Preloading To Accelerate Slow-Crack-Growth Testing

Science.gov (United States)

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

2004-01-01

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.

Color Shift Modeling of Light-Emitting Diode Lamps in Step-Loaded Stress Testing

NARCIS (Netherlands)

Cai, Miao; Yang, Daoguo; Huang, J.; Zhang, Maofen; Chen, Xianping; Liang, Caihang; Koh, S.W.; Zhang, G.Q.

2017-01-01

The color coordinate shift of light-emitting diode (LED) lamps is investigated by running three stress-loaded testing methods, namely step-up stress accelerated degradation testing, step-down stress accelerated degradation testing, and constant stress accelerated degradation testing. A power

Developing MESA : an accelerated reliability test

NARCIS (Netherlands)

Baskoro, G.; Rouvroye, J.L.; Bacher, W.; Brombacher, A.C.

2003-01-01

This paper describes the on-going research on an accelerated reliability test strategy called MESA (Multiple Environment Stress Analysis) intended to find in a fast and efficient manner (potential) reliability problems during the design phase of high volume consumer products. This test has shown

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

Science.gov (United States)

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

2014-11-01

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

Quantitative accelerated degradation testing: Practical approaches

International Nuclear Information System (INIS)

Mohammadian, S. Hossein; Ait-Kadi, Daoud; Routhier, Francois

2010-01-01

The concept of accelerated testing by tracking degradation of samples over test time needs to be developed for reliability estimation. This paper aims at proposing practical approaches to conduct accelerated degradation testing on new and available used samples. For this purpose, product failure is related to a suitable physical property. Then, its failure time is defined as the expected time in which its property reaches the critical level. Degradation model of field samples returned from service due to a degrading failure mode has been estimated based on the least square method, and available gap between manufacturer criterion and user's claim (to report a failure) has also been discussed. For a product under some stresses, a general formula has been proposed by the superposition principle in order to estimate its degradation for independent and dependent failure modes. If used samples are available, and acceleration factor of the related test is unknown, partial aging method has been presented to considerably shorten the test time.

Testing the accelerating moment release (AMR) hypothesis in areas of high stress

Science.gov (United States)

Guilhem, Aurélie; Bürgmann, Roland; Freed, Andrew M.; Ali, Syed Tabrez

2013-11-01

Several retrospective analyses have proposed that significant increases in moment release occurred prior to many large earthquakes of recent times. However, the finding of accelerating moment release (AMR) strongly depends on the choice of three parameters: (1) magnitude range, (2) area being considered surrounding the events and (3) the time period prior to the large earthquakes. Consequently, the AMR analysis has been criticized as being a posteriori data-fitting exercise with no new predictive power. As AMR has been hypothesized to relate to changes in the state of stress around the eventual epicentre, we compare here AMR results to models of stress accumulation in California. Instead of assuming a complete stress drop on all surrounding fault segments implied by a back-slip stress lobe method, we consider that stress evolves dynamically, punctuated by the occurrence of earthquakes, and governed by the elastic and viscous properties of the lithosphere. We study the seismicity of southern California and extract events for AMR calculations following the systematic approach employed in previous studies. We present several sensitivity tests of the method, as well as grid-search analyses over the region between 1955 and 2005 using fixed magnitude range, radius of the search area and period of time. The results are compared to the occurrence of large events and to maps of Coulomb stress changes. The Coulomb stress maps are compiled using the coseismic stress from all M > 7.0 earthquakes since 1812, their subsequent post-seismic relaxation, and the interseismic strain accumulation. We find no convincing correlation of seismicity rate changes in recent decades with areas of high stress that would support the AMR hypothesis. Furthermore, this indicates limited utility for practical earthquake hazard analysis in southern California, and possibly other regions.

Color Shift Modeling of Light-Emitting Diode Lamps in Step-Loaded Stress Testing

OpenAIRE

Cai, Miao; Yang, Daoguo; Huang, J.; Zhang, Maofen; Chen, Xianping; Liang, Caihang; Koh, S.W.; Zhang, G.Q.

2017-01-01

The color coordinate shift of light-emitting diode (LED) lamps is investigated by running three stress-loaded testing methods, namely step-up stress accelerated degradation testing, step-down stress accelerated degradation testing, and constant stress accelerated degradation testing. A power model is proposed as the statistical model of the color shift (CS) process of LED products. Consequently, a CS mechanism constant is obtained for detecting the consistency of CS mechanisms among various s...

Accelerated Stress Testing of Multi-Source LED Products: Horticulture Lamps and Tunable-White Modules

Energy Technology Data Exchange (ETDEWEB)

Lynn Davis, Kelley Rountree, Karmann Mills

2018-03-30

This report discusses the use of accelerated stress testing (AST) to provide insights into the long-term behavior of commercial products utilizing different types of mid-power LEDs (MP-LEDs) integrated into the same LED module. Test results are presented from two commercial lamps intended for use in horticulture applications and one tunable-white LED module intended for use in educational and office lighting applications. Each of these products is designed to provide a custom spectrum for their targeted applications and each achieves this goal in different ways. Consequently, a comparison of the long-term stability of these devices will provide insights regarding approaches that could be used to possibly lengthen the lifetime of SSL products.

Reducing Variability in Stress Drop with Root-Mean Acceleration

Science.gov (United States)

Crempien, J.; Archuleta, R. J.

2012-12-01

Stress drop is a fundamental property of the earthquake source. For a given tectonic region stress drop is assumed to be constant allowing for the scaling of earthquake spectra. However, the variability of the stress drop, either for worldwide catalogs or regional catalogs, is quite large. The variability around the median value is on the order of 1.5 in log10 units. One question that continues to pervade the analysis of stress drop is whether this variability is an inherent characteristic of the Earth or is an artifact of the determination of stress drop via the use of the spectral analysis. It is simple to see that the stress drop determined by seismic moment times corner frequency cubed that errors in the corner frequency will strongly influence the variability in the stress drop. To avoid this strong dependence on corner frequency cubed, we have examined the determination of stress drop based on the approach proposed by Hanks (1979), namely using the root-mean-square acceleration. The stress drop determined using rms acceleration may be advantageous because the stress drop is only affected by the square root of the corner frequency. To test this approach we have determined stress drops for the 2000 Tottori earthquake and its aftershocks. We use both the classic method of fitting to a spectrum as well as using rms acceleration. For a preliminary analysis of eight aftershocks and the mainshock we find that the variability in stress drop is reduced by about a factor of two. This approach needs more careful analysis of more events, which will be shown at the meeting.

Failure-censored accelerated life test sampling plans for Weibull distribution under expected test time constraint

International Nuclear Information System (INIS)

Bai, D.S.; Chun, Y.R.; Kim, J.G.

1995-01-01

This paper considers the design of life-test sampling plans based on failure-censored accelerated life tests. The lifetime distribution of products is assumed to be Weibull with a scale parameter that is a log linear function of a (possibly transformed) stress. Two levels of stress higher than the use condition stress, high and low, are used. Sampling plans with equal expected test times at high and low test stresses which satisfy the producer's and consumer's risk requirements and minimize the asymptotic variance of the test statistic used to decide lot acceptability are obtained. The properties of the proposed life-test sampling plans are investigated

Life Prediction on a T700 Carbon Fiber Reinforced Cylinder with Limited Accelerated Life Testing Data

OpenAIRE

Ma Xiaobing; Zhang Yongbo

2015-01-01

An accelerated life testing investigation was conducted on a composite cylinder that consists of aluminum alloy and T700 carbon fiber. The ultimate failure stress predictions of cylinders were obtained by the mixing rule and verified by the blasting static pressure method. Based on the stress prediction of cylinder under working conditions, the constant stress accelerated life test of the cylinder was designed. However, the failure data cannot be sufficiently obtained by the accelerated life ...

Initial Results of Accelerated Stress Testing on Single-Channel and Multichannel Drivers: Solid-State Lighting Technology Area

Energy Technology Data Exchange (ETDEWEB)

None

2018-02-28

This report is the first in a series of studies on accelerated stress testing (AST) of drivers used for SSL luminaires, such as downlights, troffers, and streetlights. A representative group of two-stage commercial driver products was exposed to an AST environment consisting of 75°C and 75% relative humidity (7575). These drivers were a mix of single-channel drivers (i.e., a single output current for one LED primary) and multichannel drivers (i.e., separate output currents for multiple LED primaries). This AST environment was chosen because previous testing on downlights with integrated drivers demonstrated that 38% of the sample population failed in less than 2,500 hours of testing using this method. In addition to AST test results, the performance of an SSL downlight product incorporating an integrated, multichannel driver during extended room temperature operational life (RTOL) testing is also reported. A battery of measurements was used to evaluate these products during accelerated testing, including full electrical characterization (i.e., power consumption, PF, total harmonic distortion [THD], and inrush current) and photometric characterization of external LED loads attached to the drivers (i.e., flicker performance and lumen maintenance).

Life Prediction on a T700 Carbon Fiber Reinforced Cylinder with Limited Accelerated Life Testing Data

Directory of Open Access Journals (Sweden)

Ma Xiaobing

2015-01-01

Full Text Available An accelerated life testing investigation was conducted on a composite cylinder that consists of aluminum alloy and T700 carbon fiber. The ultimate failure stress predictions of cylinders were obtained by the mixing rule and verified by the blasting static pressure method. Based on the stress prediction of cylinder under working conditions, the constant stress accelerated life test of the cylinder was designed. However, the failure data cannot be sufficiently obtained by the accelerated life test due to the time limitation. Therefore, most of the data presented to be high censored in high stress level and zero-failure data in low stress level. When using the traditional method for rupture life prediction, the results showed to be of lower confidence. In this study, the consistency of failure mechanism for carbon fiber and cylinder was analyzed firstly. According to the analysis result, the statistical test information of carbon fiber could be utilized for the accelerated model constitution. Then, rupture life prediction method for cylinder was proposed based on the accelerated life test data and carbon fiber test data. In this way, the life prediction accuracy of cylinder could be improved obviously, and the results showed that the accuracy of this method increased by 35%.

A general Bayes weibull inference model for accelerated life testing

International Nuclear Information System (INIS)

Dorp, J. Rene van; Mazzuchi, Thomas A.

2005-01-01

This article presents the development of a general Bayes inference model for accelerated life testing. The failure times at a constant stress level are assumed to belong to a Weibull distribution, but the specification of strict adherence to a parametric time-transformation function is not required. Rather, prior information is used to indirectly define a multivariate prior distribution for the scale parameters at the various stress levels and the common shape parameter. Using the approach, Bayes point estimates as well as probability statements for use-stress (and accelerated) life parameters may be inferred from a host of testing scenarios. The inference procedure accommodates both the interval data sampling strategy and type I censored sampling strategy for the collection of ALT test data. The inference procedure uses the well-known MCMC (Markov Chain Monte Carlo) methods to derive posterior approximations. The approach is illustrated with an example

Safety of a rapid diagnostic protocol with accelerated stress testing.

Science.gov (United States)

Soremekun, Olan A; Hamedani, Azita; Shofer, Frances S; O'Conor, Katie J; Svenson, James; Hollander, Judd E

2014-02-01

Most patients at low to intermediate risk for an acute coronary syndrome (ACS) receive a 12- to 24-hour "rule out." Recently, trials have found that a coronary computed tomographic angiography-based strategy is more efficient. If stress testing were performed within the same time frame as coronary computed tomographic angiography, the 2 strategies would be more similar. We tested the hypothesis that stress testing can safely be performed within several hours of presentation. We performed a retrospective cohort study of patients presenting to a university hospital from January 1, 2009, to December 31, 2011, with potential ACS. Patients placed in a clinical pathway that performed stress testing after 2 negative troponin values 2 hours apart were included. We excluded patients with ST-elevation myocardial infarction or with an elevated initial troponin. The main outcome was safety of immediate stress testing defined as the absence of death or acute myocardial infarction (defined as elevated troponin within 24 hours after the test). A total of 856 patients who presented with potential ACS were enrolled in the clinical pathway and included in this study. Patients had a median age of 55.0 (interquartile range, 48-62) years. Chest pain was the chief concern in 86%, and pain was present on arrival in 73% of the patients. There were no complications observed during the stress test. There were 0 deaths (95% confidence interval, 0%-0.46%) and 4 acute myocardial infarctions within 24 hours (0.5%; 95% confidence interval, 0.14%-1.27%). The peak troponins were small (0.06, 0.07, 0.07, and 0.19 ng/mL). Patients who present to the ED with potential ACS can safely undergo a rapid diagnostic protocol with stress testing. © 2013.

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

Energy Technology Data Exchange (ETDEWEB)

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

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.

On the application of design of experiments to accelerated life testing

International Nuclear Information System (INIS)

Hakim-Mashhadi, M.

1992-01-01

Today, there is an increasing demand for improved quality and reliability due to increasing system complexity and increasing demands from customer. Continuous improvement of quality is not only a means of competition but also a matter of staying in the market. Accelerated life testing and statistical design of experiments are two needed methods for improvement of quality. The combined use of them is very advantageous and increases the test efficiency. Accelerated life testing is a quick way to provide information on the life distribution of materials and products. By subjecting the test unit to conditions more severe than those at normal usage, the test time can be highly reduced. Estimates of life at normal stress levels are obtained by extrapolating the available information through a reasonable acceleration model. Accelerated life testing has mostly been used to measure reliability but it is high time to use it for improvement of quality. Design of experiments serves to find out the effect of design parameters and other interesting factors on performance measure and its variability. The obtained information is essential for a continuous improvement of quality. As an illustration, two sets of experiment are designed and performed at highly increased stress levels. The results are analysed and discussed and a time saving alternative is proposed. The combination of experimental design and accelerated life testing is discussed and illustrated. The combined use of these methods can be argued for in two different cases. One is for an exploratory improvement investigation and the other is for verification of reliability. In either case, the combined use is advantageous and improves the testing efficiency. Some general conclusions are drawn to be used for planning and performance of statistically designed accelerated life testing experiments. (70 refs.) (au)

A Bayesian Optimal Design for Sequential Accelerated Degradation Testing

Directory of Open Access Journals (Sweden)

Xiaoyang Li

2017-07-01

Full Text Available When optimizing an accelerated degradation testing (ADT plan, the initial values of unknown model parameters must be pre-specified. However, it is usually difficult to obtain the exact values, since many uncertainties are embedded in these parameters. Bayesian ADT optimal design was presented to address this problem by using prior distributions to capture these uncertainties. Nevertheless, when the difference between a prior distribution and actual situation is large, the existing Bayesian optimal design might cause some over-testing or under-testing issues. For example, the implemented ADT following the optimal ADT plan consumes too much testing resources or few accelerated degradation data are obtained during the ADT. To overcome these obstacles, a Bayesian sequential step-down-stress ADT design is proposed in this article. During the sequential ADT, the test under the highest stress level is firstly conducted based on the initial prior information to quickly generate degradation data. Then, the data collected under higher stress levels are employed to construct the prior distributions for the test design under lower stress levels by using the Bayesian inference. In the process of optimization, the inverse Gaussian (IG process is assumed to describe the degradation paths, and the Bayesian D-optimality is selected as the optimal objective. A case study on an electrical connector’s ADT plan is provided to illustrate the application of the proposed Bayesian sequential ADT design method. Compared with the results from a typical static Bayesian ADT plan, the proposed design could guarantee more stable and precise estimations of different reliability measures.

An accelerated life test model for harmonic drives under a segmental stress history and its parameter optimization

Directory of Open Access Journals (Sweden)

Zhang Chao

2015-12-01

Full Text Available Harmonic drives have various distinctive advantages and are widely used in space drive mechanisms. Accelerated life test (ALT is commonly conducted to shorten test time and reduce associated costs. An appropriate ALT model is needed to predict the lifetime of harmonic drives with ALT data. However, harmonic drives which are used in space usually work under a segmental stress history, and traditional ALT models can hardly be used in this situation. This paper proposes a dedicated ALT model for harmonic drives applied in space systems. A comprehensive ALT model is established and genetic algorithm (GA is adopted to obtain optimal parameters in the model using the Manson fatigue damage rule to describe the fatigue failure process and a cumulative damage method to calculate and accumulate the damage caused by each segment in the stress history. An ALT of harmonic drives was carried out and experimental results show that this model is acceptable and effective.

Quantitative Accelerated Life Testing of MEMS Accelerometers.

Science.gov (United States)

Bâzu, Marius; Gălăţeanu, Lucian; Ilian, Virgil Emil; Loicq, Jerome; Habraken, Serge; Collette, Jean-Paul

2007-11-20

Quantitative Accelerated Life Testing (QALT) is a solution for assessing thereliability of Micro Electro Mechanical Systems (MEMS). A procedure for QALT is shownin this paper and an attempt to assess the reliability level for a batch of MEMSaccelerometers is reported. The testing plan is application-driven and contains combinedtests: thermal (high temperature) and mechanical stress. Two variants of mechanical stressare used: vibration (at a fixed frequency) and tilting. Original equipment for testing at tiltingand high temperature is used. Tilting is appropriate as application-driven stress, because thetilt movement is a natural environment for devices used for automotive and aerospaceapplications. Also, tilting is used by MEMS accelerometers for anti-theft systems. The testresults demonstrated the excellent reliability of the studied devices, the failure rate in the"worst case" being smaller than 10 -7 h -1 .

CERN Technical training 2008 - Learning for the LHC: Special Workshop demonstrating reliability with accelerated testing

CERN Multimedia

2008-01-01

Larry Edson’s workshop will show examples of quantitative reliability predictions based upon accelerated testing and demonstrates that reliability testing during the prototyping phase will help ascertain product shortcomings. When these weak points are addressed and the redesigned product is re-tested, the reliability of that product will become much higher. These methodologies successfully used in industry might be exceedingly useful also for component development in particle physics where reliability is of utmost importance. This training will provide participants with the skills necessary to demonstrate reliability requirements using accelerated testing methods. The workshop will focus on accelerated test design that employs increased stress levels. This approach has the advantage of reducing test time, sample size and test facility resources. The methodologies taught are applicable to all types of stresses, spanning the electro...

CERN Technical training 2008 - Learning for the LHC: Special Workshop demonstrating reliability with accelerated testing

CERN Multimedia

2008-01-01

Larry Edson’s workshop will show examples of quantitative reliability predictions based upon accelerated testing and demonstrate that reliability testing during the prototyping phase will help ascertain product shortcomings. When these weak points are addressed and the redesigned product is re-tested, the reliability of that product will become much higher. These methodologies successfully used in industry might be exceedingly useful also for component development in particle physics where reliability is of the utmost importance. This training will provide participants with the skills necessary to demonstrate reliability requirements using accelerated testing methods. The workshop will focus on accelerated test design that employs increased stress levels. This approach has the advantage of reducing test time, sample size and test facility resources. The methodologies taught are applicable to all types of stresses, spanning the elec...

CERN Technical training 2008 - Learning for the LHC: Special workshop demonstrating reliability with accelerated testing

CERN Multimedia

2008-01-01

Larry Edson’s workshop will show examples of quantitative reliability predictions based upon accelerated testing and demonstrate that reliability testing during the prototyping phase will help ascertain product shortcomings. When these weak points are addressed and the redesigned product is re-tested, the reliability of that product will become much higher. These methodologies successfully used in industry might be exceedingly useful also for component development in particle physics where reliability is of the utmost importance. This training will provide participants with the skills necessary to demonstrate reliability requirements using accelerated testing methods. The workshop will focus on accelerated test design that employs increased stress levels. This approach has the advantage of reducing test time, sample size and test facility resources. The methodologies taught are applicable to all types of stresses, spanning the elec...

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

Science.gov (United States)

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

1979-01-01

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.

Tractor accelerated test on test rig

Directory of Open Access Journals (Sweden)

M. Mattetti

2013-09-01

Full Text Available The experimental tests performed to validate a tractor prototype before its production, need a substantial financial and time commitment. The tests could be reduced using accelerated tests able to reproduce on the structural part of the tractor, the same damage produced on the tractor during real life in a reduced time. These tests were usually performed reproducing a particular harsh condition a defined number of times, as for example using a bumpy road on track to carry out the test in any weather condition. Using these procedures the loads applied on the tractor structure are different with respect to those obtained during the real use, with the risk to apply loads hard to find in reality. Recently it has been demonstrated how, using the methodologies designed for cars, it is possible to also expedite the structural tests for tractors. In particular, automotive proving grounds were recently successfully used with tractors to perform accelerated structural tests able to reproduce the real use of the machine with an acceleration factor higher than that obtained with the traditional methods. However, the acceleration factor obtained with a tractor on proving grounds is in any case reduced due to the reduced speed of the tractors with respect to cars. In this context, the goal of the paper is to show the development of a methodology to perform an accelerated structural test on a medium power tractor using a 4 post test rig. In particular, several proving ground testing conditions have been performed to measure the loads on the tractor. The loads obtained were then edited to remove the not damaging portion of signals, and finally the loads obtained were reproduced in a 4 post test rig. The methodology proposed could be a valid alternative to the use of a proving ground to reproduce accelerated structural tests on tractors.

Photometric and Colorimetric Assessment of LED Chip Scale Packages by Using a Step-Stress Accelerated Degradation Test (SSADT) Method.

Science.gov (United States)

Qian, Cheng; Fan, Jiajie; Fang, Jiayi; Yu, Chaohua; Ren, Yi; Fan, Xuejun; Zhang, Guoqi

2017-10-16

By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED) products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT) in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs), i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively), were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample's rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs) of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT) depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs.

Photometric and Colorimetric Assessment of LED Chip Scale Packages by Using a Step-Stress Accelerated Degradation Test (SSADT) Method

Science.gov (United States)

Yu, Chaohua; Fan, Xuejun; Zhang, Guoqi

2017-01-01

By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED) products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT) in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs), i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively), were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample’s rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs) of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT) depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs. PMID:29035300

Method for accelerated aging under combined environmental stress conditions

International Nuclear Information System (INIS)

Gillen, K.T.

1979-01-01

An accelerated aging method which can be used to simulate aging in combined stress environment situations is described. It is shown how the assumptions of the method can be tested experimentally. Aging data for a chloroprene cable jacketing material in single and combined radiation and temperature environments are analyzed and it is shown that these data offer evidence for the validity of the method

Investigation of reliability attributes and accelerated stress factors on terrestrial solar cells

Science.gov (United States)

Lathrop, J. W.; Prince, J. L.

1980-04-01

Three tasks were undertaken to investigate reliability attributes of terrestrial solar cells: (1) a study of the electrical behavior of cells in the second (reverse) quadrant; (2) the accelerated stress testing of three new state-of-the-art cells; and (3) the continued bias-temperature testing of four block 2 type silicon cells at 78 C and 135 C. Electrical characteristics measured in the second quadrant were determined to be a function of the cell's thermal behavior with breakdown depending on the initiation of localized heating. This implied that high breakdown cells may be more fault tolerant when forced to operate in the second quadrant, a result contrary to conventional thinking. The accelerated stress tests used in the first (power) quadrant were bias-temperature, bias-temperature-humidity, temperature-humidity, thermal shock, and thermal cycle. The new type cells measured included an EFG cell, a polycrystalline cell, and a Czochralski cell. Significant differences in the response to the various tests were observed between cell types. A microprocessed controlled, short interval solar cell tester was designed and construction initiated on a prototype.

Development of an accelerated reliability test schedule for terrestrial solar cells

Science.gov (United States)

Lathrop, J. W.; Prince, J. L.

1981-01-01

An accelerated test schedule using a minimum amount of tests and a minimum number of cells has been developed on the basis of stress test results obtained from more than 1500 cells of seven different cell types. The proposed tests, which include bias-temperature, bias-temperature-humidity, power cycle, thermal cycle, and thermal shock tests, use as little as 10 and up to 25 cells, depending on the test type.

Advanced Accelerated Power Cycling Test for Reliability Investigation of Power Device Modules

DEFF Research Database (Denmark)

Choi, Uimin; Jørgensen, Søren; Blaabjerg, Frede

2016-01-01

This paper presents an apparatus and methodology for an advanced accelerated power cycling test of insulated-gate bipolar transistor (IGBT) modules. In this test, the accelerated power cycling test can be performed under more realistic electrical operating conditions with online wear-out monitoring...... of tested power IGBT module. The various realistic electrical operating conditions close to real three-phase converter applications can be achieved by the simple control method. Further, by the proposed concept of applying the temperature stress, it is possible to apply various magnitudes of temperature...... swing in a short cycle period and to change the temperature cycle period easily. Thanks to a short temperature cycle period, test results can be obtained in a reasonable test time. A detailed explanation of apparatus such as configuration and control methods for the different functions of accelerated...

Accelerated life testing design using geometric process for pareto distribution

OpenAIRE

Mustafa Kamal; Shazia Zarrin; Arif Ul Islam

2013-01-01

In this paper the geometric process is used for the analysis of accelerated life testing under constant stress for Pareto Distribution. Assuming that the lifetimes under increasing stress levels form a geometric process, estimates of the parameters are obtained by using the maximum likelihood method for complete data. In addition, asymptotic interval estimates of the parameters of the distribution using Fisher information matrix are also obtained. The statistical properties of the parameters ...

Laser-accelerated particle beams for stress testing of materials.

Science.gov (United States)

Barberio, M; Scisciò, M; Vallières, S; Cardelli, F; Chen, S N; Famulari, G; Gangolf, T; Revet, G; Schiavi, A; Senzacqua, M; Antici, P

2018-01-25

Laser-driven particle acceleration, obtained by irradiation of a solid target using an ultra-intense (I > 10 18  W/cm 2 ) short-pulse (duration testing materials and are particularly suited for identifying materials to be used in harsh conditions. We show that these laser-generated protons can produce, in a very short time scale, a strong mechanical and thermal damage, that, given the short irradiation time, does not allow for recovery of the material. We confirm this by analyzing changes in the mechanical, optical, electrical, and morphological properties of five materials of interest to be used in harsh conditions.

Feasibility, safety and tolerability of accelerated dobutamine stress echocardiography

Directory of Open Access Journals (Sweden)

Pavaci Herribert

2007-11-01

Full Text Available Abstract A continuous infusion of a single high dose of dobutamine has been, recently, suggested as a simple and effective protocol of stress echocardiography. The present study assesses the feasibility, safety, and tolerability of an accelerated dobutamine stress protocol performed in patients with suspected or known coronary artery disease. Two hundred sixty five consecutive patients underwent accelerated dobutamine stress echocardiography: the dobutamine was administered at a constant dose of 50 μg/kg/min for up to 10 minutes. The mean weight-adjusted cumulative dose of dobutamine used was 330 ± 105.24 μg/kg. Total duration of dobutamine infusion was 6.6 ± 2.1 min. Heart rate rose from 69.9 ± 12.1 to 123.1 ± 22.1 beats/min at peak with a concomitant change in systolic blood pressure (127.6 ± 18.1 vs. 167.6 ± 45.0 mmHg. Dobutamine administration produced a rapid increase in heart rate (9.4 ± 5.9 beats/min2. The side effects were similar to those described with the standard protocol; the most common were frequent premature ventricular complexes (21.5%, frequent premature atrial complexes (1.5% and non sustained ventricular tachycardia (1.5%; among non cardiac symptoms the most frequent were nausea (3.4%, headache (1.1% and symptomatic hypotension (1.1%. No major side effects were observed during the test. Our data demonstrate that a continous infusion of a single high dose of dobutamine is a safe and well tolerated method of performing stress echocardiography in patients with suspected or known coronary artery disease. This new protocol requires the administration of lower cumulative dobutamine dose than standard protocol and results in a significant reduction in test time.

Estimation for a Weibull accelerated life testing model

International Nuclear Information System (INIS)

Glaser, R.E.

1984-01-01

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

Stress Testing of Organic Light- Emitting Diode Panels and Luminaires

Energy Technology Data Exchange (ETDEWEB)

Lynn Davis, Kelley Rountree, Karmann Mills

2018-01-31

This report builds on previous DOE efforts with OLED technology by updating information on a previously benchmarked OLED product (the Chalina luminaire from Acuity Brands) and provides new benchmarks on the performance of Brite 2 and Brite Amber OLED panels from OLEDWorks. During the tests described here, samples of these devices were subjected to continuous operation in stress tests at elevated ambient temperature environments of 35°C or 45°C. In addition, samples were also operated continuously at room temperature in a room temperature operational life test (RTOL). One goal of this study was to investigate whether these test conditions can accelerate failure of OLED panels, either through panel shorting or an open circuit in the panel. These stress tests are shown to provide meaningful acceleration of OLED failure modes, and an acceleration factor of 2.6 was calculated at 45°C for some test conditions. In addition, changes in the photometric properties of the emitted light (e.g., luminous flux and chromaticity maintenance) was also evaluated for insights into the long-term stability of these products compared to earlier generations. Because OLEDs are a lighting system, electrical testing was also performed on the panel-driver pairs to provide insights into the impact of the driver on long-term panel performance.

Stresses in the foil of an electron accelerator extraction channel

International Nuclear Information System (INIS)

Abroyan, M.A.; Makarenko, T.I.; Tokmakov, I.L.

1983-01-01

Stresses in the foil of an electron accelerator extraction channel are assessed with account of contributions of thermal expansion and stress concentrations during switchings. Optimization of extraction grid parameters of the electron accelerator extraction channel and choice of foil material for high current electron beam is conducted. It is suggested that an extraction grid with circular cells and Al-Mg foil should be used. A simple formula applicable for design calculations is proposed for evaluation of stress concentration coefficient during phase switchings

Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table

Science.gov (United States)

Sawicki, Andrzej; Kulczykowski, Marek; Jankowski, Robert

2012-12-01

Theoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important to determine the stress field as function of the base acceleration. It is particularly important for a proper interpretation of shaking table tests, where the base acceleration is controlled but the stresses are hard to measure, and they can only be deduced. Preliminary experiments have shown that small accelerations do not lead to essential settlements, whilst large accelerations cause some phenomena typical for limit states, including a visible appearance of slip lines. All these problems should be well understood for rational planning of experiments. The analysis of these problems is presented in this paper. First, some heuristic considerations about the dynamics of experimental system are presented. Then, the analysis of boundary conditions, expressed as resultants of respective stresses is shown. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. Such an approach leads to determination of the limit base accelerations, which do not cause the plastic state in soil. It was shown that larger accelerations lead to increase of the lateral stresses, and the respective method, which may replace complex plasticity analyses, is proposed. It is shown that it is the lateral stress coefficient K0 that controls the statically admissible stress field during the shaking table experiments.

Accelerated Creep Testing of High Strength Aramid Webbing

Science.gov (United States)

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

2012-01-01

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

Catalyst Degradation Under Potential Cycling as an Accelerated Stress Test for PBI-Based High-Temperature PEM Fuel Cells - Effect of Humidification

DEFF Research Database (Denmark)

Søndergaard, Tonny; Cleemann, Lars Nilausen; Zhong, Lijie

2018-01-01

In the present work, high-temperature polymer electrolyte membrane fuel cells were subjected to accelerated stress tests of 30,000 potential cycles between 0.6 and 1.0 V at 160 textdegreeC (133 h cycling time). The effect that humidity has on the catalyst durability was studied by testing either...... with or without humidification of the nitrogen that was used as cathode gas during cycling segments. Pronounced degradation was seen from the polarization curves in both cases, though permanent only in the humidified case. In the unhumidified case, the performance loss was more or less recoverable following 24 h...

The Next Linear Collider Test Accelerator

International Nuclear Information System (INIS)

Ruth, R.D.; Adolphsen, C.; Bane, K.

1993-04-01

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

Multi-axial Creep and the LICON Methodology for Accelerated Creep Testing

International Nuclear Information System (INIS)

Bowyer, William H.

2006-05-01

The copper-Iron canister for disposal of nuclear waste in the Swedish Programme has a design life exceeding 100,000 years. Whilst the operating temperature (100 deg C max.) and operating stress (50 MPa max.) are modest, the very long design life does require that the likely creep performance of the canister should be investigated. Many studies have been carried out by SKB but these have all involved very short duration tests at relatively high stresses. The process of predicting canister creep life by extrapolation of data from such tests has been challenged for two main reasons. The first is that the deformation and failure mechanisms in the tests employed are different from the mechanism expected under service conditions and the second is that the extrapolation is extreme. It has been recognised that there is usually scope for some increase in test temperatures and stresses which will accelerate the development of creep damage without compromising the use of extrapolation for life prediction. Cane demonstrated that in steels designed for high temperature and pressure applications, conditions of multi-axial stressing could lead to increases or decreases in the rate of damage accumulation without changing the damage mechanism. This provided a third method for accelerating creep testing which has been implemented as the LICON method. This report aims to explain the background to the LICON method and its application to the case of the copper canister. It seems likely that the method could be used to improve our knowledge of the creep resistance of the copper canister. Multiplication factors that may be achieved by the technique could be increased by attention to specimen design but an extensive and targeted programme of data collection on creep of copper would still be needed to implement the method to best advantage

Multi-axial Creep and the LICON Methodology for Accelerated Creep Testing

Energy Technology Data Exchange (ETDEWEB)

Bowyer, William H. [Meadow End Farm, Farnham (United Kingdom)

2006-05-15

The copper-Iron canister for disposal of nuclear waste in the Swedish Programme has a design life exceeding 100,000 years. Whilst the operating temperature (100 deg C max.) and operating stress (50 MPa max.) are modest, the very long design life does require that the likely creep performance of the canister should be investigated. Many studies have been carried out by SKB but these have all involved very short duration tests at relatively high stresses. The process of predicting canister creep life by extrapolation of data from such tests has been challenged for two main reasons. The first is that the deformation and failure mechanisms in the tests employed are different from the mechanism expected under service conditions and the second is that the extrapolation is extreme. It has been recognised that there is usually scope for some increase in test temperatures and stresses which will accelerate the development of creep damage without compromising the use of extrapolation for life prediction. Cane demonstrated that in steels designed for high temperature and pressure applications, conditions of multi-axial stressing could lead to increases or decreases in the rate of damage accumulation without changing the damage mechanism. This provided a third method for accelerating creep testing which has been implemented as the LICON method. This report aims to explain the background to the LICON method and its application to the case of the copper canister. It seems likely that the method could be used to improve our knowledge of the creep resistance of the copper canister. Multiplication factors that may be achieved by the technique could be increased by attention to specimen design but an extensive and targeted programme of data collection on creep of copper would still be needed to implement the method to best advantage.

Accelerated life testing and reliability of high K multilayer ceramic capacitors

Science.gov (United States)

Minford, W. J.

1981-01-01

The reliability of one lot of high K multilayer ceramic capacitors was evaluated using accelerated life testing. The degradation in insulation resistance was characterized as a function of voltage and temperature. The times to failure at a voltage-temperature stress conformed to a lognormal distribution with a standard deviation approximately 0.5.

