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Sample records for accelerated degradation tests

  1. Membrane Degradation Accelerated Stress Test

    SciTech Connect

    Mukundan, Rangachary; Borup, Rodney L.

    2015-01-21

    These are a set of slides that deal with membrane degradation accelerated stress test. Specifically, the following topics are covered: membrane degradation FCTT drive cycle; membrane ASTs; current membrane ASTs damage mechanisms; proposed membrane AST, RH cycling in H2/Air; current proposed AST; 2min/2min AST damage mechanism; 30sec/45sec RH cycling at OCV.

  2. Accelerated Testing Of Photothermal Degradation Of Polymers

    NASA Technical Reports Server (NTRS)

    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.

  3. Degradation mechanisms and accelerated aging test design

    SciTech Connect

    Clough, R L; Gillen, K T

    1985-01-01

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

  4. Step-Stress Accelerated Degradation Testing for Solar Reflectors: Preprint

    SciTech Connect

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

    2011-09-01

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

  5. Degradation mechanisms and accelerated testing in PEM fuel cells

    SciTech Connect

    Borup, Rodney L; Mukundan, Rangachary

    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

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

    SciTech Connect

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

    2010-10-01

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

  7. Degradation Mechanisms and Accelerated Testing in PEM Fuel Cells

    SciTech Connect

    Borup, Rodney L.

    2011-01-01

    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 or 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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    SciTech Connect

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

    2011-09-01

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

  10. An iterative method for accelerated degradation testing data of smart electricity meter

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; Xie, Jinzhe

    2017-01-01

    In order to evaluate the performance of smart electricity meter (SEM), we must spend a lot of time censoring its status. For example, if we assess to the meter stability of the SEM which needs several years at least according to the standards. So accelerated degradation testing (ADT) is a useful method to assess the performance of the SEM. As we known, the Wiener process is a prevalent method to interpret the performance degradation. This paper proposes an iterative method for ADT data of SEM. The simulation study verifies the application and superiority of the proposed model than other ADT methods.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  13. Effects of UV on power degradation of photovoltaic modules in combined acceleration tests

    NASA Astrophysics Data System (ADS)

    Ngo, Trang; Heta, Yushi; Doi, Takuya; Masuda, Atsushi

    2016-05-01

    UV exposure and other factors such as high/low temperature, humidity and mechanical stress have been reported to degrade photovoltaic (PV) module materials. By focusing on the combined effects of UV stress and moisture on PV modules, two new acceleration tests of light irradiation and damp heat (DH) were designed and conducted. The effects of UV exposure were validated through a change in irradiation time (UV dosage) and a change of the light irradiation side (glass side vs backsheet side) in the UV-preconditioned DH and cyclic sequential tests, respectively. The chemical corrosion of finger electrodes in the presence of acetic acid generated from ethylene vinyl acetate used as an encapsulant was considered to be the main origin of degradation. The module performance characterized by electroluminescence images was confirmed to correlate with the measured acetic acid concentration and Ag finger electrode resistance.

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

    NASA Astrophysics Data System (ADS)

    Albin, David S.

    2008-08-01

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

  15. Experimental design and analysis for accelerated degradation tests with Li-ion cells.

    SciTech Connect

    Doughty, Daniel Harvey; Thomas, Edward Victor; Jungst, Rudolph George; Roth, Emanuel Peter

    2003-08-01

    This document describes a general protocol (involving both experimental and data analytic aspects) that is designed to be a roadmap for rapidly obtaining a useful assessment of the average lifetime (at some specified use conditions) that might be expected from cells of a particular design. The proposed experimental protocol involves a series of accelerated degradation experiments. Through the acquisition of degradation data over time specified by the experimental protocol, an unambiguous assessment of the effects of accelerating factors (e.g., temperature and state of charge) on various measures of the health of a cell (e.g., power fade and capacity fade) will result. In order to assess cell lifetime, it is necessary to develop a model that accurately predicts degradation over a range of the experimental factors. In general, it is difficult to specify an appropriate model form without some preliminary analysis of the data. Nevertheless, assuming that the aging phenomenon relates to a chemical reaction with simple first-order rate kinetics, a data analysis protocol is also provided to construct a useful model that relates performance degradation to the levels of the accelerating factors. This model can then be used to make an accurate assessment of the average cell lifetime. The proposed experimental and data analysis protocols are illustrated with a case study involving the effects of accelerated aging on the power output from Gen-2 cells. For this case study, inadequacies of the simple first-order kinetics model were observed. However, a more complex model allowing for the effects of two concurrent mechanisms provided an accurate representation of the experimental data.

  16. Acceleration tests: Degradation of anode-supported planar solid oxide fuel cells at elevated operating temperatures

    NASA Astrophysics Data System (ADS)

    Kim, Sun Jae; Choi, Moon-Bong; Park, Mansoo; Kim, Hyoungchul; Son, Ji-Won; Lee, Jong-Ho; Kim, Byung-Kook; Lee, Hae-Weon; Kim, Seung-Goo; Yoon, Kyung Joong

    2017-08-01

    As the solid oxide fuel cell (SOFC) technology matures, durability under real operating conditions is considered as one of the most critical issues for commercialization. The severe conditions encountered in practical operation include a large temperature gradient and generation of local hot spots within stacks. Herein, we report the degradation mechanisms of anode-supported planar SOFCs supplied by Posco Energy at elevated operating temperatures. A simple comparison of the voltage reduction rates at different operating temperatures does not appropriately represent the degree of degradation, because the rapid deterioration of the cell components at high temperatures is compensated for by the fast reaction and transport kinetics. A combination of impedance interpretation and post-mortem analysis reveals the major degradation processes that are distinctively accelerated by increasing temperature, including the chemical interaction between the cathode and electrolyte, the enlargement of the interfacial pores, the coarsening of the fine particles in the composite electrodes, the formation of interfacial cracks and Cr poisoning. Systematic analysis presented in this study provides guidelines for counteracting the unexpected temperature increase, and the database established under various extreme conditions would form the groundwork for achieving the lifetime goals of commercial SOFC systems.

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

    NASA Astrophysics Data System (ADS)

    Lai, Yeh-Hung; Fly, Gerald W.

    2015-01-01

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

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

    SciTech Connect

    Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent; Perrin, Greg; Glick, Stephen; Kurtz, Sarah; Wohlgemuth, John

    2015-06-14

    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 power degradation data obtained semi-continuously and statistically by in-situ dark current-voltage measurements in an environmental chamber. The modeling enables prediction of degradation rates and times as functions of temperature and humidity. Power degradation could be modeled linearly as a function of time to the second power; additionally, we found that coulombs transferred from the active cell circuit to ground during the stress test is approximately linear with time. Therefore, the power loss could be linearized as a function of coulombs squared. With this result, we observed that when the module face was completely grounded with a condensed phase conductor, leakage current exceeded the anticipated corresponding degradation rate relative to the other tests performed in damp heat.

  19. Accelerated Degradation Test and Predictive Failure Analysis of B10 Copper-Nickel Alloy under Marine Environmental Conditions

    PubMed Central

    Sun, Bo; Ye, Tianyuan; Feng, Qiang; Yao, Jinghua; Wei, Mumeng

    2015-01-01

    This paper studies the corrosion behavior of B10 copper-nickel alloy in marine environment. Accelerated degradation test under marine environmental conditions was designed and performed based on the accelerated testing principle and the corrosion degradation mechanism. With the prolongation of marine corrosion time, the thickness of Cu2O film increased gradually. Its corrosion product was Cu2(OH)3Cl, which increased in quantity over time. Cl− was the major factor responsible for the marine corrosion of copper and copper alloy. Through the nonlinear fitting of corrosion rate and corrosion quantity (corrosion weight loss), degradation data of different corrosion cycles, the quantitative effects of two major factors, i.e., dissolved oxygen (DO) and corrosion medium temperature, on corrosion behavior of copper alloy were analyzed. The corrosion failure prediction models under different ambient conditions were built. One-day corrosion weight loss under oxygenated stirring conditions was equivalent to 1.31-day weight loss under stationary conditions, and the corrosion rate under oxygenated conditions was 1.31 times higher than that under stationary conditions. In addition, corrosion medium temperature had a significant effect on the corrosion of B10 copper sheet. PMID:28793549

  20. Ethylene propylene cable degradation during LOCA research tests: tensile properties at the completion of accelerated aging

    SciTech Connect

    Bustard, L.D.

    1982-05-01

    Six ethylene-propylene rubber (EPR) insulation materials were aged at elevated temperature and radiation stress exposures common in cable LOCA qualification tests. Material samples were subjected to various simultaneous and sequential aging simulations in preparation for accident environmental exposures. Tensile properties subsequent to the aging exposure sequences are reported. The tensile properties of some, but not all, specimens were sensitive to the order of radiation and elevated temperature stress exposure. Other specimens showed more severe degradation when simultaneously exposed to radiation and elevated temperature as opposed to the sequential exposure to the same stresses. Results illustrate the difficulty in defining a single test procedure for nuclear safety-related qualification of EPR elastomers. A common worst-case sequential aging sequence could not be identified.

  1. Degradation mechanism of LiCoO2/mesocarbon microbeads battery based on accelerated aging tests

    NASA Astrophysics Data System (ADS)

    Guan, Ting; Zuo, Pengjian; Sun, Shun; Du, Chunyu; Zhang, Lingling; Cui, Yingzhi; Yang, Lijie; Gao, Yunzhi; Yin, Geping; Wang, Fuping

    2014-12-01

    A series of LiCoO2/mesocarbon microbeads (MCMB) commercial cells cycled at different rates (0.6C, 1.2C, 1.5C, 1.8C, 2.4C and 3.0C) are disassembled and the capacity fade mechanism is proposed by analyzing the structure, morphology and electrochemical performance evolution at the capacity retention of 95%, 90%, 85%, 80%. The capacity deterioration of the commercial cell is mainly caused by the decay of the reversible capacity of LiCoO2 cathode, the irreversible loss of active lithium and the lithium remaining in anode. The proportions of effects by the above three factors are calculated accurately. The consumption of the active lithium leads to a cell imbalance between the anode and the cathode. The electrochemical test results indicate that the capacity fade of the active materials at the low rate is more obvious than that at the high rate. The influence of the active lithium is gradually increscent with the increasing rate. The rate of 1.5C is the optimal value to accelerate the aging of the full cell by comparing the testing results at different capacity retentions in the specific condition of low charge/discharge rate and shallow depth of discharge.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    SciTech Connect

    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 BZO layers on CIGS

  4. Effect of TiO2-Crystal Forms on the Photo-Degradation of EVA/PLA Blend Under Accelerated Weather Testing

    NASA Astrophysics Data System (ADS)

    Van Cong, Do; Trang, Nguyen Thi Thu; Giang, Nguyen Vu; Lam, Tran Dai; Hoang, Thai

    2016-05-01

    Photo-degradation of poly (ethylene-co-vinyl acetate) (EVA)/poly (lactic acid) (PLA) blend and EVA/PLA/TiO2 nanocomposites was carried out under accelerated weather testing conditions by alternating cycles of ultraviolet (UV) light and moisture at controlled and elevated temperatures. The characters, properties, and morphology of these materials before and after accelerated weather testing were determined by Fourier transform infrared spectroscopy, colour changes, viscosity, tensile test, thermogravimetric analysis, and field emission scanning electron microscopy. The increases in the content of oxygen-containing groups, colour changes; the decreases in viscosity, tensile properties, and thermal stability of these materials after accelerated weather testing are the evidence for the photo-degradation of the blend and nanocomposites. After accelerated weather testing, the appearance of many micro-holes and micro-pores on the surface of the collected samples was observed. The photo-degradation degree of the nanocomposites depended on the TiO2-crystal form. Rutile TiO2 do not enhance the degradation, but anatase and mixed crystals TiO2 nanoparticles promoted the degradation of the nanocomposites. Particularly, the mixed crystals TiO2 nanoparticles showed the highest photo-catalytic activity of the nanocomposites.

  5. HPLC and HPLC/MS/MS Studies on Stress, Accelerated and Intermediate Degradation Tests of Antivirally Active Tricyclic Analog of Acyclovir.

    PubMed

    Lesniewska, Monika A; Dereziński, Paweł; Klupczyńska, Agnieszka; Kokot, Zenon J; Ostrowski, Tomasz; Zeidler, Joanna; Muszalska, Izabela

    2015-01-01

    The degradation behavior of a tricyclic analog of acyclovir [6-(4-MeOPh)-TACV] was determined in accordance with International Conference on Harmonization guidelines for good clinical practice under different stress conditions (neutral hydrolysis, strong acid/base degradation, oxidative decomposition, photodegradation, and thermal degradation). Accelerated [40±2°C/75%±5% relative humidity (RH)] and intermediate (30±2°C/65%±5% RH) stability tests were also performed. For observation of the degradation of the tested compound the RP-HPLC was used, whereas for the analysis of its degradation products HPLC/MS/MS was used. Degradation of the tested substance allowed its classification as unstable in neutral environment, acidic/alkaline medium, and in the presence of oxidizing agent. The tested compound was also light sensitive and was classified as photolabile both in solution and in the solid phase. However, the observed photodegradation in the solid phase was at a much lower level than in the case of photodegradation in solution. The study showed that both air temperature and RH had no significant effect on the stability of the tested substance during storage for 1 month at 100°C (dry heat) as well as during accelerated and intermediate tests. Based on the HPLC/MS/MS analysis, it can be concluded that acyclovir was formed as a degradation product of 6-(4-MeOPh)-TACV.

  6. Accelerated test design

    NASA Technical Reports Server (NTRS)

    Mcdermott, P. P.

    1980-01-01

    The design of an accelerated life test program for electric batteries is discussed. A number of observations and suggestions on the procedures and objectives for conducting an accelerated life test program are presented. Equations based on nonlinear regression analysis for predicting the accelerated life test parameters are discussed.

  7. Accelerated Stress-Corrosion Testing

    NASA Technical Reports Server (NTRS)

    1986-01-01

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

  8. Accelerated Stress-Corrosion Testing

    NASA Technical Reports Server (NTRS)

    1986-01-01

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

  9. Environmental aging in polycrystalline-Si photovoltaic modules: comparison of chamber-based accelerated degradation studies with field-test data

    NASA Astrophysics Data System (ADS)

    Lai, T.; Biggie, R.; Brooks, A.; Potter, B. G.; Simmons-Potter, K.

    2015-09-01

    Lifecycle degradation testing of photovoltaic (PV) modules in accelerated-degradation chambers can enable the prediction both of PV performance lifetimes and of return-on-investment for installations of PV systems. With degradation results strongly dependent on chamber test parameters, the validity of such studies relative to fielded, installed PV systems must be determined. In the present work, accelerated aging of a 250 W polycrystalline silicon module is compared to real-time performance degradation in a similar polycrystalline-silicon, fielded, PV technology that has been operating since October 2013. Investigation of environmental aging effects are performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability providing illumination uniformity of 98% over a 2 x 1.6 m area. Time-dependent, photovoltaic performance (J-V) is evaluated over a recurring, compressed night-day cycle providing representative local daily solar insolation for the southwestern United States, followed by dark (night) cycling. This cycle is synchronized with thermal and humidity environmental variations that are designed to mimic, as closely as possible, test-yard conditions specific to a 12 month weather profile for a fielded system in Tucson, AZ. Results confirm the impact of environmental conditions on the module long-term performance. While the effects of temperature de-rating can be clearly seen in the data, removal of these effects enables the clear interpretation of module efficiency degradation with time and environmental exposure. With the temperature-dependent effect removed, the normalized efficiency is computed and compared to performance results from another panel of similar technology that has previously experienced identical climate changes in the test yard. Analysis of relative PV module efficiency degradation for the chamber-tested system shows good comparison to the field-tested system with ~2.5% degradation following

  10. Accelerated degradation of silicon metallization systems

    NASA Technical Reports Server (NTRS)

    Lathrop, J. W.

    1983-01-01

    Clemson University has been engaged for the past five years in a program to determine the reliability attributes of solar cells by means of accelerated test procedures. The cells are electrically measured and visually inspected and then subjected for a period of time to stress in excess of that normally encountered in use, and then they are reinspected. Changes are noted and the process repeated. This testing has thus far involved 23 different unencapsulated cell types from 12 different manufacturers, and 10 different encapsulated cell types from 9 different manufacturers. Reliability attributes of metallization systems can be classified as major or minor, depending on the severity of the effects observed. As a result of the accelerated testing conducted under the Clemson program, major effects have been observed related to contact resistance and to mechanical adherence and solderability. This paper does not attempt a generalized survey of accelerated test results, but rather concentrates on one particular attribute of metallization that has been observed to cause electrical degradation - increased contact resistance due to Schottky barrier formation. In this example basic semiconductor theory was able to provide an understanding of the electrical effects observed during accelerated stress testing.

  11. Accelerated degradation of silicon metallization systems

    NASA Astrophysics Data System (ADS)

    Lathrop, J. W.

    1983-11-01

    Clemson University has been engaged for the past five years in a program to determine the reliability attributes of solar cells by means of accelerated test procedures. The cells are electrically measured and visually inspected and then subjected for a period of time to stress in excess of that normally encountered in use, and then they are reinspected. Changes are noted and the process repeated. This testing has thus far involved 23 different unencapsulated cell types from 12 different manufacturers, and 10 different encapsulated cell types from 9 different manufacturers. Reliability attributes of metallization systems can be classified as major or minor, depending on the severity of the effects observed. As a result of the accelerated testing conducted under the Clemson program, major effects have been observed related to contact resistance and to mechanical adherence and solderability. This paper does not attempt a generalized survey of accelerated test results, but rather concentrates on one particular attribute of metallization that has been observed to cause electrical degradation - increased contact resistance due to Schottky barrier formation. In this example basic semiconductor theory was able to provide an understanding of the electrical effects observed during accelerated stress testing.

  12. Acceleration of purine degradation by periodontal diseases.

    PubMed

    Barnes, V M; Teles, R; Trivedi, H M; Devizio, W; Xu, T; Mitchell, M W; Milburn, M V; Guo, L

    2009-09-01

    Periodontal diseases, such as gingivitis and periodontitis, are characterized by bacterial plaque accumulation around the gingival crevice and the subsequent inflammation and destruction of host tissues. To test the hypothesis that cellular metabolism is altered as a result of host-bacteria interaction, we performed an unbiased metabolomic profiling of gingival crevicular fluid (GCF) collected from healthy, gingivitis, and periodontitis sites in humans, by liquid and gas chromatography mass spectrometry. The purine degradation pathway, a major biochemical source for reactive oxygen species (ROS) production, was significantly accelerated at the disease sites. This suggests that periodontal-disease-induced oxidative stress and inflammation are mediated through this pathway. The complex host-bacterial interaction was further highlighted by depletion of anti-oxidants, degradation of host cellular components, and accumulation of bacterial products in GCF. These findings provide new mechanistic insights and a panel of comprehensive biomarkers for periodontal disease progression.

  13. Accelerated Corrosion Testing

    DTIC Science & Technology

    1982-12-01

    conducted on high-strength 4340 steel and 7075-T6 aluminum alloy usina accelerating pollutants such as sulfur dinxide, nitrogen dioxide, surface salt...CONTROLLED 100 ATMOSPHERES APPiENDIX B - ACCELERATED ATMDSPHERIC-CORROSION TESTING 128 v I. LIST OF ILLUSTRATIONS Ficure Page 1 Schematic Diagram of Applied...Static-Load Crack-Growth Rate (from ref. 17). 26 12 Environmental-System Flow Diagram . 33 13 Compact-Tension Plane-Strain Fracture-Toughness Specimen

  14. Accelerated Testing Validation

    SciTech Connect

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

    2011-07-01

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

  15. Analysis of insulation resistance degradation in Ni–BaTiO3 multilayer ceramic capacitors under highly accelerated life test

    NASA Astrophysics Data System (ADS)

    Sada, Takao; Fujikawa, Nobuyoshi

    2017-10-01

    The degradation mechanism of electrical breakdown in Ni–BaTiO3 multilayer ceramic capacitors (MLCCs) was studied by visualizing degraded areas in early failure and wear-out failure modes. The visualization was achieved by the fabrication of electrically degraded MLCCs just before electrical breakdown and by detection of the degraded area by infrared-optical-beam-induced resistance change (IR-OBIRCH) analysis. In the case of our prototype MLCCs, a thinner dielectric layer caused early failure and microstructural abnormalities in the dielectric layer caused wear-out failure. Such a visualization method directly demonstrates the causes of electrical breakdown in MLCCs.

  16. Statistical Modeling of Photovoltaic Reliability Using Accelerated Degradation Techniques (Poster)

    SciTech Connect

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

    2011-02-01

    We introduce a cutting-edge life-testing technique, accelerated degradation testing (ADT), for PV reliability testing. The ADT technique is a cost-effective and flexible reliability testing method with multiple (MADT) and Step-Stress (SSADT) variants. In an environment with limited resources, including equipment (chambers), test units, and testing time, these techniques can provide statistically rigorous prediction of lifetime and other interesting parameters, such as failure rate, warranty time, mean time to failure, degradation rate, activation energy, acceleration factor, and upper limit level of stress. J-V characterization can be used for degradation data and the generalized Eyring model can be used for the thermal-humidity stress condition. The SSADT model can be constructed based on the cumulative damage model (CEM), which assumes that the remaining test united are failed according to cumulative density function of current stress level regardless of the history on previous stress levels.

  17. Antifoam degradation testing

    SciTech Connect

    Lambert, D. P.; Zamecnik, J. R.; Newell, D. D.; Williams, M. S.

    2015-08-20

    This report describes the results of testing to quantify the degradation products resulting from the dilution and storage of Antifoam 747. Antifoam degradation is of concern to the Defense Waste Processing Facility (DWPF) due to flammable decomposition products in the vapor phase of the Chemical Process Cell vessels, as well as the collection of flammable and organic species in the offgas condensate. The discovery that hexamethyldisiloxane is formed from the antifoam decomposition was the basis for a Potential Inadequacy in the Safety Analysis declaration by the DWPF.

  18. Accelerated stress testing of terrestrial solar cells

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  19. Accelerated stress testing of terrestrial solar cells

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  20. Accelerated stress testing of terrestrial solar cells

    SciTech Connect

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

    1982-08-01

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

  1. Accelerating degradation rate of pure iron by zinc ion implantation.

    PubMed

    Huang, Tao; Zheng, Yufeng; Han, Yong

    2016-12-01

    Pure iron has been considered as a promising candidate for biodegradable implant applications. However, a faster degradation rate of pure iron is needed to meet the clinical requirement. In this work, metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron. Results showed that the implantation depth of zinc ions was about 60 nm. The degradation rate of pure iron was found to be accelerated after zinc ion implantation. The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells. In terms of hemocompatibility, the hemolysis of zinc ion implanted pure iron was lower than 2%. However, zinc ions might induce more adhered and activated platelets on the surface of pure iron. Overall, zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications.

  2. Accelerating degradation rate of pure iron by zinc ion implantation

    PubMed Central

    Huang, Tao; Zheng, Yufeng; Han, Yong

    2016-01-01

    Pure iron has been considered as a promising candidate for biodegradable implant applications. However, a faster degradation rate of pure iron is needed to meet the clinical requirement. In this work, metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron. Results showed that the implantation depth of zinc ions was about 60 nm. The degradation rate of pure iron was found to be accelerated after zinc ion implantation. The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells. In terms of hemocompatibility, the hemolysis of zinc ion implanted pure iron was lower than 2%. However, zinc ions might induce more adhered and activated platelets on the surface of pure iron. Overall, zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications. PMID:27482462

  3. A General Accelerated Degradation Model Based on the Wiener Process

    PubMed Central

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

    2016-01-01

    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. PMID:28774107

  4. Accelerated stress testing of terrestrial solar cells

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    A program to investigate the reliability characteristics of unencapsulated low-cost terrestrial solar cells using accelerated stress testing is described. Reliability (or parametric degradation) factors appropriate to the cell technologies and use conditions were studied and a series of accelerated stress tests was synthesized. An electrical measurement procedure and a data analysis and management system was derived, and stress test fixturing and material flow procedures were set up after consideration was given to the number of cells to be stress tested and measured and the nature of the information to be obtained from the process. Selected results and conclusions are presented.

  5. Diagnosis of MEA degradation under accelerated relative humidity cycling

    NASA Astrophysics Data System (ADS)

    Vengatesan, S.; Fowler, Michael W.; Yuan, Xiao-Zi; Wang, Haijiang

    The objective of this work is to identify the failure mode diagnosis protocols for polymer electrolyte membrane (PEM) fuel cells with the use of accelerated testing conditions. The single cells used in this work were constructed using commercial Ion Power ® membrane electrode assemblies (MEAs) and the performance degradation was studied under accelerated dynamic reactant relative humidity (RH) conditions. The influence of RH on cell performance was investigated, and a strong dependence of degradation with respect to relative humidity was found. RH cycling was seen to not only cause the gradual decrease in performance at the beginning of cell operation, but it was also related to the rapid decline in performance observed after 330 h operation. This change in degradation rate is seen a change in the material degradation failure mechanism at this point in the operational history of the cell. The increase in cell resistance, membrane crossover, fluoride release rate and decrease in electrochemical surface area (ESA) were also observed with time, and these results were correlated to change in degradation rate. Infra-Red (IR) imaging of an aged MEA was utilized to show varying temperature profiles and outline the possibility of cracks, tears or pinholes in the membrane.

  6. Accelerated degradation of methyl iodide by agrochemicals.

    PubMed

    Zheng, Wei; Papiernik, Sharon K; Guo, Mingxin; Yates, Scott R

    2003-01-29

    The fumigant methyl iodide (MeI, iodomethane) is considered a promising alternative to methyl bromide (MeBr) for soil-borne pest control in high-cash-value crops. However, the high vapor pressure of MeI results in emissions of a significant proportion of the applied mass into the ambient air, and this may lead to pollution of the environment. Integrating the application of certain agrochemicals with soil fumigation provides a novel approach to reduce excessive fumigant emissions. This study investigated the potential for several agrochemicals that are commonly used in farming operations, including fertilizers and nitrification inhibitors, to transform MeI in aqueous solution. The pseudo-first-order hydrolysis half-life (t(1/2)) of MeI was approximately 108 d, while the transformation of MeI in aqueous solutions containing selected agrochemicals was more rapid, with t(1/2) < 100 d (t(1/2) < 0.5 d in some solutions containing nitrification inhibitors). The influence of these agrochemicals on the rate of MeI degradation in soil was also determined. Adsorption to soil apparently reduced the availability of some nitrification inhibitors in the soil aqueous phase and lowered the degradation rate in soil. In contrast, addition of the nitrification inhibitors thiourea and allylthiourea to soil significantly accelerated the degradation of MeI, possibly due to soil surface catalysis. The t(1/2) of MeI was <20 h in thiourea- and allylthiourea-amended soil, considerably less than that in unamended soil (t(1/2) > 300 h).

  7. Accelerators for Fusion Materials Testing

    NASA Astrophysics Data System (ADS)

    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

  8. Accelerators for Fusion Materials Testing

    NASA Astrophysics Data System (ADS)

    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

  9. Sequential and combined acceleration tests for crystalline Si photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Masuda, Atsushi; Yamamoto, Chizuko; Uchiyama, Naomi; Ueno, Kiyoshi; Yamazaki, Toshiharu; Mitsuhashi, Kazunari; Tsutsumida, Akihiro; Watanabe, Jyunichi; Shirataki, Jyunko; Matsuda, Keiko

    2016-04-01

    The sequential combination test for photovoltaic modules is effective for accelerating degradation to shorten the test time and for reproducing degradation phenomena observed in modules exposed outdoors for a long time. The damp-heat (DH) test, thermal-cycle (TC) test, humidity-freeze (HF) test or dynamic mechanical load (DML) test is combined for the test modules. It was confirmed that chemical corrosion degradation or physical mechanical degradation is reproduced by the combination of the above tests. Cracks on the back sheet and delamination, often observed upon outdoor exposure, were well reproduced by the combination of DH and TC tests and TC and HF tests, respectively. Sequential DH and TC tests and DML and TC tests accelerated the degradation. These sequential tests are expected to be effective in reducing the required time of indoor testing for ensuring long-term reliability.

  10. Accelerated testing of space batteries

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  11. Accelerated Test Methods

    NASA Technical Reports Server (NTRS)

    Jansen, Ralph

    1995-01-01

    Neural network systems were evaluated for use in predicting wear of mechanical systems. Three different neural network software simulation packages were utilized in order to create models of tribological wear tests. Representative simple, medium, and high complexity simulation packages were selected. Pin-on-disk, rub shoe, and four-ball tribological test data was used for training, testing, and verification of the neural network models. Results showed mixed success. The neural networks were able to predict results with some accuracy if the number of input variables was low or the amount of training data was high. Increased neural network complexity resulted in more accurate results, however there was a point of diminishing return. Medium complexity models were the best trade off between accuracy and computing time requirements. A NASA Technical Memorandum and a Society of Tribologists and Lubrication Engineers paper are being published which detail the work.

  12. Accelerated life testing of solar absorber coatings

    NASA Astrophysics Data System (ADS)

    Carlsson, Bo; Moeller, K.; Frei, Ulrich; Koehl, Michael

    1994-09-01

    Results from a comprehensive case study on accelerated life testing of some selective solar collector absorber coatings for DHW systems are reviewed. The study was conducted within Task X `Solar Materials Research and Development' of the IEA Solar Heating and Cooling Program from 1987 to 1992 and is unique due to its quantitative and systematic approach for durability assessment. The work of case study involved the development of both experimental and theoretical tools to aid the assessment of service life or absorber coatings. This entailed performance analysis, failure analysis, microclimate characterization, environmental resistance testing and life date analysis. Predicted in-service degradation of coatings from accelerated life testing was found to be in fairly good agreement both qualitatively and quantitatively with what was actually observed on coatings installed and tested for three years in solar collectors working under typical DHW conditions.

  13. Accelerated leach test development program

    SciTech Connect

    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.

  14. High Modulus Biodegradable Polyurethanes for Vascular Stents: Evaluation of Accelerated in vitro Degradation and Cell Viability of Degradation Products.

    PubMed

    Sgarioto, Melissa; Adhikari, Raju; Gunatillake, Pathiraja A; Moore, Tim; Patterson, John; Nagel, Marie-Danielle; Malherbe, François

    2015-01-01

    We have recently reported the mechanical properties and hydrolytic degradation behavior of a series of NovoSorb™ biodegradable polyurethanes (PUs) prepared by varying the hard segment (HS) weight percentage from 60 to 100. In this study, the in vitro degradation behavior of these PUs with and without extracellular matrix (ECM) coating was investigated under accelerated hydrolytic degradation (phosphate buffer saline; PBS/70°C) conditions. The mass loss at different time intervals and the effect of aqueous degradation products on the viability and growth of human umbilical vein endothelial cells (HUVEC) were examined. The results showed that PUs with HS 80% and below completely disintegrated leaving no visual polymer residue at 18 weeks and the degradation medium turned acidic due to the accumulation of products from the soft segment (SS) degradation. As expected the PU with the lowest HS was the fastest to degrade. The accumulated degradation products, when tested undiluted, showed viability of about 40% for HUVEC cells. However, the viability was over 80% when the solution was diluted to 50% and below. The growth of HUVEC cells is similar to but not identical to that observed with tissue culture polystyrene standard (TCPS). The results from this in vitro study suggested that the PUs in the series degraded primarily due to the SS degradation and the cell viability of the accumulated acidic degradation products showed poor viability to HUVEC cells when tested undiluted, however particles released to the degradation medium showed cell viability over 80%.

  15. High Modulus Biodegradable Polyurethanes for Vascular Stents: Evaluation of Accelerated in vitro Degradation and Cell Viability of Degradation Products

    PubMed Central

    Sgarioto, Melissa; Adhikari, Raju; Gunatillake, Pathiraja A.; Moore, Tim; Patterson, John; Nagel, Marie-Danielle; Malherbe, François

    2015-01-01

    We have recently reported the mechanical properties and hydrolytic degradation behavior of a series of NovoSorb™ biodegradable polyurethanes (PUs) prepared by varying the hard segment (HS) weight percentage from 60 to 100. In this study, the in vitro degradation behavior of these PUs with and without extracellular matrix (ECM) coating was investigated under accelerated hydrolytic degradation (phosphate buffer saline; PBS/70°C) conditions. The mass loss at different time intervals and the effect of aqueous degradation products on the viability and growth of human umbilical vein endothelial cells (HUVEC) were examined. The results showed that PUs with HS 80% and below completely disintegrated leaving no visual polymer residue at 18 weeks and the degradation medium turned acidic due to the accumulation of products from the soft segment (SS) degradation. As expected the PU with the lowest HS was the fastest to degrade. The accumulated degradation products, when tested undiluted, showed viability of about 40% for HUVEC cells. However, the viability was over 80% when the solution was diluted to 50% and below. The growth of HUVEC cells is similar to but not identical to that observed with tissue culture polystyrene standard (TCPS). The results from this in vitro study suggested that the PUs in the series degraded primarily due to the SS degradation and the cell viability of the accumulated acidic degradation products showed poor viability to HUVEC cells when tested undiluted, however particles released to the degradation medium showed cell viability over 80%. PMID:26000274

  16. Correlation between mechanical and chemical degradation after outdoor and accelerated laboratory aging for multilayer photovoltaic backsheets

    NASA Astrophysics Data System (ADS)

    Lin, Chiao-Chi; Lyu, Yadong; Yu, Li-Chieh; Gu, Xiaohong

    2016-09-01

    Channel cracking fragmentation testing and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were utilized to study mechanical and chemical degradation of a multilayered backsheet after outdoor and accelerated laboratory aging. A model sample of commercial PPE backsheet, namely polyethylene terephthalate/polyethylene terephthalate/ethylene vinyl acetate (PET/PET/EVA) was investigated. Outdoor aging was performed in Gaithersburg, Maryland, USA for up to 510 days, and complementary accelerated laboratory aging was conducted on the NIST (National Institute of Standards and Technology) SPHERE (Simulated Photodegradation via High Energy Radiant Exposure). Fracture energy, mode I stress intensity factor and film strength were analyzed using an analytical model based on channel cracking fragmentation testing results. The correlation between mechanical and chemical degradation was discussed for both outdoor and accelerated laboratory aging. The results of this work provide preliminary understanding on failure mechanism of backsheets after weathering, laying the groundwork for linking outdoor and indoor accelerated laboratory testing for multilayer photovoltaic backsheets.

  17. Accelerated life testing of spacecraft subsystems

    NASA Technical Reports Server (NTRS)

    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.

  18. Hycrest crested wheatgrass accelerates the degradation of pentachlorophenol in soil

    NASA Technical Reports Server (NTRS)

    Ferro, A. M.; Sims, R. C.; Bugbee, B.

    1994-01-01

    We investigated the effects of vegetation on the fate of pentachlorophenol (PCP) in soil using a novel high-flow sealed test system. Pentachlorophenol has been widely used as a wood preservative, and this highly toxic biocide contaminates soil and ground water at many sites. Although plants are known to accelerate the rates of degradation of certain soil contaminants, this approach has not been thoroughly investigated for PCP. The fate of [14C]PCP, added to soil at a concentration of 100 mg/kg, was compared in three unplanted and three planted systems. The plant used was Hycrest, a perennial, drought-tolerant cultivar of crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes]. The flow-through test system allowed us to maintain a budget for 14C-label as well as monitor mineralization (breakdown to 14CO2) and volatilization of the test compound in a 155-d trial. In the unplanted systems, an average of 88% of the total radiolabel remained in the soil and leachate and only 6% was mineralized. In the planted system, 33% of the radiolabel remained in the soil plus leachate, 22% was mineralized, and 36% was associated with plant tissue (21% with the root fraction and 15% with shoots). Mineralization rates were 23.1 mg PCP mineralized kg-1 soil in 20 wk in the planted system, and for the unplanted system 6.6 mg PCP kg-1 soil for the same time period. Similar amounts of volatile organic material were generated in the two systems (1.5%). Results indicated that establishing crested wheatgrass on PCP-contaminated surface soils may accelerate the removal of the contaminant.

  19. Hycrest crested wheatgrass accelerates the degradation of pentachlorophenol in soil

    NASA Technical Reports Server (NTRS)

    Ferro, A. M.; Sims, R. C.; Bugbee, B.

    1994-01-01

    We investigated the effects of vegetation on the fate of pentachlorophenol (PCP) in soil using a novel high-flow sealed test system. Pentachlorophenol has been widely used as a wood preservative, and this highly toxic biocide contaminates soil and ground water at many sites. Although plants are known to accelerate the rates of degradation of certain soil contaminants, this approach has not been thoroughly investigated for PCP. The fate of [14C]PCP, added to soil at a concentration of 100 mg/kg, was compared in three unplanted and three planted systems. The plant used was Hycrest, a perennial, drought-tolerant cultivar of crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes]. The flow-through test system allowed us to maintain a budget for 14C-label as well as monitor mineralization (breakdown to 14CO2) and volatilization of the test compound in a 155-d trial. In the unplanted systems, an average of 88% of the total radiolabel remained in the soil and leachate and only 6% was mineralized. In the planted system, 33% of the radiolabel remained in the soil plus leachate, 22% was mineralized, and 36% was associated with plant tissue (21% with the root fraction and 15% with shoots). Mineralization rates were 23.1 mg PCP mineralized kg-1 soil in 20 wk in the planted system, and for the unplanted system 6.6 mg PCP kg-1 soil for the same time period. Similar amounts of volatile organic material were generated in the two systems (1.5%). Results indicated that establishing crested wheatgrass on PCP-contaminated surface soils may accelerate the removal of the contaminant.

  20. Accelerated testing of space mechanisms

    NASA Technical Reports Server (NTRS)

    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.

  1. The Brookhaven National Laboratory Accelerator Test Facility

    SciTech Connect

    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.

  2. The Brookhaven National Laboratory Accelerator Test Facility

    SciTech Connect

    Batchelor, K.

    1992-09-01

    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.

  3. Design considerations and test facilities for accelerated radiation effects testing

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

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

    SciTech Connect

    Kempe, M.

    2014-03-01

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

  5. Polymer degradation and molecular relaxation during accelerated weathering of coatings

    NASA Astrophysics Data System (ADS)

    Fernando, B. Malcolm Dilhan

    2011-12-01

    A model polyester-urethane coating similar to those on USAF aircraft was the focus in this research. It was studied for physical property changes during accelerated weathering. Isothermal aging and natural weathering were utilized as control studies. Coatings subjected to accelerated weathering had an increase in tensile modulus, glass transition temperature and surface stiffness. DSC analysis of these coatings clearly showed evidence for 'physical aging'. This phenomenon was pursued further to find out the impact of macromolecular relaxation on the polymer physical properties. The unique feature of this research is the investigation of kinetics of macromolecular relaxation whilst a polymer undergoes simultaneous degradation. Assessment was done for some material parameters as found in theoretical models. Fictive temperature (Tf), apparent activation energy (Deltah*/R) and non linearity parameter ( x) found in Tool-Narayanswamy-Moyniham (TNM) model were explored. Tf was found to be decreasing with weathering and explained the increasingly aged 'state' of the structure. Deltah*/R was found to be increasing and explains an increased energy barrier to overcome to attain relaxation. DSC peak-shift method was used to characterize x. At early stages there is a stronger non linearity of relaxation (lower x) with a stronger structure dependence and later the relaxation kinetics seems more temperature dependent (higher x). MDSC was done to characterize the non exponentiality parameter (beta) as found in the Kohlrauch-Williams-Watts (KWW) equation. Decreasing beta value with exposure implies an increasingly broad distribution of relaxation times. The Cooperatively Rearranging Regions (CRR) concept of Adams and Gibbs was also examined. Molecular weight (Ma) of the volume (Va) represented by a CRR was compared with Mc, the molecular weight between crosslinks. Nanoindentation was done to explore the coatings' surface mechanical properties. During accelerated weathering the

  6. Uniform and accelerated degradation of pure iron patterned by Pt disc arrays.

    PubMed

    Huang, Tao; Zheng, Yufeng

    2016-04-01

    Pure iron has been confirmed as a promising biodegradable metal. However, the degradation rate of pure iron should be accelerated to meet the clinical requirements. In this work, two different designs of platinum disc arrays, including sizes of Φ20 μm × S5 μm and Φ4 μm × S4 μm, have been coated on the surface of pure iron. Corrosion tests showed the platinum discs formed plenty of galvanic cells with the iron matrix which significantly accelerated the degradation of pure iron. Simultaneously, due to the designability of the shape, size as well as distribution of Pt discs, the degradation rate as well as degradation uniformity of pure iron can be effectively controlled by coating with platinum discs. The cytotoxicity test results unveiled that Pt discs patterned pure iron exhibited almost no toxicity to human umbilical vein endothelial cells, but a significant inhibition on proliferation of vascular smooth muscle cells. In addition, the hemolysis rate of Pt discs patterned pure iron was lower than 1%. Moreover, Pt discs also effectively reduced the number of adhered platelets. All these results indicated that Pt discs patterning is an effective way to accelerate degradation and improve biocompatibility of pure iron.

