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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

Accelerated test program  

NASA Technical Reports Server (NTRS)

A brief discussion on the accelerated testing of batteries is given. The statistical analysis and the various aspects of the modeling that was done and the results attained from the model are also briefly discussed.

Ford, F. E.; Harkness, J. M.

1977-01-01

3

Accelerated testing of space batteries  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

4

Accelerated Stress-Corrosion Testing  

NASA Technical Reports Server (NTRS)

Test procedures for accelerated stress-corrosion testing of high-strength aluminum alloys faster and provide more quantitative information than traditional pass/fail tests. Method uses data from tests on specimen sets exposed to corrosive environment at several levels of applied static tensile stress for selected exposure times then subsequently tensile tested to failure. Method potentially applicable to other degrading phenomena (such as fatigue, corrosion fatigue, fretting, wear, and creep) that promote development and growth of cracklike flaws within material.

1986-01-01

5

Experimental test accelerator (ETA) II  

SciTech Connect

The Experimental Test Accelerator (ETA) is designed to produce a 10 kAmp electron beam at an energy of 4.5 MeV in 40 nsec pulses at an average rate of 2 pps. The accelerator also operates in bursts of 5 pulses spaced by as little as one millisec at an average rate of 5 pps. The machine is currently operating near 80% of its design values and has accumulated over 2.5 million pulses - mostly at a rate of one pps. The plasma cathode electron source, the remainder of the accelerator, and the operating characteristics of the machine are discussed.

Fessenden, T.J.; Atchison, W.L.; Birx, D.L.

1981-03-06

6

Accelerated Testing Validation  

SciTech Connect

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

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

2011-07-01

7

Accelerated leach test development program  

SciTech Connect

In FY 1989, a draft accelerated leach test for solidified waste was written. Combined test conditions that accelerate leaching were validated through experimental and modeling efforts. A computer program was developed that calculates test results and models leaching mechanisms. This program allows the user to determine if diffusion controls leaching and, if this is the case, to make projections of releases. Leaching mechanisms other than diffusion (diffusion plus source term partitioning and solubility limited leaching) are included in the program is indicators of other processes that may control leaching. Leach test data are presented and modeling results are discussed for laboratory scale waste forms composed of portland cement containing sodium sulfate salt, portland cement containing incinerator ash, and vinyl ester-styrene containing sodium sulfate. 16 refs., 38 figs., 5 tabs.

Fuhrmann, M.; Pietrzak, R.F.; Heiser, J.; Franz, E.M.; Colombo, P.

1990-11-01

8

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

9

Focusing on accelerated life testing for cylinders  

Microsoft Academic Search

The study of accelerated life test on cylinders for pneumatic industry is covered in this paper. Accelerated life testing is valuable tools to get information quickly on life distribution which is achieved by subjecting the test units to conditions that are more severe than the normal ones. Long lifetime pneumatic cylinders are selected as the test object. Section I covers

Juan Chen; Jungong Ma; Zhanlin Wang; Andreas Wank

2008-01-01

10

DARHT II Scaled Accelerator Tests on the ETA II Accelerator  

Microsoft Academic Search

The DARHT II accelerator at LANL is preparing a series of preliminary tests at the reduced voltage of 7.8 Me V. The transport hardware between the end of the accelerator and the final target magnet was shipped to LLNL and installed on ETA II. Using the ETA II beam at 5.2 MeV we completed a set of experiments designed reduce

J. T. Weir; E M Anaya Jr; G. J. Caporaso; F. W. Chambers; Yu-Jiuan Chen; S. Falabella; B. S. Lee; A. C. Paul; B. A. Raymond; R. A. Richardson; J. A. Watson; D. Chan; H. A. Davis; L. A. Day; R. D. Scarpetti; M. E. Schultze; T. P. Hughes

2005-01-01

11

ACCELERATED EXPOSURE TESTING Accelerated exposure testing has become increasingly  

E-print Network

for applications such as metal corrosion and protective coatings Atmospheric exposure testing of equipment salt solution, and ultraviolet radiation can be programmed dynamically to test requirements. A process environments simulation Corrosion evaluation and mitigation technologies Thermal stability testing Thermal

Chapman, Clark R.

12

Test of pulsar acceleration mechanisms  

Microsoft Academic Search

The veracity of various acceleration mechanisms proposed to explain the high velocities of pulsars is assessed on the basis of the relative orientation of the projected direction of the spin axis (S) and the observed direction of motion of the pulsar (V). The spin axis projected direction is obtained from the intrinsic angle of polarization of the radio emission at

D. Morris; V. Radhakrishnan; C. Shukre

1976-01-01

13

RHIC sextant test: Accelerator systems and performance  

SciTech Connect

One sextant of the RHIC Collider was commissioned in early 1997 with beam. We describe here the performance of the accelerator systems, instrumentation subsystems and application software. We also describe a ramping test without beam that took place after the commissioning with beam. Finally, we analyze the implications of accelerator systems performance and their impact on the planning for RHIC installation and commissioning.

Pilat, F.; Trbojevic, D.; Ahrens, L. [and others

1997-08-01

14

Solid oxide materials research accelerated electrochemical testing  

SciTech Connect

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

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

1995-12-31

15

DARHT II Scaled Accelerator Tests on the ETA II Accelerator*  

SciTech Connect

The DARHT II accelerator at LANL is preparing a series of preliminary tests at the reduced voltage of 7.8 MeV. The transport hardware between the end of the accelerator and the final target magnet was shipped to LLNL and installed on ETA II. Using the ETA II beam at 5.2 MeV we completed a set of experiments designed reduce start up time on the DARHT II experiments and run the equipment in a configuration adapted to the reduced energy. Results of the beam transport using a reduced energy beam, including the kicker and kicker pulser system will be presented.

Weir, J T; Anaya Jr, E M; Caporaso, G J; Chambers, F W; Chen, Y; Falabella, S; Lee, B S; Paul, A C; Raymond, B A; Richardson, R A; Watson, J A; Chan, D; Davis, H A; Day, L A; Scarpetti, R D; Schultze, M E; Hughes, T P

2005-05-26

16

46 CFR 160.072-5 - Accelerated weathering test.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 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...

2010-10-01

17

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

18

46 CFR 160.072-5 - Accelerated weathering test.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 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...

2014-10-01

19

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

20

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

21

Focusing on accelerated life testing for cylinders  

NASA Astrophysics Data System (ADS)

The study of accelerated life test on cylinders for pneumatic industry is covered in this paper. Accelerated life testing is valuable tools to get information quickly on life distribution which is achieved by subjecting the test units to conditions that are more severe than the normal ones. Long lifetime pneumatic cylinders are selected as the test object. Section I covers the fault mechanism analysis, the piston and piston pole parking are the weak units as they are movable parts as well as leakage sources which easily result in the cylinders failure. Liquid temperature and operating frequency are chosen as stresses since their accelerating potentials are available for the specific cylinders. The complete ALT data is presented using Weibull distribution. Estimation for the parameters of failure model and other characteristics of cylinders population life distribution are done successfully. From the 3-axis graph plotted, the effects of each stresses to cylinders can be seen clearly which provide useful results for cylinders researcher and developer.

Chen, Juan; Ma, Jungong; Wang, Zhanlin; Wank, Andreas

2008-10-01

22

RHIC sextant test: Accelerator systems and performance  

Microsoft Academic Search

One sextant of the RHIC Collider was commissioned in early 1997 with beam. We describe here the performance of the accelerator systems during the test, such as the mag-net and power supply systems, instrumentation subsystems and application software. We also describe a ramping test without beam that took place after the commissioning with beam. Finally, we analyze the implications of

F. Pilat

1998-01-01

23

RHIC Sextant Test - Accelerator Systems and Performance  

NASA Astrophysics Data System (ADS)

One sextant of the RHIC collider and the full AtR (AGS to RHIC) transfer line have been commissioned in early 1997 with beam. We describe here the design and performance of the accelerator systems during the test, such as the magnet and power supply systems, instrumentation subsystems and application software. After reviewing the main milestones of the commissioning we describe a ramping test without beam that took place after the commissioning with beam. Finally, we analyze the implications of accelerator systems preformance and their impact on the plannig for RHIC installation and commissioning.

Pilat, F.; Ahrens, L.; Brown, K.; Connolly, R.; dell, G. F.; Fischer, W.; Kewisch, J.; Mackay, W.; Mane, V.; Peggs, S.; Satogata, T.; Tepikian, S.; Thompson, P.; Trbojevic, D.; Tsoupas, N.; Wei, J.

1997-05-01

24

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

25

BNL ACCELERATOR TEST FACILITY CONTROL SYSTEM UPGRADE.  

SciTech Connect

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

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

2001-06-18

26

Testing a combined vibration and acceleration environment.  

SciTech Connect

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

Jepsen, Richard Alan; Romero, Edward F.

2005-01-01

27

Test particle acceleration by rotating jet magnetospheres  

E-print Network

Centrifugal acceleration of charged test particles at the base of a rotating jet magnetosphere is considered. Based on an analysis of forces we derive the equation for the radial accelerated motion and present an analytical solution. It is shown that for particles moving outwards along rotating magnetic field lines, the energy gain is in particular limited by the breakdown of the bead-on-the-wire approximation which occurs in the vicinity of the light cylinder $r_{L}$. The corresponding upper limit for the maximum Lorentz factor $\\gamma_{max}$ for electrons scales $\\propto B^{2/3} r_{L}^{2/3}$, with $B$ the magnetic field strength at $r_{L}$, and is at most of the order of a $10^2-10^3$ for the conditions regarded to be typical for BL Lac objects. Such values suggest that this mechanism may provide pre-accelerated seed particles which are required for efficient Fermi-type particle acceleration at larger scales in radio jets.

F. M. Rieger; K. Mannheim

2000-11-01

28

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

29

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

2010-10-11

30

Accelerated Strength Testing of Thermoplastic Composites  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

31

Fault mechanism analysis and accelerate life testing for pneumatic cylinders  

Microsoft Academic Search

This paper focuses on accelerated life test on cylinders for pneumatic industry which sharply shortens the test time to get the reliability evaluation specification and decreases the cost during products development stage. Accelerated tests are valuable tools to get information quickly on life distribution which is achieved by subjecting the test units to conditions that are more severe than the

Chen Juan; Ma Jungong; Wu Qiang

2008-01-01

32

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

33

Multiple Stress Effect Analysis on Pneumatic Cylinders Accelerated Life Testing  

Microsoft Academic Search

Accelerated life testing is a valuable tool to get information quickly on lifetime distribution which is achieved by subjecting the test units to conditions that are more severe than the normal ones. This paper firstly describes a model for multiple stress-type accelerated life data which is based on the widely known log-linear model and is formulated with Weibull model for

Chen Juan; Wang Deyi; Wu Qiang; Wang Zhanlin

2009-01-01

34

Terrestrial Photovoltaic Module Accelerated Test-To-Failure Protocol  

SciTech Connect

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

Osterwald, C. R.

2008-03-01

35

Accelerated life testing effects on CMOS microcircuit characteristics  

NASA Technical Reports Server (NTRS)

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

1980-01-01

36

Apparatus for accelerated degradation testing of concrete specimens  

Microsoft Academic Search

To simulate chemical degradation of concrete in an automated and standardized way, an apparatus for accelerated degradation\\u000a tests was developed. Because alternated wetting and drying often accelerate concrete degradation, cylindrical test specimens\\u000a are subjected to a cyclic procedure of turning through an aggressive solution and drying by air. After every attack cycle\\u000a the test specimens are brushed with rotary brushes

N. De Belie; J. Monteny; L. Taerwe

2002-01-01

37

Testing general relativity with laser accelerated electron beams  

SciTech Connect

Electron accelerations of the order of 10{sup 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.

Gergely, L. A.; Harko, T. [Department of Theoretical Physics, University of Szeged, Szeged 6720, Tisza L. krt. 84, Hungary and Department of Experimental Physics, University of Szeged, 6720 Szeged, Dom ter 9 (Hungary); Department of Physics and Center for Theoretical and Computational Physics, University of Hong Kong, Pok Fu Lam Road (Hong Kong)

2012-07-09

38

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

39

Beam Physics of Integrable Optics Test Accelerator at Fermilab  

SciTech Connect

Fermilab's Integrable Optics Test Accelerator (IOTA) is an electron storage ring designed for testing advanced accelerator physics concepts, including implementation of nonlinear integrable beam optics and experiments on optical stochastic cooling. The machine is currently under construction at the Advanced Superconducting Test Accelerator facility. In this report we present the goals and the current status of the project, and describe the details of machine design. In particular, we concentrate on numerical simulations setting the requirements on the design and supporting the choice of machine parameters.

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

2012-05-01

40

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

41

Significance of acceleration period in a dynamic strength testing study.  

PubMed

The acceleration period that occurs during isokinetic tests may provide valuable information regarding neuromuscular readiness to produce maximal contraction. The purpose of this study was to collect the normative data of acceleration time during isokinetic knee testing, to calculate the acceleration work (Wacc), and to determine the errors (ERexp, ERwork, ERpower) due to ignoring Wacc during explosiveness, total work, and average power measurements. Seven male and 13 female subjects attended the test by using the Cybex 325 system and electronic stroboscope machine for 10 testing speeds (30-300 degrees/sec). A three-way ANOVA was used to assess gender, direction, and speed factors on acceleration time, Wacc, and errors. The results indicated that acceleration time was significantly affected by speed and direction; Wacc and ERexp by speed, direction, and gender; and ERwork and ERpower by speed and gender. The errors appeared to increase when testing the female subjects, during the knee flexion test, or when speed increased. To increase validity in clinical testing, it is important to consider the acceleration phase effect, especially in higher velocity isokinetic testing or for weaker muscle groups. PMID:8025571

Chen, W L; Su, F C; Chou, Y L

1994-06-01

42

The Accelerator Test Facility at Brookhaven: Main capabilities  

NASA Astrophysics Data System (ADS)

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

Yakimenko, Vitaly

2004-12-01

43

Testing pulse forming networks with DARHT accelerator cells  

SciTech Connect

The Dual Axis Radiographic Hydrotest Facility [DARHT] at Los Alamos will use two induction linacs to produce high-energy electron beams. The electron beams will be used to generate x-rays from bremsstrahlung targets. The x-rays will be used to produce radiographs. The first accelerator is operational now, generating a 60-nanosecond electron beam. The second accelerator is under construction. It will generate a 2-microsecond electron beam. The 78 induction cells of the second axis accelerator will be driven by an equal number of pulse forming networks. Each pulse forming network [PFN] generates a nominal 200-kV, 2-microsecond pulse to drive an accelerator cell. Each pulse forming network consists of a set of four equal-capacitance sub-PFN's, stacked in a Marx configuration. The PFN Test Stand was configured to test newly constructed accelerator cells under conditions of full voltage and pulse duration. The PFN Test Stand also explored jitter, prefire and reliability issues for a pulse forming network operated into a purely resistive load. The PFN Test Stand provided experience operating a simple subsystem of the DARHT accelerator. This subsystem involved controls, diagnostics, data acquisition and archival, power supplies, trigger systems, core reset and a gas flow system for the spark gaps. Issues for the DARHT accelerator were investigated in this small-scale facility.

Rose, E. A. (Evan A.); Dalmas, D. A. (Dale Allen); Downing, J. N. (James N.), Jr.; Temple, R. D. (Rodney Dean)

2001-01-01

44

TESTING PULSE FORMING NETWORKS WITH DARHT ACCELERATOR CELLS  

SciTech Connect

The Dual Axis Radiographic Hydrotest Facility [DARHT] at Los Alamos will use two induction linacs to produce high-energy electron beams. The electron beams will be used to generate x-rays from bremsstrahlung targets. The x-rays will be used to produce radiographs. The first accelerator is operational now, generating a 60- nanosecond electron beam. The second accelerator is under construction. It will generate a 2-microsecond electron beam. The 78 induction cells of the second axis accelerator will be driven by an equal number of pulse forming networks. Each pulse forming network [PFN] generates a nominal 200-kV, 2-microsecond pulse to drive an accelerator cell. Each pulse forming network consists of a set of four equal-capacitance sub-PFN's, stacked in a Marx configuration. The PFN Test Stand was configured to test newly constructed accelerator cells under conditions of full voltage and pulse duration. The PFN Test Stand also explored jitter, prefire and reliability issues for a pulse forming network operated into a purely resistive load. The PFN Test Stand provided experience operating a simple subsystem of the DARHT accelerator. This subsystem involved controls, diagnostics, data acquisition and archival, power supplies, trigger systems, core reset and a gas flow system for the spark gaps. Issues for the DARHT accelerator were investigated in this small-scale facility.

E.A. ROSE; D.A. DALMAS; J.N. DOWNING; R.D. TEMPLE

2001-06-01

45

Development of a new accelerated salt crystallization test  

Microsoft Academic Search

, a new accelerated salt crystallization test. In this paper the design process leading to the definition of this test is described. Preliminary tests studying the influence of the environmental conditions on the damage development showed that the use of a high, but still realistic, temperature can enhance salt damage. The use of wet-dry cycles was found to be more

Tomas Wijffels; Barbara Lubelli

2006-01-01

46

Accelerated Life Test for the Embrittlement of Natural Rubber Grommets  

NASA Astrophysics Data System (ADS)

This paper presents an accelerated life test for embrittlement of natural rubber grommets. From the analyses of field samples, it is found that embrittlement is due to the decrease of plasticizer (zinc stearate for natural rubber) in the rubber. To estimate the embrittlement life, an accelerated life test is designed based on a factorial design. Temperature and compression load are selected as accelerating variables, and the hardness is measured for each specimen during the test. An analysis of variance indicates that the significant factor affecting the hardness is not load, but temperature. The embrittlement life and temperature relationship and the acceleration factor are estimated from the failure times using linear degradation model under the assumptions of Weibull lifetime distribution and Arrhenius model.

Kong, Min Gyu; Kim, Jin Woo; Kim, Myung Soo; Jang, Joong Soon; Ryu, Dong Su

47

COMPACT PROTON INJECTOR AND FIRST ACCELERATOR SYSTEM TEST FOR COMPACT PROTON DIELECTRIC WALL CANCER THERAPY ACCELERATOR  

SciTech Connect

A compact proton accelerator for cancer treatment is being developed by using the high-gradient dielectric insulator wall (DWA) technology [1-4]. We are testing all the essential DWA components, including a compact proton source, on the First Article System Test (FAST). The configuration and progress on the injector and FAST will be presented.

Chen, Y; Guethlein, G; Caporaso, G; Sampayan, S; Blackfield, D; Cook, E; Falabella, S; Harris, J; Hawkins, S; Nelson, S; Poole, B; Richardson, R; Watson, J; Weir, J; Pearson, D

2009-04-23

48

Testing of a high current dc ESQ accelerator  

SciTech Connect

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

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

1991-05-01

49

Tungsten Powder as an accelerator target & InBeam Testing  

E-print Network

Programme in PASIWP3 + ASTEC 1 2 3 4 · Offline testing ­ Pneumatic conveying (densephase and leanphase1 Tungsten Powder as an accelerator target & InBeam Testing Ottone Caretta, Peter Loveridge - Reliability in harsh environment? - High static stress levels require much larger beam sigma than baseline

McDonald, Kirk

50

Study of battery accelerated-testing techniques. Final report  

Microsoft Academic Search

Batteries for solar photovoltaic applications and other terrestrial applications require long life in daily cycling regimes. There is a need to develop testing procedures to accelerate aging of electrochemical cells so that cycle life data can be acquired in less time than real time testing would require. The initial emphasis has been on lead-acid type batteries. A literature review and

J. E. Clifford; R. E. Thomas

1982-01-01

51

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

52

On the life time of contrail cirrus  

NASA Astrophysics Data System (ADS)

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

Schumann, U.; Graf, K.

2012-04-01

53

Quick setup of unit test for accelerator controls system  

SciTech Connect

Testing a single hardware unit of an accelerator control system often requires the setup of a program with graphical user interface. Developing a dedicated application for a specific hardware unit test could be time consuming and the application may become obsolete after the unit tests. This paper documents a methodology for quick design and setup of an interface focused on performing unit tests of accelerator equipment with minimum programming work. The method has three components. The first is a generic accelerator device object (ADO) manager which can be used to setup, store, and log testing controls parameters for any unit testing system. The second involves the design of a TAPE (Tool for Automated Procedure Execution) sequence file that specifies and implements all te testing and control logic. The sting third is the design of a PET (parameter editing tool) page that provides the unit tester with all the necessary control parameters required for testing. This approach has been used for testing the horizontal plane of the Stochastic Cooling Motion Control System at RHIC.

Fu, W.; D'Ottavio, T.; Gassner, D.; Nemesure, S.; Morris, J.

2011-03-28

54

TESTING METGLAS FOR USE IN DARHT ACCELERATOR CELLS  

SciTech Connect

The Dual Axis Radiographic Hydrotest Facility [DARHT] at Los Alamos will use two induction linacs to produce high-energy electron beams. The electron beams will be used to generate x-rays from bremsstrahlung targets. The x-rays will be used to produce radiographs. The first accelerator is operational now, producing a 60-nanosecond electron beam. The second accelerator is under construction. It will produce a 2-microsecond electron beam. The 78 induction cells of the second axis accelerator require a total Metglas capacity of approximately 40 volt seconds of flux. Four Metglas cores are used in each of the 5-foot diameter accelerator cells. Each Metglas core weighs approximately 3000 pounds. This paper presents the measurement techniques and results of the Metglas tests. Routine automated analysis and archival of the pulse data provided hysteresis curves, energy loss curves and total flux swing in the operating regime. Results of the tests were used to help the manufacturer improve quality control and increase the average flux swing of the cores. Results of the tests were used to match Metglas cores and to assemble accelerator cells with equal volt-second ratings.

E.A. ROSE; D.A. DALMAS; J.N. DOWNING; R.D. TEMPLE

2001-06-01

55

TESTING METGLAS FOR USE IN DARHT ACCELERATOR CELLS  

SciTech Connect

The Dual Axis Radiographic Hydrotest Facility [DARHT] at Los Alamos will use two induction linacs to produce high-energy electron beams. The electron beams will be used to generate x-rays from bremsstrahlung targets. The x-rays will be used to produce radiographs. The first accelerator is operational now, producing a 60-nanosecond electron beam. The second accelerator is under construction. It will produce a 2-microsecond electron beam. The 78 induction cells of the second axis accelerator require a total Metglas capacity of approximately 40 volt seconds of flux. Four Metglas cores are used in each of the 5-foot diameter accelerator cells. Each Metglas core weighs approximately 3000 pounds. This paper presents the measurement techniques and results of the Metglas tests. Routine automated analysis and archival of the pulse data provided hysteresis curves, energy loss curves and total flux swing in the operating regime. Results of the tests were used to help the manufacturer improve quality control and increase the average flux swing of the cores. Results of the tests were used to match Metglas cores and to assemble accelerator cells with equal volt-second ratings.

Rose, E. A. (Evan A.); Dalmas, D. A. (Dale Allen); Downing, J. N. (James N.), Jr.; Temple, R. D. (Rodney Dean)

2001-01-01

56

ACCELERATED LIFE TESTING: DOES IT SATISFY VRLA USER AND DESIGNER NEEDS?  

Microsoft Academic Search

It is universally accepted that the Arrhenius equation relating temperature to reaction rate can be used to determine VRLA life. To this end normal room temperature life is determined from extrapolation of the high temperature life times. A prerequisite to this test method requires that the reactions occurring at the elevated test temperatures are common to all those at room

Frank Vaccaro; Robert Landwehrle Glen Evans

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

Brookhaven National Laboratory's Accelerator Test Facility: research highlights and plans  

NASA Astrophysics Data System (ADS)

The Accelerator Test Facility (ATF) at Brookhaven National Laboratory has served as a user facility for accelerator science for over a quarter of a century. In fulfilling this mission, the ATF offers the unique combination of a high-brightness 80 MeV electron beam that is synchronized to a 1 TW picosecond CO2 laser. We unveil herein our plan to considerably expand the ATF's floor space with an upgrade of the electron beam's energy to 300 MeV and the CO2 laser's peak power to 100 TW. This upgrade will propel the ATF even further to the forefront of research on advanced accelerators and radiation sources, supporting the most innovative ideas in this field. We discuss emerging opportunities for scientific breakthroughs, including the following: plasma wakefield acceleration studies in research directions already active at the ATF; laser wakefield acceleration (LWFA), where the longer laser wavelengths are expected to engender a proportional increase in the beam's charge while our linac will assure, for the first time, the opportunity to undertake detailed studies of seeding and staging of the LWFA; proton acceleration to the 100-200 MeV level, which is essential for medical applications; and others.

Pogorelsky, I. V.; Ben-Zvi, I.

2014-08-01

59

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

60

Testing a Fourier Accelerated Hybrid Monte Carlo Algorithm  

E-print Network

We describe a Fourier Accelerated Hybrid Monte Carlo algorithm suitable for dynamical fermion simulations of non-gauge models. We test the algorithm in supersymmetric quantum mechanics viewed as a one-dimensional Euclidean lattice field theory. We find dramatic reductions in the autocorrelation time of the algorithm in comparison to standard HMC.

S. Catterall; S. Karamov

2001-12-17

61

Demonstration recommendations for accelerated testing of concrete decontamination methods  

Microsoft Academic Search

A large number of aging US Department of Energy (DOE) surplus facilities located throughout the US require deactivation, decontamination, and decommissioning. Although several technologies are available commercially for concrete decontamination, emerging technologies with potential to reduce secondary waste and minimize the impact and risk to workers and the environment are needed. In response to these needs, the Accelerated Testing of

K. S. Dickerson; M. R. Ally; C. H. Brown; M. I. Morris; M. J. Wilson-Nichols

1995-01-01

62

An Asset Test of the CLIC Accelerating Structure  

Microsoft Academic Search

Transverse wakefield suppression in the CLIC (Compact Linear Collider) multibunch accelerating structure, called the TDS (Tapered Damped Structure), is achieved primarily through heavy damping. In order to verify the performance of the TDS design and the validity of the theoretical tools used to model it, a 15 GHz version of the TDS has been constructed and tested in the ASSET

Claude Achard; C E Adolphsen; M Dehler; E Jensen; M Luong; D McCormick; M Ross; T Slaton; Ian H Wilson; Walter Wuensch

2000-01-01

63

Accelerated life testing : Analysis and optimization Seyyedeh zohreh Fatemi, Fabrice Guerin, Laurent Saintis  

E-print Network

for finding dominant failure mechanisms. Thus, an accelerated Life Test (ALT) is a test method which subjectsAccelerated life testing : Analysis and optimization Seyyedeh zohreh Fatemi, Fabrice Guerin to conduct a sequential test defined by an optimal accelerated testing plan. This test plan is based

Boyer, Edmond

64

Longitudinal bunching of electrons in the Advanced Test Accelerator  

SciTech Connect

The Advanced Test Accelerator (ATA) is a linear induction accelerator for electrons with design goals of 50 MeV and 10 kA. The accelerator consists of a 2.5 to 3 MeV injector and 170 accelerating units, each unit capable of an applied voltage up to 350 kV. At a number of positions in the accelerator, the return current in the beam pipe is measured as a function of time as the beam passes that position. The measuring device, a four quadrant addition, is somewhat sensitive to the transverse position of the beam centroid as well as transverse distribution of current in the beam. Therefore a time-dependent signal may indicate time-dependent transverse motion or beam structure as well as an axial modulation of the beam current. These signals sometimes exhibit spikes and notches on the leading and trailing edges of the beam pulse. The presence of these rapidly varying signals during the rise and fall of the current stimulated this work. 2 references, 4 figures.

