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1

Accelerated life-time testing and resistance degradation of thin-film decoupling capacitors  

SciTech Connect

Resistance degradation in PZT thin-film capacitors has been studied as a function of applied voltage, temperature, and film composition. It is found that the mean-time-to-failure (life-time or t{sub f}) of the capacitors shows a power law dependence on applied voltage of he form t{sub f} {proportional_to} V{sup {minus}n} (n {approximately} 4--5). The capacitor life-time also exhibits a temperature dependence of the form t{sub f} {proportional_to} exp(E{sub a}/kT), with an activation energy of {approximately} 0.8 eV. The steady-state leakage current in these samples appears to be bulk controlled. The voltage, temperature, and polarity dependence of the leakage current collectively suggest a leakage current mechanism most similar to a Frenkel-Poole process. The life-time and leakage current of the Nb-doped PZT films are superior to the undoped PZT films. This result can be explained based on the point-defect chemistry of the PZT system. Finally, the results indicate that the Nb-doped PZT films meet the essential requirements for decoupling capacitor applications.

Al-Shareef, H.; Dimos, D.

1996-09-01

2

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

3

Advanced Test Accelerator (ATA) injector  

SciTech Connect

The ATA injector, developed from experience gained from the Experimental Test Accelerator (ETA) linac, has recently been completed. The injector consists of ten 0.25 MV cells that are used to develop 2.5 MV across a single diode gap. The 10 kA beam is extracted from a 500 cm/sup 2/ plasma cathode at average rates of up to 5 Hz and burst rates to 1 kHz. Pulsed power from 20 water filled blumleins is divided and introduced symmetrically through four ports on each cell. All major insulators are fabricated from filled epoxy castings. With these improvements, the ATA injector is smaller than the ETA injector; has a faster pulse response; has lower voltage stress on insulators and higher ultimate performance. Injector characterization tests began in October 1982. These tests include beam current, energy, and emittance measurements.

Jackson, C.H.; Bubp, D.G.; Fessenden, T.J.; Hester, R.E.; Neil, V.K.; Paul, A.C.; Prono, D.S.

1983-03-09

4

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

5

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

6

A Review of Accelerated Test Models  

Microsoft Academic Search

Engineers in the manufacturing industries have used accelerated test (AT) experiments for many decades. The purpose of AT experiments is to acquire reliability information quickly. Test units of a material, component, subsystem or entire systems are subjected to higher-than-usual levels of one or more accelerating variables such as temperature or stress. Then the AT results are used to predict life

Luis A. Escobar; William Q. Meeker

2006-01-01

7

Accelerator Test of an Imaging Calorimeter  

NASA Technical Reports Server (NTRS)

The Imaging Calorimeter for ACCESS (ICA) utilizes a thin sampling calorimeter concept for direct measurements of high-energy cosmic rays. The ICA design uses arrays of small scintillating fibers to measure the energy and trajectory of the produced cascades. A test instrument has been developed to study the performance of this concept at accelerator energies and for comparison with simulations. Two test exposures have been completed using a CERN test beam. Some results from the accelerator tests are presented.

Christl, Mark J.; Adams, James H., Jr.; Binns, R. W.; Derrickson, J. H.; Fountain, W. F.; Howell, L. W.; Gregory, J. C.; Hink, P. L.; Israel, M. H.; Kippen, R. M.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

8

ACCELERATED EXPOSURE TESTING Accelerated exposure testing has become increasingly  

E-print Network

Consortium (IEC) Underwriters Laboratories (UL) Deutsche Norm (DIN) FACILITIES Test chambers control system developed at SwRI constantly collects environmental test data for real-time analysis measurement Laboratory earthquake simulation Vibration testing Component design Failure analysis Federal

Chapman, Clark R.

9

Accelerated stress testing of terrestrial solar cells  

NASA Technical Reports Server (NTRS)

The development of an accelerated test schedule for terrestrial solar cells is described. This schedule, based on anticipated failure modes deduced from a consideration of IC failure mechanisms, involves bias-temperature testing, humidity testing (including both 85-85 and pressure cooker stress), and thermal-cycle thermal-shock testing. Results are described for 12 different unencapsulated cell types. Both gradual electrical degradation and sudden catastrophic mechanical change were observed. These effects can be used to discriminate between cell types and technologies relative to their reliability attributes. Consideration is given to identifying laboratory failure modes which might lead to severe degradation in the field through second quadrant operation. Test results indicate that the ability of most cell types to withstand accelerated stress testing depends more on the manufacturer's design, processing, and worksmanship than on the particular metallization system. Preliminary tests comparing accelerated test results on encapsulated and unencapsulated cells are described.

Lathrop, J. W.; Hawkins, D. C.; Prince, J. L.; Walker, H. A.

1982-01-01

10

46 CFR 160.072-5 - Accelerated weathering test.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Accelerated weathering test. 160.072-5 Section 160...Flag § 160.072-5 Accelerated weathering test. (a) Condition the flag...d) The flag fails the accelerated weathering test if (1) After...

2012-10-01

11

46 CFR 160.072-5 - Accelerated weathering test.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Accelerated weathering test. 160.072-5 Section 160...Flag § 160.072-5 Accelerated weathering test. (a) Condition the flag...d) The flag fails the accelerated weathering test if (1) After...

2011-10-01

12

46 CFR 160.072-5 - Accelerated weathering test.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Accelerated weathering test. 160.072-5 Section 160...Flag § 160.072-5 Accelerated weathering test. (a) Condition the flag...d) The flag fails the accelerated weathering test if (1) After...

2013-10-01

13

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

14

Accelerated testing of copper corrosion  

SciTech Connect

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. Initial work successfully reproduced soft-water copper pitting in the laboratory using a synthetic water, facilitating future studies of pit initiation and potential remedies. Relative pitting tendencies were predicted using the short-term test, as was the long-term release of the by-products of copper corrosion. Pitting severity increased with increasing pH and duration of stagnation and decreased in the presence of natural organic matter or chlorine residuals.

Edwards, M. (Univ. of Colorado, Boulder, CO (United States). Dept. of Civil Engineering); Ferguson, J.F. (Univ. of Washington, Seattle, WA (United States). Dept. of Civil Engineering)

1993-10-01

15

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

16

Accelerator Tests of Crystal Undulators  

E-print Network

A series of Silicon crystal undulator samples were produced based on the approach presented in PRL 90 (2003) 034801, with the periods of undulation from 0.1 mm to 1 mm, and the number of periods on the order of 10. The samples were characterized by X-rays, revealing the sine-like shape of the crystal lattice in the bulk. Next step in the characterization has been the channeling tests done with 70 GeV protons, where good channeling properties of the undulated Silicon lattice have been observed. The photon radiation tests of crystal undulators with high energy positrons are in progress on several locations: IHEP Protvino, LNF Frascati, and CERN SPS. The progress in the experimental activities and the predictions from detailed simulations are reported.

Biryukov, V M; Baranov, V T; Baricordi, S; Bellucci, S; Britvich, G I; Chepegin, V N; Chesnokov, Yu A; Balasubramanian, C; Giannini, G; Guidi, V; Ivanov, Y M; Kotov, V I; Kushnirenko, A; Maisheev, V A; Malagu, C; Martinelli, G; Milan, E; Petrunin, A A; Pikalov, V A; Skorobogatov, V V; Stefancich, M; Terekhov, V I; Tombolini, F; Uggerhøj, U; Chesnokov, Yu.A.; Ivanov, Yu.M.

2004-01-01

17

Test particle acceleration in torsional fan reconnection  

NASA Astrophysics Data System (ADS)

Magnetic reconnection is understood to be a potential mechanism for particle acceleration in astrophysical and space plasmas, especially in solar flares. Torsional fan reconnection is one of the proposed mechanisms for steady-state three-dimensional (3D) magnetic reconnection. By using the magnetic and electric fields for `torsional fan reconnection', the features of test particle acceleration with input parameters for the solar corona are investigated numerically. We show that torsional fan reconnection is potentially an efficient particle accelerator and a proton can gain up to tens of MeV of kinetic energy within only a few milliseconds. Although the final kinetic energy of the accelerated particle depends on the injection position but there exists only one scenario for the particle's trajectory with different initial positions in which the particle is accelerated on the fan plane. Moreover, adopting either spatially uniform or non-uniform localized plasma resistivity does not much influence the features of trajectory. These results are compared with those of torsional spine reconnection.

Hosseinpour, M.

2014-12-01

18

Accelerated aging test on LEDs life estimation  

NASA Astrophysics Data System (ADS)

Light-emitting diodes(LEDs) have become very attractive in different application field such as Solid State Lighting, automotive and street lights, due to their long operative lifetime, lower energy consumption etc. This paper mainly introduces the accelerated aging test, we focus our attention on the study of a life model for LEDs by relating the time to failure with the supplying condition. The constant accelerated aging experiments were firstly performed on LED samples. Process the experiment data by exploiting the degradation of LED optical power formula and degradation coefficient. Finally, the average lifetime of the samples under normal conditions was calculated via using numerical analytical method. According to data, analysis the test result and the failure mechanism of LED, provide the technical basis to improve product design and quality assurance.

Dong, Yi; Zhang, Shu-sheng; Du, Jiang-qi

2011-11-01

19

VACUUM LASER ACCELERATION EXPERIMENT PERSPECTIVE AT BROOKHAVEN NATIONAL LAB-ACCELERATOR TEST FACILITY  

E-print Network

VACUUM LASER ACCELERATION EXPERIMENT PERSPECTIVE AT BROOKHAVEN NATIONAL LAB-ACCELERATOR TEST This first stage experiment is a Proof-of-Principle to support our novel vacuum laser acceleration (VLA at the Brookhaven National Laboratory Accelerator Test Facility (ATF), an electron beam with initial energy of 15 Me

Brookhaven National Laboratory

20

Vacuum system for Advanced Test Accelerator  

SciTech Connect

The Advanced Test Accelerator (ATA) is a pulsed linear electron beam accelerator designed to study charged particle beam propagation. ATA is designed to produce a 10,000 amp 50 MeV, 70 ns electron beam. The electron beam acceleration is accomplished in ferrite loaded cells. Each cell is capable of maintaining a 70 ns 250 kV voltage pulse across a 1 inch gap. The electron beam is contained in a 5 inch diameter, 300 foot long tube. Cryopumps turbomolecular pumps, and mechanical pumps are used to maintain a base pressure of 2 x 10/sup -6/ torr in the beam tube. The accelerator will be installed in an underground tunnel. Due to the radiation environment in the tunnel, the controlling and monitoring of the vacuum equipment, pressures and temperatures will be done from the control room through a computer interface. This paper describes the vacuum system design, the type of vacuum pumps specified, the reasons behind the selection of the pumps and the techniques used for computer interfacing.

Denhoy, B.S.

1981-09-03

21

Powerline Conductor Accelerated Testing Facility (PCAT) The Powerline Conductor Accelerated Testing facility (PCAT) at Oak Ridge National  

E-print Network

Accelerated Testing facility (PCAT) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee environmental conditions. The tests provide both the manufacturer and utilities with conductor performance dataPowerline Conductor Accelerated Testing Facility (PCAT) Overview: The Powerline Conductor

22

Laboratory Test of Newton's Second Law for Small Accelerations  

Microsoft Academic Search

We have tested the proportionality of force and acceleration in Newton's second law, F=ma, in the limit of small forces and accelerations. Our tests reach well below the acceleration scales relevant to understanding several current astrophysical puzzles such as the flatness of galactic rotation curves, the Pioneer anomaly, and the Hubble acceleration. We find good agreement with Newton's second law

Brian Woodahl; Jens Gundlach; Stephan Schlamminger; Chris Spitzer; Ki Choi; Jen Coy; Ephraim Fischbach

2009-01-01

23

Laboratory Test of Newton's Second Law for Small Accelerations  

Microsoft Academic Search

We have tested the proportionality of force and acceleration in Newton's second law, F=ma, in the limit of small forces and accelerations. Our tests reach well below the acceleration scales relevant to understanding several current astrophysical puzzles such as the flatness of galactic rotation curves, the Pioneer anomaly, and the Hubble acceleration. We find good agreement with Newton's second law

Brian Woodahl; S. Schlamminger; Chris Spitzer; B. A. Woodahl; Jennifer Coy; Ephraim Fischbach

2007-01-01

24

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

25

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

26

An Accelerated Method for Soldering Testing  

SciTech Connect

An accelerated method for testing die soldering has been developed. High intensity ultrasonic vibrations have been applied to simulate the die casting conditions such as high pressure and high molten metal velocity on the pin. The soldering tendency of steels and coated pins has been examined. The results suggest that in the low carbon steel/Al system, the onset of soldering is 60 times faster with ultrasonic vibration than that without ultrasonic vibration. In the H13/A380 system, the onset of soldering reaction is accelerated to between 30-60 times. Coatings significantly reduce the soldering tendency. For purposes of this study, several commercial coatings from Balzers demonstrated the potential for increasing the service life of core pins between 15 and 180 times.

Han, Qingyou [ORNL; Xu, Hanbing [University of Tennessee, Knoxville (UTK); Ried, Paul [Ried, Engineering; Olson, Paul [Balzers, Inc.

2007-01-01

27

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

28

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

29

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

30

Laboratory Test of Newton's Second Law for Small Accelerations  

SciTech Connect

We have tested the proportionality of force and acceleration in Newton's second law, F=ma, in the limit of small forces and accelerations. Our tests reach well below the acceleration scales relevant to understanding several current astrophysical puzzles such as the flatness of galactic rotation curves, the Pioneer anomaly, and the Hubble acceleration. We find good agreement with Newton's second law at accelerations as small as 5x10{sup -14} m/s{sup 2}.

Gundlach, J. H.; Schlamminger, S.; Spitzer, C. D.; Choi, K.-Y.; Woodahl, B. A.; Coy, J. J.; Fischbach, E. [Center for Experimental Nuclear Physics and Astrophysics, University of Washington, Seattle, Washington 98195 (United States); Physics Department, Indiana University-Purdue University, Indianapolis, Indiana 46202 (United States); Earth and Space Science Department, Saint Joseph's College, Rensselaer, Indiana 47978 (United States); Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States)

2007-04-13

31

Laboratory test of Newton's second law for small accelerations.  

PubMed

We have tested the proportionality of force and acceleration in Newton's second law, F=ma, in the limit of small forces and accelerations. Our tests reach well below the acceleration scales relevant to understanding several current astrophysical puzzles such as the flatness of galactic rotation curves, the Pioneer anomaly, and the Hubble acceleration. We find good agreement with Newton's second law at accelerations as small as 5 x 10(-14) m/s(2). PMID:17501332

Gundlach, J H; Schlamminger, S; Spitzer, C D; Choi, K-Y; Woodahl, B A; Coy, J J; Fischbach, E

2007-04-13

32

The advanced test accelerator (ATA) injector  

SciTech Connect

The ATA injector, developed from experience gained from the Experimental Test Accelerator (ETA) linac, has recently been completed. The injector consists of ten 0.25 MV cells that are used to develop 2.5 MV across a single diode gap. The 10 kA beam is extracted from a 500 cm/sup 2/ plasma cathode at average rates of up to 5 Hz and burst rates to 1 kHz. Pulsed power from 20 water filled blumleins is divided and introduced symmetrically through four ports on each cell. All major insulators are fabricated from filled epoxy castings. With these improvements, the ATA injector is smaller than the ETA injector; has a faster pulse response; has lower voltage stress on insulators and higher ultimate performance. Injector characterization tests began in October, 1982. These tests include beam current, energy, and emittance measurements.

Jackson, C.H.; Bubp, D.G.; Fessenden, T.J.; Hester, R.E.; Neil, V.K.; Paul, A.C.; Prono, D.S.

1983-08-01

33

Degradation mechanisms and accelerated aging test design  

SciTech Connect

The fundamental mechanisms underlying the chemical degradation of polymers can change as a function of environmental stress level. When this occurs, it greatly complicates any attempt to use accelerated tests for predicting long-term material degradation behaviors. Understanding how degradation mechanisms can change at different stress levels facilitates both the design and the interpretation of aging tests. Oxidative degradation is a predominant mechanism for many polymers exposed to a variety of different environments in the presence of air, and there are two mechanistic considerations which are widely applicable to material oxidation. One involves a physical process, oxygen diffusion, as a rate-limiting step. This mechanism can predominate at high stress levels. The second is a chemical process, the time-dependent decomposition of peroxide species. This leads to chain branching and can become a rate-controlling factor at lower stress levels involving time-scales applicable to use environments. The authors describe methods for identifying the operation of these mechanisms and illustrate the dramatic influence they can have on the degradation behaviors of a number of polymer types. Several commonly used approaches to accelerated aging tests are discussed in light of the behaviors which result from changes in degradation mechanisms. 9 references, 4 figures.

Clough, R L; Gillen, K T

1985-01-01

34

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

35

Using Accelerated Testing to Predict Module Reliability  

SciTech Connect

Long-term reliability is critical to the cost effectiveness and commercial success of photovoltaic (PV) products. Today most PV modules are warranted for 25 years, but there is no accepted test protocol to validate a 25-year lifetime. The qualification tests do an excellent job of identifying design, materials, and process flaws that are likely to lead to premature failure (infant mortality), but they are not designed to test for wear-out mechanisms that limit lifetime. This paper presents a method for evaluating the ability of a new PV module technology to survive long-term exposure to specific stresses. The authors propose the use of baseline technologies with proven long-term field performance as controls in the accelerated stress tests. The performance of new-technology modules can then be evaluated versus that of proven-technology modules. If the new-technology demonstrates equivalent or superior performance to the proven one, there is a high likelihood that they will survive versus the tested stress in the real world.

Wohlgemuth, J. H.; Kurtz, S.

2011-01-01

36

DNA Bubble Life Time in Denaturation  

E-print Network

We have investigated the denaturation bubble life time for a homogeneous as well as for a heterogeneous DNA within a Poland-Scheraga model. It is shown that at criticality the bubble life time for a homogeneous DNA is finite provided that the loop entropic exponent c>2 and has a scaling dependence on DNA length for c<2. Heterogeneity in the thermodynamical limit makes the bubble life time infinite for any entropic exponent.

Zh. S. Gevorkian; Chin-Kun Hu

2008-10-04

37

Small-scale accelerated pavement testing  

SciTech Connect

This paper presents the results of a study conducted to explore the use of small-scale models of accelerated pavement testing (APT) devices to evaluate the performance of pavements in conjunction with full-scale tests. The motivation for the study was the availability of a model mobile load simulator (MMLS), which had been built originally to illustrate the operation of the full-scale mobile load simulator (MLS) under design at the time. The scaling requirements will be different depending on whether dynamic (inertia), viscous, or gravity effects are important. One must thus decide which one of these effects controls the behavior to try to reproduce it exactly. In the preliminary tests conducted with the MMLS, emphasis had been placed in reproducing accurately the viscoelastic behavior of the asphalt layer. The possibility of obtaining valid results, even if similitude is not maintained in relation to inertia forces, is explored in this paper. The effects of load frequency or velocity and the effects of layer thicknesses are studied. The total thickness of the model pavement, which must be finite, and its effects on displacements and strains are also considered. It is concluded that even when full similitude is not satisfied it is possible to obtain valid results that can be extrapolated to predict prototype performance if one were interested primarily in the behavior of the asphalt layer. Preliminary analyses should be conducted, however, to guide on the selection of the model dimensions.

Kim, S.M. [Korea Highway Corp., Kyunggi (Korea, Republic of). Highway Research Inst.; Hugo, F. [Univ. of Stellenbosch (South Africa). Inst. for Transport Technology; Roesset, J.M. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering

1998-03-01

38

Applicability of the Accelerated Switching Test Method - A Comprehensive Survey  

Microsoft Academic Search

The enhanced degradation exhibited at low dose rates by many bipolar-technology components is a major reliability issue for spacecraft electronics. As an accelerated ELDRS test method an approach has been suggested that makes use of sequenced high dose rate and low dose rate exposures - the so called accelerated switching test method. In this paper we describe the results of

M. Wind; P. Beck; J. Boch; L. Dusseau; M. Latocha; M. Poizat; A. Zadeh

2011-01-01

39

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

40

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

41

Testing General Relativity With Laser Accelerated Electron Beams  

E-print Network

Electron accelerations of the order of $10^{21} g$ obtained by laser fields open up the possibility of experimentally testing one of the cornerstones of general relativity, the weak equivalence principle, which states that the local effects of a gravitational field are indistinguishable from those sensed by a properly accelerated observer in flat space-time. We illustrate how this can be done by solving the Einstein equations in vacuum and integrating the geodesic equations of motion for a uniformly accelerated particle.

L. Á. Gergely; T. Harko

2012-07-16

42

Accelerated corrosion test for aluminum-zinc alloy coatings  

SciTech Connect

An electrochemically monitored etching method has been developed to enable accelerated service life testing of aluminum/zinc alloy coatings with a dendritic microstructure. The method involved pre-exposure of materials to the etching solution to remove the most active phases from the coatings. This process simulated the early phases of atmospheric corrosion. The method significantly shortened the time required for an atmospheric exposure test. Historical performance data and data collected using the accelerated test method agreed.

Simpson, T.C. (Bethlehem Steel Corp., Bethlehem, PA (United States). Homer Research Labs.)

1993-07-01

43

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

44

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

45

Test of Newton's second law at small accelerations  

Microsoft Academic Search

We present the results of a test of Newton's second law for small accelerations. It is found that within experimental errors F=ma holds down to the lowest accelerations measurable with our apparatus, ~3×10-9 cm\\/s2.

Alex Abramovici; Zeev Vager

1986-01-01

46

46 CFR 160.072-5 - Accelerated weathering test.  

Code of Federal Regulations, 2010 CFR

...APPROVAL LIFESAVING EQUIPMENT Distress Signals for Boats, Orange Flag § 160.072-5 Accelerated weathering test. ...tearing, (3) The flag does not retain its bright red/orange color, (4) The disc and square images no longer meet...

2010-10-01

47

A general Bayes weibull inference model for accelerated life testing  

E-print Network

for accelerated life testing. The failure times at a constant stress level are assumed to belong to a Weibull's, it is often too time consuming and too costly to test these items in their use (or nominal) environmentÃ? has become a standard procedure [1] to test these items under more severe environments than

van Dorp, Johan René

48

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

49

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

50

ACCELERATED CORROSION TESTING OF GALVANIC COUPLES  

Microsoft Academic Search

New materials and structural designs are required for advanced aircraft functionalities. Long standing standardized corrosion test methods (e.g. ASTM B117) are regularly called out in procurement documents to qualify these new materials. However, it is becoming increasingly evident that these test methods can be misleading resulting in approval of material systems that have very poor in service performance and\\/or the

James F. Dante; Josh Averett; Fritz Friedersdorf; Christy Vestal

51

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

52

Electrical performance characteristics of the SSC Accelerator System String Test  

SciTech Connect

The intent of the Accelerator System String Test (ASST) is to obtain data for model verification and information on the magnitudes of pressures and voltages encountered in an accelerator environment. The ASST milestone run was achieved during July and August, 1992 and consisted of demonstrating the accelerator components could be configured together as a system operating at full current. Following the milestone run, the string was warmed to counteract some design flaws that impeded the operational range. The string was again cooled to cryogenic temperatures in October, and a comprehensive power testing program was conducted through the end of January, 1993. This paper describes how the collider arc components operate in an accelerator environment during quenches induced by firing both strip heaters and spot heaters. Evaluation of the data illustrates how variations in the design parameters on magnets used in a string environment can impact system performance.

Robinson, W.; Burgett, W.; Gannon, J.; Kraushaar, P.; Mcinturff, A.; Nehring, R.; Saladin, V.; Savord, T.; Sorrensen, G.; Smellie, R.; Tool, G.; Voy, D.

1993-05-01

53

Beam dynamics in the Advanced Test Accelerator (ATA)  

SciTech Connect

We will review the performance of the Advanced Test Accelerator, a 50 MeV, 10 KA induction linac. The discussion will cover the operation of the plasma cathode electron source, beam transport throughout the accelerator, and transverse instabilities. Particular emphasis will be placed on the beam breakup instability and on the methods used to minimize it. These include a program of design changes that lead to an order of magnitude reduction in the Q's of the accelerator cavity modes and optimization of the transport tune.

Caporaso, G.J.; Barletta, W.A.; Birx, D.L.; Briggs, R.J.; Chong, Y.P.; Cole, A.G.; Fessenden, T.J.; Hester, R.E.; Lauer, E.J.; Neil, V.K.

1983-09-28

54

Power-conditioning system for the Advanced Test Accelerator  

Microsoft Academic Search

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 capable of generating electron beam pulses at a 1 kHz rate in a 10 pulse burst, 5 pps average, with a pulse width

M. A. Newton; M. E. Smith; D. L. Birx; D. R. Branum; E. G. Cook; R. L. Copp; F. D. Lee; L. L. Reginato; D. Rogers; G. C. Speckert

1982-01-01

55

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

56

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

57

The BNL Accelerator Test Facility and experimental program  

SciTech Connect

The Accelerator Test Facility (ATF) at BNL is a users` facility for experiments in Accelerator and Beam Physics. The ATF provides high brightness electron beams and high-power laser pulses synchronized to the electron beam, suitable for studies of new methods of high-gradient acceleration and state-of-the-art Free-Electron Lasers. The electrons are produced by a laser photocathode rf gun and accelerated to 50 MeV by two traveling wave accelerator sections. The lasers include a 10 mJ, 10 ps ND:YAG laser and a 500 mJ, 10 to 100 ps C0{sub 2} laser. A number of users from National Laboratories, universities and industry take part in experiments at the ATF. The experimental program includes various laser acceleration schemes, Free-Electron Laser experiments and a program on the development of high-brightness electron beams. The ATF`s experimental program commenced in early 1991 at an energy of about 4 MeV. The full program, with 50 MeV and the high-power laser will begin operation this year.

Ben-Zvi, I. [Brookhaven National Lab., Upton, NY (United States)]|[State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics

1992-09-01

58

The BNL Accelerator Test Facility and experimental program  

SciTech Connect

The Accelerator Test Facility (ATF) at BNL is a users' facility for experiments in Accelerator and Beam Physics. The ATF provides high brightness electron beams and high-power laser pulses synchronized to the electron beam, suitable for studies of new methods of high-gradient acceleration and state-of-the-art Free-Electron Lasers. The electrons are produced by a laser photocathode rf gun and accelerated to 50 MeV by two traveling wave accelerator sections. The lasers include a 10 mJ, 10 ps ND:YAG laser and a 500 mJ, 10 to 100 ps C0{sub 2} laser. A number of users from National Laboratories, universities and industry take part in experiments at the ATF. The experimental program includes various laser acceleration schemes, Free-Electron Laser experiments and a program on the development of high-brightness electron beams. The ATF's experimental program commenced in early 1991 at an energy of about 4 MeV. The full program, with 50 MeV and the high-power laser will begin operation this year.

Ben-Zvi, I. (Brookhaven National Lab., Upton, NY (United States) State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics)

1992-01-01

59

Accelerated hygrothermal cyclical tests for carbon\\/epoxy laminates  

Microsoft Academic Search

The paper deals with the design of reasonable accelerated test conditions to assess polymer matrix composite durability when it is subjected to supersonic flight-cycles. The study is closely linked to novel application of carbon fibre polymer matrix composites in supersonic aircraft primary structures, leading to substantial weight saving and stiffness improvement. A supersonic flight can result in surface temperatures close

J. Jedidi; F. Jacquemin; A. Vautrin

2006-01-01

60

Initial tests of the magnetic spectrometer at the TANDAR accelerator  

Microsoft Academic Search

A new magnetic spectrometer has started operating at the 20 UD tandem accelerator of the TANDAR laboratory. A large acceptance angle and the ability to handle a broad range of energies and masses are its main characteristics. The associated detection system consists of a multiwire vertical drift chamber, an ionization chamber and a plastic scintillator. The complete device was tested

E. Achterberg; A. J Pacheco; M di Tada; J. O Fernández Niello; R. Liberman; G. V. Martí; M. Ramírez; J. E Testoni; K. Koide

1995-01-01

61

On the inverse power laws for accelerated random fatigue testing  

Microsoft Academic Search

This paper addresses the usage of inverse power laws in accelerated fatigue testing under wide-band Gaussian random loading. The aim is not at predicting an absolute value of fatigue life but assessing the fatigue damage relative accumulation. The widely accepted inverse power scaling laws in fatigue damage assessment is discussed, reviewing the engineering standards and pointing out their inherent limitations.

G. Allegri; X. Zhang

2008-01-01

62

On the inverse power laws for accelerated random fatigue testing  

Microsoft Academic Search

This paper addresses the usage of inverse power laws in accelerated fatigue testing under wide-band Gaussian random loading. The aim is not at predicting an ab- solute value of fatigue life but assessing the fatigue damage relative accumulation. The widely accepted inverse power scaling laws in fatigue damage assessment is discussed, reviewing the engineering standards and pointing out their inherent

G. Allegri; X. Zhang

2009-01-01

63

Reliability estimation of aeronautic component by accelerated tests  

Microsoft Academic Search

This article presents a reliability assessment of aeronautic electronic board using the accelerated test approach. The mission profile used is one defined in FIDES for electronic equipment in aircraft. The reliability function is defined taking into account the different phases of product life (Ground, Taxiing, Flying, Dormant). FIDES describes the environment (thermal and humidity, thermal cycling, mechanical, …) for each

S. Charruau; F. Guerin; J. Hernández Dominguez; J. Berthon

2006-01-01

64

Accelerated Destructive Degradation Tests Robust to Distribution Misspecification  

E-print Network

National Cheng Kung University, Tainan, Taiwan, ROC Bei-Ying Huang Cathay Life Insurance Company, Taipei, Taiwan, ROC William Q. Meeker Iowa State University, Ames, IOWA, USA Abstract Accelerated repeated-measures degradation tests (ARMDTs) take measurements of degra- dation or performance on a sample of units over time

65

Optimum simple step-stress accelerated life tests with censoring  

Microsoft Academic Search

The authors present the optimum simple time-step and failure-step stress accelerated life tests for the case where a prespecified censoring time is involved. An exponential life distribution with a mean that is a log-linear function of stress, and a cumulative exposure model are assumed. The authors obtain the optimum test plans to minimize the asymptotic variance of the maximum-likelihood estimator

D. S. Bai; M. S. Kim; S. H. Lee

1989-01-01

66

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

67

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)

1994-12-31

68

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

69

Test particle acceleration in torsional spine magnetic reconnection  

NASA Astrophysics Data System (ADS)

Three-dimensional (3D) magnetic reconnection is taking place commonly in astrophysical and space plasmas, especially in solar flares which are rich sources of highly energetic particles. One of the proposed mechanisms for steady-state 3D magnetic reconnection is "torsional spine reconnection". By using the magnetic and electric fields for "torsional spine reconnection", we numerically investigate the features of test particle acceleration with input parameters for the solar corona. We show that efficient acceleration of a relativistic proton is possible near the null point where it can gain up to 100 MeV of kinetic energy within a few milliseconds. However, varying the injection position results in different scenarios for proton acceleration. A proton is most efficiently accelerated when it is injected at the point where the magnetic field lines change their curvature in the fan plane. Moreover, a proton injected far away from the null point cannot be accelerated and, even in some cases, it is trapped in the magnetic field. In addition, adopting either spatially uniform or non-uniform localized plasma resistivity does not much influence the features of trajectory.

Hosseinpour, M.

2014-10-01

70

Preloading To Accelerate Slow-Crack-Growth Testing  

NASA Technical Reports Server (NTRS)

An accelerated-testing methodology has been developed for measuring the slow-crack-growth (SCG) behavior of brittle materials. Like the prior methodology, the accelerated-testing methodology involves dynamic fatigue ( constant stress-rate) testing, in which a load or a displacement is applied to a specimen at a constant rate. SCG parameters or life prediction parameters needed for designing components made of the same material as that of the specimen are calculated from the relationship between (1) the strength of the material as measured in the test and (2) the applied stress rate used in the test. Despite its simplicity and convenience, dynamic fatigue testing as practiced heretofore has one major drawback: it is extremely time-consuming, especially at low stress rates. The present accelerated methodology reduces the time needed to test a specimen at a given rate of applied load, stress, or displacement. Instead of starting the test from zero applied load or displacement as in the prior methodology, one preloads the specimen and increases the applied load at the specified rate (see Figure 1). One might expect the preload to alter the results of the test and indeed it does, but fortunately, it is possible to account for the effect of the preload in interpreting the results. The accounting is done by calculating the normalized strength (defined as the strength in the presence of preload the strength in the absence of preload) as a function of (1) the preloading factor (defined as the preload stress the strength in the absence of preload) and (2) a SCG parameter, denoted n, that is used in a power-law crack-speed formulation. Figure 2 presents numerical results from this theoretical calculation.

Gyekenyesi, John P.; Choi, Sung R.; Pawlik, Ralph J.

2004-01-01

71

Accelerated aging test results for aerospace wire insulation constructions  

NASA Astrophysics Data System (ADS)

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.

