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Time Dilation Cosmology 3: Mathematical Proof of the 3 Temporal and 2 Spatial Acceleration Factors
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作者 Joseph H. (Cass) Forrington 《Journal of Modern Physics》 2024年第12期2228-2237,共10页
This is the fifth paper in a series on Time Dilation Cosmology, TDC. TDC is an eternal holographic model of the universe based on time dilation that ties astrophysics to quantum physics and resolves all the conundrums... This is the fifth paper in a series on Time Dilation Cosmology, TDC. TDC is an eternal holographic model of the universe based on time dilation that ties astrophysics to quantum physics and resolves all the conundrums in astrophysics and serves as a model for the unified field. In the author’s previous four TDC papers, it was demonstrated that all gravitationally induced velocities are compensation for the apparent difference in the rates of time, “dRt”, due to mass/energy densities, and, vice-versa, in all force-induced velocities the dRt is compensation for the velocity, so the uniform evolution of the continuum at c is maintained at the invariant 1 s/s rate of time of the universe as a whole. These compensations make it impossible for an event to lag behind or get ahead of the evolving continuum. When the author did the first velocity formula derivations in “General Relativity: Effects in Time as Causation” [1], the author felt the explanations for the appearance of the 2spatial and the 3temporal acceleration factors in the formulas were correct, but poorly explained and incomplete. This paper is a proof of the temporal and spatial acceleration factors used in the time dilation-based velocity formula derivations in the Time Dilation Cosmology model. 展开更多
关键词 Mathematical Proof Time Dilation Cosmology acceleration factors
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Acceleration Factor Harmonious Particle Swarm Optimizer 被引量:2
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作者 Jie Chen Feng Pan Tao Cai 《International Journal of Automation and computing》 EI 2006年第1期41-46,共6页
A Particle Swarm Optimizer (PSO) exhibits good performance for optimization problems, although it cannot guarantee convergence to a global, or even local minimum. However, there are some adjustable parameters, and r... A Particle Swarm Optimizer (PSO) exhibits good performance for optimization problems, although it cannot guarantee convergence to a global, or even local minimum. However, there are some adjustable parameters, and restrictive conditions, which can affect the performance of the algorithm. In this paper, the sufficient conditions for the asymptotic stability of an acceleration factor and inertia weight are deduced, the value of the inertia weight w is enhanced to ( 1, 1). Furthermore a new adaptive PSO algorithm - Acceleration Factor Harmonious PSO (AFHPSO) is proposed, and is proved to be a global search algorithm. AFHPSO is used for the parameter design of a fuzzy controller for a linear motor driving servo system. The performance of the nonlinear model for the servo system demonstrates the effectiveness of the optimized fuzzy controller and AFHPSO. 展开更多
关键词 Particle swarm optimizer acceleration factor harmonious PSO asymptotic stability global convergence fuzzy control.
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Effect of basic fibroblast growth factor and danshen on bcl-2 and p53 mRNA expression in the brain of rats exposed to repeated, high, positive acceleration (+Gz)
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作者 Hongjin Liu Qing Cai 《Neural Regeneration Research》 SCIE CAS CSCD 2008年第7期747-750,共4页
BACKGROUND: Both animal experiments and clinical studies have shown that basic fibroblast growth factor (bFGF) and danshen (Salvia miltiorrhiza) can exhibit protective effects on ischemia-reperfusion cerebral inj... BACKGROUND: Both animal experiments and clinical studies have shown that basic fibroblast growth factor (bFGF) and danshen (Salvia miltiorrhiza) can exhibit protective effects on ischemia-reperfusion cerebral injury. OBJECTIVE: To test whether bFGF and danshen can protect cerebral injury induced by exposure to repeated, high, positive acceleration (+Gz) in an animal model and to analyze the possible mechanisms. DESIGN, TIME AND SETTING: Randomized controlled animal study. The experiment was performed at the Research Center for Molecular Biology, Air-force General Hospital of Chinese PLA from April to August 2000. MATERIALS: A total of 20 clean grade, healthy, Sprague Dawley rats of both genders, weighing (200 ± 15) g, were provided by our experimental animal center. Rats were randomly divided into 5 groups: the control group, +Gz exposure group, bFGF group, danshen group, and saline group, with 4 animals per group. bFGF (Beijing Bailuyuan Biotechnology Co. Ltd.) and danshen solution (Shanghai Zhongxi Pharmaceutical