Neil, V.K.; Caporaso, G.J.; Paul, A.C.

1984-04-06

65

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

66

Accelerated stress testing of solar photovoltaic modules. Interim report  

SciTech Connect

In 1974, the U.S. Coast Guard began investigating solar photovoltaic arrays as power sources for marine aids to navigation. Initially, 53 systems consisting of a solar array, battery, and a flashing lamp load were placed in a rooftop test facility adjacent to Long Island Sound in Groton, CT. Within two years, the solar arrays of 25 systems had no power output thereby indicating failure. Effects of the marine environment were judged to be responsible for the failures. In order to use solar arrays on operational aids to navigation, much greater reliability was essential. Consequently, development work was initiated on an accelerated stress test system that would rapidly identify solar photovoltaic modules capable of surviving in the marine environment. This interim report traces the history of accelerated stress testing of solar photovoltaic modules carried out at the U.S. Coast Guard RandD Center. It describes the military standard tests to which the prototype modules were exposed to and the results of that exposure. The report traces the evolution of the simultaneous multiple stress test to the present marine environment screening test. The results of exposure to the marine environment screening test of 136 test modules are reported.

Trenchard, S.E.

1981-09-01

67

Reproduction of natural corrosion by accelerated laboratory testing methods  

SciTech Connect

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

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

1996-05-01

68

Accelerated weathering of cementitious matrix for the development of an accelerated laboratory test of biodeterioration  

Microsoft Academic Search

Cement based materials are porous, may contain organic adjuvants, and thus possesses an important primary bioreceptivity.\\u000a To preserve constructions from fungal colonization and to act efficiently against fungal biodeterioration, it is necessary\\u000a to have a better understanding of biodeterioration mechanisms and its effects on materials properties. An accelerated laboratory\\u000a test which allows us to compare the growth of three fungal

Virginie Wiktor; Philippe Grosseau; René Guyonnet; Eric Garcia-Diaz; Christine Lors

2011-01-01

69

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

70

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

71

Testing in a combined vibration and acceleration environment.  

SciTech Connect

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

Jepsen, Richard Alan; Romero, Edward F.

2004-10-01

72

Cooling fan reliability: failure criteria, accelerated life testing, modeling and qualification  

Microsoft Academic Search

Based on field return and test data, the major failure mechanisms and failure modes of cooling fan system are presented in this paper. Then, the failure criteria and the reliability metrics for cooling fan systems are discussed. By critically comparing the accelerated life testing methods from various vendors, a practical accelerated life testing methodology is presented. The acceleration testing models

Xijin Tian

2006-01-01

73

The Accelerator Production of Tritium Materials Test Program  

SciTech Connect

A materials qualification program has been developed to irradiate and test candidate materials (alloy 718, Type 316L, and Type 304L stainless steel, modified Fe9Cr-1Mo(T91), Al-6061-T6, and Al-5052-O) for use in the Accelerator Production of Tritium (APT) target and blanket. The irradiations were performed in prototypic proton and neutron spectra at prototypic temperatures (50 to 160 deg. C). The study used the 800-MeV, 1.0-mA proton accelerator at the Los Alamos Neutron Science Center, which produces a Gaussian beam with 2 sigma = 3 cm. The experiment geometry is arranged to contain near-prototypic modules of the tungsten neutron source and the lead and aluminum blanket as well as mechanical test specimens of candidate APT materials. The particle spectrum varies throughout the irradiation volume; specimens are exposed to protons and a variety of mixed proton and neutron spectra, depending on the specimen's position relative to the beam center. These specimens have been irradiated for >3600 h to a maximum proton fluence of 4 x 10{sup 21} p/cm{sup 2} in the center of the proton beam. Specimens will yield data on the effect of proton irradiation, to high dose, on material properties from tensile tests, three-point bend tests, fracture toughness tests, pressurized tubes, U-bend stress corrosion cracking specimens, corrosion measurements, and microstructural characterization using transmission electron microscopy specimens. Results from these studies are applicable to all spallation neutron sources now in operation and under consideration, including the Spallation Neutron Source, the European Spallation Source, and The Accelerator Transmutation of Waste project.

Maloy, Stuart A.; Sommer, Walter F.; James, Michael R.; Romero, Tobias J.; Lopez, Manuel R.; Zimmermann, Eugene; Ledbetter, James M. [Los Alamos National Laboratory (United States)

2000-10-15

74

Accelerated stress testing of amorphous silicon solar cells  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

75

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

76

Vibrational measurement for commissioning SRF Accelerator Test Facility at Fermilab  

SciTech Connect

The commissioning of two cryomodule components is underway at Fermilab's Superconducting Radio Frequency (SRF) Accelerator Test Facility. The research at this facility supports the next generation high intensity linear accelerators such as the International Linear Collider (ILC), a new high intensity injector (Project X) and other future machines. These components, Cryomodule No.1 (CM1) and Capture Cavity II (CC2), which contain 1.3 GHz cavities are connected in series in the beamline and through cryogenic plumbing. Studies regarding characterization of ground motion, technical and cultural noise continue. Mechanical transfer functions between the foundation and critical beamline components have been measured and overall system displacement characterized. Baseline motion measurements given initial operation of cryogenic, vacuum systems and other utilities are considered.

McGee, M.W.; Leibfritz, J.; Martinez, A.; Pischalnikov, Y.; Schappert, W.; /Fermilab

2011-03-01

77

Improved Accelerated Stress Tests Based on Fuel Cell Vehicle Data  

SciTech Connect

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

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

2012-06-01

78

Testing Einstein's time dilation under acceleration using Mössbauer spectroscopy  

NASA Astrophysics Data System (ADS)

The Einstein time dilation formula was tested in several experiments. Many trials have been conducted to measure the transverse second-order Doppler shift by Mössbauer spectroscopy using a rotating absorber, to test the validity of this formula. Such experiments are also able to test if the time dilation depends only on the velocity of the absorber, as assumed by Einstein's clock hypothesis, or whether the present centripetal acceleration contributes to the time dilation. We show here that because the experiment requires ?-ray emission and detection slits of finite size, the absorption line is broadened, by geometric longitudinal first-order Doppler shifts immensely. Moreover, the absorption line is non-Lorentzian. We obtain an explicit expression for the absorption line for any angular velocity of the absorber. The analysis of the experimental results in all previous experiments which did not observe the full absorption line itself were wrong and the conclusions doubtful. The only proper experiment was done by Kündig (1963 Phys. Rev. 129 2371), who observed the broadening, but associated it with random vibrations of the absorber. We establish necessary conditions for the successful measurement of a transverse second-order Doppler shift by Mössbauer spectroscopy. We indicate how the results of such an experiment can be used to verify the existence of a Doppler shift due to acceleration and to test the validity of Einstein's clock hypothesis.

Friedman, Yaakov; Nowik, Israel

2012-06-01

79

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

80

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

ScienceCinema

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

Andrei Seryi

2010-01-08

81

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

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 Uncertainty Analysis to Guide the Development of Accelerated Stress Tests (Presentation)  

SciTech Connect

Extrapolation of accelerated testing to the long-term results expected in the field has uncertainty associated with the acceleration factors and the range of possible stresses in the field. When multiple stresses (such as temperature and humidity) can be used to increase the acceleration, the uncertainty may be reduced according to which stress factors are used to accelerate the degradation.

Kempe, M.

2014-03-01

85

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

86

Update on lifetime tests results and analysis carried out on Thales Cryogenics integral coolers (RM family)  

NASA Astrophysics Data System (ADS)

The life time tests realised on the serial production of Rotary Mmonoblock RM2 coolers show a measured MTTF of 4900 hours. The conventional test profile applied to these coolers is representative of operation in typical application. The duration of such life time tests is very long. The results of a design change and its impact on MTTF are available only several months after the assembly of the prototypes. We decided to develop a test method in order to reduce the duration of these life time tests. The principle is to define a test protocol easy to implement, more severe than typical application profile in order to accelerate life time tests. The accelerated test profile was defined and tested successfully. This new technique allows us to reduce life time tests costs and duration and thus the costs involved. As a consequence, we decided to have a screening of our production with this accelerated test. This allows us to master continuously the quality of our serial products and to collect additional data. This paper presents the results of life time tests performed on RM2 coolers according to the conventional and accelerated test profiles as well as the first results on the new RM2 design which show a calculated MTTF of 10000 hours.

Cauquil, Jean-Marc; Martin, Jean-Yves; Bruins, Peter; Benschop, A. A. J.

2003-01-01

87

Seeable universe and its accelerated expansion: an observational test  

NASA Astrophysics Data System (ADS)

From the equivalence principle, one gets the strength of the gravitational effect of a mass M on the metric at position r from it. It is proportional to the dimensionless parameter ? 2=2 GM/ rc 2, which normally is ?1. Here G is the gravitational constant, M the mass of the gravitating body, r the position of the metric from the gravitating body and c the speed of light. The seeable universe is the sphere, with center at the observer, having a size such that it shall contain all light emitted within it. For this to occur one can impose that the gravitational effect on the velocity of light at r is zero for the radial component, and non zero for the tangential one. Light is then trapped. The condition is given by the equality R g =2 GM/ c 2, where R g represents the radius of the seeable universe. It is the gravitational radius of the mass M. The result has been presented elsewhere as the condition for the universe to be treated as a black hole. According to present observations, for the case of our universe taken as flat ( k=0), and the equation of state as p=- ?c 2, we prove here from the Einstein's cosmological equations that the universe is expanding in an accelerated way as t 2, a constant acceleration as has been observed. This implies that the gravitational radius of the universe (at the event horizon) expands as t 2. Taking c as constant, observing the galaxies deep in space this means deep in time as ct, linear. Then, far away galaxies from the observer that we see today will disappear in time as they get out of the distance ct that is < R g . The accelerated expanding vacuum will drag them out of sight. This may be a valid test for the present ideas in cosmology. Previous calculations are here halved by our results.

Alfonso-Faus, Antonio; Fullana i Alfonso, Màrius Josep

2013-12-01

88

Integration Test of the High Voltage Hall Accelerator System Components  

NASA Technical Reports Server (NTRS)

NASA Glenn Research Center is developing a 4 kilowatt-class Hall propulsion system for implementation in NASA science missions. NASA science mission performance analysis was completed using the latest high voltage Hall accelerator (HiVHAc) and Aerojet-Rocketdyne's state-of-the-art BPT-4000 Hall thruster performance curves. Mission analysis results indicated that the HiVHAc thruster out performs the BPT-4000 thruster for all but one of the missions studied. Tests of the HiVHAc system major components were performed. Performance evaluation of the HiVHAc thruster at NASA Glenn's vacuum facility 5 indicated that thruster performance was lower than performance levels attained during tests in vacuum facility 12 due to the lower background pressures attained during vacuum facility 5 tests when compared to vacuum facility 12. Voltage-Current characterization of the HiVHAc thruster in vacuum facility 5 showed that the HiVHAc thruster can operate stably for a wide range of anode flow rates for discharge voltages between 250 and 600 volts. A Colorado Power Electronics enhanced brassboard power processing unit was tested in vacuum for 1,500 hours and the unit demonstrated discharge module efficiency of 96.3% at 3.9 kilowatts and 650 volts. Stand-alone open and closed loop tests of a VACCO TRL 6 xenon flow control module were also performed. An integrated test of the HiVHAc thruster, brassboard power processing unit, and xenon flow control module was performed and confirmed that integrated operation of the HiVHAc system major components. Future plans include continuing the maturation of the HiVHAc system major components and the performance of a single-string integration test.

Kamhawi, Hani; Haag, Thomas; Huang, Wensheng; Pinero, Luis; Peterson, Todd; Dankanich, John

2013-01-01

89

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

90

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

91

Accelerated corrosion tests for aerospace materials: current limitations and future trends  

Microsoft Academic Search

Examines accelerated methods for the corrosion testing of materials, coatings and surface treatments used in the aerospace and defence industries. The drawbacks with some current accelerated corrosion tests are examined, particularly the problems experienced with neutral salt spray tests. Specific examples are given which identify the acute discrepancy between salt spray and marine exposure in the corrosion testing of metallic

K. R. Baldwin; C. J. E. Smith

1999-01-01

92

Vibrational Stability of SRF Accelerator Test Facility at Fermilab  

SciTech Connect

Recently developed, the Superconducting Radio Frequency (SRF) Accelerator Test Facilities at Fermilab support the International Linear Collider (ILC), High Intensity Neutrino Source (HINS), a new high intensity injector (Project X) and other future machines. These facilities; Meson Detector Building (MDB) and New Muon Lab (NML) have very different foundations, structures, relative elevations with respect to grade level and surrounding soil composition. Also, there are differences in the operating equipment and their proximity to the primary machine. All the future machines have stringent operational stability requirements. The present study examines both near-field and ambient vibration in order to develop an understanding of the potential contribution of near-field sources (e.g. compressors, ultra-high and standard vacuum equipment, klystrons, modulators, utility fans and pumps) and distant noise sources to the overall system displacements. Facility vibration measurement results and methods of possible isolation from noise sources are presented and discussed.

McGee, M.W.; Volk, J.T.; /Fermilab

2009-05-01

93

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

94

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

95

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

96

Voltage stress effects on microcircuit accelerated life test failure rates  

NASA Technical Reports Server (NTRS)

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

Johnson, G. M.

1976-01-01

97

Preliminary analysis of accelerated space flight ionizing radiation testing  

NASA Astrophysics Data System (ADS)

A preliminary analysis shows that radiation dose equivalent to 30 years in the geosynchronous environment can be accumulated in a typical composite material exposed to space for 2 years or less onboard a spacecraft orbiting from perigee of 300 km out to the peak of the inner electron belt (approximately 2750 km). Future work to determine spacecraft orbits better tailored to materials accelerated testing is indicated. It is predicted that a range of 10 to the 9th power to 10 to the 10th power rads would be accumulated in 3-6 mil thick epoxy/graphite exposed by a test spacecraft orbiting in the inner electron belt. This dose is equivalent to the accumulated dose that this material would be expected to have after 30 years in a geosynchronous orbit. It is anticipated that material specimens would be brought back to Earth after 2 years in the radiation environment so that space radiation effects on materials could be analyzed by laboratory methods.

Wilson, J. W.; Stock, L. V.; Carter, D. J.; Chang, C. K.

1982-01-01

98

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

99

Accelerating estimates of activity-specific metabolic rate in fishes: Testing the applicability of acceleration data-loggers  

Microsoft Academic Search

We report the results of a series of experiments to test the utility of acceleration data-loggers for determining the energy expenditure of juvenile hammerhead sharks (Sphyrna lewini). In one experiment, three sharks were instrumented with miniature acceleration data-loggers and swum in a Brett-style respirometer at a range of speeds. For all three sharks, significant linear relationships were obtained between mean

Adrian C. Gleiss; Jonathan J. Dale; Kim N. Holland; Rory P. Wilson

2010-01-01

100

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

101

Accelerated cyclic corrosion testing of structural steels and its application to assess steel bridge coatings  

Microsoft Academic Search

Purpose – The purpose of this study was to determine correlation between an accelerated cyclic corrosion test (S6-cycle test) specified in Japanese Industrial Standards K5621 and field exposure tests, and to open up applications of the accelerated tests in various regional environments. Design\\/methodology\\/approach – The S6-cycle corrosion test was carried out on structural steels for 30, 60, 90, 120 and

Yoshito Itoh; In-Tae Kim

2006-01-01

102

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

103

Fast Extraction Kicker for the Accelerator Test Facility  

SciTech Connect

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

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

2007-06-20

104

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

105

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

106

Accelerated life testing design based on wear failure mechanism for pneumatic cylinders  

Microsoft Academic Search

The piston and piston pole sealing ring are the weak units as well as leakage sources which easily result in the cylinders failure. The primary criterion for determining test acceleration factors is that the failure mode or failure mechanism should not change or be different from that expected from a non-accelerated test. Working temperature, frequency and motion velocity are chosen

Juan Chen; Qiang Wu; Guochang Bai; Jungong Ma; Zhanlin Wang

2009-01-01

107

Optimum Accelerated Life Test Plans for Log-Location-Scale Distributions with Multiple Objectives  

Microsoft Academic Search

Most of the previous work on planning accelerated life tests (ALTs) is focused on a sole estimating objective, such as some specified 100p-th quantitle lifetime, the reliability of the product over some specified period of time, and accelerating factor. However, it is impossible to estimate only a single objective parameter after conducting such costly tests. In this paper, we consider

Hai-Yan Xu; He-Liang Fei

2009-01-01

108

Testing of a loop heat pipe experimental apparatus under varied acceleration  

E-print Network

An experimental apparatus was designed and fabricated to test a Loop Heat Pipe under varied acceleration. The experiment consisted of both flight and ground testing as well as comparisons to a model developed from models found in literature...

Kurwitz, Richard Cable

2012-06-07

109

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

110

Testing pulse forming networks with DARHT accelerator cells  

Microsoft Academic Search

The Dual Axis Radiographic Hydrotest Facility [DARHT] at Los Alamos will use two induction linacs to produce high-energy electron beams. The electron beams will be used to generate X-rays from bremsstrahlung targets. The X-rays will be used to produce radiographs. The first accelerator is operational now, generating a 60-nanosecond electron beam. The second accelerator is under construction. It will generate

E. A. Rose; D. A. Dalmas; J. N. Downing; R. D. Temple

2001-01-01

111

Testing Metglas for use in DARHT accelerator cells  

Microsoft Academic Search

Summary form only given. The Dual Axis Radiographic Hydrotest Facility [DARHT] at Los Alamos will use two induction linacs to produce high-energy electron beams. The electron beams will be used to generate X-rays from a bremsstrahlung target. Those X-rays will be used to generate radiographs. The first accelerator is operational now, operating with a 60-nanosecond electron beam. The second accelerator

E. A. Rose; D. A. Dalmas; J. N. Downing; R. D. Temple

2001-01-01

112

Testing Metglas for use in DARHT accelerator cells  

Microsoft Academic Search

The Dual Axis Radiographic Hydrotest Facility [DARHT] at Los Alamos will use two induction linacs to produce high-energy electron beams. The electron beams will be used to generate X-rays from bremsstrahlung targets. The X-rays will be used to produce radiographs. The first accelerator is operational now, producing a 60-nanosecond electron beam. The second accelerator is under construction. It will produce

E. A. Rose; D. A. Dalmas; J. N. Downing; R. D. Temple

2001-01-01

113

Testing pulse forming networks with DARHT accelerator cells  

Microsoft Academic Search

Summary form only given. The Dual Axis Radiographic Hydrotest Facility [DARHT] at Los Alamos will use two induction linacs to produce high-energy electron beams. The electron beams will be used to generate X-rays from a bremsstrahlung target. Those X-rays will be used to generate radiographs. The first accelerator is operational now, operating with a 60-nanosecond electron beam. The second accelerator

E. A. Rose; D. A. Dalmas; J. N. Downing; R. D. Temple

2001-01-01

114

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

2014-08-20

115

Development of an accelerated leach test(s) for low-level waste forms  

SciTech Connect

An accelerated leach test(s) is being developed to predict long-term leaching behavior of low-level radioactive waste (LLW) forms in their disposal environments. As necessary background, a literature survey of reported leaching mechanisms, available mathematical models and factors that affect leaching of LLW forms has been compiled. Mechanisms which have been identified include diffusion, dissolution, ion exchange, corrosion and surface effects. A computerized data base of LLW leaching data and mathematical models is being developed. The data is being used for model evaluation by curve fitting and statistical analysis according to standard procedures of statistical quality control. Long-term leach tests on portland cement, bitumen and vinyl ester-styrene (VES) polymer waste forms are underway which are designed to identify and evaluate factors that accelerate leaching without changing the mechanisms. Initial results on the effect of temperature on leachability indicate that the leach rates of cement and VES waste forms increase with increasing temperature, whereas, the leach rate of bitumen is little affected. 10 refs., 5 figs.

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

1985-01-01

116

Particle Acceleration in three dimensional Reconnection Regions: A New Test Particle Approach  

E-print Network

Magnetic Reconnection is an efficient and fast acceleration mechanism by means of direct electric field acceleration parallel to the magnetic field. Thus, acceleration of particles in reconnection regions is a very important topic in plasma astrophysics. This paper shows that the conventional analytical models and numerical test particle investigations can be misleading concerning the energy distribution of the accelerated particles, since they oversimplify the electric field structure by the assumption that the field is homogeneous. These investigations of the acceleration of charged test particles are extended by considering three-dimensional field configurations characterized by localized field-aligned electric fields. Moreover, effects of radiative losses are discussed. The comparison between homogeneous and inhomogeneous electric field acceleration in reconnection regions shows dramatic differences concerning both, the maximum particle energy and the form of the energy distribution.

Rudiger Schopper; Guido T. Birk; Harald Lesch

2001-06-29

117

Experimental test accelerator: description and results of initial experiments  

SciTech Connect

The ETA is a high current (10,000 Amp) linear induction accelerator that produces short (30 ns) pulses of electrons at 5 MeV twice per second or in bursts of 5 pulses separated by as little as one millisecond. At this time the machine has operated at 65% of its design current and 90% of the design voltage. This report contains a description of the accelerator and its diagnostics; the results of the initial year of operation; a comparison of design codes with experiments on beam transport; and a discussion of some of the special problems and their status.

Fessenden, T.; Birx, D.; Briggs, R.

1980-06-02

118

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

119

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

120

Development of a 20 MeV Dielectric-Loaded Test Accelerator  

SciTech Connect

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

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

2006-11-27

121

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

SciTech Connect

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

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

2009-01-22

122

Characterization of interfacial adhesion damage induced by accelerated life testing  

Microsoft Academic Search

The purpose of this effort was to characterize statistically and experimentally the interfacial adhesion damage of generic dual in-line packages (DIP's) exposed to accelerated stress conditions. DIP's, consisting of three parallel gold conductors in a meander pattern on a 24 pin Al2O3 ceramic substrate spin-coated with Pyralin PI-2555 polyimide with and without an adhesion promoter (APS), were chosen as the

Jongwoo Park; D. Gary Harlow; Herman F. Nied

2000-01-01

123

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

124

Accelerated life testing and temperature dependence of device characteristics in GaAs CHFET devices  

NASA Technical Reports Server (NTRS)

Accelerated life testing of GaAs complementary heterojunction field effect transistors (CHFET) was carried out. Temperature dependence of single and synchronous rectifier CHFET device characteristics were also obtained.

Gallegos, M.; Leon, R.; Vu, D. T.; Okuno, J.; Johnson, A. S.

2002-01-01

125

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

Microsoft Academic Search

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

Mutluhan AkinAydi; Ayd?n Özsan

2011-01-01

126

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

127

The acceleration stress test of the brake system on an airplane  

Microsoft Academic Search

he test method is discussed which increases the environment stress and the working stress to stimulate failures in products without damage, besides, the method which converts the acceleration stress test time to working time is put forward to evaluate the MTBF and first overhaul period of the product. In order to stimulate potential failures, the technology of colligating reliability test

Jianjun Qiao

2011-01-01

128

Accelerated Desensitization and Adaptive Attitudes Interventions and Test Gains with Academic Probation Students  

ERIC Educational Resources Information Center

The study evaluates the test-gain benefits of an accelerated desensitization and adaptive attitudes intervention for test-anxious students. College students were screened for high test anxiety. Twenty anxious students, half of them on academic probation, were assigned to an Intervention or to a minimal treatment Control group. The Intervention was…

Driscoll, Richard; Holt, Bruce; Hunter, Lori

2005-01-01

129

Indoor Powerline Conductor Accelerated Testing Facility (Indoor-PCAT)  

E-print Network

conducting conductor tests and analyzing test data. Wind (both speed and direction) is no longer a variable variables. For example, there is no wind or rain inside the facility to slow or delays installations conductors in parallel tests. The tension limitations (i.e., the number of conductors) inherent in towers

130

Status and Plans for an SRF Accelerator Test Facility at Fermilab  

SciTech Connect

A superconducting RF accelerator test facility is currently under construction at Fermilab. The accelerator will consist of an electron gun, 40 MeV injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, and multiple downstream beam lines for testing diagnostics and performing beam experiments. With 3 cryomodules installed this facility will initially be capable of generating an 810 MeV electron beam with ILC beam intensity. The facility can accommodate up to 6 cryomodules for a total beam energy of 1.5 GeV. This facility will be used to test SRF cryomodules under high intensity beam conditions, RF power equipment, instrumentation, and LLRF and controls systems for future SRF accelerators such as the ILC and Project-X. This paper describes the current status and overall plans for this facility.

Church, M.; Leibfritz, J.; Nagaitsev, S.; /Fermilab

2011-07-29

131

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

132

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

133

A novel accelerated moisture absorption test and characterization  

Microsoft Academic Search

Moisture plays a significant role in influencing the mechanical behavior and long-term durability of composites. With the current available testing techniques the time required for environmental qualification of polymer composites can be on the order of several years and any interruption in the test can result in a significant cost and schedule penalty. Because of these long environmental conditioning times

Siva P. Pilli; Kevin L. Simmons; James D. Holbery; Vaithiyalingam Shutthanandan; Patrick B. Stickler; Lloyd V. Smith

2009-01-01

134

Enabling More than Moore: Accelerated Reliability Testing and Risk Analysis for Advanced Electronics Packaging  

NASA Technical Reports Server (NTRS)

For five decades, the semiconductor industry has distinguished itself by the rapid pace of improvement in miniaturization of electronics products-Moore's Law. Now, scaling hits a brick wall, a paradigm shift. The industry roadmaps recognized the scaling limitation and project that packaging technologies will meet further miniaturization needs or ak.a "More than Moore". This paper presents packaging technology trends and accelerated reliability testing methods currently being practiced. Then, it presents industry status on key advanced electronic packages, factors affecting accelerated solder joint reliability of area array packages, and IPC/JEDEC/Mil specifications for characterizations of assemblies under accelerated thermal and mechanical loading. Finally, it presents an examples demonstrating how Accelerated Testing and Analysis have been effectively employed in the development of complex spacecraft thereby reducing risk. Quantitative assessments necessarily involve the mathematics of probability and statistics. In addition, accelerated tests need to be designed which consider the desired risk posture and schedule for particular project. Such assessments relieve risks without imposing additional costs. and constraints that are not value added for a particular mission. Furthermore, in the course of development of complex systems, variances and defects will inevitably present themselves and require a decision concerning their disposition, necessitating quantitative assessments. In summary, this paper presents a comprehensive view point, from technology to systems, including the benefits and impact of accelerated testing in offsetting risk.

