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Area-time associated test cost model for SoC and lower bound of test time
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作者 张金艺 翁寒一 +1 位作者 黄徐辉 蔡万林 《Journal of Shanghai University(English Edition)》 CAS 2011年第1期43-48,共6页
A novel test access mechanism (TAM) architecture with multi test-channel (TC) based on IEEE Standard 1500 is proposed instead of the traditional sub-TAM structure. The cost model of an area-time associated test an... A novel test access mechanism (TAM) architecture with multi test-channel (TC) based on IEEE Standard 1500 is proposed instead of the traditional sub-TAM structure. The cost model of an area-time associated test and the corresponding lower bound of system-on-chip (SoC) test time are established based on this TAM architecture. The model provides a more reliable method to control the SoC scheduling and reduces the complexity in related algorithm research. The result based on the area time associated test cost model has been validated using the ITC02 test benchmark. 展开更多
关键词 system-on-chip design for testability (SoC DriP) test cost test time lower bound
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Modified DS np Chart Using Generalized Multiple Dependent State Sampling under Time Truncated Life Test
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作者 Wimonmas Bamrungsetthapong Pramote Charongrattanasakul 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第3期2471-2495,共25页
This study presents the design of a modified attributed control chart based on a double sampling(DS)np chart applied in combination with generalized multiple dependent state(GMDS)sampling to monitor the mean life of t... This study presents the design of a modified attributed control chart based on a double sampling(DS)np chart applied in combination with generalized multiple dependent state(GMDS)sampling to monitor the mean life of the product based on the time truncated life test employing theWeibull distribution.The control chart developed supports the examination of the mean lifespan variation for a particular product in the process of manufacturing.Three control limit levels are used:the warning control limit,inner control limit,and outer control limit.Together,they enhance the capability for variation detection.A genetic algorithm can be used for optimization during the in-control process,whereby the optimal parameters can be established for the proposed control chart.The control chart performance is assessed using the average run length,while the influence of the model parameters upon the control chart solution is assessed via sensitivity analysis based on an orthogonal experimental design withmultiple linear regression.A comparative study was conducted based on the out-of-control average run length,in which the developed control chart offered greater sensitivity in the detection of process shifts while making use of smaller samples on average than is the case for existing control charts.Finally,to exhibit the utility of the developed control chart,this paper presents its application using simulated data with parameters drawn from the real set of data. 展开更多
关键词 Modified DS np chart generalizedmultiple dependent state sampling time truncated life test Weibull distribution average run length average sample size
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Statistical Properties and Confidence Limits about the Mean Time between the Failures (MTBF) in Failure-free Period Life Test (FFPLT)
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作者 王庆成 《Chinese Quarterly Journal of Mathematics》 CSCD 2001年第1期9-19,共11页
On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and correspond... On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and corresponding calculating formulae are found out. 展开更多
关键词 FFPLT MTBF operating characteristic (OC) function expected test time (ETT) maximum likelihood estimation lower confidence limit
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A Novel Multiple Dependent State Sampling Plan Based on Time Truncated Life Tests Using Mean Lifetime 被引量:1
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作者 Pramote Charongrattanasakul Wimonmas Bamrungsetthapong Poom Kumam 《Computers, Materials & Continua》 SCIE EI 2022年第12期4611-4626,共16页
The design of a new adaptive version of the multiple dependent state(AMDS)sampling plan is presented based on the time truncated life test under the Weibull distribution.We achieved the proposed sampling plan by apply... The design of a new adaptive version of the multiple dependent state(AMDS)sampling plan is presented based on the time truncated life test under the Weibull distribution.We achieved the proposed sampling plan by applying the concept of the double sampling plan and existing multiple dependent state sampling plans.A warning sign for acceptance number was proposed to increase the probability of current lot acceptance.The optimal plan parameters were determined simultaneously with nonlinear optimization problems under the producer’s risk and consumer’s risk.A simulation study was presented to support the proposed sampling plan.A comparison between the proposed and existing sampling plans,namely multiple dependent state(MDS)sampling plans and a modified multiple dependent state(MMDS)sampling plan,was considered under the average sampling number and operating characteristic curve values.In addition,the use of two real datasets demonstrated the practicality and usefulness of the proposed sampling plan.The results indicated that the proposed plan is more flexible and efficient in terms of the average sample number compared to the existing MDS and MMDS sampling plans. 展开更多
关键词 Adaptive version of multiple dependent state sampling plan time truncated life test quality level weibull distribution mean lifetime
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Determination of the Minimum Testing Time for Wireline Formation Testing with the Finite Element Method
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作者 Hu Falong Xiao Lizhi +1 位作者 Zhang Yuanzhong Wang Chengwei 《Petroleum Science》 SCIE CAS CSCD 2006年第1期39-44,共6页