Co. Ltd.) were used. METHODS: All rats were fixed on a rotary arm of a centrifugal apparatus (2 m in radius) with their heads oriented towards the center of the apparatus. Except for rats in the control group, the value of +Gz exposure was +14 Gz with an acceleration rate of 1.5 G/s. The peak force lasted for 45 seconds. +Gz exposure was performed three times with intervals of 30 minutes. Rats in the control group received the same +Gz procedure, but the G value was +1 Gz. Rats in bFGF group and danshen group were intraperitoneally injected with 100 μg/kg bFGF or 15 g/kg danshen solution, respectively, at 30 minutes prior to centrifugation and immediately after centrifugation. Rats in saline group were injected with the same volume of saline. Six hours after exposure, rats were decapitated. One hemisphere was preserved in liquid nitrogen for RNA extraction and the other was processed for apoptosis detection. MAIN OUTCOME MEASURES: mRNA levels of bcl-2 and p53 were measured by semi-quantitative reverse-transcription polymerase chain reaction. Apoptotic cell death was detected by terminal deoxynuleotidyl transferase-mediated dUTP nick end labeling. RESULTS: Changes in mRNA expression of bcl-2 and p53 and apoptotic cells were observed in rat brain six hours after repeated +Gz exposures, bFGF and danshen were able block the changes of bcl-2 and p53 expression and inhibit apoptotic cell death. CONCLUSION: The data suggest that apoptosis and changes in bcl-2 and p53 expression in the rat brain can be induced by repeated +Gz exposures. Apoptosis is, therefore, one of the molecular mechanisms of brain damage induced by repeated +Gz exposures, bFGF and danshen were of the equal potency in preventing brain injury induced by repeated +Gz exposures. 展开更多
关键词 positive acceleration RATS apoptosis BCL-2 P53 gene expression basic fibroblast growth factor DANSHEN
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A WSN Node Fault Diagnosis Model Based on BRB with Self-Adaptive Quality Factor
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作者 Guo-Wen Sun Gang Xiang +3 位作者 Wei He Kai Tang Zi-Yi Wang Hai-Long Zhu 《Computers, Materials & Continua》 SCIE EI 2023年第4期1157-1177,共21页
Wireless sensor networks (WSNs) operate in complex and harshenvironments;thus, node faults are inevitable. Therefore, fault diagnosis ofthe WSNs node is essential. Affected by the harsh working environment ofWSNs and ... Wireless sensor networks (WSNs) operate in complex and harshenvironments;thus, node faults are inevitable. Therefore, fault diagnosis ofthe WSNs node is essential. Affected by the harsh working environment ofWSNs and wireless data transmission, the data collected by WSNs containnoisy data, leading to unreliable data among the data features extracted duringfault diagnosis. To reduce the influence of unreliable data features on faultdiagnosis accuracy, this paper proposes a belief rule base (BRB) with a selfadaptivequality factor (BRB-SAQF) fault diagnosis model. First, the datafeatures required for WSN node fault diagnosis are extracted. Second, thequality factors of input attributes are introduced and calculated. Third, themodel inference process with an attribute quality factor is designed. Fourth,the projection covariance matrix adaptation evolution strategy (P-CMA-ES)algorithm is used to optimize the model’s initial parameters. Finally, the effectivenessof the proposed model is verified by comparing the commonly usedfault diagnosis methods for WSN nodes with the BRB method consideringstatic attribute reliability (BRB-Sr). The experimental results show that BRBSAQFcan reduce the influence of unreliable data features. The self-adaptivequality factor calculation method is more reasonable and accurate than thestatic attribute reliability method. 展开更多
关键词 self-adaptive quality factor belief rule base wireless sensor networks fault diagnosis
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Relationship between critical seismic acceleration coefficient and static factor of safety of 3D slopes
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作者 SHI He-yang CHEN Guang-hui 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第5期1546-1554,共9页
Many analytical methods have been adopted to estimate the slope stability by providing various stability numbers,e.g.static safety of factor(static FoS)or the critical seismic acceleration coefficient,while little att... Many analytical methods have been adopted to estimate the slope stability by providing various stability numbers,e.g.static safety of factor(static FoS)or the critical seismic acceleration coefficient,while little attention has been given to the relationship between the slope stability numbers and the critical seismic acceleration coefficient.This study aims to investigate the relationship between the static FoS and the critical seismic acceleration coefficient of soil slopes in the framework of the upper-bound limit analysis.Based on the 3D rotational failure mechanism,the critical seismic acceleration coefficient using the pseudo-static method and the static FoS using the strength reduction technique are first determined.Then,the relationship between the static FoS and the critical seismic acceleration coefficient is presented under considering the slope angleβ,the frictional angleφ,and the dimensionless coefficients B/H and c/γH.Finally,a fitting formula between the static FoS and the critical seismic acceleration coefficient is proposed and validated by analytical and numerical results. 展开更多