Ghaffarian, Reza; Evans, John W.

2014-01-01

135

Evaluation for EAPSM life time by ArF pellicle characteristic  

NASA Astrophysics Data System (ADS)

As the nano-lithography technology continues to develop towards advanced generation of ArF immersion lithography, the quality of ArF EAPSM becomes the most valuable factor for worldwide Maskshop. Therefore outturn of ArF EAPMS increase continuously, and people who work in the fields of semiconductor engineering give consequence to good quality of ArF EAPSM until the EUV lithography generation. Because 300mm wafer litho-facility use higher exposure energy, wider shot field and more shots per a wafer for achieving more memory(DRAM or Flash) chips than 200mm exposure facility, photo engineer wants unchanged initial condition of mask quality(CD MTT, CD Uniformity, repeating defect, phase shift and transmittance). In other words, mask manufacturer must focus on the concept of ArF EAPSM 'life time'. We have investigated the influence grade inducing the lithographic variation between the growth of exposure energy based Haze phenomena, thin organic pellicle membrane characteristics, and we have verified that the ArF pellicle durability is one of the most important evidence for improvement of life time of ArF EAPSM. In this study, related with ArF EAPSM life time, we tried to evaluate the influence of ArF pellicle characteristic consisting of pellicle membrane transmittance strength (durability against ArF laser source) and non acid mask condition for the period of non Haze contamination without added re-pellicle --> re-cleaning cycle. Metrological inspection and evaluation was conducted with several equipment and analysis including mask inspection, Scatterometer, IC, ArF laser accelerator.

Seo, Kang Joon; Ryu, Ji Sun; Jeong, Goo Min; Kang, Shin Cheol; Kim, Yong Dae; Kim, Sang Chul; Kim, Chang Yeol

2009-04-01

136

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

137

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

138

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

139

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

140

Rutting Performance of Airport Hot-Mix Asphalt Characterized by Laboratory Performance Testing, Full-Scale Accelerated Pavement Testing, and Finite Element Modeling  

E-print Network

potential laboratory tests, (b) comparisons of laboratory tests results to full-scale accelerated pavement test results, and (c) analyses of results from finite element simulations. The laboratory study evaluated of the repeated load test, the static creep...

Rushing, John Ford

2014-04-25

141

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

142

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

SciTech Connect

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

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

2007-11-07

143

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

SciTech Connect

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

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

2008-01-01

144

Using Globular Clusters to Test Gravity in the Weak Acceleration Regime  

NASA Astrophysics Data System (ADS)

We report on the results from an ongoing programme aimed at testing Newton's law of gravity in the low acceleration regime using globular clusters. We find that all clusters studied so far behave like galaxies, that is, their velocity dispersion profiles flatten out at large radii where the acceleration of gravity goes below 10 8 cm s 2, instead of following the expected Keplerian fall-off. In galaxies this behaviour is ascribed to the existence of a dark matter halo. Globular clusters, however, are not supposed to contain dark matter, hence this result might indicate that our present understanding of gravity in the weak regime of accelerations is incomplete and possibly incorrect.

Scarpa, Riccardo; Marconi, Gianni; Gilmozzi, Roberto; Carraro, Giovanni

2007-06-01

145

Accelerated laboratory corrosion test for materials and finishes used in naval aircraft. Progress report  

Microsoft Academic Search

An accelerated laboratory corrosion test has been developed to screen materials and finishes for use on naval aircraft. Sulfur dioxide is introduced at periodic intervals into a conventional salt fog chamber to simulate conditions produced by the carrier stack gas\\/marine environment. Procedures for conducting the test are described.

Ketcham

1977-01-01

146

TENSILE AND CREEP BEHAVIOR OF GEOSYNTHETICS USING CONFINED-ACCELERATED TESTS  

E-print Network

obtained in standard tensile tests, with in-isolation specimens at room temperature. This may have led and accelerated creep tests were able to be performed, with any combination of temperature and soil confinement to be conducted in the same temperature and soil confinement conditions. As a result, the creep load used in non

Zornberg, Jorge G.

147

THE IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT (TIM) 1 An Accelerated Stress Test Method for  

E-print Network

THE IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT (TIM) 1 An Accelerated Stress Test Method Test Method for Electro-Statically Driven MEMS Devices Journal: IEEE-TIM Authors: Corresponding Author on Instrumentation and Measurement (2012) 456-461" DOI : 10.1109/TIM.2011.2161937 #12;THE IEEE TRANSACTIONS

Paris-Sud XI, Université de

148

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

149

Original article A means of accelerating red oak genetic tests  

E-print Network

-mature correlations allow genetic selection to be made at juvenile ages rath- er than at rotation age. Any method The earlier accurate genetic estimates of important traits can be made, the more rapidly genetic gains can be realized. In tree improvement programs, juvenile ge- netic tests are conducted under intensive cultural

Paris-Sud XI, Université de

150

Accelerated aging test results for aerospace wire insulation constructions  

Microsoft Academic Search

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

William G. Dunbar

1995-01-01

151

Hydraulic testing of accelerator-production-of-tritium rod bundles  

SciTech Connect

Hydraulic tests have been performed on small pitch-to-diameter-ratio rod bundles using light water (1.7 < P/D < 1.17, and d = 3.175 mm). Flows cover the range from greater-than-nominal Reynolds numbers (fully turbulent) to low-speed laminar flows. Differential pressure measurements were made across the support plates holding the rod bundles, across the rod bundles, and across the entire assembly. Flow rates, temperatures, and gauge pressures also were measured. The data from these hydraulic tests have been compared to correlating literature for tightly pitched rod bundles. The prototypic geometry of these tests did not compare directly to any geometry found in the literature because of the variety of subchannels along the outer wall of the rod bundle. Under that constraint, there was excellent comparison of the rod-bundle friction factor with those factors given in the literature. The results show a large range of the Reynolds number over which the flow is in transition from laminar to turbulent (e.g., 580 < Re{sub Tr} < 13,000). Also presented is the comparison of the overall rung pressure drop to a solution based on hydraulic-resistance handbook calculations.

Spatz, T.L.; Siebe, D.A.

1999-01-01

152

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

SciTech Connect

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 [MKS, Deutsches Elektronen Synchrotron DESY, 22607 Hamburg (Germany)

2014-01-29

153

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

154

Isolation of a piezoresistive accelerometer used in high acceleration tests  

SciTech Connect

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

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

1992-12-31

155

Accelerated tests for the prediction of cut-edge corrosion of coil-coated architectural cladding  

Microsoft Academic Search

Various accelerated cabinet tests have been used for the evaluation of the cut-edge corrosion of coil-coated architectural cladding. These include the conventional ASTM B-117 method (5% continuous NaCl spray), the standard Prohesion test (0.35% (NH4)2SO4+0.05% NaCl wet\\/dry spray) as well as modified wet\\/dry spray tests using a relatively dilute artificial acid rain solution, shallow specimen incline angles with variations in

R. L. Howard; S. B. Lyon; J. D. Scantlebury

1999-01-01

156

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

NASA Astrophysics Data System (ADS)

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

Scarpa, Riccardo; Marconi, Gianni; Gilmozzi, Roberto

2006-03-01

157

Do sediment type and test durations affect results of laboratory-based, accelerated testing studies of permeable pavement clogging?  

PubMed

Previous studies have attempted to quantify the clogging processes of Permeable Interlocking Concrete Pavers (PICPs) using accelerated testing methods. However, the results have been variable. This study investigated the effects that three different sediment types (natural and silica), and different simulated rainfall intensities, and testing durations had on the observed clogging processes (and measured surface infiltration rates) of laboratory-based, accelerated PICP testing studies. Results showed that accelerated simulated laboratory testing results are highly dependent on the type, and size of sediment used in the experiments. For example, when using real stormwater sediment up to 1.18mm in size, the results showed that neither testing duration, nor stormwater application rate had any significant effect on PICP clogging. However, the study clearly showed that shorter testing durations generally increased clogging and reduced the surface infiltration rates of the models when artificial silica sediment was used. Longer testing durations also generally increased clogging of the models when using fine sediment (<300?m). Results from this study will help researchers and designers better anticipate when and why PICPs are susceptible to clogging, reduce maintenance and extend the useful life of these increasingly common stormwater best management practices. PMID:25618819

Nichols, Peter W B; White, Richard; Lucke, Terry

2015-04-01

158

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

159

IFMIF (International Fusion Materials Irradiation Facility), an accelerator-based neutron source for fusion components irradiation testing: Materials testing capabilities  

SciTech Connect

The International Fusion Materials Irradiation Facility (IFMIF) 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. At the extended facility, 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/sup 15/ n/cm/sup 2/-s) testing in IFMITF would be over a liter, a factor of about three 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 1A or more. Such an increase can be accomplished by funneling beams of deuterium ions from the radio-frequency quadruple into a linear accelerator and by taking advantage of recent developments in accelerator technology. Multiple beams and large total current allow great variety in available testing. For example, multiple simultaneous experiments, and great flexibility in tailoring spatial distributions of flux and spectra can be achieved. 5 refs., 2 figs., 1 tab.

Mann, F.M.

1988-08-01

160

Vacuum system design considerations of the Los Alamos Accelerator Test Stand (ATS)  

SciTech Connect

The accelerator test stand (ATS), in operation at the Los Alamos National Laboratory, includes a hydrogen ion source, low- and high-energy beam-transport sections, and a 425-MHz radio-frequency quadrupole (RFQ) linear accelerator. A 425-MHz drift-tube linac (DTL) and a powered ''buncher'' matching section have been constructed and will be installed on the ATS. The vacuum systems required for the various sections of the ATS are designed to provide: (1) high gas-load capability, as required in the ion source, and (2) high-vacuum capability in the high-power, radio-frequency accelerator sections (where fast vacuum-system response time is of importance) through the use of distributed, differential pumping as a principal vacuum-system feature. This paper describes properties of accelerator materials, vacuum-systems engineering and analysis, vacuum equipment used, and ATS vacuum-system performance.

Wilson, N.G.

1986-01-01

161

Fabrication and cold test of photonic band gap resonators and accelerator structures  

NASA Astrophysics Data System (ADS)

We present the detailed description of the successful design and cold test of photonic band gap (PBG) resonators and traveling-wave accelerator structures. Those tests provided the essential basis for later hot test demonstration of the first PBG accelerator structure at 17.140 GHz [E. I. Smirnova, A. S. Kesar, I. Mastovsky, M. A. Shapiro, and R. J. Temkin, Phys. Rev. Lett., 95, 074801 (2005).PRLTAO0031-900710.1103/PhysRevLett.95.074801]. The advantage of PBG resonators is that they were built to support only the main, TM01-like, accelerator mode while not confining the higher-order modes (HOM) or wakefields. The design of the PBG resonators was based on a triangular lattice of rods, with a missing rod at the center. Following theoretical analysis, the rod radius divided by the rod spacing was held to a value of about 0.15 to avoid supporting HOM. For a single-cell test the PBG structure was fabricated in X-band (11 GHz) and brazed. The mode spectrum and Q factor (Q=5000) agreed well with theory. Excellent HOM suppression was evident from the cold test. A six-cell copper PBG accelerator traveling-wave structure with reduced long-range wakefields was designed and was built by electroforming at Ku-band (17.140 GHz). The structure was tuned by etching the rods. Cold test of the structure yielded excellent agreement with the theoretical design. Successful results of the hot test of the structure demonstrating the acceleration of the electron beam were published in E. I. Smirnova, A. S. Kesar, I. Mastovsky, M. A. Shapiro, and R. J. Temkin, Phys. Rev. Lett., 95, 074801 (2005).PRLTAO0031-900710.1103/PhysRevLett.95.074801

Smirnova, Evgenya I.; Mastovsky, Ivan; Shapiro, Michael A.; Temkin, Richard J.; Earley, Lawrence M.; Edwards, Randall L.

2005-09-01

162

Space Mechanisms Lessons Learned and Accelerated Testing Studies  

NASA Technical Reports Server (NTRS)

A number of mechanism (mechanical moving component) failures and anomalies have recently occurred on satellites. In addition, more demanding operating and life requirements have caused mechanism failures or anomalies to occur even before some satellites were launched (e.g., during the qualification testing of GOES-NEXT, CERES, and the Space Station Freedom Beta Joint Gimbal). For these reasons, it is imperative to determine which mechanisms worked in the past and which have failed so that the best selection of mechanically moving components can be made for future satellites. It is also important to know where the problem areas are so that timely decisions can be made on the initiation of research to develop future needed technology. To chronicle the life and performance characteristics of mechanisms operating in a space environment, a Space Mechanisms Lessons Learned Study was conducted. The work was conducted by the NASA Lewis Research Center and by Mechanical Technologies Inc. (MTI) under contract NAS3-27086. The expectation of the study was to capture and retrieve information relating to the life and performance of mechanisms operating in the space environment to determine what components had operated successfully and what components had produced anomalies.

Fusaro, Robert L.

1997-01-01

163

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

164

Accelerated lifetime testing of fused silica for deep ultraviolet laser applications revised  

NASA Astrophysics Data System (ADS)

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

Mühlig, Christian; Bublitz, Simon

2014-12-01

165

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

166

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

SciTech Connect

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

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

2011-09-01

167

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

168

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

169

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

170

Lessons from two field tests on pipeline damage detection using acceleration measurement (Invited Paper)  

E-print Network

Lessons from two field tests on pipeline damage detection using acceleration measurement (Invited, Irvine, CA USA 92697-2700 ABSTRACT Early detection of pipeline damages has been highlighted in water supply industry. Water pressure change in pipeline due to a sudden rupture causes pipe to vibrate

Shinozuka, Masanobu

171

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

Microsoft Academic Search

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

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

2007-01-01

172

Progress in development of an accelerated leach test for low-level radioactive waste forms  

SciTech Connect

Factors that accelerate leaching from solidified low-level radioactive waste are being investigated to develop a short-term leach test that can be used to predict long-term releases. Data from work with portland cement containing radioactive tracers indicate that elevated temperatures can accelerate leaching of Ce-137 by at least a factor of eleven without changing the leaching mechanism. An 18 day leach test at 50/sup 0/C provided the equivalent of 200 days data taken at 20/sup 0/C. Portland cement containing 5 wt % Na/sub 2/SO/sub 4/ also can be accelerated, but to a lesser degree. Solid phase analysis indicated that pore plugging and increased tortuosity may be the cause of the smaller acceleration. Reduced specimen size was also a useful acceleration factor with inhomogeneities not being a problem in very small specimens. Elevated pH and 100 ppM EDTA in leaching solutions increased Sr-85 releases without altering Cs-137 leaching. 9 refs., 10 figs., 1 tab.

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

1987-08-01

173

Accelerated aging tests on magnet wires under high frequency pulsating voltage and high temperature  

Microsoft Academic Search

Breakdown voltage and accelerated multistress aging tests were conducted on fine gauge magnet wire of heavy build insulation film of polyurethane resin with nylon overcoat. The aging tests were carried out under simultaneous high frequency pulsating voltages (15-40 kHz) and high temperatures (100-180°C). The effects of the duty cycle and rise time of the voltage pulse on the time-to-breakdown were

S. Grzybowski; E. A. Feilat; P. Knight

1999-01-01

174

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

175

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

176

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

177

Identifying the failure mechanism in accelerated life tests by two-parameter lognormal distributions  

NASA Astrophysics Data System (ADS)

The failure mechanism stimulated by accelerated stress in the degradation may be different from that under normal conditions, which would lead to invalid accelerated life tests. To solve the problem, we study the relation between the Arrhenius equation and the lognormal distribution in the degradation process. Two relationships of the lognormal distribution parameters must be satisfied in the conclusion of the unaltered failure mechanism, the first is that the logarithmic standard deviations must be equivalent at different temperature levels, and the second is that the ratio of the differences between logarithmic means must be equal to the ratio of the differences between reciprocals of temperature. The logarithm of distribution lines must simultaneously have the same slope and regular interval lines. We studied the degradation of thick-film resistors in MCM by accelerated stress at four temperature levels (390, 400, 410 and 420 K), and the result agreed well with our method.

Chunsheng, Guo; Yanfeng, Zhang; Ning, Wan; Hui, Zhu; Shiwei, Feng

2014-08-01

178

Overview of the Beam diagnostics in the Medaustron Accelerator:Design choices and test Beam commissioning  

E-print Network

The MedAustron centre is a synchrotron based accelerator complex for cancer treatment and clinical and non-clinical research with protons and light ions, currently under construction in Wiener Neustadt, Austria. The accelerator complex is based on the CERN-PIMMS study [1] and its technical implementation by the Italian CNAO foundation in Pavia [2]. The MedAustron beam diagnostics system is based on sixteen different monitor types (153 devices in total) and will allow measuring all relevant beam parameters from the source to the irradiation rooms. The monitors will have to cope with large intensities and energy ranges. Currently, one ion source, the low energy beam transfer line and the RFQ are being commissioned in the Injector Test Stand (ITS) at CERN. This paper gives an overview of all beam monitors foreseen for the MedAustron accelerator, elaborates some of the design choices and reports the first beam commissioning results from the ITS.

Osmic, F; Gyorgy, A; Kerschbaum, A; Repovz, M; Schwarz, S; Neustadt, W; Burtin, G

2012-01-01

179

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

180

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

181

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

182

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

183

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

184

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

185

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

186

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

187

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. PMID:24677412

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

2014-11-01

188

Beam test of a new radio frequency quadrupole linac for the Japan Proton Accelerator Research Complex  

NASA Astrophysics Data System (ADS)

We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.

Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saisyun; Hori, Toshihiko; Sawabe, Yuki; Chishiro, Etsuji; Fukuta, Shinpei; Hasegawa, Kazuo; Hirano, Koichiro; Kikuzawa, Nobuhiro; Koizumi, Isao; Miura, Akihiko; Oguri, Hidetomo; Ohkoshi, Kiyonori; Sato, Fumiaki; Shinozaki, Shinichi; Ueno, Akira; Kawamata, Hiroshi; Sugimura, Takashi; Takagi, Akira; Fang, Zhigao; Fukui, Yuji; Futatsukawa, Kenta; Ikegami, Kiyoshi; Maruta, Tomofumi; Miyao, Tomoaki; Nanmo, Kesao

2014-12-01

189

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

PubMed

The reliability test of an electron cyclotron resonance ion source developed for accelerator driven sub-critical system is carried out in China Institute of Atomic Energy. A unique technique to improve the reliability is adopted. The source is operated for more than 200 h at 75 keV, 100 mA extracted hydrogen current, while 2 beam trips are recorded in the period, and uninterrupted operation time is about 150 h. The experimental result is described. PMID:22380168

Cui, B; Tang, B; Ma, R; Huang, Q; Ma, Y; Chen, L; Jiang, W

2012-02-01

190

Experimental tests of the modernized VASSILISSA separator (SHELS) with the use of accelerated 50Ti ions  

NASA Astrophysics Data System (ADS)

A high intensity ion beam of 50Ti ions was obtained using the ECR ion source on the U400 cyclotron. The experimental tests using accelerated 50Ti ions were performed with a modernized VASSILISSA separator (SHELS). Data has been obtained on the transmission coefficients of recoil nuclei synthesized in complete fusion reactions. Estimates from ion optical calculations performed in the design phase of the project of modernizing the separator are completely confirmed.

Yeremin, A. V.; Popeko, A. G.; Malyshev, O. N.; Gall, B.; Asfari, Z.; Lopez-Martens, A.; Hauschild, K.; Dorvaux, O.; Gikal, B. N.; Bogomolov, S. L.; Loginov, V. N.; Bondarchenko, A. E.; Chepigin, V. I.; Svirikhin, A. I.; Isaev, A. V.; Sokol, E. A.; Chelnokov, M. L.; Kuznetsov, A. N.; Kuznetsova, A. A.; Popov, Yu. A.; Rezynkina, K.; Dechery, F.; Andel, B.; Hofmann, S.; Maurer, J.; Heinz, S.; Rubert, J.

2015-01-01

191

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

SciTech Connect

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

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

2012-02-15

192

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

193

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

Microsoft Academic Search

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

Prager

1986-01-01

194

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

PubMed

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

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

2008-02-01

195

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

SciTech Connect

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., E-mail: hosseinpour@tabrizu.ac.ir; Mehdizade, M.; Mohammadi, M. A. [Plasma Physics Department, University of Tabriz, Tabriz (Iran, Islamic Republic of)

2014-10-15

196

Limitations of predicting in vivo biostability of multiphase polyurethane elastomers using temperature-accelerated degradation testing.  

PubMed

Polyurethane biostability has been the subject of intense research since the failure of polyether polyurethane pacemaker leads in the 1980s. Accelerated in vitro testing has been used to isolate degradation mechanisms and predict clinical performance of biomaterials. However, validation that in vitro methods reproduce in vivo degradation is critical to the selection of appropriate tests. High temperature has been proposed as a method to accelerate degradation. However, correlation of such data to in vivo performance is poor for polyurethanes due to the impact of temperature on microstructure. In this study, we characterize the lack of correlation between hydrolytic degradation predicted using a high temperature aging model of a polydimethylsiloxane-based polyurethane and its in vivo performance. Most notably, the predicted molecular weight and tensile property changes from the accelerated aging study did not correlate with clinical explants subjected to human biological stresses in real time through 5 years. Further, DMTA, ATR-FTIR, and SAXS experiments on samples aged for 2 weeks in PBS indicated greater phase separation in samples aged at 85°C compared to those aged at 37°C and unaged controls. These results confirm that microstructural changes occur at high temperatures that do not occur at in vivo temperatures. In addition, water absorption studies demonstrated that water saturation levels increased significantly with temperature. This study highlights that the multiphase morphology of polyurethane precludes the use of temperature accelerated biodegradation for the prediction of clinical performance and provides critical information in designing appropriate in vitro tests for this class of materials. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 159-168, 2015. PMID:24810790

Padsalgikar, Ajay; Cosgriff-Hernandez, Elizabeth; Gallagher, Genevieve; Touchet, Tyler; Iacob, Ciprian; Mellin, Lisa; Norlin-Weissenrieder, Anna; Runt, James

2015-01-01

197

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

NASA Astrophysics Data System (ADS)

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

Sawant, M.; Christou, A.

2012-12-01

198

Development of a quantitative accelerated sulphate attack test for mine backfill  

NASA Astrophysics Data System (ADS)

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

Shnorhokian, Shahe

199

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

200

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

NASA Astrophysics Data System (ADS)

We report on the design, numerical modeling, and experimental testing of a cylindrical dielectric loaded traveling wave structure for charged particle beam acceleration. This type of structure has similar accelerating properties to disk-loaded metal slow wave structures but with some distinct advantages in terms of simplicity of fabrication and suppression of parasitic wakefield effects. Efficient coupling of external rf power to the cylindrical dielectric waveguide is a technical challenge, particularly with structures of very high dielectric constant ?. We have designed and constructed an X-band structure loaded with a permittivity ?=20 dielectric to be powered by an external rf power source. We have attained high efficiency broadband rf coupling by using a combination of a tapered dielectric end section and a carefully adjusted coupling slot. Bench testing using a network analyzer has demonstrated a power coupling efficiency in excess of 95% with bandwidth of 30 MHz, thus providing a necessary basis for construction of an accelerator using this device. We have also simulated the parameters of this structure using a finite difference time domain electromagnetic solver. Within the limits of the approximations used, the results are in reasonable agreement with the bench measurements.

Zou, P.; Gai, W.; Konecny, R.; Sun, X.; Wong, T.; Kanareykin, A.

2000-06-01

201

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

SciTech Connect

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

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

1987-01-01

202

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

203

Test particle acceleration by non-uniform MHD fields in short time scales  

NASA Astrophysics Data System (ADS)

We consider the acceleration of test particles in non-uniform electric and magnetic fields obtained from direct numerical solutions of the MHD equations in a turbulent regime. Numerical experiments are performed for cases with and without a strong background magnetic field and results are compared. Distribution functions of the particles velocities are computed at short time scales and the appearance of anisotropic effects is studied. We found different behavior according to the particle motion lengthscale compared to the turbulent correlation scale and the dissipative scales. An acceleration mechanism by fields in reconnection geometries is proposed to explain qualitatively the behavior of the particles. A question remains as to how these results relate to the understanding of the self-consistent heating of solar protons and electrons. Work supported by NSF grant ATM-9977692 and DOE grant DE-FG02-98ER54490.

Dmitruk, P.; Matthaeus, W. H.

2004-05-01

204

Accelerator Testing of the General Antiparticle Spectrometer, a Novel Approach to Indirect Dark Matter Detection  

E-print Network

We report on recent accelerator testing of a prototype general antiparticle spectrometer (GAPS). GAPS is a novel approach for indirect dark matter searches that exploits the antideuterons produced in neutralino-neutralino annihilations. GAPS captures these antideuterons into a target with the subsequent formation of exotic atoms. These exotic atoms decay with the emission of X-rays of precisely defined energy and a correlated pion signature from nuclear annihilation. This signature uniquely characterizes the antideuterons. Preliminary analysis of data from a prototype GAPS in an antiproton beam at the KEK accelerator in Japan has confirmed the multi-X-ray/pion star topology and indicated X-ray yields consistent with prior expectations. Moreover our success in utilizing solid rather than gas targets represents a significant simplification over our original approach and offers potential gains in sensitivity through reduced dead mass in the target area.

C J Hailey; T Aramaki; W W Craig; L Fabris; F Gahbauer; J E Koglin; N Madden; K Mori; H T Yu; K P Ziock

2005-09-20

205

Preliminary results of accelerated exposure testing of solar cell system components  

NASA Technical Reports Server (NTRS)

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

Anagnostou, E.; Forestieri, A. F.

1977-01-01

206

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

207

An accelerated step test to assess dancer pre-season aerobic fitness.  