  7. Uniform and accelerated degradation of pure iron patterned by Pt disc arrays

    PubMed Central

    Huang, Tao; Zheng, Yufeng

    2016-01-01

    Pure iron has been confirmed as a promising biodegradable metal. However, the degradation rate of pure iron should be accelerated to meet the clinical requirements. In this work, two different designs of platinum disc arrays, including sizes of Φ20 μm × S5 μm and Φ4 μm × S4 μm, have been coated on the surface of pure iron. Corrosion tests showed the platinum discs formed plenty of galvanic cells with the iron matrix which significantly accelerated the degradation of pure iron. Simultaneously, due to the designability of the shape, size as well as distribution of Pt discs, the degradation rate as well as degradation uniformity of pure iron can be effectively controlled by coating with platinum discs. The cytotoxicity test results unveiled that Pt discs patterned pure iron exhibited almost no toxicity to human umbilical vein endothelial cells, but a significant inhibition on proliferation of vascular smooth muscle cells. In addition, the hemolysis rate of Pt discs patterned pure iron was lower than 1%. Moreover, Pt discs also effectively reduced the number of adhered platelets. All these results indicated that Pt discs patterning is an effective way to accelerate degradation and improve biocompatibility of pure iron. PMID:27033380

  8. Uniform and accelerated degradation of pure iron patterned by Pt disc arrays

    NASA Astrophysics Data System (ADS)

    Huang, Tao; Zheng, Yufeng

    2016-04-01

    Pure iron has been confirmed as a promising biodegradable metal. However, the degradation rate of pure iron should be accelerated to meet the clinical requirements. In this work, two different designs of platinum disc arrays, including sizes of Φ20 μm × S5 μm and Φ4 μm × S4 μm, have been coated on the surface of pure iron. Corrosion tests showed the platinum discs formed plenty of galvanic cells with the iron matrix which significantly accelerated the degradation of pure iron. Simultaneously, due to the designability of the shape, size as well as distribution of Pt discs, the degradation rate as well as degradation uniformity of pure iron can be effectively controlled by coating with platinum discs. The cytotoxicity test results unveiled that Pt discs patterned pure iron exhibited almost no toxicity to human umbilical vein endothelial cells, but a significant inhibition on proliferation of vascular smooth muscle cells. In addition, the hemolysis rate of Pt discs patterned pure iron was lower than 1%. Moreover, Pt discs also effectively reduced the number of adhered platelets. All these results indicated that Pt discs patterning is an effective way to accelerate degradation and improve biocompatibility of pure iron.

  9. Mechanisms of accelerated degradation in the front cells of PEMFC stacks and some mitigation strategies

    NASA Astrophysics Data System (ADS)

    Li, Pengcheng; Pei, Pucheng; He, Yongling; Yuan, Xing; Chao, Pengxiang; Wang, Xizhong

    2013-11-01

    The accelerated degradation in the front cells of a polymer electrolyte membrane fuel cell(PEMFC) stack seriously reduces the reliability and durability of the whole stack. Most researches only focus on the size and configuration of the gas intake manifold, which may lead to the maldistribution of flow and pressure. In order to find out the mechanisms of the accelerated degradation in the front cells, an extensive program of experimental and simulation work is initiated and the results are reported. It is found that after long-term lifetime tests the accelerated degradation in the front cells occurs in all three fuel cell stacks with different flow-fields under the U-type feed configuration. Compared with the rear cells of the stack, the voltage of the front cells is much lower at the same current densities and the membrane electrode assembly(MEA) has smaller active area, more catalyst particle agglomeration and higher ohmic impedance. For further investigation, a series of three dimensional isothermal numerical models are built to investigate the degradation mechanisms based on the experimental data. The simulation results reveal that the dry working condition of the membrane and the effect of high-speed gas scouring the MEA are the main causes of the accelerated degradation in the front cells of a PEM fuel cell stack under the U-type feed configuration. Several mitigation strategies that would mitigate these phenomena are presented: removing cells that have failed and replacing them with those of the same aging condition as the average of the stack; choosing a Z-type feed pattern instead of a U-type one; putting several air flow-field plates without MEA in the front of the stack; or exchanging the gas inlet and outlet alternately at a certain interval. This paper specifies the causes of the accelerated degradation in the front cells and provides the mitigation strategies.

  10. Dynamic Multivariate Accelerated Corrosion Test Protocol

    DTIC Science & Technology

    2014-10-01

    include the development of a test chamber, modified to include the synergistic effects of UV and ozone and the exposure of bare and coated samples to yield...prediction of performance lifetime based upon a relatively short timeframe accelerated test. 15. SUBJECT TERMS Corrosion, ozone , ultraviolet...modified to include the synergistic effects of UV and ozone and the exposure of bare and coated samples to yield an accelerated corrosion test. This test

  11. Accelerator Test of an Imaging Calorimeter

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  12. Improved Accelerated Stress Tests Based on Fuel Cell Vehicle Data

    SciTech Connect

    Patterson, Timothy; Motupally, Sathya

    2012-06-01

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

  13. RHIC sextant test: Accelerator systems and performance

    SciTech Connect

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

    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.

  14. Testing general relativity on accelerators

    DOE PAGES

    Kalaydzhyan, Tigran

    2015-09-07

    Within the general theory of relativity, the curvature of spacetime is related to the energy and momentum of the present matter and radiation. One of the more specific predictions of general relativity is the deflection of light and particle trajectories in the gravitational field of massive objects. Bending angles for electromagnetic waves and light in particular were measured with a high precision. However, the effect of gravity on relativistic massive particles was never studied experimentally. Here we propose and analyze experiments devoted to that purpose. We demonstrate a high sensitivity of the laser Compton scattering at high energy accelerators tomore » the effects of gravity. The main observable – maximal energy of the scattered photons – would experience a significant shift in the ambient gravitational field even for otherwise negligible violation of the equivalence principle. In conclusion, we confirm predictions of general relativity for ultrarelativistic electrons of energy of tens of GeV at a current level of resolution and expect our work to be a starting point of further high-precision studies on current and future accelerators, such as PETRA, European XFEL and ILC.« less

  15. Investigation of accelerated stress factors and failure/degradation mechanisms in terrestrial solar cells

    NASA Astrophysics Data System (ADS)

    Lathrop, J. W.

    1986-09-01

    This is the final report of a reliability research program to study the response of amorphous silicon colar cells to accelerated temperature testing. The goal of the research was to utilize accelerated testing to identify failure/degradation modes and to relate them to basic physical, chemical, and metallurgical phenomena. Four types of single junction commercial modules were subjected to 140 C testing, both in the dark and under illuminated conditions. The before and after electrical characteristics of individual cells were measured and compared and correlated with physical evidence. A fifth module type could not be tested because of poor adherence of the films to the glass superstrate. A short term effect of stressing was noted which dramatically improved cells with low Voc on one type of construction. All cells eventually showed long term irreversible degradation, but the time to 50% Pm reduction varied by as much as two orders of magnitude depending on construction. No basic difference could be detected between degradation under illuminated or non-illuminated conditions, when cells were either open or short circuited. Comparison with one type of tendem cell and with published results of Japanese cell testing indicated the marked superiority of the tandem cell to all other types. Cells were examined physically by optical, IR, and scanning electron microscopy and by Auger spectroscopy, spectroscopy, secondary ion mass spectroscopy, and energy dispersive x-ray analysis. The long term degradation was felt to be due to localized penetration of aluminum through the amorphous film.

  16. Investigation of accelerated stress factors and failure/degradation mechanisms in terrestrial solar cells

    NASA Technical Reports Server (NTRS)

    Lathrop, J. W.

    1983-01-01

    Results of an ongoing research program into the reliability of terrestrial solar cells are presented. Laboratory accelerated testing procedures are used to identify failure/degradation modes which are then related to basic physical, chemical, and metallurgical phenomena. In the most recent tests, ten different types of production cells, both with and without encapsulation, from eight different manufacturers were subjected to a variety of accelerated tests. Results indicated the presence of a number of hitherto undetected failure mechanisms, including Schottky barrier formation at back contacts and loss of adhesion of grid metallization. The mechanism of Schottky barrier formation is explained by hydrogen, formed by the dissociation of water molecules at the contact surface, diffusing to the metal semiconductor interface. This same mechanism accounts for the surprising increase in sensitivity to accelerated stress conditions that was observed in some cells when encapsulated.

  17. Solid oxide materials research accelerated electrochemical testing

    SciTech Connect

    Windisch, C.; Arey, B.

    1995-08-01

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

  18. A Statistical Perspective on Highly Accelerated Testing

    SciTech Connect

    Thomas, Edward V.

    2015-02-01

    Highly accelerated life testing has been heavily promoted at Sandia (and elsewhere) as a means to rapidly identify product weaknesses caused by flaws in the product's design or manufacturing process. During product development, a small number of units are forced to fail at high stress. The failed units are then examined to determine the root causes of failure. The identification of the root causes of product failures exposed by highly accelerated life testing can instigate changes to the product's design and/or manufacturing process that result in a product with increased reliability. It is widely viewed that this qualitative use of highly accelerated life testing (often associated with the acronym HALT) can be useful. However, highly accelerated life testing has also been proposed as a quantitative means for "demonstrating" the reliability of a product where unreliability is associated with loss of margin via an identified and dominating failure mechanism. It is assumed that the dominant failure mechanism can be accelerated by changing the level of a stress factor that is assumed to be related to the dominant failure mode. In extreme cases, a minimal number of units (often from a pre-production lot) are subjected to a single highly accelerated stress relative to normal use. If no (or, sufficiently few) units fail at this high stress level, some might claim that a certain level of reliability has been demonstrated (relative to normal use conditions). Underlying this claim are assumptions regarding the level of knowledge associated with the relationship between the stress level and the probability of failure. The primary purpose of this document is to discuss (from a statistical perspective) the efficacy of using accelerated life testing protocols (and, in particular, "highly accelerated" protocols) to make quantitative inferences concerning the performance of a product (e.g., reliability) when in fact there is lack-of-knowledge and uncertainty concerning the

  19. Next linear collider test accelerator injector upgrade

    SciTech Connect

    Yeremian, A.D.; Miller, R.H.

    1995-12-31

    The Next Linear Collider Test Accelerator (NLCTA) is being constructed at SLAC to demonstrate multibunch beam loading compensation, suppression of higher order deflecting modes and measure transverse components of the accelerating fields in X-band accelerating structures. Currently a simple injector which provides the average current necessary for the beam loading compensations studies is under construction. An injector upgrade is planned to produce bunch trains similar to that of the NLC with microbunch intensity, separation and energy spread, identical to that of NLC. We discuss the design of the NLCTA injector upgrade.

  20. Focusing on accelerated life testing for cylinders

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

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

  1. The accelerated testing of cements in brines

    SciTech Connect

    Krumhansl, J.L.

    1993-12-31

    Cementitious materials may be employed in settings where they face prolonged exposure to Mg-rich brines. This study evaluated the possibility of using high temperatures to accelerate brine-cement reaction rates. Class-H cement coupons were tested in Mg-K-Na-C1- SO{sub 4} brines to 100{degrees}C. MgC1{sub 2}-NaC1 solutions were also employed in a test sequence that extended to 200{degrees}C. It was found that accelerated testing could be used successfully to evaluate the compatability of cementitious materials with such brines.

  2. Accelerated aging tests of liners for uranium mill tailings disposal

    SciTech Connect

    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.

  3. Optimal sequential Bayesian analysis for degradation tests.

    PubMed

    Rodríguez-Narciso, Silvia; Christen, J Andrés

    2016-07-01

    Degradation tests are especially difficult to conduct for items with high reliability. Test costs, caused mainly by prolonged item duration and item destruction costs, establish the necessity of sequential degradation test designs. We propose a methodology that sequentially selects the optimal observation times to measure the degradation, using a convenient rule that maximizes the inference precision and minimizes test costs. In particular our objective is to estimate a quantile of the time to failure distribution, where the degradation process is modelled as a linear model using Bayesian inference. The proposed sequential analysis is based on an index that measures the expected discrepancy between the estimated quantile and its corresponding prediction, using Monte Carlo methods. The procedure was successfully implemented for simulated and real data.

  4. Accelerated aromatic compounds degradation in aquatic environment by use of interaction between Spirodela polyrrhiza and bacteria in its rhizosphere.

    PubMed

    Toyama, Tadashi; Yu, Ning; Kumada, Hirohide; Sei, Kazunari; Ike, Michihiko; Fujita, Masanori

    2006-04-01

    Accelerated degradation of organic chemicals by aquatic plant-bacterial associations was reported for the first time with elucidation of the role and contribution of aquatic plant and bacteria in its rhizosphere using a fast-growing giant duckweed, Spirodela polyrrhiza. The results clearly showed the accelerated degradation of all the three aromatic compounds (phenol, aniline and 2,4-dichlorophenol [2,4-DCP]) tested by aquatic plant-bacterial associations. In phenol degradation system, phenol-degrading bacteria indigenous to the rhizosphere fraction of S. polyrrhiza mainly contributed, while in aniline degradation system S. polyrrhiza mainly contributed by stimulating aniline-degrading bacteria both in the rhizosphere and balk water fraction. On the other hand in 2,4-DCP degradation system, S. polyrrhiza itself mainly contributed to its removal by uptake and degradation. Thus, the mechanisms for accelerated removal of aromatic compounds were quite different depending on the substrates. S. polyrrhiza showed selective accumulation of phenol-degrading bacteria in its rhizosphere fraction, while aniline- and 2,4-DCP-degrading bacteria were not much accumulated. S. polyrrhiza secreted peroxidase and laccase. However, both of the enzymatic activities increased with the addition of aromatic compounds, degrading ability of S. polyrrhiza itself should be owing to the production of peroxidase rather than laccase because the change of peroxidase activity and concentration of each aromatic compound well concurred. From the results obtained in the present study, it can be concluded that the feasibility of the use of aquatic plant-bacterial associations to accelerate the degradation of organic chemicals especially recalcitrant compounds in aquatic environment was shown.

  5. RHIC Sextant Test - Accelerator Systems and Performance

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

  6. Accelerated dissolution testing for improved quality assurance.

    PubMed

    Quist, Per Ola; Ostling, Göran

    2002-06-15

    In pharmaceutical production of controlled release tablets and capsules, a rapid and automated at-line dissolution test for quality assurance of semi-products is advantageous. For effective control of the production, the analysis should not take more than about an hour, without loss of correlation to the ordinary (USP) dissolution test of the final product. For almost a decade, the ACDRA apparatus (ACcelerated Dissolution Rate Analysis) have been used for this purpose at AstraZeneca Tablet Production Sweden (TPS). In this paper, we give examples on different ways to accelerate the dissolution process. We use the USP dissolution calibrator tablets of salicylic acid (non-disintegrating type) to illustrate the strategy. We investigate the accelerated dissolution of the dissolution calibrator tablets, and show how it can be correlated with the dissolution in the ordinary USP-II equipment. The dissolution process was accelerated by variation of temperature, solvent and stirring. For example, we show that by increasing the temperature to 70 degrees C, changing the solvent to water, and increasing the stirring, it is possible to accelerate the dissolution by a factor of 5, without any loss of correlation to the dissolution process in the ordinary test.

  7. Accelerated metolachlor degradation in soil by zerovalent iron and compost amendments.

    PubMed

    Kim, Sung-Chul; Yang, Jae E; Ok, Yong Sik; Skousen, Jeff; Kim, Dong-Guk; Joo, Jin-Ho

    2010-04-01

    Soil incubation and germination tests were conducted to assess zerovalent iron (ZVI), organic compost, moisture and their combinations on metolachlor degradation in soil. The ZVI alone degraded 91% of metolachlor in soil within 40 days following bi-phasic kinetics. Organic amendment alone facilitated metolachlor degradation in soil up to 60% after 40 days depending on the amendment rate. However, the combination of ZVI with compost amendment at 30 ton ha(-1) and 30% moisture content accelerated metolachlor degradation to 90% after 3 days and 98% after 40 days. The half life (t (1/2)) of metolachlor degradation with ZVI, compost at 30 ton ha(-1), and 30% moisture was about 1 day, which was faster than ZVI treatment alone and 98% faster than controls. Germination and growth of lettuce (Lactuca sativa) and crabgrass (Digitaria sanguinalis L. Scop.) were severely inhibited in unamended metolachlor-contaminated soils but when these soils were amended with ZVI, germination and growth was comparable to controls (metolachlor free soil). Metolachlor degradation was greatest when ZVI, compost and moisture were used together, suggesting that these treatments will maximize in situ remediation of metolachlor-contaminated soils in the field.

  8. Parkin promotes proteasomal degradation of synaptotagmin IV by accelerating polyubiquitination.

    PubMed

    Kabayama, Hiroyuki; Tokushige, Naoko; Takeuchi, Makoto; Kabayama, Miyuki; Fukuda, Mitsunori; Mikoshiba, Katsuhiko

    2017-04-01

    Parkin is an E3 ubiquitin ligase whose mutations cause autosomal recessive juvenile Parkinson's disease (PD). Unlike the human phenotype, parkin knockout (KO) mice show no apparent dopamine neuron degeneration, although they demonstrate reduced expression and activity of striatal mitochondrial proteins believed to be necessary for neuronal survival. Instead, parkin-KO mice show reduced striatal evoked dopamine release, abnormal synaptic plasticity, and non-motor symptoms, all of which appear to mimic the preclinical features of Parkinson's disease. Extensive studies have screened candidate synaptic proteins responsible for reduced evoked dopamine release, and synaptotagmin XI (Syt XI), an isoform of Syt family regulating membrane trafficking, has been identified as a substrate of parkin in humans. However, its expression level is unaltered in the striatum of parkin-KO mice. Thus, the target(s) of parkin and the molecular mechanisms underlying the impaired dopamine release in parkin-KO mice remain unknown. In this study, we focused on Syt IV because of its highly homology to Syt XI, and because they share an evolutionarily conserved lack of Ca(2+)-binding capacity; thus, Syt IV plays an inhibitory role in Ca(2+)-dependent neurotransmitter release in PC12 cells and neurons in various brain regions. We found that a proteasome inhibitor increased Syt IV protein, but not Syt XI protein, in neuron-like, differentiated PC12 cells, and that parkin interacted with and polyubiquitinated Syt IV, thereby accelerating its protein turnover. Parkin overexpression selectively degraded Syt IV protein, but not Syt I protein (indispensable for Ca(2+)-dependent exocytosis), thus enhancing depolarization-dependent exocytosis. Furthermore, in parkin-KO mice, the level of striatal Syt IV protein was increased. Our data indicate a crucial role for parkin in the proteasomal degradation of Syt IV, and provide a potential mechanism of parkin-regulated, evoked neurotransmitter release

  9. The effects of irradiation and EtO-treatment on ultrahigh molecular weight polyethylene acetabular cups following accelerated aging: Degradation of mechanical properties and morphology changes during hip simulator tests

    NASA Astrophysics Data System (ADS)

    Taddei, Paola; Affatato, Saverio; Rocchi, Mirko; Fagnano, Concezio; Viceconti, Marco

    2008-03-01

    The present study was aimed at investigating the effects of the sterilization method and accelerated aging on the wear and morphology of ultrahigh molecular weight polyethylene. In a first test, gamma- and EtO-sterilized acetabular cups were tested in a hip joint simulator for two million cycles. After the test, the cups underwent an accelerated aging treatment (80 °C, 4 weeks in air furnace) and were newly tested for another three million cycles. Wear was evaluated by gravimetric measurements, morphology by micro-Raman spectroscopy. During the first test, the EtO-sterilized cups underwent a significantly higher wear than the gamma-sterilized ones (62 and 30 mg/million cycles, respectively). No significant crystallinity changes were observed. Upon accelerated aging, the crystallinity increase of the gamma-sterilized cups was more pronounced than for the EtO-sterilized cups, due to chain scission and oxygen incorporation. In the second test, the wear rate of EtO-sterilized cups decreased to 38 mg/million cycles, while for gamma-irradiated cups it increased to 84 mg/million cycles. At the same time, the latter cups underwent significant increases in temperature and crystallinity, due to the higher friction. For the EtO-sterilized cups a significant decrease in crystallinity was observed, due to the occurrence of an orthorhombic → monoclinic phase transformation.

  10. Bioelectrochemical system accelerates microbial growth and degradation of filter paper.

    PubMed

    Sasaki, Kengo; Hirano, Shin-Ichi; Morita, Masahiko; Sasaki, Daisuke; Matsumoto, Norio; Ohmura, Naoya; Igarashi, Yasuo

    2011-01-01

    Bioelectrochemical reactors (BERs) with a cathodic working potential of -0.6 or -0.8 V more efficiently degraded cellulosic material, i.e., filter paper (57.4-74.1% in 3 days and 95.9-96.3% in 7 days) than did control reactors without giving exogenous potential (15.4% in 3 days and 64.2% in 7 days). At the same time, resultant conversions to methane and carbon dioxide in cathodic working chamber of BERs by application of electrochemical reduction in 3 days of operation were larger than control reactors. However, cumulative methane production in cathodic BERs was similar to those in control reactors after 7 days of operation. Microscopic observation and 16S rRNA gene analysis showed that microbial growth in the entire consortium was higher after 2 days of operation of cathodic BERs as compared with the control reactors. In addition, the number of methanogenic 16S rRNA gene copies in cathodic BERs was higher than in control reactors. Moreover, archaeal community structures constructed in cathodic BERs consisted of hydrogenotrophic methanogen-related organisms and differed from those in control reactors after 2 days of operation. Specifically, the amount of Methanothermobacter species in cathodic BERs was higher within archaeal communities than in those control reactors after 2 days of operation. Electrochemical reduction may be effective for accelerating microbial growth in the start-up period and thereby increasing microbial treatment of cellulosic waste and methane production.

  11. Investigation of accelerated stress factors and failure/degradation mechanisms in terrestrial solar cells

    NASA Technical Reports Server (NTRS)

    Lathrop, J. W.

    1984-01-01

    Research on the reliability of terrestrial solar cells was performed to identify failure/degradation modes affecting solar cells and to relate these to basic physical, chemical, and metallurgical phenomena. Particular concerns addressed were the reliability attributes of individual single crystalline, polycrystalline, and amorphous thin film silicon cells. Results of subjecting different types of crystalline cells to the Clemson accelerated test schedule are given. Preliminary step stress results on one type of thin film amorphous silicon (a:Si) cell indicated that extraneous degradation modes were introduced above 140 C. Also described is development of measurement procedures which are applicable to the reliability testing of a:Si solar cells as well as an approach to achieving the necessary repeatability of fabricating a simulated a:Si reference cell from crystalline silicon photodiodes.

  12. Low Energy Accelerator Facility Upgrade and test

    SciTech Connect

    Alford, K.; Chemerisov, S.; Gromov, R.; Hafenrichter, L.; Jonah, C. D.; Tafoya, R.; Wesolowski, K.; Brown, D.; Forknall, S.; Gardner, James; Macrillo, Dave; Zulpo, A.

    2015-01-01

    The Low Energy Accelerator Facility (LEAF) contains a low-energy linac with high average beam power, which was designed and built in the late 1960’s primarily for radiation-chemistry experiments. The maximum beam energy in that configuration was 21 MeV. Although, the installation is old, it is still reliable. The accelerator was repurposed for development of accelerator-based technologies for the production of 99Mo with funding provided by the National Nuclear Security Administration’s Office of Material Management and Minimization (M3 ). An extensive scientific program on the production of radioactive isotopes demanded an upgrade of the accelerator to fit the experimental requirements. Several possible LEAF upgrades were proposed to increase the electron beam energy. The final design proposed the replacement of the old accelerating structures with new ones. In 2011-2012, the new structures were manufactured, installed, and tested with the beam energy up to 50 MeV and average beam power up to 20 kW. LEAF now is an attractive installation for performing research into medical isotope production.

  13. Mechanical loading of bovine pericardium accelerates enzymatic degradation.

    PubMed

    Ellsmere, J C; Khanna, R A; Lee, J M

    1999-06-01

    Bioprosthetic heart valves fail as the result of two simultaneous processes: structural deterioration and calcification. Leaflet deterioration and perforation have been correlated with regions of highest stress in the tissue. The failures have long been assumed to be due to simple mechanical fatigue of the collagen fibre architecture; however, we have hypothesized that local stresses-and particularly dynamic stresses-accelerate local proteolysis, leading to tissue failure. This study addresses that hypothesis. Using a novel, custom-built microtensile culture system, strips of bovine pericardium were subjected to static and dynamic loads while being exposed to solutions of microbial collagenase or trypsin (a non-specific proteolytic enzyme). The time to extend to 30% strain (defined here as time to failure) was recorded. After failure, the percentage of collagen solubilized was calculated based on the amount of hydroxyproline present in solution. All data were analyzed by analysis of variance (ANOVA). In collagenase, exposure to static load significantly decreased the time to failure (P < 0.002) due to increased mean rate of collagen solubilization. Importantly, specimens exposed to collagenase and dynamic load failed faster than those exposed to collagenase under the same average static load (P = 0.02). In trypsin, by contrast, static load never led to failure and produced only minimal degradation. Under dynamic load, however, specimens exposed to collagenase, trypsin, and even Tris/CaCl2 buffer solution, all failed. Only samples exposed to Hanks' physiological solution did not fail. Failure of the specimens exposed to trypsin and Tris/CaCl2 suggests that the non-collagenous components and the calcium-dependent proteolytic enzymes present in pericardial tissue may play roles in the pathogenesis of bioprosthetic heart valve degeneration.

  14. Mir Cooperative Solar Array Project Accelerated Life Thermal Cycling Test

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.; Scheiman, David A.

    1996-01-01

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

  15. BNL ACCELERATOR TEST FACILITY CONTROL SYSTEM UPGRADE.

    SciTech Connect

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

    2001-06-18

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

  16. Vacuum system for Advanced Test Accelerator

    SciTech Connect

    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.

  17. Testing a combined vibration and acceleration environment.

    SciTech Connect

    Jepsen, Richard Alan; Romero, Edward F.

    2005-01-01

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

  18. Accelerated test plan for nickel cadmium spacecraft batteries

    NASA Technical Reports Server (NTRS)

    Hennigan, T. J.

    1973-01-01

    An accelerated test matrix is outlined that includes acceptance, baseline and post-cycling tests, chemical and physical analyses, and the data analysis procedures to be used in determining the feasibility of an accelerated test for sealed, nickel cadmium cells.

  19. Beam alignment test for therapy accelerators

    SciTech Connect

    Lutz, W.R.; Larsen, R.D.; Bjarngard, B.D.

    1981-12-01

    Beam spot displacement, collimator asymmetry, and movement of either collimator or gantry rotational axis can cause misalignment of the X ray beam from a therapy accelerator. A test method, sensitive to all the above problems, consists of double-exposing a film, located at the isocenter, for two gantry positions, 180/sup o/ apart. Opposite halves of the field are blocked for each exposure. A lateral shift of one half with respect to the other indicates the presence of one of the problems mentioned above. Additional tests are described, each of which is sensitive to only one of the problems and capable of quantifying the error.

  20. Beam alignment tests for therapy accelerators

    SciTech Connect

    Lutz, W.R.; Larsen, R.D.; Bjarngard, B.E.

    1981-12-01

    Beam spot displacement, collimator asymmetry, and movement of either collimator or gantry rotational axis can cause misalignment of the X ray beam from a therapy accelerator. A test method, sensitive to all the above problems, consists of double-exposing a film, located at the isocenter, for two gantry positions, 180/sup 0/ apart. Opposite halves of the field are blocked for each exposure. A lateral shift of one half with respect to the other indicates the presence of one of the problems mentioned above. Additional tests are described, each of which is sensitive to only one of the problems and capable of quantifying the error.

  1. Accelerated stress testing of amorphous silicon solar cells

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  2. Ultra-accelerated natural sunlight exposure testing

    DOEpatents

    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.

  3. Commissioning of the Ground Test Accelerator RFQ

    SciTech Connect

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

  4. Commissioning of the Ground Test Accelerator RFQ

    SciTech Connect

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

    1992-09-01

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

  5. Stochastic Modeling and Analysis of Multiple Nonlinear Accelerated Degradation Processes through Information Fusion

    PubMed Central

    Sun, Fuqiang; Liu, Le; Li, Xiaoyang; Liao, Haitao

    2016-01-01

    Accelerated degradation testing (ADT) is an efficient technique for evaluating the lifetime of a highly reliable product whose underlying failure process may be traced by the degradation of the product’s performance parameters with time. However, most research on ADT mainly focuses on a single performance parameter. In reality, the performance of a modern product is usually characterized by multiple parameters, and the degradation paths are usually nonlinear. To address such problems, this paper develops a new s-dependent nonlinear ADT model for products with multiple performance parameters using a general Wiener process and copulas. The general Wiener process models the nonlinear ADT data, and the dependency among different degradation measures is analyzed using the copula method. An engineering case study on a tuner’s ADT data is conducted to demonstrate the effectiveness of the proposed method. The results illustrate that the proposed method is quite effective in estimating the lifetime of a product with s-dependent performance parameters. PMID:27509499

  6. Accelerated performance degradation of CIGS solar cell determined by in-situ monitoring

    NASA Astrophysics Data System (ADS)

    Theelen, Mirjam; Barreau, Nicolas; Daume, Felix; Steijvers, Henk; Hans, Vincent; Liakopoulou, Aikaterini; Vroon, Zeger; Zeman, Miro

    2014-10-01

    An `hybrid' degradation setup, in which humidity, temperature and illumination are used in order to accelerate degradation of CIGS, has been developed. This setup consists of a climate chamber, which can vary the temperature and humidity. Furthermore, an area of 80x80 cm2 is illuminated, which allows both the study of light induced behvaior and the in-situ measurement of the IV curve of the cell during the test, so the degradation behavior can be observed in time. The IV output is automatically logged and characteristic parameters like efficiency, currents, voltages, ideality factor and resistance can be extracted. The 40x40 cm2 in the center of the illuminated area was calibrated BAA according to IEC norm 60904-9. Twelve cells or minimodules can be degraded and measured in-situ at the same time. The continuous in-situ IV measurements allowed us to do various studies, including the determination of the temperature dependency and of the impact of light and dark exposure on the performance of CIGS solar cells. Furthermore, the impact of different Na and K concentrations in the CIGS absorber layer on the ininial as well as long term performance of CIGS solar cells was studied.

  7. The cell-in-series method: A technique for accelerated electrode degradation in redox flow batteries

    DOE PAGES

    Pezeshki, Alan M.; Sacci, Robert L.; Veith, Gabriel M.; ...

    2015-11-21

    Here, we demonstrate a novel method to accelerate electrode degradation in redox flow batteries and apply this method to the all-vanadium chemistry. Electrode performance degradation occurred seven times faster than in a typical cycling experiment, enabling rapid evaluation of materials. This method also enables the steady-state study of electrodes. In this manner, it is possible to delineate whether specific operating conditions induce performance degradation; we found that both aggressively charging and discharging result in performance loss. Post-mortem x-ray photoelectron spectroscopy of the degraded electrodes was used to resolve the effects of state of charge (SoC) and current on the electrodemore » surface chemistry. For the electrode material tested in this work, we found evidence that a loss of oxygen content on the negative electrode cannot explain decreased cell performance. Furthermore, the effects of decreased electrode and membrane performance on capacity fade in a typical cycling battery were decoupled from crossover; electrode and membrane performance decay were responsible for a 22% fade in capacity, while crossover caused a 12% fade.« less

  8. The cell-in-series method: A technique for accelerated electrode degradation in redox flow batteries

    SciTech Connect

    Pezeshki, Alan M.; Sacci, Robert L.; Veith, Gabriel M.; Zawodzinski, Thomas A.; Mench, Matthew M.

    2015-11-21

    Here, we demonstrate a novel method to accelerate electrode degradation in redox flow batteries and apply this method to the all-vanadium chemistry. Electrode performance degradation occurred seven times faster than in a typical cycling experiment, enabling rapid evaluation of materials. This method also enables the steady-state study of electrodes. In this manner, it is possible to delineate whether specific operating conditions induce performance degradation; we found that both aggressively charging and discharging result in performance loss. Post-mortem x-ray photoelectron spectroscopy of the degraded electrodes was used to resolve the effects of state of charge (SoC) and current on the electrode surface chemistry. For the electrode material tested in this work, we found evidence that a loss of oxygen content on the negative electrode cannot explain decreased cell performance. Furthermore, the effects of decreased electrode and membrane performance on capacity fade in a typical cycling battery were decoupled from crossover; electrode and membrane performance decay were responsible for a 22% fade in capacity, while crossover caused a 12% fade.

  9. Irradiation imposed degradation of the mechanical and electrical properties of electrical insulation for future accelerator magnets

    SciTech Connect

    Polinski, J.; Chorowski, M.; Bogdan, P.; Strychalski, M.; Rijk, G. de

    2014-01-27

    Future accelerators will make extensive use of superconductors made of Nb{sub 3}Sn, which allows higher magnetic fields than NbTi. However, the wind-and-react technology of Nb{sub 3}Sn superconducting magnet production makes polyimide Kapton® non applicable for the coils' electrical insulation. A Nb{sub 3}Sn technology compatible insulation material should be characterized by high radiation resistivity, good thermal conductivity, and excellent mechanical properties. Candidate materials for the electrical insulation of future accelerator's magnet coils have to be radiation certified with respect to potential degradation of their electrical, thermal, and mechanical properties. This contribution presents procedures and results of tests of the electrical and mechanical properties of DGEBA epoxy + D400 hardener, which is one of the candidates for the electrical insulation of future magnets. Two test sample types have been used to determine the material degradation due to irradiation: a untreated one (unirradiated) and irradiated at 77 K with 11 kGy/min intense, 4MeV energy electrons beam to a total dose of 50 MGy.

  10. Disparity between online and offline tests in accelerated aging tests of LED lamps under electric stress.

    PubMed

    Wang, Yao; Jing, Lei; Ke, Hong-Liang; Hao, Jian; Gao, Qun; Wang, Xiao-Xun; Sun, Qiang; Xu, Zhi-Jun

    2016-09-20

    The accelerated aging tests under electric stress for one type of LED lamp are conducted, and the differences between online and offline tests of the degradation of luminous flux are studied in this paper. The transformation of the two test modes is achieved with an adjustable AC voltage stabilized power source. Experimental results show that the exponential fitting of the luminous flux degradation in online tests possesses a higher fitting degree for most lamps, and the degradation rate of the luminous flux by online tests is always lower than that by offline tests. Bayes estimation and Weibull distribution are used to calculate the failure probabilities under the accelerated voltages, and then the reliability of the lamps under rated voltage of 220 V is estimated by use of the inverse power law model. Results show that the relative error of the lifetime estimation by offline tests increases as the failure probability decreases, and it cannot be neglected when the failure probability is less than 1%. The relative errors of lifetime estimation are 7.9%, 5.8%, 4.2%, and 3.5%, at the failure probabilities of 0.1%, 1%, 5%, and 10%, respectively.

  11. Detecting and Confirming Accelerated Atrazine Degradation in Illinois Soils

    USDA-ARS?s Scientific Manuscript database

    Technical abstract: Enhanced degradation of atrazine has been documented in many parts of the world where the herbicide has been extensively used. Atrazine is widely used in corn in Illinois, but enhanced degradation in the field has not been documented. In this study, the dissipation of atrazine...

  12. Accelerated weathering-induced degradation of poly(lactic acid) fiber studied by near-infrared (NIR) hyperspectral imaging.

    PubMed

    Shinzawa, Hideyuki; Nishida, Masakazu; Tanaka, Toshiyuki; Kanematsu, Wataru

    2012-04-01

    Hydrolysis degradation of a set of drawn poly(lactic acid) (PLA) fibers was induced by an accelerated weathering test, radiating ultraviolet (UV) light under a certain temperature and humidity. The fine features of the transient behavior of the PLA fibers were captured by near-infrared (NIR) hyperspectral imaging. The PLA fibers showed a gradual decrease in mechanical property (e.g., tensile strength), indicating hydrolysis degradation. Thus, the detailed analysis of the spectral variation, in turn, offers useful information on the molecular-level degradation behavior of the drawn PLA fibers. The variation of the spectral intensity as well as band position shift of the crystalline band of PLA was analyzed. The spectral intensity of the crystalline band of PLA showed gradual decrease, suggesting the decrease in molecular weight induced by the hydrolysis degradation. In addition, the crystalline band also exhibited a coinciding shift to the lower wavenumber direction with the weathering test, revealing cleavage-induced crystallization of the PLA samples. Consequently, the hydrolysis degradation induced by the weathering test substantially accelerates predominant degradation of the amorphous structure of the PLA and such variation of the molecular structure, in turn, brings less ductility to the PLA fiber.

  13. The Brookhaven accelerator test facility injection system

    SciTech Connect

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

    1989-01-01

    The Brookhaven Accelerator Test Facility (ATF) consists of a 50-MeV/c electron linac and a high-brightness RF-gun both operating at 2856 MHz. An extremely short (a few picoseconds) electron pulse with low transverse emittance is generated by the RF-gun. In order to preserve both longitudinal and transverse emittances, great care must be taken in transporting the electron beam from the RF-gun to the linac. We describe the injection line, present first- and second-order lattice studies of the injection line, and study nonlinear effects on the emittance. 11 refs., 4 figs., 4 tabs.

  14. Accelerated Leach Test(s) Program: Annual report

    SciTech Connect

    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.

  15. Laboratory Test of Newton's Second Law for Small Accelerations

    SciTech Connect

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

    2007-04-13

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

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

    PubMed

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

    2007-04-13

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

  17. Laboratory Test of Newton's Second Law for Small Accelerations

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    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 5 x 10-14 m/s^2.

  18. Laboratory Test of Newton's Second Law for Small Accelerations

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

    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 5×10-14m/s2.

  19. Instrumentation for accelerated life tests of concentrator solar cells.

    PubMed

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

    2011-02-01

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

  20. Instrumentation for accelerated life tests of concentrator solar cells

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

  1. Determining anaerobic degradation kinetics from batch tests.

    PubMed

    Moreda, Iván López

    2016-01-01

    Data obtained from a biomethane potential (BMP) test were used in order to obtain the parameters of a kinetic model of solid wastes anaerobic degradation. The proposed model considers a hydrolysis step with a first order kinetic, a Monod kinetic for the soluble organic substrate degradation and a first order decay of microorganisms. The instantaneous release of methane was assumed. The parameters of the model are determined following a direct search optimization procedure. A 'multiple-shooting' technique was used as a first step of the optimization process. The confidence interval of the parameters was determined by using Monte Carlo simulations. Also, the distribution functions of the parameters were determined. Only the hydrolysis first order constant shows a normal distribution.

  2. Hurricane Isabel gives accelerators a severe test

    SciTech Connect

    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

  3. Cerium migration during PEM fuel cell accelerated stress testing

    DOE PAGES

    Baker, Andrew M.; Mukundan, Rangachary; Borup, Rodney L.; ...

    2016-01-01

    Cerium is a radical scavenger which improves polymer electrolyte membrane (PEM) fuel cell durability. During operation, however, cerium rapidly migrates in the PEM and into the catalyst layers (CLs). In this work, membrane electrode assemblies (MEAs) were subjected to accelerated stress tests (ASTs) under different humidity conditions. Cerium migration was characterized in the MEAs after ASTs using X-ray fluorescence. During fully humidified operation, water flux from cell inlet to outlet generated in-plane cerium gradients. Conversely, cerium profiles were flat during low humidity operation, where in-plane water flux was negligible, however, migration from the PEM into the CLs was enhanced. Humiditymore » cycling resulted in both in-plane cerium gradients due to water flux during the hydration component of the cycle, and significant migration into the CLs. Fluoride and cerium emissions into effluent cell waters were measured during ASTs and correlated, which signifies that ionomer degradation products serve as possible counter-ions for cerium emissions. Fluoride emission rates were also correlated to final PEM cerium contents, which indicates that PEM degradation and cerium migration are coupled. Lastly, it is proposed that cerium migrates from the PEM due to humidification conditions and degradation, and is subsequently stabilized in the CLs by carbon catalyst supports.« less

  4. Cerium migration during PEM fuel cell accelerated stress testing

    SciTech Connect

    Baker, Andrew M.; Mukundan, Rangachary; Borup, Rodney L.; Spernjak, Dusan; Judge, Elizabeth J.; Advani, Suresh G.; Prasad, Ajay K.