The wireline formation tester (WFT) is an important tool for formation evaluation, such as calculating the formation pressure and permeability, identifying the fluid type, and determining the interface between oil a... The wireline formation tester (WFT) is an important tool for formation evaluation, such as calculating the formation pressure and permeability, identifying the fluid type, and determining the interface between oil and water. However, in a low porosity and low permeability formation, the supercharge pressure effect exists, since the mudcake has a poor sealing ability. The mudcake cannot isolate the hydrostatic pressure of the formation around the borehole and the mud seeps into the formations, leading to inaccurate formation pressure measurement. At the same time, the tool can be easily stuck in the low porosity/low permeability formation due to the long waiting and testing time. We present a method for determining the minimum testing time for the wireline formation tester. The pressure distribution of the mudcake and the formation were respectively calculated with the finite element method (FEM). The radius of the influence of mud pressure was also computed, and the minimum testing time in low porosity/low permeability formations was determined within a range of values for different formation permeabilities. The determination of the minimum testing time ensures an accurate formation pressure measurement and minimizes possible accidents due to long waiting and testing time. 展开更多
关键词 Wireline formation tester the minimum testing time the finite element method
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Changes in reaction time, coefficient of variance of reaction time, and autonomic nerve function in the mental fatigue state caused by long-term computerized Kraepelin test workload in healthy volunteers 被引量:1
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作者 Daisuke Kuratsune Seiki Tajima +10 位作者 Junichi Koizumi Kouzi Yamaguti Tetsuya Sasabe Kei Mizuno Masaaki Tanaka Naoko Okawa Hideki Mito Hirokazu Tsubone Yasuyoshi Watanabe Masayasu Inoue Hirohiko Kuratsune 《World Journal of Neuroscience》 2012年第2期113-118,共6页
Fatigue is a common sense caused by crushing labor, stressful social events and various illnesses. It is usually judged by their subjective symptoms, but it should be evaluated in an objective perspective. Here we sho... Fatigue is a common sense caused by crushing labor, stressful social events and various illnesses. It is usually judged by their subjective symptoms, but it should be evaluated in an objective perspective. Here we show that the decrease of working efficiency and sympathetic hyperactivity are associated with mental fatigue state caused by prolonged mental workload. Recently we made a new mental fatigue model of healthy volunteers caused by long-term computerized Kraepelin test (CKT) workload. CKT is our new software for automatically checking the calculation capability, with which it is easy to determine the reaction time (RT), coefficient of variance of reaction time (CV), and accuracy of the answers (AC) during tasks. We put 24 healthy volunteers into the fatigue state by subjecting them to 120 minutes’ CKT workload, and then studied the changes in fatigue sensation, RT, CV, and AC before and after the CKT workload. The fatigue sensation, RT, and CV were clearly increased by the fatigue-inducing task and recovered during the resting period. We also studied the changes in autonomic nerve activity by using heart rate variability analysis. The low/high frequency component ratio (LF/HF) was signifi-cantly increased by the fatigue-inducing task and decreased by resting, suggesting that mental stress causes a relatively sympathetic nerve activity-dominant state. Therefore, our new fatigue model involving a long-term CKT workload is a good mental fatigue model to provide much information about the fatigue state simultane-ously, and the increase of RT, CV, and proportion of sympathetic activity (LF/HF) are associated with mental fatigue state. These might be useful objective biomarkers or evaluating a mental fatigue state. 展开更多
关键词 Fatigue COMPUTERIZED Kraepelin test Reaction time Accuracy of the ANSWERS AUTONOMIC NERVE Activity
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On modeling approach for embedded real-time software simulation testing 被引量:6
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作者 Yin Yongfeng Liu Bin Zhong Deming Jiang Tongmin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第2期420-426,共7页
Modeling technology has been introduced into software testing field. However, how to carry through the testing modeling effectively is still a difficulty. Based on combination of simulation modeling technology and emb... Modeling technology has been introduced into software testing field. However, how to carry through the testing modeling effectively is still a difficulty. Based on combination of simulation modeling technology and embedded real-time software testing method, the process of simulation testing modeling is studied first. And then, the supporting environment of simulation testing modeling is put forward. Furthermore, an approach of embedded real-time software simulation testing modeling including modeling of cross-linked equipments of system under testing (SUT), test case, testing scheduling, and testing system service is brought forward. Finally, the formalized description and execution system of testing models are given, with which we can realize real-time, closed loop, mad automated system testing for embedded real-time software. 展开更多
关键词 embedded real-time software software testing testing modeling SIMULATION
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A new nonparametric stability test with an application to major Chinese macroeconomic time series
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作者 CAI Nan CAI Zong-wu FANG Ying 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2013年第1期1-16,共16页
In this paper, we propose a new test for testing the stability in macroeconomic time series, based on the LASSO variable selection approach and nonparametric estimation of a time-varying model. The wild bootstrap is e... In this paper, we propose a new test for testing the stability in macroeconomic time series, based on the LASSO variable selection approach and nonparametric estimation of a time-varying model. The wild bootstrap is employed to obtain its data-dependent critical values. We apply the new method to test the stability of bivariate relations among 92 major Chinese macroeconomic time series. We find that more than 70% bivariate relations are significantly unstable. 展开更多
关键词 LASSO stability test time-varying coefficients model wild bootstrap.
