMTF, cryogenic design of the test stand, design issues of principal components and schedule.

Bozhko, Yury; Anashin, Vadim; Belova, Lyudmila; Boeckmann, Torsten Axel; Kholopov, Michail; Konstantinov, Valeriy; Petersen, Bernd; Pivovarov, Sergey; Pyata, Eugeny; Sellmann, Detlef; Wang, Xilong; Zhirnov, Anatoly; Zolotov, Anatoly

2012-06-01

16

Design on highway accelerated loading testing facility  

Microsoft Academic Search

Accelerated loading testing facility gains importance for proofing evaluations of structure designs as well as the final evaluation of new pavement materials and functions. So a highway accelerated loading testing facility is developed, which has self-owned intellectual property. The facility is made up of machine frame, a mobile car and a frame for dragging cable. The facility can test and

Zhiguang Guan; Mingxing Lin; Xuguang Wang; Jiwei Zhang

2009-01-01

17

The Next Linear Collider Test Accelerator  

SciTech Connect

During the past several years, there has been tremendous progress on the development of the RF system and accelerating structures for a Next Linear Collider (NLC). Developments include high-power klystrons, RF pulse-compression systems and damped/detuned accelerator structures to reduce wakefields. In order to integrate these separate development efforts into an actual X-band accelerator capable of accelerating the electron beams necessary for an NLC, we plan to build an NLC Test Accelerator (NLCTA). The goal of the NLCTA is to bring together all elements of the entire accelerating system by constructing. and reliably operating an engineered model of a high-gradient linac suitable for the NLC. The NLCTA win serve as a test-bed as the design of the NLC evolves and will provide a model upon which a reliable cost estimate can be based. In addition to testing the RF acceleration system, the NLCTA will be able to address many questions related to the dynamics of the beam during acceleration. In this paper, we will report on the status of the design and component development for the NLC Test Accelerator.

Paterson, J.M.; Ruth, R.D.; Adolphsen, C.; Bane, K.L.; Burke, D.L.; Callin, R.S.; Caryotakis, G.; Cassel, R.L.; Clark, S.L.; Deruyter, H.; Fant, K.; Fuller, R.W.; Heifets, S.A.; Hoag, H.A.; Humphrey, R.; Keicher, A.J.; Kheifets, S.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Menegat, A.; Miller, R.H.; Nordby, M.E.; Pearson, C.; Rifkin, J.; Spencer, J.; Tantawi, S.G.; Thompson, K.A.; Vlieks, A.E.; Vylet, V.; Wang, J.W.; Wilson, P.B.; Yeremian, A.D.; Youngman, B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Kroll, N.M. [California Univ., San Diego, CA (United States); Nantista, C. [California Univ., Los Angeles, CA (United States)

1992-09-01

18

The Next Linear Collider Test Accelerator  

SciTech Connect

During the past several years, there has been tremendous progress the development of the RF system and accelerating structures for a Next Linear Collider (NLC). Developments include high-power klystrons, RF pulse compression systems and damped/detuned accelerator structures to reduce wakefields. In order to integrate these separate development efforts into an actual X-band accelerator capable of accelerating the electron beams necessary for an NLC, we are building an NLC Test Accelerator (NLCTA). The goal of the NLCTA is to bring together all elements of the entire accelerating system by constructing and reliably operating an engineered model of a high-gradient linac suitable for the NLC. The NLCTA will serve as a testbed as the design of the NLC evolves. In addition to testing the RF acceleration system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration. In this paper, we will report oil the status of the design, component development, and construction of the NLC Test Accelerator.

Ruth, R.D.; Adolphsen, C.; Bane, K. [and others

1993-04-01

19

Solid oxide materials research accelerated electrochemical testing  

SciTech Connect

The objectives of this work were to develop methods for accelerated testing of cathode material for solid oxide fuel cells under selected operating conditions. The methods would be used to evaluate the performance of LSM cathode material.

Armstrong, T.R.; Windisch, C.; Arey, B.

1995-12-31

20

Accelerated Testing Of Photothermal Degradation Of Polymers  

NASA Technical Reports Server (NTRS)

Electron-spin-resonance (ESR) spectroscopy and Arrhenius plots used to determine maximum safe temperature for accelerated testing of photothermal degradation of polymers. Aging accelerated by increasing illumination, temperature, or both. Results of aging tests at temperatures higher than those encountered in normal use valid as long as mechanism of degradation same throughout range of temperatures. Transition between different mechanisms at some temperature identified via transition between activation energies, manifesting itself as change in slope of Arrhenius plot at that temperature.

Kim, Soon Sam; Liang, Ranty Hing; Tsay, Fun-Dow

1989-01-01

21

Accelerated Testing of Copper Corrosion  

Microsoft Academic Search

An innovative, short-term corrosion test has been developed that can predict long-term copper corrosion behavior. When used in a six-day study of uniform copper corrosion in five waters, the test predicted corrosion rates that were in good qualitative and quantitative agreement with known long-term (210-day) results. A second phase of the study examined the poorly understood phenomenon of soft-water pitting.

Marc Edwards; John F. Ferguson

1993-01-01

22

SLAC low emittance accelerator test facility  

SciTech Connect

SLAC is proposing to build a new Accelerator Test Facility (ATF) capable of producing a 50 MeV electron beam with an extremely low geometric tranverse emittance (1.5 x 10/sup -10/ rad.m) for the purpose of testing new methods of acceleration. The low emittance will be achieved by assembling a linear accelerator using one standard SLAC three-meter section and a 400 kV electron gun with a very small photocathode (40 microns in diameter). The photocathode will be illuminated from the back by short bursts (on the order of 6 ps) of visible laser light which will produce bunches of about 10/sup 5/ electrons. Higher currents could be obtained by illuminating the cathode from the front. The gun will be mounted directly against the accelerator section. Calculations show that in the absence of an rf buncher, injection of these 400 keV small radius electron bunches roughly 30/sup 0/ ahead of crest produces negligible transverse emittance growth due to radial rf forces. Acceleration of the electrons up to 50 MeV followed by collimation, energy slits and focusing will provide a 3.2 mm long waist of under 1.5 ..mu..m in diameter where laser acceleration and other techniques can be tested.

Loew, G.A.; Miller, R.H.; Sinclair, C.K.

1986-05-01

23

Cathodic Delamination Accelerated Life Test Method.  

National Technical Information Service (NTIS)

A method for conducting an accelerated life test of a polymer coated metallic sample includes placing the sample below the water surface in a test tank containing water and an oxygen containing gas. Cathodic polarization of the metallic portion of the sam...

T. S. Ramotowski

2007-01-01

24

Results from the SLAC NLC Test Accelerator  

NASA Astrophysics Data System (ADS)

The design for the Next Linear Collider (NLC) at SLAC is based on two 11.4 GHz linacs operating at an unloaded acceleration gradient of 50 MV/m increasing to 85 MV/m as the energy is increased from 1/2 TeV to 1 TeV in the center of mass[1]. During the past several years there has been tremendous progress on the development of 11.4 GHz (X-band) RF systems. These developments include klystrons which operate at the required power and pulse length, pulse compression systems that achieve a factor of four power multiplication and structures that are specially designed to reduce long-range wakefields. Together with these developments, we have constructed a 1/2 GeV test accelerator, the NLC Test Accelerator (NLCTA). The NLCTA will serve as a test bed as the design of the NLC is refined. In addition to testing the RF system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration, in particular the study of multibunch beam loading compensation and transverse beam break-up. In this paper we present the results from the initial round of experiments with the NLCTA. In particular we will cover the initial commisioning, experience with beamline and RF instrumentation, and finally, tests of beamloading compensation and transverse beam breakup.

Ruth, Ronald D.

1997-05-01

25

Test Stand for Linear Induction Accelerator Optimization  

SciTech Connect

Lawrence Livermore National Laboratory has designed and constructed a test stand to improve the voltage regulation in our Flash X-Ray (FXR) accelerator cell. The goal is to create a more mono-energetic electron beam that will create an x-ray source with a smaller spot size. Studying the interaction of the beam and pulse-power system with the accelerator cell will improve the design of high-current accelerators at Livermore and elsewhere. On the test stand, a standard FXR cell is driven by a flexible pulse-power system and the beam current is simulated with a switched center conductor. The test stand is fully instrumented with high-speed digitizers to document the effect of impedance mismatches when the cell is operated under various full-voltage conditions. A time-domain reflectometry technique was also developed to characterize the beam and cell interactions by measuring the impedance of the accelerator and pulse-power component. Computer models are being developed in parallel with the testing program to validate the measurements and evaluate different design changes. Both 3D transient electromagnetic and circuit models are being used.

Ong, M; DeHope, B; Griffin, K; Goerz, D; Kihara, R; Vogtlin, G; Zentler, J M; Scarpetti, R

2003-06-03

26

The BNL Accelerator Test Facility control system  

SciTech Connect

Described is the VAX/CAMAC-based control system for Brookhaven National Laboratory's Accelerator Test Facility, a laser/linac research complex. Details of hardware and software configurations are presented along with experiences of using Vsystem, a commercial control system package.

Malone, R.; Bottke, I.; Fernow, R.; Ben-Zvi, I.

1993-01-01

27

Brookhaven Accelerator Test Facility Injection System.  

National Technical Information Service (NTIS)

The Brookhaven Accelerator Test Facility (ATF) consists of a 50-MeV/c electron linac and a high-brightness RF-gun both operating at 2856 MHz. An extremely short (a few picoseconds) electron pulse with low transverse emittance is generated by the RF-gun. I...

X. J. Wang H. G. Kirk C. Pellegrini K. T. McDonald D. P. Russell

1989-01-01

28

Photooxidation and Accelerated Testing of Polypropylene.  

National Technical Information Service (NTIS)

The ultimate objective of the research described here was to devise an accelerated test to predict the useful lives of stabilized polypropylene (PP) resins exposed to sun and weather. The point of departure was a study of radical-initiated oxidations of p...

F. R. Mayo H. Richardson T. Mill

1976-01-01

29

Results from the SLAC NLC test accelerator  

SciTech Connect

The design for the Next Linear Collider (NLC) at SLAC is based on two 11.4 GHz linacs operating at an unloaded acceleration gradient of 50 MV/m increasing to 85 MV/m as the energy is increased from 1/2 TeV to 1 TeV in the center of mass. During the past several years there has been tremendous progress on the development of 11.4 GHz (X-band) RF systems. These developments include klystrons which operate at the required powder and pulse length, pulse compression systems that achieve a factor of four power multiplication and structures that are specially designed to reduce long-range wakefields. Together with these developments, we have constructed a 1/2 GeV test accelerator, the NLC Test Accelerator (NLCTA). The NLCTA will serve as a test bed as the design of the NLC is refined. In addition to testing the RF system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration, in particular, multibunch beam-loading compensation and transverse beam break-up. In this paper we describe the NLCTA and present results from initial experiments.

Ruth, R.D.; Adolphsen, C.; Allison, S. [and others

1997-06-01

30

Humidity Control in Accelerated Life Tests  

Microsoft Academic Search

The humidity-controlled environments over certain saturated salt solutions used for accelerated temperature-humidity life testing have been more accurately characterized. Measurements of relative humidity were made for seven salt solutions at four temperatures: 25, 50, 60, and 80°C. Variations in the experimental test environment were caused by temperature fluctuations and the approach toward uniform salt concentrations in the solutions. Establishing chemical

KATHLEEN L. MCDONALD

1984-01-01

31

BNL ACCELERATOR TEST FACILITY CONTROL SYSTEM UPGRADE.  

SciTech Connect

Brookhaven National Laboratory's Accelerator Test Facility (ATF) has embarked on a complete upgrade of its decade old computer system. The planned improvements affect every major component: processors (Intel Pentium replaces VAXes), operating system (Linux/Real-Time Linux supplants OpenVMS), and data acquisition equipment (fast Ethernet equipment replaces CAMAC serial highway.) This paper summarizes the strategies and progress of the upgrade along with plans for future expansion.

MALONE,R.; BEN-ZVI,I.; WANG,X.; YAKIMENKO,V.

2001-06-18

32

Testing a combined vibration and acceleration environment.  

SciTech Connect

Sandia National Laboratories has previously tested a capability to impose a 7.5 g-rms (30 g peak) radial vibration load up to 2 kHz on a 25 lb object with superimposed 50 g acceleration at its centrifuge facility. This was accomplished by attaching a 3,000 lb Unholtz-Dickie mechanical shaker at the end of the centrifuge arm to create a 'Vibrafuge'. However, the combination of non-radial vibration directions, and linear accelerations higher than 50g's are currently not possible because of the load capabilities of the shaker and the stresses on the internal shaker components due to the combined centrifuge acceleration. Therefore, a new technique using amplified piezo-electric actuators has been developed to surpass the limitations of the mechanical shaker system. They are lightweight, modular and would overcome several limitations presented by the current shaker. They are 'scalable', that is, adding more piezo-electric units in parallel or in series can support larger-weight test articles or displacement/frequency regimes. In addition, the units could be mounted on the centrifuge arm in various configurations to provide a variety of input directions. The design along with test results will be presented to demonstrate the capabilities and limitations of the new piezo-electric Vibrafuge.

Jepsen, Richard Alan; Romero, Edward F.

2005-01-01

33

Ultra-accelerated natural sunlight exposure testing  

DOEpatents

Process and apparatus for providing ultra accelerated natural sunlight exposure testing of samples under controlled weathering without introducing unrealistic failure mechanisms in exposed materials and without breaking reciprocity relationships between flux exposure levels and cumulative dose that includes multiple concurrent levels of temperature and relative humidity at high levels of natural sunlight comprising: a) concentrating solar flux uniformly; b) directing the controlled uniform sunlight onto sample materials in a chamber enclosing multiple concurrent levels of temperature and relative humidity to allow the sample materials to be subjected to accelerated irradiance exposure factors for a sufficient period of time in days to provide a corresponding time of about at least a years worth of representative weathering of the sample materials.

Jorgensen, Gary J. (Pine, CO); Bingham, Carl (Lakewood, CO); Goggin, Rita (Englewood, CO); Lewandowski, Allan A. (Evergreen, CO); Netter, Judy C. (Westminster, CO)

2000-06-13

34

Commissioning of the Ground Test Accelerator RFQ  

SciTech Connect

The Ground Test Accelerator (GTA) has the objective of verifying much of the technology (physics and engineering) required for producing high-brightness, high-current H{sup {minus}} beams. GTA commissioning is staged to verify the beam dynamics design of each major accelerator component as it is brought on-line. The commissioning stages are the 35 key H{sup {minus}} injector, the 2.5 MeV Radio Frequency Quadrupole (RFQ), the Intertank Matching Section (IMS), the 3.2 MeV first 2{beta}{gamma} Drift Tube Linac (DTL-1) module, the 8.7 MeV 2{beta}{gamma} DTL (modules 1--5), and the 24 MeV GTA; all 10 DTL modules. Commissioning results from the RFQ beam experiments will be presented along with comparisons to simulations.

Johnson, K.F.; Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Brown, S.; Connolly, R.; Garnett, R.; Gilpatrick, J.D.; Guy, F.W.; Ingalls, W.B.; Little, C.; Lohson, R.A.; Lloyd, S.; Neuschaefer, G.; Power, J.; Saadatmand, K.; Sandoval, D.P.; Stevens, R.R.; Vaughn, G.; Wadlinger, E.A.; Weiss, R.; Yuan, V.

1992-09-01

35

Commissioning of the Ground Test Accelerator RFQ  

SciTech Connect

The Ground Test Accelerator (GTA) has the objective of verifying much of the technology (physics and engineering) required for producing high-brightness, high-current H{sup {minus}} beams. GTA commissioning is staged to verify the beam dynamics design of each major accelerator component as it is brought on-line. The commissioning stages are the 35 key H{sup {minus}} injector, the 2.5 MeV Radio Frequency Quadrupole (RFQ), the Intertank Matching Section (IMS), the 3.2 MeV first 2{beta}{gamma} Drift Tube Linac (DTL-1) module, the 8.7 MeV 2{beta}{gamma} DTL (modules 1--5), and the 24 MeV GTA; all 10 DTL modules. Commissioning results from the RFQ beam experiments will be presented along with comparisons to simulations.

Johnson, K.F.; Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Brown, S.; Connolly, R.; Garnett, R.; Gilpatrick, J.D.; Guy, F.W.; Ingalls, W.B.; Little, C.; Lohson, R.A.; Lloyd, S.; Neuschaefer, G.; Power, J.; Saadatmand, K.; Sandoval, D.P.; Stevens, R.R.; Vaughn, G.; Wadlinger, E.A.; Weiss, R.; Yuan, V.

1992-01-01

36

Accelerated Leach Test(s) Program: Annual report  

SciTech Connect

A computerized data base of LLW leaching data has been developed. Long-term tests on portland cement, bitumen and vinyl ester-styrene (VES) polymer waste forms containing simulated wastes are underway which are designed to identify and evaluate factors that accelerate leaching without changing the mechanisms.

Dougherty, D.R.; Pietrzak, R.F.; Fuhrmann, M.; Colombo, P.

1986-09-01

37

Role of failure-mechanism identification in accelerated testing  

NASA Technical Reports Server (NTRS)

Accelerated life testing techniques provide a short-cut method to investigate the reliability of electronic devices with respect to certain dominant failure mechanisms that occur under normal operating conditions. However, accelerated tests have often been conducted without knowledge of the failure mechanisms and without ensuring that the test accelerated the same mechanism as that observed under normal operating conditions. This paper summarizes common failure mechanisms in electronic devices and packages and investigates possible failure mechanism shifting during accelerated testing.

Hu, J. M.; Barker, D.; Dasgupta, A.; Arora, A.

1993-01-01

38

Induction accelerator test module for HIF  

SciTech Connect

An induction linac test module suitable for investigating the drive requirements and the longitudinal coupling impedance of a high-power ion induction linac has been constructed by the Heavy Ion Fusion (HIF) group at LBL. The induction linac heavy ion driver for inertial confinement fusion (ICF) as presently envisioned uses multiple parallel beams which are transported in separate focusing channels but accelerated together in the induction modules. The resulting induction modules consequently have large beam apertures-1--2 meters in diameter- and correspondingly large outside diameters. The module geometry is related to a low-frequency gap capacity'' and high-frequency structural resonances, which are affected by the magnetic core loading and the module pulser impedance. A description of the test module and preliminary results are presented. 3 figs.

Faltens, A.

1991-04-01

39

Operational experience on the Brookhaven National Laboratory Accelerator Test Facility  

SciTech Connect

Brookhaven National Laboratory Accelerator Test Facility is a laser-electron linear accelerator complex designed to provide high brightness beams for testing of advanced acceleration concepts and high power pulsed photon sources. Results of electron beam parameters attained during the commissioning of the nominally 45 MeV energy machine are presented.

Batchelor, K.; Babzien, M.; Ben-Zvi, I. [and others

1994-09-01

40

Accelerated Strength Testing of Thermoplastic Composites  

NASA Technical Reports Server (NTRS)

Constant ramp strength tests on unidirectional thermoplastic composite specimens oriented in the 90 deg. direction were conducted at constant temperatures ranging from 149 C to 232 C. Ramp rates spanning 5 orders of magnitude were tested so that failures occurred in the range from 0.5 sec. to 24 hrs. (0.5 to 100,000 MPa/sec). Below 204 C, time-temperature superposition held allowing strength at longer times to be estimated from strength tests at shorter times but higher temperatures. The data indicated that a 50% drop in strength might be expected for this material when the test time is increased by 9 orders of magnitude. The shift factors derived from compliance data applied well to the strength results. To explain the link between compliance and strength, a viscoelastic fracture model was investigated. The model, which used compliance as input, was found to fit the strength data only if the critical fracture energy was allowed to vary with temperature reduced stress rate. This variation in the critical parameter severely limits its use in developing a robust time-dependent strength model. The significance of this research is therefore seen as providing both the indication that a more versatile acceleration method for strength can be developed and the evidence that such a method is needed.

Reeder, J. R.; Allen, D. H.; Bradley, W. L.

1998-01-01

41

Testing Planck-scale gravity with accelerators.  

PubMed

Quantum or torsion gravity models predict unusual properties of space-time at very short distances. In particular, near the Planck length, around 10(-35)??m, empty space may behave as a crystal, singly or doubly refractive. However, this hypothesis remains uncheckable for any direct measurement, since the smallest distance accessible in experiment is about 10(-19)??m at the LHC. Here I propose a laboratory test to measure the space refractivity and birefringence induced by gravity. A sensitivity from 10(-31)??m down to the Planck length could be reached at existent GeV and future TeV energy lepton accelerators using laser Compton scattering. There are already experimental hints for gravity signature at distances approaching the Planck length by 5-7 orders of magnitude, derived from SLC and HERA data. PMID:23083234

Gharibyan, Vahagn

2012-10-01

42

Testing Planck-Scale Gravity with Accelerators  

NASA Astrophysics Data System (ADS)

Quantum or torsion gravity models predict unusual properties of space-time at very short distances. In particular, near the Planck length, around 10-35m, empty space may behave as a crystal, singly or doubly refractive. However, this hypothesis remains uncheckable for any direct measurement, since the smallest distance accessible in experiment is about 10-19m at the LHC. Here I propose a laboratory test to measure the space refractivity and birefringence induced by gravity. A sensitivity from 10-31m down to the Planck length could be reached at existent GeV and future TeV energy lepton accelerators using laser Compton scattering. There are already experimental hints for gravity signature at distances approaching the Planck length by 5-7 orders of magnitude, derived from SLC and HERA data.

Gharibyan, Vahagn

2012-10-01

43

Advanced Test Accelerator: A High-Current Induction Linac.  

National Technical Information Service (NTIS)

The Advanced Test Accelerator (ATA) is a linear induction accelerator being built at Lawrence Livermore National Laboratory. The aim of the ATA, together with its associated physics program is the research and development necessary to resolve whether part...

E. G. Cook D. L. Birx L. L. Reginato

1982-01-01

44

The Next Linear Collider Test Accelerator  

Microsoft Academic Search

During the past several years, there has been tremendous progress on the development of the RF system and accelerating structures for a Next Linear Collider (NLC). Developments include high-power klystrons, RF pulse compression systems and damped\\/detuned accelerator structures to reduce wakefields. In order to integrate these separate development efforts into an actual X-band accelerator capable of accelerating the electron beams

R. D. Ruth; C. Adolphsen; K. Bane; R. F. Boyce; D. L. Burke; R. Callin; G. Caryotakis; R. Cassel; S. L. Clark; H. Deruyter; K. Fant; R. Fuller; S. Heifets; H. Hoag; R. Humphrey; S. Kheifets; R. Koontz; N. M. Kroll; R. T. Lavine; G. A. Loew; A. Menegat; R. H. Miller; C. Nantista; J. M. Paterson; C. Pearson; R. Phillips; J. Rifkin; J. Spencer; S. Tantawi; K. A. Thompson; A. Vlieks; V. Vylet; J. W. Wang; P. B. Wilson; A. Yeremian; B. Youngman

1993-01-01

45

VMAT testing for an Elekta accelerator.  

PubMed

Volumetric-modulated arc therapy (VMAT) has been shown to be able to deliver plans equivalent to intensity-modulated radiation therapy (IMRT) in a fraction of the treatment time. This improvement is important for patient immobilization/localization compliance due to comfort and treatment duration, as well as patient throughput. Previous authors have suggested commissioning methods for this modality. Here, we extend the methods reported for the Varian RapidArc system (which tested individual system components) to the Elekta linear accelerator, using custom files built using the Elekta iComCAT software. We also extend the method reported for VMAT commissioning of the Elekta accelerator by verifying maximum values of parameters (gantry speed, multileaf collimator (MLC) speed, and backup jaw speed), investigating: 1) beam profiles as a function of dose rate during an arc, 2) over/under dosing due to MLC reversals, and 3) over/under dosing at changing dose rate junctions. Equations for construction of the iComCAT files are given. Results indicate that the beam profile for lower dose rates varies less than 3% from that of the maximum dose rate, with no difference during an arc. The gantry, MLC, and backup jaw maximum speed are internally consistent. The monitor unit chamber is stable over the MUs and gantry movement conditions expected. MLC movement and position during VMAT delivery are within IMRT tolerances. Dose rate, gantry speed, and MLC speed are accurately controlled. Over/under dosing at junctions of MLC reversals or dose rate changes are within clinical acceptability. PMID:22402389

Kaurin, Darryl Gl; Sweeney, Larry E; Marshall, Edward I; Mahendra, Saikanth

2012-01-01

46

First partial Siberian snake test during acceleration  

SciTech Connect

The authors studied the acceleration of a spin-polarized beam through a depolarizing resonance using a partial Siberian snake. They accelerated polarized protons from 95 to 140 MeV while ramping a 10% partial Siberian snake along with the acceleration cycle. The 10% partial snake suppressed all observable depolarization during acceleration due to the G{gamma}=2 imperfection depolarizing resonance which occurred near 108 MeV. However, 20% and 30% partial Siberian snakes apparently moved an intrinsic depolarization resonance, normally near 177 MeV, into this energy range; this caused some interesting but not-yet-fully understood depolarization.

Varzar, S.M.; Alexeeva, L.V.; Blinov, B.B. [Univ. of Michigan, Ann Arbor, MI (United States)] [and others

1995-04-01

47

Accelerated Leach Test(s) Program. Annual report  

SciTech Connect

This report summarizes the work performed for the Accelerated Leach Test(s) Program at Brookhaven National Laboratory in Fiscal Year 1985 under the sponsorship of the US Department of Energy's Low-Level Waste Management Program (LLWMP). Programmatic activities were concentrated in three areas, as listed and described in the following paragraphs. (1) A literature survey of reported leaching mechanisms, available mathematical models and factors that affect leaching of LLW forms has been compiled. Mechanisms which have been identified include diffusion, dissolution, ion exchange, corrosion and surface effects. Available mathematical models are based on diffusion as the predominant mechanism. Although numerous factors that affect leaching have been identified, they have been conveniently categorized as factors related to the entire leaching system, to the leachant or to the waste form. A report has been published on the results of this literature survey. (2) A computerized data base of LLW leaching data and mathematical models is being developed. The data are being used for model evaluation by curve fitting and statistical analysis according to standard procedures of statistical quality control. (3) Long-term tests on portland cement, bitumen and vinyl ester-styrene (VES) polymer waste forms are underway which are designed to identify and evaluate factors that accelerate leaching without changing the mechanisms. Results on the effect of temperature on leachability indicate that the leach rates of cement and VES waste forms increase with increasing temperature, whereas, the leach rate of bitumen is little affected.

Dougherty, D.R.; Fuhrmann, M.; Colombo, P.

1985-09-01

48

Nonparametric Estimation from Accelerated Life Tests with Random Censorship.  

National Technical Information Service (NTIS)

For an accelerated life test, let V sub 1,...,V sub k denote k fixed accelerated stresses and let V sub 0 be the normal stress. It is assumed that the probability distributions corresponding to the accelerated stresses differ from the nonaccelerated life ...

W. J. Padgett D. T. McNichols

1984-01-01

49

An Accelerated Life Test for Evaluating Power Cable Insulation  

Microsoft Academic Search

For many years, the power cable industry has sought an accelerated test that would quantitatively evaluate the life of polyethylene insulation for high voltage cables. This paper describes preliminary results leading to development of such a test. This test employs full size cables with accelerating factors such as temperature, water, electrical stress, frequency and mechanical stress. Times-to-failure for thernnplastic and

R. Lyle; J. W. Kirkland

1981-01-01

50

The Advanced Test Accelerator (ATA) experience  

SciTech Connect

On January 26, 1990 at 20:03:30, the Advanced Test Accelerator (ATA) was turned off with the shot counter reading 12,425,999. During the interval between 1985 and 1990 there were eight major experiments performed at ATA. Three of these experiments were for the Free Electron Laser program, and five were for the Charged Particle Beam (CPB) program. The five experiments were: Spring 1985 Propagation Experiment (April 1985), December 1985 20m Propagation Experiment (December 1985), Open Air Experiment (March--June 1987), Beam Transport Experiment (Spring 1988), and Multi Pulse Propagation Experiment (September 89--January 90). Several new technologies such as the rise time sharpener, the Beam Director, and the Fast Corrector Coil were also developed. Experiments for diagnostic development such as the transition radiation studies were also conducted. In this report the major experiments will be revisited; their highlights and shortcomings will be outlined. The current view on the understanding of lead pulse stability and CPB feasibility will be discussed.

Chambers, F.W.

1990-10-01

51

Reliability assessment of seat belt webbings through accelerated life testing  

Microsoft Academic Search

A reliability assessment method for seat belt webbings is proposed based on life–stress relationships combined with statistical distribution using a newly designed accelerated test equipment. The method was successfully used to predict lifetimes of webbing by performing an accelerated life test (ALT) which was designed using more severe temperatures, UV irradiance and abrasion as stress factors. The failure times obtained

Hyun-Jin Koo; You-Kyum Kim

2005-01-01

52

A Survey of Methods for Planning and Analyzing Accelerated Tests  

Microsoft Academic Search

This paper surveys methods for planning and analyzing accelerated life tests. Many of these methods are new and providemore informative results for less time and cost than do previous methods. These methods are of value to all who plan and analyze accelerated tests on any product or material.

Wayne Nelson

1974-01-01

53

Accelerated life testing effects on CMOS microcircuit characteristics  

NASA Technical Reports Server (NTRS)

The 250 C, 200C and 125C accelerated tests are described. The wear-out distributions from the 250 and 200 C tests were used to estimate the activation energy between the two test temperatures. The duration of the 125 C test was not sufficient to bring the test devices into the wear-out region. It was estimated that, for the most complex of the three devices types, the activation energy between 200 C and 125 C should be at least as high as that between 250 C and 200 C. The practicality of the use of high temperature for the accelerated life tests from the point of view of durability of equipment is assessed. Guidlines for the development of accelerated life-test conditions are proposed. The use of the silicon nitride overcoat to improve the high temperature accelerated life-test characteristics of CMOS microcircuits is described.

1980-01-01

54

Terrestrial Photovoltaic Module Accelerated Test-To-Failure Protocol  

SciTech Connect

This technical report documents a test-to-failure protocol that may be used to obtain quantitative information about the reliability of photovoltaic modules using accelerated testing in environmental temperature-humidity chambers.

Osterwald, C. R.

2008-03-01

55

Acceleration Test for Aircraft Low-Pass Filter,  

National Technical Information Service (NTIS)

The paper introduces a constant intensive acceleration endurance test method. 40 paper-capacitor low-pass filters have been selected at random sampling for the reliability endurance test at four intensive levels on the increased temperature. According to ...

Z. Zhang

1988-01-01

56

Ground test accelerator control system software  

SciTech Connect

The GTA control system provides an environment in which the automation of a state-of-the-art accelerator can be developed. It makes use of commercially available computers, workstations, computer networks, industrial I/O equipment, and software. This system has built-in supervisory control (like most accelerator control systems), tools to support continuous control (like the process control industry), and sequential control for automatic startup and fault recovery (like few other accelerator control systems). Several software tools support these levels of control: a real-time operating system (VxWorks) with a real-time kernel (VRTX), a configuration database, a sequencer, and a graphics editor. VxWorks supports multitasking, fast context-switching, and preemptive scheduling. VxWorks/VRTX is a network-based development environment specifically designed to work in partnership with the UNIX operating system. A database provides the interface to the accelerator components. It consists of a run time library and a database configuration and editing tool. A sequencer initiates and controls the operation of all sequence programs (expressed as state programs). A graphics editor gives the user the ability to create color graphic displays showing the state of the machine in either text or graphics form. 11 refs., 2 figs.

Burczyk, L.; Dalesio, R.; Dingler, R.; Hill, J.; Howell, J.A.; Kerstiens, D.; King, R.; Kozubal, A.; Little, C.; Martz, V.; Rothrock, R.; Sutton, J.

1988-01-01

57

New acceleration factors for temperature, humidity, bias testing  

Microsoft Academic Search

New temperature-humidity acceleration factors for surface conductance (G) were determined. These can be used to relate device life in a high-stress laboratory environment to device life in a normal-use environment. Analytical expressions for the acceleration factors were derived for both encapsulated and unencapsulated test specimens. Lower acceleration factors were predicted for specimens encapsulated with DC 3-6550 RTV silicone rubber than

N. L. Sbar; R. P. Kozakiewicz

1979-01-01

58

Timescale Correlation between Marine Atmospheric Exposure and Accelerated Corrosion Testing  

NASA Technical Reports Server (NTRS)

Evaluation of metal-based structures has long relied on atmospheric exposure test sites to determine corrosion resistance in marine environments. Traditional accelerated corrosion testing relies on mimicking the exposure conditions, often incorporating salt spray and ultraviolet (UV) radiation, and exposing the metal to continuous or cyclic conditions of the corrosive environment. Their success for correlation to atmospheric exposure is often a concern when determining the timescale to which the accelerated tests can be related. Accelerated laboratory testing, which often focuses on the electrochemical reactions that occur during corrosion conditions, has yet to be universally accepted as a useful tool in predicting the long term service life of a metal despite its ability to rapidly induce corrosion. Although visual and mass loss methods of evaluating corrosion are the standard and their use is imperative, a method that correlates timescales from atmospheric exposure to accelerated testing would be very valuable. This work uses surface chemistry to interpret the chemical changes occurring on low carbon steel during atmospheric and accelerated corrosion conditions with the objective of finding a correlation between its accelerated and long-term corrosion performance. The current results of correlating data from marine atmospheric exposure conditions at the Kennedy Space Center beachside corrosion test site, alternating seawater spray, and immersion in typical electrochemical laboratory conditions, will be presented. Key words: atmospheric exposure, accelerated corrosion testing, alternating seawater spray, marine, correlation, seawater, carbon steel, long-term corrosion performance prediction, X-ray photoelectron spectroscopy.

Montgomery, Eliza L.; Calle, Luz Marina; Curran, Jerone C.; Kolody, Mark R.

2011-01-01

59

4Rod RFQ Proton Acceleration Tests  

Microsoft Academic Search

A 4-Rod RFQ was constructed to accelerate protons from 30 keV to 100 KeV. The PARMTEQ code was used to determine the RFQ parameters at the operating frequency of 100 MHz and 10 kV inter-electrode voltage. The RFQ structure was installed in the copper tank of 190 mm diameter. The resonant frequency was tuned to within 1% of the design

Hiroshi FUJISAWA; Yoshihisa IWASHITA; Hidekuni TAKEKOSHI

1989-01-01

60

Miniature penetrator (MinPen) acceleration recorder development test  

SciTech Connect

The Telemetry Technology Development Department at Sandia National Laboratories actively develops and tests acceleration recorders for penetrating weapons. This new acceleration recorder (MinPen) utilizes a microprocessor-based architecture for operational flexibility while maintaining electronics and packaging techniques developed over years of penetrator testing. MinPen has been demonstrated to function in shock environments up to 20,000 Gs. The MinPen instrumentation development has resulted in a rugged, versatile, miniature acceleration recorder and is a valuable tool for penetrator testing in a wide range of applications.

Franco, R.J.; Platzbecker, M.R.

1998-08-01

61

Power-Conditioning System for the Advanced Test Accelerator.  

National Technical Information Service (NTIS)

The Advanced Test Accelerator (ATA) is a pulsed, linear induction, electron accelerator currently under construction and nearing completion at Lawrence Livermore National Laboratory's Site 300 near Livermore, California. The ATA is a 50 MeV, 10 kA machine...

M. A. Newton M. E. Smith D. L. Birx D. R. Branum E. G. Cook

1982-01-01

62

Computer modeling of test particle acceleration at oblique shocks  

Microsoft Academic Search

We review the basic techniques and results of numerical codes used to model the acceleration of charged particles at oblique, fast-mode, collisionless shocks. The emphasis is upon models in which accelerated particles (ions) are treated as test particles, and particle dynamics is calculated by numerically integrating along exact phase-space orbits. We first review the case where ions are sufficiently energetic

Robert B. Decker

1988-01-01

63

Accelerated Life Testing Effects on CMOS Microcircuit Characteristics.  

National Technical Information Service (NTIS)

The 250 C, 200C and 125C accelerated tests are described. The wear-out distributions from the 250 and 200 C tests were used to estimate the activation energy between the two test temperatures. The duration of the 125 C test was not sufficient to bring the...

1980-01-01

64

The Accelerator Test Facility at Brookhaven: Main capabilities  

NASA Astrophysics Data System (ADS)

Brookhaven National Laboratory's (BNL's) Accelerator Test Facility (ATF) is a user facility for accelerator- and beam- physics. Researchers from national and foreign universities, the DOE's national laboratories, and small businesses can carry out their experiments here, thereby relieving their institutions and companies from the large investment in accelerators, lasers, control and diagnostic equipment, and trained accelerator operators, all of which BNL's ATF offers. The main emphasis of this paper is on the capabilities of the ATF that I illustrate by discussing a few experiments. More detailed information can be obtained from the ATF web site: http://www.bnl.gov/atf.

Yakimenko, Vitaly

2004-12-01

65

Voltage Stress Effects on Microcircuit Accelerated Life Test Failure Rates.  

National Technical Information Service (NTIS)

The applicability of Arrhenius and Eyring reaction rate models for describing microcircuit aging characteristics as a function of junction temperature and applied voltage was evaluated. The results of a matrix of accelerated life tests with a single metal...

G. M. Johnson

1976-01-01

66

On Accelerated Fatigue Testing of Prosthetic Heart Valves  

Microsoft Academic Search

\\u000a Accelerated testing (AT) of prosthetic heart valves allows simulation of wear and fatigue sustained by the replacement heart\\u000a valves, and to estimate the valves’ life expectancy in human body. At accelerated test rates, sufficient amounts of data can\\u000a be collected within a reasonably short time period, after repeated opening and closing cycles, to predict the valve durability.\\u000a The U.S. Food

Po-Chien Lu; Jia-shing Liu; Baoshu Xi; Shawyan Li; Jia Wu; Ned H. C. Hwang

67

On the life time of contrail cirrus  

NASA Astrophysics Data System (ADS)

Contrails represent reproducible prototypes of cirrus clouds which are easier to understand scientifically and offer better chances for experimental investigations than natural cirrus. In the past, investigation of contrails led to important general insight into the atmosphere system, such as the detection of ice supersaturation, homogeneous and heterogeneous ice particle formation, and subvisible cirrus. Even the Brewer-Dobson circulation was detected because contrails were observed to be short-lived at multitudes above the tropopause. Here we present results constraining the mean life time of contrail cirrus based on comparisons of results from a new contrail cirrus model, ECMWF forecast data and several years of Meteosat satellite observations for the North Atlantic and Europe. The mean life time of contrails is not yet well known. Persistent contrails form at aviation cruise altitudes mainly in the upper troposphere, when the temperature is below the Schmidt-Appleman (SAC) threshold temperature and when the ambient atmosphere is humid enough for long-lived contrails. The SAC threshold depends on aircraft and fuel properties, pressure and humidity. Contrails spread and persist in ice supersaturated air masses. Contrails are visible also for several minutes or even longer when the relative humidity is slightly below saturation, in particular at low temperatures. Contrails survive until the ambient air gets dried beyond ice saturation (e.g. by subsidence, mixing with dry air, radiative warming) or until the ice particles get large enough to sediment quickly and to fall down into drier air masses or, rarely, precipitate to ground. Contrails with large ice particles may end in fallstreaks (i.e. in a curtain of large and quickly falling ice particles). With time, contrails may loose their identity and become part of other thicker cirrus clouds. We model the formation and decay of contrails for a fleet of aircraft using a recently developed Lagrangian contrail cirrus prediction model CoCiP (Schumann, U.: A contrail cirrus prediction model, Geosci. Model Dev. Discuss., 4, 3185-3293, doi:10.5194/gmdd-4-3185-2011, 2011). The formation of contrails and their transition into contrail cirrus is modeled for given aircraft types, aircraft tracks and given meteorology (taken from ECMWF). We found that the computed contrail cover is highly sensitive to the processes which limit the life time of contrail cirrus. The life-time of contrail clusters should be similar to the lifetime of ice supersaturated regions (ISSR) which has been estimated at mid-latitudes to vary from minutes to possibly a few days with median values of order hours. Here, we estimate the life-time of ISSR regions by computing the age of trajectories which start at aircraft waypoints satisfying the SAC in ice supersaturated air and last until the ambient humidity drops below ice saturation. This aircraft-related ISSR-life-time is not the life-time of ISSR per se, but the life-time of ice supersaturation relevant for contrails. For this purpose we use the Lagrangian trajectory model part of CoCiP for a passive tracer with ECMWF data. Most of such trajectories end after less than one hour. The age frequency distribution follows an exponential function. Based on such a fit the mean and median ages of ISSR regions are 14.6 and 10.1 h. The life time depends on many parameters; it is large in particular in the upper and mid polar and upper tropical troposphere. When we apply CoCiP for contrails including ice formation form ambient ice supersaturation but without any particle number loss process, we compute ages which exceed the ISSR ages. The larger life time result from the reservoir of ice water built up in the contrails while staying in the ISSR. This ice water reservoir is a maximum just when the ISSR regime ends. It takes considerable time to mix drier ambient air into the contrail and to sublimate this ice. Hence, the total contrail age without ice loss processes could reach about 1.5 times the age of ISSR masses. With some loss processes included in the model, the c

Schumann, U.; Graf, K.

2012-04-01

68

Accelerated biocatalyst stability testing for process optimization.  

PubMed

The deactivation of protein biocatalysts even at relatively low temperatures is one of the principal drawbacks to their use. To aid in the development of novel biocatalysts, we have derived an equation for both time- and temperature-dependent activity of the biocatalyst based on known concepts such as transition state theory and the Lumry-Eyring model. We then derived an analytical solution for the total turnover number (ttn), under isothermal operation, as a function of the catalytic constant kcat, the unfolding equilibrium constant K, and the intrinsic first-order deactivation rate constant(s) k(d,i). Employing an immobilized glucose isomerase biocatalyst in a CSTR and utilizing a linear temperature ramp beyond the Tm of the enzyme, we demonstrate an accelerated method for extracting the thermodynamic and kinetic constants describing the biocatalyst system. In addition, we demonstrate that the predicted biocatalyst behavior at different temperatures and reaction times is consistent with the experimental observations. PMID:15932254

Gibbs, Phillip R; Uehara, Christian S; Neunert, Urban; Bommarius, Andreas S

2005-01-01

69

Accelerated life testing effects on CMOS microcircuit characteristics  

NASA Technical Reports Server (NTRS)

Accelerated life tests were performed on CMOS microcircuits to predict their long term reliability. The consistency of the CMOS microcircuit activation energy between the range of 125 C to 200 C and the range 200 C to 250 C was determined. Results indicate CMOS complexity and the amount of moisture detected inside the devices after testing influences time to failure of tested CMOS devices.

1977-01-01

70

Accelerated life testing effects on CMOS microcircuit characteristics  

NASA Technical Reports Server (NTRS)

This report covers the time period from May 1976 to December 1979 and encompasses the three phases of accelerated testing: Phase 1, the 250 C testing; Phase 2, the 200 C testing; and Phase 3, the 125 C testing. The duration of the test in Phase 1 and Phase 2 was sufficient to take the devices into the wear out region. The wear out distributions were used to estimate the activation energy between the 250 C and the 200 C test temperatures. The duration of the 125 C test, 20,000 hours, was not sufficient to bring the test devices into the wear out region; consequently the third data point at 125 C for determining the consistency of activation energy could not be obtained. It was estimated that, for the most complex of the three device types, the activation energy between 200 C and 125 C should be at least as high as that between 250 C and 200 C. The practicality of the use of high temperature for the accelerated life tests from the point of view of durability of equipment was assessed. Guidelines for the development of accelerated life test conditions were proposed. The use of the silicon nitride overcoat to improve the high temperature accelerated life test characteristics of CMOS microcircuits was explored in Phase 4 of this study and is attached as an appendix to this report.

1980-01-01

71

Accelerator Tests of the KLEM Prototypes  

NASA Technical Reports Server (NTRS)

The Kinematic Lightweight Energy Meter (KLEM) device is planned for direct measurement of the elemental energy spectra of high-energy (10(exp 11)-10(exp 16) eV) cosmic rays. The first KLEM prototype has been tested at CERN with 180 GeV pion beam in 2001. A modified KLEM prototype will be tested in proton and heavy ion beams to give more experimental data on energy resolution and charge resolution with KLEM method. The first test results are presented and compared with simulations.

Bashindzhagyan, G.; Adams, J. H.; Bashindzhagyan, P.; Baranova, N.; Christl, M.; Chilingarian, A.; Chupin, I.; Derrickson, J.; Drury, L.; Egorov, N.

2003-01-01

72

Accelerated Durability Testing of Electrochromic Windows  

Microsoft Academic Search

Prototype electrochromic windows made by several different U.S. companies have been tested in our laboratory for their long-term durability. Samples were subjected to alternate coloring and bleaching voltage cycles while exposed to simulated on 1-sun irradiance in a temperature-controlled environmental chamber with low relative humidity. The samples inside the chamber were tested under a matrix of different conditions. These conditions

C. E. Tracy; J. G. Zhang; D. K. Benson; A. W. Czanderna; S. K. Deb

1998-01-01

73

Accelerated durability testing of electrochromic windows  

Microsoft Academic Search

Prototype electrochromic windows made by several different US companies have been tested in our laboratory for their long-term durability. Samples were subjected to alternate coloring and bleaching voltage cycles while exposed to simulated 1-sun irradiance in a temperature-controlled environmental chamber with low relative humidity. The samples inside the chamber were tested under a matrix of different conditions. These conditions include:

C. E. Tracy; J.-G Zhang; D. K. Benson; A. W. Czanderna; S. K. Deb

1999-01-01

74

Testing of a high current dc ESQ accelerator  

SciTech Connect

A high current dc electrostatic quadrupole (ESQ) accelerator is being developed for negative-ion-based neutral beam heating and current drive on the next generation tokamak. Beam energy and current will eventually be in the MeV and multiampere range.l This CCVV (constant- current variable-voltage) accelerator uses a series of identical ESQ modules. We have successfully tested a prototype CCVV accelerator up to 200 keV with a 100 mA He{sub +} beam (with space charge equivalence of 140 mA of D{sup {minus}}) for a pulse length of 1 s. Testing was also done with a 42 mA H{sup {minus}} beam (H{sup {minus}} beam current was limited by source performance). There was almost no beam loss in the ESQ accelerator. no emittance growth was found in the beam injected from the preaccelerator into the ESQ accelerator had low aberration. We are presently designing a proof-of- principle one-channel CCVV accelerator that would accelerate 1.0 A of D{sup {minus}} 1.3 MeV energy. 4 refs., 7 figs.

Kwan, J.W.; Ackerman, G.D.; Ackerman, O.A.; Chan, C.F.; Cooper, W.S.; deVries, G.J.; Kunkel, W.B.; Soroka, L.; Steele, W.F.; Wells, R.P.

1991-05-01

75

Preliminary description of the ground test accelerator cryogenic cooling system  

SciTech Connect

The Ground Test Accelerator (GTA) under construction at the Los Alamos National Laboratory is part of the Neutral Particle Beam Program supported by the Strategic Defense Initiative Office. The GTA is a full-sized test facility to evaluate the feasibility of using a negative ion accelerator to produce a neutral particle beam (NPB). The NPB would ultimately be used outside the earth's atmosphere as a target discriminator or as a directed energy weapon. The operation of the GTA at cryogenic temperature is advantageous for two reasons: first, the decrease of temperature caused a corresponding decrease in the rf heating of the copper in the various units of the accelerator, and second, at the lower temperature the decrease in the thermal expansion coefficient also provides greater thermal stability and consequently, better operating stability for the accelerator. This paper discusses the cryogenic cooling system needed to achieve these advantages. 5 figs., 3 tabs.

Edeskuty, F.J.; Stewart, W.F.