关键词 static safety of factor critical seismic acceleration coefficient upper-bound limit analysis 3D rotational failure mechanism
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ON THE CHOICES OF ACCELERATING CONVERGENCE FACTORS FOR LIMIT PERIODIC CONTINUED FRACTION K(an/1) 被引量:4
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作者 唐烁 檀结庆 朱功勤 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 1996年第1期62-70,共9页
There are many accelerating convergence factors (ACFs) for limit periodic continued fraction K(an/1)(an→a≠0). In this paper, some characteristics and comparative theorems are ob tained on ACFs. Two results are given... There are many accelerating convergence factors (ACFs) for limit periodic continued fraction K(an/1)(an→a≠0). In this paper, some characteristics and comparative theorems are ob tained on ACFs. Two results are given for most frequently used ACFs. 展开更多
关键词 LIMIT PERIODIC continued FRACTION accelerating CONVERGENCE factor.
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Ultrahigh accelerating gradient and quality factor of CEPC 650 MHz superconducting radio-frequency cavity 被引量:3
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作者 Peng Sha Wei-Min Pan +9 位作者 Song Jin Ji-Yuan Zhai Zheng-Hui Mi Bai-Qi Liu Chao Dong Fei-Si He Rui Ge Liang-Rui Sun Shi-Ao Zheng Ling-Xi Ye 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第10期33-40,共8页
Two 650 MHz single-cell superconducting radio-frequency(SRF)cavities used for the Circular Electron Positron Collider(CEPC)were studied to achieve a high accelerating gradient(E_(acc))and high intrinsic quality factor... Two 650 MHz single-cell superconducting radio-frequency(SRF)cavities used for the Circular Electron Positron Collider(CEPC)were studied to achieve a high accelerating gradient(E_(acc))and high intrinsic quality factor(Q_(0)).The 650 MHz single-cell cavities were subjected to a combination of buffered chemical polishing(BCP)and electropolishing(EP),and their E_(acc) exceeded40 MV/m.Such a high E_(acc) may result from the cold EP with more uniform removal.BCP is easy,cheap,and rough,whereas EP is complicated,expensive,and precise Therefore,the combination of BCP and EP investigated in this study is suitable for surface treatments of mass SRF cavities.Medium temperature(mid-T)furnace baking was also conducted,which demonstrated an ultrahigh Q_(0) of 8×10^(10) at 22 MV/m for both cavities,and an extremely low BCS resistance(R_(BCS))of~1.0 nΩwas achieved a2.0 K. 展开更多
关键词 SRF cavity accelerating gradient Quality factor ELECTROPOLISHING Vertical test
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Seismic force demands on acceleration-sensitive nonstructural components:a state-of-the-art review 被引量:4
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作者 Wang Tao Shang Qingxue Li Jichao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2021年第1期39-62,共24页
Nonstructural components(NSCs)are parts,elements,and subsystems that are not part of the primary loadbearing system of building structures but are subject to seismic loading.Damage to NSCs may disrupt the functionalit... Nonstructural components(NSCs)are parts,elements,and subsystems that are not part of the primary loadbearing system of building structures but are subject to seismic loading.Damage to NSCs may disrupt the functionality of buildings and result in significant economic losses,injuries,and casualties.In past decades,extensive studies have been conducted on the seismic performance and seismic design methods of NSCs.As the input for the seismic design of NSCs,floor response spectra(FRS)have attracted the attention of researchers worldwide.This paper presents a state-of-the-art review of FRS.Different methods for generating FRS are summarized and compared with those in current seismic design codes.A detailed review of the parameters influencing the FRS is presented.These parameters include the characteristics of ground motion excitation,supporting building and NSCs.The floor acceleration response and the FRS obtained from experimental studies and field observations during earthquakes are also discussed.Three RC frames are used in a case study to compare the peak floor acceleration(PFA)and FRS calculated from time history analyses(THA)with that generated using current seismic design codes and different methods in the literature.Major knowledge gaps are identified,including uncertainties associated with developing FRS,FRS generation methods for different types of buildings,the need for comprehensive studies on absolute acceleration,relative velocity,and relative displacement FRS,and the calibration of FRS by field observations during earthquakes. 展开更多