    2016-01-01

    Cerium is a radical scavenger which improves polymer electrolyte membrane (PEM) fuel cell durability. During operation, however, cerium rapidly migrates in the PEM and into the catalyst layers (CLs). In this work, membrane electrode assemblies (MEAs) were subjected to accelerated stress tests (ASTs) under different humidity conditions. Cerium migration was characterized in the MEAs after ASTs using X-ray fluorescence. During fully humidified operation, water flux from cell inlet to outlet generated in-plane cerium gradients. Conversely, cerium profiles were flat during low humidity operation, where in-plane water flux was negligible, however, migration from the PEM into the CLs was enhanced. Humidity cycling resulted in both in-plane cerium gradients due to water flux during the hydration component of the cycle, and significant migration into the CLs. Fluoride and cerium emissions into effluent cell waters were measured during ASTs and correlated, which signifies that ionomer degradation products serve as possible counter-ions for cerium emissions. Fluoride emission rates were also correlated to final PEM cerium contents, which indicates that PEM degradation and cerium migration are coupled. Lastly, it is proposed that cerium migrates from the PEM due to humidification conditions and degradation, and is subsequently stabilized in the CLs by carbon catalyst supports.

  5. Error-Induced Beam Degradation in Fermilab's Accelerators

    SciTech Connect

    Yoon, Sung-Young Phil

    2008-01-01

    In Part I, three independent models of Fermilab's Booster synchrotron are presented. All three models are constructed to investigate and explore the effects of unavoidable machine errors on a proton beam under the influence of space-charge effects. The first is a stochastic noise model. Electric current fluctuations arising from power supplies are ubiquitous and unavoidable and are a source of instabilities in accelerators of all types. A new noise module for generating the Ornstein-Uhlenbeck (O-U) stochastic noise is first created and incorporated into the existing Object-oriented Ring Beam Injection and Tracking (ORBIT-FNAL) package. After being convinced with a preliminary model that the noise, particularly non-white noise, does matter to beam quality, we proceeded to measure directly current ripples and common-mode voltages from all four Gradient Magnet Power Supplies (GMPS). Then, the current signals are Fourier-analyzed. Based upon the power spectra of current signals, we tune up the Ornstein-Uhlnbeck noise model. As a result, we are able to closely match the frequency spectra between current measurements and the modeled O-U stochastic noise. The stochastic noise modeled upon measurements is applied to the Booster beam in the presence of the full space-charge effects. This noise model, accompanied by a suite of beam diagnostic calculations, manifests that the stochastic noise, impinging upon the beam and coupled to the space-charge effects, can substantially enhance the beam degradation process throughout the injection period. The second model is a magnet misalignment model. It is the first time to utilize the latest beamline survey data for building a magnet-by-magnet misalignment model. Given as-found survey fiducial coordinates, we calculate all types of magnet alignment errors (station error, pitch, yaw, roll, twists, etc.) are implemented in the model. We then follow up with statistical analysis to understand how each type of alignment errors are

  6. Error-induced beam degradation in Fermilab's accelerators

    NASA Astrophysics Data System (ADS)

    Yong, Sung-Yong Phil

    In Part I, three independent models of Fermilab's Booster synchrotron are presented. All three models are constructed to investigate and to explore the effects of unavoidable machine errors on a proton beam under the influence of space-charge effects. The first is a stochastic noise model. Electric current fluctuations arising from power supplies are ubiquitous and unavoidable and are a source of instabilities in accelerators of all types. A new noise module for generating the Ornstein-Uhlenbeck (O-U) stochastic noise is first created and incorporated into the existing Object-oriented Ring Beam Injection and Tracking (ORBIT-FNAL) package. After being convinced that the noise does matter to a beam with a preliminary model, we proceed to measure directly current ripples and common-mode voltages from all four Gradient Magnet Power Supplies (GMPS). Then, the current signals are Fourier-analyzed. Based upon the power spectra of current signals, we tune up the Ornstein-Uhlnbeck noise model. As a result, we are able to closely match the frequency spectra between current measurements and the modeled O-U stochastic noise. The stochastic noise modeled upon measurements is applied to the Booster beam in the presence of the full space-charge effects. This noise model, accompanied by a suite of beam diagnostic calculations, manifests that the stochastic noise, impinging upon the beam and coupled to the space-charge effects, can substantially enhance the beam degradation process throughout the injection period. The second model is a magnet misalignment model. It is the first time to utilize the latest beamline survey data for building a magnet-by-magnet misalignment model. Given as-found survey fiducial coordinates, we calculate all types of magnet alignment errors (station error, pitch, yaw, roll, twists, etc.) are implemented in the model. We then follow up with statistical analysis to understand how each type of alignment errors are currently distributed around the Booster

  7. Relatively uniform and accelerated degradation of pure iron coated with micro-patterned Au disc arrays.

    PubMed

    Cheng, J; Huang, T; Zheng, Y F

    2015-03-01

    Pure iron has been proven to be a potential biodegradable metal, but its degradation rate was too slow. To accelerate its biodegradation, micro-patterned Au disc films were deposited on the surface of pure iron by vacuum sputtering. The influence of Au disc films on the degradation of pure iron matrix in vitro was investigated in the present study. Electrochemical measurement results indicated that the corrosion current density of pure iron coated with micro-patterned Au disc films in Hank's solution was 4 times larger than that of the uncoated one, while the difference between the influences of micro-patterned Au discs with different diameters on the corrosion rate of pure iron was insignificant. Immersion test indicated that the corrosion depth for pure iron coated with Au disc films was about three times as that of bare pure iron. Both electrochemical test and immersion test revealed that the corrosion of pure iron matrix coated with Au disc array became more uniform.

  8. Accelerated Strength Testing of Thermoplastic Composites

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Mühlig, Christian; Bublitz, Simon

    2013-11-01

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

  10. Stripline kicker for integrable optics test accelerator

    SciTech Connect

    Antipov, Sergey A.; Didenko, Alexander; Lebedev, Valeri; Valishev, Alexander

    2016-06-30

    We present a design of a stripline kicker for Integrable Optics Test Accelerator (IOTA). For its experimental program IOTA needs two full-aperture kickers, capable to create an arbitrary controllable kick in 2D. For that reason their strengths are variable in a wide range of amplitudes up to 16 mrad, and the pulse length 100 ns is less than a revolution period for electrons. In addition, the kicker should have a physical aperture of 40 mm for a proposed operation with proton beam, and an outer size of 70 mm to fit inside existing quadrupole magnets to save space in the ring. Computer simulations using CST Microwave Studio show high field uniformity and wave impedance close to 50 {\\Omega}.

  11. Testing Planck-scale gravity with accelerators.

    PubMed

    Gharibyan, Vahagn

    2012-10-05

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

  12. Testing Planck-Scale Gravity with Accelerators

    NASA Astrophysics Data System (ADS)

    Gharibyan, Vahagn

    2012-10-01

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

  13. Planck Scale Gravity Test with Accelerators

    NASA Astrophysics Data System (ADS)

    Gharibyan, V.

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

    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.

  15. Advanced beamline design for Fermilab's Advanced Superconducting Test Accelerator

    NASA Astrophysics Data System (ADS)

    Prokop, Christopher R.

    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.

  16. Advanced Beamline Design for Fermilab's Advanced Superconducting Test Accelerator

    SciTech Connect

    Prokop, Christopher

    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.

  17. Accelerated Durability Testing of Electrochromic Windows

    SciTech Connect

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

    1998-12-29

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

  18. Accelerated Degradation Due to Weakened Adhesion from Li-TFSI Additives in Perovskite Solar Cells.

    PubMed

    Lee, Inhwa; Yun, Jae Hoon; Son, Hae Jung; Kim, Taek-Soo

    2017-03-01

    Reliable integration of organometallic halide perovskite in photovoltaic devices is critically limited by its low stability in humid environments. Furthermore, additives to increase the mobility in the hole transport material (HTM) have deliquescence and hygroscopic properties, which attract water molecules and result in accelerated degradation of the perovskite devices. In this study, a double cantilever beam (DCB) test is used to investigate the effects of additives in the HTM layer on the perovskite layer through neatly delaminating the interface between the perovskite and HTM layers. Using the DCB test, the bottom surface of the HTM layers is directly observed, and it is found that the additives are accumulated at the bottom along the thickness (i.e., through-plane direction) of the films. It is also found that the additives significantly decrease the adhesion at the interface between the perovskite and HTM layers by more than 60% through hardening the HTM films. Finally, the adhesion-based degradation mechanism of perovskite devices according to the existence of additives is proposed for humid environments.

  19. VMAT testing for an Elekta accelerator.

    PubMed

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

    2012-03-08

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

  20. Nylon 6.6 accelerated aging studies : thermal-oxidative degradation and its interaction with hydrolysis.

    SciTech Connect

    Bernstein, Robert; Derzon, Dora Kay; Gillen, Kenneth T.

    2004-06-01

    Accelerated aging of Nylon 6.6 fibers used in parachutes has been conducted by following the tensile strength loss under both thermal-oxidative and 100% relative humidity conditions. Thermal-oxidative studies (air circulating ovens) were performed for time periods of weeks to years at temperatures ranging from 37 C to 138 C. Accelerated aging humidity experiments (100% RH) were performed under both an argon atmosphere to examine the 'pure' hydrolysis pathway, and under an oxygen atmosphere (oxygen partial pressure close to that occurring in air) to mimic true aging conditions. As expected the results indicated that degradation caused by humidity is much more important than thermal-oxidative degradation. Surprisingly when both oxygen and humidity were present the rate of degradation was dramatically enhanced relative to humidity aging in the absence of oxygen. This significant and previously unknown phenomena underscores the importance of careful accelerated aging that truly mimics real world storage conditions.

  1. Preliminary tests of the electrostatic plasma accelerator

    NASA Technical Reports Server (NTRS)

    Aston, G.; Acker, T.

    1990-01-01

    This report describes the results of a program to verify an electrostatic plasma acceleration concept and to identify those parameters most important in optimizing an Electrostatic Plasma Accelerator (EPA) thruster based upon this thrust mechanism. Preliminary performance measurements of thrust, specific impulse and efficiency were obtained using a unique plasma exhaust momentum probe. Reliable EPA thruster operation was achieved using one power supply.

  2. Laboratory Test of Newton's Second Law for Small Accelerations

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

    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 5 x 10-14 m/s^2. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.OSS07.P1.15

  3. 46 CFR 160.072-5 - Accelerated weathering test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Accelerated weathering test. 160.072-5 Section 160.072-5... weathering test. (a) Condition the flag, folded to 1/16th its size or as packaged, whichever is smaller, by... less than 24 hours. (d) The flag fails the accelerated weathering test if (1) After conditioning, the...

  4. 46 CFR 160.072-5 - Accelerated weathering test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Accelerated weathering test. 160.072-5 Section 160.072-5... weathering test. (a) Condition the flag, folded to 1/16th its size or as packaged, whichever is smaller, by... less than 24 hours. (d) The flag fails the accelerated weathering test if (1) After conditioning, the...

  5. 46 CFR 160.072-5 - Accelerated weathering test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Accelerated weathering test. 160.072-5 Section 160.072-5... weathering test. (a) Condition the flag, folded to 1/16th its size or as packaged, whichever is smaller, by... less than 24 hours. (d) The flag fails the accelerated weathering test if (1) After conditioning, the...

  6. 46 CFR 160.072-5 - Accelerated weathering test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Accelerated weathering test. 160.072-5 Section 160.072-5... weathering test. (a) Condition the flag, folded to 1/16th its size or as packaged, whichever is smaller, by... less than 24 hours. (d) The flag fails the accelerated weathering test if (1) After conditioning, the...

  7. 46 CFR 160.072-5 - Accelerated weathering test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Accelerated weathering test. 160.072-5 Section 160.072-5... weathering test. (a) Condition the flag, folded to 1/16th its size or as packaged, whichever is smaller, by... less than 24 hours. (d) The flag fails the accelerated weathering test if (1) After conditioning, the...

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Microbial changes linked to the accelerated degradation of the herbicide atrazine in a range of temperate soils.

    PubMed

    Yale, R L; Sapp, M; Sinclair, C J; Moir, J W B

    2017-03-01

    Accelerated degradation is the increased breakdown of a pesticide upon its repeated application, which has consequences for the environmental fate of pesticides. The herbicide atrazine was repeatedly applied to soils previously untreated with s-triazines for >5 years. A single application of atrazine, at an agriculturally relevant concentration, was sufficient to induce its rapid dissipation. Soils, with a range of physico-chemical properties and agricultural histories, showed similar degradation kinetics, with the half-life of atrazine decreasing from an average of 25 days after the first application to <2 days after the second. A mathematical model was developed to fit the atrazine-degrading kinetics, which incorporated the exponential growth of atrazine-degrading organisms. Despite the similar rates of degradation, the repertoire of atrazine-degrading genes varied between soils. Only a small portion of the bacterial community had the capacity for atrazine degradation. Overall, the microbial community was not significantly affected by atrazine treatment. One soil, characterised by low pH, did not exhibit accelerated degradation, and atrazine-degrading genes were not detected. Neutralisation of this soil restored accelerated degradation and the atrazine-degrading genes became detectable. This illustrates the potential for accelerated degradation to manifest when conditions become favourable. Additionally, the occurrence of accelerated degradation under agriculturally relevant concentrations supports the consideration of the phenomena in environmental risk assessments.

  10. AREAL test facility for advanced accelerator and radiation source concepts

    NASA Astrophysics Data System (ADS)

    Tsakanov, V. M.; Amatuni, G. A.; Amirkhanyan, Z. G.; Aslyan, L. V.; Avagyan, V. Sh.; Danielyan, V. A.; Davtyan, H. D.; Dekhtiarov, V. S.; Gevorgyan, K. L.; Ghazaryan, N. G.; Grigoryan, B. A.; Grigoryan, A. H.; Hakobyan, L. S.; Haroutiunian, S. G.; Ivanyan, M. I.; Khachatryan, V. G.; Laziev, E. M.; Manukyan, P. S.; Margaryan, I. N.; Markosyan, T. M.; Martirosyan, N. V.; Mehrabyan, Sh. A.; Mkrtchyan, T. H.; Muradyan, L. Kh.; Nikogosyan, G. H.; Petrosyan, V. H.; Sahakyan, V. V.; Sargsyan, A. A.; Simonyan, A. S.; Toneyan, H. A.; Tsakanian, A. V.; Vardanyan, T. L.; Vardanyan, A. S.; Yeremyan, A. S.; Zakaryan, S. V.; Zanyan, G. S.

    2016-09-01

    Advanced Research Electron Accelerator Laboratory (AREAL) is a 50 MeV electron linear accelerator project with a laser driven RF gun being constructed at the CANDLE Synchrotron Research Institute. In addition to applications in life and materials sciences, the project aims as a test facility for advanced accelerator and radiation source concepts. In this paper, the AREAL RF photoinjector performance, the facility design considerations and its highlights in the fields of free electron laser, the study of new high frequency accelerating structures, the beam microbunching and wakefield acceleration concepts are presented.

  11. Cross-correlation of backsheet degradation between real-world exposed modules and accelerated exposures of backsheet materials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Bruckman, Laura S.; French, Roger H.; Wang, Yu; Kempe, Michael D.; Lefebvre, Amy A.; Gu, Xiaohong; Ji, Liang; Wan, Kai-Tak; Flueckiger, Christopher

    2016-09-01

    heets are a key polymeric component of a PV module and understanding its degradation is necessary to be able to predict the lifetime of PV modules. We are developing a backsheet predictive tests and a model based on point- in-time data from analytical techniques and datastreams that are applicable to both outdoor and indoor PV module backsheet studies and are supplemented with meteorology data, climatic and brand/model, and other accessible information. The predictive tests and models will specify indoor and outdoor exposure and evaluation data acquisition criteria, variable selection, and temporal duration and variation so as to be able to predict backsheet performance in various climatic zones. This backsheet performance prediction is based on defined backsheet failures in the field, and is quantified by tracking backsheet degradation in the field so as to determine degradation rates. The backsheet lifetime performance predictive tests and models, will be developed using a Stressor / Mechanism / Response framework in which all data are categorized as stressor, mechanism and performance (response) variables and are represented as discrete points-in-time datasets. We will develop and validate these accelerated indoor exposures and evaluations and models and cross-correlate the outdoor and accelerated indoor exposures and evaluations. The evaluation techniques include nondestructive spectroscopy and microscopy techniques and destructive techniques and will provide data in predefined variables, which are used in the predictive modeling.

  12. Accelerated life testing effects on CMOS microcircuit characteristics

    NASA Technical Reports Server (NTRS)

    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.

  13. Terrestrial Photovoltaic Module Accelerated Test-To-Failure Protocol

    SciTech Connect

    Osterwald, C. R.

    2008-03-01

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

  14. Acceleration of potential-induced degradation by salt-mist preconditioning in crystalline silicon photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Suzuki, Soh; Nishiyama, Naoki; Yoshino, Seiji; Ujiro, Takumi; Watanabe, Shin; Doi, Takuya; Masuda, Atsushi; Tanahashi, Tadanori

    2015-08-01

    We examined the sequential effects of salt-mist stress followed by high-system-voltage stress on the power loss of crystalline silicon photovoltaic (PV) modules to determine whether a crucial failure as potential-induced degradation (PID) is accelerated by material-property changes caused by the long-term effects of a less harmful stress such as salt-mist spraying. Degradation profiles confirmed in this study show that PID is accelerated by certain types of salt-mist preconditioning. For the acceleration of PID, the contribution of sodium ions liberated from the front glass of the PV module seems to be excluded. Therefore, we consider that the sodium ions penetrating into the PV modules from the ambient environment may also cause degradation according to the proposed mechanisms of PID, as the sodium ions existing in the front glass cause PID. Furthermore, this type of degradation may indicate the wear-out phenomenon after a long-term exposure in the field (especially near the coast).

  15. Accelerated Test Method for Corrosion Protective Coatings Project

    NASA Technical Reports Server (NTRS)

    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.

  16. Test of F=ma for small accelerations

    NASA Astrophysics Data System (ADS)

    Schlamminger, Stephan; Spitzer, Chris; Choi, Ki-Young; Gundlach, Jens; Woodahl, Brian; Coy, Jennifer; Fischbach, Ephraim

    2007-04-01

    We have used a torsion balance to test Newton's second law in the limit of small forces and accelerations. We were able to verify the proportionality between force and acceleration down to accelerations of 5 x10-14; m/s^2. This is approximately three orders of magnitude lower than a previous measurement and provides a stringent constraint on theories involving a modification of Newtonian dynamics to explain the flatness of galactic rotation curves.

  17. Testing general relativity with laser accelerated electron beams

    SciTech Connect

    Gergely, L. A.; Harko, T.

    2012-07-09

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

  18. Timescale Correlation between Marine Atmospheric Exposure and Accelerated Corrosion Testing

    NASA Technical Reports Server (NTRS)

    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.

  19. The Accelerator Test Facility at Brookhaven: Main capabilities

    NASA Astrophysics Data System (ADS)

    Yakimenko, Vitaly

    2004-12-01

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

  20. Miniature penetrator (MinPen) acceleration recorder development test

    SciTech Connect

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

    1998-08-01

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

  1. Acceleration of fatigue tests for built-up titanium components

    NASA Technical Reports Server (NTRS)

    Watanabe, R. T.

    1976-01-01

    A study was made of the feasibility of a room-temperature scheme of accelerating fatigue tests for Mach 3 advanced supersonic transport aircraft. The test scheme used equivalent room-temperature cycles calculated for supersonic flight conditions. Verification tests were conducted using specimens representing titanium wing lower surface structure. Test-acceleration parameters were developed for the test with an auxiliary test set. Five specimens were tested with a flight-by-flight load and temperature spectrum to simulate typical Mach 3 operation. Two additional sets of five specimens were tested at room temperature to evaluate the test-acceleration scheme. The fatigue behavior of the specimens generally correlated well with the proposed correction method.

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  3. Performance degradation studies on an poly 2,5-benzimidazole high-temperature proton exchange membrane fuel cell using an accelerated degradation technique

    NASA Astrophysics Data System (ADS)

    Jung, Guo-Bin; Chen, Hsin-Hung; Yan, Wei-Mon

    2014-02-01

    In this work, the performance degradation of a poly 2,5-benzimidazole (ABPBI) based high-temperature proton exchange membrane fuel cell (HT-PEMFC) was examined using an accelerated degradation technique (ADT). Experiments using an ADT with 30 min intervals were performed by applying 1.5 V to a membrane electrode assembly (MEA) with hydrogen and nitrogen feeding to the anode and cathode, respectively, to simulate the high voltage generated during fuel cell shutdown and restart. The characterization of the MEAs was performed using in-situ and ex-situ electrochemical methods, such as polarization curves, AC impedance, and cyclic voltammetry (CV), and TEM imaging before and after the ADT experiments. The measured results demonstrated that the ADT testing could be used to dramatically reduce the duration of the degradation. The current output at 0.4 V decreased by 48% after performing ADT testing for 30 min. From the AC impedance, CV and RTGA measurements, the decline in cell performance was found to be primarily due to corrosion and thinning of the catalyst layer (or carbon support) during the first 30 min, leading to the dissolution and agglomeration of the platinum catalyst.

  4. Advanced Test Accelerator (ATA) pulse power technology development

    SciTech Connect

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

    1981-03-09

    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.

  5. Acceleration of the herbicide isoproturon degradation in wheat by glycosyltransferases and salicylic acid.

    PubMed

    Lu, Yi Chen; Zhang, Shuang; Yang, Hong

    2015-01-01

    Isoproturon (IPU) is a herbicide widely used to prevent weeds in cereal production. Due to its extensive use in agriculture, residues of IPU are often detected in soils and crops. Overload of IPU to crops is associated with human health risks. Hence, there is an urgent need to develop an approach to mitigate its accumulation in crops. In this study, the IPU residues and its degradation products in wheat were characterized using ultra performance liquid chromatography-time of fight tandem-mass spectrometer/mass spectrometer (UPLC-TOF-MS/MS). Most detected IPU-derivatives were sugar-conjugated. Degradation and glycosylation of IPU-derivatives could be enhanced by applying salicylic acid (SA). While more sugar-conjugated IPU-derivatives were identified in wheat with SA application, lower levels of IPU were detected, indicating that SA is able to accelerate intracellular IPU catabolism. All structures of IPU-derivatives and sugar-conjugated products were characterized. Comparative data were provided with specific activities and gene expression of certain glucosyltransferases. A pathway with IPU degradation and glucosylation was discussed. Our work indicates that SA-accelerated degradation is practically useful for wheat crops growing in IPU-contaminated soils because such crops with SA application can potentially lower or minimize IPU accumulation in levels below the threshold for adverse effects.

  6. Cosmological consistency tests of gravity theory and cosmic acceleration

    NASA Astrophysics Data System (ADS)

    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.

  7. Test particle acceleration in turbulent reconnecting magnetic fields

    NASA Technical Reports Server (NTRS)

    Ambrosiano, John; Matthaeus, William H.; Goldstein, Melvyn L.; Plante, Daniel

    1988-01-01

    The effect of turbulence on particle acceleration in a MHD field was investigated by computing test particle trajectories in turbulent MHD reconnecting fields, including reconnection simulations at different magnetic Reynolds numbers. The dynamics of individual particles were investigated making it possible to examine the acceleration mechanism in great detail. It was found that turbulence influences the acceleration in two ways. It enhances the reconnection electric field while producing a stochastic electric field that gives rise to momentum diffusion; and it produces magnetic 'bubbles' and other irregularities that can temporarily trap test particles in the strong reconnection electric field for times comparable to the magnetofluid characteristic time.

  8. Test particle acceleration in turbulent reconnecting magnetic fields

    NASA Technical Reports Server (NTRS)

    Ambrosiano, John; Matthaeus, William H.; Goldstein, Melvyn L.; Plante, Daniel

    1988-01-01

    The effect of turbulence on particle acceleration in a MHD field was investigated by computing test particle trajectories in turbulent MHD reconnecting fields, including reconnection simulations at different magnetic Reynolds numbers. The dynamics of individual particles were investigated making it possible to examine the acceleration mechanism in great detail. It was found that turbulence influences the acceleration in two ways. It enhances the reconnection electric field while producing a stochastic electric field that gives rise to momentum diffusion; and it produces magnetic 'bubbles' and other irregularities that can temporarily trap test particles in the strong reconnection electric field for times comparable to the magnetofluid characteristic time.

  9. High gradient tests of metallic mm-wave accelerating structures

    NASA Astrophysics Data System (ADS)

    Dal Forno, Massimo; Dolgashev, Valery; Bowden, Gordon; Clarke, Christine; Hogan, Mark; McCormick, Doug; Novokhatski, Alexander; O'Shea, Brendan; Spataro, Bruno; Weathersby, Stephen; Tantawi, Sami G.

    2017-08-01

    This paper explores the physics of vacuum rf breakdowns in high gradient mm-wave accelerating structures. We performed a series of experiments with 100 GHz and 200 GHz metallic accelerating structures, at the Facility for Advanced Accelerator Experimental Tests (FACET) at the SLAC National Accelerator Laboratory. This paper presents the experimental results of rf tests of 100 GHz travelling-wave accelerating structures, made of hard copper-silver alloy. The results are compared with pure hard copper structures. The rf fields were excited by the FACET ultra-relativistic electron beam. The accelerating structures have open geometries, 10 cm long, composed of two halves separated by a variable gap. The rf frequency of the fundamental accelerating mode depends on the gap size and can be changed from 90 GHz to 140 GHz. The measured frequency and pulse length are consistent with our simulations. When the beam travels off-axis, a deflecting field is induced in addition to the decelerating longitudinal field. We measured the deflecting forces by observing the displacement of the electron bunch and used this measurement to verify the expected accelerating gradient. We present the first quantitative measurement of rf breakdown rates in 100 GHz copper-silver accelerating structure, which was 10-3 per pulse, with peak electric field of 0.42 GV/m, an accelerating gradient of 127 MV/m, at a pulse length of 2.3 ns. The goal of our studies is to understand the physics of gradient limitations in order to increase the energy reach of future accelerators.

  10. High gradient tests of metallic mm-wave accelerating structures

    DOE PAGES

    Dal Forno, Massimo; Dolgashev, Valery; Bowden, Gordon; ...

    2017-05-10

    This study explores the physics of vacuum rf breakdowns in high gradient mm-wave accelerating structures. We performed a series of experiments with 100 GHz and 200 GHz metallic accelerating structures, at the Facility for Advanced Accelerator Experimental Tests (FACET) at the SLAC National Accelerator Laboratory. This paper presents the experimental results of rf tests of 100 GHz travelling-wave accelerating structures, made of hard copper-silver alloy. The results are compared with pure hard copper structures. The rf fields were excited by the FACET ultra-relativistic electron beam. The accelerating structures have open geometries, 10 cm long, composed of two halves separated bymore » a variable gap. The rf frequency of the fundamental accelerating mode depends on the gap size and can be changed from 90 GHz to 140 GHz. The measured frequency and pulse length are consistent with our simulations. When the beam travels off-axis, a deflecting field is induced in addition to the decelerating longitudinal field. We measured the deflecting forces by observing the displacement of the electron bunch and used this measurement to verify the expected accelerating gradient. We present the first quantitative measurement of rf breakdown rates in 100 GHz copper-silver accelerating structure, which was 10–3 per pulse, with peak electric field of 0.42 GV/m, an accelerating gradient of 127 MV/m, at a pulse length of 2.3 ns. The goal of our studies is to understand the physics of gradient limitations in order to increase the energy reach of future accelerators.« less

  11. Accelerated cycle-life testing of small sealed lead/acid batteries

    NASA Astrophysics Data System (ADS)

    Kim, I.; Oh, S. H.; Kang, H. Y.

    An attempt has been made to devise methods for reducing the cycle-testing time of long-life sealed lead/acid batteries. In order for the accelerated test results to equate to the actual field operations, it is assumed that the failure modes under both normal and accelerated conditions must be the same. As a first step in the search for a reliable accelerated test, observations of the battery ageing process have been made under different daily duty cycles, viz., 1 (normal), 8 and 16 cycles/day at ambient temperature and 80% depth-of-discharge. It has been found that the main cause of failure is different for a given duty cycle. This complicates the task of applying accelerated test results to field operations. For the 8 cycles/day schedule, the main cause of failure is degradation of the positive active material. Positive grid corrosion is the main factor in the 16 cycles/day case. Under normal conditions, both grid corrosion and PbO 2 degradation appear to be equally significant.

  12. Accelerator Tests of the KLEM Prototypes

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  13. Accelerated Reliability Testing Utilizing Design of Experiments

    DTIC Science & Technology

    1993-12-01

    hat to Measure ............................... 23 b. Identify Stresses ................................ 24 c . Stress Levels...36 c . Test Time ................................... 48 d. Trade Off Analysis .............................. 56 3. A nalysis...79 2. Exam ple 2 . ..................................... 92 3. Exam ple 3 . .................................... 102 C . Conclusion

  14. Accelerated life testing effects on CMOS microcircuit characteristics

    NASA Technical Reports Server (NTRS)

    1977-01-01

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

  15. Accelerated life testing effects on CMOS microcircuit characteristics

    NASA Technical Reports Server (NTRS)

    1980-01-01

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

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

    SciTech Connect

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

    2009-04-23

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

  17. Tamoxifen inhibits ER-negative breast cancer cell invasion and metastasis by accelerating Twist1 degradation.

    PubMed

    Ma, Gang; He, Jianjun; Yu, Yang; Xu, Yixiang; Yu, Xiaobin; Martinez, Jarrod; Lonard, David M; Xu, Jianming

    2015-01-01

    Twist1 is a transcription factor driving epithelial-mesenchymal transition, invasion and metastasis of breast cancer cells. Mice with germ-line Twist1 knockout are embryonic lethal, while adult mice with inducible Twist1 knockout have no obvious health problems, suggesting that Twist1 is a viable therapeutic target for the inhibition of invasion and metastasis of breast cancer in adult patients. In this study, we expressed a luciferase protein or a Twist1-luciferase fusion protein in HeLa cells as part of a high throughput system to screen 1280 compounds in the Library of Pharmacologically Active Compounds (LOPAC) from Sigma-Aldrich for their effects on Twist1 protein expression. One of the most interesting compounds identified is tamoxifen, a selective estrogen receptor (ER) modulator used to treat ER-positive breast cancer. Tamoxifen treatment significantly accelerated Twist1 degradation in multiple cell lines including HEK293 human kidney cells, 4T1 and 168FARN mouse mammary tumor cells with either ectopically or endogenously expressed Twist1. Tamoxifen-induced Twist1 degradation could be blocked by the MG132 proteasome inhibitor, suggesting that tamoxifen induces Twist1 degradation through the ubiquitination-proteasome pathway. However, tamoxifen-induced Twist1 degradation was independent of Twist1 mRNA expression, estrogen signaling and MAPK-mediated Twist1 phosphorylation in these cells. Importantly, tamoxifen also significantly inhibited invasive behavior in Matrigel and lung metastasis in SCID-bg mice of ER-negative 4T1 mammary tumor cells, which depend on endogenous Twist1 to invade and metastasize. These results indicate that tamoxifen can significantly accelerate Twist1 degradation to suppress cancer cell invasion and metastasis, suggesting that tamoxifen can be used not only to treat ER-positive breast cancers but also to reduce Twist1-mediated invasion and metastasis in ER-negative breast cancers.

  18. Performance Degradation of Encapsulated Monocrystalline-Si Solar Cells upon Accelerated Weathering Exposures: Preprint

    SciTech Connect

    Glick, S. H.; Pern, F. J.; Watson, G. L.; Tomek, D.; Raaff, J.

    2001-10-01

    Presented at 2001 NCPV Program Review Meeting: Performed accelerated exposures to study performance reliability/materials degradation of encapsulated c-Si cells using weathering protocols in 2 weatherometers. We have performed accelerated exposures to study performance reliability and materials degradation of a total of forty-one 3-cm x 3-cm monocrystalline-Si (c-Si) solar cells that were variously encapsulated using accelerated weathering protocols in two weatherometers (WOMs), with and without front specimen water sprays. Laminated cells (EVA/c-Si/EVA, ethylene vinyl acetate) with one of five superstrate/substrate variations and other features including with and without: (i) load resistance, (ii) Al foil light masks, and (iii) epoxy edge-sealing were studied. Three additional samples, omitting EVA, were exposed under a full-spectrum solar simulator, or heated in an oven, for comparison. After exposures, cell performance decreased irregularly, but to a relatively greater extent for samples exposed in WOM where light, heat, and humidity cycles were present (solar simulator or oven lacked such cycles). EVA laminates in the samples masked with aluminum (Al) foils were observed to retain moisture in WOM with water spray. Moisture effects caused substantial efficiency losses probably related in part to increasing series resistance.

  19. Computer modeling of test particle acceleration at oblique shocks

    NASA Technical Reports Server (NTRS)

    Decker, Robert B.

    1988-01-01

    The present evaluation of the basic techniques and illustrative results of charged particle-modeling numerical codes suitable for particle acceleration at oblique, fast-mode collisionless shocks emphasizes the treatment of ions as test particles, calculating particle dynamics through numerical integration along exact phase-space orbits. Attention is given to the acceleration of particles at planar, infinitessimally thin shocks, as well as to plasma simulations in which low-energy ions are injected and accelerated at quasi-perpendicular shocks with internal structure.

  20. The Advanced Superconducting Test Accelerator at Fermilab: Science Program

    SciTech Connect

    Piot, Philippe; Harms, Elvin; Henderson, Stuart; Leibfritz, Jerry; Nagaitsev, Sergei; Shiltsev, Vladimir; Valishev, Alexander

    2014-07-01

    The Advanced Superconducting Test Accelerator (ASTA) currently in commissioning phase at Fermilab is foreseen to support a broad range of beam-based experiments to study fundamental limitations to beam intensity and to develop novel approaches to particle-beam generation, acceleration and manipulation. ASTA incorporates a superconducting radiofrequency (SCRF) linac coupled to a flexible high-brightness photoinjector. The facility also includes a small-circumference storage ring capable of storing electrons or protons. This report summarizes the facility capabilities, and provide an overview of the accelerator-science researches to be enabled.

  1. Preliminary description of the ground test accelerator cryogenic cooling system

    SciTech Connect

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

    1988-01-01

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

  2. Earth Scanner Bearing Accelerated Life Test

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  3. Earth Scanner Bearing Accelerated Life Test

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  4. Geniposide accelerates proteasome degradation of Txnip to inhibit insulin secretion in pancreatic β-cells.

    PubMed

    Liu, C Y; Hao, Y N; Yin, F; Zhang, Y L; Liu, J H

    2017-05-01

    To analyze the role of geniposide in the protein degradation of Txnip and to determine the impact of Txnip on geniposide-regulated GSIS in pancreatic INS-1 cells. The content of Txnip protein was measured by western blot; insulin content and glucose uptake were determined by ELISA; and knockdown of Txnip was the method of RNA interference. Glucose induces a rapid increase in Txnip protein, and geniposide accelerates the degradation of Txnip via proteasome pathway in the presence of high glucose (25 mM) in INS-1 pancreatic β-cells. And MG132, a proteasomal inhibitor, potentiates glucose uptake, metabolism (ATP production) and glucose-stimulated insulin secretion (GSIS) in high-glucose (25 mM)-treated INS-1 cells, but geniposide significantly prevents these effects. Furthermore, the combination of geniposide and Txnip knockdown shows substantial synergistic effects to reduce glucose uptake, metabolism and GSIS in high-glucose (25 mM)-treated INS-1 cells. Txnip protein played an essential role in glucose uptake, metabolism and GSIS, and geniposide could accelerate the degradation via proteasome pathway in high-glucose-treated pancreatic INS-1 cells.

  5. MHD turbulence, reconnection, and test-particle acceleration

    NASA Technical Reports Server (NTRS)

    Gray, Perry C.; Matthaeus, William H.

    1992-01-01

    We examine homogeneous MHD turbulence and turbulent magnetic reconnection as possible mechanisms for accelerating cosmic ray particles. Test particle calculations are performed using fields from MHD simulations, and initially Maxwellian particle distributions are shown to evolve into power-law distributions. Simple estimates for both the maximum energy attainable and the mean energies of the accelerated particles are fairly successful and are consistent with timescales for flares and cosmic rays.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  8. Accelerated Stress Testing of Solar Photovoltaic Modules

    DTIC Science & Technology

    1981-09-01

    1200C (2480F) 2 0.0 z -A VZe~ or z- V - 011-: r t r- 1’ 4m a. .5&.A - -i Z I -1 - 4K-3 ’P, 4 m mqzl S; 0. OLAOR POT.!’R LPk. ~~ dml I’.v SPCTROLA3...I _ . ..,_- -’I ... _ ESI !- I’ ’ [ : 1 ’" 󈧓 S * r_- M A~ IIN U F= IC TI~E S - P E CT~ L E:I F M i O _ L_ ,1: u cI__ C I -3’ UL...alternate spraying with fresh water and drying . (using eight GE 275-watt sunlamps and four GE 40BL ultraviolet lamps). This pre-exposure test continued

  9. Accelerated testing of solid oxide fuel cell stacks for micro combined heat and power application

    NASA Astrophysics Data System (ADS)

    Hagen, Anke; Høgh, Jens Valdemar Thorvald; Barfod, Rasmus

    2015-12-01

    State-of-the-art (SoA) solid oxide fuel cell (SOFC) stacks are tested using profiles relevant for use in micro combined heat and power (CHP) units. Such applications are characterised by dynamic load profiles. In order to shorten the needed testing time and to investigate potential acceleration of degradation, the profiles are executed faster than required for real applications. Operation with fast load cycling, both using hydrogen and methane/steam as fuels, does not accelerate degradation compared to constant operation, which demonstrates the maturity of SoA stacks and enables transferring knowledge from testing at constant conditions to dynamic operation. 7.5 times more cycles than required for 80,000 h lifetime as micro CHP are achieved on one-cell-stack level. The results also suggest that degradation mechanisms that proceed on a longer time-scale, such as creep, might have a more dominating effect for long life-times than regular short time changes of operation. In order to address lifetime testing it is suggested to build a testing program consisting of defined modules that represent different application profiles, such as one module at constant conditions, followed by modules at one set of dynamic conditions etc.

  10. Evaluation of an Accelerated ELDRS Test Using Molecular Hydrogen

    NASA Technical Reports Server (NTRS)

    Pease, Ronald L.; Adell, Philippe C.; Rax, Bernard; McClure, Steven; Barnaby, Hugh J.; Kruckmeyer, Kirby; Triggs, B.

    2011-01-01

    An accelerated total ionizing dose (TID) hardness assurance test for enhanced low dose rate sensitive (ELDRS) bipolar linear circuits, using high dose rate tests on parts that have been exposed to molecular hydrogen, has been proposed and demonstrated on several ELDRS part types. In this study several radiation-hardened "ELDRS-free" part types have been tested using this same approach to see if the test is overly conservative.

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

    PubMed

    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).

  12. A Complex of Htm1 and the Oxidoreductase Pdi1 Accelerates Degradation of Misfolded Glycoproteins.

    PubMed

    Pfeiffer, Anett; Stephanowitz, Heike; Krause, Eberhard; Volkwein, Corinna; Hirsch, Christian; Jarosch, Ernst; Sommer, Thomas

    2016-06-03

    A quality control system in the endoplasmic reticulum (ER) efficiently discriminates polypeptides that are in the process of productive folding from conformers that are trapped in an aberrant state. Only the latter are transported into the cytoplasm and degraded in a process termed ER-associated protein degradation (ERAD). In the ER, an enzymatic cascade generates a specific N-glycan structure of seven mannosyl and two N-acetylglucosamine residues (Man7GlcNAc2) on misfolded glycoproteins to facilitate their disposal. We show that a complex encompassing the yeast lectin-like protein Htm1 and the oxidoreductase Pdi1 converts Man8GlcNAc2 on glycoproteins into the Man7GlcNAc2 signal. In vitro the Htm1-Pdi1 complex processes both unfolded and native proteins albeit with a preference for the former. In vivo, elevated expression of HTM1 causes glycan trimming on misfolded and folded proteins, but only degradation of the non-native species is accelerated. Thus, modification with a Man7GlcNAc2 structure does not inevitably commit a protein for ER-associated protein degradation. The function of Htm1 in ERAD relies on its association with Pdi1, which appears to regulate the access to substrates. Our data support a model in which the balanced activities of Pdi1 and Htm1 are crucial determinants for the efficient removal of misfolded secretory glycoproteins.

  13. Testing and Analysis for Lifetime Prediction of Crystalline Silicon PV Modules Undergoing Degradation by System Voltage Stress: Preprint

    SciTech Connect

    Hacke, P.; Smith, R.; Terwiliger, K.; Glick, S.; Jordan, D.; Johnston, S.; Kempe, M.; Kurtz, S.

    2012-07-01

    Acceleration factors are calculated for crystalline silicon PV modules under system voltage stress by comparing the module power during degradation outdoors to that in accelerated testing at three temperatures and 85% relative humidity. A lognormal analysis is applied to the accelerated lifetime test data considering failure at 80% of the initial module power. Activation energy of 0.73 eV for the rate of failure is determined, and the probability of module failure at an arbitrary temperature is predicted. To obtain statistical data for multiple modules over the course of degradation in-situ of the test chamber, dark I-V measurements are obtained and transformed using superposition, which is found well suited for rapid and quantitative evaluation of potential-induced degradation. It is determined that shunt resistance measurements alone do not represent the extent of power degradation. This is explained with a two-diode model analysis that shows an increasing second diode recombination current and ideality factor as the degradation in module power progresses. Failure modes of the modules stressed outdoors are examined and compared to those stressed in accelerated tests.