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Topographic tear film trend and new parameters for noninvasive break up time test
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作者 Yakup Acet 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2022年第12期1932-1939,共8页
AIM:To evaluate the quantitative and qualitative results of the noninvasive tear film break-up time(NI-BUT)test and investigate the predictive ability of the new NIBUT parameter in discriminating between normal Ocular... AIM:To evaluate the quantitative and qualitative results of the noninvasive tear film break-up time(NI-BUT)test and investigate the predictive ability of the new NIBUT parameter in discriminating between normal Ocular Surface Disease Index(OSDI;scores≤12)and abnormal OSDI(scores≥13).METHODS:A total of 341 eyes of 341 volunteers who applied for routine eye outpatient control were included in the prospective study.All participants'noninvasive first tear film break-up time(NIF-BUT),noninvasive average tear film break-up time(NIAvg-BUT)and average value of the first three break-up time(A3F-BUT)were analyzed.A3F-BUT,the new NI-BUT parameter,is calculated by adding the NIF-BUT value to the 2^(nd )break-up time value that has a difference of at most 1 second from the NIF-BUT value and to the 3^(rd) break-up time and then dividing the respective sum by 3.Receiver operating characteristic(ROC)curve and forward logistic regression analyses were performed to determine the parameter that had the best predictive ability between the OSDI groups.RESULTS:The NI-BUT values of 255 eyes of 255 volunteers included in the study were analyzed statistically.The mean NIF-BUT,NIAvg-BUT,and A3F-BUT values were calculated as 5.3±3.0,8±3.1,and 5.8±3.0 seconds,respectively.All three parameters were found to be significantly lower in the abnormal OSDI group(P=0.014,0.034,and 0.011,respectively).The area under the curve(AUC)of the A3F-BUT to predict abnormal OSDI was AUC=0.625(0.529-0.720),P=0.011 and NIF-BUT was AUC=0.599(0.502-0.696),P=0.043.The A3F-BUT parameter and NIF-BUT parameters were found to be significantly efficient in discriminating abnormal OSDI.CONCLUSION:The new parameter for the NI-BUT test has more predictive ability in the discrimination of OSDI groups. 展开更多
关键词 noninvasive break-up time Ocular Surface Disease Index tear film topographic break-up time test
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An Automatic Testing System of Scheduling Strategies in Real-Time UNIX
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作者 Qin Xiao, Pang Liping & Han Zongfen Department of Computer Science, Huazhong University of Science and Technology, Wuhan 430074, P. R. China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2001年第2期59-62,共4页
This paper proposes a formal model of the automatic testing system for scheduling strategies in real-time UNIX and describes the algorithm of the key part of the system. The model of the system is an important technol... This paper proposes a formal model of the automatic testing system for scheduling strategies in real-time UNIX and describes the algorithm of the key part of the system. The model of the system is an important technology of the automatization of software development. According to the model presented in the paper, many different kinds of automatic testing systems can be designed and developed easily. At the end of the paper, the prototype proves the feasibility of the model and design. 展开更多
关键词 ALGORITHMS Automatic testing Real time systems SCHEDULING Software prototyping
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基于Simulink Real-Time的汽车空调半实物仿真试验系统研发 被引量:1
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作者 姚栋伟 吴晓虎 +4 位作者 卢鑫威 张永光 付忠亮 黄忠毅 吴锋 《国外电子测量技术》 北大核心 2023年第9期114-121,共8页
针对多样化汽车空调电子零部件的高效、低成本总成级测试需求,研究基于一汽大众速腾1.6 L车型原型,设计了基于Simulink Real-Time的汽车空调半实物仿真试验系统。该系统集成了真实的汽车空调总成、制冷循环以及包含宿主机和目标机的双... 针对多样化汽车空调电子零部件的高效、低成本总成级测试需求,研究基于一汽大众速腾1.6 L车型原型,设计了基于Simulink Real-Time的汽车空调半实物仿真试验系统。该系统集成了真实的汽车空调总成、制冷循环以及包含宿主机和目标机的双机实时仿真系统,用于开发和运行台架监控和空调控制模型,为汽车空调电子零部件提供半实物仿真测试环境。通过系统集成及功能验证,结果表明,汽车空调半实物仿真试验系统能够实现汽车空调基本控制功能,同时在不同工况下实现乘员舱温度控制的稳定性,稳态误差控制在±1℃以内。此外,该系统还具备灵活调整空调运行工况和状态的能力,为汽车空调电子零部件提供了高效、低成本的半实物仿真测试环境。 展开更多
关键词 Simulink Real-time 汽车空调 半实物仿真 仿真模型 试验系统
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Delay-dependent stability and added damping of SDOF real-time dynamic hybrid testing 被引量:14
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作者 Chi Fudong Wang Jinting Jin Feng 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2010年第3期425-438,共14页