1988-01-01

76

A test accelerator for the next linear collider  

SciTech Connect

At SLAC, the authors are pursuing the design of a Next Linear Collider (NLC) which would begin with a center-of-mass energy of 0.5 TeV, and be upgradable to at least 1.0 TeV. To achieve this high energy, they have been working on the development of a high-gradient 11.4-GHz (X-band) linear accelerator for the main linac of the collider. In this paper, they present the design of a {open_quotes}Next Linear Collider Test Accelerator{close_quotes} (NLCTA). The goal of the NLCTA is to incorporate the new technologies of X-band accelerator structures, RF pulse compression systems and klystrons into a short linac which will then be a test bed for beam dynamics issues related to high-gradient acceleration.

Ruth, R.D.; Adolphsen, C.; Bane, K.; Boyce, R.F.; Burke, D.L.; Callin, R.; Caryotakis, G.; Cassel, R.; Clark, S.L.; Deruyter, H.; Fant, K.; Fuller, R.; Heifets, S.; Hoag, H.; Humphrey, R.; Kheifets, S.; Koontz, R.; Lavine, T.; Loew, G.A.; Menegat, A.; Miller, R.H.; Paterson, J.M.; Pearson, C.; Phillips, R.; Rifkin, J.; Spencer, J.; Tantawi, S.; Thompson, K.A.; Vlieks, A.; Vylet, V.; Wang, J.W.; Wilson, P.B.; Yeremian, A.; Youngman, B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Kroll, N.M. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)]|[California Univ., San Diego, CA (United States); Nantista, C. [California Univ., Los Angeles, CA (United States)

1993-07-01

77

The Next Linear Collider test accelerator: Status and results  

SciTech Connect

At SLAC, the authors are pursuing the design of a Next Linear Collider (NLC) which would begin with a center-of-mass energy of 0.5 TeV, and would be upgradable to 1.0 TeV and beyond. To achieve this high energy, for the past several years they have been working on the development of a high-gradient 11.4-GHz (X-band) linear accelerator for the main linac of the collider. In this paper, they present the status and initial results from the ``Next Linear Collider Test Accelerator`` (NLCTA). The goal of the NLCTA is to model the high gradient linac of the NLC. It incorporates the new technologies of X-band accelerator structures, rf pulse compression systems and high-power klystrons into a 0.5 to 1.0 GeV linac which is a test bed for beam dynamics issues related to high-gradient acceleration.

Ruth, R.D.

1996-06-01

78

Plasma wake field acceleration: A proposed experimental test  

SciTech Connect

The prospect of achieving very high accelerating fields has led to proposals for using electrostatic plasma waves to accelerate charged particles for high energy physics. It has been predicted theoretically that these plasma waves can be driven by the wake fields of short bunches, or trains of bunches, of charged particles, to accelerate a subsequent bunch; the longitudinal electric fields possible could be of the order of a few GV/m. This note presents an outline of a proposed experimental test of this principle.

Rosenzweig, J.B.; Cline, D.B.; Dexter, R.N.; Larson, D.J.; Leonard, A.W.; Mengelt, K.R.; Sprott, J.C.; Mills, F.E.; Cole, F.T.

1985-07-15

79

Accelerated Durability Testing of Electrochromic Windows.  

National Technical Information Service (NTIS)

Prototype electrochromic windows made by several different U.S. companies have been tested in our laboratory for their long-term durability. Samples were subjected to alternate coloring and bleaching voltage cycles while exposed to simulated on 1-sun irra...

A.W. Czanderna C.E. Tracy D.K. Benson J.G. Zhang S.K. Deb

1998-01-01

80

High power RF testing of dielectric loaded accelerating structures  

Microsoft Academic Search

A joint Argonne National Laboratory\\/Naval Research Laboratory program is under way to investigate X-band dielectric-loaded accelerating (DLA) structures, using high-power 11.424-GHz radiation from the NRL Magnicon Facility. DLA structures offer the potential of a simple, inexpensive alternative to copper disk-loaded structures for use in high-gradient RF linear accelerators. The purpose of the high-power tests is to find the RF breakdown

Wei Gai; J. G. Power; R. Konecny; C. Jing; W. Liu; Z. M. Yusof; S. H. Gold; A. K. Kinkead

2004-01-01

81

RF pulse compression in the NLC test accelerator at SLAC  

SciTech Connect

At the Stanford Linear Accelerator Center (SLAC), the authors are designing a Next Linear Collider (NLC) with linacs powered by X-band klystrons with rf pulse compression. The design of the linac rf system is based on X-band prototypes which have been tested at high power, and on a systems-integration test - the Next Linear Collider Test Accelerator (NLCTA) - which is currently under construction at SLAC. This paper discusses some of the systems implications of rf pulse compression, and the use of pulse compression in the NLCTA, both for peak power multiplication and for controlling, by rf phase modulation, intra-pulse variations in the linac beam energy.

Lavine, T.L.

1995-02-01

82

Earth Scanner Bearing Accelerated Life Test  

NASA Technical Reports Server (NTRS)

The Moderate Resolution Imaging Spectrometer (MODIS) optical instrument for NASA Goddard will measure biological and physical processes on the Earth's surface and in the lower atmosphere. A key component of the instrument is an extremely accurate scan mirror motor/encoder assembly. Of prime concern in the performance and reliability of the scan motor/encoder is bearing selection and lubrication. This paper describes life testing of the bearings and lubrication selected for the program.

Dietz, Brian J.; VanDyk, Steven G.; Predmore, Roamer E.

2000-01-01

83

Kinematics of Synthetic Flexible Leaflet Heart Valves during Accelerated Testing  

Microsoft Academic Search

Background and aims of the study: The study aim was to examine the effect of variation of test frequencies on the duration and kinematics of valve leaflets dur- ing opening, and at the fully open position. Methods: Trileaflet polyurethane heart valves were tested in a Rowan Ash fatigue accelerator at 5, 10 and 15 Hz. Images of the valves were

Stephen S. D'Souza; Maya Butterfield; John Fisher

84

Accelerated indoor durability testing of polymeric photovoltaic encapsulation materials  

Microsoft Academic Search

The aim of these investigations was to determine the influence of the relevant load parameters temperature and humidity on the degradation behavior of selected polymeric PV encapsulation materials. A test program concerning three accelerated artificial ageing tests was set up and a comprehensive study of the selected candidate materials and its degradation behavior was done. To assess the long term

Gernot Oreski

2010-01-01

85

Accelerated Durability Testing of Electrochromic Windows  

SciTech Connect

Prototype electrochromic windows made by several different U.S. companies have been tested in our laboratory for their long-term durability. Samples were subjected to alternate coloring and bleaching voltage cycles while exposed to simulated on 1-sun irradiance in a temperature-controlled environmental chamber with low relative humidity. The samples inside the chamber were tested under a matrix of different conditions. These conditions include: cycling at different temperatures (65 C, 85 C, and 107 C) under the irradiance, cycling versus no-cycling under the same irradiance and temperature, testing with different voltage waveforms and duty cycles with the same irradiance and temperature, cycling under various filtered irradiance intensities, and simple thermal exposure with no irradiance or cycling. The electro-optical characteristics of the samples were measured between 350 and 1,100 nm every 4,000 cycles for up to 20,000 cycles. Photographs of the samples were taken periodically wi th a digital camera to record cosmetic defects, the extent of residual coloration, and overall coloration and bleaching uniformity of the samples. Our results indicate that the most important cause of degradation is the combination of continuous cycling, elevated temperature, and irradiance. The relative importance of these variables, when considered synergistically or separately, depends on the particular device materials and design.

Tracy, C. E.; Zhang, J. G.; Benson, D. K.; Czanderna, A. W.; Deb, S. K.

1998-12-29

86

The Brookhaven National Laboratory (BNL) Accelerator Test Facility  

SciTech Connect

The design of the Brookhaven National Laboratory Accelerator Test Facility is presented including the design goals and computational results. The heart of the system is a radiofrequency electron gun utilizing a photo-excited metal cathode followed by a conventional electron linac. The Nd:YAG laser used to drive the cathode with 6 ps long pulses can be synchronized to a high peak power CO{sub 2} laser in order to study laser acceleration of electrons. Current operational status of the project will be presented along with early beam tests.

Batchelor, K.

1990-01-01

87

Accelerated life testing effects on CMOS microcircuit characteristics, phase 1  

NASA Technical Reports Server (NTRS)

An accelerated life test of sufficient duration to generate a minimum of 50% cumulative failures in lots of CMOS devices was conducted to provide a basis for determining the consistency of activation energy at 250 C. An investigation was made to determine whether any thresholds were exceeded during the high temperature testing, which could trigger failure mechanisms unique to that temperature. The usefulness of the 250 C temperature test as a predictor of long term reliability was evaluated.

Maximow, B.

1976-01-01

88

Application of the Argonne Advanced Acceleration Test Facility to development for conventional accelerators  

SciTech Connect

The Argonne Advanced Acceleration Test Facility is designed as a powerful tool to test ideas for very high gradient acceleration schemes based on direct beam excitation of plasmas, metal structures, dielectrics, etc. The characteristic size in these systems is )approximately) 1 cm, corresponding to frequencies )approximately) 10 GHz. The question addressed here is whether the special features of this facility have application as well to the development of components for the more conventional, lower frequency, accelerators now operating or under development. It is suggested that the usefulness of the facility for the development of conventional systems could be enhanced by a provision for longer time delay between driver and witness beam pulses. 9 refs., 2 figs.

MacLachlan, J.A.

1988-04-07

89

High current electron linacs (advanced test accelerator/experimental test accelerator)  

SciTech Connect

The high current induction accelerator development at the Lawrence Livermore National Laboratory is described. The ATA facility is designed for 10 kA peak currents, 50 nsec pulse lengths and 50 MeV energies. At this time, half of the design current has been accelerated through the entire machine to particle energies of about 45 MeV. Current problem areas and operational experience to date will be discussed. Several key technical areas required development for the ATA machine; this report will survey these developments. The control of transverse beam instabilities required an accelerating cavity design with very low Q. Electron sources capable of 10 kA operation at high rep rates were developed using a plasma sparkboard approach. The pulse power systems on ATA, using the same type of spark gap switches as ETA, have exhibited excellent operational reliability.

Briggs, R.J.

1984-04-30

90

Accelerated Testing Methodology in Constant Stress-Rate Testing for Advanced Structural Ceramics: A Preloading Technique.  

National Technical Information Service (NTIS)

Preloading technique was used as a means of an accelerated testing methodology in constant stress-rate (dynamic fatigue) testing for two different brittle materials. The theory developed previously for fatigue strength as a function of preload was further...

S. R. Choi J. P. Gyekenyesi D. Huebert A. Bartlett H. H. Choi

2001-01-01

91

Status and results from the next linear collider test accelerator  

SciTech Connect

The design for the Next Linear Collider (NLC) at SLAC is based on two 11.4 GHz linacs operating at an unloaded acceleration gradient of 50 MV/m increasing to 85 MV/m as the energy is increased from {1/2} TeV to 1 TeV in the center of mass. During the past several years there has been tremendous progress on the development of 11.4 GHz (X-band) RF systems. These developments include klystrons which operate at the required power and pulse length, pulse compression systems that achieve a factor of four power multiplication and structures that are specially designed to reduce long-range wakefields. Together with these developments, we have constructed a {1/2} GeV test accelerator, the NLC Test Accelerator (NLCTA). The NLCTA will serve as a test bed as the design of the NLC is refined. In addition to testing the RF system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration, in particular the study of multibunch beam loading compensation and transverse beam break-up. In this paper we present the status of the NLCTA and the results of initial commissioning.

Ruth, R.D.; Adolphsen, C.; Allison, S. [and others

1996-08-01

92

Cryogenic cooling tests of a neutral particle beam accelerator component  

Microsoft Academic Search

Due to the need to reduce the power requirements and thus the weight of large space-based neutral particle beam (NPB) space platforms, current systems studies propose that these NPB accelerators be maintained at cryogenic temperature levels. As such, the ground test articles that will be used to develop many of the technological advancements necessary prior to engineering development of an

Stephen J. Black

1988-01-01

93

Estimation of threshold stress in accelerated life-testing  

Microsoft Academic Search

The author presents a method that uses accelerated life-test data to estimate the mean life at the service stress and the threshold stress below which a failure is unlikely to occur. The relation between stress and mean-life at that stress is assumed to follow an inverse power law that includes a threshold stress. The failure times at a given stress

H. Hirose

1993-01-01

94

Step-Stress Accelerated Degradation Testing for Solar Reflectors: Preprint  

SciTech Connect

To meet the challenge to reduce the cost of electricity generated with concentrating solar power (CSP) new low-cost reflector materials are being developed including metalized polymer reflectors and must be tested and validated against appropriate failure mechanisms. We explore the application of testing methods and statistical inference techniques for quantifying estimates and improving lifetimes of concentrating solar power (CSP) reflectors associated with failure mechanisms initiated by exposure to the ultraviolet (UV) part of the solar spectrum. In general, a suite of durability and reliability tests are available for testing a variety of failure mechanisms where the results of a set are required to understand overall lifetime of a CSP reflector. We will focus on the use of the Ultra-Accelerated Weathering System (UAWS) as a testing device for assessing various degradation patterns attributable to accelerated UV exposure. Depending on number of samples, test conditions, degradation and failure patterns, test results may be used to derive insight into failure mechanisms, associated physical parameters, lifetimes and uncertainties. In the most complicated case warranting advanced planning and statistical inference, step-stress accelerated degradation (SSADT) methods may be applied.

Jones, W.; Elmore, R.; Lee, J.; Kennedy, C.

2011-09-01

95

Accelerated aging tests of liners for uranium mill tailings disposal  

SciTech Connect

This document describes the results of accelerated aging tests to determine the long-term effectiveness of selected impoundment liner materials in a uranium mill tailings environment. The study was sponsored by the US Department of Energy under the Uranium Mill Tailings Remedial Action Project. The study was designed to evaluate the need for, and the performance of, several candidate liners for isolating mill tailings leachate in conformance with proposed Environmental Protection Agency and Nuclear Regulatory Commission requirements. The liners were subjected to conditions known to accelerate the degradation mechanisms of the various liners. Also, a test environment was maintained that modeled the expected conditions at a mill tailings impoundment, including ground subsidence and the weight loading of tailings on the liners. A comparison of installation costs was also performed for the candidate liners. The laboratory testing and cost information prompted the selection of a catalytic airblown asphalt membrane and a sodium bentonite-amended soil for fiscal year 1981 field testing.

Barnes, S.M.; Buelt, J.L.; Hale, V.Q.

1981-11-01

96

Thermosonic gold-ball bond accelerated life test  

Microsoft Academic Search

Accelerated aging tests on gold-ball bonds in hermetic packages have been conducted at 350°C, 300°C, 250°C, and 200°C to determine time to failure, activation energy of failure, and the electrical\\/mechanical degradation at failure. Four different aluminium\\/1% silicon metallizations were tested: evaporated metal with P-glass (passivation-glass) contamination, evaporated metal with no P-glass contamination, sputtered metal with P-glass contamination, and sputtered metal

Tom D. Hund

1990-01-01

97

Cryogenic cooling system for the ground test accelerator  

SciTech Connect

A cryogenic cooling system has been designed, built and tested for the Ground Test Accelerator (GTA) at the Los Alamos National Laboratory. Major components of the GTA require cooling to less than 50 K to reduce rf-heating and to increase thermal stability. The cooling system is capable of cooling (at an acceptable rate for thermal stresses) the cryogenically cooled components and then maintaining them at their operating temperature during accelerator testing for all modes and power levels of operation. The accelerator components are cooled by circulating cold, dense helium gas (about 21 K and 2.1 MPa) through the components. The circulating helium is refrigerated in a heat exchanger that uses boiling liquid hydrogen as a source of refrigeration. The cryogenic cooling system consists of the following major components: a liquid hydrogen (LH[sub 2]) storage Dewar with a transfer line to an LH[sub 2] run tank containing an LH[sub 2]/gaseous helium (GHe) heat exchanger, circulation lines, and a circulation pump. The system, sized to cool a load of approximately 40 kW at temperatures as low as 20 K, is operational, but has not yet been operated in conjunction with the accelerator.

Edeskuty, F.J.; Stewart, W.F.; Moeller, J.; Durham, F. (Los Alamos National Lab., NM (United States)); Spulgis, I. (CVI, Inc., Columbus, OH (United States))

1993-01-01

98

Cryogenic cooling system for the ground test accelerator  

SciTech Connect

A cryogenic cooling system has been designed, built and tested for the Ground Test Accelerator (GTA) at the Los Alamos National Laboratory. Major components of the GTA require cooling to less than 50 K to reduce rf-heating and to increase thermal stability. The cooling system is capable of cooling (at an acceptable rate for thermal stresses) the cryogenically cooled components and then maintaining them at their operating temperature during accelerator testing for all modes and power levels of operation. The accelerator components are cooled by circulating cold, dense helium gas (about 21 K and 2.1 MPa) through the components. The circulating helium is refrigerated in a heat exchanger that uses boiling liquid hydrogen as a source of refrigeration. The cryogenic cooling system consists of the following major components: a liquid hydrogen (LH{sub 2}) storage Dewar with a transfer line to an LH{sub 2} run tank containing an LH{sub 2}/gaseous helium (GHe) heat exchanger, circulation lines, and a circulation pump. The system, sized to cool a load of approximately 40 kW at temperatures as low as 20 K, is operational, but has not yet been operated in conjunction with the accelerator.

Edeskuty, F.J.; Stewart, W.F.; Moeller, J.; Durham, F. [Los Alamos National Lab., NM (United States); Spulgis, I. [CVI, Inc., Columbus, OH (United States)

1993-06-01

99

Estimation for a Weibull accelerated life testing model  

SciTech Connect

It is sometimes reasonable to assume that the lifetime distribution of an item belongs to a certain parametric family, and that actual parameter values depend upon the testing environment of the item. In the two-parameter Weibull family setting, suppose both the shape and scale parameters are expressible as functions of the testing environment. For various models of functional dependency on environment, maximum likelihood methods are used to estimate characteristics of interest at specified environmental levels. The methodology presented handles exact, censored, and grouped data. A detailed accelerated life testing analysis of stress-rupture data for Kevlar/epoxy composites is given. 10 references, 1 figure, 2 tables.

Glaser, R.E.

1984-01-01

100

Reproduction of natural corrosion by accelerated laboratory testing methods  

SciTech Connect

Various laboratory corrosion tests have been developed to study the behavior of glass waste forms under conditions similar to those expected in an engineered repository. The data generated by laboratory experiments are useful for understanding corrosion mechanisms and for developing chemical models to predict the long-term behavior of glass. However, it is challenging to demonstrate that these test methods produce results that can be directly related to projecting the behavior of glass waste forms over time periods of thousands of years. One method to build confidence in the applicability of the test methods is to study the natural processes that have been taking place over very long periods in environments similar to those of the repository. In this paper, we discuss whether accelerated testing methods alter the fundamental mechanisms of glass corrosion by comparing the alteration patterns that occur in naturally altered glasses with those that occur in accelerated laboratory environments. This comparison is done by (1) describing the alteration of glasses reacted in nature over long periods of time and in accelerated laboratory environments and (2) establishing the reaction kinetics of naturally altered glass and laboratory reacted glass waste forms.

Luo, J.S.; Wronkiewicz, D.J.; Mazer, J.J.; Bates, J.K.

1996-05-01

101

Accelerated aging test results for aerospace wire insulation constructions  

NASA Technical Reports Server (NTRS)

Several wire insulation constructions were evaluated with and without continuous glow discharges at low pressure and high temperature to determine the aging characteristics of acceptable wire insulation constructions. It was known at the beginning of the test program that insulation aging takes several years when operated at normal ambient temperature and pressure of 20 C and 760 torr. Likewise, it was known that the accelerated aging process decreases insulation life by approximately 50% for each 10 C temperature rise. Therefore, the first phases of the program, not reported in these test results, were to select wire insulation constructions that could operate at high temperature and low pressure for over 10,000 hours with negligible shrinkage and little materials' deterioration.The final phase of the program was to determine accelerated aging characteristics. When an insulation construction is subjected to partial discharges the insulation is locally heated by the bombardment of the discharges, the insulation is also subjected to ozone and other deteriorating gas particles that may significantly increase the aging process. Several insulation systems using either a single material or combinations of teflon, kapton, and glass insulation constructions were tested. All constructions were rated to be partial discharge and/or corona-free at 240 volts, 400 Hz and 260 C (500 F) for 50, 000 hours at altitudes equivalent to the Paschen law. Minimum partial discharge aging tests were preceded by screening tests lasting 20 hours at 260 C. The aging process was accelerated by subjecting the test articles to temperatures up to 370 C (700 F) with and without partial discharges. After one month operation with continuous glow discharges surrounding the test articles, most insulation systems were either destroyed or became brittle, cracked, and unsafe for use. Time with space radiation as with partial discharges is accumulative.

Dunbar, William G.

1995-01-01

102

Accelerated Creep Testing of High Strength Aramid Webbing  

NASA Technical Reports Server (NTRS)

A series of preliminary accelerated creep tests were performed on four variants of 12K and 24K lbf rated Vectran webbing to help develop an accelerated creep test methodology and analysis capability for high strength aramid webbings. The variants included pristine, aged, folded and stitched samples. This class of webbings is used in the restraint layer of habitable, inflatable space structures, for which the lifetime properties are currently not well characterized. The Stepped Isothermal Method was used to accelerate the creep life of the webbings and a novel stereo photogrammetry system was used to measure the full-field strains. A custom MATLAB code is described, and used to reduce the strain data to produce master creep curves for the test samples. Initial results show good correlation between replicates; however, it is clear that a larger number of samples are needed to build confidence in the consistency of the results. It is noted that local fiber breaks affect the creep response in a similar manner to increasing the load, thus raising the creep rate and reducing the time to creep failure. The stitched webbings produced the highest variance between replicates, due to the combination of higher local stresses and thread-on-fiber damage. Large variability in the strength of the webbings is also shown to have an impact on the range of predicted creep life.

Jones, Thomas C.; Doggett, William R.; Stnfield, Clarence E.; Valverde, Omar

2012-01-01

103

Testing in a combined vibration and acceleration environment.  

SciTech Connect

Sandia National Laboratories has previously tested a capability to impose a 7.5 g-rms (30 g peak) radial vibration load up to 2 kHz on a 25 lb object with superimposed 50 g acceleration at its centrifuge facility. This was accomplished by attaching a 3,000 lb Unholtz-Dickie mechanical shaker at the end of the centrifuge arm to create a 'Vibrafuge'. However, the combination of non-radial vibration directions, and linear accelerations higher than 50g's are currently not possible because of the load capabilities of the shaker and the stresses on the internal shaker components due to the combined centrifuge acceleration. Therefore, a new technique using amplified piezo-electric actuators has been developed to surpass the limitations of the mechanical shaker system. They are lightweight, modular and would overcome several limitations presented by the current shaker. They are 'scalable', that is, adding more piezo-electric units in parallel or in series can support larger-weight test articles or displacement/frequency regimes. In addition, the units could be mounted on the centrifuge arm in various configurations to provide a variety of input directions. The design along with test results will be presented to demonstrate the capabilities and limitations of the new piezo-electric Vibrafuge.

Jepsen, Richard Alan; Romero, Edward F.

2004-10-01

104

An Asset Test of the CLIC Accelerating Structure  

SciTech Connect

Transverse wakefield suppression in the CLIC (Compact Linear Collider) multibunch accelerating structure, called the TDS (Tapered Damped Structure), is achieved primarily through heavy damping. In order to verify the performance of the TDS design and the validity of the theoretical tools used to model it, a 15 GHz version of the TDS has been constructed and tested in the ASSET facility at SLAC. The test has directly demonstrated transverse wakefield suppression of over a factor 100, with an excellent agreement between the measured and the calculated wakefield.

Adolphsen, Chris

2001-07-31

105

Database requirements for the Advanced Test Accelerator project  

SciTech Connect

The database requirements for the Advanced Test Accelerator (ATA) project are outlined. ATA is a state-of-the-art electron accelerator capable of producing energetic (50 million electron volt), high current (10,000 ampere), short pulse (70 billionths of a second) beams of electrons for a wide variety of applications. Databasing is required for two applications. First, the description of the configuration of facility itself requires an extended database. Second, experimental data gathered from the facility must be organized and managed to insure its full utilization. The two applications are intimately related since the acquisition and analysis of experimental data requires knowledge of the system configuration. This report reviews the needs of the ATA program and current implementation, intentions, and desires. These database applications have several unique aspects which are of interest and will be highlighted. The features desired in an ultimate database system are outlined. 3 references, 5 figures.

Chambers, F.W.

1984-11-05

106

Ultra-Accelerated Natural Sunlight Exposure Testing Facilities  

DOEpatents

A multi-faceted concentrator apparatus for providing ultra-accelerated natural sunlight exposure testing for sample materials under controlled weathering conditions comprising: facets that receive incident natural sunlight, transmits VIS/NIR and reflects UV/VIS onto a secondary reflector that delivers a uniform flux of UV/VIS onto a sample exposure plane located near a center of a facet array in a chamber that provide concurrent levels of temperature and/or relative humidity at high levels of up to 100.times. of natural sunlight that allow sample materials to be subjected to accelerated irradiance exposure factors for a significant period of time of about 3 to 10 days to provide a corresponding time of about at least a years worth representative weathering of sample materials.

Lewandowski, Allan A. (Evergreen, CO); Jorgensen, Gary J. (Pine, CO)

2004-11-23

107

Commissioning of the Ground Test Accelerator Intertank Matching Section  

SciTech Connect

The Ground Test Accelerator (GTA) has the objective of verifying much of the technology (physics and engineering) required for producing high-brightness, high-current H{sup {minus}} beams. GTA commissioning is staged to verify the beam dynamics design of each major accelerator component as it is brought on-line. The commissioning stages are the 35 keV H{sup {minus}} injector, the 2.5 MeV Radio Frequency Quadrupole (RFQ), the Intertank Matching Section (IMS), the 3.2 MeV first 2{beta}{gamma} Drift Tube Linac (DTL-1) module, the 8.7 MeV 2{beta}{gamma} DTL (modules 1--5), and the 24 MeV GTA; all 10 DTL modules. Commissioning results from the IMS beam experiments will be presented.

Johnson, K.F.; Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Cole, R.; Connolly, R.; Gilpatrick, J.D.; Ingalls, W.B.; Kersteins, D.; Little, C.; Lohsen, R.A.; Lysenko, W.P.; Mottershead, C.T.; Power, J.; Rusthoi, D.P.; Sandoval, D.P.; Stevens, R.R.; Vaughn, G.; Wadlinger, E.A.; Weiss, R.; Yuan, V.

1992-09-01

108

Commissioning of the Ground Test Accelerator Intertank Matching Section  

SciTech Connect

The Ground Test Accelerator (GTA) has the objective of verifying much of the technology (physics and engineering) required for producing high-brightness, high-current H{sup {minus}} beams. GTA commissioning is staged to verify the beam dynamics design of each major accelerator component as it is brought on-line. The commissioning stages are the 35 keV H{sup {minus}} injector, the 2.5 MeV Radio Frequency Quadrupole (RFQ), the Intertank Matching Section (IMS), the 3.2 MeV first 2{beta}{gamma} Drift Tube Linac (DTL-1) module, the 8.7 MeV 2{beta}{gamma} DTL (modules 1--5), and the 24 MeV GTA; all 10 DTL modules. Commissioning results from the IMS beam experiments will be presented.

Johnson, K.F.; Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Cole, R.; Connolly, R.; Gilpatrick, J.D.; Ingalls, W.B.; Kersteins, D.; Little, C.; Lohsen, R.A.; Lysenko, W.P.; Mottershead, C.T.; Power, J.; Rusthoi, D.P.; Sandoval, D.P.; Stevens, R.R.; Vaughn, G.; Wadlinger, E.A.; Weiss, R.; Yuan, V.

1992-01-01

109

Accelerated stress testing of amorphous silicon solar cells  

NASA Technical Reports Server (NTRS)

A technique for performing accelerated stress tests of large-area thin a-Si solar cells is presented. A computer-controlled short-interval test system employing low-cost ac-powered ELH illumination and a simulated a-Si reference cell (seven individually bandpass-filtered zero-biased crystalline PIN photodiodes) calibrated to the response of an a-Si control cell is described and illustrated with flow diagrams, drawings, and graphs. Preliminary results indicate that while most tests of a program developed for c-Si cells are applicable to a-Si cells, spurious degradation may appear in a-Si cells tested at temperatures above 130 C.

Stoddard, W. G.; Davis, C. W.; Lathrop, J. W.

1985-01-01

110

Plasma Wakefield Acceleration and FACET - Facilities for Accelerator Science and Experimental Test Beams at SLAC  

ScienceCinema

Plasma wakefield acceleration is one of the most promising approaches to advancing accelerator technology. This approach offers a potential 1,000-fold or more increase in acceleration over a given distance, compared to existing accelerators.  FACET, enabled by the Recovery Act funds, will study plasma acceleration, using short, intense pulses of electrons and positrons. In this lecture, the physics of plasma acceleration and features of FACET will be presented.  

Andrei Seryi

2010-01-08

111

Improved Accelerated Stress Tests Based on Fuel Cell Vehicle Data  

SciTech Connect

UTC will led a top-tier team of industry and national laboratory participants to update and improve DOE’s Accelerated Stress Tests (AST’s) for hydrogen fuel cells. This in-depth investigation will focused on critical fuel cell components (e.g. membrane electrode assemblies - MEA) whose durability represented barriers for widespread commercialization of hydrogen fuel cell technology. UTC had access to MEA materials that had accrued significant load time under real-world conditions in PureMotion® 120 power plant used in transit buses. These materials are referred to as end-of-life (EOL) components in the rest of this document. Advanced characterization techniques were used to evaluate degradation mode progress using these critical cell components extracted from both bus power plants and corresponding materials tested using the DOE AST’s. These techniques were applied to samples at beginning-of-life (BOL) to serve as a baseline. These comparisons advised the progress of the various failure modes that these critical components were subjected to, such as membrane degradation, catalyst support corrosion, platinum group metal dissolution, and others. Gaps in the existing ASTs predicted the degradation observed in the field in terms of these modes were outlined. Using the gaps, new AST’s were recommended and tested to better reflect the degradation modes seen in field operation. Also, BOL components were degraded in a test vehicle at UTC designed to accelerate the bus field operation.

Patterson, Timothy [Research Engineer] [Research Engineer; Motupally, Sathya [Research Engineer] [Research Engineer

2012-06-01

112

Thermal Vacuum Accelerated Life Test of No. 1 Hawker Siddeley Dynamics Low Speed Mechanism.  

National Technical Information Service (NTIS)

A solar array drive mechanism, was subjected to an accelerated life test under vacuum. The accelerated life test involved operating the mechanism at increased speed sufficient to accrue the equivalent of 10 years normal speed running (1 revolution of the ...

J. Gillies

1974-01-01

113

Results of accelerated thermal cycle tests of solar cells modules  

NASA Technical Reports Server (NTRS)

Various candidate solar panel designs were evaluated, both theoretically and experimentally, with respect to their thermal cycling survival capability, and in particular with respect to an accelerated simulation of thermal cycles representative of Viking '75 mission requirements. The experimental results were obtained on 'mini-panels' thermally cycled in a newly installed automated test facility herein described. The resulting damage was analyzed physically and theoretically, and on the basis of these analyses the panel design was suitably modified to significantly improve its ability to withstand the thermal environment. These successful modifications demonstrate the value of the complementary theoretical-experimental approach adopted, and discussed in detail in this paper.

Berman, P.; Mueller, R.; Salama, M.; Yasui, R.

1976-01-01

114

Testing of accelerator dipoles in pressurized superfluid helium  

SciTech Connect

Two superconducting accelerator dipole magnets, with different internal construction features, have been tested in pressurized superfluid helium (1.8K, 1.2 atmosphere) as well as in regular pool boiling helium (4.4K, 1.2 atmosphere) helium. The coils of one magnet were moderately pre-stressed, and 4.2K design performance was rapidly achieved in the superfluid. The other magnet had very low coil pre-stress, reduced helium ventilation, and displayed degraded performance, even in the superfluid helium.

Gilbert, W.S.; Caspi, S.; Hassenzahl, W.; Lambertson, G.; Meuser, R.; Rechen, J.; Schafer, R.; Warren, R.

1980-01-01

115

Mir Cooperative Solar Array Project Accelerated Life Thermal Cycling Test  

NASA Technical Reports Server (NTRS)

The Mir Cooperative Solar Array (MCSA) project was a joint U.S./Russian effort to build a photovoltaic (PV) solar array and deliver it to the Russian space station Mir. The MCSA will be used to increase the electrical power on Mir and provide PV array performance data in support of Phase 1 of the International Space Station. The MCSA was brought to Mir by space shuttle Atlantis in November 1995. This report describes an accelerated thermal life cycle test which was performed on two samples of the MCSA. In eight months time, two MCSA solar array 'mini' panel test articles were simultaneously put through 24,000 thermal cycles. There was no significant degradation in the structural integrity of the test articles and no electrical degradation, not including one cell damaged early and removed from consideration. The nature of the performance degradation caused by this one cell is briefly discussed. As a result of this test, changes were made to improve some aspects of the solar cell coupon-to-support frame interface on the flight unit. It was concluded from the results that the integration of the U.S. solar cell modules with the Russian support structure would be able to withstand at least 24,000 thermal cycles (4 years on-orbit). This was considered a successful development test.

Hoffman, David J.; Scheiman, David A.

1996-01-01

116

78 FR 76410 - Request for Information on Strategies To Accelerate the Testing and Adoption of Pay for Success...  

Federal Register 2010, 2011, 2012, 2013

...Strategies To Accelerate the Testing and Adoption of Pay for Success (PFS) Financing...Strategies to Accelerate the Testing and Adoption of Pay for Success (PFS) Financing...Strategies to Accelerate the Testing and Adoption of Pay for Success (PFS)...

2013-12-17

117

High-energy lattice for first-beam operation of the SRF test accelerator at NML  

SciTech Connect

The Superconducting Radio Frequency Test Accelerator, a linear electron accelerator currently in construction at Fermilab's New Muon Laboratory, will eventually reach energies of {approx} 900 MeV using four ILC-type superconducting accelerating cryomodules. The accelerator's construction is staged according to cryomodules availability. The first phase that will support first beam operation incorporates one cryomodule. In this Note, we summarize a possible design for the first-beam accelerator configuration.

Prokop, C.; /NICADD, DeKalb; Piot, P.; /NICADD, DeKalb /Fermilab; Church, M.; /Fermilab

2011-09-01

118

Lessons learned on the Ground Test Accelerator control system  

SciTech Connect

When we initiated the control system design for the Ground Test Accelerator (GTA), we envisioned a system that would be flexible enough to handle the changing requirements of an experimental project. This control system would use a developers` toolkit to reduce the cost and time to develop applications for GTA, and through the use of open standards, the system would accommodate unforeseen requirements as they arose. Furthermore, we would attempt to demonstrate on GTA a level of automation far beyond that achieved by existing accelerator control systems. How well did we achieve these goals? What were the stumbling blocks to deploying the control system, and what assumptions did we make about requirements that turned out to be incorrect? In this paper we look at the process of developing a control system that evolved into what is now the ``Experimental Physics and Industrial Control System`` (EPICS). Also, we assess the impact of this system on the GTA project, as well as the impact of GTA on EPICS. The lessons learned on GTA will be valuable for future projects.

Kozubal, A.J.; Weiss, R.E.

1994-09-01

119

Accelerated Test Techniques for Micro-Circuits: Evaluation of High Temperature (473 K - 573 K) Accelerated Life Test Techniques as Effective Microcircuit Screening Methods.  

National Technical Information Service (NTIS)

The application of high temperature accelerated test techniques was shown to be an effective method of microcircuit defect screening. Comprehensive microcircuit evaluations and a series of high temperature (473 K to 573 K) life tests demonstrated that a f...

G. M. Johnson

1976-01-01

120

Beam based alignment at the KEK accelerator test facility  

SciTech Connect

The KEK Accelerator Test Facility (ATF) damping ring is a prototype low emittance source for the NLC/JLC linear collider. To achieve the goal normalized vertical emittance {gamma}{var_epsilon}{sub {gamma}} = 20 nm-rad, magnet placement accuracy better than 30 mm must be achieved. Accurate beam-based alignment (BBA) is required. The ATF arc optics uses a FOBO cell with two horizontally focusing quadrupoles, two sextupoles and a horizontally defocusing gradient dipole, all of which must be aligned with BBA. BBA at ATF uses the quadrupole and sextupole trim windings to find the trajectory through the center of each magnet. The results can be interpreted to assess the accuracy of the mechanical alignment and the beam position monitor offsets.

Ross, M.; Nelson, J.; Woodley, M.; Wolski, A.

2002-06-14

121

Accelerators  

NSDL National Science Digital Library

What is the purpose of particle accelerators? On this web page, part of a particle physics tutorial, students read that accelerators solve two problems. The accelerators provide an increase in momentum to produce particles of small wavelength, and the fast-moving particles can create new particles when smashed together. A photograph of the inside of a particle accelerator is provided. Copyright 2005 Eisenhower National Clearinghouse

Group, Lawrence B.

2002-01-01

122

A critical review of ultra-accelerated tests for alkali-silica reactivity  

Microsoft Academic Search

A large number of ultra-accelerated test procedures, for determining the potential alkali reactivity of aggregates, have been developed, particularly in the past 15 years. An ultra-accelerated test method is defined as one which yields results within a few days or, at most, a few weeks. A number of ultra-accelerated test methods have been adopted as ‘standard tests’, but few have

P. E. Grattan-Bellew

1997-01-01

123

Beam Test of Multi-Bunch Energy Compensation System in the Accelerator Test Facility at KEK  

NASA Astrophysics Data System (ADS)

A beam test of the multi-bunch energy compensation system (ECS) was performed using the ? F method with the 2856± 4.327 MHz accelerating structures in the accelerator test facility (ATF) at KEK. The 1.54 GeV S-band linac of the ATF was designed to accelerate a multi-bunch beam that consists of 20 bunches with 2.8 ns spacing. The multi-bunch beam with 2.0× 1010 electrons/bunch has an energy deviation of about 8.5% at the end of the linac due to transient beam loading without ECS. The ATF linac is the injector of the ATF damping ring (DR), whose energy acceptance is ± 0.5%. The beam loading compensation system is necessary in the ATF linac for the successful injection of multi-bunch into DR. The rf system of the linac consists of 8 regular rf units with the SLED system and 2 ECS rf units without the SLED system. The accelerating structures of the regular units are driven at 2856 MHz and the 2 ECS structures are operated with slightly different rf frequencies of 2856± 4.327 MHz. In the beam test, we have succeeded in compressing the multi-bunch energy spread within the energy acceptance of the DR using ? F ECS. The principle of the beam loading compensation system of KEK-ATF and the experimental results are described in this paper.

Kashiwagi, Shigeru; Hayano, Hitoshi; Kubo, Kiyoshi; Korhonen, Timo; Nakamura, Shogo; Naito, Takashi; Oide, Katsunobu; Takeda, Seishi; Terunuma, Nobuhiro; Urakawa, Junji

2004-08-01

124

Degradation mechanisms and accelerated testing in PEM fuel cells  

SciTech Connect

The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. Although there has been recent progress in improving durability, further improvements are needed to meet the commercialization targets. Past improvements have largely been made possible because of the fundamental understanding of the underlying degradation mechanisms. By investigating component and cell degradation modes; defining the fundamental degradation mechanisms of components and component interactions new materials can be designed to improve durability. Various factors have been shown to affect the useful life of PEM fuel cells. Other issues arise from component optimization. Operational conditions (such as impurities in either the fuel and oxidant stream), cell environment, temperature (including subfreezing exposure), pressure, current, voltage, etc.; or transient versus continuous operation, including start-up and shutdown procedures, represent other factors that can affect cell performance and durability. The need for Accelerated Stress Tests (ASTs) can be quickly understood given the target lives for fuel cell systems: 5000 hours ({approx} 7 months) for automotive, and 40,000 hrs ({approx} 4.6 years) for stationary systems. Thus testing methods that enable more rapid screening of individual components to determine their durability characteristics, such as off-line environmental testing, are needed for evaluating new component durability in a reasonable turn-around time. This allows proposed improvements in a component to be evaluated rapidly and independently, subsequently allowing rapid advancement in PEM fuel cell durability. These tests are also crucial to developers in order to make sure that they do not sacrifice durability while making improvements in costs (e.g. lower platinum group metal [PGM] loading) and performance (e.g. thinner membrane or a GDL with better water management properties). To achieve a deeper understanding and improve PEM fuel cell durability LANL is conducting research to better define fuel cell component degradation mechanisms and correlate AST measurements to component in 'real-world' situations.

Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

2010-01-01

125

Accelerated indoor durability testing of polymeric photovoltaic encapsulation materials  

NASA Astrophysics Data System (ADS)

The aim of these investigations was to determine the influence of the relevant load parameters temperature and humidity on the degradation behavior of selected polymeric PV encapsulation materials. A test program concerning three accelerated artificial ageing tests was set up and a comprehensive study of the selected candidate materials and its degradation behavior was done. To assess the long term performance and durability of materials, it was necessary not only to measure the deterioration of macroscopic physical properties, but also to gain information about degradation processes taking place at a molecular level. Therefore, the material properties and the aging behaviour were characterized by infrared spectroscopy, by UV/VIS spectroscopy, by differential scanning calorimetry, by dynamical mechanical analysis and by tensile tests. By IR spectroscopy no significant thermal oxidation was detected for all investigated materials. But UV/VIS spectroscopy showed a significant drop in solar transmittance and reflectance values. Yellowing was observed due to the formation of chromophoric degradation products. For all materials a significant decrease in ultimate mechanical properties due to chemical aging was measured. For both backsheet materials the changes in ultimate mechanical properties can be attributed nearly exclusiveley to the polyester layer. On the other hand, a stiffening of all materials due to physical aging was observed within the first 1000h of damp heat testing. For the backsheet laminates, delamination at the edges was observed. Generally, higher temperature levels during exposure induced faster rate of chemical and physical aging. High humidity levels showed to be less influential on polymer degradation than temperature.

Oreski, Gernot

2010-08-01

126

Accelerated atmospheric corrosion testing of electroplated gold mirror coatings  

NASA Astrophysics Data System (ADS)

Gold-coated mirrors are widely used in infrared optics for industrial, space, and military applications. These mirrors are often made of aluminum or beryllium substrates with polished nickel plating. Gold is deposited on the nickel layer by either electroplating or vacuum deposition processes. Atmospheric corrosion of gold-coated electrical connectors and contacts was a well-known problem in the electronic industry and studied extensively. However, there is limited literature data that correlates atmospheric corrosion to the optical properties of gold mirror coatings. In this paper, the atmospheric corrosion of different electroplated gold mirror coatings were investigated with an accelerated mixed flowing gas (MFG) test for up to 50 days. The MFG test utilizes a combination of low-level air pollutants, humidity, and temperatures to achieve a simulated indoor environment. Depending on the gold coating thickness, pore corrosion started to appear on samples after about 10 days of the MFG exposure. The corrosion behavior of the gold mirror coatings demonstrated the porous nature of the electroplated gold coatings as well as the variation of porosity to the coating thickness. The changes of optical properties of the gold mirrors were correlated to the morphology of corrosion features on the mirror surface.

Chu, C.-T.; Alaan, D. R.; Taylor, D. P.

2010-08-01

127

Voltage stress effects on microcircuit accelerated life test failure rates  

NASA Technical Reports Server (NTRS)

The applicability of Arrhenius and Eyring reaction rate models for describing microcircuit aging characteristics as a function of junction temperature and applied voltage was evaluated. The results of a matrix of accelerated life tests with a single metal oxide semiconductor microcircuit operated at six different combinations of temperature and voltage were used to evaluate the models. A total of 450 devices from two different lots were tested at ambient temperatures between 200 C and 250 C and applied voltages between 5 Vdc and 15 Vdc. A statistical analysis of the surface related failure data resulted in bimodal failure distributions comprising two lognormal distributions; a 'freak' distribution observed early in time, and a 'main' distribution observed later in time. The Arrhenius model was shown to provide a good description of device aging as a function of temperature at a fixed voltage. The Eyring model also appeared to provide a reasonable description of main distribution device aging as a function of temperature and voltage. Circuit diagrams are shown.

Johnson, G. M.

1976-01-01

128

Thermal fatigue test for turbine housing by a pulse YAG laser  

Microsoft Academic Search

A steam turbine housing (casing) for power plant is subject to thermal fatigue in the long service. Evaluation of the life time is required for the replacement of turbine housing. In the present work, the possibility of thermal fatigue test by laser to accelerate the thermal damage of the materials (heat resisting Cr-Mo steel) and estimate the life time of

Muneharu Kutsuna; Shinji Fujita; Yuji Sugita; Katsushige Yamada

2000-01-01

129

Inverse Cherenkov and inverse FEL accelerator experiments at the Brookhaven Accelerator Test Facility  

SciTech Connect

Status update on the ongoing inverse Cherenkov acceleration experiment and prospects to its 100 MeV short-term upgrade. The first report on 1 MeV electron acceleration with the 0.5 GW CO{sub 2} laser used in the inverse FEL scheme. (author). 22 refs., 8 figs., 1 tab.

Pogorelsky, I.V.; vanSteenbergen, A.; Babzien, M.

1995-12-31

130

Acceleration tests to determine salient pole synchronous motor inrush currents and torques  

Microsoft Academic Search

Determining torque and current at locked rotor and various slips during the acceleration test on a synchronous machine is very tedious and time consuming. Induction and synchronous machines behave similarly during acceleration except that synchronous machine acceleration can include a pulsation torque. Because of the salient poles, conditions exist where the synchronous motor has minimum torque at quadrature axis and

J. H. Dymond; B. Mistry; R. Ong

2002-01-01

131

Step-Stress Accelerated Degradation Testing (SSADT) for Photovoltaic (PV) Devices and Cells (Presentation)  

SciTech Connect

Presentation on step-stress accelerated degradation testing (SSADT) for photovoltaics (PV). Developed are a step-stress degradation test (SSADT) for PV reliability tests and a lifetime prediction model for PV products.

Lee, J.; Elmore, R.; Suh, C.; Jones, W.

2010-10-01

132

Effect of time and temperature on accelerated chemical durability tests made on commercial glass bottles  

Microsoft Academic Search

Chemical durability results obtained by tests on crushed samples and bottle surfaces on a variety of commercial glass-bottle compositions show the difficulties encountered in attempting to correlate accelerated tests with the actural performance of the bottles toward various solutions under service conditions. The results obtained thus far indicate that the value of accelerated tests conducted with distilled water as a

Frank R. Bacon; O. G. Burch

1940-01-01

133

Testing of a Loop Heat Pipe Subjected to Variable Accelerating Forces  

NASA Technical Reports Server (NTRS)

This paper presents viewgraphs of the functionality of a loop heat pipe that was subjected to variable accelerating forces. The topics include: 1) Summary of LHP (Loop Heat Pipe) Design Parameters; 2) Picture of the LHP; 3) Schematic of Test Setup; 4) Test Configurations; 5) Test Profiles; 6) Overview of Test Results; 7) Start-up; 8) Typical Start-up without Temperature Overshoot; 9) Start-up with a Large Temperature Overshoot; 10) LHP Operation Under Stationary Condition; 11) LHP Operation Under Continuous Acceleration; 12) LHP Operation Under Periodic Acceleration; 13) Effects of Acceleration on Temperature Oscillation and Hysteresis; 14) Temperature Oscillation/Hysteresis vs Spin Rate; and 15) Summary.

Ku, Jentung; Ottenstein, Laura; Kaya, Tarik; Rogers, Paul; Hoff, Craig

2000-01-01

134

Fast Extraction Kicker for the Accelerator Test Facility  

SciTech Connect

We present the results of a study for the design of a fastextraction kicker to be installed in the Accelerator Test Facility ringat KEK. This activity is carried on in the framework of the ATF2 project,which will be built on the KEK Tsukuba campus as an extension of theexisting ATF, taking advantage of the world s smallest normalizedemittance achieved there. ATF2's primary goal is to operate as a testfacility and establish the hardware and beam handling technologiesenvisaged for the International Linear Collider. In particular, the fastextraction kicker object of the present paper is an important componentof the ILC damping rings, since its rise and fall time define the minimumdistance between bunches and ultimately the damping rings length itself.Building on the initial results presented at EPAC '06, we report on thepresent status of the kicker design and define the minimumcharacteristics for pulsers and other subsystems. In addition to theoriginal scheme with multiple stripline modules producing a totaldeflection of 5 mrad, we also investigated a scheme with a single kickermodule for a reduced deflection of 1 mrad placed inside a closed orbitbump, which takes the electron closer to the extractionseptum.