PubMed

As the technical performance demands of dance increase, professional companies and pre-professional schools are implementing pre-season screenings that require an efficient, cost effective way to measure dancer aerobic fitness. The aim of this study was to assess an accelerated 3-minute step test (112 beats·min(-1)) by comparing it to the well-studied YMCA step test (96 beats·min(-1)) and a benchmark standard, an incremental treadmill test, using heart rate (HR) and oxygen consumption (VO2) as variables. Twenty-six professional and pre- professional dancers (age 20 ± 2.02 years) were fitted with a telemetric gas analysis system and HR monitor. They were tested in the following order: 96 step, 112 step, and treadmill test, with rest to return to baseline heart rate between each test. The step and treadmill tests were compared using Intra-class Correlation Coefficients [ICC (3, k)] calculated with analysis of variance (p < 0.05). To determine whether there was a relationship between peak and recovery HR (HRpeak, HRrecov) and VO2(VO2peak, VO2recov) variables, Pearson product moment correlations were used. Differences due to gender or group (pre- professionals versus professionals) were explored with MANOVAs for HRpeak, VO2peak, HRrecov, VO2recov, and fitness category. The 112 step test produced higher HRpeak and VO2peak values than the 96 step test, reflecting a greater workload (p < 0.001). For HRpeak, there were high correlations (r = 0.71) and for HRrecov, moderate correlations (r = 0.60) between the 112 step test and treadmill test. For VO2peak and VO2recov, there were moderate correlations between the 112 step test and treadmill test (r = 0.65 and 0.73). No differences between genders for VO2peak values were found for either step test, but males displayed lower HRpeak values for both step tests and higher VO2peak values during the treadmill test (p < 0.001). Recovery HR was lower in males for the 96 and 112 step tests (p < 0.05). This was reflected in higher fitness scores. There were no differences between groups in any of the variables when only females were compared. For the 112 step test, correlations between HRpeak and HRrecov were high (r = 0.85), and correlations between HRpeak and fitness category were very high (r = 0.98). It is concluded that the 112 step test provides an efficient, acceptable tool for testing dance populations, though further testing in larger groups of dancers representing a diverse range of genres and training levels is needed. PMID:24568799

Bronner, Shaw; Rakov, Sara

2014-03-01

208

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

NASA Technical Reports Server (NTRS)

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

Sovey, J.

1997-01-01

209

Tolerable Limits of Oscillatory Accelerations Due to Rolling Motions Experienced by One Pilot During Automatic-Interceptor Flight Tests  

NASA Technical Reports Server (NTRS)

Limited flight - test data obtained from an automatically controlled interceptor during runs in which oscillatory rolling motions were encountered have been correlated with the pilot's comments regarding his ability to tolerate the imposed lateral accelerations.

Brissenden, Roy F.; Cheatham, Donald C.; Champine, Robert A.

1961-01-01

210

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

211

Closed-loop caloric, harmonic acceleration and active head rotation tests: norms and reliability.  

PubMed

Norms and test-retest data from 20 persons with normal hearing and balance function were obtained for bithermal caloric (BC) using a closed-loop irrigator, sinusoidal harmonic acceleration (SHA) and active head rotation (AHR) tests. Each subject was tested twice with each test, with at least 24 hours between retest. Results of BC testing indicate that a unilateral weakness of 30% should be present to confidently identify a significant inter-ear difference when using a closed-loop irrigator for stimulus. Test-retest correlations of unilateral weakness were extremely poor, reflecting the potential for considerable variability with this test. With the exception of asymmetry measures at 0.01 and 0.02 Hz, SHA gain, phase, and asymmetry are very similar to previously published norms. Test-retest correlations were generally better than BC correlations, with phase measures having the highest test-retest correlations. AHR norms were obtained in three conditions, with eyes open and starting at a stationary target (AHR-EO), with eyes closed (AHR-EC), and with eyes open and fixated on a target moving synchronously with the head (AHR-FX). AHR-EO mean gain and phase were slightly less than that reported by other researchers, possibly as a result of differences in analysis algorithms, and had the poorest test-retest correlations. AHR-EC gain and phase were much more variable than AHR-EO between subjects, but showed very high test-retest correlations. AHR-FX gain, phase, and asymmetry are similar to those reported previously and have slightly better test-retest correlations than AHR-EO. PMID:8265197

Henry, D F; DiBartolomeo, J D

1993-12-01

212

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

Microsoft Academic Search

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

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

2009-01-01

213

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

214

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

NASA Astrophysics Data System (ADS)

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 3.5x10-9 cm s-2 . The velocity dispersion is found to remain constant at large radii (with an asymptotic values of 2.7 km s-1 ) rather than follow the Keplerian falloff. Similar results were previously found for the globular clusters ? 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 a0 1.2x10-8 cm s-2 . 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.

Scarpa, Riccardo; Marconi, Gianni; Gilmozzi, Roberto

2004-12-01

215

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

216

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

217

Accelerated corrosion tests for protective properties of aluminum and zinc coatings  

Microsoft Academic Search

We perform accelerated corrosion tests of aluminum-zinc coatings according to the B-117 ASTM standard in the following three\\u000a modes: (1) CCT mode, which includes drying at 60C for 4h, holding at a relative humidity of 100% for 2h, and salt spraying\\u000a (pH=6.8–7.2) at 35C for 2h; (2) AAR mode, which includes drying at 60C and a relative humidity of 20–30%

L. Kwiatkowski; J. Kwiecie?; T. Szustkiewicz

1996-01-01

218

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

219

ACCELERATED TESTING OF NEUTRON-ABSORBING ALLOYS FOR NUCLEAR CRITICALITY CONTROL  

SciTech Connect

The US Department of Energy requires nuclear criticality control materials be used for storage of highly enriched spent nuclear fuel used in government programs and the storage of commercial spent nuclear fuel at the proposed High-Level Nuclear Waste Geological Repository located at Yucca Mountain, Nevada. Two different metallic alloys (Ni-Cr-Mo-Gd and borated stainless steel) have been chosen for this service. An accelerated corrosion test program to validate these materials for this application is described and a performance comparison is made.

Ronald E. Mizia

2011-10-01

220

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

221

Development of an Accelerated Test Design for Predicting the Service Life of the Solar Array at Mead, Nebraska  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

222

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

223

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

224

Scaled Accelerator Test for the DARHT-II Downstream Transport System  

SciTech Connect

The second axis of the Dual Axial radiography Hydrodynamic Test (DARHT-II) facility at LANL is currently in the commissioning phase[1]. The beam parameters for the DARHT-II machine will be nominally 18 MeV, 2 kA and 1.6 {micro}s. This makes the DARHT-II downstream system the first system ever designed to transport a high current, high energy and long pulse beam [2]. We will test these physics issues of the downstream transport system on a scaled DARHT-II accelerator with a 7.8-MeV and 660-A beam at LANL before commissioning the machine at its full energy and current. The scaling laws for various physics concerns and the beam parameters selection is discussed in this paper.

Chen, Y; Blackfield, D T; Caporaso, G J; Guethlein, G; McCarrick, J F; Paul, A C; Watson, J A; Weir, J T

2005-10-03

225

Extension of Life Time of Welded Fatigue Loaded Structures  

Microsoft Academic Search

Summary. At the University of Braunschweig the effects of ultrasonic peening (UP) and shot peening on the fatigue life and fatigue strength of new and existing wind energy plants have been investigated. The test results demonstrate that UP is an effective and practical means to extend their service life.

Thomas Ummenhofer; Imke Weich; Thomas Nitschke-Pagel

226

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

227

Accelerated Life Structural Benchmark Testing for a Stirling Convertor Heater Head  

NASA Astrophysics Data System (ADS)

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

Krause, David L.; Kantzos, Pete T.

2006-01-01

228

Accelerated Life Structural Benchmark Testing for a Stirling Convertor Heater Head  

NASA Technical Reports Server (NTRS)

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

Krause, David L.; Kantzos, Pete T.

2006-01-01

229

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

SciTech Connect

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

M.A. Alvin

1999-09-30

230

Further Analysis of Accelerated Exposure Testing of Thin-Glass Mirror Matrix  

SciTech Connect

Concentrating solar power (CSP) companies have deployed thin-glass mirrors produced by wet-silver processes on {approx}1-mmthick, relatively lightweight glass. These mirrors are bonded to metal substrates in commercial installations and have the confidence of the CSP industry. Initial hemispherical reflectance is {approx}93%-96%, and the cost is {approx}$16.1/m{sup 2}-$43.0/m{sup 2}. However, corrosion was observed in mirror elements of operational solar systems deployed outdoors for 2 years. National Renewable Energy Laboratory (NREL) Advanced Materials Team has been investigating this problem. First, it was noted that this corrosion is very similar to the corrosion bands and spots observed on small (45 mm x 67 mm) thin-glass mirrors laminated to metal substrates with several different types of adhesives and subjected to accelerated exposure testing (AET) at NREL. The corrosion appears as dark splotches in the center of the mirror, with a corresponding 5%-20% loss in reflectivity. Secondly, two significant changes in mirror manufacture have occurred in the wet-chemistry process because of environmental concerns. The first is the method of forming a copper-free reflective mirror, and the second is the use of lead-free paints. However, the copper-free process requires stringent quality control and the lead-free paints were developed for interior applications. A test matrix of 84 combinations of sample constructions (mirror type/backprotective paint/adhesive/substrate) was devised for AET as a designed experiment to identify the most-promising mirrors, paints, and adhesives for use with concentrator designs. Two types of accelerated exposure were used: an Atlas Ci5000 WeatherOmeter (CI5000) and a BlueM damp-heat chamber. Based on an analysis of variance (ANOVA), the various factors and interactions were modeled. These samples now have more than 36 months of accelerated exposure, and most samples have completed their test cycle. We will discuss the results of the final exposure testing of these mirror samples. Glass mirrors with copper back-layers and heavily leaded paints have been considered robust for outdoor use. However, the basic mirror composition of the new mirrors is radically different from that of historically durable solar mirrors, and the outdoor durability must be determined.

Kennedy, C. E.; Terwilliger, K.; Jorgensen, G. J.

2007-01-01

231

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

232

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

233

Cryogenic test facility of superconducting magnets for the accelerator complex NICA  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

234

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

235

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

236

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

237

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

NASA Astrophysics Data System (ADS)

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

Koyanagi, Jun; Nakada, Masayuki; Miyano, Yasushi

2012-02-01

238

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

NASA Technical Reports Server (NTRS)

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

Gates, Thomas S.

2003-01-01

239

EPICS BASED HIGH POWER RF CONDITIONING CONTROL SYSTEM FOR THE SNS ACCELERATOR RF TEST FACILITY  

Microsoft Academic Search

Charged particle accelerators use various vacuum windows on their accelerating RF cavities to pass very high RF power through. Before placing on the cavities the windows should be cleaned, baked and fully RF conditioned due to poor vacuum caused by outgassing and other contamination. The linear accelerator (linac) in the Spallation Neutron Source (SNS) in Oak Ridge National Laboratory (ORNL)

S. M. Shajedul Hasan; Johnny Tang; Kay Kasemir; Yoon W. Kang; Mark Crofford

240

Simulation prediction and experiment setup of vacuum laser acceleration at Brookhaven National Lab-Accelerator Test Facility  

NASA Astrophysics Data System (ADS)

This paper presents the pre-experiment plan and prediction of the first stage of vacuum laser acceleration (VLA) collaborating by UCLA, Fudan University and ATF-BNL. This first stage experiment is a proof-of-principle to support our previously posted novel VLA theory. Simulations show that based on ATF's current experimental conditions the electron beam with initial energy of 15 MeV can get net energy gain from an intense CO2 laser beam. The difference in electron beam energy spread is observable by the ATF beam line diagnostics system. Further, this energy spread expansion effect increases along with an increase in laser intensity. The proposal has been approved by the ATF committee and the experiment will be our next project.

Shao, L.; Cline, D.; Ding, X.; Ho, Y. K.; Kong, Q.; Xu, J. J.; Pogorelsky, I.; Yakimenko, V.; Kusche, K.

2013-02-01

241

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

242

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

NASA Astrophysics Data System (ADS)

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

Milgrom, Mordehai

2012-09-01

243

Accelerated exposure tests of encapsulated Si solar cells and encapsulation materials  

NASA Astrophysics Data System (ADS)

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

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

1999-03-01

244

Testing MOND over a wide acceleration range in x-ray ellipticals.  

PubMed

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 modified Newtonian dynamics (MOND) in ellipticals with force and quality that, arguably, approach those of rotation-curve tests in disk galaxies. In the context of MOND, it is noteworthy that the measured accelerations span a wide range, from more than 10a(0) to about 0.1a(0), unprecedented in individual ellipticals. I find that MOND predicts correctly the measured dynamical mass runs (apart from a possible minor tension in the inner few kpc of NGC 720, which might be due to departure from hydrostatic equilibrium): The predicted mass discrepancy increases outward from none near the center, to ~10 at the outermost radii. The implications for the MOND-versus-dark-matter controversy go far beyond the simple fact of two more galaxies conforming to MOND. PMID:23030078

Milgrom, Mordehai

2012-09-28

245

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

246

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

247

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

248

Corrosion Testing in Support of the Accelerator Production of Tritium Program  

SciTech Connect

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

Chandler, G.

2000-11-07

249

Direct observation of RTN-induced SRAM failure by accelerated testing and its application to product reliability assessment  

Microsoft Academic Search

A new accelerated testing scheme for detecting SRAM bit failure caused by random telegraph noise (RTN) is proposed. By repeatedly monitoring the fail bit count (FBC) under a reduced margin operation condition, increasing trend of FBC along time was clearly observed, which is believed to be caused by RTN. In addition, physics-based ultra-fast Monte Carlo RTN simulation program has been

K. Takeuchi; T. Nagumo; K. Takeda; S. Asayama; S. Yokogawa; K. Imai; Y. Hayashi

2010-01-01

250

Compact Accelerated Life Testing with Expanded Measurement Suite John Raguse, Russell Geisthardt, Jennifer Drayton, James R. Sites  

E-print Network

-- An accelerated-life-testing (ALT) system has been built at the Colorado State University Photovoltaics Laboratory commercially available 40 W broad- spectrum LED arrays. A preliminary study has been performed on Cadmium-beam-induced current (LBIC). Index Terms -- Cadmium compounds, photovoltaic cells, stress measurement

Sites, James R.

251

Study of graphite\\/NCA Li-ion cell degradation during accelerated aging tests — Data analysis of the SIMSTOCK project  

Microsoft Academic Search

This paper presents a preliminary analysis of ag- ing data from the French SIMSTOCK program in order to evaluate the influence of several aging factors on capacity fade and impedance increase of graphite\\/NCA Li-ion batteries over accelerated aging tests. Test protocols (cycling and check-up) are presented, and the behavior of battery under aging is described. An equivalent-circuit model is used

Weiping Liu; Charles Delacourt; Christophe Forgez; Serge Pelissier

2011-01-01

252

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

253

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

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

X-ray beam size measurements on the Advanced Test Accelerator  

SciTech Connect

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

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

1986-01-01

256

INITIAL TEST OF A FAST RAMPED SUPERCONDUCTING MODEL DIPOLE FOR GSIS PROPOSED SIS200 ACCELERATOR.  

SciTech Connect

Gesellschaft fur Schwerionenforschung (GSI) has proposed a large expansion of the existing facility in Darmstadt, Germany. The proposal includes an accelerator, SIS200, with rigidity of 200 Tam that utilizes 4 T superconducting dipoles ramped at 1 T/s. An R&D program including both the superconductor and the magnet is directed at achieving the desired ramp rate with minimal energy loss. The RHIC arc dipoles, with 8 cm aperture, possess adequate aperture and field strength but are ramped at only 1/20 of the desired rate. However, for reasons of speed and economy, the RHIC dipole is being used as the basis for this work. The superconductor R&D has progressed far enough to permit the manufacture of an initial cable with satisfactory properties. This cable has been used in the construction of a I m model magnet, appropriately modified from the RHIC design. The magnet has been tested successfully at 2 T/s to 4.38 T.

WANDERER,P.; ANERELLA,M.; GANETIS,G.; GHOSH,A.; JOSHI,P.; MARONE,A.; MURATORE,J.; SCHMALZLE,J.; SOIKA,R.; THOMAS,R.; KAUGERTS,J.; MORITZ,G.; HASSENZAHL,W.; WILSON,N.M.

2003-05-12

257

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

258

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

259

Conductive cooling in white organic light emitting diode for enhanced efficiency and life time  

NASA Astrophysics Data System (ADS)

We demonstrate white organic light emitting diodes with enhanced efficiency (26.8 lm/W) and life time (˜11 000 h) by improved heat dissipation through encapsulation composed of a metal (Cu, Mo, and Al) and mica sheet joined using thermally conducting epoxy. Finite element simulation is used to find effectiveness of these encapsulations for heat transfer. Device temperature is reduced by about 50% with the encapsulation. This, consequently, has improved efficiency and life time by about 30% and 60%, respectively, with respect to glass encapsulation. Conductive cooling of device is suggested as the possible cause for this enhancement.

Tyagi, Priyanka; Kumar, Arunandan; Giri, Lalat Indu; Tuli, Suneet; Srivastava, Ritu

2015-01-01

260

Analysis of transmitted optical spectrum enabling accelerated testing of multijunction concentrating photovoltaic designs  

NASA Astrophysics Data System (ADS)

Concentrating photovoltaic (CPV) technology has recently gained interest based on its scalability and expected low levelized cost of electricity. The reliability of encapsulation materials used in CPV systems, however, is not well established. For example, the present qualification test for CPV modules includes only real-time ultraviolet (UV) exposure, i.e., methods for accelerated UV testing have not yet been developed. To better define the stress inherent to CPV systems, the UV and infrared spectra transmitted through representative optical systems were evaluated. Measurements of optical components are used to assess expected optical performance and quantify damaging optical exposure. Optical properties (transmittance, refractive index, reflectance, and absorptance) of candidate materials (including PMMA, soda-lime glass, borosilicate glass, and quartz refractors), components (including Ag- and Al-enabled reflectors), and encapsulants (including EVA, ionomer, PDMS, PPMS, polyolefin, and PVB) were identified. The activation spectrum was calculated for the representative optical systems using an assumed action spectrum to compare the expected damaging dose of UV radiation delivered to the cell encapsulation. The dose and flux analysis identifies the significance of IR relative to UV exposure for CPV systems. Because UV light is typically more highly attenuated, the UV dose within the encapsulation may not greatly exceed the unconcentrated global solar condition, but the thermal load scales nearly directly with the geometric concentration. Relative to a previous analysis for crystalline silicon cell technology, the analysis here is performed for III-V multijunction technology. Novel aspects here also include additional materials (such as TPU encapsulation) and additional components (transmission through silicone on glass lenses, antireflective coatings, and the front glass used with reflective systems, as well as reflection off of the cell).

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

2011-01-01

261

Using a commercial mathematics software package for on-line analysis at the BNL Accelerator Test Facility  

SciTech Connect

BY WRITING BOTH A CUSTOM WINDOWS(NTTM) DYNAMIC LINK LIBRARY AND GENERIC COMPANION SERVER SOFTWARE, THE INTRINSIC FUNCTIONS OF MATHSOFT MATHCAD(TM) HAVE BEEN EXTENDED WITH NEW CAPABILITIES WHICH PERMIT DIRECT ACCESS TO THE CONTROL SYSTEM DATABASES OF BROOKHAVEN NATIONAL LABORATORY ACCELERATOR TEST FACILITY. UNDER THIS SCHEME, A MATHCAD WORKSHEET EXECUTING ON A PERSONAL COMPUTER BECOMES A CLIENT WHICH CAN BOTH IMPORT AND EXPORT DATA TO A CONTROL SYSTEM SERVER VIA A NETWORK STREAM SOCKET CONNECTION. THE RESULT IS AN ALTERNATIVE, MATHEMATICALLY ORIENTED VIEW OF CONTROLLING THE ACCELERATOR INTERACTIVELY.

Malone, R.; Wang, X.J.

1999-06-14

262

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

263

Simulation of launch and re-entry acceleration profiles for testing of Shuttle and unmanned microgravity research payloads  

NASA Technical Reports Server (NTRS)

A procedure was developed for the simulation of the launch and reentry acceleration profiles of the Space Shuttle (3.3 and 1.7 g maximum, respectively) and of two versions of NASA's proposed materials research Reusable Reentry Satellite (RRS) (8 and 4 g maximum, respectively). With a 7-m centrifuge, the time dependence of five different acceleration episodes was simulated for payload masses up to 59 kg. Test results obtained for the Materials Dispersion Apparatus, a commercial low-cost payload device, are presented.

Cassanto, J. M.; Ziserman, H. I.; Chapman, D. K.; Korszun, Z. R.; Todd, D. K.

1988-01-01

264

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

265

Combined approach to damaged wire ropes life-time assessment based on NDT results and rope mechanics  

NASA Astrophysics Data System (ADS)

Principles of strength assessment and life-time prediction of deteriorated wire ropes based on magnetic NDT technique are presented. The measured loss of metallic cross-section area due to abrasion, corrosion etc. and local wire breaks are treated as input data for mechanical model of rope structure. The rope is interpreted as a system with two degrees of freedom that enables to calculate the strains and stresses in each wire when the rope is subjected to tension, torsion and bending. Stress safety factor is considered as a generalized parameter that specifies the rope degradation and may be used for predicting the instant lifetimes during the rope operating history. The rope discard criterion refers to residual life-time calculated with respect to minimal allowable strength factor. Examples of integrity analysis of mine hoisting rope and jib crane rope under tension-bending fatigue loading are demonstrated. The residual strength estimates give the rope inspector further information that helps to make a valid decision on testing policy.

Vorontsov, A.; Volokhovsky, V.; Slesarev, D.

2011-07-01

266

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

267

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

268

Brand choice dynamics of consumers over their life-time of purchasing in a product category  

Microsoft Academic Search

This study develops a probabilistic model of brand choice that captures dynamic preferences and loyalties of consumers over their life-time of purchasing in a product category (i.e., first ever purchase through to last ever purchase made in a product category). The model is motivated by our theory that choice processes evolve over time, perpetuated by changes in consumer expertise, consumer

Carrie Miriam Heilman

1997-01-01

269

Overview of the Beam diagnostics in the Medaustron Accelerator:Design choices and test Beam commissioning  

Microsoft Academic Search

The MedAustron centre is a synchrotron based accelerator complex for cancer treatment and clinical and non-clinical research with protons and light ions, currently under construction in Wiener Neustadt, Austria. The accelerator complex is based on the CERN-PIMMS study [1] and its technical implementation by the Italian CNAO foundation in Pavia [2]. The MedAustron beam diagnostics system is based on sixteen

F Osmic; M Feurstein; A Gyorgy; A Kerschbaum; M Repovz; S Schwarz; W Neustadt; G Burtin

2012-01-01

270

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

271

An accelerated life test model for solid lubricated bearings based on dependence analysis and proportional hazard effect  

NASA Astrophysics Data System (ADS)

Solid lubricated bearings are important mechanical components in space, and accelerated life tests (ALT) of them are widely conducted. ALT model is needed to give the lifetime of solid lubricated bearings with ALT data, and former accelerated life test models of solid lubricated models are mainly statistical models, while physical models can imply an understanding of the failure mechanism and are preferred whenever possible. This paper proposes a physical model, which is called copula dependent proportional hazards model. A solid lubricated bearing is considered as a system consisting of several dependent items and Clayton copula function is used to describe the dependence. Proportional hazard effect is also considered to build the model. An ALT of solid lubricated bearing is carried out and the results show that this model is effective.

Zhang, Chao; Wang, Shaoping; Bai, Guanghan

2014-02-01

272

Simulation of launch and re-entry acceleration profiles for testing of shuttle and unmanned microgravity research payloads  

NASA Astrophysics Data System (ADS)

Microgravity experiments designed for execution in Get-Away Special canisters, Hitchhiker modules, and Reusable Re-entry Satellites will be subjected to launch and re-entry accelerations. Crew-dependent provisions for preventing acceleration damage to equipment or products will not be available for these payloads during flight; therefore, the effects of launch and re-entry accelerations on all aspects of such payloads must be evaluated prior to flight. A procedure was developed for conveniently simulating the launch and re-entry acceleration profiles of the Space Shuttle (3.3 and 1.7 × g maximum, respectively) and of two versions of NASA's proposed materials research Re-usable Re-entry Satellite (8 × g maximum in one case and 4 × g in the other). By using the 7 m centrifuge of the Gravitational Plant Physiology Laboratory in Philadelphia it was found possible to simulate the time dependence of these 5 different acceleration episodes for payload masses up to 59 kg. A commercial low-cost payload device, the “Materials Dispersion Apparatus” of Instrumentation Technology Associates was tested for (1) integrity of mechanical function, (2) retention of fluid in its compartments, and (3) integrity of products under simulated re-entry g-loads. In particular, the sharp rise from 1 g to maximum g-loading that occurs during re-entry in various unmanned vehicles was successfully simulated, conditions were established for reliable functioning of the MDA, and crystals of 5 proteins suspended in compartments filled with mother liquor were subjected to this acceleration load.

Cassanto, J. M.; Ziserman, H. I.; Chapman, D. K.; Korszun, Z. R.; Todd, P.

273

Effect of various coal contaminants on the performance of solid oxide fuel cells: Part I. Accelerated testing  

Microsoft Academic Search

The contaminants that are potentially present in the coal-derived gas stream and their thermochemical nature are discussed. Accelerated testing was carried out on Ni–YSZ\\/YSZ\\/LSM solid oxide fuel cells (YSZ: yttria stabilized zirconia and LSM: lanthanum strontium manganese oxide) for eight main kind of contaminants: CH3Cl, HCl, As, P, Zn, Hg, Cd and Sb at the temperature range of 750–850°C. The

JianEr Bao; Gopala N. Krishnan; Palitha Jayaweera; Jordi Perez-Mariano; Angel Sanjurjo

2009-01-01

274

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

Microsoft Academic Search

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 the design analyses including physics, heat-transfer, hydraulics, structural, radiological, and safety analyses. The design is based on a coaxial geometrical configuration to minimize the

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

275

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

276

Cosmetic corrosion of painted aluminum and steel automotive body sheet: Results from outdoor and accelerated laboratory test methods  

SciTech Connect

In recent years, increasing attention has been given to the need to develop an accelerated laboratory test method(s) for cosmetic corrosion of painted panels that realistically simulate in-service exposure. Much of that work has focused on steel substrates. The purpose of this research is to compare the corrosion performance of painted aluminum and steel sheet as determined om various laboratory methods and in-service exposure, and to develop a realistic accelerated test method for evaluation of the cosmetic corrosion of painted aluminum. Several aluminum sheet products from the 2xxx, 5xxx, and 6xxx alloy series have been tested. The steel substrates are similar to those used in other programs. The test methods chosen represent a cross-section of methods common to the automotive and aluminum industries for evaluation of painted sheet metal products. The results indicate that there is considerable difference in the relative correlation of various test methods to in-service exposure. In addition, there is considerable difference in the relative magnitudes and morphologies of corrosion, and occasionally in the relative rankings, as a function of test method. The influence of alloy composition and zinc phosphate coating weight are also discussed.

Moran, J.P.; Ziman, P.R.; Egbert, M.W. [Alcoa Technical Center, Alcoa Center, PA (United States). Alloy Technology Division

1995-11-01

277

Acceleration test for small three-phase integral horsepower induction motors-techniques, limitation, and problems of the test and interpretation of the results  

Microsoft Academic Search

This paper aims at the realization of the acceleration method for the small three-phase integral horsepower induction motors as referred to IEEE standard 112-1996. Testing on the small induction motors with an increasing moment of inertia technique is proposed. The characteristic results, the current-speed and torque-speed characteristics, are presented. In addition, verification of the results, limitation, and problems of this

W. Sae-kok; P. Lumyong

2003-01-01

278

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

279

Identification of Heredity Kernels and Their Influence on the Life Time of Glass/Polyester Composites  

NASA Astrophysics Data System (ADS)

One of the major problems encountered in prediction of hereditary viscoelastic behavior of polymeric composites is the determination of heredity kernels. This issue comes down to identification of the model characterizing the viscoelastic properties of these materials. The purpose of this work is to propose a model for prediction of viscoelastic nonlinear behavior of laminate composite with polyester matrix, through the study and analysis of heredity kernels and their influence on the life time of this material. Identification of this model required experimental determination at room temperature, of viscoelastic parameters of heredity kernels by macroscopic approach. These data provide predictive tools for establishment of the life time and long term stress limit under static complex loading for this type of material.