It is well-recognized that a transfer system response delay that reduces the test stability inevitably exists in real-time dynamic hybrid testing (RTDHT). This paper focuses on the delay-dependent stability and adde... It is well-recognized that a transfer system response delay that reduces the test stability inevitably exists in real-time dynamic hybrid testing (RTDHT). This paper focuses on the delay-dependent stability and added damping of SDOF systems in RTDHT. The exponential delay term is transferred into a rational fraction by the Pad6 approximation, and the delay-dependent stability conditions and instability mechanism of SDOF RTDHT systems are investigated by the root locus technique. First, the stability conditions are discussed separately for the cases of stiffness, mass, and damping experimental substructure. The use of root locus plots shows that the added damping effect and instability mechanism for mass are different from those for stiffness. For the stiffness experimental substructure case, the instability results from the inherent mode because of an obvious negative damping effect of the delay. For the mass case, the delay introduces an equivalent positive damping into the inherent mode, and instability occurs at an added high frequency mode. Then, the compound stability condition is investigated for a general case and the results show that the mass ratio may have both upper and lower limits to remain stable. Finally, a high-emulational virtual shaking table model is built to validate the stability conclusions. 展开更多
关键词 real-time dynamic hybrid testing root locus analysis delay-dependent stability Pade approximation added damping
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Design and Analysis of Test Schemes of Static Postponing Time on Shrapnels Used to Riot Control
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作者 单永海 闵碧波 孙国基 《Defence Technology(防务技术)》 SCIE EI CAS 2006年第2期102-105,共4页
The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and thr... The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and three kinds of pressures, the consumed ammunitions are more excessive. Statistic analysis and tentative checkout about a lot of test data are done, feasibility gists are put forward for optimizing of the test design scheme. The optimizing design and data analysis of test scheme of the item are done by managing uniformity design theory, two scientific and reasonable six-point test schemes are confirmed. The feasibility and reliability of the optimizing design schemes put forward above are proved ulteriorly by test validating. The gained schemes not only have good design uniformity and little ammunition wastage and meet the test demand, but also have better forecast ability for the result data of other points using the mathematic models from the actual test points. 展开更多
关键词 防暴动榴弹 延时 测试计划 静态定位
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Simulation of large-scale numerical substructure in real-time dynamic hybrid testing 被引量:7
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作者 Zhu Fei Wang Jinting +2 位作者 Jin Feng Zhou Mengxia Gui Yao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2014年第4期599-609,共11页
A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element (FE) numerical substructures. The analysis of the FE numerical substructure is split into response anal... A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element (FE) numerical substructures. The analysis of the FE numerical substructure is split into response analysis and signal generation tasks, and executed in two different target computers in real-time. One target computer implements the response analysis task, wherein a large time-step is used to solve the FE substructure, and another target computer implements the signal generation task, wherein an interpolation program is used to generate control signals in a small time-step to meet the input demand of the controller. By using this strategy, the scale of the FE numerical substructure simulation may be increased significantly. The proposed scheme is initially verified by two FE numerical substructure models with 98 and 1240 degrees of freedom (DOFs). Thereafter, RTDHTs of a single frame-foundation structure are implemented where the foundation, considered as the numerical substructure, is simulated by the FE model with 1240 DOFs. Good agreements between the results of the RTDHT and those from the FE analysis in ABAQUS are obtained. 展开更多
关键词 real-time dynamic hybrid testing large-scale numerical substructure control signal generation finite element simulation