  14. Accelerated Testing of Polymeric Composites Using the Dynamic Mechanical Analyzer

    NASA Technical Reports Server (NTRS)

    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.

  15. TESTING METGLAS FOR USE IN DARHT ACCELERATOR CELLS

    SciTech Connect

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

    2001-06-01

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

  16. Accelerated life testing effects on CMOS microcircuit characteristics, phase 1

    NASA Technical Reports Server (NTRS)

    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.

  17. Method for the Accelerated Testing of the Durability of a Construction Binder using the Arrhenius Approach

    NASA Astrophysics Data System (ADS)

    Fridrichová, Marcela; Dvořák, Karel; Gazdič, Dominik

    2016-03-01

    The single most reliable indicator of a material's durability is its performance in long-term tests, which cannot always be carried out due to a limited time budget. The second option is to perform some kind of accelerated durability tests. The aim of the work described in this article was to develop a method for the accelerated durability testing of binders. It was decided that the Arrhenius equation approach and the theory of chemical reaction kinetics would be applied in this case. The degradation process has been simplified to a single quantifiable parameter, which became compressive strength. A model hydraulic binder based on fluidised bed combustion ash (FBC ash) was chosen as the test subject for the development of the method. The model binder and its hydration products were tested by high-temperature X-ray diffraction analysis. The main hydration product of this binder was ettringite. Due to the thermodynamic instability of this mineral, it was possible to verify the proposed method via long term testing. In order to accelerate the chemical reactions in the binder, four combinations of two temperatures (65 and 85°C) and two different relative humidities (14 and 100%) were used. The upper temperature limit was chosen because of the results of the high-temperature x-ray testing of the ettringite's decomposition. The calculation formulae for the accelerated durability tests were derived on the basis of data regarding the decrease in compressive strength under the conditions imposed by the four above-mentioned combinations. The mineralogical composition of the binder after degradation was also described. The final degradation product was gypsum under dry conditions and monosulphate under wet conditions. The validity of the method and formula was subsequently verified by means of long-term testing. A very good correspondence between the calculated and real values was achieved. The deviation of these values did not exceed 5 %. The designed and verified method

  18. Cycle life estimation of lithium secondary battery by extrapolation method and accelerated aging test

    NASA Astrophysics Data System (ADS)

    Takei, K.; Kumai, K.; Kobayashi, Y.; Miyashiro, H.; Terada, N.; Iwahori, T.; Tanaka, T.

    The testing methods to estimate the life cycles of lithium ion batteries for a short period, have been developed using a commercialized cell with LiCoO 2/hard carbon cell system. The degradation reactions with increasing cycles were suggested to occur predominantly above 4 V from the results of operating voltage range divided tests. In the case of the extrapolation method using limited cycle data, the straight line approximation was useful as the cycle performance has the linearity, but the error is at most 40% in using the initial short cycle data. In the case of the accelerated aging tests using the following stress factors, the charge and/or discharge rate, large accelerated coefficients were obtained in the high charge rate and the high temperature thermal stress.

  19. Quick setup of unit test for accelerator controls system

    SciTech Connect

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

    2011-03-28

    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.

  20. Ultrasonic agitation method for accelerating batch leaching tests

    SciTech Connect

    Caldwell, R.J.; Stegemann, J.A.; Chao, C.C.

    1996-12-31

    A method has been developed which uses ultrasonic cavitation to accelerate batch leaching tests. Batch leaching tests, in which attainment of an equilibrium between the solid sample and liquid leachant is desired, usually involve particle size reduction and mixing to hasten mass transfer of soluble compounds. In the study discussed here, mixing in the form of ultrasonic cavitation was used to supply an intense level of agitation. Breaking the liquid boundary layer surrounding individual waste particles ensured a maximum concentration gradient between the solid and liquid phases and accelerated attainment of steady state concentrations. Evaluation of the acceleration technique was made through comparison of leachate quality of stabilized/solidified (S/S) residue samples tested using the Wastewater Technology Centre`s (WTC) equilibrium extraction (EE) and an ultrasonically agitated version of the same test method (UEE). The sample preparation, liquid-to-solid ratio, extraction fluid, etc., specified in the EE method were held constant for the EE and UEE samples, while the duration and method of agitation was altered for the UEE samples. To date, this evaluation has been made using five metal finishing residues, which were selected based on their elevated concentrations of regulated contaminants. The results of the evaluations are presented and suggestions are made as to the applicability of this accelerated test method.

  1. Next Linear Collider Test Accelerator conceptual design report

    SciTech Connect

    Not Available

    1993-08-01

    This document presents the scientific justification and the conceptual design for the {open_quotes}Next Linear Collider Test Accelerator{close_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 current{close_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.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Design of Octupole Channel for Integrable Optics Test Accelerator

    SciTech Connect

    Antipov, Sergey; Carlson, Kermit; Castellotti, Riccardo; Valishev, Alexander; Wesseln, Steven

    2016-06-01

    We present the design of octupole channel for Integrable Optics Test Accelerator (IOTA). IOTA is a test accelerator at Fermilab, aimed to conduct research towards high-intensity machines. One of the goals of the project is to demonstrate high nonlinear betatron tune shifts while retaining large dynamic aperture in a realistic accelerator design. At the first stage the tune shift will be attained with a special channel of octupoles, which creates a variable octupole potential over a 1.8 m length. The channel consists of 18 identical air-cooled octupole magnets. The magnets feature a simple low-cost design, while meeting the requirements on maximum gradient - up to 1.4 kG/cm³, and field quality - strength of harmonics below 1%. Numerical simulations show that the channel is capable of producing a nonlinear tune shift of 0.08 without restriction of dynamic aperture of the ring.

  4. The test pulse line ion accelerator in Lanzhou

    NASA Astrophysics Data System (ADS)

    Shen, Xiao-Kang; Cao, Shu-Chun; Zhang, Zi-Min; Zhao, Hong-Wei; Zhao, Quan-Tang; Liu, Ming; Jing, Yi; Li, Zhong-Ping; Wan, Ming; Wang, Bin; Yang, Chun-Ming; Xiao, Rong-Qing; Zhang, Ying-Fa; Li, Ji-An

    2012-03-01

    To accelerate intense, short pulsed heavy ion beams to the energies of interest for studies of high energy density physics and warm dense matter, the Pulse Line Ion Accelerator (PLIA), of which the axial acceleration gradient can achieve several MeV per meter with realistic helix parameters at very low cost, was developed in recent years. A simple prototype of PLIA for a proof-of-principle experiment called the Lanzhou Test PLIA was designed and constructed at the Institute of Modern Physics in Lanzhou, and the test result matches the calculated result well. The pattern of the axial electric field Ez and the velocity of the traveling wave were simulated by CST.

  5. rf breakdown tests of mm-wave metallic accelerating structures

    DOE PAGES

    Dal Forno, Massimo; Dolgashev, Valery; Bowden, Gordon; ...

    2016-01-06

    In this study, we explore the physics and frequency-scaling of vacuum rf breakdowns at sub-THz frequencies. We present the experimental results of rf tests performed in metallic mm-wave accelerating structures. These experiments were carried out at the facility for advanced accelerator experimental tests (FACET) at the SLAC National Accelerator Laboratory. The rf fields were excited by the FACET ultrarelativistic electron beam. We compared the performances of metal structures made with copper and stainless steel. The rf frequency of the fundamental accelerating mode, propagating in the structures at the speed of light, varies from 115 to 140 GHz. The traveling wavemore » structures are 0.1 m long and composed of 125 coupled cavities each. We determined the peak electric field and pulse length where the structures were not damaged by rf breakdowns. We calculated the electric and magnetic field correlated with the rf breakdowns using the FACET bunch parameters. The wakefields were calculated by a frequency domain method using periodic eigensolutions. Such a method takes into account wall losses and is applicable to a large variety of geometries. The maximum achieved accelerating gradient is 0.3 GV/m with a peak surface electric field of 1.5 GV/m and a pulse length of about 2.4 ns.« less

  6. rf breakdown tests of mm-wave metallic accelerating structures

    NASA Astrophysics Data System (ADS)

    Dal Forno, Massimo; Dolgashev, Valery; Bowden, Gordon; Clarke, Christine; Hogan, Mark; McCormick, Doug; Novokhatski, Alexander; Spataro, Bruno; Weathersby, Stephen; Tantawi, Sami G.

    2016-01-01

    We are exploring the physics and frequency-scaling of vacuum rf breakdowns at sub-THz frequencies. We present the experimental results of rf tests performed in metallic mm-wave accelerating structures. These experiments were carried out at the facility for advanced accelerator experimental tests (FACET) at the SLAC National Accelerator Laboratory. The rf fields were excited by the FACET ultrarelativistic electron beam. We compared the performances of metal structures made with copper and stainless steel. The rf frequency of the fundamental accelerating mode, propagating in the structures at the speed of light, varies from 115 to 140 GHz. The traveling wave structures are 0.1 m long and composed of 125 coupled cavities each. We determined the peak electric field and pulse length where the structures were not damaged by rf breakdowns. We calculated the electric and magnetic field correlated with the rf breakdowns using the FACET bunch parameters. The wakefields were calculated by a frequency domain method using periodic eigensolutions. Such a method takes into account wall losses and is applicable to a large variety of geometries. The maximum achieved accelerating gradient is 0.3 GV /m with a peak surface electric field of 1.5 GV /m and a pulse length of about 2.4 ns.

  7. Neuronal-Targeted TFEB Accelerates Lysosomal Degradation of APP, Reducing Aβ Generation and Amyloid Plaque Pathogenesis.

    PubMed

    Xiao, Qingli; Yan, Ping; Ma, Xiucui; Liu, Haiyan; Perez, Ronaldo; Zhu, Alec; Gonzales, Ernesto; Tripoli, Danielle L; Czerniewski, Leah; Ballabio, Andrea; Cirrito, John R; Diwan, Abhinav; Lee, Jin-Moo

    2015-09-02

    In AD, an imbalance between Aβ production and removal drives elevated brain Aβ levels and eventual amyloid plaque deposition. APP undergoes nonamyloidogenic processing via α-cleavage at the plasma membrane, amyloidogenic β- and γ-cleavage within endosomes to generate Aβ, or lysosomal degradation in neurons. Considering multiple reports implicating impaired lysosome function as a driver of increased amyloidogenic processing of APP, we explored the efficacy of targeting transcription factor EB (TFEB), a master regulator of lysosomal pathways, to reduce Aβ levels. CMV promoter-driven TFEB, transduced via stereotactic hippocampal injections of adeno-associated virus particles in APP/PS1 mice, localized primarily to neuronal nuclei and upregulated lysosome biogenesis. This resulted in reduction of APP protein, the α and β C-terminal APP fragments (CTFs), and in the steady-state Aβ levels in the brain interstitial fluid. In aged mice, total Aβ levels and amyloid plaque load were selectively reduced in the TFEB-transduced hippocampi. TFEB transfection in N2a cells stably expressing APP695, stimulated lysosome biogenesis, reduced steady-state levels of APP and α- and β-CTFs, and attenuated Aβ generation by accelerating flux through the endosome-lysosome pathway. Cycloheximide chase assays revealed a shortening of APP half-life with exogenous TFEB expression, which was prevented by concomitant inhibition of lysosomal acidification. These data indicate that TFEB enhances flux through lysosomal degradative pathways to induce APP degradation and reduce Aβ generation. Activation of TFEB in neurons is an effective strategy to attenuate Aβ generation and attenuate amyloid plaque deposition in AD. A key driver for AD pathogenesis is the net balance between production and clearance of Aβ, the major component of amyloid plaques. Here we demonstrate that lysosomal degradation of holo-APP influences Aβ production by limiting the availability of APP for amyloidogenic

  8. Neuronal-Targeted TFEB Accelerates Lysosomal Degradation of APP, Reducing Aβ Generation and Amyloid Plaque Pathogenesis

    PubMed Central

    Xiao, Qingli; Yan, Ping; Ma, Xiucui; Liu, Haiyan; Perez, Ronaldo; Zhu, Alec; Gonzales, Ernesto; Tripoli, Danielle L.; Czerniewski, Leah; Ballabio, Andrea; Cirrito, John R.

    2015-01-01

    In AD, an imbalance between Aβ production and removal drives elevated brain Aβ levels and eventual amyloid plaque deposition. APP undergoes nonamyloidogenic processing via α-cleavage at the plasma membrane, amyloidogenic β- and γ-cleavage within endosomes to generate Aβ, or lysosomal degradation in neurons. Considering multiple reports implicating impaired lysosome function as a driver of increased amyloidogenic processing of APP, we explored the efficacy of targeting transcription factor EB (TFEB), a master regulator of lysosomal pathways, to reduce Aβ levels. CMV promoter-driven TFEB, transduced via stereotactic hippocampal injections of adeno-associated virus particles in APP/PS1 mice, localized primarily to neuronal nuclei and upregulated lysosome biogenesis. This resulted in reduction of APP protein, the α and β C-terminal APP fragments (CTFs), and in the steady-state Aβ levels in the brain interstitial fluid. In aged mice, total Aβ levels and amyloid plaque load were selectively reduced in the TFEB-transduced hippocampi. TFEB transfection in N2a cells stably expressing APP695, stimulated lysosome biogenesis, reduced steady-state levels of APP and α- and β-CTFs, and attenuated Aβ generation by accelerating flux through the endosome-lysosome pathway. Cycloheximide chase assays revealed a shortening of APP half-life with exogenous TFEB expression, which was prevented by concomitant inhibition of lysosomal acidification. These data indicate that TFEB enhances flux through lysosomal degradative pathways to induce APP degradation and reduce Aβ generation. Activation of TFEB in neurons is an effective strategy to attenuate Aβ generation and attenuate amyloid plaque deposition in AD. SIGNIFICANCE STATEMENT A key driver for AD pathogenesis is the net balance between production and clearance of Aβ, the major component of amyloid plaques. Here we demonstrate that lysosomal degradation of holo-APP influences Aβ production by limiting the availability of

  9. Acceleration tests of a 3 GHz proton linear accelerator (LIBO) for hadrontherapy

    NASA Astrophysics Data System (ADS)

    De Martinis, C.; Giove, D.; Amaldi, U.; Berra, P.; Crandall, K.; Mauri, M.; Weiss, M.; Zennaro, R.; Rosso, E.; Szeless, B.; Vretenar, M.; Masullo, M. R.; Vaccaro, V.; Calabretta, L.; Rovelli, A.

    2012-07-01

    This paper describes the acceleration tests performed at the Catania LNS Laboratory on a 3 GHz linac module of the side coupled type, which boosts the proton energy of a beam extracted from a cyclotron from 62 to 72 MeV. The output proton energy was measured with two devices: a NaI(Tl) crystal and a bending magnet. The experimental spectra are in good agreement with the calculated ones. From their shape it is obtained that (18±3.0)% of the transmitted protons fall in a ±2 MeV interval centered around 72 MeV. This result is in good agreement with the 20% value derived from the simulation of the acceleration process. The measured energy of the accelerated protons was used to check that the shunt impedance of the structure is equal to the computed one within 3%. This was the first time that a 3 GHz structure has been used to accelerate protons, and the results of the tests have demonstrated that a high frequency linac can be used as a cyclotron booster.

  10. Cryogenic cooling system for the Ground Test Accelerator

    SciTech Connect

    Edeskuty, F.J.; Stewart, W.F.; Moeller, J.; Durham, F.; Spulgis, I.

    1994-12-31

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

  11. Cryogenic cooling system for the ground test accelerator

    SciTech Connect

    Edeskuty, F.J.; Stewart, W.F.; Moeller, J.; Durham, F. ); Spulgis, I. )

    1993-01-01

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

  12. Cryogenic cooling system for the ground test accelerator

    SciTech Connect

    Edeskuty, F.J.; Stewart, W.F.; Moeller, J.; Durham, F.; Spulgis, I.

    1993-06-01

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

  13. Robust Design of Reliability Test Plans Using Degradation Measures.

    SciTech Connect

    Lane, Jonathan Wesley; Lane, Jonathan Wesley; Crowder, Stephen V.; Crowder, Stephen V.

    2014-10-01

    With short production development times, there is an increased need to demonstrate product reliability relatively quickly with minimal testing. In such cases there may be few if any observed failures. Thus, it may be difficult to assess reliability using the traditional reliability test plans that measure only time (or cycles) to failure. For many components, degradation measures will contain important information about performance and reliability. These measures can be used to design a minimal test plan, in terms of number of units placed on test and duration of the test, necessary to demonstrate a reliability goal. Generally, the assumption is made that the error associated with a degradation measure follows a known distribution, usually normal, although in practice cases may arise where that assumption is not valid. In this paper, we examine such degradation measures, both simulated and real, and present non-parametric methods to demonstrate reliability and to develop reliability test plans for the future production of components with this form of degradation.

  14. Fabrication and cold test of dielectric assist accelerating structure

    NASA Astrophysics Data System (ADS)

    Satoh, D.; Yoshida, M.; Hayashizaki, N.

    2017-09-01

    We present the detailed description of a successful design and cold testing of the dielectric assist accelerating (DAA) structure. The DAA structure consists of ultralow-loss dielectric cylinders and disks with irises which are periodically arranged in a metallic enclosure. The advantage of the DAA structure is that it has an extremely high quality factor and a very high shunt impedance at room temperature since the electromagnetic field distribution of accelerating mode can be controlled by dielectric parts so that the wall loss on the metallic surface is greatly reduced. A prototype of the five-cell DAA structure was designed and built at C-band (5.712 GHz), and cold tested. Three types of dielectric cell structure, "regular," "end," and "hybrid" dielectric cells, are fabricated by sintering high-purity magnesia. The prototype was assembled by stacking these cells in the hollow copper cylinder, whose two ends are closed by copper plates. The resonant frequency of the prototype was tuned to the desired frequency by machining only end copper plates. The unloaded quality factor of the accelerating mode was measured at 119,314 and the shunt impedance per unit length of the prototype was estimated from the experimental results of the bead pull measurement as Zsh=617 M Ω /m , which were within 2 percent of the design values. The field distribution of accelerating mode was also measured by the bead pull method, and its results agreed well with simulation results.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Preloading To Accelerate Slow-Crack-Growth Testing

    NASA Technical Reports Server (NTRS)

    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.

  18. Test ion acceleration in a dynamic planar electron sheath

    NASA Astrophysics Data System (ADS)

    Basko, M. M.

    2007-03-01

    New exact results are obtained for relativistic acceleration of test positive ions in the laminar zone of a planar electron sheath evolving from an initially mono-energetic electron distribution. The electron dynamics is calculated against the background of motionless foil ions. The limiting gamma-factor γp∞ of accelerated ions is shown to be determined primarily by the values of the ion-electron charge-over-mass ratio μ=meZp/mp and the initial gamma-factor γ0 of the accelerated electrons. For μ> 1/8 a test ion always overtakes the electron front and attains γp∞> γ0. For μ< 1/8 a test ion can catch up with the electron front only when γ0 is above a certain critical value γcr, which for μ≪1 can most often be evaluated as γ_{cr} = ({1}/{4}) μexpleft(μ^{-1}-1right). In this model the protons and heavier test ions, for which γcr> 10398 is enormous, always lag behind the front edge of the electron sheath and have γp∞< γ0; for their maximum energy an appropriate intermediate asymptotic formula is derived. The domain of applicability of the laminar-zone results is analyzed in detail.

  19. Reproduction of natural corrosion by accelerated laboratory testing methods

    SciTech Connect

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

    1996-05-01

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

  20. Accelerated testing of module-level power electronics for long-term reliability

    DOE PAGES

    Flicker, Jack David; Tamizhmani, Govindasamy; Moorthy, Mathan Kumar; ...

    2016-11-10

    This work has applied a suite of long-term-reliability accelerated tests to a variety of module-level power electronics (MLPE) devices (such as microinverters and optimizers) from five different manufacturers. This dataset is one of the first (only the paper by Parker et al. entitled “Dominant factors affecting reliability of alternating current photovoltaic modules,” in Proc. 42nd IEEE Photovoltaic Spec. Conf., 2015, is reported for reliability testing in the literature), as well as the largest, experimental sets in public literature, both in the sample size (five manufacturers including both dc/dc and dc/ac units and 20 units for each test) and the numbermore » of experiments (six different experimental test conditions) for MLPE devices. The accelerated stress tests (thermal cycling test per IEC 61215 profile, damp heat test per IEC 61215 profile, and static temperature tests at 100 and 125 °C) were performed under powered and unpowered conditions. The first independent long-term experimental data regarding damp heat and grid transient testing, as well as the longest term (>9 month) testing of MLPE units reported in the literature for thermal cycling and high-temperature operating life, are included in these experiments. Additionally, this work is the first to show in situ power measurements, as well as periodic efficiency measurements over a series of experimental tests, demonstrating whether certain tests result in long-term degradation or immediate catastrophic failures. Lastly, the result of this testing highlights the performance of MLPE units under the application of several accelerated environmental stressors.« less

  1. Accelerated testing of module-level power electronics for long-term reliability

    SciTech Connect

    Flicker, Jack David; Tamizhmani, Govindasamy; Moorthy, Mathan Kumar; Thiagarajan, Ramanathan; Ayyanar, Raja

    2016-11-10

    This work has applied a suite of long-term-reliability accelerated tests to a variety of module-level power electronics (MLPE) devices (such as microinverters and optimizers) from five different manufacturers. This dataset is one of the first (only the paper by Parker et al. entitled “Dominant factors affecting reliability of alternating current photovoltaic modules,” in Proc. 42nd IEEE Photovoltaic Spec. Conf., 2015, is reported for reliability testing in the literature), as well as the largest, experimental sets in public literature, both in the sample size (five manufacturers including both dc/dc and dc/ac units and 20 units for each test) and the number of experiments (six different experimental test conditions) for MLPE devices. The accelerated stress tests (thermal cycling test per IEC 61215 profile, damp heat test per IEC 61215 profile, and static temperature tests at 100 and 125 °C) were performed under powered and unpowered conditions. The first independent long-term experimental data regarding damp heat and grid transient testing, as well as the longest term (>9 month) testing of MLPE units reported in the literature for thermal cycling and high-temperature operating life, are included in these experiments. Additionally, this work is the first to show in situ power measurements, as well as periodic efficiency measurements over a series of experimental tests, demonstrating whether certain tests result in long-term degradation or immediate catastrophic failures. Lastly, the result of this testing highlights the performance of MLPE units under the application of several accelerated environmental stressors.

  2. Accelerated stress testing of solar photovoltaic modules. Interim report

    SciTech Connect

    Trenchard, S.E.

    1981-09-01

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

  3. Biodegradation of 4-nitrophenol in standardized aquatic degradation tests

    SciTech Connect

    Nyholm, N.; Lindgaard-Jorgensen, P.; Hansen, N.

    1984-10-01

    During the years 1978-1981 both the European Economic Community (the EEC) and the Organization for Economic Cooperation and Development (the OECD) organized various interlaboratory comparison programs on standardized screening methods to study the biodegradability of chemicals in water. While the ring test results were generally rather heterogenous, one of the compounds studied, 4-nitrophenol, turned out to be particularly problematic as the compound was found either easily biodegradable or not biodegradable by various laboratories in various tests. This paper describes some more detailed studies on 4-nitrophenol degradation in two different tests, the modified OECD screening test (MOST test) and the Zahn-Wellens test, respectively. The test variables investigated include inoculum characteristics and pretreatment, test duration, and 4-nitrophenol concentration. The results are discussed in relation to toxicity and degradation pathways of 4-nitrophenol. It is concluded that in order to improve the comparability of results from standardized aquatic biodegradation tests, test strategies should allow the option of performing a test with a preadapted inoculum in the event of negative test results with freshly collected inocula. Increasing the inoculated concentration of microorganisms in some tests may also contribute to the attainment of more consistent test results.

  4. Characterization, Modeling, and Accelerating Emulation of Aircraft Coating Exposure and Degradation

    DTIC Science & Technology

    2009-09-30

    Maocheng Yan Stuart Croll Jun Nie Jinhai Wang Dennis Tallman Quan Su Yechung Wang Kerry Allahar Andrew Huovinen Duhua Wang Brian Hinderliter...than may natural weathering. Thus coating failure due to adhesion loss or hydrolysis can be very different between accelerated testing protocols... Kerry Allahar and Brian Hinderliter. Some of the results are discussed above. The results of these studies are also discussed in detail in the

  5. Visualization of TlBr ionic transport mechanism by the Accelerated Device Degradation technique

    NASA Astrophysics Data System (ADS)

    Datta, Amlan; Becla, Piotr; Motakef, Shariar

    2015-06-01

    Thallium Bromide (TlBr) is a promising gamma radiation semiconductor detector material. However, it is an ionic semiconductor and suffers from polarization. As a result, TlBr devices degrade rapidly at room temperature. Polarization is associated with the flow of ionic current in the crystal under electrical bias, leading to the accumulation of charged ions at the device's electrical contacts. We report a fast and reliable direct characterization technique to identify the effects of various growth and post-growth process modifications on the polarization process. The Accelerated Device Degradation (ADD) characterization technique allows direct observation of nucleation and propagation of ionic transport channels within the TlBr crystals under applied bias. These channels are observed to be initiated both directly under the electrode as well as away from it. The propagation direction is always towards the anode indicating that Br- is the mobile diffusing species within the defect channels. The effective migration energy of the Br- ions was calculated to be 0.33±0.03 eV, which is consistent with other theoretical and experimental results.

  6. Predictive models of poly(ethylene-terephthalate) film degradation under multi-factor accelerated weathering exposures

    PubMed Central

    Ngendahimana, David K.; Fagerholm, Cara L.; Sun, Jiayang; Bruckman, Laura S.

    2017-01-01

    Accelerated weathering exposures were performed on poly(ethylene-terephthalate) (PET) films. Longitudinal multi-level predictive models as a function of PET grades and exposure types were developed for the change in yellowness index (YI) and haze (%). Exposures with similar change in YI were modeled using a linear fixed-effects modeling approach. Due to the complex nature of haze formation, measurement uncertainty, and the differences in the samples’ responses, the change in haze (%) depended on individual samples’ responses and a linear mixed-effects modeling approach was used. When compared to fixed-effects models, the addition of random effects in the haze formation models significantly increased the variance explained. For both modeling approaches, diagnostic plots confirmed independence and homogeneity with normally distributed residual errors. Predictive R2 values for true prediction error and predictive power of the models demonstrated that the models were not subject to over-fitting. These models enable prediction under pre-defined exposure conditions for a given exposure time (or photo-dosage in case of UV light exposure). PET degradation under cyclic exposures combining UV light and condensing humidity is caused by photolytic and hydrolytic mechanisms causing yellowing and haze formation. Quantitative knowledge of these degradation pathways enable cross-correlation of these lab-based exposures with real-world conditions for service life prediction. PMID:28498875

  7. Internal loop photo-biodegradation reactor used for accelerated quinoline degradation and mineralization.

    PubMed

    Chang, Ling; Zhang, Yongming; Gan, Lu; Xu, Hua; Yan, Ning; Liu, Rui; Rittmann, Bruce E

    2014-07-01

    Biofilm biodegradation was coupled with ultra-violet photolysis using the internal loop photobiodegradation reactor for degradation of quinoline. Three protocols-photolysis alone (P), biodegradation alone (B), and intimately coupled photolysis and biodegradation (P&B)-were used for degradation of quinoline in batch and continuous-flow experiments. For a 1,000 mg/L initial quinoline concentration, the volumetric removal rate for quinoline was 38 % higher with P&B than with B in batch experiments, and the P&B kinetics were the sum of kinetics from the P and B experiments. Continuous-flow experiments with an influent quinoline concentration of 1,000 mg/L also gave significantly greater quinoline removal in P&B, and the quinoline-removal kinetics for P&B were approximately equal to the sum of the removal kinetics for P and B. P&B similarly increased the rate and extent of quinoline mineralization, for which the kinetics for P&B were nearly equal to the sum of kinetics for P and B. These findings support that the rate-limiting step for mineralization was transformation of quinoline, which was accelerated by the simultaneous action of photolysis and biodegradation.

  8. Mechanical Stability Study for Integrable Optics Test Accelerator at Fermilab

    SciTech Connect

    McGee, Mike; Andrews, Richard; Carlson, Kermit; Leibfritz, Jerry; Nobrega, Lucy; Valishev, Alexander

    2016-07-01

    The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p⁺) diagnostic test ring. A heavy low frequency steel floor girder is proposed as the primary tier for IOTA device component support. Two design lengths; (8) 4 m and (2) 2.8 m long girders with identical cross section completely encompass the ring. This study focuses on the 4 m length girder and the development of a working prototype. Hydrostatic Level Sensor (HLS), temperature, metrology and fast motion measurements characterize the anticipated mechanical stability of the IOTA ring.

  9. Testing in a combined vibration and acceleration environment.

    SciTech Connect

    Jepsen, Richard Alan; Romero, Edward F.

    2004-10-01

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

  10. Accelerated Creep Testing of High Strength Aramid Webbing

    NASA Technical Reports Server (NTRS)

    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.

  11. Accelerated aging test results for aerospace wire insulation constructions

    NASA Technical Reports Server (NTRS)

    Dunbar, William G.

    1995-01-01

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

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

    SciTech Connect

    Puskar, Joseph David; Quintana, Michael A.; Sorensen, Neil Robert; Lucero, Samuel J.

    2009-07-01

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

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

    ScienceCinema

    Andrei Seryi

    2016-07-12

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

  14. System Voltage Potential-Induced Degradation Mechanisms in PV Modules and Methods for Test

    SciTech Connect

    Hacke, P.; Terwilliger, K.; Smith, R.; Glick, S.; Pankow, J.; Kempe, M.; Kurtz, S.; Bennett, I.; Kloos, M.

    2011-01-01

    Over the past decade, degradation and power loss have been observed in PV modules resulting from the stress exerted by system voltage bias. This is due in part to qualification tests and standards that do not adequately evaluate for the durability of modules to the long-term effects of high voltage bias experienced in fielded arrays. High voltage can lead to module degradation by multiple mechanisms. The extent of the voltage bias degradation is linked to the leakage current or culombs passed from the silicon active layer through the encapsulant and glass to the grounded module frame, which can be experimentally determined; however, competing processes make the effect non-linear and history-dependent. Appropriate testing methods and stress levels are described that demonstrate module durability to system voltage potential-induced degradation (PID) mechanisms. This information, along with outdoor testing that is in progress, is used to estimate the acceleration factors needed to evaluate the durability of modules to system voltage stress. Na-rich precipitates are observed on the cell surface after stressing the module to induce PID in damp heat with negative bias applied to the active layer.

  15. System Voltage Potential-Induced Degradation Mechanisms in PV Modules and Methods for Test: Preprint

    SciTech Connect

    Hacke, P.; Terwilliger, K.; Smith, R.; Glick, S.; Pankow, J.; Kempe, M.; Kurtz, S.; Bennett, I.; Kloos, M.

    2011-07-01

    Over the past decade, degradation and power loss have been observed in PV modules resulting from the stress exerted by system voltage bias. This is due in part to qualification tests and standards that do not adequately evaluate for the durability of modules to the long-term effects of high voltage bias experienced in fielded arrays. High voltage can lead to module degradation by multiple mechanisms. The extent of the voltage bias degradation is linked to the leakage current or coulombs passed from the silicon active layer through the encapsulant and glass to the grounded module frame, which can be experimentally determined; however, competing processes make the effect non-linear and history-dependent. Appropriate testing methods and stress levels are described that demonstrate module durability to system voltage potential-induced degradation (PID) mechanisms. This information, along with outdoor testing that is in progress, is used to estimate the acceleration factors needed to evaluate the durability of modules to system voltage stress. Na-rich precipitates are observed on the cell surface after stressing the module to induce PID in damp heat with negative bias applied to the active layer.

  16. Test Sequence for Superconducting XFEL Cavities in the Accelerator Module Test Facility (AMTF) at DESY

    NASA Astrophysics Data System (ADS)

    Schaffran, J.; Petersen, B.; Reschke, D.; Swierblewski, J.

    The European XFEL is a new research facility currently under construction at DESY in the Hamburg area in Germany. From 2016 onwards, it will generate extremely intense X-ray flashes that will be used by researchers from all over the world. The main part of the superconducting European XFEL linear accelerator consists of 100 accelerator modules with 800 RF-cavities inside. The accelerator modules, superconducting magnets and cavities will be tested in the accelerator module test facility (AMTF) at DESY. This paper gives an overview of the test sequences for the superconducting cavities, applied in the preparation area and at the two cryostats (XATC) of the AMTF-hall, and describes the complete area. In addition it summarizes the tests and lessons learnt until the middle of 2014.

  17. Accelerated Life Tests under Competing Weibull Causes of Failure.

    DTIC Science & Technology

    1981-06-01

    rj denote the number of systems which fail from cause j at stress V , j = 1, ..., p, i = 1, ..., s. The Ni items on test at stress Vi, i = 1, ..., s...A-f-AI02 560 MISSOU UMIV-COLUMBIA DEPT OF STATISTICS F/6 2/ ACCELERATED LIFE TESTS UNDER COMPETING WEIBULL CAUSES OF FAILUR.-ETC(U) N J 81 J P KLEIN... Causes of Failure by John P. Klein Department of Statistics, Ohio State University Asit P Basu Department of Statistics, University of Missouri

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

    SciTech Connect

    Not Available

    1986-08-01

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

  19. The Accelerator Production of Tritium Materials Test Program

    SciTech Connect

    Maloy, Stuart A.; Sommer, Walter F.; James, Michael R.; Romero, Tobias J.; Lopez, Manuel R.; Zimmermann, Eugene; Ledbetter, James M.

    2000-10-15

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

  20. Ultra-accelerated natural sunlight exposure testing facilities

    DOEpatents

    Lewandowski, Allan A.; Jorgensen, Gary J.

    2003-08-12

    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 to deliver a uniform flux of UV/VIS onto a sample exposure plane located near a center of a facet array in chamber means 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.

  1. Ultra-Accelerated Natural Sunlight Exposure Testing Facilities

    DOEpatents

    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.

  2. Vibrational measurement for commissioning SRF Accelerator Test Facility at Fermilab

    SciTech Connect

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

    2011-03-01

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

  3. Database requirements for the Advanced Test Accelerator project

    SciTech Connect

    Chambers, F.W.

    1984-11-05

    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.

  4. Commissioning of the Ground Test Accelerator Intertank Matching Section

    SciTech Connect

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

    1992-09-01

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

  5. Commissioning of the Ground Test Accelerator Intertank Matching Section

    SciTech Connect

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

  6. Recovery mechanisms in proton exchange membrane fuel cells after accelerated stress tests

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Guo, Liejin; Liu, Hongtan

    2015-11-01

    The mechanisms of performance recovery after accelerated stress test (AST) in proton exchange membrane fuel cells (PEMFCs) are systematically studied. Experiments are carried out by incorporating a well-designed performance recovery procedure right after the AST protocol. The experiment results show that the cell performance recovers significantly from the degraded state after the AST procedure. The results from cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements further show that the performance recovery can be divided into kinetic and mass transport recoveries. It is further determined that the kinetic recovery, i.e. the recovery of electrochemical active area (ECA), is due to two distinct mechanisms: the reduction of platinum oxide and the re-attachment of detached platinum nanoparticles onto the carbon surface. The mass transport resistance is probably due to reduction of hydrophilic oxide groups on the carbon surface and the microstructure change that alleviates flooding. Performance comparisons show that the recovery procedure is highly effective, indicating the results of AST significantly over-estimate the true degradation in a PEM fuel cell. Therefore, a recovery procedure is highly recommended when an AST protocol is used to evaluate cell degradations to avoid over-estimating true performance degradations in PEMFCs.

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

    NASA Technical Reports Server (NTRS)

    Bhattacharya, Pallab

    2001-01-01

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

  8. Thermally Accelerated Oxidative Degradation of Quercetin Using Continuous Flow Kinetic Electrospray-Ion Trap-Time of Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Barnes, Jeremy S.; Foss, Frank W.; Schug, Kevin A.

    2013-10-01

    Thermally accelerated oxidative degradation of aqueous quercetin at pH 5.9 and 7.4 was kinetically measured using an in-house built online continuous flow device made of concentric capillary tubes, modified to fit to the inlet of an electrospray ionization-ion trap-time-of-flight-mass spectrometer (ESI-IT-TOF-MS). Time-resolved mass spectral measurements ranging from 2 to 21 min were performed in the negative mode to track intermediate degradation products and to evaluate the degradation rate of the deprotonated quercetin ion, [Q-H]-. Upon heating solutions in the presence of dissolved oxygen, degradation of [Q-H]- was observed and was accelerated by an increase in pH and temperature. Regardless of the condition, the same degradation pathways were observed. Degradation mechanisms and structures were determined using higher order tandem mass spectrometry (up to MS3) and high mass accuracy. The observed degradation mechanisms included oxidation, hydroxylation, and ring-cleavage by nucleophilic attack. A chalcan-trione structure formed by C-ring opening after hydroxylation at C2 was believed to be a precursor for other degradation products, formed by hydroxylation at the C2, C3, and C4 carbons from attack by nucleophilic species. This resulted in A-type and B-type ions after cross-ring cleavage of the C-ring. Based on time of appearance and signal intensity, nucleophilic attack at C3 was the preferred degradation pathway, which generated 2,4,6-trihydroxymandelate and 2,4,6-trihydroxyphenylglyoxylate ions. Overall, 23 quercetin-related ions were observed.

  9. Results of accelerated thermal cycle tests of solar cells modules

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  10. Metal and elastomer seal tests for accelerator applications

    SciTech Connect

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

    1989-01-01

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

  11. Testing Gravity and Cosmic Acceleration with Galaxy Clustering

    NASA Astrophysics Data System (ADS)

    Kazin, Eyal; Tinker, J.; Sanchez, A. G.; Blanton, M.

    2012-01-01

    The large-scale structure contains vast amounts of cosmological information that can help understand the accelerating nature of the Universe and test gravity on large scales. Ongoing and future sky surveys are designed to test these using various techniques applied on clustering measurements of galaxies. We present redshift distortion measurements of the Sloan Digital Sky Survey II Luminous Red Galaxy sample. We find that when combining the normalized quadrupole Q with the projected correlation function wp(rp) along with cluster counts (Rapetti et al. 2010), results are consistent with General Relativity. The advantage of combining Q and wp is the addition of the bias information, when using the Halo Occupation Distribution framework. We also present improvements to the standard technique of measuring Hubble expansion rates H(z) and angular diameter distances DA(z) when using the baryonic acoustic feature as a standard ruler. We introduce clustering wedges as an alternative basis to the multipole expansion and show that it yields similar constraints. This alternative basis serves as a useful technique to test for systematics, and ultimately improve measurements of the cosmic acceleration.

  12. Proton Injection into the Fermilab Integrable Optics Test Accelerator (IOTA)

    SciTech Connect

    Prebys, Eric; Antipov, Sergey; Piekarz, Henryk; Valishev, A.

    2015-06-01

    The Integrable Optics Test Accelerator (IOTA) is an experimental synchrotron being built at Fermilab to test the concept of non-linear "integrable optics". These optics are based on a lattice including non-linear elements that satisfies particular conditions on the Hamiltonian. The resulting particle motion is predicted to be stable but without a unique tune. The system is therefore insensitive to resonant instabilities and can in principle store very intense beams, with space charge tune shifts larger than those which are possible in conventional linear synchrotrons. The ring will initially be tested with pencil electron beams, but this poster describes the ultimate plan to install a 2.5 MeV RFQ to inject protons, which will produce tune shifts on the order of unity. Technical details will be presented, as well as simulations of protons in the ring.

  13. Using co-metabolism to accelerate synthetic starch wastewater degradation and nutrient recovery in photosynthetic bacterial wastewater treatment technology.

    PubMed

    Lu, Haifeng; Zhang, Guangming; Lu, Yufeng; Zhang, Yuanhui; Li, Baoming; Cao, Wei

    2016-01-01

    Starch wastewater is a type of nutrient-rich wastewater that contains numerous macromolecular polysaccharides. Using photosynthetic bacteria (PSB) to treat starch wastewater can reduce pollutants and enhance useful biomass production. However, PSB cannot directly degrade macromolecular polysaccharides, which weakens the starch degradation effect. Therefore, co-metabolism with primary substances was employed in PSB wastewater treatment to promote starch degradation. The results indicated that co-metabolism is a highly effective method in synthetic starch degradation by PSB. When malic acid was used as the optimal primary substrate, the chemical oxygen demand, total sugar, macromolecules removal and biomass yield were considerably higher than when primary substances were not used, respectively. Malic acid was the primary substrate that played a highly important role in starch degradation. It promoted the alpha-amylase activity to 46.8 U and the PSB activity, which induced the degradation of macromolecules. The products in the wastewater were ethanol, acetic acid and propionic acid. Ethanol was the primary product throughout the degradation process. The introduction of co-metabolism with malic acid to treat wastewater can accelerate macromolecules degradation and bioresource production and weaken the acidification effect. This method provides another pathway for bioresource recovery from wastewater. This approach is a sustainable and environmentally friendly wastewater treatment technology.

