期刊文献+
共找到123,982篇文章
< 1 2 250 >
每页显示 20 50 100
Reliability Modeling and Evaluation of Complex Multi-State System Based on Bayesian Networks Considering Fuzzy Dynamic of Faults 被引量:4
1
作者 Fangjun Zuo Meiwei Jia +2 位作者 Guang Wen Huijie Zhang Pingping Liu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第11期993-1012,共20页
In the traditional reliability evaluation based on the Bayesian method,the failure probability of nodes is usually expressed by the average failure rate within a period of time.Aiming at the shortcomings of traditiona... In the traditional reliability evaluation based on the Bayesian method,the failure probability of nodes is usually expressed by the average failure rate within a period of time.Aiming at the shortcomings of traditional Bayesian network reliability evaluation methods,this paper proposes a Bayesian network reliability evaluation method considering dynamics and fuzziness.The fuzzy theory and the dynamic of component failure probability are introduced to construct the dynamic fuzzy set function.Based on the solving characteristics of the dynamic fuzzy set and Bayesian network,the fuzzy dynamic probability and fuzzy dynamic importance degree of the fault state of leaf nodes are solved.Finally,through the dynamic fuzzy reliability analysis of CNC machine tool hydraulic system balance circuit,the application of this method in system reliability evaluation is verified,which provides support for fault diagnosis of CNC machine tools. 展开更多
关键词 Bayesian network(BN) dynamics fuzzy multi-state
在线阅读 下载PDF
基于BAS—Smith—Fuzzy PID的物联网水肥控制系统研究 被引量:2
2
作者 丁筱玲 王克林 +3 位作者 李军台 郭冰 李志勇 赵立新 《中国农机化学报》 北大核心 2025年第4期240-247,共8页
针对水肥控制难度大,传统灌溉施肥方法智能化程度较低的问题,设计一种基于BAS—Smith—Fuzzy PID的物联网水肥一体化控制系统。以控制混合肥液的EC(电导率)值为目标,在传统模糊PID控制算法的基础上引入BAS(天牛须搜索)算法和Smith预估... 针对水肥控制难度大,传统灌溉施肥方法智能化程度较低的问题,设计一种基于BAS—Smith—Fuzzy PID的物联网水肥一体化控制系统。以控制混合肥液的EC(电导率)值为目标,在传统模糊PID控制算法的基础上引入BAS(天牛须搜索)算法和Smith预估器。通过MATLAB/Simulink软件仿真,验证其寻优和优化能力,对比常规PID、BAS—PID模型,结果表明,BAS—Smith—Fuzzy PID控制器拥有优异控制性能。基于STM32主控平台搭建单通道混肥装置,配置MCGS触摸屏上位机并基于Android平台开发客户端进行人机交互,试验结果表明,BAS—Smith—Fuzzy PID的调节时间对比常规PID、BAS—PID缩短17.1%、63%、超调量降低82.1%、87.2%。 展开更多
关键词 水肥一体化 BAS算法 模糊PID控制 物联网 SIMULINK仿真
在线阅读 下载PDF
基于AW-CPSO-Fuzzy-PID的茶鲜叶分级输送速度控制器研究 被引量:1
3
作者 胡永光 靳筱天 +2 位作者 张志 鹿永宗 潘庆民 《农业机械学报》 北大核心 2025年第4期275-283,共9页
为解决基于机器视觉的茶鲜叶分级输送速度控制精度低的问题,本文设计一种引入自适应权重与Circle混沌映射的PSO优化模糊PID控制器(AW-CPSO-Fuzzy-PID),并开展基于改进模糊PID的茶鲜叶分级输送速度控制。在茶鲜叶输送传动系统作业过程中... 为解决基于机器视觉的茶鲜叶分级输送速度控制精度低的问题,本文设计一种引入自适应权重与Circle混沌映射的PSO优化模糊PID控制器(AW-CPSO-Fuzzy-PID),并开展基于改进模糊PID的茶鲜叶分级输送速度控制。在茶鲜叶输送传动系统作业过程中,当设定输送速度为78.5 mm/s时,每1 ms记录一次,输送速度波动可控制在0.7 mm/s内;改进模糊PID茶鲜叶输送传动系统响应时间比传统PID与模糊PID分别减少81.41%、61.74%;超调量分别降低81.24%、41.82%;采集目标图像平均峰值信噪比分别提高5.8、10.4 dB。结果表明,本文提出的方法具有更好的寻优性能和收敛速度。研究结果为基于机器视觉的茶鲜叶自动分级系统精确而稳定的控制奠定了理论基础,为解决由输送速度波动导致的图像模糊问题提供了技术方案。 展开更多
关键词 茶鲜叶分级 输送速度 模糊PID控制 粒子群算法
在线阅读 下载PDF
L-fuzzifying拓扑空间范畴和可延L-fuzzy拓扑空间范畴的Galois联络
4
作者 方进明 陈芳芳 《模糊系统与数学》 CSCD 北大核心 2011年第3期42-47,共6页
在完全分配格的格值环境下,提供了L-fuzzifying拓扑结构和可延L-fuzzy拓扑结构相互转化的方法。还进一步研究了L-fuzzifying拓扑空间范畴和可延L-fuzzy拓扑空间范畴之间的关系。文中结果表明,L-fuzzifying拓扑空间范畴和可延L-fuzzy拓... 在完全分配格的格值环境下,提供了L-fuzzifying拓扑结构和可延L-fuzzy拓扑结构相互转化的方法。还进一步研究了L-fuzzifying拓扑空间范畴和可延L-fuzzy拓扑空间范畴之间的关系。文中结果表明,L-fuzzifying拓扑空间范畴和可延L-fuzzy拓扑空间范畴之间存在Galois联络。 展开更多
关键词 完全分配格 L-fuzzifying拓扑 可延L-fuzzy拓扑 Galois联络
原文传递
Importance measure of system reliability upgrade for multi-state consecutive k-out-of-n systems 被引量:3
5
作者 HonQvan Dui Shubin si +2 位作者 Zhiqiang Cai Shudong Sun Yingfeng Zhang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第6期936-942,共7页