关键词 nonstructural components peak floor acceleration floor response spectra component amplification factor
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Amplification Effect of Peak Ground Motion Acceleration in ClassⅡ and Ⅲ Sites over Shandong Province 被引量:1
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作者 Diao Ting Chen Shijun Jiang Zaofeng 《Earthquake Research in China》 2011年第4期498-506,共9页
In this paper, the amplification factor (ks ) of peek ground motion with different exceedance probability in class Ⅱ and Ⅲ sites over Shandong Province was estimated by analyzing the seismic response data of soil ... In this paper, the amplification factor (ks ) of peek ground motion with different exceedance probability in class Ⅱ and Ⅲ sites over Shandong Province was estimated by analyzing the seismic response data of soil layers collected from 358 boreholes of class Ⅱ sites and 140 boreholes of class Ⅲ site. From the results, one can conclude that: (1) The scatter plot of ks generally obeys a normal distribution ; (2) ks decreases with the increase of the strength of input ground motion, which is more apparent in Class Ⅲ site than in class lI site; (3) for class Ⅱ site, with the increase of depth of the bedrock interface where ground motion inputs, ks increases gradually until to a stable value when the depth reaches up to approximately 20 meters or larger. Yet, for class Ⅲ site, ks is insensitive to the depth; (4) the average of ks for class Ⅱ site is 1.47, slightly larger than that used in the Seismic Ground Motion Parameters Zonation Map of China ( GB 18306-2001 ). Also, ks in class Ⅱ and Ⅲ sites at different levels of peak ground acceleration over Shandong Province is preliminarily discussed in the paper. 展开更多
关键词 Seismic ground motion Peak ground acceleration Site condition Exceedanceprobability amplification factor
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An enriched environment improves cognitive performance in mice from the senescence-accelerated prone mouse 8 strain Role of upregulated neurotrophic factor expression in the hippocampus 被引量:2
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作者 Zhenyun Yuan Mingwei Wang Baoyong Yan Ping Gu Xiangming Jiang Xiufen Yang 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第23期1797-1804,共8页
In this study,we examined 3-month-old female mice from the senescence-accelerated prone mouse 8 strain and age-matched homologous normal aging female mice from the senescence accelerated-resistant mouse 1 strain.Mice ... In this study,we examined 3-month-old female mice from the senescence-accelerated prone mouse 8 strain and age-matched homologous normal aging female mice from the senescence accelerated-resistant mouse 1 strain.Mice from each strain were housed in an enriched environment(including a platform,running wheels,tunnel,and some toys)or a standard environment for 3 months.The mice housed in the enriched environment exhibited shorter escape latencies and a greater percentage of time in the target quadrant in the Morris water maze test,and they exhibited reduced errors and longer latencies in step-down avoidance experiments compared with mice housed in the standard environment.Correspondently,brain-derived neurotrophic factor mRNA and protein ex- pression in the hippocampus was significantly higher in mice housed in the enriched environment compared with those housed in the standard environment,and the level of hippocampal brain-derived neurotrophic factor protein was positively correlated with the learning and memory abilities of mice from the senescence-accelerated prone mouse 8 strain.These results suggest that an enriched environment improved cognitive performance in mice form the senescence-accelerated prone mouse 8 strain by increasing brain-derived neurotrophic factor expression in the hippocampus. 展开更多
关键词 Alzheimer’s disease enriched environment cognition brain-derived neurotrophic factor neurotrophic factor senescence-accelerated prone mouse HIPPOCAMPUS neural regeneration
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A Self-Adaptive Control Method for Uncertainty Systems Based on ANN with AEP
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作者 王平 杨汝清 《Journal of Donghua University(English Edition)》 EI CAS 2007年第6期774-777,共4页