1995-11-01

72

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

73

GTA (ground test accelerator) Phase 1: Baseline design report  

SciTech Connect

The national Neutral Particle Beam (NPB) program has two objectives: to provide the necessary basis for a discriminator/weapon decision by 1992, and to develop the technology in stages that lead ultimately to a neutral particle beam weapon. The ground test accelerator (GTA) is the test bed that permits the advancement of the state-of-the-art under experimental conditions in an integrated automated system mode. An intermediate goal of the GTA program is to support the Integrated Space Experiments, while the ultimate goal is to support the 1992 decision. The GTA system and each of its major subsystems are described, and project schedules and resource requirements are provided. (LEW)

Not Available

1986-08-01

74

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

75

Beam loading and cavity compensation for the ground test accelerator  

SciTech Connect

The Ground Test Accelerator (GTA) will be a heavily beam-loaded H/sup minus/ linac with tight tolerances on accelerating field parameters. The methods used in modeling the effects of beam loading in this machine are described. The response of the cavity to both beam and radio-frequency (RF) drive stimulus is derived, including the effects of cavity detuning. This derivation is not restricted to a small-signal approximation. An analytical method for synthesizing a predistortion network that decouples the amplitude and phase responses of the cavity is also outlined. Simulation of performance, including beam loading, is achieved through use of a control system analysis software package. A straightforward method is presented for extrapolating this work to model large coupled structures with closely spaced parasitic modes. Results to date have enabled the RF control system designs for GTA to be optimized and have given insight into their operation. 6 refs., 10 figs.

Jachim, S.P.; Natter, E.F.

1989-01-01

76

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

77

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

78

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

79

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

SciTech Connect

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

2009-09-09

80

Instrumentation for accelerated life tests of concentrator solar cells.  

PubMed

Concentrator photovoltaic is an emergent technology that may be a good economical and efficient alternative for the generation of electricity at a competitive cost. However, the reliability of these new solar cells and systems is still an open issue due to the high-irradiation level they are subjected to as well as the electrical and thermal stresses that they are expected to endure. To evaluate the reliability in a short period of time, accelerated aging tests are essential. Thermal aging tests for concentrator photovoltaic solar cells and systems under illumination are not available because no technical solution to the problem of reaching the working concentration inside a climatic chamber has been available. This work presents an automatic instrumentation system that overcomes the aforementioned limitation. Working conditions have been simulated by forward biasing the solar cells to the current they would handle at the working concentration (in this case, 700 and 1050 times the irradiance at one standard sun). The instrumentation system has been deployed for more than 10?000 h in a thermal aging test for III-V concentrator solar cells, in which the generated power evolution at different temperatures has been monitored. As a result of this test, the acceleration factor has been calculated, thus allowing for the degradation evolution at any temperature in addition to normal working conditions to be obtained. PMID:21361622

Núñez, N; Vázquez, M; González, J R; Jiménez, F J; Bautista, J

2011-02-01

81

High power testing of 30 GHz accelerating structures at the Clic Test Facility (CTF II)  

E-print Network

During the year 2000, experiments using the CLIC Test Facility [1] (CTF II) focused on high-power testing of 30 GHz CLIC prototype accelerating structures [2] (CAS) and on investigating the processes involved in RF breakdown. For this purpose, a 30 GHz high-power test stand equipped with diagnostics for breakdown studies has been developed. The experimental set-up, diagnostics and performance of the one meter long power extraction structure used to feed the accelerating structures with 30 GHz power will be described. A single-feed coupler CAS assembled by AEG, a planar structure produced by the University of Berlin, and a double-feed coupler CAS made at CERN, were tested in CTF. The accelerating and surface gradient limits found for these structures at different RF pulse lengths, and ideas about the processes involved in electrical breakdown, are summarised and discussed.

Braun, Hans Heinrich; Groening, L; Wilson, Ian H; Wuensch, Walter; Zhou, F

2001-01-01

82

Simulations and Vacuum Tests of a CLIC Accelerating Structure  

E-print Network

The Compact LInear Collider, under study, is based on room temperature high gradient structures. The vacuum specificities of these cavities are low conductance, large surface areas and a non-baked system. The main issue is to reach UHV conditions (typically 10-7 Pa) in a system where the residual vacuum is driven by water outgassing. A finite element model based on an analogy thermal/vacuum has been built to estimate the vacuum profile in an accelerating structure. Vacuum tests are carried out in a dedicated set-up, the vacuum performances of different configurations are presented and compared with the predictions.

Garion, C

2011-01-01

83

Metal and elastomer seal tests for accelerator applications  

SciTech Connect

The vacuum system of the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory has more than a thousand metal vacuum seals. Also, numerous elastomer seals are used throughout the AGS to seal large beam component chambers. An accelerator upgrade program is being implemented to reduce the AGS operating pressure by x100 and improve the reliability of the vacuum system. This paper describes work in progress on metal and elastomer vacuum seals to help meet those two objectives. Tests are reported on the sealing properties of a variety of metal seals used on different sealing surfaces. Results are also given on reversible sorption properties of certain elastomers. 16 refs., 6 figs., 4 tabs.

Welch, K.M.; McIntyre, G.T.; Tuozzolo, J.E.; Skelton, R.; Pate, D.J.; Gill, S.M.

1989-01-01

84

Using Accelerated Testing To Predict Module Reliability: Preprint  

SciTech Connect

Long-term reliability is critical to the cost effectiveness and commercial success of photovoltaic (PV) products. Today most PV modules are warranted for 25 years, but there is no accepted test protocol to validate a 25-year lifetime. The qualification tests do an excellent job of identifying design, materials, and process flaws that are likely to lead to premature failure (infant mortality), but they are not designed to test for wear-out mechanisms that limit lifetime. This paper presents a method for evaluating the ability of a new PV module technology to survive long-term exposure to specific stresses. The authors propose the use of baseline technologies with proven long-term field performance as controls in the accelerated stress tests. The performance of new-technology modules can then be evaluated versus that of proven-technology modules. If the new-technology demonstrates equivalent or superior performance to the proven one, there is a high likelihood that they will survive versus the tested stress in the real world.

Wohlgemuth, J. H.; Kurtz, S.

2011-07-01

85

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

86

Cosmic acceleration without dark energy: background tests and thermodynamic analysis  

NASA Astrophysics Data System (ADS)

A cosmic scenario with gravitationally induced particle creation is proposed. In this model the Universe evolves from an early to a late time de Sitter era, with the recent accelerating phase driven only by the negative creation pressure associated with the cold dark matter component. The model can be interpreted as an attempt to reduce the so-called cosmic sector (dark matter plus dark energy) and relate the two cosmic accelerating phases (early and late time de Sitter expansions). A detailed thermodynamic analysis including possible quantum corrections is also carried out. For a very wide range of the free parameters, it is found that the model presents the expected behavior of an ordinary macroscopic system in the sense that it approaches thermodynamic equilibrium in the long run (i.e., as it nears the second de Sitter phase). Moreover, an upper bound is found for the Gibbons–Hawking temperature of the primordial de Sitter phase. Finally, when confronted with the recent observational data, the current `quasi'-de Sitter era, as predicted by the model, is seen to pass very comfortably the cosmic background tests.

Lima, J. A. S.; Graef, L. L.; Pavón, D.; Basilakos, Spyros

2014-10-01

87

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

88

Battery management systems (BMS) for increasing battery life time  

Microsoft Academic Search

The life time of the battery depends of many different parameters. One parameter set is the internal battery parameters which are influenced by the battery manufacturers, and the second set is the external battery parameters which are influenced by the battery users. The external parameter can have an enormous influence on the life time. By use of a battery management

A. Jossen; V. Spath; H. Doring; J. Garche

1999-01-01

89

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

90

The Status of Turkish Accelerator Center Test Facility  

SciTech Connect

Recently, conceptual design of Turkic Accelerator Center (TAC) proposal was completed. Main goal of this proposal is a charm factory that consists of a linac-ring type electron-positron collider. In addition, synchrotron radiation from the positron ring and free electron laser from the electron linac are proposed. The project related with this proposal has been accepted by Turkish government. It is planned that the Technical Design Report of TAC will have been written in next three years. In this period, an infrared oscillator free electron laser (IR FEL) will be constructed as a test facility for TAC. 20 and 50 MeV electron energies will be used to obtain infra red free electron laser. The main parameters of the electron linac, the optical cavities and the free electron laser were determined. The possible use of obtained laser beam in basic and applied research areas such as biotechnology, nanotechnology, semiconductors and photo chemistry were stated.

Yavas, Oe. [University of Ankara, Fac. of Engineering, Dept. of Engineering Physics, Tandogan 06100, Ankara (Turkey)

2007-04-23

91

The Status of Turkish Accelerator Center Test Facility  

NASA Astrophysics Data System (ADS)

Recently, conceptual design of Turkic Accelerator Center (TAC) proposal was completed. Main goal of this proposal is a charm factory that consists of a linac-ring type electron-positron collider. In addition, synchrotron radiation from the positron ring and free electron laser from the electron linac are proposed. The project related with this proposal has been accepted by Turkish government. It is planned that the Technical Design Report of TAC will have been written in next three years. In this period, an infrared oscillator free electron laser (IR FEL) will be constructed as a test facility for TAC. 20 and 50 MeV electron energies will be used to obtain infra red free electron laser. The main parameters of the electron linac, the optical cavities and the free electron laser were determined. The possible use of obtained laser beam in basic and applied research areas such as biotechnology, nanotechnology, semiconductors and photo chemistry were stated.

Yava?, Ö.

2007-04-01

92

The use of accelerated radiation testing for avionics  

NASA Astrophysics Data System (ADS)

In recent years, the use of unmanned aerial vehicles (UAVs) for military and national security applications has been increasing. One possible use of these vehicles is as remote sensing platforms, where the UAV carries several sensors to provide real-time information about biological, chemical or radiological agents that might have been released into the environment. One such UAV, the Global Hawk, has a payload space that can carry nearly one ton of sensing equipment, which makes these platforms significantly larger than many satellites. Given the size of the potential payload and the heightened radiation environment at high altitudes, these systems could be affected by the radiation-induced failure mechanisms from the naturally occurring terrestrial environment. In this paper, we will explore the use of accelerated radiation testing to prepare UAV payloads for deployment.

Quinn, Heather

2013-04-01

93

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

94

RESULTS FROM THE ARGONNE WAKEFIELD ACCELERATOR TEST FACILITY  

Microsoft Academic Search

We report on the wakefield experimental results using the Argonne Wakefield Accelerator (AWA). Since the commissioning of the AWA, we have conducted numerous wakefield related experiments: plasma wakefield acceleration, dielectric collinear wakefield and step-up transformer two-beam acceleration experiments. In this paper, we summarize the experimental results and discuss the ongoing AWA upgrade to further these experimental results. Future plans for

W. Gai; M. Conde; R. Konencny; W. Liu

95

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

96

Design of accelerated corrosion tests for electronic components in automotive applications  

Microsoft Academic Search

Two new accelerated laboratory corrosion tests for electronic components in automotive applications have been developed, based on the use of metallic copper as a meter for corrosivity. The accelerated tests are designed so that they reproduce the same kind of corrosion effects as observed with exposure of copper in real vehicle environments. The test cycle that best simulates the corrosion

Peter Eriksson; Bo Carlsson; I. O. Wallinder

2001-01-01

97

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

98

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

99

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

100

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 rate 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

101

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

102

How soccer players head the ball: A test of optic acceleration cancellation theory with virtual reality  

E-print Network

1 How soccer players head the ball: A test of optic acceleration cancellation theory with virtual; visuomotor; movement; action #12;3 How soccer players head the ball: A test of optic acceleration measured the movements of soccer players heading a football in a fully immersive virtual reality

Glennerster, Andrew

103

Using Accelerated Tests to Predict Service Life in Highly-Variable Environments  

E-print Network

Chapter xx Using Accelerated Tests to Predict Service Life in Highly-Variable Environments William while im- proving productivity, reliability, and quality. This requires improved accelerated test (AT) methods that can usefully predict service life. For example, automobile manufacturers would like

104

Using Accelerated Tests to Predict Service Life in HighlyVariable Environments  

E-print Network

Chapter xx Using Accelerated Tests to Predict Service Life in Highly­Variable Environments William in record time while im­ proving productivity, reliability, and quality. This requires improved accelerated test (AT) methods that can usefully predict service life. For example, automobile manufacturers would

105

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

106

Meson Life Time in the Anisotropic Quark-Gluon Plasma  

E-print Network

In the hot (an)isotropic plasma the meson life time $\\tau$ is defined as a time scale after which the meson dissociates. According to the gauge/gravity duality, this time can be identified with the inverse of the imaginary part of the frequency of the quasinormal modes, $\\omega_I$, in the (an)isotropic black hole background. In the high temperature limit, we numerically show that at fixed temperature(entropy density) the life time of the mesons decreases(increases) as the anisotropy parameter raises. For general case, at fixed temperature we introduce a polynomial function for $\\omega_I$ and observe that the meson life time decreases. Moreover, we realize that $(s/T^3)^6$, where $s$ and $T$ are entropy density and temperature of the plasma respectively, can be expressed as a function of anisotropy parameter over temperature. Interestingly, this function is a Pad\\'{e} approximant.

Mohammad Ali-Akbari; Davood Allahbakhshi

2014-04-23

107

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

108

Laboratory test of Newton's law of gravity for small accelerations  

NASA Astrophysics Data System (ADS)

The rotation curves of spiral galaxies suggest that either a considerable fraction of the galactic mass must be dark matter, or that one of Newton's laws needs revision at accelerations less than 1× {{10}-10} m {{s}-2}. We have endeavored to search for evidence of the latter in a terrestrial laboratory. A sensitive torsion balance was employed to measure small accelerations due to gravity. No deviations from the predictions of Newton's law were found down to 1 × 10?12 m s?2.

Little, S.; Little, M.

2014-10-01

109

Highly accelerated electromigration lifetime test (HALT) of copper  

Microsoft Academic Search

The reliability of copper interconnects is an important aspect in ULSI technology. The test time of the standard electromigration test is rising with improving interconnect systems. At moderate current densities, lifetime test could last more than 500 h. In this paper, lifetime tests on via-line test structures in a copper dual-damascene technology at extremely high temperatures have been investigated. This

Oliver Aubel; Wolfgang Hasse; Martina Hommel

2003-01-01

110

Applications of the ram accelerator to hypervelocity aerothermodynamic testing  

NASA Technical Reports Server (NTRS)

A ram accelerator used as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerodynamics research is presented. It is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled down a stationary tube filled with a tailored combustible gas mixture. Ram accelerator operation has been demonstrated at 39 mm and 90 mm bores, supporting the proposition that this launcher concept can be scaled up to very large bore diameters of the order of 30-60 cm. It is concluded that high quality data obtained from the tube wall and projectile during the aceleration process itself are very useful for understanding aerothermodynamics of hypersonic flow in general, and for providing important CFD validation benchmarks.

Bruckner, A. P.; Knowlen, C.; Hertzberg, A.

1992-01-01

111

Application of accelerated tool life tests to machining of titanium  

SciTech Connect

The tool life of several commercial C-2 grade cutting tools used in machining titanium was estimated using two experimental techniques, the quick facing test and the multipass facing test. Comparisons among the tools tested were made statistically by analyzing differences in regression equations derived from test data. Tool life end points were determined by operator judgement, tool force analysis, and tool wear measurement. Of the ten tools tested, nine had the same life under the test conditions.

Stagner, R.T.

1980-09-01

112

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; Bruce, R.W.; /Unlisted

2007-04-13

113

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

114

Acceleration test of TIT-IHQ linac for heavy ion irradiation  

NASA Astrophysics Data System (ADS)

We have developed an interdigital-H quadrupole (IHQ) linac for industrial applications. This linac was designed to accelerate particles with charge to mass ratio greater than 1/16 from 21.8 up to 145 keV/u. The particles are focused by an electric quadrupole field exited by fingertips on the drift tubes. This IHQ linac was installed at Tokyo Institute of Technology in 1997 and some tests such as low power tuning and vacuum tests were done. Then, proton acceleration tests ware performed in 1998, and the proton beam was successfully accelerated up to the designed energy. As a result of this experiment, the effective shunt impedance was determined to be 210 M?/m, the required RF power consumption was 93 W and the beam transmission rate was about 9%. In this paper, the results of the high power acceleration test with H + ion are described.

Takashi, Ito; Noriyosu, Hayashizaki; Shinjiro, Matsui; Kimikazu, Sasa; Schubert, H.; Osvath, E.; Toshiyuki, Hattori

2000-03-01

115

Analysis of Transmitted Optical Spectrum Enabling Accelerated Testing of CPV Designs: Preprint  

SciTech Connect

Reliability of CPV systems' materials is not well known; methods for accelerated UV testing have not been developed. UV and IR spectra transmitted through representative optical systems are evaluated.

Miller, D. C.; Kempe, M. D.; Kennedy, C. E.; Kurtz, S. R.

2009-07-01

116

Measuring test mass acceleration noise in space-based gravitational wave astronomy  

E-print Network

The basic constituent of interferometric gravitational wave detectors -- the test mass to test mass interferometric link -- behaves as a differential dynamometer measuring effective differential forces, comprising an integrated measure of gravity curvature, inertial effects, as well as non-gravitational spurious forces. This last contribution is going to be characterised by the LISA Pathfinder mission, a technology precursor of future space-borne detectors like eLISA. Changing the perspective from displacement to acceleration can benefit the data analysis of LISA Pathfinder and future detectors. The response in differential acceleration to gravitational waves is derived for a space-based detector's interferometric link. The acceleration formalism can also be integrated into time delay interferometry by building up the unequal-arm Michelson differential acceleration combination. The differential acceleration is nominally insensitive to the system free evolution dominating the slow displacement dynamics of low-...

Congedo, Giuseppe

2014-01-01

117

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

118

COMPARISON OF ACCELERATED CORROSION TESTS TO CORROSION PERFORMANCE IN NATURAL ATMOSPHERIC ENVIRONMENTS  

Microsoft Academic Search

There is interest in the comparison of accelerated corrosion tests to corrosion performance in natural atmospheric environments. Currently, there are some concerns that accelerated corrosion testing may not accurately predict performance in natural atmospheric environments. This provided motivation to compare the corrosion behavior of Al 1060, Al 6061-T6, Al 7075-T6, Al 2024-T3, pure copper, pure magnesium, coated pure magnesium, 1008

R. Sugamoto; G. A. Hawthorn

119

Comparison of experimental tests and theory for a rectangular two-channel dielectric wakefield accelerator structure  

NASA Astrophysics Data System (ADS)

Experimental results are reported for test beam acceleration and deflection in a two-channel, cm-scale, rectangular dielectric-lined wakefield accelerator structure energized by a 14-MeV drive beam. The dominant waveguide mode of the structure is at ˜30GHz, and the structure is configured to exhibit a high transformer ratio (˜12?1). Accelerated bunches in the narrow secondary channel of the structure are continuously energized via Cherenkov radiation that is emitted by a drive bunch moving in the wider primary channel. Observed energy gains and losses, transverse deflections, and changes in the test bunch charge distribution compare favorably with predictions of theory.

Shchelkunov, S. V.; Marshall, T. C.; Sotnikov, G.; Hirshfield, J. L.; Gai, Wei; Conde, M.; Power, J.; Mihalcea, D.; Yusof, Z.

2012-03-01

120

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

121

Strategy for Planning Accelerated Life Tests with Small Sample Sizes Haiming Ma and W. Q. Meeker  

E-print Network

at ,Ls Ms and Hs , respectively standardized stress level ( ) ( )UHU ssss --= / t, failure time1 Strategy for Planning Accelerated Life Tests with Small Sample Sizes Haiming Ma and W. Q. Meeker life tests has been based on large-sample approximations to evaluate test plan properties

122

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

123

Accelerated thermal and mechanical testing of CSP assemblies  

NASA Technical Reports Server (NTRS)

Chip Scale Packages (CSP) are now widely used for many electronic applications including portable and telecommunication products. A test vehicle (TV-1) with eleven package types and pitches was built and tested by the JPL MicrotypeBGA Consortium during 1997 to 1999. Lessons learned by the team were published as a guidelines document for industry use. The finer pitch CSP packages which recently became available were indluded in the next test vehicle of the JPL CSP Consortium.

Ghaffarian, R.

2000-01-01

124

Design and test of a superconducting magnet in a linear accelerator for an Accelerator Driven Subcritical System  

NASA Astrophysics Data System (ADS)

A batch superconducting solenoid magnet for the ADS proton linear accelerator has been designed, fabricated, and tested in a vertical dewar in Sept. 2013. A total of ten superconducting magnets will be installed into two separate cryomodules. Each cryomodule contains six superconducting spoke RF cavities for beam acceleration and five solenoid magnets for beam focusing. The multifunction superconducting magnet contains a solenoid for beam focusing and two correctors for orbit correction. The design current for the solenoid magnet is 182 A. A quench performance test shows that the operating current of the solenoid magnet can reach above 300 A after natural quenching on three occasions during current ramping (260 A, 268 A, 308 A). The integrated field strength and leakage field at the nearby superconducting spoke cavities all meet the design requirements. The vertical test checked the reliability of the test dewar and the quench detection system. This paper presents the physical and mechanical design of the batch magnets, the quench detection technique, field measurements, and a discussion of the residual field resulting from persistent current effects.

Peng, Quanling; Xu, Fengyu; Wang, Ting; Yang, Xiangchen; Chen, Anbin; Wei, Xiaotao; Gao, Yao; Hou, Zhenhua; Wang, Bing; Chen, Yuan; Chen, Haoshu

2014-11-01

125

Accelerated vacuum testing of long life ball bearings and sliprings  

NASA Technical Reports Server (NTRS)

Extensive analytical studies and testing have been conducted on bearings and sliprings in vacuum at temperatures from 30 to 130 F. Thirty-six bearings lubricated with two types of oil were tested in vacuum of less than 10 to the minus 8th power torr at speeds from 55 to 180 rpm. Temperatures, load, speed, and oil viscosity were varied to evaluate the effects on life and wear. All bearings performed successfully during a 7-month test, and the potential merits of the two oils were compared. Over 25 different, dry-lubricated brush/slipring material combinations have been tested, with variations of brush and ring design and surface speed. Test results indicate the probability of 10 years or more of slipring and brush lifetime with properly designed brushes for 1-in.-diameter ring rotating at 60 rpm.

Meeks, C. R.; Christy, R. I.; Cunningham, A. C.

1971-01-01

126

Cryogenic characteristics of the SSC Accelerator Systems String Test (ASST)  

SciTech Connect

A series of static and dynamic tests of the ASST were conducted from July 1992 to the present. These tests included heat leak measurements, as well as, temperature and pressure profiles obtained during quench testing of the string. An accurate assessment of heat leak measurements of collider components requires a stable thermal environment with the minimization of end effects. The string test provides the ideal static environment necessary to conduct these measurements. This report summarizes the results of the heat leak measurements conducted on the cold mass, 20K, and 80K shields of the dipoles used in the ASST assembly. We also report on the rapidly changing temperatures and pressures recorded during the string quench tests.

Burgett, W.; Franks, D.; Kraushaar, P.; Levin, M.; McAshan, M.; McInturff, A.; Pletzer, R.; Revell, D.; Robinson, W.; Saladin, V.; Shuy, G.; Smellie, R.; Weisend, J.G. II.

1993-04-01

127

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

128

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

129

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. PMID:22686344

Shen, Jie; Burgess, Diane J.

2012-01-01

130

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

131

Test particle simulation of direct laser acceleration in a density-modulated plasma waveguide  

SciTech Connect

Direct laser acceleration (DLA) of electrons by the use of the intense axial electric field of an ultrafast radially polarized laser pulse is a promising technique for future compact accelerators. Density-modulated plasma waveguides can be implemented for guiding the propagation of the laser pulse to extend the acceleration distance and for the quasi-phase-matching between the accelerated electrons and the laser pulse. A test particle model is developed to study the optimal axial density modulation structure of plasma waveguides for laser pulses to efficiently accelerate co-propagating electrons. A simple analytical approach is also presented, which can be used to estimate the energy gain in DLA. The analytical model is validated by the test particle simulation. The effect of injection phase and acceleration of electrons injected at various radial positions are studied. The results indicate that a positively chirped density modulation of the waveguide structure is required to accelerate electron with low initial energies, and can be effectively optimized. A wider tolerance on the injection phase and radial distance from the waveguide axis exists for electrons injected with a higher initial energy.

Lin, M.-W.; Jovanovic, I. [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2012-11-15

132

The static spacetime relative acceleration for the general free fall and its possible experimental test  

E-print Network

Mishra has recently established, using a generic static metric, the relative local proper-time 3-acceleration of a test-particle in one-dimensional free fall relative to a static reference frame in any static spacetime. In this paper, on the grounds of gravitoelectromagnetism we establish, in a covariant spacetime form, the relative 4-acceleration for the general free fall, indicating its canonical representation with its 3-space cinematical content. Then we obtain the relation between this representation and the very known expression for the relative free fall acceleration in Fermi coordinates. Taking this into account, it is shown that an experiment with relativistic beams in a circular accelerator, modelled by Fermi coordinates, recently proposed by Moliner et al, can test the here established covariant result and, therefore, can also verify Mishra's formula. This possibility of experimental verification, besides its intrinsic importance, can answer a recent inquire by Vigier, related to his recent proposal of derivation of inertial forces.

F. Bunchaft; S. Carneiro

1998-03-17

133

A Test of Newton's Law of Gravity in the Weak Acceleration Regime  

E-print Network

A pilot experiment suitable to test Newton's law of gravity down to the regime of acceleration typical of galaxies has been carried out in Omega Centauri. Stars in the extreme periphery of this globular cluster are used as test particles immersed in such weak gravitational field. The stellar velocity dispersion is found to remain constant at large radii, rather than decrease monotonically, starting at acceleration a=10e-7 cm/s2. This is comparable to the acceleration at which the effect of dark matter becomes relevant in galaxies. Explanations for this result within Newtonian dynamics exist (e.g. cluster evaporation, tidal effects, presence of dark matter) but require fine tuning of the relevant parameters in order to make the dispersion profile flat. An interesting alternative is that this result, together with a similar one for Palomar 13 and the anomalous behavior of spacecrafts outside the solar system, suggests a breakdown of Newton's law in the weak acceleration regime.

Riccardo Scarpa; Gianni Marconi; Roberto Gilmozzi

2002-08-02

134

Design and Factory Test of the E /E- Frascati Linear Accelerator for DAFNE  

SciTech Connect

The electron-positron accelerator for the DAFNE project has been built and is in test at Titan Beta in Dublin, CA. This S-Band RF linac system utilizes four 45 MW sledded klystrons and 16-3 m accelerating structures to achieve the required performance. It delivers a 4 ampere electron beam to the positron converter and accelerates the resulting positrons to 550 MeV. The converter design uses a 4.3T pulsed tapered flux compressor along with a pseudo-adiabatic tapered field to a 5 KG solenoid over the first two positron accelerating sections. Quadrupole focusing is used after 100 MeV. The system performance is given in Table 1. This paper briefly describes the design and development of the various subassemblies in this system and gives the initial factory test data.

Anamkath, H.; Lyons, S.; Nett, D.; Treas, P.; Whitham, K.; Zante, T.; /Titan Beta, Dublin; Miller, R.; /Titan Beta, Dublin /SLAC; Boni, R.; Hsieh, H.; Sannibale, F.; Vescovi, M.; Vignola, G.; /Frascati

2011-11-28

135

Investigation of hypersonic ramjet propulsion cycles using a ram accelerator test facility  

NASA Technical Reports Server (NTRS)

Experimental research on hypersonic propulsion using a ram accelerator test facility is presented. The gasdynamics of the ram accelerator has been studied experimentally in a 38-mm bore facility over the Mach number range of 2.5 to 8.5, using methane- and ethylene-based propellant mixtures. Three different propulsive modes, centered on the Chapman-Jouguet (C-J) detonation speed of the combustible gas, have been experimentally observed. Projectiles have been accelerated smoothly from velocities below to above the C-J speed within a single propellant mixture.

Bruckner, A. P.; Chew, G.; De Turenne, J. A.; Dunmire, B.

1991-01-01

136

Accelerated testing of anodically bonded glass-silicon packages in salt water  

Microsoft Academic Search

This paper reports long-term accelerated test results of glass-silicon packages in aqueous solutions including phosphate buffered saline (PBS) and de-ionized water. An analysis of the dominant failure mode and the long term biocompatibility of the packages is also performed. Using the accelerated data at 85 and 95°C in saline with an Arrhenius model we calculate an activation energy of 1.26

M. R. Dokmeci; J. A. von Arx; K. Najafi

1997-01-01

137

Deformation and Fracture of CFRP under HyperVelocity Impact Test Using Laser-Accelerated Flyer  

Microsoft Academic Search

Using laser-accelerated Al flyers, we examined hyper-velocity impact tests of CFRP (carbon fiber reinforced plastics) laminates as a simulation of orbital debris impact. A short-pulsed intense laser beam can accelerate a small flyer as fast as LEO (low earth orbit) satellite velocity. We succeeded in observing the deformation and fracture processes of the CFRP targets with a high-speed framing camera.

Yoshiaki Yamauchi; Motohiro Nakano; Keizo Kishida; Norimasa Ozaki; Takao Kasai; Yasufumi Sasatani; Hidehiko Amaki; Kazuo A. Tanaka

2002-01-01

138

Electro-Optic Sampling at the TESLA Test Accelerator: Experimental Setup and First Results  

Microsoft Academic Search

Abstract A mode-locked titanium-sapphire laser with 15 fs pulse width is used to determine the temporal profile of the ultrashort electron bunches in the linear TESLA Test accelerator. The experimental setup is described and first results are presented on the synchronization of the Ti:Sa laser with the radio frequency of the superconducting accelerator and on the coincidence measurements between the

M. Brunken; H. Genz; P. Gottlicher; C. Hessler; M. Huning; H. Loos; A. Richter; H. Schlarb; P. Schmuser; S. Simrock; D. Suetterlin; M. Tonutti; D. Turke; Physikalisches Insitut Iiia; Rwth Aachen

139

An experimental test of the theory of the stimulated dielectric wakefield accelerator  

Microsoft Academic Search

We have installed a dielectric-lined wakefield accelerator at the Accelerator Test Facility (ATF), Brookhaven National Laboratory. The first experiment, reported here, uses a single 0.2 nC, 10 psec bunch of 40 MeV electrons to excite the multi-mode TM0m wakefields which trail the bunch. The device is configured as a cylindrical waveguide containing an annular alumina liner; the electrons move along

J.-M. Fangy; T. C. Marshall; J. L. Hirshfield; M. A. LaPointe; T.-B. Zhang; X. J. Wang

1999-01-01

140

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

141

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

142

Accelerated Wear Tests on Common Floor-covering Materials.  

E-print Network

materials indicated there are variations in the changes of appearance and wear in these materials. Solid sheet vinyls and rubber tiles showed significantly less wear than asphalt tiles, vinyl- asbestos tiles, linoleums and cork. Asphalt tiles showed... in home installations. Six common floor covering materials-solid .sheet vinyls, rubber tiles, vinyl-asbestos tiles, J linoleums, corks and asphalt tiles-were used to construct 63 test specimens 2 x 2 feet in size. 1 T'ariations in specimens were...

Stewart, B. R.; Kunze, O. R.; Hobgood, Price.

1958-01-01

143

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

144

An Evaluation of High Frequency Acceleration Test at XLPE Cable’s Insulator  

NASA Astrophysics Data System (ADS)

We investigated whether a high frequency acceleration method has validity at the degradation of XLPE in case of no influence of water for realizing a lifetime test at near the operating electric field. The tests was carried out at 50Hz, 1000Hz, and 3000Hz frequency using Recessed specimen and the specimen under Needle-plane electrode system, time-to-breakdown was measured. A clear property of frequency acceleration was checked in both results of tests, and the validity of the frequency acceleration technique was shown. And we realize that frequency acceleration factor is lower than the frequency ratio at both tests of specimens. We think the reason is that the amount of accumulation of the space charge per cycle at a defect or a tree tip at high frequency is less than the accumulation at 50Hz. Moreover, tree growth time effects at the time to breakdown of Needle-plane system specimen, but it effects a little at Recessed specimen, so there is difference of acceleration rate between both specimens. The lifetime exponent of V-t characteristic, n, increases at a 3000Hz examination, so it is suggested that n has a frequency dependence.

Iwasaki, Kimihiro; Nakade, Masahiko; Tanaka, Atsushi; Tanimoto, Mihoko; Okashita, Minoru; Ito, Kazumi

145

Concept, implementation and commissioning of the automation system for the accelerator module test facility AMTF  

NASA Astrophysics Data System (ADS)

The European XFEL project launched on June 5, 2007 will require about 103 accelerator modules as a main part of the XFEL linear accelerator. All superconducting components constituting the accelerator module like cavities and magnets have to be tested before the assembly. For the tests of the individual cavities and the complete modules an XFEL Accelerator Module Test Facility (AMTF) has been erected at DESY. The process control system EPICS (Experimental Physics and Industrial Control System) is used to control and operate the cryogenic plant and all its subcomponents. A complementary component of EPICS is the Open Source software suit CSS (Control System Studio). CSS is an integrated engineering, maintenance and operating tool for EPICS. CSS enables local and remote operating and monitoring of the complete system and thus represents the human machine interface. More than 250 PROFIBUS nodes work at the accelerator module test facility. DESY installed an extensive diagnostic and condition monitoring system. With these diagnostic tools it is possible to examine the correct installation and configuration of all PROFIBUS nodes in real time. The condition monitoring system based on FDT/DTM technology shows the state of the PROFIBUS devices at a glance. This information can be used for preventive maintenance which is mandatory for continuous operation of the AMTF facility. The poster will describe all steps form engineering to implementation and commissioning.

Böckmann, Torsten A.; Korth, Olaf; Clausen, Matthias; Schoeneburg, Bernd

2014-01-01

146

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

147

Vertical and horizontal test results of 3.9-GHz accelerating cavities at FNAL  

SciTech Connect

The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve the beam performance of the VUV FEL, FLASH. In the frame of a collaborative agreement, Fermilab will provide DESY with a cryomodule containing a string of four cavities. Seven 9-cell Nb cavities were tested and six of them did reach accelerating gradient up to 24 MV/m almost twice more than design value of 14 MV/m. Two of these cavities are with new HOM couplers with improved design. In this paper we present all results of the vertical and horizontal tests.