  14. Pyrene degradation accelerated by constructed consortium of bacterium and microalga: effects of degradation products on the microalgal growth.

    PubMed

    Luo, Shusheng; Chen, Baowei; Lin, Li; Wang, Xiaowei; Tam, Nora Fung-Yee; Luan, Tiangang

    2014-12-02

    Abundant microbes including bacteria, fungi, or algae are capable of biodegrading polycyclic hydrocarbons (PAHs). However, pure cultures never occur in the contaminated environments. This study aimed to understand the general potential mechanisms of interactions between microbes under pollution stress by constructing a consortium of PAH-degrading microalga (Selenastrum capricornutum) and bacterium (Mycobacterium sp. strain A1-PYR). Bacteria alone could grow on the pyrene, whereas the growth of algae alone was substantially inhibited by the pyrene of 10 mg L(-1). In the mixing culture of algae and bacteria, the growth rate of algae was significantly increased from day 4 onward. Rapid bacterial degradation of pyrene might mitigate the toxicity of pyrene to algae. Phenolic acids, the bacterial degradation products of pyrene, could serve as the phytohormone for promoting algal growth in the coculture of algae and bacteria. In turn, bacterial growth was also enhanced by the algae presented in the mixing culture. Consequently, the fastest degradation of pyrene among all biodegradation systems was achieved by the consortium of algae and bacteria probably due to such interactions between the two species by virtue of degradation products. This study reveals that the consortium containing multiple microbial species is high potential for microbial remediation of pyrene-contaminated environments, and provides a new strategy to degrade the recalcitrant PAHs.

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  16. Development of test methods for assessing microbial influenced degradation of cement-solidified radioactive and industrial waste

    SciTech Connect

    Rogers, R.D.; Knight, J.J.; Cheeseman, C.R.; Wolfram, J.H.; Idachaba, M.; Nyavor, K.; Egiebor, N.O

    2003-12-01

    This paper reports on the development of accelerated tests for evaluating microbial influenced degradation (MID) of cement-solidified wastes. An existing U.S. Nuclear Regulatory Commission accelerated test cannot distinguish between degradation caused by biogenic acid produced under optimal conditions in a bioreactor and that caused by active biofilms formed on the waste materials. Nutrient limitations were also observed that would significantly limit the activity of any developing biofilm. Results from this work have shown that it is possible to modify this test to remove nutrient limitations and enable the effects of MID resulting from active biofilms to be examined. Aggressive MID microorganisms can form a biofilm on the surface of cement-solidified waste so that when nutrients are provided the microbes remain active. Elemental mass loss data from exposed solidified waste forms indicate the continued development and growth of microbes on the surface of samples.

  17. Statistical characteristics of mechanical heart valve cavitation in accelerated testing.

    PubMed

    Wu, Changfu; Hwang, Ned H C; Lin, Yu-Kweng M

    2004-07-01

    Cavitation damage has been observed on mechanical heart valves (MHVs) undergoing accelerated testing. Cavitation itself can be modeled as a stochastic process, as it varies from beat to beat of the testing machine. This in-vitro study was undertaken to investigate the statistical characteristics of MHV cavitation. A 25-mm St. Jude Medical bileaflet MHV (SJM 25) was tested in an accelerated tester at various pulse rates, ranging from 300 to 1,000 bpm, with stepwise increments of 100 bpm. A miniature pressure transducer was placed near a leaflet tip on the inflow side of the valve, to monitor regional transient pressure fluctuations at instants of valve closure. The pressure trace associated with each beat was passed through a 70 kHz high-pass digital filter to extract the high-frequency oscillation (HFO) components resulting from the collapse of cavitation bubbles. Three intensity-related measures were calculated for each HFO burst: its time span; its local root-mean-square (LRMS) value; and the area enveloped by the absolute value of the HFO pressure trace and the time axis, referred to as cavitation impulse. These were treated as stochastic processes, of which the first-order probability density functions (PDFs) were estimated for each test rate. Both the LRMS value and cavitation impulse were log-normal distributed, and the time span was normal distributed. These distribution laws were consistent at different test rates. The present investigation was directed at understanding MHV cavitation as a stochastic process. The results provide a basis for establishing further the statistical relationship between cavitation intensity and time-evolving cavitation damage on MHV surfaces. These data are required to assess and compare the performance of MHVs of different designs.

  18. Acceleration of nonylphenol and 4-tert-octylphenol degradation in sediment by Phragmites australis and associated rhizosphere bacteria.

    PubMed

    Toyama, Tadashi; Murashita, Manabu; Kobayashi, Kazutaka; Kikuchi, Shintaro; Sei, Kazunari; Tanaka, Yasuhiro; Ike, Michihiko; Mori, Kazuhiro

    2011-08-01

    We investigated biodegradation of technical nonylphenol (tNP) in Phragmites australis rhizosphere sediment by conducting degradation experiments using sediments spiked with tNP. Accelerated tNP removal was observed in P. australis rhizosphere sediment, whereas tNP persisted in unvegetated sediment without plants and in autoclaved sediment with sterile plants, suggesting that the accelerated tNP removal resulted largely from tNP biodegradation by rhizosphere bacteria. Three bacterial strains, Stenotrophomonas sp. strain IT-1 and Sphingobium spp. strains IT-4 and IT-5, isolated from the rhizosphere were capable of utilizing tNP and 4-tert-octylphenol as a sole carbon source via type II ipso-substitution. Oxygen from P. australis roots, by creating highly oxygenated conditions in the sediment, stimulated cell growth and the tNP-degrading activity of the three strains. Moreover, organic compounds from P. australis roots functioned as carbon and energy sources for two strains, IT-4 and IT-5, supporting cell growth and tNP-degrading activity. Thus, P. australis roots elevated the cell growth and tNP-degrading activity of the three bacterial strains, leading to accelerated tNP removal. These results demonstrate that rhizoremediation of tNP-contaminated sediments using P. australis can be an effective strategy.

  19. Results of initial testing of the four stage RHEPP accelerator

    SciTech Connect

    Johnson, D.L.; Reed, K.W.; Harjes, H.C.

    1993-08-01

    The low power checkout of the Repetitive High Energy Pulsed Power (RHEPP) pulse forming line (PFL) and linear induction voltage adder (LIVA) is complete. The accelerator has four LIVA cavities driven via coaxial cables from the PFL that utilizes magnetic switching to provide a 250-kV, 60-ns output pulse. The PFL is repetitively charged by a ten stage Marx generator to operate from single shot to five Hz. Results from these tests of the initial four stage RHEPP accelerator are presented and compared with design simulations. Data from a resistive cavity load and from preliminary electron diode experiments are included. While core temperatures remain low during five Hz operation, they are monitored and compared to extrapolated predictions from the design modeling. Performance of the Metglas magnetic switches and blocking cores, the voltage addition in the four LIVA cavities, and system efficiencies are discussed. Sources of discrepancies from the original design models are identified, and improved models that account for the discrepancies are presented. Improved performance potential based on these models is discussed. Plans for future testing of the 1-MV system up to 120 kW at 120 Hz and for the full system with ten LIVA cavities are presented.

  20. Accelerated Neutron Testing of Semiconductor Devices at the LANSCE

    NASA Astrophysics Data System (ADS)

    Wender, S. A.; Bateman, F. B.; Haight, R. C.; Ullmann, J. L.

    1998-04-01

    The high-energy neutron source at the Los Alamos Neutron Science Center (LANSCE) produces beams of neutrons for accelerated testing of integrated circuit devices. Neutrons produced in the atmosphere by cosmic-rays are thought to be a significant threat to integrated circuits both at aircraft altitudes as well as at lower elevations. Neutrons have been shown to cause single event upsets, multiple event upsets, latchup and burnout in semiconductor devices. Neutrons are produced at LANSCE via spallation reactions with the 800 MeV pulsed proton beam. Proton beam currents of about 2 microamperes strike a tungsten target and produce a spectrum of neutrons whose energy and intensity can be precisely measured by time-of-flight techniques. The neutron spectrum produced in this manner has energies up to approximately 600 MeV and is very similar in shape to the atmospheric neutron spectrum at 40,000 ft. A flight path located at 20 m from the neutron production target is dedicated to accelerated testing of semiconductor devices. The integrated neutron flux above 1 MeV is about 10^6 n/cm^2/sec over an area about 10 cm in diameter. This intensity is about 10^5 (10^7) times greater than the cosmic-ray neutron flux at 40,000 ft (sea level).

  1. Accelerated tests for bounding the low dose rate radiation response of lateral PNP bipolar junction transistors

    SciTech Connect

    Witczak, S.C.; Schrimpf, R.D.; Galloway, K.F.; Schmidt, D.M.; Fleetwood, D.M.; Pease, R.L.; Coombs, W.E.; Suehle, J.S.

    1996-03-01

    Low dose rate gain degradation of lateral pnp bipolar transistors can be simulated by accelerated irradiations performed at approximately 135 degrees C. Degradation enhancement is explained by temperature- dependent radiation-induced interface trap formation above the transistor`s base.

  2. Accelerated stress testing of thin film solar cells: Development of test methods and preliminary results

    NASA Technical Reports Server (NTRS)

    Lathrop, J. W.

    1985-01-01

    If thin film cells are to be considered a viable option for terrestrial power generation their reliability attributes will need to be explored and confidence in their stability obtained through accelerated testing. Development of a thin film accelerated test program will be more difficult than was the case for crystalline cells because of the monolithic construction nature of the cells. Specially constructed test samples will need to be fabricated, requiring committment to the concept of accelerated testing by the manufacturers. A new test schedule appropriate to thin film cells will need to be developed which will be different from that used in connection with crystalline cells. Preliminary work has been started to seek thin film schedule variations to two of the simplest tests: unbiased temperature and unbiased temperature humidity. Still to be examined are tests which involve the passage of current during temperature and/or humidity stress, either by biasing in the forward (or reverse) directions or by the application of light during stress. Investigation of these current (voltage) accelerated tests will involve development of methods of reliably contacting the thin conductive films during stress.

  3. Accelerated Leach Testing of GLASS: ALTGLASS Version 3.0

    SciTech Connect

    Trivelpiece, Cory L.; Jantzen, Carol M.; Crawford, Charles L.

    2016-12-31

    The Accelerated Leach Testing of GLASS (ALTGLASS) database is a collection of data from short- and long-term product consistency tests (PCT, ASTM C1285 A and B) on high level waste (HLW) as well as low activity waste (LAW) glasses. The database provides both U.S. and international researchers with an archive of experimental data for the purpose of studying, modeling, or validating existing models of nuclear waste glass corrosion. The ALTGLASS database is maintained and updated by researchers at the Savannah River National Laboratory (SRNL). This newest version, ALTGLASS Version 3.0, has been updated with an additional 503 rows of data representing PCT results from corrosion experiments conducted in the United States by the Savannah River National Laboratory, Pacific Northwest National Laboratory, Argonne National Laboratory, and the Vitreous State Laboratory (SRNL, PNNL, ANL, VSL, respectively) as well as the National Nuclear Laboratory (NNL) in the United Kingdom.

  4. [Effects of Oil Pollutants on the Performance of Marine Benthonic Microbial Fuel Cells and Its Acceleration of Degradation].

    PubMed

    Meng, Yao; Fu, Yu-bin; Liang, Sheng-kang; Chen, Wei; Liu, Zhao-hui

    2015-08-01

    Degradation of oil pollutants under the sea is slow for its oxygen-free environment which has caused long-term harm to ocean environment. This paper attempts to accelerate the degradation of the sea oil pollutants through electro catalysis by using the principle of marine benthonic microbial fuel cells (BMFCs). The influence of oil pollutants on the battery performance is innovatively explored by comparing the marine benthonic microbial fuel cells ( BMFCs-A) containing oil and oil-free microbial fuel cells (BMFCs-B). The acceleration effect of BMFCs is investigated by the comparison between the oil-degrading rate and the number of heterotrophic bacteria of the BMFCs-A and BMFCs-B on their anodes. The results show that the exchange current densities in the anode of the BMFCs-A and BMFCs-B are 1. 37 x 10(-2) A x m(-2) and 1.50 x 10(-3) A x m(-2) respectively and the maximum output power densities are 105.79 mW x m(-2) and 83.60 mW x m(-2) respectively. The exchange current densities have increased 9 times and the maximum output power density increased 1. 27 times. The anti-polarization ability of BMFCs-A is improved. The heterotrophic bacteria numbers of BMFCs-A and BMFCs-C on their anodes are (66 +/- 3.61) x 10(7) CFU x g(-1) and (7.3 +/- 2.08) x 10(7) CFU x g(-1) respectively and the former total number has increased 8 times, which accelerates the oil-degrading rate. The degrading rate of the oil in the BMFCs-A is 18.7 times higher than that in its natural conditions. The BMFCs can improve its electrochemical performance, meanwhile, the degradation of oil pollutants can also be accelerated. A new model of the marine benthonic microbial fuel cells on its acceleration of oil degradation is proposed in this article.

  5. The application of electrochemistry to pharmaceutical stability testing--comparison with in silico prediction and chemical forced degradation approaches.

    PubMed

    Torres, Susana; Brown, Roland; Szucs, Roman; Hawkins, Joel M; Zelesky, Todd; Scrivens, Garry; Pettman, Alan; Taylor, Mark R

    2015-11-10

    The aim of this study was to evaluate the use of electrochemistry to generate oxidative degradation products of a model pharmaceutical compound. The compound was oxidized at different potentials using an electrochemical flow-cell fitted with a glassy carbon working electrode, a Pd/H2 reference electrode and a titanium auxiliary electrode. The oxidative products formed were identified and structurally characterized by LC-ESI-MS/MS using a high resolution Q-TOF mass spectrometer. Results from electrochemical oxidation using electrolytes of different pH were compared to those from chemical oxidation and from accelerated stability studies. Additionally, oxidative degradation products predicted using an in silico commercially available software were compared to those obtained from the various experimental methods. The electrochemical approach proved to be useful as an oxidative stress test as all of the final oxidation products observed under accelerated stability studies could be generated; previously reported reactive intermediate species were not observed most likely because the electrochemical mechanism differs from the oxidative pathway followed under accelerated stability conditions. In comparison to chemical degradation tests electrochemical degradation has the advantage of being much faster and does not require the use of strong oxidizing agents. Moreover, it enables the study of different operating parameters in short periods of time and optimisation of the reaction conditions (pH and applied potential) to achieve different oxidative products mixtures. This technique may prove useful as a stress test condition for the generation of oxidative degradation products and may help accelerate structure elucidation and development of stability indicating analytical methods.

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

    NASA Astrophysics Data System (ADS)

    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 cm2, 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.

  7. Accelerated degradation of 14C-atrazine in an atrazine adapted field soil from Belgium

    NASA Astrophysics Data System (ADS)

    Hamacher, Georg; Jablonowski, Nicolai David; Martinazzo, Rosane; Accinelli, Cesare; Köppchen, Stephan; Langen, Ulrike; Linden, Andreas; Krause, Martina; Burauel, Peter

    2010-05-01

    Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] is one of the most widely used herbicides in the world. Atrazine is considered to be mobile in soil and has often been characterized as a rather recalcitrant compound in the environment. In the present study the accelerated atrazine degradation in an agriculturally used soil was examined. Soil samples were collected from a Belgian field which was used for corn-plantations and was regularly treated with atrazine during the last 30 years. The experiment was conducted under controlled laboratory conditions (GLP) using 14C-labelled and unlabelled atrazine in accordance to the reported field application dose of 1 mg kg-1. Triplicates of treated subsamples were incubated at 50% WHCmax and under slurry conditions (1:4 soil:solution ratio, using distilled water) in the dark at 20° C. Control samples were collected at an adjacent pear orchard where no atrazine or other triazine pesticides application was reported. After 92 days of incubation, the mineralized amount of atrazine reached 83% of the initially applied 14C-activity in the atrazine treated soil for the slurry setup. A maximum of atrazine mineralization was observed in the treated field soil between 6 and 7 days of incubation for both, 50% WHCmax and slurry setups. The total 14C-atrazine mineralization was equally high for 50% WHCmax in the atrazine treated soil. After an extended lag-phase in comparison to the treated soil the overall mineralization of 14C-atrazine of 81% was observed in the atrazine untreated soil under slurry conditions. This observation might be due to a possible cross adaption of the microflora. These results could be attributed to an atrazine drift during application since the control samples were taken in an adjacent pear orchard with no atrazine application history. These results demonstrate an adaption of the microflora to mineralize atrazine rapidly. The formation of desorbable metabolites as well as the formation of

  8. Accelerating the degradation of green plant waste with chemical decomposition agents.

    PubMed

    Kejun, Sun; Juntao, Zhang; Ying, Chen; Zongwen, Liao; Lin, Ruan; Cong, Liu

    2011-10-01

    Degradation of green plant waste is often difficult, and excess maturity times are typically required. In this study, we used lignin, cellulose and hemicellulose assays; scanning electron microscopy; infrared spectrum analysis and X-ray diffraction analysis to investigate the effects of chemical decomposition agents on the lignocellulose content of green plant waste, its structure and major functional groups and the mechanism of accelerated degradation. Our results showed that adding chemical decomposition agents to Ficus microcarpa var. pusillifolia sawdust reduced the contents of lignin by 0.53%-11.48% and the contents of cellulose by 2.86%-7.71%, and increased the contents of hemicellulose by 2.92%-33.63% after 24 h. With increasing quantities of alkaline residue and sodium lignosulphonate, the lignin content decreased. Scanning electron microscopy showed that, after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, lignocellulose tube wall thickness increased significantlyIncreases of 29.41%, 3.53% and 34.71% were observed after treatment with NaOH, alkaline residue and sodium lignosulphonate, respectively. Infrared spectroscopy showed that CO and aromatic skeleton stretching absorption peaks were weakened and the C-H vibrational absorption peak from out-of-plane in positions 2 and 6 (S units) (890-900 cm(-1)) was strengthened after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, indicating a reduction in lignin content. Several absorption peaks [i.e., C-H deformations (asymmetry in methyl groups, -CH(3)- and -CH(2)-) (1450-1460 cm(-1)); Aliphatic C-H stretching in methyl and phenol OH (1370-1380 cm(-1)); CO stretching (cellulose and hemicellulose) (1040-1060 cm(-1))] that indicate the presence of a chemical bond between lignin and cellulose was reduced, indicating that the chemical bond between lignin and cellulose had been partially broken. X-ray diffraction analysis showed that Na

  9. Using Accelerated Testing To Predict Module Reliability: Preprint

    SciTech Connect

    Wohlgemuth, J. H.; Kurtz, S.

    2011-07-01

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

  10. Cosmic acceleration without dark energy: background tests and thermodynamic analysis

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  11. Cosmic acceleration without dark energy: background tests and thermodynamic analysis

    SciTech Connect

    Lima, J.A.S.; Graef, L.L.; Pavón, D.; Basilakos, Spyros E-mail: leilagraef@usp.br E-mail: svasil@academyofathens.gr

    2014-10-01

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

  12. Power-conditioning system for the Advanced Test Accelerator

    SciTech Connect

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

    1982-06-01

    The Advanced Test Accelerator (ATA) is a pulsed, linear induction, electron accelerator currently under construction and nearing completion at Lawrence Livermore National Laboratory's Site 300 near Livermore, California. The ATA is a 50 MeV, 10 kA machine capable of generating electron beam pulses at a 1 kHz rate in a 10 pulse burst, 5 pps average, with a pulse width of 70 ns FWHM. Ten 18 kV power supplies are used to charge 25 capacitor banks with a total energy storage of 8 megajoules. Energy is transferred from the capacitor banks in 500 microsecond pulses through 25 Command Resonant Charge units (CRC) to 233 Thyratron Switch Chassis. Each Thyratron Switch Chassis contains a 2.5 microfarad capacitor and is charged to 25 kV (780 joules) with voltage regulation of +- .05%. These capacitors are switched into 10:1 step-up resonant transformers to charge 233 Blumleins to 250 kV in 20 microseconds. A magnetic modulator is used instead of a Blumlein to drive the grid of the injector.

  13. Lessons learned on the Ground Test Accelerator control system

    SciTech Connect

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

    1994-09-01

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

  14. Degradation of a connexin40 mutant linked to atrial fibrillation is accelerated.

    PubMed

    Gemel, Joanna; Simon, Adria R; Patel, Dakshesh; Xu, Qin; Matiukas, Arvydas; Veenstra, Richard D; Beyer, Eric C

    2014-09-01

    Several Cx40 mutants have been identified in patients with atrial fibrillation (AF). We have been working to identify physiological or cell biological abnormalities of several of these human mutants that might explain how they contribute to disease pathogenesis. Wild type (wt) Cx40 or four different mutants (P88S, G38D, V85I, and L229M) were expressed by the transfection of communication-deficient HeLa cells or HL-1 cardiomyocytes. Biophysical channel properties and the sub-cellular localization and protein levels of Cx40 were characterized. Wild type Cx40 and all mutants except P88S formed gap junction plaques and induced significant gap junctional conductances. The functional mutants showed only modest alterations of single channel conductances or gating by trans-junctional voltage as compared to wtCx40. However, immunoblotting indicated that the steady state levels of G38D, V85I, and L229M were reduced relative to wtCx40; most strikingly, G38D was only 20-31% of wild type levels. After the inhibition of protein synthesis with cycloheximide, G38D (and to a lesser extent the other mutants) disappeared much faster than wtCx40. Treatment with the proteasomal inhibitor, epoxomicin, greatly increased levels of G38D and restored the abundance of gap junctions and the extent of intercellular dye transfer. Thus, G38D, V85I, and L229M are functional mutants of Cx40 with small alterations of physiological properties, but accelerated degradation by the proteasome. These findings suggest a novel mechanism (protein instability) for the pathogenesis of AF due to a connexin mutation and a novel approach to therapy (protease inhibition). Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Inoculation of Pichia kudriavzevii RB1 degrades the organic acids present in raw compost material and accelerates composting.

    PubMed

    Nakasaki, Kiyohiko; Araya, Shogo; Mimoto, Hiroshi

    2013-09-01

    In this study, the yeast strain Pichia kudriavzevii RB1 was used as an inoculum to accelerate organic matter degradation of rabbit food with added organic acids, which was used as a model food waste for composting. The RB1 strain rapidly degraded the organic acids present in the raw compost material, leading to an increase in pH beyond the neutral level, within 2 days. Both mesophilic and thermophilic bacteria proliferated faster in the compost with RB1 inoculation than in that without inoculation. Although the yeast died with the increase in compost temperature, it affected the early stages of composting prior to the thermophilic stage and accelerated the composting process by 2 days by eliminating the initial lag phase seen in the growth of other microorganisms. Moreover, populations of Bacillus thermoamylovorans, Bacillus foraminis, and Bacillus coagulans became dominant during the thermophilic stages of both composting with and without RB1 inoculation.

  16. Surface degradation of polymer insulators under accelerated climatic aging in weather-ometer

    SciTech Connect

    Xu, G.; McGrath, P.B.; Burns, C.W.

    1996-12-31

    Climatic aging experiments were conducted on two types of outdoor polymer insulators by using a programmable weather-ometer. The housing materials for the insulators were silicone rubber (SR) and ethylene propylene diene monomer (EPDM). The accelerated aging stresses were comprised of ultraviolet radiation, elevated temperature, temperature cycling, thermal shock and high humidity. Their effects on the insulator surface conditions and electrical performance wee examined through visual inspection and SEM studies, contact angle measurements, thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS) analysis, and 50% impulse flashover voltage tests. The results showed a significant damage on the insulator surface caused by some of the imposed aging stresses. The EDS analysis suggested a photooxidation process that happened on the insulator surface during the aging period.

  17. Integration Test of the High Voltage Hall Accelerator System Components

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  18. The use of accelerated radiation testing for avionics

    NASA Astrophysics Data System (ADS)

    Quinn, Heather

    2013-04-01

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

  19. A New Approach to Inference from Accelerated Life Tests.

    DTIC Science & Technology

    1978-10-01

    Ft A 0 A065 325 0t0R6E WASHINGTON UNIV WASHINGTON D C F~G l’e/2A NEW APPROACH To INFERENCE FROM ACCELERATED LIFE TESTS.(U) OCT 78 F PROSCHAN. N 0...SINSPURWALLA N000 14_t7eC_ 0265 UNCLASSIFIED AFOSI—TR—79—0098 ML P p _____ A REPORT DOCUMENTATION PAGE I ~~~~~~~~~~~~~~~~~~~~~~ I. REPORT NUMBER / 2...GOVT ACCESSION 3. RECIPIENT S CATALOG NUM _ RAFOSR4R. 79-0095 1 4. TITLE (and Subtlt l .) 5~ , TYPE OF REPORT & PERIOD COVERED A NEW APPROACH TO

  20. A flexible and configurable system to test accelerator magnets

    SciTech Connect

    Jerzy M. Nogiec et al.

    2001-07-20

    Fermilab's accelerator magnet R and D programs, including production of superconducting high gradient quadrupoles for the LHC insertion regions, require rigorous yet flexible magnetic measurement systems. Measurement systems must be capable of handling various types of hardware and extensible to all measurement technologies and analysis algorithms. A tailorable software system that satisfies these requirements is discussed. This single system, capable of distributed parallel signal processing, is built on top of a flexible component-based framework that allows for easy reconfiguration and run-time modification. Both core and domain-specific components can be assembled into various magnet test or analysis systems. The system configured to comprise a rotating coil harmonics measurement is presented. Technologies as Java, OODB, XML, JavaBeans, software bus and component-based architectures are used.

  1. Vibrational Stability of SRF Accelerator Test Facility at Fermilab

    SciTech Connect

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

    2009-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Sawant, M.; Christou, A.

    2012-12-01

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

  3. Evaluation of accelerated stability test conditions for medicated chewing gums.

    PubMed

    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.

  4. Development of Cu(In,Ga)Se2 Test Coupons for Potential Induced Degradation Studies

    SciTech Connect

    Contreras, Miguel A.; Hacke, Peter; Repins, Ingrid

    2016-11-21

    We report on the design, fabrication and accelerated testing of fully encapsulated small area coupons (approximately 7.5cm x 7.5 cm) for the purpose of researching potential induced degradation in Cu(In, Ga)Se2 based PV modules. The fabrication of these coupons enables the study of the solar cells and the materials used in PV module manufacturing such as top and bottom glass covers of different composition (soda-lime glass, high temperature glass, alkaline-free glass, etc), plastic-based top covers, ethylene vinyl acetate and edge seal encapsulation materials. The coupons can also be used to emulate framed and frameless modules that utilize either monolithically interconnected modules or singular cell type of modules. The design of the coupons, their fabrication, the materials used and their testing for 1000 hours under 85 degrees C and 85% RH conditions are presented.

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

    SciTech Connect

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

    1995-12-31

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

  6. Degradation of the TBC system during the static oxidation test.

    PubMed

    Moskal, G; Swadźba, L; Mendala, B; Góral, M; Hetmańczyk, M

    2010-03-01

    This study was done on the IN-738 type alloy with thermal barrier coatings. On the basic surface of the NiCoCrAlY superalloy, VPS-sprayed powder was applied as the bond-coat. In addition, ZrO(2)x 8%Y(2)O(3) powder was used for a deposition outside the top surface of a ceramic layer by the APS method. Appropriate control of the spraying process parameters permitted to obtain a gradient of porosity on the thickness of the ceramic coating. Then a static oxidation test at 1100 degrees C and for 1100 h was performed. The basic conclusions of that testing showed that main degradation modes of the gradient thermal barrier coating system were connected with formation of porous NiAl(2)O(4) oxides in the thermally grown oxide area and, consequently, formation of micro-cracks, delamination of a ceramic layer and final spallation of a ceramic top-coat.

  7. Preliminary analysis of accelerated space flight ionizing radiation testing

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  8. Voltage stress effects on microcircuit accelerated life test failure rates

    NASA Technical Reports Server (NTRS)

    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.

  9. Estimating service lifetimes of a polymer encapsulant for photovoltaic modules from accelerated testing

    SciTech Connect

    Czanderna, A.W.; Pern, F.J.

    1996-05-01

    In this paper, most of the emphasis is on A9918 ethylene vinyl acetate (EVA) used commercially as the pottant for encapsulating photovoltaic (PV) modules, in which the efficiencies in field-deployed modules have been reduced by 10-70% in 4-12 years. Yet, projections were made by several different research groups in the 1980s that the EVA lifetime could range from 2-100 years. The authors (1) elucidate the complexity of the encapsulation problem, (2) indicate the performance losses reported for PV systems deployed since 1981, (3) critically assess the service lifetime predictions for EVA as a PV pottant based on studies by others for which they review the inherent errors in their assumptions about the Arrhenius relation, (4) show how degradation of minimodules in laboratory experiments that simulate reality can produce efficiency losses comparable to those in field-degraded PV modules reported in the literature, and (5) outline an acceptable methodology for making a service lifetime prediction of the polymer encapsulant, including the essential need for relating accelerated lifetime testing to real-time testing with a sufficient number of samples.

  10. LeRC rail accelerators - Test designs and diagnostic techniques

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  11. Molecular modeling and redesign of alginate lyase from Pseudomonas aeruginosa for accelerating CRPA biofilm degradation.

    PubMed

    Cho, Hoon; Huang, Xiaoqin; Lan Piao, Yu; Eun Kim, Da; Yeon Lee, So; Jeong Yoon, Eun; Hee Park, So; Lee, Kyoung; Ho Jang, Chul; Zhan, Chang-Guo

    2016-12-01

    Administration of an efficient alginate lyase (AlgL) or AlgL mutant may be a promising therapeutic strategy for treatment of cystic fibrosis patients with Pseudomonas aeruginosa infections. Nevertheless, the catalytic activity of wild-type AlgL is not sufficiently high. It is highly desired to design and discover an AlgL mutant with significantly improved catalytic efficiency against alginate substrates. For the purpose of identifying an AlgL mutant with significantly improved catalytic activity, in this study, we first constructed and validated a structural model of AlgL interacting with substrate, providing a better understanding of the interactions between AlgL and its substrate. Based on the modeling insights, further enzyme redesign and experimental testing led to discovery of AlgL mutants, including the K197D/K321A mutant, with significantly improved catalytic activities against alginate and acetylated alginate in ciprofloxacin-resistant P. aeruginosa (CRPA) biofilms. Further anti-biofilm activity assays have confirmed that the K197D/K321A mutant with piperacillin/tazobactam is indeed effective in degrading the CRPA biofilms. Co-administration of the potent mutant AlgL and an antibiotic (such as a nebulizer) could be effective for therapeutic treatment of CRPA-infected patients with cystic fibrosis. Proteins 2016; 84:1875-1887. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  13. Specific methanogenic activity test for anaerobic degradation of influents

    NASA Astrophysics Data System (ADS)

    Hussain, Athar; Dubey, Shashi Kant

    2017-05-01

    Specific methanogenic activity (SMA) determines the methane-producing capability of the sludge for a specific substrate. Methanogenic activity test can be used to delineate the operating conditions for anaerobic systems and a parameter to assess the system performance by giving a better perceptive of the system and its stability. At the beginning of the start-up period of a new digester, the SMA is of great importance for the determination of proper initial organic loading rate. In different phases, a regular determination of SMA also ascertains the development stages of the sludge. Also, a change in SMA indicates an inhibition or an accumulation of slow degradable or even non-biodegradable organic matter from the influents. This paper reviews the SMA of anaerobic sludge under different operating conditions using different substrates.

  14. Demonstration recommendations for accelerated testing of concrete decontamination methods

    SciTech Connect

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

    1995-12-01

    A large number of aging US Department of Energy (DOE) surplus facilities located throughout the US require deactivation, decontamination, and decommissioning. Although several technologies are available commercially for concrete decontamination, emerging technologies with potential to reduce secondary waste and minimize the impact and risk to workers and the environment are needed. In response to these needs, the Accelerated Testing of Concrete Decontamination Methods project team described the nature and extent of contaminated concrete within the DOE complex and identified applicable emerging technologies. Existing information used to describe the nature and extent of contaminated concrete indicates that the most frequently occurring radiological contaminants are {sup 137}Cs, {sup 238}U (and its daughters), {sup 60}Co, {sup 90}Sr, and tritium. The total area of radionuclide-contaminated concrete within the DOE complex is estimated to be in the range of 7.9 {times} 10{sup 8} ft{sup 2}or approximately 18,000 acres. Concrete decontamination problems were matched with emerging technologies to recommend demonstrations considered to provide the most benefit to decontamination of concrete within the DOE complex. Emerging technologies with the most potential benefit were biological decontamination, electro-hydraulic scabbling, electrokinetics, and microwave scabbling.

  15. Synergistic acceleration of thyroid hormone degradation by phenobarbital and the PPAR{alpha} agonist WY14643 in rat hepatocytes

    SciTech Connect

    Wieneke, N.; Neuschaefer-Rube, F.; Bode, L.M.; Kuna, M.; Andres, J.; Carnevali, L.C.; Hirsch-Ernst, K.I.; Pueschel, G.P.

    2009-10-01

    Energy balance is maintained by controlling both energy intake and energy expenditure. Thyroid hormones play a crucial role in regulating energy expenditure. Their levels are adjusted by a tight feedback-controlled regulation of thyroid hormone production/incretion and by their hepatic metabolism. Thyroid hormone degradation has previously been shown to be enhanced by treatment with phenobarbital or other antiepileptic drugs due to a CAR-dependent induction of phase II enzymes of xenobiotic metabolism. We have recently shown, that PPAR{alpha} agonists synergize with phenobarbital to induce another prototypical CAR target gene, CYP2B1. Therefore, it was tested whether a PPAR{alpha} agonist could enhance the phenobarbital-dependent acceleration of thyroid hormone elimination. In primary cultures of rat hepatocytes the apparent half-life of T3 was reduced after induction with a combination of phenobarbital and the PPAR{alpha} agonist WY14643 to a larger extent than after induction with either compound alone. The synergistic reduction of the half-life could be attributed to a synergistic induction of CAR and the CAR target genes that code for enzymes and transporters involved in the hepatic elimination of T3, such as OATP1A1, OATP1A3, UGT1A3 and UGT1A10. The PPAR{alpha}-dependent CAR induction and the subsequent induction of T3-eliminating enzymes might be of physiological significance for the fasting-induced reduction in energy expenditure by fatty acids as natural PPAR{alpha} ligands. The synergism of the PPAR{alpha} agonist WY14643 and phenobarbital in inducing thyroid hormone breakdown might serve as a paradigm for the synergistic disruption of endocrine control by other combinations of xenobiotics.

  16. Synergistic acceleration of thyroid hormone degradation by phenobarbital and the PPAR alpha agonist WY14643 in rat hepatocytes.

    PubMed

    Wieneke, N; Neuschäfer-Rube, F; Bode, L M; Kuna, M; Andres, J; Carnevali, L C; Hirsch-Ernst, K I; Püschel, G P

    2009-10-01

    Energy balance is maintained by controlling both energy intake and energy expenditure. Thyroid hormones play a crucial role in regulating energy expenditure. Their levels are adjusted by a tight feedback-controlled regulation of thyroid hormone production/incretion and by their hepatic metabolism. Thyroid hormone degradation has previously been shown to be enhanced by treatment with phenobarbital or other antiepileptic drugs due to a CAR-dependent induction of phase II enzymes of xenobiotic metabolism. We have recently shown, that PPAR alpha agonists synergize with phenobarbital to induce another prototypical CAR target gene, CYP2B1. Therefore, it was tested whether a PPAR alpha agonist could enhance the phenobarbital-dependent acceleration of thyroid hormone elimination. In primary cultures of rat hepatocytes the apparent half-life of T3 was reduced after induction with a combination of phenobarbital and the PPAR alpha agonist WY14643 to a larger extent than after induction with either compound alone. The synergistic reduction of the half-life could be attributed to a synergistic induction of CAR and the CAR target genes that code for enzymes and transporters involved in the hepatic elimination of T3, such as OATP1A1, OATP1A3, UGT1A3 and UGT1A10. The PPAR alpha-dependent CAR induction and the subsequent induction of T3-eliminating enzymes might be of physiological significance for the fasting-induced reduction in energy expenditure by fatty acids as natural PPAR alpha ligands. The synergism of the PPAR alpha agonist WY14643 and phenobarbital in inducing thyroid hormone breakdown might serve as a paradigm for the synergistic disruption of endocrine control by other combinations of xenobiotics.

  17. Lattice design of the integrable optics test accelerator and optical stochastic cooling experiment at Fermilab

    SciTech Connect

    Kafka, Gene

    2015-05-01

    The Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab will serve as the backbone for a broad spectrum of Advanced Accelerator R&D (AARD) experiments, and as such, must be designed with signi cant exibility in mind, but without compromising cost e ciency. The nonlinear experiments at IOTA will include: achievement of a large nonlinear tune shift/spread without degradation of dynamic aperture; suppression of strong lattice resonances; study of stability of nonlinear systems to perturbations; and studies of di erent variants of nonlinear magnet design. The ring optics control has challenging requirements that reach or exceed the present state of the art. The development of a complete self-consistent design of the IOTA ring optics, meeting the demands of all planned AARD experiments, is presented. Of particular interest are the precise control for nonlinear integrable optics experiments and the transverse-to-longitudinal coupling and phase stability for the Optical Stochastic Cooling Experiment (OSC). Since the beam time-of- ight must be tightly controlled in the OSC section, studies of second order corrections in this section are presented.

  18. Testing of a Loop Heat Pipe Subjected to Variable Accelerating Forces

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  19. Degradation in PV Encapsulation Transmittance: An Interlaboratory Study Towards a Climate-Specific Test: Preprint

    SciTech Connect

    Miller, David C.; Annigoni, Eleonora; Ballion, Amal; Bokria, Jayesh G.; Bruckman, Laura S.; Burns, David M.; Chen, Xinxin; Elliott, Lamont; Feng, Jiangtao; French, Roger H.; Fowler, Sean; Gu, Xiaohong; Hacke, Peter L.; Honeker, Christian C.; Kempe, Michael D.; Khonkar, Hussam; Kohl, Michael; Perret-Aebi, Laure-Emmanuelle; Phillips, Nancy H.; Scott, Kurt P.; Sculati-Meillaud, Fanny; Shioda, Tsuyos

    2015-08-12

    Reduced optical transmittance of encapsulants resulting from ultraviolet (UV) degradation has frequently been identified as a cause of decreased PV module performance through the life of service in the field. The present module safety and qualification standards, however, apply short UV doses only capable of examining design robustness or 'infant mortality' failures. Essential information that might be used to screen encapsulation through product lifetime remains unknown. For example, the relative efficacy of xenon-arc and UVA-340 fluorescent sources or the typical range of activation energy for degradation is not quantified. We have conducted an interlaboratory experiment to provide the understanding that will be used towards developing a climate- and configuration-specific (UV) weathering test. Five representative, known formulations of EVA were studied in addition to one TPU material. Replicate laminated silica/polymer/silica specimens are being examined at 14 institutions using a variety of indoor chambers (including Xenon, UVA-340, and metal-halide light sources) or field aging. The solar-weighted transmittance, yellowness index, and the UV cut-off wavelength, determined from the measured hemispherical transmittance, are examined to provide understanding and guidance for the UV light source (lamp type) and temperature used in accelerated UV aging tests.

  20. Degradation in PV Encapsulation Transmittance: An Interlaboratory Study Toward a Climate-Specific Test

    SciTech Connect

    Miller, David C.; Hacke, Peter L.; Kempe, Michael D.; Wohlgemuth, John H.; Annigoni, Eleonora; Sculati-Meillaud, Fanny; Ballion, Amal; Kohl, Michael; Bokria, Jayesh G.; Bruckman, Laura S.; French, Roger H.; Burns, David; Phillips, Nancy H.; Feng; Jiangtao; Elliott, Lamont; Scott, Kurt P.; Fowler, Sean; Gu, Xiaohong; Honeker, Christian C.; Khonkar, Hussam; Perret-Aebi, Laure-Emmanuelle; Shioda, Tsy

    2015-06-14

    Reduced optical transmittance of encapsulation resulting from ultraviolet (UV) degradation has frequently been identified as a cause of decreased PV module performance through the life of installations in the field. The present module safety and qualification standards, however, apply short UV doses only capable of examining design robustness or 'infant mortality' failures. Essential information that might be used to screen encapsulation through product lifetime remains unknown. For example, the relative efficacy of xenon-arc and UVA-340 fluorescent sources or the typical range of activation energy for degradation is not quantified. We have conducted an interlaboratory experiment to provide the understanding that will be used towards developing a climate- and configuration-specific (UV) weathering test. Five representative, known formulations of EVA were studied in addition to one TPU material. Replicate laminated silica/polymer/silica specimens are being examined at 14 institutions using a variety of indoor chambers (including Xe, UVA-340, and metal-halide light sources) or field aging. The solar-weighted transmittance, yellowness index, and the UV cut-off wavelength, determined from the measured hemispherical transmittance, are examined to provide understanding and guidance for the UV light source (lamp type) and temperature used in accelerated UV aging tests. Index Terms -- reliability, durability, thermal activation.