De Santis, Stefano; Urakawa, Junji; Naito, Takashi

2007-06-20

135

Low-energy proton accelerator for detector testing  

NASA Astrophysics Data System (ADS)

Future fundamental physics experiments in neutron beta-decay require highly efficient detection of protons. Many of the experiments use electrostatic acceleration of the recoil protons into large-area silicon detectors for this purpose. A 30~keV proton accelerator was designed, created, and commissioned in order to characterize silicon detectors of this type. Final construction and initial results on the performance of the accelerator are presented. A unique aspect of the work is the use of a Penning ion generator as an ion source. The accelerator produced protons with momentum resolution ~1%. The ion source produced current stably, over a range of parameters, and over long periods of time. The accelerator achieved proton rates sufficient to calibrate silicon detectors.

Harrison, David

136

LeRC rail accelerators - Test designs and diagnostic techniques  

NASA Technical Reports Server (NTRS)

The feasibility of using rail accelerators for various in-space and to-space propulsion applications was investigated. A 1 meter, 24 sq mm bore accelerator was designed with the goal of demonstrating projectile velocities of 15 km/sec using a peak current of 200 kA. A second rail accelerator, 1 meter long with a 156.25 sq mm bore, was designed with clear polycarbonate sidewalls to permit visual observation of the plasma arc. A study of available diagnostic techniques and their application to the rail accelerator is presented. Specific topics of discussion include the use of interferometry and spectroscopy to examine the plasma armature as well as the use of optical sensors to measure rail displacement during acceleration. Standard diagnostics such as current and voltage measurements are also discussed. Previously announced in STAR as N83-35053

Zana, L. M.; Kerslake, W. R.; Sturman, J. C.; Wang, S. Y.; Terdan, F. F.

1984-01-01

137

Framework for a Comparative Accelerated Testing Standard for PV Modules: Preprint  

SciTech Connect

As the photovoltaic industry has grown, the interest in comparative accelerated testing has also grown. Private test labs offer testing services that apply greater stress than the standard qualification tests as tools for differentiating products and for gaining increased confidence in long-term PV investments. While the value of a single international standard for comparative accelerated testing is widely acknowledged, the development of a consensus is difficult. This paper strives to identify a technical basis for a comparative standard.

Kurtz, S.; Wohlgemuth, J.; Yamamichi, M.; Sample, T.; Miller, D.; Meakin, D.; Monokroussos, C.; TamizhMani, M.; Kempe, M.; Jordan, D.; Bosco, N.; Hacke, P.; Bermudez, V.; Kondo, M.

2013-08-01

138

Optical system for measurement of pyrotechnic test accelerations  

NASA Astrophysics Data System (ADS)

This effort was directed at comparing the response of several different accelerometer and amplifier combinations to the pyrotechnic pulse simulating the ordnance separation of stages of multistage missiles. These pyrotechnic events can contain peak accelerations in excess of 100,000 G and a frequency content exceeding 100,000 Hz. The main thrust of this work was to compare the several accelerometer systems with each other and with a very accurate laser Doppler displacement meter in order to establish the frequency bands and acceleration amplitudes where the accelerometer systems are in error. The comparisons were made in simple sine-wave and low-acceleration amplitude environments, as well as in very severe pyroshock environments. An optical laser Doppler displacement meter (LDDM) was used to obtain the displacement velocity and acceleration histories, as well as the corresponding shock spectrum.

Lieberman, Paul; Czajkowski, John; Rehard, John

1992-12-01

139

Hypersonic aerodynamics test facility using the external propulsion accelerator  

NASA Technical Reports Server (NTRS)

The use of the External propulsion Accelerator (EPA) for launching models of hypersonic aerodynamic configurations into an instrumented ballistic range is discussed. The aerodynamic model is encased inside an axisymmetric projectile designed to be accelerated to high speed in the EPA. Accelerator lengths required to achieve hypersonic speeds are estimated to vary from 10 meters for Mach 7, 40 meters for Mach 10, 150 meters for Mach 15, and 700 meters for Mach 30, assuming a limit of 50,000 g's acceleration. For a model span of 10 cm to 25 cm, the launch tube diameters are 40 cm and 100 cm, respectively. Using this EPA launcher will enable exact simulation of hypersonic flight in ground facilities where both the gas composition and pressure can be controlled in the ballistic range.

Rom, J.; Lewis, M.; Gupta, A.; Sabean, J.

1995-01-01

140

Accelerated Testing Methodology in Constant Stress-Rate Testing for Advanced Structural Ceramics: A Preloading Technique  

NASA Technical Reports Server (NTRS)

Preloading technique was used as a means of an accelerated testing methodology in constant stress-rate (dynamic fatigue) testing for two different brittle materials. The theory developed previously for fatigue strength as a function of preload was further verified through extensive constant stress-rate testing for glass-ceramic and CRT glass in room temperature distilled water. The preloading technique was also used in this study to identify the prevailing failure mechanisms at elevated temperatures, particularly at lower test rates in which a series of mechanisms would be associated simultaneously with material failure, resulting in significant strength increase or decrease. Two different advanced ceramics including SiC whisker-reinforced composite silicon nitride and 96 wt% alumina were used at elevated temperatures. It was found that the preloading technique can be used as an additional tool to pinpoint the dominant failure mechanism that is associated with such a phenomenon of considerable strength increase or decrease.

Choi, Sung R.; Gyekenyesi, John P.; Huebert, Dean; Bartlett, Allen; Choi, Han-Ho

2001-01-01

141

Development of a 20 MeV Dielectric-Loaded Accelerator Test Facility  

SciTech Connect

This paper describes a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the StanFord Linear Accelerator Center (SLAC), to develop a dielectric-loaded accelerator (DLA) test facility powered by a high-power 11.424-GHz magnicon amplifier. The magnicon can presently produce 25 MW of output power in a 250-ns pulse at 10 Hz, and efforts are in progress to increase this to 50 MW. The facility will include a 5 MeV electron injector being developed by the Accelerator Laboratory of Tsinghua University in Beijing, China. The DLA test structures are being developed by ANL, and some have undergone testing at NRL at gradients up to {approx}8 MV/m. SLAC is developing a means to combine the two magnicon output arms, and to drive an injector and accelerator with separate control of the power ratio and relative phase. RWBruce Associates, Inc., working with NRL, is developing a means to join short ceramic sections into a continuous accelerator tube by ceramic brazing using an intense millimeter-wave beam. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA structure, and spectrometer, should take place within the next year. The facility will be used for testing DLA structures using a variety of materials and configurations, and also for testing other X-band accelerator concepts. The initial goal is to produce a compact 20 MeV dielectric-loaded test accelerator.

Gold, Steven H.; Fliflet, Arne W. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kinkead, Allen K. [LET Corporation, Washington, DC 20007 (United States); Gai Wei; Power, John G.; Konecny, Richard; Jing Chunguang [Argonne National Laboratory, Argonne, IL 60439 (United States); Tantawi, Sami G.; Nantista, Christopher D. [Stanford Linear Accelerator Center, Menlo Park, CA 94025 (United States); Hu, Y.; Chen, H.; Tang, C.; Lin, Y. [Tsinghua University, Beijing 100084 (China); Bruce, Ralph W.; Bruce, Robert L. [RWBruce Associates, Inc., Arnold, MD 21012 (United States); Lewis, David III [Material Science and Technology Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2004-12-07

142

Development of a 20-MeV Dielectric-Loaded Accelerator Test Facility  

SciTech Connect

This paper describes a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded accelerator (DLA) test facility powered by a high-power 11.424-GHz magnicon amplifier. The magnicon can presently produce 25 MW of output power in a 250-ns pulse at 10 Hz, and efforts are in progress to increase this to 50 MW. The facility will include a 5 MeV electron inector being developed by the Accelerator Laboratory of Tsinghua University in Beijing, China. The DLA test structures are being developed by ANL, and some have undergone testing at NRL at gradients up to {approx} 8 MV/m. SLAC is developing a means to combine the two magnicon output arms, and to drive an injector and accelerator with separate control of the power ratio and relative phase. RWBruce Associates, Inc., working with NRl, is developing a means to join short ceramic sections into a continuous accelerator tube by ceramic brazing using an intense millimeter-wave beam. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA structure, and spectrometer, should take place within the next year. The facility will be used for testing DLA structures using a variety of materials and configurations, and also for testing other X-band accelerator concepts. The initial goal is to produce a compact 20 MeV dielectric-loaded test accelerator.

Gold, S.H.; Kinkead, A.K.; Gai, W.; Power, J.G.; Konecny, R.; Jing, C.G.; Tantawi, S.G.; Nantista, C.D.; Hu, Y.; Chen, H.; Tang, C.; Lin, Y.; Bruce, R.W.; Bruce, R.L.; Fliflet, A.W.; Lewis, D.; /Naval Research Lab, Wash., D.C. /LET Corp., Washington /Argonne /SLAC /Tsinghua U., Beijing

2005-06-22

143

78 FR 60998 - Strategies To Accelerate the Testing and Adoption of Pay for Success (PFS) Financing Models  

Federal Register 2010, 2011, 2012, 2013

...Strategies To Accelerate the Testing and Adoption of Pay for Success (PFS) Financing...achievement of program outcomes by accelerating adoption of PFS to improve program outcomes...stakeholders on strategies for accelerating PFS adoption and learning, including...

2013-10-02

144

Preparation of an Accelerated Protection Test Method for Lubricants, Corrosion Preventives and Hydraulic Fluids.  

National Technical Information Service (NTIS)

An accelerated condensation protection test method was prepared for publication as a standard method in Federal Test Method Standard No. 791. The method was established by determining the protective life of twenty-two samples of corrosion preventive oils,...

R. E. Johnson

1973-01-01

145

Experimental evaluation of the Battelle accelerated test design for the solar array at Mead, Nebraska  

NASA Technical Reports Server (NTRS)

A previously developed test design for accelerated aging of photovoltaic modules was experimentally evaluated. The studies included a review of relevant field experience, environmental chamber cycling of full size modules, and electrical and physical evaluation of the effects of accelerated aging during and after the tests. The test results indicated that thermally induced fatigue of the interconnects was the primary mode of module failure as measured by normalized power output. No chemical change in the silicone encapsulant was detectable after 360 test cycles.

Frickland, P. O.; Repar, J.

1982-01-01

146

Design and Simulation of IOTA - a Novel Concept of Integrable Optics Test Accelerator  

SciTech Connect

The use of nonlinear lattices with large betatron tune spreads can increase instability and space charge thresholds due to improved Landau damping. Unfortunately, the majority of nonlinear accelerator lattices turn out to be nonintegrable, producing chaotic motion and a complex network of stable and unstable resonances. Recent advances in finding the integrable nonlinear accelerator lattices have led to a proposal to construct at Fermilab a test accelerator with strong nonlinear focusing which avoids resonances and chaotic particle motion. This presentation will outline the main challenges, theoretical design solutions and construction status of the Integrable Optics Test Accelerator (IOTA) underway at Fermilab.

Nagaitsev, S.; Valishev, A.; /Fermilab; Danilov, V.V.; /Oak Ridge; Shatilov, D.N.; /Novosibirsk, IYF

2012-05-01

147

A life time model for ceramic thermal barrier coatings  

Microsoft Academic Search

The life time of Y2O3 stabilized ZrO2 thermal barrier coatings (TBC) has been modelled using a rather simple fracture mechanical approach. The basis of the model, is a finite element analysis of the thermal stresses and approximate assumptions of crack growth along the bond coat (BC)-ceramics interface. The FE calculations show the influence of several microstructural features of the TBC

F. Traeger; M. Ahrens; R. Vaßen; D. Stöver

2003-01-01

148

A flexible and configurable system to test accelerator magnets  

Microsoft Academic Search

Fermilab's accelerator magnet R&D programs, including production of superconducting high gradient quadrupoles for the LHC insertion regions, require rigorous yet flexible magnetic measurement systems. Measurement systems must be capable of handling various types of hardware and extensible to all measurement technologies and analysis algorithms. A tailorable software system that satisfies these requirements is discussed. This single system, capable of distributed

Jerzy M. Nogiec; J. Dimarco; H. Glass; J. Sim; K. Trombly-Freytag; G. Velev; D. Walbridge

2001-01-01

149

Accelerated aging for testing polymeric biomaterials and medical devices  

Microsoft Academic Search

Elevated temperature is frequently used to accelerate the aging process in polymers that are associated with medical devices and other applications. A common approach is to assume that the rate of aging is increased by a factor of 2?T\\/10, where ?T is the temperature increase. This result is a mathematical expression of the empirical observation that increasing the temperature by

D. W. L. Hukins; A. Mahomed; S. N. Kukureka

2008-01-01

150

High energy acceleration of H{sup {minus}} ion beam at MeV test facility  

SciTech Connect

MeV test facility was constructed for proof-of-principle test of 1 MeV, 1 A class negative ion beam acceleration. The dimensions of the ion source/accelerator is 2 m in diameter and 1.9 m in height. The H{sup {minus}} ions were produced in a KAMABOKO shaped volume production type negative ion source, and extracted through 49 apertures of 14 mm in diameter. The accelerator is a five-stage electrostatic accelerator with insulator columns made of fiber reinforced plastic (FRP). The accelerator was conditioned to hold the voltage up to 760 kV without beam. Then the H{sup {minus}} ion beams of 0.23 A (drain current) were successfully accelerated up to 700 keV for 1 s. Degradation of voltage holding characteristics was not observed with/without the beam at this level of the current and energy. {copyright} {ital 1996 American Institute of Physics.}

Inoue, T.; Fujiwara, Y.; Miyamoto, K.; Miyamoto, N.; Nagase, A.; Ohara, Y.; Okumura, Y.; Watanabe, K.; Yokoyama, K. [Japan Atomic Energy Research Institute, Naka, Naka-machi, Naka-gun, Ibaraki-ken 311-01 (Japan)

1996-07-01

151

Some practical observations on the accelerated testing of Nickel-Cadmium Cells  

NASA Technical Reports Server (NTRS)

A large scale test of 6.0 Ah Nickel-Cadmium Cells conducted at the Naval Weapons Support Center, Crane, Indiana has demonstrated a methodology for predicting battery life based on failure data from cells cycled in an accelerated mode. After examining eight variables used to accelerate failure, it was determined that temperature and depth of discharge were the most reliable and efficient parameters for use in accelerating failure and for predicting life.

Mcdermott, P. P.

1979-01-01

152

Results of an accelerated borehole closure testing program at Avery Island: Topical report RSI-0211  

SciTech Connect

This report presents the results of an accelerated borehole closure testing program conducted in the ONWI test facility in the Avery Island salt mine. The accelerated borehole closure tests were a part of a field testing program at Avery Island to provide data on the thermomechanical response of domal salt when subjected to conditions similar to those expected in a high-level nuclear waste repository. The primary objective of the accelerated borehole closure test is to provide data that can be used for validation of the numerical methods used to predict the creep behavior of salt. Two series of accelerated borehole closure tests were performed. The first of these (Phase I) was conducted during 1980, and the second (Phase II) was conducted during 1981 and 1982. 5 refs., 19 figs., 2 tabs.

Stickney, R.G.

1985-04-01

153

Timescale Correlation between Marine Atmospheric Exposure and Accelerated Corrosion Testing - Part 2  

NASA Technical Reports Server (NTRS)

Evaluation of metals to predict service life of metal-based structures in corrosive environments has long relied on atmospheric exposure test sites. Traditional accelerated corrosion testing relies on mimicking the exposure conditions, often incorporating salt spray and ultraviolet (UV) radiation, and exposing the metal to continuous or cyclic conditions similar to those of the corrosive environment. Their reliability to correlate to atmospheric exposure test results is often a concern when determining the timescale to which the accelerated tests can be related. Accelerated corrosion testing has yet to be universally accepted as a useful tool in predicting the long-term service life of a metal, despite its ability to rapidly induce corrosion. Although visual and mass loss methods of evaluating corrosion are the standard, and their use is crucial, a method that correlates timescales from accelerated testing to atmospheric exposure would be very valuable. This paper presents work that began with the characterization of the atmospheric environment at the Kennedy Space Center (KSC) Beachside Corrosion Test Site. The chemical changes that occur on low carbon steel, during atmospheric and accelerated corrosion conditions, were investigated using surface chemistry analytical methods. The corrosion rates and behaviors of panels subjected to long-term and accelerated corrosion conditions, involving neutral salt fog and alternating seawater spray, were compared to identify possible timescale correlations between accelerated and long-term corrosion performance. The results, as well as preliminary findings on the correlation investigation, are presented.

Montgomery, Eliza L.; Calle, Luz Marina; Curran, Jerome C.; Kolody, Mark R.

2012-01-01

154

Results of an accelerated borehole closure testing program at Avery Island, Louisiana  

SciTech Connect

This report presents the results of an accelerated borehole closure testing program conducted in the test facility in the Avery Island salt mine. The accelerated borehole closure tests provided data on the thermomechanical response of domal salt when subjected to conditions similar to those expected in a high-level nuclear waste repository. The objective is to aid numerical methods used to predict the creep behavior of salt. 5 refs., 19 figs., 2 tabs.

Stickney, R.G.

1987-09-01

155

Mycologg: a new accelerated test method for wood durability above ground  

Microsoft Academic Search

If not properly handled, selected and protected, wood will be degraded by bacteria, fungi and also insects. In order to ensure\\u000a service life, durability tests are needed. Most accelerated laboratory tests on wood durability are focused either on fungi\\u000a attacks or the uptake of moisture. Accelerated field tests in ground contact are of limited use since they could be difficult

Å. Blom; M. Bergström

2005-01-01

156

Operational status of the Brookhaven National Laboratory Accelerator Test Facility  

SciTech Connect

Design and operation of a 50 MeV Electron Linear Accelerator utilizing a low emittance ({gamma} {var epsilon} = 5 to 10 mm-mrad) radio frequency gun operating at an output energy of 5 MeV and a charge of 1 nC is described. Design calculations and early radio frequency measurements and operational experience with the electron gun utilizing a dummy copper cathode in place of the proposed photocathode emitter are given. 6 refs., 9 figs., 1 tab.

Batchelor, K.; Ben-Zvi, I.; Chou, T.S.; Fernow, R.C.; Fischer, J.; Gallarado, J.; Kirk, H.G.; Palmer, R.B.; Pellegrini, C.; Sheehan, J.; Srinivasan-Rao, T.; Ulc, S.; Van Steenbergen, A.; Woodle, M.; Biglio, I.; Kurnit, N.; McDonald, K.T. (Brookhaven National Lab., Upton, NY (USA); Los Alamos National Lab., NM (USA); Princeton Univ., NJ (USA). Dept. of Physics)

1989-01-01

157

A Proposal for a TESLA Accelerator Module Test Facility  

Microsoft Academic Search

The Tera-eV Energy Superconducting Linear Accelerator (TESLA), a 32 km long superconducting linear electron\\/positron collider of 500 GeV (upgradeable to 800 GeV) centre of mass energy, presently in the planning phase at DESY, will consist of about 21000 superconducting RF-9-cell cavities of pure Niobium, cooled in a 2.0 K helium bath. The cavities will be assembled in groups of 12

W. D. Moeller; B. Petersen; B. Sparr; Elektronen Synchrotron

158

Tests on S-Band Superconducting Niobium Prototype Accelerator Structures  

Microsoft Academic Search

The fabrication, processing, and measurement of two S-band niobium prototype electron accelerator structures are discussed. Maximum surface magnetic fields were typically between 250 and 550 Oe, corresponding to average energy gradients between 4.6 and 6.5 MeV\\/m, with Q0 values typically greater than 5 ?? 109. The structures which were electropolished gave more reproducible results than those which were chemically polished.

P. Kneiselt; C. Lyneis; J. P. Turneaure

1975-01-01

159

Acceleration \\  

Microsoft Academic Search

The paper proposes a digital compensation by imposing real-time compensation voltage to Vin Pin of VCOXCO while device vibrating. The embedded digital compensating circuit includes a MEMS three-axes acceleration sensor, a FPGA and a D\\/A converter. G-sensitivity vector can be computed based on the MEMS sensor. A proportion digital compensation model is built to generate voltage which can compensate frequency

QingXiao Shan; Yang Jun; JianYun Chen; Tang Qian; LongZhe Ji

2011-01-01

160

Estimation of the Join Point in a Heteroscedastic Regression Model Arising in Accelerated Life Tests.  

National Technical Information Service (NTIS)

In certain accelerated life test experiments, when accelerating beyond certain values of the stress, a change in the basic failure mechanism occurs. Such situations call for the introduction of two or more submodels joined at what is known as a join point...

N. D. Singpurwalla

1974-01-01

161

Estimation of the Join Point in a Heteroscedastic Regression Model Arising in Accelerated Life Tests.  

National Technical Information Service (NTIS)

In certain accelerated life test experiments, when accelerating beyond certain values of the stress, a change in the basic failure mechanism occurs. Such situations call for the introduction of two or more submodels joined at what is known as a joint poin...

N. D. Singpurwalla

1973-01-01

162

Low-level RF signal processing for the Next Linear Collider Test Accelerator.  

National Technical Information Service (NTIS)

In the X-band accelerator system for the Next Linear Collider Test Accelerator (NLCTA), the Low Level RF (LLRF) drive system must be very phase stable, but concurrently, be very phase agile. Phase agility is needed to make the Stanford Linear Doubler (SLE...

S. Holmes C. Ziomek C. Adolphsen

1997-01-01

163

Commissioning of the first drift tube linac module in the Ground Test Accelerator.  

National Technical Information Service (NTIS)

The Ground Test Accelerator (GTA) has the objective of verifying much of the technology required for producing high-brightness, high-current H(sup (minus)) beams. GTA commissioning is staged to verify the beam-dynamics design of each major accelerator com...

K. F. Johnson O. R. Sander W. H. Atkins G. O. Bolme S. Bowling

1993-01-01

164

A review of accelerated stress tests of MEA durability in PEM fuel cells  

Microsoft Academic Search

This paper is a review of recent work done on accelerated stress tests in the study of PEM fuel cell durability, with a primary focus on the main components of the membrane electrode assembly (MEA). The accelerated stressors for each component under different conditions are outlined, in an attempt to gain a detailed understanding of cell degradation with respect to

Shengsheng Zhang; Xiaozi Yuan; Haijiang Wang; Walter Mérida; Hong Zhu; Jun Shen; Shaohong Wu; Jiujun Zhang

2009-01-01

165

Development of a 20 MeV Dielectric-Loaded Test Accelerator  

SciTech Connect

This paper presents a progress report on a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded test accelerator in the magnicon facility at NRL. The accelerator will be powered by an experimental 11.424-GHz magnicon amplifier that presently produces 25 MW of output power in a {approx}250-ns pulse at up to 10 Hz. The accelerator will include a 5-MeV electron injector originally developed at the Tsinghua University in Beijing, China, and can incorporate DLA structures up to 0.5 m in length. The DLA structures are being developed by ANL, and shorter test structures fabricated from a variety of dielectric materials have undergone testing at NRL at gradients up to {approx}8 MV/m. SLAC has developed components to distribute the power from the two magnicon output arms to the injector and to the DLA accelerating structure with separate control of the power ratio and relative phase. RWBruce Associates, Inc., working with NRL, has investigated means to join short ceramic sections into a continuous accelerator tube by a brazing process using an intense 83-GHz beam. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA test structure, and spectrometer, should take place within the next year.

Gold, S.H.; Kinkead, A.K.; Gai, W.; Power, J.G.; Konecny, R.; Jing, C.; Long, J.; Tantawi, S.G.; Nantista, C.D.; Fliflet, A.W.; Lombardi, M.; Lewis, D.; /Naval Research Lab, Wash., D.C. /LET Corp., Washington /Argonne /Euclid Techlabs, Solon /SLAC; Bruce, R.W.; /Unlisted

2007-04-13

166

Development of a 20 MeV Dielectric-Loaded Test Accelerator  

SciTech Connect

This paper presents a progress report on a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded test accelerator in the magnicon facility at NRL. The accelerator will be powered by an experimental 11.424-GHz magnicon amplifier that presently produces 25 MW of output power in a {approx}250-ns pulse at up to 10 Hz. The accelerator will include a 5-MeV electron injector originally developed at the Tsinghua University in Beijing, China, and can incorporate DLA structures up to 0.5 m in length. The DLA structures are being developed by ANL, and shorter test structures fabricated from a variety of dielectric materials have undergone testing at NRL at gradients up to {approx}8 MV/m. SLAC has developed components to distribute the power from the two magnicon output arms to the injector and to the DLA accelerating structure with separate control of the power ratio and relative phase. RWBruce Associates, Inc., working with NRL, has investigated means to join short ceramic sections into a continuous accelerator tube by a brazing process using an intense 83-GHz beam. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA test structure, and spectrometer, should take place within the next year.

Gold, Steven H.; Fliflet, Arne W.; Lombardi, Marcie [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kinkead, Allen K. [LET Corporation, Washington, DC 20007 (United States); Gai, Wei; Power, John G.; Konecny, Richard; Long, Jidong [Argonne National Laboratory, Argonne, IL 60439 (United States); Jing, Chunguang [Argonne National Laboratory, Argonne, IL 60439 (United States); Euclid Techlabs, LLC, Solon, OH 44139 (United States); Tantawi, Sami G.; Nantista, Christopher D. [Stanford Linear Accelerator Center, Menlo Park, CA 94025 (United States); Bruce, Ralph W. [RWBruce Associates, Inc., Arnold, MD 21012 (United States); Lewis, David III [Material Science and Technology Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2006-11-27

167

Electrical parameters degradation of power RF LDMOS device after accelerated ageing tests  

Microsoft Academic Search

This paper reports novel methods for accelerated ageing tests, with comparative reliability between them for stresses applied on power RF LDMOS: Thermal Shock Tests (TST), Thermal Cycling Tests (TCT), High Voltage Drain (HVD) and coupling thermal and electrical effects under various conditions. The investigation findings obtained after various ageing tests show the degradation and the device’s performance shifts for most

M. A. Belaïd; K. Ketata; M. Masmoudi; M. Gares; H. Maanane; J. Marcon

2006-01-01

168

Testing of Composite Fan Vanes With Erosion-Resistant Coating Accelerated  

NASA Technical Reports Server (NTRS)

The high-cycle fatigue of composite stator vanes provided an accelerated life-state prior to insertion in a test stand engine. The accelerated testing was performed in the Structural Dynamics Laboratory at the NASA Glenn Research Center under the guidance of Structural Mechanics and Dynamics Branch personnel. Previous research on fixturing and test procedures developed at Glenn determined that engine vibratory conditions could be simulated for polymer matrix composite vanes by using the excitation of a combined slip table and electrodynamic shaker in Glenn's Structural Dynamics Laboratory. Bench-top testing gave researchers the confidence to test the coated vanes in a full-scale engine test.

Bowman, Cheryl L.; Sutter, James K.; Otten, Kim D.; Samorezov, Sergey; Perusek, Gail P.

2004-01-01

169

Development of a Compact Dielectric-Loaded Test Accelerator at 11.4 GHz  

SciTech Connect

This paper presents a progress report on the development of a dielectric-loaded test accelerator in the Magnicon Facility at the Naval Research Laboratory (NRL). The accelerator will be powered by an 11.4-GHz magnicon amplifier that provides up to 25 MW of output power in a {approx}250-ns pulse at up to 10 Hz. The accelerator includes a 5-MeV electron injector originally developed at the Tsinghua University in Beijing, China, and can incorporate dielectric-loaded accelerating (DLA) structures of up to 0.5 m in length. The DLA structures are being developed by Argonne National Laboratory and Euclid Techlabs, and shorter test structures fabricated from a variety of dielectric materials have undergone rf testing at NRL at accelerating gradients up to 15 MV/m. The first stage of the accelerator, including the 5-MeV injector, has recently begun operation, and initial operation of the complete dielectric-loaded test accelerator, including injector, DLA test structure, and spectrometer, should take place within the next year.

Gold, S. H.; Fliflet, A. W. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kinkead, A. K. [Icarus Research, Bethesda, MD 20814 (United States); Gai, W.; Power, J. G.; Konecny, R. [Argonne National Laboratory, Argonne, IL 60439 (United States); Jing, C. [Argonne National Laboratory, Argonne, IL 60439 (United States); Euclid Techlabs, Solon, OH 44139 (United States)

2009-01-22

170

Experimental Evaluation of the Battelle Accelerated Test Design for the Solar Array at Mead, Nebraska.  

National Technical Information Service (NTIS)

A previously developed test design for accelerated aging of photovoltaic modules was experimentally evaluated. The studies included a review of relevant field experience, environmental chamber cycling of full-size modules, and electrical and physical eval...

P. O. Frickland J. Repar

1982-01-01

171

Accelerated Environmental Testing. A Study of Highway Structure Corrosion Problems and Metal Protective Coating Systems.  

National Technical Information Service (NTIS)

This report provides a description of the design and operation of an accelerated corrosion environmental chamber for metal protective paints and a discussion of the findings of experiments designed to test the reproducibility of results in the chamber and...

W. R. Tooke D. R. Hurst

1973-01-01

172

High Acceleration Cockpits for Advanced Fighter Aircraft. Volume IV. Test Results.  

National Technical Information Service (NTIS)

A high acceleration cockpit design test/evaluation program was conducted, using a full scale design aid. Alternate configurations were compared using this full scale design aid in a formally structured evaluation including mission related task elements. T...

C. F. Asiala T. J. Quinn

1974-01-01

173

Testing Predictions Derived from a Model of Progressive Adaptation to Coriolis Accelerations.  

National Technical Information Service (NTIS)

A theoretical model for progressive adaptation to Coriolis accelerations is described. Thirteen subjects were tested under procedures identical to those using fixed velocity increments described in previous studies, but in this instance diminishing veloci...

A. J. Benson E. Diaz J. T. Reason

1971-01-01

174

Analysis of Accelerated Life Test Data for Aerospace Nickel-Cadmium Cells.  

National Technical Information Service (NTIS)

A process was developed for the accelerated life testing of a particular cell or battery which comprises the comparison and extrapolation of the end of discharge voltages plotted versus the logarithm of the cycle number in combination with prior knowledge...

E. A. Roeger, J. McCallum, G. H. Miller

1974-01-01

175

First High power test results for 2.1 GHz superconducting photonic band gap accelerator cavities.  

PubMed

We report the results of the recent high power testing of superconducting radio frequency photonic band gap (PBG) accelerator cells. Tests of the two single-cell 2.1 GHz cavities were performed at both 4 and 2 K. An accelerating gradient of 15 MV/m and an unloaded quality factor Q(0) of 4×10(9) were achieved. It has been long realized that PBG structures have great potential in reducing long-range wakefields in accelerators. A PBG structure confines the fundamental TM(01)-like accelerating mode, but does not support higher order modes. Employing PBG cavities to filter out higher order modes in superconducting particle accelerators will allow suppression of dangerous beam instabilities caused by wakefields and thus operation at higher frequencies and significantly higher beam luminosities. This may lead towards a completely new generation of colliders for high energy physics and energy recovery linacs for the free-electron lasers. PMID:23215084

Simakov, Evgenya I; Haynes, W Brian; Madrid, Michael A; Romero, Frank P; Tajima, Tsuyoshi; Tuzel, Walter M; Boulware, Chase H; Grimm, Terry L

2012-10-19

176

Verification of force and acceleration specifications for random vibration tests of Cassini spacecraft equipment  

NASA Technical Reports Server (NTRS)

The use of force limiting in the random vibration testing of the Cassini spacecraft's subsystems is reported on. A verification of the Cassini equipment random vibration test acceleration and force specifications is provided by interface acceleration and force data measured in acoustic tests of the Cassini spacecraft development test model (DTM). Acoustic tests were performed on the DTM structure with different structural and equipment configurations. The acceleration and force spectra at the interface between the equipment items and the spacecraft DTM structure were measured in the acoustic tests and compared with the equipment random vibration test specifications. The spacecraft's apparent masses were measured at the equipment mounting points and used in force limit predictions.

Chang, Kurng Y.; Scharton, Terry D.

1996-01-01

177

An accelerated test design for use with synchronous orbit. [on Ni-Cd cell degradation behavior  

NASA Technical Reports Server (NTRS)

The Naval Weapons Support Center at Crane, Indiana has conducted a large scale accelerated test of 6.0 Ah Ni-Cd cells. Data from the Crane test have been used to develop an equation for the description of Ni-Cd cell behavior in geosynchronous orbit. This equation relates the anticipated time to failure for a cell in synchronous orbit to temperature and overcharge rate sustained by the cell during the light period. A test design is suggested which uses this equation for setting test parameters for future accelerated testing.

Mcdermott, P. P.; Vasanth, K. L.

1980-01-01

178

The research of reliability and accelerated life tests method of oil-line pumps  

NASA Astrophysics Data System (ADS)

Mechanical pumps are used to show how to determine the useful life of a product and its corresponding reliability characteristic values and acceleration coefficient by means of constant stress accelerated life testing. The existing difficulties of lengthy life test time, high test cost, and unknown reliability indices are then resolved. The overall period of life test time has been shortened to one sixth of the original period of life test time. The weak elements, failure modes, and failure mechanisms of the product are identified as well. It provides a scientific base to improve the performance of a product.

Zhang, Pingping; Lu, Jiansheng; Zhang, Zengliang; Hu, Boling

1992-01-01

179

Evaluation of the long-term durability of yellow travertine using accelerated weathering tests  

Microsoft Academic Search

The study investigated the long-term performance\\/durability of yellow travertine against various environmental processes using\\u000a several accelerated weathering tests: wet–dry, freeze–thaw and salt crystallization. Prior to the accelerated weathering tests,\\u000a the specimens were separated into two groups based on their porosities. The re-crystallization pressure of Na2SO4 salt was found to be the most destructive factor in the deterioration of the yellow

Mutluhan AkinAydi; Ayd?n Özsan

2011-01-01

180

Methodology for predicting the life of waste-package materials, and components using multifactor accelerated life tests  

Microsoft Academic Search

Accelerated life tests are essential for estimating the service life of waste-package materials and components. A recommended methodology for generating accelerated life tests is described in this report. The objective of the methodology is to define an accelerated life test program that is scientifically and statistically defensible. The methodology is carried out using a select team of scientists and usually

R. E. Thomas; R. W. Cote

1983-01-01

181

Status and Plans for a Superconducting RF Accelerator Test Facility at Fermilab  

SciTech Connect

The Advanced Superconducting Test Accelerator (ASTA) is being constructed at Fermilab. The existing New Muon Lab (NML) building is being converted for this facility. The accelerator will consist of an electron gun, injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, multiple downstream beam lines for testing diagnostics and conducting various beam tests, and a high power beam dump. When completed, it is envisioned that this facility will initially be capable of generating a 750 MeV electron beam with ILC beam intensity. An expansion of this facility was recently completed that will provide the capability to upgrade the accelerator to a total beam energy of 1.5 GeV. Two new buildings were also constructed adjacent to the ASTA facility to house a new cryogenic plant and multiple superconducting RF (SRF) cryomodule test stands. In addition to testing accelerator components, this facility will be used to test RF power systems, instrumentation, and control systems for future SRF accelerators such as the ILC and Project-X. This paper describes the current status and overall plans for this facility.

Leibfritz, J.; Andrews, R.; Baffes, C.M.; Carlson, K.; Chase, B.; Church, M.D.; Harms, E.R.; Klebaner, A.L.; Kucera, M.; Martinez, A.; Nagaitsev, S.; /Fermilab

2012-05-01

182

Inference for Step-Stress Accelerated Life Tests under Arbitrary Right-Censorship,  

National Technical Information Service (NTIS)

A step-stress test is an accelerated life test in which the stress on an unfailed item is allowed to increase at a preassigned time. Step-stress testing is considered here from a non-parametric point of view when the observations have been arbitrarily rig...

D. T. McNichols, W. J. Padgett

1988-01-01

183

Testing of a Loop Heat Pipe Subjective to Variable Accelerations. Part 1; Start-up  

NASA Technical Reports Server (NTRS)

The effect of accelerating forces on the performance of loop heat pipes (LHP) is of interest and importance to terrestrial and space applications. They are being considered for cooling of military combat vehicles and for spinning spacecraft. In order to investigate the effect of an accelerating force on LHP operation, a miniature LHP was installed on a spin table. Variable accelerating forces were imposed on the LHP by spinning the table at different angular speeds. Several patterns of accelerating forces were applied, i.e. continuous spin at different speeds and periodic spin at different speeds and frequencies. The resulting accelerations ranged from 1.17 g's to 4.7 g's. This paper presents the first part of the experimental study, i.e. the effects of a centrifugal force on the LHP start-up. Tests were conducted by varying the heat load to the evaporator, sink temperature, magnitude and frequency of centrifugal force, and LHP orientation relative to the direction of the accelerating force. The accelerating force seems to have little effect on the loop start-up in terms of temperature overshoot and superheat at boiling incipience. Changes in these parameters seem to be stochastic with or without centrifugal accelerating forces. The LHP started successfully in all tests.

Ku, Jentung; Rogers, Paul; Hoff, Craig

2000-01-01

184

Accelerated Fatigue Testing of Stent-Like Diamond Specimens  

NASA Astrophysics Data System (ADS)

In this study, we investigated the fatigue behavior of stent-like diamond specimens with particular attention paid to the nature of the test specimen, the constitutive model for the finite element analyses and the displacement condition. A newly designed test rig did enhance the investigation and results with respect to the simulation of the expected in vivo displacement conditions. The excellent performance of the new test method presented within our study provides a good basis for future tests without risk of compromised results due to differing characteristics between test specimens and finished stents, inappropriate displacement conditions or constitutive material model and provides a high reliability and applicability of the results to actual stents.

Zipse, A.; Schlun, M.; Dreher, G.; Zum Gahr, J.; Rebelo, N.

2011-07-01

185

Testing of a Loop Heat Pipe Subjective to Variable Accelerations. Part 2; Temperature Stability  

NASA Technical Reports Server (NTRS)

The effect of accelerating forces on the performance of loop heat pipes (LHP) is of interest and importance to terrestrial and space applications. LHP's are being considered for cooling of military combat vehicles and for spinning spacecraft. In order to investigate the effect of an accelerating force on LHP operation, a miniature LHP was installed on a spin table. Variable accelerating forces were imposed on the LHP by spinning the table at different angular speeds. Several patterns of accelerating forces were applied, i.e. continuous spin at different speeds and periodic spin at different speeds and frequencies. The resulting accelerations ranged from 1.17 g's to 4.7 g's. This paper presents the second part of the experimental study, i.e. the effect of an accelerating force on the LHP operating temperature. It has been known that in stationary tests the LHP operating temperature is a function of the evaporator power and the condenser sink temperature when the compensation temperature is not actively controlled. Results of this test program indicate that any change in the accelerating force will result in a chance in the LHP operating temperature through its influence on the fluid distribution in the evaporator, condenser and compensation chamber. However, the effect is not universal, rather it is a function of other test conditions. A steady, constant acceleration may result in an increase or decrease of the operating temperature, while a periodic spin will lead to a quasi-steady operating temperature over a sufficient time interval. In addition, an accelerating force may lead to temperature hysteresis and changes in the temperature oscillation. In spite of all these effects, the LHP continued to operate without any problems in all tests.

Ku, Jentung; Ottenstein, Laura; Kaya, Taril; Rogers, Paul; Hoff, Craig

2000-01-01

186

Low-energy demonstration accelerator (LEDA) test results and plans  

SciTech Connect

The LEDA 75-keV injector and 6.7-MeV RFQ have been tested with pulsed and cw proton beam currents up to 100 mA. Several LINAC2000 papers give the results of those measurements. A follow-on experiment, to intentionally introduce and measure beam halo on the RFQ output beam, is reported in several papers at this conference (PAC2001). In this paper we summarize the LEDA RFQ commissioning results and the beam-halo measurements and we discuss future test plans for this high-current, high-average-power rf structures test bed.

Smith, H. V. (Horace V.); Schneider, J. D. (J. David); Sheffield, R. L. (Richard L.)

2001-01-01

187

Accelerated irradiation test of Gundremmingen reactor vessel trepan material  

SciTech Connect

Initial mechanical properties tests of beltline trepanned from the decommissioned KRB-A pressure vessel and archive material irradiated in the UBR test reactor revealed a major anomaly in relative radiation embrittlement sensitivity. Poor correspondence of material behavior in test vs. power reactor environments was observed for the weak test orientation (ASTL C-L) whereas correspondence was good for the strong orientation (ASTM C-L). To resolve the anomaly directly, Charpy-V specimens from a low (essentially-nil) fluence region of the vessel were irradiated together with archive material at 279{degrees}C in the UBR test reactor. Properties tests before UBR irradiation revealed a significant difference in 41-J transition temperature and upper shelf energy level between the materials. However, the materials exhibited essentially the same radiation embrittlement sensitivity (both orientations), proving that the anomaly is not due to a basic difference in material irradiation resistances. Possible causes of the original anomaly and the significance to NRC Regulatory Guide 1.99 are discussed.

Hawthorne, J.R. [Materials Engineering Associates, Inc., Lanham, MD (United States)

1992-08-01

188

Preliminary results from pressure tank test and field acceleration test of New-Profiling float of Japan (NINJA)  

Microsoft Academic Search

As one of contributions of Japan to the international Argo community, one of Japanese ocean instrument manufacturers, Tsurumi Seiki Co. (TSK), has started the development of original profiling float in 2000. We purchased the four TSK floats in 2001, and performed the pressure tank test and the acceleration field test in the north Pacific. Among four floats, two are carrying

K. Izawa; K. Ando; K. Mizuno; A. Inoue; N. Shikama; K. Takeuchi; M. Sekimoto

2002-01-01

189

Accelerated in vitro release testing methods for extended release parenteral dosage forms  

PubMed Central

Objectives This review highlights current methods and strategies for accelerated in vitro drug release testing of extended release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in situ depot-forming systems, and implants. Key findings Extended release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, “real-time” in vitro release tests for these dosage forms are often run over a long time period. Accelerated in vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in vitro release methods using United States Pharmacopoeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended release parenteral dosage forms, along with the accelerated in vitro release testing methods currently employed are discussed. Conclusions Accelerated in vitro release testing methods with good discriminatory ability are critical for quality control of extended release parenteral products. Methods that can be used in the development of in vitro-in vivo correlation (IVIVC) are desirable, however for complex parenteral products this may not always be achievable.

Shen, Jie; Burgess, Diane J.

2012-01-01

190

Investigating the feasibility of temperature-controlled accelerated drug release testing for an intravaginal ring.  

PubMed

The objective of the present study was to investigate if temperature can be utilized to accelerate drug release from Nuvaring®, a reservoir type intravaginal ring based on polyethylene vinyl acetate copolymer that releases a constant dose of contraceptive steroids over a duration of 3 weeks. The reciprocating holder apparatus (USP 7) was utilized to determine real-time and accelerated etonogestrel release from ring segments. It was demonstrated that drug release increased with increasing temperature which can be attributed to enhanced drug diffusion. An Arrhenius relationship of the zero-order release constants was established, indicating that temperature is a valid parameter to accelerate drug release from this dosage form and that the release mechanism is maintained under these accelerated test conditions. Accelerated release tests are particularly useful for routine quality control to assist during batch release of extended release formulations that typically release the active over several weeks, months or even years, since they can increase the product shelf life. The accelerated method should therefore be able to discriminate between formulations with different release characteristics that can result from normal manufacturing variance. In the case of Nuvaring®, it is well known that the process parameters during the extrusion process strongly influence the polymeric structure. These changes in the polymeric structure can affect the permeability which, in turn, is reflected in the release properties. Results from this study indicate that changes in the polymeric structure can lead to a different temperature dependence of the release rate, and as a consequence, the accelerated method can become less sensitive to detect changes in the release properties. When the accelerated method is utilized during batch release, it is therefore important to take this possible restriction into account and to evaluate the accelerated method with samples from non-conforming batches that are explicitly "out of specification" under real-time test conditions. PMID:23791685

Externbrink, Anna; Clark, Meredith R; Friend, David R; Klein, Sandra

2013-11-01

191

Step-stress accelerated degradation test modeling and statistical analysis methods  

NASA Astrophysics Data System (ADS)

In order to get a rapid assessment on the storage reliability of high-reliable and long-life products within the storage period, accelerated degradation test data with a large amount of reliability information of product is adopted. Conducting a constant-stress accelerated degradation test(CSADT) is generally very costly as it requires a large sample size and long time for test. To overcome this problem, it is necessary to carry out research on modeling and statistical analysis methods of step-stress accelerated degradation test (SSADT). Taking electrical connectors as the object, a research is conducted on statistical model and assessment method for SSADT. On the basis of mixed-effect degradation path model, the statistical model of SSADT for electrical connectors is presented, the maximum likelihood method for SSADT data based on mixed-effect degradation model is proposed. SSADT accelerated by temperature stress is conducted to Y11X-1419 type of electrical connectors, and the storage reliability is assessed with the SSADT data. Compared with the result obtained from accelerated life test, the reliability estimation of 32-year storage period for electrical connectors obtained from SSADT data only have a difference of 0.869%, which validates the accuracy of the degradation model and the feasibility of the test data statistic analysis method put forward.

Chen, Wenhua; Liu, Juan; Gao, Liang; Pan, Jun; Lu, Xianbiao

2013-11-01

192

Study of shock acceleration mechanisms of charged energetic particles with test particle simulations  

NASA Astrophysics Data System (ADS)

Shock acceleration is considered one of the most important mechanisms of space energetic particles' propagation. Much efforts have been done to investigate the shock acceleration of energetic particles, but it is still a puzzle for the community about shock acceleration. In this work, we numerically solve a large amount of test charged particles' trajectories in model shock fields with magnetic turbulence typical in space environment. In addition, from the simulation results we obtain particles' energy increase due to the shock crossing and compare it with different theories. Furthermore, we compare our simulation results with spacecraft measurements, so that we are able to explain some observation phenomena.

Zhang, L.; Qin, G.

2012-12-01

193

Technological Issues and High Gradient Test Results on X-Band Molybdenum Accelerating Structures  

SciTech Connect

Two 11.424 GHz single cell standing wave accelerating structures have been fabricated for high gradient RF breakdown studies. Both are brazed structures: one made from copper and the other from sintered molybdenum bulk. The tests results are presented and compared to those of similar devices constructed at SLAC (Stanford Linear Accelerator Center) and KEK (Ko Enerugi Kasokuki Kenkyu Kiko). The technological issues to build both sections are discussed.

Spataro, B.; /LNF, Dafne Light; Alesini, D.; /LNF, Dafne Light; Chimenti, V.; /LNF, Dafne Light; Dolgashev, V.; /SLAC; Haase, A.; /SLAC; Tantawi, S.G.; /SLAC; Higashi, Y.; /KEK, Tsukuba; Marrelli, C.; /Rome U.; Mostacci, A.; /Rome U.; Parodi, R.; /INFN, Genoa; Yeremian, A.D.; /SLAC

2012-04-24

194

Planning step-stress life-test with a target acceleration-factor  

Microsoft Academic Search

A sequential approach is presented to plan a multiple-steps step-stress accelerated life test (SSALT) with type-I censoring so as to achieve a pre-specified acceleration factor. An initial optimal plan for a simple SSALT, where one not only has to determine the optimum hold-time under low stress but also the optimum low stress level, is obtained by solving a constrained nonlinear

Kwee-Poo Yeo; Loon-Ching Tang

1999-01-01

195

Commissioning of the first drift tube linac module in the Ground Test Accelerator  

Microsoft Academic Search

The Ground Test Accelerator (GTA) has the objective of verifying much of the technology required for producing high-brightness, high-current H- beams. GTA commissioning is staged to verify the beam-dynamics design of each major accelerator component as it is brought online. The major components are the 35-keV H- injector, the 2.5-MeV radiofrequency quadrupole (RFQ), the intertank matching section (IMS), the 3.2

K. F. Johnson; O. R. Sander; G. O. Bolme; S. Bowling; R. Connolly; P. Denney; J. Erickson; J. D. Gilpatrick; W. B. Ingalls; D. Kersteins; R. Kraus; W. P. Lysenko; D. McMurry; C. T. Mottershead; J. Power; C. Rose; D. P. Rusthoi; D. P. Sandoval; J. D. Schneider; M. Smith; G. Vaughn; E. A. Wadlinger; R. Weiss; V. Yuan

1993-01-01

196

High power testing of a fused quartz-based dielectric-loaded accelerating structure.  