Khabiboulline, T.; Edwards, H.; Foley, M.; Harms, E.; Hocker, James Andrew; Mitchell, D.; Rowe, A.; Solyak, N.; /Fermilab

2008-06-01

148

Production and test results of SC 3.9-GHz accelerating cavity at Fermilab  

SciTech Connect

The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve beam performances for TTF-FEL facility. In the frame of collaboration Fermilab will provide DESY with a cryomodule containing a string of four cavities. In addition, a second cryomodule with one cavity will be fabricated for installation in the Fermilab photo-injector, which will be upgraded for the ILC accelerator test facility. In this paper we discuss the status of the cavity and coupler production and the first result of cavity tests. It is hoped that this project will be completed during the first half of 2007 and the cryomodule delivered to DESY in this time span.

Khabiboulline, Timergali; Cooper, Charlie; Edwards, Helen; Foley, Mike; Gonin, Ivan; Mitchell, Donald; Olis, D.; Rowe, Allan; Salman, Tariq; Solyak, Nikolay; /Fermilab

2006-08-01

149

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

150

PREDICTING CHRONIC LETHALITY OF CHEMICALS TO FISHES FROM ACUTE TOXICITY TEST DATA: THEORY OF ACCELERATED LIFE TESTING  

EPA Science Inventory

A method for modeling aquatic toxicity date based on the theory of accelerated life testing and a procedure for maximum likelihood fitting the proposed model is presented. he procedure is computerized as software, which can predict chronic lethality of chemicals using data from a...

151

Possibility of a modification of life time of radioactive elements by magnetic monopoles  

E-print Network

A simple explanation of the fact that light magnetic monopoles have not been observed at accelerator experiments is given. It is based on a possibility of violation of C invariance in the electromagnetic interactions. Because of the difficulty of monopole registration, two interconnected problems arise: to formulate a theory describing monopole production (it should include a new force beyond the Standard Model of electroweak interaction), and to point the way to monopole observation. We consider a possibility, closely related to some experiments, of a modification of life time of radioactive elements by magnetic monopoles. The first part of the article is devoted to purely electromagnetic impact of monopoles, caused by the vertex M --> M + gamma. The second part, more speculative one, is based on experimental evidences in favour of the existence of some axial vector currents, responsible for a new force, which can stimulate, or suppress, decays of radioactive elements.

B. F. Kostenko; M. Z. Yuriev

2007-09-07

152

Effects of accelerated testing on porcine bioprosthetic heart valve fiber architecture.  

PubMed

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 16 Hz, and small-angle light scattering (SALS) was used to quantify the gross fiber structure of the cusps. The degree of gross fiber alignment remained essentially constant from 0 to 500 million cycles over the entire cusp. Increasing fiber orientation randomness, indicative of local damage, was observed only in the vicinity of the nodulus of Arantii after 50 million cycles. The SALS data from the damaged regions suggested shearing between fiber layers, which may be part of the failure process and accelerates valve failure. Histological analysis revealed a relatively intact gross fiber structure with the collagen fiber crimp remaining, although delamination and de-registration of the crimp was also observed. Accelerated tested PBHVs also demonstrated a pronounced 'sagging', which began at the earliest cycle number tested (1.4 million cycles) and whose rate decreased logarithmically with cycle number. Results of this study suggest that PBHV cusps can alter their shape without any visually apparent material yielding or fiber failure under continual cyclic loading. Further, while most of the 4 mmHg pressure fixed PBHV's gross fiber architecture remains unchanged after 500 million cycles of accelerated testing, localized accumulated fiber damage can occur on a sub-visual structural level as early as 50 million cycles. PMID:9692801

Sacks, M S; Smith, D B

1998-06-01

153

Design and beam test of a high intensity continuous wave RFQ accelerator  

NASA Astrophysics Data System (ADS)

A four-vane continuous wave (CW) RFQ has been designed for the injector II LINAC of China ADS project. To acquire the experience of a CW RFQ on design, tuning, conditioning, running, etc., a 1-m-long RFQ accelerator prototype has been built. Working at 162.5 MHz, the RFQ prototype accelerates protons of 10 mA from 20 keV to 560 keV in one meter length with a low inter-vane voltage of 65 kV and a safe Kilpatric factor of 1.3. Conditioning and beam test of the accelerator prototype have been completed, and it shows the transmission efficiency can reach 90% with a 10 mA CW proton beam. Design, fabrication and tests of the RFQ prototype will be presented in detail in the paper.

Zhang, Zhouli; Sun, Liepeng; Jia, Huan; He, Yuan; Shi, Aimin; Du, Xiaonan; Wang, Jing; Jin, Xiaofeng; Pan, Gang; Xu, Xianbo; Li, Chenxing; Shi, Longbo; Lu, Liang; Zhang, Zimin; Wu, Junxia; Wang, Haoning; Zhu, Tieming; Wang, Xianwu; Guo, Yuhui; Liu, Yong; Zhao, Hongwei

2014-11-01

154

Experimental Testing of a Micron-Scale Laser-Powered Accelerator  

SciTech Connect

An experimental program to develop, perfect, and demonstrate a micron-scale dielectric-based slab-symmetric accelerator is underway at UCLA. The effort includes parallel development of a particle source to be integrated with the accelerator, forming a monolithic radiation source. We present results from first-round cold tests of the structure resonance on a simplified metal-walled device, containing >100 structure periods in an area of 100x20 {mu}m. The resonance frequency and strength can be observed via reflection and transmission measurements on the drive laser. Initial measurements may be consistent with simulation. We also report on the status of the electron source development and on work toward an acceleration test in an all-dielectric structure.

Travish, G.; Arab, E.; Lacroix, U. H.; Rosenzweig, J. B.; Vartanian, N. [UCLA Department of Physics and Astronomy, Los Angeles, CA 90095 (United States); Yoder, R. B. [Manhattanville College, Department of Physics, Purchase, NY 10577 (United States)

2009-01-22

155

Design and test results of the Low Energy Demonstration Accelerator (LEDA) RF systems  

SciTech Connect

The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos will serve as the prototype for the low energy section of the Accelerator Production of Tritium (APT) accelerator. The APT accelerator requires over 200 RF systems each with a continuous wave output power of 1 MW. The reliability and availability of these RF systems is critical to the successful operation of the APT plant and prototypes of these systems are being developed and demonstrated on LEDA. The RF system design for LEDA includes three, 1.2 MW, 350 MHz continuous wave (CW), RF systems driving a radio frequency quadrupole (RFQ) and one, 1.0 MW, CW, RF system driving a coupled-cavity drift tube linac (CCDTL). This paper presents the design and test results for these RF systems including the klystrons, cathode power supply, circulators, RF vacuum windows, accelerator field and resonance control system, and RF transmission components. The three RF systems driving the RFQ use the accelerating structure as a power combiner, and this places some unique requirements on the RF system. These requirements and corresponding operational implications will be discussed.

Rees, D.; Bradley, J. III; Cummings, K.; Lynch, M.; Regan, A.; Rohlev, T.; Roybal, W.; Wang, Y.M.

1998-12-01

156

Accelerated life tests for prognostic and health management of MEMS devices  

E-print Network

. These tasks can be performed within Prognostics and Health Management (PHM) framework. This paper presents are then combined and used to monitor the microgripper, assess its health state and estimate its Remaining UsefulAccelerated life tests for prognostic and health management of MEMS devices Haithem Skima, Kamal

Boyer, Edmond

157

A Tool for Evaluating Time-Varying-Stress Accelerated Life Test Plans with  

E-print Network

1 A Tool for Evaluating Time-Varying-Stress Accelerated Life Test Plans with Log-stress s = log(VH/V ) Standardized stress = (s - sU ) / (sH - sU ) k Ramp rate Time to reach the highest that a unit will fail by time at use and the highest stress levels, respectively zp p quantile of a standard

158

Linking Accelerating Laboratory Test with Outdoor Performance Results for a Model Epoxy Coating System  

E-print Network

Linking Accelerating Laboratory Test with Outdoor Performance Results for a Model Epoxy Coating System Xiaohong Gu1 , Brian Dickens1 , Debbie Stanley1 , Walter E. Byrd1 , Tinh Nguyen1 , Iliana Vaca Iowa State University, Ames, IA 50011 1 #12;ABSTRACT Laboratory and outdoor exposure results have been

159

Failure Modes, Effects and Criticality Analysis and Accelerated Life testing of  

E-print Network

Failure Modes, Effects and Criticality Analysis and Accelerated Life testing of LEDs for Medical Application for LEDs 2. Failure Modes and Effects Criticality Analysis (FMECA) - Failure Modes & Mechanisms not to scale #12;Failure Modes & Effects Criticality Analysis Severity Classification for Medical Diagnostic

Rubloff, Gary W.

160

DEVELOPMENT OF A HIGH BRIGHTNESS ELECTRON GUN FOR THE ACCELERATOR TEST FACILITY AT BROOKHAVEN NATIONAL LABORATORY*  

E-print Network

954 DEVELOPMENT OF A HIGH BRIGHTNESS ELECTRON GUN FOR THE ACCELERATOR TEST FACILITY AT BROOKHAVEN, New York 11973 and K. McDonald Princeton [Jniversity Abstract An electron gun utilizing a radio). Here we report on the de;$n of the electron gun which will provide r.f. bunches of up to 10 electrons

McDonald, Kirk

161

Accelerated Life Testing Model for a Generalized Birnbaum-Saunders Distribution  

E-print Network

of the distribution, is the failure threshold level, is the standard deviation of the failure time dataAccelerated Life Testing Model for a Generalized Birnbaum-Saunders Distribution Yao Cheng and E. A@gmail.com, elsayed@rci.rutgers.edu Abstract--Fatigue failures caused by cyclic stresses are commonly

Boyer, Edmond

162

Compilation of radiation damage test data materials used around high-energy accelerators  

E-print Network

For pt.II see CERN report 79-08 (1979). This handbook gives the results of radiation damage tests on various engineering materials and components intended for installation in radiation areas of the CERN high-energy particle accelerators. It complements two previous volumes covering organic cable-insulating materials and thermoplastic and thermosetting resins.

Beynel, Paul; Schönbacher, Helmut

1982-01-01

163

SUPER-FMIT, an accelerator based neutron source for fusion components irradiation testing  

NASA Astrophysics Data System (ADS)

The SUPER-FMIT facility is proposed as an advanced accelerator based neutron source for high flux irradiation testing of large-sized fusion reactor components. The facility would require only small extensions to existing accelerator and target technology originally developed for the Fusion Materials Irradiation Test (FMIT) facility. There, neutrons would be produced by a 0.1 A beam of 35 MeV deuterons incident upon a liquid lithium target. The volume available for high flux (> 10 14n/ cm2s) testing in SUPER-FMIT would be 14 1, about a factor of 30 larger than in the FMIT facility. This is because the effective beam current of 35 MeV deuterons on target can be increased by a factor of ten to 1.0 A or more. Such a large increase can be accomplished by acceleration of multiple beams of molecular deuterium ions (D +2) to 70 MeV in a common accelerator structure. The availability of multiple beams and large total current allows great variety in the testing that can be done. For example, fluxes greater than 10 16 n/cm 2 s, multiple simultaneous experiments and great flexibility in tailoring of spatial distributions of flux and spectra can be achieved.

Burke, R. J.; Holmes, J. J.; Johnson, D. L.; Mann, F. M.; Miles, R. R.

1985-05-01

164

Testing the Newton second law in the regime of small accelerations  

Microsoft Academic Search

It has been pointed out that the Newtonian second law can be tested in the very small acceleration regime by using the combined movement of the Earth and Sun around the Galactic center of mass. It has been shown that there are only two brief intervals during the year in which the experiment can be completed, which correspond to only

V. A. de Lorenci; M. Faúndez-Abans; J. P. Pereira

2009-01-01

165

TERA high gradient test program of RF cavities for medical linear accelerators  

NASA Astrophysics Data System (ADS)

The scientific community and the medical industries are putting a considerable effort into the design of compact, reliable and cheap accelerators for hadrontherapy. Up to now only circular accelerators are used to deliver beams with energies suitable for the treatment of deep seated tumors. The TERA Foundation has proposed and designed a hadrontherapy facility based on the cyclinac concept: a high gradient linear accelerator placed downstream of a cyclotron used as an injector. The overall length of the linac, and therefore its final cost, is almost inversely proportional to the average accelerating gradient achieved in the linac. TERA, in collaboration with the CLIC RF group, has started a high gradient test program. The main goal is to study the high gradient behavior of prototype cavities and to determine the appropriate linac operating frequency considering important issues such as machine reliability and availability of distributed power sources. A preliminary test of a 3 GHz cavity has been carried out at the beginning of 2010, giving encouraging results. Further investigations are planned before the end of 2011. A set of 5.7 GHz cavities is under production and will be tested in a near future. The construction and test of a multi-cell structure is also foreseen.

Degiovanni, A.; Amaldi, U.; Bonomi, R.; Garlasché, M.; Garonna, A.; Verdú-Andrés, S.; Wegner, R.

2011-11-01

166

A GLM approach to step-stress accelerated life testing with interval censoring  

Microsoft Academic Search

In this paper, we present a statistical inference procedure for the step-stress accelerated life testing (SSALT) model with Weibull failure time distribution and interval censoring via the formulation of generalized linear model (GLM). The likelihood function of an interval censored SSALT is in general too complicated to obtain analytical results. However, by transforming the failure time to an exponential distribution

Jinsuk Lee; Rong Pan

167

Status and specifications of a Project X front-end accelerator test facility at Fermilab  

SciTech Connect

This paper describes the construction and operational status of an accelerator test facility for Project X. The purpose of this facility is for Project X component development activities that benefit from beam tests and any development activities that require 325 MHz or 650 MHz RF power. It presently includes an H- beam line, a 325 MHz superconducting cavity test facility, a 325 MHz (pulsed) RF power source, and a 650 MHz (CW) RF power source. The paper also discusses some specific Project X components that will be tested in the facility. Fermilab's future involves new facilities to advance the intensity frontier. In the early 2000's, the vision was a pulsed, superconducting, 8 GeV linac capable of injecting directly into the Fermilab Main Injector. Prototyping the front-end of such a machine started in 2005 under a program named the High Intensity Neutrino Source (HINS). While the HINS test facility was being constructed, the concept of a new, more versatile accelerator for the intensity frontier, now called Project X, was forming. This accelerator comprises a 3 GeV CW superconducting linac with an associated experimental program, followed by a pulsed 8 GeV superconducting linac to feed the Main Injector synchrotron. The CW Project X design is now the model for Fermilab's future intensity frontier program. Although CW operation is incompatible with the original HINS front-end design, the installation remains useful for development and testing many Project X components.

Steimel, J.; Webber, R.; Madrak, R.; Wildman, D.; Pasquinelli, R.; Evans-Peoples, E.; /Fermilab

2011-03-01

168

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

169

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

SciTech Connect

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. [CERN, 1211 Geneva 23 (Switzerland)

1999-05-07

170

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

171

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

172

Measuring test mass acceleration noise in space-based gravitational wave astronomy  

E-print Network

The basic constituent of interferometric gravitational wave detectors -- the test mass to test mass interferometric link -- behaves as a differential dynamometer measuring effective differential forces, comprising an integrated measure of gravity curvature, inertial effects, as well as non-gravitational spurious forces. This last contribution is going to be characterised by the LISA Pathfinder mission, a technology precursor of future space-borne detectors like eLISA. Changing the perspective from displacement to acceleration can benefit the data analysis of LISA Pathfinder and future detectors. The response in differential acceleration to gravitational waves is derived for a space-based detector's interferometric link. The acceleration formalism can also be integrated into time delay interferometry by building up the unequal-arm Michelson differential acceleration combination. The differential acceleration is nominally insensitive to the system free evolution dominating the slow displacement dynamics of low-frequency detectors. Working with acceleration also provides an effective way to subtract measured signals acting as systematics, including the actuation forces. Because of the strong similarity with the equations of motion, the optimal subtraction of systematic signals, known within some amplitude and time shift, with the focus on measuring the noise provides an effective way to solve the problem and marginalise over nuisance parameters. The $\\mathcal{F}$-statistic, in widespread use throughout the gravitation waves community, is included in the method and suitably generalised to marginalise over linear parameters and noise at the same time. The method is applied to LPF simulator data and, thanks to its generality, can also be applied to the data reduction and analysis of future gravitational wave detectors.

Giuseppe Congedo

2014-09-29

173

High Gradient Test of a Clamped, Molybdenum Iris, X-Band Accelerator Structure at NLCTA  

SciTech Connect

Inspired by the very high gradients (150-195 MV/m) achieved at CERN in 30 GHz accelerator structures made with tungsten and molybdenum irises and operated with short (16 ns) rf pulses [1], an X-band (11.4 GHz) version of this structure design was built at CERN and tested at SLAC. The goals of this experiment were to provide frequency scaling data on high gradient phenomena at similar pulse lengths, and to measure the structure performance at the longer pulse lengths available at SLAC (the CLIC test facility, CTF II, could provide only 16 ns pulses for high power operation and 32 ns pulses for medium power operation). Earlier high gradient tests of 21 GHz to 39 GHz standing-wave, single cells, indicated no significant frequency dependence of the maximum obtainable surface field [2]. The X-band scaling test would check if this was true for travelling-wave, multi-cell structures as well. For the experiment, the CLIC group at CERN built a 30 cell accelerating structure that consisted of copper cells and molybdenum irises that were clamped together. The structure was mounted in a vacuum tank and installed in the Next Linear Collider Test Accelerator (NLCTA) beam line at SLAC where it was operated at high power for more than 700 hours.

Doebert, S.

2004-11-08

174

Commissioning and Acceptance Testing of the existing linear accelerator upgraded to volumetric modulated arc therapy  

PubMed Central

Aim The RapidArc commissioning and Acceptance Testing program will test and ensure accuracy in DMLC position, precise dose-rate control during gantry rotation and accurate control of gantry speed. Background Recently, we have upgraded our linear accelerator capable of performing IMRT which was functional from 2007 with image guided RapidArc facility. The installation of VMAT in the existing linear accelerator is a tedious process which requires many quality assurance procedures before the proper commissioning of the facility and these procedures are discussed in this study. Materials and methods Output of the machine at different dose rates was measured to verify its consistency at different dose rates. Monitor and chamber linearity at different dose rates were checked. DMLC QA comprising of MLC transmission factor measurement and dosimetric leaf gap measurements were performed using 0.13 cm3 and 0.65 cm3 Farmer type ionization chamber, dose 1 dosimeter, and IAEA 30 cm × 30 cm × 30 cm water phantom. Picket fence test, garden fence test, tests to check leaf positioning accuracy due to carriage movement, calibration of the leaves, leaf speed stability effects due to the acceleration and deceleration of leaves, accuracy and calibration of leaves in producing complex fields, effects of interleaf friction, etc. were verified using EDR2 therapy films, Vidar scanner, Omnipro accept software, amorphous silicon based electronic portal imaging device and EPIQA software.1–8 Results All the DMLC related quality assurance tests were performed and evaluated by film dosimetry, portal dosimetry and EPIQA.7 Conclusion Results confirmed that the linear accelerator is capable of performing accurate VMAT. PMID:24416566

Varadharajan, Ekambaram; Ramasubramanian, Velayudham

2013-01-01

175

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

176

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

177

Note: An online testing method for lifetime projection of high power light-emitting diode under accelerated reliability test.  

PubMed

In recent years, due to the fast development of high power light-emitting diode (LED), its lifetime prediction and assessment have become a crucial issue. Although the in situ measurement has been widely used for reliability testing in laser diode community, it has not been applied commonly in LED community. In this paper, an online testing method for LED life projection under accelerated reliability test was proposed and the prototype was built. The optical parametric data were collected. The systematic error and the measuring uncertainty were calculated to be within 0.2% and within 2%, respectively. With this online testing method, experimental data can be acquired continuously and sufficient amount of data can be gathered. Thus, the projection fitting accuracy can be improved (r(2) = 0.954) and testing duration can be shortened. PMID:25273797

Chen, Qi; Chen, Quan; Luo, Xiaobing

2014-09-01

178

Note: An online testing method for lifetime projection of high power light-emitting diode under accelerated reliability test  

NASA Astrophysics Data System (ADS)

In recent years, due to the fast development of high power light-emitting diode (LED), its lifetime prediction and assessment have become a crucial issue. Although the in situ measurement has been widely used for reliability testing in laser diode community, it has not been applied commonly in LED community. In this paper, an online testing method for LED life projection under accelerated reliability test was proposed and the prototype was built. The optical parametric data were collected. The systematic error and the measuring uncertainty were calculated to be within 0.2% and within 2%, respectively. With this online testing method, experimental data can be acquired continuously and sufficient amount of data can be gathered. Thus, the projection fitting accuracy can be improved (r2 = 0.954) and testing duration can be shortened.

Chen, Qi; Chen, Quan; Luo, Xiaobing

2014-09-01

179

Study on constant-step stress accelerated life tests in white organic light-emitting diodes.  

PubMed

In order to obtain reliability information for a white organic light-emitting diode (OLED), two constant and one step stress tests were conducted with its working current increased. The Weibull function was applied to describe the OLED life distribution, and the maximum likelihood estimation (MLE) and its iterative flow chart were used to calculate shape and scale parameters. Furthermore, the accelerated life equation was determined using the least squares method, a Kolmogorov-Smirnov test was performed to assess if the white OLED life follows a Weibull distribution, and self-developed software was used to predict the average and the median lifetimes of the OLED. The numerical results indicate that white OLED life conforms to a Weibull distribution, and that the accelerated life equation completely satisfies the inverse power law. The estimated life of a white OLED may provide significant guidelines for its manufacturers and customers. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24677412

Zhang, J P; Liu, C; Chen, X; Cheng, G L; Zhou, A X

2014-11-01

180

Characterization of wear debris generated in accelerated rolling-element fatigue tests  

NASA Technical Reports Server (NTRS)

A ferrographic analysis was used to determine the types and quantities of wear debris generated during accelerated rolling contact fatigue tests. The five-ball rolling contact fatigue tester was used. Ball specimens were made of a corrosion resistant, high-temperature bearing steel. The lubricant was a superrefined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.52 10 to the 9th power Pa and a shaft speed of 10,000 rpm. Four types of wear debris were observed: (1) normal rubbing wear particles, (2) fatigue microspall particles, (3) spheres, and (4) friction polymer deposits. The characterization of wear debris as a function of time was of limited use in predicting fatigue failures in these accelerated tests.

Jones, W. R., Jr.; Parker, R. J.

1978-01-01

181

Electron Cloud Effects in Cornell Electron Storage Ring Test Accelerator and International Linear Collider Damping Ring  

Microsoft Academic Search

In this paper, the effects of electron cloud are discussed for the ultra low emittance positron beam in Cornell Electron Storage Ring Test Accelerator (Cesr-TA) and the International Linear Collider (ILC) damping ring. We have investigated the electron-cloud instabilities with Cesr-TA which has been operating to experiment for the ILC damping ring with different positron beam energies: 2 and 5

Hyunchang Jin; Moohyun Yoon; Kazuhito Ohmi; John W. Flanagan; Mark A. Palmer

2011-01-01

182

Testing the Newton second law in the regime of small accelerations  

Microsoft Academic Search

It has been pointed out that the Newtonian second law can be tested in the\\u000avery small acceleration regime by using the combined movement of the Earth and\\u000aSun around the Galactic center of mass. It has been shown that there are only\\u000atwo brief intervals during the year in which the experiment can be completed,\\u000awhich correspond to only

V. A. De Lorenci; M. Faundez-Abans; J. P. Pereira

2010-01-01

183

Tests of a niobium split-ring superconducting heavy-ion accelerating structure  

Microsoft Academic Search

A niobium split-ring accelerating structure designed for use in the Argonne superconducting heavy-ion energy booster has been successfully tested. The superconducting resonator has a resonant frequency of 97 MHz and an optimum particle velocity ? = 0.11. Ultimate performance is expected to be limited by peak surface fields, which in this structure are 4.7 Eaelectric and 170 Ea(Gauss) magnetic, where

R. Benaroya; L. Bollinger; A. Jaffey; T. Khoe; M. Olesen; C. Scheibelhut; K. Shepard; W. Wesolowski

1977-01-01

184

Comparison of Accelerated Testing with Modeling to Predict Lifetime of CPV Solder Layers (Presentation)  

SciTech Connect

Concentrating photovoltaic (CPV) cell assemblies can fail due to thermomechanical fatigue in the die-attach layer. In this presentation, we show the latest results from our computational model of thermomechanical fatigue. The model is used to estimate the relative lifetime of cell assemblies exposed to various temperature histories consistent with service and with accelerated testing. We also present early results from thermal cycling experiments designed to help validate the computational model.

Silverman, T. J.; Bosco, N.; Kurtz, S.

2012-03-01

185

Rapid estimation of lives of deficient superpave mixes and laboratory-based accelerated mix testing models  

NASA Astrophysics Data System (ADS)

The engineers from the Kansas Department of Transportation (KDOT) often have to decide whether or not to accept non-conforming Superpave mixtures during construction. The first part of this study focused on estimating lives of deficient Superpave pavements incorporating nonconforming Superpave mixtures. These criteria were based on the Hamburg Wheel-Tracking Device (HWTD) test results and analysis. The second part of this study focused on developing accelerated mix testing models to considerably reduce test duration. To accomplish the first objective, nine fine-graded Superpave mixes of 12.5-mm nominal maximum aggregate size (NMAS) with asphalt grade PG 64-22 from six administrative districts of KDOT were selected. Specimens were prepared at three different target air void levels Ndesign gyrations and four target simulated in-place density levels with the Superpave gyratory compactor. Average number of wheel passes to 20-mm rut depth, creep slope, stripping slope, and stripping inflection point in HWTD tests were recorded and then used in the statistical analysis. Results showed that, in general, higher simulated in-place density up to a certain limit of 91% to 93%, results in a higher number of wheel passes until 20-mm rut depth in HWTD tests. A Superpave mixture with very low air voids Ndesign (2%) level performed very poorly in the HWTD test. HWTD tests were also performed on six 12.5-mm NMAS mixtures with air voids Ndesign of 4% for six projects, simulated in-place density of 93%, two temperature levels and five load levels with binder grades of PG 64-22, PG 64-28, and PG 70-22. Field cores of 150-mm in diameter from three projects in three KDOT districts with 12.5-mm NMAS and asphalt grade of PG 64-22 were also obtained and tested in HWTD for model evaluation. HWTD test results indicated as expected. Statistical analysis was performed and accelerated mix testing models were developed to determine the effect of increased temperature and load on the duration of the HWTD test. Good consistency between predicted and observed test results was obtained when higher temperature and standard load level were used. Test duration of the HWTD can thus be reduced to two hours or less using accelerated mix testing (statistical) models.

Manandhar, Chandra Bahadur

186

Feasibility study of a nonequilibrium MHD accelerator concept for hypersonic propulsion ground testing  

SciTech Connect

A National Aeronautics and Space Administration (NASA) funded research study to evaluate the feasibility of using magnetohydrodynamic (MHD) body force accelerators to produce true air simulation for hypersonic propulsion ground testing is discussed in this paper. Testing over the airbreathing portion of a transatmospheric vehicle (TAV) hypersonic flight regime will require high quality air simulation for actual flight conditions behind a bow shock wave (forebody, pre-inlet region) for flight velocities up to Mach 16 and perhaps beyond. Material limits and chemical dissociation at high temperature limit the simulated flight Mach numbers in conventional facilities to less than Mach 12 for continuous and semi-continuous testing and less than Mach 7 for applications requiring true air chemistry. By adding kinetic energy directly to the flow, MHD accelerators avoid the high temperatures and pressures required in the reservoir region of conventional expansion facilities, allowing MHD to produce true flight conditions in flight regimes impossible with conventional facilities. The present study is intended to resolve some of the critical technical issues related to the operation of MHD at high pressure. Funding has been provided only for the first phase of a three to four year feasibility study that would culminate in the demonstration of MHD acceleration under conditions required to produce true flight conditions behind a bow shock wave to flight Mach numbers of 16 or greater. MHD critical issues and a program plan to resolve these are discussed.

Lee, Ying-Ming; Simmons, G.A.; Nelson, G.L. [MSE Inc., Butte, MT (United States)

1995-12-31

187

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

188

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

189

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

190

Comparison of test particle acceleration in torsional spine and fan reconnection regimes  

NASA Astrophysics Data System (ADS)

Magnetic reconnection is a common phenomenon taking place in astrophysical and space plasmas, especially in solar flares which are rich sources of highly energetic particles. Torsional spine and fan reconnections are important mechanisms proposed for steady-state three-dimensional null-point reconnection. By using the magnetic and electric fields for these regimes, we numerically investigate the features of test particle acceleration in both regimes with input parameters for the solar corona. By comparison, torsional spine reconnection is found to be more efficient than torsional fan reconnection in an acceleration of a proton to a high kinetic energy. A proton can gain as high as 100 MeV of relativistic kinetic energy within only a few milliseconds. Moreover, in torsional spine reconnection, an accelerated particle can escape either along the spine axis or on the fan plane depending on its injection position. However, in torsional fan reconnection, the particle is only allowed to accelerate along the spine axis. In addition, in both regimes, the particle's trajectory and final kinetic energy depend on the injection position but adopting either spatially uniform or non-uniform localized plasma resistivity does not much influence the features of trajectory.

Hosseinpour, M.; Mehdizade, M.; Mohammadi, M. A.

2014-10-01

191

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

192

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

193

WindoWorks: A flexible program for computerized testing of accelerator control system electronic circuit boards  

SciTech Connect

Since most accelerator control system circuit boards reside in a commercial bus architecture, such as CAMAC or VMEbus, a computerized test station is needed for exercising the boards. This test station is needed for the development of newly designed prototypes, for commissioning newly manufactured boards, for diagnosing boards which have failed in service, and for long term testing of boards with intermittent failure problems. WindoWorks was created to address these needs. It is a flexible program which runs on a PC compatible computer and uses a PC to bus crate interface. WindoWorks was designed to give the user a flexible way to test circuit boards. Each test is incapsulated into a window. By bringing up several different windows the user can run several different tests simultaneously. The windows are sizable, and moveable. They have data entry boxes so that the test can be customized to the users preference. The windows can be used in conjunction with each other in order to create supertests. There are several windows which are generic. They can be used to test basic functions on any VME (or CAMAC) board. There are other windows which have been created to test specific boards. New windows for testing specific boards can be easily created by a Pascal programmer using the WindoWorks framework.

Utterback, J.

1993-09-01

194

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

SciTech Connect

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 component as it is brought on-line. The major components 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}{lambda} drift tube linac (DTL-1) module, and the 24-MeV GTA with 10 DTL modules. Results from the DTL-1 beam experiments will be presented.

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

1993-06-01

195

Design of a 3 GHz Accelerator Structure for the CLIC Test Facility (CTF 3) Drive Beam  

E-print Network

For the CLIC two-beam scheme, a high-current, long-pulse drive beam is required for RF power generation. Taking advantage of the 3 GHz klystrons available at the LEP injector once LEP stops, a 180 MeV electron accelerator is being constructed for a nominal beam current of 3.5 A and 1.5 ms pulse length. The high current requires highly effective suppression of dipolar wakes. Two concepts are investigated for the accelerating structure design: the "Tapered Damped Structure" developed for the CLIC main beam, and the "Slotted Iris - Constant Aperture" structure. Both use 4 SiC loads per cell for effective higher-order mode damping. A full-size prototype of the TDS structure has been built and tested successfully at full power. A first prototype of the SICA structure is being built

Carron, G; Luong, M; Millich, Antonio; Rugo, E; Syratchev, I V; Thorndahl, L

2000-01-01

196

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

SciTech Connect

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. [Consorzio RFX, Corso Stati Uniti 4, 35127 Padova (Italy); Department of Engineering and Management, University of Padova, Vicenza (Italy); Agostinetti, P.; Marconato, N.; Marcuzzi, D.; Sartori, E.; Serianni, G.; Sonato, P. [Consorzio RFX, Corso Stati Uniti 4, 35127 Padova (Italy)

2012-02-15

197

Methodology to Improve Design of Accelerated Life Tests in Civil Engineering Projects  

PubMed Central

For reliability testing an Energy Expansion Tree (EET) and a companion Energy Function Model (EFM) are proposed and described in this paper. Different from conventional approaches, the EET provides a more comprehensive and objective way to systematically identify external energy factors affecting reliability. The EFM introduces energy loss into a traditional Function Model to identify internal energy sources affecting reliability. The combination creates a sound way to enumerate the energies to which a system may be exposed during its lifetime. We input these energies into planning an accelerated life test, a Multi Environment Over Stress Test. The test objective is to discover weak links and interactions among the system and the energies to which it is exposed, and design them out. As an example, the methods are applied to the pipe in subsea pipeline. However, they can be widely used in other civil engineering industries as well. The proposed method is compared with current methods. PMID:25111800

Lin, Jing; Yuan, Yongbo; Zhou, Jilai; Gao, Jie

2014-01-01

198

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

199

Kenneth J. Turner and Qian Bing. Protocol Techniques for Testing Radiotherapy Accelerators. In Moshe Vardi and Doron Peled, editors,  

E-print Network

domain. Radiotherapy accelerators are complex, software- controlled, safety-critical systems 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

Turner, Ken

200

NEUTRON MONITOR DATA ON THE 15 JUNE 1991 FLARE: NEUTRONS AS A TEST FOR PROTON ACCELERATION SCENARIO  

E-print Network

NEUTRON MONITOR DATA ON THE 15 JUNE 1991 FLARE: NEUTRONS AS A TEST FOR PROTON ACCELERATION SCENARIO.J.TANSKANEN University of Oulu, SF-90570, Oulu, Finland ABSTRACT. Response of A1ma-Ata neuuon monitor for solar neutrons of proton acceleration during the flare. The analysis of neutron monitor is an evidence in favour

Usoskin, Ilya G.