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Velocity plus displacement equivalent force control for real-time substructure testing 被引量:1
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作者 Zhou Huimeng D.Wagg Wang Tao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第1期87-102,共16页
This paper employs a velocity plus displacement(V+D)-based equivalent force control(EFC) method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 fee... This paper employs a velocity plus displacement(V+D)-based equivalent force control(EFC) method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 feedback control loops to replace mathematical iteration to solve the nonlinear dynamic equation. A spectral radius analysis of the amplification matrix shows that the type 2 EFC-explicit, Newmark-β method has beneficial numerical characteristics for this method. Its stability limit of Ω = 2 remains unchanged regardless of the system damping because the velocity is achieved with very high accuracy during simulation. In contrast, the stability limits of the central difference method using direct velocity prediction and the EFC-average acceleration method with linear interpolation are shown to decrease with an increase in system damping. In fact, the EFC-average acceleration method is shown to change from unconditionally stable to conditionally stable. We also show that if an over-damped system with a damping ratio of 1.05 is considered, the stability limit is reduced to Ω =1.45. Finally, the results from an experiment with a single-degree-of-freedom structure installed with a magneto-rheological(MR) damper are presented. The results demonstrate that the proposed method is able to follow both displacement and velocity commands with moderate accuracy, resulting in improved test performance and accuracy for structures that are sensitive to both velocity and displacement inputs. Although the findings of the study are promising, additional test data and several further improvements will be required to draw general conclusions. 展开更多
关键词 real-time substructure test EFC velocity/displacement control newmark-β method stability
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A Study of Visual Event-Related Potential and Reaction Time in Elderly People: Comparative Analysis of the Scores of Intelligence Test in 30 Subjects
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作者 杨文俊 潘速跃 《Journal of Medical Colleges of PLA(China)》 CAS 1990年第3期222-226,共5页
The results of visual event-related potential(ERP)examinations and reactiontime(RT)tests were reported in 30 elders and compared with their performanceintellegence quotient(PIQ)scores.The subjects consisted of 18 male... The results of visual event-related potential(ERP)examinations and reactiontime(RT)tests were reported in 30 elders and compared with their performanceintellegence quotient(PIQ)scores.The subjects consisted of 18 males and 12 femalesaged 50-71(mean 61.4)years old.No history of central nervous system disease wasfound.The visual stimuli were randomly presented to the subject,including three sym-bols:E as target stimulus with 0.15 probability,and H and E as nontarget stimuliwith 0.15 and 0.70 probability respectively.The recording electrodes were placed on Fzand Pz.The duration from the subject seeing the target to touching a button immediatelywas considered as reaction time(RT).It was shown that the P3 latency at Pz was longer than that at Fz and the P3amplitude at Pz was larger than that at Fz,and that the RT was longer than P3 latencywith obvious effect of distribution(P【0.05 at Fz and P】0.05 at Pz)as well .The higherthe PIQ scores,the longer the RT and the P3 latency.It is suggested that the ERPmight reflect the differences of PIQ scores,and the P3 is an objective index.We considerthat the research of ERP is of great interest in the neuropsychological and neurological sci-ences. 展开更多
关键词 ELDER EVENT-RELATED potential REACTION time INTELLIGENCE test
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The Study of Relaxation Time in Test of 940 nm Semiconductor Laser
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作者 Jiachun Li Jianjun Li +5 位作者 Tao Liu Bifeng Cui Jun Deng Jun Han Linjie He Shengjie Lin 《Journal of Computer and Communications》 2013年第7期46-49,共4页