SciTech Connect

We report on the most recent results from a series of high power tests being carried out on rf-driven dielectric-loaded accelerating (DLA) structures. The purpose of these tests is to determine the viability of the DLA as a traveling-wave accelerator and is a collaborative effort between Argonne National Laboratory (ANL), Naval Research Laboratory (NRL), and Stanford Linear Accelerator Center (SLAC). In this paper, we report on the recent high power tests of a fused quartz-based DLA structure that was carried out at incident powers of up to 12 MW at NRL and 37 MW at SLAC. We also report on test results of a TiN coated quartz structure, that exhibits good multipactor suppression.

Power, J. G.; Konecny, R.; Gai, W.; Yusof, Z.; Gold, S. H.; Kinkead, A.; Dolgashev, V.; Tantawi, S. G.; Jing, C.; High Energy Physics; Euclid techlabs, LLC; LET Corp.; SLAC; NRL

2008-01-01

197

High Power Testing of A Fused Quartz-based Dielectric-Loaded Accelerating Structure  

SciTech Connect

We report on the most recent results from a series of high power tests being carried out on rf-driven dielectric loaded accelerating (DLA) structures. The purpose of these tests is to determine the viability of the DLA as a traveling-wave accelerator and is a collaborative effort between Argonne National Laboratory (ANL), Naval Research Laboratory (NRL), and Stanford Linear Accelerator Center (SLAC). In this paper, we report on the recent high power tests of a fused quartz-based DLA structure that was carried out at incident powers of up to 12 MW at NRL and 37 MW at SLAC. We also report on test results of a TiN coated quartz structure, that exhibits good multipactor suppression.

Jing, C.; /Euclid Techlabs, Solon; Power, J.G.; Konecny, R.; Gai, W.; Yusof, Z.; /Argonne; Gold, S.H.; /Naval Research Lab, Wash., D.C.; Kinkead, A.K.; /LET Corp., Washington; Dolgashev, V.; Tantawi, S.G.; /SLAC

2007-11-07

198

A facility to test short superconducting accelerator magnets at Fermilab  

SciTech Connect

During the past four years the Superconducting Magnet R D facility at Fermilab (Lab 2) has successfully tested superconducting dipole, quadrupole, and correction coil magnets less than 2 meters in length for the SSC project and the Tevatron D0/B0 Low-[beta] Insertion. During this time several improvements have been made to the facility that have greatly enhanced its magnet testing capabilities. Among the upgrades have been a new rotating coil and data acquisition system for measuring magnetic fields, a controlled flow liquid helium transfer line using an electronically actuated cryo valve, and stand-alone systems for measuring AC loss and training low current Tevatron correction coil packages. A description of the Lab 2 facilities is presented.

Lamm, M.J.; Hess, C.; Lewis, D.; Jaffery, T.; Kinney, W.; Ozelis, J.P.; Strait, J. (Fermi National Accelerator Lab., Batavia, IL (United States)); Butteris, J.; McInturff, A.D. (Superconducting Super Collider Lab., Dallas, TX (United States)); Coulter, K.J. (Argonne National Lab., IL (United States))

1992-10-01

199

Mechanical Component Lifetime Estimation Based on Accelerated Life Testing with Singularity Extrapolation  

NASA Astrophysics Data System (ADS)

Life testing under nominal operating conditions of mechanical parts with high mean lifetime between failure (MTBF) often consumes a significant amount of time and resources, rendering such procedures expensive and impractical. As a result, the technology of accelerated life testing (ALT) has been developed for testing at high stress levels (e.g. temperature, voltage, pressure, corrosive media, load, vibration amplitude, etc.) so that it can be extrapolated—through a physically reasonable statistical model—to obtain estimations of life at lower, normal stress levels or even limit stress levels. However, the issue of prediction accuracy associated with extrapolating data outside the range of testing, or even to a singularity level (no stress), has not yet been fully addressed. In this research, an accelerator factor is introduced into an inverse power law model to estimate the life distribution in terms of time and stresses. Also, a generalized Eyring model is set up for singularity extrapolation in handling limit stress level conditions. The procedure to calibrate the associated shape factors based on the maximum likelihood principle is also formulated. The methodology implementation, based on a one-main-step, multiple-step-stress test scheme, is experimentally illustrated with tapered roller bearing under the stress of environmental corrosion as a case study. The experimental results show that the developed accelerated life test model can effectively evaluate the life probability of a bearing based on accelerated testing data when extrapolating to the stress levels within or outside the range of testing.

Zhang, C.; Chuckpaiwong, I.; Liang, S. Y.; Seth, B. B.

2002-07-01

200

Accelerated test program for sealed nickel-cadmium spacecraft batteries/cells  

NASA Technical Reports Server (NTRS)

The feasibility was examined of inducing an accelerated test on sealed Nickel-Cadmium batteries or cells as a tool for spacecraft projects and battery users to determine: (1) the prediction of life capability; (2) a method of evaluating the effect of design and component changes in cells; and (3) a means of reducing time and cost of cell testing.

Goodman, L. A.

1976-01-01

201

Advanced X-Band Test Accelerator for High Brightness Electron and Gamma Ray Beams.  

National Technical Information Service (NTIS)

In support of Compton scattering gamma-ray source efforts at LLNL, a multi-bunch test stand is being developed to investigate accelerator optimization for future upgrades. This test stand will enable work to explore the science and technology paths requir...

C. Adolphsen C. A. Ebbers C. P. J. Barty D. J. Gibson F. V. Hartemann R. A. Marsh S. G. Anderson T. S. Chu

2012-01-01

202

Accelerated testing for time dependent dielectric breakdown (TDDB) evaluation of embedded DRAM capacitors using tantalum pentoxide  

Microsoft Academic Search

Mechanisms of breakdown in Ta2O5 are evaluated by studying the leakage and TDDB characteristics, and a model close to those widely accepted for SiO2 is suggested. Various statistical modeling approaches are evaluated and used to verify this breakdown model. Accelerated testing techniques are also outlined that can dramatically improve parameter estimates while slashing reliability test times.

Anand Inani; Victor Koldyaev; Spencer Graves

2007-01-01

203

Isolation of a piezoresistive accelerometer used in high acceleration tests  

SciTech Connect

Both uniaxial and triaxial shock isolation techniques for a piezoresistive accelerometer have been developed for pyroshock and impact tests. The uniaxial shock isolation technique has demonstrated acceptable characteristics for a temperature range of {minus}50{degree}F to +186{degree}F and a frequency bandwidth of DC to 10 kHz. The triaxial shock isolation technique has demonstrated acceptable results for a temperature range of {minus}50{degree}F to 70{degree}F and a frequency bandwidth of DC to 10 kHz. These temperature ranges, that are beyond the accelerometer manufacturer`s operational limits of {minus}30{degree}F and +150{degree}F, required the calibration of accelerometers at high shock levels and at the temperature extremes of {minus}50{degree}F and +160{degree}F. The purposes of these calibrations were to insure that the accelerometers operated at the field test temperatures and to provide an accelerometer sensitivity at each test temperature. Since there is no NIST-traceable (National Institute of Standards and Technology traceable) calibration capability at shock levels of 5,000 g - 15,000 g for the temperature extremes of {minus}50{degree}F and +160{degree}F, a method for calibrating and certifying the Hopkinson bar with a transfer standard was developed. Time domain and frequency domain results are given that characterize the Hopkinson bar. The NIST-traceable accuracy for the standard accelerometer in shock is {plus_minus}5%. The Hopkinson bar has been certified by the Sandia Secondary Standards Division with an uncertainty of 6%.

Bateman, V.I.; Brown, F.A.; Davie, N.T.

1992-12-31

204

ACCELERATORS Control system for the CSNS ion source test stand  

NASA Astrophysics Data System (ADS)

A penning plasma surface H- ion source test stand for the CSNS has just been constructed at the IHEP. In order to achieve a safe and reliable system, nearly all devices of the ion source are designed to have the capability of both local and remote operation function. The control system consists of PLCs and EPICS real-time software tools separately serving device control and monitoring, PLC integration and OPI support. This paper summarizes the hardware and software implementation satisfying the requirements of the ion source control system.

Lu, Yan-Hua; Li, Gang; Ouyang, Hua-Fu

2010-12-01

205

An accelerated stress testing program for determining the reliability sensitivity of silicon solar cells to encapsulation and metallization systems  

NASA Technical Reports Server (NTRS)

The use of accelerated testing methods in a program to determine the reliability attributes of terrestrial silicon solar cells is discussed. Different failure modes are to be expected when cells with and without encapsulation are subjected to accelerated testing and separate test schedules for each are described. Unencapsulated test cells having slight variations in metallization are used to illustrate how accelerated testing can highlight different diffusion related failure mechanisms. The usefulness of accelerated testing when applied to encapsulated cells is illustrated by results showing that moisture related degradation may be many times worse with some forms of encapsulation than with no encapsulation at all.

Lathrop, J. W.; Davis, C. W.; Royal, E.

1982-01-01

206

An accelerated exposure and testing apparatus for building joint sealants.  

PubMed

The design, fabrication, and implementation of a computer-controlled exposure and testing apparatus for building joint sealants are described in this paper. This apparatus is unique in its ability to independently control and monitor temperature, relative humidity, ultraviolet (UV) radiation, and mechanical deformation. Each of these environmental factors can be controlled precisely over a wide range of conditions during periods of a month or more. Moreover, as controlled mechanical deformations can be generated, in situ mechanical characterization tests can be performed without removing specimens from the chamber. Temperature and humidity were controlled during our experiments via a precision temperature regulator and proportional mixing of dry and moisture-saturated air; while highly uniform UV radiation was attained by attaching the chamber to an integrating sphere-based radiation source. A computer-controlled stepper motor and a transmission system were used to provide precise movement control. The reliability and effectiveness of the apparatus were demonstrated on a model sealant material. The results clearly show that this apparatus provides an excellent platform to study the long-term durability of building joint sealants. PMID:24089872

White, C C; Hunston, D L; Tan, K T; Hettenhouser, J; Garver, J D

2013-09-01

207

An accelerated exposure and testing apparatus for building joint sealants  

NASA Astrophysics Data System (ADS)

The design, fabrication, and implementation of a computer-controlled exposure and testing apparatus for building joint sealants are described in this paper. This apparatus is unique in its ability to independently control and monitor temperature, relative humidity, ultraviolet (UV) radiation, and mechanical deformation. Each of these environmental factors can be controlled precisely over a wide range of conditions during periods of a month or more. Moreover, as controlled mechanical deformations can be generated, in situ mechanical characterization tests can be performed without removing specimens from the chamber. Temperature and humidity were controlled during our experiments via a precision temperature regulator and proportional mixing of dry and moisture-saturated air; while highly uniform UV radiation was attained by attaching the chamber to an integrating sphere-based radiation source. A computer-controlled stepper motor and a transmission system were used to provide precise movement control. The reliability and effectiveness of the apparatus were demonstrated on a model sealant material. The results clearly show that this apparatus provides an excellent platform to study the long-term durability of building joint sealants.

White, C. C.; Hunston, D. L.; Tan, K. T.; Hettenhouser, J.; Garver, J. D.

2013-09-01

208

Field Operations Program Chevrolet S-10 (Lead-Acid) Accelerated Reliability Testing - Final Report  

SciTech Connect

This report summarizes the Accelerated Reliability testing of five lead-acid battery-equipped Chevrolet S-10 electric vehicles by the US Department of Energy's Field Operations Program and the Program's testing partners, Electric Transportation Applications (ETA) and Southern California Edison (SCE). ETA and SCE operated the S-10s with the goal of placing 25,000 miles on each vehicle within 1 year, providing an accelerated life-cycle analysis. The testing was performed according to established and published test procedures. The S-10s' average ranges were highest during summer months; changes in ambient temperature from night to day and from season-to-season impacted range by as much as 10 miles. Drivers also noted that excessive use of power during acceleration also had a dramatic effect on vehicle range. The spirited performance of the S-10s created a great temptation to inexperienced electric vehicle drivers to ''have a good time'' and to fully utilize the S-10's acceleration capability. The price of injudicious use of power is greatly reduced range and a long-term reduction in battery life. The range using full-power accelerations followed by rapid deceleration in city driving has been 20 miles or less.

J. Francfort (INEEL); J. Argueta; M. Wehrey (Southern California Edison); D. Karner; L. Tyree (Electric Transportation Applications)

1999-07-01

209

Cycle life of nickel-hydrogen cells. II - Accelerated cycle life test  

NASA Technical Reports Server (NTRS)

A cycle life test of nickel-hydrogen (Ni/H2) cells containing electrolytes of various KOH concentrations and a sintered-type nickel electrode were carried out at 23 C using a 45-min accelerated low earth orbit (LEO) cycle regime at 80 percent depth of discharge. Ten cells containing 21 to 36 percent KOH were tested. Since this accelerated test regime accelerated the cycle life roughly twice as fast as a typical LEO regime, the present results indicate that the cells with 26 percent KOH may last over 5 years in an 80 percent depth-of-discharge cycling in an LEO regime. Cells with lower KOH concentrations (21 to 23.5 percent) also showed longer cycle life than those with KOH concentrations of 31 percent or higher, although the life was shorter than those with 26 percent KOH.

Lim, H. S.; Verzwyvelt, S. A.

1986-01-01

210

Globular Clusters as a Test for Gravity in the Weak Acceleration Regime  

NASA Astrophysics Data System (ADS)

Non-baryonic Dark Matter (DM) appears in galaxies and other cosmic structures when and only when the acceleration of gravity, as computed considering only baryons, goes below a well defined value a0 = 1.2 × 10-8 cm s-2. This fact is extremely important and suggestive of the possibility of a breakdown of Newton's law of gravity (or inertia) below a0. It is therefore important to verify whether Newton's law of gravity holds in this regime of accelerations. In order to do this, one has to study the dynamics of objects that do not contain significant amounts of DM and therefore should follow Newton's prediction for whatever small accelerations. Globular clusters are believed, even by strong supporters of DM, to contain negligible amounts of DM and therefore are ideal for testing Newtonian dynamics in the low acceleration limit. Here, we discuss the status of an ongoing program aimed to do this test. Compared to other studies of globular clsuters, the novelty is that we trace the velocity dispersion profile of globular clusters far enough from the center to probe gravitational accelerations well below a0. In all three clusters studied so far the velocity dispersion is found to remain constant at large radii rather than follow the Keplerian falloff. On average, the flattening occurs at the radius where the cluster internal acceleration of gravity is 1.8 +/- 0.4 × 10-8 cm s-2, fully consistent with MOND predictions.

Scarpa, Riccardo; Marconi, Gianni; Gilmozzi, Roberto

2006-03-01

211

Beam-turning magnet design and test for the Recirculating Linear Accelerator  

SciTech Connect

We have designed and tested a system for applying a ramped vertical magnetic field for turning the electron beam in the IFR Recirculating Linear Accelerator. The field is highly uniform over two Gaussian beam radii, and can be adjusted for a large radial gradient for increased energy bandwidth. The system includes shielding of the current-carrying rods to protect the pulser from REB induced fields and to reduce the effect of REB images on the beam transport to negligible levels. The system has been tested on the IBEX accelerator with > 95% peak current transport and > 90% charge transport through a 90{degree} turn. 2 refs., 6 figs.

Crow, J.T. (Sandia National Labs., Albuquerque, NM (United States)); Platt, R.C. (Science Applications International Corp., San Diego, CA (United States))

1991-01-01

212

Construction and testing of an 11.4 GHz dielectric structure based travelling wave accelerator.  

SciTech Connect

One major challenge in constructing a dielectric loaded traveling wave accelerator powered by an external rf power source is the difficulty in achieving efficient coupling. In this paper, we report that we have achieved high efficiency broadband coupling by using a combination of a tapered dielectric section and a carefully adjusted coupling slot. We are currently constructing an 11.4 GHz accelerator structure loaded with a permitivity=20 dielectric. Bench testing has demonstrated a coupling efficiency in excess of 95% with bandwidth of 600 MHz. The final setup will be tested at high power at SLAC using an X-band klystron rf source.

Gai, W.; Konecny, R.; Wong, T.; Zou, P.

1999-03-26

213

Use of the LEDA Facility as an ADS High-Power Accelerator Test Bed  

SciTech Connect

The Low-Energy Demonstration Accelerator (LEDA) was built to generate high-current proton beams. Its successful full-power operation and testing in 1999-2001 confirmed the feasibility of a high-power linear accelerator (linac) front end, the most technically challenging portion of such a machine. The 6.7-MeV accelerator operates reliably at 95-mA CW beam current with few interruptions orjaults, and qualiJes as one of the most powerful accelerators in the world. LEDA is now available to address the needs of other programs. LEDA can be upgraded in a staged fashion to allow for full-power accelerator demonstrations. The proposed post-h!FQ accelerator structures are 350-MHz superconducting spoke cavities developed for the AAA /APT program. The superconducting portion of the accelerator is designed for a IOO-mA proton beam current. Superconducting cavities were chosen because of the signijkant thermal issues with room-temperature structures, the larger superconducting cavity apertures, and the lower operating costs ('because of improved electrical efficiency) of a superconducting accelerator. Since high reliability is a major issue for an ADS system, the superconducting design architecture alIows operation through faults due to the failure of single magnets or superconducting cavities. The presently installed power capacity of 13 MVA of input ACpower is capable of supporting a 40-MeVproton beam at 100 mA. (The input power is easily expandable to 25 MVA, allowing up to 100-MeV operation). Operation at 40-MeV would provide a complete demonstration of all of the critical accelerator sub-systems ofa full-power ADS system.

Garnett, R. W. (Robert W.); Sheffield, R. L. (Richard L.)

2003-01-01

214

Accelerated durability testing via reactants relative humidity cycling on PEM fuel cells  

Microsoft Academic Search

Cycling of relative humidity (RH) levels in polymer electrolyte membrane (PEM) fuel cells reactant streams have been reported to decay fuel cell performance. This study focuses on accelerated durability testing to examine different modes of membrane failure via relative humidity cycling. A single fuel cell with an active area of 42.25cm2 was tested. A Hydrogenics G50 test station was used

Karachakorn Panha; Michael Fowler; Xiao-Zi Yuan; Haijiang Wang

2012-01-01

215

Testing of vacuum pumps for the Accelerator Production of Tritium/Low Energy Demonstration Accelerator radio frequency quadrupole  

SciTech Connect

Two vacuum systems were designed and built for the RFQ (Radio Frequency Quadrupole) cavity in the APT/LEDA (Low Energy Demonstration Accelerator) linac. The gas load from the proton beam required very high hydrogen pump speed and capacity. The gas load from the high power RF windows also required very high hydrogen pump speed for the RF window vacuum system. Cryopumps were chosen for the RFQ vacuum system and ST185 sintered non-evaporable getter (NEG) cartridges were chosen for the RF window vacuum system. Hydrogen pump speed and capacity measurements were carried out for a commercial cryopump and a NEG pump. This paper will discuss the test procedures and the results of the measurements.

Kishiyama, K.; Shen, S.; Behne, D. [Lawrence Livermore National Lab., CA (United States); Wilson, N.G. [AMPARO Inc., Los Alamos, NM (United States); Schrage, D.; Valdiviez, R. [Los Alamos National Lab., NM (United States)

1998-12-31

216

Plasma Accelerator.  

National Technical Information Service (NTIS)

The accelerator has potential applications in aerodynamic testing, as a source of high-speed plasma for research and as a propulsion system for space vehicles. The accelerator is capable of steady flow operation. The arrangement includes an accelerating c...

G. P. Wood A. F. Carter A. Busemann

1965-01-01

217

Acceleration tests on large salient pole synchronous motors to determine inrush currents and torques methods-interpretation-problems  

Microsoft Academic Search

It is a very tedious and time consuming process to determine torque and current at locked rotor and at various slips during the acceleration test on a synchronous machine. Induction motors and synchronous machines behave similarly during acceleration except that the synchronous machine acceleration can include a pulsation torque. At locked rotor because of the salient poles, there will be

J. H. Dymond; B. Mistry; R. Ong

2000-01-01

218

Beam acceleration test in negative-ion based NBI system for JT-60U  

NASA Astrophysics Data System (ADS)

Beam extraction and acceleration test in the Negative Ion Based Neutral Beam Injector for JT-60U has been started using one ion source that is designed to produce a 500 keV, 22 A D- ion beam. Deuterium negative ions are produced in a cesium-seeded semi-cylindrical plasma generator and accelerated by a multi-aperture three-stage electrostatic accelerator. In the preliminary experiment of beam acceleration, the D- ion beam of 13.5 A was successfully accelerated to 400 keV for a pulse duration of 0.12 s. The negative ion beam power was 5.4 MW. The operating gas pressure in the plasma generator was as low as 0.22 Pa. The highest energy beam of 460 keV, 2.4 A, 0.44 s was also obtained. The ratio of extracted electron current to extracted negative ion current is estimated Ie/ID-<1. It was confirmed that the electron leak from the extractor to the accelerator is suppressed efficiently by the effects of biassing, electron trapping gap and magnetic field.

Watanabe, K.; Akino, N.; Araki, M.; Ebisawa, N.; Fujiwara, Y.; Hanada, M.; Honda, A.; Inoue, T.; Itoh, T.; Kawai, M.; Kazawa, M.; Koizumi, J.; Kuriyama, M.; Miyamoto, K.; Miyamoto, N.; Mogaki, K.; Nagase, A.; Ohara, Y.; Ohga, T.; Okumura, Y.; Oohara, H.; Ohshima, K.; Satoh, F.; Takahashi, S.; Takenouchi, T.; Usami, H.; Usui, K.; Yamamoto, M.; Yamazaki, T.

1996-07-01

219

Beam acceleration test in negative-ion based NBI system for JT-60U  

SciTech Connect

Beam extraction and acceleration test in the Negative Ion Based Neutral Beam Injector for JT-60U has been started using one ion source that is designed to produce a 500 keV, 22 A D{sup {minus}} ion beam. Deuterium negative ions are produced in a cesium-seeded semi-cylindrical plasma generator and accelerated by a multi-aperture three-stage electrostatic accelerator. In the preliminary experiment of beam acceleration, the D{sup {minus}} ion beam of 13.5 A was successfully accelerated to 400 keV for a pulse duration of 0.12 s. The negative ion beam power was 5.4 MW. The operating gas pressure in the plasma generator was as low as 0.22 Pa. The highest energy beam of 460 keV, 2.4 A, 0.44 s was also obtained. The ratio of extracted electron current to extracted negative ion current is estimated Ie/I{sub D{sup {minus}}}{lt}1. It was confirmed that the electron leak from the extractor to the accelerator is suppressed efficiently by the effects of biassing, electron trapping gap and magnetic field. {copyright} {ital 1996 American Institute of Physics.}

Watanabe, K.; Akino, N.; Araki, M.; Ebisawa, N.; Fujiwara, Y.; Hanada, M.; Honda, A.; Inoue, T.; Itoh, T.; Kawai, M.; Kazawa, M.; Koizumi, J.; Kuriyama, M.; Miyamoto, K.; Miyamoto, N.; Mogaki, K.; Nagase, A.; Ohara, Y.; Ohga, T.; Okumura, Y.; Oohara, H.; Ohshima, K.; Satoh, F.; Takahashi, S.; Takenouchi, T.; Usami, H.; Usui, K.; Yamamoto, M.; Yamazaki, T. [Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Ibaraki-ken, 311-01 (Japan)

1996-07-01

220

Design of the in-situ testing system for the accelerated life test of the space infrared device  

NASA Astrophysics Data System (ADS)

Space infrared detector is the core component of photoelectric conversion in the infrared system, the indicator of which, such as sensibility and reliability, limits the optimum performance of the detection system. In the reliability research of infrared detector, the operating life of the device is a very important index and also a significant subject in the engineering application. In the accelerated life test of space infrared detector, it was difficult to periodically measure blackbody response signal of infrared detector, due to equipment limitations for a long time. Accordingly, it was also hard to get abundant failure data of devices for statistical analysis. For this problem, we designed a novel multi-station testing system for accelerated life test of space infrared device, in which response signal as well as temperature can be measured in-situ and recorded for further analysis. Based on theoretical calculation and analysis of actual measured data, we studied and designed the mechanical structure of the equipment and the key component of the testing system, such as the displacement platform, illustrated the control algorithm and put up a system design proposal which meet the testing requirements well. This work technically supports the accelerated life test of space infrared device.

Zhu, Xianliang; Zhang, Haiyan; Wang, Yang; He, Xiangrong; Gong, Haimei

2013-09-01

221

Accelerated Heavy Ion BEAMS from a Test Injector for Negative Ions.  

National Technical Information Service (NTIS)

The construction of an ion source testing device is described which can be used as injector for the Munich MP-tandem accelerators. Studies of the existence of double negative charged ions are described. Uranium ion beams were produced in a sputtering sour...

W. Goldstein

1980-01-01

222

Degradation in silicon solar cells caused by the formation of Schottky barrier contacts during accelerated testing  

Microsoft Academic Search

When p+\\/n silicon solar cells having a lightly doped substrate, i.e. no back surface field, were subjected to accelerated stress testing an irregularity occurred in the VI characteristic along with the resulting loss of power output. Evidence is presented which indicates that this is due to formation of a rectifying Schottky barrier between the back metal contact and the silicon,

J. W. Lathrop; C. W. Davis; K. Misiakos

1984-01-01

223

Lifetime Prediction for Degradation of Solar Mirrors using Step-Stress Accelerated Testing (Presentation)  

SciTech Connect

This research is to illustrate the use of statistical inference techniques in order to quantify the uncertainty surrounding reliability estimates in a step-stress accelerated degradation testing (SSADT) scenario. SSADT can be used when a researcher is faced with a resource-constrained environment, e.g., limits on chamber time or on the number of units to test. We apply the SSADT methodology to a degradation experiment involving concentrated solar power (CSP) mirrors and compare the results to a more traditional multiple accelerated testing paradigm. Specifically, our work includes: (1) designing a durability testing plan for solar mirrors (3M's new improved silvered acrylic "Solar Reflector Film (SFM) 1100") through the ultra-accelerated weathering system (UAWS), (2) defining degradation paths of optical performance based on the SSADT model which is accelerated by high UV-radiant exposure, and (3) developing service lifetime prediction models for solar mirrors using advanced statistical inference. We use the method of least squares to estimate the model parameters and this serves as the basis for the statistical inference in SSADT. Several quantities of interest can be estimated from this procedure, e.g., mean-time-to-failure (MTTF) and warranty time. The methods allow for the estimation of quantities that may be of interest to the domain scientists.

Lee, J.; Elmore, R.; Kennedy, C.; Gray, M.; Jones, W.

2011-09-01

224

Improved tests reveal that the accelerating moment release hypothesis is statistically insignificant  

Microsoft Academic Search

We test the hypothesis that accelerating moment release (AMR) is a precursor to large earthquakes, using data from California, Nevada, and Sumatra. Spurious cases of AMR can arise from data fitting because the time period, area, and sometimes magnitude range analyzed before each main shock are often optimized to produce the strongest AMR signal. Optimizing the search criteria can identify

Jeanne L. Hardebeck; Karen R. Felzer; Andrew J. Michael

2008-01-01

225

A research on the overall unit accelerated storage test method for aerospace products  

Microsoft Academic Search

Based on the transformation method, this paper proposes a method of overall unit accelerated storage test with time synchronization. We have done engineering practices on certain pyrotechnics device with this method, and forecasted the storage life of this certain pyrotechnics device.

Gehong Song; Ting Liu; Shumei Chen

2009-01-01

226

An Accelerated Test Method for Predicting the Useful Life of an LED Driver  

Microsoft Academic Search

This paper proposes an accelerated life-test method for LED drivers that use electrolytic capacitors at the output stage. The type of failure considered here is parametric. Estimated failure rates of power components suggest the electrolytic capacitor used at the driver output stage is the weakest link. As an electrolytic capacitor degrades, its capacitance decreases and its equivalent series resistance increases,

Lei Han; Nadarajah Narendran

2011-01-01

227

Results of metallographical diagnostic examination of Navy half-watt thermoelectric converters degraded by accelerated tests  

NASA Technical Reports Server (NTRS)

To verify the 15-year reliability of the Navy half-watt radioisotope thermoelectric generator (RTG), bismuth-telluride thermoelectric converters were submitted to testing at high temperatures which accelerated the degradation and caused failure of the converters. Metallographic diagnostic examination of failed units verified failure mechanisms. Results of diagnostic examinations are presented.

Rosell, F. E., Jr.; Rouklove, P. G.

1977-01-01

228

A statistical treatment of accelerated life test data for copper-water heat pipes  

Microsoft Academic Search

A statistical method is proposed to treat accelerated life test data conducted at several elevated temperatures for a sufficient number of commercially available Cu-water heat pipes to predict the operation life. The temperature distribution measurements periodically carried out yield both data sets concerning the temperature drop and the gas column length as measures of noncondensible gas accumulation. The gas analysis

M. Murakami; K. Arai; Y. Kojima

1988-01-01

229

About tests of collapse models and Bell inequalities at accelerator facilities  

NASA Astrophysics Data System (ADS)

This contribution summarizes some ideas how foundations of quantum theory can be tested with systems in high energy physics, i.e. those produced at accelerator facilities. In particular, we focus on Bell inequalities and collapse models for then neutral kaon system and enlighten the insights into the quantum theory that do not show up for systems at low energies.

Hiesmayr, Beatrix; Tyc, Tomas

2012-12-01

230

Accelerated aging tests for evaluations of durability performance of FRP reinforcing bars for concrete structures  

Microsoft Academic Search

This paper presents accelerated aging test results of a durability study on fiber-reinforced polymer (FRP) reinforcing bars for concrete structures. Bare FRP bars and also bars embedded in concrete, primarily for glass composites, were exposed to five different solutions: water, two types of simulated alkaline pore solutions of normal and high performance concrete, saline solution, and combined alkaline solution with

Yi Chen; Julio F. Davalos; Indrajit Ray; Hyeong-Yeol Kim

2007-01-01

231

Accelerated in vitro release testing of implantable PLGA microsphere/PVA hydrogel composite coatings.  

PubMed

Dexamethasone loaded poly(lactic-co-glycolic acid) (PLGA) microsphere/PVA hydrogel composites have been investigated as an outer drug-eluting coating for implantable devices such as glucose sensors to counter negative tissue responses to implants. The objective of this study was to develop a discriminatory, accelerated in vitro release testing method for this drug-eluting coating using United States Pharmacopeia (USP) apparatus 4. Polymer degradation and drug release kinetics were investigated under "real-time" and accelerated conditions (i.e. extreme pH, hydro-alcoholic solutions and elevated temperatures). Compared to "real-time" conditions, the initial burst and lag phases were similar using hydro-alcoholic solutions and extreme pH conditions, while the secondary apparent zero-order release phase was slightly accelerated. Elevated temperatures resulted in a significant acceleration of dexamethasone release. The accelerated release data were able to predict "real-time" release when applying the Arrhenius equation. Microsphere batches with faster and slower release profiles were investigated under "real-time" and elevated temperature (60°C) conditions to determine the discriminatory ability of the method. The results demonstrated both the feasibility and the discriminatory ability of this USP apparatus 4 method for in vitro release testing of drug loaded PLGA microsphere/PVA hydrogel composites. This method may be appropriate for similar drug/device combination products and drug delivery systems. PMID:22016033

Shen, Jie; Burgess, Diane J

2012-01-17

232

Testing of large area drift chambers at the Saskatchewan Accelerator Laboratory for High Energy Astrophysics  

Microsoft Academic Search

Large area (0.5 m×0.5 m) drift chambers developed for the imaging system for the Advanced Gamma Ray Astronomy Telescope Experiment (AGATE), sensitive in the energy range 20 MeV to 100 GeV, have been tested at the Saskatchewan Accelerator Laboratory (SAL) in March 1995. Testing was performed with the instrument configured in 3 different angles relative to the incident photon beam

R. Cuddapah; D. L. Bertsch; J. R. Catelli; B. L. Dingus; J. A. Esposito; C. E. Fichtel; R. C. Hartman; S. D. Hunter; R. Mukherjee; D. J. Thompson; J. M. Vogt

1995-01-01

233

Effects of accelerated testing on porcine bioprosthetic heart valve fiber architecture  

Microsoft Academic Search

We undertook the following study to quantitatively assess the changes in porcine bioprosthetic heart valve (PBHV) fiber architecture to increasing levels of fatigue damage using an in vitro accelerated test model. PBHVs were subjected to 0–500 million test cycles at 16Hz, and small-angle light scattering (SALS) was used to quantify the gross fiber structure of the cusps. The degree of

Michael S. Sacks; David B. Smith

1998-01-01

234

Accelerator driven gamma and fast neutron radiography test-bed at Lawrence Livermore National Laboratory  

NASA Astrophysics Data System (ADS)

Accelerator driven fusion gammas and fast neutrons could provide unique radiography capabilities due to their ability to produce both high and low energy mono-energetic gammas and neutrons compared with broadband bremsstrahlung based x-ray sources. The possibility of simultaneously obtaining both gamma and neutron radiographs using one source could allow complex objects composed of a large range of low to high Z materials to be imaged. In this paper we review a 4 MV RFQ accelerator driven radiography test-bed at LLNL designed to study the physics involved in applying these dual output fusion reactions for radiography applications. First experimental neutron images from a carbon target are presented.

Tang, V.; Rusnak, B.; Falabella, S.; Hawkins, S.; McCarrick, J. F.; Wang, H.; Hall, J. M.; Ellsworth, J.

2013-04-01

235

Electron spin resonance spectral study of PVC and XLPE insulation materials and their life time analysis.  

PubMed

Electron spin resonance (ESR) study is carried out to characterize thermal endurance of insulating materials used in power cable industry. The presented work provides ESR investigation and evaluation of widely used cable insulation materials, namely polyvinyl chloride (PVC) and cross-linked polyethylene (XLPE). The results confirm the fact that PVC is rapidly degrades than XLPE. The study also indicates that colorants and cable's manufacturing processes enhance the thermal resistance of the PVC. It also verifies the powerfulness and the importance of the ESR-testing of insulation materials compared to other tests assumed by International Electrotechnical Commission (IEC) Standard 216-procedure, e.g. weight loss (WL), electric strength (ES) or tensile strength (TS). The estimated thermal endurance parameters by ESR-method show that the other standard methods overestimate these parameters and produce less accurate thermal life time curves of cable insulation materials. PMID:16024271

Morsy, M A; Shwehdi, M H

2006-03-01

236

Electron spin resonance spectral study of PVC and XLPE insulation materials and their life time analysis  

NASA Astrophysics Data System (ADS)

Electron spin resonance (ESR) study is carried out to characterize thermal endurance of insulating materials used in power cable industry. The presented work provides ESR investigation and evaluation of widely used cable insulation materials, namely polyvinyl chloride (PVC) and cross-linked polyethylene (XLPE). The results confirm the fact that PVC is rapidly degrades than XLPE. The study also indicates that colorants and cable's manufacturing processes enhance the thermal resistance of the PVC. It also verifies the powerfulness and the importance of the ESR-testing of insulation materials compared to other tests assumed by International Electrotechnical Commission (IEC) Standard 216-procedure, e.g. weight loss (WL), electric strength (ES) or tensile strength (TS). The estimated thermal endurance parameters by ESR-method show that the other standard methods overestimate these parameters and produce less accurate thermal life time curves of cable insulation materials.

Morsy, M. A.; Shwehdi, M. H.

2006-03-01

237

Ground Test of the Urine Processing Assembly for Accelerations and Transfer Functions  

NASA Technical Reports Server (NTRS)

This viewgraph presentation gives an overview of the ground test of the urine processing assembly for accelerations and transfer functions. Details are given on the test setup, test data, data analysis, analytical results, and microgravity assessment. The conclusions of the tests include the following: (1) the single input/multiple output method is useful if the data is acquired by tri-axial accelerometers and inputs can be considered uncorrelated; (2) tying coherence with the matrix yields higher confidence in results; (3) the WRS#2 rack ORUs need to be isolated; (4) and future work includes a plan for characterizing performance of isolation materials.

Houston, Janice; Almond, Deborah F. (Technical Monitor)

2001-01-01

238

Technology evaluation of man-rated acceleration test equipment for vestibular research  

NASA Technical Reports Server (NTRS)

The considerations for eliminating acceleration noise cues in horizontal, linear, cyclic-motion sleds intended for both ground and shuttle-flight applications are addressed. the principal concerns are the acceleration transients associated with change in direction-of-motion for the carriage. The study presents a design limit for acceleration cues or transients based upon published measurements for thresholds of human perception to linear cyclic motion. The sources and levels for motion transients are presented based upon measurements obtained from existing sled systems. The approaches to a noise-free system recommends the use of air bearings for the carriage support and moving-coil linear induction motors operating at low frequency as the drive system. Metal belts running on air bearing pulleys provide an alternate approach to the driving system. The appendix presents a discussion of alternate testing techniques intended to provide preliminary type data by means of pendulums, linear motion devices and commercial air bearing tables.

Taback, I.; Kenimer, R. L.; Butterfield, A. J.

1983-01-01

239

Electron cloud dynamics in the Cornell Electron Storage Ring Test Accelerator wiggler  

NASA Astrophysics Data System (ADS)

The interference of stray electrons (also called “electron clouds”) with accelerator beams is important in modern intense-beam accelerators, especially those with beams of positive charge. In magnetic wigglers, used, for instance, for transverse emittance damping, the intense synchrotron radiation produced by the beam can generate an electron cloud of relatively high density. In this paper the complicated dynamics of electron clouds in wigglers is examined using the example of a wiggler in the Cornell Electron Storage Ring Test Accelerator experiment at the Cornell Electron Storage Ring. Three-dimensional particle-in-cell simulations with the WARP-POSINST computer code show different density and dynamics for the electron cloud at locations near the maxima of the vertical wiggler field when compared to locations near the minima. Dynamics in these regions, the electron cloud distribution vs longitudinal position, and the beam coherent tune shift caused by the wiggler electron cloud will be discussed.

Celata, C. M.

2011-04-01

240

Demonstration of two-beam acceleration and 30 GHz power production in the CLIC Test Facility  

NASA Astrophysics Data System (ADS)

The Compact Linear Collider (CLIC) Test Facility (CTF II) at CERN has recently demonstrated Two-Beam power production and acceleration at 30 GHz. With 41 MW of 30 GHz power produced in 14 ns pulses at a repetition rate of 5 Hz, the main beam has been accelerated by 28 MeV. The 30 GHz RF power is extracted in low impedance decelerating structures from a low-energy, high-current ``drive beam'' which runs parallel to the main beam. The average current in the drive-beam train is 25 A, while the peak current exceeds 2 kA. Crosschecks between measured drive-beam charge, 30 GHz power and main-beam energy gain are in good agreement. In this paper, some relevant experimental and technical issues on drive-beam generation, two-beam power production and acceleration are presented.

Bossart, R.; Braun, H. H.; Carron, G.; Chanudet, M.; Chautard, F.; Delahaye, J. P.; Godot, J. C.; Hutchins, S.; Martinez, C.; Suberlucq, G.; Tenenbaum, P.; Thorndahl, L.; Trautner, H.; Valentini, M.; Wilson, I.; Wuensch, W.

1999-05-01

241

Facility for Advanced Accelerator Experimental Tests (FACET) at SLAC and its Radiological Considerations  

SciTech Connect

Facility for Advanced Accelerator Experimental Tests (FACET) in SLAC will be used to study plasma wakefield acceleration. FLUKA Monte Carlo code was used to design a maze wall to separate FACET project and LCLS project to allow persons working in FACET side during LCLS operation. Also FLUKA Monte Carlo code was used to design the shielding for FACET dump to get optimum design for shielding both prompt and residual doses, as well as reducing environmental impact. FACET will be an experimental facility that provides short, intense pulses of electrons and positrons to excite plasma wakefields and study a variety of critical issues associated with plasma wakefield acceleration [1]. This paper describes the FACET beam parameters, the lay-out and its radiological issues.

Mao, X.S.; Leitner, M.Santana; Vollaire, J.

2011-08-22

242

Accelerated test techniques for micro-circuits: Evaluation of high temperature (473 k - 573 K) accelerated life test techniques as effective microcircuit screening methods  

NASA Technical Reports Server (NTRS)

The application of high temperature accelerated test techniques was shown to be an effective method of microcircuit defect screening. Comprehensive microcircuit evaluations and a series of high temperature (473 K to 573 K) life tests demonstrated that a freak or early failure population of surface contaminated devices could be completely screened in thirty two hours of test at an ambient temperature of 523 K. Equivalent screening at 398 K, as prescribed by current Military and NASA specifications, would have required in excess of 1,500 hours of test. All testing was accomplished with a Texas Instruments' 54L10, low power triple-3 input NAND gate manufactured with a titanium- tungsten (Ti-W), Gold (Au) metallization system. A number of design and/or manufacturing anomalies were also noted with the Ti-W, Au metallization system. Further study of the exact nature and cause(s) of these anomalies is recommended prior to the use of microcircuits with Ti-W, Au metallization in long life/high reliability applications. Photomicrographs of tested circuits are included.

Johnson, G. M.

1976-01-01

243

New Accelerated Testing and Lifetime Modeling Methods Promise Faster Development of More Durable MEAs  

SciTech Connect

For the successful commercialization of fuel cell technology, it is imperative that membrane electrode assembly (MEA) durability is understood and quantified. MEA lifetimes of 40,000 hours remain a key target for stationary power applications. Since it is impractical to wait 40,000 hours for durability results, it is critical to learn as much information as possible in as short a time period as possible to determine if an MEA sample will survive past its lifetime target. Consequently, 3M has utilized accelerated testing and statistical lifetime modeling tools to develop a methodology for evaluating MEA lifetime. Construction and implementation of a multi-cell test stand have allowed for multiple accelerated tests and stronger statistical data for learning about durability.

Pierpont, D. M.; Hicks, M. T.; Turner, P. L.; Watschke, T. M.

2005-11-01

244

Implications for the establishment of accelerated fatigue test protocols for prosthetic heart valves.  

PubMed

The goal of this research is to establish a reliable methodology for accelerated fatigue tests of prosthetic heart valves. A polymer valve was the subject, and the influence of various drive parameters on durability was investigated in three different machines. Valve lifetime was notably shortened by increasing the cyclic rate or stroke even though the maximum pressure difference at valve closure was maintained at 120 mm Hg. These results demonstrate that adjustment of the maximum transvalvular pressure is not sufficient to ensure tests are conducted under the same conditions and indicate that measurement of the dynamic load would be more efficacious. Moreover, the locations of tears sustained in the accelerated tests differed from those encountered in an animal experiment although in both cases the locations were entirely consistent with the areas of strain concentration revealed by finite element analysis. These findings should be discussed during a revision of ISO 5840. PMID:12000438

Iwasaki, Kiyotaka; Umezu, Mitsuo; Iijima, Kazuo; Imachi, Kou

2002-05-01

245

Bayesian Analysis of Step-Stress Accelerated Life Test with Exponential Distribution  

SciTech Connect

In this article, we propose a general Bayesian inference approach to the step-stress accelerated life test with type II censoring. We assume that the failure times at each stress level are exponentially distributed and the test units are tested in an increasing order of stress levels. We formulate the prior distribution of the parameters of life-stress function and integrate the engineering knowledge of product failure rate and acceleration factor into the prior. The posterior distribution and the point estimates for the parameters of interest are provided. Through the Markov chain Monte Carlo technique, we demonstrate a nonconjugate prior case using an industrial example. It is shown that with the Bayesian approach, the statistical precision of parameter estimation is improved and, consequently, the required number of failures could be reduced.

Lee, J.; Pan, R.

2012-04-01

246

Inter-laboratory comparison of UV-light sources for accelerated durability testing of PV modules  

NASA Astrophysics Data System (ADS)

Accelerated testing of the durability of materials exposed to natural weathering requires testing of the UV stability, especially for polymeric materials. The type approval testing of PV-modules according to the standards IEC 61215 and IEC 61646 includes a so-called UV-preconditioning test with a total UV dose of 15 kWh/m2. Fraunhofer ISE performed an Inter-laboratory comparison of UV-light sources in accredited test labs and in test centres of major PV module manufacturers. One topic was the spectral measurement of the used UV sources. Another main issue was the comparison of the integral measurements by the sensors used for control of the tests. Errors up to 120% were found.

Philipp, Daniel; Weiss, Karl-Anders; Koehl, Michael

2011-09-01

247

Status of the ETA-II (Experimental Test Accelerator II) linear induction accelerator: High brightness results. Revised.  

National Technical Information Service (NTIS)

A two-aperture collimator has been used to measure brightness of the electron beam produced by the injector and the first 20 acceleration cells of the ETA-II linear induction accelerator. Osmium alloy dispenser cathodes produce the electron beam. For acce...

W. C. Turner J. K. Boyd J. C. Clark W. E. Nexsen

1989-01-01

248

Advanced X-Band Test Accelerator for High Brightness Electron and Gamma Ray Beams  

SciTech Connect

In support of Compton scattering gamma-ray source efforts at LLNL, a multi-bunch test stand is being developed to investigate accelerator optimization for future upgrades. This test stand will enable work to explore the science and technology paths required to boost the current 10 Hz monoenergetic gamma-ray (MEGa-Ray) technology to an effective repetition rate exceeding 1 kHz, potentially increasing the average gamma-ray brightness by two orders of magnitude. Multiple bunches must be of exceedingly high quality to produce narrow-bandwidth gamma-rays. Modeling efforts will be presented, along with plans for a multi-bunch test stand at LLNL. The test stand will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. The photoinjector will be a high gradient standing wave structure, featuring a dual feed racetrack coupler. The accelerator will increase the electron energy so that the emittance can be measured using quadrupole scanning techniques. Multi-bunch diagnostics will be developed so that the beam quality can be measured and compared with theory. Design will be presented with modeling simulations, and layout plans.

Marsh, Roark; /LLNL, Livermore; Anderson, Scott; /LLNL, Livermore; Barty, Christopher; /LLNL, Livermore; Chu, Tak Sum; /LLNL, Livermore; Ebbers, Chris; /LLNL, Livermore; Gibson, David; /LLNL, Livermore; Hartemann, Fred; /LLNL, Livermore; Adolphsen, Chris; /SLAC; Jongewaard, Erik; /SLAC; Raubenheimer, Tor; /SLAC; Tantawi, Sami; /SLAC; Vlieks, Arnold; /SLAC; Wang, Juwen; /SLAC

2012-07-03

249

ADVANCED X-BAND TEST ACCELERATOR FOR HIGH BRIGHTNESS ELECTRON AND GAMMA RAY BEAMS  

SciTech Connect

In support of Compton scattering gamma-ray source efforts at LLNL, a multi-bunch test stand is being developed to investigate accelerator optimization for future upgrades. This test stand will enable work to explore the science and technology paths required to boost the current 10 Hz monoenergetic gamma-ray (MEGa-Ray) technology to an effective repetition rate exceeding 1 kHz, potentially increasing the average gamma-ray brightness by two orders of magnitude. Multiple bunches must be of exceedingly high quality to produce narrow-bandwidth gamma-rays. Modeling efforts will be presented, along with plans for a multi-bunch test stand at LLNL. The test stand will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. The photoinjector will be a high gradient standing wave structure, featuring a dual feed racetrack coupler. The accelerator will increase the electron energy so that the emittance can be measured using quadrupole scanning techniques. Multi-bunch diagnostics will be developed so that the beam quality can be measured and compared with theory. Design will be presented with modeling simulations, and layout plans.