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

Science.gov (United States)

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

1982-01-01

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

Accelerated life testing of spacecraft subsystems

Science.gov (United States)

Wiksten, D.; Swanson, J.

1972-01-01

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

Reliability and Lifetime Prediction of Remote Phosphor Plates in Solid-State Lighting Applications Using Accelerated Degradation Testing

NARCIS (Netherlands)

Yazdan Mehr, M.; van Driel, W.D.; Zhang, G.Q.

2015-01-01

A methodology, based on accelerated degradation testing, is developed to predict the lifetime of remote phosphor plates used in solid-state lighting (SSL) applications. Both thermal stress and light intensity are used to accelerate degradation reaction in remote phosphor plates. A reliability model,

Nuclear stress test

Science.gov (United States)

... Persantine stress test; Thallium stress test; Stress test - nuclear; Adenosine stress test; Regadenoson stress test; CAD - nuclear stress; Coronary artery disease - nuclear stress; Angina - nuclear ...

Accelerated cyclic corrosion tests

Directory of Open Access Journals (Sweden)

Prošek T.

2016-06-01

Full Text Available Accelerated corrosion testing is indispensable for material selection, quality control and both initial and residual life time prediction for bare and painted metallic, polymeric, adhesive and other materials in atmospheric exposure conditions. The best known Neutral Salt Spray (NSS test provides unrealistic conditions and poor correlation to exposures in atmosphere. Modern cyclic accelerated corrosion tests include intermittent salt spray, wet and dry phases and eventually other technical phases. They are able to predict the material performance in service more correctly as documented on several examples. The use of NSS should thus be restricted for quality control.

Traumatic stress and accelerated DNA methylation age: A meta-analysis.

Science.gov (United States)

Wolf, Erika J; Maniates, Hannah; Nugent, Nicole; Maihofer, Adam X; Armstrong, Don; Ratanatharathorn, Andrew; Ashley-Koch, Allison E; Garrett, Melanie; Kimbrel, Nathan A; Lori, Adriana; Va Mid-Atlantic Mirecc Workgroup; Aiello, Allison E; Baker, Dewleen G; Beckham, Jean C; Boks, Marco P; Galea, Sandro; Geuze, Elbert; Hauser, Michael A; Kessler, Ronald C; Koenen, Karestan C; Miller, Mark W; Ressler, Kerry J; Risbrough, Victoria; Rutten, Bart P F; Stein, Murray B; Ursano, Robert J; Vermetten, Eric; Vinkers, Christiaan H; Uddin, Monica; Smith, Alicia K; Nievergelt, Caroline M; Logue, Mark W

2018-06-01

Recent studies examining the association between posttraumatic stress disorder (PTSD) and accelerated aging, as defined by DNA methylation-based estimates of cellular age that exceed chronological age, have yielded mixed results. We conducted a meta-analysis of trauma exposure and PTSD diagnosis and symptom severity in association with accelerated DNA methylation age using data from 9 cohorts contributing to the Psychiatric Genomics Consortium PTSD Epigenetics Workgroup (combined N = 2186). Associations between demographic and cellular variables and accelerated DNA methylation age were also examined, as was the moderating influence of demographic variables. Meta-analysis of regression coefficients from contributing cohorts revealed that childhood trauma exposure (when measured with the Childhood Trauma Questionnaire) and lifetime PTSD severity evidenced significant, albeit small, meta-analytic associations with accelerated DNA methylation age (ps = 0.028 and 0.016, respectively). Sex, CD4T cell proportions, and natural killer cell proportions were also significantly associated with accelerated DNA methylation age (all ps age. There was no evidence of moderation of the trauma or PTSD variables by demographic factors. Results suggest that traumatic stress is associated with advanced epigenetic age and raise the possibility that cells integral to immune system maintenance and responsivity play a role in this. This study highlights the need for additional research into the biological mechanisms linking traumatic stress to accelerated DNA methylation age and the importance of furthering our understanding of the neurobiological and health consequences of PTSD. Published by Elsevier Ltd.

Accelerated Life Structural Benchmark Testing for a Stirling Convertor Heater Head

Science.gov (United States)

Krause, David L.; Kantzos, Pete T.

2006-01-01

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.

Voltage stress effects on microcircuit accelerated life test failure rates

Science.gov (United States)

Johnson, G. M.

1976-01-01

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.

Accelerated Aging during Chronic Oxidative Stress: A Role for PARP-1

Directory of Open Access Journals (Sweden)

Daniëlle M. P. H. J. Boesten

2013-01-01

Full Text Available Oxidative stress plays a major role in the pathophysiology of chronic inflammatory disease and it has also been linked to accelerated telomere shortening. Telomeres are specialized structures at the ends of linear chromosomes that protect these ends from degradation and fusion. Telomeres shorten with each cell division eventually leading to cellular senescence. Research has shown that poly(ADP-ribose polymerase-1 (PARP-1 and subtelomeric methylation play a role in telomere stability. We hypothesized that PARP-1 plays a role in accelerated aging in chronic inflammatory diseases due to its role as coactivator of NF-κb and AP-1. Therefore we evaluated the effect of chronic PARP-1 inhibition (by fisetin and minocycline in human fibroblasts (HF cultured under normal conditions and under conditions of chronic oxidative stress, induced by tert-butyl hydroperoxide (t-BHP. Results showed that PARP-1 inhibition under normal culturing conditions accelerated the rate of telomere shortening. However, under conditions of chronic oxidative stress, PARP-1 inhibition did not show accelerated telomere shortening. We also observed a strong correlation between telomere length and subtelomeric methylation status of HF cells. We conclude that chronic PARP-1 inhibition appears to be beneficial in conditions of chronic oxidative stress but may be detrimental under relatively normal conditions.

Radiative processes for Rindler and accelerating observers and the stress-tensor detector

International Nuclear Information System (INIS)

Paola, R. De; Svaiter, N.F.

1996-04-01

It is considered a monopole detector interacting with a massive scalar field. Using the rotating wave approximation the radiative processes is discussed from the accelerated frame point of view. After this, it is obtained the Minkowski vacuum stress tensor measured by the accelerated observer using a non-gravitational stress sensor detector. Finally we analyse radiative processes of the monopole detector travelling in a world line that is inertial in the infinite past and has a constant proper acceleration in the infinite future. (author). 30 refs

Accelerated test program

Science.gov (United States)

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

1977-01-01

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.

Major depressive disorder mediates accelerated aging in rats subjected to chronic mild stress.

Science.gov (United States)

Xie, Xiaoxian; Chen, Yangyang; Ma, Lingyan; Shen, Qichen; Huang, Liangfeng; Zhao, Binggong; Wu, Tao; Fu, Zhengwei

2017-06-30

Major depressive disorder (MDD) has a complex etiology and is characterized by a change in mood and psychophysiological state. MDD has been shown to mediate accelerated biological aging in patients, although the underlying mechanism is not well understood. In the present study, we used a chronic mild stress (CMS) paradigm to induce anhedonia, one of the main symptoms of MDD. CMS induced depression-like symptoms in rats, including reduced sucrose preference and increased immobility time in the forced swim test. Moreover, stressed rats travelled a shorter total distance, had fewer grid line crossings, and spent less time in the outer zone in the open field test than controls. CMS altered the levels of 5-hydroxytryptophan, dopamine, and corticosterone in the serum and hippocampus (P<0.05); these rats also exhibited impaired liver function, decreased telomerase activity, and telomere shortening, which was associated with increased oxidative damage along with decreased superoxide dismutase and glutathione reductase activities. Mitochondria in CMS-treated rats showed ultrastructural damage as well as reduced DNA content and integrity. These findings provide physiological and cellular evidence that the MDD can mediate accelerated aging in rats. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimal design of accelerated life tests for an extension of the exponential distribution

International Nuclear Information System (INIS)

Haghighi, Firoozeh

2014-01-01

Accelerated life tests provide information quickly on the lifetime distribution of the products by testing them at higher than usual levels of stress. In this paper, the lifetime of a product at any level of stress is assumed to have an extension of the exponential distribution. This new family has been recently introduced by Nadarajah and Haghighi (2011 [1]); it can be used as an alternative to the gamma, Weibull and exponentiated exponential distributions. The scale parameter of lifetime distribution at constant stress levels is assumed to be a log-linear function of the stress levels and a cumulative exposure model holds. For this model, the maximum likelihood estimates (MLEs) of the parameters, as well as the Fisher information matrix, are derived. The asymptotic variance of the scale parameter at a design stress is adopted as an optimization objective and its expression formula is provided using the maximum likelihood method. A Monte Carlo simulation study is carried out to examine the performance of these methods. The asymptotic confidence intervals for the parameters and hypothesis test for the parameter of interest are constructed

Evaluation of accelerated stability test conditions for medicated chewing gums.

Science.gov (United States)

Maggi, Lauretta; Conte, Ubaldo; Nhamias, Alain; Grenier, Pascal; Vergnault, Guy

2013-10-01

The overall stability of medicated chewing gums is investigated under different storage conditions. Active substances with different chemical stabilities in solid state are chosen as model drugs. The dosage form is a three layer tablet obtained by direct compression. The gum core contains the active ingredient while the external layers are formulated to prevent gum adhesion to the punches of the tableting machine. Two accelerated test conditions (40°C/75% RH and 30°C/65% RH) are performed for 6 months. Furthermore, a long-term stability test at room conditions is conducted to verify the predictability of the results obtained from the stress tests. Some drugs are stable in all the conditions tested, but other drugs, generally considered stable in solid dosage forms, have shown relevant stability problems particularly when stress test conditions are applied to this particular semi-solid dosage forms. For less stable drugs, the stress conditions of 40°C/75% RH are not always predictable of chewing gum stability at room temperature and may produce false negative; intermediate conditions, 30°C/65% RH, are more predictive for this purpose, the results of drug content found after 6 months at intermediate stress conditions and 12 months at room conditions are generally comparable. But the results obtained show that only long-term conditions stability tests gave consistent results. During aging, the semi solid nature of the gum base itself, may also influence the drug delivery rate during chewing and great attention should be given also to the dissolution stability.

Quantum corrections to the stress-energy tensor in thermodynamic equilibrium with acceleration

Science.gov (United States)

Becattini, F.; Grossi, E.

2015-08-01

We show that the stress-energy tensor has additional terms with respect to the ideal form in states of global thermodynamic equilibrium in flat spacetime with nonvanishing acceleration and vorticity. These corrections are of quantum origin and their leading terms are second order in the gradients of the thermodynamic fields. Their relevant coefficients can be expressed in terms of correlators of the stress-energy tensor operator and the generators of the Lorentz group. With respect to previous assessments, we find that there are more second-order coefficients and that all thermodynamic functions including energy density receive acceleration and vorticity dependent corrections. Notably, also the relation between ρ and p , that is, the equation of state, is affected by acceleration and vorticity. We have calculated the corrections for a free real scalar field—both massive and massless—and we have found that they increase, particularly for a massive field, at very high acceleration and vorticity and very low temperature. Finally, these nonideal terms depend on the explicit form of the stress-energy operator, implying that different stress-energy tensors of the scalar field—canonical or improved—are thermodynamically inequivalent.

Role of failure-mechanism identification in accelerated testing

Science.gov (United States)

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

1993-01-01

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

Are malnutrition and stress risk factors for accelerated cognitive decline? A prisoner of war study.

Science.gov (United States)

Sulway, M R; Broe, G A; Creasey, H; Dent, O F; Jorm, A F; Kos, S C; Tennant, C C

1996-03-01

We set out to test the hypothesis that severe malnutrition and stress experienced by prisoners of war (POWs) are associated with cognitive deficits later in life. We assessed 101 former Australian POWs of the Japanese and 108 veteran control subjects using a battery of neuropsychological tests, a depression scale, a clinical examination for dementia, and CT. We divided the POWs into high weight loss (>35%) and low weight loss groups (malnutrition is a risk factor for accelerated cognitive decline nor the theory that severe stress can lead to hippocampal neuronal loss and cognitive deficits. Cognitive deficits in earlier studies of former POWs may have been associated with concurrent depression.

Dysregulated physiological stress systems and accelerated cellular aging

NARCIS (Netherlands)

Révész, D.; Verhoeven, J.; Milaneschi, Y.; de Geus, E.J.C.; Wolkowitz, O.M.; Penninx, B.W.J.H.

2014-01-01

Exposure to chronic stressors is associated with accelerated biological aging as indicated by reduced leukocyte telomere length (LTL). This impact could be because of chronic overactivation of the body's physiological stress systems. This study examined the associations between LTL and the immune

Acceleration test with mixed higher harmonics in HIMAC

International Nuclear Information System (INIS)

Kanazawa, M.; Sugiura, A.; Misu, T.

2004-01-01

In HIMAC synchrotron, beam tests with a magnetic ally loaded cavity have been performed. This cavity has very low Q-value of about 0.5, and can be added higher harmonics with fundamental acceleration frequency. In our tested system for higher harmonics, wave form of a DDS (Direct Digital Synthesizer) can be rewrite, and arbitrary wave form can be used for beam acceleration. In the beam test, second and third harmonic wave were added on the fundamental acceleration frequency, and increases of the accelerated beam intensity have been achieved. In this paper, results of the beam test and the acceleration system are presented. (author)

Accelerated Strength Testing of Thermoplastic Composites

Science.gov (United States)

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

1998-01-01

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.

Synthetic sea water - An improved stress corrosion test medium for aluminum alloys

Science.gov (United States)

Humphries, T. S.; Nelson, E. E.

1973-01-01

A major problem in evaluating the stress corrosion cracking resistance of aluminum alloys by alternate immersion in 3.5 percent salt (NaCl) water is excessive pitting corrosion. Several methods were examined to eliminate this problem and to find an improved accelerated test medium. These included the addition of chromate inhibitors, surface treatment of specimens, and immersion in synthetic sea water. The results indicate that alternate immersion in synthetic sea water is a very promising stress corrosion test medium. Neither chromate inhibitors nor surface treatment (anodize and alodine) of the aluminum specimens improved the performance of alternate immersion in 3.5 percent salt water sufficiently to be classified as an effective stress corrosion test method.

Accelerated Solar-UV Test Chamber

Science.gov (United States)

Gupta, A.; Laue, E. G.

1984-01-01

Medium-pressure mercury-vapor lamps provide high ratio of ultraviolet to total power. Chamber for evaluating solar-ultraviolet (UV) radiation damage permits accelerated testing without overheating test specimens.

The Brookhaven Accelerator Test Facility

International Nuclear Information System (INIS)

Batchelor, K.; Ben-Zvi, I.; Fernow, R.C.; Fischer, J.; Fisher, A.S.; Gallardo, J.; Jialin, Xie; Kirk, H.G.; Parsa, Z.; Palmer, R.B.; Rao, T.; Rogers, J.; Sheehan, J.; Tsang, T.Y.F.; Ulc, S.; Van Steenbergen, A.; Woodle, M.; Zhang, R.S.; McDonald, K.T.; Russell, D.P.; Jiang, Z.Y.; Pellegrini, C.; Wang, X.J.

1990-01-01

The Accelerator Test Facility (ATF), presently under construction at Brookhaven National laboratory, is described. It consists of a 50-MeV electron beam synchronizable to a high-peak power CO 2 laser. The interaction of electrons with the laser field will be probed, with some emphasis on exploring laser-based acceleration techniques. 5 refs., 2 figs

Accelerated leach test development program

International Nuclear Information System (INIS)

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

1990-11-01

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

Accelerated life testing effects on CMOS microcircuit characteristics

Science.gov (United States)

1980-01-01

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.

Stress corrosion evaluation of powder metallurgy aluminum alloy 7091 with the breaking load test method

Science.gov (United States)

Domack, Marcia S.

1987-01-01

The stress corrosion behavior of the P/M aluminum alloy 7091 is evaluated in two overaged heat treatment conditions, T7E69 and T7E70, using an accelerated test technique known as the breaking load test method. The breaking load data obtained in this study indicate that P/M 7091 alloy is highly resistant to stress corrosion in both longitudinal and transverse orientations at stress levels up to 90 percent of the material yield strength. The reduction in mean breaking stress as a result of corrosive attack is smallest for the more overaged T7E70 condition. Details of the test procedure are included.

The Brookhaven National Laboratory Accelerator Test Facility

International Nuclear Information System (INIS)

Batchelor, K.

1992-01-01

The Brookhaven National Laboratory Accelerator Test Facility comprises a 50 MeV traveling wave electron linear accelerator utilizing a high gradient, photo-excited, raidofrequency electron gun as an injector and an experimental area for study of new acceleration methods or advanced radiation sources using free electron lasers. Early operation of the linear accelerator system including calculated and measured beam parameters are presented together with the experimental program for accelerator physics and free electron laser studies

Assessing high reliability via Bayesian approach and accelerated tests

International Nuclear Information System (INIS)

Erto, Pasquale; Giorgio, Massimiliano

2002-01-01

Sometimes the assessment of very high reliability levels is difficult for the following main reasons: - the high reliability level of each item makes it impossible to obtain, in a reasonably short time, a sufficient number of failures; - the high cost of the high reliability items to submit to life tests makes it unfeasible to collect enough data for 'classical' statistical analyses. In the above context, this paper presents a Bayesian solution to the problem of estimation of the parameters of the Weibull-inverse power law model, on the basis of a limited number (say six) of life tests, carried out at different stress levels, all higher than the normal one. The over-stressed (i.e. accelerated) tests allow the use of experimental data obtained in a reasonably short time. The Bayesian approach enables one to reduce the required number of failures adding to the failure information the available a priori engineers' knowledge. This engineers' involvement conforms to the most advanced management policy that aims at involving everyone's commitment in order to obtain total quality. A Monte Carlo study of the non-asymptotic properties of the proposed estimators and a comparison with the properties of maximum likelihood estimators closes the work

The Stress Acceleration Hypothesis of Nightmares

Directory of Open Access Journals (Sweden)

Tore Nielsen

2017-06-01

Full Text Available Adverse childhood experiences can deleteriously affect future physical and mental health, increasing risk for many illnesses, including psychiatric problems, sleep disorders, and, according to the present hypothesis, idiopathic nightmares. Much like post-traumatic nightmares, which are triggered by trauma and lead to recurrent emotional dreaming about the trauma, idiopathic nightmares are hypothesized to originate in early adverse experiences that lead in later life to the expression of early memories and emotions in dream content. Accordingly, the objectives of this paper are to (1 review existing literature on sleep, dreaming and nightmares in relation to early adverse experiences, drawing upon both empirical studies of dreaming and nightmares and books and chapters by recognized nightmare experts and (2 propose a new approach to explaining nightmares that is based upon the Stress Acceleration Hypothesis of mental illness. The latter stipulates that susceptibility to mental illness is increased by adversity occurring during a developmentally sensitive window for emotional maturation—the infantile amnesia period—that ends around age 3½. Early adversity accelerates the neural and behavioral maturation of emotional systems governing the expression, learning, and extinction of fear memories and may afford short-term adaptive value. But it also engenders long-term dysfunctional consequences including an increased risk for nightmares. Two mechanisms are proposed: (1 disruption of infantile amnesia allows normally forgotten early childhood memories to influence later emotions, cognitions and behavior, including the common expression of threats in nightmares; (2 alterations of normal emotion regulation processes of both waking and sleep lead to increased fear sensitivity and less effective fear extinction. These changes influence an affect network previously hypothesized to regulate fear extinction during REM sleep, disruption of which leads to

Repeated restraint stress exposure during early withdrawal accelerates incubation of cue-induced cocaine craving.

Science.gov (United States)

Glynn, Ryan M; Rosenkranz, J Amiel; Wolf, Marina E; Caccamise, Aaron; Shroff, Freya; Smith, Alyssa B; Loweth, Jessica A

2018-01-01

A major challenge for treating cocaine addiction is the propensity for abstinent users to relapse. Two important triggers for relapse are cues associated with prior drug use and stressful life events. To study their interaction in promoting relapse during abstinence, we used the incubation model of craving and relapse in which cue-induced drug seeking progressively intensifies ('incubates') during withdrawal from extended-access cocaine self-administration. We tested rats for cue-induced cocaine seeking on withdrawal day (WD) 1. Rats were then subjected to repeated restraint stress or control conditions (seven sessions held between WD6 and WD14). All rats were tested again for cue-induced cocaine seeking on WD15, 1 day after the last stress or control session. Although controls showed a time-dependent increase in cue-induced cocaine seeking (incubation), rats exposed to repeated stress in early withdrawal exhibited a more robust increase in seeking behavior between WD1 and WD15. In separate stressed and control rats, equivalent cocaine seeking was observed on WD48. These results indicate that repeated stress in early withdrawal accelerates incubation of cocaine craving, although craving plateaus at the same level were observed in controls. However, 1 month after the WD48 test, rats subjected to repeated stress in early withdrawal showed enhanced cue-induced cocaine seeking following acute (24 hours) food deprivation stress. Together, these data indicate that chronic stress exposure enhances the initial rate of incubation of craving during early withdrawal, resulting in increased vulnerability to cue-induced relapse during this period, and may lead to a persistent increase in vulnerability to the relapse-promoting effects of stress. © 2016 Society for the Study of Addiction.

Laboratory Test of Newton's Second Law for Small Accelerations

International Nuclear Information System (INIS)

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

2007-01-01

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 -14 m/s 2

Vehicle accelerated corrosion test procedures for automotive in Malaysia

Directory of Open Access Journals (Sweden)

Anuar Liza

2017-01-01

Full Text Available An accelerated corrosion test, known as proving ground accelerated test, is commonly performed by automotive manufacturers to evaluate the corrosion performance of a vehicle. The test combines corrosion and durability inputs to detect potential failures that may occur during in-service conditions. Currently, the test is conducted at an external test center overseas. Such test is aimed to simulate the effects of one year accelerated corrosion in severe corrosive environment of the north-east and south east of America. However, the test results obtained do not correlate with the actual corrosion conditions observed in the Malaysian market, which is likely attributed to the different test environment of the tropical climate of vehicles in service. Therefore, a vehicle accelerated corrosion test procedure that suits the Malaysian market is proposed and benchmarked with other global car manufacturers that have their own dedicated corrosion test procedure. In the present work, a test track is used as the corrosion test ground and consists of various types of roads for structural durability exposures. Corrosion related facilities like salt trough, mud trough and gravel road are constructed as addition to the existing facilities. The establishment of accelerated corrosion test facilities has contributed to the development of initial accelerated corrosion test procedure for the national car manufacturer. The corrosion exposure is monitored by fitting test coupons at the underbody of test vehicle using mass loss technique so that the desired corrosion rate capable of simulating the real time corrosion effects for its target market.

Earthquake acceleration amplification based on single microtremor test

Science.gov (United States)

Jaya Syahbana, Arifan; Kurniawan, Rahmat; Soebowo, Eko

2018-02-01

Understanding soil dynamics is needed to understand soil behaviour, including the parameters of earthquake acceleration amplification. Many researchers now conduct single microtremor tests to obtain amplification of velocity and natural periods of soil at test sites. However, these amplification parameters are rarely used, so a method is needed to convert the velocity amplification to acceleration amplification. This paper will discuss the proposed process of changing the value of amplification. The proposed method is to integrate the time histories of the synthetic earthquake acceleration of the soil surface under the deaggregation at that location so the time histories of the velocity earthquake will be obtained. Next is to conduct a “fitting curve” between amplification by a single microtremor test with amplification of the synthetic earthquake velocity time histories. After obtaining the fitting curve time histories of velocity, differentiation will be conducted to obtain fitting curve acceleration time histories. The final step after obtaining the fitting curve is to compare the acceleration of the “fitting curve” against the histories time of the acceleration of synthetic earthquake at bedrocks to obtain single microtremor acceleration amplification factor.

Accelerated Test Method for Corrosion Protective Coatings Project

Science.gov (United States)

Falker, John; Zeitlin, Nancy; Calle, Luz

2015-01-01

This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as accurately and reliably as current long-term atmospheric exposure tests. This new accelerated test method will shorten the time needed to evaluate the corrosion protection performance of coatings for NASA's critical ground support structures. Lifetime prediction for spaceport structure coatings has a 5-year qualification cycle using atmospheric exposure. Current accelerated corrosion tests often provide false positives and negatives for coating performance, do not correlate to atmospheric corrosion exposure results, and do not correlate with atmospheric exposure timescales for lifetime prediction.

Recent progress of the advanced test accelerator

International Nuclear Information System (INIS)

Prono, D.S.

1985-01-01

The Advanced Test Accelerator (ATA) of Lawrence Livermore National Laboratory is a linear induction accelerator whose electron beam parameters are 10 kA, 50 MeV, and 70 ns. This accelerator structure basically is a 2.5 MeV injector followed by 190 identical induction accelerator cores each of which incrementally adds 250 kV to the electron beam as it threads the center of the core. Recent work on beam stability, beam emittance and beam brightness is reported

Test Stand for Linear Induction Accelerator Optimization

International Nuclear Information System (INIS)

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

2003-01-01

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

Advanced Test Accelerator (ATA) pulse power technology development

International Nuclear Information System (INIS)

Reginato, L.L.; Branum, D.; Cook, E.

1981-01-01

The Advanced Test Accelerator (ATA) is a pulsed linear induction accelerator with the following design parameters: 50 MeV, 10 kA, 70 ns, and 1 kHz in a ten-pulse burst. Acceleration is accomplished by means of 190 ferrite-loaded cells, each capable of maintaining a 250 kV voltage pulse for 70 ns across a 1-inch gap. The unique characteristic of this machine is its 1 kHz burst mode capability at very high currents. This paper dscribes the pulse power development program which used the Experimental Test Accelerator (ETA) technology as a starting base. Considerable changes have been made both electrically and mechanically in the pulse power components with special consideration being given to the design to achieve higher reliability. A prototype module which incorporates all the pulse power components has been built and tested for millions of shots. Prototype components and test results are described

Test accelerator for linear collider

International Nuclear Information System (INIS)

Takeda, S.; Akai, K.; Akemoto, M.; Araki, S.; Hayano, H.; Hugo, T.; Ishihara, N.; Kawamoto, T.; Kimura, Y.; Kobayashi, H.; Kubo, T.; Kurokawa, S.; Matsumoto, H.; Mizuno, H.; Odagiri, J.; Otake, Y.; Sakai, H.; Shidara, T.; Shintake, T.; Suetake, M.; Takashima, T.; Takata, K.; Takeuchi, Y.; Urakawa, J.; Yamamoto, N.; Yokoya, K.; Yoshida, M.; Yoshioka, M.; Yamaoka, Y.

1989-01-01

KEK has proposed to build Test Accelerator Facility (TAF) capable of producing a 2.5 GeV electron beam for the purpose of stimulating R ampersand D for linear collider in TeV region. The TAF consists of a 1.5 GeV S-band linear accelerator, 1.5 GeV damping ring and 1.0 GeV X-band linear accelerator. The TAF project will be carried forward in three phases. Through Phase-I and Phase-II, the S-band and X-band linacs will be constructed, and in Phase-III, the damping ring will be completed. The construction of TAF Phase-I has started, and the 0.2 GeV S-band injector linac has been almost completed. The Phase-I linac is composed of a 240 keV electron gun, subharmonic bunchers, prebunchers and traveling buncher followed by high-gradient accelerating structures. The SLAC 5045 klystrons are driven at 450 kV in order to obtain the rf-power of 100 MW in a 1 μs pulse duration. The rf-power from a pair of klystrons are combined into an accelerating structure. The accelerating gradient up to 100 MeV/m will be obtained in a 0.6 m long structure. 5 refs., 3 figs., 2 tabs

Understanding How Kurtosis Is Transferred from Input Acceleration to Stress Response and Its Influence on Fatigue Llife

Science.gov (United States)

Kihm, Frederic; Rizzi, Stephen A.; Ferguson, Neil S.; Halfpenny, Andrew

2013-01-01

High cycle fatigue of metals typically occurs through long term exposure to time varying loads which, although modest in amplitude, give rise to microscopic cracks that can ultimately propagate to failure. The fatigue life of a component is primarily dependent on the stress amplitude response at critical failure locations. For most vibration tests, it is common to assume a Gaussian distribution of both the input acceleration and stress response. In real life, however, it is common to experience non-Gaussian acceleration input, and this can cause the response to be non-Gaussian. Examples of non-Gaussian loads include road irregularities such as potholes in the automotive world or turbulent boundary layer pressure fluctuations for the aerospace sector or more generally wind, wave or high amplitude acoustic loads. The paper first reviews some of the methods used to generate non-Gaussian excitation signals with a given power spectral density and kurtosis. The kurtosis of the response is examined once the signal is passed through a linear time invariant system. Finally an algorithm is presented that determines the output kurtosis based upon the input kurtosis, the input power spectral density and the frequency response function of the system. The algorithm is validated using numerical simulations. Direct applications of these results include improved fatigue life estimations and a method to accelerate shaker tests by generating high kurtosis, non-Gaussian drive signals.

Inspection of piping wall loss with flow accelerated corrosion accelerated simulation test

International Nuclear Information System (INIS)

Ryu, Kyung Ha; Kim, Ji Hak; Hwang, Il Soon; Lee, Na Young; Kim, Ji Hyun

2009-01-01

Flow Accelerated Corrosion (FAC) has become a hot issue for aging of passive components. Ultrasonic Technique (UT) has been adopted to inspect the secondary piping of Nuclear Power Plants (NPPs). UT, however, uses point detection method, which results in numerous detecting points and thus takes time. We developed an Equipotential Switching Direct Current Potential Drop (ES-DCPD) method to monitor the thickness of piping that covers wide range of piping at once time. Since the ES-DCPD method covers area, not a point, it needs less monitoring time. This can be a good approach to broad carbon steel piping system such as secondary piping of NPPs. In this paper, FAC accelerated simulation test results is described. We realized accelerated FAC phenomenon by 2 times test: 23.7% thinning in 216.7 hours and 51% thinning in 795 hours. These were monitored by ES-DCPD and traditional UT. Some parameters of water chemistry are monitored and controlled to accelerate FAC process. As sensitive factors on FAC, temperature and pH was changed during the test. The wall loss monitored results reflected these changes of water chemistry successfully. Developed electrodes are also applied to simulation loop to monitor water chemistry. (author)

Cooling the APS storage ring radio-frequency accelerating cavities: Thermal/stress/fatigue analysis and cavity cooling configuration

International Nuclear Information System (INIS)

Primdahl, K.; Kustom, R.

1995-01-01

The 7-GeV Advanced Photon Source positron storage ring requires sixteen separate 352-MHz radio-frequency (rf) accelerating cavities. Cavities are installed as groups of four, in straight sections used elsewhere for insertion devices. They occupy the first such straight section after injection, along with the last three just before injection. Cooling is provided by a subsystem of the sitewide deionized water system. Pumping equipment is located in a building directly adjacent to the accelerator enclosure. A prototype cavity was fabricated and tested where cooling was via twelve 19-mm-diameter [3/4 in] brazed-on tubes in a series-parallel flow configuration. Unfortunately, the thermal contact to some tubes was poor due to inadequate braze filler. Here, heat transfer studies, including finite-element analysis and test results, of the Advanced Photon Source (APS) storage ring 352-MHz rf accelerating cavities are described. Stress and fatigue life of the copper are discussed. Configuration of water cooling is presented

Accelerated aging in schizophrenia patients: the potential role of oxidative stress.

Science.gov (United States)

Okusaga, Olaoluwa O

2014-08-01

Several lines of evidence suggest that schizophrenia, a severe mental illness characterized by delusions, hallucinations and thought disorder is associated with accelerated aging. The free radical (oxidative stress) theory of aging assumes that aging occurs as a result of damage to cell constituents and connective tissues by free radicals arising from oxygen-associated reactions. Schizophrenia has been associated with oxidative stress and chronic inflammation, both of which also appear to reciprocally induce each other in a positive feedback manner. The buildup of damaged macromolecules due to increased oxidative stress and failure of protein repair and maintenance systems is an indicator of aging both at the cellular and organismal level. When compared with age-matched healthy controls, schizophrenia patients have higher levels of markers of oxidative cellular damage such as protein carbonyls, products of lipid peroxidation and DNA hydroxylation. Potential confounders such as antipsychotic medication, smoking, socio-economic status and unhealthy lifestyle make it impossible to solely attribute the earlier onset of aging-related changes or oxidative stress to having a diagnosis of schizophrenia. Regardless of whether oxidative stress can be attributed solely to a diagnosis of schizophrenia or whether it is due to other factors associated with schizophrenia, the available evidence is in support of increased oxidative stress-induced cellular damage of macromolecules which may play a role in the phenomenon of accelerated aging presumed to be associated with schizophrenia.

Cathodic Delamination Accelerated Life Test Method

National Research Council Canada - National Science Library

Ramotowski, Thomas S

2007-01-01

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

Significance of acceleration period in a dynamic strength testing study.

Science.gov (United States)

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

1994-06-01

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.

Advanced Superconducting Test Accelerator (ASTA)

Data.gov (United States)

Federal Laboratory Consortium — The Advanced Superconducting Test Accelerator (ASTA) facility will be based on upgrades to the existing NML pulsed SRF facility. ASTA is envisioned to contain 3 to 6...

Accelerated Leach Test(s) Program: Annual report

International Nuclear Information System (INIS)

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

1986-09-01

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

Early life stress accelerates behavioral and neural maturation of the hippocampus in male mice.

Science.gov (United States)

Bath, K; Manzano-Nieves, G; Goodwill, H

2016-06-01

Early life stress (ELS) increases the risk for later cognitive and emotional dysfunction. ELS is known to truncate neural development through effects on suppressing cell birth, increasing cell death, and altering neuronal morphology, effects that have been associated with behavioral profiles indicative of precocious maturation. However, how earlier silencing of growth drives accelerated behavioral maturation has remained puzzling. Here, we test the novel hypothesis that, ELS drives a switch from growth to maturation to accelerate neural and behavioral development. To test this, we used a mouse model of ELS, fragmented maternal care, and a cross-sectional dense sampling approach focusing on hippocampus and measured effects of ELS on the ontogeny of behavioral development and biomarkers of neural maturation. Consistent with previous work, ELS was associated with an earlier developmental decline in expression of markers of cell proliferation (Ki-67) and differentiation (doublecortin). However, ELS also led to a precocious arrival of Parvalbumin-positive cells, led to an earlier switch in NMDA receptor subunit expression (marker of synaptic maturity), and was associated with an earlier rise in myelin basic protein expression (key component of the myelin sheath). In addition, in a contextual fear-conditioning task, ELS accelerated the timed developmental suppression of contextual fear. Together, these data provide support for the hypothesis that ELS serves to switch neurodevelopment from processes of growth to maturation and promotes accelerated development of some forms of emotional learning. Copyright © 2016 Elsevier Inc. All rights reserved.