A self-adaptive control method is proposed based on an artificial neural network(ANN)with accelerated evolutionary programming(AEP)algorithm.The neural network is used to model the uncertainty process,from which the t... A self-adaptive control method is proposed based on an artificial neural network(ANN)with accelerated evolutionary programming(AEP)algorithm.The neural network is used to model the uncertainty process,from which the teacher signals are produced online to regulate the parameters of the controller.The accelerated evolutionary programming is used to train the neural network.The experiment results show that the method can obviously improve the dynamic performance of uncertainty systems. 展开更多
关键词 accelerated evolutionary programming ANN self-adaptive control uncertainty system
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Discussion of the Fluid Acceleration Quality of a Ducted Propulsion System on the Propulsive Performance
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作者 Jui-Hsiang Kao Yi-Fan Liao 《Computer Modeling in Engineering & Sciences》 SCIE EI 2022年第3期1325-1348,共24页
This paper focuses on the ducted propulsion with the accelerating nozzle,and discusses the influence of its fluid acceleration quality on its propulsive performances,including the hull efficiency,the relative rotative... This paper focuses on the ducted propulsion with the accelerating nozzle,and discusses the influence of its fluid acceleration quality on its propulsive performances,including the hull efficiency,the relative rotative efficiency,the effective wake,and the thrust deduction factor.An actual ducted propulsion system is used as an example for computational analysis.The computational conditions are divided into four combinations,which are provided with different propeller pitches,cambers,and duct lengths.Themethod applied in this study is the Computational Fluid Dynamics(CFD)technology,and the contents of the calculation include the hull’s viscous resistance,the wave-making resistance,the propeller performance curve,and the self-propulsion simulation in order to obtain the ship’s effective wake,thrust deduction factor,hull efficiency,and relative rotative efficiency.The performance curve of the propeller and resistance estimation results are compared with the experimental values for determining the correctness of the self-propulsion simulation.According to the computational analysis,it is known that increasing the propeller pitch cannot effectively increase the hull efficiency.The duct acceleration quality can be reduced by shortening the duct length;hence,when the effective wake fraction and thrust deduction factor decrease,the hull efficiency is increased.In addition,the pressure inside the duct is relatively low if the acceleration quality of the duct is too high,which is unfavorable for controlling the propeller cavitation.Moreover,if the hull bottom in front of the propeller is tapered up from the front to the back at an overly steep angle,the thrust deduction factor will be too large and lead to a relatively low hull efficiency. 展开更多
关键词 Ducted propellers accelerating nozzle hull efficiency relative rotative efficiency effective wake thrust deduction factor
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Statistical Analysis for Constant-stress Partially Accelerated Life Test with Interval Censored Data 被引量:2
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作者 LONG Bing ZHANG Zhong-zhan 《Chinese Quarterly Journal of Mathematics》 2019年第1期1-13,共13页
In this paper, a statistical analysis method is proposed to research life characteristics of products based on the partially accelerated life test. We discuss the statistical analysis for constant-stress partially acc... In this paper, a statistical analysis method is proposed to research life characteristics of products based on the partially accelerated life test. We discuss the statistical analysis for constant-stress partially accelerated life tests with Lomax distribution based on interval censored samples. The EM algorithm is used to obtain the maximum likelihood estimations(MLEs) and interval estimations for the shape parameter and acceleration factor.The average relative errors(AREs), mean square errors(MSEs), the confidence intervals for the parameters, and the influence of the sample size are discussed. The results show that the AREs and MSEs of the MLEs decrease with the increase of sample size. Finally, a simulation sample is used to estimate the reliability under different stress levels. 展开更多
关键词 INTERVAL censored SAMPLES PARTIALLY accelerATED life test accelerATED factor EM algorithm FISHER information matrix
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Electromagnetic Oscillations in a Spherical Conducting Cavity with Dielectric Layers. Application to Linear Accelerators 被引量:1
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作者 Wladyslaw Zakowicz Andrzej A. Skorupski Eryk Infeld 《Journal of Electromagnetic Analysis and Applications》 2013年第1期32-42,共11页
