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突发灾害下城市路网交通流可靠性运行态势 被引量:5
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作者 林赐云 王琳虹 +2 位作者 龚勃文 赵丁选 杨兆升 《吉林大学学报(工学版)》 EI CAS CSCD 北大核心 2012年第3期581-587,共7页
为了识别突发灾害下交通流运行过程中路网可靠性的变化规律和潜在的运行态势,采用Rough集理论,结合城市道路交通状态判别、预测的知识,构建了突发灾害下路网可靠性知识表达系统。通过对路网元素属性数值的离散化处理,路网可靠性决策表... 为了识别突发灾害下交通流运行过程中路网可靠性的变化规律和潜在的运行态势,采用Rough集理论,结合城市道路交通状态判别、预测的知识,构建了突发灾害下路网可靠性知识表达系统。通过对路网元素属性数值的离散化处理,路网可靠性决策表的属性约简等一系列操作过程,实现了对路网可靠性运行态势的逻辑推理。试验结果表明:路网可靠性能够较好地拟合突发灾害下路网交通流的运行特征,交通路网可靠性态势分析的知识表达系统对可靠度的预测精度可达90%以上。 展开更多
关键词 交通运输系统工程 交通流可靠性 突发灾害 粗集理论 交通态势估计
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基于不确定图的最可靠最大流的改进算法 被引量:2
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作者 张柏礼 杨娟 +1 位作者 吕建华 田伟 《东南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2015年第2期241-246,共6页
针对网络规模和稠密度的增大最可靠最大流SDBA算法性能下降较快的不足,提出了基于概率和割集双过滤的状态空间划分算法DF-SDBA.首先,在状态空间划分过程中使用概率约束,针对每一个待处理的区间,筛选掉下界分布概率值小于当前最可靠最大... 针对网络规模和稠密度的增大最可靠最大流SDBA算法性能下降较快的不足,提出了基于概率和割集双过滤的状态空间划分算法DF-SDBA.首先,在状态空间划分过程中使用概率约束,针对每一个待处理的区间,筛选掉下界分布概率值小于当前最可靠最大流分布的未处理区间,有效地减少了算法迭代的次数;然后,针对不确定的区间使用割集约束,即在区间上界对应的子图中求出最大流,同时求出最小割集,根据最小割集中的边必须都出现在合格子区间上界向量中这一规则,对待划分的子区间进行筛选,从而进一步减少了划分区间的数量.实验结果表明,相对于SDBA算法,DF-SDBA算法有效地减少了需要划分的区间,很大程度上克服了网络规模和稠密度对算法性能的影响,具有显著的性能优势,有效地提高了算法的适用性. 展开更多
关键词 不确定图 最大 流可靠性 最小割
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一种不确定图中最可靠最大流问题的解决方案 被引量:2
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作者 张柏礼 吕建华 +1 位作者 生衍 田伟 《计算机学报》 EI CSCD 北大核心 2014年第10期2084-2095,共12页
最可靠最大流是不确定图中可靠性最高的最大流,它是传统最大流问题在不确定图上的自然延伸.现有的最可靠最大流算法SDBA时间复杂性较高,无法满足实际中不同应用的需求,为此,文中提出一种具有普遍适用性的最可靠最大流解决方案.该方案包... 最可靠最大流是不确定图中可靠性最高的最大流,它是传统最大流问题在不确定图上的自然延伸.现有的最可靠最大流算法SDBA时间复杂性较高,无法满足实际中不同应用的需求,为此,文中提出一种具有普遍适用性的最可靠最大流解决方案.该方案包含面向不同需求的3种算法:基于负权群落消去的NWCE算法、基于时间约束优先单环消去的SPEA-t算法和基于概率阈值约束优先单环消去的SPEA-p算法.其中,NWCE算法借鉴最小费用最大流的"流平移"思想并基于文中提出的负权群落概念,在辅助剩余图中不断地消去可使可靠性增加而流量不变的负权群落,可证当消去所有负权群落时对应的最大流即为最可靠最大流.根据负权群落中由单环组成的群落占很高比例且相对于多环组成的群落更易查找和消去的性质,同时考虑到NWCE算法为了获得最优解,往往为了消去最后少数几个对概率提高贡献很小的负权群落却花费了很长时间的现象,提出SPEA-t和SPEA-p两种快速近似算法,前者是以规定时间内尽可能逼近最优解为目标,后者是以最少时间达到预设的概率阈值为目标,它们都采用了优先消去概率-时间效益较好的单环群落的策略,加快对最优解的逼近速度,减少或放弃时间开销较大的多环群落的消去,以满足那些对算法时间性能要求很高而结果以近似最优即可的应用需求.实验表明,相对于SDBA算法,NWCE算法结合概率剪枝策略在时间性能上有了数量级的提高,而SPEA-t算法和SPEA-p算法则具有更高的性能和更好的适用性. 展开更多
关键词 不确定图 最大 流可靠性
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不确定图最可靠最大流算法研究 被引量:9
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作者 蔡伟 张柏礼 吕建华 《计算机学报》 EI CSCD 北大核心 2012年第11期2371-2380,共10页
文中首先基于可能世界模型提出了不确定图的最可靠最大流问题和可靠性计算模型,这对于构建可靠性网络、可靠传输路径选择以及系统薄弱环节分析等一系列实际问题具有重要意义;然后基于简单路径组合思想提出了一种求解最可靠最大流的算法S... 文中首先基于可能世界模型提出了不确定图的最可靠最大流问题和可靠性计算模型,这对于构建可靠性网络、可靠传输路径选择以及系统薄弱环节分析等一系列实际问题具有重要意义;然后基于简单路径组合思想提出了一种求解最可靠最大流的算法SPCA,通过简单路径流量的组合,在无需求得所有最大流分布的情况下获得最可靠最大流,并在组合过程中引入概率剪枝与约束剪枝策略,对无效组合进行过滤,从而显著地提高了算法效率;接着文中针对SPCA算法易受路径数量及瓶颈容量影响的问题,又提出一种基于状态空间划分的最可靠最大流算法SDBA,该算法的主要思想是将不确定图所蕴含的子图空间划分为互不相交且满足最大流值的闭合区间集合,进而寻找所有闭合区间中概率最大的下界状态,经证明这个下界状态对应子图中的最大流分布为最可靠最大流;最后通过实验,比较了两种算法的性能.实验结果表明SDBA算法相对于SPCA算法其空间复杂度有一定的增加,但时间复杂度方面具有较大的优势,能够很好地解决SPCA算法性能受制于容量的问题,具有更好的性能与适用性. 展开更多
关键词 不确定图 可能世界模型 最大 流可靠性
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地铁列车弓网接触电阻数学模型研究 被引量:2
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作者 张冬冬 李小波 +3 位作者 张浩 张程 吴竑霖 汪翔 《智能计算机与应用》 2022年第2期165-169,共5页