201

A Proposal for a TESLA Accelerator Module Test Facility W.D.Moeller, B.Petersen, B.Sparr  

E-print Network

1 A Proposal for a TESLA Accelerator Module Test Facility W.D.Moeller, B.Petersen, B.Sparr Deutsches Elektronen Synchrotron TESLA Report No. 2001-08 Abstract The Tera-eV Energy Superconducting Linear Accelerator (TESLA), a 32 km long superconducting linear electron/positron collider of 500 GeV (upgradeable

202

Research of the optical properties of solar-reflective materials subjected to accelerated and nonaccelerated exposure tests. Final report  

SciTech Connect

Research on candidate reflective materials for use in solar thermal power applications is reported. The candidate materials have been subjected to exposure tests conducted previously at the Phoenix, Arizona test site. The samples have been exposed to each of three test conditions - one non-accelerated and two different accelerated tests (nominally 8 suns). Post-exposure optical measurements of spectral reflectance were then conducted for the exposure test samples. Reflectance specularity data for the subject materials are obtained from optical measurements performed by Battelle-PNL. Summarized is an investigation of the accumulated reflectance data for correlations using three of the various materials included in the exposure test sample set. (LEW)

Rausch, R A

1980-10-01

203

Models of f(R) Cosmic Acceleration that Evade Solar-System Tests  

E-print Network

We study a class of metric-variation f(R) models that accelerates the expansion without a cosmological constant and satisfies both cosmological and solar-system tests in the small-field limit of the parameter space. Solar-system tests alone place only weak bounds on these models, since the additional scalar degree of freedom is locked to the high-curvature general-relativistic prediction across more than 25 orders of magnitude in density, out through the solar corona. This agreement requires that the galactic halo be of sufficient extent to maintain the galaxy at high curvature in the presence of the low-curvature cosmological background. If the galactic halo and local environment in f(R) models do not have substantially deeper potentials than expected in LCDM, then cosmological field amplitudes |f_R| > 10^{-6} will cause the galactic interior to evolve to low curvature during the acceleration epoch. Viability of large-deviation models therefore rests on the structure and evolution of the galactic halo, requiring cosmological simulations of f(R) models, and not directly on solar-system tests. Even small deviations that conservatively satisfy both galactic and solar-system constraints can still be tested by future, percent-level measurements of the linear power spectrum, while they remain undetectable to cosmological-distance measures. Although we illustrate these effects in a specific class of models, the requirements on f(R) are phrased in a nearly model-independent manner.

Wayne Hu; Ignacy Sawicki

2007-05-08

204

European Particle Accelerator Conference -Rome, Italy -June 7-12, 1988 DEVELOPMENT OFA HIGH BRIGHTNESS ELECTRON GUN FOR THE ACCELERATOR TEST FACILITY AT  

E-print Network

BRIGHTNESS ELECTRON GUN FOR THE ACCELERATOR TEST FACILITY AT BROOKHAVEN NATIONAL LABORATORY* K. Batchelor, HDonald Princeton University At innBNL--41767 DE89 002179 Abstract An electron gun utilizing aradio frequency on the design of (he electron gun which will provide r.f. bunches of upto 101 electrons synchronized

McDonald, Kirk

205

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. PMID:24106578

Kebede, Bekana; Abate, Tatek; Mekonnen, Desalew

2013-01-01

206

Using globular clusters to test gravity in the weak acceleration regime: NGC 6171  

E-print Network

As part of an ongoing program to test Newton's law of gravity in the low acceleration regime using globular clusters, we present here new results obtained for NGC 6171. Combining VLT spectra for 107 stars with data from the literature, we were able to trace the velocity dispersion profile up to 16 pc from the cluster center, probing accelerations of gravity down to 3.5e-9 cm/s/s. The velocity dispersion is found to remain constant at large radii rather than follow the Keplerian falloff. Similar results were previously found for the globular clusters $\\omega$ Centauri and M15. We have now studied three clusters and all three have been found to have a flat dispersion profile beyond the radius where their internal acceleration of gravity is ~ 1e-8 cm/s/s. Whether this indicates a failure of Newtonian dynamics or some more conventional dynamical effect (e.g., tidal heating) is still unclear. However, the similarities emerging between globular clusters and elliptical galaxies seem to favor the first of the two possibilities.

Riccardo Scarpa; Gianni Marconi; Roberto Gilmozzi

2004-11-03

207

Lead-bismuth target design for the subcritical multiplier (SCM) of the accelerator driven test facility (ADTF)..  

National Technical Information Service (NTIS)

A lead-bismuth eutectic (LBE) target design concept has been developed to drive the subcritical multiplier (SCM) of the accelerator-driven test facility (ADTF). This report gives the target design description, the results from the parametric studies, and ...

Y. Gohar, P. J. Finck, L. Krajtl, J. Herceg, W. D. Pointer, J. Saiveau, T. Sofu, A. L. Hanson, M. Todosow, M. Koploy, P. Mijatovic

2002-01-01

208

Accelerated-life testing of sintered filters for high-temperature corrosive environments  

SciTech Connect

Thermal waste treatment systems generate harsh off-gas environments in the event of an excursion from normal operating conditions. These harsh environments consist of chlorine and other halogens, sulfur, salts, and.erosive particles at temperatures approaching 450 C. An accelerated-life tester was developed to generate these corrosive environments and to provide a means for testing a variety of new and promising materials for use in thermal waste treatment systems. This paper discusses the use of the accelerated-life tester to investigate corrosion of sintered ceramic (silicon carbide) and stainless steel alloy (SS316B) filters. Each filter sample was characterized by measurement of weight change, and by results obtained from surface analytical techniques. In this Phase 1 investigation, porous sintered silicon carbide (SiC) filter elements were found to be relatively inert to the test environment. Under identical exposure conditions, SS316B filter elements were found to corrode significantly. These tests confirmed that porous sintered SiC is a promising filter material for use in hot corrosive HCl-containing gas environments.

Quick, N.R. [EG and G Rocky Flats, Golden, CO (United States); Weber, L.D. [Pall Corp., Port Washington, NY (United States)

1995-12-31

209

Ferrographic analysis of wear debris generated in accelerated rolling element fatigue tests  

NASA Technical Reports Server (NTRS)

The types and quantities of wear particles generated during accelerated ball rolling contact fatigue tests were determined. Ball specimens were made of AMS 5749, a corrosion resistant, high-temperature bearing steel. The lubricant was a super-refined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.215 times 10 to the 9th power Pa and a shaft speed of 10,000 rpm. Four types of wear particles were observed; normal rubbing wear particles, fatigue spall particles, spheres, and friction polymer.

Jones, W. R., Jr.; Parker, R. J.

1977-01-01

210

Ferrographic analysis of wear debris generated in accelerated rolling element fatigue tests  

NASA Technical Reports Server (NTRS)

Ferrographic analysis was used to determine the types and quantities of wear particles generated during accelerated rolling contact fatigue tests. The NASA five-ball rolling contact fatigue tester was used. Ball specimens were made of AMS 5749, a corrosion-resistant high-temperature bearing steel. The lubricant was a super-refined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.52 billion Pa and a shaft speed of 10,000 rpm. Four types of wear particles were observed: normal rubbing wear particles, fatigue spall particles, spheres, and friction polymer.

Jones, W. R., Jr.; Parker, R. J.

1977-01-01

211

Upgrade of the A0 photoinjector laser system for NML accelerator test facility at Fermilab  

SciTech Connect

The current Fermilab A0 Photoinjector laser system includes a seed laser, a flashlamp pumped multipass amplifier cavity, a flashlamp pumped 2-pass amplifier system followed by an Infra-Red (IR) to Ultra-Violet (UV) conversion stage. However the current system can only deliver up to 800 pulses due to the low efficiency of Nd:Glass used inside multi-pass cavity. In this paper we will report the effort to develop a new multi pass cavity based on Nd:YLF crystal end-pumped by diode laser. We will also discuss the foreseen design of the laser system for the NML accelerator test facility at Fermilab.

Ruan, J.; Edwards, H.; Fliller, R.P., III; Santucci, J.K.; /Fermilab

2007-06-01

212

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

213

Testing the Newton second law in the regime of small accelerations  

E-print Network

It has been pointed out that the Newtonian second law can be tested in the very small acceleration regime by using the combined movement of the Earth and Sun around the Galactic center of mass. It has been shown that there are only two brief intervals during the year in which the experiment can be completed, which correspond to only two specific spots on the Earth surface. An alternative experimental setup is presented to allow the measurement to be made on Earth at any location and at any time.

V. A. De Lorenci; M. Faundez-Abans; J. P. Pereira

2010-02-15

214

Accelerated-aging tests of fiber Bragg gratings written in hydrogen loaded tapered optical fibers  

NASA Astrophysics Data System (ADS)

In this paper we show preliminary experimental studies on accelerated aging-tests of tapered fiber Bragg gratings (TFBG). Examined gratings were fabricated on tapered and then hydrogenated optical fibers using uniform phase mask and scanning technique. In particular, the impact of isothermal annealing of TFBGs on their spectral and dispersion characteristics was analyzed. Experimental results show that although reflectance levels of TFBGs significantly reduce due to the aging process, slopes of the group delay characteristics remain practically unchanged. New knowledge on spectral and dispersion characteristics of TFBGs written in hydrogen loaded optical fibers is important in possible applications, where long-term stability and reliability is required.

Osuch, Tomasz; Herman, Dorota; Markowski, Konrad; Jedrzejewski, Kazimierz

2014-05-01

215

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

216

SLAC National Accelerator Laboratory Accelerator Physics Faculty Search  

E-print Network

SLAC National Accelerator Laboratory Accelerator Physics Faculty Search The SLAC National Accelerator Laboratory invites applications for a faculty appointment in Accelerator Physics (LCLS), LCLS-II, SPEAR-3, NLC Test Accelerator (NLCTA), Cathode Test Facility (CTF), the proposed

Ford, James

217

Neutron life time value measured by storing ultracold neutrons with detection of inelastically scattered neutrons  

Microsoft Academic Search

The neutron life time ?n was measured by storage of ultracold neutrons (UCN) in a material bottle covered with Fomblin oil. The inelastically scattered neutrons were detected by surrounding neutron counters monitoring the UCN losses due to upscattering at the bottle walls. Comparing traps with different surface to volume ratios the free neutron life time was deduced. Consistent results for

S. Arzumanov; L. Bondarenko; S. Chernyavsky; W. Drexel; A. Fomin; P. Geltenbort; V. Morozov; Y. Panin; J. Pendlebury; K. Schreckenbach

2000-01-01

218

Quantitative measurement of the life time of turbulence in pipe flow  

Microsoft Academic Search

In pipe flow at low Reynolds number, decay of localized disturbances is observed. As the Reynolds number is increased, the question emerges whether the life time of these disturbances diverges at a finite Reynolds number or remains transient. In the current investigation we determine their life time quantitatively from pressure measurements, while in previous investigations the distance over which a

D. J. Kuik; Christian Poelma; Bjorn Hof; J. Westerweel

2009-01-01

219

Prototyping games for training and education in Second Life: Time2Play and TREG  

E-print Network

and computer-savvy [Aldrich 2005]. The Time2Play and TREG games were created in Second Life (SL) using itsPrototyping games for training and education in Second Life: Time2Play and TREG K. Vega A. Pereira of Informatics, Brazil Figure 1: Educational Games in Second Life: Time2Play (left) and TREG (right). Abstract

Barbosa, Alberto

220

A General Bayes Weibull Inference Model for Accelerated Life Testing J. Ren Van Dorp & Thomas A. Mazzuchi  

E-print Network

presents the development of a general Bayes inference model for accelerated life testing. The failure times. With such MTTF's, it is often too time consuming and too costly to test these items in their use (or nominal If such is the case, it has become aÃ? standard procedure (see MIL-STD-781C) to test these items under more severe

van Dorp, Johan René

221

Abstract--Comparing to the most common reliability tests this work presents a new approach of accelerated  

E-print Network

Abstract-- Comparing to the most common reliability tests this work presents a new approach of accelerated testing, by combining temperature, humidity and pressure cycling with voltage stress. A design of experiments methodology has been proposed to test IGBT inverters and understand environmental factors effect

Boyer, Edmond

222

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

223

Membrane degradation during combined chemical and mechanical accelerated stress testing of polymer electrolyte fuel cells  

NASA Astrophysics Data System (ADS)

A cyclic open circuit voltage (COCV) accelerated stress test (AST) is designed to screen the simultaneous effect of chemical and mechanical membrane degradation in polymer electrolyte fuel cells. The AST consists of a steady state OCV phase to accelerate chemical degradation and periodic wet/dry cycles to provide mechanical degradation. The membrane degradation process induced by COCV AST operation is analyzed using a standard MEA with PFSA ionomer membrane. The OCV shows an initially mild decay rate followed by a higher decay rate in the later stages of the experiment. Membrane failure, defined by a threshold convective hydrogen leak rate, is obtained after 160 h of operation. Uniform membrane thinning is observed with pinhole formation being the primary cause of failure. Mechanical tensile tests reveal that the membrane becomes stiffer and more brittle during AST operation, which contributes to mechanical failure upon cyclic humidity induced stress. Solid state 19F NMR spectroscopy and fluoride emission measurements demonstrate fluorine loss from both side chain and main chain upon membrane exposure to high temperature and low humidity OCV condition.

Lim, C.; Ghassemzadeh, L.; Van Hove, F.; Lauritzen, M.; Kolodziej, J.; Wang, G. G.; Holdcroft, S.; Kjeang, E.

2014-07-01

224

PXIe-based LLRF architecture and versatile test bench for heavy ion linear acceleration  

E-print Network

This work describes the architecture of a digital LLRF system for heavy-ion acceleration developed under the specification of the projected future heavy-ion accelerator facility in Huelva, Spain. A prototype LLRF test bench operating at 80MHz in CW mode has been designed and built. The core LLRF control has been digitally implemented on a PXIe chassis, including an FPGA for digital signal processing and a real time controller. The test bench is completed with a good quality signal generator used as master frequency reference, an analog front end for reference modulation and signal conditioning, small RF components completing the circuit, as well as a tunable resonant cavity at 80 MHz, whose RF amplitude, phase and frequency are real-time controlled and monitored. The presented LLRF system is mainly digitally implemented using a PXIe platform provided by National Instruments, and is based on IQ modulation and demodulation. The system can be configured to use both direct sampling and undersampling techniques, r...

Jugo, I Badillo J; Feutchwanger, J; Vicente, C San; Etxebarria, V

2014-01-01

225

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

226

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

227

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

228

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

229

Studies of high-brightness electron beams at the accelerator test facility  

NASA Astrophysics Data System (ADS)

The Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL) is a user facility providing high brightness electron beams and synchronized high power lasers for researches in free-electron lasers and high-gradient laser acceleration schemes. The system consists of a radio-frequency (RF) electron gun with a photo-cathode, two SLAC linear accelerator (linac) sections and three experiment beamlines, as well as a 10- ps Nd:YAG laser and a high power CO2 laser. The facility is capable of delivering electron bunches with temporal duration of 1-10ps, charge of the order of 1 nC, normalized emittance in the order of 10-6 mm.mrad and energy up to 70 MeV. The research described in this dissertation represents a comprehensive study of the beam dynamics of the high brightness electron beams at the ATF accelerator system. The charge emitted by the photo-cathode depends on the work function and the photon energy as well as the strength of the electric field. This relationship has been determined and it provides a convenient method to determine the laser to RF phase. Standard techniques like the multiple-screen method and the quadrupole-scan method were used to characterize the transverse phase space. We have also developed computed tomography techniques for a detailed characterization of the transverse phase space. The longitudinal phase space is analyzed by a dipole energy spectrometer incorporated into transport line. We developed a technique for selecting pico-second slices of the electron beam along the longitudinal position within the bunch. Using the slice-selection technique, we measured the time duration of the electron bunches under different operating conditions of the electron gun. The bunch length is a function of the field gradient in the gun and the laser to RF phase. The transverse phase space ellipses of different slices along the bunches were measured for a number of current settings of the emittance compensation solenoid. The changes in the relative orientations of the ellipses are consistent with the prediction by the relativities envelope equation. The dependence of the slice emittance on different system parameters was also studied. Finally, the use of optical transition radiation for electron beam diagnostics was explored.

Qiu, Joe Xu Zhou

1997-12-01

230

A new approach of studying correlation between outdoor exposure and indoor accelerated corrosion test for high polymer materials  

Microsoft Academic Search

The correlation between outdoor exposure and indoor accelerated corrosion test for high polymer materials was investigated\\u000a according to the variation of the functional group of exposure models aged. Environment aging intesities at different zones\\u000a (Wuhan and Lasa with the same latitude) and the influences of indoor accelerating factors including water and ultraviolet\\u000a on weathering performance of high polymer materials were

Yang Lixia; Li Xiaogang; Zhang Sanping

2006-01-01

231

Quantitative measurement of the life time of turbulence in pipe flow  

NASA Astrophysics Data System (ADS)

In pipe flow at low Reynolds number, decay of localized disturbances is observed. As the Reynolds number is increased, the question emerges whether the life time of these disturbances diverges at a finite Reynolds number or remains transient. In the current investigation we determine their life time quantitatively from pressure measurements, while in previous investigations the distance over which a structure survives has been determined. The obtained results confirm that the life time of localized disturbances does not diverge in the range of Reynolds numbers covered in the current experiment.

Kuik, D. J.; Poelma, Christian; Hof, Bjorn; Westerweel, J.

232

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

233

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

234

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

235

Cavity beam position monitor system for the Accelerator Test Facility 2  

SciTech Connect

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 {mu}m for the S-band system. Without attenuation the best recorded C-band cavity resolution was 27 nm.

Kim, Y.I.; /Kyungpook Natl. U.; Ainsworth, R.; /Royal Holloway, U. of London; Aryshev, A.; /KEK, Tsukuba; Boogert, S.T.; Boorman, G.; /Royal Holloway, U. of London; Frisch, J.; /SLAC; Heo, A.; /Kyungpook Natl. U.; Honda, Y.; /KEK, Tsukuba; Hwang, W.H.; Huang, J.Y.; /Pohang Accelerator Lab.; Kim, E-S.; /Kyungpook Natl. U. /Pohang Accelerator Lab. /Royal Holloway, U. of London /KEK, Tsukuba

2012-04-02

236

Beam profile of the advanced test accelerator under laser-ion guiding  

SciTech Connect

Laser-ion guiding is currently deployed on the Advanced Test Accelerator (ATA). Beam profiles are measured as a function of time by detecting optical emissions from foils inserted into the beam path. The beam size is observed to grow with time into the pulse. Two other experimental measurements support this observation: (1) vacuum expansion of the beam shows a loss of current in the latter part of the pulse; (2) beam transport through a pipe of reduced diameter results in a similar loss of current in the tail. These observations of increasing beam size are contrary to expectations based on increasing focus strength due to beam-induced ionization. Possible explanations will be presented.

Chong, Y.P.; Caporaso, G.J.; Lauer, E.J.; Prono, D.S.; Rainer, F.; Struve, K.W.; Weir, J.T.

1986-01-01

237

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

238

Life-time and hierarchy of memory in the dissipative quantum model of brain  

E-print Network

Some recent developments of the dissipative quantum model of brain are reported. In particular, the time-dependent frequency case is considered with its implications on the different life-times of the collective modes.

Eleonora Alfinito; Giuseppe Vitiello

1999-12-30

239

Life-time and hierarchy of memory in the dissipative quantum model of brain  

E-print Network

Some recent developments of the dissipative quantum model of brain arereported. In particular, the time-dependent frequency case is considered withits implications on the different life-times of the collective modes.

Alfinito, E; Alfinito, Eleonora; Vitiello, Giuseppe

1999-01-01

240

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

NASA Astrophysics Data System (ADS)

The prediction of long-term fatigue life of various FRP laminates combined with resins, fibers and fabrics for marine use under temperature and water environments were performed by our developed accelerated testing methodology based on the time-temperature superposition principle (TTSP). The base material of five kinds of FRP laminates employed in this study was plain fabric CFRP laminates T300 carbon fibers/vinylester (T300/VE). The first selection of FRP laminate to T300/VE was the combinations of different fabrics, that is flat yarn plain fabric T700 carbon fibers/vinylester (T700/VE-F) and multi-axial knitted T700 carbon fibers/vinylester (T700/VE-K) for marine use and the second selection of FRP laminates to T300/VE was the combinations with different fibers and matrix resin, that is plain fabric T300 carbon fibers/epoxy (T300/EP) and plain fabric E-glass fibers/vinylester (E-glass/VE). These five kinds of FRP laminates were prepared under three water absorption conditions of Dry, Wet and Wet C Dry after molding. The three-point bending constant strain rate (CSR) tests for these FRP laminates at three conditions of water absorption were carried out at various temperatures and strain rates. Furthermore, the three-point bending fatigue tests for these specimens were carried out at various temperatures and frequencies. The flexural CSR and fatigue strengths of these five kinds of FRP laminates strongly depend on water absorption as well as time and temperature. The mater curves of fatigue strength as well as CSR strength for these FRP laminates at three water absorption conditions are constructed by using the test data based on TTSP. It is possible to predict the long term fatigue life for these FRP laminates under an arbitrary temperature and water absorption conditions by using the master curves.

Miyano, Yasushi; Nakada, Masayuki

241

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

E-print Network

The gravitational fields of two isolated ellipticals, NGC 720 and NGC 1521, have been recently measured to very large galactic radii (~100 and ~200 kpc), assuming hydrostatic balance of the hot gas enshrouding them. They afford, for the first time to my knowledge, testing 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 a0/10, 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-vs-dark-matter controversy go far beyond the simple fact of two more galaxies conforming to MOND.

Mordehai Milgrom

2012-05-07

242

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

243

Low-emittance tuning at the Cornell Electron Storage Ring Test Accelerator  

NASA Astrophysics Data System (ADS)

In 2008 the Cornell Electron/Positron Storage Ring (CESR) was reconfigured from an electron/positron collider to serve as a test bed for the International Linear Collider damping rings. One of the primary goals of the CESR Test Accelerator (CesrTA) project is to develop a fast low-emittance tuning method which scales well to large rings such as the ILC damping rings, and routinely achieves a vertical emittance of order 10 pm at 2.085 GeV. This paper discusses the tuning methods developed at CesrTA to achieve low-emittance conditions. One iteration of beam-based measurement and correction requires about 10 min. A minimum vertical emittance of 10.3(+3.2/-3.4)sys(±0.2)stat pm has been achieved at 2.085 GeV. In various configurations and beam energies the correction technique routinely achieves vertical emittance around 10 pm after correction, with rms coupling <0.5%. The measured vertical dispersion is dominated by beam position monitor systematics. The propagation of uncertainties in the emittance measurement is described in detail. Simulations modeling the effects of magnet misalignments, beam position monitor errors, and the emittance correction algorithm suggest the residual vertical emittance measured at the conclusion of the tuning procedure is dominated by sources other than optics errors and misalignments.

Shanks, J.; Rubin, D. L.; Sagan, D.

2014-04-01

244

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

245

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.

1992-01-01

246

Accelerated aging, natural aging, and small punch testing of gamma-air sterilized polycarbonate urethane acetabular components.  

PubMed

The objectives of this study were three-fold: (1) to determine the applicability of the small punch test to characterize Bionate 80A polycarbonate urethane (PCU) acetabular implants; (2) to evaluate the susceptibility of PCU acetabular implants to exhibit degradation of mechanical behavior following gamma irradiation in air and accelerated aging; and (3) to compare the oxidation of gamma-air sterilized PCU following accelerated aging and 5 years of natural shelf aging. In addition to attenuated total reflectance-Fourier transform infrared spectroscopy, we also adapted a miniature specimen mechanical test, the small punch test, for the deformable PCU cups. Accelerated aging was performed using ASTM F2003, a standard test that represents a severe oxidative challenge. The results of this study suggest that the small punch test is sufficiently sensitive and reproducible to discriminate slight differences in the large-deformation mechanical behavior of Bionate 80A following accelerated aging. The gamma-air sterilized PCU had a reduction of 9% in ultimate load after aging. Five years of shelf aging had little effect on the mechanical properties of the PCU. Overall, our findings suggest that the Bionate 80A material has greater oxidative stability than ultra-high molecular weight polyethylene following gamma irradiation in air and exposure to a severe oxidative challenge. PMID:20166119

Kurtz, S M; Siskey, R; Reitman, M

2010-05-01

247

Beam test of the acceleration system with the DDS in HIMAC synchrotron  

Microsoft Academic Search

We have examined the acceleration efficiency as a function of B-clock step size from 0.1 to 2.0 Gauss\\/pulse at the HIMAC synchrotron. The result showed good acceleration efficiency with 0.2 Gauss\\/pulse, even if we haven't used feedback. The larger width case shows significant loss, suggesting a limitation due to stepwise change of acceleration frequency

M. Kanazawa; K. Noda; E. Takada; M. Kumada; A. Itano; S. Watanabe; Y. Morii

1997-01-01

248

Tested by Fire - How two recent Wildfires affected Accelerator Operations at LANL  

SciTech Connect

In a little more than a decade two large wild fires threatened Los Alamos and impacted accelerator operations at LANL. In 2000 the Cerro Grande Fire destroyed hundreds of homes, as well as structures and equipment at the DARHT facility. The DARHT accelerators were safe in a fire-proof building. In 2011 the Las Conchas Fire burned about 630 square kilometers (250 square miles) and came dangerously close to Los Alamos/LANL. LANSCE accelerator operations Lessons Learned during Las Conchas fire: (1) Develop a plan to efficiently shut down the accelerator on short notice; (2) Establish clear lines of communication in emergency situations; and (3) Plan recovery and keep squirrels out.

Spickermann, Thomas [Los Alamos National Laboratory

2012-08-01

249

Exploratory test of utility of magnetic insulation for electrostatic accelerators L. R. Grisham, A. von Halle, A. F. Carpe, Guy Rossi, K. R. Gilton et al.  

E-print Network

Exploratory test of utility of magnetic insulation for electrostatic accelerators L. R. Grisham, A;Exploratory test of utility of magnetic insulation for electrostatic accelerators L. R. Grisham,a) A. von a preliminary exploratory test of whether this magnetic insulation approach might be of benefit at a modest

Gilson, Erik

250

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

251

Accelerated hermeticity testing of a glasssilicon package formed by rapid thermal processing aluminum-to-silicon nitride bonding$  

E-print Network

temperature and long processing time [3]. On the other hand, reliability and long-term stability of sealedAccelerated hermeticity testing of a glass±silicon package formed by rapid thermal processing aluminum-to-silicon nitride bonding$ Mu Chiao* , Liwei Lin Department of Mechanical Engineering, Berkeley

Lin, Liwei

252

Application of a relational data base for documenting the Ground Test Accelerator cable routing and wiring interconnections  

Microsoft Academic Search

The Ground Test Accelerator (GTA) has many different types of equipment and interconnections to support the operation. Various functions are performed by these equipments such as signal generation, instrument control, and diagnostics. All of the thousands of signals must be routed from the protected tunnel area into the operational control area of the building. Tabulating the routing of these cables,

D. B. Blackwell; W. L. Rogers; V. W. Brown; G. A. Ekeroth; T. O. McGill

1990-01-01

253

Acceleration ground test program to verify GAS payload No. 559 structure/support avionics and experiment structural integrity  

NASA Technical Reports Server (NTRS)

Acceleration ground tests were conducted on the Get Away Special (GAS) payload 559 to verify the structural integrity of the structure/support avionics and two of the planned three flight experiments. The ITA (Integrated Test Area) Standardized Experiment Module (ISEM) structure was modified to accommodate the experiments for payload 559. The ISEM avionics consisted of a heavy duty sliver zinc power supply, three orthogonal-mounted low range microgravity accelerometers, a tri-axis high range accelerometer, a solid state recorder/programmer sequencer, and pressure and temperature sensors. The tests were conducted using the Gravitational Plant Physiology Laboratory Centrifuge of the University City Science Center in Philadelphia, PA. The launch-powered flight steady state acceleration profile of the shuttle was simulated from lift-off through jettison of the External Tank (3.0 g's). Additional tests were conducted at twice the nominal powered flight acceleration levels (6 g's) and an over-test condition of four times the powered flight loads to 12.6 g's. The present test program has demonstrated the value of conducting ground tests to verify GAS payload experiment integrity and operation before flying on the shuttle.

Cassanto, John M.; Cassanto, Valerie A.

1988-01-01

254

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

255

Utilization of optical image data from the Advanced Test Accelerator (ATA)  

SciTech Connect

Extensive use is made of optical diagnostics to obtain information on the 50-MeV, 10-kA, 70-ns pulsed-electron beam produced by the Advanced Test Accelerator (ATA). Light is generated by the beam striking a foil inserted in the beamline or through excitation of the gas when the beamline is filled with air. The emitted light is collected and digitized. Two-dimensional images are recorded by either a gated framing camera or a streak camera. Extraction of relevant beam parameters, such as current density, current, and beam size, requires an understanding of the physics of the light-generation mechanism and an ability to handle and properly exploit a large digital database of image data. We will present a brief overview of the present understanding of the light-generation mechanisms in foil and gas, with emphasis on experimental observations and trends. We will review our data management and analysis techniques and indicate successful approaches for extracting beam parameters.

Chambers, F.W.; Kallman, J.S.; Slominski, M.E.; Chong, Y.P.; Donnelly, D.; Cornish, J.P.

1987-01-01

256

Measurement and compensation of horizontal crabbing at the Cornell Electron Storage Ring Test Accelerator  

NASA Astrophysics Data System (ADS)

In storage rings, horizontal dispersion in the rf cavities introduces horizontal-longitudinal (xz) coupling, contributing to beam tilt in the xz plane. This coupling can be characterized by a "crabbing" dispersion term ?a that appears in the normal mode decomposition of the 1-turn transfer matrix. ?a is proportional to the rf cavity voltage and the horizontal dispersion in the cavity. We report experiments at the Cornell Electron Storage Ring Test Accelerator where xz coupling was explored using three lattices with distinct crabbing properties. We characterize the xz coupling for each case by measuring the horizontal projection of the beam with a beam size monitor. The three lattice configurations correspond to (i) 16 mrad xz tilt at the beam size monitor source point, (ii) compensation of the ?a introduced by one of two pairs of rf cavities with the second, and (iii) zero dispersion in rf cavities, eliminating ?a entirely. Additionally, intrabeam scattering is evident in our measurements of beam size vs rf voltage.

Ehrlichman, M. P.; Chatterjee, A.; Hartung, W.; Heltsley, B.; Peterson, D. P.; Rider, N.; Rubin, D.; Sagan, D.; Shanks, J. P.; Wang, S. T.

2014-04-01

257

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

258

A modified feed-forward control system at the Accelerator Test Facility  

NASA Astrophysics Data System (ADS)

A modified feed-forward control system has been operated at the Brookhaven Accelerator Test Facility to control the phase and amplitude of two high power klystron rf systems used to power a photocathode rf gun and a traveling wave electron linac. The changes to the control algorithm include an improved handling of cross coupling between the amplitude and the phase channels, an improved calibration routine that allows for changes in the matrix elements due to the variable base-line and improved filtering. The modifications to the software include modularity, portability, and user-friendliness. Improvements to the hardware include a linearized phase and amplitude controller with dc biasing for an improved dynamic range. The feed-forward system can handle nonlinear and noninstantaneous systems. With simultaneous regulation of two channels, the phase and the amplitude fluctuations over a time span of more than 3 ?S were reduced to less than ±0.2° and ±0.2%, from the initial ±2.7° and ±1.8%, respectively.

Liu, Y.; Cline, D.; Ben-Zvi, I.; Wang, X. J.; Sheehan, J.; Batchelor, K.; Malone, R.; Issapour, M.

1997-02-01

259

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. PMID:24482775

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

2013-01-01

260

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

261

Fabrication and testing of Rutherford-type cables for react and wind accelerator magnets  

SciTech Connect

A common coil design for a high-field accelerator dipole magnet using a Nb{sub 3}Sn cable with the React-and-Wind approach is pursued by a collaboration between Fermilab and LBNL. The design requirements for the cable include a high operating current so that a field of 10-11 T can be produced, together with a low critical current degradation due to bending around a 90 mm radius. A program, using ITER strands of the internal tin type, was launched to develop the optimal cable design for React-and-Wind common coil magnets. Three prototype cable designs, all 15 mill wide, were fabricated: a 41-strand cable with 0.7 mm diameter strands; a 57-strand cable with 0.5 mm diameter strands; and a 259 strand multi-level cable with a 6-around-1 sub-element using 0.3 mm diameter wire. Two versions of these cables were fabricated: one with no core and one with a stainless steel core. Additionally, the possibility of a wide (22 mm) cable made from 0.7 mm strand was explored. This paper describes the first results of the cable program including reports on cable fabrication and reaction, first winding tests and first results of the measurement of the critical current degradation due to cabling and bending.

Bauer, P.; Ambrosio, G.; Andreev, N.; Barzi, E.; Dietderich, D.; Ewald, K.; Fratini, M.; Ghosh, A.K.; Higley, H.C.; Kim, S.W.; Miller, G.; Miller, J.; Ozelis, J.; Scanlan, R.M.