Marsh, R A; Anderson, S G; Barty, C P; Chu, T S; Ebbers, C A; Gibson, D J; Hartemann, F V; Adolphsen, C; Jongewaard, E N; Raubenheimer, T; Tantawi, S G; Vlieks, A E; Wang, J W

2010-05-12

250

LLRF and timing system for the SCSS test accelerator at SPring-8  

NASA Astrophysics Data System (ADS)

The 250 MeV SCSS test accelerator as an extreme-ultra violet (EUV) laser source has been built at SPring-8. The accelerator comprises a 500 kV thermionic gun, a velocity bunching system using multi-sub-harmonic bunchers (SHB) in an injector and a magnetic bunch compressor using a chicane of 4 bending magnets, a 5712 MHz main accelerator to accelerate an electron beam up to 250 MeV, and undulators to radiate the EUV laser. These bunch compression processes make short bunched electrons with a 300 A peak current and a 300 fs pulse width. The pulse width and peak current of an electron beam, which strongly affect the pulse width and intensity of the laser light, are mainly decided by the pulse compression ratio of the velocity bunching and the magnetic bunch compressing processes. The compression ratio is also determined due to an energy chirp along the beam bunch generated by an off-crest rf field at the SHB and cavities before the chicane. To constantly keep the beam pulse-width conducted by rf and timing signals, which are temporally controlled within subpicoseconds of the designed value, the low-level rf and timing system of the test accelerator has been developed. The system comprises a very low-noise and temporally stable reference signal source, in-phase and quadrature (IQ) modulators and demodulators, as well as VME type 12 bits analog-to-digital and digital-to-analog converter modules to manipulate an rf phase and amplitude by IQ functions for the cavity. We achieved that the SSB noise of the 5712 MHz reference signal source was less than -120 dBc/Hz at 1 kHz offset from the reference frequency; the phase setting and detecting resolution of the IQ-modulators and demodulators were within +/-0.5° at 5712 MHz. A master trigger VME module and a trigger delay VME module were also developed to activate the components of the test accelerator. The time jitter of the delay module was less than 0.7 ps, sufficient for our present requirement. As a result, a beam energy variation of 0.06% was achieved and a time jitter of 46 fs between the acceleration rf signal and the beam was realized.

Otake, Yuji; Ohshima, Takashi; Hosoda, Naoyasu; Maesaka, Hirokazu; Fukui, Toru; Kitamura, Masanobu; Shintake, Tsumoru

2012-12-01

251

Possibilities of SSC device testing at the Serpukhov 70-GeV accelerator  

SciTech Connect

The possibilities for the testing and measurement of different physical facilities related to the Superconducting Super Collider (SSC) are considered. The Institute for High Energy Physics (IHEP) accelerator complex at Serpukhov, Russia, is described, and technical parameters are presented. Generally, the beam extraction and beam line systems are described because both systems constitute the environment in which the physicist finds himself, and most often these systems define the final possibilities of experimental set-up for a fixed-target run. Three groups of SSC problems may be examined at the existing 70-GeV accelerator at IHEP: the study of radiation resistance of various devices, the study of beam monitor performances, and the testing and investigation of modules of collider detectors.

Cherny, S.

1992-09-01

252

600 kV Modulator Design for the SLAG Next Linear Collider Test Accelerator  

Microsoft Academic Search

Preliminary design for the SLAC Next Linear Collider Test Accelerator (NLCTA) requires a pulse power source to produce a 600 kV, 600 A, 1.4 μs, 0.1% flat top pulse with rise and fall times of approximately 100 ns to power an X-Band klystron with a microperveance of 1.25 at â 100 MW peak RF power. The design goals for the

K. Harris; J. deLamare; V. Nesterov; R. Cassel

1992-01-01

253

Prediction of storage life of hydraulic oils on the basis of accelerated climatic tests  

SciTech Connect

On the basis of changes in physicochemical characteristics of hydraulic oil (kinematic viscosity, solid point, refractive index, density) under the influence of conditions of accelerated climatic tests (ACTs), it is impossible to judge the changes of oil composition with any degree of reliability. Of the components of hydraulic oil, the most sensitive to the combined action of temperature, moisture, and various metals are the aromatic hydrocarbons, oxygen-containing compounds, and the antioxidant diphenylamine.

Lovzin, E.V.; Polyakova, A.A.; Semanyuk, R.N.; Fal`kovskaya, O.I.; Shabalina, T.N.; Tyshchenko, V.A.; Kalinina, L.D.

1994-09-01

254

Update on Reciprocity Effects for Accelerated Ozone Fade Testing of Inkjet Photographic Prints  

Microsoft Academic Search

Inkjet photographic prints, especially those printed with dye-based inks on po- rous media, are subject to rapid dye fad- ing when exposed to ambient levels of ozone. The rate of fade is much slower with dye-based inks on swellable media and, in general, with pigment-based inks. As part of an ongoing effort to establish a standardized test method to accelerate

Douglas Bugner; Richard Van Hanehem; Peter Artz; Daniel Zaccour

2003-01-01

255

Dissimilar-weld failure analysis and development program: Volume 3, Accelerated discriminatory tests: Final report  

Microsoft Academic Search

This volume of the report on research project RP1874 describes the results of studies to develop an accelerated discriminatory test for evaluation of dissimilar metal welds (DMWs) typical of those found in boiler superheater and reheater tubing. The weldments of interest are generally those between 2-1\\/4 Cr - 1 Mo low-alloy steel and 300-series stainless steel, including those made by

Prager

1986-01-01

256

Accelerated Stress Testing of SiC MEMS-DCA Pressure Transducers  

Microsoft Academic Search

Preliminary accelerated stress tests (AST) have been performed on 6H-SiC pn-junction piezoresistive pressure transducers that were packaged by Microelectromechanical Systems Direct Chip Attach (MEMS-DCA) process for the purpose of evaluating their long-term operational stability and reliability under cyclic pressure and temperature. Finite element analysis (FEA) was used to understand the stress distribution at critical sensor\\/Aluminum nitride (AlN) header and AlN

Ender Savrun; Vu Nguyen; Robert Okojie; Charles Blaha

2004-01-01

257

Accelerated Exposure Tests of Encapsulated Si Solar Cells and Encapsulation Materials  

Microsoft Academic Search

We have conducted a series of accelerated exposure test (AET) studies for various crystalline-Si (c-Si) and amorphous-Si (a-Si) cell samples that were encapsulated with different superstrates, pottants, and substrates. Nonuniform browning patterns of ethylene vinyl acetate (EVA) pottants were observed for glass\\/EVA\\/glass-encapsulated c-Si cell samples under solar simulator exposures at elevated temperatures. The polymer\\/polymer-configured laminates with Tedlar or Tefzel did

F. J. Pern; S. H. Glick

1998-01-01

258

Accelerated exposure tests of encapsulated Si solar cells and encapsulation materials  

Microsoft Academic Search

We have conducted a series of accelerated exposure test (AET) studies for various crystalline-Si (c-Si) and amorphous-Si (a-Si) cell samples that were encapsulated with different superstrates, pottants, and substrates. Nonuniform browning patterns of ethylene vinyl acetate (EVA) pottants were observed for glass\\/EVA\\/glass-encapsulated c-Si cell samples under solar simulator exposures at elevated temperatures. The polymer\\/polymer-configured laminates with Tedlar or Tefzel did

F. J. Pern; S. H. Glick

1999-01-01

259

Repeatable electrical measurement instrumentation for use in the accelerated stress testing of thin film solar cells  

NASA Technical Reports Server (NTRS)

Attention is given to the construction, calibration, and performance of a repeatable measurement system for use in conjunction with the accelerated stress testing of a-Si:H cells. A filtered diode array is utilized to approximate the spectral response of any type of solar cell in discrete portions of the spectrum. It is noted that in order to achieve the necessary degree of overall repeatability, it is necessary to pay particular attention to methods of contacting and positioning the cells.

Davis, C. W.; Lathrop, J. W.

1985-01-01

260

Reliability test of an electron cyclotron resonance ion source for accelerator driven sub-critical system  

SciTech Connect

The reliability test of an electron cyclotron resonance ion source developed for accelerator driven sub-critical system is carried out in China Institute of Atomic Energy. A unique technique to improve the reliability is adopted. The source is operated for more than 200 h at 75 keV, 100 mA extracted hydrogen current, while 2 beam trips are recorded in the period, and uninterrupted operation time is about 150 h. The experimental result is described.

Cui, B.; Tang, B.; Ma, R.; Huang, Q.; Ma, Y.; Chen, L.; Jiang, W. [China Institute of Atomic Energy, P. O. Box 275(27), Beijing 102413 (China)

2012-02-15

261

Accelerated Testing for Long-term Durability of FRP Laminates for Marine Use  

Microsoft Academic Search

The accelerated testing methodology has been proposed for the long-term durability of polymer composites based on the time–temperature superposition principle to be held for the viscoelasticity of polymer matrix. In this paper, the long-term flexural fatigue life of plain woven carbon fiber–vinylester (CFRP) laminates for advanced marine use was predicted based on the proposed methodology, compared with that of plain

Yasushi Miyano; Masayuki Nakada; Naoyuki Sekine

2005-01-01

262

Accelerated testing for long-term durability of GFRP laminates for marine use  

Microsoft Academic Search

Our proposed accelerated testing methodology for the long term durability of polymer composites is based on the time–temperature superposition principle to be held for the viscoelasticity of polymer matrix. The long term flexural fatigue life of plain woven glass fiber\\/vinyl-ester (GFRP) laminates for conventional marine use was predicted based on the proposed methodology. As results, the flexural fatigue strengths of

Yasushi Miyano; Masayuki Nakada; Naoyuki Sekine

2004-01-01

263

Accelerated Testing for Long-Term Durability of Various FRP Laminates for Marine Use  

Microsoft Academic Search

\\u000a The prediction of long-term fatigue life of various FRP laminates combined with resins, fibers and fabrics for marine use\\u000a under temperature and water environments were performed by our developed accelerated testing methodology based on the time-temperature\\u000a superposition principle (TTSP). The base material of five kinds of FRP laminates employed in this study was plain fabric CFRP\\u000a laminates T300 carbon fibers\\/vinylester

Yasushi Miyano; Masayuki Nakada

2009-01-01

264

Test results of the proton injector of the Proton Engineering Frontier Project accelerator  

NASA Astrophysics Data System (ADS)

One of the goals of the Proton Engineering Frontier Project (PEFP) is to develop a 100 MeV proton accelerator. As a low energy part, a 20 MeV proton linac has been developed and tested. The 20 MeV accelerator consists of a 50 keV proton injector, a 3 MeV radio frequency quadrupole, and a 20 MeV drift tube linac. The proton injector includes a duoplasmatron type ion source and a low energy beam transport. After a preliminary test with 1 mA peak current of the 20 MeV accelerator, the proton injector was modified with the goal of increasing the 20 MeV beam current up to 20 mA peak value. The modifications include the reduction of the proton injector length, installation of a beam current monitor, and electron trap and supplement of the solenoid and steering magnets. In this paper, the modifications of the PEFP proton injector are described and initial test results are presented.

Kwon, Hyeok-Jung; Kim, Han-Sung; Cho, Yong-Sub

2008-02-01

265

Test results of the proton injector of the Proton Engineering Frontier Project accelerator  

SciTech Connect

One of the goals of the Proton Engineering Frontier Project (PEFP) is to develop a 100 MeV proton accelerator. As a low energy part, a 20 MeV proton linac has been developed and tested. The 20 MeV accelerator consists of a 50 keV proton injector, a 3 MeV radio frequency quadrupole, and a 20 MeV drift tube linac. The proton injector includes a duoplasmatron type ion source and a low energy beam transport. After a preliminary test with 1 mA peak current of the 20 MeV accelerator, the proton injector was modified with the goal of increasing the 20 MeV beam current up to 20 mA peak value. The modifications include the reduction of the proton injector length, installation of a beam current monitor, and electron trap and supplement of the solenoid and steering magnets. In this paper, the modifications of the PEFP proton injector are described and initial test results are presented.

Kwon, Hyeok-Jung; Kim, Han-Sung; Cho, Yong-Sub [Proton Engineering Frontier Project, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of)

2008-02-15

266

Test results of the proton injector of the Proton Engineering Frontier Project accelerator.  

PubMed

One of the goals of the Proton Engineering Frontier Project (PEFP) is to develop a 100 MeV proton accelerator. As a low energy part, a 20 MeV proton linac has been developed and tested. The 20 MeV accelerator consists of a 50 keV proton injector, a 3 MeV radio frequency quadrupole, and a 20 MeV drift tube linac. The proton injector includes a duoplasmatron type ion source and a low energy beam transport. After a preliminary test with 1 mA peak current of the 20 MeV accelerator, the proton injector was modified with the goal of increasing the 20 MeV beam current up to 20 mA peak value. The modifications include the reduction of the proton injector length, installation of a beam current monitor, and electron trap and supplement of the solenoid and steering magnets. In this paper, the modifications of the PEFP proton injector are described and initial test results are presented. PMID:18315260

Kwon, Hyeok-Jung; Kim, Han-Sung; Cho, Yong-Sub

2008-02-01

267

Closeout Report for the Refractory Metal Accelerated Heat Pipe Life Test Activity  

NASA Technical Reports Server (NTRS)

With the selection of a gas-cooled reactor, this heat pipe accelerated life test activity was closed out and its resources redirected. The scope of this project was to establish the long-term aging effects on Mo-44.5%Re sodium heat pipes when subjected to space reactor temperature and mass fluences. To date, investigators have demonstrated heat pipe life tests of alkali metal systems up to .50,000 hours. Unfortunately, resources have not been available to examine the effect of temperature, mass fluence, or impurity level on corrosion or to conduct post-test forensic examination of heat pipes. The key objective of this effort was to establish a cost/time effective method to systematically test alkali metal heat pipes with both practical and theoretical benefits. During execution of the project, a heat pipe design was established, a majority of the laboratory test equipment systems specified, and operating and test procedures developed. Procurements for the heat pipe units and all major test components were underway at the time the stop work order was issued. An extremely important outcome was the successful fabrication of an annular wick from Mo-5%Re screen (the single, most difficult component to manufacture) using a hot isostatic pressing technique. This Technical Publication (TP) includes specifics regarding the heat pipe calorimeter water-cooling system, vendor design for the radio frequency heating system, possible alternative calorimeter designs, and progress on the vanadium equilibration technique. The methods provided in this TP and preceding project documentation would serve as a good starting point to rapidly implement an accelerated life test. Relevant test data can become available within months, not years, and destructive examination of the first life test heat pipe might begin within 6 months of test initiation. Final conclusions could be drawn in less than a quarter of the mission duration for a long-lived, fission-powered, deep space probe.

Martin, J.; Reid, R.; Stewart, E.; Hickman, R.; Mireles, O.

2013-01-01

268

Accelerated aging and flashover tests on 138 kV nonceramic line post insulators  

SciTech Connect

The behavior of 138 kV nonceramic line post insulators is investigated by means of clean fog tests conducted before and after aging in a specially designed accelerated aging chamber. The laboratory aging cycles are justified on the basis of actual weather in the coastal regions of Florida. Analytical measurements quantifying the degree of artificial aging are discussed and comparisons of artificial aging with service experience are presented. Observations of audible noise and radio influence voltage during the clean fog tests are reported.

Schneider, H.M.; Guidi, W.W. (EPRI High Voltage Transmission Research Center, Lenox, MA (United States)); Burnham, J.T. (Florida Power and Light Co., Juno Beach (United States)); Gorur, R.S. (Arizona State Univ., Tempe (United States)); Hall, J.F. (Electric Power Research Inst., Palo Alto, CA (United States))

1993-01-01

269

Accelerated life tests of specimen heat pipe from Communication Technology Satellite (CTS) project  

NASA Technical Reports Server (NTRS)

A gas-loaded variable conductance heat pipe of stainless steel with methanol working fluid identical to one now on the CTS satellite was life tested in the laboratory at accelerated conditions for 14 200 hours, equivalent to about 70 000 hours at flight conditions. The noncondensible gas inventory increased about 20 percent over the original charge. The observed gas increase is estimated to increase operating temperature by about 2.2 C, insufficient to harm the electronic gear cooled by the heat pipes in the satellite. Tests of maximum heat input against evaporator elevation agree well with the manufacturer's predictions.

Tower, L. K.; Kaufman, W. B.

1977-01-01

270

Bow-tie-tree in EPR cables after accelerated water treeing test  

SciTech Connect

The paper describes the results of accelerated water treeing test after a period of approximately one year with two recently manufactured (1988) varieties of commercial EPR cables, produced by different manufacturers and possessing different cable structures, as well as water impervious XLPE cable for comparison. In the test, bow-tie trees were found in the EPR insulation which was though to develop no or few bow-tie-trees. Examination results of bow-tie-tree in EPR cables are described in this report.

Uematsu, T.; Iwata, Z.; Irie, S.; Fujii, O. (Furukawa Electric Co. Ltd., Tokyo (Japan))

1992-10-01

271

Failure modes and effects criticality analysis and accelerated life testing of LEDs for medical applications  

NASA Astrophysics Data System (ADS)

While use of LEDs in Fiber Optics and lighting applications is common, their use in medical diagnostic applications is not very extensive. Since the precise value of light intensity will be used to interpret patient results, understanding failure modes [1-4] is very important. We used the Failure Modes and Effects Criticality Analysis (FMECA) tool to identify the critical failure modes of the LEDs. FMECA involves identification of various failure modes, their effects on the system (LED optical output in this context), their frequency of occurrence, severity and the criticality of the failure modes. The competing failure modes/mechanisms were degradation of: active layer (where electron-hole recombination occurs to emit light), electrodes (provides electrical contact to the semiconductor chip), Indium Tin Oxide (ITO) surface layer (used to improve current spreading and light extraction), plastic encapsulation (protective polymer layer) and packaging failures (bond wires, heat sink separation). A FMECA table is constructed and the criticality is calculated by estimating the failure effect probability (?), failure mode ratio (?), failure rate (?) and the operating time. Once the critical failure modes were identified, the next steps were generation of prior time to failure distribution and comparing with our accelerated life test data. To generate the prior distributions, data and results from previous investigations were utilized [5-33] where reliability test results of similar LEDs were reported. From the graphs or tabular data, we extracted the time required for the optical power output to reach 80% of its initial value. This is our failure criterion for the medical diagnostic application. Analysis of published data for different LED materials (AlGaInP, GaN, AlGaAs), the Semiconductor Structures (DH, MQW) and the mode of testing (DC, Pulsed) was carried out. The data was categorized according to the materials system and LED structure such as AlGaInP-DH-DC, AlGaInP-MQW-DC, GaN-DH-DC, and GaN-DH-DC. Although the reported testing was carried out at different temperature and current, the reported data was converted to the present application conditions of the medical environment. Comparisons between the model data and accelerated test results carried out in the present are reported. The use of accelerating agent modeling and regression analysis was also carried out. We have used the Inverse Power Law model with the current density J as the accelerating agent and the Arrhenius model with temperature as the accelerating agent. Finally, our reported methodology is presented as an approach for analyzing LED suitability for the target medical diagnostic applications.

Sawant, M.; Christou, A.

2012-12-01

272

Development of a Dielectric-Loaded Accelerator Test Facility Based on an X-Band Magnicon Amplifier  

SciTech Connect

The Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), are developing a dielectric-loaded accelerator (DLA) test facility powered by the 11.424-GHz magnicon amplifier that was developed jointly by NRL and Omega-P, Inc. Thus far, DLA structures developed by ANL have been tested at the NRL Magnicon Facility without injected electrons, including tests of alumina and magnesium calcium titanate structures at gradients up to {approx}8 MV/m. The next step is to inject electrons in order to build a compact DLA test accelerator. The Accelerator Laboratory of Tsinghua University in Beijing, China has developed a 5-MeV electron injector for the accelerator, and SLAC is developing a means to combine the two magnicon output arms, and to drive the injector and an accelerator section with separate control of the power ratio and relative phase. Also, RWBruce Associates, working with NRL, is developing a means to join ceramic tubes to produce long accelerating sections using a microwave brazing process. The installation and commissioning of the first dielectric-loaded test accelerator, including injector, DLA structure, and spectrometer, should take place within the next year.

Gold, S. H.; Fliflet, A. W. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kinkead, A. K. [LET Corporation, Washington, DC 20007 (United States); Gai, W.; Power, J. G.; Konecny, R.; Jing, C. [High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Tantawi, S. G.; Nantista, C. D. [Stanford Linear Accelerator Center, Menlo Park, CA 94025 (United States); Hu, Y.; Du, X.; Tang, C.; Lin, Y. [Tsinghua University, Beijing 100084 (China); Bruce, R. W.; Bruce, R. L. [RWBruce Associates, Inc., Arnold, MD 21012 (United States); Lewis, D. III [Material Science and Technology Division, Naval Research Laboratory (United States)

2006-01-03

273

Design of the fiber optic support system and fiber bundle accelerated life test for VIRUS  

NASA Astrophysics Data System (ADS)

The quantity and length of optical fibers required for the Hobby-Eberly Telescope* Dark Energy eXperiment (HETDEX) create unique fiber handling challenges. For HETDEX‡, at least 33,600 fibers will transmit light from the focal surface of the telescope to an array of spectrographs making up the Visible Integral-Field Replicable Unit Spectrograph (VIRUS). Up to 96 Integral Field Unit (IFU) bundles, each containing 448 fibers, hang suspended from the telescope's moving tracker located more than 15 meters above the VIRUS instruments. A specialized mechanical system is being developed to support fiber optic assemblies onboard the telescope. The discrete behavior of 448 fibers within a conduit is also of primary concern. A life cycle test must be conducted to study fiber behavior and measure Focal Ratio Degradation (FRD) as a function of time. This paper focuses on the technical requirements and design of the HETDEX fiber optic support system, the electro-mechanical test apparatus for accelerated life testing of optical fiber assemblies. Results generated from the test will be of great interest to designers of robotic fiber handling systems for major telescopes. There is concern that friction, localized contact, entanglement, and excessive tension will be present within each IFU conduit and contribute to FRD. The test apparatus design utilizes six linear actuators to replicate the movement of the telescope over 65,000 accelerated cycles, simulating five years of actual operation.

Soukup, Ian M.; Beno, Joseph H.; Hayes, Richard J.; Heisler, James T.; Mock, Jason R.; Mollison, Nicholas T.; Good, John M.; Hill, Gary J.; Vattiat, Brian L.; Murphy, Jeremy D.; Anderson, Seth C.; Bauer, Svend M.; Kelz, Andreas; Roth, Martin M.; Fahrenthold, Eric P.

2010-07-01

274

Life Time Prediction of Gas Turbine Components (Turbine Blades).  

National Technical Information Service (NTIS)

The problems of lifetime predictions for gas turbine blades made of cast alloys IN 738 LC and IN 939 were examined. The materials were tested under typical operating temperatures on their performance under fatigue and creep stress and with combined strain...

W. Hoffelner M. Nazmy C. Wuethrich

1985-01-01

275

Seismic-fragility tests of new and accelerated-aged Class 1E battery cells  

SciTech Connect

The seismic-fragility response of naturally-aged nuclear station safety-related batteries is of interest for two reasons: (1) to determine actual failure modes and thresholds and (2) to determine the validity of using the electrical capacity of individual cells as an indicator of the potential survivability of a battery given a seismic event. Prior reports in this series discussed the seismic-fragility tests and results for three specific naturally-aged cell types: 12-year old NCX-2250, 10-year old LCU-13, and 10-year old FHC-19. This report focuses on the complementary approach, namely, the seismic-fragility response of accelerated-aged batteries. Of particular interest is the degree to which such approaches accurately reproduce the actual failure modes and thresholds. In these tests the significant aging effects observed, in terms of seismic survivability, were: embrittlement of cell cases, positive bus material and positive plate grids; and excessive sulphation of positive plate active material causing hardening and expansion of positive plates. The IEEE Standard 535 accelerated aging method successfully reproduced seismically significant aging effects in new cells but accelerated grid embrittlement an estimated five years beyond the conditional age of other components.

Bonzon, L.L.; Janis, W.J.; Black, D.A.; Paulsen, G.A.

1987-01-01

276

Cavitation behavior observed in three monoleaflet mechanical heart valves under accelerated testing conditions.  

PubMed

Accelerated testing provides a substantial amount of data on mechanical heart valve durability in a short period of time, but such conditions may not accurately reflect in vivo performance. Cavitation, which occurs during mechanical heart valve closure when local flow field pressure decreases below vapor pressure, is thought to play a role in valve damage under accelerated conditions. The underlying flow dynamics and mechanisms behind cavitation bubble formation are poorly understood. Under physiologic conditions, random perivalvular cavitation is difficult to capture. We applied accelerated testing at a pulse rate of 600 bpm and transvalvular pressure of 120 mm Hg, with synchronized videographs and high-frequency pressure measurements, to study cavitation of the Medtronic Hall Standard (MHS), Medtronic Hall D-16 (MHD), and Omni Carbon (OC) valves. Results showed cavitation bubbles between 340 and 360 micros after leaflet/housing impact of the MHS, MHD, and OC valves, intensified by significant leaflet rebound. Squeeze flow, Venturi, and water hammer effects each contributed to cavitation, depending on valve design. PMID:18356649

Lo, Chi-Wen; Liu, Jia-Shing; Li, Chi-Pei; Lu, Po-Chien; Hwang, Ned H

2008-01-01

277

Development of a quantitative accelerated sulphate attack test for mine backfill  

NASA Astrophysics Data System (ADS)

Mining operations produce large amounts of tailings that are either disposed of in surface impoundments or used in the production of backfill to be placed underground. Their mineralogy is determined by the local geology, and it is not uncommon to come across tailings with a relatively high sulphide mineral content, including pyrite and pyrrhotite. Sulphides oxidize in the presence of oxygen and water to produce sulphate and acidity. In the concrete industry, sulphate is known to produce detrimental effects by reacting with the cement paste to produce the minerals ettringite and gypsum. Because mine backfill uses tailings and binders---including cement---it is therefore prone to sulphate attack where the required conditions are met. Currently, laboratory tests on mine backfill mostly measure mechanical properties such as strength parameters, and the study of the chemical aspects is restricted to the impact of tailings on the environment. The potential of sulphate attack in mine backfill has not been studied at length, and no tests are conducted on binders used in backfill for their resistance to attack. Current ASTM guidelines for sulphate attack tests have been deemed inadequate by several authors due to their measurement of only expansion as an indicator of attack. Furthermore, the tests take too long to perform or are restricted to cement mortars only, and not to mixed binders that include pozzolans. Based on these, an accelerated test for sulphate attack was developed in this work through modifying and compiling procedures that had been suggested by different authors. Small cubes of two different binders were fully immersed in daily-monitored sodium sulphate and sulphuric acid solutions for a total of 28 days, after 7 days of accelerated curing at 50°C. In addition, four binders were partially immersed in the same solutions for 8 days for an accelerated attack process. The two procedures were conducted in tandem with leach tests using a mixed solution of ethylene glycol and methanol solution, which enabled the quantification of ettringite and gypsum that had formed due to the attack. Combining the partial immersion technique with the dissolution of ettringite and gypsum in the organic solutions, a new quantitative accelerated test for sulphate attack was developed.

Shnorhokian, Shahe

278

Concepts for the magnetic design of the MITICA neutral beam test facility ion accelerator  

NASA Astrophysics Data System (ADS)

The megavolt ITER injector concept advancement neutral injector test facility will be constituted by a RF-driven negative ion source and by an electrostatic Accelerator, designed to produce a negative Ion with a specific energy up to 1 MeV. The beam is then neutralized in order to obtain a focused 17 MW neutral beam. The magnetic configuration inside the accelerator is of crucial importance for the achievement of a good beam efficiency, with the early deflection of the co-extracted and stripped electrons, and also of the required beam optic quality, with the correction of undesired ion beamlet deflections. Several alternative magnetic design concepts have been considered, comparing in detail the magnetic and beam optics simulation results, evidencing the advantages and drawbacks of each solution both from the physics and engineering point of view.

Chitarin, G.; Agostinetti, P.; Marconato, N.; Marcuzzi, D.; Sartori, E.; Serianni, G.; Sonato, P.

2012-02-01

279

Preliminary results of accelerated exposure testing of solar cell system components  

NASA Technical Reports Server (NTRS)

Plastic samples and solar cell sub modules were exposed to an accelerated outdoor environment in Arizona and an accelerated simulated environment in a cyclic ultraviolet exposure tester which included humidity exposure. These tests were for preliminary screening of materials suitable for use in the manufacture of solar cell modules which are to have a 20-year lifetime. The samples were exposed for various times up to six months, equivalent to a real time exposure of four years. Suitable materials were found to be FEP-A, FEP-C, PFA, acrylic, silicone compounds and adhesives and possibly parylene. The method of packaging the sub modules was also found to be important to their performance.

Anagnostou, E.; Forestieri, A. F.

1977-01-01

280

Concepts for the magnetic design of the MITICA neutral beam test facility ion accelerator.  

PubMed

The megavolt ITER injector concept advancement neutral injector test facility will be constituted by a RF-driven negative ion source and by an electrostatic Accelerator, designed to produce a negative Ion with a specific energy up to 1 MeV. The beam is then neutralized in order to obtain a focused 17 MW neutral beam. The magnetic configuration inside the accelerator is of crucial importance for the achievement of a good beam efficiency, with the early deflection of the co-extracted and stripped electrons, and also of the required beam optic quality, with the correction of undesired ion beamlet deflections. Several alternative magnetic design concepts have been considered, comparing in detail the magnetic and beam optics simulation results, evidencing the advantages and drawbacks of each solution both from the physics and engineering point of view. PMID:22380264

Chitarin, G; Agostinetti, P; Marconato, N; Marcuzzi, D; Sartori, E; Serianni, G; Sonato, P

2012-02-01

281

Beam Based HOM Analysis of Accelerating Structures at the TESLA Test Facility Linac  

SciTech Connect

The beam emittance in future linear accelerators for high energy physics and SASE-FEL applications depends highly on the field performance in the accelerating structures, i.e. the damping of higher order modes (HOM). Besides theoretical and laboratory analysis, a beam based analysis technique was established [1] at the TESLA Test Facility (TTF) linac. It uses a charge modulated beam of variable modulation frequency to excite dipole modes. This causes a modulation of the transverse beam displacement, which is observed at a downstream BPM and associated with a direct analysis of the modes at the HOM-couplers. A brief introduction of eigenmodes of a resonator and the concept of the wake potential is given. Emphasis is put on beam instrumentation and signal analysis aspects, required for this beam based HOM measurement technique.

Wendt, M.; Schreiber, S.; Castro, P.; Gossel, A.; /DESY; Huning, M.; /Fermilab; Devanz, G.; Jablonka, M.; Magne, C.; Napoly, O.; /Saclay; Baboi, N.; /SLAC

2005-08-09

282

Design and testing of a DC ion injector suitable for accelerator-driven transmutation  

NASA Astrophysics Data System (ADS)

For a number of years, Los Alamos personnel have collaborated with a team of experimentalists at Chalk River Labs (CRL) near Deep River, Ontario, Canada who were pursuing the development of the front end of a high power cw proton accelerator. At the termination of this program last year, Los Alamos acquired this equipment. With the help of internal Laboratory funding and modest defense conversion funds, we have set up and operated the accelerator at Los Alamos. Operational equipment includes a slightly modified Chalk River Injector Test Stand (CRITS) including a 50 keV proton injector and a 1.25 MeV radio-frequency quadrupole (RFQ) with a klystrode rf power system. Substantial upgrading and modification of the ac power system was necessary to provide the required ac voltage (2400 vac) and power (2 MVA) needed for the operation of this equipment. A companion paper describes in detail the first ion source and beam-transport measurements at Los Alamos. Many of the challenges involved in operating an rf linear accelerator to provide neutrons for an accelerator-driven reactor are encountered at the front (low energy) end of this system. The formation of the ion beam, the control of the beam parameters, and the focusing and matching of a highly space-charge-dominated beam are major problems. To address the operating problems in this critical front end, the Accelerator Operations and Technology Division at the Los Alamos National Laboratory has designed the APDF (Accelerator Prototype Demonstration Facility). The front end of this facility is a 75 keV, high-current, ion injector which has been assembled and is now being tested. This paper discusses the design modifications required in going from the 50 keV CRITS injector to the higher current, 75 keV injector. Major innovative changes were made in the design of this injector. This design eliminates all the control electronics and most of the ion source equipment at high potential. Also, a new, high-quality, ion-extractor system has been built. A dual-solenoid lens will be used in the low energy beam transport (LEBT) line to provide the capability of matching the extracted beam to a high-current ADTT linac. This new injector is the first piece of hardware in the APDF program and will be used to develop the long-term, reliable cw beam operation required for ADTT applications.

Schneider, J. David; Meyer, Earl; Stevens, Ralph R.; Hansborough, Lash; Sherman, Joseph

1995-09-01

283

Design and testing of a dc ion injector suitable for accelerator-driven transmutation  

SciTech Connect

For a number of years, Los Alamos have collaborated with a team of experimentalists at Chalk River Labs who were pursuing the development of the front end of a high power cw proton accelerator. With the help of internal laboratory funding and modest defense conversion funds, we have set up and operated the accelerator at Los Alamos Operational equipment includes a slightly modified Chalk River Injector Test Stand (CRITS) including a 50 keV proton injector and a 1.25 MeV radio-frequency quadrupole (RFQ) with a klystrode rf power system. Many of the challenges involved in operating an rf linear accelerator to provide neutrons for an accelerator-driven reactor are encountered at the front (low energy) end of this system. The formation of the ion beam, the control of the beam parameters, and the focusing and matching of a highly space-charge-dominated beam are major problems. To address the operating problems in this critical front end, the Accelerator Operations and Technology Division at the Los Alamos National Laboratory has designed the APDF (Accelerator Prototype Demonstration Facility). The front end of this facility is a 75 keV, high-current, ion injector which has been assembled and is now being tested. This paper discusses the design modifications required in going from the 50 keV CRITS injector to the higher current, 75 keV injector. Major innovative changes were made in the design of this injector. This design eliminates all the control electronics and most of the ion source equipment at high potential. Also, a new, high-quality, ion-extractor system has been built. A dual-solenoid lens will be used in the low energy beam transport (LEBT) line to provide the capability of matching the extracted beam to a high-current ADTT linac. This new injector is the first piece of hardware in the APDF program and will be used to develop the long-term, reliable cw beam operation required for ADIT applications.

Schneider, J.D.; Meyer, E.; Stevens, R.R. Jr.; Hansborough, L.; Sherman, J.

1994-08-01

284

Accelerated life test of sputtering and anode deposit spalling in a small mercury ion thruster  

NASA Technical Reports Server (NTRS)

Tantalum and molybdenum sputtered from discharge chamber components during operation of a 5 centimeter diameter mercury ion thruster adhered much more strongly to coarsely grit blasted anode surfaces than to standard surfaces. Spalling of the sputtered coating did occur from a coarse screen anode surface but only in flakes less than a mesh unit long. The results were obtained in a 200 hour accelerated life test conducted at an elevated discharge potential of 64.6 volts. The test approximately reproduced the major sputter erosion and deposition effects that occur under normal operation but at approximately 75 times the normal rate. No discharge chamber component suffered sufficient erosion in the test to threaten its structural integrity or further serviceability. The test indicated that the use of tantalum-surfaced discharge chamber components in conjunction with a fine wire screen anode surface should cure the problems of sputter erosion and sputtered deposits spalling in long term operation of small mercury ion thrusters.

Power, J. L.

1975-01-01

285

Test of pixel detectors for laser-driven accelerated particle beams  

NASA Astrophysics Data System (ADS)

Laser-driven accelerated (LDA) particle beams have due to the unique acceleration process very special properties. In particular they are created in ultra-short bunches of high intensity exceeding more than 107 \\frac{particles}{cm^{2} \\cdot ns} per bunch. Characterization of these beams is very limited with conventional particle detectors. Non-electronic detectors such as imaging plates or nuclear track detectors are, therefore, conventionally used at present. Moreover, all these detectors give only offline information about the particle pulse position and intensity as they require minutes to hours to be processed, calling for a new highly sensitive online device. Here, we present tests of different pixel detectors for real time detection of LDA ion pulses. Experiments have been performed at the Munich 14MV Tandem accelerator with 8-20 MeV protons in dc and pulsed beam, the latter producing comparable flux as a LDA ion pulse. For detection tests we chose the position-sensitive quantum-counting semiconductor pixel detector Timepix which also provides per-pixel energy- or time-sensitivity. Additionally other types of commercially available pixel detectors are being evaluated such as the RadEye™1, a large area (25 x 50 mm2) CMOS image sensor. All of these devices are able to resolve individual ions with high spatial- and energy-resolution down to the level of ?m and tens of keV, respectively. Various beam delivering parameters of the accelerator were thus evaluated and verified. The different readout modes of the Timepix detector which is operated with an integrated USB-based readout interface allow online visualization of single and time-integrated events. Therefore Timepix offers the greatest potential in analyzing the beam parameters.

Reinhardt, S.; Granja, C.; Krejci, F.; Assmann, W.

2011-12-01

286

Estimation of the join point in a heteroscedast1c regression model arising in accelerated life tests  

Microsoft Academic Search

In certain accelerated life test experiments, when acceler-ating beyond certain values of the stress, a change in the basic failure mechanism occurs. Such situations call for the introduction of two or more submodels joined at what is known as a \\

Nozer D. Singpurwalla

1974-01-01

287

The next linear collider test accelerator{close_quote}s RF pulse compression and transmission systems  

SciTech Connect

The overmoded rf transmission and pulsed power compression system for SLAC{close_quote}s Next Linear Collider (NLC) program requires a high degree of transmission efficiency and mode purity to be economically feasible. To this end, a number of new, high power components and systems have been developed at X-band, which transmit rf power in the low loss, circular TE{sub 01} mode with negligible mode conversion. In addition, a highly efficient SLED-II [1] pulse compressor has been developed and successfully tested at high power at two accelerator test facilities at SLAC. The systems produced a 200 MW pulse with a near-perfect flat-top with pulse widths ranging from 150{endash}245 ns. In this paper we describe the design and test results of a rectangular-to-circular mode converter and the components/transmission systems based on them, as well as the design and measurements of the high power pulse compression systems using SLED-II. We will also describe how these components are being used to efficiently provide high power rf in the NLC Test Accelerator (NLCTA) program at SLAC. {copyright} {ital 1997 American Institute of Physics.}

Tantawi, S.G.; Vlieks, A.E.; Fant, K.; Lavine, T.; Loewen, R.J.; Pearson, C.; Pope, R.; Rifkin, J.; Ruth, R.D. [Stanford Linear Accelerator Center, 2575 Sand Hill Rd., Menlo Park, California, 94025 (United States)

1997-03-01

288

The next linear collider test accelerator's RF pulse compression and transmission systems  

NASA Astrophysics Data System (ADS)

The overmoded rf transmission and pulsed power compression system for SLAC's Next Linear Collider (NLC) program requires a high degree of transmission efficiency and mode purity to be economically feasible. To this end, a number of new, high power components and systems have been developed at X-band, which transmit rf power in the low loss, circular TE01 mode with negligible mode conversion. In addition, a highly efficient SLED-II [1] pulse compressor has been developed and successfully tested at high power at two accelerator test facilities at SLAC. The systems produced a 200 MW pulse with a near-perfect flat-top with pulse widths ranging from 150-245 ns. In this paper we describe the design and test results of a rectangular-to-circular mode converter and the components/transmission systems based on them, as well as the design and measurements of the high power pulse compression systems using SLED-II. We will also describe how these components are being used to efficiently provide high power rf in the NLC Test Accelerator (NLCTA) program at SLAC.

Tantawi, S. G.; Vlieks, A. E.; Fant, K.; Lavine, T.; Loewen, R. J.; Pearson, C.; Pope, R.; Rifkin, J.; Ruth, R. D.

1997-03-01

289

HIV self-testing practices among Health Care Workers: feasibility and options for accelerating HIV testing services in Ethiopia  

PubMed Central

Introduction HIV is still an enormous global burden and it is also causing loss of huge health care workers (HCWs) on the already limited human resource capacity in health care services in Sub-Saharan Africa. Variety of methods of accelerating HIV testing is required to increase the rate of HIV testing and expand treatment services. Therefore, this study was aimed to find out the prevalence, feasibility and options of HIV self-testing practices in Ethiopia. Methods A cross-sectional study design triangulated with qualitative method was conducted from February to May, 2012. The data was collected using a semi-structured pretested questionnaire and in-depth interview, at government and private health centers or clinics and hospitals. During the data collection all the available healthcare workers (HCWs) which encompass the internship students including: Medical, Health Officer, Nurses, Midwives and Laboratory students, and health professionals working in the selected health institutions were involved. Results A total of 307 HCWs were included in the analysis and we found that 288(94.4%) of them were ever tested for HIV, of which majority 203 (70.5%) were tested by themselves though 244(80%) of the HCWs had motivation or interest to be tested by themselves. Generally, of the ever tested only 85(29.5%) were tested by the help of health care providers/counselors other than self. Regarding the place where the HCWs had the test, majority 136 (69.4%) tested by themselves at the health facility and the rest were tested at their home, office, market and church. The main reason stated for self-testing was the need for confidentiality for the test result, which was mentioned by 205(82%). Moreover, 35(14.0%) claims lack of time to access the ordinary counseling and testing services. Conclusion This study depicts high rate of HIV self-testing practice among HCWs. This shows that HIV self-testing can be considered as one pillar to increase the HIV-testing services and a means for the HIV prevention and control policy, through increasing HIV testing uptake and awareness of HIV status. However, the implementation may require the role of different stakeholders and decision makers with further study to extend the options.

Kebede, Bekana; Abate, Tatek; Mekonnen, Desalew

2013-01-01

290

Feasibility of Using Neural Network Models to Accelerate the Testing of Mechanical Systems  

NASA Technical Reports Server (NTRS)

Verification testing is an important aspect of the design process for mechanical mechanisms, and full-scale, full-length life testing is typically used to qualify any new component for use in space. However, as the required life specification is increased, full-length life tests become more costly and lengthen the development time. At the NASA Lewis Research Center, we theorized that neural network systems may be able to model the operation of a mechanical device. If so, the resulting neural network models could simulate long-term mechanical testing with data from a short-term test. This combination of computer modeling and short-term mechanical testing could then be used to verify the reliability of mechanical systems, thereby eliminating the costs associated with long-term testing. Neural network models could also enable designers to predict the performance of mechanisms at the conceptual design stage by entering the critical parameters as input and running the model to predict performance. The purpose of this study was to assess the potential of using neural networks to predict the performance and life of mechanical systems. To do this, we generated a neural network system to model wear obtained from three accelerated testing devices: 1) A pin-on-disk tribometer; 2) A line-contact rub-shoe tribometer; 3) A four-ball tribometer.

Fusaro, Robert L.

1998-01-01

291

Low-Level RF Signal Processing for the Next Linear Collider Test Accelerator  

NASA Astrophysics Data System (ADS)

In the X-band accelerator system for the Next Linear Collider Test Accelerator (NLCTA), the Low Level RF (LLRF) drive system must be very phase stable, but concurrently, be very phase agile. Phase agility is needed to make SLED power multiplier systems work and to shape the rf waveform to compensate beam loading in the accelerator sections. Similarly, precision fast phase and amplitude monitors are required to view, track, and feed back on rf signals at various locations throughout the system. The LLRF System is composed of several subsystems: the RF Reference System generates and distributes a reference 11.424 GHz rf signal to four rf stations, the Signal Processing Chassis creates the rf waveforms with the appropriate phase modulation, and the Phase Detector Assembly measures the amplitude and phase of monitored rf signals. The LLRF is run via VXI instrumentation. These instruments are controlled using HP VEE graphical programming software. Programs have been developed to shape the rf waveform, calibrate the phase modulators and demodulators, and display the measured waveforms. This paper describes these and other components of the LLRF system.

Holmes, Sharon; Adolphsen, Chris; Akre, Ron; Gold, Saul; Koontz, Ron; Nantista, Chris; Wilson, Zane; Ziomek, Chris

1997-05-01

292

Low-level RF signal processing for the Next Linear Collider Test Accelerator  

SciTech Connect

In the X-band accelerator system for the Next Linear Collider Test Accelerator (NLCTA), the Low Level RF (LLRF) drive system must be very phase stable, but concurrently, be very phase agile. Phase agility is needed to make the Stanford Linear Doubler (SLED) power multiplier systems Energy work and to shape the RF waveforms to compensate beam loading in the accelerator sections. Similarly, precision fast phase and amplitude monitors are required to view, track, and feed back on RF signals at various locations throughout the system. The LLRF is composed of several subsystems: the RF Reference System generates and distributes a reference 11.424 GHz signal to all of the RF stations, the Signal Processing Chassis creates the RF waveforms with the appropriate phase modulation, and the Phase Detector Assembly measures the amplitude and phase of monitor3ed RF signals. The LLRF is run via VXI instrumentation. These instruments are controlled using HP VEE graphical programming software. Programs have been developed to shape the RF waveform, calibrate the phase modulators and demodulators, and display the measured waveforms. This paper describes these and other components of the LLRF system.

Holmes, S.; Ziomek, C.; Adolphsen, C. [and others

1997-05-12

293

Selected Topics in Railroad Tank Car Safety Research. Volume II. Test Plan for Accelerated Life Testing of Thermally Shielded Tank Cars.  

National Technical Information Service (NTIS)

A test plan for the accelerated life testing of thermally shielded tank cars is described. The test program would be conducted at the DOT Transportation Test Center in Pueblo, Colorado. Eighteen tank cars would be included in the program. Five cars would ...

M. R. Johnson O. J. Viergutz

1978-01-01

294

Tests for linkage of multiple cohorts in an accelerated longitudinal design.  

PubMed

In accelerated longitudinal design, one samples multiple age cohorts and then collects longitudinal data on members of each cohort. The aim is to study age-outcome trajectories over a broad age span during a study of short duration. A threat to valid inference is the Age x Cohort interaction effect. S. W. Raudenbush and W. S. Chan (1993) developed a test for such interactions in the context of 2 cohorts by using a hierarchical model. The current article extends this approach to include any number of cohorts. Using the National Youth Survey, the authors combine data collected on 7 cohorts over 5 years to approximate change in antisocial attitudes between 11 and 21 years of age. They show how to test for cohort differences in trajectories, how to calculate the power of the test, and how to use graphical procedures to aid understanding. The approach allows unbalanced designs and the clustering of participants within families, neighborhoods, or other social units. PMID:10937322

Miyazaki, Y; Raudenbush, S W

2000-03-01

295

Single Event Upset Test at the CRYRING Heavy-Ion Accelerator  

NASA Astrophysics Data System (ADS)

The energy and particle intensity domain of the CRYRING heavy-ion accelerator is well suited for studies of Single Event Upset phenomena. This effect occurs when a charged particle hits a working electronic circuit and the charge created alters its state. The radiative environment is one of the major problems for electronic circuits in an orbiting satellite. The situation is similar for future detectors at the new high-energy physics facilities, like the Large Hadron Collider (LHC) at CERN. The increasing use of submicron technology in combination with a lowering of the circuit voltage decreases the critical charge for temporary upsets. In this article the SEU test setup at CRYRING is described, where memories are used for testing digital circuit technologies. For these tests two types of particle extraction is used and two types of scintillator beam monitors (BaF2 and YAP) are described. Temporary, soft errors were recorded in static RAM memory circuits.

Novak, D.; Kerek, A.; Klamra, W.; Norlin, L.-O.; Bagge, L.; Kaellberg, A.; Paal, A.; Rensfelt, K. G.; Molnar, J.