We present an analysis of electromagnetic oscillations in a spherical conducting cavity filled concentrically with either dielectric or vacuum layers. The fields are given analytically, and the resonant frequency is d... We present an analysis of electromagnetic oscillations in a spherical conducting cavity filled concentrically with either dielectric or vacuum layers. The fields are given analytically, and the resonant frequency is determined numerically. An important special case of a spherical conducting cavity with a smaller dielectric sphere at its center is treated in more detail. By numerically integrating the equations of motion we demonstrate that the transverse electric oscillations in such cavity can be used to accelerate strongly relativistic electrons. The electron’s trajectory is assumed to be nearly tangential to the dielectric sphere. We demonstrate that the interaction of such electrons with the oscillating magnetic field deflects their trajectory from a straight line only slightly. The Q factor of such a resonator only depends on losses in the dielectric. For existing ultra low loss dielectrics, Q can be three orders of magnitude better than obtained in existing cylindrical cavities. 展开更多
关键词 SPHERICAL CAVITY SPHERICAL DIELECTRIC Layer TE MODE TM MODE Q factor Linear accelerATOR
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Designing Adaptive Multiple Dependent State Sampling Plan for Accelerated Life Tests 被引量:1
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作者 Pramote Charongrattanasakul Wimonmas Bamrungsetthapong Poom Kumam 《Computer Systems Science & Engineering》 SCIE EI 2023年第8期1631-1651,共21页
A novel adaptive multiple dependent state sampling plan(AMDSSP)was designed to inspect products from a continuous manufacturing process under the accelerated life test(ALT)using both double sampling plan(DSP)and multi... A novel adaptive multiple dependent state sampling plan(AMDSSP)was designed to inspect products from a continuous manufacturing process under the accelerated life test(ALT)using both double sampling plan(DSP)and multiple dependent state sampling plan(MDSSP)concepts.Under accelerated conditions,the lifetime of a product follows the Weibull distribution with a known shape parameter,while the scale parameter can be determined using the acceleration factor(AF).The Arrhenius model is used to estimate AF when the damaging process is temperature-sensitive.An economic design of the proposed sampling plan was also considered for the ALT.A genetic algorithm with nonlinear optimization was used to estimate optimal plan parameters to minimize the average sample number(ASN)and total cost of inspection(TC)under both producer’s and consumer’s risks.Numerical results are presented to support the AMDSSP for the ALT,while performance comparisons between the AMDSSP,the MDSSP and a single sampling plan(SSP)for the ALT are discussed.Results indicated that the AMDSSP was more flexible and efficient for ASN and TC than the MDSSP and SSP plans under accelerated conditions.The AMDSSP also had a higher operating characteristic(OC)curve than both the existing sampling plans.Two real datasets of electronic devices for the ALT at high temperatures demonstrated the practicality and usefulness of the proposed sampling plan. 展开更多
关键词 accelerated life test acceleration factor adaptive of multiple dependent state sampling plan average sample number total cost of inspection weibull distribution
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Model Associated with the Study of the Degradation Based on the Accelerated Test: A Literature Review 被引量:1
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作者 Fatou Dia Nacire Mbengue +6 位作者 Omar Ngalla Sarr Moulaye Diagne Omar A. Niasse Awa Dieye Mor Niang Bassirou Ba Cheikh Sene 《Open Journal of Applied Sciences》 2016年第1期49-63,共15页
Most manufacturers of solar modules guarantee the minimum performance of their modules for 20 to 25 years, and 30-year warranties have been introduced. The warranty typically guarantees that the modules will perform t... Most manufacturers of solar modules guarantee the minimum performance of their modules for 20 to 25 years, and 30-year warranties have been introduced. The warranty typically guarantees that the modules will perform to at least 90% capacity in the first 10 years and to at least 80% in the following 10 - 15 years. Early degradation resulting from design flaws, materials or processing issues is often apparent from startup to the first few years in service. Importantly, many module failures and performance losses are the result of gradual accumulated damage resulting from long-term outdoor exposure in harsh environments, referred. Many of these processes occur on relatively long time scales and the various degradation processes may be chemical, electrical, thermal or mechanical in nature. These are either initiated or accelerated by the combined stresses of the service environment, in particular solar radiation, temperature and moisture, and other stresses such as salt air, wind and snow. Accelerated Life