地铁列车受电弓-接触网之间接触电阻是由弓网之间滑动电接触造成的,与车辆运行工况密切相关。本文通过试验测试不同接触压力、接触电流和滑动速度下的弓网接触电阻,研究了接触电阻的变化趋势,分析了这3个因素对接触电阻的影响,通过试验... 地铁列车受电弓-接触网之间接触电阻是由弓网之间滑动电接触造成的,与车辆运行工况密切相关。本文通过试验测试不同接触压力、接触电流和滑动速度下的弓网接触电阻,研究了接触电阻的变化趋势,分析了这3个因素对接触电阻的影响,通过试验数据和理论分析建立了弓网接触电阻数学模型,并验证了模型的有效性。该模型对增强地铁列车弓网之间的受流可靠性具有重要参考价值。 展开更多
关键词 接触电阻 滑动电接触 流可靠性 地铁列车
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Gate breakdown of high-voltage P-LDMOS and improved methods
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作者 孙伟锋 孙智林 +2 位作者 易扬波 陆生礼 时龙兴 《Journal of Southeast University(English Edition)》 EI CAS 2006年第1期35-38,共4页
The failure experiments of the P-LDMOS (lateral double diffused metal oxide semiconductor) demonstrate that the high peak electrical fields in the channel region of high-voltage P-LDMOS will reinforce the hot-carrie... The failure experiments of the P-LDMOS (lateral double diffused metal oxide semiconductor) demonstrate that the high peak electrical fields in the channel region of high-voltage P-LDMOS will reinforce the hot-carrier effect, which can greatly reduce the reliability of the P-LDMOS. The electrical field distribution and two field peaks along the channel surface are proposed by Tsuprem-4 and Medici. The reason of resulting in the two electrical field peaks is also discussed. Two ways of reducing the two field peaks, which are to increase the channel length and to reduce the channel concentration, are also presented. The experimental results show that the methods presented can effectively improve the gate breakdown voltage and greatly improve the reliability of the P-LDMOS. 展开更多
关键词 peak electrical field hot-carrier effect RELIABILITY
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Rheological properties of tailing paste slurry 被引量:14
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作者 王新民 李建雄 +1 位作者 肖智政 肖卫国 《Journal of Central South University of Technology》 EI 2004年第1期75-79,共5页
The initial shear stress and plastic cohesion ( η ) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship amo... The initial shear stress and plastic cohesion ( η ) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship among the consumption of different fill materials were obtained through the experiment and research on these parameters. They can be used to predict the scope of the values of τ and η in production for a given ratio, which can reduce the conveying resistance of fill slurry along the pipelines and avoid the blockage of the pipelines. It is found that the rheological model of the total tailing slurry belongs to the Bingham type, which has a feature of strong internal structure and large initial shear stress. The calculation formula for the resistance loss of pipelines conforms nicely to the field test and the actual production in Jinchuan Nickel Mine. 展开更多
关键词 FILL rheological property regression analysis reliability engineering average tailing paste slurry
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Development and validation of a simple and multifaceted instrument,GERD-TEST,for the clinical evaluation of gastroesophageal reflux and dyspeptic symptoms 被引量:3