  1. Degradation in PV Encapsulation Transmittance: An Interlaboratory Study Towards a Climate-Specific Test

    SciTech Connect

    Miller, David C.; Annigoni, Eleonora; Ballion, Amal; Bokria, Jayesh G.; Bruckman, Laura S.; Burns, David M.; Chen, Xinxin; Elliott, L.; Feng, J.; French, Roger H.; Fowler, S.; Gu, X.; Hacke, Peter L.; Honeker, C. C.; Kempe, Michael D.; Khonkar, H.; Kohl, M.; Perret-Aebi, Laure-Emmanuelle; Phillips, N. H.; Scott, K. P.; Sculati-Meillaud, F.; Shioda, T.; Suga, S.; Watanabe, S.; Wohlgemuth, John H.

    2015-06-14

    Reduced optical transmittance of encapsulants resulting from ultraviolet (UV) degradation has frequently been identified as a cause of decreased PV module performance through the life of service in the field. The present module safety and qualification standards, however, apply short UV doses only capable of examining design robustness or 'infant mortality' failures. Essential information that might be used to screen encapsulation through product lifetime remains unknown. For example, the relative efficacy of xenon-arc and UVA-340 fluorescent sources or the typical range of activation energy for degradation is not quantified. We have conducted an interlaboratory experiment to provide the understanding that will be used towards developing a climate- and configuration-specific (UV) weathering test. Five representative, known formulations of EVA were studied in addition to one TPU material. Replicate laminated silica/polymer/silica specimens are being examined at 14 institutions using a variety of indoor chambers (including Xenon, UVA-340, and metal-halide light sources) or field aging. The solar-weighted transmittance, yellowness index, and the UV cut-off wavelength, determined from the measured hemispherical transmittance, are examined to provide understanding and guidance for the UV light source (lamp type) and temperature used in accelerated UV aging tests.

  2. Amino acids induce peptide uptake via accelerated degradation of CUP9, the transcriptional repressor of the PTR2 peptide transporter.

    PubMed

    Xia, Zanxian; Turner, Glenn C; Hwang, Cheol-Sang; Byrd, Christopher; Varshavsky, Alexander

    2008-10-24

    Multiple pathways link expression of PTR2, the transporter of di- and tripeptides in the yeast Saccharomyces cerevisiae, to the availability and quality of nitrogen sources. Previous work has shown that induction of PTR2 by extracellular amino acids requires, in particular, SSY1 and PTR3. SSY1 is structurally similar to amino acid transporters but functions as a sensor of amino acids. PTR3 acts downstream of SSY1. Expression of the PTR2 peptide transporter is induced not only by amino acids but also by dipeptides with destabilizing N-terminal residues. These dipeptides bind to UBR1, the ubiquitin ligase of the N-end rule pathway, and allosterically accelerate the UBR1-dependent degradation of CUP9, a transcriptional repressor of PTR2. UBR1 targets CUP9 through its internal degron. Here we demonstrate that the repression of PTR2 by CUP9 requires TUP1 and SSN6, the corepressor proteins that form a complex with CUP9. We also show that the induction of PTR2 by amino acids is mediated by the UBR1-dependent acceleration of CUP9 degradation that requires both SSY1 and PTR3. The acceleration of CUP9 degradation is shown to be attained without increasing the activity of the N-end rule pathway toward substrates with destabilizing N-terminal residues. We also found that GAP1, a general amino acid transporter, strongly contributes to the induction of PTR2 by Trp. Although several aspects of this complex circuit remain to be understood, our findings establish new functional links between the amino acids-sensing SPS system, the CUP9-TUP1-SSN6 repressor complex, the PTR2 peptide transporter, and the UBR1-dependent N-end rule pathway.

  3. Hypersonic aerodynamics test facility using the external propulsion accelerator

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  4. Optical system for measurement of pyrotechnic test accelerations

    NASA Astrophysics Data System (ADS)

    Lieberman, Paul; Czajkowski, John; Rehard, John

    1992-12-01

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

  5. Hypersonic aerodynamics test facility using the external propulsion accelerator

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  6. Long Term Corrosion/Degradation Test Six Year Results

    SciTech Connect

    M. K. Adler Flitton; C. W. Bishop; M. E. Delwiche; T. S. Yoder

    2004-09-01

    The Subsurface Disposal Area (SDA) of the Radioactive Waste Management Complex (RWMC) located at the Idaho National Engineering and Environmental Laboratory (INEEL) contains neutron-activated metals from non-fuel, nuclear reactor core components. The Long-Term Corrosion/Degradation (LTCD) Test is designed to obtain site-specific corrosion rates to support efforts to more accurately estimate the transfer of activated elements to the environment. The test is using two proven, industry-standard methods—direct corrosion testing using metal coupons, and monitored corrosion testing using electrical/resistance probes—to determine corrosion rates for various metal alloys generally representing the metals of interest buried at the SDA, including Type 304L stainless steel, Type 316L stainless steel, Inconel 718, Beryllium S200F, Aluminum 6061, Zircaloy-4, low-carbon steel, and Ferralium 255. In the direct testing, metal coupons are retrieved for corrosion evaluation after having been buried in SDA backfill soil and exposed to natural SDA environmental conditions for times ranging from one year to as many as 32 years, depending on research needs and funding availability. In the monitored testing, electrical/resistance probes buried in SDA backfill soil will provide corrosion data for the duration of the test or until the probes fail. This report provides an update describing the current status of the test and documents results to date. Data from the one-year and three-year results are also included, for comparison and evaluation of trends. In the six-year results, most metals being tested showed extremely low measurable rates of general corrosion. For Type 304L stainless steel, Type 316L stainless steel, Inconel 718, and Ferralium 255, corrosion rates fell in the range of “no reportable” to 0.0002 mils per year (MPY). Corrosion rates for Zircaloy-4 ranged from no measurable corrosion to 0.0001 MPY. These rates are two orders of magnitude lower than those specified in

  7. Accelerated azo dye degradation and concurrent hydrogen production in the single-chamber photocatalytic microbial electrolysis cell.

    PubMed

    Hou, Yanping; Zhang, Renduo; Yu, Zebin; Huang, Lirong; Liu, Yuxin; Zhou, Zili

    2017-01-01

    The single-chamber microbial electrolysis cell constructed with a TiO2-coated photocathode, termed photocatalytic microbial electrolysis cell (PMEC), was developed to accelerate methyl orange (MO) degradation and concurrent hydrogen (H2) recovery under UV irradiation. Results showed that faster MO decolorization rates were achieved from the PMEC compared with those without UV irradiation or with open circuit. With increase of MO concentrations (acetate as co-substrate) from 50 to 300mg/L at an applied voltage of 0.8V, decolorization efficiencies decreased from 98% to 76% within 12h, and cyclic H2 production declined from 113 to 68mL. As the possible mechanism of MO degradation, bioelectrochemical reduction, co-metabolism reduction, and photocatalysis were involved; and degradation intermediates (mainly sulfanilic acid and N,N-dimethylaniline) were further degraded by OH generated from photocatalysis. This makes MO mineralization be possible in the single-chamber PMEC. Hence, the PMEC is a promising system for dyeing wastewater treatment and simultaneous H2 production. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2015-06-01

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

  9. Accelerated test methods for life prediction of hermetic motor insulation systems exposed to alternative refrigerant/lubricant mixtures. Final report

    SciTech Connect

    Ellis, II, P F; Ferguson, A F

    1995-04-19

    In 1992, the Air-Conditioning and Refrigeration Technology Institute, Inc. (ARTI) contracted Radian Corporation to ascertain whether an improved accelerated test method or procedure could be developed that would allow prediction of the life of motor insulation materials used in hermetic motors for air-conditioning and refrigeration equipment operated with alternative refrigerant/lubricant mixtures. Phase 1 of the project, Conceptual Design of an accelerated test method and apparatus, was successfully completed in June 1993. The culmination of that effort was the concept of the Simulated Stator Unit (SSU) test. The objective of the Phase 2 limited proof-of-concept demonstration was to: answer specific engineering/design questions; design and construct an analog control sequencer and supporting apparatus; and conduct limited tests to determine the viability of the SSU test concept. This report reviews the SSU test concept, and describes the results through the conclusion of the proof-of-concept prototype tests in March 1995. The technical design issues inherent in transforming any conceptual design to working equipment have been resolved, and two test systems and controllers have been constructed. Pilot tests and three prototype tests have been completed, concluding the current phase of work. One prototype unit was tested without thermal stress loads. Twice daily insulation property measurements (IPMs) on this unit demonstrated that the insulation property measurements themselves did not degrade the SSU.

  10. Accelerated test methods for life prediction of hermetic motor insulation systems exposed to alternative refrigerant/lubricant mixtures

    NASA Astrophysics Data System (ADS)

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

    1995-04-01

    In 1992, the Air-Conditioning and Refrigeration Technology Institute, Inc. (ARTI) contracted Radian Corporation to ascertain whether an improved accelerated test method or procedure could be developed that would allow prediction of the life of motor insulation materials used in hermetic motors for air-conditioning and refrigeration equipment operated with alternative refrigerant/lubricant mixtures. Phase 1 of the project, Conceptual Design of an accelerated test method and apparatus, was successfully completed in June 1993. The culmination of that effort was the concept of the Simulated Stator Unit (SSU) test. The objective of the Phase 2 limited proof-of-concept demonstration was to: answer specific engineering/design questions; design and construct an analog control sequencer and supporting apparatus; and conduct limited tests to determine the viability of the SSU test concept. This report reviews the SSU test concept, and describes the results through the conclusion of the proof-of-concept prototype tests in March 1995. The technical design issues inherent in transforming any conceptual design to working equipment have been resolved, and two test systems and controllers have been constructed. Pilot tests and three prototype tests have been completed, concluding the current phase of work. One prototype unit was tested without thermal stress loads. Twice daily insulation property measurements (IPM's) on this unit demonstrated that the insulation property measurements themselves did not degrade the SSU.

  11. Experimental test of photonic entanglement in accelerated reference frames

    PubMed Central

    Fink, Matthias; Rodriguez-Aramendia, Ana; Handsteiner, Johannes; Ziarkash, Abdul; Steinlechner, Fabian; Scheidl, Thomas; Fuentes, Ivette; Pienaar, Jacques; Ralph, Timothy C.; Ursin, Rupert

    2017-01-01

    The unification of the theory of relativity and quantum mechanics is a long-standing challenge in contemporary physics. Experimental techniques in quantum optics have only recently reached the maturity required for the investigation of quantum systems under the influence of non-inertial motion, such as being held at rest in gravitational fields, or subjected to uniform accelerations. Here, we report on experiments in which a genuine quantum state of an entangled photon pair is exposed to a series of different accelerations. We measure an entanglement witness for g-values ranging from 30 mg to up to 30 g—under free-fall as well on a spinning centrifuge—and have thus derived an upper bound on the effects of uniform acceleration on photonic entanglement. PMID:28489082

  12. Experimental test of photonic entanglement in accelerated reference frames

    NASA Astrophysics Data System (ADS)

    Fink, Matthias; Rodriguez-Aramendia, Ana; Handsteiner, Johannes; Ziarkash, Abdul; Steinlechner, Fabian; Scheidl, Thomas; Fuentes, Ivette; Pienaar, Jacques; Ralph, Timothy C.; Ursin, Rupert

    2017-05-01

    The unification of the theory of relativity and quantum mechanics is a long-standing challenge in contemporary physics. Experimental techniques in quantum optics have only recently reached the maturity required for the investigation of quantum systems under the influence of non-inertial motion, such as being held at rest in gravitational fields, or subjected to uniform accelerations. Here, we report on experiments in which a genuine quantum state of an entangled photon pair is exposed to a series of different accelerations. We measure an entanglement witness for g-values ranging from 30 mg to up to 30 g--under free-fall as well on a spinning centrifuge--and have thus derived an upper bound on the effects of uniform acceleration on photonic entanglement.

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

    SciTech Connect

    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.

  14. Sorafenib suppresses growth and survival of hepatoma cells by accelerating degradation of enhancer of zeste homolog 2.

    PubMed

    Wang, Shanshan; Zhu, Yu; He, Hongyong; Liu, Jing; Xu, Le; Zhang, Heng; Liu, Haiou; Liu, Weisi; Liu, Yidong; Pan, Deng; Chen, Lin; Wu, Qian; Xu, Jiejie; Gu, Jianxin

    2013-06-01

    Enhancer of zeste homolog 2 (EZH2) is a mammalian histone methyltransferase that contributes to the epigenetic silencing of target genes that regulate cancer cell growth and survival. It is overexpressed in hepatocellular carcinoma (HCC) with a clinical significance that remains obscure. Sorafenib, a multikinase inhibitor, has been used as a first-line therapeutic drug and shown clinical efficiency for advanced-stage HCC patients. In the present study, we found that sorafenib lowered the protein level of EZH2 through accelerating proteasome-mediated EZH2 degradation in hepatoma cells. Overexpression of EZH2 reversed sorafenib-induced cell growth arrest, cell cycle arrest, and cell apoptosis dependent on histone methyltransferase activity in hepatoma cells. More importantly, shRNA-mediated EZH2 knockdown or EZH2 inhibition with 3-deazaneplanocin A treatment promoted sorafenib-induced hepatoma cell growth arrest and apoptosis. Sorafenib altered the hepatoma epigenome by reducing EZH2 and H3K27 trimethylation. These results revealed a novel therapeutic mechanism underlying sorafenib treatment in suppressing hepatoma growth and survival by accelerating EZH2 degradation. Genetic deletion or pharmacological ablation of EZH2 made hepatoma cells more sensitive to sorafenib, which helps provide a strong framework for exploring innovative combined therapies for advanced-stage HCC patients.

  15. Mechanical degradation of fuel cell membranes under fatigue fracture tests

    NASA Astrophysics Data System (ADS)

    Khorasany, Ramin M. H.; Sadeghi Alavijeh, Alireza; Kjeang, Erik; Wang, G. G.; Rajapakse, R. K. N. D.

    2015-01-01

    The effects of cyclic stresses on the fatigue and mechanical stability of perfluorosulfonic acid (PFSA) membranes are experimentally investigated under standard fuel cell conditions. The experiments are conducted ex-situ by subjecting membrane specimens to cyclic uniaxial tension at controlled temperature and relative humidity. The fatigue lifetime is measured in terms of the number of cycles until ultimate fracture. The results indicate that the membrane fatigue lifetime is a strong function of the applied stress, temperature, and relative humidity. The fatigue life increases exponentially with reduced stresses in all cases. The effect of temperature is found to be more significant than that of humidity, with reduced fatigue life at high temperatures. The maximum membrane strain at fracture is determined to decrease exponentially with increasing membrane lifetime. At a given fatigue life, a membrane exposed to fuel cell conditions is shown to accommodate more plastic strain before fracture than one exposed to room conditions. Overall, the proposed ex-situ membrane fatigue experiment can be utilized to benchmark the fatigue lifetime of new materials in a fraction of the time and cost associated with conventional in-situ accelerated stress testing methods.

  16. Strontium exerts dual effects on calcium phosphate cement: Accelerating the degradation and enhancing the osteoconductivity both in vitro and in vivo.

    PubMed

    Kuang, Guan-Ming; Yau, W P; Wu, Jun; Yeung, Kelvin W K; Pan, Haobo; Lam, W M; Lu, W W; Chiu, K Y

    2015-05-01

    Calcium phosphate cements (CPCs) have long been used as osteoconductive bone substitutes in the treatment of bone defects. However, the degradation rate of CPC is typically too slow to match the new bone growth rate. It is known that strontium increases the solubility of hydroxyapatite as well as exerts both anabolic and anticatabolic effects on bone. Therefore, we hypothesized that the incorporation of strontium would accelerate the degradation rate and enhance the osteoconductivity of CPC. In this study, Three groups, CPC (0% Sr-CPC), 5% Sr-CPC, and 10% Sr-CPC, were prepared, with the total molar ratio for Sr/(Sr+Ca) in the cement powder phase being 0, 5, and 10%, respectively. In the immersion test, less residual weight was observed in both 5% Sr-CPC and 10% Sr-CPC groups than CPC group. In addition, a higher osteoblastic cell proliferation rate and alkaline phosphatase activity were obtained in the strontium groups. In a rat femur bone defect model comparing CPC with 10% Sr-CPC, at 2 weeks postoperation, early endochondral ossification was found in the 10% Sr-CPC group, whereas only fibrous tissue was observed in control group; at 4-16 weeks postoperation, progressive osteoconduction toward the cement was observed in both groups. At 32 weeks, a higher peri-cement bone area and reduced cement area were noted in the 10% Sr-CPC group. In conclusion, in the 10% Sr-CPC group, strontium exerts dual effects on CPC: accelerating degradation rate and enhancing osteoconductivity, as shown here both in vitro and in vivo.

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

    Treesearch

    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...

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  1. Development of an Accelerated Methodology to Study Degradation of Materials in Supercritical Water for Application in High Temperature Power Plants

    NASA Astrophysics Data System (ADS)

    Rodriguez, David

    The decreasing supply of fossil fuel sources, coupled with the increasing concentration of green house gases has placed enormous pressure to maximize the efficiency of power generation. Increasing the outlet temperature of these power plants will result in an increase in operating efficiency. By employing supercritical water as the coolant in thermal power plants (nuclear reactors and coal power plants), the plant efficiency can be increased to 50%, compared to traditional reactors which currently operate at 33%. The goal of this dissertation is to establish techniques to characterize the mechanical properties and corrosion behavior of materials exposed to supercritical water. Traditionally, these tests have been long term exposure tests spanning months. The specific goal of this dissertation is to develop a methodology for accelerated estimation of corrosion rates in supercritical water that can be sued as a screening tool to select materials for long term testing. In this study, traditional methods were used to understand the degradation of materials in supercritical water and establish a point of comparison to the first electrochemical studies performed in supercritical water. Materials studied included austenitic steels (stainless steel 304, stainless steel 316 and Nitronic 50) and nickel based alloys (Inconel 625 and 718). Surface chemistry of the oxide layer was characterized using scanning electron microscopy, X-ray diffraction, FT-IR, Raman and X-ray photoelectron spectroscopies. Stainless steel 304 was subjected to constant tensile load creep tests in water at a pressure of 27 MPa and at temperatures of 200 °C, 315 °C and supercritical water at 450 °C for 24 hours. It was determined that the creep rate for stainless steel 304 exposed to supercritical water would be unacceptable for use in service. It was observed that the formation of hematite was favored in subcritical temperatures, while magnetite was formed in the supercritical region. Corrosion of

  2. Accelerator Stewardship Test Facility Program - Elliptical Twin Cavity for Accelerator Applications

    SciTech Connect

    Hutton, Andrew; Areti, Hari

    2015-08-01

    Funding is being requested pursuant to the proposals entitled Elliptical Twin Cavity for Accelerator Applications that was submitted and reviewed through the Portfolio Analysis and Management System (PAMS). The PAMS proposal identifier number is 0000219731. The proposed new type of superconducting cavity, the Elliptical Twin Cavity, is capable of accelerating or decelerating beams in two separate beam pipes. This configuration is particularly effective for high-current, low energy electron beams that will be used for bunched beam cooling of high-energy protons or ions. Having the accelerated beam physically separated from the decelerated beam, but interacting with the same RF mode, means that the low energy beam from the gun can be injected into to the superconducting cavity without bends enabling a small beam emittance to be maintained. A staff engineer who has been working with non-standard complicated cavity structures replaces the senior engineer (in the original budget) who is moving on to be a project leader. This is reflected in a slightly increased engineer time and in reduced costs. The Indirect costs for FY16 are lower than the previous projection. As a result, there is no scope reduction.

  3. The role of animal seed dispersal in accelerating native forest regeneration on degraded tropical lands.

    Treesearch

    J.M. Wunderle Jr.

    1997-01-01

    this paper reviews the characteristicas of animal seed dispersal. relevant to tropical forest restoration efforts and discusses their managment implication. In many tropical regions seed dispersal by animals is the predominant form of dissemination of propagules and has a potential to facilitate recolonization of native vegetation on degraded sites.

  4. Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation.

    PubMed

    Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui

    2015-08-15

    Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89-94% of the electrons released from benzoate oxidation were recovered in CH4 production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.

  5. Potential Application of Magnetohydrodynamic Acceleration to Hypersonic Environmental Testing

    DTIC Science & Technology

    1990-08-01

    homopolar generators, and compulsators should be evaluated along with solid-state converters. 86 AEDC-TR-90-6 B.4.2 Design Study of Control and...heater as a source of hot air for accelerator research. One could consider using motor generator power supplies for the arc heater as d3ne tor the

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

    SciTech Connect

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

    2012-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Frickland, P. O.; Repar, J.

    1982-01-01

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

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

    SciTech Connect

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

    2012-05-10

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

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

    SciTech Connect

    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.

  10. Accelerated degradation of methylammonium lead iodide perovskites induced by exposure to iodine vapour

    NASA Astrophysics Data System (ADS)

    Wang, Shenghao; Jiang, Yan; Juarez-Perez, Emilio J.; Ono, Luis K.; Qi, Yabing

    2017-01-01

    Efficiencies of organic-inorganic lead halide perovskite solar cells (PSCs) have significantly increased in recent years, but instability issues impede their further development and application. Previous studies reported that volatile species (for example, iodine, I2) were generated when perovskites were subjected to moisture, oxygen, light illumination, applied electric field, and thermal stress (all of which are relevant to the operation of PSCs in practical applications). Here we show that I2 vapour causes severe degradation of MAPbI3 (MA: CH3NH3+) perovskite, due to chemical chain reactions. Furthermore, I2 vapour could also induce degradation of other iodide-based perovskites, such as FAPbI3 (FA: HC(NH2)2+) and FA0.8Cs0.2PbI3. The results reveal a universal degradation factor for iodide-based perovskite by I2. As the release of I2 is nearly inevitable during practical applications, this work suggests that MAPbI3 may not be suitable for long-term stable solar cells and it is imperative to develop other types of perovskite material to achieve stable PSCs.

  11. Applications of the ram accelerator to hypervelocity aerothermodynamic testing

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  12. Applications of the ram accelerator to hypervelocity aerothermodynamic testing

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  13. Testing changes: the next step in accelerating excellence.

    PubMed

    Coutts, Jane

    2011-01-01

    Saskatchewan's Health Quality Council (HQC) was launched in 2003 with a mandate not only to measure and report on healthcare but also work with a range of partners to improve the province's health system. In late 2007, HQC's board decided it was time for Saskatchewan to reinvent its healthcare system, using the highest-performing systems in the world as its model. And in 2008, HQC launched Accelerating Excellence, a multi-level program to rethink, redesign and renew healthcare.

  14. Insig-mediated, sterol-accelerated degradation of the membrane domain of hamster 3-hydroxy-3-methylglutaryl-coenzyme A reductase in insect cells.

    PubMed

    Nguyen, Andrew D; Lee, Soo Hee; DeBose-Boyd, Russell A

    2009-09-25

    Sterol-accelerated degradation of the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase is one of several mechanisms through which cholesterol synthesis is controlled in mammalian cells. This degradation results from sterol-induced binding of the membrane domain of reductase to endoplasmic reticulum membrane proteins called Insig-1 and Insig-2, which are carriers of a ubiquitin ligase called gp78. The ensuing gp78-mediated ubiquitination of reductase is a prerequisite for its rapid, 26 S proteasome-mediated degradation from endoplasmic reticulum membranes, a reaction that slows a rate-limiting step in cholesterol synthesis. Here, we report that the membrane domain of hamster reductase is subject to sterol-accelerated degradation in Drosophila S2 cells, but only when mammalian Insig-1 or Insig-2 are co-expressed. This degradation mimics the reaction that occurs in mammalian cells with regard to its absolute requirement for the action of Insigs, sensitivity to proteasome inhibition, augmentation by nonsterol isoprenoids, and sterol specificity. RNA interference studies reveal that this degradation requires the Drosophila Hrd1 ubiquitin ligase and several other proteins, including a putative substrate selector, which associate with the enzyme in yeast and mammalian systems. These studies define Insigs as the minimal requirement for sterol-accelerated degradation of the membrane domain of reductase in Drosophila S2 cells.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed Central

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

    2013-01-01

    The physical and chemical degradation of drugs may result in altered therapeutic efficacy and even toxic effects. Therefore, the objective of this work was to study the stability of clobetasol propionate (CP) in a nanoemulsion. The nanoemulsion formulation containing CP was prepared by the spontaneous emulsification method. For the formulation of the nanoemulsion, Safsol, Tween 20, ethanol, and distilled water were used. The drug was incorporated into an oil phase in 0.05% w/v. The lipophilic nature of the drug led to the O/W nanoemulsion formulation. This was characterized by droplet size, pH, viscosity, conductivity, and refractive index. Stability studies were performed as per ICH guidelines for a period of three months. The shelf life of the nanoemulsion formulation was also determined after performing accelerated stability testing (40°C ± 2°C and 75% ± 5% RH). We also performed an intermediate stability study (30°C ± 2°C/65% RH ± 5% RH). It was found that the droplet size, conductivity, and refractive index were slightly increased, while the viscosity and pH slightly decreased at all storage conditions during the 3-month period. However, the changes in these parameters were not statistically significant (p≥0.05). The degradation (%) of the optimized nanoemulsion of CP was determined and the shelf life was found to be 2.18 years at room temperature. These studies confirmed that the physical and chemical stability of CP were enhanced in the nanoemulsion formulation. PMID:24482775

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

    PubMed

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

    2013-01-01

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

  18. Ex-situ tensile fatigue-creep testing: A powerful tool to simulate in-situ mechanical degradation in fuel cells

    NASA Astrophysics Data System (ADS)

    Sadeghi Alavijeh, A.; Venkatesan, S. V.; Khorasany, R. M. H.; Kim, W. H. J.; Kjeang, E.

    2016-04-01

    An ex-situ tensile fatigue and creep based accelerated stress test (TFC-AST) is proposed to evaluate the mechanical stability of catalyst coated membranes (CCMs) used in fuel cells. The fatigue-creep action of the TFC test is analyzed by tensile and hygrothermal expansion measurements on partially degraded specimens supplemented by microstructural characterization using transmission electron microscopy, revealing significant decay in mechanical properties as well as morphological rearrangement due to the combined fatigue and creep loading. Through comparison with in-situ hygrothermally degraded CCMs, the TFC-AST protocol is demonstrated to be an economical alternative to the costly in-situ mechanical accelerated stress tests that can reduce the test duration by more than 99%.

  19. Design, fabrication and first beam tests of the C-band RF acceleration unit at SINAP

    NASA Astrophysics Data System (ADS)

    Fang, Wencheng; Gu, Qiang; Sheng, Xing; Wang, Chaopeng; Tong, Dechun; Chen, Lifang; Zhong, Shaopeng; Tan, Jianhao; Lin, Guoqiang; Chen, Zhihao; Zhao, Zhentang

    2016-07-01

    C-band RF acceleration is a crucial technology for the compact Free Electron Laser (FEL) facility at the Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences. A project focusing on C-band RF acceleration technology was launched in 2008, based on high-gradient accelerating structures powered by klystron and pulse compressor units. The target accelerating gradient is 40 MV/m or higher. Recently one prototype of C-band RF unit, consisting of a 1.8 m accelerating structure and a klystron with a TE0115 mode pulse compressor, has been tested with high-power and electron beam. Stable operation at 40 MV/m was demonstrated and, 50 MV/m approached by the end of the test. This paper introduces the C-band R&D program at SINAP and presents the experiment results of high-power and beam tests.

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

    SciTech Connect

    Loewen, Rod

    2000-03-30

    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.

  1. Development of a 20 MeV Dielectric-Loaded Test Accelerator

    SciTech Connect

    Gold, S.H.; Kinkead, A.K.; Gai, W.; Power, J.G.; Konecny, R.; Jing, C.; Long, J.; Tantawi, S.G.; Nantista, C.D.; Fliflet, A.W.; Lombardi, M.; Lewis, D.; Bruce, R.W.; /Unlisted

    2007-04-13

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

  2. Testing Cosmic-Ray Acceleration in Young, Embedded Stellar Clusters

    NASA Astrophysics Data System (ADS)

    Nukri, Komin; Marcowith, Alexandre; Lamanna, Giovanni; Maurin, Gilles; Krayzel, Fabien

    2016-07-01

    Most of the massive stars appear grouped in clusters located in giant molecular clouds. Their strong wind activity generates large structures known as stellar wind bubbles and induces collective effects which could accelerate particles up to high energy and produce gamma-rays. The best objects to observe these effects are young massive star clusters in which no supernova explosion has occurred yet. We model these star clusters as a spherical leaky box (the molecular cloud) surrounding a central cosmic ray source (the stellar cluster). We developed a phenomenological model to estimate the cosmic and gamma-ray production for a set of 8 selected clusters. We compare the predicted gamma-ray emission with data obtained with the Fermi-LAT telescope. No significant emission has been detected from any of the selected cluster. Comparing the upper limit on the gamma-ray flux with the prediction from our phenomenological model indicates that not more than 10% of the stellar wind luminosity of the stellar clusters is converted into cosmic rays. If all O-type stars do not contribute more than 10% of their stellar wind luminosity to cosmic-ray acceleration they do not contribute to more than on percent of the total cosmic-ray luminosity.

  3. Accelerated and environmental module stress testing at NREL

    SciTech Connect

    Osterwald, C.R.; Basso, T.S.; del Cueto, J.A.; McMahon, T.J.; Pruett, J.; Trudell, D.

    1999-03-01

    This paper presents an overview of the Module Testing and Technology Validation task at the National Renewable Energy Laboratory. The extensive module testing capabilities at the Outdoor Test Facility are outlined, emphasizing the test facilities, equipment, and analytical services available. Highlights and results of several recent testing efforts are then presented, followed by a list of the external programs supported by the task. The paper concludes with a brief description of the new testing programs that are planned for the near future. {copyright} {ital 1999 American Institute of Physics.}

  4. Degradation Testing of Fluorotelomer-based polymers (FTPs)

    EPA Science Inventory

    Over the last decade, concern about sources of per and polyfluorochemicals (PFCs) have led to an increasing need for information on the microbial and/or abiotic degradation of polymer materials that contain PFC structural fragments that may be released. EPA, OECD, ASTM and other...

  5. Degradation Testing of Fluorotelomer-based polymers (FTPs)

    EPA Science Inventory

    Over the last decade, concern about sources of per and polyfluorochemicals (PFCs) have led to an increasing need for information on the microbial and/or abiotic degradation of polymer materials that contain PFC structural fragments that may be released. EPA, OECD, ASTM and other...

  6. Life testing of low-voltage air circuit breaker to assess age-related degradation

    SciTech Connect

    Subudhi, M. )

    1992-03-01

    This paper reports that a DS-416 low-voltage air circuit breaker manufactured by Westinghouse is mechanically cycled to identify age-related degradation in the various breaker subcomponents, specifically in the power-operated mechanism. This accelerated aging test is performed on one breaker unit for over 36 000 cycles. Three separate pole shafts, one with a 60-deg weld, one with a 120-deg weld, and one with a 180-deg weld in the third pole lever, are used to characterize cracking in the welds. In addition, during the testing, three different operating mechanisms and several other parts are replaced as they become inoperable. Among the seven welds on the pole shaft, welds 1 and 3 are found to be critical ones whose fracture can result in misalignment of the pole levers. This can lead to problems with the operating mechanism, including the burning of coils, excessive wear in certain parts, and overstressed linkages. Furthermore, the limiting service life of a number of subcomponents of the power-operated mechanism, including the operating mechanism itself, is assessed.

  7. A test and instrumentation system for the investigation of degradation of electrical insulating materials

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The basic test methods of aging and deterioration mechanisms of electrical insulating materials are discussed. A comprehensive test system developed to study the degradation process is described. This system is completely checked, and calibrated with a few insulating material samples.

  8. History of Accelerated and Qualification Testing of Terrestrial Photovoltaic Modules: A Literature Review

    SciTech Connect

    Osterwald, C. R.; McMahon, T. J.

    2009-01-01

    We review published literature from 1975 to the present for accelerated stress testing of flat-plate terrestrial photovoltaic (PV) modules. An important facet of this subject is the standard module test sequences that have been adopted by national and international standards organizations, especially those of the International Electrotechnical Commission (IEC). The intent and history of these qualification tests, provided in this review, shows that standard module qualification test results cannot be used to obtain or infer a product lifetime. Closely related subjects also discussed include: other limitations of qualification testing, definitions of module lifetime, module product certification, and accelerated life testing.

  9. Testing of Composite Fan Vanes With Erosion-Resistant Coating Accelerated

    NASA Technical Reports Server (NTRS)

    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.

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

    SciTech Connect

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

    2009-01-22

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

  11. Testing Verlinde's emergent gravity with the radial acceleration relation

    NASA Astrophysics Data System (ADS)

    Lelli, Federico; McGaugh, Stacy S.; Schombert, James M.

    2017-06-01

    It has recently been proposed that space-time and gravity may emerge from an underlying microscopic theory. In a de Sitter space-time, such emergent gravity (EG) contains an additional gravitational force due to dark energy, which may explain the mass discrepancies observed in galactic systems without the need of dark matter. For a point mass, EG is equivalent to Modified Newtonian Dynamics (MOND). We show that this equivalence does not hold for finite-size galaxies: There are significant differences between EG and MOND in the inner regions of galaxies. We confront theoretical predictions with the empirical radial acceleration relation (RAR). We find that (i) EG is consistent with the observed RAR only if we substantially decrease the fiducial stellar mass-to-light ratios; the resulting values are in tension with other astronomical estimates; (ii) EG predicts that the residuals around the RAR should correlate with radius; such residual correlation is not observed.

  12. 4-Hydroxynonenal differentially regulates adiponectin gene expression and secretion via activating PPARγ and accelerating ubiquitin–proteasome degradation

    PubMed Central

    Wanga, Zhigang; Dou, Xiaobing; Gu, Dongfang; Shen, Chen; Yao, Tong; Nguyen, Van; Braunschweig, Carol; Song, Zhenyuan

    2011-01-01

    Although well-established, the underlying mechanisms involved in obesity-related plasma adiponectin decline remain elusive. Oxidative stress is associated with obesity and insulin resistance and considered to contribute to the progression toward obesity-related metabolic disorders. In this study, we investigated the effects of 4-hydroxynonenal (4-HNE), the most abundant lipid peroxidation end product, on adiponectin production and its potential implication in obesity-related adiponectin decrease. Long-term high-fat diet feeding led to obesity in mouse, accompanied by decreased plasma adiponectin and increased adipose tissue 4-HNE content. Exposure of adipocytes to exogenous 4-HNE resulted in decreased adiponectin secretion in a dose-dependent manner, which was consistent with significantly decreased intracellular adiponectin protein abundance. In contrast, adiponectin gene expression was significantly elevated by 4-HNE treatment, which was concomitant with increased peroxisome proliferator-activated receptor gamma (PPAR-γ) gene expression and transactivity. The effect was abolished by T0070907, a PPAR-γ antagonist, suggesting that PPAR-γ activation plays a critical role in this process. To gain insight into mechanisms involved in adiponectin protein decrease, we examined the effects of 4-HNE on adiponectin protein degradation. Cycloheximide (CHX)-chase assay revealed that 4-HNE exposure accelerated adiponectin protein degradation, which was prevented by MG132, a potent proteasome inhibitor. Immunoprecipitation assay showed that 4-HNE exposure increased ubiquitinated adiponectin protein levels. These data altogether indicated that 4-HNE enhanced adiponectin protein degradation via ubiquitin–proteasome system. Finally, we demonstrated that supplementation of HF diet with betaine, an antioxidant and methyl donor, alleviated high-fat-induced adipose tissue 4-HNE increase and attenuated plasma adiponectin decline. Taken together, our findings suggest that the lipid

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

    PubMed

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

    2012-10-19

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

  14. Degradation testing of Mg alloys in Dulbecco's modified eagle medium: Influence of medium sterilization.

    PubMed

    Marco, Iñigo; Feyerabend, Frank; Willumeit-Römer, Regine; Van der Biest, Omer

    2016-05-01

    This work studies the in vitro degradation of Mg alloys for bioabsorbable implant applications under near physiological conditions. For this purpose, the degradation behaviour of Mg alloys in Dulbecco's modified eagle medium (DMEM) which is a commonly used cell culture medium is analysed. Unfortunately, DMEM can be contaminated by microorganisms, acidifying the medium and accelerating the Mg degradation process by dissolution of protective degradation layers, such as (Mgx,Cay)(PO4)z. In this paper the influence of sterilization by applying UV-C radiation and antibiotics (penicillin/streptomycin) is analysed with two implant material candidates: Mg-Gd and Mg-Ag alloys; and pure magnesium as well as Mg-4Y-3RE as a reference.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  17. Acceleration test of TIT-IHQ linac for heavy ion irradiation

    NASA Astrophysics Data System (ADS)

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

    2000-03-01

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

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

    SciTech Connect

    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.

  19. Methodology for the design of accelerated stress tests for non-precious metal catalysts in fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Sharabi, Ronit; Wijsboom, Yair Haim; Borchtchoukova, Nino; Finkelshtain, Gennadi; Elbaz, Lior

    2016-12-01

    In this work we propose systematic methods for testing non-precious group metal catalysts and support degradation alkaline fuel cell cathodes. In this case study, we used a cathode composed of a pyrolyzed non-precious metal catalyst (NPMC) on activated carbon. The vulnerabilities of the cathode components were studied in order to develop the methodology and design an accelerated stress test (AST) for NPMC-based cathode in alkaline environment. Cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) were used to characterize the electrochemical behavior of the cathode and to follow the changes that occur as a result of exposing the cathodes to extreme operating conditions. Rotating ring disk electrode (RRDE) was used to study the cathodes kinetics; Raman spectroscopy and X-ray fluorescence (XRF) were used to study the structural changes in the electrode surface as well as depletion of the catalysts' active sites from the electrode. The changes in the composition of the electrode and catalyst were detected using X-ray diffraction (XRD). For the first time, we show that NPMC degrade rapidly at low operating potentials whereas the support degrades at high operating potentials and developed a tailor-made AST to take these into account.

  20. Accelerated thermal and mechanical testing of CSP assemblies

    NASA Technical Reports Server (NTRS)

    Ghaffarian, R.

    2000-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Chang, Kurng Y.; Scharton, Terry D.

    1996-01-01

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

  2. Calibration of rotational acceleration for the rotarod test of rodent motor coordination.

    PubMed

    Bohlen, Martin; Cameron, Andy; Metten, Pamela; Crabbe, John C; Wahlsten, Douglas

    2009-03-30

    The latency of mice and rats to fall from the accelerating rotarod can differ markedly between laboratories using the same brand of rod as well as between studies using different kinds of rods. These discrepancies can arise from different rod diameters, surface textures, test protocols, or laboratory environmental factors beyond the test itself, but it is also possible that the actual acceleration rates of the different rods do not correspond to the nominal rates set on the devices. This paper describes a simple method to measure acceleration rate of the rotarod and to set the rate to a desired value for any brand of rod.

  3. Contribution of Accelerated Degradation to Feedback Regulation of 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase and Cholesterol Metabolism in the Liver.

    PubMed

    Hwang, Seonghwan; Hartman, Isamu Z; Calhoun, Leona N; Garland, Kristina; Young, Gennipher A; Mitsche, Matthew A; McDonald, Jeffrey; Xu, Fang; Engelking, Luke; DeBose-Boyd, Russell A

    2016-06-24

    Accumulation of sterols in endoplasmic reticulum membranes stimulates the ubiquitination of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), which catalyzes a rate-limiting step in synthesis of cholesterol. This ubiquitination marks HMGCR for proteasome-mediated degradation and constitutes one of several mechanisms for feedback control of cholesterol synthesis. Mechanisms for sterol-accelerated ubiquitination and degradation of HMGCR have been elucidated through the study of cultured mammalian cells. However, the extent to which these reactions modulate HMGCR and contribute to control of cholesterol metabolism in whole animals is unknown. Here, we examine transgenic mice expressing in the liver the membrane domain of HMGCR (HMGCR (TM1-8)), a region necessary and sufficient for sterol-accelerated degradation, and knock-in mice in which endogenous HMGCR harbors mutations that prevent sterol-induced ubiquitination. Characterization of transgenic mice revealed that HMGCR (TM1-8) is appropriately regulated in the liver of mice fed a high cholesterol diet or chow diet supplemented with the HMGCR inhibitor lovastatin. Ubiquitination-resistant HMGCR protein accumulates in the liver and other tissues disproportionately to its mRNA, indicating that sterol-accelerated degradation significantly contributes to feedback regulation of HMGCR in vivo Results of these studies demonstrate that HMGCR is subjected to sterol-accelerated degradation in the liver through mechanisms similar to those established in cultured cells. Moreover, these studies designate sterol-accelerated degradation of HMGCR as a potential therapeutic target for prevention of atherosclerosis and associated cardiovascular disease. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Accelerated light-induced degradation for detecting copper contamination in p-type silicon

    SciTech Connect

    Inglese, Alessandro Savin, Hele; Lindroos, Jeanette

    2015-08-03

    Copper is a harmful metal impurity that significantly impacts the performance of silicon-based devices if present in active regions. In this contribution, we propose a fast method consisting of simultaneous illumination and annealing for the detection of copper contamination in p-type silicon. Our results show that, within minutes, such method is capable of producing a significant reduction of the minority carrier lifetime. A spatial distribution map of copper contamination can then be obtained through the lifetime values measured before and after degradation. In order to separate the effect of the light-activated copper defects from the other metastable complexes in low resistivity Cz-silicon, we carried out a dark anneal at 200 °C, which is known to fully recover the boron-oxygen defect. Similar to the boron-oxygen behavior, we show that the dark anneal also recovers the copper defects. However, the recovery is only partial and it can be used to identify the possible presence of copper contamination.