Proposal for an Accelerator R&D User Facility at Fermilab's Advanced Superconducting Test Accelerator (ASTA)

Energy Technology Data Exchange (ETDEWEB)

Church, M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Edwards, H. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Harms, E. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Henderson, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Holmes, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lumpkin, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Kephart, R. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Levedev, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Leibfritz, J. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Nagaitsev, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Piot, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Northern Illinois Univ., DeKalb, IL (United States); Prokop, C. [Northern Illinois Univ., DeKalb, IL (United States); Shiltsev, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Sun, Y. E. [Argonne National Lab. (ANL), Argonne, IL (United States); Valishev, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2013-10-01

Fermilab is the nation’s particle physics laboratory, supported by the DOE Office of High Energy Physics (OHEP). Fermilab is a world leader in accelerators, with a demonstrated track-record— spanning four decades—of excellence in accelerator science and technology. We describe the significant opportunity to complete, in a highly leveraged manner, a unique accelerator research facility that supports the broad strategic goals in accelerator science and technology within the OHEP. While the US accelerator-based HEP program is oriented toward the Intensity Frontier, which requires modern superconducting linear accelerators and advanced highintensity storage rings, there are no accelerator test facilities that support the accelerator science of the Intensity Frontier. Further, nearly all proposed future accelerators for Discovery Science will rely on superconducting radiofrequency (SRF) acceleration, yet there are no dedicated test facilities to study SRF capabilities for beam acceleration and manipulation in prototypic conditions. Finally, there are a wide range of experiments and research programs beyond particle physics that require the unique beam parameters that will only be available at Fermilab’s Advanced Superconducting Test Accelerator (ASTA). To address these needs we submit this proposal for an Accelerator R&D User Facility at ASTA. The ASTA program is based on the capability provided by an SRF linac (which provides electron beams from 50 MeV to nearly 1 GeV) and a small storage ring (with the ability to store either electrons or protons) to enable a broad range of beam-based experiments to study fundamental limitations to beam intensity and to develop transformative approaches to particle-beam generation, acceleration and manipulation which cannot be done elsewhere. It will also establish a unique resource for R&D towards Energy Frontier facilities and a test-bed for SRF accelerators and high brightness beam applications in support of the OHEP

Blue lighting accelerates post-stress relaxation: Results of a preliminary study.

Science.gov (United States)

Minguillon, Jesus; Lopez-Gordo, Miguel Angel; Renedo-Criado, Diego A; Sanchez-Carrion, Maria Jose; Pelayo, Francisco

2017-01-01

Several authors have studied the influence of light on both human physiology and emotions. Blue light has been proved to reduce sleepiness by suppression of melatonin secretion and it is also present in many emotion-related studies. Most of these have a common lack of objective methodology since results and conclusions are based on subjective perception of emotions. The aim of this work was the objective assessment of the effect of blue lighting in post-stress relaxation, in comparison with white lighting, by means of bio-signals and standardized procedures. We conducted a study in which twelve healthy volunteers were stressed and then performed a relaxation session within a chromotherapy room with blue (test group) or white (control group) lighting. We conclude that the blue lighting accelerates the relaxation process after stress in comparison with conventional white lighting. The relaxation time decreased by approximately three-fold (1.1 vs. 3.5 minutes). We also observed a convergence time (3.5-5 minutes) after which the advantage of blue lighting disappeared. This supports the relationship between color of light and stress, and the observations reported in previous works. These findings could be useful in clinical and educational environments, as well as in daily-life context and emerging technologies such as neuromarketing. However, our study must be extended to draw reliable conclusions and solid scientific evidence.

Blue lighting accelerates post-stress relaxation: Results of a preliminary study.

Directory of Open Access Journals (Sweden)

Jesus Minguillon

Full Text Available Several authors have studied the influence of light on both human physiology and emotions. Blue light has been proved to reduce sleepiness by suppression of melatonin secretion and it is also present in many emotion-related studies. Most of these have a common lack of objective methodology since results and conclusions are based on subjective perception of emotions. The aim of this work was the objective assessment of the effect of blue lighting in post-stress relaxation, in comparison with white lighting, by means of bio-signals and standardized procedures. We conducted a study in which twelve healthy volunteers were stressed and then performed a relaxation session within a chromotherapy room with blue (test group or white (control group lighting. We conclude that the blue lighting accelerates the relaxation process after stress in comparison with conventional white lighting. The relaxation time decreased by approximately three-fold (1.1 vs. 3.5 minutes. We also observed a convergence time (3.5-5 minutes after which the advantage of blue lighting disappeared. This supports the relationship between color of light and stress, and the observations reported in previous works. These findings could be useful in clinical and educational environments, as well as in daily-life context and emerging technologies such as neuromarketing. However, our study must be extended to draw reliable conclusions and solid scientific evidence.

Design and test of a new MITL for the Yang accelerator

International Nuclear Information System (INIS)

Song Shengyi; Gu Yuanchao; Zhou Rongguo; Wei Bing; Han Wenhui; Yang Liang; Wang Xiong; Xie Weiping

2005-01-01

In this paper the physical design and test of a new MITL for the Yang accelerator have been introduced. With reducing the total length of the MITL and width of the insulator, the common-vertex-coaxial-circular-cones-like MITL has been employed to displace the old one, resulting in the decrease of structural inductance from 70.9 nH of the old to 31.7 nH of the new, and electrical stress criterion for some special locations has also been satisfied by reiteration and modification, and minimum magnetic current has been kept below that of the old. The tests both with short load and wire array load have shown that the performance of the new MITL was improved. (authors)

High-voltage terminal test of a test stand for a 1-MV electrostatic accelerator

Science.gov (United States)

Park, Sae-Hoon; Kim, Yu-Seok

2015-10-01

The Korea Multipurpose Accelerator Complex has been developing a 300-kV test stand for a 1-MV electrostatic accelerator ion source. The ion source and accelerating tube will be installed in a high-pressure vessel. The ion source in the high-pressure vessel is required to have a high reliability. The test stand has been proposed and developed to confirm the stable operating conditions of the ion source. The ion source will be tested at the test stand to verify the long-time operating conditions. The test stand comprises a 300-kV high-voltage terminal, a battery for the ion-source power, a 60-Hz inverter, 200-MHz radio-frequency power supply, a 5-kV extraction power supply, a 300-kV accelerating tube, and a vacuum system. The results of the 300-kV high-voltage terminal tests are presented in this paper.

The Use of Conditional Probability Integral Transformation Method for Testing Accelerated Failure Time Models

Directory of Open Access Journals (Sweden)

Abdalla Ahmed Abdel-Ghaly

2016-06-01

Full Text Available This paper suggests the use of the conditional probability integral transformation (CPIT method as a goodness of fit (GOF technique in the field of accelerated life testing (ALT, specifically for validating the underlying distributional assumption in accelerated failure time (AFT model. The method is based on transforming the data into independent and identically distributed (i.i.d Uniform (0, 1 random variables and then applying the modified Watson statistic to test the uniformity of the transformed random variables. This technique is used to validate each of the exponential, Weibull and lognormal distributions' assumptions in AFT model under constant stress and complete sampling. The performance of the CPIT method is investigated via a simulation study. It is concluded that this method performs well in case of exponential and lognormal distributions. Finally, a real life example is provided to illustrate the application of the proposed procedure.

Accelerated Testing Of Photothermal Degradation Of Polymers

Science.gov (United States)

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

1989-01-01

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

Temperature rise and stress induced by microcracks in accelerating structures

Directory of Open Access Journals (Sweden)

W. Zhu

2010-12-01

Full Text Available The temperature rise and induced stress due to Ohmic heating in the vicinity of microcracks on the walls of high-gradient accelerating structures are considered. The temperature rise and induced stress depend on the orientation of the crack with respect to the rf magnetic field, the shape of the crack, and the power and duration of the rf pulse. Under certain conditions the presence of cracks can double the temperature rise over that of a smooth surface. Stress at the bottom of the cracks can be several times larger than that of the case when there are no cracks. We study these effects both analytically and by computer simulation. It is shown that the stress in cracks is maximal when the crack depth is on the order of the thermal penetration depth.

Development of a 20 MeV Dielectric-Loaded Test Accelerator

International Nuclear Information System (INIS)

Gold, Steven H.; Fliflet, Arne W.; Lombardi, Marcie; Kinkead, Allen K.; Gai, Wei; Power, John G.; Konecny, Richard; Long, Jidong; Jing, Chunguang; Tantawi, Sami G.; Nantista, Christopher D.; Bruce, Ralph W.; Lewis, David III

2006-01-01

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 ∼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 ∼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

Timescale Correlation between Marine Atmospheric Exposure and Accelerated Corrosion Testing

Science.gov (United States)

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

2011-01-01

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

Reliability data collection on IC and VLSI devices tested under accelerated life conditions

International Nuclear Information System (INIS)

Barry, D.M.; Meniconi, M.

1986-01-01

As part of a more general investigation into the reliability and failure causes of semiconductor devices, statistical samples of integrated circuit devices (LM741C) and dynamic random access memory devices (TMS4116) were tested destructively to failure using elevated temperature as the accelerating stress. The devices were operated during the life test and the failure data generated were collected automatically using a multiple question-and-answer program and a process control computer. The failure data were modelled from the lognormal, inverse Gaussian and Weibull distribution using an Arrhenius reaction rate model. The failed devices were later decapsulated for failure cause determination. (orig./DG)

Dysregulated physiological stress systems and accelerated cellular aging.

Science.gov (United States)

Révész, Dóra; Verhoeven, Josine E; Milaneschi, Yuri; de Geus, Eco J C N; Wolkowitz, Owen M; Penninx, Brenda W J H

2014-06-01

Exposure to chronic stressors is associated with accelerated biological aging as indicated by reduced leukocyte telomere length (LTL). This impact could be because of chronic overactivation of the body's physiological stress systems. This study examined the associations between LTL and the immune system, hypothalamic-pituitary-adrenal axis and autonomic nervous system. LTL was assessed in 2936 adults from the Netherlands Study of Depression and Anxiety. Inflammation markers (interleukin-6, c-reactive protein, tumor necrosis factor-alpha), hypothalamic-pituitary-adrenal-axis indicators (salivary cortisol awakening curve [area under the curve indicators, with respect to the ground and increase], evening levels, 0.5 mg dexamethasone cortisol suppression ratio), and autonomic nervous system measures (heart rate, respiratory sinus arrhythmia, pre-ejection period) were determined. Linear regression analyses were performed and adjusted for sociodemographic, lifestyle and clinical factors. Shorter LTL was significantly associated with higher c-reactive protein, interleukin-6, area under the curve with respect to increase, and heart rate. A cumulative index score was calculated based on the number of highest tertiles of these 4 stress markers. LTL demonstrated a significant gradient within subjects ranging from having zero (5528 base pairs) to having 4 elevated stress markers (5371 base pairs, p for trend = 0.002), corresponding to a difference of 10 years of accelerated biological aging. Contrary to the expectations, shorter LTL was also associated with longer pre-ejection period, indicating lower sympathetic tone. This large-scale study showed that inflammation, high awakening cortisol response, and increased heart rate are associated with shorter LTL, especially when they are dysregulated cumulatively. Copyright © 2014 Elsevier Inc. All rights reserved.

Accelerated Testing with Multiple Failure Modes under Several Temperature Conditions

Directory of Open Access Journals (Sweden)

Zongyue Yu

2014-01-01

Full Text Available A complicated device may have multiple failure modes, and some of the failure modes are sensitive to low temperatures. To assess the reliability of a product with multiple failure modes, this paper presents an accelerated testing in which both of the high temperatures and the low temperatures are applied. Firstly, an acceleration model based on the Arrhenius model but accounting for the influence of both the high temperatures and low temperatures is proposed. Accordingly, an accelerated testing plan including both the high temperatures and low temperatures is designed, and a statistical analysis method is developed. The reliability function of the product with multiple failure modes under variable working conditions is given by the proposed statistical analysis method. Finally, a numerical example is studied to illustrate the proposed accelerated testing. The results show that the proposed accelerated testing is rather efficient.

Effect of initial longitudinal stresses on the linearity of the shape rolled products after accelerated cooling

International Nuclear Information System (INIS)

Shetulov, D.I.

1991-01-01

Consideration is given to results of investigation into effect of initial longitudinal stresses on the linearity of the shaped rolled products after accelerated cooling. Particular attention is placed on the influence of an initial stresses state of material on qualiti of heat-treated rolled products. Effect of stresses state of worked material residual bending is studed by the use of computerized simulation.Theoretical analysis of stress-strain state of shape hot-rolled products during accelerated cooling after finishing stand of rolls is developed. A residual stress-strain state of material does not affected by rolling stresses when using a rautine cooling device with rigid centering of the product under rolling. It is expected that the effect of initial stresses could be significant in the absence of a limitator for bending deformation of shaped product longitudinal axis

Accelerators for Society - TIARA 2012 Test Infrastructure and Accelerator Research Area (in Polish)

CERN Document Server

Romaniuk, R S

2013-01-01

TIARA (Test Infrastructure and Accelerator Research Area - Preparatory Phae) is an European Collaboration of Accelerator Technology, which by running research projects, technical, networks and infrastructural has a duty to integrate the research and technical communities and infrastructures in the global scale of Europe. The Collaboration gathers all research centers with large accelerator infrastructures. Other ones, like universities, are affiliated as associate members. TIARA-PP (preparatory phase) is an European infrastructural project run by this Consortium and realized inside EU-FP7. The paper presents a general overview of TIARA activities, with an introduction containing a portrait of contemporary accelerator technology and a digest of its applications in modern society.

Development of a 20 MeV Dielectric-Loaded Accelerator Test Facility

International Nuclear Information System (INIS)

Gold, Steven H.; Fliflet, Arne W.; Kinkead, Allen K.; Gai Wei; Power, John G.; Konecny, Richard; Jing Chunguang; Tantawi, Sami G.; Nantista, Christopher D.; Hu, Y.; Chen, H.; Tang, C.; Lin, Y.; Bruce, Ralph W.; Bruce, Robert L.; Lewis, David III

2004-01-01

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

Operation of the graded-β electron test accelerator

International Nuclear Information System (INIS)

Fraser, J.S.; McKeown, J.; McMichael, G.E.; Diamond, W.T.

1976-01-01

The Electron Test Accelerator has been built to model the behaviour of the high energy portion of a proton linear accelerator which would be suitable for breeding fissile material. The test accelerator and its control systems have been tested at 100% duty factor producing a beam of electrons at 1.5 MeV and currents up to 20 mA where the incident rf power is shared equally between the structure dissipation and the beam loading. The structure has performed satisfactorily in all respects at dissipation power densities up to 5 kW/cell where the mean energy gradient was 1.1 MeV/m. Experiments have been done on the beam loading effects in the coupling of the transmission line to the cavity, the amplitude depression in and phase tilt along the structure, and the phase lag of the structure field. The phase acceptance, the variation of transmission with buncher-accelerator phase shift and the beam energy spread are in qualitative agreement with beam dynamics calculations. (author)

RHIC sextant test: Accelerator systems and performance

Energy Technology Data Exchange (ETDEWEB)

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

1997-08-01

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.

RHIC sextant test: Accelerator systems and performance

International Nuclear Information System (INIS)

Pilat, F.; Trbojevic, D.; Ahrens, L.

1997-01-01

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

Optimizing conditions for an accelerated leach test

International Nuclear Information System (INIS)

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

1988-01-01

An accelerated leach test for low-level radioactive waste forms is being developed to provide, in a short time, data that can be extrapolated to long time periods. The approach is to provide experimental conditions that will accelerate leaching without changing the dominant release mechanism. Experimental efforts have focused on combining individual factors that have been observed to accelerate leaching. These include elevated temperature, increased leachant volume, and reduced specimen size. The response of diffusion coefficients to various acceleration factors have been evaluated and provide information on experimental parameters that need to be optimized to increase leach rates. Preliminary modeling using a diffusion mechanism (allowing for depletion) of a finite cylinder geometry indicates that during early portions of experiments (daily sampling intervals), leaching is diffusion controlled and more rapid than later in the same experiments (weekly or greater sampling intervals). For cement waste forms, this reduction in rate may be partially controlled by changes in physical structure and chemistry (sometimes related to environmental influences such as CO 2 ), but it is more likely associated with the duration of the sampling interval. By using a combination of mathematical modeling and by experimentally investigating various leach rate controlling factors, a more complete understanding of leaching processes is being developed. This, in turn, is leading to optimized accelerating conditions for a leach test

Quick setup of test unit for accelerator control system

International Nuclear Information System (INIS)

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

2011-01-01

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.

Accelerated testing of composites

Science.gov (United States)

Papazian, H. A.

1983-01-01

It is shown that the Zhurkov method for testing the strength of solids can be applied to dynamic tension and to cyclic loading and provides a viable approach to accelerated testing of composites. Data from the literature are used to demonstrate a straightforward application of the method to dynamic tension of glass fiber and cyclic loading for glass/polymer, metal matrix, and graphite/epoxy composites. Zhurkov's equation can be used at relatively high loads to obtain failure times at any temperature of interest. By taking a few data points at one or two other temperatures the spectrum of failure times can be expanded to temperatures not easily accessible.

Increased rate of acceleration on Pine Island Glacier strongly coupled to changes in gravitational driving stress

Directory of Open Access Journals (Sweden)

J. B. T. Scott

2009-05-01

Full Text Available Pine Island Glacier, Antarctica, has been undergoing several related changes for at least two decades; these include acceleration, thinning and grounding line retreat. During the first major ground-based study between 2006 and 2008, GPS receivers were used to monitor ice flow from 55 km to 171 km inland, along the central flowline. At four sites both acceleration and thinning rates over the last two years exceeded rates observed at any other time over the last two decades. At the downstream site acceleration was 6.4% over 2007 and thinning was 3.5±0.5 ma⁻¹. Acceleration and thinning have spread rapidly inland with the acceleration 171 km inland at 4.1% over 2007, greater than any measured annual flow increase along the whole glacier prior to 2006. Increases in surface slope, and hence gravitational driving stress, correlate well with the acceleration and no sustained change in longitudinal stress gradient is needed to explain the force balance. There is no indication that the glacier is approaching a new steady state.

Accelerated Aging Test for Plastic Scintillator Gamma Ray Detectors

Energy Technology Data Exchange (ETDEWEB)

Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-05-12

Polyvinyl toluene (PVT) and polystyrene (PS), collectively referred to as “plastic scintillator,” are synthetic polymer materials used to detect gamma radiation, and are commonly used in instrumentation. Recent studies have revealed that plastic scintillator undergoes an environmentally related material degradation that adversely affects performance under certain conditions and histories. A significant decrease in gamma ray sensitivity has been seen in some detectors in systems as they age. The degradation of sensitivity of plastic scintillator over time is due to a variety of factors, and the term “aging” is used to encompass all factors. Some plastic scintillator samples show no aging effects (no significant change in sensitivity over more than 10 years), while others show severe aging (significant change in sensitivity in less than 5 years). Aging effects arise from weather (variations in heat and humidity), chemical exposure, mechanical stress, light exposure, and loss of volatile components. The damage produced by these various causes can be cumulative, causing observable damage to increase over time. Damage may be reversible up to some point, but becomes permanent under some conditions. It has been demonstrated that exposure of plastic scintillator in an environmental chamber to 30 days of high temperature and humidity (90% relative humidity and 55°C) followed by a single cycle to cold temperature (-30°C) will produce severe fogging in all PVT samples. This thermal cycle will be referred to as the “Accelerated Aging Test.” This document describes the procedure for performing this Accelerated Aging Test.

Accelerated Leach Test(s) Program. Annual report

International Nuclear Information System (INIS)

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

1985-09-01

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

Standard Operating Procedure for Accelerated Corrosion Testing at ARL

Science.gov (United States)

2017-11-01

ARL-TN-0855 ● NOV 2017 US Army Research Laboratory Standard Operating Procedure for Accelerated Corrosion Testing at ARL by... Corrosion Testing at ARL by Thomas A Considine Weapons and Materials Research Directorate, ARL Approved for public...November 2017 2. REPORT TYPE Technical Note 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Standard Operating Procedure for Accelerated

High gradient test of X-band accelerating structure at GLCTA

International Nuclear Information System (INIS)

Watanabe, K.; Higo, T.; Hayano, H.; Terunuma, N.; Saeki, T.; Kudo, N.; Sanuki, T.; Seuhara, T.

2004-01-01

GLCTA (Global Linear Collider Test Accelerator) is the high power test facility for X-band acceleration. We have installed an X-band 60cm structure in April 2004 and have been processing it for more than 3 months. Now it is under test on long-term operation. We report here the installation process and high power test result to date. (author)

Advanced Beamline Design for Fermilab's Advanced Superconducting Test Accelerator

Energy Technology Data Exchange (ETDEWEB)

Prokop, Christopher [Northern Illinois Univ., DeKalb, IL (United States)

2014-01-01

The Advanced Superconducting Test Accelerator (ASTA) at Fermilab is a new electron accelerator currently in the commissioning stage. In addition to testing superconducting accelerating cavities for future accelerators, it is foreseen to support a variety of Advanced Accelerator R&D (AARD) experiments. Producing the required electron bunches with the expected flexibility is challenging. The goal of this dissertation is to explore via numerical simulations new accelerator beamlines that can enable the advanced manipulation of electron bunches. The work especially includes the design of a low-energy bunch compressor and a study of transverse-to-longitudinal phase space exchangers.

NLC. A test accelerator for the next linear collider

International Nuclear Information System (INIS)

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

1993-01-01

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

Panel manipulation in social stress testing: The Bath Experimental Stress Test for Children (BEST-C).

Science.gov (United States)

Cheetham, Tara J; Turner-Cobb, Julie M

2016-01-01

Whilst acute stress paradigms in adults make use of adult panel members, similar paradigms modified for child participants have not manipulated the panel. Most work has utilised an audience of adult confederates, regardless of the age of the population being tested. The aim of this study was to trial a social stress test for children that provided a meaningful environment using age-matched child peers as panel actors. Thirty-three participants (7-11 years) underwent the Bath Experimental Stress Test for Children (BEST-C). Based on the Trier Social Stress Test (TSST), it comprises a shortened six-minute public speaking task and four-minute maths challenge. It differs from previous stress tests by using age-matched children on the panel, pre-recorded and presented as a live feed, and includes an expanded manipulation check of subjective experience. Salivary cortisol was assessed at four time points, pre-post stress testing; life events, daily hassles and coping strategies were measured through questionnaires. A simple numerical coding scheme was applied to post-test interview data. The BEST-C generated a typical stress and adaptation response in salivary cortisol (p=.032). Age and gender differences were observed during recovery. Cortisol responses mapped directly onto three distinct subjective response patterns: (i) expected response and recovery; (ii) expected response, no recovery; (iii) no response. The BEST-C, utilising child confederates of participant target age is a meaningful social stress test for children. This is the first social stress test developed specifically for children that manipulates panel characteristics by using child confederates and a pre-recorded sham panel. Greater cortisol responses to the test were also found to match subjective verbal accounts of the experience. It offers a meaningful acute stress paradigm with potential applications to other child and adolescent age groups. Furthermore, it leads the way in the use of panel manipulation

Operation of the Brookhaven National Laboratory Accelerator Test Facility

International Nuclear Information System (INIS)

Batchelor, K.; Ben-Zvi, I.; Botke, I.; Chou, T.S.; Fernow, R.; Fischer, J.; Fisher, A.; Gallardo, J.; Ingold, G.; Malone, R.; Palmer, R.; Parsa, Z.; Pogorelsky, I.; Rogers, J.; Sheehan, J.; Srinivasan-Rao, T.; Tsang, T.; Ulc, S.; van Steenbergen, A.; Wang, X.J.; Woodle, M.; Yu, L.H.

1992-01-01

Early operation of the 50 MeV high brightness electron linac of the Accelerator Test Facility is described along with experimental data. This facility is designed to study new linear acceleration techniques and new radiation sources based on linacs in combination with free electron lasers. The accelerator utilizes a photo-excited, metal cathode, radio frequency electron gun followed by two travelling wave accelerating sections and an Experimental Hall for the study program

Some problems in the technique of high-voltage testing of the accelerating tube gaps in electrostatic accelerators

International Nuclear Information System (INIS)

Romanov, V.A.; Ivanov, V.V.; Mukhametshin, V.I.; Dmitriev, E.P.; Kidalov, A.I.

1983-01-01

Problems arising during high-voltage testing and training of accelerating taubes of electrostatic accelrators are discussed. A rig and technique of the accelerating tube testing and program designed for the processing of the data obtained and sorting out of the samples investigated are described

Methodology to improve design of accelerated life tests in civil engineering projects.

Directory of Open Access Journals (Sweden)

Jing Lin

Full Text Available 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.

Methodology to improve design of accelerated life tests in civil engineering projects.

Science.gov (United States)

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

2014-01-01

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.

Vacuum system for Advanced Test Accelerator

International Nuclear Information System (INIS)

Denhoy, B.S.

1981-01-01

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

Vacuum system for Advanced Test Accelerator

Energy Technology Data Exchange (ETDEWEB)

Denhoy, B.S.

1981-09-03

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

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

Science.gov (United States)

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

2009-01-01

Composite Overwrapped Pressure Vessels (COPVs) that have survived a long service time under pressure generally must be recertified before service is extended. Flight certification is dependent on the reliability analysis to quantify the risk of stress rupture failure in existing flight vessels. Full certification of this reliability model would require a statistically significant number of lifetime tests to be performed and is impractical given the cost and limited flight hardware for certification testing purposes. One approach to confirm the reliability model is to perform a stress rupture test on a flight COPV. Currently, testing of such a Kevlar49 (Dupont)/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 database 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 model 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 predicted 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 vessels would be necessary.

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

Science.gov (United States)

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

2015-01-01

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.

77 FR 3408 - Annual Stress Test

Science.gov (United States)

2012-01-24

...-2011-0029] RIN 1557-AD58 Annual Stress Test AGENCY: Office of the Comptroller of the Currency (``OCC... certain companies to conduct annual stress tests pursuant to regulations prescribed by their respective... stress test as prescribed by this proposed rule. In addition to the annual stress test requirement, such...

Operation of the Brookhaven national laboratory accelerator test facility

International Nuclear Information System (INIS)

Batchelor, K.; Ben-Zvi, I.; Botke, I.; Chou, T.S.; Fernow, R.; Fischer, J.; Fisher, A.; Gallardo, J.; Ingold, G.; Malone, R.; Palmer, R.; Parsa, Z.; Pogorelsky, I.; Rogers, J.; Sheehan, J.; Srinivasan-Rao, T.; Tsang, T.; Ulc, S.; Van Steenbergen, A.; Wang, X.J.; Woodle, M.; Yu, L.H.

1992-01-01

Early operation of the 50 MeV high brightness electron linac of the Accelerator Test Facility is described along with experimental data. This facility is designed to study new linear acceleration techniques and new radiation sources based on linacs in combination with free electron lasers. The accelerator utilizes a photo-excited, metal cathode, radio frequency electron gun followed by two travelling wave accelerating sections and an Experimental Hall for the study program. (Author) 5 refs., 4 figs., tab

Accelerated fatigue testing of dentin-composite bond with continuously increasing load.

Science.gov (United States)

Li, Kai; Guo, Jiawen; Li, Yuping; Heo, Young Cheul; Chen, Jihua; Xin, Haitao; Fok, Alex

2017-06-01

The aim of this study was to evaluate an accelerated fatigue test method that used a continuously increasing load for testing the dentin-composite bond strength. Dentin-composite disks (ϕ5mm×2mm) made from bovine incisor roots were subjected to cyclic diametral compression with a continuously increasingly load amplitude. Two different load profiles, linear and nonlinear with respect to the number of cycles, were considered. The data were then analyzed by using a probabilistic failure model based on the Weakest-Link Theory and the classical stress-life function, before being transformed to simulate clinical data of direct restorations. All the experimental data could be well fitted with a 2-parameter Weibull function. However, a calibration was required for the effective stress amplitude to account for the difference between static and cyclic loading. Good agreement was then obtained between theory and experiments for both load profiles. The in vitro model also successfully simulated the clinical data. The method presented will allow tooth-composite interfacial fatigue parameters to be determined more efficiently. With suitable calibration, the in vitro model can also be used to assess composite systems in a more clinically relevant manner. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A 1MeV, 1A negative ion accelerator test facility

International Nuclear Information System (INIS)

Hanada, M.; Dairaku, M.; Inoue, T.; Miyamoto, K.; Ohara, Y.; Okumura, Y.; Watanabe, K.; Yokoyama, K.

1995-01-01

For the Proof-of-Principle test of negative ion acceleration up to 1 MeV, the beam energy required for ITER, a negative ion test facility named MeV Test Facility (MTF) and an ion source/accelerator have been designed and constructed. They are designed to produce a 1 MeV H- beam at a low source pressure of 0.13Pa. The MTF has a power supply system, which constituts of a 1MV, 1A, 60 s Cockcroft-Walton type dc high energy generator and power supplies for negative ion generation and extraction (ion source power supplies). The negative ion source/accelerator is composed of a cesiated volume source and a 5-stage, multi-aperture, electrostatic accelerator. The MTF and the ion source/accelerator have been completed, and the accelertion test up to 1 MeV of the H- ions has started. (orig.)

A test accelerator for the next linear collider

International Nuclear Information System (INIS)

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

1993-07-01

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

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

International Nuclear Information System (INIS)

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

2012-01-01

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.

Pad stress tests with increasing load for the diagnosis of stress urinary incontinence.

Science.gov (United States)

Rimstad, Liv; Larsen, Elsa Skjønhaug; Schiøtz, Hjalmar A; Kulseng-Hanssen, Sigurd

2014-09-01

The aim of the study was to test the ability of pad stress tests with increasing load (supine, jumping on the floor, and jumping on a trampoline) to document stress incontinence in subjectively stress incontinent women. In this prospective study 147 subjectively stress and mixed incontinent women performed consecutively the three pad stress tests with a bladder volume of 300 ml. Nineteen women performed a second trampoline pad stress test to test repeatability of the test. Nine continent women performed a trampoline pad stress test in order to determine if subjectively continent women would leak during the test. Seventy-two women (49%) leaked during the supine, 136 (93%) leaked during the jumping, and 146 (99%) leaked during the trampoline pad stress test. The differences between pad stress tests were significant with P trampoline pad stress tests was high at 0.8. None of the nine continent women leaked during the trampoline pad stress test. The supine pad stress test has low sensitivity and is therefore often falsely negative. The jumping pad stress test is a simple test to perform and is satisfactory for everyday use. Subjectively stress incontinent women who do not leak during the jumping pad stress test may perform a trampoline pad stress test to document stress incontinence. The trampoline pad stress test is also simple to perform and detected leakage in 91% of the women who did not leak during the jumping pad stress test. © 2013 Wiley Periodicals, Inc.

Obesity-induced oxidative stress, accelerated functional decline with age and increased mortality in mice.

Science.gov (United States)

Zhang, Yiqiang; Fischer, Kathleen E; Soto, Vanessa; Liu, Yuhong; Sosnowska, Danuta; Richardson, Arlan; Salmon, Adam B

2015-06-15

Obesity is a serious chronic disease that increases the risk of numerous co-morbidities including metabolic syndrome, cardiovascular disease and cancer as well as increases risk of mortality, leading some to suggest this condition represents accelerated aging. Obesity is associated with significant increases in oxidative stress in vivo and, despite the well-explored relationship between oxidative stress and aging, the role this plays in the increased mortality of obese subjects remains an unanswered question. Here, we addressed this by undertaking a comprehensive, longitudinal study of a group of high fat-fed obese mice and assessed both their changes in oxidative stress and in their performance in physiological assays known to decline with aging. In female C57BL/6J mice fed a high-fat diet starting in adulthood, mortality was significantly increased as was oxidative damage in vivo. High fat-feeding significantly accelerated the decline in performance in several assays, including activity, gait, and rotarod. However, we also found that obesity had little effect on other markers of function and actually improved performance in grip strength, a marker of muscular function. Together, this first comprehensive assessment of longitudinal, functional changes in high fat-fed mice suggests that obesity may induce segmental acceleration of some of the aging process. Published by Elsevier Inc.

The electron test accelerator safety in design and operation

International Nuclear Information System (INIS)

McKeown, J.

1980-06-01

The Electron Test Accelerator is being designed as an experiment in accelerator physics and technology. With an electron beam power of up to 200 kW the operation of the accelerator presents a severe radiation hazard as well as rf and electrical hazards. The design of the safety system provides fail-safe protection while permitting flexibility in the mode of operation and minimizing administrative controls. (auth)

A bandwidth correction to the Allegri-Zhang solution for accelerated random vibration testing

Directory of Open Access Journals (Sweden)

Benasciutti Denis

2018-01-01

Full Text Available In 2008, Allegri and Zhang published a study [Int. J. Fatigue. 2008, 30(6:967-977] in which they provided an exact analytical solution to the inverse scaling law for accelerated vibration tests of linear systems submitted to stationary Gaussian excitations By combining finite element analysis with multiaxial spectral methods defined in the frequency-domain, their solution generalised the simple inverse power law model suggested in some standards. The solution adopted the “equivalent von Mises stress” multiaxial criterion combined with the narrow-band damage expression. This work aims to propose a bandwidth correction to the original Allegri-Zhang solution to account for the actual spectral banwidth of the local multiaxial stress. The corrected Allegri-Zhang solution is also extended to another multiaxial spectral method, namely the “Projection-by-Projection” criterion. A numerical example is finally discussed, in which the corrected solution is applied to an L-shaped beam submitted to random accelerations.