1999-05-01

296

Preliminary results from pressure tank test and field acceleration test of New-Profiling float of Japan (NINJA)  

NASA Astrophysics Data System (ADS)

As one of contributions of Japan to the international Argo community, one of Japanese ocean instrument manufacturers, Tsurumi Seiki Co. (TSK), has started the development of original profiling float in 2000. We purchased the four TSK floats in 2001, and performed the pressure tank test and the acceleration field test in the north Pacific. Among four floats, two are carrying SBE41 CTD sensor, and two are carrying TSK-original CTD sensor. In the pressure tank test, by controlling a tank pressure as float controller expects, we created the ideal ocean in a tank for the float. The TSK float successfully worked as was scheduled, and measured profile data when the float was coming up to the surface (i.e. pressure in tank was decreasing). We also performed the ballasting test of weight of the TSK float to drift at 2000dbars (Swift and Riser, 1994). After these tests, we launched two floats with TSK sensor in the north Pacific in June. One of the floats has finished the 20th profile on 26 August 2002 and is still working. The technical message from the float indicates the stable parking near 2000dbars, the stable profiling speed, and no missing profile data. The temperature and salinity data also indicate the stable T-S relations in deeper layer below 1500dbars among profiles. In this presentation, we will also show the results of field test of the floats with SBE sensor, which will be launched in October 2002.

Izawa, K.; Ando, K.; Mizuno, K.; Inoue, A.; Shikama, N.; Takeuchi, K.; Sekimoto, M.

2002-12-01

297

Long-term storage life of light source modules by temperature cycling accelerated life test  

NASA Astrophysics Data System (ADS)

Light source modules are the most crucial and fragile devices that affect the life and reliability of the interferometric fiber optic gyroscope (IFOG). While the light emitting chips were stable in most cases, the module packaging proved to be less satisfactory. In long-term storage or the working environment, the ambient temperature changes constantly and thus the packaging and coupling performance of light source modules are more likely to degrade slowly due to different materials with different coefficients of thermal expansion in the bonding interface. A constant temperature accelerated life test cannot evaluate the impact of temperature variation on the performance of a module package, so the temperature cycling accelerated life test was studied. The main failure mechanism affecting light source modules is package failure due to solder fatigue failure including a fiber coupling shift, loss of cooling efficiency and thermal resistor degradation, so the Norris-Landzberg model was used to model solder fatigue life and determine the activation energy related to solder fatigue failure mechanism. By analyzing the test data, activation energy was determined and then the mean life of light source modules in different storage environments with a continuously changing temperature was simulated, which has provided direct reference data for the storage life prediction of IFOG.

Ningning, Sun; Manqing, Tan; Ping, Li; Jian, Jiao; Xiaofeng, Guo; Wentao, Guo

2014-05-01

298

In Situ, Time-Resolved Accelerator Grid Erosion Measurements in the NSTAR 8000 Hour Ion Engine Wear Test  

NASA Technical Reports Server (NTRS)

Time-resolved, in situ measurements of the charge exchange ion erosion pattern on the downstream face of the accelerator grid have been made during an ongoin wear test of the NSTAR 30 cm ion thruster.

Sovey, J.

1997-01-01

299

Simulation and steering in the intertank matching section of the ground test accelerator  

SciTech Connect

The Intertank Matching Section (IMS) of the Ground Test Accelerator (GTA) is a short (36 cm) beamline designed to match the Radio Frequency Quadrupole (RFQ) exit beam into the first Drift Tube LINAC (DTL) tank. The IMS contains two steering quadrupoles (SMQs) and four variable-field focussing quads (VFQs). The SMQs are fixed strength permanent magnet quadrupoles on mechanical actuators capable of transverse movement for the purpose of steering the beam. The upstream and downstream steering quadrupoles are labelled SMQ1 and SMQ4 respectively. Also contained in the IMS are two RF cavities for longitudinal matching.

Yuan, V.W.; Bolme, G.O.; Johnson, K.F.; Mottershead, C.T.; Sander, O.R.; Smith, M.T. [Los Alamos National Lab., NM (United States); Erickson, J.L. [Grumman Energy Systems Division, Bethpage, NY (United States)

1994-10-01

300

Analysis of debris from accelerated life test of the Hughes five-year Vuilleumier cryocooler  

NASA Astrophysics Data System (ADS)

Unit S3 of the Hughes Vuilleumier (VM) Cryocooler Program has undergone accelerated life testing at twice the service speed expected in a normal unit. Debris samples were obtained from all areas of the cooler; samples of the regenerator balls were collected from the second and third stages only. The debris has been identified by an investigative analysis using the analytical techniques of X-ray diffraction, IMMA, and SEM/EDXS. Most of the particulates contain a combination of Fe, Cr, and Ni or Mo-Nb compounds.

Cranmer, D. C.; Watts, E. J.

1987-05-01

301

Environmental Phase Stabilization of the Next Linear Collider Test Accelerator's Low-Level RF System  

NASA Astrophysics Data System (ADS)

The Next Linear Collider Test Accelerator (NLCTA) requires an extremely phase stable low-level RF (LLRF) drive system. In order to help achieve this both the LLRF drive system and the LLRF monitor system have been provided controlled environments in which to operate. In this paper we describe the mechanical design and layout of the thermal and mechanical isolation systems for the LLRF, the performance of the isolation systems and the effects on phase stability of the LLRF system due to the isolation systems. These systems include temperature stable enclosures, active thermal systems, passive thermal systems, temperature stable water systems, and mechanically isolated support structures.

Wilson, Zane J.

1997-05-01

302

Low-level RF system design for the Accelerator Test Facility (ATF) damping ring  

SciTech Connect

The ATF damping ring was built to demonstrate the production of low emittance, high current beams for future linear colliders. To attain high beam currents, multiple high current bunch trains are required. The low-level rf system should be designed to minimize both steady-state and transient beam loading effects in the accelerating cavities. In addition the design should be sufficiently flexible to allow for a variety of beam dynamics tests which require a wide range of beam currents and cavity voltages. The low-level rf system and stability boundaries for reduced power and full power operation are discussed in this paper.

Minty, M.G. [Stanford Univ., CA (US). Stanford Linear Accelerator Center; Kubo, K.; Hinode, F.; Sakanaka, S.; Urakawa, J. [KEK, Tsukuba, Ibaraki (Japan)

1997-11-01

303

Development and beam test of a continuous wave radio frequency quadrupole accelerator  

NASA Astrophysics Data System (ADS)

The front end of any modern ion accelerator includes a radio frequency quadrupole (RFQ). While many pulsed ion linacs successfully operate RFQs, several ion accelerators worldwide have significant difficulties operating continuous wave (CW) RFQs to design specifications. In this paper we describe the development and results of the beam commissioning of a CW RFQ designed and built for the National User Facility: Argonne Tandem Linac Accelerator System (ATLAS). Several innovative ideas were implemented in this CW RFQ. By selecting a multisegment split-coaxial structure, we reached moderate transverse dimensions for a 60.625-MHz resonator and provided a highly stabilized electromagnetic field distribution. The accelerating section of the RFQ occupies approximately 50% of the total length and is based on a trapezoidal vane tip modulation that increased the resonator shunt impedance by 60% in this section as compared to conventional sinusoidal modulation. To form an axially symmetric beam exiting the RFQ, a very short output radial matcher with a length of 0.75?? was developed. The RFQ is designed as a 100% oxygen-free electronic (OFE) copper structure and fabricated with a two-step furnace brazing process. The radio frequency (rf) measurements show excellent rf properties for the resonator, with a measured intrinsic Q equal to 94% of the simulated value for OFE copper. An O5+ ion beam extracted from an electron cyclotron resonance ion source was used for the RFQ commissioning. In off-line beam testing, we found excellent coincidence of the measured beam parameters with the results of beam dynamics simulations performed using the beam dynamics code TRACK, which was developed at Argonne. These results demonstrate the great success of the RFQ design and fabrication technology developed here, which can be applied to future CW RFQs.

Ostroumov, P. N.; Mustapha, B.; Barcikowski, A.; Dickerson, C.; Kolomiets, A. A.; Kondrashev, S. A.; Luo, Y.; Paskvan, D.; Perry, A.; Schrage, D.; Sharamentov, S. I.; Sommer, R.; Toter, W.; Zinkann, G.

2012-11-01

304

Development of an accelerated abrasion test apparatus with a standardized testing procedure  

Microsoft Academic Search

Depending on the nature of the working environment, the abrasive wear of concrete floor slabs can range from scratching or\\u000a scuffing to impact and local crushing. To assess abrasion resistance it is, therefore, necessary to have a versatile apparatus.\\u000a This investigation describes the development of a basic apparatus with three modes of action and a standardized testing procedure,\\u000a for assessing

M. Sadegzadeh; R. J. Kettle

1988-01-01

305

How to estimate the differential acceleration in a two-species atom interferometer to test the equivalence principle  

Microsoft Academic Search

We propose a scheme for testing the weak equivalence principle (universality of free-fall (UFF)) using an atom-interferometric measurement of the local differential acceleration between two atomic species with a large mass ratio as test masses. An apparatus in free fall can be used to track atomic free-fall trajectories over large distances. We show how the differential acceleration can be extracted

Gael Varoquaux; R. A. Nyman; Rémi Geiger; Patrick Cheinet; Arnaud Landragin; Philippe Bouyer

2009-01-01

306

Acceleration for the ?+?- collider  

Microsoft Academic Search

We discuss possible acceleration scenarios and methods for a ? +-?- collider. The accelerator must take the beams from ~100 MeV to 2 TeV energies within the muon life-time (2.2×10-6E?\\/m? ?S), while compressing bunches of ~1012 muons from m to cm bunch lengths. A linac, recirculating linac, and very rapid-cycling synchrotron approaches are studied. A multiple recirculating linac approach is

D. Summers; D. Neuffer; Q.-S. Shu; E. Willen

1997-01-01

307

Design and Flight Tests of an Adaptive Control System Employing Normal-Acceleration Command  

NASA Technical Reports Server (NTRS)

An adaptive control system employing normal-acceleration command has been designed with the aid of an analog computer and has been flight tested. The design of the system was based on the concept of using a mathematical model in combination with a high gain and a limiter. The study was undertaken to investigate the application of a system of this type to the task of maintaining nearly constant dynamic longitudinal response of a piloted airplane over the flight envelope without relying on air data measurements for gain adjustment. The range of flight conditions investigated was between Mach numbers of 0.36 and 1.15 and altitudes of 10,000 and 40,000 feet. The final adaptive system configuration was derived from analog computer tests, in which the physical airplane control system and much of the control circuitry were included in the loop. The method employed to generate the feedback signals resulted in a model whose characteristics varied somewhat with changes in flight condition. Flight results showed that the system limited the variation in longitudinal natural frequency of the adaptive airplane to about half that of the basic airplane and that, for the subsonic cases, the damping ratio was maintained between 0.56 and 0.69. The system also automatically compensated for the transonic trim change. Objectionable features of the system were an exaggerated sensitivity of pitch attitude to gust disturbances, abnormally large pitch attitude response for a given pilot input at low speeds, and an initial delay in normal-acceleration response to pilot control at all flight conditions. The adaptive system chatter of +/-0.05 to +/-0.10 of elevon at about 9 cycles per second (resulting in a maximum airplane normal-acceleration response of from +/-0.025 g to +/- 0.035 g) was considered by the pilots to be mildly objectionable but tolerable.

McNeill, Water E.; McLean, John D.; Hegarty, Daniel M.; Heinle, Donovan R.

1961-01-01

308

Development of an accelerated test design for predicting the service life of the solar array at Mead, Nebraska  

NASA Technical Reports Server (NTRS)

An accelerated life test is described which was developed to predict the life of the 25 kW photovoltaic array installed near Mead, Nebraska. A quantitative model for accelerating testing using multiple environmental stresses was used to develop the test design. The model accounts for the effects of thermal stress by a relation of the Arrhenius form. This relation was then corrected for the effects of nonthermal environmental stresses, such as relative humidity, atmospheric pollutants, and ultraviolet radiation. The correction factors for the nonthermal stresses included temperature-dependent exponents to account for the effects of interactions between thermal and nonthermal stresses on the rate of degradation of power output. The test conditions, measurements, and data analyses for the accelerated tests are presented. Constant-temperature, cyclic-temperature, and UV types of tests are specified, incorporating selected levels of relative humidity and chemical contamination and an imposed forward-bias current and static electric field.

Gaines, G. B.; Thomas, R. E.; Noel, G. T.; Shilliday, T. S.; Wood, V. E.; Carmichael, D. C.

1979-01-01

309

Lessons from two field tests on pipeline damage detection using acceleration measurement  

NASA Astrophysics Data System (ADS)

Early detection of pipeline damages has been highlighted in water supply industry. Water pressure change in pipeline due to a sudden rupture causes pipe to vibrate and the pressure change propagates through the pipeline. From the measurement of pipe vibration the rupture can be detected. In this paper, the field test results and observations are provided for implementing next generation of SCADA system for pipeline rupture detection. Two field tests were performed on real buried plastic and metal pipelines for rupture detection. The rupture was simulated by introducing sudden water pressure drop caused by water blow-off and valve control. The measured acceleration data at the pipe surfaces were analyzed in both time and frequency domain. In time domain, the sudden narrow increase of acceleration amplitude was used as an indication of rupture event. For the frequency domain analysis, correlation function and the short time Fourier Transform technique were adopted to trace the dominant frequency shift. The success of rupture detection was found to be dependent on several factors. From the frequency analysis, the dominant frequency of metal water pipe was shifted by the water pressure drop, however, it was hard to identify from the plastic pipeline. Also the influence of existing facility such as airvac on pipe vibrations was observed. Finally, several critical lessons learned in the viewpoint of field measurement are discussed in this paper.

Shinozuka, Masanobu; Lee, Sungchil; Kim, Sehwan; Chou, Pai H.

2011-03-01

310

Test Results of a Superconducting Quadrupole Model Designed for Linear Accelerator Applications  

SciTech Connect

The first model of a superconducting quadrupole for use in a Linear Accelerator was designed, built and tested at Fermilab. The quadrupole has a 78 mm aperture, and a cold mass length of 680 mm. A superferric magnet configuration with iron poles and four racetrack coils was chosen based on magnet performance, cost, and reliability considerations. Each coil is wound using enamel insulated, 0.5 mm diameter, NbTi superconductor. The quadrupole package also includes racetrack type dipole steering coils. The results of the quadrupole design, manufacturing and test, are presented. Specific issues related to the quadrupole magnetic center stability, superconductor magnetization and mechanical stability are discussed. The magnet quench performance and results of magnetic measurements will also be briefly discussed.

Kashikhin, Vladimir S.; Andreev, Nikolai; Chlachidze, Guram; DiMarco, Joseph; Kashikhin, Vadim V.; Lamm, Michael J.; Lopes, Mauricio L.; Orris, Darryl; Tartaglia, Michael; Tompkins, John C.; Velev, Gueorgui; /Fermilab

2008-08-01

311

Accelerated Life Structural Benchmark Testing for a Stirling Convertor Heater Head  

NASA Technical Reports Server (NTRS)

For proposed long-duration NASA Space Science missions, the Department of Energy, Lockheed Martin, Infinia Corporation, and NASA Glenn Research Center are developing a high-efficiency, 110 W Stirling Radioisotope Generator (SRG110). A structurally significant limit state for the SRG110 heater head component is creep deformation induced at high material temperature and low stress level. Conventional investigations of creep behavior adequately rely on experimental results from uniaxial creep specimens, and a wealth of creep data is available for the Inconel 718 material of construction. However, the specified atypical thin heater head material is fine-grained with a heat treatment that limits precipitate growth, and little creep property data for this microstructure is available in the literature. In addition, the geometry and loading conditions apply a multiaxial stress state on the component, far from the conditions of uniaxial testing. For these reasons, an extensive experimental investigation is ongoing to aid in accurately assessing the durability of the SRG110 heater head. This investigation supplements uniaxial creep testing with pneumatic testing of heater head-like pressure vessels at design temperature with stress levels ranging from approximately the design stress to several times that. This paper presents experimental results, post-test microstructural analyses, and conclusions for four higher-stress, accelerated life tests. Analysts are using these results to calibrate deterministic and probabilistic analytical creep models of the SRG110 heater head.

Krause, David L.; Kantzos, Pete T.

2006-01-01

312

Accelerated Life Structural Benchmark Testing for a Stirling Convertor Heater Head  

SciTech Connect

For proposed long-duration NASA Space Science missions, the Department of Energy, Lockheed Martin, Infinia Corporation, and NASA Glenn Research Center are developing a high-efficiency, 110-watt Stirling Radioisotope Generator (SRG110). A structurally significant limit state for the SRG110 heater head component is creep deformation induced at high material temperature and low stress level. Conventional investigations of creep behavior adequately rely on experimental results from uniaxial creep specimens, and a wealth of creep data is available for the Inconel 718 material of construction. However, the specified atypical thin heater head material is fine-grained with a heat treatment that limits precipitate growth, and little creep property data for this microstructure is available in the literature. In addition, the geometry and loading conditions apply a multiaxial stress state on the component, far from the conditions of uniaxial testing. For these reasons, an extensive experimental investigation is ongoing to aid in accurately assessing the durability of the SRG110 heater head. This investigation supplements uniaxial creep testing with pneumatic testing of heater head-like pressure vessels at design temperature with stress levels ranging from approximately the design stress to several times that. This paper presents experimental results, post-test microstructural analyses, and conclusions for four higher-stress, accelerated life tests. Analysts are using these results to calibrate deterministic and probabilistic analytical creep models of the SRG110 heater head.

Krause, David L. [National Aeronautics and Space Administration, Glenn Research Center, Cleveland, OH 44135 (United States); Kantzos, Pete T. [Ohio Aerospace Institute, NASA Glenn Research Center, Cleveland, OH 44135 (United States)

2006-01-20

313

ASSESSMENT OF THE PCFBC-EXPOSED AND ACCELERATED LIFE-TESTED CANDLE FILTERS  

SciTech Connect

Development of the hot gas filtration technology has been the focus of DOE/FETC and Siemens Westinghouse Power Corporation during the past twenty years. Systems development during this time has successfully lead to the generation and implementation of high temperature Siemens Westinghouse particulate filtration systems that are currently installed and are operational at Demonstration Plant sites, and which are ready for installation at commercial plant sites. Concurrently, materials development has advanced the use of commercially available oxide- and nonoxide-based monoliths, and has fostered the manufacture and use of second generation, oxide-based, continuous fiber reinforced ceramic composites and filament wound materials. This report summarizes the material characterization results for commercially available and second generation filter materials tested in Siemens Westinghouse's advanced, high temperature, particulate removal system at the Foster Wheeler, pressurized circulating fluidized-bed combustion, pilot-scale test facility in Karhula, Finland, and subsequent extended accelerated life testing of aged elements in Siemens Westinghouse pressurized fluidized-bed combustion simulator test facility in Pittsburgh, PA. The viability of operating candle filters successfully for over 1 year of service life has been shown in these efforts. Continued testing to demonstrate the feasibility of acquiring three years of service operation on aged filter elements is recommended.

M.A. Alvin

1999-09-30

314

Accelerated in vitro durability testing of nonvascular Nitinol stents based on the electrical potential sensing method  

NASA Astrophysics Data System (ADS)

In this paper, we report an evaluation of the performance of a new stent durability tester based on the electrical potential sensing method through accelerated in vitro testing of six different nonvascular Nitinol stents simulating physiological conditions. The stents were subjected to a pulsatile loading of 33 Hz for a total of 62,726,400 cycles, at constant temperature and pressure of 35±0.5 °C and 120±4 mmHg, respectively. The electrical potential of each stent was measured in real-time and monitored for any changes in readings. After conducting test-to-fracture tests, the stents were visually checked, and by scanning electron microscopy. A sudden electrical potential drop in the readings suggests a fracture has occurred, and the only two instances of fracture in our present results were correctly determined by our present device, with the fractures confirmed visually after the test. The excellent performance of our new method shows good potential for a highly reliable and applicable in vitro durability testing for different kinds and sizes of metallic stents.

Park, Chan-Hee; Tijing, Leonard D.; Pant, Hem Raj; Kim, Tae-Hyung; Amarjargal, Altangerel; Kim, Han Joo; Kim, Cheol Sang

2013-09-01

315

Temperature and current accelerated lifetime conditions and testing of laser diodes for ESA BepiColombo space mission  

NASA Astrophysics Data System (ADS)

System designers and end users of diode pumped solid state lasers often require knowledge of the operability limits of QCW laser diode pump sources and their predicted reliability performance as a function of operating conditions. Accelerated ageing at elevated temperatures, duty cycles and/or currents allows extended lifetime testing of diode stacks to be executed on compressed timescales with high confidence. We present a novel, time-efficient technique for the determination of accelerated lifetime test conditions using degradation rate data, rather than the traditionally used failures against time data. To assess the effect of thermally accelerated ageing, 4 groups of 4 stacks each were operated for 60 million pulses at different temperature stress levels by varying the pulse repetition rate from 100Hz to 250Hz. The measured power degradation rates fitted to an Arrhenius type model, result in activation energy of 0.47- 0.74eV, apparently indicating two thermally activated degradation modes with different activation energies. Similarly, for current accelerated ageing, another 4 groups of 4 stacks were tested at operation currents from 120A to 150A. The optical power degradation rates due to current stress follow a power law behavior with a current acceleration factor of 1.7. The obtained acceleration parameters allowed considerable reduction of the lifetime test duration, which would have otherwise taken an unacceptably long time under nominal operating conditions. The successful results of the accelerated lifetime have been a major milestone enabling qualification of SCD stacks as pump sources for the laser altimeter in ESA Bepi-Colombo space mission. The presented reliability analysis allows life test qualification programs to be accelerated for generic QCW stacks and their lifetime to be predicted in various operating environments.

Klumel, Genady; Karni, Yoram; Cohen, Shalom; Rech, Markus; Weidlich, Kai

2011-02-01

316

Long-Term Reliability of SiGe/Si HBTs From Accelerated Lifetime Testing  

NASA Technical Reports Server (NTRS)

Accelerated lifetime tests were performed on double-mesa structure Si(0.7)Ge(0.3)/Si npn heterojunction bipolar transistors, grown by molecular beam epitaxy, in the temperature range of 175 C-275 C. The transistors (with 5x20 sq micron emitter area) have DC current gains approx. 40-50 and f(sub T) and f(sub max) of up to 22 GHz and 25 GHz, respectively. It is found that a gradual degradation in these devices is caused by the recombination enhanced impurity diffusion (REID) of boron atoms from the p-type base region and the associated formation of parasitic energy barriers to electron transport from the emitter to collector layers. This REED has been quantitatively modeled and explained, to the first order of approximation, and the agreement with the measured data is good. The mean time to failure (MTTF) of these devices at room temperature under 1.35 x 10(exp 4) A/sq cm current density operation is estimated from the extrapolation of the Arrhenius plots of device lifetime versus reciprocal temperature. The results of the reliability tests offer valuable feedback for SiGe heterostructure design in order to improve the long-term reliability of the devices and circuits made with them. Hot electron induced degradation of the base-emitter junction was also observed during the accelerated lifetime testing. In order to improve the HBT reliability endangered by the hot electrons, deuterium sintered techniques have been proposed. The preliminary results from this study show that a deuterium-sintered HBT is, indeed, more resistant to hot-electron induced base-emitter junction degradation.

Bhattacharya, Pallab

2001-01-01

317

Performance report on the ground test accelerator radio-frequency quadrupole  

SciTech Connect

The Ground Test Accelerator (GTA) uses a radio-frequency quadrupole (RFQ) to bunch and accelerate a 35 keV input beam to a final energy of 2.5 MeV. Most measured parameters of the GTA RFQ agreed with simulated predictions. The relative shape of the transmission versus the vane-voltage relationship and the Courant-Snyder (CS) parameters of the output beam`s transverse and longitudinal phase spaces agreed well with predictions. However, the transmission of the RFQ was significantly lower than expected. Improved simulation studies included image charges and multipole effects in the RFQ. Most of the predicted properties of the RFQ, such as input matched-beam conditions and output-beam shapes were unaffected by these additional effects. However, the comparison of measured with predicted absolute values of transmitted beam was much improved by the inclusion of these effects in the simulations. The comparison implied a value for the input emittance that is consistent with measurements.

Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Brown, S.; Cole, R.; Connolly, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B. [and others

1994-09-01

318

Fatigue-test acceleration with flight-by-flight loading and heating to simulate supersonic-transport operation  

NASA Technical Reports Server (NTRS)

Possibilities for reducing fatigue-test time for supersonic-transport materials and structures were studied in tests with simulated flight-by-flight loading. In order to determine whether short-time tests were feasible, the results of accelerated tests (2 sec per flight) were compared with the results of real-time tests (96 min per flight). The effects of design mean stress, the stress range for ground-air-ground cycles, simulated thermal stress, the number of stress cycles in each flight, and salt corrosion were studied. The flight-by-flight stress sequences were applied to notched sheet specimens of Ti-8Al-1Mo-1V and Ti-6Al-4V titanium alloys. A linear cumulative-damage analysis accounted for large changes in stress range of the simulated flights but did not account for the differences between real-time and accelerated tests. The fatigue lives from accelerated tests were generally within a factor of two of the lives from real-time tests; thus, within the scope of the investigation, accelerated testing seems feasible.

Imig, L. A.; Garrett, L. E.

1973-01-01

319

Calculating Nozzle Side Loads using Acceleration Measurements of Test-Based Models  

NASA Technical Reports Server (NTRS)

As part of a NASA/MSFC research program to evaluate the effect of different nozzle contours on the well-known but poorly characterized "side load" phenomena, we attempt to back out the net force on a sub-scale nozzle during cold-flow testing using acceleration measurements. Because modeling the test facility dynamics is problematic, new techniques for creating a "pseudo-model" of the facility and nozzle directly from modal test results are applied. Extensive verification procedures were undertaken, resulting in a loading scale factor necessary for agreement between test and model based frequency response functions. Side loads are then obtained by applying a wide-band random load onto the system model, obtaining nozzle response PSD's, and iterating both the amplitude and frequency of the input until a good comparison of the response with the measured response PSD for a specific time point is obtained. The final calculated loading can be used to compare different nozzle profiles for assessment during rocket engine nozzle development and as a basis for accurate design of the nozzle and engine structure to withstand these loads. The techniques applied within this procedure have extensive applicability to timely and accurate characterization of all test fixtures used for modal test.A viewgraph presentation on a model-test based pseudo-model used to calculate side loads on rocket engine nozzles is included. The topics include: 1) Side Loads in Rocket Nozzles; 2) Present Side Loads Research at NASA/MSFC; 3) Structural Dynamic Model Generation; 4) Pseudo-Model Generation; 5) Implementation; 6) Calibration of Pseudo-Model Response; 7) Pseudo-Model Response Verification; 8) Inverse Force Determination; 9) Results; and 10) Recent Work.

Brown, Andrew M.; Ruf, Joe

2007-01-01

320

Cryogenic test facility of superconducting magnets for the accelerator complex NICA  

NASA Astrophysics Data System (ADS)

The new accelerator complex NICA is being constructed on the basis of the existing superconducting synchrotron Nuclotron at JINR. NICA will consist of 3 rings of superconducting magnets: the Nuclotron, a booster synchrotron and a two-aperture collider ring. Superconducting dipole and quadrupole magnets for the NICA complex will be manufactured and tested at the new test facility. All the magnets contain a cold iron yoke and saddle-shaped superconducting windings made of the hollow NbTi composite superconducting cable refrigerated by two-phase helium flow at 4.5 K. The cryogenic system of the new facility is based on helium refrigerators with excess return flow. The scheme of the cryogenic testing area of the test facility is presented. A mathematical model of the cooling-down processes of the magnets was developed based on the experimental data for the prototypes of the booster and collider superconducting magnets. The calculated parameters allow us having a shorter time of cooling-down and warming-up of the magnets, thus reaching the necessary productivity of the facility.

Nikiforov, D.; Agapov, N.; Khodzhibagiyan, H.; Emelianov, N.; Korolev, V.

2014-05-01

321

Corrosion characterization of durable silver coatings by electrochemical impedance spectroscopy and accelerated environmental testing.  

PubMed

Highly reflective front-surface silver mirrors are needed for many optical applications. While various protective dielectric coating schemes have been developed, the long-term durability of Ag mirrors is still of great concern in the optics community for a variety of applications under harsh environments. The corrosion protection behavior of a SiNx-coated silver-mirror coating scheme was tested with electrochemical impedance spectroscopy (EIS) and accelerated environmental testing, including humidity and salt fog tests. The EIS data obtained were fitted with different equivalent circuit models. The results suggested that the 100A thick SiNx coating produced by rf magnetron sputtering was porous and acted as a leaky capacitor on the Ag film, whereas the addition of a NiCrNx interlayer as thin as 3A between SiNx and Ag films resulted in a much denser SiNx coating with a low-frequency impedance value of 2 orders of magnitude higher than that without the interlayer. Humidity and salt fog testing of different silver coatings showed similar results. The 100A SiNx/3A-NiCrNx/Ag coating exhibited excellent corrosion resistance against the corrosive environments used in this study. PMID:16539267

Chu, Chung-Tse; Fuqua, Peter D; Barrie, James D

2006-03-01

322

The use of the high-frequency fatigue test as a method for accelerated estimation of endurance characteristics of materials  

NASA Astrophysics Data System (ADS)

It is shown that the methods for accelerated estimation of endurance characteristics of materials involving high-frequency cyclic loading have certain advantages as compared to other "accelerated" methods. The effect of cyclic loading frequency on the endurance limit is considered for a number of metallic materials and the possibility is shown to plot a single fatigue curve independent of the number of cycles. The most promising areas of application for high-frequency fatigue test methods are noted.

Kuz'menko, V. A.

323

Degradation in silicon solar cells caused by the formation of Schottky barrier contacts during accelerated testing  

SciTech Connect

When p+/n silicon solar cells having a lightly doped substrate, i.e. no back surface field, were subjected to accelerated stress testing an irregularity occurred in the VI characteristic along with the resulting loss of power output. Evidence is presented which indicates that this is due to formation of a rectifying Schottky barrier between the back metal contact and the silicon, possibly as a result of the dissociation of water vapor molecules and the subsequent diffusion of hydrogen to the metal-silicon interface. When encapsulated cells were stressed, those having a steel substrate showed less degradation than unencapsulated cells while those with Tedlar or foil substrates showed more. This rather surprising result can also be explained in terms of the hydrogen diffusion phenomenon.

Lathrop, J.W.; Davis, C.W.; Misiakos, K.

1984-05-01

324

Experimental Test For Novel Vacuum Laser Acceleration at the BNL-ATF  

SciTech Connect

A recently developed theoretical model revealed that the injection electrons with low-energy (5-20 MeV) and small incident angle ({theta}{approx}0.1) relative to the laser propagation direction can be captured and significantly accelerated in a strong laser field (a0 {>=}4), and the energy gain can reach a few GeV with a0 >100. To verify the novel VLA mechanics, we propose to use the BNL-ATF Terawatt CO2 laser and a high-brightness electron beam to carry out a proof-of-principle beam experiment. Conditions for the beam test are investigated. Simulation results with practical ATF parameters are presented. Experiment setup including the laser injection optics and electron extraction system is described. Diagnostics to measure angular distribution and energy spectrum of output electrons are discussed.

Zhou, F.; Cline, D.; Shao, L. [University of California at Los Angeles, CA 90095 (United States); Ho, Y. [Fudan University, Shanghai (China); Kusche, K.; Pogorelsky, I.; Yakimenko, V. [Brookhaven National Laboratory, Upton, NY 11973 (United States)

2004-12-07

325

RF system description for the ground test accelerator radio-frequency quadrupole  

NASA Astrophysics Data System (ADS)

This paper describes the RF system being used to provide RF power and to control the cavity field used for the ground test accelerator (GTA) radio-frequency quadrupole (RFQ). The RF system consists of a low-level RF (LLRF) control system that uses a tetrode as a high-power amplifier (HPA) as part of its plant to deliver up to 300 kW of peak power to the RFQ at a 2 percent duty factor. The LLRF control system implements in-phase and quadrature (I&Q) control to maintain the cavity field within tolerances of 0.5 percent in amplitude and 0.5 degrees in phase in the presence of beam-induced instabilities. This paper describes the identified components and presents measured performance data. The user interface with the systems is described, and cavity field measurements are included.

Regan, A. H.; Brittain, D.; Rees, D. E.; Ziomek, D.

1992-08-01

326

Rf system description for the ground test accelerator radio-frequency quadrupole  

SciTech Connect

This paper describes the RF system being used to provide RF power and to control the cavity field used for the ground test accelerator (GTA) radio-frequency quadrupole (RFQ). The RF system consists of a low-level RF (LLRF) control system that uses a tetrode as a high-power amplifier (HPA) as part of its plant to deliver up to 300 kW of peak power to the RFQ at a 2% duty factor. The LLRF control system implements in-phase and quadrature (I&Q) control to maintain the cavity field within tolerances of 0.5% in amplitude and 0.5{degrees} in phase in the presence of beam-induced instabilities. This paper describes the identified components and presents measured performance data. The user interface with the systems is described, and cavity field measurements are included.

Regan, A.H.; Brittain, D.; Rees, D.E.; Ziomek, D.

1992-09-01

327

Rf system description for the ground test accelerator radio-frequency quadrupole  

SciTech Connect

This paper describes the RF system being used to provide RF power and to control the cavity field used for the ground test accelerator (GTA) radio-frequency quadrupole (RFQ). The RF system consists of a low-level RF (LLRF) control system that uses a tetrode as a high-power amplifier (HPA) as part of its plant to deliver up to 300 kW of peak power to the RFQ at a 2% duty factor. The LLRF control system implements in-phase and quadrature (I Q) control to maintain the cavity field within tolerances of 0.5% in amplitude and 0.5{degrees} in phase in the presence of beam-induced instabilities. This paper describes the identified components and presents measured performance data. The user interface with the systems is described, and cavity field measurements are included.

Regan, A.H.; Brittain, D.; Rees, D.E.; Ziomek, D.

1992-01-01

328

Accelerated test methods to determine the long-term behavior of FRP composite structures: environmental effects  

SciTech Connect

Technical literature on the subject of environmental exposure effects related to determining accelerated test methods for the prediction of long-term performance of FRP composite materials for highway structural applications is reviewed in this paper. Effects of environmental exposure of a chemical and a thermal nature on fiber-reinforced polymer (FRP) composites are considered. Such exposures include temperature, moisture and chemicals in liquid solutions or in gaseous mixtures. The effects include the changes in the physical and mechanical properties of the composite materials. Such changes are typically related to the degradation or deterioration of the composite material. Synergistic effects of mechanical load and exposure are also reviewed. The review is divided in topics entitled Materials, Exposure Conditions, Experimental Techniques, Failure Mechanisms and Theoretical Modeling. 81 refs.

Bank, L.C.; Gentry, T.R.; Barkatt, A. [Catholic Univ. of America, Washington, DC (United States)

1995-06-01

329

High power testing of the prototype accelerating cavity (352 MHz) for the advanced photon source (APS)  

SciTech Connect

Measurement of the higher order of modes of a prototype single-cell 352 MHz cavity for the APS 7-Gev storage ring will be presented and discussed. A cavity made from solid copper was built according to dimensions derived from URMEL program runs. The longitudinal and transverse impedances of the first several higher order modes have been measured using various-shaped metal beads. High power ( > 60 kW) testing of the cavity will be described along with design and operation of dampers for those modes with coupled-bunch instability threshold currents under 300 milliamperes, the maximum circulating positron current. Low power level rf circuitry for timing and synchronization of the various APS accelerators and storage ring will be described.

Bridges, J.F.; Kang, Y.W.; Kustom, R.L.; Primdahl, K.

1992-07-01

330

High power testing of the prototype accelerating cavity (352 MHz) for the advanced photon source (APS)  

SciTech Connect

Measurement of the higher order of modes of a prototype single-cell 352 MHz cavity for the APS 7-Gev storage ring will be presented and discussed. A cavity made from solid copper was built according to dimensions derived from URMEL program runs. The longitudinal and transverse impedances of the first several higher order modes have been measured using various-shaped metal beads. High power ( > 60 kW) testing of the cavity will be described along with design and operation of dampers for those modes with coupled-bunch instability threshold currents under 300 milliamperes, the maximum circulating positron current. Low power level rf circuitry for timing and synchronization of the various APS accelerators and storage ring will be described.

Bridges, J.F.; Kang, Y.W.; Kustom, R.L.; Primdahl, K.

1992-01-01

331

Accelerated testing of metal foil tape joints and their effect of photovoltaic module reliability  

NASA Astrophysics Data System (ADS)

A program is underway at Sandia National Laboratories to predict long-term reliability of photovoltaic (PV) systems. The vehicle for the reliability predictions is a Reliability Block Diagram (RBD), which models system behavior. Because this model is based mainly on field failure and repair times, it can be used to predict current reliability, but it cannot currently be used to accurately predict lifetime. In order to be truly predictive, physics-informed degradation processes and failure mechanisms need to be included in the model. This paper describes accelerated life testing of metal foil tapes used in thin-film PV modules, and how tape joint degradation, a possible failure mode, can be incorporated into the model.

Sorensen, N. Robert; Quintana, Michael A.; Puskar, Joseph D.; Lucero, Samuel J.

2009-08-01

332

Final safety analysis report for the Ground Test Accelerator (GTA), Phase 2  

SciTech Connect

This document is the third volume of a 3 volume safety analysis report on the Ground Test Accelerator (GTA). The GTA program at the Los Alamos National Laboratory (LANL) is the major element of the national Neutral Particle Beam (NPB) program, which is supported by the Strategic Defense Initiative Office (SDIO). A principal goal of the national NPB program is to assess the feasibility of using hydrogen and deuterium neutral particle beams outside the Earth`s atmosphere. The main effort of the NPB program at Los Alamos concentrates on developing the GTA. The GTA is classified as a low-hazard facility, except for the cryogenic-cooling system, which is classified as a moderate-hazard facility. This volume consists of appendices C through U of the report

NONE

1994-10-01

333

Extremely low vertical-emittance beam in accelerator-test facility at KEK  

SciTech Connect

Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping rings which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1 percent of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10{sup -8} rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance.

Kubo, K.; Akemoto, M.; Anderson, S.; Aoki, T.; Araki, S.; Bane, K.L.F.; Blum, P.; Corlett, J.; Dobashi, K.; Emma, P.; Frisch, J.; Fukuda, M.; Guo, Z.; Hasegawa, K.; Hayano, H.; Higo, T.; Higurashi, A.; Honda, Y.; Iimura, T.; Imai, T.; Jobe, K.; Kamada, S.; Karataev, P.; Kashiwagi, S.; Kim, E.; Kobuki, T.; Kotseroglou, T.; Kurihara, Y.; Kuriki, M.; Kuroda, R.; Kuroda, S.; Lee, T.; Luo, X.; McCormick, D.J.; McKee, B.; Mimashi, T.; Minty, M.; Muto, T.; Naito, Takashi; Naumenko, G.; Nelson, J.; Nguyen, M.N.; Oide, K.; Okugi, T.; Omori, T.; Oshima, T.; Pei, G.; Potylitsyn, A.; Qin, Q.; Raubenheimer, T.; Ross, M.; Sakai, H.; Sakai, I.; Schmidt, F.; Slaton, T.; Smith, H.; Smith, S.; Suzuki, Toshikazu; Takano, M.; Takeda, Seishi; Terunuma, N.; Toge, N.; Turner, J.; Urakawa, J.; Vogel, V.; Woodley, M.; Yocky, J.; Young, A.; Zimmerman, F.; ATF Collaboration

2002-05-13

334

Cavity beam position monitor system for the Accelerator Test Facility 2  

NASA Astrophysics Data System (ADS)

The Accelerator Test Facility 2 (ATF2) is a scaled demonstrator system for final focus beam lines of linear high energy colliders. This paper describes the high resolution cavity beam position monitor (BPM) system, which is a part of the ATF2 diagnostics. Two types of cavity BPMs are used, C-band operating at 6.423 GHz, and S-band at 2.888 GHz with an increased beam aperture. The cavities, electronics, and digital processing are described. The resolution of the C-band system with attenuators was determined to be approximately 250 nm and 1?m for the S-band system. Without attenuation the best recorded C-band cavity resolution was 27 nm.

Kim, Y. I.; Ainsworth, R.; Aryshev, A.; Boogert, S. T.; Boorman, G.; Frisch, J.; Heo, A.; Honda, Y.; Hwang, W. H.; Huang, J. Y.; Kim, E.-S.; Kim, S. H.; Lyapin, A.; Naito, T.; May, J.; McCormick, D.; Mellor, R. E.; Molloy, S.; Nelson, J.; Park, S. J.; Park, Y. J.; Ross, M.; Shin, S.; Swinson, C.; Smith, T.; Terunuma, N.; Tauchi, T.; Urakawa, J.; White, G. R.

2012-04-01

335

Simulation and steering in the Intertank matching section of the ground test accelerator  

SciTech Connect

The Intertank Matching Section (IMS) of the Ground Test Accelerator (GTA) is a short (36 cm) beamline designed to match the Radio Frequency Quadrupole (RFQ) exit beam into the first Drift Tube LINAC (DTL) tank. The IMS contains two steering quadrupoles (SMQS) and four variable-field focusing quads (VFQs). The SMQs are fixed strength permanent magnet quadrupoles on mechanical actuators capable of transverse movement for the purpose of steerng the beam. Also contained in the IMS are two RF cavities for longitudinal matching. A comparison of measured to calculated steering coefficients has been made for data aken in 3 different tunes of the IMS transport line. (AIP) {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Yuan, V.W.; Bolme, G.O.; Erickson, J.L.; Johnson, K.F.; Mottershead, C.T.; Sander, O.R.; Smith, M.T. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1995-05-05

336

Final safety analysis report for the Ground Test Accelerator (GTA), Phase 2  

SciTech Connect

This document is the first volume of a 3 volume safety analysis report on the Ground Test Accelerator (GTA). The GTA program at the Los Alamos National Laboratory (LANL) is the major element of the national Neutral Particle Beam (NPB) program, which is supported by the Strategic Defense Initiative Office (SDIO). A principal goal of the national NPB program is to assess the feasibility of using hydrogen and deuterium neutral particle beams outside the Earth`s atmosphere. The main effort of the NPB program at Los Alamos concentrates on developing the GTA. The GTA is classified as a low-hazard facility, except for the cryogenic-cooling system, which is classified as a moderate-hazard facility. This volume consists of an introduction, summary/conclusion, site description and assessment, description of facility, and description of operation.

NONE

1994-10-01

337

On the Use of Accelerated Test Methods for Characterization of Advanced Composite Materials  

NASA Technical Reports Server (NTRS)

A rational approach to the problem of accelerated testing for material characterization of advanced polymer matrix composites is discussed. The experimental and analytical methods provided should be viewed as a set of tools useful in the screening of material systems for long-term engineering properties in aerospace applications. Consideration is given to long-term exposure in extreme environments that include elevated temperature, reduced temperature, moisture, oxygen, and mechanical load. Analytical formulations useful for predictive models that are based on the principles of time-based superposition are presented. The need for reproducible mechanisms, indicator properties, and real-time data are outlined as well as the methodologies for determining specific aging mechanisms.

Gates, Thomas S.

2003-01-01

338

Tensile strength at elevated temperature and its applicability as an accelerated testing methodology for unidirectional composites  

NASA Astrophysics Data System (ADS)

The applicability of a macroscopic time-temperature superposition principle (TTSP) to unidirectional composite strength is discussed based on the microscopic Simultaneous Fiber-Failure (SFF) model that has been presented by Koyanagi et al. (J. Compos. Mater. 43:1901-1914, 2009a). The SFF model estimates composite strengths as functions of fiber, matrix, and interface strengths. This paper first investigates the applicability of SFF to the complicated temperature dependence of composite strengths, i.e., one composite exhibits significant temperature dependence and another does not, considering the temperature dependence of the components, which results in successful estimations for the two composite systems used in the present study. The long-term durability predicted by the SFF and that predicted by the TTSP are then compared. They typically correspond to each other in various cases; accelerated testing methodology (ATM) employing TTSP is thus proved to be valid from the micromechanical viewpoint, assuming the SFF applicability.

Koyanagi, Jun; Nakada, Masayuki; Miyano, Yasushi

2012-02-01

339

A Review of Accelerated Test Methods for Predicting the Image Life of Digitally-Printed Photographs - Part II  

Microsoft Academic Search

This paper gives an overview of the various factors affecting the permanence of digitally-printed photographs. 1 Accelerated test methods are discussed, with emphasis on light stability tests specified with past and current ANSI and ISO Standards, future ISO Standards, and the \\

Henry Wilhelm

2004-01-01

340

Rail Profile Grinding on High-Hardness Premium Rail at the Facility for Accelerated Service Testing. Research Results.  

National Technical Information Service (NTIS)

Since 2003, Transportation Technology Center, Inc. (TTCI) has been evaluating the effects of rail grinding on the performance of high-hardness premium rail at the Facility for Accelerated Service Testing (FAST). A 6-degree test curve is divided into three...

2008-01-01

341

Evaluation of stone durability using a combination of ultrasound, mechanical and accelerated aging tests  

NASA Astrophysics Data System (ADS)

The durability of a rock when exposed to decay agents is an important criterion when assessing its quality as a building material. Our study focuses on six varieties of natural stone (two limestones, one dolostone, one travertine and two sandstones) that are widely used in both new and historical buildings. In order to assess their quality, we measured and characterized their dynamic elastic properties using ultrasounds, we measured their compressive strength using the uniaxial compression test and we evaluated their durability by means of accelerated aging tests (freeze-thaw and salt crystallization). In order to get a full picture of the decay suffered by the different stones, we determined the composition and amount of the clay fraction of the six stones. We also observed small fragments subjected to the salt crystallization test under an environmental scanning electron microscope to study any textural change and measured the changes of colour on the surface with a spectrophotometer. Finally, we analysed the pore system of the stones before and after their deterioration using mercury injection porosimetry. We then compared the results for the different stones and found that dolostone obtained the best results, while the two limestones proved to be the least durable and had the lowest compressive strength.

Molina, E.; Cultrone, G.; Sebastián, E.; Alonso, F. J.

2013-06-01

342

Some scale estimators and lack-of-fit tests for the censored two-sample accelerated life model.  

PubMed

Some new scale estimators for the censored two-sample accelerated life model are introduced. They are zeros of some integrated weighted difference between the two cumulative hazard estimators. These estimators are asymptotically normal. The weight is chosen to result in estimators whose asymptotic variances do not involve the destiny functions and can be easily estimated. This provides a fast and simple means of statistical inference in the censored two-sample accelerated life model. Through investigating the asymptotic relative efficiency at some important censoring submodels and the finite example behaviors in various numerical studies, we obtain some estimators with very competitive performance. From the new class of scale estimators, some lack-of-fit tests for the accelerated life model are also derived. These tests are related to Gill-Schumacher type tests and require little extra computing time once the estimator is obtained. The estimators and tests are illustrated in two applications. For a vaginal cancer data set for rats, the effect of pretreatment regime was found to be well described by the two-sample accelerated life model. For a data set on progression of ovarian cancer, it was found that the effect of grade of disease could not be described either by the two-sample proportional hazards model or the two-sample accelerated life model. PMID:9750250

Yang, S

1998-09-01

343

Tests of GNSS receivers for dynamic, high sample rate response using controlled sources of displacement, velocity, and acceleration  

NASA Astrophysics Data System (ADS)

Global Navigational Satellite Systems (GNSS) are being employed to augment seismic instrumentation to record large, dynamic displacements and accelerations from large earthquakes. To date, however, there have been only a few tests that independently characterize the GNSS at frequencies and displacements that occur during large earthquakes (a number of error sources might influence such GPS result, including loss of lock or bias in signal tracking loops). Many of these tests consist of replaying the observed accelerations for select earthquakes recorded by seismic instruments through a shake-table on which a GNSS antenna is attached. Then the derived displacement from the accelerometer is compared with the displacement estimated from the GNSS system, or the GNSS derived acceleration is compared with the acceleration of the shake table. Neither comparison is optimal since derived quantities are used, and in particular, displacements derived from acceleration data have many sources of error at long periods. Another approach is to test the response of the GNSS receiver using a GNSS-simulator where synthetic GNSS signals are generated that mimic the signals that are actually received. Ebinuma and Kato (Earth Planet Space, 2012) describe a series of controlled tests using this approach with three different GNSS receivers. As a "real world" test, we performed similar experiments using a shake table, in open air with normal views of GNSS satellites, with controlled displacement inputs but, importantly, measured the displacement and acceleration of this table independently. We used a single-axis shake-table having up to 40 cm horizontal displacement and independently measured the position of the stage to better than 0.1 mm (from table servo loop optical reference; accelerations measured by accelerometers attached to moving part of stage). We tested five different GNSS receivers recording both GPS and GLONASS at 50 samples per second (sps), with the exception of the Trimble NetRS, which is widely used in the Plate Boundary Observatory, that recorded 10 sps GPS data only. To determine the system response, we tested each receiver using both a rounded Heaviside (step) function (40, 10, and 2 cm) and a variety of sinusoid signals from 0.2 to 20 Hz spanning a range in accelerations between 0.02 to 3.0 g. The results of these real-world tests will be compared with similar measurements by Ebinuma and Kato (2012), who used a GPS simulator.