Olodo, E. T.; Adjovi, E. C.; Adanhounme, V.

2014-11-01

280

Performance tests of the 600-kW cw, 80-MHz, radio-frequency systems for the FMIT accelerator  

SciTech Connect

The high-power rf system for the Fusion Materials Irradiation Test (FMIT) accelerator consists of 14 sets of equipment,** each of which can deliver up to 600 kW (cw) at 80 MHz into a load having a VSWR of 1.4 or less (any phase). The equipment was designed and constructed to FMIT specifications by Continental Electronics Mfg. Co. (CEMC) of Dallas, Texas. Four sets have been shipped to Los Alamos for use with the accelerator (two with the radio-frequency quadrupole (RFQ) and two with the drift-tube linac (DTL)). The first set was fully tested at CEMC; results are summarized. Further tests conducted at Los Alamos, both into a resistive (electrolytic) load and into a resonant cavity (Q about 21,000), have confirmed that this system meets, and in most cases far exceeds, the specified performance limits. The first of the 13 production sets also was tested at CEMC before shipping any of the rf equipment to the Hanford Engineering and Development Laboratory at Richland, Washington. Because of the differences in behavior observed when No. 1 was operated at Los Alamos with a different tube installed in the final power amplifier (FPA) cavity, CEMC agreed to test No. 5 with two tubes having widely differing characteristics (notably primary screen emission). As expected, behavior differed markedly, and some design modification was necessary to meet all specifications with either tube. Results of final performance tests on No. 5 are summarized. As noted in the table, detailed test results are presented in the CEMC Acceptance Test Reports (ATRs) dated April 7, 1982 and January 3, 1983. Discussion of the most significant aspects of CEMC's tests and of those performed at Los Alamos follows a brief description of the equipment.

Nylander, R.F.; Bacci, F.F.; Fazio, M.V.; Rodgers, J.D.

1983-08-01

281

Data acquisition, control, and analysis for the Argonne Advanced Accelerator Test Facility (AATF)  

SciTech Connect

The AATF has been used to study wakefield acceleration and focusing in plasmas and rf structures. A PC-based system is described which incorporates the functions of beamline control and acquisition, storage, and preliminary analysis of video images from luminescent screen beam diagnostics. General features of the offline analysis of wakefield data are also discussed. 4 refs., 3 figs.

Schoessow, P.

1989-01-01

282

Atomic oxygen ground-based accelerated tests of spacecraft materials and structures for long-term LEO missions  

NASA Astrophysics Data System (ADS)

Spacecraft materials are degradated during long-term low earth orbit (LEO) flight. The Internation Space Station (ISS) is planed to be prolonged the term of action up to 20-25 years. To specify so long life one requires a validation of spacecraft material behaviour conservation for the period. The LEO environment includes atomic oxygen (AO) destructive incident flow. The appropriate AO fluence is proposed to be as high as 10E22-10E23 atom O/sq cm. The simulative ground-based test is evident to be acceptable if its duration is not too long usually under several hundreds of hours. In that case the rate of the test acceleration exceeds 100-200. One way to accelerate test is to increase oxygen particles energy. We test materials under oxygen plasma beam, formed by a magnetoplasmadynamic accelerator, with the oxygen particle energy of 20 -30 eV. In this way we determine an AO effective fluence by a kapton equivalent technique. The beam varies from LEO incident flow by energy, flux and rates of the oxygen dissociation / ionization/ excitation. To evaluate the test adequacy we measured and compared with LEO data erosion yields of a number of polymer materials, applied on spacecraft external surfaces. There were: polyimide (kapton), polyamide (nylon), polyethylene, polyvinyl fluoride (tedlar), polysteren, polymethyl methacrylate, epoxy, polyethylene terephthalate (mylar), graphite. Their relative erosion yields, measured and normalized by polyimide in this way, practically coincide with the data of flight experiments on the ISS. The results ground to use our plasma mode for accelerated tests of spacecraft material durability for long-term LEO flights. We tested quite a number of polymer-based materials and structures usable on ISS and another LEO spacecrafts. The effective AO fluencies ran up to 3,5 10E22 atom O/sq cm corresponding to the ISS flight duration about 20 years. We studied material behaviors like mass and thickness losses, erosion yield, surface morphology, stress-strain data. Some results we present in the report.

Chernik, Vladimir; Novikov, Lev; Smirnova, Tatyana; Shumov, Andrey

283

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

284

Preliminary temperature accelerated life test (ALT) on lattice mismatched triple-junction concentrator solar cells-on-carriers  

NASA Astrophysics Data System (ADS)

A temperature accelerated life test on concentrator lattice mismatched Ga0.37In0.63P/Ga0.83In0.17As/Ge triple-junction solar cells-on-carrier is being carried out. The solar cells have been tested at three different temperatures: 125, 145 and 165°C and the nominal photo-current condition (500X) is emulated by injecting current in darkness. The final objective of these tests is to evaluate the reliability, warranty period, and failure mechanism of these solar cells in a moderate period of time. Up to now only the test at 165°C has finished. Therefore, we cannot provide complete reliability information, but we have carried out preliminary data and failure analysis with the current results.

Orlando, Vincenzo; Espinet, Pilar; Nuñez, Neftalí; Eltermann, Fabian; Contreras, Yedileth; Bautista, Jesús; Vázquez, Manuel; Bett, Andreas W.; Algora, Carlos

2014-09-01

285

Development of an Accelerated Test Design for Predicting the Service Life of the Solar Array at Mead, Nebraska  

NASA Technical Reports Server (NTRS)

Potential long-term degradation modes for the two types of modules in the Mead array were determined and judgments were made as to those environmental stresses and combinations of stresses which accelerate the degradation of the power output. Hierarchical trees representing the severity of effects of stresses (test conditions) on eleven individual degradation modes were constructed and were pruned of tests judged to be nonessential. Composites of those trees were developed so that there is now one pruned tree covering eight degradation modes, another covering two degradation modes, and a third covering one degradation mode. These three composite trees form the basis for selection of test conditions in the final test plan which is now being prepared.

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

1979-01-01

286

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

287

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

SciTech Connect

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 [Department of Physics, Kyoto University, Kyoto, 606–8502 (Japan); Nishizawa, Atsushi; Yoo, Chul-Moon, E-mail: kent@tap.scphys.kyoto-u.ac.jp, E-mail: anishi@yukawa.kyoto-u.ac.jp, E-mail: yoo@yukawa.kyoto-u.ac.jp [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606–8502 (Japan)

2012-04-01

288

A novel accelerated corrosion test for exhaust systems by means of power ultrasound  

Microsoft Academic Search

Cycling corrosion tests have been performed to simulate corrosion conditions in the cold end of an automotive exhaust system. A middle range 1.4512 (AISI 409) stainless steel is submitted to a conventional dip dry test (DDT) parallel to a similar test but including an additional external stress thanks to an ultrasonic transducer. This new ultrasonic test (so called UST) is

M. L. Doche; J. Y. Hihn; A. Mandroyan; C. Maurice; O. Hervieux; X. Roizard

2006-01-01

289

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

290

The High-Frequency\\/Acceleration Head Heave Test in Detecting Otolith Diseases  

Microsoft Academic Search

Objective: To investigate whether transient, high-acceleration interaural head heaves (translational vestibulo-ocular reflex (tVOR)) could aid in the diagnosis of otolith diseases. Study Design: Prospective cohort study. Setting: Tertiary referral center. Patients: Thirteen patients with symptoms suggestive of oto- lith diseases and 10 age-matched controls. Interventions: Patients underwent a clinical otoneurologic examination and standard laboratory audiovestibular evalua- tion, including audiometry, electronystagmography

Paul Kessler; David Tomlinson; Alan Blakeman; John Rutka; Paul Ranalli; Agnes Wong

2007-01-01

291

In vitro evaluation of the bonding durability of self-adhesive resin cement to titanium using highly accelerated life test.  

PubMed

The purpose of this in vitro study was to evaluate the bonding durability of three self-adhesive resin cements to titanium using the Highly Accelerated Life Test (HALT). The following self-adhesive resin cements were used to bond pairs of titanium blocks together according to manufacturers' instructions: RelyX Unicem, Breeze, and Clearfil SA Luting. After storage in water at 37°C for 24 h, bonded specimens (n=15) immersed in 37°C water were subjected to cyclic shear load testing regimes of 20, 30, or 40 kg using a fatigue testing machine. Cyclic loading continued until failure occurred, and the number of cycles taken to reach failure was recorded. The bonding durability of a self-adhesive resin cement to titanium was largely influenced by the weight of impact load. HALT showed that Clearfil SA Luting, which contained MDP monomer, yielded the highest median bonding lifetime to titanium. PMID:22123007

Lin, Jie; Shinya, Akikazu; Gomi, Harunori; Matinlinna, Jukka Pekka; Shinya, Akiyoshi

2011-11-25

292

Evaluation of the atmospheric corrosion resistance of AISI A-36 steel painted with coatings based on epoxy and poly(urethane) resins using semi-accelerated testing  

Microsoft Academic Search

The influence of temperature, humidity, salinity, and the number of wet-dry cycles in the atmospheric corrosion resistance\\u000a of the AISI A-36 steel, painted with coatings based on epoxy and poly(urethane) resins was studied. The aim of this work is\\u000a to present an alternative to the accelerated and field tests developing a semi-accelerated test for evaluating the resistance\\u000a and durability of

E. M. Oliveira; J. R. G. Carneiro; V. F. Cunha Lins

2009-01-01

293

In-situ diagnostics and degradation mapping of a mixed-mode accelerated stress test for proton exchange membranes  

NASA Astrophysics Data System (ADS)

With increasing availability of more durable membrane materials for proton exchange membrane fuel cells, there is a need for a more stressful test that combines chemical and mechanical stressors to enable accelerated screening of promising membrane candidates. Equally important is the need for in-situ diagnostic methods with sufficient spatial resolution that can provide insights into how membranes degrade to facilitate the development of durable fuel cell systems. In this article, we report an accelerated membrane stress test and a degradation diagnostic method that satisfy both needs. By applying high-amplitude cycles of electrical load to a fuel cell fed with low-RH reactant gases, a wide range of mechanical and chemical stressful conditions can be created within the cell which leads to rapid degradation of a mechanically robust Ion Power™ N111-IP membrane. Using an in-situ shorting/crossover diagnostic method on a segmented fuel cell fixture that provides 100 local current measurements, we are able to monitor the progression and map the degradation modes of shorting, thinning, and crossover leak over the entire membrane. Results from this test method have been validated by conventional metrics of fluoride release rates, physical crossover leak rates, pinhole mapping, and cross-sectional measurements.

Lai, Yeh-Hung; Fly, Gerald W.

2015-01-01

294

Experimental limits on the proton life-time from the neutrino experiments with heavy water  

NASA Astrophysics Data System (ADS)

Experimental data on the number of neutrons born in the heavy water targets of the large neutrino detectors are used to set the limit on the proton life-time independently on decay mode through the reaction d-->n+?. The best up-to-date limit ?p>4×1023 yr with 95% C.L. is derived from the measurements with D2O target (mass 267 kg) installed near the Bugey reactor. This value can be improved by six orders of magnitude with future data accumulated with the SNO detector containing 1000 t of D2O.

Tretyak, V. I.; Zdesenko, Y. G.

2001-04-01

295

The Design and Testing of a Dual Fiber Textile Matrix for Accelerating Surface Hemostasis  

PubMed Central

The standard treatment for severe traumatic injury is frequently compression and application of gauze dressing to the site of hemorrhage. However, while able to rapidly absorb pools of shed blood, gauze fails to provide strong surface (topical) hemostasis. The result can be excess hemorrhage-related morbidity and mortality. We hypothesized that cost-effective materials (based on widespread availability of bulk fibers for other commercial uses) could be designed based on fundamental hemostatic principles to partially emulate the wicking properties of gauze while concurrently stimulating superior hemostasis. A panel of readily available textile fibers was screened for the ability to activate platelets and the intrinsic coagulation cascade in vitro. Type E continuous filament glass and a specialty rayon fiber were identified from the material panel as accelerators of hemostatic reactions and were custom woven to produce a dual fiber textile bandage. The glass component strongly activated platelets while the specialty rayon agglutinated red blood cells. In comparison with gauze in vitro, the dual fiber textile significantly enhanced the rate of thrombin generation, clot generation as measured by thromboelastography, adhesive protein adsorption and cellular attachment and activation. These results indicate that hemostatic textiles can be designed that mimic gauze in form but surpass gauze in ability to accelerate hemostatic reactions. PMID:19489008

Fischer, Thomas H.; Vournakis, John N.; Manning, James E.; McCurdy, Shane L.; Rich, Preston B.; Nichols, Timothy C.; Scull, Christopher M.; McCord, Marian G.; Decorta, Joseph A.; Johnson, Peter C.; Smith, Carr J.

2011-01-01

296

Accelerated and real-time geosynchronous life cycling test performance of nickel-hydrogen batteries  

Microsoft Academic Search

RCA Astro-Electronics currently has four nickel-hydrogen storage battery modules (11 cells each) on test in simulated geosynchronous life cycle regimes. These battery modules are of identical design to those used on the GSTAR (GTE Satellite Corp.) and Spacenet (GTE Spacenet Corp.) communications satellites. The batteries are being tested using an automated test station equipped with computer-controlled environmental chambers and recording

R. S. Green

1985-01-01

297

Facility for Advanced Accelerator Experimental Tests at SLAC (FACET) Conceptual Design Report  

SciTech Connect

This Conceptual Design Report (CDR) describes the design of FACET. It will be updated to stay current with the developing design of the facility. This CDR begins as the baseline conceptual design and will evolve into an 'as-built' manual for the completed facility. The Executive Summary, Chapter 1, gives an introduction to the FACET project and describes the salient features of its design. Chapter 2 gives an overview of FACET. It describes the general parameters of the machine and the basic approaches to implementation. The FACET project does not include the implementation of specific scientific experiments either for plasma wake-field acceleration for other applications. Nonetheless, enough work has been done to define potential experiments to assure that the facility can meet the requirements of the experimental community. Chapter 3, Scientific Case, describes the planned plasma wakefield and other experiments. Chapter 4, Technical Description of FACET, describes the parameters and design of all technical systems of FACET. FACET uses the first two thirds of the existing SLAC linac to accelerate the beam to about 20GeV, and compress it with the aid of two chicanes, located in Sector 10 and Sector 20. The Sector 20 area will include a focusing system, the generic experimental area and the beam dump. Chapter 5, Management of Scientific Program, describes the management of the scientific program at FACET. Chapter 6, Environment, Safety and Health and Quality Assurance, describes the existing programs at SLAC and their application to the FACET project. It includes a preliminary analysis of safety hazards and the planned mitigation. Chapter 7, Work Breakdown Structure, describes the structure used for developing the cost estimates, which will also be used to manage the project. The chapter defines the scope of work of each element down to level 3.

Amann, J.; Bane, K.; /SLAC

2009-10-30

298

Lifetime Measurements of Carbon and Diamond Stripping Foils Tested in the Fermi National Accelerator Laboratory Linac  

Microsoft Academic Search

A foil testing apparatus was fabricated to test carbon versus diamond stripper foil life expectancy. The goal of this experiment is to find a target material more suitable for the proposed multi-mega-watt 8-GeV proton driver and booster system, which uses multiturn charge-exchange injection. Preparation includes tuning bending and quadrupole magnets and doing calculations of pertinent theoretical values, such as instantaneous

Trivia Penns Frazier

299

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

300

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

301

THE MECHANICAL AND SHIELDING DESIGN OF A PORTABLE SPECTROMETER AND BEAM DUMP ASSEMBLY AT BNLS ACCELERATOR TEST FACILITY.  

SciTech Connect

A portable assembly containing a vertical-bend dipole magnet has been designed and installed immediately down-beam of the Compton electron-laser interaction chamber on beamline 1 of the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL). The water-cooled magnet designed with field strength of up to 0.7 Tesla will be used as a spectrometer in the Thompson scattering and vacuum acceleration experiments, where field-dependent electron scattering, beam focusing and energy spread will be analyzed. This magnet will deflect the ATF's 60 MeV electron-beam 90{sup o} downward, as a vertical beam dump for the Compton scattering experiment. The dipole magnet assembly is portable, and can be relocated to other beamlines at the ATF or other accelerator facilities to be used as a spectrometer or a beam dump. The mechanical and shielding calculations are presented in this paper. The structural rigidity and stability of the assembly were studied. A square lead shield surrounding the assembly's Faraday Cup was designed to attenuate the radiation emerging from the 1 inch-copper beam stop. All photons produced were assumed to be sufficiently energetic to generate photoneutrons. A safety evaluation of groundwater tritium contamination due to the thermal neutron capturing by the deuterium in water was performed, using updated Monte Carlo neutron-photon coupled transport code (MCNP). High-energy neutron spallation, which is a potential source to directly generate radioactive tritium and sodium-22 in soil, was conservatively assessed in verifying personal and environmental safety.

HU,J.P.; CASEY,W.R.; HARDER,D.A.; PJEROV,S.; RAKOWSKY,G.; SKARITKA,J.R.

2002-09-05

302

Accelerated Testing of HT-9 with Zirconia Coatings Containing Gallium using Raman Spectroscopy and XPS  

SciTech Connect

Laser Raman spectroscopy and x-ray photoelectron spectroscopy were used to study the evolution of composition of oxide films in the presence of zirconia coatings on miniature HT-9 alloy specimens subjected to elevated temperature in air. The experiments expanded on previous efforts to develop a quick-screening technique for candidate alloys for cladding materials (HT-9) and actinide-based mixed oxide fuel mixtures (represented by the zirconia coating) by investigating the effect of both coating composition and alloy pretreatment conditions on the high temperature reactions. In particular, the presence of the element Ga (a potential impurity in mixed oxide fuel) in the initial zirconia coating was found to accelerate the rate of oxide growth relative to that of yttria-stabilized zirconia studied previously. In addition, HT-9 samples that were subjected to different thermal pretreatments gave different results. The results suggest that the presence of Ga in a mixed oxide fuel will enhance the corrosion of HT-9 cladding under the conditions of this study, although the extent of enhancement is influenced by thermal pretreatment of the cladding material. The results also demonstrate the need to combine Raman spectroscopy with other techniques, particularly photoelectron spectroscopy, for optimizing composition and/or fabrication conditions of both cladding and oxide fuels for advanced nuclear reactors.

Windisch, Charles F.; Henager, Charles H.; Engelhard, Mark H.; Bennett, Wendy D.

2009-12-01

303

Direct Measurement of the Positive Acceleration of the Universe and Testing Inhomogeneous Models under Gravitational Wave Cosmology  

E-print Network

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 $\\Lambda$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 $\\Lambda$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 Lema\\^itre-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 $z\\sim 0$. 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 $\\alp...

Yagi, Kent; Yoo, Chul-Moon

2011-01-01

304

Direct Measurement of the Positive Acceleration of the Universe and Testing Inhomogeneous Models under Gravitational Wave Cosmology  

E-print Network

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 $\\Lambda$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 $\\Lambda$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 Lema\\^itre-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 $z\\sim 0$. 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 $\\alpha$ forest.

Kent Yagi; Atsushi Nishizawa; Chul-Moon Yoo

2011-12-28

305

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

306

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

307

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

308

Development of an Accelerated Test Method for the Determination of Susceptibility to Atmospheric Corrosion  

NASA Technical Reports Server (NTRS)

The theoretical rationale is presented for use of a repetitive cyclic current reversal voltammetric technique for characterization of localized corrosion processes, including atmospheric corrosion. Applicability of this proposed experimental protocol is applied to characterization of susceptibility to crevice and pitting corrosion, atmospheric corrosion and stress corrosion cracking. Criteria upon which relative susceptibility is based were determined and tested using two iron based alloys commonly in use at NASA-Kennedy; A36 (a low carbon steel) and 4130 (a low alloy steel). Practicality of the procedure was demonstrated by measuring changes in anodic polarization behavior during high frequency current reversal cycles of 25 cycles per second with 1 mA/sq cm current density amplitude in solutions containing Cl anions. The results demonstrated that, due to excessive polarization which affects conductivity of barrier corrosion product layers, A36 was less resistant to atmospheric corrosion than its 4130 counterpart; behavior which was also demonstrated during exposure tests.

Ambrose, John R.

1991-01-01

309

An RF Waveguide Distribution System for the ILC Test Accelerator at Fermilab's NML  

SciTech Connect

An ILC R&D facility is being constructed in the NML building at Fermilab which, in addition to an injector and beam dump with spectrometer, will contain up to three cryomodules of ILC-type superconducting 9-cell cavities. This linac will be powered by a single klystron. As part of SLAC's contribution to this project, we will provide a distribution network in WR650 waveguide to the various cavity couplers. In addition to commercial waveguide components and circulators and loads, this system will include adjustable tap-offs, and customized hybrids. In one configuration, the circulators will be removed to test pair-wise cancellation of cavity reflections through hybrids. The system will be pressurized with nitrogen to 3 bar absolute to avoid the need for SF{sub 6}. The full distribution system for the first cryomodule will be delivered and installed later this year. We describe the design of the system and completed RF testing.

Nantista, Christopher; Adolphsen, Chris; Bowden, Gordon; Swent, Richard; McKee, Bobby; /SLAC

2007-06-27

310

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

311

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

Microsoft Academic Search

The seismic-fragility response of naturally-aged nuclear station safety-related batteries is of interest for two reasons: (1) to determine actual failure modes and thresholds and (2) to determine the validity of using the electrical capacity of individual cells as an indicator of the potential survivability of a battery given a seismic event. Prior reports in this series discussed the seismic-fragility tests

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

1987-01-01

312

Accelerated post-glucose glycaemia and altered alliesthesia-test in Seasonal Affective Disorder  

Microsoft Academic Search

Background: Little is known about the link between mood, food and metabolic function in Seasonal Affective Disorder (SAD). Methods: We investigated this link in a combined glucose tolerance–alliesthesia test in eight SAD patients in winter before and after one week light therapy, and in summer. Results: SAD patients exhibited faster post-glucose glycaemic and insulin responses (p<0.05), and increased hedonic ratings

Kurt Kräuchi; Ulrich Keller; Georg Leonhardt; Daniel P. Brunner; Peter van der Velde; Hans-Joachim Haug; Anna Wirz-Justice

1999-01-01

313

Scaled Accelerator Test For the DARHT-II Downstream Transport System  

Microsoft Academic Search

The second axis of the dual axial radiography hydrodynamic test (DARHT-II) facility at LANL is currently in the commissioning phase. The beam parameters for the DARHT-II machine will be nominally 17 MeV, 2 kA and 1.6 mus. This makes the DARHT-II downstream system the first system ever designed to transport a high current, high energy and long pulse beam [2].

Yu-Jiuan Chen; D. T. Blackfield; G. J. Caporaso; G. Guethlein; J. F. McCarrick; A. C. Paul; J. A. Watson; J. T. Weir

2005-01-01

314

Neural Network Models of Simple Mechanical Systems Illustrating the Feasibility of Accelerated Life Testing  

NASA Technical Reports Server (NTRS)

A complete evaluation of the tribological characteristics of a given material/mechanical system is a time-consuming operation since the friction and wear process is extremely systems sensitive. As a result, experimental designs (i.e., Latin Square, Taguchi) have been implemented in an attempt to not only reduce the total number of experimental combinations needed to fully characterize a material/mechanical system, but also to acquire life data for a system without having to perform an actual life test. Unfortunately, these experimental designs still require a great deal of experimental testing and the output does not always produce meaningful information. In order to further reduce the amount of experimental testing required, this study employs a computer neural network model to investigate different material/mechanical systems. The work focuses on the modeling of the wear behavior, while showing the feasibility of using neural networks to predict life data. The model is capable of defining which input variables will influence the tribological behavior of the particular material/mechanical system being studied based on the specifications of the overall system.

Fusaro, Robert L.; Jones, Steven P.; Jansen, Ralph

1996-01-01

315

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

316

Vacuum seals design and testing for a linear accelerator of the National Spallation Neutron Source  

SciTech Connect

Vacuum seals are very important to ensure that the Spallation Neutron Source (SNS) Linac has an optimum vacuum system. The vacuum joints between flanges must have reliable seals to minimize the leak rate and meet vacuum and electrical requirements. In addition, it is desirable to simplify the installation and thereby also simplify the maintenance required. This report summarizes an investigation of the metal vacuum seals that include the metal C-seal, Energized Spring seal, Helcoflex Copper Delta seal, Aluminum Delta seal, delta seal with limiting ring, and the prototype of the copper diamond seals. The report also contains the material certifications, design, finite element analysis, and testing for all of these seals. It is a valuable reference for any vacuum system design. To evaluate the suitability of several types of metal seals for use in the SNS Linac and to determine the torque applied on the bolts, a series of vacuum leak rate tests on the metal seals have been completed at Los Alamos Laboratory. A copper plated flange, using the same type of delta seal that was used for testing with the stainless steel flange, has also been studied and tested. A vacuum seal is desired that requires significantly less loading than a standard ConFlat flange with a copper gasket for the coupling cavity assembly. To save the intersegment space the authors use thinner flanges in the design. The leak rate of the thin ConFlat flange with a copper gasket is a baseline for the vacuum test on all seals and thin flanges. A finite element analysis of a long coupling cavity flange with a copper delta seal has been performed in order to confirm the design of the long coupling cavity flange and the welded area of a cavity body with the flange. This analysis is also necessary to predict a potential deformation of the cavity under the combined force of atmospheric pressure and the seating load of the seal. Modeling of this assembly has been achieved using both HKS/Abaqus and COSMOS/M, which are finite element packages for analysis of coupled, nonlinear problems. From these studies, the appropriate seals that are reliable for SNS long coupling cavities and beamline joints were determined.