An accelerated test method for efflorescence in clay bricks

International Nuclear Information System (INIS)

Beggan, John Edward

1998-01-01

An investigation into the creation of accelerated efflorescence in clay bricks was undertaken with a view to creating a viable test procedure for determining efflorescence potential. The testing programme incorporated ambient conditions similar to those which promote efflorescence growth in bricks in use. Theoretical investigations into the physical mechanism underlying the creation of efflorescence directed the attempts to accelerate the process. It was found that calcium sulphate efflorescence could not be sufficiently accelerated such that a useful efflorescence test procedure could be proposed. The inability to produce accelerated efflorescence in brick samples was attributed to limitations associated with time dependent salt diffusion in the efflorescence mechanism. The preliminary testing that was undertaken into the creation of efflorescence prompted the use of acid assisted methods to accelerate efflorescence. The acid assisted method that was adopted to provide a possible indication of efflorescence potential relies upon the transformation of low solubility calcium to a more soluble form. The movement of the transformed salt is then induced by cyclic temperature exposure at temperatures similar to those experienced in Spring. The appearance of the transformed calcium salt on the surface of the brick specimen provides an indication of the efflorescence potential. Brick piers constructed on an exposed site and monitored over a 12 month period provided information on the validity of the acid assisted test method. The efflorescence observed on the piers correlated well with that predicted by the acid assisted test, suggesting that the new test has the potential to accurately predict the efflorescence potential of clay bricks Relationships between other properties such as air permeability, sorptivity and tensile strength were investigated such that an alternative method of predicting efflorescence could be achieved. It was found that (within the bounds of the

Nuclear-waste-package materials degradation modes and accelerated testing

International Nuclear Information System (INIS)

1981-09-01

This report reviews the materials degradation modes that may affect the long-term behavior of waste packages for the containment of nuclear waste. It recommends an approach to accelerated testing that can lead to the qualification of waste package materials in specific repository environments in times that are short relative to the time period over which the waste package is expected to provide containment. This report is not a testing plan but rather discusses the direction for research that might be considered in developing plans for accelerated testing of waste package materials and waste forms

Accelerated Test Method for Corrosion Protective Coatings

Data.gov (United States)

National Aeronautics and Space Administration — This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as...

Accelerated pavement testing of low-volume paved roads with geocell reinforcement.

Science.gov (United States)

2015-03-01

The Midwest States Accelerated Pavement Testing Pooled-Fund Program, financed by the highway : departments of Kansas, Iowa, Missouri, and New York, has supported an accelerated pavement testing (APT) project : to study the rehabilitation of low-volum...

Credibility and Crisis Stress Testing

Directory of Open Access Journals (Sweden)

Li Lian Ong

2014-02-01

Full Text Available Credibility is the bedrock of any crisis stress test. The use of stress tests to manage systemic risk was introduced by the U.S. authorities in 2009 in the form of the Supervisory Capital Assessment Program. Since then, supervisory authorities in other jurisdictions have also conducted similar exercises. In some of those cases, the design and implementation of certain elements of the framework have been criticized for their lack of credibility. This paper proposes a set of guidelines for constructing an effective crisis stress test. It combines financial markets impact studies of previous exercises with relevant case study information gleaned from those experiences to identify the key elements and to formulate their appropriate design. Pertinent concepts, issues and nuances particular to crisis stress testing are also discussed. The findings may be useful for country authorities seeking to include stress tests in their crisis management arsenal, as well as for the design of crisis programs.

Testing of a Plasmadynamic Hypervelocity Dust Accelerator

Science.gov (United States)

Ticos, Catalin M.; Wang, Zhehui; Dorf, Leonid A.; Wurden, G. A.

2006-10-01

A plasmadynamic accelerator for microparticles (or dust grains) has been designed, built and tested at Los Alamos National laboratory. The dust grains are expected to be accelerated to hypervelocities on the order of 1-30 km/s, depending on their size. The key components of the plasmadynamic accelerator are a coaxial plasma gun operated at 10 kV, a dust dispenser activated by a piezoelectric transducer, and power and remote-control systems. The coaxial plasma gun produces a high density (10^18 cm-3) and low temperature (˜ 1 eV) plasma in deuterium ejected by J x B forces, which provides drag on the dust particles in its path. Carbon dust particles will be used, with diameters from 1 to 50 μm. The plasma parameters produced in the coaxial gun are presented and their implication to dust acceleration is discussed. High speed dust will be injected in the National Spherical Torus Experiment to measure the pitch angle of magnetic field lines.

Manufacturing and Testing of Accelerator Superconducting Magnets

CERN Document Server

Rossi, L

2014-01-01

Manufacturing of superconducting magnet for accelerators is a quite complex process that is not yet fully industrialized. In this paper, after a short history of the evolution of the magnet design and construction, we review the main characteristics of the accelerator magnets having an impact on the construction technology. We put in evidence how the design and component quality impact on construction and why the final product calls for a total-quality approach. LHC experience is widely discussed and main lessons are spelled out. Then the new Nb$_{3}$Sn technology, under development for the next generation magnet construction, is outlined. Finally, we briefly review the testing procedure of accelerator superconducting magnets, underlining the close connection with the design validation and with the manufacturing process.

Manufacturing and Testing of Accelerator Superconducting Magnets

International Nuclear Information System (INIS)

Rossi, L

2014-01-01

Manufacturing of superconducting magnet for accelerators is a quite complex process that is not yet fully industrialized. In this paper, after a short history of the evolution of the magnet design and construction, we review the main characteristics of the accelerator magnets having an impact on the construction technology. We put in evidence how the design and component quality impact on construction and why the final product calls for a total-quality approach. LHC experience is widely discussed and main lessons are spelled out. Then the new Nb3Sn technology, under development for the next generation magnet construction, is outlined. Finally, we briefly review the testing procedure of accelerator superconducting magnets, underlining the close connection with the design validation and with the manufacturing process

Manufacturing and Testing of Accelerator Superconducting Magnets

Energy Technology Data Exchange (ETDEWEB)

Rossi, L [European Organization for Nuclear Research, Geneva (Switzerland)

2014-07-01

Manufacturing of superconducting magnet for accelerators is a quite complex process that is not yet fully industrialized. In this paper, after a short history of the evolution of the magnet design and construction, we review the main characteristics of the accelerator magnets having an impact on the construction technology. We put in evidence how the design and component quality impact on construction and why the final product calls for a total-quality approach. LHC experience is widely discussed and main lessons are spelled out. Then the new Nb3Sn technology, under development for the next generation magnet construction, is outlined. Finally, we briefly review the testing procedure of accelerator superconducting magnets, underlining the close connection with the design validation and with the manufacturing process.

The first acceleration test of polarized protons in KEK PS

International Nuclear Information System (INIS)

Hiramatsu, Shigenori; Sato, Hikaru; Toyama, Takeshi

1984-03-01

The outline of the polarized proton acceleration project at KEK and the results of the first acceleration test are described. Depolarization in the 500 MeV booster synchrotron was investigated as the first step of this program. The beam polarization was measured in the 20 MeV beam transport line from the linac to the booster and in the main ring at the injection energy. About 40 % of the linac beam polarization was kept in the main ring. This acceleration test encouraged us to proceed with this program. (author)

Accelerated Performance Testing on the 2006 NCAT Pavement Test Track

Science.gov (United States)

2009-12-01

The original National Center for Asphalt Technology (NCAT) Pavement Test Track was built in 2000 in Opelika, Alabama where it has served as a state-of-the-art, full-scale, closed-loop accelerated loading facility. The construction, operation, and res...

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

Science.gov (United States)

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

2012-01-01

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.

Cosmological consistency tests of gravity theory and cosmic acceleration

Science.gov (United States)

Ishak-Boushaki, Mustapha B.

2017-01-01

Testing general relativity at cosmological scales and probing the cause of cosmic acceleration are among the important objectives targeted by incoming and future astronomical surveys and experiments. I present our recent results on consistency tests that can provide insights about the underlying gravity theory and cosmic acceleration using cosmological data sets. We use statistical measures, the rate of cosmic expansion, the growth rate of large scale structure, and the physical consistency of these probes with one another.

Stress Corrosion Cracking of Steel and Aluminum in Sodium Hydroxide: Field Failure and Laboratory Test

Directory of Open Access Journals (Sweden)

Y. Prawoto

2012-01-01

Full Text Available Through an investigation of the field failure analysis and laboratory experiment, a study on (stress corrosion cracking SCC behavior of steel and aluminum was performed. All samples were extracted from known operating conditions from the field failures. Similar but accelerated laboratory test was subsequently conducted in such a way as to mimic the field failures. The crack depth and behavior of the SCC were then analyzed after the laboratory test and the mechanism of stress corrosion cracking was studied. The results show that for the same given stress relative to ultimate tensile strength, the susceptibility to SCC is greatly influenced by heat treatment. Furthermore, it was also concluded that when expressed relative to the (ultimate tensile strength UTS, aluminum has similar level of SCC susceptibility to that of steel, although with respect to the same absolute value of applied stress, aluminum is more susceptible to SCC in sodium hydroxide environment than steel.

The BNL Accelerator Test Facility and experimental program

International Nuclear Information System (INIS)

Ben-Zvi, I.; State Univ. of New York, Stony Brook, NY

1992-01-01

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 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

The BNL Accelerator Test Facility and experimental program

International Nuclear Information System (INIS)

Ben-Zvi, I.; State Univ. of New York, Stony Brook, NY

1991-01-01

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 to 100 MeV by two traveling wave accelerator sections. The lasers include a 10 mJ, 10 ps Nd:YAG laser and a 100 mJ, 10 ps CO 2 laser. A number of users from National Laboratories, universities and industry take part in experiments at the ATF. The experimental program includes various acceleration schemes, Free-Electron Laser experiments and a program on the development of high brightness electron beams. The AFT'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. 28 refs., 4 figs

Stress Tests and Vulnerability Assessment

Energy Technology Data Exchange (ETDEWEB)

Wallner, A. [Austrian Institute of Ecology, Vienna (Austria); Lorenz, P. [ed.; Becker, O. [eds.; Weber, U. [Austrian Institute of Ecology, Vienna (Austria)

2012-07-01

After the accident in Fukushima, nuclear safety as topic in anti-nuclear work has gained importance within the Joint Project countries. Therefore, nuclear safety and in particular the activities of the European stress tests were chosen to be the main focus of the Joint Project 2011/2012 as well as the common theme of the national projects. This brochure describes: A) Vulnerability Assessment A critical review of the EU Nuclear Stress Tests in Bulgaria, Hungary, Romania and Ukraine is presented in chapter 1. The review details the main weaknesses identified within the stress tests. Important shortcomings not mentioned in the stress tests reports are also discussed. These evaluations do not claim to be exhaustive, but the findings contribute to a more comprehensive understanding of safety and risk of nuclear power plants in Europe. B) Transparency of the stress tests In chapter 2 the experience of the Joint Project NGOs concerning transparency of the stress tests is presented. The information is not meant to be an evaluation of the transparency of the stress tests in general – such an evaluation is not possible within the scope of this brochure. The evaluation aims to show activities concerning stress tests and how they were conceived by the JP NGOs. Some recommendations for improvement are given. C) Safety focus Within the main topic “nuclear safety” of the Joint Project 2011/2012 the NGOs of each JP country selected a special safety relevant topic, which is/was of particular interest in their country: Bulgaria: The short story of Belene NPP – The victory – Key points of the campaign against the nuclear power plant Romania: Risks of the CANDU reactor design Czech Republic: Results of the conference “Power Plant Load Testing: Safety Inspection or Propaganda?“ Slovakia: Safety deficits of the NPP Mochovce These safety relevant issues are discussed in separate sections within the brochure at hand. (author)

Stress Tests and Vulnerability Assessment

International Nuclear Information System (INIS)

Wallner, A.; Lorenz, P.

2012-01-01

After the accident in Fukushima, nuclear safety as topic in anti-nuclear work has gained importance within the Joint Project countries. Therefore, nuclear safety and in particular the activities of the European stress tests were chosen to be the main focus of the Joint Project 2011/2012 as well as the common theme of the national projects. This brochure describes: A) Vulnerability Assessment A critical review of the EU Nuclear Stress Tests in Bulgaria, Hungary, Romania and Ukraine is presented in chapter 1. The review details the main weaknesses identified within the stress tests. Important shortcomings not mentioned in the stress tests reports are also discussed. These evaluations do not claim to be exhaustive, but the findings contribute to a more comprehensive understanding of safety and risk of nuclear power plants in Europe. B) Transparency of the stress tests In chapter 2 the experience of the Joint Project NGOs concerning transparency of the stress tests is presented. The information is not meant to be an evaluation of the transparency of the stress tests in general – such an evaluation is not possible within the scope of this brochure. The evaluation aims to show activities concerning stress tests and how they were conceived by the JP NGOs. Some recommendations for improvement are given. C) Safety focus Within the main topic “nuclear safety” of the Joint Project 2011/2012 the NGOs of each JP country selected a special safety relevant topic, which is/was of particular interest in their country: Bulgaria: The short story of Belene NPP – The victory – Key points of the campaign against the nuclear power plant Romania: Risks of the CANDU reactor design Czech Republic: Results of the conference “Power Plant Load Testing: Safety Inspection or Propaganda?“ Slovakia: Safety deficits of the NPP Mochovce These safety relevant issues are discussed in separate sections within the brochure at hand. (author)

Sequential accelerated tests: Improving the correlation of accelerated tests to module performance in the field

Science.gov (United States)

Felder, Thomas; Gambogi, William; Stika, Katherine; Yu, Bao-Ling; Bradley, Alex; Hu, Hongjie; Garreau-Iles, Lucie; Trout, T. John

2016-09-01

DuPont has been working steadily to develop accelerated backsheet tests that correlate with solar panels observations in the field. This report updates efforts in sequential testing. Single exposure tests are more commonly used and can be completed more quickly, and certain tests provide helpful predictions of certain backsheet failure modes. DuPont recommendations for single exposure tests are based on 25-year exposure levels for UV and humidity/temperature, and form a good basis for sequential test development. We recommend a sequential exposure of damp heat followed by UV then repetitions of thermal cycling and UVA. This sequence preserves 25-year exposure levels for humidity/temperature and UV, and correlates well with a large body of field observations. Measurements can be taken at intervals in the test, although the full test runs 10 months. A second, shorter sequential test based on damp heat and thermal cycling tests mechanical durability and correlates with loss of mechanical properties seen in the field. Ongoing work is directed toward shorter sequential tests that preserve good correlation to field data.

Accelerated storage testing of freeze-dried Pseudomonas ...

African Journals Online (AJOL)

Accelerated storage testing of freeze-dried Pseudomonas fluorescens BTP1, ... of all P. fluorescens strains were not significantly different and thermal inactivation ... useful to the development of improved reference materials and samples held ...

Ultra-accelerated natural sunlight exposure testing

Science.gov (United States)

Jorgensen, Gary J.; Bingham, Carl; Goggin, Rita; Lewandowski, Allan A.; Netter, Judy C.

2000-06-13

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

Test setup for accelerated test of high power IGBT modules with online monitoring of Vce and Vf voltage during converter operation

DEFF Research Database (Denmark)

de Vega, Angel Ruiz; Ghimire, Pramod; Pedersen, Kristian Bonderup

2014-01-01

Several accelerated test methods exist in order to study the failures mechanisms of the high power IGBT modules like temperature cycling test or power cycles based on DC current pulses. The main drawback is that the test conditions do not represent the real performance and stress conditions...... of the device in real application. The hypothesis is that ageing of power modules closer to real environment including cooling system, full dc-link voltage and continuous PWM operation could lead to more accurate study of failure mechanism. A new type of test setup is proposed, which can create different real...... load conditions like in the field. Furthermore, collector-emitter voltage (Vce) has been used as indicator of the wear-out of the high power IGBT module. The innovative monitoring system implemented in the test setup is capable of measure the Vce and forward voltage of the antiparallel diode (Vf...

Accelerated weathering of fire-retardant-treated wood for fire testing

Science.gov (United States)

Robert H. White

2009-01-01

Fire-retardant-treated products for exterior applications must be subjected to actual or accelerated weathering prior to fire testing. For fire-retardant-treated wood, the two accelerated weathering methods have been Method A and B of ASTM D 2898. The rain test is Method A of ASTM D 2898. Method B includes exposures to ultraviolet (UV) sunlamps in addition to water...

Next Linear Collider Test Accelerator conceptual design report

International Nuclear Information System (INIS)

1993-08-01

This document presents the scientific justification and the conceptual design for the open-quotes Next Linear Collider Test Acceleratorclose quotes (NLCTA) at SLAC. The goals of the NLCTA are to integrate the new technologies of X-band accelerator structures and rf systems being developed for the Next Linear Collider, to measure the growth of the open-quotes dark currentclose quotes generated by rf field emission in the accelerator, to demonstrate multi-bunch beam-loading energy compensation and suppression of higher-order deflecting modes, and to measure any transverse components of the accelerating field. The NLCTA will be a 42-meter-long beam line consisting, consecutively, of a thermionic-cathode gun, an X-band buncher, a magnetic chicane, six 1.8-meter-long sections of 11.4-GHz accelerator structure, and a magnetic spectrometer. Initially, the unloaded accelerating gradient will be 50 MV/m. A higher-gradient upgrade option eventually would increase the unloaded gradient to 100 MV/m

Accelerated aging as vigor test for sunn hemp seeds

OpenAIRE

Silva, Clíssia Barboza da; Barbosa, Rafael Marani; Vieira, Roberval Daiton

2016-01-01

ABSTRACT: This study aimed to determine the most appropriate method to assess the sunn hemp ( Crotalaria juncea L.) seed vigor in the accelerated aging test. Five seed lots from harvest 2007/2008 were evaluated for germination, vigor and seedling emergence in the field. Accelerated aging test was performed at 41°C during 48, 72 and 96 hours, with and without sodium chloride saturated solution. Then, the promising procedure was also performed for 2008/2009 and 2009/2010 harvests. In the tradit...

Accelerated aging as vigor test for sunn hemp seeds

OpenAIRE

Silva,Clíssia Barboza da; Barbosa,Rafael Marani; Vieira,Roberval Daiton

2017-01-01

ABSTRACT: This study aimed to determine the most appropriate method to assess the sunn hemp ( Crotalaria juncea L.) seed vigor in the accelerated aging test. Five seed lots from harvest 2007/2008 were evaluated for germination, vigor and seedling emergence in the field. Accelerated aging test was performed at 41°C during 48, 72 and 96 hours, with and without sodium chloride saturated solution. Then, the promising procedure was also performed for 2008/2009 and 2009/2010 harvests. In the tradit...

77 FR 3166 - Annual Stress Test

Science.gov (United States)

2012-01-23

... FEDERAL DEPOSIT INSURANCE CORPORATION 12 CFR Part 325, Subpart C RIN 3064-AD91 Annual Stress Test... Reform and Consumer Protection Act (the ``Dodd-Frank Act'') regarding stress tests (``proposed rule... to conduct annual stress tests in accordance with the proposed rule, report the results of such...

77 FR 16484 - Annual Stress Test

Science.gov (United States)

2012-03-21

...-2011-0029] RIN 1557-AD58 Annual Stress Test AGENCY: Office of the Comptroller of the Currency, Treasury... billion to conduct an annual stress test and comply with certain reporting and disclosure requirements. To... conduct annual stress tests pursuant to regulations prescribed by their respective Federal primary...

Feedback on the Inaugural Meeting of the Cost 347 Accelerated Loading Test (ALT) Action in Europe: June 27th to 29th 2001

CSIR Research Space (South Africa)

De Beer, Morris

2001-11-01

Full Text Available . The author presented two topics, i.e. Accelerated Pavement Testing (APT) in South Africa, and Stress-In-Motion (SIM). This COST 347 action started in October 2001, and needs to deliver recommendations on ALT April 2004. There are 6 Working Groups, chaired...

77 FR 61238 - Annual Stress Test

Science.gov (United States)

2012-10-09

...-2011-0029] RIN 1557-AD58 Annual Stress Test AGENCY: Office of the Comptroller of the Currency (``OCC... conduct annual stress tests pursuant to regulations prescribed by their respective primary financial... annual stress test as prescribed by this rule. Under the final rule covered institutions are divided into...

Testing of Composite Fan Vanes With Erosion-Resistant Coating Accelerated

Science.gov (United States)

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

2004-01-01

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.

Association of stressful life events with accelerated bone loss in older men: the Osteoporotic Fractures in Men (MrOS) Study

Science.gov (United States)

Fink, Howard A.; Kuskowski, Michael A.; Cauley, Jane A.; Taylor, Brent C.; Schousboe, John T.; Cawthon, Peggy M.; Ensrud, Kristine E.

2015-01-01

Purpose/Introduction Prior studies suggest that stressful life events may increase adverse health outcomes, including falls and possibly fractures. The current study builds on these findings and examines whether stressful life events are associated with increased bone loss. Methods 4388 men aged ≥65 years in the Osteoporotic Fractures in Men study completed total hip bone mineral density (BMD) measures at baseline and visit 2, approximately 4.6 years later, and self-reported stressful life events data mid-way between baseline and visit 2, and at visit 2. We used linear regression to model the association of stressful life events with concurrent annualized total hip BMD loss, and log binomial regression or Poisson regression to model risk of concurrent accelerated BMD loss (>1 SD more than mean annualized change). Results 75.3% of men reported ≥1 type of stressful life event, including 43.3% with ≥2 types of stressful life events. Mean annualized BMD loss was −0.36% (SD 0.88) and 13.9% of men were categorized with accelerated BMD loss (about 5.7% or more total loss). Rate of annualized BMD loss increased with the number of types of stressful life events after adjustment for age (pstressful life events (RR, 1.10 [95% CI, 1.04–1.16]) per increase of 1 type of stressful life event). Fracture risk was not significantly different between stressful life event-accelerated bone loss subgroups (p=0.08). Conclusions In these older men, stressful life events were associated with a small, dose-related increase in risk of concurrent accelerated hip bone loss. Low frequency of fractures limited assessment of whether rapid bone loss mediates any association of stressful life events with incident fractures. Future studies are needed to confirm these findings and to investigate the mechanism that may underlie this association. PMID:25169421

A comparative study of accelerated tests to simulate atmospheric corrosion

International Nuclear Information System (INIS)

Assis, Sergio Luiz de

2000-01-01

In this study, specimens coated with five organic coating systems were exposed to accelerated tests for periods up to 2000 hours, and also to weathering for two years and six months. The accelerated tests consisted of the salt spray test, according to ASTM B-117; Prohesion (ASTM G 85-98 annex 5A); Prohesion combined with cyclic exposure to UV-A radiation and condensation; 'Prohchuva' a test described by ASTM G 85-98 using a salt spray with composition that simulated the acid rain of Sao Paulo, but one thousand times more concentrated, and 'Prohchuva' combined with cyclic exposure to UV-A radiation and condensation. The coated specimens were exposed with and without incision to expose the substrate. The onset and progress of corrosion at and of the exposed metallic surface, besides coating degradation, were followed by visual observation, and photographs were taken. The coating systems were classified according to the extent of corrosion protection given to the substrate, using a method based on ASTM standards D-610, D-714, D-1654 and D-3359. The rankings of the coatings obtained from accelerated tests and weathering were compared and contrasted with classification of the same systems obtained from literature, for specimens exposed to an industrial atmosphere. Coating degradation was strongly dependent on the test, and could be attributed to differences in test conditions. The best correlation between accelerated test and weathering was found for the test Prohesion alternated with cycles of exposure to UV-A radiation and condensation. (author)

Accelerated spike resampling for accurate multiple testing controls.

Science.gov (United States)

Harrison, Matthew T

2013-02-01

Controlling for multiple hypothesis tests using standard spike resampling techniques often requires prohibitive amounts of computation. Importance sampling techniques can be used to accelerate the computation. The general theory is presented, along with specific examples for testing differences across conditions using permutation tests and for testing pairwise synchrony and precise lagged-correlation between many simultaneously recorded spike trains using interval jitter.

Model- and calibration-independent test of cosmic acceleration

International Nuclear Information System (INIS)

Seikel, Marina; Schwarz, Dominik J.

2009-01-01

We present a calibration-independent test of the accelerated expansion of the universe using supernova type Ia data. The test is also model-independent in the sense that no assumptions about the content of the universe or about the parameterization of the deceleration parameter are made and that it does not assume any dynamical equations of motion. Yet, the test assumes the universe and the distribution of supernovae to be statistically homogeneous and isotropic. A significant reduction of systematic effects, as compared to our previous, calibration-dependent test, is achieved. Accelerated expansion is detected at significant level (4.3σ in the 2007 Gold sample, 7.2σ in the 2008 Union sample) if the universe is spatially flat. This result depends, however, crucially on supernovae with a redshift smaller than 0.1, for which the assumption of statistical isotropy and homogeneity is less well established

A fiber optics sensor for strain and stress management in superconducting accelerator magnets

International Nuclear Information System (INIS)

van Oort, J.M.; ten Kate, H.H.J.

1993-01-01

A novel cryogenic interferometric fiber optics sensor for the measurement of strain and stress in the coil windings of superconducting accelerator magnets is described. The sensor can operate with two different readout sources, monochromatic laser light and white light respectively. The sensor head is built up as an extrinsic Fabry-Perot interferometer formed with two cleaved fiber surfaces, and can be mounted in several configurations. When read with laser light, the sensor is an extremely sensitive relative strain or temperature detector. When read with white light the absolute strain and pressure can be measured. Results are presented of tests in several configurations at 77 K and 4.2 K, both for the relative and absolute readout method. Finally, the possible use for quench localization using the temperature sensitivity is described

A modified PMMA cement (Sub-cement) for accelerated fatigue testing of cemented implant constructs using cadaveric bone.

Science.gov (United States)

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

2008-10-20

Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress-intensity factor, fatigue crack propagation rates for Sub-cement were higher by a factor of 25+/-19. When tested in a simplified 2 1/2-D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models.

The BNL Accelerator Test Facility control system

International Nuclear Information System (INIS)

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

1993-01-01

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

Accelerated testing for studying pavement design and performance (FY 2003) : research summary.

Science.gov (United States)

2008-01-01

The Midwest States Accelerated Pavement Testing Pooled Fund Program, financed by : the highway departments of Missouri, Iowa, Kansas and Nebraska, has supported an : accelerated pavement testing (APT) project to compare the performance of stabilized ...

SLAC High Gradient Testing of a KEK X-Band Accelerator Structure

International Nuclear Information System (INIS)

Loewen, Rod

2000-01-01

The high accelerating gradients required for future linear colliders demands a better study of field emission and RF breakdown in accelerator structures. Changes in structure geometry, vacuum pumping, fabrication methods, and surface finish can all potentially impact the conditioning process, dark current emission, and peak RF power handling capability. Recent tests at SLAC of KEK's ''M2'' travelling wave x-band accelerator section provides an opportunity to investigate some of these effects by comparing its performance to previously high power tested structures at SLAC. In addition to studying ultimate power limitations, this test also demonstrates the use of computer automated conditioning to reach practical, achievable gradients

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

Science.gov (United States)

Shen, Jie; Burgess, Diane J

2012-07-01

This review highlights current methods and strategies for accelerated in-vitro drug release testing of extended-release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in-situ depot-forming systems and implants. Extended-release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, 'real-time' in-vitro release tests for these dosage forms are often run over a long time period. Accelerated in-vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in-vitro release methods using United States Pharmacopeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended-release parenteral dosage forms, along with the accelerated in-vitro release testing methods currently employed are discussed. Accelerated in-vitro release testing methods with good discriminatory ability are critical for quality control of extended-release parenteral products. Methods that can be used in the development of in-vitro-in-vivo correlation (IVIVC) are desirable; however, for complex parenteral products this may not always be achievable. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.

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

Science.gov (United States)

Shen, Jie; Burgess, Diane J.

2012-01-01

Objectives This review highlights current methods and strategies for accelerated in vitro drug release testing of extended release parenteral dosage forms such as polymeric microparticulate systems, lipid microparticulate systems, in situ depot-forming systems, and implants. Key findings Extended release parenteral dosage forms are typically designed to maintain the effective drug concentration over periods of weeks, months or even years. Consequently, “real-time” in vitro release tests for these dosage forms are often run over a long time period. Accelerated in vitro release methods can provide rapid evaluation and therefore are desirable for quality control purposes. To this end, different accelerated in vitro release methods using United States Pharmacopoeia (USP) apparatus have been developed. Different mechanisms of accelerating drug release from extended release parenteral dosage forms, along with the accelerated in vitro release testing methods currently employed are discussed. Conclusions Accelerated in vitro release testing methods with good discriminatory ability are critical for quality control of extended release parenteral products. Methods that can be used in the development of in vitro-in vivo correlation (IVIVC) are desirable, however for complex parenteral products this may not always be achievable. PMID:22686344

The SAT Protein of Porcine Parvovirus Accelerates Viral Spreading through Induction of Irreversible Endoplasmic Reticulum Stress.

Science.gov (United States)

Mészáros, István; Tóth, Renáta; Olasz, Ferenc; Tijssen, Peter; Zádori, Zoltán

2017-08-15

The SAT protein (SATp) of porcine parvovirus (PPV) accumulates in the endoplasmic reticulum (ER), and SAT deletion induces the slow-spreading phenotype. The in vitro comparison of the wild-type Kresse strain and its SAT knockout (SAT - ) mutant revealed that prolonged cell integrity and late viral release are responsible for the slower spreading of the SAT - virus. During PPV infection, regardless of the presence or absence of SATp, the expression of downstream ER stress response proteins (Xbp1 and CHOP) was induced. However, in the absence of SATp, significant differences in the quantity and the localization of CHOP were detected, suggesting a role of SATp in the induction of irreversible ER stress in infected cells. The involvement of the induction of irreversible ER stress in porcine testis (PT) cell necrosis and viral egress was confirmed by treatment of infected cells by ER stress-inducing chemicals (MG132, dithiothreitol, and thapsigargin), which accelerated the egress and spreading of both the wild-type and the SAT - viruses. UV stress induction had no beneficial effect on PPV infection, underscoring the specificity of ER stress pathways in the process. However, induction of CHOP and its nuclear translocation cannot alone be responsible for the biological effect of SAT, since nuclear CHOP could not complement the lack of SAT in a coexpression experiment. IMPORTANCE SATp is encoded by an alternative open reading frame of the PPV genome. Earlier we showed that SATp of the attenuated PPV NADL-2 strain accumulates in the ER and accelerates virus release and spreading. Our present work revealed that slow spreading is a general feature of SAT - PPVs and is the consequence of prolonged cell integrity. PPV infection induced ER stress in infected cells regardless of the presence of SATp, as demonstrated by the morphological changes of the ER and expression of the stress response proteins Xbp1 and CHOP. However, the presence of SATp made the ER stress more severe and

European accelerator facilities for single event effects testing

Energy Technology Data Exchange (ETDEWEB)

Adams, L; Nickson, R; Harboe-Sorensen, R [ESA-ESTEC, Noordwijk (Netherlands); Hajdas, W; Berger, G

1997-03-01

Single event effects are an important hazard to spacecraft and payloads. The advances in component technology, with shrinking dimensions and increasing complexity will give even more importance to single event effects in the future. The ground test facilities are complex and expensive and the complexities of installing a facility are compounded by the requirement that maximum control is to be exercised by users largely unfamiliar with accelerator technology. The PIF and the HIF are the result of experience gained in the field of single event effects testing and represent a unique collaboration between space technology and accelerator experts. Both facilities form an essential part of the European infrastructure supporting space projects. (J.P.N.)

Accelerated testing for studying pavement design and performance (FY 2002) : research summary.

Science.gov (United States)

2004-01-01

This report covers the Fiscal Year 2002 project conducted at the Accelerated Testing : Laboratory at Kansas State University. The project was selected and funded by the : Midwest States Accelerated Testing Pooled Fund Program, which includes Iowa, Ka...

High gradient tests of SLAC Linear Collider Accelerator Structures

International Nuclear Information System (INIS)

Wang, J.W.; Deruyter, H.; Eichner, J.; Fant, K.H.; Hoag, H.A.; Koontz, R.F.; Lavine, T.; Loew, G.A.; Loewen, R.; Menegat, L.

1994-08-01

This paper describes the current SLAC R ampersand D program to develop room temperature accelerator structures for the Next Linear Collider (NLC). The structures are designed to operate at 11.4 GHz at an accelerating gradient in the range of 50 to 100 MV/m. In the past year a 26 cm constant-impedance traveling-wave section, a 75 cm constant-impedance traveling-wave section, and a 1.8 m traveling-wave section with detuned deflecting modes have been high-power tested. The paper presents a brief description of the RF test setup, the design and manufacturing details of the structures, and a discussion of test results including field emission, RF processing, dark current spectrum and RF breakdown

Electrical performance characteristics of the SSC Accelerator System String Test

International Nuclear Information System (INIS)

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

1993-05-01

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

Development of laboratory acceleration test method for service life prediction of concrete structures

International Nuclear Information System (INIS)

Cho, M. S.; Song, Y. C.; Bang, K. S.; Lee, J. S.; Kim, D. K.

1999-01-01

Service life prediction of nuclear power plants depends on the application of history of structures, field inspection and test, the development of laboratory acceleration tests, their analysis method and predictive model. In this study, laboratory acceleration test method for service life prediction of concrete structures and application of experimental test results are introduced. This study is concerned with environmental condition of concrete structures and is to develop the acceleration test method for durability factors of concrete structures e.g. carbonation, sulfate attack, freeze-thaw cycles and shrinkage-expansion etc

Solutions for acceleration measurement in vehicle crash tests

Science.gov (United States)

Dima, D. S.; Covaciu, D.

2017-10-01

Crash tests are useful for validating computer simulations of road traffic accidents. One of the most important parameters measured is the acceleration. The evolution of acceleration versus time, during a crash test, form a crash pulse. The correctness of the crash pulse determination depends on the data acquisition system used. Recommendations regarding the instrumentation for impact tests are given in standards, which are focused on the use of accelerometers as impact sensors. The goal of this paper is to present the device and software developed by authors for data acquisition and processing. The system includes two accelerometers with different input ranges, a processing unit based on a 32-bit microcontroller and a data logging unit with SD card. Data collected on card, as text files, is processed with a dedicated software running on personal computers. The processing is based on diagrams and includes the digital filters recommended in standards.

Study on the correlation between long-term exposure tests and accelerated corrosion tests by the combined damage of salts

International Nuclear Information System (INIS)

Park, Sang Soon; Lee, Min Woo

2014-01-01

Interest in the durability assessment and structural performance has increased according to an increase of concrete structures in salt damage environment recent years. Reliable way ensuring the most accelerated corrosion test is a method of performing the rebar corrosion monitoring as exposed directly to the marine test site exposure. However, long-term exposure test has a disadvantage because of a long period of time. Therefore, many studies on reinforced concrete in salt damage environments have been developed as alternatives to replace this. However, accelerated corrosion test is appropriate to evaluate the critical chlorine concentration in the short term, but only accelerated test method, is not easy to get correct answer. Accuracy of correlation acceleration test depends on the period of the degree of exposure environments. Therefore, in this study, depending on the concrete mix material, by the test was performed on the basis of the composite degradation of the salt damage, and investigate the difference of corrosion initiation time of the rebar, and indoor corrosion time of the structure, of the marine environment of the actual environments were investigated. The correlation coefficient was derived in the experiment. Long-term exposure test was actually conducted in consideration of the exposure conditions submerged zone, splash zone and tidal zone. The accelerated corrosion tests were carried out by immersion conditions, and by the combined deterioration due to the carbonation and accelerated corrosion due to wet and dry condition

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

International Nuclear Information System (INIS)

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

1986-01-01

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

Pilot instrumentation of a Superpave test section at the Kansas Accelerated Testing laboratory

Science.gov (United States)

2003-04-01

Two Superpave test sections were constructed at the Kansas Accelerated Testing Laboratory (K-ATL) with 12.5 mm (2 in) nominal maximum size Superpave mixture (SM-2A) with varying percentages (15 and 30 percent) of river sand. A 150 kN (34 kip) tandem ...