Testing (ALT) test methodology is normally predicated on first being able to reproduce a specific degradation or failure mode without altering it (correlation);and, second, to produce that result in less than real-time acceleration. Degradation and failure may result when an applied stress exceeds material or product strength. This may be a one-time catastrophic event, the result of cyclic fatigue, or a gradual decline in requisite properties due to ageing mechanisms. Engineers in the manufacturing industries have used accelerated test (AT) experiments for many decades. The purpose of AT experiments is to acquire reliability information quickly. Test units of a material, component, subsystem or entire systems are subjected to higher-than-usual levels of one or more accelerating variables such as temperature or stress. Then the AT results are used to predict life of the units at use conditions. The extrapolation is typically justified (correctly or incorrectly) on the basis of physically motivated models or a combination of empirical model fitting with a sufficient amount of previous experience in testing similar units. The need to extrapolate in both time and the accelerating variables generally necessitates the use of fully parametric models. Statisticians have made important contributions in the development of appropriate stochastic models for AT data [typically a distribution for the response and regression relationships between the parameters of this distribution and the accelerating variable(s)], statistical methods for AT planning (choice of accelerating variable levels and allocation of available test units to those levels) and methods of estimation of suitable reliability metrics. This paper provides a review of many of the AT models that have been used successfully in this area. 展开更多
关键词 DEGRADATION acceleration factor Arrhenius Relationship Eyring Relationship Inverse Power Relationship Voltage-Stress PHOTODEGRADATION
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Impact of Accelerated Stresses on Power Transformer Insulation
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作者 Jashandeep Singh Yog Raj Sood Piush Verma 《Energy and Power Engineering》 2017年第4期217-231,共15页
The paper is based on the experimental investigation of accelerated stresses on insulation of power transformer. The effects of individual thermal and electrical stresses have been graphically presented. The factors a... The paper is based on the experimental investigation of accelerated stresses on insulation of power transformer. The effects of individual thermal and electrical stresses have been graphically presented. The factors accelerated thermal aging factor (ATAF) and accelerated electrical aging factor (AEAF) have been introduced, it helps to understand the contribution of thermal and electrical stresses and degradation trends of insulating properties. The accelerated aging factors have been mathematically correlated with different properties of insulation such as moisture, breakdown voltage (BDV), tan delta and resistivity. These parameters were determined experimentally for fresh oil samples and for samples subjected to accelerated aging. 展开更多
关键词 accelerATED Thermal AGING factor (ATAF) accelerATED Electrical AGING factor (AEAF) Moisture Breakdown Voltage (BDV) RESISTIVITY TAN Delta
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A study of grid failure mode drivers and methods for accelerated life testing of a 30cm diameter ion thruster
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作者 孙明明 龙建飞 +3 位作者 陈娟娟 杨威 郭伟龙 陈新伟 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第11期122-132,共11页
In view of the high cost caused by the 1:1 lifetime verification test of ion thrusters,the lifetime acceleration test should be considered.This work uses the PIC-MCC(Particle-in-Cell MonteCarlo Collision)method to ana... In view of the high cost caused by the 1:1 lifetime verification test of ion thrusters,the lifetime acceleration test should be considered.This work uses the PIC-MCC(Particle-in-Cell MonteCarlo Collision)method to analyze the five failure factors that lead to the failure of the accelerator grid of a 30 cm diameter ion thruster under the working mode of 5 k W.Meanwhile,the acceleration stress levels corresponding to different failure factors are obtained.The results show that background pressure has the highest stress level on the grid's erosion.The accelerator grid aperture's mass sputtering rate under the rated vacuum degree(1×10^(-4)Pa)of 5 k W work mode is 8.78 times that of the baseline vacuum degree(1×10^(-6)Pa),and the mass sputtering rate under worse vacuum degree(5×10^(-3)Pa)is 5.08 times that of 1×10^(-4)Pa.Under the influence of the other four failure factors,namely,the voltage of the accelerator grid,upstream plasma density,the screen grid voltage and mass utilization efficiency,the mass sputtering rates of the accelerator grid hole are 2.32,2.67,1.98 and 2.51 times those of the accelerator grid hole under baseline condition,respectively.The ion sputtering results of two 30 cm diameter ion thrusters(both installed with new grids assembly)after working for 1000 h show that the mass sputtering rate of the accelerator grid hole under vacuum conditions of 5×10^(-3)Pa is 4.54 times that under the condition of 1×10^(-4)Pa,and the comparison error between simulation results and test results of acceleration stress is about 10%.In the subsequent ion thruster lifetime verification,the working vacuum degree can be adjusted according to the acceleration stress level of background pressure,so as to shorten the test time and reduce the test cost. 展开更多