Z. Chen; C. Gautier; F. Hemez; N. K. Bultman

2000-02-01

317

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

318

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

319

Structural Benchmark Testing for Stirling Converter Heater Heads  

NASA Astrophysics Data System (ADS)

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

320

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

321

Study of the degradation mechanisms of carbon-supported platinum fuel cells catalyst via different accelerated stress test  

NASA Astrophysics Data System (ADS)

A combination method based on three different accelerated stress test (AST) protocols along with the monitoring of electrochemical surface area (ECSA), oxygen reduction reaction (ORR) activities, X-Ray photoelectron spectrometer (XPS), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS) response is introduced to investigate the degradation mechanisms of carbon-supported platinum (Pt/C) catalyst. By comparing the ECSA and ORR activity loss under different AST protocols, we revealed that the activity loss in AST can be divided into recoverable activity loss and unrecoverable activity loss. The recoverable activity loss is attributed to the reduction of Pt oxide or partially due to the removal of CO formed during carbon corrosion. The unrecoverable activity loss is ascribed to the Pt dissolution/re-deposition, agglomeration, detachment and carbon corrosion. XPS results show that the Pt dissolution/re-deposition in AST can be detected by using a more negative potential window. TEM images and analysis confirmed that the Pt growth mode in this study is mainly due to the Pt agglomeration rather than dissolution/re-deposition. EIS analysis reveals that the alternative decomposition/formation of oxygen containing groups over time is the main corrosion pathway of carbon support. These findings are very important for understanding Pt/C catalyst degradation and are also useful for developing fast test protocol for screening new durable catalyst materials.

Zhang, Yuanliang; Chen, Siguo; Wang, Yao; Ding, Wei; Wu, Rui; Li, Li; Qi, Xueqiang; Wei, Zidong

2015-01-01

322

Tests of an environmental and personnel safe cleaning process for BNL accelerator and storage ring components  

SciTech Connect

A large measure of the successful operation of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL) for over a decade can be attributed to the cleaning of its UHV components during and after construction. A new UHV cleaning process, which had to be environmentally and personnel safe, was needed to replace the harsh, unfriendly process which was still in use. Dow Advanced Cleaning Systems was contracted to develop a replacement process without the use of harsh chemicals and which must clean vacuum surfaces as well as the existing process. Acceptance of the replacement process was primarily based on Photon Stimulated Desorption (PSD) measurements of beam tube samples run on NSLS beam line U10B. One meter long beam tube samples were fabricated from aluminum, 304 stainless steel and oxygen free copper. Initially, coupon samples were cleaned and passed preliminary testing for the proposed process. Next, beam tube samples of each material were cleaned, and the PSD measured on beam line U10B using white light with a critical energy of 487 ev. Prior to cleaning, the samples were contaminated with a mixture of cutting oils, lubricants, vacuum oils and vacuum grease. The contaminated samples were then baked. Samples of each material were also cleaned with the existing process after the same preparation. Beam tube samples were exposed to between 10{sup 22} and 10{sup 23} photons per meter for a PSD measurement. Desorption yields for H{sub 2}, CO, CO{sub 2}, CH{sub 4} and H{sub 2}O are reported for both the existing cleaning and for the replacement cleaning process. Preliminary data, residual gas scans, and PSD results are given and discussed. The new process is also compared with new cleaning methods developed in other laboratories.

Foerster, C.L.; Lanni, C.; Lee, R. [Brookhaven National Lab., Upton, NY (United States); Mitchell, G.; Quade, W. [Dow Chemical Advanced Cleaning Systems, Midland, MI (United States)

1996-10-01

323

Relaxation of the accelerating-gas boundary layer to the test-gas boundary layer on a flat plate in an expansion tube  

NASA Technical Reports Server (NTRS)

An analytic investigation of the relaxation of the accelerating-gas boundary layer to the test-gas boundary layer over a flat plate mounted in an expansion tube has been conducted. In this treatment, nitrogen has been considered as the test gas and helium as the accelerating gas. The problem is analyzed in two conically similar limits: (1) when the time lag between the arrival of the shock and the interface at the leading edge of the plate is very large, and (2) when this time lag is negligible. The transient laminar boundary-layer equations of a perfect binary-gas mixture are taken as the flow governing equations. These coupled equations have been solved numerically by Gauss-Seidel line-relaxation method. The results predict the transient behavior as well as the time required for an all-helium accelerating-gas boundary layer to relax to an all-nitrogen boundary layer.

Gupta, R. N.; Trimpi, R. L.

1973-01-01

324

Vacuum Performance and Beam Life Time in the PEP-II Storage Rings  

SciTech Connect

The vacuum systems of the storage rings of the PEP-II B-Factory have had by now over two years of production running at high beam current and seen synchrotron radiation from almost 4 kAh High Energy Ring (HER) and 10 kAh Low Energy Ring (LER) of integrated beam current. The systems have performed well, reaching the design pressures and being able to cope with beam currents of almost 1 A HER and in excess of 2 A LER. The photo-desorption coefficient {eta} was found in the HER to have reached values as low as 10{sup -7}. The shielded bellows have performed very well, with only one pair of bellows assemblies damaged due to higher-order mode generation from a known, nearby source. Issues encountered during normal operation have been a significant amount of dust trapping in the HER and the effect of a cloud of photo-electrons around the positron beam affecting the LER beam size. A couple of chambers in the HER failed; these failures arose from a combination of design and fabrications issues. The beam life time in the LER has been lower than expected based on the vacuum pressure and has been determined to be Touschek limited.

Wienands, Uli

2002-08-21

325

Loss of consciousness as criterion of +Gz tolerance at Institute of Aviation Medicine MMA during +Gz acceleration selective test.  

PubMed

+Gz induced loss of consciousness (G-LOC) is one of the most serious threats to aircrews flying high performance fighter aircraft. From the early beginning of use of our Centrifuge, use in selection was primary task. As a functional "endpoints" we use criteria: loss of peripheral vision, extreme pulse rate (above 180 b.p.m.), arrhythmias and loss of consciousness. The key-method in selection the candidate who tolerates +Gz stress on the best way is selection by common selective centrifuge "Test of linear increasing of acceleration" (TOLIA). We used gradual onset rate (GOR--0.1 G/s) and maximum/peak value: +5.5 Gz, +6.0 Gz and 7.0 Gz. Applied peak value depends on the goal of the test. The lowest peak value is for candidates planned for Air Academy, higher peak value is for those pilots planned for training to supersonic combat aircrafts and the highest peak value is for pilots who are planned to fly High performance combat aircrafts. We examined 2192 candidates in the last 20 years. Eleven subjects experienced G-LOC episodes. All episodes of G-LOC had occurred occasionally and without warning symptoms (loss of peripheral vision, gray out, blackout). The percentage of subjects having G-LOC episodes was 0.50%. Nine subjects experienced G-LOC during primary selection (+5.5 Gz), one G-LOC were observed at secondary selection (+6.0 Gz) and one G-LOC was observed during tertiary selection (+7 Gz). G-LOC is the only "endpoint" in the centrifuge selection which disqualifies the candidate at once and forever for planned flying duties. The other "endpoints" (loss of peripheral vision, heart rate above 180 b.p.m., arrhythmias) allow one more testing, not less than seven days later. PMID:17191669

Rudnjanin, S; Arsic-Komljenovic, G; Pavlovic, M; Vujnovic, J

2006-12-01

326

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

327

Assessment of drug release from oil depot formulations using an in vitro model -- potential applicability in accelerated release testing.  

PubMed

In vitro drug release and transport rates from oil depot formulations under nonsink conditions have been investigated in the rotating dialysis cell model. Eight model drug compounds and eight oil vehicle compositions were used for the releaseexperiments. The experimentally obtained apparent first-order rate constants related to the drug appearance in the acceptor phase after initial instillation of a drug-containing oil solution were found to be in excellent agreement with the rate constants obtained from a theoretically derived expression. It was observed that the drug oil-water distribution coefficient was the key parameter influencing the release characteristics. As compared with ketoprofen, flurbiprofen exhibited a higher affinity for the oil, resulting in a significantly lower and more slowly decreasing drug concentrations in the aqueous donor compartment. Release profiles for prilocaine and the more lipophilic agent bupivacaine after incorporation of both drugs in fractionated coconut oil were characterized by a fast release of prilocaine, whereas bupivacaine was liberated much slower to the acceptor phase. The high oil-buffer interfacial area generated in vitro by rotation of the donor cell tends to overestimate release rates in comparison to those expected in vivo, for example, after intra-articular administration of oil solutions. The present in vitro method may constitute a valuable tool in accelerated in vitro release testing of parenteral oil depot formulations in areas comprising formulation design and product quality control. PMID:18363145

Larsen, Susan Weng; Jessen, Marit N B; Ostergaard, Jesper; Larsen, Claus

2008-03-01

328

Induction of apoptosis by accelerated heavy-ion beams in cultured fetal rat testes and its modification  

NASA Astrophysics Data System (ADS)

The increasing human activities in space missions make the study on effects from high-LET ionizing radiation an important issue to be addressed. We reported previously that prenatal irradiations with heavy-ion beams on gestation day 15 generally induced markedly detrimental effects on prenatal gonads, postnatal testicular development and male breeding activity in rats. To explore the mechanisms involved in radiation-induced gonocyte apoptosis in fetal gonads, which played a critical role in the fate of postnatal testis development, accelerated heavy-ion irradiations and organotypic culture of Wistar fetal rat testes were applied to investigations focused on cellular and molecular events after irradiations with or without chemical addition. Results showed that, in addition to the clustered distribution, both the time course and the percentage of apoptosis in gonocytes on gestation day 15 equivalent in vitro appeared similar to that in utero after exposure to either carbon-ion beams with a LET value of about 13 keV/µm or neon-ion beams with a LET value of about 30 keV/µm. Irradiations induced increased p53 expression in a dose dependent manner and decreased expressions of p21 and Bcl- 2 by Western Blot examination. Administration of pan-caspase inhibitor prior to irradiations effectively inhibited apoptosis occurrence and reduced the extent of clustered apoptosis, while such effects were not observed with the presence of p53 inhibitor, gap junction inhibitor, or nitric oxide specific scavenger. These findings indicated that irradiations of cultured fetal rat testes manifested pathologically similar apoptosis induction in gonocytes to that in utero. P53 expression was possibly responsible for the response to radiation damage rather than induction of apoptosis. The syncytial organization of gonocytes played a key role in formation of the clustered apoptosis, an event that both gap junction inhibitor and nitric oxide specific scavenger were incapable of preventing.

Wang, Bing; Tanaka, Kaoru; Shang, Yi; Fujita, Kazuko; Ninomiya, Yasuharu; Moreno, Stephanie G.; Coffigny, Herve; Hayata, Isamu; Murakami, Masahiro; Eguchi-Kasai, Kiyomi; Nenoi, Mitsuru

329

Life time suicidal thoughts in an urban community in Hanoi, Vietnam  

PubMed Central

Background Suicidal thought is a risk factor and a stage in the suicidal process from planning to attempting and dying by suicide. To date, studies on suicidal thought in the general population, especially in Asian communities, have been limited. Method The WHO SUPRE-MISS (the multisite intervention study on suicidal behaviours) community survey questionnaire was filled in for 2,280 randomly selected residents of the DongDa district of Hanoi, Vietnam by means of face-to-face interviews. This multi-factor questionnaire includes such variables as sociodemographic information, suicidal thought and history of suicide attempts, physical health, alcohol consumption and medication. Results Prevalence rates for life time suicidal thoughts, suicide plans and suicide attempts were 8.9%, 1.1% and 0.4% respectively. Suicidal thoughts are associated with multiple characteristics, such as female gender, single/widowed/separated/divorced marital status, low income, lifestyle (use of alcohol, sedatives and pain relief medication), but not with low education or employment status. Having no religion and being a Buddhist appear to be protective factors for suicidal thought. The ratio of suicidal thoughts, suicide plans and suicide attempts on a lifetime basis is 22.3:2.8:1. Conclusion In Vietnam, as in Western and other Asian countries, suicidal thoughts are associated with similar negative psychosocial risk factors, lifestyle and emotional problems, which implies that suicide preventive measure developed elsewhere can be adjusted to Vietnamese condition. Understanding the unique and common risks in a culture may assist in prediction and control. PMID:16563173

Thanh, Huong Tran Thi; Tran, Trung Nam; Jiang, Guo-Xin; Leenaars, Antoon; Wasserman, Danuta

2006-01-01

330

Supervised learning of a regression model based on latent process. Application to the estimation of fuel cell life time  

E-print Network

of fuel cell life time Raïssa Onanena(1) , Faicel Chamroukhi(1) , Latifa Oukhellou(1)(2) , Denis Candusso to estimate fuel cell duration time from electrochemical impedance spectroscopy measurements. It consists for the estimation of fuel cell time duration. The performances of the proposed approach are evaluated

Chamroukhi, Faicel

331

Final Report on "Development and Testing of Advanced Accelerator Structures and Technologies at 11.424 GHz"  

SciTech Connect

This is the final report on the research program ?Development and Testing of Advanced Accelerator Structures and Technologies at 11.424 GHz,? which was carried out by the Naval Research Laboratory (NRL) under Interagency Agreement DE?AI02?01ER41170 with the Department of Energy. The period covered by this report is 15 July 2010 ? 14 July 2013. The program included two principal tasks. Task 1 involved a study of the key physics issues related to the use of high gradient dielectric-loaded accelerating (DLA) structures in rf linear accelerators and was carried out in collaboration with Argonne National Laboratory (ANL) and Euclid Techlabs LLC. Task 2 involved a study of high power active microwave pulse compressors and was carried out in collaboration with Omega-P, Inc. and the Institute of Applied Physics of the Russian Academy of Sciences in Nizhny Novgorod. The studies under Task 1 were focused on rf-induced multipactor and breakdown in externally driven DLA structures at the 200-ns timescale. Suppression of multipactor and breakdown are essential to the practical application of dielectric structures in rf linear accelerators. The structures that were studied were developed by ANL and Euclid Techlabs and their performance was evaluated at high power in the X-band Magnicon Laboratory at NRL. Three structures were designed, fabricated, and tested, and the results analyzed in the first two years of the program: a clamped quartz traveling-wave (TW) structure, a externally copper-coated TW structure, and an externally copper-coated dielectric standing-wave (SW) structure. These structures showed that rf breakdown could be largely eliminated by eliminating dielectric joints in the structures, but that the multipactor loading was omnipresent. In the third year of the program, the focus of the program was on multipactor suppression using a strong applied axial magnetic field, as proposed by Chang et al. [C. Chang et al., J. Appl. Phys. 110, 063304 (2011).], and a successful experiment was carried out that demonstrated suppression of multipactor in the uniform-field region of a TW DLA structure. However, in accordance with theory, the multipactor was enhanced in regions of the structure with lower values of axial magnetic field. Under Task 2, there were two two-month experimental runs at NRL that were used to characterize the performance of high power two-channel dual-mode active microwave pulse compressor configurations that used electron-beam triggered switch cavities. The pulse compressors were designed and fabricated by Omega-P, Inc. and the Russian Institute of Applied Physics and tested in the Magnicon Laboratory at NRL. These pulse compressors made use of an electron beam discharge from a cylindrical knife-edged Mo cathode coated with a CVD diamond film that was driven by a ?100 kV, 100 ns high voltage pulse. The electron beam was used to change the resonant frequency of the switch cavities in order to create the output microwave pulse. The compressor channels included a TE01 input and output section and a TE02 energy storage cavity, followed by a switch assembly that controlled the coupling between the TE01 and TE02 modes. In the initial state, the switch cavity was in resonance, the reflection from the cavity was out of phase, and the mode conversion was only ~2-3%, allowing the energy storage cavity to fill. When the electron beam was discharged into the switch cavity, the cavity was shifted out of resonance, causing the phase of the reflection to change by ~?. As a result of the change in the reflection phase, the mode coupling in the conical taper was greatly increased, and could approach ~100%, permitting the energy storage cavity to empty in one cavity round trip time of the TE02 mode to produce a high power output pulse. The second experiment runs demonstrated a 190 MW, ~20 ns compressed pulse at 25.7 gain and ~50% efficiency, using a 7.4 MW, 1 ?s drive pulse from the magnicon. The success of this experiment suggests a path to future high gain active versions of the SLED 2 pulse compressor at SLAC.

Gold, Steven H. [Naval Research Laboratory

2013-10-13

332

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

333

Linear Accelerators  

SciTech Connect

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 [Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna (Russian Federation)

2010-01-05

334

A Novel Angular Acceleration Sensor Based on the Electromagnetic Induction Principle and Investigation of Its Calibration Tests  

PubMed Central

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

335

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

336

The Effect of Maternal Relaxation Training on Reactivity of Non-Stress Test, Basal Fetal Heart Rate, and Number of Fetal Heart Accelerations: A Randomized Controlled Trial  

PubMed Central

Background: Relaxation-training, as an anxiety-reducer intervention, plays an important role in fetal health. The present study aimed to analyze the effect of maternal relaxation on stress test (NST), basal fetal heart rate, and number of fetal heart accelerations. Methods: In this randomized controlled trial, 84 pregnant women were randomly divided into two groups of teaching relaxation and control groups in 2012. In the intervention group, 60-90 minute classes were held every week lasting for 4 weeks. Besides, home practice charts were given to the mothers and researchers controlled the home practices by phone calls every week. The control group received routine prenatal care. In the 4th week, NST was performed in the intervention group 30 minutes before and after the 4th session. In the control group, NST was done in the 4th week. The quantitative variables in the two groups were compared through ANOVA and Chi-square test. Results: The results of paired t-test showed that relaxation could improve the NST results (P=0.01). Mean and standard deviation of basal fetal heart rate was 138.95±8.18 before the intervention and 133.07±6.9 after the intervention. Paired t-test also showed that relaxation reduced the basal fetal heart rate (P=0.001). Mean and standard deviation of the number of fetal heart accelerations was 1.5±0.8 before the intervention and 2.2±0.9 after it. The results of paired t-test also showed that relaxation increased the number of fetal heart accelerations (P=0.001). Conclusions: Relaxation could improve the NST results, reduce the basal fetal heart rate, and increase the number of fetal heart accelerations. Therefore, relaxation is recommended during pregnancy. Trial Registration Number: IRCT2012072810418N1 PMID:25553334

Akbarzade, Marzieh; Rafiee, Bahare; Asadi, Nasrin; Zare, Najaf

2015-01-01

337

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

338

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

Microsoft Academic Search

The thermal reliability of a closed-type BLDC motor for a high-speed fan is analyzed by an accelerated-life testing and numerical\\u000a 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\\u000a and electronic components in the PCB module cannot be effectively removed to the outside. Therefore,

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

2008-01-01

339

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

Microsoft Academic Search

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

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

2009-01-01

340

Physically Based Rendering Intersection Acceleration  

E-print Network

Physically Based Rendering (600.657) Intersection Acceleration #12;Intersection Testing Accelerated partitions: Group objects into clusters Cluster volumes may overlap #12;Uniform (Voxel) Grid Acceleration Acceleration · Trace rays through grid cells ­ Fast ­ Incremental A B C D E F Only check primitives

Kazhdan, Michael

341

Stability of CIGS solar cells and component materials evaluated by a step-stress accelerated degradation test method  

NASA Astrophysics Data System (ADS)

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 15°C and then a 15% relative humidity (RH) increment step, beginning from 40°C/40%RH (T/RH = 40/40) to 85°C/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

342

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

343

Discharge properties of neurons in the monkey thalamus tested with angular acceleration, eye movement and visual stimuli  

Microsoft Academic Search

Summary  Monkeys were trained to make visually evoked eye movements while undergoing simultaneous head rotation. Single units were recorded in the pregeniculate nucleus (PGN). PGN neurons discharged during each saccade, but there was no change in activity with horizontal head acceleration or with various combinations of head and smooth pursuit eye movements as previously described in the cat. Therefore, the anatomical

M. Magnin; A. F. Fuchs

1977-01-01

344

Accelerated cycle life testing of lead-acid golf car batteries and the influence of separator type on battery life, energy consumption and operating cost  

NASA Astrophysics Data System (ADS)

Commercial lead-acid golf car batteries containing five different separator materials were cycle life tested. An accelerated cycle life test was employed in which the battery temperature was allowed to rise as the batteries became less efficient in power utilization towards the end of life, and there was no rest period between charge and discharge during cycling. The effects of continuous cycling and separator type on battery performance were monitored throughout the test together with battery temperature, end of charge current, energy balances, and capacity. Cycle life test data through correlation with actual expected life in the field allowed calculations to be made to determine the relative effective operating cost of various battery types. The battery made with FLEX-SIL® rubber separators exhibited the best life and economics when compared with batteries containing ACE-SILC® rubber, polyethylene, cellulose (paper), and sintered PVC separators.

Goldberg, Bruce S.; Hausser, Alexander G.; Le, Bich T.

345

The Orientation and Grain Texture Effect on Life Time Reliability of Sol-Gel Derived PbZr0.52Ti0.48O3 Films  

NASA Astrophysics Data System (ADS)

We fabricated Pb(Zr,Ti)O3 (PZT) films with different orientations and grain textures by the sol-gel method. The fabricated films were tested using the high accelerated lifetime testing system. As a result, films with coarse grain texture exhibited longer lifetimes and a higher acceleration factor than those with fine-grained texture. The film orientation did not affect the mean time to failure of the film. This suggests that breaking phenomena are strongly dependent on the number of grain boundaries.

Doi, Toshihiro; Noguchi, Takashi; Fuji, Jun; Soyama, Nobuyuki; Sakurai, Hideaki

2012-09-01

346

Statistical analysis of accelerated experiments in mechanics using a mechanical accelerated life model  

Microsoft Academic Search

Accelerated testing of mechanical products offers great potential for development in reliability life testing. Unfortunately, difficulties met in accelerated life testing have limited its applications and acceptance. This paper presents a discussion of the different approaches to accelerate life of mechanical materials. The importance of failure mechanism models and the separate treatment of failure mechanisms during accelerated life tests are

O. Tebbi; F. Guerin; B. Dumon

2003-01-01

347

Transition points in steel fibre pull-out tests from magnesium phosphate and accelerated calcium aluminate binders  

Microsoft Academic Search

Results are reported on the pull-out characteristics of two distinct types of steel fibre from two different rapid strengthening matrices, magnesia phosphate and accelerated calcium aluminate. The procedure incorporated a novel method of identifying the force necessary to initiate whole fibre movement relative to the matrix, one of the key transition points in the force\\/displacement relationship. Significantly different force\\/displacement relationships

P. Frantzis; R. Baggott

2003-01-01

348

A normalization method for life-time prediction of composite materials  

E-print Network

Introduction Industrials are increasingly using more composite materi- als in various fields particularly in aviation and automobiles fields. Their great advantage is their strength and stiffness associated are given. 2 Materials and test 2.1 Materials The studied materials were manufactured by moulding composite

Paris-Sud XI, Université de

349

New limit on the proton life-time independent on channel from the neutrino experiments with heavy water  

NASA Astrophysics Data System (ADS)

Experimental data on the number of neutrons born in the heavy water targets of the large neutrino detectors are used to set the limit on the proton life-time independently on decay mode through the reaction d ? n + ?. The best up-to-date limit ? p > 4×10 23 yr with 95% C.L. is derived from the measurements with D 2O target (mass 267 kg) installed near the Bugey reactor. This value can be improved by six orders of magnitude with future data accumulated with the SNO detector containing 1000 t of D 2O.

Tretyak, V. I.; Zdesenko, Yu. G.

2002-07-01

350

Mosapride Accelerates the Delayed Gastric Emptying of High-Viscosity Liquids: A Crossover Study Using Continuous Real-Time 13C Breath Test (BreathID System)  

PubMed Central

Background/Aims The administration of liquid nutrients to patients is often accompanied by complications such as gastroesophageal reflux. To prevent gastroesophageal reflux, high-viscosity liquid meals are used widely, however, it still remains controversial whether high-viscosity liquid meals have any effect on the rate of gastric emptying. The present study was conducted with the aim of determining whether high-viscosity liquid meals had any effect on the rate of gastric emptying and mosapride might accelerate the rate of gastric emptying of high-viscosity liquid meals. Methods Six healthy male volunteers underwent 3 tests at intervals of > 1 week. After fasting for > 8 hours, each subject received one of three test meals (liquid meal only, high-viscosity liquid meal [liquid meal plus pectin] only, or high-viscosity liquid meal 30 minutes after intake of mosapride). A 13C-acetic acid breath test was performed, which monitored the rate of gastric emptying for 4 hours. Using the Oridion Research Software (? version), breath test parameters were calculated. The study parameters were examined for all the 3 test conditions and compared using the Freidman test. Results Gastric emptying was significantly delayed following intake of a high-viscosity liquid meal alone as compared with a liquid meal alone; however, intake of mosapride prior to a high-viscosity liquid meal was associated with a significantly accelerated rate of gastric emptying as compared with a high-viscosity liquid meal alone. Conclusions This study showed that high-viscosity liquid meals delayed gastric emptying: however, mosapride recovered the delayed rate of gastric emptying by high-viscosity liquid meals. PMID:22148109

Sakamoto, Yasunari; Sekino, Yusuke; Yamada, Eiji; Ohkubo, Hidenori; Higurashi, Takuma; Sakai, Eiji; Iida, Hiroshi; Hosono, Kunihiro; Endo, Hiroki; Nonaka, Takashi; Ikeda, Tamon; Fujita, Koji; Yoneda, Masato; Koide, Tomoko; Takahashi, Hirokazu; Goto, Ayumu; Abe, Yasunobu; Gotoh, Eiji; Maeda, Shin; Nakajima, Atsushi

2011-01-01

351

Development and test of a cryogenic trap system dedicated to confinement of radioactive volatile isotopes in SPIRAL2 post-accelerator  

NASA Astrophysics Data System (ADS)

A cryogenic trap system called Cryotrap has been studied and developed in the framework of nuclear safety studies for SPIRAL2 accelerator. The main objective of Cryotrap is to confine and reduce strongly the migration of radioactive volatile isotopes in beam lines. These radioactive gases are produced after interaction between a deuteron beam and a fissile target. Mainly, Cryotrap is composed by a vacuum vessel and two copper thermal screens maintained separately at two temperatures T1=80 K and T2=20 K. A Cryocooler with two stages at previous temperatures is used to remove static heat losses of the cryostat and ensure an efficient cooling of the system. Due to strong radiological constraints that surround Cryotrap, the coupling system between Cryocooler and thermal screens is based on aluminum thermo-mechanical contraction. The main objective of this original design is to limit direct human maintenance interventions and provide maximum automated operations. A preliminary prototype of Cryotrap has been developed and tested at GANIL laboratory to validate its design, and determine its thermal performance and trapping efficiency. In this paper, we will first introduce briefly SPIRAL2 project and discuss the main role of Cryotrap in nuclear safety of the accelerator. Then, we will describe the proposed conceptual design of Cryotrap and its main characteristics. After that, we will focus on test experiment and analyze experimental data. Finally, we will present preliminary results of gas trapping efficiency tests.

Souli, M.; Dolégiéviez, P.; Fadil, M.; Gallardo, P.; Levallois, R.; Munoz, H.; Ozille, M.; Rouillé, G.; Galet, F.