Electrical performance characteristics of the SSC Accelerator System String Test

International Nuclear Information System (INIS)

Robinson, W.; Burgett, W.; Dombeck, T.; Gannon, J.; Kraushaar, P.; McInturff, A.; Savord, T.; Tool, G.

1993-01-01

The string test facility was constructed to provide a development test bed for the arc regions of the Superconducting Super Collider (SSC). Significant effort has been devoted to the development and testing of superconducting magnets, spools, and accelerator control systems required for the SSC. The string test facility provides the necessary environment required to evaluate the operational performance of these components as they are configured as an accelerator lens in the collider. This discussion will review the results of high current testing of the string conducted to evaluate magnet element uniformity and compatibility, the splice resistance used to connect the magnets, and system response to various quench conditions. Performance results of the spools, energy bypass systems, energy dump, and the power supply system are also discussed

Electrical performance characteristics of the SSC Accelerator System String Test

International Nuclear Information System (INIS)

Robinson, W.; Burgett, W.; Dombeck, T.; Gannon, J.; Kraushaar, P.; McInturff, A.; Savord, T.; Tool, G.

1993-05-01

The string test facility was constructed to provide a development test bed for the arc regions of the Superconducting Super Collider (SSC). Significant effort has been devoted to the development and testing of superconducting magnets, spools, and accelerator control systems required for the SSC. The string test facility provides the necessary environment required to evaluate the operational performance of these components as they are configured as an accelerator lens in the collider. This discussion will review the results of high current testing of the string conducted to evaluate magnet element uniformity and compatibility, the splice resistance used to connect the magnets, and system response to various quench conditions. Performance results of the spools, energy bypass systems, energy dump, and the power supply system are also discussed

Real-time and accelerated outdoor endurance testing of solar cells

Science.gov (United States)

Forestieri, A. F.; Anagnostou, E.

1977-01-01

Real-time and accelerated outdoor endurance testing was performed on a variety of samples of interest to the National Photovoltaic Conversion Program. The real-time tests were performed at seven different sites and the accelerated tests were performed at one of those sites in the southwestern United States. The purpose of the tests were to help evaluate the lifetime of photovoltaic systems. Three types of samples were tested; transmission samples of possible cover materials, sub-modules constructed using these materials attached to solar cells, and solar cell modules produced by the manufacturers for the ERDA program. Results indicate that suitable cover materials are glass, FEP-A and PFA. Dirt accumulation and cleanability are important factors in the selection of solar cell module covers and encapsulants.

Accelerated Testing with Multiple Failure Modes under Several Temperature Conditions

OpenAIRE

Zongyue Yu; Zhiqian Ren; Junyong Tao; Xun Chen

2014-01-01

A complicated device may have multiple failure modes, and some of the failure modes are sensitive to low temperatures. To assess the reliability of a product with multiple failure modes, this paper presents an accelerated testing in which both of the high temperatures and the low temperatures are applied. Firstly, an acceleration model based on the Arrhenius model but accounting for the influence of both the high temperatures and low temperatures is proposed. Accordingly, an accelerated testi...

An accelerated test method of luminous flux depreciation for LED luminaires and lamps

International Nuclear Information System (INIS)

Qian, C.; Fan, X.J.; Fan, J.J.; Yuan, C.A.; Zhang, G.Q.

2016-01-01

Light Emitting Diode (LED) luminaires and lamps are energy-saving and environmental friendly alternatives to traditional lighting products. However, current luminous flux depreciation test at luminaire and lamp level requires a minimum of 6000 h testing, which is even longer than the product development cycle time. This paper develops an accelerated test method for luminous flux depreciation to reduce the test time within 2000 h at an elevated temperature. The method is based on lumen maintenance boundary curve, obtained from a collection of LED source lumen depreciation data, known as LM-80 data. The exponential decay model and Arrhenius acceleration relationship are used to determine the new threshold of lumen maintenance and acceleration factor. The proposed method has been verified by a number of simulation studies and experimental data for a wide range of LED luminaire and lamp types from both internal and external experiments. The qualification results obtained by the accelerated test method agree well with traditional 6000 h tests. - Highlights: • We develop an accelerated test method for LED luminaires and lamps. • The method is proposed based on a “Boundary Curve” concept. • The parameters of the boundary curve are extracted from LM-80 test reports. • Qualification results from the proposed method agree with ES requirements.

Accelerated in vitro release testing method for naltrexone loaded PLGA microspheres.

Science.gov (United States)

Andhariya, Janki V; Choi, Stephanie; Wang, Yan; Zou, Yuan; Burgess, Diane J; Shen, Jie

2017-03-30

The objective of the present study was to develop a discriminatory and reproducible accelerated release testing method for naltrexone loaded parenteral polymeric microspheres. The commercially available naltrexone microsphere product (Vivitrol ® ) was used as the testing formulation in the in vitro release method development, and both sample-and-separate and USP apparatus 4 methods were investigated. Following an in vitro drug stability study, frequent media replacement and addition of anti-oxidant in the release medium were used to prevent degradation of naltrexone during release testing at "real-time" (37°C) and "accelerated" (45°C), respectively. The USP apparatus 4 method was more reproducible than the sample-and-separate method. In addition, the accelerated release profile obtained using USP apparatus 4 had a shortened release duration (within seven days), and good correlation with the "real-time" release profile. Lastly, the discriminatory ability of the developed accelerated release method was assessed using compositionally equivalent naltrexone microspheres with different release characteristics. The developed accelerated USP apparatus 4 release method was able to detect differences in the release characteristics of the prepared naltrexone microspheres. Moreover, a linear correlation was observed between the "real-time" and accelerated release profiles of all the formulations investigated, suggesting that the release mechanism(s) may be similar under both conditions. These results indicate that the developed accelerated USP apparatus 4 method has the potential to be an appropriate fast quality control tool for long-acting naltrexone PLGA microspheres. Copyright © 2017 Elsevier B.V. All rights reserved.

(stress) testing

African Journals Online (AJOL)

However, maximal HR was significantly higher in all groups during their sporting activities than during stress testing in the laboratory (P < 0.01). Conclusions. Maximal HR in veteran athletes during specific sporting activities was significantly higher than that attained during a routine sECG. This finding was not sport-specific, ...

Biaxial Stress Tests of Plain Concrete

Energy Technology Data Exchange (ETDEWEB)

Lee, S.K.; Cho, M.S.; Song, Y.C. [Korea Electric Power Research Institute, Taejon (Korea)

2001-07-01

Containment concrete specimens(4000, 5000psi) were tested under biaxial stress and presented basic physical properties and biaxial failure envelops for the concrete specimens. Failure behaviors of concrete under biaxial stress were assessed with stress-strain responses and failure modes. Here provided real test data to develop nonlinear finite element concrete models. (author). 15 refs., 46 figs., 4 tabs.

Compact X-ray source at STF (Super Conducting Accelerator Test Facility)

International Nuclear Information System (INIS)

Urakawa, J

2012-01-01

KEK-STF is a super conducting linear accelerator test facility for developing accelerator technologies for the ILC (International Linear Collider). We are supported in developing advanced accelerator technologies using STF by Japanese Ministry (MEXT) for Compact high brightness X-ray source development. Since we are required to demonstrate the generation of high brightness X-ray based on inverse Compton scattering using super conducting linear accelerator and laser storage cavity technologies by October of next year (2012), the design has been fixed and the installation of accelerator components is under way. The necessary technology developments and the planned experiment are explained.

Design of Accelerated Reliability Test for CNC Motorized Spindle Based on Vibration Signal

Directory of Open Access Journals (Sweden)

Chen Chao

2016-01-01

Full Text Available Motorized spindle is the key functional component of CNC machining centers which is a mechatronics system with long life and high reliability. The reliability test cycle of motorized spindle is too long and infeasible. This paper proposes a new accelerated test for reliability evaluation of motorized spindle. By field reliability test, authors collect and calculate the load data including rotational speed, cutting force and torque. Load spectrum distribution law is analyzed. And authors design a test platform to apply the load spectrum. A new method to define the fuzzy acceleration factor based on the vibration signal is proposed. Then the whole test plan of accelerated reliability test is done.

Proposed research on class I components to test a general approach to accelerated aging under combined stress environments

International Nuclear Information System (INIS)

Gillen, K.T.; Salazar, E.A.; Frank, C.W.

1977-04-01

This report summarizes research on the aging of Class I components in environments representative of nuclear power plants. It discusses Class IE equipment used in nuclear power plants, typical environments encountered by Class IE components, and aging techniques used to qualify this equipment. General discussions of radiation chemistry of polymers and accelerated aging techniques are also included. Based on the inadequacies of present aging techniques for Class IE equipment, a proposal for an experimental program on electrical cables is presented. One of the main purposes of the proposed work is to obtain relevant data in two areas of particular concern--the effect of radiation dose rate on polymer degradation, and the importance of synergism for combined thermal and radiation environments. A new model that allows combined environment accelerated aging to be carried out is introduced, and it is shown how the experimental data to be generated can be used to test this model

RF pulse compression in the NLC test accelerator at SLAC

International Nuclear Information System (INIS)

Lavine, T.L.

1995-01-01

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

Accelerated Testing of Polymeric Composites Using the Dynamic Mechanical Analyzer

Science.gov (United States)

Abdel-Magid, Becky M.; Gates, Thomas S.

2000-01-01

Creep properties of IM7/K3B composite material were obtained using three accelerated test methods at elevated temperatures. Results of flexural creep tests using the dynamic mechanical analyzer (DMA) were compared with results of conventional tensile and compression creep tests. The procedures of the three test methods are described and the results are presented. Despite minor differences in the time shift factor of the creep compliance curves, the DMA results compared favorably with the results from the tensile and compressive creep tests. Some insight is given into establishing correlations between creep compliance in flexure and creep compliance in tension and compression. It is shown that with careful consideration of the limitations of flexure creep, a viable and reliable accelerated test procedure can be developed using the DMA to obtain the viscoelastic properties of composites in extreme environments.

Verification of mechanistic-empirical design models for flexible pavements through accelerated pavement testing.

Science.gov (United States)

2014-08-01

The Midwest States Accelerated Pavement Testing Pooled Fund Program, financed by the highway : departments of Kansas, Iowa, and Missouri, has supported an accelerated pavement testing (APT) project to : validate several models incorporated in the NCH...

Accelerated testing of space mechanisms

Science.gov (United States)

Murray, S. Frank; Heshmat, Hooshang

1995-01-01

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.

Accelerated pavement testing of low-volume paved roads with geocell reinforcement : [technical summary].

Science.gov (United States)

2015-03-01

The Midwest States Accelerated Pavement Testing Pooled-Fund Program, financed : by the highway departments of Kansas, Iowa, Missouri, and New York, has : supported an accelerated pavement testing (APT) project to study the rehabilitation : of low-vol...

Accelerated corrosion test for metal drainage pipes : final report.

Science.gov (United States)

1987-06-01

This study represents an attempt to develop an accelerated test which would assist the highway engineer in evaluating the usefulness of a new type of coated steel culvert. The test method was to be short in duration (in the order of days), and the re...

Accelerated leach testing of radionuclides from solidified low-level waste

International Nuclear Information System (INIS)

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

1989-01-01

This paper describes some of the work performed to develop an accelerated leach test designed to provide data that show long-term leaching behavior of solidified waste in a relatively short period of testing (1,2). The need for an accelerated leach test stems from the fact that the response of an effectively solidified waste form to the leaching process is so slow that a very long time is required to complete a test which shows the long-term leaching behavior of a waste form. Because of time limitations, as well as economic considerations, most studies have been limited to the early stages of the leaching process which is predominantly controlled by diffusion, although acknowledged to be due to also dissolution, corrosion or ion-exchange

Evaluation methods of vibration stress of small bore piping

Energy Technology Data Exchange (ETDEWEB)

Hiramatsu, Miki; Sasaki, Toru [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)

2001-09-01

Fatigue fracture by vibration stress is one of the main causes of troubles which occur at small bore piping in nuclear power plants. Therefore at the plants they manage small bore piping using a method in which their vibration accelerations are measured and the vibration stresses are calculated. In this work, vibration tests for two sets of mock-ups simulating actual piping in the plants by sinusoidal oscillation and by that obtained at an actual plant were carried out, and then an evaluation method was developed to obtain proper value of vibration stress from the measured data by the vibration tests. In comparison of the vibration stress obtained from the measured acceleration with that directly measured using strain gauges, it is confirmed that accurate vibration stress can be evaluated by a formula in which the real center of gravity of small bore piping and the acceleration of main (system) piping are considered. (author)

Serpentine endophytic bacterium Pseudomonas azotoformans ASS1 accelerates phytoremediation of soil metals under drought stress.

Science.gov (United States)

Ma, Ying; Rajkumar, Mani; Moreno, António; Zhang, Chang; Freitas, Helena

2017-10-01

This study evaluates the potential of serpentine endophytic bacterium to foster phytoremediation efficiency of Trifolium arvense grown on multi-metal (Cu, Zn and Ni) contaminated soils under drought stress. A drought resistant endophytic bacterial strain ASS1 isolated from the leaves of Alyssum serpyllifolium grown in serpentine soils was identified as Pseudomonas azotoformans based on biochemical tests and partial 16S rRNA gene sequencing. P. azotoformans ASS1 possessed abiotic stress resistance (heavy metals, drought, salinity, antibiotics and extreme temperature) and plant growth promoting (PGP) properties (phosphate solubilization, nitrogen fixation, production of 1-aminocyclopropane-1-carboxylate deaminase, siderophore and ammonia). Inoculation of T. arvense with ASS1 considerably increased the plant biomass and leaf relative water content in both roll towel assay and pot experiments in the absence and presence of drought stress (DS). In the pot experiments, ASS1 greatly enhanced chlorophyll content, catalase, peroxidase, superoxide dismutase activities, and proline content (only in the absence of drought) in plant leaves, whereas they decreased the concentrations of malondialdehyde. Irrespective of water stress, ASS1 significantly improved accumulation, total removal, bio-concentration factor and biological accumulation coefficient of metals (Cu, Zn and Ni), while decreased translocation factors of Cu. The effective colonization and survival in the rhizosphere and tissue interior assured improved plant growth and successful metal phytoremediation under DS. These results demonstrate the potential of serpentine endophytic bacterium ASS1 for protecting plants against abiotic stresses and helping plants to thrive in semiarid ecosystems and accelerate phytoremediation process in metal polluted soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Time-dependent diffusive acceleration of test particles at shocks

Energy Technology Data Exchange (ETDEWEB)

Drury, L.O' C. (Dublin Inst. for Advanced Studies (Ireland))

1991-07-15

The acceleration of test particles at a steady plane non-relativistic shock is considered. Analytic expressions are found for the mean and the variance of the acceleration time distribution in the case where the diffusion coefficient has an arbitrary dependence on position and momentum. These expressions are used as the basis for an approximation scheme which is shown, by comparison with numerical solutions, to give an excellent representation of the time-dependent spectrum. (author).

Time-dependent diffusive acceleration of test particles at shocks

International Nuclear Information System (INIS)

Drury, L.O'C.

1991-01-01

The acceleration of test particles at a steady plane non-relativistic shock is considered. Analytic expressions are found for the mean and the variance of the acceleration time distribution in the case where the diffusion coefficient has an arbitrary dependence on position and momentum. These expressions are used as the basis for an approximation scheme which is shown, by comparison with numerical solutions, to give an excellent representation of the time-dependent spectrum. (author)

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

International Nuclear Information System (INIS)

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

1985-01-01

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

High gradient test of the C-band choke-mode type accelerating structure

International Nuclear Information System (INIS)

Inagaki, T.; Shintake, T.; Baba, H.; Togawa, K.; Onoe, K.; Marechal, X.; Takashima, T.; Takahashi, S.; Matsumoto, H.

2004-01-01

The C-band (5712 MHz) choke-mode type accelerating structure will be used for SPring-8 Compact SASE-FEL Source (SCSS). To make the accelerator length short, we designed the field gradient as high as 40 MV/m. Since it is higher gradient than other traditional electron accelerators, we have to carefully check its performance (RF breakdown, dark current emission, etc.) in the high gradient test stand. The first experiment will be scheduled in this summer. In this paper, we will describe the preparation progress for the test. (author)

Residual Stress Testing of Outer 3013 Containers

International Nuclear Information System (INIS)

Dunn, K.

2004-01-01

A Gas Tungsten Arc Welded (GTAW) outer 3013 container and a laser welded outer 3013 container have been tested for residual stresses according to the American Society for Testing Materials (ASTM) Standard G-36-94 [1]. This ASTM standard describes a procedure for conducting stress-corrosion cracking tests in boiling magnesium chloride (MgCl2) solution. Container sections in both the as-fabricated condition as well as the closure welded condition were evaluated. Significantly large residual stresses were observed in the bottom half of the as-fabricated container, a result of the base to can fabrication weld because through wall cracks were observed perpendicular to the weld. This observation indicates that regardless of the closure weld technique, sufficient residual stresses exist in the as-fabricated container to provide the stress necessary for stress corrosion cracking of the container, at the base fabrication weld. Additionally, sufficiently high residual stresses were observed in both the lid and the body of the GTAW as well as the laser closure welded containers. The stresses are oriented perpendicular to the closure weld in both the container lid and the container body. Although the boiling MgCl2 test is not a quantitative test, a comparison of the test results from the closure welds shows that there are noticeably more through wall cracks in the laser closure welded container than in the GTAW closure welded container

Medical Standards for Experimental Human Use in Acceleration Stress Research

Science.gov (United States)

1983-01-01

or re- teroposterior and lateral X-rays of the cervical , thoracic, sources, we consider a positive treadmill test to be dis- and lumbar spine. These...Gz stress. The requirement for a complete cervical , thoracic and dividuals who developed significant stress dysrhythmias lumbar spine X-ray series...hematoma h. Hernia Ill. Cardiac Stress: a. Dywrhythmla (Tachyarrhythmias and Bradyarrhythmim) b. Heart blocks c. Stress caadlomyopmt U244 Awono. spme

Ultra-Accelerated Natural Sunlight Exposure Testing Facilities

Science.gov (United States)

Lewandowski, Allan A.; Jorgensen, Gary J.

2004-11-23

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

Commissioning of the Ground Test Accelerator RFQ

International Nuclear Information System (INIS)

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

1992-01-01

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

Commissioning of the ground test accelerator RFQ

International Nuclear Information System (INIS)

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

1992-01-01

The Ground Test Accelerator (GTA) has the objective of verifying much of the technology (physics and engineering) required for producing high-brightness, high-current H - beams. GTA commissioning is staged to verify the beam dynamics design of each major accelerator component as it is brought on line. The commissioning stages are the 35-keV H - injector, the 2.5-MeV radio-frequency quadrupole (RFQ), the intertank matching section (IMS), the 3.2-MeV first 2-βλ drift tube linac (DTL-1) module, the 8.7-MeV 2-βλDTL (modules 1-5), and the 24-MeV GTA (all 10 DTL modules). Commissioning results from the RFQ beam experiments are presented along with comparisons with simulations. (Author) 8 refs., 9 figs

RF pulse compression in the NLC test accelerator at SLAC

International Nuclear Information System (INIS)

Lavine, T.L.

1995-01-01

At the Stanford Linear Accelerator Center (SLAC), we are designing a Next Linear Collider (NLC) with linacs powered by X-band klystrons with rf pulse compression. The design of the linac rf system is based on X-band prototypes which have been tested at high power, and on a systems-integration test---the Next Linear Collider Test Accelerator (NLCTA)---which is currently under construction at SLAC. This paper discusses some of the systems implications of rf pulse compression, and the use of pulse compression in the NLCTA, both for peak power multiplication and for controlling, by rf phase modulation, intra-pulse variations in the linac beam energy. copyright 1995 American Institute of Physics

High power testing oa ANL X-band dielectric-loaded accelerating structures

International Nuclear Information System (INIS)

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

2002-01-01

In the second phase of a program to develop a compact accelerator based on a dielectric-loaded accelerating structure, we have conducted high power tests on a traveling-wave and a standing-wave prototype. Indications are that the traveling-wave structure achieved an accelerating gradient of 3-5 MV/m before the input coupling window failed, while the standing wave structure was poorly matched at high power due to contamination of copper residue on its coupling window. To solve both of these problems, a new method for coupling RF into the structures has been developed. The new couplers and the rest of the modular structure are currently under construction and will be tested at the Naval Research Laboratory shortly

Chronic stress accelerates the development of endometriosis in mouse through adrenergic receptor β2.

Science.gov (United States)

Long, Qiqi; Liu, Xishi; Qi, Qiuming; Guo, Sun-Wei

2016-11-01

Does chronic stress in mice accelerate the development of endometriosis, and, if so, through what mechanism? Exposure to chronic stress accelerates the development of endometriosis and exacerbates the endometriosis-associated generalized hyperalgesia, most likely through activation of the adrenoceptor β2 (ADRB2) and cAMP responsive element-binding protein (CREB). Women with endometriosis tend to have higher levels of psychological stress, which is known to impact negatively on health in general and to promote tumor growth and metastasis in particular. Exposure to chronic stress before and after the induction of endometriosis is reported to increase lesion sizes in rodents, but it is unclear whether adrenoceptors are involved or not in the stress-promoted development of endometriosis. Three independent, prospective, randomized mouse experimentations. A total of 184 virgin female Balb/C mice were used. In Experiment 1, the mice were randomly divided into four groups: the control group, which received no stress; the before, after and both groups, which received immobilization stress before, after and both before and after the induction of endometriosis, respectively. In Experiment 2, mice were randomly divided into four groups one day after the induction of endometriosis: phosphate buffer saline (PBS) and propranolol (PROP) groups, which received the mini-pump containing, respectively, PBS only and propranolol (a non-selective ADRB antagonist) but no stress, STR+PROP and STR+PBS groups, which received stress and the mini-pump containing, respectively, propranolol and PBS. The immobilization stress started after the insertion of mini-pumps. In Experiment 3, mice were induced with endometriosis. Three days after the induction, they were randomly divided into four groups: control, ADRAa, ADRB2a, and ADRBa, which received the mini-pump containing solution only, metaraminol (a non-specific α adrenoceptor agonist), tebutaline (a specific ADRB2 agonist), or isoproterenol

Poisson simulation for high voltage terminal of test stand for 1MV electrostatic accelerator

Energy Technology Data Exchange (ETDEWEB)

Park, Sae-Hoon; Kim, Jeong-Tae; Kwon, Hyeok-Jung; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Yu-Seok [Dongguk Univ.., Gyeongju (Korea, Republic of)

2014-10-15

KOMAC provide ion beam to user which energy range need to expand to MeV range and develop 1 MV electrostatic accelerator. The specifications of the electrostatic accelerator are 1MV acceleration voltage, 10 mA peak current and variable gas ion. We are developing test stand before set up 1 MV electrostatic accelerator. The test stand voltage is 300 kV and operating time is 8 hours. The test stand is consist of 300 kV high voltage terminal, DC-AC-DC inverter, power supply device inside terminal, 200MHz RF power, 5 kV extraction power supply, 300 kV accelerating tube and vacuum system.. The beam measurement system and beam dump will be installed next to accelerating tube. Poisson code simulation results of the high voltage terminal are presented in this paper. Poisson code has been used to calculate the electric field for high voltage terminal. The results of simulation were verified with reasonable results. The poisson code structure could be apply to the high voltage terminal of the test stand.

Poisson simulation for high voltage terminal of test stand for 1MV electrostatic accelerator

International Nuclear Information System (INIS)

Park, Sae-Hoon; Kim, Jeong-Tae; Kwon, Hyeok-Jung; Cho, Yong-Sub; Kim, Yu-Seok

2014-01-01

KOMAC provide ion beam to user which energy range need to expand to MeV range and develop 1 MV electrostatic accelerator. The specifications of the electrostatic accelerator are 1MV acceleration voltage, 10 mA peak current and variable gas ion. We are developing test stand before set up 1 MV electrostatic accelerator. The test stand voltage is 300 kV and operating time is 8 hours. The test stand is consist of 300 kV high voltage terminal, DC-AC-DC inverter, power supply device inside terminal, 200MHz RF power, 5 kV extraction power supply, 300 kV accelerating tube and vacuum system.. The beam measurement system and beam dump will be installed next to accelerating tube. Poisson code simulation results of the high voltage terminal are presented in this paper. Poisson code has been used to calculate the electric field for high voltage terminal. The results of simulation were verified with reasonable results. The poisson code structure could be apply to the high voltage terminal of the test stand

Test Particles with Acceleration-Dependent Lagrangian

OpenAIRE

Toller, M.

2005-01-01

We consider a classical test particle subject to electromagnetic and gravitational fields, described by a Lagrangian depending on the acceleration and on a fundamental length. We associate to the particle a moving local reference frame and we study its trajectory in the principal fibre bundle of all the Lorentz frames. We discuss in this framework the general form of the Lagrange equations and the connection between symmetries and conservation laws (Noether theorem). We apply these results to...

Modelling of degradation processes in creep resistant steels through accelerated creep tests after long-term isothermal ageing

Energy Technology Data Exchange (ETDEWEB)

Sklenicka, V.; Kucharova, K.; Svoboda, M.; Kroupa, A.; Kloc, L. [Academy of Sciences of the Czech Republic, Brno (Czech Republic). Inst. of Physics of Materials; Cmakal, J. [UJP PRAHA a.s., Praha-Zbraslav (Czech Republic)

2010-07-01

Creep behaviour and degradation of creep properties of creep resistant materials are phenomena of major practical relevance, often limiting the lives of components and structures designed to operate for long periods under stress at elevated and/or high temperatures. Since life expectancy is, in reality, based on the ability of the material to retain its high-temperature creep strength for the projected designed life, methods of creep properties assessment based on microstructural evolution in the material during creep rather than simple parametric extrapolation of short-term creep tests are necessary. In this paper we will try to further clarify the creep-strength degradation of selected advanced creep resistant steels. In order to accelerate some microstructural changes and thus to simulate degradation processes in long-term service, isothermal ageing at 650 C for 10 000 h was applied to P91 and P23 steels in their as-received states. The accelerated tensile creep tests were performed at temperature 600 C in argon atmosphere on all steels both in the as-received state and after long-term isothermal ageing, in an effort to obtain a more complete description of the role of microstructural stability in high temperature creep of these steels. Creep tests were followed by microstructural investigations by means of both transmission and scanning electron microscopy and by the thermodynamic calculations. The applicability of the accelerated creep tests was verified by the theoretical modelling of the phase equilibria at different temperatures. It is suggested that under restructed oxidation due to argon atmosphere microstructural instability is the main detrimental process in the long-term degradation of the creep rupture strength of these steels. (orig.)

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

Science.gov (United States)

Mcdermott, P. P.

1979-01-01

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

Accelerated testing statistical models, test plans, and data analysis

CERN Document Server

Nelson, Wayne B

2009-01-01

The Wiley-Interscience Paperback Series consists of selected books that have been made more accessible to consumers in an effort to increase global appeal and general circulation. With these new unabridged softcover volumes, Wiley hopes to extend the lives of these works by making them available to future generations of statisticians, mathematicians, and scientists. "". . . a goldmine of knowledge on accelerated life testing principles and practices . . . one of the very few capable of advancing the science of reliability. It definitely belongs in every bookshelf on engineering.""-Dev G.

Stress Testing with Student's t Dependence

NARCIS (Netherlands)

H.J.W.G. Kole (Erik); C.G. Koedijk (Kees); M.J.C.M. Verbeek (Marno)

2003-01-01

textabstractIn this study we propose the use of the Student's t dependence function to model dependence between asset returns when conducting stress tests. To properly include stress testing in a risk management system, it is important to have accurate information about the (joint) probabilities of

Accelerating action of stresses on crystallization kinetics in silicon ion-implanted layers during pulsed heating

International Nuclear Information System (INIS)

Aleksandrov, L.N.

1985-01-01

Numerical simulation of the effect of stressed in ion-implanted layers on kinetics of amorphous phase transformations is performed. The suggested model of accounting stresses including concentration ones is based on the locality of action of interstitial addition atoms and on general structural inhomogeneity of amorphous semiconductor leading to the formation of areas of the facilitated phase transition. Accounting of effect of energy variation of silicon atoms interaction on probability of displacement events and atoms building in lattice points or atomic bonds disintegration allows one to trace the accelerating action of introduced by ion implantation stresses on the kinetics of layer crystallization during pulsed heating

Group SkSP-R sampling plan for accelerated life tests

Indian Academy of Sciences (India)

Muhammad Aslam

2017-09-15

Sep 15, 2017 ... SkSP-R sampling; life test; Weibull distribution; producer's risk; ... designed a sampling plan under a time-truncated life test .... adjusted using an acceleration factor. ... where P is the probability of lot acceptance for a single.

Optimizing conditions for an accelerated leach test

International Nuclear Information System (INIS)

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

1988-01-01

An accelerated leach test for low-level radioactive waste forms is being developed to provide, in a short time, data that can be extrapolated to long time periods. The approach is to provide experimental conditions that will accelerate leaching without changing the dominant release mechanism. Experimental efforts have focused on combining individual factors that have been observed to accelerate leaching. These include elevated temperature, increased leachant volume, and reduced specimen size. The response of diffusion coefficients to various acceleration factors have been evaluated and provide information on experimental parameters that need to be optimized to increase leach rates. For example, these data show that large volumes of leachant are required when leaching portland cement waste forms at elevated temperatures because of high concentrations of dissolved species. Sr-85 leaching is particularly susceptible to suppression due to concentration effects while Cs-137 leaching is less so. Preliminary modeling using a diffusion mechanism (allowing for depletion) of a finite cylinder geometry indicates that during early portions of experiments (daily sampling intervals), leaching is diffusion controlled and more rapid than later in the same experiments (weekly or greater sampling intervals). For cement waste forms, this reduction in rate may be partially controlled by changes in physical structure and chemistry (sometimes related to environmental influences such as CO 2 ), but it is more likely associated with the duration of the sampling interval. 9 refs., 6 figs

Radiation testing of thick-wall objects using a linear accelerator or Co-60

International Nuclear Information System (INIS)

Depending on the energy required, a 60 Co source or various types of betatrons and linear accelerators may be used for radiation testing of thick-walled metal parts. While 60 Co sources are easily transported, accelerators are not, but a transportable linear accelerator is described

Salicylic acid alleviates decreases in photosynthesis under heat stress and accelerates recovery in grapevine leaves

Directory of Open Access Journals (Sweden)

Cheng Jian-Shan

2010-02-01

Full Text Available Abstract Background Although the effect of salicylic acid (SA on photosynthesis of plants including grapevines has been investigated, very little is yet known about the effects of SA on carbon assimilation and several components of PSII electron transport (donor side, reaction center and acceptor side. In this study, the impact of SA pretreatment on photosynthesis was evaluated in the leaves of young grapevines before heat stress (25°C, during heat stress (43°C for 5 h, and through the following recovery period (25°C. Photosynthetic measures included gas exchange parameters, PSII electron transport, energy dissipation, and Rubisco activation state. The levels of heat shock proteins (HSPs in the chloroplast were also investigated. Results SA did not significantly (P Pn of leaves before heat stress. But, SA did alleviate declines in Pn and Rubisco activition state, and did not alter negative changes in PSII parameters (donor side, acceptor side and reaction center QA under heat stress. Following heat treatment, the recovery of Pn in SA-treated leaves was accelerated compared with the control (H2O-treated leaves, and, donor and acceptor parameters of PSII in SA-treated leaves recovered to normal levels more rapidly than in the controls. Rubisco, however, was not significantly (P Conclusion SA pretreatment alleviated the heat stress induced decrease in Pn mainly through maintaining higher Rubisco activition state, and it accelerated the recovery of Pn mainly through effects on PSII function. These effects of SA may be related in part to enhanced levels of HSP21.

U.S. advanced accelerator applications program: plans to develop and test waste transmutation technologies

International Nuclear Information System (INIS)

Van Tuyle, G.; Bennett, D.; Arthur, E.; Cappiello, M.; Finck, P.; Hill, D.; Herczeg, J.; Goldner, F.

2001-01-01

The primary mission of the U.S. Advanced Accelerator Applications (AAA) Program is to establish a national nuclear technology research capability that can demonstrate accelerator-based transmutation of waste and conduct transmutation research while at the same time providing a capability for the production of tritium if required. The AAA Program was created during fiscal year 2001 from the Accelerator Transmutation of Waste (ATW) Program and the Accelerator Production of Tritium (APT) Project. This paper describes the new AAA Program, as well as its two major components: development and testing of waste transmutation technologies and construction of an integrated accelerator-driven test facility (ADTF). (author)

Stress testing in financial institutions

Directory of Open Access Journals (Sweden)

Mirković Vladimir

2014-01-01

Full Text Available In 2000 the Basle Committee on the Global Financial System defined stress testing as 'a generic term describing various techniques used by financial firms to gauge their potential vulnerability to exceptional but plausible events'. Exceptional events refer to one-off or recurring events with far-reaching consequences for the concerned financial institution and the financial sector s stability overall. Such unexpected (exceptional events include, for instance: bankruptcy in Argentina in 2001, stock markets collapse ('Black Monday' on 19 October 1987, or the fall of the energy giant Enron in 2001. The adoption of the new Basle Accord (better known as Basle II in 2001 envisaged the implementation of stress tests for the identification of events and future changes in economic circumstances that could cause some unfavorable effects on banks' credit exposure, along with the assessment of banks' ability to survive in the new circumstances. Negative experiences from the past, having undermined the stability of financial systems worldwide, made a decisive impact on regulators at all levels to additionally consider the issue of increasing the financial system's resistance to the occurrence of unexpected - exceptional events. To this end, the introduction of stress tests was the turning point in the process of increased banking systems' resistance to shocks. This paper primarily deals with stress testing methodology and bank risk measurement techniques, along with the main results of conducted tests, directly impacting the entire financial system.

What Is Stress Testing?

Science.gov (United States)

... would during exercise. You can then have the stress test. The medicine may make you flushed and anxious, but the effects go away as soon as the test is over. The medicine also may give you a headache. While you're exercising or getting medicine to ...