Conventional test of the peak wavelength of a laser used to be applied immediately after a device is injected current. However, the results can not be considered as an accurate description to temperature characteristi... Conventional test of the peak wavelength of a laser used to be applied immediately after a device is injected current. However, the results can not be considered as an accurate description to temperature characteristic. This passage puts forward a concept of relaxation time in wavelength texts, mainly based on the experiment of 940 nm strain quantum well laser, confirming that under constant current, wavelength will get through a process of rising, and then, reach the limit. This process brings the effect on spectral characteristics of a device which cannot be ignored and the accumulated heat in relaxation time will gradually impact the emission wavelength of the laser, even crest split to form bimodal phenomenon. 展开更多
关键词 SEMICONDUCTOR Laser test TEMPERATURE Characteristics RELAXATION time
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Research on multi-time scale doubly-fed wind turbine test system based on FPGA+CPU heterogeneous calculation
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作者 Qing Mu Xing Zhang +3 位作者 Xiaoxin Zhou Xiaowei Fan Yingmei Liu Dongbo Pan 《Global Energy Interconnection》 2019年第1期7-18,共12页
As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and m... As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and more important. Traditional dynamic simulation systems and digital-analog hybrid simulation systems are difficult to compromise on the economy, flexibility and accuracy. A multi-time scale test system of doubly fed induction generator based on FPGA+ CPU heterogeneous calculation is proposed in this paper. The proposed test system is based on the ADPSS simulation platform. The power circuit part of the test system is setup up using the EMT(electromagnetic transient simulation) simulation, and the control part uses the actual physical devices. In order to realize the close-loop testing for the physical devices, the power circuit must be simulated in real-time. This paper proposes a multi-time scale simulation algorithm, in which the decoupling component divides the power circuit into a large time scale system and a small time scale system in order to reduce computing effort. This paper also proposes the FPGA+CPU heterogeneous computing architecture for implementing this multitime scale simulation. In FPGA, there is a complete small time-scale EMT engine, which support the flexibly circuit modeling with any topology. Finally, the test system is connected to an DFIG controller based on Labview to verify the feasibility of the test system. 展开更多
关键词 Renewable energy gen erati on DOUBLY fed in duction generator ADPSS simulati on SYSTEM Wind turbine test SYSTEM Multi-time scale FPGA+CPU
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变厚度CFRP超声缺陷自动成像的相关性算法研究
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作者 王涛 邓婉欣 +1 位作者 王海军 俞慈君 《振动与冲击》 EI CSCD 北大核心 2024年第12期232-240,共9页
针对变厚度碳纤维增强聚合物复合材料(carbon fiber reinforced polymer,CFRP)超声缺陷成像工序繁琐的问题,提出了一种基于相关性的自动成像算法。试验预埋夹杂缺陷,使用超声相控阵检测获取数据,首先依据离散序列互相关理论,对不同厚度C... 针对变厚度碳纤维增强聚合物复合材料(carbon fiber reinforced polymer,CFRP)超声缺陷成像工序繁琐的问题,提出了一种基于相关性的自动成像算法。试验预埋夹杂缺陷,使用超声相控阵检测获取数据,首先依据离散序列互相关理论,对不同厚度CFRP的超声A扫描信号进行底波时移处理,之后利用自相关理论从无缺陷区域生成必要的参考信号。通过相关计算结果,利用欧氏距离区分缺陷信号和非缺陷信号,并依据欧式距离进行颜色编码绘图。最后通过基于机器视觉以及Hough圆变换的边缘检测算法来对缺陷尺寸进行统计测量,总体均值误差率小于7%,最大误差率为16.25%,最小误差率为0.25%。结果表明该算法可广泛应用于变厚度CFRP自动化超声检测。 展开更多
关键词 变厚度复合材料 超声检测 时移 自相关
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Properties of Time-Varying Causality Tests in the Presence of Multivariate Stochastic Volatility
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作者 Daiki Maki 《Open Journal of Statistics》 2016年第5期777-788,共13页
This paper compares the statistical properties of time-varying causality tests when errors of variables have multivariate stochastic volatility (SV). The time-varying causal-ity tests in this paper are based on a logi... This paper compares the statistical properties of time-varying causality tests when errors of variables have multivariate stochastic volatility (SV). The time-varying causal-ity tests in this paper are based on a logistic smooth transition autoregressive model. The compared time-varying causality tests include asymptotic tests, heteroskedasticity-robust tests, and tests using wild bootstrap. Our simulation results show that asymptotic tests and heteroskedasticity-robust counterparts have size distortions under multivariate SV, whereas tests using wild bootstrap have better size properties regardless of type of error. In particular, the time-varying causality test with first-order Taylor approximation using wild bootstrap has better statistical properties. 展开更多
关键词 time-Varying Causality tests Wild Bootstrap Multivariate Stochastic Volatility
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