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

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Rogers, Paul; Hoff, Craig

    2000-01-01

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

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

    SciTech Connect

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

    2012-05-01

    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.

  7. 78 FR 76410 - Request for Information on Strategies To Accelerate the Testing and Adoption of Pay for Success...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-17

    ... Request for Information on Strategies To Accelerate the Testing and Adoption of Pay for Success (PFS... period on its request for information on Strategies to Accelerate the Testing and Adoption of Pay for... Strategies to Accelerate the Testing and Adoption of Pay for Success (PFS) Financing Models (78 FR 60998...

  8. Systemic response to thermal injury in rats. Accelerated protein degradation and altered glucose utilization in muscle.

    PubMed Central

    Clark, A S; Kelly, R A; Mitch, W E

    1984-01-01

    Negative nitrogen balance and increased oxygen consumption after thermal injury in humans and experimental animals is related to the extent of the burn. To determine whether defective muscle metabolism is restricted to the region of injury, we studied protein and glucose metabolism in forelimb muscles of rats 48 h after a scalding injury of their hindquarters. This injury increased muscle protein degradation (PD) from 140 +/- 5 to 225 +/- 5 nmol tyrosine/g per h, but did not alter protein synthesis. Muscle lactate release was increased greater than 70%, even though plasma catecholamines and muscle cyclic AMP were not increased. Insulin dose-response studies revealed that the burn decreased the responsiveness of muscle glycogen synthesis to insulin but did not alter its sensitivity to insulin. Rates of net glycolysis and glucose oxidation were increased and substrate cycling of fructose-6-phosphate was decreased at all levels of insulin. The burn-induced increase in protein and glucose catabolism was not mediated by adrenal hormones, since they persisted despite adrenalectomy. Muscle PGE2 production was not increased by the burn and inhibition of prostaglandin synthesis by indomethacin did not inhibit proteolysis. The increase in PD required lysosomal proteolysis, since inhibition of cathepsin B with EP475 reduced PD. Insulin reduced PD 20% and the effects of EP475 and insulin were additive, reducing PD 41%. An inhibitor of muscle PD, alpha-ketoisocaproate, reduced burn-induced proteolysis 28% and lactate release 56%. The rate of PD in muscle of burned and unburned rats was correlated with the percentage of glucose uptake that was directed into lactate production (r = +0.82, P less than 0.01). Thus, a major thermal injury causes hypercatabolism of protein and glucose in muscle that is distant from the injury, and these responses may be linked to a single metabolic defect. PMID:6470144

  9. Status and Plans for an SRF Accelerator Test Facility at Fermilab

    SciTech Connect

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

    2011-07-29

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

  10. Safety of a rapid diagnostic protocol with accelerated stress testing.

    PubMed

    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.

  11. Development and testing of the improved focusing quadrupole for heavy ion fusion accelerators

    SciTech Connect

    Manahan, R R; Martovetsky, N N; Meinke, R B; Chiesa, L; Lietzke, A F; Sabbi, G L; Seidl, P A

    2003-10-23

    An improved version of the focusing magnet for a Heavy Ion Fusion (HIF) accelerator was designed, built and tested in 2002-2003. This quadrupole has higher focusing power and lower error field than the previous version of the focusing quadrupoles successfully built and tested in 2001. We discuss the features of the new design, selected fabrication issues and test results.

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

    ERIC Educational Resources Information Center

    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…

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  14. NWSC nickel cadmium spacecraft cell accelerated life test program data analysis

    NASA Technical Reports Server (NTRS)

    Lander, J.

    1980-01-01

    An analysis of the data leading to a proposed accelerated life test scheme to test a nickel cadmium cell under spacecraft usage conditions is described. The amount and concentration of electrolyte and the amount of precharge in the cell are discussed in relation to the design of the cell and the accelerated test design. A failure analysis of the cell is summarized. The analysis included such environmental test variables as the depth of discharge, the temperature, the amount of recharge and the charge and discharge rate.

  15. Accelerated life testing effects on CMOS microcircuit characteristics

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Modifications and additions to the present process of making CMOS microcircuits which are designed to provide protective layers on the chip to guard against moisture and contaminants were investigated. High and low temperature Si3N4 protective layers were tested on the CMOS microcircuits and no conclusive improvements in device reliability characteristics were evidenced.

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

    PubMed

    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.

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

    PubMed Central

    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

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed

    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

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    SciTech Connect

    Anamkath, H.; Lyons, S.; Nett, D.; Treas, P.; Whitham, K.; Zante, T.; Miller, R.; 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.

  2. Composite Unit Accelerated Life Test of the High Gain Array

    DTIC Science & Technology

    1993-01-08

    computed using a classic Arrhenius relation and a 13.3 kcal/ mole activation energy. This value corresponds to a nominal activation energy for the...UNDERWATER COMPOENTS RELIABILITY TESTING OF LONG LIFE UNDERWATER COMPONENTS Alan V. Bray and Shawn L Arnett Texas Research Institute Austin, Inc. 9063...Austin, Inc. (TRI/Austin) Reliability Engineering Division A.V. Bray, S.L. Arnett, and S.C. Liberty 9063 Bee Caves Road Austin, Texas 78733 (512) 263

  3. Composite-Unit Accelerated Life Testing (CUALT) of Sonar Transducers

    DTIC Science & Technology

    1979-09-01

    testing were identified and corrected. 2, Resolution of the current -runaway problem on the TR-316 was largely based on the CUALT experimental and...Kinnison - Suggested the use of in-air impedance NOSC experiments on individual resonators to understand the current -runaway problem. Homer Ding...2-1 2.2 Use of Current -Buy Transducers .................... 2-2 2.3 Use of Both Projector and Receiver Transducers .... 2-2 2.4 Hands-on ALT

  4. Isolation of a piezoresistive accelerometer used in high acceleration tests

    NASA Astrophysics Data System (ADS)

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

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

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

    SciTech Connect

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

    1999-01-01

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

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

    SciTech Connect

    Spataro, B.; Alesini, D.; Chimenti, V.; Dolgashev, V.; Haase, A.; Tantawi, S.G.; Higashi, Y.; Marrelli, C.; Mostacci, A.; Parodi, R.; Yeremian, A.D.; /SLAC

    2012-04-24

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

  7. Technological issues and high gradient test results on X-band molybdenum accelerating structures

    NASA Astrophysics Data System (ADS)

    Spataro, B.; Alesini, D.; Chimenti, V.; Dolgashev, V.; Haase, A.; Tantawi, S. G.; Higashi, Y.; Marrelli, C.; Mostacci, A.; Parodi, R.; Yeremian, A. D.

    2011-11-01

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

  8. Isolation of a piezoresistive accelerometer used in high acceleration tests

    SciTech Connect

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

    1992-12-31

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

  9. Testing Modules for Potential-Induced Degradation - A Status Update of IEC 62804 (Presentation)

    SciTech Connect

    Hacke, P.

    2014-03-01

    Stresses and degradation rates for the 25 degrees C with foil and the 60 degrees C/85% RH damp heat tests are compared, the Illumination factor on PID rate is evaluated, and measurement techniques and stress levels are discussed.

  10. ACCELERATORS Control system for the CSNS ion source test stand

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  11. An accelerated exposure and testing apparatus for building joint sealants

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  12. Considerations for a Standardized Test for Potential-Induced Degradation of Crystalline Silicon PV Modules (Presentation)

    SciTech Connect

    Hacke, P.

    2012-03-01

    Over the past decade, there have been observations of module degradation and power loss because of the stress that system voltage bias exerts. This results in part from qualification tests and standards note adequately evaluating for the durability of modules to the long-term effects of high voltage bias that they experience in fielded arrays. This talk deals with factors for consideration, progress, and information still needed for a standardized test for degradation due to system voltage stress.

  13. Low-acceleration dwarf galaxies as tests of quantised inertia

    NASA Astrophysics Data System (ADS)

    McCulloch, M. E.

    2017-03-01

    Dwarf satellite galaxies of the Milky Way appear to be gravitationally bound, but their stars' orbital motion seems too fast to allow this given their visible mass. This is akin to the larger-scale galaxy rotation problem. In this paper, a modification of inertia called quantised inertia or MiHsC (Modified inertia due to a Hubble-scale Casimir effect) which correctly predicts larger galaxy rotations without dark matter is tested on eleven dwarf satellite galaxies of the Milky Way, for which mass and velocity data are available. Quantised inertia slightly outperforms MoND (Modified Newtonian Dynamics) in predicting the velocity dispersion of these systems, and has the fundamental advantage over MoND that it does not need an adjustable parameter.

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

    ERIC Educational Resources Information Center

    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…

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    SciTech Connect

    J. Francfort; J. Argueta; M. Wehrey; D. Karner; L. Tyree

    1999-07-01

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

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

    SciTech Connect

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

    2014-01-29

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

  19. Accelerated lifetime test of vibration isolator made of Metal Rubber material

    NASA Astrophysics Data System (ADS)

    Ao, Hongrui; Ma, Yong; Wang, Xianbiao; Chen, Jianye; Jiang, Hongyuan

    2017-01-01

    The Metal Rubber material (MR) is a kind of material with nonlinear damping characteristics for its application in the field of aerospace, petrochemical industry and so on. The study on the lifetime of MR material is impendent to its application in engineering. Based on the dynamic characteristic of MR, the accelerated lifetime experiments of vibration isolators made of MR working under random vibration load were conducted. The effects of structural parameters of MR components on the lifetime of isolators were studied and modelled with the fitting curves of degradation data. The lifetime prediction methods were proposed based on the models.

  20. 3.9 GHz superconducting accelerating 9-cell cavity vertical test results

    SciTech Connect

    Khabiboulline, Timergali; Cooper, Charles; Dhanaraj, Nandhini; Edwards, Helen; Foley, Mike; Harms, Elvin; Mitchell, Donald; Rowe, Allan; Solyak, Nikolay; Moeller, Wolf-Dietrich; /DESY

    2007-06-01

    The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve the beam performance of the FLASH (TTF/DESY) facility [1]. In the frame of a collaborative agreement, Fermilab will provide DESY with a cryomodule containing a string of four cavities. In addition, a second cryomodule with one cavity will be fabricated for installation in the Fermilab photo-injector, which will be upgraded for the ILC accelerator test facility. The first 9-cell Nb cavities were tested in a vertical setup and they didn't reach the designed accelerating gradient [2]. The main problem was a multipactor in the HOM couplers, which lead to overheating and quenching of the HOM couplers. New HOM couplers with improved design are integrated in the next 9-cell cavities. In this paper we present all results of the vertical tests.

  1. Anaerobic nonylphenol ethoxylate degradation coupled to nitrate reduction in a modified biodegradability batch test.

    PubMed

    Luppi, Lorena I; Hardmeier, Ivo; Babay, Paola A; Itria, Raúl F; Erijman, Leonardo

    2007-08-01

    The aim of this work was to elucidate the role of nitrate as a terminal electron acceptor on the biodegradation of NPEO. We have characterized the products of NPEO degradation by mixed microbial communities in anaerobic batch tests by means of HPLC, (1)H NMR and GC-MS. Anaerobic degradation of NPEO was strictly dependent on the presence of nitrate. Within seven days of anoxic incubation, NP2EO appeared as the major degradation product. After 21 days, NP was the main species detected, and was not degraded further even after 35 days. Nitrate concentration decreased in parallel with NPEO de-ethoxylation. A transient accumulation of nitrite was observed within the time period in which NP formation reached its maximum production. The observed generation of nonylphenol coupled to nitrate reduction suggests that the microbial consortium possessed an alternate pathway for the degradation of NPEO, which was not accessible under aerobic conditions.

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

    SciTech Connect

    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.

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

    DTIC Science & Technology

    1974-11-01

    butadiene acrylonitrile rubber bonded Sassembliesshowed a severe loes of 100 percent in bond strength; the EPDM bond.ed assemblies shcwed a 40 percent lose...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

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

    SciTech Connect

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

    2006-08-01

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

  5. UV-accelerated test based on analysis of field-exposed PV modules

    NASA Astrophysics Data System (ADS)

    Shioda, T.

    2011-09-01

    We proposed an UV accelerated test condition for an EVA encapsulant, based on analysis of long term field exposed PV modules. We found that strong UV irradiation into EVA encapsulant test sample led to the fast decomposition of UV absorber formulated in EVA encapsulant, which has never seen in the field exposed PV modules. Thus, the integrating UV intensity of 60 W/m2 and black panel temperature of 110°C using a xenon weather-o-meter were suitable as an UV accelerated test condition. With this proposed test condition, which shows that 1 week exposure by xenon light corresponds to 1 year field exposure, we can predict discoloration rate of EVA encapsulant. In addition, we evaluated change in peel strength to glass for Mitsui's and the other commercially available EVA encapsulants during UV accelerated test with the proposed condition. There was no large change in peel strength for our EVA encapsulant during the UV accelerated test. On the other hand, we observed that the competitor's EVA encapsulant showed the large decrease of peel strength to glass at early stage, even no change in yellowness index (YI). This result indicates not only YI change but also peel strength change should be evaluated for design of reliable PV module and encapsulant.

  6. Numerical Analysis of JNES Seismic Tests on Degraded Combined Piping System

    SciTech Connect

    Zhang T.; Nie J.; Brust, F.; Wilkowski, G.; Hofmayer, C.; Ali, S.; Shim, D-J.

    2012-02-02

    Nuclear power plant safety under seismic conditions is an important consideration. The piping systems may have some defects caused by fatigue, stress corrosion cracking, etc., in aged plants. These cracks may not only affect the seismic response but also grow and break through causing loss of coolant. Therefore, an evaluation method needs to be developed to predict crack growth behavior under seismic excitation. This paper describes efforts conducted to analyze and better understand a series of degraded pipe tests under seismic loading that was conducted by Japan Nuclear Energy Safety Organization (JNES). A special 'cracked-pipe element' (CPE) concept, where the element represented the global moment-rotation response due to the crack, was developed. This approach was developed to significantly simplify the dynamic finite element analysis in fracture mechanics fields. In this paper, model validation was conducted by comparisons with a series of pipe tests with circumferential through-wall and surface cracks under different excitation conditions. These analyses showed that reasonably accurate predictions could be made using the abaqus connector element to model the complete transition of a circumferential surface crack to a through-wall crack under cyclic dynamic loading. The JNES primary loop recirculation piping test was analyzed in detail. This combined-component test had three crack locations and multiple applied simulated seismic block loadings. Comparisons were also made between the ABAQUS finite element (FE) analyses results to the measured displacements in the experiment. Good agreement was obtained, and it was confirmed that the simplified modeling is applicable to a seismic analysis for a cracked pipe on the basis of fracture mechanics. Pipe system leakage did occur in the JNES tests. The analytical predictions using the CPE approach did not predict leakage, suggesting that cyclic ductile tearing with large-scale plasticity was not the crack growth mode for

  7. Surface degradation of CeO2 stabilized acrylic polyurethane coated thermally treated jack pine during accelerated weathering

    NASA Astrophysics Data System (ADS)

    Saha, Sudeshna; Kocaefe, Duygu; Boluk, Yaman; Pichette, Andre

    2013-07-01

    The thermally treated wood is a new value-added product and is very important for the diversification of forestry products. It drew the attention of consumers due to its attractive dark brown color. However, it loses its color when exposed to outside environment. Therefore, development of a protective coating for this value added product is necessary. In the present study, the efficiency of CeO2 nano particles alone or in combination with lignin stabilizer and/or bark extracts in acrylic polyurethane polymer was investigated by performing an accelerated weathering test. The color measurement results after accelerated weathering demonstrated that the coating containing CeO2 nano particles was the most effective whereas visual assessment suggested the coating containing CeO2 nano particles and lignin stabilizer as the most effective coating. The surface polarity changed for all the coatings during weathering and increase in contact angle after weathering suggested cross linking and reorientation of the polymer chain during weathering. The surface chemistry altered during weathering was evaluated by ATR-FTIR analysis. It suggested formation of different carbonyl byproducts during weathering. The chain scission reactions of the urethane linkages were not found to be significant during weathering.

  8. Decoupling degradation in exciton formation and recombination during lifetime testing of organic light-emitting devices

    NASA Astrophysics Data System (ADS)

    Hershey, Kyle W.; Suddard-Bangsund, John; Qian, Gang; Holmes, Russell J.

    2017-09-01

    The analysis of organic light-emitting device degradation is typically restricted to fitting the overall luminance loss as a function of time or the characterization of fully degraded devices. To develop a more complete understanding of degradation, additional specific data are needed as a function of luminance loss. The overall degradation in luminance during testing can be decoupled into a loss in emitter photoluminescence efficiency and a reduction in the exciton formation efficiency. Here, we demonstrate a method that permits separation of these component efficiencies, yielding the time evolution of two additional specific device parameters that can be used in interpreting and modeling degradation without modification to the device architecture or introduction of any additional post-degradation characterization steps. Here, devices based on the phosphor tris[2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3) are characterized as a function of initial luminance and emissive layer thickness. The overall loss in device luminance is found to originate primarily from a reduction in the exciton formation efficiency which is exacerbated in devices with thinner emissive layers. Interestingly, the contribution to overall degradation from a reduction in the efficiency of exciton recombination (i.e., photoluminescence) is unaffected by thickness, suggesting a fixed exciton recombination zone width and degradation at an interface.

  9. Development of a photovoltaic module qualification test based on combined-environment accelerated stress data

    NASA Technical Reports Server (NTRS)

    Trenchard, S. E.; Royal, E.; Anderson, R. T.

    1982-01-01

    The U.S. Coast Guard has developed a qualification test to screen photovoltaic modules for utilization on marine aids to navigation. The test is based on a combined-environment of hot and cold saltwater immersion and air pressurization. The test has demonstrated a very high acceleration factor and excellent correlation of electrical failures with modules in a concurrent real-time marine exposure.

  10. Development of a photovoltaic module qualification test based on combined-environment accelerated stress data

    NASA Technical Reports Server (NTRS)

    Trenchard, S. E.; Royal, E.; Anderson, R. T.

    1982-01-01

    The U.S. Coast Guard has developed a qualification test to screen photovoltaic modules for utilization on marine aids to navigation. The test is based on a combined-environment of hot and cold saltwater immersion and air pressurization. The test has demonstrated a very high acceleration factor and excellent correlation of electrical failures with modules in a concurrent real-time marine exposure.

  11. LWRSP FY09 testing and analysis of reactor metal degradation

    SciTech Connect

    Busby, Jeremy T; Nanstad, Randy K; Odette, G.; Was, Gary

    2009-09-01

    Current regulations require RPV steels to maintain conservative margins of fracture toughness so that postulated flaws do not threaten the integrity of the RPV during either normal operation and maintenance cycles or under accident transients, like pressurized thermal shock. Neutron irradiation degrades fracture toughness, in some cases severely. Thermal aging, while not generally considered a significant issue for a 40-y operating life, must be an additional consideration for operation to 60 or 80 years. Regulations, codified in the ASME Boiler and Pressure Vessel Code, Regulatory Guide 1.99 Rev 2, etc., recognize that embrittlement has a potential for reducing toughness below acceptable levels. The last few decades have seen remarkable progress in developing a mechanistic understanding of irradiation embrittlement. This understanding has been exploited in formulating robust, physically-based and statistically-calibrated models of CVN-indexed transition-temperature shifts (TTS). These semi-empirical models account for key embrittlement variables and variable interactions, including the effects of copper (Cu), nickel (Ni), phosphorous (P), fluence ({phi}t), flux ({phi}), and irradiation temperature (T{sub i}). However, these models and our present understanding of radiation damage are not fully quantitative, and do not treat all potentially significant variables and issues. Over the past three decades, developments in fracture mechanics have led to a number of consensus standards and codes for determining the fracture toughness parameters needed for development of databases that are useful for statistical analysis and establishment of uncertainties. The CVN toughness, however, is a qualitative measure, which must be correlated with the fracture toughness and crack-arrest toughness properties, K{sub Ic} and K{sub Ia}, necessary for structural integrity evaluations. Where practicable, direct measurements of the fracture toughness properties are desirable to reduce

  12. The conversion of CESR to operate as the Test Accelerator, CesrTA. Part 1: overview

    NASA Astrophysics Data System (ADS)

    Billing, M. G.

    2015-07-01

    Cornell's electron/positron storage ring (CESR) was modified over a series of accelerator shutdowns beginning in May 2008, which substantially improves its capability for research and development for particle accelerators. CESR's energy span from 1.8 to 5.6 GeV with both electrons and positrons makes it ideal for the study of a wide spectrum of accelerator physics issues and instrumentation related to present light sources and future lepton damping rings. Additionally a number of these are also relevant for the beam physics of proton accelerators. This paper outlines the motivation, design and conversion of CESR to a test accelerator, CESRTA, enhanced to study such subjects as low emittance tuning methods, electron cloud (EC) effects, intra-beam scattering, fast ion instabilities as well as general improvements to beam instrumentation. While the initial studies of CESRTA focussed on questions related to the International Linear Collider (ILC) damping ring design, CESRTA is a very flexible storage ring, capable of studying a wide range of accelerator physics and instrumentation questions. This paper contains the outline and the basis for a set of papers documenting the reconfiguration of the storage ring and the associated instrumentation required for the studies described above. Further details may be found in these papers.

  13. Test-particle acceleration in a hierarchical three-dimensional turbulence model

    SciTech Connect

    Dalena, S.; Rappazzo, A. F.; Matthaeus, W. H.; Dmitruk, P.; Greco, A.

    2014-03-10

    The acceleration of charged particles is relevant to the solar corona over a broad range of scales and energies. High-energy particles are usually detected in concomitance with large energy release events like solar eruptions and flares. Nevertheless, acceleration can occur at smaller scales, characterized by dynamical activity near current sheets. To gain insight into the complex scenario of coronal charged particle acceleration, we investigate the properties of acceleration with a test-particle approach using three-dimensional magnetohydrodynamic (MHD) models. These are obtained from direct solutions of the reduced MHD equations, well suited for a plasma embedded in a strong axial magnetic field, relevant to the inner heliosphere. A multi-box, multiscale technique is used to solve the equations of motion for protons. This method allows us to resolve an extended range of scales present in the system, namely, from the ion inertial scale of the order of a meter up to macroscopic scales of the order of 10 km (1/100th of the outer scale of the system). This new technique is useful to identify the mechanisms that, acting at different scales, are responsible for acceleration to high energies of a small fraction of the particles in the coronal plasma. We report results that describe acceleration at different stages over a broad range of time, length, and energy scales.

  14. Experimental Testing of a Micron-Scale Laser-Powered Accelerator

    SciTech Connect

    Travish, G.; Arab, E.; Lacroix, U. H.; Rosenzweig, J. B.; Vartanian, N.; Yoder, R. B.

    2009-01-22

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

  15. A self-injection acceleration test experiment for the FLAME laser

    NASA Astrophysics Data System (ADS)

    Labate, L.; Anelli, F.; Bacci, A.; Batani, D.; Bellaveglia, M.; Benedetti, C.; Benocci, R.; Cacciotti, L.; Cecchetti, C. A.; Ciricosta, O.; Clozza, A.; Cultrera, L.; Di Pirro, G.; Drenska, N.; Faccini, R.; Ferrario, M.; Filippetto, D.; Gallo, S.; Fioravanti, S.; Gamucci, A.; Gatti, G.; Ghigo, A.; Giulietti, A.; Giulietti, D.; Köster, P.; Levato, T.; Lollo, V.; Pace, E.; Pathak, N.; Rossi, A.; Serafini, L.; Turchetti, G.; Vaccarezza, C.; Valente, P.; Vicario, C.; Gizzi, L. A.

    2010-10-01

    A 250-TW laser system (FLAME - Frascati laser for acceleration and multidisciplinary experiments) is now in its commissioning phase in a new laboratory at LNF-INFN in the framework of the PLASMONX (Plasma acceleration and monochromatic X-ray generation) project. The laser will deliver<25 fs duration pulses with an energy up to 6 J, at a 10 Hz repetition rate. An ad hoc target area has also been designed and is currently being set up, allowing the first test experiments of electron laser wakefield acceleration to be carried out over the next few months in a safe, radiation-protected environment. An overview of the main features of the laser system and target area is given, along with a survey of the design and set-up of the self-injection test experiment, which is expected to reach the production of sub-GeV electron bunches.

  16. Real-time and accelerated outdoor endurance testing of solar cells

    NASA Technical Reports Server (NTRS)

    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.

  17. Statistical Degradation Models for Reliability Analysis in Non-Destructive Testing

    NASA Astrophysics Data System (ADS)

    Chetvertakova, E. S.; Chimitova, E. V.

    2017-04-01

    In this paper, we consider the application of the statistical degradation models for reliability analysis in non-destructive testing. Such models enable to estimate the reliability function (the dependence of non-failure probability on time) for the fixed critical level using the information of the degradation paths of tested items. The most widely used models are the gamma and Wiener degradation models, in which the gamma or normal distributions are assumed as the distribution of degradation increments, respectively. Using the computer simulation technique, we have analysed the accuracy of the reliability estimates, obtained for considered models. The number of increments can be enlarged by increasing the sample size (the number of tested items) or by increasing the frequency of measuring degradation. It has been shown, that the sample size has a greater influence on the accuracy of the reliability estimates in comparison with the measuring frequency. Moreover, it has been shown that another important factor, influencing the accuracy of reliability estimation, is the duration of observing degradation process.

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

    PubMed

    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.

  19. Effect of precipitation pattern on leaching of preservative from treated wood and implications for accelerated testing

    Treesearch

    Stan Lebow

    2014-01-01

    There is a need to develop improved accelerated test methods for evaluating the leaching of wood preservatives from treated wood exposed to precipitation. In this study the effects of rate of rainfall and length of intervals between rainfall events on leaching was evaluated by exposing specimens to varying patterns of simulated rainfall under controlled laboratory...

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  1. First Beam and High-Gradient Cryomodule Commissioning Results of the Advanced Superconducting Test Accelerator at Fermilab

    SciTech Connect

    Crawford, Darren; et al.

    2015-06-01

    The advanced superconducting test accelerator at Fermilab has accelerated electrons to 20 MeV and, separately, the International Linear Collider (ILC) style 8-cavity cryomodule has achieved the ILC performance milestone of 31.5 MV/m per cavity. When fully completed, the accelerator will consist of a photoinjector, one ILC-type cryomodule, multiple accelerator R&D beamlines, and a downstream beamline to inject 300 MeV electrons into the Integrable Optics Test Accelerator (IOTA). We report on the results of first beam, the achievement of our cryomodule to ILC gradient specifications, and near-term future plans for the facility.

  2. New Methodology and Apparatus for Accelerated Long-Life Testing of Linear-Drive Cryocoolers

    NASA Astrophysics Data System (ADS)

    Eremenko, V. V.; Getmanets, V. F.; Levin, A. Ya.; Pokhil, Yu. A.; Popov, V. A.; Stears, H.

    Present day cryocoolers should a 10-20 years on-orbit life-time. It is virtually impossible to test such a system in real time and maintain the design currency. We are proposing a new methodology and have been implemented unique technology to allow accelerated life of 6 to 20 times for such linear drive-type cryocoolers. Our approach is to segregate the cryocooler assembly into critical components and units with similar fatigue and aging characteristics. This selection must be based on use of innovative test stands, experience and past data. Next, we accelerate the life-time tests for each unit individually. And eventually, we assemble the cryocooler unit again, providing verification and validation of its parameters and comparing resultant data with those obtained prior to accelerated tests. In the report we described a test-stand being currently developed for the purpose of checking major critical components: * compressor drive as a whole (for fatigue aging tests under elevated testing frequency); * compressor borehole/ piston gap-sealing wear rate; * displacer failure caused due to buildup of deposited cryo-particles; * cryostat adsorber failure caused due to vacuum deterioration; * thermo-cycling fatigue aging of pressure-tight cryostat and compressor jackets.

  3. Optical characterization of voltage-accelerated degradation in CH3NH3PbI3 perovskite solar cells.

    PubMed

    Handa, Taketo; Tex, David M; Shimazaki, Ai; Aharen, Tomoko; Wakamiya, Atsushi; Kanemitsu, Yoshihiko

    2016-05-16

    We investigate the performance degradation mechanism of CH3NH3PbI3 perovskite solar cells under bias voltage in air and nitrogen atmospheres using photoluminescence and electroluminescence techniques. When applying forward bias, the power conversion efficiency of the solar cells decreased significantly in air, but showed no degradation in nitrogen atmosphere. Time-resolved photoluminescence measurements on these devices revealed that the application of forward bias in air accelerates the generation of non-radiative recombination centers in the perovskite layer buried in the device. We found a negative correlation between the electroluminescence intensity and the injected current intensity in air. The irreversible change of the perovskite grain surface in air initiates the degradation of the perovskite solar cells.

  4. LIDT test coupled with gamma radiation degraded optics

    NASA Astrophysics Data System (ADS)

    IOAN, M.-R.

    2016-06-01

    A laser can operate in regular but also in nuclear ionizing radiation environments. This paper presents the results of a real time measuring method used to detect the laser induced damage threshold (LIDT) in the optical surfaces/volumes of TEMPAX borosilicate glasses operating in high gamma rays fields. The laser damage quantification technique is applied by using of an automated station intended to measure the damage threshold of optical components, according to the International Standard ISO 21254. Single and multiple pulses laser damage thresholds were determined. For an optical material, life time when it is subjected to multiple pulses of high power laser radiation can be predicted. A few ns pulses shooting laser, operating in regular conditions, inflects damage to a target by its intense electrical component but also in a lower manner by local absorption of its transported thermal energy. When the beam is passing thru optical glass elements affected by ionizing radiation fields, the thermal component is starting to have a more important role, because of the increased thermal absorption in the material's volume caused by the radiation induced color centers. LIDT results on TEMPAX optical glass windows, with the contribution due to the gamma radiation effects (ionization mainly by Compton effect in this case), are presented. This contribution was highlighted and quantified. Energetic, temporal and spatial beam characterizations (according to ISO 11554 standards) and LIDT tests were performed using a high power Nd: YAG laser (1064 nm), before passing the beam through each irradiated glass sample (0 kGy, 1.3 kGy and 21.2 kGy).

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

    SciTech Connect

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

    2013-04-19

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

  6. Planned High-brightness Channeling Radiation Experiment at Fermilab's Advanced Superconducting Test Accelerator

    SciTech Connect

    Blomberg, Ben; Mihalcea, Daniel; Panuganti, Harsha; Piot, Philippe; Brau, Charles; Choi, Bo; Gabella, William; Ivanov, Borislav; Mendenhall, Marcus; Lynn, Christopher; Sen, Tanaji; Wagner, Wolfgang

    2014-07-01

    In this contribution we describe the technical details and experimental setup of our study aimed at producing high-brightness channeling radiation (CR) at Fermilab’s new user facility the Advanced Superconducting Test Accelerator (ASTA). In the ASTA photoinjector area electrons are accelerated up to 40-MeV and focused to a sub-micron spot on a ~40 micron thick carbon diamond, the electrons channel through the crystal and emit CR up to 80-KeV. Our study utilizes ASTA’s long pulse train capabilities and ability to preserve ultra-low emittance, to produce the desired high average brightness.

  7. The first picosecond terawatt CO{sub 2} laser at the Brookhaven Accelerator Test Facility

    SciTech Connect

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

    1998-02-01

    The first terawatt picosecond CO{sub 2} laser will be brought to operation at the Brookhaven Accelerator Test Facility in 1998. System consists of a single-mode TEA oscillator, picosecond semiconductor optical switch, multi-atmosphere. The authors report on design, simulation, and performance tests of the 10 atm final amplifier that allows for direct multi-joule energy extraction in a picosecond laser pulse.

  8. Sources of Error in Accelerated Stability Test Methods for Diesel Fuels.

    DTIC Science & Technology

    1985-06-01

    designated by other au- *- thorized documents. Trade names cited in this report do not constitute an official endorsement or approval of the use of such...including ASTM D 2274) used to determine the accelerated oxidation sta- bility of middle distillate fuels were reviewed. A critique of various...aging, and post-aging procedures on test results using a small set of test fuels. . Changes in the particulate filtration procedure and adherent

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  10. System tests with electric thruster beam and accelerator directly powered from laboratory solar arrays

    NASA Technical Reports Server (NTRS)

    Stover, J. B.

    1976-01-01

    Laboratory high voltage solar arrays were operated directly connected to power the beam and accelerator loads of an 8-centimeter ion thruster. The beam array comprised conventional 2 by 2 centimeter solar cells; the accelerator array comprised multiple junction edge-illuminated solar cells. Conventional laboratory power supplies powered the thruster's other loads. Tests were made to evaluate thruster performance and to investigate possible electrical interactions between the solar arrays and the thruster. Thruster performance was the same as with conventional laboratory beam and accelerator power supplies. Most of the thruster beam short circuits that occurred during solar array operation were cleared spontaneously without automatic or manual intervention. No spontaneous clearing occurred during conventional power supply operation.

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

    SciTech Connect

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

    2011-08-22

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

  12. Testing cosmic ray acceleration with radio relics: a high-resolution study using MHD and tracers

    NASA Astrophysics Data System (ADS)

    Wittor, D.; Vazza, F.; Brüggen, M.

    2017-02-01

    Weak shocks in the intracluster medium may accelerate cosmic-ray protons and cosmic-ray electrons differently depending on the angle between the upstream magnetic field and the shock normal. In this work, we investigate how shock obliquity affects the production of cosmic rays in high-resolution simulations of galaxy clusters. For this purpose, we performed a magnetohydrodynamical simulation of a galaxy cluster using the mesh refinement code ENZO. We use Lagrangian tracers to follow the properties of the thermal gas, the cosmic rays and the magnetic fields over time. We tested a number of different acceleration scenarios by varying the obliquity-dependent acceleration efficiencies of protons and electrons, and by examining the resulting hadronic γ-ray and radio emission. We find that the radio emission does not change significantly if only quasi-perpendicular shocks are able to accelerate cosmic-ray electrons. Our analysis suggests that radio-emitting electrons found in relics have been typically shocked many times before z = 0. On the other hand, the hadronic γ-ray emission from clusters is found to decrease significantly if only quasi-parallel shocks are allowed to accelerate cosmic ray protons. This might reduce the tension with the low upper limits on γ-ray emission from clusters set by the Fermi satellite.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Sensitization to Rubber Accelerators in Northeastern Italy: The Triveneto Patch Test Database.

    PubMed

    Buttazzo, Silvia; Prodi, Andrea; Fortina, Anna Belloni; Corradin, Maria Teresa; Larese Filon, Francesca

    2016-01-01

    Natural and synthetic rubbers containing rubber accelerators are well-known causes of occupational skin disease. Allergic contact dermatitis caused by rubber gloves is frequent and has almost exclusively been attributed to contact sensitization to accelerators. This study aimed to evaluate the frequency of rubber accelerators sensitization in the population living in northeastern Italy, to find time trend and a correlation with occupations, and to investigate co-sensitization between rubber accelerators. A population of 23,774 subjects was patch tested in 6 cities in northeastern Italy in the years 1996 to 2012 using carba mix 3%, thiuram mix 1%, benzothiazole (MBT) mix 1%, and isopropyl phenyl paraphenylamine diamine (IPPD) mix 0.6%. The overall frequency of carbamates, MBT, thiurams, and IPPD mix sensitization was 3.4%, 0.65%, 1.75%, and 0.83%, respectively. On a logistic regression analysis (control group: white-collar workers), we found a statistically significant association to carbamates (odds ratio [OR], 1.3; 95% confidence interval [CI], 1.03-1.7) and thiurams (OR, 1.6; 95% CI, 1.1-2.3) for health care workers. Thiuram sensitivity was also significantly associated with dermatitis in maids and restaurant workers (OR, 2.2; 95% CI, 1.4-3.6), hairdressers (OR, 3.6; 95% CI, 1.8-7.1), shop assistants (OR, 2.9; 95% CI, 1.2-6.8), construction workers (OR, 2.7; 95% CI, 1.7-4.1), mechanics (OR, 2.1; 95% CI, 1.3-3.4), and professional drivers (OR, 2.6; 95% CI, 1.2-5.9). In conclusion, our results demonstrated that rubber accelerators have an important role in allergic contact dermatitis in the northeast of Italy and their sensitization is associated significantly with occupations that wear gloves or use chemical substances. Between rubber accelerators tested, carbamates sensitization is prevalent and increasing during considered years.

  16. Measurement requirements and techniques for degradation studies and lifetime prediction testing of photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Noel, G. T.; Sliemers, F. A.; Derringer, G. C.; Wood, V. E.; Wilkes, K. E.; Gaines, G. B.; Carmichael, D. C.

    1978-01-01

    Tests of weathering and aging behavior are being developed to characterize the degradation and predict the lifetimes of low-cost photovoltaic arrays. Environmental factors which affect array performance include UV radiation, thermal energy, water, oxygen (generally involved in synergistic effects with UV radiation or high temperatures), physical stress, pollutants (oxides of nitrogen, sulfur dioxide and ozone), abrasives and dirt. A survey of photovoltaic array testing has shown the need to establish quantitative correlations between certain measurable properties (carbonyl formation, glass transition temperature, and molecular weight change) and modes of degradation and failure.

  17. In situ degradation: a new concept for system suitability tests in monographs of the European Pharmacopoeia.

    PubMed

    Rose, U

    1998-10-01

    Monographs of the European Pharmacopoeia describe in the LC-test for related substances usually a system suitability test in order to ensure the adequate separation of impurities. Since the reference substances required are often not available a recent approach to avoid this problem is the generation of the required impurity by 'in situ degradation' of the active principle. This paper describes some typical applications of this technique as well as recent examples, such as the controlled degradation of cefalotin sodium, imipenem and spiramycin.

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

    NASA Technical Reports Server (NTRS)

    Johnson, G. M.

    1976-01-01

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

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

    SciTech Connect

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

    2005-11-01

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

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

    SciTech Connect

    Lee, J.; Pan, R.

    2012-04-01

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

  1. Model for Initiation of Quality Factor Degradation at High Accelerating Fields in Superconducting Radio-Frequency Cavaties

    SciTech Connect

    Dzyuba, A.; Romanenko, A.; Cooley, L.D.; /Fermilab

    2010-07-13

    A model for the onset of the reduction in SRF cavity quality factor, the so-called Q-drop, at high accelerating electric fields is presented. Since magnetic fields at the cavity equator are tied to accelerating electric fields by a simple geometric factor, the onset of magnetic flux penetration determines the onset of Q-drop. We consider breakdown of the surface barrier at triangular grooves to predict the magnetic field of first flux penetration H{sub pen}. Such defects were argued to be the worst case by Buzdin and Daumens, [1998 Physica C 294 257], whose approach, moreover, incorporates both the geometry of the groove and local contamination via the Ginzburg-Landau parameter {kappa}. Since previous Q-drop models focused on either topography or contamination alone, the proposed model allows new comparisons of one effect in relation to the other. The model predicts equivalent reduction of H{sub pen} when either roughness or contamination were varied alone, so smooth but dirty surfaces limit cavity performance about as much as rough but clean surfaces do. Still lower H{sub pen} was predicted when both effects were combined, i.e. contamination should exacerbate the negative effects of roughness and vice-versa. To test the model with actual data, coupons were prepared by buffered chemical polishing and electropolishing, and stylus profilometry was used to obtain distributions of angles. From these data, curves for surface resistance generated by simple flux flow as a function of magnetic field were generated by integrating over the distribution of angles for reasonable values of {kappa}. This showed that combined effects of roughness and contamination indeed reduce the Q-drop onset field by {approx}20%, and that that contamination contributes to Q-drop as much as roughness. The latter point may be overlooked by SRF cavity research, since access to the cavity interior by spectroscopy tools is very difficult, whereas optical images have become commonplace. The model

  2. Model for initiation of quality factor degradation at high accelerating fields in superconducting radio-frequency cavities

    NASA Astrophysics Data System (ADS)

    Dzyuba, A.; Romanenko, A.; Cooley, L. D.