Leveraging accelerated testing of LED drivers to model the reliability of two-stage and multi-channel drivers

Energy Technology Data Exchange (ETDEWEB)

Davis, Lynn; Perkins, Curtis; Smith, Aaron; Clark, Terry; Mills, Karmann

2017-05-30

The next wave of LED lighting technology is likely to be tunable white lighting (TWL) devices which can adjust the colour of the emitted light between warm white (~ 2700 K) and cool white (~ 6500 K). This type of lighting system uses LED assemblies of two or more colours each controlled by separate driver channels that independently adjust the current levels to achieve the desired lighting colour. Drivers used in TWL devices are inherently more complex than those found in simple SSL devices, due to the number of electrical components in the driver required to achieve this level of control. The reliability of such lighting systems can only be studied using accelerated stress tests (AST) that accelerate the aging process to time frames that can be accommodated in laboratory testing. This paper describes AST methods and findings developed from AST data that provide insights into the lifetime of the main components of one-channel and multi-channel LED devices. The use of AST protocols to confirm product reliability is necessary to ensure that the technology can meet the performance and lifetime requirements of the intended application.

An Integration Testing Facility for the CERN Accelerator Controls System

CERN Document Server

Stapley, N; Bau, J C; Deghaye, S; Dehavay, C; Sliwinski, W; Sobczak, M

2009-01-01

A major effort has been invested in the design, development, and deployment of the LHC Control System. This large control system is made up of a set of core components and dependencies, which although tested individually, are often not able to be tested together on a system capable of representing the complete control system environment, including hardware. Furthermore this control system is being adapted and applied to CERN's whole accelerator complex, and in particular for the forthcoming renovation of the PS accelerators. To ensure quality is maintained as the system evolves, and toimprove defect prevention, the Controls Group launched a project to provide a dedicated facility for continuous, automated, integration testing of its core components to incorporate into its production process. We describe the project, initial lessons from its application, status, and future directions.

Scientists confirm delay in testing new CERN particle accelerator

CERN Multimedia

2007-01-01

"Scientists seeking to uncover the secrets of the universe will have to wait a little longer after the CERN laboratory inswitzerland on Monday confirmed a delay in tests of a massive new particle accelerator." (1 page)

Stress Testing as a Tool of Bank Risk Management

Directory of Open Access Journals (Sweden)

Antonyuk Oksana I.

2013-12-01

Full Text Available The goal of the article is development of theoretical, methodological and practical recommendations on the use of stress testing by Ukrainian commercial banks. Stress testing is defined as a part of bank risk management on the basis of scientific studies of domestic and foreign scientists. The article marks the essence of the bank stress testing and identifies its role in the structure of banks’ risk management in Ukraine. It considers goals of conducting stress testing in banking institutions. It identifies main aspects and specific features of conducting stress testing of bank risks. It characterises main advantages and shortcomings of use of stress testing in the modern bank risk management. It generalises the world and European approaches to the methods of conducting stress testing in commercial banks in comparison with the Ukrainian methodical recommendations. It shows that results of stress testing have practical value, since they help to preliminary assess influence of potentially negative events upon the state of the loan portfolio of the bank and make relevant managerial decisions.

Testing a Fourier Accelerated Hybrid Monte Carlo Algorithm

OpenAIRE

Catterall, S.; Karamov, S.

2001-01-01

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.

Stress corrosion cracking evaluation of precipitation-hardening stainless steel

Science.gov (United States)

Humphries, T. S.; Nelson, E. E.

1970-01-01

Accelerated test program results show which precipitation hardening stainless steels are resistant to stress corrosion cracking. In certain cases stress corrosion susceptibility was found to be associated with the process procedure.

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

Science.gov (United States)

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

2014-08-01

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.

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

International Nuclear Information System (INIS)

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

1984-01-01

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

Panel manipulation in social stress testing:The Bath experimental stress test for children (BEST-C)

OpenAIRE

Cheetham, Tara J.; Turner-Cobb, Julie M.

2016-01-01

BackgroundWhilst acute stress paradigms in adults make use of adult panel members, similar paradigms modified for child participants have not manipulated the panel. Most work has utilised an audience of adult confederates, regardless of the age of the population being tested. The aim of this study was to trial a social stress test for children that provided a meaningful environment using age-matched child peers as panel actors.MethodsThirty-three participants (7-11 years) underwent the Bath E...

Environmental Exposure and Accelerated Testing of Rubber-to-Metal Vulcanized Bonded Assemblies

Science.gov (United States)

1974-11-01

btadiene/acrylonitrile ( NBR ) rubber -to-metat -. canized bonded assemblies at the two exposure sites are shown in Table 5. After exposure for one year...AD-A0-17 368 EN~VIRONMENTAL EXPOSURE AND ACCELERATED TESTING OF RUBBER -TO-METAL VULCANIZED BONDED ASSEMBLIES John A. WilliamsI Rock Island Arseital...COMMERCE 325116 1AD R-TR-75-013 ENViRONMENTAL EXPOSURE AND ACCELERATED TESTING OF RUBBER -TO-METAL VULCANIZED BONDED ASSEMBLIES by __ John A. Williams

A Randomized Comparative Study Evaluating Various Cough Stress Tests and 24-Hour Pad Test with Urodynamics in the Diagnosis of Stress Urinary Incontinence.

Science.gov (United States)

Henderson, Joseph W; Kane, Sarah M; Mangel, Jeffrey M; Kikano, Elias G; Garibay, Jorge A; Pollard, Robert R; Mahajan, Sangeeta T; Debanne, Sara M; Hijaz, Adonis K

2018-06-01

The cough stress test is a common and accepted tool to evaluate stress urinary incontinence but there is no agreement on how the test should be performed. We assessed the diagnostic ability of different cough stress tests performed when varying patient position and bladder volume using urodynamic stress urinary incontinence as the gold standard. The 24-hour pad test was also evaluated. We recruited women who presented to specialty outpatient clinics with the complaint of urinary incontinence and who were recommended to undergo urodynamic testing. A total of 140 patients were randomized to 4 cough stress test groups, including group 1-a comfortably full bladder, group 2-an empty bladder, group 3- a bladder infused with 200 cc saline and group 4-a bladder filled to half functional capacity. The sequence of standing and sitting was randomly assigned. The groups were compared by 1-way ANOVA or the generalized Fisher exact test. The κ statistic was used to evaluate agreement between the sitting and standing positions. The 95% CIs of sensitivity and specificity were calculated using the Wilson method. ROC analysis was done to evaluate the performance of the 24-hour pad test. The cough stress test performed with a bladder filled to half functional capacity was the best performing test with 83% sensitivity and 90% specificity. There was no statistically significant evidence that the sensitivity or specificity of 1 cough stress test differed from that of the others. The pad test had no significant predictive ability to diagnose urodynamic stress urinary incontinence (AUC 0.60, p = 0.08). Cough stress tests were accurate to diagnose urodynamic stress urinary incontinence. The 24-hour pad test was not predictive of urodynamic stress urinary incontinence and not helpful when used in conjunction with the cough stress test. Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Accelerated aging tests of liners for uranium mill tailings disposal

International Nuclear Information System (INIS)

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

1981-11-01

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

Benefits of Considering More than Temperature Acceleration for GaN HEMT Life Testing

Directory of Open Access Journals (Sweden)

Ronald A. Coutu

2016-06-01

Full Text Available The purpose of this work was to investigate the validity of Arrhenius accelerated-life testing when applied to gallium nitride (GaN high electron mobility transistors (HEMT lifetime assessments, where the standard assumption is that only critical stressor is temperature, which is derived from operating power, device channel-case, thermal resistance, and baseplate temperature. We found that power or temperature alone could not explain difference in observed degradation, and that accelerated life tests employed by industry can benefit by considering the impact of accelerating factors besides temperature. Specifically, we found that the voltage used to reach a desired power dissipation is important, and also that temperature acceleration alone or voltage alone (without much power dissipation is insufficient to assess lifetime at operating conditions.

40 CFR 90.329 - Catalyst thermal stress test.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress test. 90.329... Equipment Provisions § 90.329 Catalyst thermal stress test. (a) Oven characteristics. The oven used for thermally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000 ±10...

40 CFR 91.329 - Catalyst thermal stress test.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress test. 91.329....329 Catalyst thermal stress test. (a) Oven characteristics. The oven used for termally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000 ±10 °C. (b) Evaluation...

Induction accelerator test module for HIF

International Nuclear Information System (INIS)

Faltens, A.

1991-04-01

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

An induction accelerator for the Heidelberg Test Storage Ring TSR

International Nuclear Information System (INIS)

Ellert, C.; Habs, D.; Music, M.; Schwalm, D.; Wolf, A.; Jaeschke, E.; Kambara, T.; Sigray, P.

1992-01-01

An induction accelerator has been installed in the heavy ion test storage ring TSR in Heidelberg. It allows for constant acceleration or deceleration of stored coasting ion beams without affecting their velocity profile and is well suited for ion beam manipulation in cooling experiments and for measurements of velocity dependent cooling forces. The design and operation of the device and first applications to laser cooling and to measurements of laser and electron cooling forces are described. (orig.)

Accelerated pavement testing efforts using the heavy vehicle simulator

CSIR Research Space (South Africa)

Du Plessis, Louw

2017-10-01

Full Text Available This paper provides a brief description of the technological developments involved in the development and use of the Heavy Vehicle Simulator (HVS) accelerated pavement testing equipment. This covers the period from concept in the late 1960’s...

Nondestructive Evaluation and Monitoring Results from COPV Accelerated Stress Rupture Testing, NASA White Sands Test Facility (WSTF)

Science.gov (United States)

Saulsberry Regor

2010-01-01

Develop and demonstrate NDE techniques for real-time characterization of CPVs and, where possible, identification of NDE capable of assessing stress rupture related strength degradation and/or making vessel life predictions (structural health monitoring or periodic inspection modes). Secondary: Provide the COPV user and materials community with quality carbon/epoxy (C/Ep) COPV stress rupture progression rate data. Aid in modeling, manufacturing, and application of COPVs for NASA spacecraft.

Verification of mechanistic-empirical design models for flexible pavements through accelerated pavement testing : technical summary.

Science.gov (United States)

2014-08-01

Midwest States Accelerated Pavement Testing Pooled-Fund Program, financed by the : highway departments of Kansas, Iowa, and Missouri, has supported an accelerated : pavement testing (APT) project to validate several models incorporated in the NCHRP :...

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

Science.gov (United States)

Ghaffarian, Reza; Evans, John W.

2014-01-01

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.

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

Energy Technology Data Exchange (ETDEWEB)

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

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.

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

Science.gov (United States)

Congedo, Giuseppe

2015-03-01

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 nongravitational spurious forces. This last contribution is going to be characterized 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's 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 marginalize over nuisance parameters. The F statistic, in widespread use throughout the gravitation waves community, is included in the method and suitably generalized to marginalize 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.

Test of the law of gravitation at small accelerations

Energy Technology Data Exchange (ETDEWEB)

Meyer, H. [Wuppertal Univ. (Germany); Lohrmann, E.; Schubert, S. [Hamburg Univ. (Germany). Inst. fuer Experimentalphysik; Bartel, W.; Glazov, A.; Loehr, B.; Niebuhr, C.; Wuensch, E. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Joensson, L.; Kempf, G. [Lund Univ. (Sweden)

2011-12-15

Newton's Law of Gravitation has been tested at small values a of the acceleration, down to a {approx}10{sup -10} ms{sup -2}, the approximate value of MOND's constant a{sub 0}. No deviations were found. (orig.)

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

International Nuclear Information System (INIS)

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

2014-01-01

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

The Brookhaven Accelerator Test Facility

International Nuclear Information System (INIS)

Batchelor, K.; Chou, T.S.; Fernow, R.C.

1988-01-01

The Brookhaven Accelerator Test Facility (ATF) will consist of a 50--100 MeV/c electron linac and a 100 GW CO 2 laser system. A high brightness RF-gun operating at 2856 MHz is to be used as the injector into the linac. The RF-gun contains a Nd:Yag-laser-driven photocathode capable of producing a stream of six ps electron pulses separated by 12.5 ns. The maximum charge in a micropulse will be one nano-Coulomb. The CO 2 laser pulse length will be a few picoseconds and will be synchronized with the electron pulse. The first experimental beam is expected in Fall 89. The design electron beam parameters are given and possible initial experiments are discussed. 9 refs., 1 fig., 3 tabs

Beam Profile Measurement of 300 kV Ion Source Test Stand for 1 MV Electrostatic Accelerator

International Nuclear Information System (INIS)

Park, Sae-Hoon; Kim, Yu-Seok; Kim, Dae-Il; Kwon, Hyeok-Jung; Cho, Yong-Sub

2015-01-01

In this paper, RF ion source, test stand of the ion source and its test results are presented. Beam profile was measured at the downstream from the accelerating tube and at the beam dump by using BPM and wire scanner. The RF ion source of the test stand is verified by measuring the total beam current with a faraday cup in the chamber. The KOMAC (KOrea Multi-purpose Accelerator Complex) has been developing a 300 kV ion source test stand for a 1 MV electrostatic accelerator. An ion source and accelerating tube will be installed in a high pressure vessel. The ion source in a high pressure vessel requires high reliability. To confirm the stable operation of the ion source, a test stand was proposed and developed. The ion source will be tested at the test stand to verify its long-term operation conditions. The test stand consists of a 300 kV high voltage terminal, a battery for the ion source power, a 60 Hz inverter, a 200 MHz RF power, a 5 kV extraction power supply, a 300 kV accelerating tube, and a vacuum system. The beam profile monitor was installed at the downstream from the accelerating tube. Wire scanner and faraday-cup was installed at the end of the chamber

Beam Profile Measurement of 300 kV Ion Source Test Stand for 1 MV Electrostatic Accelerator

Energy Technology Data Exchange (ETDEWEB)

Park, Sae-Hoon; Kim, Yu-Seok [Dongguk University, Gyeonju (Korea, Republic of); Kim, Dae-Il; Kwon, Hyeok-Jung; Cho, Yong-Sub [Korea Multipurpose Accelerator Complex, Gyeongju (Korea, Republic of)

2015-10-15

In this paper, RF ion source, test stand of the ion source and its test results are presented. Beam profile was measured at the downstream from the accelerating tube and at the beam dump by using BPM and wire scanner. The RF ion source of the test stand is verified by measuring the total beam current with a faraday cup in the chamber. The KOMAC (KOrea Multi-purpose Accelerator Complex) has been developing a 300 kV ion source test stand for a 1 MV electrostatic accelerator. An ion source and accelerating tube will be installed in a high pressure vessel. The ion source in a high pressure vessel requires high reliability. To confirm the stable operation of the ion source, a test stand was proposed and developed. The ion source will be tested at the test stand to verify its long-term operation conditions. The test stand consists of a 300 kV high voltage terminal, a battery for the ion source power, a 60 Hz inverter, a 200 MHz RF power, a 5 kV extraction power supply, a 300 kV accelerating tube, and a vacuum system. The beam profile monitor was installed at the downstream from the accelerating tube. Wire scanner and faraday-cup was installed at the end of the chamber.

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

Science.gov (United States)

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

2015-04-01

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 1.18 mm 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 μm). 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. Copyright © 2015 Elsevier B.V. All rights reserved.

Liquid salt environment stress-rupture testing

Science.gov (United States)

Ren, Weiju; Holcomb, David E.; Muralidharan, Govindarajan; Wilson, Dane F.

2016-03-22

Disclosed herein are systems, devices and methods for stress-rupture testing selected materials within a high-temperature liquid salt environment. Exemplary testing systems include a load train for holding a test specimen within a heated inert gas vessel. A thermal break included in the load train can thermally insulate a load cell positioned along the load train within the inert gas vessel. The test specimen can include a cylindrical gage portion having an internal void filled with a molten salt during stress-rupture testing. The gage portion can have an inner surface area to volume ratio of greater than 20 to maximize the corrosive effect of the molten salt on the specimen material during testing. Also disclosed are methods of making a salt ingot for placement within the test specimen.

AAPM Medical Physics Practice Guideline 8.a.: Linear accelerator performance tests.

Science.gov (United States)

Smith, Koren; Balter, Peter; Duhon, John; White, Gerald A; Vassy, David L; Miller, Robin A; Serago, Christopher F; Fairobent, Lynne A

2017-07-01

The purpose of this guideline is to provide a list of critical performance tests in order to assist the Qualified Medical Physicist (QMP) in establishing and maintaining a safe and effective quality assurance (QA) program. The performance tests on a linear accelerator (linac) should be selected to fit the clinical patterns of use of the accelerator and care should be given to perform tests which are relevant to detecting errors related to the specific use of the accelerator. A risk assessment was performed on tests from current task group reports on linac QA to highlight those tests that are most effective at maintaining safety and quality for the patient. Recommendations are made on the acquisition of reference or baseline data, the establishment of machine isocenter on a routine basis, basing performance tests on clinical use of the linac, working with vendors to establish QA tests and performing tests after maintenance. The recommended tests proposed in this guideline were chosen based on the results from the risk analysis and the consensus of the guideline's committee. The tests are grouped together by class of test (e.g., dosimetry, mechanical, etc.) and clinical parameter tested. Implementation notes are included for each test so that the QMP can understand the overall goal of each test. This guideline will assist the QMP in developing a comprehensive QA program for linacs in the external beam radiation therapy setting. The committee sought to prioritize tests by their implication on quality and patient safety. The QMP is ultimately responsible for implementing appropriate tests. In the spirit of the report from American Association of Physicists in Medicine Task Group 100, individual institutions are encouraged to analyze the risks involved in their own clinical practice and determine which performance tests are relevant in their own radiotherapy clinics. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on

Scintigraphic ventriculography and stress testing

International Nuclear Information System (INIS)

Goris, M.L.; Hung, J.; Debusk, R.F.

1982-01-01

Scintigraphic stress ventriculography yields information which is complex and defies description by the difference in ejection fraction between rest and maximum exercise only. The complexity results in part from the ''derived'' nature of the ejection fraction measurement, which is physiologically secondary to stroke volume and end-diastolic volume. Furthermore, the nature of the stress test in which the pulse (stress) is not independent from the response forces an analysis which considers ''when'' as much as ''what'' happens. Automation in data processing, however, has made oversimplification unnecessary and allows a more exhaustive but correct analysis

Female False Positive Exercise Stress ECG Testing - Fact Verses Fiction.

Science.gov (United States)

Fitzgerald, Benjamin T; Scalia, William M; Scalia, Gregory M

2018-03-07

Exercise stress testing is a well validated cardiovascular investigation. Accuracy for treadmill stress electrocardiograph (ECG) testing has been documented at 60%. False positive stress ECGs (exercise ECG changes with non-obstructive disease on anatomical testing) are common, especially in women, limiting the effectiveness of the test. This study investigates the incidence and predictors of false positive stress ECG findings, referenced against stress echocardiography (SE) as a standard. Stress echocardiography was performed using the Bruce treadmill protocol. False positive stress ECG tests were defined as greater than 1mm of ST depression on ECG during exertion, without pain, with a normal SE. Potential causes for false positive tests were recorded before the test. Three thousand consecutive negative stress echocardiograms (1036 females, 34.5%) were analysed (age 59+/-14 years. False positive (F+) stress ECGs were documented in 565/3000 tests (18.8%). F+ stress ECGs were equally prevalent in females (194/1036, 18.7%) and males (371/1964, 18.9%, p=0.85 for the difference). Potential causes (hypertension, left ventricular hypertrophy, known coronary disease, arrhythmia, diabetes mellitus, valvular heart disease) were recorded in 36/194 (18.6%) of the female F+ ECG tests and 249/371 (68.2%) of the male F+ ECG tests (preinforce the value of stress imaging, particularly in women. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). All rights reserved.

[Characteristics of the sympathoadrenal system response to psychoemotional stress under hypoxic conditions in aged people with physiological and accelerated aging of the respiratory system].

Science.gov (United States)

Asanov, E O; Os'mak, Ie D; Kuz'mins'ka, L A

2013-01-01

The peculiarities of the response of the sympathoadrenal system to psychoemotional and hypoxic stress in healthy young people and in aged people with physiological and accelerated aging of respiratory system were studied. It was shown that in aging a more pronounced response of the sympathoadrenal system to psychoemotional stress. At the same time, elderly people with different types of aging of the respiratory system did not demonstrate a difference in the response of the sympathoadrenal system to psychoemotional stress. Unlike in young people, in aged people, combination of psychoemotional and hypoxic stresses resulted in further activation of the sympathoadrenal system. The reaction of the sympathoadrenal system was more expressed in elderly people with accelerated ageing of the respiratory system.

Development and evaluation of accelerated drug release testing methods for a matrix-type intravaginal ring.

Science.gov (United States)

Externbrink, Anna; Eggenreich, Karin; Eder, Simone; Mohr, Stefan; Nickisch, Klaus; Klein, Sandra

2017-01-01

Accelerated drug release testing is a valuable quality control tool for long-acting non-oral extended release formulations. Currently, several intravaginal ring candidates designed for the long-term delivery of steroids or anti-infective drugs are being in the developing pipeline. The present article addresses the demand for accelerated drug release methods for these formulations. We describe the development and evaluation of accelerated release methods for a steroid releasing matrix-type intravaginal ring. The drug release properties of the formulation were evaluated under real-time and accelerated test conditions. Under real-time test conditions drug release from the intravaginal ring was strongly affected by the steroid solubility in the release medium. Under sufficient sink conditions that were provided in release media containing surfactants drug release was Fickian diffusion driven. Both temperature and hydro-organic dissolution media were successfully employed to accelerate drug release from the formulation. Drug release could be further increased by combining the temperature effect with the application of a hydro-organic release medium. The formulation continued to exhibit a diffusion controlled release kinetic under the investigated accelerated conditions. Moreover, the accelerated methods were able to differentiate between different prototypes of the intravaginal ring that exhibited different release profiles under real-time test conditions. Overall, the results of the present study indicate that both temperature and hydro-organic release media are valid parameters for accelerating drug release from the intravaginal ring. Variation of either a single or both parameters yielded release profiles that correlated well with real-time release. Copyright © 2016 Elsevier B.V. All rights reserved.

High Power Test of an X-Band Slotted-IRIS Accelerator Structure at NLCTA

International Nuclear Information System (INIS)

Doebert, S.; Fandos, R.; Grudiev, A.; Heikkinen, S.; Rodriquez, J.A.; Taborelli, M.; Wuensch, W.; Adolphsen, Chris E.; Laurent, L.

2007-01-01

The CLIC study group at CERN has built two X-band HDS (hybrid damped structure) accelerating structures for high-power testing in NLCTA at SLAC. These accelerating structures are novel with respect to their rf- design and their fabrication technique. The eleven-cell constant impedance structures, one made out of copper and one out of molybdenum, are assembled from clamped high-speed milled quadrants. They feature the same heavy higher-order-mode damping as nominal CLIC structures achieved by slotted irises and radial damping waveguides for each cell. The X-band accelerators are exactly scaled versions of structures tested at 30 GHz in the CLIC test facility, CTF3. The results of the X-band tests are presented and compared to those at 30 GHz to determine frequency scaling, and are compared to the extensive copper data from the NLC structure development program to determine material dependence and make a basic validation of the HDS design

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

Science.gov (United States)

Goodman, L. A.

1976-01-01

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.

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

International Nuclear Information System (INIS)

Mann, F.M.

1988-08-01

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

Degradation mechanisms and accelerated testing in PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

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

2010-01-01

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

The Brookhaven Accelerator Test Facility

International Nuclear Information System (INIS)

Batchelor, K.; Chou, T.S.; Fernow, R.C.; Fischer, J.; Gallardo, J.; Kirk, H.G.; Koul, R.; Palmer, R.B.; Pellegrini, C.; Sheehan, J.; Srinivasan-Rao, T.; Ulc, S.; Woodle, M.; Bigio, I.; Kurnit, N.; McDonald, K.T.

1989-01-01

The Brookhaven Accelerator Test Facility ATF will consist of a 50-100 MeV/c electron linac and a 100 GW CO 2 laser system. A high brightness RF-gun operating at 2,856 MHz is to be used as the injector into the linac. The RF-gun contains a Nd:Yag-laser-driven photocathode capable of producing a stream of six ps electron pulses separated by 12.5 ns. The maximum charge in a micropulse will be one nano-Coulomb. The CO 2 laser pulse length will be a few picoseconds and will be synchronized with the electron pulse. The first experimental beam is expected in Fall 89. The design electron beam parameters are given and possible initial experiments are discussed. 9 refs., 1 fig., 3 tabs

Triaxial Wetting Test on Rockfill Materials under Stress Combination Conditions of Spherical Stress p and Deviatoric Stress q

Directory of Open Access Journals (Sweden)

Yan-yi Zhang

2018-01-01

Full Text Available A GCTS medium-sized triaxial apparatus is used to conduct a single-line method wetting test on three kinds of rockfill materials of different mother rocks such as mixture of sandstone and slate, and dolomite and granite, and the test stress conditions is the combination of spherical stress p and deviatoric stress q. The test results show that (1 for wetting shear strain, the effects of spherical stress p and deviatoric stress q are equivalent, and wetting shear strain and deviatoric stress q show the power function relationship preferably. (2 For wetting volumetric strain, the effect of deviatoric stress q can be neglected because it is extremely insignificant, and spherical stress p is the main influencing factor and shows the power function relationship preferably. (3 The wetting strains decrease significantly with the increase in initial water content and sample density generally, but the excessively high dry density will increase the wetting deformation. Also, the wetting strains will decrease with the increase in the saturated uniaxial compressive strength and average softening coefficient of the mother rock. Based on the test results, a wetting strain model is proposed for rockfill materials. The verification results indicate that the model satisfactorily reflects the development law of wetting deformation.

A reproducible accelerated in vitro release testing method for PLGA microspheres.

Science.gov (United States)

Shen, Jie; Lee, Kyulim; Choi, Stephanie; Qu, Wen; Wang, Yan; Burgess, Diane J

2016-02-10

The objective of the present study was to develop a discriminatory and reproducible accelerated in vitro release method for long-acting PLGA microspheres with inner structure/porosity differences. Risperidone was chosen as a model drug. Qualitatively and quantitatively equivalent PLGA microspheres with different inner structure/porosity were obtained using different manufacturing processes. Physicochemical properties as well as degradation profiles of the prepared microspheres were investigated. Furthermore, in vitro release testing of the prepared risperidone microspheres was performed using the most common in vitro release methods (i.e., sample-and-separate and flow through) for this type of product. The obtained compositionally equivalent risperidone microspheres had similar drug loading but different inner structure/porosity. When microsphere particle size appeared similar, porous risperidone microspheres showed faster microsphere degradation and drug release compared with less porous microspheres. Both in vitro release methods investigated were able to differentiate risperidone microsphere formulations with differences in porosity under real-time (37 °C) and accelerated (45 °C) testing conditions. Notably, only the accelerated USP apparatus 4 method showed good reproducibility for highly porous risperidone microspheres. These results indicated that the accelerated USP apparatus 4 method is an appropriate fast quality control tool for long-acting PLGA microspheres (even with porous structures). Copyright © 2015 Elsevier B.V. All rights reserved.

Testing the stress shadow hypothesis

Science.gov (United States)

Felzer, Karen R.; Brodsky, Emily E.

2005-05-01

A fundamental question in earthquake physics is whether aftershocks are predominantly triggered by static stress changes (permanent stress changes associated with fault displacement) or dynamic stresses (temporary stress changes associated with earthquake shaking). Both classes of models provide plausible explanations for earthquake triggering of aftershocks, but only the static stress model predicts stress shadows, or regions in which activity is decreased by a nearby earthquake. To test for whether a main shock has produced a stress shadow, we calculate time ratios, defined as the ratio of the time between the main shock and the first earthquake to follow it and the time between the last earthquake to precede the main shock and the first earthquake to follow it. A single value of the time ratio is calculated for each 10 × 10 km bin within 1.5 fault lengths of the main shock epicenter. Large values of the time ratio indicate a long wait for the first earthquake to follow the main shock and thus a potential stress shadow, whereas small values indicate the presence of aftershocks. Simulations indicate that the time ratio test should have sufficient sensitivity to detect stress shadows if they are produced in accordance with the rate and state friction model. We evaluate the 1989 MW 7.0 Loma Prieta, 1992 MW 7.3 Landers, 1994 MW 6.7 Northridge, and 1999 MW 7.1 Hector Mine main shocks. For each main shock, there is a pronounced concentration of small time ratios, indicating the presence of aftershocks, but the number of large time ratios is less than at other times in the catalog. This suggests that stress shadows are not present. By comparing our results to simulations we estimate that we can be at least 98% confident that the Loma Prieta and Landers main shocks did not produce stress shadows and 91% and 84% confident that stress shadows were not generated by the Hector Mine and Northridge main shocks, respectively. We also investigate the long hypothesized existence

Chronic stress accelerates ligature-induced periodontitis by suppressing glucocorticoid receptor-α signaling.

Science.gov (United States)

Lu, Huaixiu; Xu, Minguang; Wang, Feng; Liu, Shisen; Gu, Jing; Lin, Songshan; Zhao, Lisheng

2016-03-25

Periodontitis is a common chronic inflammatory disease. Recent studies have shown that chronic stress (CS) might modulate periodontal disease, but there are few models of CS-induced periodontitis, and the underlying mechanisms are unclear. The present study established a rat model of periodontitis associated with CS induced by nylon thread ligatures. The severity of periodontitis was evaluated in this model by radiographic and pathological examination. The inflammatory reaction indicated by the elevated serum levels of interleukin (IL)-1β, IL-6 and IL-8 was assessed by enzyme-linked immunosorbent assay. Toll-like receptor-4 (TLR4) and glucocorticoid receptor-α (GR-α) expressions were detected by reverse transcriptase-PCR and western blotting. Open-field tests and serum corticosterone were used to evaluate CS. The results showed that CS induced behavioral changes and increased corticosterone levels of the animals with periodontitis. CS stimulation markedly increased alveolar bone loss, periodontal pocket depth and the number of plaques. It also enhanced the inflammatory reaction. These results suggest that CS accelerated the ligature-induced pathological changes associated with periodontitis. Further analysis of the mechanisms involved showed that GR-α expression was significantly downregulated in periodontal tissues of the animals undergoing CS. Blocking GR-α signaling in lipopolysaccharide and corticosteroid-treated human periodontal ligament fibroblast cells in vitro significantly upregulated the expression of p-Akt (protein kinase B) and TLR4, promoted nuclear factor-κB activity and increased levels of IL-1β, IL-6 and IL-8. This research suggests that CS might accelerate the pathological progression of periodontitis by a GR-α signaling-mediated inflammatory response and that this may be a potential therapeutic target for the treatment of periodontal disease, particularly in patients with CS.

Commissioning of the Ground Test Accelerator Intertank Matching Section

International Nuclear Information System (INIS)

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

1992-01-01

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

Accelerated Testing of UH-60 Viscous Bearings for Degraded Grease Fault

Science.gov (United States)

Dykas, Brian; Hood, Adrian; Krantz, Timothy; Klemmer, Marko

2015-01-01

An accelerated aging investigation of critical aviation bearings lubricated with MIL-PRF- 81322 grease was conducted to derive an understanding of the mechanisms of grease degradation and loss of lubrication over time. The current study focuses on UH-60 Black Hawk viscous damper bearings supporting the tail rotor driveshaft, which were subjected to more than 5800 hours of testing in a heated environment to accelerate the deterioration of the grease. The mechanism of grease degradation is a reduction in the oil/thickener ratio rather than the expected chemical degradation of grease constituents. Over the course of testing, vibration and temperature monitoring of bearings was conducted and trends for failing bearings are presented.

Plain bearing stresses due to forming and oil film pressure

International Nuclear Information System (INIS)

Burke-Veliz, A; Reed, P A S; Syngellakis, S; Wang, D; Wahdy, N; Merritt, D

2009-01-01

This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

Plain bearing stresses due to forming and oil film pressure

Energy Technology Data Exchange (ETDEWEB)

Burke-Veliz, A; Reed, P A S; Syngellakis, S [University of Southampton, School of Engineering Sciences, Southampton SO17 1BJ (United Kingdom); Wang, D; Wahdy, N; Merritt, D, E-mail: allan.burke@itesm.m [MAHLE Engine Systems UK Ltd, 2 Central park Drive, Rugby CV23 0WE (United Kingdom)

2009-08-01

This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

Development of an accelerated test for Internal Sulfate Attack study

Directory of Open Access Journals (Sweden)

Khelil Nacim

2014-04-01

Full Text Available Internal Sulfate Attack (ISA is a pathology that occurs under certain conditions in concrete having undergone heating above 70 °C at early age (through heating in pre-casting industry or due to hydration in large concrete parts. This reaction deemed very slow, numerous methods to speed up reactions leading to delayed ettringite formation have been developed. These methods are all based on the material damage. Another type of test is currently under development. It is based on rehabilitation techniques such as electrochemical chloride extraction (ECE in order to accelerate the leaching of alkalis that could be one of the triggers of the pathology. The study presented in this paper focused on concrete specimens prepared from cement (CEM I 52.5 N enriched with Na2SO4. These concretes have undergone a heat treatment typical of those used in precast plants (up to 24 hours with a maximum temperature of 80 °C. Various paths were explored for the development of the accelerated test. The first results showed that it was necessary to use a removable titanium anode ruthenium anode instead of stainless steel embedded in the concrete. Then tests with de-ionized water as the solute to the cathode did not accelerate the onset of expansions. The experiment has been modified and potassium carbonate was added to the solution. This modification didn’t show any significant improvement, and other experiments are being carried out to explain this result.

Have you stress tested your assay?