2000-09-11

262

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

263

Cosmic opacity: cosmological-model-independent tests and their impacts on cosmic acceleration  

E-print Network

With assumptions that the violation of the distance-duality (DD) relation entirely arises from non-conservation of the photon number and 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 SN Ia sample, which is taken for observed $D_\\mathrm{L}$, and galaxy cluster samples compiled by De Filippis {\\it et al.} and Bonamente {\\it et al.}, which are responsible for providing observed $D_\\mathrm{A}$. Two parameterizations, $\\tau(z)=2\\epsilon z$ and $\\tau(z)=(1+z)^{2\\epsilon}-1$ are adopted for the optical depth associated to the cosmic absorption. We find that, an almost transparent universe is favored by Filippis {\\it et al.} sample but it is only marginally accommodated by Bonomente {\\it et al.} samples at 95.4% confidence level (C. L.) (even at 99.7% C. L. when the $r<100 \\mathrm{kpc}$-cut spherical $\\beta$ model is considered). Taking the possible cosmic absorption (in 68.3% C. L. range) constrained from the model-independent tests into consideration, we correct the distance modulus of SNe Ia and then use them to study their cosmological implications. The constraints on the $\\Lambda$CDM show that a decelerating expanding universe with $\\Omega_\\Lambda=0$ is only allowed at 99.7% C. L. by observations when the Bonamente {\\it 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 to be supported by current observations.

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

2013-04-27

264

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

265

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

266

Observation and Characterization of Coherent Optical Radiation and Microbunching Instability in the SLAC Next Linear Collider Test Accelerator  

SciTech Connect

The NLC Test Accelerator (NLCTA) at SLAC is currently configured for a proof-of-principle echo-enabled harmonic generation (EEHG) experiment using an 120 MeV beam. During commissioning, unexpected coherent optical undulator radiation (CUR) and coherent optical transition radiation (COTR) was observed when beam is accelerated off-crest and compressed after the chicanes. The CUR and COTR is likely due to a microbunching instability where the initial small ripples in cathode drive laser is compressed and amplified. In this paper we present the observation and characterization of the CUR, COTR and microbunching instability at NLCTA.

Weathersby, S.; Dunning, M.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Xiang, D.; /SLAC

2011-06-02

267

Status of the visible Free-Electron Laser at the Brookhaven Accelerator Test Facility  

SciTech Connect

The 500 nm Free-Electron Laser (ATF) of the Brookhaven National Laboratory is reviewed. We present an overview of the ATF, a high-brightness, 50-MeV, electron accelerator and laser complex which is a users' facility for accelerator and beam physics. A number of laser acceleration and FEL experiments are under construction at the ATF. The visible FEL experiment is based on a novel superferric 8.8 mm period undulator. The electron beam parameters, the undulator, the optical resonator, optical and electron beam diagnostics are discussed. The operational status of the experiment is presented. 22 refs., 7 figs.

Batchelor, K.; Ben-Zvi, I.; Fernow, R.C.; Fisher, A.S.; Friedman, A.; Gallardo, J.; Ingold, G.; Kirk, H.; Kramer, S.; Lin, L.; Rogers, J.T.; Sheehan, J.F.; van Steenbergen, A.; Woodle, M.; Xie, J.; Yu, L.H.; Zhang, R. (Brookhaven National Lab., Upton, NY (United States)); Bhowmik, A. (Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.)

1991-01-01

268

Formation and life-time of memory domains in the dissipative quantum model of brain  

E-print Network

We show that in the dissipative quantum model of brain the time-dependence ofthe frequencies of the electrical dipole wave quanta leads to the dynamicalorganization of the memories in space (i.e. to their localization in more orless diffused regions of the brain) and in time (i.e. to their longer orshorter life-time). The life-time and the localization in domains of the memorystates also depend on internal parameters and on the number of links that thebrain establishes with the external world. These results agree with thephysiological observations of the dynamic formation of neural circuitry whichgrows as brain develops and relates to external world.

Alfinito, E

2000-01-01

269

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

270

Accelerated Reader.  

ERIC Educational Resources Information Center

This paper provides an overview of Accelerated Reader, a system of computerized testing and record-keeping that supplements the regular classroom reading program. Accelerated Reader's primary goal is to increase literature-based reading practice. The program offers a computer-aided reading comprehension and management program intended to motivate…

Education Commission of the States, Denver, CO.

271

Novel SiO2-based antioxidant compound with significantly extended life-time and activity  

E-print Network

Novel SiO2-based antioxidant compound with significantly extended life-time and activity Georgios A of Process Engineering ETH Zurich, Switzerland #12;May 15, 2013 Copyright ETH Zürich 2 Antioxidants: What 15, 2013 Copyright ETH Zürich 3 Current antioxidants Phenols are potent antioxidants Gallic acid

Daraio, Chiara

272

A null test of the metric nature of the cosmic acceleration  

SciTech Connect

We discuss the testable predictions of a phenomenological model in which the accelerated expansion of the universe is the result of the action of a non-gravitational force field, rather than the effect of a negative-pressure dark energy fluid or a modification of general relativity. We show, through the equivalence principle, that in such a scenario the cosmic acceleration felt by distant standard candles like SNIa (type Ia supernovae (SNe)) depends on the mass of the host system, being larger in isolated galaxies than in rich clusters. As a consequence, the scatter in the observed SNIa Hubble diagram has mostly a physical origin in this scenario: in fact, the SNIa distance modulus is increasing, at fixed redshift, for SNe that are hosted in isolated galaxies with respect to the case of SNe hosted in rich galaxy clusters. Due to its strong dependence on the astrophysical environments of standard candles, we conclude that alternative non-gravitational mechanisms for the observed accelerated expansion of the universe can be interestingly contrasted against the standard metric interpretation of the cosmological acceleration by means of an environmental analysis of the cosmic structures in which SNIa are found. The possible absence of such environmental effects would definitely exclude the possibility of non-gravitational mechanisms being responsible for the accelerated cosmological expansion and will therefore reinforce a metric interpretation.

Buzzi, A; Marinoni, C [Centre de Physique Theorique, UMR 6207 CNRS-Luminy and Universite de Provence, Case 907, F-13288 Marseille Cedex 9 (France)] [Centre de Physique Theorique, UMR 6207 CNRS-Luminy and Universite de Provence, Case 907, F-13288 Marseille Cedex 9 (France); Colafrancesco, S, E-mail: buzzi@cpt.univ-mrs.fr, E-mail: christian.marinoni@cpt.univ-mrs.fr, E-mail: cola@mporzio.inaf.it [ASI-ASDC, c/o ESRIN, Via G Galilei, I-00040 Frascati (Italy)] [ASI-ASDC, c/o ESRIN, Via G Galilei, I-00040 Frascati (Italy)

2008-11-15

273

Testing prototypes of high-temperature superconducting current leads of cryogenic stand for testing magnetic elements of the NICA accelerating complex  

NASA Astrophysics Data System (ADS)

In the Laboratory of High Energies at the Joint Institute for Nuclear Research, as part of the NICA-MPD [1] project, tests of two prototypes of HTSC current leads prepared at ASIPP institute (Hefei, China) have been performed [2, 3] to measure electric and heat parameters and to search for structural and physical drawbacks. Based on the experimental results, necessary changes are made in the structure of HTSC current leads of the testing stand for the magnetic element testing of the NICA accelerating complex and its basic setups: the Nuclotron, Booster, and Collider.

Kres, E. V.; Kadenko, I. N.; Bessheiko, O. A.; Belov, D. V.; Blinov, N. A.; Galimov, A. R.; Zorin, A. G.; Karpinsky, V. N.; Nikiforov, D. N.; Pivin, R. V.; Smirnov, A. V.; Shevchenko, E. V.; Smirnov, S. A.; Khodzhibagiyan, G. G.; Liu, Cheng Lian

2014-09-01

274

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

275

Analysis of DC current accelerated life tests of GaN LEDs using a Weibull-based statistical model  

Microsoft Academic Search

Gallium-nitride-based light-emitting diode (LED) accelerated life tests were carried out over devices adopting two different packaging schemes (i.e., with plastic transparent encapsulation or with pure metallic package). Data analyses were done using a Weibull-based statistical description with the aim of estimating the effect of high current on device performance. A consistent statistical model was found with the capability to estimate

S. Levada; M. Meneghini; G. Meneghesso; E. Zanoni

2005-01-01

276

Long-Term and Accelerated Life Testing of a Novel Single-Wafer Vacuum Encapsulation for MEMS Resonators  

Microsoft Academic Search

We have developed a single-wafer vacuum encapsulation for microelectromechanical systems (MEMS), using a thick (20-mum) polysilicon encapsulation to package micromechanical resonators in a pressure 600 cycles of -50 to 80degC, and no measurable change in cavity pressure was seen. We have also performed accelerated leakage tests by driving hydrogen gas in and out of the encapsulation at elevated temperature. Two

Rob N. Candler; Matthew A. Hopcroft; Bongsang Kim; Woo-Tae Park; Renata Melamud; Manu Agarwal; Gary Yama; Aaron Partridge; Markus Lutz; Thomas W. Kenny

2006-01-01

277

Study of the effect of temperature on Pt dissolution in polymer electrolyte membrane fuel cells via accelerated stress tests  

NASA Astrophysics Data System (ADS)

Operation of polymer electrolyte membrane fuel cells (PEMFC) at higher cell temperatures accelerates Pt dissolution in the catalyst layer. In this study, a Pt dissolution accelerated stress testing protocol involving the application of a potentiostatic square-wave with 3 s at 0.6 V followed by 3 s at 1.0 V was developed to test fuel cell membrane electrode assemblies (MEAs). The use of this Pt dissolution protocol at three different temperatures (40 °C, 60 °C and 80 °C) was investigated for the same membrane electrode assembly composition. Impedance analysis of the membrane electrode assemblies showed an increase in polarization resistance during the course of the accelerated stress testing. Polarization analysis and electrochemical active surface area (ECSA) loss measurements revealed evidence of increased cathode catalyst layer (CCL) degradation due to Pt dissolution and deposition in the membrane as the cell temperature was raised. Scanning electron microscope (SEM) images confirmed the formation of Pt bands in the membrane. A diagnostic expression was developed to estimate kinetic losses due to oxygen reduction using the effective platinum surface area (EPSA) estimated from cyclic voltammograms. The results indicated that performance degradation occurred mainly due to Pt loss.

Dhanushkodi, S. R.; Kundu, S.; Fowler, M. W.; Pritzker, M. D.

2014-01-01

278

Studies of a new accelerated evaluation method for coating corrosion resistance — thermal cycling testing  

Microsoft Academic Search

A long time is often needed to differentiate the corrosion protection afforded by coatings systems, especially for high performance samples. Accelerating methods such as salt spray or Prohesion methods require as much as 2000h exposure to qualitatively differentiate high performance samples. General room temperature immersion electrochemical measurements {electrochemical impedance spectroscopy (EIS) and electrochemical noise methods (ENM)} may require up to

Gordon P Bierwagen; L He; J Li; L Ellingson; D. E Tallman

2000-01-01

279

A Test of Newton’s Law of Gravity in the Weak Acceleration Regime  

E-print Network

Newton’s law of gravity is routinely used to describe galaxies, even though its validity has been fully verified only within the solar system, in regimes of acceleration orders of magnitude stronger than the ones typical of galaxies. Though we have plenty of reasons for trusting Newton’s law also in these weak regimes,

Giampaolo Piotto; George Meylan; George Djorgovski; Marco Riello; Riccardo Scarpa; Gianni Marconi; Roberto Gilmozzi

2002-01-01

280

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

281

Formation and life-time of memory domains in the dissipative quantum model of brain  

E-print Network

We show that in the dissipative quantum model of brain the time-dependence of the frequencies of the electrical dipole wave quanta leads to the dynamical organization of the memories in space (i.e. to their localization in more or less diffused regions of the brain) and in time (i.e. to their longer or shorter life-time). The life-time and the localization in domains of the memory states also depend on internal parameters and on the number of links that the brain establishes with the external world. These results agree with the physiological observations of the dynamic formation of neural circuitry which grows as brain develops and relates to external world.

E. Alfinito; G. Vitiello

2000-02-03

282

Proton injector acceptance tests for a Dielectric Wall Accelerator (DWA):characterisation of Advanced Injection System of Light Ions (AISLI)  

NASA Astrophysics Data System (ADS)

To demonstrate the acceleration capability of a Dielectric Wall Accelerator (DWA), a proton injector has been developed at Peking University (PKU). It is composed of a compact permanent magnet 2.45 GHz Electron Cyclotron Resonance Ion Source (PKU PMECRIS) associated with a LEBT of two electrostatic Einzel lenses [1]. This injector is named as Advanced Injector System of Light Ions (AISLI). The acceptance tests have been performed with a 40 keV-55 mA hydrogen beam successfully passing through a ? 10 mm aperture diaphragm. This diaphragm is located 200 mm downstream the plasma emission hole at the location of the future DWA entrance flange. The beam rms emittance reached about 0.10 ? mm mrad in pulsed mode. This article describes the AISLI experimental setup, the measurement principle and the obtained beam characteristics.

Peng, S. X.; Ren, H. T.; Xu, Y.; Zhang, T.; Zhao(??), J.; Zhang, A. L.; Guo, Z. Y.; Chen, J. E.

2014-11-01

283

Direct measurement of the positive acceleration of the universe and testing inhomogeneous models under gravitational wave cosmology  

NASA Astrophysics Data System (ADS)

One possibility for explaining the apparent accelerating expansion of the universe is that we live in the center of a spherically inhomogeneous universe. Although current observations cannot fully distinguish ?CDM and these inhomogeneous models, direct measurement of the acceleration of the universe can be a powerful tool in probing them. We have shown that, if ?CDM is the correct model, DECIGO/BBO would be able to detect the positive redshift drift (which is the time evolution of the source redshift z) in 3-5 year gravitational wave (GW) observations from neutron-star binaries, which enables us to rule out any Lemaître-Tolman-Bondi (LTB) void model with monotonically increasing density profile. We may even be able to rule out any LTB model unless we allow unrealistically steep density profile at z ~ 0. This test can be performed with GW observations alone, without any reference to electromagnetic observations, and is more powerful than the redshift drift measurement using Lyman ? forest.

Yagi, Kent; Nishizawa, Atsushi; Yoo, Chul-Moon

2012-04-01

284

Mechanical Design of a High Energy Beam Absorber for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab  

SciTech Connect

A high energy beam absorber has been built for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In the facility's initial configuration, an electron beam will be accelerated through 3 TTF-type or ILC-type SRF cryomodules to an energy of 750MeV. The electron beam will be directed to one of multiple downstream experimental and diagnostic beam lines and then deposited in one of two beam absorbers. The facility is designed to accommodate up to 6 cryomodules, which would produce a 75kW beam at 1.5GeV; this is the driving design condition for the beam absorbers. The beam absorbers consist of water-cooled graphite, aluminum and copper layers contained in a helium-filled enclosure. This paper describes the mechanical implementation of the beam absorbers, with a focus on thermal design and analysis. The potential for radiation-induced degradation of the graphite is discussed.

Baffes, C.; Church, M.; Leibfritz, J.; Oplt, S.; Rakhno, I.; /Fermilab

2012-05-10

285

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

286

Design of a 3 GHz Accelerator Structure for the CLIC Test Facility (CTF 3) Drive Beam  

Microsoft Academic Search

For the CLIC two-beam scheme, a high-current, long-pulse drive beam is required for RF power generation. Taking advantage of the 3 GHz klystrons available at the LEP injector once LEP stops, a 180 MeV electron accelerator is being constructed for a nominal beam current of 3.5 A and 1.5 microsecond pulse length. The high current requires highly effective suppression of

Erk Jensen; E. Jensen; M. Luong; Antonio Millich; E. Rugo; I V Syratchev; L. Thorndahl

2000-01-01

287

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

288

Estimation in step-stress partially accelerated life tests for the Burr type XII distribution using type I censoring  

Microsoft Academic Search

In this paper, step-stress partially accelerated life tests are considered when the lifetime of a product follows a Burr type XII distribution. Based on type I censoring, the maximum likelihood estimates (MLEs) are obtained for the distribution parameters and acceleration factor. In addition, asymptotic variance and covariance matrix of the estimators are given. An iterative procedure is used to obtain

A. M. Abd-Elfattah; Amal S. Hassan; S. G. Nassr

2008-01-01

289

Reliability statistics perspective on standard wafer-level electromigration accelerated test (SWEAT)  

Microsoft Academic Search

Electromigration is an important reliability issue for ULSI. However, conventional electromigration test employing NIST structure usually takes too long for practical purposes. As the electromigration of metal interconnection has improved drastically over the year, the practical usefulness of the conventional electromigration test is even less, and the trend for electromigration test now is toward fast wafer level test, and SWEAT

Cher Ming Tan; K. N. C. Yeo

2000-01-01

290

Life-time history of suicide attempts and coronary artery disease in a community-dwelling elderly population  

E-print Network

Life-time history of suicide attempts and coronary artery disease in a community- dwelling elderly be at high risk of suicide attempts. Objective: The aim of the present study is to examine the relationship between CAD within a general population cohort and life-time history of psychiatric disorder and suicidal

Boyer, Edmond

291

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

2005-05-27

292

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

293

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

294

Occupant Response and Vehicle Acceleration in a 30 MPH Frontal Impact Test: 1981 Subaru DL-4 Wheel Drive-4 Door Wagon.  

National Technical Information Service (NTIS)

The purpose of the effort documented was to acquire occupant response and vehicle acceleration data in a 1981 Subaru DL - 4 Wheel Drive - 4 Door Wagon, NHTSA 811301 during a 30 MPH frontal fixed barrier impact test.

D. H. Hand

1981-01-01

295

A method to minimize test time for accelerated ageing of pHEMT's by analysis of the electronic fingerprint of the initial stage of degradation  

Microsoft Academic Search

Accelerated life testing provides a necessary tool for reliability validation but is generally very time-consuming as standard test take up to 2000 hours to proceed. In this article, results on the early stages of the ageing of pHEMT transistors are presented and it is shown that the necessary test time can be decreased from 2000 hours to 144 hours without

R. Petersen; W. De Ceuninck; L. De Schepper; J.-L. Muraro

2000-01-01

296

Test particle acceleration in a numerical MHD experiment of an anemone jet  

NASA Astrophysics Data System (ADS)

Aims: To use a 3D numerical MHD experiment representing magnetic flux emerging into an open field region as a background field for tracing charged particles. The interaction between the two flux systems generates a localised current sheet where MHD reconnection takes place. We investigate how efficiently the reconnection region accelerates charged particles and what kind of energy distribution they acquire. Methods: The particle tracing is done numerically using the Guiding Center Approximation on individual data sets from the numerical MHD experiment. Results: We derive particle and implied photon distribution functions having power law forms, and look at the impact patterns of particles hitting the photosphere. We find that particles reach energies far in excess of those seen in observations of solar flares. However the structure of the impact region in the photosphere gives a good representation of the topological structure of the magnetic field. Three movies are only available in electronic form at http://www.aanda.org

Rosdahl, K. J.; Galsgaard, K.

2010-02-01

297

Test particle acceleration in a numerical MHD experiment of an anemone jet  

E-print Network

To use a 3D numerical MHD experiment representing magnetic flux emerging into an open field region as a background field for tracing charged particles. The interaction between the two flux systems generates a localised current sheet where MHD reconnection takes place. We investigate how efficiently the reconnection region accelerates charged particles and what kind of energy distribution they acquire. The particle tracing is done numerically using the Guiding Center Approximation on individual data sets from the numerical MHD experiment. We derive particle and implied photon distribution functions having power law forms, and look at the impact patterns of particles hitting the photosphere. We find that particles reach energies far in excess of those seen in observations of solar flares. However the structure of the impact region in the photosphere gives a good representation of the topological structure of the magnetic field.

Rosdahl, Karl Joakim

2010-01-01

298

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. PMID:18774136

Race, Amos; Miller, Mark A.; Mann, Kenneth A.

2008-01-01

299

Testosterone in Newly Diagnosed, Antipsychotic-Na?ve Men with Nonaffective Psychosis: A Test of the Accelerated Aging Hypothesis  

PubMed Central

Objective Schizophrenia has been associated with age-related abnormalities, including abnormal glucose tolerance, increased pulse pressure, increased inflammation, abnormal stem cell signalling and shorter telomere length. These metabolic abnormalities as well as other findings suggest schizophrenia and related disorders might be associated with accelerated aging. Testosterone activity has a progressive decline with increasing age. Methods We tested the hypothesis that circulating biologically active testosterone is lower in newly diagnosed, antipsychotic-naïve male patients with nonaffective psychosis than in matched control subjects. Results Patients (n=33) were matched to control subjects (n=33) for age, gender, body mass index, socioeconomic status of the family of origin, and smoking. The free androgen index (FAI), a measure of biologically active testosterone, was significantly lower in the psychosis group [mean 57.7%, SD=26.1] than in control subjects [71.6%, 27.0; p=0.04], with an effect size of 0.53. Multivariate analysis also supported the findings. In the psychosis group, FAI had a significant negative correlation with the conceptual disorganization item (r=-0.35, p=0.049), but not with reality distortion (r=-0.21; p=0.24), negative symptoms (r=0.004; p=0.98) or depression (r=-0.014; p=0.94). Conclusion Lower testosterone is consistent with accelerated aging in nonaffective psychosis, but further testing of this hypothesis is needed. PMID:21949421

Fernandez-Egea, Emilio; Garcia-Rizo, Clemente; Miller, Brian; Parellada, Eduard; Justicia, Azucena; Bernardo, Miguel; Kirkpatrick, Brian

2011-01-01

300

Long life nickel electrodes for a nickel-hydrogen cell. III - Results of an accelerated test and failure analyses  

NASA Astrophysics Data System (ADS)

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.

301

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

302

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

303

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

304

How soccer players head the ball: A test of optic acceleration cancellation theory with virtual reality  

PubMed Central

We measured the movements of soccer players heading a football in a fully immersive virtual reality environment. In mid-flight the ball’s trajectory was altered from its normal quasi-parabolic path to a linear one, producing a jump in the rate of change of the angle of elevation of gaze (?) from player to ball. One reation time later the players adjusted their speed so that the rate of change of ? increased when it had been reduced and reduced it when it had been increased. Since the result of the player’s movement was to regain a value of the rate of change close to that before the disturbance, the data suggest that the players have an expectation of, and memory for, the pattern that the rate of change of ? will follow during the flight. The results support the general claim that players intercepting balls use servo control strategies and are consistent with the particular claim of Optic Acceleration Cancellation theory that the servo strategy is to allow ? to increase at a steadily decreasing rate. PMID:18472123

McLeod, Peter; Reed, Nick; Gilson, Stuart; Glennerster, Andrew

2010-01-01

305

Beam steering: A Test bench for generic algorithms in accelerator controls  

SciTech Connect

The operation of a complex accelerator system such as LEP or the future LHC at CERN demands automatic and standard controls to make it easy to use and reliable in all circumstances. A class of beam manipulations is the steering in the various machines and transfer channels. An algorithm has been devised to satisfy the required condition of genericity. It is based on a least squares method and yields a correction system which is not necessarily well conditioned in a usual operational environment where correctors and monitors may be either missing or redundant. The algorithm has been coded in Mathematica and implemented in the CERN PS control system. It is called through the MathLink protocol by an application program linked to standard beam position measurement software. With this technique, the development of the algorithm and its linkage to the control system are fully de-coupled. The application will become generic as soon as the magnetic and optical parameters will be loaded in data bases.

Autin, B.; Arruat, M.; Maio, F. di; Martini, M. [CERN, Geneva (Switzerland)

1994-12-31

306

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

307

Microwave power coupler for a superconducting multiple-cell cavity for accelerator application and its testing procedures  

SciTech Connect

Superconducting cavity resonators offer the advantage of high field intensity for a given input power, making them an attractive contender for particle accelerator applications. Power coupling into a superconducting cavity employed in a particle accelerator requires unique provisions to maintain high vacuum and cryogenic temperature on the cavity side, while operating with ambient conditions on the source side. Components introduced to fulfill mechanical requirements must show negligible obstruction of the propagation of the microwave with absence of critical locations that may give rise to electron multipaction, leading to a multiple section design, instead of an aperture, a probe, or a loop structure as found in conventional cavities. A coaxial power coupler for a superconducting multiple-cell cavity at 3.9 GHz has been developed. The cavity is intended to be employed as an accelerator to provide enhanced electron beam quality in a free-electron laser in Hamburg (FLASH) user facility. The design of the coupler called for two windows to sustain high vacuum in the cavity and two bellows to accommodate mechanical dimensional changes resulting from cryogenics. Suppression of multipacting was accomplished by the choice of conductor dimensions and materials with low second yield coefficients. Prior to integration with the cavity, the coupler was tested for intrinsic properties in a back-to-back configuration and conditioned for high-power operation with increasing power input. Maximum incident power was measured to be 61 kW. When integrated with the superconducting cavity, a loaded quality factor of 9 x 10{sup 5} was measured by transient method. Coupler return loss and insertion loss were estimated to be around -21 dB and -0.2 dB, respectively.

Li, Jianjian; /IIT, Chicago

2008-12-01

308

Evaluation of HVDC cables for the St. Lawrence crossing of Hydro-Quebec 500 kV DC Line. Part 1; Dielectric and accelerated aging tests on prototypes  

SciTech Connect

This paper describes the dielectric and accelerated aging tests on prototype {plus minus}500 kV dc oil-filled self-contained cables. The extensive test program was required to evaluate the High-Voltage cables for the St. Lawrence river crossing of the {plus minus}500 kV Quebec-New England HVDC power transmission system. The paper relates the main elements of the test program. It describes the required insulation levels, the characteristics of the cables supplied by three different manufacturers, as well as the cables' installation for the type tests and accelerated aging tests. Details of the test program and procedures followed to carry out the tests are given. Findings of the tests are also reported.

Coudere, D.; Trinh, N.G.; Belec, M.; Chaaban, M.; Leduc, J.; Beausejour, Y. (Inst. de Recherche d'Hydro-Quebec, Varennes, Quebec J3X 1S1 (CA))

1992-04-01

309

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

310

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

311

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

312

Performance of zinc phosphate coatings obtained by cathodic electrochemical treatment in accelerated corrosion tests  

Microsoft Academic Search

The formation of zinc phosphate coating by cathodic electrochemical treatment and evaluation of its corrosion resistance is addressed. The corrosion behaviour of cathodically phosphated mild steel substrate in 3.5% sodium chloride solution exhibits the stability of these coatings, which lasts for a week's time with no red rust formation. Salt spray test convincingly proves the white rust formation in the

S. Jegannathan; T. S. N. Sankara Narayanan; K. Ravichandran; S. Rajeswari

2005-01-01

313

High power breakdown testing of a photonic band-gap accelerator structure with elliptical rods  

E-print Network

An improved single-cell photonic band-gap (PBG) structure with an inner row of elliptical rods (PBG-E) was tested with high power at a 60 Hz repetition rate at X-band (11.424 GHz), achieving a gradient of 128??MV/m at a ...

Munroe, Brian James

314

Rapid estimation of lives of deficient superpave mixes and laboratory-based accelerated mix testing models  

Microsoft Academic Search

The engineers from the Kansas Department of Transportation (KDOT) often have to decide whether or not to accept non-conforming Superpave mixtures during construction. The first part of this study focused on estimating lives of deficient Superpave pavements incorporating nonconforming Superpave mixtures. These criteria were based on the Hamburg Wheel-Tracking Device (HWTD) test results and analysis. The second part of this

Chandra Bahadur Manandhar

2010-01-01

315

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

316

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

317

Architecture, implementation, and testing of a multiple-shell gas injection system for high current implosions on the Z accelerator  

NASA Astrophysics Data System (ADS)

Tests are ongoing to conduct ˜20 MA z-pinch implosions on the Z accelerator at Sandia National Laboratory using Ar, Kr, and D2 gas puffs as the imploding loads. The relatively high cost of operations on a machine of this scale imposes stringent requirements on the functionality, reliability, and safety of gas puff hardware. Here we describe the development of a prototype gas puff system including the multiple-shell nozzles, electromagnetic drivers for each nozzle's valve, a UV pre-ionizer, and an inductive isolator to isolate the ˜2.4 MV machine voltage pulse present at the gas load from the necessary electrical and fluid connections made to the puff system from outside the Z vacuum chamber. This paper shows how the assembly couples to the overall Z system and presents data taken to validate the functionality of the overall system.

Krishnan, Mahadevan; Elliott, Kristi Wilson; Madden, Robert E.; Coleman, P. L.; Thompson, John R.; Bixler, Alex; Lamppa, D. C.; McKenney, J. L.; Strizic, T.; Johnson, D.; Johns, O.; Vigil, M. P.; Jones, B.; Ampleford, D. J.; Savage, M. E.; Cuneo, M. E.; Jones, M. C.

2013-06-01

318

Architecture, implementation, and testing of a multiple-shell gas injection system for high current implosions on the Z accelerator.  

PubMed

Tests are ongoing to conduct ~20 MA z-pinch implosions on the Z accelerator at Sandia National Laboratory using Ar, Kr, and D2 gas puffs as the imploding loads. The relatively high cost of operations on a machine of this scale imposes stringent requirements on the functionality, reliability, and safety of gas puff hardware. Here we describe the development of a prototype gas puff system including the multiple-shell nozzles, electromagnetic drivers for each nozzle's valve, a UV pre-ionizer, and an inductive isolator to isolate the ~2.4 MV machine voltage pulse present at the gas load from the necessary electrical and fluid connections made to the puff system from outside the Z vacuum chamber. This paper shows how the assembly couples to the overall Z system and presents data taken to validate the functionality of the overall system. PMID:23822342

Krishnan, Mahadevan; Elliott, Kristi Wilson; Madden, Robert E; Coleman, P L; Thompson, John R; Bixler, Alex; Lamppa, D C; McKenney, J L; Strizic, T; Johnson, D; Johns, O; Vigil, M P; Jones, B; Ampleford, D J; Savage, M E; Cuneo, M E; Jones, M C

2013-06-01

319

Surface composition and barium evaporation rate of ``pedigreed'' impregnated tungsten dispenser cathodes during accelerated life testing  

NASA Astrophysics Data System (ADS)

A study has been made of the surface composition and barium evaporation rate of "pedigreed" impregnated tungsten dispenser cathodes. The effect of air exposure on coated cathodes was examined and was found to have no significant effect on barium evaporation rate although in some cases longer reactivation times were required. No changes in surface topography were apparent following air exposure and reactivation. Life testing was done at 100°C above the typical operating temperature for the cathode, where the typical operating temperature was taken to be 950°C for coated cathodes and 1050°C for uncoated cathodes. The cathodes were examined at different stages of life testing, up to 1200 h. Significant decreases in barium evaporation rates were found after as few as 500 h of life testing. After 1000 h the evaporation rate had decreased more than an order of magnitude. Changes in surface composition were also found. The effects of tungsten particle size, used in manufacture of the billet, on barium evaporation rate were also studied but no correlation was found.

Tomich, D. H.; Mescher, J. A.; Grant, J. T.

1987-03-01

320

Evaluation of the reliability of commercial concentrator triple-junction solar cells by means of accelerated life tests (ALT)  

NASA Astrophysics Data System (ADS)

A temperature accelerated life test on commercial concentrator lattice-matched GaInP/GaInAs/Ge triple-junction solar cells has been carried out. The solar cells have been tested at three different temperatures: 119, 126 and 164 °C and the nominal photo-current condition (820 X) has been emulated by injecting current in darkness. All the solar cells have presented catastrophic failures. The failure distributions at the three tested temperatures have been fitted to an Arrhenius-Weibull model. An Arrhenius activation energy of 1.58 eV was determined from the fit. The main reliability functions and parameters (reliability function, instantaneous failure rate, mean time to failure, warranty time) of these solar cells at the nominal working temperature (80 °C) have been obtained. The warranty time obtained for a failure population of 5 % has been 69 years. Thus, a long-term warranty could be offered for these particular solar cells working at 820 X, 8 hours per day at 80 °C.

Espinet-González, Pilar; Algora, Carlos; Núñez, Neftalí; Orlando, Vincenzo; Vázquez, Manuel; Bautista, Jesús; Araki, Kenji

2013-09-01

321

Search for major genes with progeny test data to accelerate the development of genetically superior loblolly pine  

SciTech Connect

This research project is to develop a novel approach that fully utilized the current breeding materials and genetic test information available from the NCSU-Industry Cooperative Tree Improvement Program to identify major genes that are segregating for growth and disease resistance in loblolly pine. If major genes can be identified in the existing breeding population, they can be utilized directly in the conventional loblolly pine breeding program. With the putative genotypes of parents identified, tree breeders can make effective decisions on management of breeding populations and operational deployment of genetically superior trees. Forest productivity will be significantly enhanced if genetically superior genotypes with major genes for economically important traits could be deployed in an operational plantation program. The overall objective of the project is to develop genetic model and analytical methods for major gene detection with progeny test data and accelerate the development of genetically superior loblolly pine. Specifically, there are three main tasks: (1) Develop genetic models for major gene detection and implement statistical methods and develop computer software for screening progeny test data; (2) Confirm major gene segregation with molecular markers; and (3) Develop strategies for using major genes for tree breeding.