    2010-12-01

    A model for the onset of the reduction in superconducting radio-frequency (SRF) cavity quality factor, the so-called Q-drop, at high accelerating electric fields is presented. Since magnetic fields at the cavity equator are tied to accelerating electric fields by a simple geometric factor, the onset of magnetic flux penetration determines the onset of Q-drop. We consider breakdown of the surface barrier at triangular grooves to predict the magnetic field of first flux penetration Hpen. Such defects were argued to be the worst case by Buzdin and Daumens (1998 Physica C 294 257), whose approach, moreover, incorporates both the geometry of the groove and local contamination via the Ginzburg-Landau parameter κ. Since previous Q-drop models focused on either topography or contamination alone, the proposed model allows new comparisons of one effect in relation to the other. The model predicts equivalent reduction of Hpen when either roughness or contamination were varied alone, so smooth but dirty surfaces limit cavity performance about as much as rough but clean surfaces do. Still lower Hpen was predicted when both effects were combined, i.e. contamination should exacerbate the negative effects of roughness and vice versa. To test the model with actual data, coupons were prepared by buffered chemical polishing and electropolishing, and stylus profilometry was used to obtain distributions of angles. From these data, curves for surface resistance generated by simple flux flow as a function of magnetic field were generated by integrating over the distribution of angles for reasonable values of κ. This showed that combined effects of roughness and contamination indeed reduce the Q-drop onset field by ~ 20%, and that contamination contributes to Q-drop as much as roughness. The latter point may be overlooked by SRF cavity research, since access to the cavity interior by spectroscopy tools is very difficult, whereas optical images have become commonplace. The model was

  3. [Assessment of soil degradation in regions of nuclear power explosions at Semipalatinsk Nuclear Test Site].

    PubMed

    Evseeva, T I; Geras'kin, S A; Maĭstrenko, T A; Belykh, E S

    2011-01-01

    Degree of the soil cover degradation at the "Balapan" and "Experimental field" test sites was assessed based on Allium-test of soil toxicity results and international guidelines on radioactive restriction of solid materials (IAEA, 2004) and environment (Smith, 2005). Soil cover degradation maps of large-scale (1 : 25000) were made. The main part of the area mapped belongs to high-contaminated toxic degraded soil. A relationship between the soil toxicity and the total radionuclide activity concentrations was found to be described by power functions. When the calculated value (equal to 413-415 Bq/kg of air dry soil) increases, the soil becomes toxic for plants. This value is 7.8 times higher than the maximal value for background territories (53 Bq/kg) surrounding SNTS. Russian sanitary and hygienic guidelines (Radiation safety norms, 2009; Sanitary regulations of radioactive waste management, 2003) underestimate the degree of soil radioactive contamination for plants.

  4. Life Assessment for Cr-Mo Steel Dissimilar Joints by Various Filler Metals Using Accelerated Creep Testing

    NASA Astrophysics Data System (ADS)

    Petchsang, S.; Phung-on, I.; Poopat, B.

    2016-12-01

    Accelerated creep rupture tests were performed on T22/T91 dissimilar metal joints to determine the fracture location and rupture time of different weldments. Four configurations of deposited filler metal were tested using gas tungsten arc welding to estimate the service life for Cr-Mo steel dissimilar joints at elevated temperatures in power plants. Results indicated that failure in all configurations occurred in the tempered original microstructure and tempered austenite transformation products (martensite or bainite structure) as type IV cracking at the intercritical area of the heat-affected zone (ICHAZ) for both T22 and T91 sides rather than as a consequence of the different filler metals. Creep damage occurred with the formation of precipitations and microvoids. The correlation between applied stress and the Larson-Miller parameter (PLM) was determined to predict the service life of each material configuration. Calculated time-to-failure based on the PLM and test results for both temperature and applied stress parameters gave a reasonable fit. The dissimilar joints exhibited lower creep rupture compared to the base material indicating creep degradation of the weldment.

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

    SciTech Connect

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

    2012-07-03

    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.

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  8. A test house study of pesticides and pesticide degradation products following an indoor application.

    PubMed

    Starr, J M; Gemma, A A; Graham, S E; Stout, D M

    2014-08-01

    Preexisting pesticide degradates are a concern for pesticide biomonitoring studies as exposure to them may result in overestimation of pesticide exposure. The purpose of this research was to determine whether there was significant formation and movement, of pesticide degradates over a 5-week period in a controlled indoor setting after insecticide application. Movement of the pesticides during the study was also evaluated. In a simulated crack and crevice application, commercially available formulations of fipronil, propoxur, cis/trans-permethrin, and cypermethrin were applied to a series of wooden slats affixed to the wall in one room of an unoccupied test house. Floor surface samples were collected through 35 days post-application. Concentrations of the pesticides and the following degradates were determined: 2-iso-propoxyphenol, cis/trans 3-(2,2-dichlorovinyl)-3-3-dimethyl-(1-cyclopropane) carboxylic acid, 3-phenoxybenzoic acid, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl. Deltamethrin, which had never been applied, and chlorpyrifos, which had been applied several years earlier, and their degradation products, cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid, and, 3,5,6-trichloro-2-pyridinol, respectively, were also measured. Propoxur was the only insecticide with mass movement away from the application site. There was no measurable formation or movement of the degradates. However, all degradates were present at low levels in the formulated product. These results indicate longitudinal repetitive sampling of indoor degradate levels during short-term studies, is unnecessary. Exposure to preexisting pesticide degradates may inflate estimates of exposure in biomonitoring studies where these compounds are used as biomarkers. To date, there is no published information on formation of pesticide degradates following an indoor application. We found that the study pesticides have low rates of degradation and are unlikely to be a

  9. Novel durable bio-photocatalyst purifiers, a non-heterogeneous mechanism: accelerated entrapped dye degradation into structural polysiloxane-shield nano-reactors.

    PubMed

    Dastjerdi, Roya; Montazer, Majid; Shahsavan, Shadi; Böttcher, Horst; Moghadam, M B; Sarsour, Jamal

    2013-01-01

    This research has designed innovative Ag/TiO(2) polysiloxane-shield nano-reactors on the PET fabric to develop novel durable bio-photocatalyst purifiers. To create these very fine nano-reactors, oppositely surface charged multiple size nanoparticles have been applied accompanied with a crosslinkable amino-functionalized polysiloxane (XPs) emulsion. Investigation of photocatalytic dye decolorization efficiency revealed a non-heterogeneous mechanism including an accelerated degradation of entrapped dye molecules into the structural polysiloxane-shield nano-reactors. In fact, dye molecules can be adsorbed by both Ag and XPs due to their electrostatic interactions and/or even via forming a complex with them especially with silver NPs. The absorbed dye and active oxygen species generated by TiO(2) were entrapped by polysiloxane shelter and the presence of silver nanoparticles further attract the negative oxygen species closer to the adsorbed dye molecules. In this way, the dye molecules are in close contact with concentrated active oxygen species into the created nano-reactors. This provides an accelerated degradation of dye molecules. This non-heterogeneous mechanism has been detected on the sample containing all of the three components. Increasing the concentration of Ag and XPs accelerated the second step beginning with an enhanced rate. Further, the treated samples also showed an excellent antibacterial activity.

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

    PubMed

    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.

  11. Electron Lens Construction for the Integrable Optics Test Accelerator at Fermilab

    SciTech Connect

    McGee, Mike; Carlson, Kermit; Nobrega, Lucy; Stancari, Giulio; Valishev, Alexander

    2016-06-01

    The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p⁺) diagnostic test ring. Construction of an electron lens for IOTA is necessary for both electron and proton operation. Components required for the Electron Lens design include; a 0.8 T conventional water-cooled main solenoid, and magnetic bending and focusing elements. The foundation of the design relies on repurposing the Fermilab Tevatron Electron Lens II (TELII) gun and collector under ultra-high vacuum (UHV) conditions.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  13. Acceleration Testing: A Better, Faster, Cheaper Alternative for Strength Qualification Testing

    NASA Technical Reports Server (NTRS)

    Mattiello, Carmine F.

    1997-01-01

    This paper addresses the advantages of utilizing a centrifuge test over the conventional static load test methods to structurally qualify aerospace structures. Three recent test cases are reviewed and used as examples to highlight these benefits. In addition, the overall capability of Goddard's High Capacity Centrifuge (HCC) is outlined along with some unique features that were designed specifically to reduce costs, test turn around time, and increase test item safety.

  14. BLISTERING AND DEGRADATION OF POLYURETHANE COATINGS UNDER DIFFERENT ACCELERATED WEATHERING TESTS. (R828081E01)

    EPA Science Inventory

    An epoxy primer with a high gloss polyurethane topcoat coating system was exposed either only in a QUV chamber or exposed in a QUV chamber and a Prohesion chamber, alternatively, in this study. AFM studies found that micro blisters formed on the coating surface after both expo...

  15. Accelerated Stress Testing and Diagnostic Analysis of Degradation in CdTe Solar Cells

    SciTech Connect

    Albin, D. S.

    2008-11-01

    The primary goal of this study was to ascertain the presence and types of mechanisms affecting CdS/CdTe device stability in the temperature range of 60 to 120 ..deg..C. It should be noted that the results presented were specific to cells made using the specific growth conditions described.

  16. BLISTERING AND DEGRADATION OF POLYURETHANE COATINGS UNDER DIFFERENT ACCELERATED WEATHERING TESTS. (R828081E01)

    EPA Science Inventory

    An epoxy primer with a high gloss polyurethane topcoat coating system was exposed either only in a QUV chamber or exposed in a QUV chamber and a Prohesion chamber, alternatively, in this study. AFM studies found that micro blisters formed on the coating surface after both expo...

  17. Application of Rate Theory to Accelerated Durability Testing of Structural Adhesives

    DTIC Science & Technology

    1980-03-01

    comes too late to impact on material selection or design considerations. The analytical approach, coupled with an accelerated 10 testing program, is...estimated range and then evaluating the impact of each parameter on the failure rate and expected service life. The life-limiting components and the...interest of processing economy can be identified. This information can then be fed back into the system design process and the analyses repeated to

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

    SciTech Connect

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

    2012-03-01

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

  19. Relativistic Klystron Two-Beam Accelerator studies at the RTA test facility

    SciTech Connect

    Westenskow, G.A.; Houck, T.L.; Anderson, D.

    1996-08-16

    A prototype rf power source based on the Relativistic Klystron Two- Beam Accelerator (RK-TBA) concept is being constructed at LBNL to study physics, engineering, and costing issues. The prototype, called RTA, is described and compared to a full scale design appropriate for driving the Next Linear Collider. Specific details of the induction core test and pulsed power system are presented. Details of the 1-MeV, 1.2-kA induction gun currently under construction are described.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

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

    DTIC Science & Technology

    1975-08-01

    AD R-TR-77014 ENVIRONMENTAL EXPOSURE AND ACCELERATED TESTING OF RUBBER -TO-METAL VULCANIZED BONDED ASSABLIES JOHN A. WILLIAMS AUGUST 1975 A TECHNICAL...19. KEY WORDS (Continue on reverse aide If neceseary end Identify by block number) 1. Rubber -to-metal vulcanized bonds 2. Environmental exposure 3...was to determine the environmental resistance of rubber - to-metal vulcanized bonds and to develop the means of predicting this environ- mental

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

    SciTech Connect

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

    1994-09-01

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

  3. Thermoelectric generator testing and RTG degradation mechanisms evaluation. Progress report No. 35

    SciTech Connect

    Lockwood, A.; Shields, V.

    1980-05-01

    The n-type selenide legs after 14,000 hours continue to show reasonable agreement with the 3M Co. published data. In the ingradient testing after 14,700 hours the n-legs show serious degradation in power to load. Weight loss measurements on the first samples of material produced by G.E. match the results previously obtained on R.C.A. material from the MHW program. The remaining MHW generator on test Q1-A has accumulated 22,519 hours and performance remains stable. The 18 couple modules S/N-1 and -3 previously tested at RCA show no significant change in operation during the current JPL testing. No changes in the trends of degradation of LES 8 and 9 and the Voyager RTGs have been observed.

  4. Laboratory Test Methods to Determine the Degradation of Plastics in Marine Environmental Conditions

    PubMed Central

    Tosin, Maurizio; Weber, Miriam; Siotto, Michela; Lott, Christian; Degli Innocenti, Francesco

    2012-01-01

    In this technology report, three test methods were developed to characterize the degradation of plastic in marine environment. The aim was to outline a test methodology to measure the physical and biological degradation in different habitats where plastic waste can deposit when littered in the sea. Previously, research has focused mainly on the conditions encountered by plastic items when floating in the sea water (pelagic domain). However, this is just one of the possible habitats that plastic waste can be exposed to. Waves and tides tend to wash up plastic waste on the shoreline, which is also a relevant habitat to be studied. Therefore, the degradation of plastic items buried under sand kept wet with sea water has been followed by verifying the disintegration (visual disappearing) as a simulation of the tidal zone. Most biodegradable plastics have higher densities than water and also as a consequence of fouling, they tend to sink and lay on the sea floor. Therefore, the fate of plastic items lying on the sediment has been followed by monitoring the oxygen consumption (biodegradation). Also the effect of a prolonged exposure to the sea water, to simulate the pelagic domain, has been tested by measuring the decay of mechanical properties. The test material (Mater-Bi) was shown to degrade (total disintegration achieved in less than 9 months) when buried in wet sand (simulation test of the tidal zone), to lose mechanical properties but still maintain integrity (tensile strength at break = −66% in 2 years) when exposed to sea water in an aquarium (simulation of pelagic domain), and substantially biodegrade (69% in 236 days; biodegradation relative to paper: 88%) when located at the sediment/sea water interface (simulation of benthic domain). This study is not conclusive as the methodological approach must be completed by also determining degradation occurring in the supralittoral zone, on the deep sea floor, and in the anoxic sediment. PMID:22737147

  5. Laboratory test methods to determine the degradation of plastics in marine environmental conditions.

    PubMed

    Tosin, Maurizio; Weber, Miriam; Siotto, Michela; Lott, Christian; Degli Innocenti, Francesco

    2012-01-01

    In this technology report, three test methods were developed to characterize the degradation of plastic in marine environment. The aim was to outline a test methodology to measure the physical and biological degradation in different habitats where plastic waste can deposit when littered in the sea. Previously, research has focused mainly on the conditions encountered by plastic items when floating in the sea water (pelagic domain). However, this is just one of the possible habitats that plastic waste can be exposed to. Waves and tides tend to wash up plastic waste on the shoreline, which is also a relevant habitat to be studied. Therefore, the degradation of plastic items buried under sand kept wet with sea water has been followed by verifying the disintegration (visual disappearing) as a simulation of the tidal zone. Most biodegradable plastics have higher densities than water and also as a consequence of fouling, they tend to sink and lay on the sea floor. Therefore, the fate of plastic items lying on the sediment has been followed by monitoring the oxygen consumption (biodegradation). Also the effect of a prolonged exposure to the sea water, to simulate the pelagic domain, has been tested by measuring the decay of mechanical properties. The test material (Mater-Bi) was shown to degrade (total disintegration achieved in less than 9 months) when buried in wet sand (simulation test of the tidal zone), to lose mechanical properties but still maintain integrity (tensile strength at break = -66% in 2 years) when exposed to sea water in an aquarium (simulation of pelagic domain), and substantially biodegrade (69% in 236 days; biodegradation relative to paper: 88%) when located at the sediment/sea water interface (simulation of benthic domain). This study is not conclusive as the methodological approach must be completed by also determining degradation occurring in the supralittoral zone, on the deep sea floor, and in the anoxic sediment.

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

    SciTech Connect

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

    2014-10-15

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

  7. Measurements and simulations of wakefields at the Accelerator Test Facility 2

    NASA Astrophysics Data System (ADS)

    Snuverink, J.; Ainsworth, R.; Boogert, S. T.; Cullinan, F. J.; Lyapin, A.; Kim, Y. I.; Kubo, K.; Kuroda, S.; Okugi, T.; Tauchi, T.; Terunuma, N.; Urakawa, J.; White, G. R.

    2016-09-01

    Wakefields are an important factor in accelerator design, and are a real concern when preserving the low beam emittance in modern machines. Charge dependent beam size growth has been observed at the Accelerator Test Facility (ATF2), a test accelerator for future linear collider beam delivery systems. Part of the explanation of this beam size growth is wakefields. In this paper we present numerical calculations of the wakefields produced by several types of geometrical discontinuities in the beam line as well as tracking simulations to estimate the induced effects. We also discuss precision beam kick measurements performed with the ATF2 cavity beam position monitor system for a test wakefield source in a movable section of the vacuum chamber. Using an improved model independent method we measured a wakefield kick for this movable section of about 0.49 V /pC /mm , which, compared to the calculated value from electromagnetic simulations of 0.41 V /pC /mm , is within the systematic error.

  8. Accelerated aging test of solar mirrors: Comparison of different UV chambers

    NASA Astrophysics Data System (ADS)

    Avenel, Coralie; Gardette, Jean-Luc; Therias, Sandrine; Disdier, Angela; Raccurt, Olivier

    2017-06-01

    This study aimed to compare three accelerated aging chambers with different lamps and irradiance levels: Suntest XXL+ and Sepap 12/24 from ATLAS MTS and UV5X from AMC/AMTC. Five kinds of solar mirrors were tested: thin and thick monolithic glass, laminated glass, aluminum and a glass mirror stick on a composite polymer substrate. All samples were aged under irradiation with a temperature set onto 70 °C. Temperatures were measured directly onto samples in addition to the chamber value. Temperature was kept constant and equal in each device in order to get the same acceleration factor due to temperature for all aging. This allowed comparing the effect of irradiation only. Specular reflectance was measured at several intervals during aging, and silver and paints surfaces were monitored by optical microscopy. This study is included in the framework of the STAGE-STE European project. One of the objectives is to establish a standard for CSP mirrors accelerated aging tests. Results of aging are needed to understand which tests are relevant to each available technology of mirror. Furthermore, a standard aimed to be applied in any device which can reach required conditions, so influence of these devices has to be known to ensure the reproducibility of aging between chambers and laboratories.

  9. Performance and Environmental Test Results of the High Voltage Hall Accelerator Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Kamhawi, Hani; Haag, Thomas; Huang, Wensheng; Shastry, Rohit; Pinero, Luis; Peterson, Todd; Mathers, Alex

    2012-01-01

    NASA Science Mission Directorate's In-Space Propulsion Technology Program is sponsoring the development of a 3.5 kW-class engineering development unit Hall thruster for implementation in NASA science and exploration missions. NASA Glenn and Aerojet are developing a high fidelity high voltage Hall accelerator that can achieve specific impulse magnitudes greater than 2,700 seconds and xenon throughput capability in excess of 300 kilograms. Performance, plume mappings, thermal characterization, and vibration tests of the high voltage Hall accelerator engineering development unit have been performed. Performance test results indicated that at 3.9 kW the thruster achieved a total thrust efficiency and specific impulse of 58%, and 2,700 sec, respectively. Thermal characterization tests indicated that the thruster component temperatures were within the prescribed material maximum operating temperature limits during full power thruster operation. Finally, thruster vibration tests indicated that the thruster survived the 3-axes qualification full-level random vibration test series. Pre and post-vibration test performance mappings indicated almost identical thruster performance. Finally, an update on the development progress of a power processing unit and a xenon feed system is provided.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  11. Degradation profile and preliminary clinical testing of a resorbable device for ligation of blood vessels.

    PubMed

    Aminlashgari, Nina; Höglund, Odd V; Borg, Niklas; Hakkarainen, Minna

    2013-06-01

    A resorbable device for ligation of blood vessels was developed and tested in vitro to reveal the degradation profile of the device and to predict the clinical performance in terms of adequate mechanical support during a healing period of 1week. In addition, preliminary clinical testing was performed that showed complete hemostasis and good tissue grip of renal arteries in five pigs. The device was made by injection molding of poly(glycolide-co-trimethylene carbonate) triblock copolymer, and it consisted of a case with a locking mechanism connected to a partly perforated flexible band. A hydrolytic degradation study was carried out for 7, 30 and 60days in water and buffer medium, following the changes in mass, water absorption, pH and mechanical properties. A new rapid matrix-free laser desorption ionization-mass spectrometry (LDI-MS) method was developed for direct screening of degradation products released into the degradation medium. The combination of LDI-MS and electrospray ionization-mass spectrometry analyses enabled the comparison of the degradation product patterns in water and buffer medium. The identified degradation products were rich in trimethylene carbonate units, indicating preferential hydrolysis of amorphous regions where trimethylene units are located. The crystallinity of the material was doubled after 60days of hydrolysis, additionally confirming the preferential hydrolysis of trimethylene carbonate units and the enrichment of glycolide units in the remaining solid matrix. The mechanical performance of the perforated band was followed for the first week of hydrolysis and the results suggest that sufficient strength is retained during the healing time of the blood vessels.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

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

    SciTech Connect

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

    1987-01-01

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

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

    PubMed

    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.

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

    SciTech Connect

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

    1994-08-01

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

  16. Generation of laser pulse trains for tests of multi-pulse laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Shalloo, R. J.; Corner, L.; Arran, C.; Cowley, J.; Cheung, G.; Thornton, C.; Walczak, R.; Hooker, S. M.

    2016-09-01

    In multi-pulse laser wakefield acceleration (MP-LWFA) a plasma wave is driven by a train of low-energy laser pulses separated by the plasma period, an approach which offers a route to driving plasma accelerators with high efficiency and at high pulse repetition rates using emerging technologies such as fibre and thin-disk lasers. Whilst these laser technologies are in development, proof-of-principle tests of MP-LWFA require a pulse train to be generated from a single, high-energy ultrafast pulse. Here we demonstrate the generation of trains of up to 7 pulses with pulse separations in the range 150-170 fs from single 40 fs pulses produced by a Ti:sapphire laser.

  17. Prediction of reliability on thermoelectric module through accelerated life test and Physics-of-failure

    NASA Astrophysics Data System (ADS)

    Choi, Hyoung-Seuk; Seo, Won-Seon; Choi, Duck-Kyun

    2011-09-01

    Thermoelectric cooling module (TEM) which is electric device has a mechanical stress because of temperature gradient in itself. It means that structure of TEM is vulnerable in an aspect of reliability but research on reliability of TEM was not performed a lot. Recently, the more the utilization of thermoelectric cooling devices grows, the more the needs for life prediction and improvement are increasing. In this paper, we investigated life distribution, shape parameter of the TEM through accelerated life test (ALT). And we discussed about how to enhance life of TEM through the Physics-of-failure. Experimental results of ALT showed that the thermoelectric cooling module follows the Weibull distribution, shape parameter of which is 3.6. The acceleration model is coffin Coffin-Manson and material constant is 1.8.

  18. Error-Rate Estimation Based on Multi-Signal Flow Graph Model and Accelerated Radiation Tests

    PubMed Central

    Wang, Yueke; Xing, Kefei; Deng, Wei; Zhang, Zelong

    2016-01-01

    A method of evaluating the single-event effect soft-error vulnerability of space instruments before launched has been an active research topic in recent years. In this paper, a multi-signal flow graph model is introduced to analyze the fault diagnosis and meantime to failure (MTTF) for space instruments. A model for the system functional error rate (SFER) is proposed. In addition, an experimental method and accelerated radiation testing system for a signal processing platform based on the field programmable gate array (FPGA) is presented. Based on experimental results of different ions (O, Si, Cl, Ti) under the HI-13 Tandem Accelerator, the SFER of the signal processing platform is approximately 10−3(error/particle/cm2), while the MTTF is approximately 110.7 h. PMID:27583533

  19. Error-Rate Estimation Based on Multi-Signal Flow Graph Model and Accelerated Radiation Tests.

    PubMed

    He, Wei; Wang, Yueke; Xing, Kefei; Deng, Wei; Zhang, Zelong

    2016-01-01

    A method of evaluating the single-event effect soft-error vulnerability of space instruments before launched has been an active research topic in recent years. In this paper, a multi-signal flow graph model is introduced to analyze the fault diagnosis and meantime to failure (MTTF) for space instruments. A model for the system functional error rate (SFER) is proposed. In addition, an experimental method and accelerated radiation testing system for a signal processing platform based on the field programmable gate array (FPGA) is presented. Based on experimental results of different ions (O, Si, Cl, Ti) under the HI-13 Tandem Accelerator, the SFER of the signal processing platform is approximately 10-3(error/particle/cm2), while the MTTF is approximately 110.7 h.

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

    SciTech Connect

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

    1993-06-01

    The Ground Test Accelerator (GTA) has the objective of verifying much of the technology required for producing high-brightness, high-current H{sup {minus}} beams. GTA commissioning is staged to verify the beam-dynamics design of each major accelerator component as it is brought on-line. The major components are the 35-keV H{sup {minus}} injector, the 2.5-MeV radio-frequency quadrupole (RFQ), the intertank matching section (IMS), the 3.2 MeV first 2{beta}{lambda} drift tube linac (DTL-1) module, and the 24-MeV GTA with 10 DTL modules. Results from the DTL-1 beam experiments will be presented.

  1. Raman distributed temperature measurement at CERN high energy accelerator mixed field radiation test facility (CHARM)

    NASA Astrophysics Data System (ADS)

    Toccafondo, Iacopo; Nannipieri, Tiziano; Signorini, Alessandro; Guillermain, Elisa; Kuhnhenn, Jochen; Brugger, Markus; Di Pasquale, Fabrizio

    2015-09-01

    In this paper we present a validation of distributed Raman temperature sensing (RDTS) at the CERN high energy accelerator mixed field radiation test facility (CHARM), newly developed in order to qualify electronics for the challenging radiation environment of accelerators and connected high energy physics experiments. By investigating the effect of wavelength dependent radiation induced absorption (RIA) on the Raman Stokes and anti-Stokes light components in radiation tolerant Ge-doped multi-mode (MM) graded-index optical fibers, we demonstrate that Raman DTS used in loop configuration is robust to harsh environments in which the fiber is exposed to a mixed radiation field. The temperature profiles measured on commercial Ge-doped optical fibers is fully reliable and therefore, can be used to correct the RIA temperature dependence in distributed radiation sensing systems based on P-doped optical fibers.

  2. Preliminary results of accelerated exposure testing of solar cell system components

    NASA Technical Reports Server (NTRS)

    Anagnostou, E.; Forestieri, A. F.

    1977-01-01

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

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

    PubMed

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

    2012-02-01

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

  4. Nondestructive Magnetic Adaptive Testing of nuclear reactor pressure vessel steel degradation

    NASA Astrophysics Data System (ADS)

    Tomáš, I.; Vértesy, G.; Gillemot, F.; Székely, R.

    2013-01-01

    Inspection of neutron-irradiation-generated degradation of nuclear reactor pressure vessel steel (RPVS) is a very important task. In ferromagnetic materials, such as RPVS, the structural degradation is connected with a change of their magnetic properties. In this work, applicability of a novel magnetic nondestructive method (Magnetic Adaptive Testing, MAT), based on systematic measurement and evaluation of minor magnetic hysteresis loops, is shown for inspection of neutron irradiation embrittlement in RPVS. Three series of samples, made of JRQ, 15CH2MFA and 10ChMFT type steels were measured by MAT. The samples were irradiated by E > 1 MeV energy neutrons with total neutron fluence of 1.58 × 1019-11.9 × 1019 n/cm2. Regular correlation was found between the optimally chosen MAT degradation functions and the neutron fluence in all three types of the materials. Shift of the ductile-brittle transition temperature, ΔDBTT, independently determined as a function of the neutron fluence for the 15CH2MFA material, was also evaluated. A sensitive, linear correlation was found between the ΔDBTT and values of the relevant MAT degradation function. Based on these results, MAT is shown to be a promising (at least) complimentary tool of the destructive tests within the surveillance programs, which are presently used for inspection of neutron-irradiation-generated embrittlement of RPVS.

  5. Photothermal degradation studies

    NASA Technical Reports Server (NTRS)

    Liang, R. H.

    1985-01-01

    Key reaction intermediates of photooxidation identified and characterized by laser flash Electron Spin Resonance (ESR) spectroscopy were discussed. Effects of temperature and ultraviolet intensity were studied in order to develop meaningful accelerated testing procedures for encapsulant evaluation. In a program to study the failure of Tedlar/ethylene vinyl acetate (EVA)/stainless steel modules, failure modes similar to those observed outdoors in real-time conditions were simulated in accelerated testing. An experimental technique was developed to quantitatively assess the extent of degradation.

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

    PubMed Central

    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. PMID:25111800

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

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1975-01-01

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

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

    PubMed

    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.

  9. An activated energy approach for accelerated testing of the deformation of UHMWPE in artificial joints.

    PubMed

    Galetz, Mathias Christian; Glatzel, Uwe

    2010-05-01

    The deformation behavior of ultrahigh molecular polyethylene (UHMWPE) is studied in the temperature range of 23-80 degrees C. Samples are examined in quasi-static compression, tensile and creep tests to determine the accelerated deformation of UHMWPE at elevated temperatures. The deformation mechanisms under compression load can be described by one strain rate and temperature dependent Eyring process. The activation energy and volume of that process do not change between 23 degrees C and 50 degrees C. This suggests that the deformation mechanism under compression remains stable within this temperature range. Tribological tests are conducted to transfer this activated energy approach to the deformation behavior under loading typical for artificial knee joints. While this approach does not cover the wear mechanisms close to the surface, testing at higher temperatures is shown to have a significant potential to reduce the testing time for lifetime predictions in terms of the macroscopic creep and deformation behavior of artificial joints.

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

    SciTech Connect

    Utterback, J.

    1993-09-01

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

  11. Assessment of Accelerated Tests Compared to Beachfront Test and Proposed Evaluation Method

    DTIC Science & Technology

    2009-09-03

    corrosion tests to beachfront test NCAP Data Assessment Data set includes: – 4 aluminum alloys: 2024, 7075, 2219 , 5083 – 9 conversion coatings...2024-T3 Alodine 1600 2024-T3 TCP-IC 7075- T6 Alodine 1600 7075- T6 TCP-IC 18 Months Exposure at KSC 20X view of surface As is Cleaned Unpainted Corrosion ...Certification Program (ESTCP) funded project entitled “Non-Chromate Aluminum Pretreatments” (NCAP) – Funding began in 2000, ended 2004 for Phase I

  12. A Doping Lattice of Aluminum and Copper with Accelerated Electron Transfer Process and Enhanced Reductive Degradation Performance

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Gao, Xue; Zhang, Zhixuan; Zhang, Mingbo; Cheng, Yiqian; Su, Jixin

    2016-08-01

    Treatment of azo dye effluents has received increasing concerns over the years due to their potential harms to natural environment and human health. The present study described the degrading ability of the as-synthesized crystalline Al-Cu alloys for removal of high-concentration Acid Scarlet 3R in alkaline aqueous solutions and its degradation mechanism. Al-Cu alloy particles with Al/Cu ratios 19:1 were successfully synthesized by high-energy mechanical milling. Characterization results showed that 10 h mechanical alloying process could lead to the formation of crystalline Al(Cu) solid solution. Batch experiment results confirmed the excellent ability of Al-Cu alloy particles for the degradation of 3R in aqueous solution. Under a certain condition ([Al-Cu]0 = 2 g/L, [3R]0 = 200 mg/L, [NaCl]0 = 25 g/L, initial pH = 10.9), the 3R could be completely degraded within only 3 min. It was also found that the degradation reaction followed zero-order kinetics model with respect to the initial dye concentration. The intermediate compounds were identified by UV-vis, FT-IR and HPLC-MS, and a pathway was proposed. Additionally, post-treatment Al-Cu alloy particles were characterized by SEM and TEM, and the results showed that the degradation might be attributed to the corrosion effect of Al-Cu alloys.

  13. A Doping Lattice of Aluminum and Copper with Accelerated Electron Transfer Process and Enhanced Reductive Degradation Performance.

    PubMed

    Zhang, Lin; Gao, Xue; Zhang, Zhixuan; Zhang, Mingbo; Cheng, Yiqian; Su, Jixin

    2016-08-18

    Treatment of azo dye effluents has received increasing concerns over the years due to their potential harms to natural environment and human health. The present study described the degrading ability of the as-synthesized crystalline Al-Cu alloys for removal of high-concentration Acid Scarlet 3R in alkaline aqueous solutions and its degradation mechanism. Al-Cu alloy particles with Al/Cu ratios 19:1 were successfully synthesized by high-energy mechanical milling. Characterization results showed that 10 h mechanical alloying process could lead to the formation of crystalline Al(Cu) solid solution. Batch experiment results confirmed the excellent ability of Al-Cu alloy particles for the degradation of 3R in aqueous solution. Under a certain condition ([Al-Cu]0 = 2 g/L, [3R]0 = 200 mg/L, [NaCl]0 = 25 g/L, initial pH = 10.9), the 3R could be completely degraded within only 3 min. It was also found that the degradation reaction followed zero-order kinetics model with respect to the initial dye concentration. The intermediate compounds were identified by UV-vis, FT-IR and HPLC-MS, and a pathway was proposed. Additionally, post-treatment Al-Cu alloy particles were characterized by SEM and TEM, and the results showed that the degradation might be attributed to the corrosion effect of Al-Cu alloys.

  14. A Doping Lattice of Aluminum and Copper with Accelerated Electron Transfer Process and Enhanced Reductive Degradation Performance

    PubMed Central

    Zhang, Lin; Gao, Xue; Zhang, Zhixuan; Zhang, Mingbo; Cheng, Yiqian; Su, Jixin

    2016-01-01

    Treatment of azo dye effluents has received increasing concerns over the years due to their potential harms to natural environment and human health. The present study described the degrading ability of the as-synthesized crystalline Al-Cu alloys for removal of high-concentration Acid Scarlet 3R in alkaline aqueous solutions and its degradation mechanism. Al-Cu alloy particles with Al/Cu ratios 19:1 were successfully synthesized by high-energy mechanical milling. Characterization results showed that 10 h mechanical alloying process could lead to the formation of crystalline Al(Cu) solid solution. Batch experiment results confirmed the excellent ability of Al-Cu alloy particles for the degradation of 3R in aqueous solution. Under a certain condition ([Al-Cu]0 = 2 g/L, [3R]0 = 200 mg/L, [NaCl]0 = 25 g/L, initial pH = 10.9), the 3R could be completely degraded within only 3 min. It was also found that the degradation reaction followed zero-order kinetics model with respect to the initial dye concentration. The intermediate compounds were identified by UV-vis, FT-IR and HPLC-MS, and a pathway was proposed. Additionally, post-treatment Al-Cu alloy particles were characterized by SEM and TEM, and the results showed that the degradation might be attributed to the corrosion effect of Al-Cu alloys. PMID:27535800

  15. Test Particle Simulation of Acceleration in Cascading Current Sheet Obtained with 2.5D AMR MHD

    NASA Astrophysics Data System (ADS)

    Liu, Siming; Büchner, Jörg; Gan, Weiqun; Bárta, Miroslav; Zhou, Xiaowei

    2016-07-01

    With electro-magnetic field configuration derived from 2.5D AMR MHD simulations, we calculate the orbit of test charged particles with the guiding center approximation and study the particle acceleration by the induction and resistive electric fields. The induction field can lead to gradual acceleration via the drift of the particle guiding center in magnetic field curvature or gradient.The resistive electric field can lead to run away acceleration with particle energy changing drastically in regions with anomalous resistivity. We will discuss the implication of these results on the study of particle acceleration in turbulent reconnection current sheets.

  16. Accelerated proteasomal activity induced by Pb2+, Ga3+, or Cu2+ exposure does not induce degradation of alpha-synuclein.

    PubMed

    Grunberg-Etkovitz, Nurit; Lev, Nirit; Ickowicz, Debby; Avital, Almog; Offen, Daniel; Malik, Zvi

    2009-01-01

    The involvement of environmental heavy metals in Parkinson's disease (PD) has been suggested by epidemiologic studies; however, the mechanism of this effect is unknown. PD is characterized by the aggregation of alpha-synuclein in Lewy bodies. We previously showed that Pb2+ accelerates proteasomal activity. Therefore, we examined the effect of Pb2+, Ga3+, and Cu2+ on alpha-synuclein in human SH-SY5Y cells. The heavy metals induced an increase in heme-oxygenase-1 levels without significant cell death or ROS generation. The metals inhibited ALA-dehydratase, which is the inhibitory subunit of the proteasome, thereby accelerating proteasomal activity and decreasing protein levels of CDK-1 and PBGD. However, alpha-synuclein protein levels increased after exposure to metals, similar to the effect obtained with the proteasome inhibitor, hemin, suggesting that alpha-synuclein is inaccessible to proteasomal degradation. Indeed, electron microscopy revealed the formation of aggresomes in Pb2+- or hemin-treated cells. Thus, although heavy metals enhance proteasomal activity, alpha-synuclein is protected from degradation, and its protein levels and aggregation are increased.

  17. Test results of a Nb3Al/Nb3Sn subscale magnet for accelerator application

    DOE PAGES

    Iio, Masami; Xu, Qingjin; Nakamoto, Tatsushi; ...

    2015-01-28

    The High Energy Accelerator Research Organization (KEK) has been developing a Nb3Al and Nb3Sn subscale magnet to establish the technology for a high-field accelerator magnet. The development goals are a feasibility demonstration for a Nb3Al cable and the technology acquisition of magnet fabrication with Nb3Al superconductors. KEK developed two double-pancake racetrack coils with Rutherford-type cables composed of 28 Nb3Al wires processed by rapid heating, quenching, and transformation in collaboration with the National Institute for Materials Science and the Fermi National Accelerator Laboratory. The magnet was fabricated to efficiently generate a high magnetic field in a minimum-gap common-coil configuration with twomore » Nb3Al coils sandwiched between two Nb3Sn coils produced by the Lawrence Berkeley National Laboratory. A shell-based structure and a “bladder and key” technique have been used for adjusting coil prestress during both the magnet assembly and the cool down. In the first excitation test of the magnet at 4.5 K performed in June 2014, the highest quench current of the Nb3Sn coil, i.e., 9667 A, was reached at 40 A/s corresponding to 9.0 T in the Nb3Sn coil and 8.2 T in the Nb3Al coil. The quench characteristics of the magnet were studied.« less

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

    SciTech Connect

    Holmes, S.; Ziomek, C.; Adolphsen, C.

    1997-05-12

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

  19. Experimental high gradient testing of a 17.1 GHz photonic band-gap accelerator structure

    NASA Astrophysics Data System (ADS)

    Munroe, Brian J.; Zhang, JieXi; Xu, Haoran; Shapiro, Michael A.; Temkin, Richard J.

    2016-03-01

    We report the design, fabrication, and high gradient testing of a 17.1 GHz photonic band-gap (PBG) accelerator structure. Photonic band-gap (PBG) structures are promising candidates for electron accelerators capable of high-gradient operation because they have the inherent damping of high order modes required to avoid beam breakup instabilities. The 17.1 GHz PBG structure tested was a single cell structure composed of a triangular array of round copper rods of radius 1.45 mm spaced by 8.05 mm. The test assembly consisted of the test PBG cell located between conventional (pillbox) input and output cells, with input power of up to 4 MW from a klystron supplied via a TM01 mode launcher. Breakdown at high gradient was observed by diagnostics including reflected power, downstream and upstream current monitors and visible light emission. The testing procedure was first benchmarked with a conventional disc-loaded waveguide structure, which reached a gradient of 87 MV /m at a breakdown probability of 1.19 ×10-1 per pulse per meter. The PBG structure was tested with 100 ns pulses at gradient levels of less than 90 MV /m in order to limit the surface temperature rise to 120 K. The PBG structure reached up to 89 MV /m at a breakdown probability of 1.09 ×10-1 per pulse per meter. These test results show that a PBG structure can simultaneously operate at high gradients and low breakdown probability, while also providing wakefield damping.

  20. Degradation tests with PAH-metabolizing soil bacteria for in situ bioremediation

    SciTech Connect

    Maue, G.; Dott, W.

    1995-12-31

    A rapid screening test for PAH degradation was used to evaluate the metabolizing potential of a bacterial community from a contaminated soil. The test was performed on a small scale within a few days using direct fluorometric quantitative analysis of selected PAHs. Therefore, a wide range of isolates and mixed cultures could be investigated under various substrate conditions with little time and material expenditure. Furthermore, the composition of the bacterial community after growth on different carbon sources was observed. The tests accompanied PAH degradation experiments in a bioreactor for the detection of suitable soil bacteria for in situ bioremediation. A mixed culture consisting of at least five different bacterial species was found in samples of the bioreactor. Different precultivation substrates (PAH) did not influence the stability of the bacterial community. Although only a few isolates metabolized single PAHs (acenaphthene, anthracene, phenanthrene) as sole substrates, the mixed culture metabolized these PAHs within a few days regardless of the precultivation. The stability of the mixed culture indicates its resistance to substrate changes that may occur during in situ bioremediation processes. Enhanced degradation rates occurred following the growth on acenaphthene and phenanthrene.