Directory of Open Access Journals (Sweden)

Zheng Cao

2016-08-01

Full Text Available Objectives: When a clinical assay is stressed with extraordinarily high volume of specimens over a short period of time, extra caution may be needed to avoid systematic errors and biases. Here we report our experience with a HgbA1c assay used for high volume wellness screening purpose, to illustrate the importance of stress testing during assay validation. Design and Methods: Over 15,000 whole blood specimens were tested for HgbA1c in a period of 2 months. HgbA1c was tested by an immunoturbidimetric method on a high through-put automation line. The HgbA1c population distribution in our study was compared to that from the NHANES database. Daily distributions of HgbA1c values ≥6%, means and medians were plotted. Correlation studies were performed between the high through-put immunoturbidimetric assay and a medium through-put HPLC method. Results: We observed a shift of HgbA1c distribution to the higher values compared to the NHANES. A bias of 15–20% was noted from further stress testing where large number of samples were batched and tested using the immunoturbidimetric assay. A 5–7% higher bias remained after implementing a cuvette washing program after each HgbA1c sample. We hypothesized this bias was caused by build-up of blood cell fragments in the cuvettes when continuous whole blood samples are run through the system. Our experience suggests stress testing needs to be incorporated early in the test validation process for high volume batched screening applications. This seemingly extra validation step may save significant troubleshooting and retesting efforts down the road. Keywords: Hemoglobin A1c, Immunoturbidimetric assay, HPLC, Quality assurance, Systematic bias, High volume, Automation

Accelerated Aging in Electrolytic Capacitors for Prognostics

Science.gov (United States)

Celaya, Jose R.; Kulkarni, Chetan; Saha, Sankalita; Biswas, Gautam; Goebel, Kai Frank

2012-01-01

The focus of this work is the analysis of different degradation phenomena based on thermal overstress and electrical overstress accelerated aging systems and the use of accelerated aging techniques for prognostics algorithm development. Results on thermal overstress and electrical overstress experiments are presented. In addition, preliminary results toward the development of physics-based degradation models are presented focusing on the electrolyte evaporation failure mechanism. An empirical degradation model based on percentage capacitance loss under electrical overstress is presented and used in: (i) a Bayesian-based implementation of model-based prognostics using a discrete Kalman filter for health state estimation, and (ii) a dynamic system representation of the degradation model for forecasting and remaining useful life (RUL) estimation. A leave-one-out validation methodology is used to assess the validity of the methodology under the small sample size constrain. The results observed on the RUL estimation are consistent through the validation tests comparing relative accuracy and prediction error. It has been observed that the inaccuracy of the model to represent the change in degradation behavior observed at the end of the test data is consistent throughout the validation tests, indicating the need of a more detailed degradation model or the use of an algorithm that could estimate model parameters on-line. Based on the observed degradation process under different stress intensity with rest periods, the need for more sophisticated degradation models is further supported. The current degradation model does not represent the capacitance recovery over rest periods following an accelerated aging stress period.

Accounting for measurement error in log regression models with applications to accelerated testing.

Science.gov (United States)

Richardson, Robert; Tolley, H Dennis; Evenson, William E; Lunt, Barry M

2018-01-01

In regression settings, parameter estimates will be biased when the explanatory variables are measured with error. This bias can significantly affect modeling goals. In particular, accelerated lifetime testing involves an extrapolation of the fitted model, and a small amount of bias in parameter estimates may result in a significant increase in the bias of the extrapolated predictions. Additionally, bias may arise when the stochastic component of a log regression model is assumed to be multiplicative when the actual underlying stochastic component is additive. To account for these possible sources of bias, a log regression model with measurement error and additive error is approximated by a weighted regression model which can be estimated using Iteratively Re-weighted Least Squares. Using the reduced Eyring equation in an accelerated testing setting, the model is compared to previously accepted approaches to modeling accelerated testing data with both simulations and real data.

Accounting for measurement error in log regression models with applications to accelerated testing.

Directory of Open Access Journals (Sweden)

Robert Richardson

Full Text Available In regression settings, parameter estimates will be biased when the explanatory variables are measured with error. This bias can significantly affect modeling goals. In particular, accelerated lifetime testing involves an extrapolation of the fitted model, and a small amount of bias in parameter estimates may result in a significant increase in the bias of the extrapolated predictions. Additionally, bias may arise when the stochastic component of a log regression model is assumed to be multiplicative when the actual underlying stochastic component is additive. To account for these possible sources of bias, a log regression model with measurement error and additive error is approximated by a weighted regression model which can be estimated using Iteratively Re-weighted Least Squares. Using the reduced Eyring equation in an accelerated testing setting, the model is compared to previously accepted approaches to modeling accelerated testing data with both simulations and real data.

Critical wall shear stress for the EHEDG test method

DEFF Research Database (Denmark)

Jensen, Bo Boye Busk; Friis, Alan

2004-01-01

In order to simulate the results of practical cleaning tests on closed processing equipment, based on wall shear stress predicted by computational fluid dynamics, a critical wall shear stress is required for that particular cleaning method. This work presents investigations that provide a critical...... wall shear stress of 3 Pa for the standardised EHEDG cleaning test method. The cleaning tests were performed on a test disc placed in a radial flowcell assay. Turbulent flow conditions were generated and the corresponding wall shear stresses were predicted from CFD simulations. Combining wall shear...... stress predictions from a simulation using the low Re k-epsilon and one using the two-layer model of Norris and Reynolds were found to produce reliable predictions compared to empirical solutions for the ideal flow case. The comparison of wall shear stress curves predicted for the real RFC...

Accelerated radiation damage test facility using a 5 MV tandem ion accelerator

International Nuclear Information System (INIS)

Wady, P.T.; Draude, A.; Shubeita, S.M.; Smith, A.D.; Mason, N.; Pimblott, S.M.; Jimenez-Melero, E.

2016-01-01

We have developed a new irradiation facility that allows to perform accelerated damage tests of nuclear reactor materials at temperatures up to 400 °C using the intense proton (<100 μA) and heavy ion (≈10 μA) beams produced by a 5 MV tandem ion accelerator. The dedicated beam line for radiation damage studies comprises: (1) beam diagnosis and focusing optical components, (2) a scanning and slit system that allows uniform irradiation of a sample area of 0.5–6 cm"2, and (3) a sample stage designed to be able to monitor in-situ the sample temperature, current deposited on the sample, and the gamma spectrum of potential radio-active nuclides produced during the sample irradiation. The beam line capabilities have been tested by irradiating a 20Cr–25Ni–Nb stabilised stainless steel with a 3 MeV proton beam to a dose level of 3 dpa. The irradiation temperature was 356 °C, with a maximum range in temperature values of ±6 °C within the first 24 h of continuous irradiation. The sample stage is connected to ground through an electrometer to measure accurately the charge deposited on the sample. The charge can be integrated in hardware during irradiation, and this methodology removes uncertainties due to fluctuations in beam current. The measured gamma spectrum allowed the identification of the main radioactive nuclides produced during the proton bombardment from the lifetimes and gamma emissions. This dedicated radiation damage beam line is hosted by the Dalton Cumbrian Facility of the University of Manchester.

Time, stress, and temperature-dependent deformation in nanostructured copper: Stress relaxation tests and simulations

International Nuclear Information System (INIS)

Yang, Xu-Sheng; Wang, Yun-Jiang; Wang, Guo-Yong; Zhai, Hui-Ru; Dai, L.H.; Zhang, Tong-Yi

2016-01-01

In the present work, stress relaxation tests, high-resolution transmission electron microscopy (HRTEM), and molecular dynamics (MD) simulations were conducted on coarse-grained (cg), nanograined (ng), and nanotwinned (nt) copper at temperatures of 22 °C (RT), 30 °C, 40 °C, 50 °C, and 75 °C. The comprehensive investigations provide sufficient information for the building-up of a formula to describe the time, stress, and temperature-dependent deformation and clarify the relationship among the strain rate sensitivity parameter, stress exponent, and activation volume. The typically experimental curves of logarithmic plastic strain rate versus stress exhibited a three staged relaxation process from a linear high stress relaxation region to a subsequent nonlinear stress relaxation region and finally to a linear low stress relaxation region, which only showed-up at the test temperatures higher than 22 °C, 22 °C, and 30 °C, respectively, in the tested cg-, ng-, and nt-Cu specimens. The values of stress exponent, stress-independent activation energy, and activation volume were determined from the experimental data in the two linear regions. The determined activation parameters, HRTEM images, and MD simulations consistently suggest that dislocation-mediated plastic deformation is predominant in all tested cg-, ng-, and nt-Cu specimens in the initial linear high stress relaxation region at the five relaxation temperatures, whereas in the linear low stress relaxation region, the grain boundary (GB) diffusion-associated deformation is dominant in the ng- and cg-Cu specimens, while twin boundary (TB) migration, i.e., twinning and detwinning with parallel partial dislocations, governs the time, stress, and temperature-dependent deformation in the nt-Cu specimens.

Combined Mini-Cylex & Disk Acceleration Tests in Type K Copper.

Energy Technology Data Exchange (ETDEWEB)

Maines, Warren Russell [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kittell, David E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hobbs, Michael L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-12-01

We combined the miniature cylinder expansion test (Mini-Cylex), with the Disk Acceleration Test (DAX) using Type K copper, Picatinny Liquid Explosive, and photonic Doppler velocimetry. We estimated the CJ state using plate reverberation methods at the test cap. We extracted velocities at 2, 7, and 10 volume expansions to fit Jones-Wilkins-Lee Equation of State at the tube wall. And we estimated Gurney velocity both at the test cap and tube wall. Our experiments and simulations are within expected uncertainty. The test and the analysis effectively reduce costs while keeping similar fidelity compared with more expensive tests.

Accelerated life testing effects on CMOS microcircuit characteristics, phase 1

Science.gov (United States)

Maximow, B.

1976-01-01

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

A study on the reliability evaluation of shot peened aluminium alloy using accelerated life test

International Nuclear Information System (INIS)

Nam, Ji Hun; Cheong, Seong Kyun; Kang, Min Woo

2006-01-01

In this paper, the concept of accelerated life test, which is a popular research field nowadays, is applied to the shot peened material. To predict the efficient and exact room temperature fatigue characteristics from the high temperature fatigue data, the adequate accelerated model is investigated. Ono type rotary bending fatigue tester and high temperature chamber were used for the experiment. Room temperature fatigue lives were predicted by applying accelerated models and doing reliability evaluation. Room temperature fatigue tests were accomplished to check the effectiveness of predicted data and the adequate accelerated life test models were presented by considering errors. Experimental result using Arrhenius model, fatigue limit obtain almost 5.45% of error, inverse power law has about 1.36% of error, so we found that inverse power law is applied well to temperature-life relative of shot peended material

Accelerated testing for cosmic soft-error rate

International Nuclear Information System (INIS)

Ziegler, J.F.; Muhlfeld, H.P.; Montrose, C.J.; Curtis, H.W.; O'Gorman, T.J.; Ross, J.M.

1996-01-01

This paper describes the experimental techniques which have been developed at IBM to determine the sensitivity of electronic circuits to cosmic rays at sea level. It relates IBM circuit design and modeling, chip manufacture with process variations, and chip testing for SER sensitivity. This vertical integration from design to final test and with feedback to design allows a complete picture of LSI sensitivity to cosmic rays. Since advanced computers are designed with LSI chips long before the chips have been fabricated, and the system architecture is fully formed before the first chips are functional, it is essential to establish the chip reliability as early as possible. This paper establishes techniques to test chips that are only partly functional (e.g., only 1Mb of a 16Mb memory may be working) and can establish chip soft-error upset rates before final chip manufacturing begins. Simple relationships derived from measurement of more than 80 different chips manufactured over 20 years allow total cosmic soft-error rate (SER) to be estimated after only limited testing. Comparisons between these accelerated test results and similar tests determined by ''field testing'' (which may require a year or more of testing after manufacturing begins) show that the experimental techniques are accurate to a factor of 2

Sensory shelf life of mantecoso cheese using accelerated testing

OpenAIRE

Sánchez-González, Jesús A.; Pérez, Joel A.

2016-01-01

The aim of this research was to estimate sensory shelf life of "huacariz" and "cefop" mantecoso cheese, vacuum packaging: "cefop" and packaging to the atmospheric pressure: "huacariz"; brands marketed in Cajamarca, using accelerated shelf life testing. For this purpose, "huacariz" cheese was stored at 20, 28, 35 y 40 °C, while it was set at 20, 28, 35 °C storage for "cefop" cheese, performing acceptability sensory tests according to time storage with both 41 consumers constants. The results f...

Electrostatic accelerator dielectrics

International Nuclear Information System (INIS)

Cooke, C.M.

1989-05-01

High voltage insulation problems in electrostatic accelerators are discussed. The aim of the analysis is to broaden the knowledge, highlight the characteristics of insulation technology and design strategies to improve use. The basic geometry of the insulation in accelerators is considered. A detailed description of each of the insulation regions is provided. The gas gap insulation of the terminal voltage is found to be sensitive to regions of high electric stress. In order to obtain satisfactory performance from solid support insulation, the attention is focused on the electric stress value and distribution. Potential subjects for discussion and further investigations are given

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

OpenAIRE

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

2014-01-01

This work describes the architecture of a digital LLRF system for heavy-ion acceleration developed under the specification of the projected future heavy-ion accelerator facility in Huelva, Spain. A prototype LLRF test bench operating at 80MHz in CW mode has been designed and built. The core LLRF control has been digitally implemented on a PXIe chassis, including an FPGA for digital signal processing and a real time controller. The test bench is completed with a good quality signal generator u...

Initial measurements of beam breakup instability in the advanced test accelerator

International Nuclear Information System (INIS)

Chong, Y.P.; Caporaso, G.T.; Struve, K.W.

1985-01-01

This paper reports the measurements of beam breakup (BBU) instability performed on the Advanced Test Accelerator (ATA) up to the end of February 1984. The main objective was to produce a high current usable electron beam at the ATA output. A well-known instability is BBU which arises from the accelerator cavity modes interacting with the electron beam. The dominant mode is TM130 at a frequency of approximately 785 MHz. It couples most strongly to the beam motion and has been observed to grow in the Experimental Test Accelerator (ETA), which has only eight accelerator cavities. ATA has one hundred and seventy cavities and therefore the growth of BBU is expected to be more severe. In this paper, BBU measurements are reported for ATA with beam currents of 4 to 7 kA. Analysis showed that the growth of the instability with propagation distance was as expected for the lower currents. However, the high current data showed an apparent higher growth rate than expected. An explanation for this anomaly is given in terms of a ''corkscrew'' excitation. The injector BBU noise level for a field emission brush cathode was found to be an order of magnitude lower than for a cold plasma discharge cathode. These injector rf amplitudes agree very well with values obtained using the method of differenced Btheta loops

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

Energy Technology Data Exchange (ETDEWEB)

Pern, F. J.; Noufi, R.

2012-10-01

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 μm to 0.50 μm 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

Applying an overstress principle in accelerated testing of absorbing mechanisms

Science.gov (United States)

Tsyss, V. G.; Sergaeva, M. Yu; Sergaev, A. A.

2018-04-01

The relevance of using overstress test as a forced one to determine the pneumatic absorber lifespan was studied. The obtained results demonstrated that at low load overstress the relative error for the absorber lifespan evaluation is no more than 3%. This means that the test results spread has almost no effect on the lifespan evaluation, and this effect is several times less than that at high load overstress tests. Accelerated testing of absorbers with low load overstress is more acceptable since the relative error for the lifespan evaluation is negligible.

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

Energy Technology Data Exchange (ETDEWEB)

Otake, Yuji, E-mail: otake@spring8.or.jp [RIKEN, SPring-8 Center, XFEL Research and Development Division, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); JASRI, XFEL Division, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Ohshima, Takashi [RIKEN, SPring-8 Center, XFEL Research and Development Division, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); JASRI, XFEL Division, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hosoda, Naoyasu [JASRI, XFEL Division, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Maesaka, Hirokazu; Fukui, Toru [RIKEN, SPring-8 Center, XFEL Research and Development Division, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); JASRI, XFEL Division, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kitamura, Masanobu [Hitachi Zosen Corporation, 7-89, Nanko-kita 1-chome, Suminoe-ku, Osaka 559-8559 (Japan); Shintake, Tsumoru [The Okinawa Institute of Science and Technology Graduate University, Tancha, Onna-Son, Kunigami, Okinawa 904-0495 (Japan)

2012-12-22

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 Degree-Sign 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

Database requirements for the Advanced Test Accelerator project

International Nuclear Information System (INIS)

Chambers, F.W.

1984-01-01

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

Stress Tests for Chest Pain: When You Need an Imaging Test -- and When You Don't

Science.gov (United States)

... Resources Adult , Geriatric Stress Tests for Chest Pain Stress Tests for Chest Pain When you need an ... pain isn’t from heart disease. A cardiac stress test makes the heart work hard so your ...

Acceleration tests of the INS 25.5-MHz split coaxial RFQ

International Nuclear Information System (INIS)

Arai, S.; Imanishi, A.; Morimoto, T.; Tojyo, E.; Tokuda, N.; Shibuya, S.

1991-05-01

The INS 25.5-MHz split coaxial RFQ, a linac that accelerates ions with a charge-to-mass ratio greater than 1/30 from 1 to 45.4 keV/u, is now undergoing acceleration tests with a beam of molecular nitrogen (N 2 + ) ions. Results so far obtained show that the RFQ operates in accordance with the design. Presented are preliminary results on the beam performance: emittances of the in- and output beams, output energy and its spread, and beam transmission. (author)

Test plan for in situ stress measurement system development

International Nuclear Information System (INIS)

Kim, K.

1981-09-01

The tests are to be performed to provide information regarding the state of stress of the basalt rock beneath the Hanford Site. This test series is designed to obtain information necessary to determine if hydrofracturing stress measurement is feasible in a fractured basalt medium. During the course of these field tests, it will be attempted to adapt the conventional hydrofracturing test method and analysis techniques to the basalt medium. If the test is shown to be feasible, more holes will be identified for testing. A comprehensive in situ stress determination program will be initiated. 2 figs

77 FR 60948 - Stress Testing of Regulated Entities

Science.gov (United States)

2012-10-05

... regulated by a primary federal financial regulatory agency, to conduct annual stress tests to determine... the regulated entities under the Federal Housing Enterprises Financial Safety and Soundness Act of... regulated by a primary Federal financial regulatory agency shall conduct annual stress tests * * * (emphasis...

Calibration of full-scale accelerated pavement testing data using long-term pavement performance data

CSIR Research Space (South Africa)

VdM Steyn, WJ

2012-09-01

Full Text Available Accelerated Pavement Testing (APT) has always been conducted with the objective of improving the understanding of real pavements under real traffic and environmental conditions. While APT provides an accelerated view of some of the major structural...

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

Science.gov (United States)

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

2013-11-01

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

A General Accelerated Degradation Model Based on the Wiener Process.

Science.gov (United States)

Liu, Le; Li, Xiaoyang; Sun, Fuqiang; Wang, Ning

2016-12-06

Accelerated degradation testing (ADT) is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses.

A General Accelerated Degradation Model Based on the Wiener Process

Directory of Open Access Journals (Sweden)

Le Liu

2016-12-01

Full Text Available Accelerated degradation testing (ADT is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses.

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

Science.gov (United States)

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

1980-01-01

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

Accelerated tests of coil coatings

Directory of Open Access Journals (Sweden)

Rosales, B. M.

2003-12-01

Full Text Available Accelerated laboratory tests on 12 materials in study in the Subgroup 6 of the PATINA Network (CYTED, are discussed for different exposition periods in salt spray, SO₂ and Prohesion chambers. International standards used to evaluate failures caused by the different aggressive agents of these laboratory tests are the same as those applied for outdoor expositions. The results exposed contribute to a better understanding of the mechanisms occurred in the diverse natural environments, being mentioned the main analogies and differences respect to factors affecting natural tests. They also allowed to evidence the advantages and limitations in the application of these tests during several days, as compared to the years required to attain similar failure magnitudes through outdoor tests.

En este trabajo se discuten los ensayos de laboratorio acelerados, realizados sobre 12 materiales de estudio en el Subgrupo 6 de la Red PATINA (CYTED, a diferentes periodos de exposición en cámaras de niebla salina, SO₂ y Prohesion. Se utilizaron las normas internacionales para evaluar los fallos causados por los diferentes agentes agresivos de estos ensayos de laboratorio, las cuales se aplican también para los ensayos de exposición a la intemperie. Los resultados expuestos contribuyen a una mejor comprensión de los mecanismos ocurridos en los diversos ambientes naturales, mencionándose las principales analogías y diferencias respecto de los factores que afectan los ensayos naturales. También permitieron evidenciar las ventajas y limitaciones en la aplicación de estos ensayos durante varios días, en comparación con los años requeridos para alcanzar magnitudes de fallos similares por medio de ensayos a intemperie.

Relationships between adolescents' test anxiety, stress and sleep

NARCIS (Netherlands)

Dewald, J.F.; Meijer, A.M.; Oort, F.J.; Bögels, S.M.

2012-01-01

Objective. This study aims to investigate the relationship between adolescents' test anxiety, stress and different aspects of sleep. Method. 175 adolescents (70.8% girls, mean age 15.14 years) participated in the study. Test anxiety, stress and chronic sleep reduction were assessed at baseline using

Stress corrosion testing of irradiated cladding tubes

International Nuclear Information System (INIS)

Lunde, L.; Olshausen, K.D.

1980-01-01

Samples from two fuel rods with different cladding have been stress corrosion tested by closed-end argon-iodine pressurization at 320 0 C. The fuel rods with stress relieved and recrystallized Zircaloy-2 had received burnups of 10.000 and 20.000 MWd/ton UO 2 , respectively. It was found that the SCC failure stress was unchanged or slightly higher for the irradiated than for the unirradiated control tubes. The tubes failed consistently in the end with the lowest irradiation dose. The diameter increase of the irradiated cladding during the test was 1.1% for the stress-relieved samples and 0.24% for the recrystallized samples. SEM examination revealed no major differences between irradiated and unirradiated cladding. A ''semi-ductile'' fracture zone in recrystallized material is described in some detail. (author)

CAS CERN Accelerator School: Advanced accelerator physics. Proceedings. Vol. 2

International Nuclear Information System (INIS)

Turner, S.

1987-01-01

This advanced course on general accelerator physics is the second of the biennial series given by the CERN Accelerator School and follows on from the first basic course given at Gif-sur-Yvette, Paris, in 1984. Stress is placed on the mathematical tools of Hamiltonian mechanics and the Vlasov and Fokker-Planck equations, which are widely used in accelerator theory. The main topics treated in this present work include: nonlinear resonances, chromaticity, motion in longitudinal phase space, growth and control of longitudinal and transverse beam emittance, space-charge effects and polarization. The seminar programme treats some specific accelerator techniques, devices, projects and future possibilities. (orig.)

Accelerated Corrosion Testing

Science.gov (United States)

1982-12-01

Treaty Organization, Brussels, 1971), p. 449. 14. D. 0. Sprowls, T. J. Summerson, G. M. Ugianski, S. G. Epstein, and H. L. Craig , Jr., in Stress...National Association of Corrosion Engineers Houston, TX, 1972). 22. H. L. Craig , Jr. (ed.), Stress Corrosion-New Approaches, ASTM-STP- 610 (American...62. M. Hishida and H. Nakada, Corrosion 33 (11) 403 (1977). b3. D. C. Deegan and B. E. Wilde, Corrosion 34 (6), 19 (1978). 64. S. Orman, Corrosion Sci

Nonexercise cardiac stress testing

International Nuclear Information System (INIS)

Vacek, J.L.; Baldwin, T.

1989-01-01

Many patients who require evaluation for coronary artery disease are unable to undergo exercise stress testing because of physiologic or psychological limitations. Drs Vacek and Baldwin describe three alternative methods for assessment of cardiac function in these patients, all of which have high levels of diagnostic sensitivity and specificity. 23 references

ESCAR, tests of superconducting bending magnets at the accelerator site

International Nuclear Information System (INIS)

Gilbert, W.S.; Lambertson, G.R.; Meuser, R.B.; Rechen, J.B.

1979-03-01

ESCAR (Experimental Superconducting Accelerator Ring) was conceived as a project in accelerator technology development which would provide data and experience to insure that planning for larger superconducting synchrotrons would proceed in a knowledgeable and responsible manner. It was to consist of the fabrication and operation of a relatively small proton synchrotron and storage ring with superconducting magnet elements for all of the main ring. The project was funded and design work began in July 1974. During the next two years it became increasingly apparent that the funding rate was directly limiting the rate of completion of ESCAR and that an intermediate goal, a test of the unconventional aspects of the project, was desirable. To that end, twelve dipole bending magnets, one-half of those required for the total ring, were installed at the site along with the 1500 watt helium refrigerator, cryogenic distribution system, electrical power supplies, vacuum systems, and necessary instrumentation. This truncated system was put through an extended series of tests which were completed in June 1978 at which time the ESCAR Project was terminated. ESCAR, and the dipole magnets have been described previously. The results of the systems tests have also been reported. The tests involving the dipole magnets are described

Sex and stress: Men and women show different cortisol responses to psychological stress induced by the Trier social stress test and the Iowa singing social stress test.

Science.gov (United States)

Reschke-Hernández, Alaine E; Okerstrom, Katrina L; Bowles Edwards, Angela; Tranel, Daniel

2017-01-02

Acute psychological stress affects each of us in our daily lives and is increasingly a topic of discussion for its role in mental illness, aging, cognition, and overall health. A better understanding of how such stress affects the body and mind could contribute to the development of more effective clinical interventions and prevention practices. Over the past 3 decades, the Trier Social Stress Test (TSST) has been widely used to induce acute stress in a laboratory setting based on the principles of social evaluative threat, namely, a judged speech-making task. A comparable alternative task may expand options for examining acute stress in a controlled laboratory setting. This study uses a within-subjects design to examine healthy adult participants' (n = 20 men, n = 20 women) subjective stress and salivary cortisol responses to the standard TSST (involving public speaking and math) and the newly created Iowa Singing Social Stress Test (I-SSST). The I-SSST is similar to the TSST but with a new twist: public singing. Results indicated that men and women reported similarly high levels of subjective stress in response to both tasks. However, men and women demonstrated different cortisol responses; men showed a robust response to both tasks, and women displayed a lesser response. These findings are in line with previous literature and further underscore the importance of examining possible sex differences throughout various phases of research, including design, analysis, and interpretation of results. Furthermore, this nascent examination of the I-SSST suggests a possible alternative for inducing stress in the laboratory. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

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

Energy Technology Data Exchange (ETDEWEB)

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

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.

Accelerated Testing and Modeling of Potential-Induced Degradation as a Function of Temperature and Relative Humidity

DEFF Research Database (Denmark)

Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent

2015-01-01

An acceleration model based on the Peck equation was applied to power performance of crystalline silicon cell modules as a function of time and of temperature and humidity, which are the two main environmental stress factors that promote potential-induced degradation (PID). This model was derived...

Accelerated Testing and Modeling of Potential-Induced Degradation as a Function of Temperature and Relative Humidity

DEFF Research Database (Denmark)

Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent

2015-01-01

An acceleration model based on the Peck equation was applied to power performance of crystalline silicon cell modules as a function of time and of temperature and humidity, the two main environmental stress factors that promote potential-induced degradation. This model was derived from module pow...

Accelerated Physical Stability Testing of Amorphous Dispersions.

Science.gov (United States)

Mehta, Mehak; Suryanarayanan, Raj

2016-08-01

The goal was to develop an accelerated physical stability testing method of amorphous dispersions. Water sorption is known to cause plasticization and may accelerate drug crystallization. In an earlier investigation, it was observed that both the increase in mobility and decrease in stability in amorphous dispersions was explained by the "plasticization" effect of water (Mehta et al. Mol. Pharmaceutics 2016, 13 (4), 1339-1346). In this work, the influence of water concentration (up to 1.8% w/w) on the correlation between mobility and crystallization in felodipine dispersions was investigated. With an increase in water content, the α-relaxation time as well as the time for 1% w/w felodipine crystallization decreased. The relaxation times of the systems, obtained with different water concentration, overlapped when the temperature was scaled (Tg/T). The temperature dependencies of the α-relaxation time as well as the crystallization time were unaffected by the water concentration. Thus, the value of the coupling coefficient, up to a water concentration of 1.8% w/w, was approximately constant. Based on these findings, the use of "water sorption" is proposed to build predictive models for crystallization in slow crystallizing dispersions.

Stress testing - ettevaatliku investori abimees / Peeter Teder

Index Scriptorium Estoniae

Teder, Peeter

2005-01-01

Autor selgitab stress testingut kui investeerimisportfelli varade väärtuse hindamist ning tutvustab selle võimalusi ja ohtusid. Diagrammid: Portfelli testimis-stsenaariumiks sobivad hästi börsikrahhid. Vt. samas: Stress testing toimib ka mujal

Development and test of a planar R-band accelerating structure

CERN Document Server

Merte, R; Peikert, M; Yu, D

1999-01-01

Planar accelerating structures, so called muffin tins, are of great interest for new accelerating techniques which are operating at high frequencies. At present the upper frequency limit for high power sources is 29.9855 GHz available at CERN. Therefore a new design of a planar traveling wave constant impedance accelerating structure is presented. A fully engineered 37-cell prototype with an operating frequency of 29.9855 GHz, which is designed for the 2 pi /3-mode, was fabricated by CNC milling technology. The design includes a power coupler, a cavity geometry optimized to compensate the effect of transverse forces, vacuum flanges and beam pipe flanges. Shown are the frequency scan of transmission and reflection measurements compared to numerical simulations with GdfidL. Further, a non resonant bead pull measurement was made to determine and verify the fundamental modes of the structure. The cavity is planned to be powered at the CLIC test stand at CERN. (4 refs).

Life time forecasting method upon occurrence of stress corrosion cracking of structure and test device therefor

International Nuclear Information System (INIS)

Anzai, Hideya; Kida, Toshitaka; Urayama, Yoshinao; Kikuchi, Eiji; Shimanuki, Sei; Kuniya, Jiro; Nakata, Kiyotomo; Izumitani, Masakiyo; Hattori, Shigeo.

1993-01-01

A load stress is applied to a metal piece made of a material identical with the constituent material of a structure and having the sensitivity enhanced to a predetermined level, and plurality of such pieces are immersed in a corrosive circumstance in this state. Then, the time from the immersion till the rupture thereof and the number of ruptured pieces of the metal pieces are detected while observing them. The relation with the probability of rupture is plotted on a paper to determine the life time for the occurrence of minimum stress corrosion creacks (SSC) of the metal pieces. Based on the relationship between the previously determined stress and the life time for the occurrence of minimum SSC, the ratio between the life time for the occurrence of minimum SSC relative to estimated stress applied to the structure and the life time for the occurrence of minimum SSC relative to the stress applied to the metal pieces is determined as a first SSC acceleration rate. The ratio between the time of occurrence for minimum SSC and the sensitivity is determined as a second SSC acceleration rate. The first and the second SSC acceleration rates are multiplied to estimate the time for the occurrence of SSC of the structure. Then, the life time for the occurrence of SSC for the equipments and structures can be recognized quantitatively, to prevent ruptures of actual equipments and extend the life time. (N.H.)

Conceptual design of multi-purpose accelerator-driven transmutation test facility

International Nuclear Information System (INIS)

Hirota, Koichi; Hida, Kenzo; Yokobori, Hitoshi; Kamishima, Yoshio

1999-01-01

The Japan Atomic Energy Research Institute (JAERI) has been developing a concept of accelerator-driven transmutation system using a high-power proton linac. To demonstrate the technical feasibility of this concept, accelerator-driven spallation experiments will be necessary. We believe our proposal of a multi-purpose test facility is a promising concept to clarify its feasibility from the basic neutronics and engineering standpoint. The main feature of our initial proposal is using an inclined beam injection. It enables to simplify the head of the test vessel as well as to facilitate easy replacing of the beam window and the testing device containing the test specimen, and also this system will minimize the complexity of the vessel head and surrounding structures. Next proposal is using an ordinary overhead beam injection system and is modified to be simple structural concept of the test vessel from inclined beam injection. At the first step, the basic neutronics experiments will be performed. At this step, the test device and the cooling device are simpler ones, due to only small heat will be generated. Then we plan using a gas cooling. At the following steps, the test device and the vessel internal structures will be remodeled or remade to adjust to the test purposes, if necessary. At these steps, target material tests and thermal hydraulic tests using some liquid metal coolants will be done. In this case, the natural circulation cooling will be done. To verify the transmutation technology, a larger heat will be generated, so a forced coolant circulation system will be installed in the test vessel. This system consists of a heat exchanger and a circulation pump. The vessel internal structure will be remade. Doing such step-wise remaking, initial construction cost of the proposed test facility will be expected to be reasonable. (author)

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

International Nuclear Information System (INIS)

Wilson, N.G.

1986-01-01

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

The Protective Effect of Antarctic Krill Oil on Cognitive Function by Inhibiting Oxidative Stress in the Brain of Senescence-Accelerated Prone Mouse Strain 8 (SAMP8) Mice.

Science.gov (United States)

Li, Qian; Wu, Fengjuan; Wen, Min; Yanagita, Teruyoshi; Xue, Changhu; Zhang, Tiantian; Wang, Yuming

2018-02-01

Alzheimer's disease (AD) is a common neurodegenerative disorder, and oxidative stress plays a vital role in its progression. Antarctic krill oil (AKO) is rich in polyunsaturated fatty acids, which has various biological activities, such as improving insulin sensitivity, alleviating inflammation and ameliorating oxidative stress. In this study, the protective effect of AKO against AD were investigated in senescence-accelerated prone mouse strain 8 (SAMP8) mice. Results showed that treatment with AKO could effectively ameliorate learning and memory deficits and ease the anxiety in SAMP8 mice by Morris water maze, Barnes maze test and open-field test. Further analysis indicated that AKO might reduce β-amyloid (Aβ) accumulation in hippocampus through decreasing the contents of malondialdehyde (MDA) and 7,8-dihydro-8-oxoguanine (8-oxo-G), increasing the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in the brain of SAMP8 mice. The results of Morris water maze, Barnes maze test and open-field test indicated that Antarctic krill oil (AKO) improved the cognitive function and anxiety of SAMP8 mice. AKO reduced the Aβ 42 level in hippocampus of SAMP8 mice. AKO ameliorated oxidative stress in brain rather than in serum and liver of SAMP8 mice. © 2018 Institute of Food Technologists®.

Accelerated Testing Methodology for the Determination of Slow Crack Growth of Advanced Ceramics

Science.gov (United States)

Choi, Sung R.; Salem, Jonathan A.; Gyekenyesi, John P.

1997-01-01

Constant stress-rate (dynamic fatigue) testing has been used for several decades to characterize slow crack growth behavior of glass and ceramics at both ambient and elevated temperatures. The advantage of constant stress-rate testing over other methods lies in its simplicity: Strengths are measured in a routine manner at four or more stress rates by applying a constant crosshead speed or constant loading rate. The slow crack growth parameters (n and A) required for design can be estimated from a relationship between strength and stress rate. With the proper use of preloading in constant stress-rate testing, an appreciable saving of test time can be achieved. If a preload corresponding to 50 % of the strength is applied to the specimen prior to testing, 50 % of the test time can be saved as long as the strength remains unchanged regardless of the applied preload. In fact, it has been a common, empirical practice in strength testing of ceramics or optical fibers to apply some preloading (less then 40%). The purpose of this work is to study the effect of preloading on the strength to lay a theoretical foundation on such an empirical practice. For this purpose, analytical and numerical solutions of strength as a function of preloading were developed. To verify the solution, constant stress-rate testing using glass and alumina at room temperature and alumina silicon nitride, and silicon carbide at elevated temperatures was conducted in a range of preloadings from O to 90 %.