关键词 ion thruster failure factors acceleration stress level
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Hyperhomocysteinemia: Risk Factors and Faster Onset of Degenerative Complications of Type 2 Diabetes in Brazzaville
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作者 Ikia Monde Valsy Russelh Evariste Bouenizabila +15 位作者 Farel Elilie Mawa Ongoth Raissa Laure Mayanda Ohouna Aymande Okoumou-Moko Paulin Kibeke Ghislain Loubano-Voumbi Luc Magloire Boumba Anicet Wilson Fabrice Ondongo Mayindou Kimbangu Archimède Gotran Tienelle Freiss Mabiala Wann Koumou Onanga Thierry Raoul Ngombea Benjamin Longo Mbenza Edouard Ngou Milama Christian Andres Etienne Mokondjimobe Henri Germain Monabeka 《Journal of Diabetes Mellitus》 2023年第3期257-267,共11页
Background: Type 2 diabetes (T2D) remains a major global public health problem. This complex metabolic disorder can lead to various complications, including cardiovascular diseases (leading cause of death) in T2D. Amo... Background: Type 2 diabetes (T2D) remains a major global public health problem. This complex metabolic disorder can lead to various complications, including cardiovascular diseases (leading cause of death) in T2D. Among the biochemical markers associated with increased risk for cardiovascular disease, homocysteine is currently one of the predictive markers under evaluation. We investigate the link between hyperhomocysteinemia and diabetes complications in DT2 population in Brazzaville. Methodology: We conducted a cross-sectional analytical study, from October to December 2022. One hundred and fifty participants were included, 100 patients T2D (34 with complications, 33 with comorbidities, 33 without), and 50 patients controls. Sociodemographic and clinical characteristics were collected. Homocysteine (Hcy) serum levels were measured using Sandwich ELISA method. Results: Study population was composed of 50% males and 50% females with sex ratio of 1;mean age was 52.2 ± 10.8 years (30 - 83). The prevalence of hyperhomocysteinemia (HHcy) was 36% (20% moderate Hcy, 15% intermediate and 1% severe). Mean Hcy concentration was 31.9 μmol/l (18 - 103). Age, gender and physical inactivity were strongly correlated to Hcy (OR of 3.5;9.4 and 3 respectively). Multivariate analysis showed that HHcy was a risk accelerator for degenerative complications (stroke: OR = 6.2;ischemic heart disease: 4.9;neuropathy: 9.2;retinopathy: 4.5 and peripheral arterial disease: 4.9). Conclusion: These findings suggest that hyperhomocysteinemia can be considered as a predictive marker to be taken into account in targeting cardiovascular risk in Congolese subjects with T2D. 展开更多
关键词 HYPERHOMOCYSTEINEMIA Patients with T2D Risk factor acceleration factor Degenerative Complications CONGO
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Multiple dependent reliability estimation of large range MEMS accelerometers in high temperature environment
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作者 QIN Li HE Cheng +2 位作者 YU Li-xia WANG Wei QIN Li-jun 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2019年第1期9-15,共7页
In the past,only one performance parameter was considered in the reliability estimation of micro-electro-mechanical system (MEMS) accelerometers,resulting in a one-sided reliability evaluation. Aiming at the failure c... In the past,only one performance parameter was considered in the reliability estimation of micro-electro-mechanical system (MEMS) accelerometers,resulting in a one-sided reliability evaluation. Aiming at the failure condition of large range MEMS accelerometers in high temperature environment,the corresponding accelerated degradation test is designed. According to the degradation condition of zero bias and scale factor,multiple dependent reliability estimation of large range MEMS accelerometers is carried out. The results show that the multiple dependent reliability estimation of the large range MEMS accelerometers can improve the accuracy of the estimation and get more accurate results. 展开更多
关键词 large range MEMS accelerometers zero bias scale factor multiple dependent reliability estimation accelerated degradation test
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