2011-12-01

352

Accelerated/abbreviated test methods, study 4 of task 3 (encapsulation) of the low-cost silicon solar array project  

NASA Technical Reports Server (NTRS)

Inherent weatherability is controlled by the three weather factors common to all exposure sites: insolation, temperature, and humidity. Emphasis was focused on the transparent encapsulant portion of miniature solar cell arrays by eliminating weathering effects on the substrate and circuitry (which are also parts of the encapsulant system). The most extensive data were for yellowing, which were measured conveniently and precisely. Considerable data also were obtained on tensile strength. Changes in these two properties after outdoor exposure were predicted very well from accelerated exposure data.

Kolyer, J. M.; Mann, N. R.

1978-01-01

353

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

354

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

355

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

356

Accelerated life test of the USDOE OC-OTEC experimental system refurbished with magnetic bearings for the 3rd stage vacuum compressor. Final report  

SciTech Connect

This report documents the accelerated life test (time-to-failure) performed, at the request of DOE, to evaluate the viability of the magnetic bearing system installed in the stage 3 vacuum pump. To this effect the plant was successfully operated for over 500 hours during the period September-November 1996. The first part of this report discusses system performance by deriving subsystem and system performance parameters from a typical record. This is followed by the discussion of the life tests. The instrumentation used to estimate the performance parameters given here is depicted. The third stage pump was operated for 535 hours without incident. It is concluded that magnetic bearings are the preferable choice for the OC-OTEC centrifugal vacuum pumps.

Vega, L.A.

1997-04-01

357

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,

358

Black Ink and Red Ink (BIRI) Testing: A Testing Method to Evaluate Both Recall and Recognition Learning in Accelerated Adult-Learning Courses  

ERIC Educational Resources Information Center

We propose, develop, and evaluate the black ink-red ink (BIRI) method of testing. This approach uses two different methods within the same test administration setting, one that matches recognition learning and the other that matches recall learning. Students purposively define their own tradeoff between the two approaches. Evaluation of the method…

Rodgers, Joseph Lee; Rodgers, Jacci L.

2011-01-01

359

High frequency circular translation pin-on-disk method for accelerated wear testing of ultrahigh molecular weight polyethylene as a bearing material in total hip arthroplasty.  

PubMed

The temporal change of the direction of sliding relative to the ultrahigh molecular weight polyethylene (UHMWPE) component of prosthetic joints is known to be of crucial importance with respect to wear. One complete revolution of the resultant friction vector is commonly called a wear cycle. It was hypothesized that in order to accelerate the wear test, the cycle frequency may be substantially increased if the circumference of the slide track is reduced in proportion, and still the wear mechanisms remain realistic and no overheating takes place. This requires an additional slow motion mechanism with which the lubrication of the contact is maintained and wear particles are conveyed away from the contact. A three-station, dual motion high frequency circular translation pin-on-disk (HF-CTPOD) device with a relative cycle frequency of 25.3Hz and an average sliding velocity of 27.4mm/s was designed. The pins circularly translated at high frequency (1.0mm per cycle, 24.8Hz, clockwise), and the disks at low frequency (31.4mm per cycle, 0.5Hz, counter-clockwise). In a 22 million cycle (10 day) test, the wear rate of conventional gamma-sterilized UHMWPE pins against polished CoCr disks in diluted serum was 1.8mg per 24h, which was six times higher than that in the established 1Hz CTPOD device. The wear mechanisms were similar. Burnishing of the pin was the predominant feature. No overheating took place. With the dual motion HF-CTPOD method, the wear testing of UHMWPE as a bearing material in total hip arthroplasty can be substantially accelerated without concerns of the validity of the wear simulation. PMID:25498368

Saikko, Vesa

2015-01-21

360

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

361

The need for speed: testing acceleration for estimating animal travel rates in terrestrial dead-reckoning systems.  

PubMed

Numerous methods are currently available to track animal movements. However, only one of these, dead-reckoning, has the capacity to provide continuous data for animal movements over fine scales. Dead-reckoning has been applied almost exclusively in the study of marine species, in part due to the difficulty of accurately measuring the speed of terrestrial species. In the present study we evaluate the use of accelerometers and a metric known as overall dynamic body acceleration (ODBA) as a proxy for the measurement of speed for use in dead-reckoning. Data were collated from previous studies, for 10 species locomoting on a treadmill and their ODBA measured by an attached data logger. All species except one showed a highly significant linear relationship between speed and ODBA; however, there was appreciable inter- and intra-specific variance in this relationship. ODBA was then used to estimate speed in a simple trial run of a dead-reckoning track. Estimating distance travelled using speed derived from prior calibration for ODBA resulted in appreciable errors. We describe a method by which these errors can be minimised, by periodic ground-truthing (e.g., by GPS or VHF telemetry) of the dead-reckoned track and adjusting the relationship between speed and ODBA until actual known positions and dead-reckoned positions accord. PMID:22244455

Bidder, Owen R; Soresina, Marion; Shepard, Emily L C; Halsey, Lewis G; Quintana, Flavio; Gómez-Laich, Agustina; Wilson, Rory P

2012-02-01

362

Acceleration of trapped particles and beams  

E-print Network

The dynamics of a quantum particle bound by an accelerating delta-functional potential is investigated. Three cases are considered, using the reference frame moving along with the {\\delta}-function, in which the acceleration is converted into the additional linear potential. (i) A stationary regime, which corresponds to a resonance state, with a minimum degree of delocalization, supported by the accelerating potential trap. (ii) A pulling scenario: an initially bound particle follows the accelerating delta-functional trap, within a finite time. (iii) The pushing scenario: the particle, which was initially localized to the right of the repulsive delta-function, is shoved to the right by the accelerating potential. For the two latter scenarios, the life time of the trapped particle, and the largest velocity to which it can be accelerated while staying trapped, are found. Analytical approximations are developed for the cases of small and large accelerations in the pulling regime, and also for a small acceleration in the stationary situation, and in the regime of pushing. The same regimes may be realized by Airy-like planar optical beams guided by a narrow bending potential channel or crest. Physical estimates are given for an atom steered by a stylus of a scanning tunneling microscope (STM), and for the optical beam guided by a bending stripe.

Er'el Granot; Boris Malomed

2011-07-30

363

Bayes Analysis and Reliability Implications of Stress-Rupture Testing a Kevlar/Epoxy COPV using Temperature and Pressure Acceleration  

NASA Technical Reports Server (NTRS)

Composite Overwrapped Pressure Vessel (COPVs) that have survived a long service time under pressure generally must be recertified before service is extended. Sometimes lifetime testing is performed on an actual COPV in service in an effort to validate the reliability model that is the basis for certifying the continued flight worthiness of its sisters. Currently, testing of such a Kevlar49(registered TradeMark)/epoxy COPV is nearing completion. The present paper focuses on a Bayesian statistical approach to analyze the possible failure time results of this test and to assess the implications in choosing between possible model parameter values that in the past have had significant uncertainty. The key uncertain parameters in this case are the actual fiber stress ratio at operating pressure, and the Weibull shape parameter for lifetime; the former has been uncertain due to ambiguities in interpreting the original and a duplicate burst test. The latter has been uncertain due to major differences between COPVs in the data base and the actual COPVs in service. Any information obtained that clarifies and eliminates uncertainty in these parameters will have a major effect on the predicted reliability of the service COPVs going forward. The key result is that the longer the vessel survives, the more likely the more optimistic stress ratio is correct. At the time of writing, the resulting effect on predicted future reliability is dramatic, increasing it by about one nine , that is, reducing the probability of failure by an order of magnitude. However, testing one vessel does not change the uncertainty on the Weibull shape parameter for lifetime since testing several would be necessary.

Phoenix, S. Leigh; Kezirian, Michael T.; Murthy, Pappu L. N.

2009-01-01

364

Multilayer insulation for the interconnect region in the Accelerator System String Test: A practical engineering approach for a new scheme of design and installation bridges  

SciTech Connect

In order to minimize the heat leak in the Accelerator System String Test (ASST) inter-connect region, shield bridges and multilayer insulation (MLI) are provided. A sliding joint between shield bridges on adjacent magnets accommodates the contraction that occurs during cooldown. In the original design of the MLI bridges, thermal contraction was provided for by compressing the MLI. During assembly of the interconnect region, it was realized that there was not enough room for the required compression. This resulted in a redesign of the MLI bridges. The new scheme involves splitting and overlapping the MLI. This scheme has worked very well in subsequent assembly of the interconnect region. In this paper, we are going to present the new design scheme. We will also compare this design with the original design and present its advantages.

Baritchi, D.; Jalloh, A.

1993-04-01

365

Development of bellows and gate valves with a comb-type rf shield for high-current accelerators: Four-year beam test at KEK B-Factory  

SciTech Connect

Since a comb-type rf shield was proposed in 2003 as a rf shield for future high-intensity accelerators, various types of bellow chambers and gate valves with this rf shield have been installed in the KEK B-Factory rings in series and tested with beams. Through beam tests to check the performance, a structural simplification has been tried in parallel. The temperatures of the bellow corrugations decreased by a factor of 3-6 compared to those with a conventional finger-type rf shield in most cases. The temperatures of the body of the gate valves also decreased by a factor of 2-5. These results demonstrated the availability of the comb-type rf shield. Although a discharge was observed in one simplified model, the latest model has shown no problem up to a stored beam current of 1.8 A (1.3 mA/bunch, 6 mm bunch length). Experiences with the comb-type rf shield in these four-year beam tests are reviewed here.

Suetsugu, Yusuke; Kanazawa, Ken-ichi; Shibata, Kyo; Shirai, Mitsuru; Bondar, Aleksander E.; Kuzminykh, Victor S.; Gorbovsky, Aleksander I.; Sonderegger, Kurt; Morii, Minoru; Kawada, Kakuyu [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); Budker Institute of Nuclear Physics (BINP), Novosibirsk 630090 (Russian Federation); VAT Vakuumventile AG, Haag CH-9469 (Switzerland); VAT SKK Vacuum Ltd., Yokohama, Kanagawa 240-0023 (Japan)

2007-04-15

366

Present Status And First Results of the Final Focus Beam Line at the KEK Accelerator Test Facility  

SciTech Connect

ATF2 is a final-focus test beam line which aims to focus the low emittance beam from the ATF damping ring to a vertical size of about 37 nm and to demonstrate nanometer level beam stability. Several advanced beam diagnostics and feedback tools are used. In December 2008, construction and installation were completed and beam commissioning started, supported by an international team of Asian, European, and U.S. scientists. The present status and first results are described.

Bambade, P.; /Orsay /KEK, Tsukuba; Alabau Pons, M.; /Valencia U., IFIC; Amann, J.; /SLAC; Angal-Kalinin, D.; /Daresbury; Apsimon, R.; /Oxford U., JAI; Araki, S.; Aryshev, A.; /KEK, Tsukuba; Bai, S.; /Beijing, Inst. High Energy Phys.; Bellomo, P.; /SLAC; Bett, D.; /Oxford U., JAI; Blair, G.; /Royal Holloway, U. of London; Bolzon, B.; /Savoie U.; Boogert, S.; Boorman, G.; /Royal Holloway, U. of London; Burrows, P.N.; Christian, G.; Coe, P.; Constance, B.; /Oxford U., JAI; Delahaye, Jean-Pierre; /CERN; Deacon, L.; /Royal Holloway, U. of London; Elsen, E.; /DESY /Valencia U., IFIC /KEK, Tsukuba /Beijing, Inst. High Energy Phys. /Savoie U. /Fermilab /Ecole Polytechnique /KEK, Tsukuba /Kyungpook Natl. U. /KEK, Tsukuba /Pohang Accelerator Lab. /Kyoto U., Inst. Chem. Res. /Savoie U. /Daresbury /Tokyo U. /Royal Holloway, U. of London /Kyungpook Natl. U. /Pohang Accelerator Lab. /Tokyo U. /KEK, Tsukuba /SLAC /University Coll. London /KEK, Tsukuba /SLAC /Royal Holloway, U. of London /KEK, Tsukuba /Tokyo U. /SLAC /Tohoku U. /KEK, Tsukuba /Tokyo U. /Pohang Accelerator Lab. /Brookhaven /SLAC /Oxford U., JAI /SLAC /Orsay /KEK, Tsukuba /Oxford U., JAI /Orsay /Fermilab /Tohoku U. /Manchester U. /CERN /SLAC /Tokyo U. /KEK, Tsukuba /Oxford U., JAI /Hiroshima U. /KEK, Tsukuba /CERN /KEK, Tsukuba /Oxford U., JAI /Ecole Polytechnique /SLAC /Oxford U., JAI /Fermilab /SLAC /Liverpool U. /SLAC /Tokyo U. /SLAC /Tokyo U. /KEK, Tsukuba /SLAC /CERN

2011-11-11

367

Diagnostics for induction accelerators  

SciTech Connect

The induction accelerator was conceived by N. C. Christofilos and first realized as the Astron accelerator that operated at LLNL from the early 1960`s to the end of 1975. This accelerator generated electron beams at energies near 6 MeV with typical currents of 600 Amperes in 400 ns pulses. The Advanced Test Accelerator (ATA) built at Livermore`s Site 300 produced 10,000 Ampere beams with pulse widths of 70 ns at energies approaching 50 MeV. Several other electron and ion induction accelerators have been fabricated at LLNL and LBNL. This paper reviews the principal diagnostics developed through efforts by scientists at both laboratories for measuring the current, position, energy, and emittance of beams generated by these high current, short pulse accelerators. Many of these diagnostics are closely related to those developed for other accelerators. However, the very fast and intense current pulses often require special diagnostic techniques and considerations. The physics and design of the more unique diagnostics developed for electron induction accelerators are presented and discussed in detail.

Fessenden, T.J.

1996-04-01

368

Accelerating Ground-Test Cycle Time: The Six-Minute Model Change and Other Visions for the 21st Century  

NASA Technical Reports Server (NTRS)

The advantage of managing organizations to minimize product development cycle time has been well established. This paper provides an overview of the wind tunnel testing cycle time reduction activities at Langley Research Center (LaRC) and gives the status of several improvements in the wind tunnel productivity and cost reductions that have resulted from these activities. Processes have been examined and optimized. Metric data from monitoring processes provides guidance for investments in advanced technologies. The most promising technologies under implementation today include the use of formally designed experiments, a diverse array of quick disconnect technology and the judicious use of advanced electronic and information technologies.

Kegelman, Jerome T.

1998-01-01

369

Accelerated Wafer-Level Integrated Circuit Reliability Testing for Electromigration in Metal Interconnects with Enhanced Thermal Modeling, Structure Design, Control of Stress, and Experimental Measurements.  

NASA Astrophysics Data System (ADS)

Wafer-level electromigration tests have been developed recently to fulfill the need for rapid testing in integrated circuit production facilities. We have developed an improved thermal model-TEARS (Thermal Energy Accounts for the Resistance of the System) that supports these tests. Our model is enhanced by treatments for determination of the thermal conductivity of metal, K_{m}, heat sinking effects of the voltage probes and current lead terminations, and thermoelectric power. Our TEARS analysis of multi-element SWEAT (Standard Wafer-level Electromigration Acceleration Test) structures yields design criteria for the length of current injection leads and choice of voltage probe locations to isolate test units from the heat sinking effect of current lead terminations. This also provides greater insight into the current for thermal runaway. From our TEARS model and Black's equation for lifetime prediction, we have developed an algorithm for a fast and accurate control of stress in SWEAT tests. We have developed a lookup table approach for precise electromigration characterizations without complicated calculations. It decides the peak temperature in the metal, T_ {max}, and the thermal conductivity of the insulator, K_{i}, from an experimental resistance measurement at a given current. We introduce a characteristic temperature, T _{EO}, which is much simpler to use than conventional temperature coefficient of the electrical resistivity of metal for calibration and transfer of calibration data of metallic films as their own temperature sensors. The use of T_{EO} also allows us to establish system specifications for a desirable accuracy in temperature measurement. Our experimental results are the first to show the effects of series elemental SWEAT units on the system failure distribution, spatial failure distribution in SWEAT structures, and bimodal distributions for straight-line structures. The adaptive approach of our TEARS based SWEAT test decides the value of Black's parameter A^{*} for optimizing the test duration. The relative values of A^ {*} can be interpreted as a figure of merit for otherwise identical structures. (Copies available exclusively from Micrographics Department, Doheny Library, USC, Los Angeles, CA 90089-0182.).

Shih, Chih-Ching

370

Title LIFE-TIME POWER EFFICIENCY IMPROVEMENT OF DISTRIBUTED PHOTO- VOLTAIC DC-DC INVERTERS IN SOLAR PANEL SYSTEMS  

E-print Network

Photo-voltaic solar panels provide a very attractive solution for future clean energy provision on site. Today's panels provide a relatively high efficiency under optimal conditions and when just fabricated. However, when external temperature, radiation angle, and radiation concentration conditions are varying, also the power efficiency fluctuates quite heavily. This is partly also true for the DC-DC inverter subsystem, especially when seen in the interaction with the solar modules. The range of these effects heavily depends on the context in which these panels are used and on the type of circuits and technology used. In this thesis, we want to model the DC-DC inverter circuits, especially for a distributed case where they are partly integrated into the solar modules. Also the control of these inverters will be investigated. We want to explore the effects of the different parameters and identify which of those effects can be effectively mitigated or counter acted. This will contribute heavily to the efficiency over the entire life time of the future solar system, with minimal hardware cost increase. That will result in a large practical impact of the work in this thesis. Keywords: photovoltaic DC-DC inverter, power-efficiency analysis, efficiency improving control, comparison of techniques

Contact Person Reinhart; Promotor Prof; Francky Catthoor; Prof Johan Driesen (imec-leuven; K. U. Leuven; Prof Francky Catthoor; Prof Johan Driesen

371

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

NASA Astrophysics Data System (ADS)

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 following conclusions: the neutralized depth of the concrete specimens of all experiments can be described as a power function of exposure duration, CaO loss and the reduction rate of strength increased with H + and decreased with SO 42- concentration in simulated acid rain. The original mineral compounds such as [Na K]AlSi 3O 8 and [Ca Na][SiAl] 4O 8 in the hardened cement paste are converted to CaSO 4·2H 2O, CaAl 2Si 2O 8 and Ca 3Al 6O 12·CaSO 4. And these are larger in volume so that the reaction with SO 42- ions result in volume expansion and strength decrease. The reduction rate of strength has a binary linear relation to the CaO loss rate and the ratio of SO 3 content to CaO content in the hardened cement paste. So the deterioration of acid rain on the concrete specimen is caused by both H + dissolution and SO 42- expansion.

Xie, Shaodong; Qi, Li; Zhou, Ding

372

High-Temperature Oxidation of Cr-Mo Steels and Its Relevance to Accelerated Rupture Testing and Life Assessment of In-Service Components  

NASA Astrophysics Data System (ADS)

Use of accelerated creep rupture testing to assess the remaining life of components operating at elevated temperatures, such as pipes and tubes, is a common practice. At high temperatures, oxide growth can affect the creep results by diameter reduction and thus can increase the stress. However, the nature of oxide layer and hence oxidation behavior can be affected by minor changes in alloying composition of steels. This article presents the study of oxide-scale growth and specimen diameter reduction kinetics during oxidation of two Cr-Mo steels used in the manufacture of boiler tubing. Oxidation tests were carried out on 1.25Cr-0.5Mo and 2.25Cr-1Mo steels at 600 °C and 700 °C for times up to 1000 hours, using cylindrical specimens (similar to those used for creep testing). At 600 °C, the oxidation resistance of 2.25Cr-1Mo steel was superior to 1.25Cr-0.5Mo steel. However, the oxidation resistance of the two steels at 700 °C was similar in spite of the difference in their Cr contents. Multilayer oxide scales of oxides with various compositions were observed to have formed over the two steels. The similarity in oxidation kinetics of the two steels at 700 °C (in spite of differences in Cr contents) is ascribed to their Si contents and the predominant role of Si in oxidation at this temperature. The article also discusses implications of the variation in the oxidation kinetics to the stress enhancement in creep specimens due to scaling losses, and possible inaccuracies in creep data, as a result of minor variations in alloying composition.

Singh Raman, R. K.; Al-Mazrouee, A.

2007-08-01

373

TEACH ENGLISH IN SOUTH KOREA Are you ready for the adventure of a life time? Imagine paying off your student loans!!  

E-print Network

TEACH ENGLISH IN SOUTH KOREA Are you ready for the adventure of a life time? Imagine paying off schools in Korea. We have positions available all over Korea! Most graduates are saving over $1000 a month, Australia, New Zealand, England, Ireland, South Africa) * No experience is required!!! Salary/Benefits * 2

374

Abstract--The duty cycle of a wireless sensor node is a key factor that determines the life time of a wireless sensor network.  

E-print Network

Abstract--The duty cycle of a wireless sensor node is a key factor that determines the life time of a wireless sensor network. In general, sensor medium access control protocols reduce the duty cycle consumption under low to extremely low duty cycle. It reduces the energy consumption for communication

Bahk, Saewoong

375

Testing  

MedlinePLUS

... curesma.org > learn about sma > causes & diagnoses > testing Testing An SMA diagnosis must be confirmed through genetic ... and must be identified through further testing. Prenatal Testing Prenatal testing is used to determine if a ...

376

Two-Sample Statistics for Testing the Equality of Survival Functions Against Improper Semi-parametric Accelerated Failure Time Alternatives: An Application to the Analysis of a Breast Cancer Clinical Trial  

PubMed Central

This paper presents two-sample statistics suited for testing equality of survival functions against improper semi-parametric accelerated failure time alternatives. These tests are designed for comparing either the short- or the long-term effect of a prognostic factor, or both. These statistics are obtained as partial likelihood score statistics from a time-dependent Cox model. As a consequence, the proposed tests can be very easily implemented using widely available software. A breast cancer clinical trial is presented as an example to demonstrate the utility of the proposed tests. PMID:15293627

BROËT, PHILIPPE; TSODIKOV, ALEXANDER; DE RYCKE, YANN; MOREAU, THIERRY

2010-01-01

377

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

SciTech Connect

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.; Power, J.G.; Liu, W. [High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Gold, S.H. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kinkead, A.K. [LET Corporation, Washington, DC 20007 (United States)

2004-12-07

378

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

379

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

380

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

381

Angular Acceleration  

NSDL National Science Digital Library

The simulation of a rotating wheel below shows the relationship between angular position, angular velocity, and angular acceleration. Graphs of angular position and angular velocity as a function of time are shown.

Christian, Wolfgang; Belloni, Mario

2008-02-19

382

Recent Advances in Plasma Acceleration  

SciTech Connect

The costs and the time scales of colliders intended to reach the energy frontier are such that it is important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators a drive beam, either laser or particle, produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultra-high accelerating fields over a substantial length to achieve a significant energy gain. More than 42 GeV energy gain was achieved in an 85 cm long plasma wakefield accelerator driven by a 42 GeV electron drive beam in the Final Focus Test Beam (FFTB) Facility at SLAC. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx}52 GV/m. This effectively doubles their energy, producing the energy gain of the 3 km long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. Prospects for a drive-witness bunch configuration and high-gradient positron acceleration experiments planned for the SABER facility will be discussed.

Hogan, Mark

2007-03-19

383

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

384

Experimental test and life estimation of the OLED at normal working stress based on the luminance degradation model.  

PubMed

In order to accurately acquire the life time information for the organic light emitting diode (OLED), an experiment based on the normal stress life test was carried out to gain the data for the luminance degradation tests. The luminance degradation model of OLED was established based on the Weibull function and the least square method. Combined with luminance degradation data, Weibull parameters were estimated, the qualitative and the quantitative relationship between the initial luminance and the OLED life was obtained, and the life estimation of the product was achieved. Numerical results show that the test scheme is feasible, the luminance degradation model proves to be reliable for the OLED life estimation, and the fitting accuracy is very high by comparison with the test data fluctuation. Moreover, the real life time of the OLED is measured, which can verify the validity of the assumptions used in accelerated life test methods and provide manufacturers and customers with significant guidelines. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25044460

Zhang, J P; Wang, C; Chen, X; Cheng, G L; Qiu, Y J; Shen, M-H H

2014-07-14

385

Laser Accelerators  

NASA Astrophysics Data System (ADS)

It is now a fact that focusing an intense ultra short laser pulse onto a gas jet or thin targets, generates energetic collimated electrons or ions forming ultra short beams of energies > 100 MeV. The different mechanisms to explain such laser accelerated electrons or ions will be discussed. Data obtained by recent experiments will be presented. We report the experiment planed to study laser accelerated ions and/or particles using picosecond and femtosecond high energy laser pulses focused to achieve intensities >1018 watts/cm2. The design of the interaction chamber and the choice of targets as well as the ultra fast detection techniques will be speculated. This source of accelerated ions having unique properties is expected to become an interesting tool for many fields in physics, chemistry and biology. It can enable advances of devices to be used in medicine.

El Nadi, Lotfia M.; Mansour, Mohy S.; Abdellatif, Galila; Reda, Mohamad Atef

2010-04-01

386

Accelerator structure work for NLC  

SciTech Connect

The NLC design achieves high luminosity with multiple bunches in each RF pulse. Acceleration of a train of bunches without emittance growth requires control of long range dipole wakefields. SLAC is pursuing a structure design which suppresses the effect of wakefields by varying the physical dimensions of successive cells of the disk-loaded traveling wave structure in a manner which spreads the frequencies of the higher mode while retaining the synchronism between the electrons and the accelerating mode. The wakefields of structures incorporating higher mode detuning have been measured at the Accelerator Test Facility at Argonne. Mechanical design and brazing techniques which avoid getting brazing alloy into the interior of the accelerator are being studied. A test facility for high-power testing of these structures is complete and high power testing has begun.

Miller, R.H.; Adolphsen, C.; Bane, K.L.F.; Deruyter, H.; Farkas, Z.D.; Hoag, H.A.; Holtkamp, N.; Lavine, T.; Loew, G.A.; Nelson, E.M.; Palmer, R.B.; Paterson, J.M.; Ruth, R.D.; Thompson, K.A.; Vlieks, A.; Wang, J.W.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Gluckstern, R. [Maryland Univ., College Park, MD (United States); Ko, K.; Kroll, N. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)]|[California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

1992-07-01

387

Acceleration Studies  

NASA Technical Reports Server (NTRS)

Work to support the NASA MSFC Acceleration Characterization and Analysis Project (ACAP) was performed. Four tasks (analysis development, analysis research, analysis documentation, and acceleration analysis) were addressed by parallel projects. Work concentrated on preparation for and implementation of near real-time SAMS data analysis during the USMP-1 mission. User support documents and case specific software documentation and tutorials were developed. Information and results were presented to microgravity users. ACAP computer facilities need to be fully implemented and networked, data resources must be cataloged and accessible, future microgravity missions must be coordinated, and continued Orbiter characterization is necessary.

Rogers, Melissa J. B.