Simulation of 20-year deterioration of acrylic IOLs using severe accelerated deterioration tests.

Science.gov (United States)

Kawai, Kenji; Hayakawa, Kenji; Suzuki, Takahiro

2012-09-20

To investigate IOL deterioration by conducting severe accelerated deterioration testing of acrylic IOLs. Department of Ophthalmology, Tokai University School of Medicine Methods: Severe accelerated deterioration tests performed on 7 types of acrylic IOLs simulated 20 years of deterioration. IOLs were placed in a screw tube bottle containing ultra-pure water and kept in an oven (100°C) for 115 days. Deterioration was determined based the outer appearance of the IOL in water and under air-dried conditions using an optical microscope. For accelerated deterioration of polymeric material, the elapse of 115 days was considered to be equivalent to 20 years based on the Arrhenius equation. All of the IOLs in the hydrophobic acrylic group except for AU6 showed glistening-like opacity. The entire optical sections of MA60BM and SA60AT became yellowish white in color. Hydrophilic acrylic IOL HP60M showed no opacity at any of the time points examined. Our data based on accelerated testing showed differences in water content to play a major role in transparency. There were differences in opacity among manufacturers. The method we have used for determining the relative time of IOL deterioration might not represent the exact clinical setting, but the appearance of the materials would presumably be very similar to that seen in patients.

Simulation of dynamic traffic loading based on accelerated pavement testing (APT)

CSIR Research Space (South Africa)

Steyn, WJvdM

2004-03-01

Full Text Available The objective of this paper is to introduce the latest Heavy Vehicle Simulator (HVS) technology as part of the South African Accelerated Pavement Testing (APT) efforts, its capabilities and expected impact on road pavement analysis....

Accelerated Desensitization with Adaptive Attitudes and Test Gains with 5th Graders

Science.gov (United States)

Miller, Melanie; Morton, Jerome; Driscoll, Richard; Davis, Kai A.

2006-01-01

The study evaluates an easily-administered test-anxiety reduction program. An entire fifth grade was screened, and 36 students identified as test-anxious were randomly assigned to an Intervention or a non-participant Control group. The intervention was an accelerated desensitization and adaptive attitudes (ADAA) treatment which involved…

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

Energy Technology Data Exchange (ETDEWEB)

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

2008-06-01

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

Current trends and future development in pharmacologic stress testing

International Nuclear Information System (INIS)

Bae, Jin Ho; Lee, Jae Tae

2005-01-01

Pharmacologic stress testing for myocardial perfusion imaging is a widely used noninvasive method for the evaluation of known or suspected coronary artery disease. The use of exercise for cardiac stress has been practiced for over 60 years and clinicians are familiar with its using. However, there are inevitable situations in which exercise stress is inappropriate. A large number of patients with cardiac problems are unable to exercise to their full potential due to comorbidity such as osteoarthritis, vascular disease and pulmonary disease and a standard exercise stress test for myocardial perfusion imaging is suboptimal means for assessment of coronary artery disease. This problem has led to the development of the pharmacologic stress test and to a great increase in its popularity. All of the currently used pharmacologic agents have well-documented diagnostic value. This review deals the physiological actions, clinical protocols, safety, nuclear imaging applications of currently available stress agents and future development of new vasodilating agents

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

Science.gov (United States)

Shen, Jie; Burgess, Diane J

2012-01-17

Dexamethasone loaded poly(lactic-co-glycolic acid) (PLGA) microsphere/PVA hydrogel composites have been investigated as an outer drug-eluting coating for implantable devices such as glucose sensors to counter negative tissue responses to implants. The objective of this study was to develop a discriminatory, accelerated in vitro release testing method for this drug-eluting coating using United States Pharmacopeia (USP) apparatus 4. Polymer degradation and drug release kinetics were investigated under "real-time" and accelerated conditions (i.e. extreme pH, hydro-alcoholic solutions and elevated temperatures). Compared to "real-time" conditions, the initial burst and lag phases were similar using hydro-alcoholic solutions and extreme pH conditions, while the secondary apparent zero-order release phase was slightly accelerated. Elevated temperatures resulted in a significant acceleration of dexamethasone release. The accelerated release data were able to predict "real-time" release when applying the Arrhenius equation. Microsphere batches with faster and slower release profiles were investigated under "real-time" and elevated temperature (60°C) conditions to determine the discriminatory ability of the method. The results demonstrated both the feasibility and the discriminatory ability of this USP apparatus 4 method for in vitro release testing of drug loaded PLGA microsphere/PVA hydrogel composites. This method may be appropriate for similar drug/device combination products and drug delivery systems. Copyright © 2011 Elsevier B.V. All rights reserved.

Dipyridamole cerebral flow stress test evaluating ischemic cerebrovascular diseases

International Nuclear Information System (INIS)

Xiu, Y.; Chen, S.; Sun, X.; Liu, S.; Li, W.; Fan, W.; Wang, X.

2000-01-01

To detect the clinical value of dipyridamole cerebral blood flow stress test in cerebrovascular diseases (CVD). Nineteen patients (9 male, 10 female, mean age=65) who were diagnosed as CVD were included. One suffered from infarct, two suffered from thrombosis, one feel dizziness. All 4 performed rest and stress test. The other 15 were VBI, 9 of them performed stress test. Rest and stress test were done two-day method using Elscint Apex SP-6 SPECT equipped with low energy all purpose collimator. Rest perfusion imaging was started 30 min after injecting 1.11 GBq 99m Tc-ECD. Dipyridamole stress test was done within one week. 0.56 mg/Kg dipyridamole was injected intravenously during 4 min the same dose of ECD was injected 2 min later. The acquisition started 30 min later with the same parameter. Heart rate, ECG and the patient's complaint were monitored 2 min before and after dipyridamole. After correction for attenuation, transverse, coronal and sagittal slices were reconstructed. Eighteen ROIs were drawn symmetrically on cingulate, frontal, temporal-parietal, temporal, occipital, vision cortex, basal ganglia, superior frontal and parietal on the 3 rd , 6 th , 9 th transverse slices, selecting the contralateral as the reference region. The counts per pixel in each ROI were divided by the counts of the mirror region to obtain the relative uptake ratio. We think it abnormality when the ratio is above 1,1 or below 0.9. The sensitivity for rest and stress rCBF test was compared. rCBF was decreased at 10 of 19 patients (sensitivity 52.6%). 14 had low rCBF after dipyridamole (sensitivity 72.3%), Among the patients who studied stress test, 6 had normal rCBF at rest and low rCBF after stress. The abnormal area was enlarged after dipyridamole for 1 patients, 2 improved and 2 unchanged. 8 of 15 VBI had normal rCBF at rest (sensitivity 53.3%). 9 of 15 VBI performed stress test. rCBF was normal at rest for 5 patients, rCBF was decreased after stress, it was improved for one

Comparison of exercise stress testing with dobutamine stress echocardiography and radionuclide ventriculography for diagnosis of coronary artery disease

International Nuclear Information System (INIS)

Ozdemir, K.; Kisacik, H.L.; Oguzhan, A.

1999-01-01

Dobutamine stress echocardiography, Tc-99m radionuclide ventriculography (RNVG), and exercise stress testing were performed prospectively in 63 patients with suspected coronary artery disease to compare the values of exercise testing, dobutamine stress echocardiography and RNVG in the non-invasive diagnosis of coronary artery disease. The sensitivities of dobutamine stress echocardiography and RNVG were found to be higher than that of exercise testing (93-62%, p 0.05). There were no differences between the sensitivities of the three techniques in multiple vessel disease (p>0.05). The specificities of dobutamine stress echocardiography and RNVG were higher than that of exercise testing (for both of the tests 86-62%, p 0.05). The results of dobutamine stress echocardiography RNVG were concordant with each other in 46 patients (76%, kappa=65%) in sectional analysis. Dobutamine stress echocardiography and RNVG tests were comparable with each other in 85% of the 189 segments (kappa=64%). The expected 5% decrease at peak doses of dobutamine was not detected in stress echocardiography in 25 patients and in RNVG in 26 of the patients. Dobutamine stress echocardiography and RNVG are superior to exercise testing in the diagnosis of single vessel disease and there is no significant difference between the two techniques. When the ejection fraction is considered in dobutamine stress echocardiography and RNVG, it does not make an additional contribution to the diagnosis of coronary artery disease. (author)

Hurricane Isabel gives accelerators a severe test

International Nuclear Information System (INIS)

Swapan Chattopadhyay

2004-01-01

Hurricane Isabel was at category five--the most violent on the Saffir-Simpson scale of hurricane strength--when it began threatening the central Atlantic seaboard of the US. Over the course of several days, precautions against the extreme weather conditions were taken across the Jefferson Lab site in south-east Virginia. On 18 September 2003, when Isabel struck North Carolina's Outer Banks and moved northward, directly across the region around the laboratory, the storm was still quite destructive, albeit considerably reduced in strength. The flood surge and trees felled by wind substantially damaged or even devastated buildings and homes, including many belonging to Jefferson Lab staff members. For the laboratory itself, Isabel delivered an unplanned and severe challenge in another form: a power outage that lasted nearly three-and-a-half days, and which severely tested the robustness of Jefferson Lab's two superconducting machines, the Continuous Electron Beam Accelerator Facility (CEBAF) and the superconducting radiofrequency ''driver'' accelerator of the laboratory's free-electron laser. Robustness matters greatly for science at a time when microwave superconducting linear accelerators (linacs) are not only being considered, but in some cases already being built for projects such as neutron sources, rare-isotope accelerators, innovative light sources and TeV-scale electron-positron linear colliders. Hurricane Isabel interrupted a several-week-long maintenance shutdown of CEBAF, which serves nuclear and particle physics and represents the world's pioneering large-scale implementation of superconducting radiofrequency (SRF) technology. The racetrack-shaped machine is actually a pair of 500-600 MeV SRF linacs interconnected by recirculation arc beamlines. CEBAF delivers simultaneous beams at up to 6 GeV to three experimental halls. An imminent upgrade will double the energy to 12 GeV and add an extra hall for ''quark confinement'' studies. On a smaller scale

Current state of X-band accelerating structure high gradient test. Be held at high energy accelerator organization on April 15, 2005

International Nuclear Information System (INIS)

Watanabe, Ken; Higo, Toshiyasu

2005-01-01

XTF (X-band Test Facility, Old name is GLCTA) is the high gradient test facility for X-band acceleration. We have installed an X-band 60cm structure (KX01) in the April 2004 and have been processing it for more than 10 months. Now it is under test on long-term operation. We report here the high gradient test result to date. (author)

Some questions of the technique of high-voltage testing of accele-- rating tube space in electrostatic accelerators

International Nuclear Information System (INIS)

Romanov, V.A.; Ivanov, V.V.; Mukhametshin, V.I.; Dmitriev, E.P.; Kidalov, A.I.

1983-01-01

In the course of high-voltage testing of accelerating spaces a wide spread of experimental values of electric strength is observed. This circumstance is determined by a number of factors one of which is the technique used for high-voltage testing. For the purpose of obtaining more reliable experimental data on electric strength of accelerating spaces it is suggested to take for a criterion of electric strength of an accelerating space in long accelerating tubes a long-time withstood voltage which is equal approximately to a doubled working space voltage obtained as a result of a smooth voltage rise at dark current density not exceeding (1...5)x10 -2 A/cm 2 . In the course of testing of accelerating spaces of 25 mm height with total working area of electrodes approximately 360 cm 2 and insulator area onto vacuum approximately 150 cm 2 a long-time 70 kV voltage with dark current less than 1.10 -8 A is obtained

Establishment of a radiotherapy service with a linear accelerator (photons): acceptance tests, dosimetry and quality control

International Nuclear Information System (INIS)

Berdaky, Mafalda Feliciano

2000-01-01

This work presents the operational part of the final process of the establishment of a radiotherapy service with a linear accelerator (6 MeV photon beams), including the acceptance tests, commissioning tests and the implementation of a quality control program through routine mechanical and radiation tests. All acceptance tests were satisfactory, showing results below the allowed limits of the manufacturer, the commissioning tests presented results within those of the international recommendations. The quality control program was performed during 34 months and showed an excellent stability of this accelerator. (author)

High power testing of the multiple-loop radio-frequency drive concept for the FMIT accelerator

International Nuclear Information System (INIS)

Fazio, M.V.; Patton, R.D.

1984-04-01

The Fusion Materials Irradiation Test (FMIT) accelerator requires several 600-kW rf systems to simultaneously supply rf power to a single accelerator tank. Each rf-system output must be carefully phase and amplitude controlled to achieve the proper system performance. Two 80-MHz, 600-kW rf amplifiers with phase- and amplitude-control systems have been tested into a single, high-Q resonant cavity. Experimental results are presented

High voltage tests of an electrostatic accelerator for different mixtures of gases at various pressures

International Nuclear Information System (INIS)

Hellborg, R.

1996-01-01

An account is given of high voltage tests of an electrostatic accelerator. High voltage conditioning is measured and is reported for the same accelerator tube after different periods of usage. Tests of different mixtures of sulphur hexafluoride and nitrogen have been performed. A considerable amount of data was obtained for various parameters connected with the high voltage system for different proportions of nitrogen in sulphur hexafluoride at various gas pressures. (orig.)

FERTILITY INTENTIONS AND EARLY LIFE HEALTH STRESS AMONG WOMEN IN EIGHT INDIAN CITIES: TESTING THE REPRODUCTIVE ACCELERATION HYPOTHESIS.

Science.gov (United States)

Kulathinal, Sangita; Säävälä, Minna

2015-09-01

In life history theory, early life adversity is associated with an accelerated reproductive tempo. In harsh and unpredictable conditions in developing societies fertility is generally higher and the reproductive tempo faster than in more secure environments. This paper examines whether differences in female anthropometry, particularly adult height, are associated with fertility intentions of women in urban environments in India. The study population consists of women aged 15-29 (N=4485) in slums and non-slums of eight Indian cities in the National Family Health Survey (NFHS) of 2005-2006. Adult height is taken as a proxy for early childhood health and nutritional condition. Fertility intentions are examined by using two variables: the desire to have a child or another child, and to have it relatively soon, as indicative of accelerated reproductive scheduling. Evidence supporting the acceleration hypothesis is found in two urban frames out of 26 examined in a two-staged multinomial logistic model. In three cases, the relationship between fertility intentions and height is the opposite than expected by the acceleration hypothesis: taller women have a higher predictive probability of desiring a(nother) child and/or narrower birth spacing. Potential explanations for the partly contradictory relationship between the childhood health indicator and fertility intentions are discussed.

Accelerators for Fusion Materials Testing

Science.gov (United States)

Knaster, Juan; Okumura, Yoshikazu

Fusion materials research is a worldwide endeavor as old as the parallel one working toward the long term stable confinement of ignited plasma. In a fusion reactor, the preservation of the required minimum thermomechanical properties of the in-vessel components exposed to the severe irradiation and heat flux conditions is an indispensable factor for safe operation; it is also an essential goal for the economic viability of fusion. Energy from fusion power will be extracted from the 14 MeV neutron freed as a product of the deuterium-tritium fusion reactions; thus, this kinetic energy must be absorbed and efficiently evacuated and electricity eventually generated by the conventional methods of a thermal power plant. Worldwide technological efforts to understand the degradation of materials exposed to 14 MeV neutron fluxes >1018 m-2s-1, as expected in future fusion power plants, have been intense over the last four decades. Existing neutron sources can reach suitable dpa (“displacement-per-atom”, the figure of merit to assess materials degradation from being exposed to neutron irradiation), but the differences in the neutron spectrum of fission reactors and spallation sources do not allow one to unravel the physics and to anticipate the degradation of materials exposed to fusion neutrons. Fusion irradiation conditions can be achieved through Li (d, xn) nuclear reactions with suitable deuteron beam current and energy, and an adequate flowing lithium screen. This idea triggered in the late 1970s at Los Alamos National Laboratory (LANL) a campaign working toward the feasibility of continuous wave (CW) high current linacs framed by the Fusion Materials Irradiation Test (FMIT) project. These efforts continued with the Low Energy Demonstrating Accelerator (LEDA) (a validating prototype of the canceled Accelerator Production of Tritium (APT) project), which was proposed in 2002 to the fusion community as a 6.7MeV, 100mA CW beam injector for a Li (d, xn) source to bridge

Poor maternal nutrition and accelerated postnatal growth induces an accelerated aging phenotype and oxidative stress in skeletal muscle of male rats

Directory of Open Access Journals (Sweden)

Jane L. Tarry-Adkins

2016-10-01

Full Text Available ‘Developmental programming’, which occurs as a consequence of suboptimal in utero and early environments, can be associated with metabolic dysfunction in later life, including an increased incidence of cardiovascular disease and type 2 diabetes, and predisposition of older men to sarcopenia. However, the molecular mechanisms underpinning these associations are poorly understood. Many conditions associated with developmental programming are also known to be associated with the aging process. We therefore utilized our well-established rat model of low birth weight and accelerated postnatal catch-up growth (termed ‘recuperated’ in this study to establish the effects of suboptimal maternal nutrition on age-associated factors in skeletal muscle. We demonstrated accelerated telomere shortening (a robust marker of cellular aging as evidenced by a reduced frequency of long telomeres (48.5-8.6 kb and an increased frequency of short telomeres (4.2-1.3 kb in vastus lateralis muscle from aged recuperated offspring compared to controls. This was associated with increased protein expression of the DNA-damage-repair marker 8-oxoguanine-glycosylase (OGG1 in recuperated offspring. Recuperated animals also demonstrated an oxidative stress phenotype, with decreased citrate synthase activity, increased electron-transport-complex activities of complex I, complex II-III and complex IV (all markers of functional mitochondria, and increased xanthine oxidase (XO, p67phox and nuclear-factor kappa-light-chain-enhancer of activated B-cells (NF-κB. Recuperated offspring also demonstrated increased antioxidant defense capacity, with increased protein expression of manganese superoxide dismutase (MnSOD, copper-zinc superoxide dismutase (CuZnSOD, catalase and heme oxygenase-1 (HO1, all of which are known targets of NF-κB and can be upregulated as a consequence of oxidative stress. Recuperated offspring also had a pro-inflammatory phenotype, as evidenced by

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

Energy Technology Data Exchange (ETDEWEB)

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

2009-07-01

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.

[Autonomic regulation at emotional stress under hypoxic conditions in the elderly with physiological and accelerated aging: effect of hypoxic training].

Science.gov (United States)

Os'mak, E D; Asanov, É O

2014-01-01

The effect of hypoxic training on autonomic regulation in psycho-emotional stress conditions in hypoxic conditions in older people with physiological (25 people) and accelerated (28 people) aging respiratory system. It is shown that hypoxic training leads to an increase in vagal activity indicators (HF) and reduced simpatovagal index (LF/HF), have a normalizing effect on the autonomic balance during stress loads in older people with different types of aging respiratory system.

Beam Extraction for 1-MV Electrostatic Accelerator at the 300 kV Test Stand

Energy Technology Data Exchange (ETDEWEB)

Park, Sae-Hoon; Kim, Yu-Seok [Dongguk University, Seoul (Korea, Republic of); Kwon, Hyeok-Jung; Cho, Yong-Sub [KOMAC, Gyeongju (Korea, Republic of)

2015-05-15

The Korea Multipurpose Accelerator Complex (KOMAC) has been developing a 300-kV test stand for a 1-MV electrostatic accelerator ion source. The ion source in the high-pressure vessel is required to have a high reliability. The test stand has been proposed and developed to confirm the stable operating conditions of the ion source. The ion source will be tested at the test stand to verify the long-time operating conditions. The test stand comprises a 300-kV high-voltage terminal, a battery for the ion-source power, a 60-Hz inverter, 200-MHz RF power, a 5-kV extraction power supply, a 300-kV accelerating tube, and a vacuum system. A beam extraction experiment for the test stand was performed, and the beam current was measured using a faraday cup in the chamber. A beam extraction results for the RF ion source will be presented. Beam extraction from the RF ion source of the test stand is verified by measuring the beam current with a faraday cup in the chamber. Thus far NI Labview, PLC and faraday cup have been used to measure the beam current. The OPC server is useful for monitoring the PLC values. The average beam current of (a), (b) and (c) shown in figure 2 are 110.241µA, 105.8597µA and 103.5278µA respectively.

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

Science.gov (United States)

Driscoll, Richard; Holt, Bruce; Hunter, Lori

2005-01-01

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…

Using the accelerated Brazilian concrete prism test (ABCPT to evaluate alkali aggregate reaction (AAR

Directory of Open Access Journals (Sweden)

L. Sanchez

Full Text Available There are many test methods used in the laboratory to detect potential alkali-aggregate reactions (AAR. However, up to now, there is no consensus if they are reliable and efficient. This work presents the development of a new and accelerated concrete prism test called ABCPT (accelerate Brazilian concrete prism test as an attempt to create a reliable and fast test that can analyze and classify the potential reactivity of aggregates in the laboratory. For this research, six aggregates from different lithotypes were used. The methods CPT, ACPT and ABCPT were carried out with all the aggregates and a comparative analysis among all tests was performed. ABCPT seems to have a great potential to analyze and classify aggregates in the laboratory, although it needs further testing with other lithotypes to be confirmed as feasible.

Testing and interfacing intelligent power supplies for the Los Alamos National Laboratory Accelerator Complex

International Nuclear Information System (INIS)

Sturrock, J.C.; Cohen, S.; Weintraub, B.L.; Hayden, D.J.; Archuleta, S.F.

1992-01-01

New high-current, high-precision microprocessor-controlled power supplies, built by Alpha Scientific Electronics of Hayward, CA, have been installed at the Los Alamos National Laboratory Accelerator Complex. Each unit has sophisticated microprocessor control on-board and communicates via RS-422 (serial communications). The units use a high level ASCII-based control protocol. Performance tests were conducted to verify adherence to specification and to ascertain ultimate long-term stability. The ''front-end'' software used by the accelerator control system has been written to accommodate these new devices. The supplies are interfaced to the control system through a terminal server port connected to the site-wide ediernet backbone. Test design and results as well as details of the software implementation for the analog and digital control of the supplies through the accelerator control system are presented

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

Science.gov (United States)

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

2008-01-01

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

Accelerated testing for studying pavement design and performance (FY 2004) : research summary.

Science.gov (United States)

2009-03-01

The thirteenth full-scale Accelerated Pavement Test (APT) experiment at the Civil Infrastructure Laboratory (CISL) of Kansas State University aimed to determine the response and the failure mode of thin concrete overlays.

Evaluation of accelerated test parameters for CMOS IC total dose hardness prediction

International Nuclear Information System (INIS)

Sogoyan, A.V.; Nikiforov, A.Y.; Chumakov, A.I.

1999-01-01

The approach to accelerated test parameters evaluation is presented in order to predict CMOS IC total dose behavior in variable dose-rate environment. The technique is based on the analytical model of MOSFET parameters total dose degradation. The simple way to estimate model parameter is proposed using IC's input-output MOSFET radiation test results. (authors)

Facility-level association of preoperative stress testing and postoperative adverse cardiac events.

Science.gov (United States)

Valle, Javier A; Graham, Laura; Thiruvoipati, Thejasvi; Grunwald, Gary; Armstrong, Ehrin J; Maddox, Thomas M; Hawn, Mary T; Bradley, Steven M

2018-06-22

Despite limited indications, preoperative stress testing is often used prior to non-cardiac surgery. Patient-level analyses of stress testing and outcomes are limited by case mix and selection bias. Therefore, we sought to describe facility-level rates of preoperative stress testing for non-cardiac surgery, and to determine the association between facility-level preoperative stress testing and postoperative major adverse cardiac events (MACE). We identified patients undergoing non-cardiac surgery within 2 years of percutaneous coronary intervention in the Veterans Affairs (VA) Health Care System, from 2004 to 2011, facility-level rates of preoperative stress testing and postoperative MACE (death, myocardial infarction (MI) or revascularisation within 30 days). We determined risk-standardised facility-level rates of stress testing and postoperative MACE, and the relationship between facility-level preoperative stress testing and postoperative MACE. Among 29 937 patients undergoing non-cardiac surgery at 131 VA facilities, the median facility rate of preoperative stress testing was 13.2% (IQR 9.7%-15.9%; range 6.0%-21.5%), and 30-day postoperative MACE was 4.0% (IQR 2.4%-5.4%). After risk standardisation, the median facility-level rate of stress testing was 12.7% (IQR 8.4%-17.4%) and postoperative MACE was 3.8% (IQR 2.3%-5.6%). There was no correlation between risk-standardised stress testing and composite MACE at the facility level (r=0.022, p=0.81), or with individual outcomes of death, MI or revascularisation. In a national cohort of veterans undergoing non-cardiac surgery, we observed substantial variation in facility-level rates of preoperative stress testing. Facilities with higher rates of preoperative stress testing were not associated with better postoperative outcomes. These findings suggest an opportunity to reduce variation in preoperative stress testing without sacrificing patient outcomes. © Article author(s) (or their employer(s) unless otherwise

Stress og aldring

DEFF Research Database (Denmark)

Jørgensen, Anders; Jørgensen, Martin Balslev; Poulsen, Henrik Enghusen

2012-01-01

Accumulating evidence supports the popular notion that psychological stress states may accelerate aging. Stress has been shown to influence cellular systems known to be involved in the aging process. Furthermore, stress is associated with an increased risk of various age-related medical disorders....... These effects are likely mediated by the secretion of stress hormones. In this short review we focus on biochemical and epidemiological evidence for a link between stress and aging.......Accumulating evidence supports the popular notion that psychological stress states may accelerate aging. Stress has been shown to influence cellular systems known to be involved in the aging process. Furthermore, stress is associated with an increased risk of various age-related medical disorders...

[Stress-corrosion test of TIG welded CP-Ti].

Science.gov (United States)

Li, H; Wang, Y; Zhou, Z; Meng, X; Liang, Q; Zhang, X; Zhao, Y

2000-12-01

In this study TIG (Tungsten Inert Gas) welded CP-Ti were subjected to stress-corrosion test under 261 MPa in artificial saliva of 37 degrees C for 3 months. No significant difference was noted on mechanical test (P > 0.05). No color-changed and no micro-crack on the sample's surface yet. These results indicate that TIG welded CP-Ti offers excellent resistance to stress corrosion.

Virtual accelerator concept, implementation and preliminary test

International Nuclear Information System (INIS)

Uriot, D.; Duperrier, R.

2006-05-01

A virtual accelerator is the coupling of a simulation code with the control system of a real machine. 3 operating modes are considered. First, the monitoring mode in which any action on the control system has an impact on both real and virtual machines. This mode allows a direct comparison between simulation results and the real behaviour of the accelerator. Secondly, the flight simulation mode, this mode allows the accelerator operators to simulate the effect of any change in the parameters of the control system before transferring them to the real machine. The main advantage of this mode is to allow the assessment of operating procedures before implementing them on the real machine. The third mode is the automatic steering mode in which the simulation code assumes the reins of the control system of the real machine. This mode allows the making of complex and time-consuming adjustment procedures in an automatic way. TraceWin is a simulation code dedicated to the behaviour of charged-particle beams in a linear accelerator. TraceWin is consistent with the EPICS technology on which the control system of most accelerators is based. A virtual accelerator composed of the SILHI injector combined to the TraceWin code via the EPICS environment has showed its efficiency in the automatic steering mode. (A.C.)

Microscopic creep models and the interpretation of stress-dip tests during creep

International Nuclear Information System (INIS)

Poirier, J.P.

1976-09-01

A critical analysis is made of the principal divergent view points concerning stress-dip tests. The raw data are examined and interpreted in the light of various creep models. The following problems are discussed: is the reverse strain anelastic or plastic; is the zero creep rate periodic due to recovery or is it spurious; can the existence or inexistence of an internal stress be deduced from stress-dip tests; can stress-dip tests allow to determine whether glide is jerky or viscous; can the internal stress be measured by stress-dip tests

Safety enhancement of composites via periodic proof testing

OpenAIRE

Woodward, Joseph H.

1993-01-01

Approved for public release; distribution is unlimited. The development of new composite materials, which lack the historical field data base, has led to the need for an accelerated life testing method applicable to composites. Accelerated life testing by increasing the sustained stress levels requires the modeling and validation of a strength-life relation. Proof testing of composite fibers by over-loading is one step in the understanding of the relationship. It is also important in the r...

Accelerated pavement testing of thin RCC over soil cement pavements

Directory of Open Access Journals (Sweden)

Zhong Wu

2016-05-01

Full Text Available Three full-scale roller compacted concrete (RCC pavement sections built over a soil cement base were tested under accelerated pavement testing (APT. The RCC thicknesses varied from 102 mm (4 in. to 152 mm (6 in. and to 203 mm (8 in., respectively. A bi-directional loading device with a dual-tire load assembly was used for this experiment. Each test section was instrumented with multiple pressure cells and strain gages. The objective was to evaluate the structural performance and load carrying capacity of thin RCC-surfaced pavements under accelerated loading. The APT results generally indicated that all three RCC pavement sections tested in this study possessed very high load carrying capacity; an estimated pavement life in terms of equivalent single axle load (ESAL for the thinnest RCC section (i.e., RCC thickness of 102 mm evaluated was approximately 19.2 million. It was observed that a fatigue failure would be the primary pavement distress type for a thin RCC pavement under trafficking. Specifically, the development of fatigue cracking was found to originate from a longitudinal crack at the edge or in the center of a tire print, then extended and propagated, and eventually merged with cracks of other directions. Instrumentation results were used to characterize the fatigue damage under different load magnitudes. Finally, based on the APT performance of this experiment, two fatigue models for predicting the fatigue life of thin RCC pavements were developed. Keywords: Roller compacted concrete, APT, Pavement performance, Non-destructive testing, Fatigue analysis

An introduction to the 'Psycho-Physiological-Stress-Test' (PPST-A standardized instrument for evaluating stress reactions.

Directory of Open Access Journals (Sweden)

Elisabeth Neureiter

Full Text Available Using a standardized instrument to evaluate patients' stress reactions has become more important in daily clinical routines. Different signs or symptoms of stress are often unilaterally explored: the physiological, psychological or social aspects of stress disorders are each viewed on a single dimension. However, all dimensions afflict patients who have persistent health problems due to chronic stress. Therefore, it is important to use a multidimensional approach to acquire data. The 'Psycho-Physiological-Stress-Test' (PPST was established to achieve a comprehensive understanding of stress and was further developed at the Charité-Universitätsmedizin Berlin in collaboration with the Psychological Department of Freie Universität Berlin. The PPST includes a series of varying stress phases, embedded in two periods of rest. Physiological and psychological parameters are simultaneously measured throughout the test session. Specifically, the PPST activates the sympathetic stress axis, which is measured by heart rate, blood pressure, respiration depth and rate, electro dermal activation and muscle tension (frontalis, masseter, trapezius. Psychological data are simultaneously collected, and include performance, motivation, emotion and behavior. After conducting this diagnostic test, it is possible to identify individual stress patterns that can be discussed with the individual patient to develop and recommend (outpatient treatment strategies. This paper introduces the PPST as a standardized way to evaluate stress reactions by presenting the results from a sample of psychosomatic inpatients (n = 139 who were treated in Charité-Universitätsmedizin Berlin, Germany. We observed that the varying testing conditions provoked adjusted changes in the different physiological parameters and psychological levels.

An experimental test of Newton's law of gravitation for small accelerations

International Nuclear Information System (INIS)

Schubert, Sven

2011-10-01

The experiment presented in this thesis has been designed to test Newton's law of gravitation in the limit of small accelerations caused by weak gravitational forces. It is located at DESY, Hamburg, and is a modification of an experiment that was carried out in Wuppertal, Germany, until 2002 in order to measure the gravitational constant G. The idea of testing Newton's law in the case of small accelerations emerged from the question whether the flat rotation curves of spiral galaxies can be traced back to Dark Matter or to a law of gravitation that deviates from Newton on cosmic scales like e.g. MOND (Modified Newtonian Dynamics). The core of this experiment is a microwave resonator which is formed by two spherical concave mirrors that are suspended as pendulums. Masses between 1 and 9 kg symmetrically change their distance to the mirrors from far to near positions. Due to the increased gravitational force the mirrors are pulled apart and the length of the resonator increases. This causes a shift of the resonance frequency which can be translated into a shift of the mirror distance. The small masses are sources of weak gravitational forces and cause accelerations on the mirrors of about 10 -10 m/s 2 . These forces are comparable to those between stars on cosmic scales and the accelerations are in the vicinity of the characteristic acceleration of MOND a 0 ∼ 1.2.10 -10 m/s 2 , where deviations from Newton's law are expected. Thus Newton's law could be directly checked for correctness under these conditions. First measurements show that due to the sensitivity of this experiment many systematic influences have to be accounted for in order to get consistent results. Newton's law has been confirmed with an accuracy of 3%. MOND has also been checked. In order to be able to distinguish Newton from MOND with other interpolation functions the accuracy of the experiment has to be improved. (orig.)

Workshop on Accelerator Operation (WAO 2001)

International Nuclear Information System (INIS)

Bailey, R.

2001-01-01

The 3rd Workshop on Accelerator Operation (WAO 2001) followed earlier workshops in 1996 and 1998. Most topics relevant for the efficient and effective operation of accelerators were covered. These included the tools and utilities necessary in the control rooms; the organization of accelerator operation (process monitoring, shift work, stress); the monitoring of beam quality; safety issues and standards; and questions particularly relevant for superconducting accelerators, in particular cryogenics. (author)

ACCELERATED AGING TEST IN DETERMINING THE VIGOUR OF SUNFLOWER SEEDS WITH AND WITHOUT PERICARP

Directory of Open Access Journals (Sweden)

K. R. Ducatti

2014-09-01

Full Text Available The standard germination test alone is insufficient to attest the quality of seeds, making necessary correlation’s with vigour tests, to determine more accurately the physiological potential of a seeds lot. The accelerated aging test is an option for determine the vigour and consists in submits seeds to high temperatures and humidity, for different periods of time, has not yet standardized. The objective of this work was to analyze the efficiency of the accelerated aging test in the assessment of the effect of a lot of sunflower seed, by three periods of aging (48, 56 and 72 hours in 42 °C temperature, in seeds with and without pericarp (manually removed and relate the results with electrical conductivity test and germination first count. The experimental design was a completely randomized design and the comparison of averages made using Tukey's test at 5% probability. The results showed that standard germination, electrical conductivity and germination first count, the seeds without pericarp showed better performance. In relation to the accelerated aging, only in the period of 72 hours of aging there was no significant difference between the treatments. In this way, the appropriate period to identify differences in force between the treatments was 72 hours, which showed a positive correlation with the germination first count and electrical conductivity.

Accelerated radiation damage test facility using a 5 MV tandem ion accelerator