NCSU

2003-12-30

322

Cell Component Accelerated Stress Test and Polarization Curve Protocols for Polymer Electrolyte Membrane Fuel Cells  

NSDL National Science Digital Library

This document contains test protocols to determine the performance and durability of fuel cell components such as electrocatalysts and supports, membranes, and membrane electrode assemblies (MEAs). These protocols were established with the intent to be used as a common industry standard when assessing durability of different polymer electrolyte membranes (PEM) in fuel cells for automotive applications and to be compared against DOE and FreedomCar targets. The resulting data may also help to model the performance of the fuel cell under variable load conditions and the effects of ageing on performance.

United States Driving Research and Innovation for Vehicle Efficiency and Energy Sustainability (USDRIVE)

323

Accelerator-based tests of radiation shielding properties of materials used in human space infrastructures.  

PubMed

Shielding is the only practical countermeasure for the exposure to cosmic radiation during space travel. It is well known that light, hydrogenated materials, such as water and polyethylene, provide the best shielding against space radiation. Kevlar and Nextel are two materials of great interest for spacecraft shielding because of their known ability to protect human space infrastructures from meteoroids and debris. We measured the response to simulated heavy-ion cosmic radiation of these shielding materials and compared it to polyethylene, Lucite (PMMA), and aluminum. As proxy to galactic nuclei we used 1 GeV n iron or titanium ions. Both physics and biology tests were performed. The results show that Kevlar, which is rich in carbon atoms (about 50% in number), is an excellent space radiation shielding material. Physics tests show that its effectiveness is close (80-90%) to that of polyethylene, and biology data suggest that it can reduce the chromosomal damage more efficiently than PMMA. Nextel is less efficient as a radiation shield, and the expected reduction on dose is roughly half that provided by the same mass of polyethylene. Both Kevlar and Nextel are more effective than aluminum in the attenuation of heavy-ion dose. PMID:18301097

Lobascio, C; Briccarello, M; Destefanis, R; Faraud, M; Gialanella, G; Grossi, G; Guarnieri, V; Manti, L; Pugliese, M; Rusek, A; Scampoli, P; Durante, M

2008-03-01

324

A reconnaissance assessment of probabilistic earthquake accelerations at the Nevada Test Site  

SciTech Connect

We have made two interim assessments of the probabilistic ground-motion hazard for the potential nuclear-waste disposal facility at the Nevada Test Site (NTS). The first assessment used historical seismicity and generalized source zones and source faults in the immediate vicinity of the facility. This model produced relatively high probabilistic ground motions, comparable to the higher of two earlier estimates, which was obtained by averaging seismicity in a 400-km-radius circle around the site. The high ground-motion values appear to be caused in part by nuclear-explosion aftershocks remaining in the catalog even after the explosions themselves have been removed. The second assessment used particularized source zones and source faults in a region substantially larger than NTS to provide a broad context of probabilistic ground motion estimates at other locations of the study region. Source faults are mapped or inferred faults having lengths of 5 km or more. Source zones are defined by boundaries separating fault groups on the basis of direction and density. For this assessment, earthquake recurrence has been estimated primarily from historic seismicity prior to nuclear testing. Long-term recurrence for large-magnitude events is constrained by geological estimates of recurrence in a regime in which the large-magnitude earthquakes would occur with predominately normal mechanisms. 4 refs., 10 figs.

Perkins, D.M.; Thenhaus, P.C.; Hanson, S.L.; Algermissen, S.T.

1986-01-01

325

First Beam Waist Measurements in the Final Focus Beam Line at the KEK Accelerator Test Facility  

SciTech Connect

The ATF2 project is the final focus system prototype for the ILC and CLIC linear collider projects, with a purpose to reach a 37 nm vertical beam size at the interaction point using compact optics based on a novel scheme of local chromaticity correction. Construction of all components and installation were completed at the end of 2008. An initial commissioning phase followed in 2009, using larger than nominal {beta} functions at the interaction point, corresponding to reduced demagnification factors in comparison to the design, to limit effects from higher-order optical aberrations and hence simplify beam tuning procedures while key instrumentation was being tested and calibrated. In this paper, first measurements of dispersion and Twiss parameters are presented based on scanning the beam during this period with a set of tungsten wires located just behind the interaction point, using two complementary analysis methods.

Bai, Sha; /Beijing, Inst. High Energy Phys.; Aryshev, Alexander; /KEK, Tsukuba; Bambade, Philip; /KEK, Tsukuba /Orsay, IPN; McCormick, Doug; /SLAC; Bolzon, Benoit; /Annecy, LAPP; Gao, Jie; /Beijing, Inst. High Energy Phys.; Tauchi, Toshiaki; /KEK, Tsukuba; Zhou, Feng; /SLAC

2012-06-22

326

Methods for Accelerating the Fluorescent-Antibody Test for Rabies Diagnosis 1  

PubMed Central

The time required to perform the fluorescent-antibody test for rabies was reduced by eliminating acetone fixation of the brain impressions and by incubating the conjugate-impression reaction at room temperature for only 10 min. Elimination of the preliminary acetone fixation had no effect on the diagnosis of impression smears from 246 mammalian brains by immunofluorescence. Staining at 37 C for 30 min and staining at room temperature for 10 min were found to be equally effective in the examination of impression smears from 161 brain samples. The procedure, as modified, shortens the time required for the diagnosis of rabies by immunofluorescence from about 5.5 hr to approximately 45 min. PMID:4995847

Larghi, Oscar P.; Ch, Edwin Jimenez

1971-01-01

327

Ion sources for accelerators  

NASA Astrophysics Data System (ADS)

A survey of different types of ion sources used for accelerator applications is given. Typical problems like the source life time, or the special need for technical solutions for specific elements will demonstrate the advantage of each type of ion source. In any case reliability is a main topic. Besides the plasma generation of the desired element, beam formation and beam transport to the accelerator are discussed. The influence of space charge on the beam transport can be of great importance if there is no space-charge compensation. Typical results achieved at GSI will be given for the following source types: Penning Ion Source (PIG), Electron Cyclotron Resonance (ECR), Cold or Hot Reflex Discharge Ion Source (CHORDIS), Multicusp Ion Source (MUCIS) and MEVVA.

Spädtke, P.; Bossler, J.; Emig, H.; Leible, K. D.; Mühle, C.; Schulte, H.; Tinschert, K.

1998-04-01

328

COLLISIONLESS SHOCKS IN A PARTIALLY IONIZED MEDIUM. I. NEUTRAL RETURN FLUX AND ITS EFFECTS ON ACCELERATION OF TEST PARTICLES  

SciTech Connect

A collisionless shock may be strongly modified by the presence of neutral atoms through the processes of charge exchange between ions and neutrals and ionization of the latter. These two processes lead to exchange of energy and momentum between charged and neutral particles both upstream and downstream of the shock. In particular, neutrals that suffer a charge exchange downstream with shock-heated ions generate high-velocity neutrals that have a finite probability of returning upstream. These neutrals might then deposit heat in the upstream plasma through ionization and charge exchange, thereby reducing the fluid Mach number. A consequence of this phenomenon, which we refer to as the neutral return flux, is a reduction of the shock compression factor and the formation of a shock precursor upstream. The scale length of the precursor is determined by the ionization and charge-exchange interaction lengths of fast neutrals moving toward upstream infinity. In the case of a shock propagating in the interstellar medium, the effects of ion-neutral interactions are especially important for shock velocities <3000 km s{sup -1}. Such propagation velocities are common among shocks associated with supernova remnants, the primary candidate sources for the acceleration of Galactic cosmic rays. We then investigate the effects of the return flux of neutrals on the spectrum of test particles accelerated at the shock. We find that, for shocks slower than {approx}3000 km s{sup -1}, the particle energy spectrum steepens appreciably with respect to the naive expectation for a strong shock, namely, {proportional_to}E{sup -2}.

Blasi, P.; Morlino, G.; Bandiera, R.; Amato, E. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, I-50125 Firenze (Italy); Caprioli, D. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08540 (United States)

2012-08-20

329

Freeze-dried snake antivenoms formulated with sorbitol, sucrose or mannitol: Comparison of their stability in an accelerated test.  

PubMed

Freeze-drying is used to improve the long term stability of pharmaceutical proteins. Sugars and polyols have been successfully used in the stabilization of proteins. However, their use in the development of freeze-dried antivenoms has not been documented. In this work, whole IgG snake antivenom, purified from equine plasma, was formulated with different concentrations of sorbitol, sucrose or mannitol. The glass transition temperatures of frozen formulations, determined by Differential Scanning Calorimetry (DSC), ranged between -13.5 °C and -41 °C. In order to evaluate the effectiveness of the different stabilizers, the freeze-dried samples were subjected to an accelerated stability test at 40 ± 2 °C and 75 ± 5% relative humidity. After six months of storage at 40 °C, all the formulations presented the same residual humidity, but significant differences were observed in turbidity, reconstitution time and electrophoretic pattern. Moreover, all formulations, except antivenoms freeze-dried with mannitol, exhibited the same potency for the neutralization of lethal effect of Bothrops asper venom. The 5% (w:v) sucrose formulation exhibited the best stability among the samples tested, while mannitol and sorbitol formulations turned brown. These results suggest that sucrose is a better stabilizer than mannitol and sorbitol in the formulation of freeze-dried antivenoms under the studied conditions. PMID:25091348

Herrera, María; Tattini, Virgilio; Pitombo, Ronaldo N M; Gutiérrez, José María; Borgognoni, Camila; Vega-Baudrit, José; Solera, Federico; Cerdas, Maykel; Segura, Alvaro; Villalta, Mauren; Vargas, Mariángela; León, Guillermo

2014-11-01

330

The impact of self-healing on the life-time of materials  

NASA Astrophysics Data System (ADS)

Structural materials that are attributed with the (new) property of ``self-healing'' will obviously lead to safer, longer lasting and more reliable structures. The property of ``self-healing'' can be defined as the ability of a material to mitigate autonomously early stages of damage such as micro cracks, and many examples of materials with this properties have been reported in recent years [1]. In this contribution we investigate the effect of healing on the expected service life time of a model material. We apply a statistical mechanics' inspired computational approach to model the process of damage accumulation and on-site healing of a material under well defined loading conditions. We define a material as being at the end of its service life when a percolative path of damaged cells has passed a prescribed length. The variation of service life for various scenarios, such as healing times and distribution of healing centers is investigated. Finally we show how this type of models may be useful for the design of optimized self healing materials. [3pt] [1] S. van der Zwaag (editor), (2007). Self Healing Materials: An Alternative Approach to 20 Centuries of Materials Science. Springer Netherlands.

Gaddy, John; Montfrooij, Wouter; Schmets, Alexander

2009-03-01

331

Kenneth J. Turner. Formally-Based Testing of Radiotherapy Accelerators. In Robert N. Procter and Mark Rouncefield, editors, Proc. Dependability in  

E-print Network

. A number of radiation accidents due to software failures have been well docu- mented (e.g. [14, 15 investigation of conformance testing with a practical application to the safety of radiotherapy equipment. Clearly its correct design and operation are safety-critical. Modern accelerators are entirely dependent

Turner, Ken

332

Reliability improvement of InGaN LED backlight module by accelerated life test (ALT) and screen policy of potential leakage LED  

Microsoft Academic Search

In this paper, to improve the reliability of InGaN white LED Backlight module, we have analyzed the module level accelerated life test (ALT) for LED which is used for the front display in the refrigerator. In addition, we have suggested a screen method that enables to screen out LEDs which have potential leakage problems. The stress factors and levels were

Jae-Seong Jeong; Jin-Kyu Jung; Sang-Deuk Park

2008-01-01

333

Experimental Testing of the Gigabit IPSec-Compliant Implementations of Rijndael and Triple DES Using SLAAC-1V FPGA Accelerator Board  

Microsoft Academic Search

In this paper, we present the results of the first phase of a project aimed at implementing a full suite of IPSec cryptographic transformations in reconfigurable hardware. Full implementations of the new Advanced Encryption Standard, Rijndael, and the older American federal standard, Triple DES, were developed and experimentally tested using the SLAAC-1V FPGA accelerator board, based on Xilinx Virtex 1000

Pawel Chodowiec; Kris Gaj; Peter Bellows; Brian Schott

2001-01-01

334

Linear Accelerators  

NASA Astrophysics Data System (ADS)

In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

Sidorin, Anatoly

2010-01-01

335

Beam life time studies and design optimization of the Ultra-low energy Storage Ring  

NASA Astrophysics Data System (ADS)

The Ultra-low energy electrostatic Storage Ring (USR) at the future Facility for Low-energy Antiproton and Ion Research (FLAIR) will provide cooled beams of antiprotons in the energy range between 300 keV down to 20 keV. Based on the original design concept developed in 2005, the USR has been completely redesigned over the past few years by the QUASAR Group. The ring structure is now based on a 'split achromat' lattice. This ensures compact ring dimensions of 10 m × 10 m, whilst allowing both, in-ring experiments with gas jet targets and studies with extracted beams. In the USR, a wide range of beam parameters shall be provided, ranging from very short pulses in the nanosecond regime to a coasting beam. In addition, a combined fast and slow extraction scheme will be featured that allows for providing external experiments with cooled beams of different time structure. Detailed investigations into the dynamics of low energy beams, including studies into the long term beam dynamics and ion kinetics, beam life time, equilibrium momentum spread and equilibrium lateral spread during collisions with an internal target were carried out. This required the development of new simulation tools to further the understanding of beam storage with electrostatic fields. In addition, studies into beam diagnostics methods for the monitoring of ultra-low energy ions at beam intensities less than 10 6 were carried out. This includes instrumentation for the early commissioning of the machine, as well as for later operation with antiprotons. In this paper, on overview of the technical design of the USR is given with emphasis on two of the most important operating modes, long term beam dynamics and the design of the beam diagnostics system.

Welsch, C. P.; Papash, A. I.; Harasimowicz, J.; Karamyshev, O.; Karamysheva, G. A.; Newton, D.; Panniello, M.; Putignano, M.; Siggel-King, M. R. F.; Smirnov, A.

2014-04-01

336

Laser accelerators  

NASA Astrophysics Data System (ADS)

Laser accelerators are characterized, by their mode of operation, into media, far field, and near field accelerators. The first category, media accelerators, include the inverse Cherenkov effect accelerator, the plasma focus accelerator, and the beat wave accelerator (BWA). The second category, far field accelerators, include the two wave device and the inverse free electron accelerator (IFEI). The third category, near field accelerators, includes conventional linac scaled to small dimensions, dielectric sheets, small holes in dielectric cylinders, and gratings. An example from each category is given; namely: (1) the BWA; (2) the IFEL; and (3) the linac scaled to small dimensions and powered by a free electron laser (FEL). Grating accelerators are also discussed.

Sessler, A.

1983-04-01

337

Ability in disability: J. M. Coetzee's Life & Times of Michael K and the empowerment of the disabled  

Microsoft Academic Search

This article argues that J. M. Coetzee's works assume the dignity and central position of the disabled in the universe. It operates, in the main, from the template provided by one of Coetzee's novels in which a disabled character appears centrally and is even the eponymous hero. The Life & Times of Michael K (1983. London: Penguin) is read as

Ayobami Kehinde

2010-01-01

338

A novel angular acceleration sensor based on the electromagnetic induction principle and investigation of its calibration tests.  

PubMed

An angular acceleration sensor can be used for the dynamic analysis of human and joint motions. In this paper, an angular acceleration sensor with novel structure based on the principle of electromagnetic induction is designed. The method involves the construction of a constant magnetic field by the excitation windings of sensor, and the cup-shaped rotor that cut the magnetic field. The output windings of the sensor generate an electromotive force, which is directly proportional to the angular acceleration through the electromagnetic coupling when the rotor has rotational angular acceleration. The mechanical structure and the magnetic working circuit of the sensor are described. The output properties and the mathematical model including the transfer function and state-space model of the sensor are established. The asymptotical stability of the sensor when it is working is verified by the Lyapunov Theorem. An angular acceleration calibration device based on the torsional pendulum principle is designed. The method involves the coaxial connection of the angular acceleration sensor, torsion pendulum and a high-precision angle sensor, and then an initial external force is applied to the torsion pendulum to produce a periodic damping angle oscillation. The angular acceleration sensor and the angle sensor will generate two corresponding electrical signals. The sensitivity coefficient of the angular acceleration sensor can be obtained after processing these two-channel signals. The experiment results show that the sensitivity coefficient of the sensor is about 17.29 mv/Krad·s2. Finally, the errors existing in the practical applications of the sensor are discussed and the corresponding improvement measures are proposed to provide effective technical support for the practical promotion of the novel sensor. PMID:23941911

Zhao, Hao; Feng, Hao

2013-01-01

339

Dynamic mechanical and molecular weight measurements on polymer bonded explosives from thermally accelerated aging tests. I. Fluoropolymer binders  

SciTech Connect

The dynamic mechanical properties and molecular weight distribution of two polymer bonded explosives, LX-10-1 and PBX-9502, maintained at 23, 60, and 74/sup 0/C for 3 years were studied. LX-10-1 is 94.5% 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane explosive bonded together with 5.5% Viton A fluoropolymer. PBX-9502 is 95% triaminotrinitrobenzene explosive bonded with 5% Kel-F-800 fluoropolymer. There are two mechanical relaxations in the LX-10-1 in the military temperature range. The relaxation at -10/sup 0/C is associated with the glass transition temperature of the Viton A binder. A second weak relaxation occurs at about 30/sup 0/C in all LX-10-1 samples tested. This relaxation is probably associated with small amounts of crystallinity in the binder although this has not been demonstrated. There is a slight increase in modulus of the LX-10-1 with accelerated aging temperature. Changes in the dynamic mechanical properties of PBX-9502 are ascribed to crystallization of the chlorotrifluoroethylene component of the Kel-F-800 binder. The molecular weight of the Viton A binder decreased slight with increasing aging temperature. Using the kinetics of random scission the activation energy for polymer degradation in the presence of the explosive was 1.19 kcal/mole. The Arrhenius preexponential term and activation energy predict an expected use-life in excess of 60 years for LX-10-1. The Kel-F-800 in PBX-9502 is also extremely stable.

Hoffman, D.M.; Caley, L.E.

1981-01-01

340

Use of the TACL (Thaumaturgic Automated Control Logic) system at CEBAF (Continuous Electron Beam Accelerator Facility) for control of the Cryogenic Test Facility  

SciTech Connect

A logic-based control software system, called Thaumaturgic Automated Control Logic (TACL), is under development at the Continuous Electron Beam Accelerator Facility in Newport News, VA. The first version of the software was placed in service in November, 1987 for control of cryogenics during the first superconducting RF cavity tests at CEBAF. In August, 1988 the control system was installed at the Cryogenic Test Facility (CTF) at CEBAF. CTF generated liquid helium in September, 1988 and is now in full operation for the current round of cavity tests. TACL is providing a powerful and flexible controls environment for the operation of CTF. 3 refs.

Navarro, E.; Keesee, M.; Bork, R.; Grubb, C.; Lahti, G.; Sage, J.

1989-01-01

341

Can Accelerators Accelerate Learning?  

SciTech Connect

The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ)[1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil, Caixa Postal 68528, 21941-972 (Brazil)

2009-03-10

342

The Accelerated Weathering of a Radioactive Low-Activity Waste Glass Under Hydraulically Unsaturated Conditions: Experimental Results from a Pressurized Unsaturated Flow Test  

SciTech Connect

To predict the long-term fate of low- and high-level waste forms in the subsurface over geologic time scales, it is important to understand how the formation of an alteration phase or phases will affect radionuclide release from the corroding waste forms under repository-relevant conditions. To generate data to conduct performance assessment calculations for the low-activity waste (LAW) integrated disposal facility at the Hanford site in southeastern Washington state, accelerated weathering experiments are being conducted with the pressurized unsaturated flow (PUF) test method to evaluate the long-term release of radionuclides from immobilized low-activity waste (ILAW) glasses. The radionuclide release rate is a key parameter affecting the overall performance of the LAW disposal facility. Currently, there are three other accelerated weathering test methods being used to evaluate the long-term durability of glasses: product consistency test, vapor hydration test, and unsaturated drip test. In contrast to these test methods, PUF test mimic the near-field vadose zone environment, allow the corroding waste form to achieve its final reaction state, and accelerate the hydrolysis and aging processes by as much as 50 times over conventional static tests run at the same temperature. In this paper, we discuss the results of an accelerated weathering experiment conducted with the PUF apparatus to evaluate the corrosion rate of an ILAW glass, LAWAN102, made with actual Hanford waste taken from Tank 241-AN-102 (U). Results from this PUF test with LAWAN102 glass showed that after one and a half years of testing, the corrosion rate, based on B release, reached a steady-state release of 0.010 ±0.003 g m-2 d-1, which is approximately eight times lower than the HLP glass series previously tested. These results indicate that LAWAN102 glass performs well and is a durable ILAW glass. These results also highlight the importance of being able to predict, with some level of certainty, the alteration phase or phases that will form under repository-relevant conditions.

Pierce, Eric M.; McGrail, B. Peter; Valenta, Michelle M.; Strachan, Denis M.

2006-08-01

343

Structural Benchmark Testing for Stirling Convertor Heater Heads  

NASA Technical Reports Server (NTRS)

The National Aeronautics and Space Administration (NASA) has identified high efficiency Stirling technology for potential use on long duration Space Science missions such as Mars rovers, deep space missions, and lunar applications. For the long life times required, a structurally significant design limit for the Stirling convertor heater head is creep deformation induced even under relatively low stress levels at high material temperatures. Conventional investigations of creep behavior adequately rely on experimental results from uniaxial creep specimens, and much creep data is available for the proposed Inconel-718 (IN-718) and MarM-247 nickel-based superalloy materials of construction. However, very little experimental creep information is available that directly applies to the atypical thin walls, the specific microstructures, and the low stress levels. In addition, the geometry and loading conditions apply multiaxial stress states on the heater head components, far from the conditions of uniaxial testing. For these reasons, experimental benchmark testing is underway to aid in accurately assessing the durability of Stirling heater heads. The investigation supplements uniaxial creep testing with pneumatic testing of heater head test articles at elevated temperatures and with stress levels ranging from one to seven times design stresses. This paper presents experimental methods, results, post-test microstructural analyses, and conclusions for both accelerated and non-accelerated tests. The Stirling projects use the results to calibrate deterministic and probabilistic analytical creep models of the heater heads to predict their life times.

Krause, David L.; Kalluri, Sreeramesh; Bowman, Randy R.

2007-01-01

344

Long-term reliability of SiSi0.7Ge0.3Si HBTs from accelerated lifetime testing  

Microsoft Academic Search

Accelerated lifetime tests were performed on double-mesa structure Si-Si0.7Ge0.3-Si npn heterojunction bipolar transistors, grown by molecular beam epitaxy, in the temperature range of 175°C-275°C. The transistors (with 5×20 ?m2 emitter area) have DC current gains ~40-50 and fT and fmax of up to 22 GHz and 25 GHz, respectively. It is found that a gradual degradation in these devices is

Zhengqiang Ma; Jae-Sung Rieh; Pallab Bhattacharya; Samuel A. Alterovitz; George E. Ponchak; Edward T. Croke

2001-01-01

345

Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint  

SciTech Connect

A step-stress accelerated degradation testing (SSADT) method was employed for the first time to evaluate the stability of CuInGaSe2 (CIGS) solar cells and device component materials in four Al-framed test structures encapsulated with an edge sealant and three kinds of backsheet or moisture barrier film for moisture ingress control. The SSADT exposure used a 15oC and then a 15% relative humidity (RH) increment step, beginning from 40oC/40%RH (T/RH = 40/40) to 85oC/70%RH (85/70) as of the moment. The voluminous data acquired and processed as of total DH = 3956 h with 85/70 = 704 h produced the following results. The best CIGS solar cells in sample Set-1 with a moisture-permeable TPT backsheet showed essentially identical I-V degradation trend regardless of the Al-doped ZnO (AZO) layer thickness ranging from standard 0.12 ?m to 0.50 ?m on the cells. No clear 'stepwise' feature in the I-V parameter degradation curves corresponding to the SSADT T/RH/time profile was observed. Irregularity in I-V performance degradation pattern was observed with some cells showing early degradation at low T/RH < 55/55 and some showing large Voc, FF, and efficiency degradation due to increased series Rs (ohm-cm2) at T/RH ? 70/70. Results of (electrochemical) impedance spectroscopy (ECIS) analysis indicate degradation of the CIGS solar cells corresponded to increased series resistance Rs (ohm) and degraded parallel (minority carrier diffusion/recombination) resistance Rp, capacitance C, overall time constant Rp*C, and 'capacitor quality' factor (CPE-P), which were related to the cells? p-n junction properties. Heating at 85/70 appeared to benefit the CIGS solar cells as indicated by the largely recovered CPE-P factor. Device component materials, Mo on soda lime glass (Mo/SLG), bilayer ZnO (BZO), AlNi grid contact, and CdS/CIGS/Mo/SLG in test structures with TPT showed notable to significant degradation at T/RH ? 70/70. At T/RH = 85/70, substantial blistering of BZO layers on CIGS cell pieces was observed that was not seen on BZO/glass, and a CdS/CIGS sample displayed a small darkening and then flaking feature. Additionally, standard AlNi grid contact was less stable than thin Ni grid contact at T/RH ? 70/70. The edge sealant and moisture-blocking films were effective to block moisture ingress, as evidenced by the good stability of most CIGS solar cells and device components at T/RH = 85/70 for 704 h, and by preservation of the initial blue color on the RH indicator strips. The SSADT experiment is ongoing to be completed at T/RH = 85/85.

Pern, F. J.; Noufi, R.

2012-10-01

346

Angular velocities, angular accelerations, and coriolis accelerations  

NASA Technical Reports Server (NTRS)

Weightlessness, rotating environment, and mathematical analysis of Coriolis acceleration is described for man's biological effective force environments. Effects on the vestibular system are summarized, including the end organs, functional neurology, and input-output relations. Ground-based studies in preparation for space missions are examined, including functional tests, provocative tests, adaptive capacity tests, simulation studies, and antimotion sickness.

Graybiel, A.

1975-01-01

347

An accelerating section with a constant acceleration rate  

SciTech Connect

An accelerating section with varying cross section and 2..pi../3 working oscillation phase has been designed, built, and tested. The experimental results at low powers and in the acceleration mode are in satisfactory agreement with calculated results.

Zykov, A.I.; Kondratenko, V.V.; Kramskoi, G.D.; Mondrus, I.N.; Ryabtsov, A.V.; Smirnov, V.L.; Terekhov, B.A.; Chikatash, I.A.

1982-11-01

348

Correlations of Capacitance-Voltage Hysteresis with Thin-Film CdTe Solar Cell Performance During Accelerated Lifetime Testing  

SciTech Connect

In this paper we present the correlation of CdTe solar cell performance with capacitance-voltage hysteresis, defined presently as the difference in capacitance measured at zero-volt bias when collecting such data with different pre-measurement bias conditions. These correlations were obtained on CdTe cells stressed under conditions of 1-sun illumination, open-circuit bias, and an acceleration temperature of approximately 100 degrees C.

Albin, D.; del Cueto, J.

2011-03-01

349

Android Acceleration  

NSDL National Science Digital Library

Students prepare for the associated activity in which they investigate acceleration by collecting acceleration vs. time data using the accelerometer of a sliding Android device. Based on the experimental set-up for the activity, students form hypotheses about the acceleration of the device. Students will investigate how the force on the device changes according to Newton's Second Law. Different types of acceleration, including average, instantaneous and constant acceleration, are introduced. Acceleration and force is described mathematically and in terms of processes and applications.

IMPART RET Program, College of Information Science & Technology,

350

Wake fields in HCS accelerator and CTS power line of the CLIC Test Facility (CTF II) simulation with program wake  

E-print Network

One of the two parallel beam lines of the CTF II, (the 'Drive Beam') is providing the other (the accelerator) with 30 GHz power. Experimentation was performed in 98 and later with a CTF layout to study acceleration of a train of bunches with beam loading compensation, bunch length compression and 30 GHz conversion of the Drive Beam power [1]. This conversion is limited by the difficulty of transmitting the beam through the structures extracting the beam power (CTS). A large transverse wake loss factor is associated with the necessary high longitudinal wake loss factor in CTS. Therefore the limitation of transmission should come mainly from transverse wakes in CTS. Dynamics in HCS and in the bunch compression device was studied with codes GPT [2] and PARMELA [3], [4] using beam parameters input derived from calculations of the beam in the RF gun with code MAFIA. Code WAKE is used to verify that the influence of the wake-fields in HCS is small, to follow the beam along the 4 CTS of the drive linac, and to give ...

Riche, A

2000-01-01

351

Accelerator applications of engineered media  

NASA Astrophysics Data System (ADS)

Material properties are vital for the field of accelerator R&D. Euclid Techlabs in collaboration with the Argonne Wakefield Accelerator facility team has investigated accelerator applications of metamaterials, photonic band gap structures, nonlinear, paramagnetic and ferroelectric materials. In this paper we will present results of our work on advanced accelerating structures and accelerating applications of engineered materials. These will include wakefield test of a photonic band gap accelerating structure, design of a dielectric loaded structure with built in tunable paramagnetic absorption mechanism and beam diagnostics applications of metamaterials.

Antipov, Sergey

2010-11-01

352

Heavy Ion Accelerator (UTI-2).  

National Technical Information Service (NTIS)

The design and test results of the 2 MeV ion accelerator designed for science of materials are described. The UTI-2 accelerator is developed on the basis of the UTI-1 accelerator and equipped with an injector of five-charge ions of iron, chromium and othe...

V. V. Bezuglyj, M. Y. Bredikhin, B. Il'enko I. M. Nekludov, V. K. Knorenko

1986-01-01

353

Yield Learning and Process Optimization on 65-nm CMOS Technology Accelerated by the Use of Short Flow Test Die  

Microsoft Academic Search

Short loop test flows have been commonly used in back-end-of-line (BEOL) interconnect process development to speed up learning rates and improve yields. This paper presents case studies on the expanded use of short loop test chips to the shallow trench isolation and gate and premetal dielectric\\/contact loops of a 65-nm process technology in addition to the BEOL. These test chips

Jeffrey R. D. DeBord; Nagarajan Sridhar

2007-01-01

354

Shortening of life-time of the pair [P680+Pheo-] contributes to general inhibitory effect of dinoseb on electron transfer in PS-II.  

PubMed

It is shown that dinoseb, added to subchloroplast photosystem-II (PS-II) preparations from pea at a concentration higher than 5 microM, along with blocking the electron transfer on the acceptor side of PS-II, induces the following effects revealing its capability to have redox interaction with the components of PS-II reaction center (RC)-pheophytin (Pheo) and chlorophyll P680: (1) acceleration of the dark relaxation of absorbance (delta A) and chlorophyll fluorescence (delta F) changes related to photoreduction of Pheo as a result of the photoreaction [P680Pheo] [symbol: see text] [P680Pheo-] that leads to elimination of the delta A and delta F at a concentration of the inhibitor higher than 50 microM; (2) lowering of the maximum level of fluorescence (F) due to a decrease of delta F under the condition when the electron acceptor, QA, is reduced; (3) loss of the described effects of dinoseb and appearance of its capability to donate electron to RC of PS-II in the presence of dithionite which reduces dinoseb in the dark; (4) inhibition of delta A related to photooxidation of P680; (5) activation of delta A related to photooxidation P700 in photosystem-I (PS-I) preparations (a similar effect is observed upon the addition of 0.2 mM methylviologen). It is suggested that redox interaction with the pair [P680+Pheo-] leading to the shortening of its life-time contributes to the general effect of inhibition of electron transfer in PS-II by dinoseb. PMID:11355638

Vyacheslav, K; Suleyman, A; Serguei, Z

2000-12-01

355

Influence of Lentinus edodes and Agaricus blazei extracts on the prevention of oxidation and retention of tocopherols in soybean oil in an accelerated storage test.  

PubMed

This study aimed to evaluate the influence of the methanol extracts of mushrooms Lentinus edodes and Agaricus blazei on the retention of tocopherols in soybean oil, when subjected to an accelerated storage test. The following treatments were subjected to an accelerated storage test in an oven at 60 °C for 15 days: Control (soybean oil without antioxidants), TBHQ (soybean oil?+?100 mg/kg of TBHQ), BHT (soybean oil?+?100 mg/kg of BHT), L. edodes (soybean oil?+?3,500 mg/kg of L. edodes extract) and A. blazei (soybean oil?+?3,500 mg/kg of A. blazei extract). The samples were analyzed for tocopherols naturally present in soybean oil and mass gain. The results showed, the time required to reach a 0.5% increase in mass was 13 days for TBHQ and 15 days for A. blazei. The content of tocopherols for TBHQ was 457.50 mg/kg and the A. blazei, 477.20 mg/kg. PMID:24876658

da Silva, Ana Carolina; Jorge, Neuza

2014-06-01

356

Thermal reliability analysis of a BLDC motor in a high-speed axial fan by the accelerated-life test and numerical methods  

NASA Astrophysics Data System (ADS)

The thermal reliability of a closed-type BLDC motor for a high-speed fan is analyzed by an accelerated-life testing and numerical methods in this paper. Since a module and a motor part are integrated in a closed case, heat generated from a rotor in a motor and electronic components in the PCB module cannot be effectively removed to the outside. Therefore, the module will easily fail due to high temperature. The experiment for measuring the temperature and the surface heat flux of the electronic components is carried out to predict their surface temperature distributions and main heat sources. The accelerated-life test is accomplished to formulate the life equation depending on the environmental temperature. Moreover, the temperature of the PCB module is different from the environmental temperature since the heat generated from the motor cannot be effectively dissipated owing to the motor’s structure. Therefore a numerical method is used to predict the temperature of the PCB module, which is one of the life equation parameter, according to the environment. By numerically obtaining the maxima of the thermal stress and strain of the electronic components according to the operation environments with the temperature results, the fatigue cycle can be estimated.