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作者 Koji Nakada Nobuyuki Matsuhashi +4 位作者 Katsuhiko Iwakiri Atsushi Oshio Takashi Joh Kazuhide Higuchi Ken Haruma 《World Journal of Gastroenterology》 SCIE CAS 2017年第28期5216-5228,共13页
To evaluate the psychometric properties of a newly developed questionnaire, known as the gastroesophageal reflux and dyspepsia therapeutic efficacy and satisfaction test (GERD-TEST), in patients with GERD.METHODSJapan... To evaluate the psychometric properties of a newly developed questionnaire, known as the gastroesophageal reflux and dyspepsia therapeutic efficacy and satisfaction test (GERD-TEST), in patients with GERD.METHODSJapanese patients with predominant GERD symptoms recruited according to the Montreal definition were treated for 4 wk using a standard dose of proton pump inhibitor (PPI). The GERD-TEST and the Medical Outcome Study Short Form-8 Health Survey (SF-8) were administered at baseline and after 4 wk of treatment. The GERD-TEST contains three domains: the severity of GERD and functional dyspepsia (FD) symptoms (5 items), the level of dissatisfaction with daily life (DS) (4 items), and the therapeutic efficacy as assessed by the patients and medication compliance (4 items).RESULTSA total of 290 patients were eligible at baseline; 198 of these patients completed 4 wk of PPI therapy. The internal consistency reliability as evaluated using the Cronbach’s α values for the GERD, FD and DS subscales ranged from 0.75 to 0.82. The scores for the GERD, FD and DS items/subscales were significantly correlated with the physical and mental component summary scores of the SF-8. After 4 wk of PPI treatment, the scores for the GERD items/subscales were greatly reduced, ranging in value from 1.51 to 1.87 and with a large effect size (P < 0.0001, Cohen’s d; 1.29-1.63). Statistically significant differences in the changes in the scores for the GERD items/subscales were observed between treatment responders and non-responders (P < 0.0001).CONCLUSIONThe GERD-TEST has a good reliability, a good convergent and concurrent validity, and is responsive to the effects of treatment. The GERD-TEST is a simple, easy to understand, and multifaceted PRO instrument applicable to both clinical trials and the primary care of GERD patients. 展开更多
关键词 Gastroesophageal reflux and dyspepsia therapeutic efficacy and satisfaction test Patient-reported outcome Gastroesophageal reflux disease Validity Reliability
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Creating a Business Process Monitoring System "A-IOMS" for Software Development
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作者 Hirotake Sakai Kakuro Amasaka 《Chinese Business Review》 2012年第6期588-595,共8页
In this paper, the authors establish the Amalab-integrated operation management system (A-IOMS) as a new way to carry out software development and monitor business processes. This new system puts the previously cons... In this paper, the authors establish the Amalab-integrated operation management system (A-IOMS) as a new way to carry out software development and monitor business processes. This new system puts the previously constructed the Amalab-project planning navigation system (A-PPNS) to work throughout the entire organization. The A-IOMS has several key