1993-01-01

388

Perturbations for transient acceleration  

SciTech Connect

According to the standard ?CDM model, the accelerated expansion of the Universe will go on forever. Motivated by recent observational results, we explore the possibility of a finite phase of acceleration which asymptotically approaches another period of decelerated expansion. Extending an earlier study on a corresponding homogeneous and isotropic dynamics, in which interactions between dark matter and dark energy are crucial, the present paper also investigates the dynamics of the matter perturbations both on the Newtonian and General Relativistic (GR) levels and quantifies the potential relevance of perturbations of the dark-energy component. In the background, the model is tested against the Supernova type Ia (SNIa) data of the Constitution set and on the perturbative level against growth rate data, among them those of the WiggleZ survey, and the data of the 2dFGRS project. Our results indicate that a transient phase of accelerated expansion is not excluded by current observations.

Vargas, Cristofher Zuñiga; Zimdahl, Winfried [Universidade Federal do Espírito Santo, Departamento de Física, Av. Fernando Ferrari, 514, Campus de Goiabeiras, CEP 29075-910, Vitória, Espírito Santo (Brazil); Hipólito-Ricaldi, Wiliam S., E-mail: win_unac@hotmail.com, E-mail: hipolito@ceunes.ufes.br, E-mail: winfried.zimdahl@pq.cnpq.br [Universidade Federal do Espírito Santo, Departamento de Ciências Naturais, Grupo de Física Teórica, Rodovia BR 101 Norte, km 60, Campus de São Mateus, CEP 29932-540, São Mateus, Espírito Santo (Brazil)

2012-04-01

389

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

390

Accelerated Achievement  

ERIC Educational Resources Information Center

This article focuses on the accelerated associate degree program at Ivy Tech Community College (Indiana) in which low-income students will receive an associate degree in one year. The three-year pilot program is funded by a $2.3 million grant from the Lumina Foundation for Education in Indianapolis and a $270,000 grant from the Indiana Commission…

Ford, William J.

2010-01-01

391

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

392

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

393

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

394

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

395

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

396

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

397

Development and test of a cryogenic trap system dedicated to confinement of radioactive volatile isotopes in SPIRAL2 post-accelerator  

Microsoft Academic Search

A cryogenic trap system called Cryotrap has been studied and developed in the framework of nuclear safety studies for SPIRAL2 accelerator. The main objective of Cryotrap is to confine and reduce strongly the migration of radioactive volatile isotopes in beam lines. These radioactive gases are produced after interaction between a deuteron beam and a fissile target. Mainly, Cryotrap is composed

M. Souli; P. Dolégiéviez; M. Fadil; P. Gallardo; R. Levallois; H. Munoz; M. Ozille; G. Rouillé; F. Galet

2011-01-01

398

GPU accelerated dislocation dynamics  

NASA Astrophysics Data System (ADS)

In this paper we analyze the computational bottlenecks in discrete dislocation dynamics modeling (associated with segment-segment interactions as well as the treatment of free surfaces), discuss the parallelization and optimization strategies, and demonstrate the effectiveness of Graphical Processing Unit (GPU) computation in accelerating dislocation dynamics simulations and expanding their scope. Individual algorithmic benchmark tests as well as an example large simulation of a thin film are presented.

Ferroni, Francesco; Tarleton, Edmund; Fitzgerald, Steven

2014-09-01

399

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

400

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

401

Thermal joining studies of CLIC accelerating structures and Establishment of a test bench and studies of thermomechanical behaviour of a CLIC two beam module  

E-print Network

The assembly procedure of the CLIC accelerating structures is constituted of several steps, involving ultra-precision machining, heating cycles at very high temperatures and many quality controls necessary to fulfil the very tight technical requirements. Diverse issues are related to the diffusion bonding process of CLIC accelerating structures; due to diffusion creep mechanisms occurring at high temperature and low stress, residual deformations might be present at the end of the joining process. A theoretical and experimental approach is presented here in order to understand this issue further and feedback on the design process. As a second issue tackled here, the final alignment of CLIC is also affected by the power dissipation occurring in the module during the normal operation modes and resulting in time-varying non-uniform thermal fields. The thermo-mechanical models of CLIC two-beam modules developed in the past are then useful to predict the structural deformations affecting the final alignment of the ...

Rossi, Fabrizio

2013-01-01

402

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

403

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

404

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.

405

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)  

USGS Publications Warehouse

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. ?? 2008 SETAC.

Fairchild, J.F.; Allert, A.; Sappington, L.S.; Nelson, K.J.; Valle, J.

2008-01-01

406

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

407

Simulating ion beam extraction from a single aperture triode acceleration column: A comparison of the beam transport codes IGUN and PBGUNS with test stand data  

SciTech Connect

Ion beam extraction from two different ion sources with single aperture triode extraction columns was simulated with the particle beam transport codes PBGUNS and IGUN. For each ion source, the simulation results are compared to experimental data generated on well-equipped test stands. Both codes reproduced the qualitative behavior of the extracted ion beams to incremental and scaled changes to the extraction electrode geometry observed on the test stands. Numerical values of optimum beam currents and beam emittance generated by the simulations also agree well with test stand data.

Patel, A.; Wills, J. S. C.; Diamond, W. T. [Chalk River Laboratories, AECL, Chalk River, Ontario K0 J 1J0 (Canada)

2008-04-15

408

Accelerated test methods for predicting the life of motor materials exposed to refrigerant/lubricant mixtures. Phase 1, Conceptual design: Final report  

SciTech Connect

The federally mandated phase-out of chlorofluorocarbon refrigerants requires screening tests for motor materials compatibility with alternative refrigerant/lubricant mixtures. In the current phase of the program, ARTI is supporting tests of promising candidate refrigeration/lubricant systems in key refrigeration component systems such as bearings and hermetic motor insulation systems to screen for more subtle detrimental effects and allow estimates of motor-compressor life. This report covers: mechanisms of failure of hermetic motor insulation, current methods for estimation of life of hermetic motors, and conceptual design of improved stator simulator device for testing of alternative refrigerant/lubricant mixtures.

Ellis, P.F. II; Ferguson, A.

1993-08-18

409

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

410

High-power electron beam tests of a liquid-lithium target and characterization study of (7)Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy.  

PubMed

A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (?=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors. PMID:24387907

Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Cohen, D; Eliyahu, I; Kijel, D; Mardor, I; Silverman, I

2014-06-01

411

Liquid Methane Conditioning Capabilities Developed at the NASA Glenn Research Center's Small Multi- Purpose Research Facility (SMiRF) for Accelerated Lunar Surface Storage Thermal Testing  

NASA Technical Reports Server (NTRS)

Glenn Research Center s Creek Road Cryogenic Complex, Small Multi-Purpose Research Facility (SMiRF) recently completed validation / checkout testing of a new liquid methane delivery system and liquid methane (LCH4) conditioning system. Facility checkout validation was conducted in preparation for a series of passive thermal control technology tests planned at SMiRF in FY10 using a flight-like propellant tank at simulated thermal environments from 140 to 350K. These tests will validate models and provide high quality data to support consideration of LCH4/LO2 propellant combination option for a lunar or planetary ascent stage.An infrastructure has been put in place which will support testing of large amounts of liquid methane at SMiRF. Extensive modifications were made to the test facility s existing liquid hydrogen system for compatibility with liquid methane. Also, a new liquid methane fluid conditioning system will enable liquid methane to be quickly densified (sub-cooled below normal boiling point) and to be quickly reheated to saturation conditions between 92 and 140 K. Fluid temperatures can be quickly adjusted to compress the overall test duration. A detailed trade study was conducted to determine an appropriate technique to liquid conditioning with regard to the SMiRF facility s existing infrastructure. In addition, a completely new roadable dewar has been procured for transportation and temporary storage of liquid methane. A new spherical, flight-representative tank has also been fabricated for integration into the vacuum chamber at SMiRF. The addition of this system to SMiRF marks the first time a large-scale liquid methane propellant test capability has been realized at Glenn.This work supports the Cryogenic Fluid Management Project being conducted under the auspices of the Exploration Technology Development Program, providing focused cryogenic fluid management technology efforts to support NASA s future robotic or human exploration missions.

Bamberger, Helmut H.; Robinson, R. Craig; Jurns, John M.; Grasl, Steven J.

2011-01-01

412

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

413

Covariant Uniform Acceleration  

E-print Network

We show that standard Relativistic Dynamics Equation F=dp/d\\tau is only partially covariant. To achieve full Lorentz covariance, we replace the four-force F by a rank 2 antisymmetric tensor acting on the four-velocity. By taking this tensor to be constant, we obtain a covariant definition of uniformly accelerated motion. We compute explicit solutions for uniformly accelerated motion which are divided into four types: null, linear, rotational, and general. For null acceleration, the worldline is cubic in the time. Linear acceleration covariantly extends 1D hyperbolic motion, while rotational acceleration covariantly extends pure rotational motion. We use Generalized Fermi-Walker transport to construct a uniformly accelerated family of inertial frames which are instantaneously comoving to a uniformly accelerated observer. We explain the connection between our approach and that of Mashhoon. We show that our solutions of uniformly accelerated motion have constant acceleration in the comoving frame. Assuming the Weak Hypothesis of Locality, we obtain local spacetime transformations from a uniformly accelerated frame K' to an inertial frame K. The spacetime transformations between two uniformly accelerated frames with the same acceleration are Lorentz. We compute the metric at an arbitrary point of a uniformly accelerated frame. We obtain velocity and acceleration transformations from a uniformly accelerated system K' to an inertial frame K. We derive the general formula for the time dilation between accelerated clocks. We obtain a formula for the angular velocity of a uniformly accelerated object. Every rest point of K' is uniformly accelerated, and its acceleration is a function of the observer's acceleration and its position. We obtain an interpretation of the Lorentz-Abraham-Dirac equation as an acceleration transformation from K' to K.

Yaakov Friedman; Tzvi Scarr

2011-05-03

414

I. ACCELERATION A. Introduction  

E-print Network

I. ACCELERATION A. Introduction Following cooling and initial bunch compression, the beams must be rapidly accelerated. The acceleration needed for a Higgs collider is probably the most conventional part undertaken. A sequence of linacs would work, but would be expensive. Some form of circulating acceleration

McDonald, Kirk

415

Acceleration of antimicrobial susceptibility testing of positive blood cultures by inoculation of Vitek 2 cards with briefly incubated solid medium cultures.  

PubMed

Briefly incubated agar cultures from positive blood cultures were used for antimicrobial susceptibility testing (AST) by Vitek 2. The cultivation time until inoculation was 3.8 h for Gram-positive cocci and 2.4 h for Gram-negative rods. The error rates were low, providing early and reliable AST without additional time or cost expenditure. PMID:25165084

Idelevich, Evgeny A; Schüle, Isabel; Grünastel, Barbara; Wüllenweber, Jörg; Peters, Georg; Becker, Karsten

2014-11-01

416

Acceleration without Horizons  

E-print Network

We derive the metric of an accelerating observer moving with non-constant proper acceleration in flat spacetime. With the exception of a limiting case representing a Rindler observer, there are no horizons. In our solution, observers can accelerate to any desired terminal speed $v_{\\infty} accelerating observer is completely determined by the distance of closest approach and terminal velocity or, equivalently, by an acceleration parameter and terminal velocity.

Alaric Doria; Gerardo Munoz

2015-02-18

417

Acceleration without Horizons  

E-print Network

We derive the metric of an accelerating observer moving with non-constant proper acceleration in flat spacetime. With the exception of a limiting case representing a Rindler observer, there are no horizons. In our solution, observers can accelerate to any desired terminal speed $v_{\\infty} accelerating observer is completely determined by the distance of closest approach and terminal velocity or, equivalently, by an acceleration parameter and terminal velocity.

Doria, Alaric

2015-01-01

418

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

419

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.

Brix, D.L.; Hawkins, S.A.; Poor, S.E.; Reginato, L.L.; Smith, M.W.

1985-10-01

420

Sources of the systematic errors in measurements of Po-214 decay half-life time variations at the Baksan deep underground experiments  

E-print Network

The design changes of the Baksan low-background TAU-1 and TAU-2 set-ups allowed to improve a sensitivity of Po-214 half-life (\\tau) measurements up to the 2.5 x 10^{-4} are described. Different possible sources of systematic errors influencing on the $\\tau$-value are studed. An annual variation of Po-214 half-life time measurements with an amplitude of A=(6.9 \\pm 3) x 10^{-4} and a phase of (\\phi=93 \\pm 10) days was found in a sequence of the week-collected \\tau-values obtained from the TAU-2 data sample with total duration of 480 days. 24 hours' variation of the \\tau-value measurements with an amplitude of A=(10.0 \\pm 2.6) x 10^{-4} and phase of (\\phi=1 \\pm 0.5) hours was found in a solar day 1 hour step \\tau-value sequence formed from the same data sample. It was found that the Po-214 half-life averaged at 480 days is equal to (163.45 \\pm 0.04) mks.

E. N. Alexeyev; Yu. M. Gavrilyuk; A. M. Gangapshev; V. V. Kazalov; V. V. Kuzminov; S. I. Panasenko; S. S. Ratkevich

2014-04-23

421

Plasma wakefield acceleration experiments at FACET  

NASA Astrophysics Data System (ADS)

FACET—Facilities for Accelerator science and Experimental Test beams at SLAC—will provide high-energy-density electron and positron beams with peak currents of roughly 20 kA that will be focused down to a 10 ?m×10 ?m transverse spot size at an energy of ~23 GeV. With FACET, the SLAC linac will support a unique program concentrating on second-generation research in plasma wakefield acceleration. Topics include high-gradient electron acceleration with a narrow energy spread and preserved emittance, beam loading and high-gradient positron acceleration. This paper describes the FACET facility, summarizes the state of the art for plasma wakefield accelerators and discusses the plasma wakefield accelerator program to be conducted at FACET over the next five years.

Hogan, M. J.; Raubenheimer, T. O.; Seryi, A.; Muggli, P.; Katsouleas, T.; Huang, C.; Lu, W.; An, W.; Marsh, K. A.; Mori, W. B.; Clayton, C. E.; Joshi, C.

2010-05-01

422

Accelerated development and flight evaluation of active controls concepts for subsonic transport aircraft. Volume 1: Load alleviation/extended span development and flight tests  

NASA Technical Reports Server (NTRS)

Active wing load alleviation to extend the wing span by 5.8 percent, giving a 3 percent reduction in cruise drag is covered. The active wing load alleviation used symmetric motions of the outboard ailerons for maneuver load control (MLC) and elastic mode suppression (EMS), and stabilizer motions for gust load alleviation (GLA). Slow maneuvers verified the MLC, and open and closed-loop flight frequency response tests verified the aircraft dynamic response to symmetric aileron and stabilizer drives as well as the active system performance. Flight tests in turbulence verified the effectiveness of the active controls in reducing gust-induced wing loads. It is concluded that active wing load alleviation/extended span is proven in the L-1011 and is ready for application to airline service; it is a very practical way to obtain the increased efficiency of a higher aspect ratio wing with minimum structural impact.

Johnston, J. F.

1979-01-01

423

Acceleration versus heart rate for estimating energy expenditure and speed during locomotion in animals: Tests with an easy model species, Homo sapiens  

Microsoft Academic Search

An important element in the measurement of energy budgets of free-living animals is the estimation of energy costs during locomotion. Using humans as a particularly tractable model species, we conducted treadmill experiments to test the validity of tri-axial accelerometry loggers, designed for use with animals in the field, to estimate rate of oxygen consumption (V?O2: an indirect measure of metabolic

Lewis G. Halsey; Emily L. C. Shepard; Carl J. Hulston; Michelle C. Venables; Craig R. White; Asker E. Jeukendrup; Rory P. Wilson

2008-01-01

424

Linear Bayesian inference for accelerated Weibull model.  

PubMed

In this paper, we present a Bayesian approach for inference from accelerated life tests when the underlying life model is Weibull. Our approach is based on the General Linear Models framework of West, Harrison and Migon (1985). We discuss inference for the model and show that computable results can be obtained using linear Bayesian methods. We illustrate the usefulness of our approach by applying it to some actual data from accelerated life tests. PMID:9384626

Mazzuchi, T A; Soyer, R; Vopatek, A L

1997-01-01

425

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

426

Acceleration of colliding shells around a black hole: Validity of the test particle approximation in the Banados-Silk-West process  

SciTech Connect

Recently, Banados, Silk and West (BSW) showed that the total energy of two colliding test particles has no upper limit in their center of mass frame in the neighborhood of an extreme Kerr black hole, even if these particles were at rest at infinity in the infinite past. We call this mechanism the BSW mechanism or BSW process. The large energy of such particles would generate strong gravity, although this has not been taken into account in the BSW analysis. A similar mechanism is seen in the collision of two spherical test shells in the neighborhood of an extreme Reissner-Nordstroem black hole. In this paper, in order to draw some implications concerning the effects of gravity generated by colliding particles in the BSW process, we study a collision of two spherical dust shells, since their gravity can be exactly treated. We show that the energy of two colliding shells in the center of mass frame observable from infinity has an upper limit due to their own gravity. Our result suggests that an upper limit also exists for the total energy of colliding particles in the center of mass frame in the observable domain in the BSW process due the gravity of the particles.

Kimura, Masashi; Nakao, Ken-ichi [Department of Mathematics and Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585 (Japan); Tagoshi, Hideyuki [Department of Earth and Space Science, Graduate School of Science, Osaka University, Osaka 560-0043 (Japan)

2011-02-15

427

Acceleration of colliding shells around a black hole: Validity of the test particle approximation in the Banados-Silk-West process  

E-print Network

Recently, Banados, Silk and West (BSW) showed that the total energy of two colliding test particles has no upper limit in their center of mass frame in the neighborhood of an extreme Kerr black hole, even if these particles were at rest at infinity in the infinite past. We call this mechanism the BSW mechanism or BSW process. The large energy of such particles would generate strong gravity, although this has not been taken into account in the BSW analysis. A similar mechanism is seen in the collision of two spherical test shells in the neighborhood of an extreme Reissner-Nordstr\\"om black hole. In this paper, in order to draw some implications concerning the effects of gravity generated by colliding particles in the BSW process, we study a collision of two spherical dust shells, since their gravity can be exactly treated. We show that the energy of two colliding shells in the center of mass frame observable from infinity has an upper limit due to their own gravity. Our result suggests that an upper limit also exists for the total energy of colliding particles in the center of mass frame in the observable domain in the BSW process due the gravity of the particles.

Masashi Kimura; Ken-ichi Nakao; Hideyuki Tagoshi

2010-10-26

428

CENTRIPETAL ACCELERATION AND CENTRIFUGAL FORCE IN GENERAL RELATIVITY  

E-print Network

1 CENTRIPETAL ACCELERATION AND CENTRIFUGAL FORCE IN GENERAL RELATIVITY D. BINI Istituto per mechanics non-inertial observers studying accelerated test particle motion experience a centripetal acceleration which, once interpreted as a centrifugal force acting on the particle, allows writing the particle

Jantzen, Robert T.

429

Gait assessment for elderly using a portable acceleration monitoring device  

Microsoft Academic Search

This study developed a portable acceleration monitoring device for gait assessments, and applied it to assess the gait of elderly. In a gait assessment experiment, 21 elderly subjects, wearing the portable acceleration monitoring device on their lower backs, walked on a test track. Four sets of evaluation indexes (physical activity, stability, symmetry, average speed) were derived from the acceleration data

Naruhiro SHIOZAWA; Shima OKADA; Masaaki MAKIKAWA

2010-01-01

430

The Use of a Vehicle Acceleration Exposure Limit Model and a Finite Element Crash Test Dummy Model to Evaluate the Risk of Injuries During Orion Crew Module Landings  

NASA Technical Reports Server (NTRS)

A review of astronaut whole body impact tolerance is discussed for land or water landings of the next generation manned space capsule named Orion. LS-DYNA simulations of Orion capsule landings are performed to produce a low, moderate, and high probability of injury. The paper evaluates finite element (FE) seat and occupant simulations for assessing injury risk for the Orion crew and compares these simulations to whole body injury models commonly referred to as the Brinkley criteria. The FE seat and crash dummy models allow for varying the occupant restraint systems, cushion materials, side constraints, flailing of limbs, and detailed seat/occupant interactions to minimize landing injuries to the crew. The FE crash test dummies used in conjunction with the Brinkley criteria provides a useful set of tools for predicting potential crew injuries during vehicle landings.

Lawrence, Charles; Fasanella, Edwin L.; Tabiei, Ala; Brinkley, James W.; Shemwell, David M.

2008-01-01

431

Chronic Low Back Pain in Young Korean Urban Males: The Life-Time Prevalence and Its Impact on Health Related Quality of Life  

PubMed Central

Objective We assessed the life-time prevalence (LTP) of chronic low back pain (LBP) in young Korean males. We also evaluated the relationship between lumbar spinal lesions and their health related quality-of-life (HRQOL). Methods A cross-sectional, self-reported survey was conducted in Korean males (aged 19-year-old) who underwent physical examinations for the conscript. We examined 3331 examinees in November 2014. We included 2411 subjects, who accepted to participate this study without any comorbidities. We interviewed using simple binary questions for their LBP experience and chronicity. HRQOL was assessed by Short-Form Health-Survey-36 (SF-36) in chronic LBP and healthy control groups. Radiological assessment was performed in chronic LBP group to determine whether there were any pathological causes of their symptoms. Results The LTP of chronic LBP was 13.4%. Most (71.7%) of them didn't have any lumbar spinal lesions (i.e., non-specific chronic LBP). The SF-36 subscale and summary scores were significantly lower in subjects with chronic LBP. Between specific and non-specific chronic LBP group, all physical and mental subscale scores were significantly lower in specific chronic LBP group, except mental health (MH) subscale score. In MH subscale and mental component summary score, statistical significant differences didn't appear between two groups (p=0.154, 0.126). Conclusion In Korean males 19 years of age, the LTP of chronic LBP was 13.4%, and more than two-thirds were non-specific chronic LBP. Chronic LBP had a significant impact on HRQOL. The presence of lumbar spinal pathoanatomical lesions affected mainly on the physical aspect of HRQOL. It influenced little on the mental health.

Shim, Jae-Hyun; Yoon, Sang-Young; Lee, Chang-Hoon; Doh, Jae-Won; Bae, Hack-Gun

2014-01-01

432

Improved plasma accelerator  

NASA Technical Reports Server (NTRS)

Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

Cheng, D. Y.

1971-01-01

433

Diffusive Acceleration of Ions at Interplanetary Shocks  

E-print Network

Heliospheric shocks are excellent systems for testing theories of particle acceleration in their environs. These generally fall into two classes: (1) interplanetary shocks that are linear in their ion acceleration characteristics, with the non-thermal ions serving as test particles, and (2) non-linear systems such as the Earth's bow shock and the solar wind termination shock, where the accelerated ions strongly influence the magnetohydrodynamic structure of the shock. This paper explores the modelling of diffusive acceleration at a particular interplanetary shock, with an emphasis on explaining in situ measurements of ion distribution functions. The observational data for this event was acquired on day 292 of 1991 by the Ulysses mission. The modeling is performed using a well-known kinetic Monte Carlo simulation, which has yielded good agreement with observations at several heliospheric shocks, as have other theoretical techniques, namely hybrid plasma simulations, and numerical solution of the diffusion-convection equation. In this theory/data comparison, it is demonstrated that diffusive acceleration theory can, to first order, successfully account for both the proton distribution data near the shock, and the observation of energetic protons farther upstream of this interplanetary shock than lower energy pick-up protons, using a single turbulence parameter. The principal conclusion is that diffusive acceleration of inflowing upstream ions can model this pick-up ion-rich event without the invoking any seed pre-acceleration mechanism, though this investigation does not rule out the action of such pre-acceleration.

Matthew G. Baring; Errol J. Summerlin

2005-06-08

434

A Solid state accelerator  

SciTech Connect

We present a solid state accelerator concept utilizing particle acceleration along crystal channels by longitudinal electron plasma waves in a metal. Acceleration gradients of order 100 GV/cm are theoretically possible, but channeling radiation limits the maximum attainable energy to 10/sup 5/ TeV for protons. Beam dechanneling due to multiple scattering is substantially reduced by the high acceleration gradient. Plasma wave dissipation and generation in metals are also discussed.

Chen, P.; Noble, R.J.

1986-11-06

435

A study of kinetic behaviours of the effective centralite/stabilizer consumption reaction of propellants using a multi-temperature artificial accelerated ageing test.  

PubMed

Using a multi-temperature artificial ageing testing apparatus and a standard method of determining the effective centralite/stabilizer content, the effective centralite/stabilizer content for varying time period in propellants heated at 95 degrees C, 90 degrees C, 85 degrees C, 75 degrees C and 65 degrees C was measured. Bethelot's equation and Semenov's equation in the temperature range of 65-95 degrees C for 81 propellants were established. The safe storage life at 30 degrees C, kinetic parameters [the apparent activation energy (E) and the pre-exponential constant (A)] and isolife temperatures obtained from the established equations and the activation energy (E(alpha=0.5)) obtained by integral isoconversional non-linear method for 81 propellants: single-base gun propellants (DF-01-DF-16), double-base gun propellants (SF-01-SF-13), tri-base gun propellants (SG-01-SG-02), nitramine gun propellants (GSF-01-GSF-18), double-base propellants (ST-01-ST-13), and composite modified double-base propellants (GST-01-GST-19), were given. Information was obtained on the effective centralite/stabilizer consumption reaction and the kinetic compensation effect. PMID:17161528

Fengqi, Zhao; Shuyun, Heng; Rongzu, Hu; Hongxu, Gao; Fang, Han

2007-06-25

436

Acceleration-Induced Nonlocality  

E-print Network

The standard relativistic theory of accelerated reference frames in Minkowski spacetime is described. The measurements of accelerated observers are considered and the limitations of the standard theory, based on the hypothesis of locality, are pointed out. The physical principles of the nonlocal theory of accelerated observers are presented. The implications of the nonlocal theory are briefly discussed.

Bahram Mashhoon

2003-01-17

437

Acceleration: It's Elementary  

ERIC Educational Resources Information Center

Acceleration is one tool for providing high-ability students the opportunity to learn something new every day. Some people talk about acceleration as taking a student out of step. In actuality, what one is doing is putting a student in step with the right curriculum. Whole-grade acceleration, also called grade-skipping, usually happens between…

Willis, Mariam

2012-01-01

438

Direction of Acceleration  

NSDL National Science Digital Library

In this short lab, students observe the movement of an air bubble in a small level, attached to a toy truck, as it is moved from a stop, to a steady speed and back to a stop. This gives a visual to the concepts positive acceleration, zero acceleration and negative acceleration.

Mary Spaulding, Clearbrook-Gonvick Public School, Clearbrook Minnesota, based on an original activity from Physics Principles and Problems (1995) page 75.

439

Force, mass and acceleration  

Microsoft Academic Search

Force, mass and acceleration are everyday words but often used inaccurately. Force is a physical influence, which when applied to an object causes it to accelerate in the direction from which it was applied. Mass is the amount of matter in an object and is expressed in kilograms. Acceleration is the rate of change of velocity of an object in

Phil Dalrymple; Richard Griffiths

2005-01-01

440

Angular Acceleration without Torque?  

ERIC Educational Resources Information Center

Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

Kaufman, Richard D.

2012-01-01