Hur, Jin-Huek; Lee, Tae-Gu; Moon, Sun-Ae; Lee, Sang-Jae; Yoo, Hoseon; Moon, Seung-Jae; Lee, Jae-Heon

2008-09-01

357

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

Federal Register 2010, 2011, 2012, 2013

...Testing and Adoption of Pay for Success (PFS) Financing Models...Camacho, Attention: Pay for Success Incentive Fund RFI, U.S...Testing and Adoption of Pay for Success (PFS) Financing Models...based and other non-profit organizations, private sector...

2013-12-17

358

On the limit theorem for life time distribution connected with some reliability systems and their validation by means of the Monte Carlo method  

NASA Astrophysics Data System (ADS)

We prove the limit theorem for life time distribution connected with reliability systems when their life time is a Pascal Convolution of independent and identically distributed random variables. We show that, in some conditions, such distributions may be approximated by means of Erlang distributions. As a consequnce, survival functions for such systems may be, respectively, approximated by Erlang survival functions. By using Monte Carlo method we experimantally confirm the theoretical results of our theorem.

Gheorghe, Munteanu Bogdan; Alexei, Leahu; Sergiu, Cataranciuc

2013-09-01

359

Development of a lifetime prediction model for lithium-ion batteries based on extended accelerated aging test data  

NASA Astrophysics Data System (ADS)

Battery lifetime prognosis is a key requirement for successful market introduction of electric and hybrid vehicles. This work aims at the development of a lifetime prediction approach based on an aging model for lithium-ion batteries. A multivariable analysis of a detailed series of accelerated lifetime experiments representing typical operating conditions in hybrid electric vehicle is presented. The impact of temperature and state of charge on impedance rise and capacity loss is quantified. The investigations are based on a high-power NMC/graphite lithium-ion battery with good cycle lifetime. The resulting mathematical functions are physically motivated by the occurring aging effects and are used for the parameterization of a semi-empirical aging model. An impedance-based electric-thermal model is coupled to the aging model to simulate the dynamic interaction between aging of the battery and the thermal as well as electric behavior. Based on these models different drive cycles and management strategies can be analyzed with regard to their impact on lifetime. It is an important tool for vehicle designers and for the implementation of business models. A key contribution of the paper is the parameterization of the aging model by experimental data, while aging simulation in the literature usually lacks a robust empirical foundation.

Ecker, Madeleine; Gerschler, Jochen B.; Vogel, Jan; Käbitz, Stefan; Hust, Friedrich; Dechent, Philipp; Sauer, Dirk Uwe

2012-10-01

360

Accelerated Learning (?)  

Microsoft Academic Search

We wish to pose accelerated learning as a challenge for intelligent systems technology. Research on intelligent tutoring systems has proved that accelerated learning is possible. The Sherlock tutor for electronics troubleshooting, for example, condensed four years of on-the-job training to approximately 25 hours, compressing the duration of the experience-feedback-learning cycle. But accelerated learning should refer to more than the hastening

Robert R. Hoffman; Paul J. Feltovich; Stephen M. Fiore; Gary Klein; David Ziebell

2009-01-01

361

Analytical and experimental investigation of the feasibility of accelerated lifetime testing of materials exposed to an atomic oxygen beam  

NASA Technical Reports Server (NTRS)

The interaction of atomic particles with surfaces is of both scientific and technological interest. Past work emphasizes the measurement of high-energy sputtering yields. Very little work utilized low-energy beams for which chemical and electronic effects can be important. Even less work has been carried out using well-defined low-energy projectiles. The use of low-energy, reactive projectiles permits one to investigate surface processes that have not been well characterized. As the energy of the projectile decreases, the collisional cascades and spikes, that are common for high-energy projectiles, become less important, and chemical and electronic effects can play a significant role. Aspects of particle-surface interactions are of concern in several areas of technology. For example, the erosion, desorption, and glow of surfaces of spacecraft in orbit are important in the arena of space technology. The materials studied under this contract are of possible use on the exterior portions of the power generation system of Space Station Freedom. Under the original designs, Space Station Freedom's power generation system would generate potential differences on the surface as high as 200 volts. Ions in the plasma that often surround orbiting vehicles would be accelerated by these potentials leading to bombardment and erosion of the exposed surfaces. The major constituent of the atmosphere, approximately 90 percent, in the low earth orbit region is atomic oxygen. Since atomic oxygen is extremely reactive with most materials, chemical effects can arise in addition to the physical sputtering caused by the acceleration of the oxygen ions. Furthermore, the incident oxygen ions can remain embedded in the exposed surfaces, altering the chemical composition of the surfaces. Since the effective binding energy of a chemically altered surface can be quite different from that of the pure substrate, the sputtering yield of a chemically altered surface is usually different also. The low-energy O+ sputtering yield measurements, reported here, will help quantify the erosion rates for materials exposed to the low-earth orbit environment. These measurements are of technological importance in another respect. In most surface analysis techniques, a surface is bombarded with ions, electrons or photons. Information concerning the structure of the surface and near-surface bulk, abundance of impurities and defects, as well as other surface properties are obtained either from the desorbed species or from the scattered projectiles. Because of their low penetration depth, low-energy ions provide an advantage over other techniques because they provide information that is more indicative of conditions on the surface rather than integrated effects arising from deeper in the bulk. A better understanding of the microscopic processes involved in these interactions is not only of basic scientific interest, but will also aid the scientific community by increasing the accuracy and usefulness of these surface analysis techniques.

Albridge, Royal; Barnes, Alan; Tolk, Norman

1993-01-01

362

Investigation of the effects of acid rain on the deterioration of cement concrete using accelerated tests established in laboratory  

Microsoft Academic Search

Deterioration of cement concrete specimens caused by simulated acid rain was investigated by laboratory tests. Before and after cement concrete specimens were exposed to simulated acid rain, the neutralized depth, the compressive strength and the chemical compositions in the hardened cement paste were measured. The mineralogical composition of the concrete specimens was analyzed with XRD. The results lead to the

Shaodong Xie; Li Qi; Ding Zhou

2004-01-01

363

The Conversion and operation of the Cornell electron storage ring as a test accelerator (cesrta) for damping rings research and development  

SciTech Connect

In March of 2008, the Cornell Electron Storage Ring (CESR) concluded twenty eight years of colliding beam operations for the CLEO high energy physics experiment. We have reconfigured CESR as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. The primary goals of the CesrTA program are to achieve a beam emittance approaching that of the ILC Damping Rings with a positron beam, to investigate the interaction of the electron cloud with both low emittance positron and electron beams, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies (in particular a fast x-ray beam size monitor capable of single pass measurements of individual bunches). We report on progress with the CESR conversion activities, the status and schedule for the experimental program, and the first experimental results that have been obtained.

Palmer, M.A.; Alexander, J.; Byrd, J.; Celata, C.M.; Corlett, J.; De Santis, S.; Furman, M.; Jackson, A.; Kraft, R.; Munson, D.; Penn, G.; Plate, D.; Rawlins, A.; Venturini, M.; Zisman, M.; Billing, M.; Calvey, J.; Chapman, S.; Codner, G.; Conolly, C.; Crittenden, J.; Dobbins, J.; Dugan, G.; Fontes, E.; Forster, M.; Gallagher, R.; Gray, S.; Greenwald, S.; Hartill, D.; Hopkins, W.; Kandaswamy, J.; Kreinick, D.; Li, Y.; Liu, X.; Livezey, J.; Lyndaker, A.; Medjidzade, V.; Meller, R.; Peck, S.; Peterson, D.; Rendina, M.; Revesz, P.; Rice, D.; Rider, N.; Rubin, D.; Sagan, D.; Savino, J.; Seeley, R.; Sexton, J.; Shanks, J.; Sikora, J.; Smolenski, K.; Strohman, C.; Temnykh, A.; tigner, M.; Whitney, W.; Williams, H.; Vishniakou, S.; Wilkens, T.; Harkay, K.; Holtzapple, R.; Smith, E.; Jones, J.; Wolski, A.; He, Y.; Ross, M.; Tan, C.Y.; Zwaska, R.; Flanagan, J.; Jain, P.; Kanazawa, K.; Ohmi, K.; Sakai, H.; Shibata, K.; Suetsugu, Y.; Kharakh, D.; Pivi, M.; Wang, L.

2009-05-01

364

Report on accelerated corrosion studies  

Microsoft Academic Search

Sandia National Laboratories (SNL) conducted accelerated atmospheric corrosion testing for the U.S. Consumer Product Safety Commission (CPSC) to help further the understanding of the development of corrosion products on conductor materials in household electrical components exposed to environmental conditions representative of homes constructed with problem drywall. The conditions of the accelerated testing were chosen to produce corrosion product growth that

Curtis Dale Mowry; Sarah Jill Glass; Neil Robert Sorensen

2011-01-01

365

Failure Engineering Study and Accelerated Stress Test Results for the Mars Global Surveyor Spacecraft's Power Shunt Assemblies  

NASA Technical Reports Server (NTRS)

Due to a post launch failure of a part a new plan for the Mars Global Surveyor was developed. This new plan involved the addition of many deep thermal cycles to the Power Shunt Assemblies (PSA's). This new plan exceeds the previous acceptance cold level, and fatigue life on packaging design. This presentation reviews the experiments that were used to test the capabilities of the PSA to function in the new situation. It also reviews the analyses preformed to verify the most likely failure mechanism, and the likelihood that these failures would impact the new mission requirements.

Gibbel, Mark; Larson, Tim

1999-01-01

366

Wakefield accelerators  

SciTech Connect

The search for new methods to accelerate particle beams to high energy using high gradients has resulted in a number of candidate schemes. One of these, wakefield acceleration, has been the subject of considerable R D in recent years. This effort has resulted in successful proof of principle experiments and in increased understanding of many of the practical aspects of the technique. Some wakefield basics plus the status of existing and proposed experimental work is discussed, along with speculations on the future of wake field acceleration. 10 refs., 6 figs.

Simpson, J.D.

1990-01-01

367

Wake field acceleration experiments  

SciTech Connect

Where and how will wake field acceleration devices find use for other than, possibly, accelerators for high energy physics. I don't know that this can be responsibly answered at this time. What I can do is describe some recent results from an ongoing experimental program at Argonne which support the idea that wake field techniques and devices are potentially important for future accelerators. Perhaps this will spawn expanded interest and even new ideas for the use of this new technology. The Argonne program, and in particular the Advanced Accelerator Test Facility (AATF), has been reported in several fairly recent papers and reports. But because this is a substantially new audience for the subject, I will include a brief review of the program and the facility before describing experiments. 10 refs., 7 figs.

Simpson, J.D.

1988-01-01

368

Influence of Bond Coat Roughness on Life Time of APS Thermal Barrier Coating Systems under Thermo-Mechanical Load  

NASA Astrophysics Data System (ADS)

The influence of the bond coat roughness on the life time of air plasma-sprayed (APS) thermal barrier coating systems (TBCs) was investigated under thermo-mechanical (TMF) load. The TBC system was applied on hollow cylindrical specimens made of the single crystal super alloy CMSX-4 in the orientation <001> with a MCrAlY-bond coat. Two different values of the bond coat roughness were investigated. In order to study the influence of the thicknesses of the thermally grown oxide layer (TGO), the specimens were isothermally oxidized at 1000 °C for a long term prior to the TMF experiments. The thermo-mechanical experiments show a higher number of cycles-to-failure for TBCs corresponding to an increase of the bond coat roughness. Furthermore, it could be demonstrated that a certain TGO thickness is needed to produce a total delamination of the top coat in the TMF experiments. This minimum thickness varies with the surface roughness of the bond coat and the TMF cycle's phase shift and strain range. Crack initiation and crack propagation were investigated by microscopical analyses, for example, SEM and EDX. Therefore most of the experiments were completed before a total delamination of the top coat occurred. On the basis of these investigations, crack initiation and crack propagation under thermo-mechanical load were described systematically.

Schmidt, Andreas; Aleksanoglu, Herman; Mao, Tongsheng; Scholz, Alfred; Berger, Christina

369

Accelerated relative sea-level rise and rapid coastal erosion: Testing a causal relationship for the Louisiana barrier islands  

USGS Publications Warehouse

The role of relative sea-level rise as a cause for the rapid erosion of Louisiana's barrier island coast is investigated through a numerical implementation of a modified Bruun rule that accounts for the low percentage of sand-sized sediment in the eroding Louisiana shoreface. Shore-normal profiles from 150 km of coastline west of the Mississippi delta are derived from bathymetric surveys conducted during the 1880s. 1930s and 1980s. An RMS difference criterion is employed to test whether an equilibrium profile form is maintained between survey years. Only about half the studied profiles meet the equilibrium Criterion this represents a significant limitation on the potential applicability of the Bruun rule. The profiles meeting the equilibrium criterion, along with measured rates of relative sea-level rise, are used to hindcast shoreline retreat rates at 37 locations within the study area. Modeled and observed shoreline retreat rates show no significant correlation. Thus in terms of the Bruun approach relative sea-level rise has no power for hindcasting (and presumably forecasting) rates of coastal erosion for the Louisiana barrier islands.

List, J. H.; Sallenger, Jr. , A. H.; Hansen, M. E.; Jaffe, B. E.

1997-01-01

370

Acceleration switch  

DOEpatents

The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

Abbin, Jr., Joseph P. (Albuquerque, NM); Devaney, Howard F. (Cedar Crest, NM); Hake, Lewis W. (Albuquerque, NM)

1982-08-17

371

Podcast: Acceleration  

NSDL National Science Digital Library

The Podcast: Acceleration is a segment of the Force and Motion Short Course. The podcast is 2 minutes 13 seconds in duration. Presented by science experts and NSTA staff, the NSTA Online Short Courses are professional development opportunities de

2009-07-06

372

Use of thermogravimetric analysis to develop accelerated test methods to investigate long-term environmental effects on fiber-reinforced plastics  

SciTech Connect

The development of accelerated test methods to characterize long-term environmental effects on fiber-reinforced plastics (FRPs) requires the use of physicochemical methods, as well as macromechanical measurements, in order to investigate the degradation processes and predict their course over long periods of time. Thermochemical and mechanical measurements were performed on a large number of FRPs exposed to neutral, basic, and acidic media between 23 and 80 C over periods of 7 to 224 days. The resin matrices used in the present study included vinylester, polyester, and epoxy, and the fiber materials were silicate glass, aramid, and carbon. TGA was used to study the effects of aqueous media on FRPs. In particular, the relative weight loss upon heating the previously exposed material from 150 to 300 C was found to be indicative of the extent of matrix depolymerization. Indications were obtained for correlation between this weight loss and the extent of degradation of various measures of mechanical strength. The measured weight change of the tested materials during exposure was found to reflect the extent of water absorption and could be related to the extent of the weight loss between 150 and 300 C. In basic environments, weight loss, rather than gain, took place as a result of fiber dissolution.

Prian, L.; Pollard, R.; Shan, R.; Mastropietro, C.W.; Barkatt, A. [Catholic Univ. of America, Washington, DC (United States); Gentry, T.R. [Georgia Inst. of Tech., Atlanta, GA (United States); Bank, L.C. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Civil and Environmental Engineering

1997-12-31

373

Biodegradation of Deep-Sea Oil Spill at the Gulf of Mexico: an Estimate of Half Life Time  

NASA Astrophysics Data System (ADS)

The deep-sea oil spill has generated an anthropogenic disaster with severe urgency. One big question being raised is how fast the spilled oil can be biodegraded in the seawater with native bacteria. The rate of biodegradation depends on many factors, including, for example, the concentration of oil and oil degrading microbes. In the oil leakage event at the Gulf of Mexico, because of the large amount of oil spill and the addition of chemical dispersants, oil can exist either in the form of oil droplets that are separated from water phase, or as dissolved oil. This work aims to estimate the time scale of oil biodegradation for both of these forms. In the former case, the size distribution of oil droplets can be critical because it determines the amount of contact area between bacteria and oil. It has been observed that oil droplets biodegradation occurs when microbes adheres to the oil-water interface. Here we formulated a model that incorporates effects of the oil droplets size distribution and microbial activity in the water-oil interface into a shrinking-core model. The growth of microbes and the corresponding rates of biodegradation were represented by the Monod’s equation. The model was calibrated using experimental results of previous studies on dispersed oil biodegradation. Our results show that biodegradation rates of oil droplets depend largely on oil droplet size distribution and on the biodegradation rate constant. For the oil and microbes’ concentration levels reported for the Gulf of Mexico oil spill, the half life time of the spilled oil is within one week, which is consistent with experimental findings using field seawater samples collected from the Gulf of Mexico. However, it takes much longer to biodegrade the remaining 50%. Depending on the oil droplets size distribution, the remaining 50% can last for months. This does not happen with dissolved oil biodegradation which, according to our results, is readily biodegraded at rates 2-3 times faster than oil droplets.

Vilcaez, J.; Li, L.; Hubbard, S. S.; Hazen, T.

2010-12-01

374

High Power rf Test on X-band MgxCa1-xTiO3 Based Dielectric-Loaded Accelerating Structure  

NASA Astrophysics Data System (ADS)

In this paper, we report experimental results on a series of high-power rf tests for dielectric-loaded accelerating (DLA) structures using a high power X-band Magnicon at the Naval Research Laboratory. The dielectric material loaded into this DLA structure is a commonly used high-Q ceramic, MgxCa1-xTiO3 (MCT), with a dielectric constant of 20. The purpose of these experiments is to study high-power phenomena in the DLA structure. Two important phenomena have been observed during these experiments. First, multipactor effects are strongly dependent on the dielectric material used in the DLA structure. In this case, the multipactor-induced power absorption threshold and trend to higher power differ when MCT is used instead of alumina. Second, although we did not observe dielectric breakdown in the bulk dielectric, breakdown occurred at the butt-joint between adjacent dielectric sections in the MCT structure. This occurs because of manufacturing imperfections of the joint that cause large, local field enhancements.

Jing, C.; Konecny, R.; Gai, W.; Gold, S. H.; Power, J. G.; Kinkead, A. K.; Liu, W.

2004-12-01

375

Particle Accelerators Test Cosmological Theory.  

ERIC Educational Resources Information Center

Discusses the symbiotic relationship of cosmology and elementary-particle physics. Presents a brief overview of particle physics. Explains how cosmological considerations set limits on the number of types of elementary particles. (RT)

Schramm, David N.; Steigman, Gary

1988-01-01

376

Brazilian accelerator mass spectrometry program  

Microsoft Academic Search

The present status of the Brazilian AMS program, based on the University of São Paulo 8UD tandem accelerator, is described. Results of tests and developments on voltage stability, focusing, automatic system for changing beams and detection system are presented. 36Cl and 26Al beams have already been successfully accelerated and detected.

G. M. Santos; J. C. Acquadro; R. M. Anjos; P. R. S. Gomes; C. Tenreiro; R. Liguori Neto; M. M. Coimbra; C. R. Appoloni; A. M. M. Maciel; N. H. Medina; M. A. Rizzuto; N. Carlin Filho

1997-01-01

377

Lifetime assessment of atomic-layer-deposited Al2O3-Parylene C bilayer coating for neural interfaces using accelerated age testing and electrochemical characterization.  

PubMed

The lifetime and stability of insulation are critical features for the reliable operation of an implantable neural interface device. A critical factor for an implanted insulation's performance is its barrier properties that limit access of biological fluids to the underlying device or metal electrode. Parylene C is a material that has been used in FDA-approved implantable devices. Considered a biocompatible polymer with barrier properties, it has been used as a substrate, insulation or an encapsulation for neural implant technology. Recently, it has been suggested that a bilayer coating of Parylene C on top of atomic-layer-deposited Al2O3 would provide enhanced barrier properties. Here we report a comprehensive study to examine the mean time to failure of Parylene C and Al2O3-Parylene C coated devices using accelerated lifetime testing. Samples were tested at 60°C for up to 3 months while performing electrochemical measurements to characterize the integrity of the insulation. The mean time to failure for Al2O3-Parylene C was 4.6 times longer than Parylene C coated samples. In addition, based on modeling of the data using electrical circuit equivalents, we show here that there are two main modes of failure. Our results suggest that failure of the insulating layer is due to pore formation or blistering as well as thinning of the coating over time. The enhanced barrier properties of the bilayer Al2O3-Parylene C over Parylene C makes it a promising candidate as an encapsulating neural interface. PMID:24185000

Minnikanti, Saugandhika; Diao, Guoqing; Pancrazio, Joseph J; Xie, Xianzong; Rieth, Loren; Solzbacher, Florian; Peixoto, Nathalia

2014-02-01

378

Particle acceleration  

NASA Technical Reports Server (NTRS)

Data is compiled from Solar Maximum Mission and Hinothori satellites, particle detectors in several satellites, ground based instruments, and balloon flights in order to answer fundamental questions relating to: (1) the requirements for the coronal magnetic field structure in the vicinity of the energization source; (2) the height (above the photosphere) of the energization source; (3) the time of energization; (4) transistion between coronal heating and flares; (5) evidence for purely thermal, purely nonthermal and hybrid type flares; (6) the time characteristics of the energization source; (7) whether every flare accelerates protons; (8) the location of the interaction site of the ions and relativistic electrons; (9) the energy spectra for ions and relativistic electrons; (10) the relationship between particles at the Sun and interplanetary space; (11) evidence for more than one acceleration mechanism; (12) whether there is single mechanism that will accelerate particles to all energies and also heat the plasma; and (13) how fast the existing mechanisms accelerate electrons up to several MeV and ions to 1 GeV.

Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.; Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.; Ellison, D.

1986-01-01

379

Plasma accelerator  

DOEpatents

There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

Wang, Zhehui (Los Alamos, NM); Barnes, Cris W. (Santa Fe, NM)

2002-01-01

380

The application of a linear electron accelerator in radiation processing  

NASA Astrophysics Data System (ADS)

A 3-5 MeV electron beam generated by a BF-5 type linear electron accelerator has been used in some radiation processing works, such as, (1) The cross-linking technology by radiation for the polyethylene foaming processing --- the correlation between the cross-linkage and the absorbed dose, the relation between the elongation of foaming polyethylene and the dose, the relation between the size of the cavities and the gelatin rate and the optimum range of dosage for foaming have been found. (2) The research work on the fast switch thyristor irradiated by electron beam --- The relation between the absorbed dose and the life-time of minority carriers has been studied and the optimum condition for radiation processing was determined. This process is much better than the conventional gold diffusion in raising the quality and end-product rate of these devices. Besides, we have made some testing works on the hereditary mutation of plant seeds and microorganism mutation induced by electron radiation and radiation sterilization for some medical instruments and foods.

Ruiying, Zhou; Binglin, Wang; Wenxiu, Chen; Yongbao, Gu; Yinfen, Zhang; Simin, Qian; Andong, Liu; Peide, Wang

381

Blind evaluation of the microwave-accelerated metal-enhanced fluorescence ultrarapid and sensitive Chlamydia trachomatis test by use of clinical samples.  

PubMed

Accurate point-of-care (POC) diagnostic tests for Chlamydia trachomatis infection are urgently needed for the rapid treatment of patients. In a blind comparative study, we evaluated microwave-accelerated metal-enhanced fluorescence (MAMEF) assays for ultrafast and sensitive detection of C. trachomatis DNA from vaginal swabs. The results of two distinct MAMEF assays were compared to those of nucleic acid amplification tests (NAATs). The first assay targeted the C. trachomatis 16S rRNA gene, and the second assay targeted the C. trachomatis cryptic plasmid. Using pure C. trachomatis, the MAMEF assays detected as few as 10 inclusion-forming units/ml of C. trachomatis in less than 9 min, including DNA extraction and detection. A total of 257 dry vaginal swabs from 245 female adolescents aged 14 to 22 years were analyzed. Swabs were eluted with water, the solutions were lysed to release and to fragment genomic DNA, and MAMEF-based DNA detection was performed. The prevalence of C. trachomatis by NAATs was 17.5%. Of the 45 samples that were C. trachomatis positive and the 212 samples that were C. trachomatis negative by NAATs, 33/45 and 197/212 were correctly identified by the MAMEF assays if both assays were required to be positive (sensitivity, 73.3%; specificity, 92.9%). Using the plasmid-based assay alone, 37/45 C. trachomatis-positive and 197/212 C. trachomatis-negative samples were detected (sensitivity, 82.2%; specificity, 92.9%). Using the 16S rRNA assay alone, 34/45 C. trachomatis-positive and 197/212 C. trachomatis-negative samples were detected (sensitivity, 75.5%; specificity, 92.9%). The overall rates of agreement with NAAT results for the individual 16S rRNA and cryptic plasmid assays were 89.5% and 91.0%, respectively. Given the sensitivity, specificity, and rapid detection of the plasmid-based assay, the plasmid-based MAMEF assay appears to be suited for clinical POC testing. PMID:23804384

Melendez, Johan H; Huppert, Jill S; Jett-Goheen, Mary; Hesse, Elizabeth A; Quinn, Nicole; Gaydos, Charlotte A; Geddes, Chris D

2013-09-01

382

Argonne Wakefield Accelerator Update '92  

SciTech Connect

The Argonne Wakefield Accelerator (AWA) is an experiment designed to test various ideas related to wakefield technology. Construction is now underway for a 100 nC electron beam in December of 1992. This report updates this progress.

Rosing, M.; Balka, L.; Chojnacki, E.; Gai, W.; Ho, C.; Konecny, R.; Power, J.; Schoessow, P.; Simpson, J.

1992-01-01

383

Argonne Wakefield Accelerator Update `92  

SciTech Connect

The Argonne Wakefield Accelerator (AWA) is an experiment designed to test various ideas related to wakefield technology. Construction is now underway for a 100 nC electron beam in December of 1992. This report updates this progress.

Rosing, M.; Balka, L.; Chojnacki, E.; Gai, W.; Ho, C.; Konecny, R.; Power, J.; Schoessow, P.; Simpson, J.

1992-09-01

384

Electrostatic Plasma Accelerator (EPA)  

NASA Technical Reports Server (NTRS)

The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass. The goal of the present program is to demonstrate feasibility of the EPA thruster concept through experimental and theoretical investigations of the EPA acceleration mechanism and discharge chamber performance. Experimental investigations will include operating the test bed ion (TBI) engine as an EPA thruster and parametrically varying the thruster geometry and operating conditions to quantify the electrostatic plasma acceleration effect. The theoretical investigations will include the development of a discharge chamber model which describes the relationships between the engine size, plasma properties, and overall performance. For the EPA thruster to be a viable propulsion concept, overall thruster efficiencies approaching 30% with specific impulses approaching 1000 s must be achieved.

Brophy, John R.; Aston, Graeme

1989-01-01

385

Kenneth J. Turner and Qian Bing. Systematic Testing of Radiotherapy Accelerators. In Hartmut Ehrig, Berndt J. Kramer and Atilla Ertas, editors,  

E-print Network

are also relevant, such as the ISO/IEC 9000 series on quality assur- ance and its European EN equivalents. This is automatically translated into LOTOS and combined with the accelerator specification. It then becomes manageable

Turner, Ken

386

DEVELOPMENT, PRODUCTION AND TESTS OF PROTOTYPE SUPERCONDUCTING CAVITIES FOR THE HIGH BETA SECTION OF THE ISAC-II HEAVY ION ACCELERATOR AT TRIUMF  

Microsoft Academic Search

The medium beta section of the ISAC-II heavy ion superconducting linear accelerator, consisting of 20 cavities, has been in operation at TRIUMF since 2006. The high beta section of the accelerator, consisting of an additional twenty cavities, is currently under development and is scheduled for completion in 2009. The cavity is a superconducting bulk Niobium two-gap quarter-wave resonator for frequency

V. Zvyagintsev; R. E. Laxdal; R. Dawson; K. Fong; A. Grasselino; P. Harmer; M. Marchetto

387

Compact accelerator  

DOEpatents

A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Kirbie, Hugh C. (Los Alamos, NM)

2007-02-06

388

BICEP's acceleration  

NASA Astrophysics Data System (ADS)

The recent Bicep2 [1] detection of, what is claimed to be primordial B-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential V(phi) for the first time — if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles epsilon(N) as a function of e-fold N and derived posterior distributions of the primordial power spectrum P(k) and potential V(phi). We find that the Bicep2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales k~ 10-3 Mpc -1. This is in agreement with a previous detection of a suppression in the scalar power [2].

Contaldi, Carlo R.

2014-10-01

389

BICEP's acceleration  

E-print Network

The recent BICEP2 detection of, what is claimed to be primordial $B$-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential $V(\\phi)$ for the first time - if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles $\\epsilon(N)$ as a function of $e$-fold $N$ and derived posterior distributions of the primordial power spectrum $P(k)$ and potential $V(\\phi)$. We find that the BICEP2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales $k\\sim 10^{-3}$ Mpc$^{-1}$. This is in agreement with a previous detection of a suppression in the scalar power.

Carlo R. Contaldi

2014-07-24

390

BICEP's acceleration  

E-print Network

The recent BICEP2 detection of, what is claimed to be primordial $B$-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential $V(\\phi)$ for the first time - if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles $\\epsilon(N)$ as a function of $e$-fold $N$ and derived posterior distributions of the primordial power spectrum $P(k)$ and potential $V(\\phi)$. We find that the BICEP2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales $k\\sim 10^{-3}$ Mpc$^{-1}$. This is in agreement with a previous detection of a...

Contaldi, Carlo R

2014-01-01

391

Advanced concepts for acceleration  

SciTech Connect

Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)

Keefe, D.

1986-07-01

392

Computer simulations of new dielectric accelerator devices  

Microsoft Academic Search

Recently, dielectric wakefield accelerator structures have been successfully demonstrated at the Argonne Advanced Accelerator Test Facility. This paper describes computer simulations of these experiments, including schemes for damping transverse deflecting forces in these devices. These simulations were performed using the MAFIA and ARRAKIS codes. MAFIA is a set of electromagnetic solvers in three dimensions widely used for designing accelerator components.

K. C. D. Chan; P. Schoessow

1990-01-01

393

Solar system constraints on Rindler acceleration  

E-print Network

We discuss the classical tests of general relativity in the presence of Rindler acceleration. Among these tests the perihelion shifts give the tightest constraints and indicate that the Pioneer anomaly cannot be caused by a universal solar system Rindler acceleration. We address potential caveats for massive test-objects. Our tightest bound on Rindler acceleration that comes with no caveats is derived from radar echo delay and yields |a|<3nm/s^2.

Sante Carloni; Daniel Grumiller; Florian Preis

2011-03-01

394

Accelerators and the Accelerator Community  

SciTech Connect

In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.

Malamud, Ernest; Sessler, Andrew

2008-06-01

395

Impact accelerations  

NASA Technical Reports Server (NTRS)

The degree to which impact acceleration is an important factor in space flight environments depends primarily upon the technology of capsule landing deceleration and the weight permissible for the associated hardware: parachutes or deceleration rockets, inflatable air bags, or other impact attenuation systems. The problem most specific to space medicine is the potential change of impact tolerance due to reduced bone mass and muscle strength caused by prolonged weightlessness and physical inactivity. Impact hazards, tolerance limits, and human impact tolerance related to space missions are described.

Vongierke, H. E.; Brinkley, J. W.

1975-01-01

396

Ring accelerators  

SciTech Connect

We present two-dimensional simulations in (r-z) and r-theta) cylinderical geometries of imploding-liner-driven accelerators of rings of charged particles. We address issues of azimuthal and longitudinal stability of the rings. We discuss self-trapping designs in which beam injection and extraction is aided by means of external cusp fields. Our simulations are done with the 2-1/2-D particle-in-cell plasma simulation code CLINER, which combines collisionless, electromagnetic PIC capabilities with a quasi-MHD finite element package.

Gisler, G.; Faehl, R.

1983-01-01

397

Accelerator Technology Division progress report, FY 1992  

SciTech Connect

This report briefly discusses the following topics: The Ground Test Accelerator Program; Defense Free-Electron Lasers; AXY Programs; A Next Generation High-Power Neutron-Scattering Facility; JAERI OMEGA Project and Intense Neutron Sources for Materials Testing; Advanced Free-Electron Laser Initiative; Superconducting Supercollider; The High-Power Microwave (HPM) Program; Neutral Particle Beam (NPB) Power Systems Highlights; Industrial Partnering; Accelerator Physics and Special Projects; Magnetic Optics and Beam Diagnostics; Accelerator Design and Engineering; Radio-Frequency Technology; Accelerator Theory and Free-Electron Laser Technology; Accelerator Controls and Automation; Very High-Power Microwave Sources and Effects; and GTA Installation, Commissioning, and Operations.

Schriber, S.O.; Hardekopf, R.A.; Heighway, E.A.

1993-07-01

398

Accelerator Technology Division annual report, FY 1991  

SciTech Connect

This report discusses the following programs: The Ground Test Accelerator Program; APLE Free-Electron Laser Program; Accelerator Transmutation of Waste; JAERI, OMEGA Project, and Intense Neutron Source for Materials Testing; Advanced Free-Electron Laser Initiative; Superconducting Super Collider; The High-Power Microwave Program; {Phi} Factory Collaboration; Neutral Particle Beam Power System Highlights; Accelerator Physics and Special Projects; Magnetic Optics and Beam Diagnostics; Accelerator Design and Engineering; Radio-Frequency Technology; Free-Electron Laser Technology; Accelerator Controls and Automation; Very High-Power Microwave Sources and Effects; and GTA Installation, Commissioning, and Operations.