Langbein, J. O.; Evans, J. R.; Blume, F.; Johanson, I. A.

2012-12-01

344

Testing MOND over a Wide Acceleration Range in X-Ray Ellipticals  

NASA Astrophysics Data System (ADS)

The gravitational fields of two isolated ellipticals, NGC 720 and NGC 1521, have been recently measured to very large galactic radii (˜100 and ˜200kpc), assuming hydrostatic balance of the hot gas enshrouding them. They afford, for the first time to my knowledge, testing modified Newtonian dynamics (MOND) in ellipticals with force and quality that, arguably, approach those of rotation-curve tests in disk galaxies. In the context of MOND, it is noteworthy that the measured accelerations span a wide range, from more than 10a0 to about 0.1a0, unprecedented in individual ellipticals. I find that MOND predicts correctly the measured dynamical mass runs (apart from a possible minor tension in the inner few kpc of NGC 720, which might be due to departure from hydrostatic equilibrium): The predicted mass discrepancy increases outward from none near the center, to ˜10 at the outermost radii. The implications for the MOND-versus-dark-matter controversy go far beyond the simple fact of two more galaxies conforming to MOND.

Milgrom, Mordehai

2012-09-01

345

Analysis of transmitted optical spectrum enabling accelerated testing of CPV designs  

NASA Astrophysics Data System (ADS)

Concentrated photovoltaics (CPV) has recently gained interest based on its scalability and expected low levelized cost of electricity. The reliability of materials used in CPV systems, however, is not well established. The current qualification test for photodegradation of CPV modules includes only real-time ultraviolet (UV) exposure, i.e. methods for accelerated UV testing have not been developed. Therefore, the UV and infrared (IR) spectra transmitted through representative optical systems is evaluated in this paper. The measurements of concentrating optics are used to assess expected optical performance as well as to understand how to quantify damaging optical exposure. Optical properties (transmittance, refractive index, reflectance, and absorptance) of candidate materials are identified. The dose and flux analysis here identifies the increased significance of IR (as opposed to UV) exposure for CPV systems, particularly for the most concentrating systems. For these, the UV dose may not greatly exceed the unconcentrated global solar condition, but the thermal load scales nearly directly with the geometric concentration.

Miller, David C.; Kempe, Michael D.; Kennedy, Cheryl E.; Kurtz, Sarah R.

2009-08-01

346

Accelerated exposure tests of encapsulated Si solar cells and encapsulation materials  

SciTech Connect

We have conducted a series of accelerated exposure test (AET) studies for various crystalline-Si (c-Si) and amorphous-Si (a-Si) cell samples that were encapsulated with different superstrates, pottants, and substrates. Nonuniform browning patterns of ethylene vinyl acetate (EVA) pottants were observed for glass/EVA/glass-encapsulated c-Si cell samples under solar simulator exposures at elevated temperatures. The polymer/polymer-configured laminates with Tedlar or Tefzel did not discolor because of photobleaching reactions, but yellowed with polyester or nylon top films. Delamination was observed for the polyester/EVE layers on a-Si minimodules and for a polyolefin-based thermoplastic pottant at high temperatures. For all tested c-Si cell samples, irregular changes in the current-voltage parameters were observed that could not be accounted for simply by the transmittance changes of the superstrate/pottant layers. Silicone-type adhesives used under UV-transmitting polymer top films were observed to cause greater cell current/efficiency loss than EVA or polyethylene pottants. {copyright} {ital 1999 American Institute of Physics.}

Pern, F.J.; Glick, S.H. [Engineering and Reliability Division, National Center for Photovoltaics, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States)

1999-03-01

347

Accelerated exposure tests of encapsulated Si solar cells and encapsulation materials  

NASA Astrophysics Data System (ADS)

We have conducted a series of accelerated exposure test (AET) studies for various crystalline-Si (c-Si) and amorphous-Si (a-Si) cell samples that were encapsulated with different superstrates, pottants, and substrates. Nonuniform browning patterns of ethylene vinyl acetate (EVA) pottants were observed for glass/EVA/glass-encapsulated c-Si cell samples under solar simulator exposures at elevated temperatures. The polymer/polymer-configured laminates with Tedlar or Tefzel did not discolor because of photobleaching reactions, but yellowed with polyester or nylon top films. Delamination was observed for the polyester/EVE layers on a-Si minimodules and for a polyolefin-based thermoplastic pottant at high temperatures. For all tested c-Si cell samples, irregular changes in the current-voltage parameters were observed that could not be accounted for simply by the transmittance changes of the superstrate/pottant layers. Silicone-type adhesives used under UV-transmitting polymer top films were observed to cause greater cell current/efficiency loss than EVA or polyethylene pottants.

Pern, F. J.; Glick, S. H.

1999-03-01

348

Design and high order optimization of the Accelerator Test Facility lattices  

NASA Astrophysics Data System (ADS)

The Accelerator Test Facility 2 (ATF2) aims to test the novel chromaticity correction scheme which is implemented in the final focus systems of future linear colliders such as the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). The ATF2 nominal and ultralow ?* lattices are designed to vertically focus the beam at the focal point, or usually referred to as interaction point (IP), down to 37 and 23 nm, respectively. The vertical chromaticities of the nominal and ultralow ?* lattices are comparable to those of ILC and CLIC, respectively. When the measured multipole components of the ATF2 magnets are considered in the simulations, the evaluated spot sizes at the IP are well above the design values. In this paper we describe the analysis of the high order aberrations that allows identifying the sources of the observed beam size growth. In order to recover the design spot sizes three solutions are considered, namely final doublet replacement, octupole insertion, and optics modification. Concerning the future linear collider projects, the consequences of magnetic field errors of the focusing quadrupole magnet of the final doublet are also addressed.

Marin, E.; Tomás, R.; Bambade, P.; Kubo, K.; Okugi, T.; Tauchi, T.; Terunuma, N.; Urakawa, J.; Seryi, A.; White, G. R.; Woodley, M.

2014-02-01

349

Trajectory measurements and correlations in the final focus beam line at the KEK Accelerator Test Facility  

NASA Astrophysics Data System (ADS)

The Accelerator Test Facility 2 (ATF2) commissioning group aims to demonstrate the feasibility of the beam delivery system of the next linear colliders (ILC and CLIC) as well as to define and to test the tuning methods. As the design vertical beam sizes of the linear colliders are about few nanometers, the stability of the trajectory as well as the control of the aberrations are very critical. ATF2 commissioning started in December 2008, and thanks to submicron resolution beam position monitors (BPMs), it has been possible to measure the beam position fluctuation along the final focus of ATF2 during the 2009 runs. The optics was not the nominal one yet, with a lower focusing to make the tuning easier. In this paper, a method to measure the noise of each BPM every pulse, in a model-independent way, will be presented. A method to reconstruct the trajectory’s fluctuations is developed which uses the previously determined BPM resolution. As this reconstruction provides a measurement of the beam energy fluctuations, it was also possible to measure the horizontal and vertical dispersion function at each BPMs parasitically. The spatial and angular dispersions can be fitted from these measurements with uncertainties comparable with usual measurements.

Renier, Y.; Bambade, P.; Tauchi, T.; White, G. R.; Boogert, S.

2013-06-01

350

Image processing and computer controls for video profile diagnostic system in the ground test accelerator (GTA)  

SciTech Connect

This paper describes the application of video image processing to beam profile measurements on the Ground Test Accelerator (GTA). A diagnostic was needed to measure beam profiles in the intermediate matching section (IMS) between the radio-frequency quadrupole (RFQ) and the drift tube linac (DTL). Beam profiles are measured by injecting puffs of gas into the beam. The light emitted from the beam-gas interaction is captured and processed by a video image processing system, generating the beam profile data. A general purpose, modular and flexible video image processing system, imagetool, was used for the GTA image profile measurement. The development of both software and hardware for imagetool and its integration with the GTA control system (GTACS) will be discussed. The software includes specialized algorithms for analyzing data and calibrating the system. The underlying design philosophy of imagetool was tested by the experience of building and using the system, pointing the way for future improvements. The current status of the system will be illustrated by samples of experimental data.

Wright, R.M.; Zander, M.E.; Brown, S.K.; Sandoval, D.P.; Gilpatrick, J.D.; Gibson, H.E.

1992-09-01

351

Corrosion Testing in Support of the Accelerator Production of Tritium Program  

SciTech Connect

The Accelerator Production of Tritium Project is part of the United States Department of Energy strategy to meet the nation's tritium needs. The project involves the design of a proton beam accelerator, which will produce tritium through neutron/proton interaction with helium-3. Design, construction and operation of this one-of-a-kind facility will involve the utilization of a wide variety of materials exposed to unique conditions, including elevated temperature and high-energy mixed-proton and -neutron spectra. A comprehensive materials test program was established by the APT project which includes the irradiation of structural materials by exposure to high-energy protons and neutrons at the Los Alamos Neutron Science Center at the Los Alamos National Laboratory. Real-time corrosion measurements were performed on specially designed corrosion probes in water irradiated by an 800 MeV proton beam. The water test system provided a means for measuring water chemistry, dissolved hydroge n concentration, and the effects of water radiolysis and water quality on corrosion rate. The corrosion probes were constructed of candidate APT materials alloy 718, 316L stainless steel, 304L stainless steel, and 6061 Aluminum (T6 heat treatment), and alternate materials 5052 aluminum alloy, alloy 625, and C276. Real-time corrosion rates during proton irradiation increased with proton beam current. Efforts are continuing to determine the effect of proton beam characteristics and mixed-particle flux on the corrosion rate of materials located directly in the proton beam. This paper focuses on the real-time corrosion measurements of materials located in the supply stream and return stream of the water flow line to evaluate effects of long-lived radiolysis products and water chemistry on the corrosion rates of materials. In general, the corrosion rates for the out-of-beam probes were low and were affected mainly by water conductivity. The data indicate a water conductivity threshold e xists to minimize corrosion in the out-of-beam areas, especially for aluminum. The in-beam probes also revealed a water conductivity threshold but at a lower value compared to the out-of-beam probes.

Chandler, G.

2000-11-07

352

Life-time prediction of a chloroprene rubber (CR) O-ring using intermittent compression stress relaxation (CSR) and time-temperature superposition (TTS) Principle  

Microsoft Academic Search

Intermittent compression stress relaxation (CSR) testing was used to examine the degradation of a large scale chloroprene\\u000a rubber (CR) O-ring, rather than a reduced scale copy, as well as predict its life-time. An intermittent CSR jig was designed\\u000a by considering the O-ring’s environment during use. The testing allowed the observation of the effects of friction, heat loss\\u000a and stress relaxation

Jin Hyok Lee; Jong Woo Bae; Jung Su Kim; Tae Jun Hwang; Sung Doo Park; Sung Han Park; Tae Min Yeo; Wonho Kim; Nam-Ju Jo

2011-01-01

353

Evaluation of Pollution Characteristic of Polymer Insulating Material with Surface Nano-Coating by a New Automatic Artificial Pollution Acceleration Test System  

Microsoft Academic Search

We have so far performed multistress acceleration test (EdF Test:) for SiR (silicone rubber) insulators, which were found to still keep good hydrophobicity even after 5000 hour testing time equivalent to about 10 years for outdoor exposure test in a heavy polluted area [1]. The two tests' results indicate that one should consider non-soluble material in an accelerated pollution test

M. Higashikoji; M. Motoyama; S. Ohtsuka; M. Hikita; H. Ikeda; J. Gavillet; G. Ravel; E. Da Silva; M. Frechette

2008-01-01

354

Voxel Occlusion Testing: A Shadow Determination Accelerator for RaY Tracing  

Microsoft Academic Search

1. Abstract A shadow determination accelerator for ray tracing is presented. It is built on top of the uniform voxel traversal grid sfucture. The accelerator proves to be rather efficient' requires little additionai memory and the worst case scenarlo per shadow determination just reduces down to traditional voxel traversal. It can also be extended to model linear, area lights, as

Andrew Woo; John Amanatides

1990-01-01

355

Temperature and current accelerated lifetime conditions and testing of laser diodes for ESA BepiColombo space mission  

Microsoft Academic Search

System designers and end users of diode pumped solid state lasers often require knowledge of the operability limits of QCW laser diode pump sources and their predicted reliability performance as a function of operating conditions. Accelerated ageing at elevated temperatures, duty cycles and\\/or currents allows extended lifetime testing of diode stacks to be executed on compressed timescales with high confidence.

Genady Klumel; Yoram Karni; Shalom Cohen; Markus Rech; Kai Weidlich

2011-01-01

356

Accelerated thermal cycle test of acetamide, stearic acid and paraffin wax for solar thermal latent heat storage applications  

Microsoft Academic Search

1500 accelerated thermal cycle tests have been conducted to study the changes in latent heat of fusion and melting temperature of commercial grade acetamide, stearic acid and paraffin wax. It has been noticed that the stearic acid melts over a wide range of temperature, has shown two melting points and has large variations in latent heat of fusion. Paraffin wax

Atul Sharma; S. D Sharma; D Buddhi

2002-01-01

357

Anomalously increased oxygen reduction reaction activity with accelerated durability test cycles for platinum on thiolated carbon nanotubes.  

PubMed

We report an anomalous phenomenon in Pt supported on thiolated multi-walled carbon nanotubes (Pt-S-MWNT): oxygen reduction reaction (ORR) activity increases with accelerated durability test (ADT) cycles. Sub-nanometer-sized Pt clusters on S-MWNT were gradually agglomerated to an optimal size with ADT cycles, and finally showed increased ORR activity after the ADT. PMID:24275723

Kim, Tae-Jun; Kwon, Gihan; Kim, Yong-Tae

2014-01-18

358

Final safety analysis report for the Ground Test Accelerator (GTA), Phase 2  

SciTech Connect

This document is the second volume of a 3 volume safety analysis report on the Ground Test Accelerator (GTA). The GTA program at the Los Alamos National Laboratory (LANL) is the major element of the national Neutral Particle Beam (NPB) program, which is supported by the Strategic Defense Initiative Office (SDIO). A principal goal of the national NPB program is to assess the feasibility of using hydrogen and deuterium neutral particle beams outside the Earth`s atmosphere. The main effort of the NPB program at Los Alamos concentrates on developing the GTA. The GTA is classified as a low-hazard facility, except for the cryogenic-cooling system, which is classified as a moderate-hazard facility. This volume consists of failure modes and effects analysis; accident analysis; operational safety requirements; quality assurance program; ES&H management program; environmental, safety, and health systems critical to safety; summary of waste-management program; environmental monitoring program; facility expansion, decontamination, and decommissioning; summary of emergency response plan; summary plan for employee training; summary plan for operating procedures; glossary; and appendices A and B.

NONE

1994-10-01

359

Integration Testing of a Modular Discharge Supply for NASA's High Voltage Hall Accelerator Thruster  

NASA Technical Reports Server (NTRS)

NASA s In-Space Propulsion Technology Program is developing a high performance Hall thruster that can fulfill the needs of future Discovery-class missions. The result of this effort is the High Voltage Hall Accelerator thruster that can operate over a power range from 0.3 to 3.5 kW and a specific impulse from 1,000 to 2,800 sec, and process 300 kg of xenon propellant. Simultaneously, a 4.0 kW discharge power supply comprised of two parallel modules was developed. These power modules use an innovative three-phase resonant topology that can efficiently supply full power to the thruster at an output voltage range of 200 to 700 V at an input voltage range of 80 to 160 V. Efficiencies as high as 95.9 percent were measured during an integration test with the NASA103M.XL thruster. The accuracy of the master/slave current sharing circuit and various thruster ignition techniques were evaluated.

Pinero, Luis R.; Kamhawi, hani; Drummond, Geoff

2010-01-01

360

X-ray beam size measurements on the Advanced Test Accelerator  

SciTech Connect

The electron beam size has been determined on the Advanced Test Accelerator (ATA) by intercepting the beam with a target and measuring the resulting x-ray intensity as a function of time as the target is moved through the beam. Several types of targets have been used. One is a tantalum rod which extends completely across the drift chamber. Another is a tungsten powder filled carbon crucible. Both of these probes are moved from shot to shot so that the x-ray signal intensity varies with probe position. A third is a larger tantalum disk which is inserted on beam axis to allow determining beam size on a one shot basis. The x-ray signals are detected with an MCP photomultiplier tube located at 90/sup 0/ to the beamline. It is sufficiently shielded to reject background x-rays and neutrons. The signals were digitized, recorded and later unfolded to produce plots of x-ray intensity versus probe position for several times during the pulse. The presumption that the x-ray intensity is proportional to beam current density is checked computationally. Details of the probe construction and PMT shielding, as well as sample measurements are given.

Struve, K.W.; Chambers, F.W.; Lauer, E.J.; Slaughter, D.R.

1986-01-01

361

A test of Lee's quasi-linear theory of ion acceleration by interplanetary traveling shocks  

NASA Technical Reports Server (NTRS)

Lee's (1983) quasi-linear theory of ion acceleration is tested using ISEE-3 measurements of the November 12, 1978 quasi-parallel interplanetary shock. His theory accounts with varying degrees of precision for the energetic proton spatial profiles; the dependence of the spectral index of the power law proton velocity distribution upon the shock compression ratio; the power law dependence of the upstream proton scalelength upon energy; the absolute magnitude of the upstream proton scale length; the behavior of the energetic proton anisotropy upstream and downstream of the shock; the behavior of the alpha-particle proton ratio upstream; the equality of the spatial scale lengths at the shock of the upstream waves and of the protons that resonate with them; and the dependence of the integrated wave energy density upon the proton energy density at the shock. However, the trace magnetic field frequency spectra disagree with his theory in two ways. The part of the spectrum that can resonate with the observed protons via first-order cyclotron resonance is flat, whereas Lee's theory predicts an f exp - 7/4 frequency dependence for the November 12 shock. Higher frequency waves, which could not resonate with the observed upstream protons, increased in amplitude as the shock approached, suggesting that they too were generated by the shock.

Kennel, C. F.; Coroniti, F. V.; Scarf, F. L.; Livesey, W. A.; Russell, C. T.; Smith, E. J.

1986-01-01

362

Accelerated stress testing and diagnostic analysis of degradation in CdTe solar cells  

NASA Astrophysics Data System (ADS)

Solar cell module reliability is inextricably linked to cell-level reliability. This is particularly so with thin-film technologies. In CdTe, reliability issues historically associate with back contact stability and the use of Cu as an extrinsic dopant. Using a simple approach by which identical cells are heated under open-circuit bias and 1-sun illumination, degradation activation energies of 0.63 and 2.94 eV in laboratory-scale CdS/CdTe devices were identified in the accelerated stress temperature range of 60 to 120 °C. At lower stress temperatures, cell performance changes were linearly correlated with changes in both fill factor (FF) and short-circuit current (Jsc). At higher stress temperatures, changes in efficiency were correlated with changes in FF and open-circuit voltage (Voc). The measured activation energy of 0.63 is associated with Cu-diffusion. During the early stage of stress testing, which may provide additional back contact annealing, improvements in FF were due to Cu-diffusion. Decreased performance observed at longer stress times (decreased FF and Voc), according to a two-diode Pspice model, were due to both increased space-charge recombination (near the junction) and decreased recombination in the bulk. Kirkendall void formation (S-outdiffusion) at the CdS/CdTe interface is given as responsible for the 2.9 eV degradation mechanism.

Albin, David S.

2008-08-01

363

Accelerated Stability Testing of a Clobetasol Propionate-Loaded Nanoemulsion as per ICH Guidelines  

PubMed Central

The physical and chemical degradation of drugs may result in altered therapeutic efficacy and even toxic effects. Therefore, the objective of this work was to study the stability of clobetasol propionate (CP) in a nanoemulsion. The nanoemulsion formulation containing CP was prepared by the spontaneous emulsification method. For the formulation of the nanoemulsion, Safsol, Tween 20, ethanol, and distilled water were used. The drug was incorporated into an oil phase in 0.05% w/v. The lipophilic nature of the drug led to the O/W nanoemulsion formulation. This was characterized by droplet size, pH, viscosity, conductivity, and refractive index. Stability studies were performed as per ICH guidelines for a period of three months. The shelf life of the nanoemulsion formulation was also determined after performing accelerated stability testing (40°C ± 2°C and 75% ± 5% RH). We also performed an intermediate stability study (30°C ± 2°C/65% RH ± 5% RH). It was found that the droplet size, conductivity, and refractive index were slightly increased, while the viscosity and pH slightly decreased at all storage conditions during the 3-month period. However, the changes in these parameters were not statistically significant (p?0.05). The degradation (%) of the optimized nanoemulsion of CP was determined and the shelf life was found to be 2.18 years at room temperature. These studies confirmed that the physical and chemical stability of CP were enhanced in the nanoemulsion formulation.

Ali, Mohammad Sajid; Alam, Mohammad Sarfaraz; Alam, Nawazish; Anwer, Tarique; Safhi, Mohammed Mohsen A.

2013-01-01

364

Linear and second order optics corrections for the KEK Accelerator Test Facility final focus beam line  

NASA Astrophysics Data System (ADS)

In this paper, the linear and second order optics corrections for the KEK Accelerator Test Facility (ATF2) final focus beam line are described. The beam optics of the ATF2 beam line is designed based on a local chromaticity correction scheme similar to the ILC final focus system. Beam measurements in 2012 revealed skew sextupole field errors that were much larger than expected from magnetic field measurements. The skew sextupole field error was a critical limitation of the beam size at the ATF2 virtual interaction point (IP). Therefore, four skew sextupole magnets were installed to correct the field error in August 2012. By using the four skew sextupole magnets, the predicted tolerances of the skew sextupole field errors of the ATF2 magnets were increased. Furthermore, analyzing field maps of the sextupole magnets identified the source of the skew sextupole field error. After the field error source was removed, the IP vertical beam size could more easily be focused to less than 65 nm.

Okugi, T.; Araki, S.; Bambade, P.; Kubo, K.; Kurado, S.; Masuzawa, M.; Marin, E.; Naito, T.; Tauchi, T.; Terunuma, N.; Tomas, R.; Urakawa, J.; White, G.; Woodley, M.

2014-02-01

365

The LeRC rail accelerators: Test designs and diagnostic techniques  

NASA Technical Reports Server (NTRS)

The feasibility of using rail accelerators for various in-space and to-space propulsion applications was investigated. A 1 meter, 24 sq mm bore accelerator was designed with the goal of demonstrating projectile velocities of 15 km/sec using a peak current of 200 kA. A second rail accelerator, 1 meter long with a 156.25 sq mm bore, was designed with clear polycarbonate sidewalls to permit visual observation of the plasma arc. A study of available diagnostic techniques and their application to the rail accelerator is presented. Specific topics of discussion include the use of interferometry and spectroscopy to examine the plasma armature as well as the use of optical sensors to measure rail displacement during acceleration. Standard diagnostics such as current and voltage measurements are also discussed.

Zana, L. M.; Kerslake, W. R.; Sturman, J. C.; Wang, S. Y.; Terdan, F. F.

1983-01-01

366

Evaluation of splashzone maintenance coating systems by accelerated laboratory testing and field trials  

SciTech Connect

Maintenance painting of platform splashzones is one of the most difficult offshore coating problems. There is a limited and frequently interrupted weather window for working, the temperature is generally low, the relative humidity is usually high and surfaces may be subjected to salt spray or complete immersion within a few hours of coating application. Once a coating is on the steel, it is continually wet and must resist abrasion and impact from the sea and from debris which is in the sea. In order to stand up to these conditions, splashzone coatings must adhere tightly to the steel, they must be tough and resilient and they must be resistant to the spread of local damage. Occidental's Piper and Claymore Platforms were installed in the North Sea in 1976 and 1977 respectively. The original splashzone coatings applied during fabrication were high-build vinyl systems over zinc silicate primers. The same coating systems were used on the platform topsides. By 1978 there was a need for coating repairs because the vinyls had poor abrasion resistance. It has proved impossible to use the original coating system for the repairs because it is intolerant of ambient conditions. Major maintenance painting programmes were planned for both platform splashzones in 1983. Surveys had shown that both splashzones required blasting to bare metal and recoating. Field trials and accelerated laboratory tests were used to select a coating system for the platform splashzones from nine alternative systems. The materials tested were ones presented by major manufacturers as their recommended splashzone systems. The coating systems ranged from coal tar epoxies to a very-high-technology system of primer injected into the grit-blasting nozzle followed by a single coat of high-build, solvent-free epoxy. Detailed descriptions of the coating systems are given in Table 1.

Tischuk, J.L.; Brebner, G.

1983-09-01

367

Cosmic opacity: Cosmological-model-independent tests and their impact on cosmic acceleration  

NASA Astrophysics Data System (ADS)

With assumptions that the violation of the distance-duality relation entirely arises from nonconservation of the photon number and that the absorption is frequency independent in the observed frequency range, we perform cosmological-model-independent tests for the cosmic opacity. The observational data include the largest Union2.1 type Ia supernova sample, which is taken for observed DL, and galaxy cluster samples compiled by De Filippis et al. and Bonamente et al., which are responsible for providing observed DA. Two parametrizations, ?(z)=2?z and ?(z)=(1+z)2?-1, are adopted for the optical depth associated with the cosmic absorption. We find that an almost transparent universe is favored by the Filippis et al. sample, but it is only marginally accommodated by the Bonomente et al. samples at 95.4% confidence level (C.L.) (even at 99.7% C.L. when the r<100kpc-cut spherical ? model is considered). Taking the possible cosmic absorption (in the 68.3% C.L. range) constrained from the model-independent tests into consideration, we correct the distance moduli of SNe Ia and then use them to study their cosmological implications. The constraints on the ?CDM show that a decelerating expanding universe with ??=0 is only allowed at 99.7% C.L. by observations when the Bonamente et al. sample is considered. Therefore, our analysis suggests that an accelerated cosmic expansion is still needed to account for the dimming of SNe, and the standard cosmological scenario remains being supported by current observations.

Li, Zhengxiang; Wu, Puxun; Yu, Hongwei; Zhu, Zong-Hong

2013-05-01

368

Structural Integrity, Accelerated Corrosion and Flow Capacity Tests of Parker Aircraft Company Valve, Check, One-Inch, Airborne, Fuel Parker Part Number 2630014. Gd/a Part Number 27-02402-5.  

National Technical Information Service (NTIS)

Two units were submitted for testing. The test program consisted of diameter measurements, accelerated corrosion, flow capacity and burst pressure tests. A 30-day accelerated corrosion test caused severe corrosion of the body base metal; but, there was no...

1964-01-01

369

Accelerated/abbreviated test methods of the low-cost silicon solar array project. Study 4, task 3: Encapsulation  

NASA Technical Reports Server (NTRS)

Methods of accelerated and abbreviated testing were developed and applied to solar cell encapsulants. These encapsulants must provide protection for as long as 20 years outdoors at different locations within the United States. Consequently, encapsulants were exposed for increasing periods of time to the inherent climatic variables of temperature, humidity, and solar flux. Property changes in the encapsulants were observed. The goal was to predict long term behavior of encapsulants based upon experimental data obtained over relatively short test periods.

Kolyer, J. M.; Mann, N. R.

1977-01-01

370

Corrosion Embrittlement of Duralumin II Accelerated Corrosion Tests and the Behavior of High-Strength Aluminum Alloys of Different Compositions  

NASA Technical Reports Server (NTRS)

The permanence, with respect to corrosion, of light aluminum alloy sheets of the duralumin type, that is, heat-treatable alloys containing Cu, Mg, Mn, and Si is discussed. Alloys of this type are subject to surface corrosion and corrosion of the interior by intercrystalline paths. Results are given of accelerated corrosion tests, tensile tests, the effect on corrosion of various alloying elements and heat treatments, electrical resistance measurements, and X-ray examinations.

Rawdon, Henry S

1928-01-01

371

A LABORATORY SOIL-CONTACT DECAY TEST: AN ACCELERATED METHOD TO DETERMINE DURABILITY OF TREATED WOOD SHAKES  

Microsoft Academic Search

In this study, cross sections of preservative-treated shakes were evaluated in soil-contact decay tests using Gleophyllum trabeum. The number of preservatives by species combinations, used allowed evaluation of procedural aspects of this method. We conclude that the soil-contact decay test is a good tool for an accelerated evaluation of the durability of treated shakes. Experimental designs need to be structured

Rodney C. De Groot; Bessie Woodward

1996-01-01

372

Using a commercial mathematics software package for on-line analysis at the BNL Accelerator Test Facility  

SciTech Connect

BY WRITING BOTH A CUSTOM WINDOWS(NTTM) DYNAMIC LINK LIBRARY AND GENERIC COMPANION SERVER SOFTWARE, THE INTRINSIC FUNCTIONS OF MATHSOFT MATHCAD(TM) HAVE BEEN EXTENDED WITH NEW CAPABILITIES WHICH PERMIT DIRECT ACCESS TO THE CONTROL SYSTEM DATABASES OF BROOKHAVEN NATIONAL LABORATORY ACCELERATOR TEST FACILITY. UNDER THIS SCHEME, A MATHCAD WORKSHEET EXECUTING ON A PERSONAL COMPUTER BECOMES A CLIENT WHICH CAN BOTH IMPORT AND EXPORT DATA TO A CONTROL SYSTEM SERVER VIA A NETWORK STREAM SOCKET CONNECTION. THE RESULT IS AN ALTERNATIVE, MATHEMATICALLY ORIENTED VIEW OF CONTROLLING THE ACCELERATOR INTERACTIVELY.

Malone, R.; Wang, X.J.

1999-06-14

373

Salt-Fog Accelerated Testing of Glass Fiber Reinforced Polymer Composites.  

National Technical Information Service (NTIS)

The objective of this project was to determine the durability under accelerated salt-fog exposure of six commercially available composites. These composites included glass- reinforced vinylesters, polyesters, phenolics, and an epoxy. Durability was measur...

A. Caceres, R. M. Jamond, T. A. Hoffard, L. J. Malvar

2002-01-01

374

Polarization Losses under Accelerated Stress Test Using Multiwalled Carbon Nanotube Supported Pt Catalyst in PEM Fuel Cells  

SciTech Connect

The electrochemical behavior for Pt catalysts supported on multiwalled carbon nanotubes and Vulcan XC-72 in proton exchange membrane fuel cells under accelerated stress test was examined by cyclic voltammetry, electrochemical impedance spectroscopy, and polarization technique. Pt catalyst supported on multiwalled carbon nanotubes exhibited highly stable electrochemical surface area, oxygen reduction kinetics, and fuel cell performance at a highly oxidizing condition, indicating multiwalled carbon nanotubes show high corrosion resistance and strong interaction with Pt nanoparticles. The Tafel slope, ohmic resistances, and limiting current density determined were used to differentiate kinetic, ohmic, mass-transfer polarization losses from the actual polarization curve. Kinetic contribution to the total overpotential was larger throughout the stress test. However, the fraction of kinetic overpotential decreased and mass-transfer overpotential portion remained quite constant during accelerated stress test, whereas the fraction of ohmic overpotential primarily originating from severe proton transport limitation in the catalyst layer increased under the anodic potential hold.

Park, Seh K.; Shao, Yuyan; Kou, Rong; Viswanathan, Vilayanur V.; Towne, Silas A.; Rieke, Peter C.; Liu, Jun; Lin, Yuehe; Wang, Yong

2011-03-01

375

High Power Testing of Dielectric-Loaded Accelerating Structures at 11.424 GHz  

Microsoft Academic Search

Summary form only given. A joint Naval Research Laboratory\\/Argonne National Laboratory study is under way to investigate the performance of X-band dielectric-loaded accelerating (DLA) structures using high-power 11.424-GHz radiation from the NRL Magnicon facility. DLA structures offer the potential of a simple, inexpensive alternative to copper disk-loaded structures for use in high-gradient RF linear accelerators. The purpose of the high-power

S. H. Gold; A. K. Kinkead; Wei Gai; J. G. Power; R. Konecny; Chunguang Jing; Wanming Liu; Z. M. Yusof

2005-01-01

376

Testing the accelerating moment release (AMR) hypothesis in areas of high stress  

NASA Astrophysics Data System (ADS)

Several retrospective analyses have proposed that significant increases in moment release occurred prior to many large earthquakes of recent times. However, the finding of accelerating moment release (AMR) strongly depends on the choice of three parameters: (1) magnitude range, (2) area being considered surrounding the events and (3) the time period prior to the large earthquakes. Consequently, the AMR analysis has been criticized as being a posteriori data-fitting exercise with no new predictive power. As AMR has been hypothesized to relate to changes in the state of stress around the eventual epicentre, we compare here AMR results to models of stress accumulation in California. Instead of assuming a complete stress drop on all surrounding fault segments implied by a back-slip stress lobe method, we consider that stress evolves dynamically, punctuated by the occurrence of earthquakes, and governed by the elastic and viscous properties of the lithosphere. We study the seismicity of southern California and extract events for AMR calculations following the systematic approach employed in previous studies. We present several sensitivity tests of the method, as well as grid-search analyses over the region between 1955 and 2005 using fixed magnitude range, radius of the search area and period of time. The results are compared to the occurrence of large events and to maps of Coulomb stress changes. The Coulomb stress maps are compiled using the coseismic stress from all M > 7.0 earthquakes since 1812, their subsequent post-seismic relaxation, and the interseismic strain accumulation. We find no convincing correlation of seismicity rate changes in recent decades with areas of high stress that would support the AMR hypothesis. Furthermore, this indicates limited utility for practical earthquake hazard analysis in southern California, and possibly other regions.

Guilhem, Aurélie; Bürgmann, Roland; Freed, Andrew M.; Ali, Syed Tabrez

2013-11-01

377

Experimental test of a new antiproton acceleration scheme in the Fermilab Main Injector  

SciTech Connect

In an effort to provide higher intensity and lower emittance antiproton beam to the Tevatron collider for high luminosity operation, a new Main Injector (MI) antiproton acceleration scheme has been developed [1-4]. In this scheme, beam is accelerated from 8 to 27 GeV using the 2.5 MHz rf system and from 27 to 150 GeV using the 53 MHz rf system. This paper reports the experimental results of beam study. Simulation results are reported in a different PAC'05 paper [5]. Experiments are conducted with proton beam from the Booster. Acceleration efficiency, emittance growth and beam harmonic transfer between 2.5 MHz (h=28) and 53 MHz (h=588) buckets have been studied. Beam study shows that one can achieve an overall acceleration efficiency of about 100%, longitudinal emittance growth less than 20% and negligible transverse emittance growth. accelerated to 150 GeV and injected to the Tevatron. The multi-bunch coalescing process is eliminated in this acceleration scheme. Consequently, longitudinal emittance growth is reduced. Smaller emittance growth reduces beam loss.

Wu, V.; Bhat, C.M.; Chase, B.E.; Dey, J.E.; Meisner, K.G.; /Fermilab

2005-05-01

378

Modernization and life time extension on steam power plants in Eastern Europe and Russia  

NASA Astrophysics Data System (ADS)

The Eastern European electricity markets with focus on Russia and Ukraine are suffering severe aging of the existing LMZ, UTZ and Turboatom steam turbine fleets after more than 25 years of operation. Energy efficient modernizations along with life time extension beyond the designed life time of existing old power plants is an economical option to address the increasing power demand. Steam Turbine modernizations are using latest state of the art materials and technology-enhanced turbine components such as blades, sealing, guide blade carriers, inner casings and rotors as well as components for auxiliary systems e.g. lube and lifting oil thus providing increased efficiency and optimized maintainability. This paper outlines unique design features and pre-engineered modules of the Siemens steam turbine modernization applications for thermal power stations, emphasizing the solutions for Turboatom 300 MW and LMZ 200 MW turbine-generators. The paper concludes with references and operational experience.

Kupetz, M.; Jenikejew, E.; Hiss, F.

2014-06-01

379

Characteristics of a 1200 V PT IGBT with trench gate and local life time control  

Microsoft Academic Search

A new 1200 V IGBT with a VCE(sat) of 1.9 V at 125°C and 140 A\\/cm2 has been developed using a trench gate PT (punch-through) structure and local life time control. Compared to state-of-the-art third generation planar devices, this device represents a 30% improvement of on-state losses at almost twice the current density. This paper describes the structure and characteristics

Eric R. Motto; John F. Donlon; H. Takahashi; M. Tabata; H. Iwamoto

1998-01-01

380

Study of cement-epoxy interfaces, accelerated testing, and surface modification  

NASA Astrophysics Data System (ADS)

Adhesion between concrete and fiber reinforced polymer (FRP) repair materials is of great importance for increasing the longevity of damaged surfaces in civil infrastructure in the US. This adhesion is dominated by a relatively weak interfacial bond that is attacked by environmental agents including water and UV radiation. Therefore, a strong bond between the two materials is essential in making a successful, long lasting repair. In this study, the fundamental question of the epoxy-concrete interface is investigated in terms of how it exists, how it is attacked by the environment, and how it may be improved to resist the elements. In this study, interactions between epoxy analogs and cement paste were investigated to get a fundamental understanding of the elusive interfacial bond. Various FTIR and NMR techniques were utilized to demonstrate the nature of this interaction. Only one of the small molecules (Bisphenol A), suggested a small interaction, however, based on the results it appeared that hydrogen bonding did not take place. The second part of this work focused on accelerated aging two epoxy systems, including a model DGEBA-POPDA system, and a commercial system. Mechanical testing was performed along with IR spectroscopy and diffusion modeling to determine the change in properties and mechanisms of degradation. The absorption of water up to 90°C resulted in a decrease in modulus and stress, along with an increase in strain. IR data confirmed the absorption of water within the epoxy network. With UV exposure, oxidation was demonstrated by the appearance of carbonyl peaks in the FTIR spectra. UV and water exposure gave evidence of hydrolysis through a decrease in ether groups and an increase in hydroxyl groups. While samples exposed to UV showed less of a loss in modulus as compared to those only exposed to water at the same temperature, the peak stress of samples exposed to UV was lower than those exposed to water. However, the data from the mechanical testing of the UV exposed samples was not statistically significant. The final section of this work used silane coupling agents to modify cement pastes. AFM measurements were performed to demonstrate the effectiveness of the polishing technique and uniformity of the surface, which the literature indicated was necessary for comparison purposes. The contact angle was shown to increase for the PDMS based silane, decrease for the amino based silane, and not change for the epoxy based silane. XPS data confirmed successful covalent linkages between the cement paste and silane coupling agents as evidenced by an increase in bridging O1s and Si2p electron orbitals after curve fitting.

Stewart, Andrew

381

Measurements of spin life time of an antimony-bound electron in silicon  

NASA Astrophysics Data System (ADS)

We report our measurements of spin life time of an antimony-bound electron in silicon. The device is a double-top-gated silicon quantum dot with antimony atoms implanted near the quantum dot region. A donor charge transition is identified by observing a charge offset in the transport characteristics of the quantum dot. The tunnel rates on/off the donor are first characterized and a three-level pulse sequence is then used to measure the spin populations at different load-and-wait times in the presence of a fixed magnetic field. The spin life time is extracted from the exponential time dependence of the spin populations. A spin life time of 1.27 seconds is observed at B = 3.25 T. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE, Office of Basic Energy Sciences user facility. The work was supported by the Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Lu, T. M.; Bishop, N. C.; Tracy, L. A.; Blume-Kohout, R.; Pluym, T.; Wendt, J. R.; Dominguez, J.; Lilly, M. P.; Carroll, M. S.

2013-03-01

382

Simulation of launch and re-entry acceleration profiles for testing of shuttle and unmanned microgravity research payloads  

NASA Astrophysics Data System (ADS)

Microgravity experiments designed for execution in Get-Away Special canisters, Hitchhiker modules, and Reusable Re-entry Satellites will be subjected to launch and re-entry accelerations. Crew-dependent provisions for preventing acceleration damage to equipment or products will not be available for these payloads during flight; therefore, the effects of launch and re-entry accelerations on all aspects of such payloads must be evaluated prior to flight. A procedure was developed for conveniently simulating the launch and re-entry acceleration profiles of the Space Shuttle (3.3 and 1.7 × g maximum, respectively) and of two versions of NASA's proposed materials research Re-usable Re-entry Satellite (8 × g maximum in one case and 4 × g in the other). By using the 7 m centrifuge of the Gravitational Plant Physiology Laboratory in Philadelphia it was found possible to simulate the time dependence of these 5 different acceleration episodes for payload masses up to 59 kg. A commercial low-cost payload device, the “Materials Dispersion Apparatus” of Instrumentation Technology Associates was tested for (1) integrity of mechanical function, (2) retention of fluid in its compartments, and (3) integrity of products under simulated re-entry g-loads. In particular, the sharp rise from 1 g to maximum g-loading that occurs during re-entry in various unmanned vehicles was successfully simulated, conditions were established for reliable functioning of the MDA, and crystals of 5 proteins suspended in compartments filled with mother liquor were subjected to this acceleration load.

Cassanto, J. M.; Ziserman, H. I.; Chapman, D. K.; Korszun, Z. R.; Todd, P.

383

An accelerated life test model for solid lubricated bearings based on dependence analysis and proportional hazard effect  

NASA Astrophysics Data System (ADS)

Solid lubricated bearings are important mechanical components in space, and accelerated life tests (ALT) of them are widely conducted. ALT model is needed to give the lifetime of solid lubricated bearings with ALT data, and former accelerated life test models of solid lubricated models are mainly statistical models, while physical models can imply an understanding of the failure mechanism and are preferred whenever possible. This paper proposes a physical model, which is called copula dependent proportional hazards model. A solid lubricated bearing is considered as a system consisting of several dependent items and Clayton copula function is used to describe the dependence. Proportional hazard effect is also considered to build the model. An ALT of solid lubricated bearing is carried out and the results show that this model is effective.

Zhang, Chao; Wang, Shaoping; Bai, Guanghan

2014-02-01

384

Failure Engineering Study and Accelerated Stress Test Results for the Mars Global Surveyor Spacecraft's Power Shunt Assemblies  

NASA Technical Reports Server (NTRS)

An Engineering-of-Failure approach to designing and executing an accelerated product qualification test was performed to support a risk assessment of a "work-around" necessitated by an on-orbit failure of another piece of hardware on the Mars Global Surveyor spacecraft. The proposed work-around involved exceeding the previous qualification experience both in terms of extreme cold exposure level and in terms of demonstrated low cycle fatigue life for the power shunt assemblies. An analysis was performed to identify potential failure sites, modes and associated failure mechanisms consistent with the new use conditions. A test was then designed and executed which accelerated the failure mechanisms identified by analysis. Verification of the resulting failure mechanism concluded the effort.

Gibbel, Mark; Larson, Timothy

2000-01-01

385

Advanced Test Accelerator (ATA), a 50 MeV, 10 kA induction linac  

NASA Astrophysics Data System (ADS)

The ATA is an induction accelerator designed to produce 70 ns pulses of electrons at currents of 10 kA and energies in excess of 50 MeV. The accelerator is capable of operating at an average rate of 5 Hz or at 1 kHz for ten pulses. The parameters were chosen primarily to provide the experimental basis for advancing the understanding of electron beam propagation physics. The 85 m accelerator has been under construction for the past four years and has adopted mainly an improved version of the ETA technology to satisfy the required parameters. Initial operation of the facility and the energy conversion system from primary power to axial electric field will be described; recent advances in magnetic switching which have been incorporated in the innector will also be discussed.

Reginato, L. L.

1983-03-01

386

Insulation characterization in multistress conditions by accelerated life tests: An application to XLPE and EPR for high voltage cables  

Microsoft Academic Search

This paper focuses on accelerated testing procedures that can be applied to XLPE and EPR for high voltage cables and that are aimed to achieve the thermo-electrical endurance characterization of insulation. Several methods and techniques for single and combined thermo-electrical stress are illustrated; indices for the evaluation of electrical, thermal, and multi-stress endurance are reported and their derivation is shown.

G. Mazzanti; G. C. Montanari; L. Simoni

1997-01-01

387

Defining the life of valve-regulated lead-acid batteries: a new approach to accelerated testing  

Microsoft Academic Search

Accelerated float life tests of lead-acid batteries are based on the assumption that positive grid corrosion is the dominant failure mode. While corrosion rates in valve-regulated lead-acid (VRLA) batteries have been assumed to be the same as in flooded designs, the float life of these systems is often less than predicted. Careful analysis of the material balances within a battery

KATHRYN R. BULLOCK; PATRICK K. NG; JORGE L. VALDES; RONALD A. HOLLAND

1995-01-01

388

Evaluation of GaN-based blue light emitting diodes based on temperature\\/humidity accelerated tests  

Microsoft Academic Search

The degradation of high power GaN-based blue light-emitting diodes (LEDs) was investigated by considering the electrical, optical and electroluminescence spectrum aging characteristics. The LED samples are stressed at the condition of 85°C and 85% RH using an injection current of 1000 mA. Optical output power decreases to 80% of initial value after 1000 hours of temperature\\/humidity accelerated tests. Changes in

Shengjun Zhou; Qin Zhang; Bin Cao; Sheng Liu

2010-01-01

389

Comprehensive beam jitter study for the commissioning of the intermediate matching section and drift tube linac at Ground Test Accelerator  

Microsoft Academic Search

An experiment on the Ground Test Accelerator (GTA) for the Neutral Particle Beam (NPB) at Los Alamos commissioned the intermediate matching section (IMS) and a single 3.2-MeV drift tube linac (DTL). A diagnostic platform or D-plate was used at the output of the DTL in order to measure various beam parameters. The D-plate and other diagnostic devices located in the

D. S. Barr; J. D. Gilpatrick

1993-01-01

390

Interplanetary shock event of November 11/12 1978, a comprehensive test of acceleration theory  

SciTech Connect

A comprehensive study of the November 11/12, 1978 shock event based on energetic particle, solar wind, magnetic field and wave data from the ISEE-3, -1 and -2 spacecraft has been undertaken both from the energetic and the collisionless shock point of view. The energy density of 10-50 keV protons accelerated by the shock is found to be equivalent to the upstream magnetic field energy density. The observations are in quantitative agreement with Lee's (1983) self consistent theory for the excitation of hydromagnetic waves and the acceleration of ions upstream of interplanetary shocks.

Wenzel, K.P.; Sanderson, T.R.; Vannes, P.; Kennel, C.F.; Scarf, F.L.; Coroniti, F.V.; Russell, C.T.; Parks, G.K.; Smith, E.J.

1983-04-01

391

10-GW CO{sub 2} laser system at the Brookhaven Accelerator Test Facility  

SciTech Connect

Design and performance of a high peak-power CO{sub 2} laser system to produce subnanosecond IR pulses for electron acceleration experiment are presented. We discuss theoretical aspects of the picosecond laser pulse propagation in a molecular amplifier and a design approach towards compact Terawatt CO{sub 2} laser systems.