elements. Specifically, the authors have constructed: (1) a Hi-reliability estimation system diagnostic tool that pinpoints problems with software development estimates and offers a prescription for resolving them; (2) a QA table map that allows for an immediate, thorough, and consistent quality assurance process; (3) a system for sharing software development schedules throughout the organization; and (4) a technological asset completion reporting system for passing down and cultivating software development technologies and strategically expanding them. The authors verified the effectiveness of the A-IOMS at company A, a systems integration company, and the given outcomes were obtained. 展开更多
关键词 software development business process A-IOMS project management
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LDO失效分析及改善
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作者 胡敏 《电子与封装》 2022年第1期27-30,共4页
低压差线性稳压器(Low Dropout Regulator,LDO)新品导入中,过强的铜线焊接会使焊球下芯片层间电介质层(Interlayer Dielectric,ILD)产生裂纹,从而导致器件测试漏电流失效或可靠性失效。通过对芯片结构的分析,指出LDO漏电流失效的原因,... 低压差线性稳压器(Low Dropout Regulator,LDO)新品导入中,过强的铜线焊接会使焊球下芯片层间电介质层(Interlayer Dielectric,ILD)产生裂纹,从而导致器件测试漏电流失效或可靠性失效。通过对芯片结构的分析,指出LDO漏电流失效的原因,同时详细讨论了如何确定合理的铜线焊接参数、如何检测失效以及失效分析步骤。 展开更多
关键词 低压差线性稳压器 铜线焊接 漏电失效 可靠性 ILD层裂纹
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Numerical Heat Transfer Modelling for Rapid Impact Assessment of Limiting Thermostat Reliability on Fuel-Oil Burner Pre-Heaters: A Case Study
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作者 Bans Elbuken 《Journal of Environmental Science and Engineering(A)》 2016年第6期298-311,共14页
In this paper, the impact of limiting thermostat on the rupture event occuring in Fuel-Oil burner fuel pre-heaters' resistant (heat generating) wires is inspected numerically. Gaseous fuel content in the pipeline h... In this paper, the impact of limiting thermostat on the rupture event occuring in Fuel-Oil burner fuel pre-heaters' resistant (heat generating) wires is inspected numerically. Gaseous fuel content in the pipeline has also been issued as a possibility. Heater's inner temperature distributions have been simulated by an in-house MATrix LABoratory (MATLAB) script in order to understand the resistant wire exposure to high temperatures by numerous scenarios. It is concluded that the effect of fuel flowrate is not a major effect on the wires' fate because of the limiting thermostat co-working. The main difference between the calculations is the effect of thermostat cut off function. The numerical simulations enlightened the dominant effect of thermostat sensing delay, so the overheating event. Intolerable delay results with a quick drop in the thermal efficiency and an increased possibility on wire rupture due to overheating which means a burner malfunction. Referring to the first numerical simulation results, a distributed and reduced heat flux was implemented with the same fluid and thermodynamic properties on a revised pre-heater model with an increased heater plate. The increment, thus the reduction on the heat flux of the ribbon wires has been noted as the key for safe operation. 展开更多
关键词 Fuel oil burner numerical simulations resistant wires rupture thermostat delay.