Not Available

1992-04-01

399

Rail accelerator research at Lewis Research Center  

NASA Technical Reports Server (NTRS)

A rail accelerator was chosen for study as an electromagnetic space propulsion device because of its simplicity and existing technology base. The results of a mission feasibility study using a large rail accelerator for direct launch of ton-size payloads from the Earth's surface to space, and the results of initial tests with a small, laboratory rail accelerator are presented. The laboratory rail accelerator has a bore of 3 by 3 mm and has accelerated 60 mg projectiles to velocities of 300 to 1000 m/s. Rail materials of Cu, W, and Mo were tested for efficiency and erosion rate.

Kerslake, W. R.; Cybyk, B. Z.

1982-01-01

400

Summary report on large HVEC accelerators  

SciTech Connect

The main features are described of the ten presently operating large HVEC tandem accelerators and of four additional HVEC accelerators which are in different stages of testing, construction or planning. Present performance characteristics are discussed as well as available information about long term reliability. Some recent improvements are mentioned and comparisons are drawn for acceleration tube gradients in various different configurations and accelerators. Finally, some possible future developments are indicated.

Thieberger, P.

1981-01-01

401

Dielectric Stimulated Wakefield Accelerator  

Microsoft Academic Search

Wakefield acceleration in a dielectric-loaded waveguide has been previously analyzed and tested.(M. Rosing and W. Gai, Phys. Rev. D 42), 1829 (1990).^,3 We note that a dielectric geometry can be found in which the wakefield is a nearly-periodic function of z - ct, and that the multi-mode wakefield period and interbunch spacing can coincide. Thus, superposition of wakes can occur.

T. B. Zhang; J. L. Hirshfield; T. C. Marshall; B. Hafizi

1997-01-01

402

Electrothermal accelerators  

SciTech Connect

In electrothermal (ET) guns, the projectile acceleration is governed by gas dynamics as in explosively-driven guns. In a conventional gun, however, both the energy for heating and the material to be heated are contained in the solid propellant. Electrothermal launchers allow an external electric power supply to be used to provide the necessary energy; hence, lower atomic weight propellants may be used and heated to higher temperatures while maintaining a tailored acceleration profile. Important improvements in hypervelocity performance and barrel degradation can be obtained by controlling the electric discharges via power conditioning. Complex voltage and current waveforms are achieved using complex power conditioning systems, since the existing power supplies do not conform to ET gun requirements. This paper advances the concept of a single element power supply for ET guns, showing that compulsator-type machines with waveform flexibility (pulse shaping capability) can satisfy all the ET gun power supply and conditioning requirements while maintaining a high efficiency and los mass. Additionally, compulsators are suitable for repetitive-fire applications. Also described in the paper is a system of homopolar generators (HPGs) and inductors for laboratory applications.

Driga, M.D.; Ingram, M.W.; Weldon, W.F. (Texas Univ., Austin, TX (USA). Center for Electromechanics)

1989-01-01

403

Mechanics of overground accelerated running vs. running on an accelerated treadmill.  

PubMed

Unsteady state gait involving net accelerations has been studied overground and on a treadmill. Yet it has never been tested if and to what extent both set-ups are mechanically equal. This study documents the differences in ground reaction forces for accelerated running on an instrumented runway and running on an accelerating treadmill by building a theoretical framework which is experimentally put to the test. It is demonstrated that, in contrast to overground, no mean fore-after force impulse should be generated to follow an accelerating treadmill due to the absence of linear whole body acceleration. Accordingly, the adaptations in the braking phase (less braking) and propulsive phase (more propulsion) to accelerate overground are not present to follow an accelerating treadmill. It can be concluded that running on an accelerating treadmill is mechanically different from accelerated running overground. PMID:23228623

Van Caekenberghe, Ine; Segers, Veerle; Willems, Patrick; Gosseye, Thierry; Aerts, Peter; De Clercq, Dirk

2013-05-01

404

Testing  

MedlinePLUS

... mutation, and must be identified through further testing. Prenatal Testing Prenatal testing is used to determine if a fetus has ... used: In amniocentesis , the most common form of prenatal testing, a very fine needle is inserted into the ...

405

Accelerator system and method of accelerating particles  

NASA Technical Reports Server (NTRS)

An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

Wirz, Richard E. (Inventor)

2010-01-01

406

Evaluation of HVDC cables for the St. Lawrence River crossing of Hydro-Quebec's 500 kV DC line. Part 2; Cable testing facility for dielectric and accelerated aging  

SciTech Connect

This paper describes the new cable testing facility at IREQ for long-term accelerated aging tests on HV cables. This test facility was required as part of an extensive program to evaluate the high-voltage cables for the river crossing of Hydro-Quebec's new transmission lines rated 800 kV AC and {plus minus}500 kV DC. The first application was for the evaluation of self-contained oil-filled (SCOF) cables for the St. Lawrence river crossing of the {plus minus}500 kV Quebec-New England HVDC power transmission system. The paper also describes the specific dielectric constraints resulting from the insertion of a short length of cable into a long line and, also, the circuits developed for the special tests, which reproduce the specific cable test conditions.

Trinh, N.G.; Couderc, D.; Faucher, P.; Chaaban, M.; Belec, M.; Leduc, J. (Inst. de Recherche d'Hydro-Quebec, Varennes, Quebec J3X 1S1 (CA))

1992-04-01

407

Particle acceleration in dipolarization events  

NASA Astrophysics Data System (ADS)

Using the electromagnetic fields of a recent MHD simulation of magnetotail reconnection, flow bursts and dipolarization, we investigate the acceleration of test particles (protons and electrons) to suprathermal energies, confirming and extending earlier results on acceleration mechanisms and sources. (Part of the new results have been reviewed recently in Birn et al., Space Science Reviews, 167, doi:10.1007/ s11214-012-9874-4.) The test particle simulations reproduce major features of energetic particle events (injections) associated with substorms or other dipolarization events, particularly a rapid rise of energetic particle fluxes over limited ranges of energy. The major acceleration mechanisms for electrons are betatron acceleration and Fermi acceleration in the collapsing magnetic field. Ions, although non-adiabatic, undergo similar acceleration. Two major entry mechanisms into the acceleration site are identified: cross-tail drift from the inner tail plasma sheet and reconnection entry from field lines extending to the more distant plasma sheet. The former dominates early in an event and at higher energies (hundreds of keV) while the latter constitutes the main source later and at lower energies (tens of keV). Despite the fact that the injection front moves earthward in the tail, the peak of energetic particle fluxes moves to higher latitude when mapped from the near-Earth boundary to Earth in a static magnetic field model.

Birn, J.; Hesse, M.; Nakamura, R.; Zaharia, S.

2013-05-01

408

An inverse free-electron-laser accelerator  

Microsoft Academic Search

Recent work at BNL on electron acceleration using the Inverse Free-Electron Laser (IFEL) has considered a low-energy, high-gradient, multi-stage linear accelerator. Experiments are planned at BNL's Accelerator Test Facility using its 50-MeV linac and 100-GW CO2 laser. We have built and tested a fast-excitation wiggler magnet with constant field, tapered period, and overall length of 47 cm. Vanadium-Permendur ferromagnetic laminations

A. S. Fisher; J. C. Gallardo; A. van Steenbergen; S. Ulc; M. Woodle; J. Sandweiss; Jyan-Min Fang

1993-01-01

409

Accelerator Technology Division progress report, FY 1993  

SciTech Connect

This report discusses the following topics: A Next-Generation Spallation-Neutron Source; Accelerator Performance Demonstration Facility; APEX Free-Electron Laser Project; The Ground Test Accelerator (GTA) Program; Intense Neutron Source for Materials Testing; Linac Physics and Special Projects; Magnetic Optics and Beam Diagnostics; Radio-Frequency Technology; Accelerator Controls and Automation; Very High-Power Microwave Sources and Effects; and GTA Installation, Commissioning, and Operation.

Schriber, S.O.; Hardekopf, R.A.; Heighway, E.A.

1993-12-31

410

Commissioning the GTA accelerator  

SciTech Connect

The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth`s magnetic field and travel in straight lines unless they enter the earth`s atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -} beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.

Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V. [Los Alamos National Lab., NM (United States); Connolly, R.; Weiss, R. [Grumman Space and Electronics Corp., Princeton, NJ (United States); Saadatmand, K. [Grumman Corp., Bethpage, NY (United States). Corporate Research Center

1992-09-01

411

Commissioning the GTA accelerator  

SciTech Connect

The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth's magnetic field and travel in straight lines unless they enter the earth's atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -} beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.

Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V. (Los Alamos National Lab., NM (United States)); Connolly, R.; Weiss, R. (Gr

1992-01-01

412

3D numerical test objects for the evaluation of a software used for an automatic analysis of a linear accelerator mechanical stability  

NASA Astrophysics Data System (ADS)

Mechanical stability of a medical LINear ACcelerator (LINAC), particularly the quality of the gantry, collimator and table rotations and the accuracy of the isocenter position, are crucial for the radiation therapy process, especially in stereotactic radio surgery and in Image Guided Radiation Therapy (IGRT) where this mechanical stability is perturbed due to the additional weight the kV x-ray tube and detector. In this paper, we present a new method to evaluate a software which is used to perform an automatic measurement of the "size" (flex map) and the location of the kV and the MV isocenters of the linear accelerator. The method consists of developing a complete numerical 3D simulation of a LINAC and physical phantoms in order to produce Electronic Portal Imaging Device (EPID) images including calibrated distortions of the mechanical movement of the gantry and isocenter misalignments.

Torfeh, Tarraf; Beaumont, Stéphane; Guédon, Jeanpierre; Benhdech, Yassine

2010-04-01

413

Calculation of water exchange times in the ICES-boxes with a eulerian dispersion model using a half-life time approach  

Microsoft Academic Search

Summary  The transport of passive, dissolved and conservative matter is calculated with a three-dimensional Eulerian transport model\\u000a in order to estimate the water exchange times for the ICES-Boxes. Daily flow fields calculated with a baroclinic circulation\\u000a model (Pohlmann [1991]) are used to drive the transport model.\\u000a \\u000a The half-life time of water exchange in a box is defined analogously to the half-life

Roger Luff; Thomas Pohlmann

1995-01-01

414

Microgravity acceleration measurement environment characterization  

NASA Technical Reports Server (NTRS)

The Space Acceleration Measurement System (SAMS) is a general-purpose instrumentation system designed to measure the accelerations onboard the shuttle Orbiter and shuttle/Spacelab vehicles. These measurements are used to support microgravity experiments and investigations into the microgravity environment of the vehicle. Acceleration measurement can be made at locations remote from the SAMS main instrumentation unit by the use of up to three remote triaxial sensor heads. The SAMS was developed by NASA's Lewis Research Center (LeRC) in support of NASA's microgravity science programs. In the past, numerous acceleration measurement systems have flown on various space missions. These systems were tailored to measure accelerations for a narrow set of requirements and were limited in bandwidth, dynamic range, and recording capability. In addition, these systems were mission-peculiar and not easily modified for other applications or missions. The result has been an inability to accurately assess the expected microgravity environment prior to a mission for a particular experiment and/or location. The prime science objective for SAMS on the SL-J mission will be to measure the accelerations experienced by a multitude of experiments in the two racks of the Japanese First Materials Processing Test (FMPT). The FMPT consists of a variety of materials science and life science experiments contained in racks no. 7 and no. 10. The SAMS data will be made available to the FMPT principal investigators after the mission for their analysis with the FMPT data. A secondary science objective for SAMS will be the characterization of the acceleration environment of the Spacelab module. This will include an analysis of the acceleration transfer function of the Spacelab module which will utilize the FMPT acceleration measurement along with measurements at the rack no. 9 structure. Another analytical effort to be undertaken is a general characterization of the acceleration environment of the Spacelab as an orbiting laboratory. These analysis efforts will be in conjunction with similar measurements and analyses on other SAMS Spacelab missions.

Delombard, Richard

1993-01-01

415

Numerical simulations of transient flows in ram accelerators  

Microsoft Academic Search

Time-accurate simulations are performed for reactive flows around accelerating projectiles in ram accelerators. The simulations show that the flow field is highly transient and the combustion process is strongly affected by the projectile acceleration. In the simulation, the acceleration of the projectile is coupled into the flow computation using the noninertial source (NIS) term. Tests of this technique show that

Chiping Li; K. Kailasanath; E. S. Oran; J. P. Boris; A. M. Landsberg

1993-01-01

416

A proposed type test for interturn insulation in multi-turn coils  

SciTech Connect

Stator insulation failures are a significant cause of forced outages of electrical machines. Accelerated aging tests or type tests have been developed and are now applied routinely to groundwall insulation in coils and bars used in machines to ensure satisfactory life time performance. It is generally accepted that many groundwall insulation failures in multi-turn coils are initiated by a premature breakdown of turn insulation. However, so far there is no type test available to examine the long term behavior of the turn insulation. The authors have been striving to develop such a type test for the turn insulation for more than ten years. Electrical, thermal, and mechanical stresses have been investigated for the accelerated aging of the turn insulation. A combination of thermal and mechanical stresses applied simultaneously has been demonstrated to produce a significant aging of the turn insulation. This paper summarizes the experimental results from tests on a large number of coils aged under electrical, thermal, and mechanical stresses. The results from factorial tests are analyzed to select the optimum test parameters which are then used to define a possible functional type test for the turn insulation.

Gupta, B.K. [Ontario Hydro Technologies, Toronto, Ontario (Canada); Fink, W.T. [Consolidated Edison Co. of New York, NY (United States)

1996-12-31

417

Chemical Accelerators The phrase "chemical accelerators"  

E-print Network

Meetings Chemical Accelerators The phrase "chemical accelerators" is scarcely older than for one or two dozen people grew to include nearly a hundred. Chemical accelerators is a name sug- gested by one of us for devices that produce beams of chemically interesting species at relative kinetic

Zare, Richard N.

418

Accelerating Spectrum Sharing Technologies  

SciTech Connect

Spectrum sharing potentially holds the promise of solving the emerging spectrum crisis. However, technology innovators face the conundrum of developing spectrum sharing technologies without the ability to experiment and test with real incumbent systems. Interference with operational incumbents can prevent critical services, and the cost of deploying and operating an incumbent system can be prohibitive. Thus, the lack of incumbent systems and frequency authorization for technology incubation and demonstration has stymied spectrum sharing research. To this end, industry, academia, and regulators all require a test facility for validating hypotheses and demonstrating functionality without affecting operational incumbent systems. This article proposes a four-phase program supported by our spectrum accountability architecture. We propose that our comprehensive experimentation and testing approach for technology incubation and demonstration will accelerate the development of spectrum sharing technologies.

Juan D. Deaton; Lynda L. Brighton; Rangam Subramanian; Hussein Moradi; Jose Loera

2013-09-01

419

17 GHz High Gradient Accelerator Research  

SciTech Connect

This is a report on the MIT High Gradient Accelerator Research program which has included: Operation of the 17 GHz, 25 MeV MIT/Haimson Research Corp. electron accelerator at MIT, the highest frequency, stand-alone accelerator in the world; collaboration with members of the US High Gradient Collaboration, including the design and test of novel structures at SLAC at 11.4 GHz; the design, construction and testing of photonic bandgap structures, including metallic and dielectric structures; the investigation of the wakefields in novel structures; and the training of the next generation of graduate students and postdoctoral associates in accelerator physics.

Temkin, Richard J. [MIT] [MIT; Shapiro, Michael A. [MIT] [MIT

2013-07-10

420

Testing.  

ERIC Educational Resources Information Center

Seven short articles on the use of standardized tests in the United States are presented. Topics include: (1) the effects on school restructuring during the 1990's of the backlash against standardized tests; (2) the movement to replace multiple-choice standardized testing and its relationship with curricular goals; (3) the influence of…

McCurdy, Jack, Ed.; Speich, Don

1991-01-01

421

46 CFR 164.018-11 - Approval tests.  

Code of Federal Regulations, 2013 CFR

...6) Resistance to accelerated weathering test method and subtest methods...reflective intensity after accelerated weathering,” “reflective intensity during rainfall...adhesion after accelerated weathering.” (The “adhesion after...

2013-10-01

422

46 CFR 164.018-11 - Approval tests.  

Code of Federal Regulations, 2010 CFR

...6) Resistance to accelerated weathering test method and subtest methods...reflective intensity after accelerated weathering,” “reflective intensity during rainfall...adhesion after accelerated weathering.” (The “adhesion after...

2010-10-01

423

46 CFR 164.018-11 - Approval tests.  

Code of Federal Regulations, 2012 CFR

...6) Resistance to accelerated weathering test method and subtest methods...reflective intensity after accelerated weathering,” “reflective intensity during rainfall...adhesion after accelerated weathering.” (The “adhesion after...

2012-10-01

424

46 CFR 164.018-11 - Approval tests.  

Code of Federal Regulations, 2011 CFR

...6) Resistance to accelerated weathering test method and subtest methods...reflective intensity after accelerated weathering,” “reflective intensity during rainfall...adhesion after accelerated weathering.” (The “adhesion after...

2011-10-01

425

Converting an AEG Cyclotron to H? Acceleration and Extraction  

NASA Astrophysics Data System (ADS)

Clinical Trials are under way to evaluate agents labeled with the nuclide 225Ac and its decay product 213Bi, in targeted alpha-immuno-therapy [1]. 225Ac can be produced on a medium-energy cyclotron via the nuclear reaction 226Ra(p,n)225Ac. To demonstrate proof-of-principle, a vintage AEG cyclotron, Model E33 [2], with an internal target, had been employed in a pilot production program at the Technical University of Munich (TUM). To enhance production capability and further support the clinical studies, the TUM facility has recently been refurbished and upgraded, adding a new external beam-line, automated target irradiation and transport systems, new laboratories, hot cells, etc. [3]. An improved high-power rotating target has been built and installed [4]. The AEG cyclotron itself has also been modified and upgraded to accelerate and extract H? ions. We have designed, built, and tested a new axial Penning-type ion source which is optimized for the production of H? ions. The ion source has continued to evolve through experiment and experience. Steady improvements in materials and mechanics have led to enhanced source stability, life-time, and H? production. We have also designed and built a precision H? charge-exchange beam-extraction system which is equipped with a vacuum lock. To fit within the tight mechanical constraint imposed by the narrow magnet gap, the system incorporates a novel chain-drive foil holder and foil-changer mechanism. The reconfigured cyclotron system has now been in operation for more than 1 year. Three long-duration target irradiations have been conducted. The most recent bombardment ran 160 continuous hours at a beam on target of ˜80 microamperes for a total yield of ˜70 milli-curies of 225Ac.

Ramsey, Fred; Carroll, Lewis; Rathmann, Tom; Huenges, Ernst; Bechtold, Matthias Mentler Volker

2009-03-01

426

Reliability Prediction Based on an Accelerated Degradation Rate Model  

Microsoft Academic Search

Accelerated degradation testing (ADT) is an alternative to accelerated life testing (ALT) with censoring to estimate reliability without waiting for actual failures to occur. We propose an ADT model that generalizes the Geometric Brownian Motion Degradation Rate (GBMDR) model by considering explanatory covariates. We intend to utilize this model to predict products' service reliability by using accelerated degradation data. A

E. A. Elsayed; H. T. Liao

427

Wakefield Acceleration in Structures  

Microsoft Academic Search

Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are

M. E. Conde

2002-01-01

428

High-Intensity Proton Accelerator  

SciTech Connect

Analysis is presented for an eight-cavity proton cyclotron accelerator that could have advantages as compared with other accelerators because of its potentially high acceleration gradient. The high gradient is possible since protons orbit in a sequence of TE111 rotating mode cavities of equally diminishing frequencies with path lengths during acceleration that greatly exceed the cavity lengths. As the cavities operate at sequential harmonics of a basic repetition frequency, phase synchronism can be maintained over a relatively wide injection phase window without undue beam emittance growth. It is shown that use of radial vanes can allow cavity designs with significantly smaller radii, as compared with simple cylindrical cavities. Preliminary beam transport studies show that acceptable extraction and focusing of a proton beam after cyclic motion in this accelerator should be possible. Progress is also reported on design and tests of a four-cavity electron counterpart accelerator for experiments to study effects on beam quality arising from variations injection phase window width. This device is powered by four 500-MW pulsed amplifiers at 1500, 1800, 2100, and 2400 MHz that provide phase synchronous outputs, since they are driven from a with harmonics derived from a phase-locked 300 MHz source.

Jay L. Hirshfield

2011-12-27

429

Wakefield acceleration in structures.  

SciTech Connect

Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are presented, and the dielectric wakefield acceleration results are briefly summarized. Possible variants of the two beam accelerator configuration are discussed, and work on planar dielectric structures in various institutions is presented. We conclude this report mentioning prospective achievements of dielectric wakefield accelerating structures.

Conde, M. E.

2002-09-17

430

Wakefield Acceleration in Structures  

NASA Astrophysics Data System (ADS)

Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are presented, and the dielectric wakefield acceleration results are briefly summarized. Possible variants of the two beam accelerator configuration are discussed, and work on planar dielectric structures in various institutions is presented. We conclude this report mentioning prospective achievements of dielectric wakefield accelerating structures.

Conde, M. E.

2002-01-01

431

Wakefield Acceleration in Structures  

NASA Astrophysics Data System (ADS)

Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are presented, and the dielectric wakefield acceleration results are briefly summarized. Possible variants of the two beam accelerator configuration are discussed, and work on planar dielectric structures in various institutions is presented. We conclude this report mentioning prospective achievements of dielectric wakefield accelerating structures.

Conde, Manoel E.

2002-12-01

432

Electron Accelerators for Environmental Protection  

NASA Astrophysics Data System (ADS)

This article gives an overview of existing and possible electron accelerator applications for environmental pollution control. Laboratory and pilot plant tests and industrial applications have illustrated the possibility of applying this technology for purification and treatment of gaseous, liquid, and solid wastes. Examples of ionizing radiation application to protect the environment and human health are discussed.

Chmielewski, Andrzej G.

2011-02-01

433

Propellant reorientation with off-axis accelerations  

NASA Technical Reports Server (NTRS)

Reorientation of propellant within a tank is important to the design of many acquisition and vent systems. A drop tower test program was conducted to determine the influence of off-axis accelerations on the motion of the liquid. A series of 39 tests was performed with a spherical tank and a cylindrical tank with hemispherical end domes, varying tank orientation, liquid volume and the magnitude of the acceleration. It was shown that reorientation under the effect of a pure axial acceleration, which has been studied in prior test programs, is a special case. The lateral component of the acceleration caused the liquid to reorient along one side of the tank. The motion of the liquid appeared to be independent of the magnitude of the lateral acceleration for the range of values considered.

Tegart, J.

1975-01-01

434

Determinants of multiple measures of acceleration  

SciTech Connect

Statistical analyses of the acceleration capability of gasoline vehicles have focused on zero to 97 km/h acceleration rates and have concluded that peak power per kilogram is an appropriate single surrogate for acceleration capability. In this paper, statistical methods are used with data for 107 vehicles tested and reported by Consumers Union for 1986--1988 model years to estimate the determinants of contemporary gasoline vehicle acceleration capability under various conditions, adding new variables to the statistical tests reported by others. Like previous studies, this analysis determined that power and weight provide the most information about acceleration capability. Using a model formulation unlike other studies, this study found that engine displacement also provides statistically significant improvements in explanation of 0-48, 0-97, and 48-97 km/h acceleration times. The coefficients of the equations imply that the use of smaller displacement engines, holding peak power constant, diminishes start-up and 0-97 km/h acceleration capability. A separate equation is estimated to illustrate the effects of advanced engine technologies on displacement, controlling for power. This equation is used in conjunction with the acceleration equations to illustrate a method of estimating performance-equivalent engine substitutions when engine technologies change. Transmission type was important for start-up acceleration, with automatic-transmission-equipped vehicles being significantly slower than stick-shift-equipped vehicles. Fuel injection was found to significantly improve start-up acceleration. Variables proxying aerodynamic-drag effects tended to be significant determinants of acceleration in the higher-speed equations, but not for start-up acceleration. Estimated aerodynamic drag effects indicated that drag slows down 0-97, 48-97, and 72-105 km/h acceleration of pickup trucks and sport utility vehicles more than passenger cars and vans.

Santini, D.J.; Anderson, J.

1993-08-01

435

Using accelerated life testing procedures to compare the relative sensitivity of rainbow trout and the federally listed threatened bull trout to three commonly used rangeland herbicides (picloram, 2,4-D, and clopyralid).  

PubMed

We conducted 96-h static acute toxicity studies to evaluate the relative sensitivity of juveniles of the threatened bull trout (Salvelinus confluentus) and the standard cold-water surrogate rainbow trout (Onchorhyncus mykiss) to three rangeland herbicides commonly used for controlling invasive weeds in the northwestern United States. Relative species sensitivity was compared using three procedures: standard acute toxicity testing, fractional estimates of lethal concentrations, and accelerated life testing chronic estimation procedures. The acutely lethal concentrations (ALC) resulting in 50% mortality at 96 h (96-h ALC50s) were determined using linear regression and indicated that the three herbicides were toxic in the order of picloram acid > 2,4-D acid > clopyralid acid. The 96-h ALC50 values for rainbow trout were as follows: picloram, 41 mg/L; 2.4-D, 707 mg/L; and clopyralid, 700 mg/L. The 96-h ALC50 values for bull trout were as follows: picloram, 24 mg/L; 2.4-D, 398 mg/L; and clopyralid, 802 mg/L. Fractional estimates of safe concentrations, based on 5% of the 96-h ALC50, were conservative (overestimated toxicity) of regression-derived 96-h ALC5 values by an order of magnitude. Accelerated life testing procedures were used to estimate chronic lethal concentrations (CLC) resulting in 1% mortality at 30 d (30-d CLC1) for the three herbicides: picloram (1 mg/L rainbow trout, 5 mg/L bull trout), 2,4-D (56 mg/L rainbow trout, 84 mg/L bull trout), and clopyralid (477 mg/L rainbow trout; 552 mg/L bull trout). Collectively, the results indicated that the standard surrogate rainbow trout is similar in sensitivity to bull trout. Accelerated life testing procedures provided cost-effective, statistically defensible methods for estimating safe chronic concentrations (30-d CLC1s) of herbicides from acute toxicity data because they use statistical models based on the entire mortality:concentration:time data matrix. PMID:17975948

Fairchild, James F; Allert, Ann; Sappington, Linda S; Nelson, Karen J; Valle, Janet

2008-03-01

436

The Accelerator Principle--Development and Evidence.  

ERIC Educational Resources Information Center

Intended as an aid to college level economics teachers, this article traces the theoretical development of the accelerator principle, as applied to investment theory. It also reviews the many investment theories that have utilized the accelerator principle for empirical testing and summarizes some of their findings. (Author/RM)

Robins, Philip

1984-01-01

437

Laser-produced plasmas and hypervelocity acceleration  

NASA Astrophysics Data System (ADS)

Laser produced plasmas have properties that overlap those of armatures required for hypervelocity particle acceleration. This makes them useful as a test bed for advanced acceleration schemes and effects. In addition, sophisticated diagnostics have been developed for measuring laser produced plasma conditions; many of these techniques can be applied or adapted to KEW armature problems.

Ripin, Barrett H.

1987-05-01

438

GPApriori: GPU-Accelerated Frequent Itemset Mining  

E-print Network

GPApriori: GPU-Accelerated Frequent Itemset Mining Fan Zhang Department of Computer Science describe GPApriori, a GPU- accelerated implementation of Frequent Itemset Mining (FIM). We tested our step on the GPU. Experimental results show that GPApriori consistently outperforms CPU-based Apriori

Bakos, Jason D.

439

Statistical Properties of Dissipative MHD Accelerators  

Microsoft Academic Search

We use exact orbit integration to investigate particle acceleration in a Gauss field proxy of magnetohydrodynamic (MHD) turbulence. Regions where the electric current exceeds a critical threshold are declared to be `dissipative' and endowed with super-Dreicer electric field ${\\\\bf E}_\\\\Omega = \\\\eta {\\\\bf j}$. In this environment, test particles (electrons) are traced and their acceleration to relativistic energies is studied.

Kaspar Arzner; Loukas Vlahos; Bernard Knaepen; Nicolas Denewet

2005-01-01

440

Accelerator development for heavy ion fusion  

SciTech Connect

Accelerator technology development is presented for heavy ion drivers used in inertial confinement fusion. The program includes construction of low-velocity ''test bed'' accelerator facilities, development of analytical and experimental techniques to characterize ion beam behavior, and the study of ion beam energy deposition.

Talbert, W.L. Jr.; Sawyer, G.A.

1980-01-01

441

Accelerated Reader. What Works Clearinghouse Intervention Report  

ERIC Educational Resources Information Center

"Accelerated Reader" is a computer-based reading management system designed to complement an existing classroom literacy program for grades pre-K-12. It is designed to increase the amount of time students spend reading independently. Students choose reading-level appropriate books or short stories for which Accelerated Reader tests are available…

What Works Clearinghouse, 2009

2009-01-01

442

Materials Testing for an Accelerator-Driven Subcritical Molten Salt Fission System: A look at the Materials Science of Molten Salt Corrosion  

NASA Astrophysics Data System (ADS)

For an accelerator-driven subcritical molten salt fission core to survive its 50+ year fuel life, the primary vessel, heat exchanger, and various internal components must be made of materials that resist corrosion and radiation damage in a high-temperature environment, (500-800 C). An experimental study of the corrosion behavior of candidate metals in contact with molten salt is being conducted at the Center for Advanced Energy Studies. Initial experiments have been run on Nb, Ta, Ni, two zirconium alloys, Hastelloy-N, and a series of steel alloys to form a base line for corrosion in both chloride and bromide salt. Metal coupons were immersed in LiCl-KCl or LiBr-KBr at 700 C in an inert-atmosphere. Salt samples were extracted on a time schedule over a 24-hr period. The samples were analyzed using inductively coupled plasma-mass spectrometry to determine concentrations of metals from corrosion. Preliminary results will be presented.

Sooby, Elizabeth; Balachandran, Shreyas; Foley, David; Hartwig, Karl; McIntyre, Peter; Phongikaroon, Supathorn; Pogue, Nathaniel; Simpson, Michael; Tripathy, Prabhat

2011-10-01

443

Technology of magnetically driven accelerators  

SciTech Connect

The marriage of Induction Linac technology with Nonlinear Magnetic Modulators has produced some unique capabilities. It appears possible to produce electron beams with average currents measured in amperes, at gradients exceeding 1 MeV/meter, and with power efficiencies approaching 50%. A 2 MeV, 5 kA electron accelerator has been constructed at the Lawrence Livermore National Laboratory (LLNL) to demonstrate these concepts and to provide a test facility for high brightness sources. The pulse drive for the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak power capability, repetition rates exceeding a kilohertz and excellent reliability. 8 figs., 1 tab.

Birx, D.L.; Hawkins, S.A.; Poor, S.E.; Reginato, L.L.; Rogers, D. Jr.; Smith, M.W.

1985-03-26

444

TURBULENT SHEAR ACCELERATION  

SciTech Connect

We consider particle acceleration by large-scale incompressible turbulence with a length scale larger than the particle mean free path. We derive an ensemble-averaged transport equation of energetic charged particles from an extended transport equation that contains the shear acceleration. The ensemble-averaged transport equation describes particle acceleration by incompressible turbulence (turbulent shear acceleration). We find that for Kolmogorov turbulence, the turbulent shear acceleration becomes important on small scales. Moreover, using Monte Carlo simulations, we confirm that the ensemble-averaged transport equation describes the turbulent shear acceleration.

Ohira, Yutaka, E-mail: ohira@phys.aoyama.ac.jp [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-5258 (Japan)

2013-04-10

445

Current limits in linear accelerators  

NASA Astrophysics Data System (ADS)

In recent years considerable interest has developed in the use of linear accelerators for various high-current applications (radiation testing facilities, neutron spallation sources, heavy-ion fusion, etc.). The beam dynamics and current limits in a linear accelerator are determined largely by the periodicity and phase-space acceptance of the external focusing system and the particle oscillation frequencies (or phase shifts per focusing period), both without the space-charge forces and with the space-charge forces of the particle bunch. General formulas for the transverse and longitudinal current limits in terms of these fundamental quantities are derived. The relationships with the actual accelerator and particle beam parameters are examined for strong (quadrupole) and weak focusing field configurations. As a practical illustration, the results are applied to a drift-tube linac with quadrupole focusing in the transverse direction and rf phase focusing in the longitudinal direction.

Reiser, M.

1981-02-01

446

Rail accelerator technology and applications  

NASA Technical Reports Server (NTRS)

Rail accelerators offer a viable means of launching ton-size payloads from the Earth's surface to space. The results of two mission studies which indicate that an Earth-to-Space Rail Launcher (ESRL) system is not only technically feasible but also economically beneficial, particularly when large amounts of bulk cago are to be delivered to space are given. An in-house experimental program at the Lewis Research Center (LeRC) was conducted in parallel with the mission studies with the objective of examining technical feasibility issues. A 1 m long - 12.5 by 12.5 mm bore rail accelerator as designed with clear polycarbonate sidewalls to visually observe the plasma armature acceleration. The general character of plasma/projectile dynamics is described for a typical test firing.

Zana, L. M.; Kerslake, W. R.

1985-01-01

447

A non-linear, passive, model of the leg drop pendulum test: assessing changes in spastic cerebral palsy after vertical accelerations  

Microsoft Academic Search

Reports on the use of a passive, second order non-linear model of the leg drop pendulum test as a means of gaining insight into a therapeutic intervention in spastic cerebral palsy. Optimization techniques are used to adjust model parameters, such that model data fits actual data. Actual data is taken from a set of triplets, two of which have varying

1994-01-01

448

Minimum accelerations from quantised inertia  

E-print Network

It has recently been observed that there are no disc