Pogorelsky, I.; Fischer, J.; Fisher, A.S. [and others

1993-12-31

392

Performance Tests of Survey Instruments used in Radiation Fields Around High-Energy Accelerators  

Microsoft Academic Search

Measurements of ambient dose equivalent in stray radiation fields behind the shielding of high-energy accelerators are a challenging task. Several radiation components (photons, neutrons, charged particles), spanning a wide range of energies, contribute to the total dose equivalent. Usually for measurements of the total dose equivalent, a set of radiation detectors consisting of ionisation chambers and so-called REM counters is

S. Mayer; D. Forkel-Wirth; M. Fuerstner; H. G. Menzel; S. Roesler; C. Theis; H. Vincke

2005-01-01

393

Experimental limits on the proton life-time from the neutrino experiments with heavy water  

NASA Astrophysics Data System (ADS)

Experimental data on the number of neutrons born in the heavy water targets of the large neutrino detectors are used to set the limit on the proton life-time independently on decay mode through the reaction d-->n+?. The best up-to-date limit ?p>4×1023 yr with 95% C.L. is derived from the measurements with D2O target (mass 267 kg) installed near the Bugey reactor. This value can be improved by six orders of magnitude with future data accumulated with the SNO detector containing 1000 t of D2O.

Tretyak, V. I.; Zdesenko, Y. G.

2001-04-01

394

Evaluation of accelerated UV and thermal testing for benzene formation in beverages containing benzoate and ascorbic acid.  

PubMed

Under certain conditions, benzene can form in beverages containing benzoic and ascorbic acids. The American Beverage Assn. (ABA) has published guidelines to help manufacturers mitigate benzene formation in beverages. These guidelines recommend accelerated testing conditions to test product formulations, because exposure to ultraviolet (UV) light and elevated temperature over the shelf life of the beverage may result in benzene formation in products containing benzoic and ascorbic acids. In this study, the effects of UVA exposure on benzene formation were determined. Benzene formation was examined for samples contained in UV stabilized and non-UV stabilized packaging. Additionally, the usefulness of accelerated thermal testing to simulate end of shelf-life benzene formation was evaluated for samples containing either benzoic or ascorbic acid, or both. The 24 h studies showed that under intense UVA light benzene levels increased by as much as 53% in model solutions stored in non-UV stabilized bottles, whereas the use of UV stabilized polyethylene terephthalate bottles reduced benzene formation by about 13% relative to the non-UV stabilized bottles. Similar trends were observed for the 7 d study. Retail beverages and positive and negative controls were used to study the accelerated thermal testing conditions. The amount of benzene found in the positive controls and cranberry juice suggests that testing at 40 degrees C for 14 d may more reliably simulate end of shelf-life benzene formation in beverages. Except for cranberry juice, retail beverages were not found to contain detectable amounts of benzene (<0.05 ng/g) at the end of their shelf lives. PMID:20492277

Nyman, Patricia J; Wamer, Wayne G; Begley, Timothy H; Diachenko, Gregory W; Perfetti, Gracia A

2010-04-01

395

Testing Done for Lorentz Force Accelerators and Electrodeless Propulsion Technology Development  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center is developing Lorentz force accelerators and electrodeless plasma propulsion for a wide variety of space applications. These applications range from precision control of formation-flying spacecraft to primary propulsion for very high power interplanetary spacecraft. The specific thruster technologies being addressed are pulsed plasma thrusters, magnetoplasmadynamic thrusters, and helicon-electron cyclotron resonance acceleration thrusters. The pulsed plasma thruster mounted on the Earth Observing-1 spacecraft was operated successfully in orbit in 2002. The two-axis thruster system is fully incorporated in the attitude determination and control system and is being used to automatically counteract disturbances in the pitch axis of the spacecraft. Recent on-orbit operations have focused on extended operations to add flight operation time to the total accumulated thruster life. The results of the experiments pave the way for electric propulsion applications on future Earth-imaging satellites.

Pencil, Eric J.; Gilland, James H.; Arrington, Lynn A.; Kamhawi, Hani

2004-01-01

396

Experimental design and analysis for accelerated degradation tests with Li-ion cells.  

SciTech Connect

This document describes a general protocol (involving both experimental and data analytic aspects) that is designed to be a roadmap for rapidly obtaining a useful assessment of the average lifetime (at some specified use conditions) that might be expected from cells of a particular design. The proposed experimental protocol involves a series of accelerated degradation experiments. Through the acquisition of degradation data over time specified by the experimental protocol, an unambiguous assessment of the effects of accelerating factors (e.g., temperature and state of charge) on various measures of the health of a cell (e.g., power fade and capacity fade) will result. In order to assess cell lifetime, it is necessary to develop a model that accurately predicts degradation over a range of the experimental factors. In general, it is difficult to specify an appropriate model form without some preliminary analysis of the data. Nevertheless, assuming that the aging phenomenon relates to a chemical reaction with simple first-order rate kinetics, a data analysis protocol is also provided to construct a useful model that relates performance degradation to the levels of the accelerating factors. This model can then be used to make an accurate assessment of the average cell lifetime. The proposed experimental and data analysis protocols are illustrated with a case study involving the effects of accelerated aging on the power output from Gen-2 cells. For this case study, inadequacies of the simple first-order kinetics model were observed. However, a more complex model allowing for the effects of two concurrent mechanisms provided an accurate representation of the experimental data.

Doughty, Daniel Harvey; Thomas, Edward Victor; Jungst, Rudolph George; Roth, Emanuel Peter

2003-08-01

397

Intense neutron source target test facility: a 200 mA dc, deuterium ion accelerator  

Microsoft Academic Search

A 200 kV, 200 mA dc, deuterium ion accelerator has been constructed to evaluate high-temperature hydride materials such as scandium and erbium for use as targets in D--T neutron generators. The metal hydride film is deposited on a water-cooled, copper substrate designed to handle power densities of 40 MW\\/m² while maintaining a surface temperature of less than or equal to

F. M. Bacon; A. A. Riedel

1978-01-01

398

Development of an accelerated test design for predicting the service life of the solar array at Mead, Nebraska  

NASA Technical Reports Server (NTRS)

Potential long-term degradation modes for the two types of modules in the Mead array were determined and judgments were made as to those environmental stresses and combinations of stresses which accelerate the degradation of the power output. Hierarchical trees representing the severity of effects of stresses (test conditions) on eleven individual degradation modes were constructed and were pruned of tests judged to be nonessential. Composites of those trees were developed so that there is now one pruned tree covering eight degradation modes, another covering two degradation modes, and a third covering one degradation mode. These three composite trees form the basis for selection of test conditions in the final test plan which is now being prepared.

Gaines, G. B.; Thomas, R. E.; Noel, G. T.; Shilliday, T. S.; Wood, V. E.; Carmichael, D. C.

1979-01-01

399

Development of an Accelerated Test Design for Predicting the Service Life of the Solar Array at Mead, Nebraska  

NASA Technical Reports Server (NTRS)

Potential long-term degradation modes for the two types of modules in the Mead array were determined and judgments were made as to those environmental stresses and combinations of stresses which accelerate the degradation of the power output. Hierarchical trees representing the severity of effects of stresses (test conditions) on eleven individual degradation modes were constructed and were pruned of tests judged to be nonessential. Composites of those trees were developed so that there is now one pruned tree covering eight degradation modes, another covering two degradation modes, and a third covering one degradation mode. These three composite trees form the basis for selection of test conditions in the final test plan which is now being prepared.

Gaines, G. B.; Thomas, R. E.; Noel, G. T.; Shilliday, T. S.; Wood, V. E.; Carmichael, D. C.

1979-01-01

400

Synchronization extends the life time of the desired behavior of globally coupled systems  

PubMed Central

Synchronization occurs widely in natural and technological world, but it has not been widely used to extend the life time of the desirable behavior of the coupled systems. Here we consider the globally coupled system consisting of n units and show that the initial synchronous state extends the lifetime of desired behavior of the coupled system in the case when the excitation of one or few units is suddenly (breakdown of energy supply) or gradually (as the effect of aging and fatigue) switched off. We give evidence that for the properly chosen coupling the energy transfer from the excited units allows unexcited units to operate in the desired manner. As proof of concept, we examine the system of coupled externally excited rotating pendula. After the partial excitation switch off the initial complete synchronization of all pendula is replaced by phase synchronization with a constant phase shift between the clusters of excited and unexcited pendula. Our results show that the described extension of the system's life time occurs for the wide range of coupling parameters and is robust to the external perturbations.

Kapitaniak, Marcin; Lazarek, Mateusz; Nielaczny, Michal; Czolczynski, Krzysztof; Perlikowski, Przemyslaw; Kapitaniak, Tomasz

2014-01-01

401

Synchronization extends the life time of the desired behavior of globally coupled systems  

NASA Astrophysics Data System (ADS)

Synchronization occurs widely in natural and technological world, but it has not been widely used to extend the life time of the desirable behavior of the coupled systems. Here we consider the globally coupled system consisting of n units and show that the initial synchronous state extends the lifetime of desired behavior of the coupled system in the case when the excitation of one or few units is suddenly (breakdown of energy supply) or gradually (as the effect of aging and fatigue) switched off. We give evidence that for the properly chosen coupling the energy transfer from the excited units allows unexcited units to operate in the desired manner. As proof of concept, we examine the system of coupled externally excited rotating pendula. After the partial excitation switch off the initial complete synchronization of all pendula is replaced by phase synchronization with a constant phase shift between the clusters of excited and unexcited pendula. Our results show that the described extension of the system's life time occurs for the wide range of coupling parameters and is robust to the external perturbations.

Kapitaniak, Marcin; Lazarek, Mateusz; Nielaczny, Michal; Czolczynski, Krzysztof; Perlikowski, Przemyslaw; Kapitaniak, Tomasz

2014-03-01

402

Synchronization extends the life time of the desired behavior of globally coupled systems.  

PubMed

Synchronization occurs widely in natural and technological world, but it has not been widely used to extend the life time of the desirable behavior of the coupled systems. Here we consider the globally coupled system consisting of n units and show that the initial synchronous state extends the lifetime of desired behavior of the coupled system in the case when the excitation of one or few units is suddenly (breakdown of energy supply) or gradually (as the effect of aging and fatigue) switched off. We give evidence that for the properly chosen coupling the energy transfer from the excited units allows unexcited units to operate in the desired manner. As proof of concept, we examine the system of coupled externally excited rotating pendula. After the partial excitation switch off the initial complete synchronization of all pendula is replaced by phase synchronization with a constant phase shift between the clusters of excited and unexcited pendula. Our results show that the described extension of the system's life time occurs for the wide range of coupling parameters and is robust to the external perturbations. PMID:24633215

Kapitaniak, Marcin; Lazarek, Mateusz; Nielaczny, Michal; Czolczynski, Krzysztof; Perlikowski, Przemyslaw; Kapitaniak, Tomasz

2014-01-01

403

Acceleration of particles by an active medium  

SciTech Connect

It is shown that an active medium can accelerate a single moving charge or a distribution of such charges. The acceleration is proportional to the population inversion and in the case of a single particle it is shown that it is inversely proportional to the spontaneous emission life-time. Simulation indicates that for the particular case presented, gradients in excess of 1 GV/m can develop. Unlike for laser applications, the spontaneous emission life-time has to be as short as possible. {copyright} 1995 {ital American Institute of Physics}.

Schaechter, L. [Electrical Engineering Department, Ben-Gurion University, Beer-Sheva 84105 (Israel)

1995-06-01

404

Performance tests of the 600-kW, cw, 80-MHz, radio-frequency systems for the FMIT accelerator  

SciTech Connect

The high-power rf system for the Fusion Materials Irradiation Test (FMIT) accelerator consists of 14 sets of equipment, each of which can deliver up to 600 kW (cw) at 80 MHz into a load having a VSWR of 1.4 or less (any phase). The equipment was designed and constructed to FMIT specifications by Continental Electronics Manufacturing Co. (CEMC) of Dallas, Texas. Four sets have been shipped to Los Alamos for use with the accelerator (two with the radio-frequency quadrupole (RFQ) and two with the drift-tube linac (DTL)). The first set was fully tested at CEMC. Further tests conducted at Los Alamos, both into a resistive (electrolytic) load and into a resonant cavity (Q approx. 21,000), have confirmed that this system meets, and in most cases far exceeds, the specified performance limits. The first of the 13 production sets (No. 5) also was tested at CEMC before shipping any of the rf equipment to the Hanford Engineering and Development Laboratory at Richland, Washington. Because of the differences in behavior observed when No. 1 was operated at Los Alamos with a different tube installed in the final power amplifier (FPA) cavity, CEMC agreed to test No. 5 with two tubes having widely differing characteristics (notably primary screen emission). As expected, behavior differed markedly, and some design modification was necessary to meet all specifications with either tube. Results of final performance tests on No. 5 are summarized. Discussion of the most significant aspects of CEMC's tests and of those performed at Los Alamos follows a brief description of the equipment.

Nylander, R.F.; Fazio, M.V.; Bacci, F.F.; Rogers, J.D.

1983-01-01

405

Optimization of parameters for the inline-injection system at Brookhaven Accelerator Test Facility  

SciTech Connect

We present some of our parameter optimization results utilizing code PARMLEA, for the ATF Inline-Injection System. The new solenoid-Gun-Solenoid -- Drift-Linac Scheme would improve the beam quality needed for FEL and other experiments at ATF as compared to the beam quality of the original design injection system. To optimize the gain in the beam quality we have considered various parameters including the accelerating field gradient on the photoathode, the Solenoid field strengths, separation between the gun and entrance to the linac as well as the (type size) initial charge distributions. The effect of the changes in the parameters on the beam emittance is also given.

Parsa, Z. [Brookhaven National Lab., Upton, NY (United States); Ko, S.K. [Ulsan Univ. (Korea, Republic of)

1995-10-01

406

Proposal of the Next Incarnation of Accelerator Test Facility at KEK for the International Linear Collider  

SciTech Connect

To reach design luminosity, the International Linear Collider (ILC) must be able to create and reliably maintain nanometer size beams. The ATF damping ring is the unique facility where ILC emittances are possible. In this paper we present and evaluate the proposal to create a final focus facility at the ATF which, using compact final focus optics and an ILC-like bunch train, would be capable of achieving 37 nm beam size. Such a facility would enable the development of beam diagnostics and tuning methods, as well as the training of young accelerator physicists.

Araki, S.; Hayano, H.; Higashi, Y.; Honda, Y.; Kanazawa, K.; Kubo, K.; Kume, T.; Kuriki, M.; Kuroda, S.; Masuzawa, M.; Naito, T.; Okugi, T.; Sugahara, R.; Takahashi, T.; Tauchi, T.; Terunuma, N.; Toge, N.; Urakawa, J.; Vogel, V.; Yamaoka, H.; Yokoya, K.; /KEK, Tsukuba /Beijing, Inst. High Energy Phys. /Novosibirsk, IYF /Daresbury /CERN /Hiroshima U. /Orsay, LAL /LLNL, Livermore /North Carolina A-T State U. /Oxford U. /Pohang Accelerator Lab. /Queen Mary, U. of London /Royal Holloway, U. of London /DESY /SLAC /University Coll. London /Oregon U. /Tokyo U.

2005-05-27

407

First Actual Field Test of Predicted Toppling Accelerations for Precarious Rocks Provided by the 1999 Hector Mine Earthquake  

NASA Astrophysics Data System (ADS)

An approximate field test of the precarious rock methodology has been provided by the Ms=7.1 Hector Mine earthquake of 16 October 1999 (Brune, 2001). The Hector Mine earthquake was a rare event on very low slip-rate faults near the eastern edge of the Eastern California Shear Zone. Preliminary trenching information indicates that the major fault segments that ruptured in this event had not ruptured in a similar event for more than 10 ka years (Lindvall et al., 2001; Rymer et al., 2001). Brune (1996) identified precarious rocks at Granite Pass, approximately 20 km northeast of the Bristol Fault, and classified them as ``precarious'', i.e., could be toppled by earthquake ground accelerations of less than 0.3~g, typically about 0.2~g (site number 3 in Brune, 1996). A photograph of three of the rocks was published: Figs. 2d and 2e of Brune (1996). The rock in Fig. 2e was apparently toppled by the Hector Mine earthquake (along with another nearby rock for which the photograph was not published). The quasi-static toppling acceleration estimated geometrically from photographs is about 0.2~g. The Amboy strong motion record from the Hector Mine earthquake, at approximately the same distance and the same general direction, recorded a peak ground acceleration of about 0.2g (Grazier et al., 2001, --actually 0.18~g measured from the seismogram available on the internet). The Intensity at Granite Pass is about I = V (Dewey, personal communication). Recent regressions of peak acceleration vs. Intensity, give an acceleration of somewhat less than 0.1~g, with considerable scatter. Both observations are consistent with the designation of the rocks as "precarious" by Brune (1996). We use the Amboy accelerogram , along with small Hector Mine aftershocks recorded at both the Amboy site and at Granite Pass sites, to make a rough correction for differences in path and site effects. The Granite Pass site (on solid granite) is richer in high frequencies than the Amboy site (underlain by layered volcanics and alluvium), but lower in peak velocity. The estimated acceleration at Granite Pass is about 0.12~g, as compared to the original Amboy accelerogram peak value of 0.18~g. Using two small earthquakes to estimate the transfer function does not take into account effects such as directivity, non-linearity and Moho reflection which might have been present in the main event. A more accurate estimate may be possible once we have recorded more aftershocks at both stations.

Anooshehpoor, R.; Brune, J. N.; Biasi, G. P.

2001-12-01

408

New method to test the gantry, collimator, and table rotation angles of a linear accelerator used in radiation therapy  

NASA Astrophysics Data System (ADS)

The precision of a medical LINear ACcelerator (LINAC) gantry rotation angle is crucial for the radiation therapy process, especially in stereotactic radio surgery, given the expected precision of the treatment and in Image Guided Radiation Therapy (IGRT) where the mechanical stability is disturbed due to the additional weight of the kV x-ray tube and detector. We present in this paper an extension of the Winston and Lutz test initially dedicated to control the size and the position of the isocenter of the LINAC and here adapted to test the gantry rotation angle with no additional portal images. This new method uses a test-object patented by QualiFormeD5 and is integrated in the QUALIMAGIQ software platform developed to automatically analyze images acquired for quality control of medical devices.

Beaumont, Stéphane; Torfeh, Tarraf; Latreille, Romain; Ben Hdech, Yassine; Guedon, Jeanpierre

2011-03-01

409

In vitro evaluation of the bonding durability of self-adhesive resin cement to titanium using highly accelerated life test.  

PubMed

The purpose of this in vitro study was to evaluate the bonding durability of three self-adhesive resin cements to titanium using the Highly Accelerated Life Test (HALT). The following self-adhesive resin cements were used to bond pairs of titanium blocks together according to manufacturers' instructions: RelyX Unicem, Breeze, and Clearfil SA Luting. After storage in water at 37°C for 24 h, bonded specimens (n=15) immersed in 37°C water were subjected to cyclic shear load testing regimes of 20, 30, or 40 kg using a fatigue testing machine. Cyclic loading continued until failure occurred, and the number of cycles taken to reach failure was recorded. The bonding durability of a self-adhesive resin cement to titanium was largely influenced by the weight of impact load. HALT showed that Clearfil SA Luting, which contained MDP monomer, yielded the highest median bonding lifetime to titanium. PMID:22123007

Lin, Jie; Shinya, Akikazu; Gomi, Harunori; Matinlinna, Jukka Pekka; Shinya, Akiyoshi

2011-11-25

410

The Design and Testing of a Dual Fiber Textile Matrix for Accelerating Surface Hemostasis  

PubMed Central

The standard treatment for severe traumatic injury is frequently compression and application of gauze dressing to the site of hemorrhage. However, while able to rapidly absorb pools of shed blood, gauze fails to provide strong surface (topical) hemostasis. The result can be excess hemorrhage-related morbidity and mortality. We hypothesized that cost-effective materials (based on widespread availability of bulk fibers for other commercial uses) could be designed based on fundamental hemostatic principles to partially emulate the wicking properties of gauze while concurrently stimulating superior hemostasis. A panel of readily available textile fibers was screened for the ability to activate platelets and the intrinsic coagulation cascade in vitro. Type E continuous filament glass and a specialty rayon fiber were identified from the material panel as accelerators of hemostatic reactions and were custom woven to produce a dual fiber textile bandage. The glass component strongly activated platelets while the specialty rayon agglutinated red blood cells. In comparison with gauze in vitro, the dual fiber textile significantly enhanced the rate of thrombin generation, clot generation as measured by thromboelastography, adhesive protein adsorption and cellular attachment and activation. These results indicate that hemostatic textiles can be designed that mimic gauze in form but surpass gauze in ability to accelerate hemostatic reactions.

Fischer, Thomas H.; Vournakis, John N.; Manning, James E.; McCurdy, Shane L.; Rich, Preston B.; Nichols, Timothy C.; Scull, Christopher M.; McCord, Marian G.; Decorta, Joseph A.; Johnson, Peter C.; Smith, Carr J.

2011-01-01

411

Performance Evaluation of New Generation 50th Percentile Anthropomorphic Test Devices - Volume II - Accelerator Sled Test Data.  

National Technical Information Service (NTIS)

Four sled test configurations were employed to evaluate the dynamic performance repeatability of the GM 50X dummy. Type 2 belt, pre-inflated air bag, energy absorbing steering column, and Type 1 belt with simulated instrument panel test environments were ...

D. E. Massing K. N. Naab P. E. Yates

1975-01-01

412

Accelerated Full Scale Fatigue Testing Of A Small Composite Wind Turbine Blade Using A Mechanically Operated Test Rig  

Microsoft Academic Search

A 2.5m long glass fibre reinforced plastic composite wind turbine blade was fatigue tested by means of a mechanically operated test rig. The rig uses a crank eccentric mechanism to flex the blade by a constant displacement in the flapwise direction for each load cycle. A yearly fatigue-loading spectrum for the blades has been developed from using short-term detailed aeroelastic

Jayantha A. Epaarachchi; Philip D. Clausen

2004-01-01

413

A MODIFIED PMMA CEMENT (SUB-CEMENT) FOR ACCELERATED FATIGUE TESTING OF CEMENTED IMPLANT CONSTRUCTS USING CADAVERIC BONE  

PubMed Central

Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress intensity factor, fatigue crack propagation rates for sub-cement were higher by a factor of 25 ± 19. When tested in a simplified 2 1/2D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models.

Race, Amos; Miller, Mark A.; Mann, Kenneth A.

2008-01-01

414

Concept of a New Multifunctional Space Simulator for Accelerated Ground-based Testing in Modern Space Exploration Era  

NASA Astrophysics Data System (ADS)

A new ground-based facility concept is introduced to provide for reliable, accelerated multi-environmental laboratory testing of spacecraft materials, systems and components in the simulated LEO, GEO and HEO space environments, as well as environmental conditions of other planets. The proposed concept of the multifunctional simulator facility is based on the Variable Energy Multifunctional Environment Simulator™ facility successfully manufactured by ITL Inc. and includes three stainless steel ultra-high vacuum chambers connected by gate valves and a sample-transfer system via an air lock chamber. These simulation chambers are used to expose the test samples to combined or individual influence of ultra-high vacuum conditions, variable-energy neutral atomic beams, variable-wavelength UV radiation, variable-energy charged particles, thermal conditioning, thermal cycling, contaminations and accelerated dust particles, with a variety of analytical capabilities. The proposed unique multifunctional space simulator is fully computer-controlled and is operated by powerful computer software implementing the physical models of various space environments.

Kleiman, J.; Horodetsky, S.; Issoupov, V.

2009-01-01

415

Methodology for designing accelerated aging tests for predicting life of photovoltaic arrays  

NASA Technical Reports Server (NTRS)

A methodology for designing aging tests in which life prediction was paramount was developed. The methodology builds upon experience with regard to aging behavior in those material classes which are expected to be utilized as encapsulant elements, viz., glasses and polymers, and upon experience with the design of aging tests. The experiences were reviewed, and results are discussed in detail.

Gaines, G. B.; Thomas, R. E.; Derringer, G. C.; Kistler, C. W.; Bigg, D. M.; Carmichael, D. C.

1977-01-01

416

Long life nickel electrodes for a nickel-hydrogen cell. III - Results of an accelerated test and failure analyses  

NASA Technical Reports Server (NTRS)

Nineteen different designs of nickel electrodes were tested in Ni/H2 boiler plate cells in an accelerated low earth orbit cycle regime to the end of their life. The failure analyses of these cells showed that the major performance changes due to the cycling was a severe reduction of their high rate discharge capability rather than an absolute capacity reduction. Many physical changes of the nickel electrodes were observed after the cycling test. These changes include dimensional expansion, sinter rupture, loose black powdering of the active material, morphology changes, active material migration, increase of pore volume, change of pore distribution, and increase of surface area. All of these were caused by active material expansion with cycling. Among these changes, the morphology change which involves migration of active material away from the current collecting nickel sinter appears to be that most responsible for the reduction of the rate capability.

Lim, H. S.; Verzwyvelt, S. A.

1984-01-01

417

An investigation of the NOCSAE linear impactor test method based on in vivo measures of head impact acceleration in American football.  

PubMed

The performance characteristics of football helmets are currently evaluated by simulating head impacts in the laboratory using a linear drop test method. To encourage development of helmets designed to protect against concussion, the National Operating Committee for Standards in Athletic Equipment recently proposed a new headgear testing methodology with the goal of more closely simulating in vivo head impacts. This proposed test methodology involves an impactor striking a helmeted headform, which is attached to a nonrigid neck. The purpose of the present study was to compare headform accelerations recorded according to the current (n=30) and proposed (n=54) laboratory test methodologies to head accelerations recorded in the field during play. In-helmet systems of six single-axis accelerometers were worn by the Dartmouth College men's football team during the 2005 and 2006 seasons (n=20,733 impacts; 40 players). The impulse response characteristics of a subset of laboratory test impacts (n=27) were compared with the impulse response characteristics of a matched sample of in vivo head accelerations (n=24). Second- and third-order underdamped, conventional, continuous-time process models were developed for each impact. These models were used to characterize the linear head/headform accelerations for each impact based on frequency domain parameters. Headform linear accelerations generated according to the proposed test method were less similar to in vivo head accelerations than headform accelerations generated by the current linear drop test method. The nonrigid neck currently utilized was not developed to simulate sport-related direct head impacts and appears to be a source of the discrepancy between frequency characteristics of in vivo and laboratory head/headform accelerations. In vivo impacts occurred 37% more frequently on helmet regions, which are tested in the proposed standard than on helmet regions tested currently. This increase was largely due to the addition of the facemask test location. For the proposed standard, impactor velocities as high as 10.5 m/s were needed to simulate the highest energy impacts recorded in vivo. The knowledge gained from this study may provide the basis for improving sports headgear test apparatuses with regard to mimicking in vivo linear head accelerations. Specifically, increasing the stiffness of the neck is recommended. In addition, this study may provide a basis for selecting appropriate test impact energies for the standard performance specification to accompany the proposed standard linear impactor test method. PMID:20524744

Gwin, Joseph T; Chu, Jeffery J; Diamond, Solomon G; Halstead, P David; Crisco, Joseph J; Greenwald, Richard M

2010-01-01

418

First Accelerator Test of the Kinematic Lightweight Energy Meter (KLEM) Prototype  

NASA Technical Reports Server (NTRS)

The essence of the KLEM (Kinematic Lightweight Energy Meter) instrument is to directly measure the elemental energy spectra of high-energy cosmic rays by determining the angular distribution of secondary particles produced in a target. The first test of the simple KLEM prototype has been performed at the CERN SPS test-beam with 180 GeV pions during 2001. The results of the first test analysis confirm that, using the KLEM method, the energy of 180 GeV pions can be measured with a relative error of about 67%, which is very close to the results of the simulation (65%).

Bashindzhagyan, G.; Adams, J. H.; Bashindzhagyan, P.; Chilingarian, A.; Donnelly, J.; Drury, L.; Egorov, N.; Golubkov, S.; Grebenyuk, V.; Kalinin, A.; Six, N. Frank (Technical Monitor)

2002-01-01

419

Reliability and Validity of a New Test of Change-of-Direction Speed for Field-Based Sports: the Change-of-Direction and Acceleration Test (CODAT).  

PubMed

Field sport coaches must use reliable and valid tests to assess change-of-direction speed in their athletes. Few tests feature linear sprinting with acute change- of-direction maneuvers. The Change-of-Direction and Acceleration Test (CODAT) was designed to assess field sport change-of-direction speed, and includes a linear 5-meter (m) sprint, 45° and 90° cuts, 3- m sprints to the left and right, and a linear 10-m sprint. This study analyzed the reliability and validity of this test, through comparisons to 20-m sprint (0-5, 0-10, 0-20 m intervals) and Illinois agility run (IAR) performance. Eighteen Australian footballers (age = 23.83 ± 7.04 yrs; height = 1.79 ± 0.06 m; mass = 85.36 ± 13.21 kg) were recruited. Following familiarization, subjects completed the 20-m sprint, CODAT, and IAR in 2 sessions, 48 hours apart. Intra-class correlation coefficients (ICC) assessed relative reliability. Absolute reliability was analyzed through paired samples t-tests (p ? 0.05) determining between-session differences. Typical error (TE), coefficient of variation (CV), and differences between the TE and smallest worthwhile change (SWC), also assessed absolute reliability and test usefulness. For the validity analysis, Pearson's correlations (p ? 0.05) analyzed between-test relationships. Results showed no between-session differences for any test (p = 0.19-0.86). CODAT time averaged ~6 s, and the ICC and CV equaled 0.84 and 3.0%, respectively. The homogeneous sample of Australian footballers meant that the CODAT's TE (0.19 s) exceeded the usual 0.2 x standard deviation (SD) SWC (0.10 s). However, the CODAT is capable of detecting moderate performance changes (SWC calculated as 0.5 x SD = 0.25 s). There was a near perfect correlation between the CODAT and IAR (r = 0.92), and very large correlations with the 20-m sprint (r = 0.75-0.76), suggesting that the CODAT was a valid change-of-direction speed test. Due to movement specificity, the CODAT has value for field sport assessment. Key pointsThe change-of-direction and acceleration test (CODAT) was designed specifically for field sport athletes from specific speed research, and data derived from time-motion analyses of sports such as rugby union, soccer, and Australian football. The CODAT features a linear 5-meter (m) sprint, 45° and 90° cuts and 3-m sprints to the left and right, and a linear 10-m sprint.The CODAT was found to be a reliable change-of-direction speed assessment when considering intra-class correlations between two testing sessions, and the coefficient of variation between trials. A homogeneous sample of Australian footballers resulted in absolute reliability limitations when considering differences between the typical error and smallest worthwhile change. However, the CODAT will detect moderate (0.5 times the test's standard deviation) changes in performance.The CODAT correlated with the Illinois agility run, highlighting that it does assess change-of-direction speed. There were also significant relationships with short sprint performance (i.e. 0-5 m and 0-10 m), demonstrating that linear acceleration is assessed within the CODAT, without the extended duration and therefore metabolic limitations of the IAR. Indeed, the average duration of the test (~6 seconds) is field sport-specific. Therefore, the CODAT could be used as an assessment of change-of-direction speed in field sport athletes. PMID:24149730

Lockie, Robert G; Schultz, Adrian B; Callaghan, Samuel J; Jeffriess, Matthew D; Berry, Simon P

2013-01-01

420

Lifetime Measurements of Carbon and Diamond Stripping Foils Tested in the Fermi National Accelerator Laboratory Linac  

Microsoft Academic Search

A foil testing apparatus was fabricated to test carbon versus diamond stripper foil life expectancy. The goal of this experiment is to find a target material more suitable for the proposed multi-mega-watt 8-GeV proton driver and booster system, which uses multiturn charge-exchange injection. Preparation includes tuning bending and quadrupole magnets and doing calculations of pertinent theoretical values, such as instantaneous

Trivia Penns Frazier

421

An accelerated stability test using the peroxide value as an index  

Microsoft Academic Search

Summary  A quick stability test for lard is described which depends on the peroxide content for identification of the rancid point.\\u000a By its use ordinary samples of lard can be evaluated for stability in a working day. Oleo oil also is being tested by this\\u000a method. It is applicable to edible fats and oils and hydrogenated shortenings. Typical peroxide curves for

A. E. King; H. L. Roschen; W. H. Irwin

1933-01-01

422

An investigation into the use of MMCTP to tune accelerator source parameters and testing its clinical application.  

PubMed

This paper presents an alternative method to tune Monte Carlo electron beam parameters to match measured data using a minimal set of variables in order to reduce the model setup time prior to clinical implementation of the model. Monte Carlo calculations provide the possibility of a powerful treatment planning verification technique. The nonstandardized and nonautomated process of tuning the required accelerator model is one of the reasons for delays in the clinical implementation of Monte Carlo techniques. This work aims to establish and verify an alternative tuning method that can be carried out in a minimal amount of time, allowing it to be easily implemented in a clinical setting by personnel with minimal experience with Monte Carlo methods. This tuned model can then be incorporated into the MMCTP system to allow the system to be used as a second dose calculation check for IMRT plans. The technique proposed was used to establish the primary electron beam parameters for accelerator models for the Varian Clinac 2100 6 MV photon beam using the BEAMnrc Monte Carlo system. The method is intended to provide a clear, direct, and efficient process for tuning an accelerator model using readily available clinical quality assurance data. The tuning provides a refined model, which agrees with measured dose profile curves within 1.5% outside the penumbra or 3 mm in the penumbra, for square fields with sides of 3 cm up to 30 cm. These models can then be employed as the basis for Monte Carlo recalculations of dose distributions, using the MMCTP system, for clinical treatment plans, providing an invaluable assessment tool. This was tested on six IMRT plans and compared to the measurements performed for the pretreatment QA process. These Monte Carlo values for the average dose to the chamber volume agreed with measurements to within 0.6%. PMID:23470925

Conneely, Elaine; Alexander, Andrew; Stroian, Gabriella; Seuntjens, Jan; Foley, Mark J

2013-01-01

423

THE MECHANICAL AND SHIELDING DESIGN OF A PORTABLE SPECTROMETER AND BEAM DUMP ASSEMBLY AT BNLS ACCELERATOR TEST FACILITY.  

SciTech Connect

A portable assembly containing a vertical-bend dipole magnet has been designed and installed immediately down-beam of the Compton electron-laser interaction chamber on beamline 1 of the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL). The water-cooled magnet designed with field strength of up to 0.7 Tesla will be used as a spectrometer in the Thompson scattering and vacuum acceleration experiments, where field-dependent electron scattering, beam focusing and energy spread will be analyzed. This magnet will deflect the ATF's 60 MeV electron-beam 90{sup o} downward, as a vertical beam dump for the Compton scattering experiment. The dipole magnet assembly is portable, and can be relocated to other beamlines at the ATF or other accelerator facilities to be used as a spectrometer or a beam dump. The mechanical and shielding calculations are presented in this paper. The structural rigidity and stability of the assembly were studied. A square lead shield surrounding the assembly's Faraday Cup was designed to attenuate the radiation emerging from the 1 inch-copper beam stop. All photons produced were assumed to be sufficiently energetic to generate photoneutrons. A safety evaluation of groundwater tritium contamination due to the thermal neutron capturing by the deuterium in water was performed, using updated Monte Carlo neutron-photon coupled transport code (MCNP). High-energy neutron spallation, which is a potential source to directly generate radioactive tritium and sodium-22 in soil, was conservatively assessed in verifying personal and environmental safety.

HU,J.P.; CASEY,W.R.; HARDER,D.A.; PJEROV,S.; RAKOWSKY,G.; SKARITKA,J.R.

2002-09-05

424

Testing Models of Accretion-Driven Coronal Heating and Stellar Wind Acceleration for T Tauri Stars  

NASA Astrophysics Data System (ADS)

Classical T Tauri stars are pre-main-sequence objects that undergo simultaneous accretion, wind outflow, and coronal X-ray emission. The impact of plasma on the stellar surface from magnetospheric accretion streams is likely to be a dominant source of energy and momentum in the upper atmospheres of these stars. This paper presents a set of models for the dynamics and heating of three distinct regions on T Tauri stars that are affected by accretion: (1) the shocked plasmas directly beneath the magnetospheric accretion streams, (2) stellar winds that are accelerated along open magnetic flux tubes, and (3) closed magnetic loops that resemble the Sun's coronal active regions. For the loops, a self-consistent model of coronal heating was derived from numerical simulations of solar field-line tangling and turbulent dissipation. Individual models are constructed for the properties of 14 well-observed stars in the Taurus-Auriga star-forming region. Predictions for the wind mass-loss rates are, on average, slightly lower than the observations, which suggests that disk winds or X-winds may also contribute to the measured outflows. For some of the stars, however, the modeled stellar winds do appear to contribute significantly to the measured mass fluxes. Predictions for X-ray luminosities from the shocks and loops are in general agreement with existing observations. The stars with the highest accretion rates tend to have X-ray luminosities dominated by the high-temperature (5-10 MK) loops. The X-ray luminosities for the stars having lower accretion rates are dominated by the cooler accretion shocks.

Cranmer, Steven R.

2009-11-01

425

Accelerated testing of HT-9 with zirconia coatings containing gallium using Raman Spectroscopy and XPS  

NASA Astrophysics Data System (ADS)

Laser Raman spectroscopy and X-ray photoelectron spectroscopy were used to study the evolution of composition of oxide films in the presence of zirconia coatings on miniature HT-9 alloy specimens subjected to elevated temperature in air. The experiments expanded on previous efforts to develop a quick-screening technique for candidate alloys for cladding materials (HT-9) and actinide-based mixed oxide fuel mixtures (represented by the zirconia coating) by investigating the effect of both coating composition and annealing conditions on the high temperature reactions. In particular, the presence of the element Ga (a potential impurity in mixed oxide fuel) in the initial zirconia coating was found to accelerate the rate of oxide growth relative to that of yttria-stabilized zirconia studied previously. In addition, HT-9 samples that were subjected to different annealing conditions gave different results. The results suggest that the presence of Ga in a mixed oxide fuel will enhance the oxidation of HT-9 cladding under the conditions of this study, although the extent of enhancement is influenced by the type of annealing previously applied to the cladding material. Due to the multi-component layered structure of the oxidation products discovered in this fuel-cladding combination, it appears unlikely that Raman spectroscopy would be applicable as a stand-alone technique for the intended quick-screening approach to all but the simplest systems. Other techniques with better depth resolution, such as photoelectron spectroscopy, are required to follow the changes in composition of individual layers as they evolve during the oxidation process.

Windisch, Charles F., Jr.; Henager, Charles H., Jr.; Engelhard, Mark H.; Bennett, Wendy D.

2009-12-01

426

Assembly and Test of SQ01b, a Nb3Sn Quadrupole Magnet for the LHC Accelerator Research Program  

SciTech Connect

The US LHC Accelerator Research Program (LARP) consists of four US laboratories (BNL, FNAL, LBNL, and SLAC) collaborating with CERN to achieve a successful commissioning of the LHC and to develop the next generation of Interaction Region magnets. In 2004, a large aperture Nb{sub 3}Sn racetrack quadrupole magnet (SQ01) has been fabricated and tested at LBNL. The magnet utilized four subscale racetrack coils and was instrumented with strain gauges on the support structure and directly over the coil's turns. SQ01 exhibited training quenches in two of the four coils and reached a peak field in the conductor of 10.4 T at a current of 10.6 kA. After the test, the magnet was disassembled, inspected with pressure indicating films, and reassembled with minor modifications. A second test (SQ01b) was performed at FNAL and included training studies, strain gauge measurements and magnetic measurements. Magnet inspection, test results, and magnetic measurements are reported and discussed, and a comparison between strain gauge measurements and 3D finite element computations is presented

Ferracin, P.; Ambrosio, G.; Bartlett, S. E.; Bordini, B.; Carcagno, R.H.; Caspi, S.; Dietderich, D.R.; Feher, S.; Gourlay, S.A.; Hafalia, A.R.; Lamm, M.J.; Lietzke, A.F.; Mattafirri, S.; McInturff, A.D.; Orris, D.F.; Pischalnikov, Y.M.; Sabbi, G.L.; Sylvester, C.D.; Tartaglia, M.A.; Velev, G.V.; Zlobin, A.V.; Kashikhin, V.V.

2006-06-01

427

ACCELERATED TESTING OF ULTRASONIC WELDING FOR CRYSTALLINE SILICON ON GLASS MODULES  

Microsoft Academic Search

Ultrasonic welding has been demonstrated to be a viable alternative tabbing process to ultrasonic soldering for Crystalline Silicon on Glass (CSG) modules. Orthodyne Electronics ultrasonically welded tab ribbons to CSG test coupons to determine the influence of substrate conditions on bond quality. Substrate texture and silicon were the most important parameters to achieve reliable low contact resistivity bonds. Ultrasonically welded

Stefan Jarnason; Christoph Luechinger

428

Thermal Vacuum Accelerated Life Test on a Prototype Teldix Single-Gimballed Momentum Wheel.  

National Technical Information Service (NTIS)

A prototype TELDIX single-gimballed momentum wheel (SGMW) has been tested in vacuum at isothermal temperatures and with various thermal gradients. The mechanism consists of a momentum wheel which is oscillated in one plane through + or - 5 deg angular mot...

K. Parker J. C. Anderson

1979-01-01

429

Analysis of Accelerations Measured during Full-Scale Tank Car Impact Tests.  

National Technical Information Service (NTIS)

Tank car impact responses were investigated using accelerometers mounted at various locations on a tank car. Several tests were run with both a full and an empty tank car, and varying the tank car impact speed. The data from the accelerometers went throug...

K. W. Koch M. L. Lyons W. T. Riddell

2007-01-01

430

A Ball Bearing Simulator—A Tool for Accelerated Testing of Self-lubricated Bearings  

Microsoft Academic Search

A special test station was designed and developed to examine self-lubricating composite wear rate and the mechanism of transfer film formation that occur in bearings operating with composite retainers. The apparatus is constructed to approximate (a) the sliding contact between the ball separator pockets and the balls and (b) the rolling contact between bearing balls and races. The ball bearing

Michael N. Gardos; Donald F. Preston

1977-01-01

431

Optimal Estimation of the Acceleration of a Car Under Performance Tests  

Microsoft Academic Search

In this paper, a recursive least-squares lattice (RLSL) adaptive filter was used to carry out the optimal estimation of the relevant signal coming from an accelerometer placed in car under performance tests. Here, the signal of interest is buried in a broadband noise background where we have little knowledge of the noise characteristics. In addition, due to the fact that

Wilmar Hernandez

2007-01-01

432

High speed photographic verification of intravascular stent strains during accelerated durability testing.  

PubMed

Most stent durability testing does not predict resulting clinical failures. Standards committees have taken on the task of generating more reliable test protocols. Currently, the AAMI/ISO Committee has chosen an experimental direction that allows an investigator to test at ultra high frequencies (above 1000 bpm) as long as the actual strain of the stents can be verified to be moving the same amount per cycle that they do during real time testing (70 to 72 bpm). We have developed a series of techniques and protocols utilizing high-speed photographic analysis to accomplish this. The first aspect requires the utilization of ultra clear silicone mock arteries. It is important that optical anomalies do not cause aberrations in the analysis. Next is the relationship between the angle of the incident lighting and the positioning of the camera in front of the pulsing tube. Finally, a unique set of marking techniques which are used as tracking locations for the automatic measurement systems located in the software of the camera have certain characteristics that are important with respect to accurate measurements. In each case the particular setup must have independent verification of the accuracy of the measurements. We will review these variables and demonstrate how this system can be utilized to verify strains of the inside wall, outside wall, and stent. PMID:15133961

Kattekola, Brunda; Conti, J C; Strope, E R

2004-01-01

433

A new approach of accelerated life testing for metallic catalytic converters  

Microsoft Academic Search

The Environmental Protection Agency (EPA) and California Air Resources Board (CARB) requirements for high mileage durability of emission components make it necessary to ensure the mechanical robustness of metallic catalytic converters. In addition, the robustness of design features must be assessed in the early design development phase without resorting to vehicle fleet testing. By following established reliability methods, a new

Thomas Nagel; Jan Kramer; Manuel Presti; Axel Schatz; Juergen Breuer; Ron Salzman; John A. Scaparo; Andrew J. Montalbano

2004-01-01

434

Phase-scan analysis results for the first drift tube linac module in the ground test accelerator: Data reproducibility and comparison to simulations  

SciTech Connect

The Ground Test Accelerator (GTA) had the objective of producing a high-brightness, high-current H- beam. The major accelerator components were a 35 keV injector, a Radio Frequency Quadrupole, an intertank matching section, and a drift tube linac (DTL), consisting of 10 modules. This paper discusses the phase-scan technique which was used to experimentally determine the rf operating parameters for the commissioning and routine operation of the first DTL module.

Johnson, K.F.; Sander, O.R.; Bolme, G.O. [and others

1995-05-01

435

Phase-scan analysis results for the first drift tube linac module in the Ground Test Accelerator: data reproducibility and comparison to simulations  

Microsoft Academic Search

The Ground Test Accelerator (GTA) had the objective of producing a high-brightness, high-current H- beam. The major accelerator components were a 35 keV injector, a Radio Frequency Quadrupole, an intertank matching section, and a drift tube linac (DTL), consisting of 10 modules. This paper discusses the phase-scan technique which was used to experimentally determine the rf operating parameters for the

K. F. Johnson; O. R. Sander; G. O. Bolme; S. Bowling; R. Connolly; J. D. Gilpatrick; W. P. Lysenko; J. Power; E. A. Wadlinger; V. Yuan

1995-01-01

436

Accelerated corrosion testing, evaluation and durability design of bonded post-tensioned concrete tendons  

NASA Astrophysics Data System (ADS)

In the last few years, the effectiveness of cement grout in galvanized or polyethylene ducts, the most widely used corrosion protection system for multistrand bonded post-tensioned concrete tendons, has been under debate, due to significant tendon corrosion damage, several reported failures of individual tendons as well as a few collapses of non-typical structures. While experience in the USA has been generally good, some foreign experience has been less than satisfactory. This dissertation is part of a comprehensive research program started in 1993, which has the objectives to examine the use of post-tensioning in bridge substructures, identify durability concerns and existing technology, develop and carry out an experimental testing program, and conclude with durability design guidelines. Three experimental programs were developed: A long term macrocell corrosion test series, to investigate corrosion protection for internal tendons in precast segmental construction; a long term beam corrosion test series, to examine the effects of post-tensioning on corrosion protection as affected by crack width; and, a long term column corrosion test series, to examine corrosion protection in vertical elements. Preliminary design guidelines were developed previously in the overall study by the initial researchers, after an extensive literature review. This dissertation scope includes continuation of exposure testing of the macrocell, beam and column specimens, performing comprehensive autopsies of selected specimens and updating the durability design guidelines based on the exposure testing and autopsy results. After autopsies were performed, overall findings indicate negative durability effects due to the use of mixed reinforcement, small concrete covers, galvanized steel ducts, and industry standard or heat-shrink galvanized duct splices. The width of cracks was shown to have a direct negative effect on specimen performance. Grout voids were found to be detrimental to the durability of both galvanized ducts and strand. Relying on epoxy and galvanized bar coatings was also found inappropriate because of local attack. On the other hand, very positive effects were found with the use of high performance concrete, high post-tensioning levels, plastic ducts, and sound epoxy filling at the joints.

Salas Pereira, Ruben Mario

2003-06-01

437

Characterization of electron clouds in the Cornell Electron Storage Ring Test Accelerator using TE-wave transmission  

SciTech Connect

A relatively new technique for measuring the electron cloud density in storage rings has been developed and successfully demonstrated [S. De Santis, J.M. Byrd, F. Caspers, A. Krasnykh, T. Kroyer, M.T.F. Pivi, and K.G. Sonnad, Phys. Rev. Lett. 100, 094801 (2008).]. We present the experimental results of a systematic application of this technique at the Cornell Electron Storage Ring Test Accelerator. The technique is based on the phase modulation of the TE mode transmitted in a synchrotron beam pipe caused by the periodic variation of the density of electron plasma. Because of the relatively simple hardware requirements, this method has become increasingly popular and has been since successfully implemented in several machines. While the principles of this technique are straightforward, quantitative derivation of the electron cloud density from the measurement requires consideration of several effects, which we address in detail.

De Santis, S.; Byrd, J. M.; Billing, M.; Palmer, M.; Sikora, J.; Carlson, B.

2010-01-02

438

Architecture, implementation, and testing of a multiple-shell gas injection system for high current implosions on the Z accelerator  

SciTech Connect

Tests are ongoing to conduct {approx}20 MA z-pinch implosions on the Z accelerator at Sandia National Labor