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Effects of Vapor Pressure and Super-Hydrophobic Nanocomposite Coating on Microelectronics Reliability
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作者 Xuejun Fan Liangbiao Chen +2 位作者 C.P.Wong Hsing-Wei Chu G.Q.Zhang 《Engineering》 SCIE EI 2015年第3期384-390,共7页
Modeling vapor pressure is crucial for studying the moisture reliability of microelectronics, as high vapor pressure can cause device failures in environments with high temperature and humidity. To minimize the impact... Modeling vapor pressure is crucial for studying the moisture reliability of microelectronics, as high vapor pressure can cause device failures in environments with high temperature and humidity. To minimize the impact of vapor pressure, a super-hydrophobic(SH) coating can be applied on the exterior surface of devices in order to prevent moisture penetration. The underlying mechanism of SH coating for enhancing device reliability, however, is still not fully understood. In this paper, we present several existing theories for predicting vapor pressure within microelectronic materials. In addition, we discuss the mechanism and effectiveness of SH coating in preventing water vapor from entering a device, based on experimental results. Two theoretical models, a micro-mechanics-based whole-field vapor pressure model and a convection-diffusion model, are described for predicting vapor pressure. Both methods have been successfully used to explain experimental results on uncoated samples. However, when a device was coated with an SH nanocomposite, weight gain was still observed, likely due to vapor penetration through the SH surface. This phenomenon may cast doubt on the effectiveness of SH coatings in microelectronic devices. Based on current theories and the available experimental results, we conclude that it is necessary to develop a new theory to understand how water vapor penetrates through SH coatings and impacts the materials underneath. Such a theory could greatly improve microelectronics reliability. 展开更多
关键词 vapor pressure MOISTURE semiconductor reliability microelectromechanical systems (MEMS) SUPERHYDROPHOBIC nanocomposite coating
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Rainfall-Runoff Simulation in Part of Lower Niger Basin
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作者 Olusegun Adeaga Gil Mahe +4 位作者 Claudine Dieulin Francoise Elbaz-poulichet Nathalie Rouche Jean-luc Seide Eric Servat 《Journal of Environmental Science and Engineering(B)》 2012年第6期812-819,共8页
Water resources assessment in poorly gauged and ungauged basins demand supportive rainfall-runoff estimation, while resolving practical water resource management and planning issues. In this study, the research method... Water resources assessment in poorly gauged and ungauged basins demand supportive rainfall-runoff estimation, while resolving practical water resource management and planning issues. In this study, the research method employed involves rainfall-runoff modeling and simulation with proper efficiency criteria evaluation using the MODMENS modeling platform, a numerical rainfall-runoff semi-distributed GR2M conceptual lumped model. The rainfall-runoff simulation was carried-out in three selected sub-basins of Lower River Niger Basin based on observable discharge dataset. Related error estimation was carried-out to estimate the runoff simulation uncertainty while model optimization approach entails use of Rosenbrock-Simplex method and model reliability evaluation entails the use of Nash and Sutcliffe efficiency criteria methods. Result shows a satisfactory model performance at Baro and Makurdi gauging stations (savannah ecological zone) while under-estimation characterizes simulated flow at Onitsha gauging station(Forest ecological region). Seasonally, the model best fit the dry season flow but underestimate during the high flow periods (rainy seasons and wetter years). 展开更多
关键词 RAINFALL-RUNOFF SIMULATION GR2M River Niger
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