Importance measures in reliability systems are used to identify weak components in contributing to a proper function of the system.Traditional importance measures mainly concerned the changing value of the system reli... Importance measures in reliability systems are used to identify weak components in contributing to a proper function of the system.Traditional importance measures mainly concerned the changing value of the system reliability caused by the change of the reliability of the component,and seldom considered the joint effect of the probability distribution,improvement rate of the object component.This paper studies the rate of the system reliability upgrading with an improvement of the component reliability for the multi-state consecutive k-out-of-n system.To verify the multi-state consecutive k-out-of-n system reliability upgrading by improving one component based on its improvement rate,an increasing potential importance(IPI)and its physical meaning are described at first.Secondly,the relationship between the IPI and Birnbaum importance measures are discussed.And the IPI for some different improvement actions of the component is further discussed.Thirdly,the characteristics of the IPI are analyzed.Finally,an application to an oil pipeline system is given. 展开更多
关键词 system reliability multi-state consecutive k-out-of-nsystem IMPROVEMENT Birnbaum importance.
在线阅读 下载PDF
基于Fuzzy DEMATEL-VIKOR模型的历史街区文化活力设计优化研究 被引量:1
6
作者 万一凡 李宇轩 +2 位作者 粟丹倪 方兴 张镨方 《包装工程》 北大核心 2025年第20期279-295,共17页
目的在城市高质量发展背景下,系统分析历史街区文化活力的现状与不足,提出优化设计方法,以提升文化活力并彰显城市地域文化特色。方法通过对武汉市的实证研究,利用POI空间聚集度分析,选取文化活力较高的4个历史街区作为实地问卷调查对... 目的在城市高质量发展背景下,系统分析历史街区文化活力的现状与不足,提出优化设计方法,以提升文化活力并彰显城市地域文化特色。方法通过对武汉市的实证研究,利用POI空间聚集度分析,选取文化活力较高的4个历史街区作为实地问卷调查对象。通过分析历史文化展现、娱乐趣味性等10个影响因素,构建了设计方法。进一步运用Fuzzy DEMATEL-VIKOR组合模型处理用户调研数据中的不确定性与模糊性,并对影响因素进行重要性排序。结果指导完成历史街区文化活力活化的方案设计,最后通过用户评分验证设计方案。结论设计方案得到了用户的认可,达到了用户的期望。说明构建的Fuzzy DEMATEL-VIKOR模型能较好地实现用户需求的合理分析与转化,以及用户满意度意见的有效融合,提升了用户需求分析与转化过程的客观性和全面性,同时也为相关设计人员在进行用户需求分析时提供了一种新的设计思路。 展开更多
关键词 历史街区 文化活力 影响因素 fuzzy DEMATEL VIKOR
在线阅读 下载PDF
Capacitated stochastic coloured Petri net-based approach for computing two-terminal reliability of multi-state network 被引量:3
7
作者 Tao Zhang Bo Guo 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第2期304-313,共10页
Classical network reliability problems assume both net- works and components have only binary states, fully working or fully failed states. But many actual networks are multi-state, such as communication networks and ... Classical network reliability problems assume both net- works and components have only binary states, fully working or fully failed states. But many actual networks are multi-state, such as communication networks and transportation networks. The nodes and arcs in the networks may be in intermediate states which are not fully working either fully failed. A simulation ap- proach for computing the two-terminal reliability of a multi-state network is described. Two-terminal reliability is defined as the probability that d units of demand can be supplied from the source to sink nodes under the time threshold T. The capacities of arcs may be in a stochastic state following any discrete or continuous distribution. The transmission time of each arc is also not a fixed number but stochastic according to its current capacity and de- mand. To solve this problem, a capacitated stochastic coloured Petri net is proposed for modelling the system behaviour. Places and transitions respectively stand for the nodes and arcs of a net- work. Capacitated transition and self-modified token colour with route information are defined to describe the multi-state network. By the simulation, the two-terminal reliability and node importance can be estimated and the optimal route whose reliability is highest can also be given. Finally, two examples of different kinds of multi- state networks are given. 展开更多
关键词 two-terminal reliability multi-state network Petri net (PN) simulation node importance.
在线阅读 下载PDF
Reliability Analysis of Retracting Actuator with Multi-State Based on Goal Oriented Methodology 被引量:3
8
作者 周琳玕 董海平 +2 位作者 伊枭剑 李媛媛 赖岳华 《Journal of Shanghai Jiaotong university(Science)》 EI 2015年第3期307-311,共5页
In order to conduct effective reliability analysis of retracting actuator with multi-state(success state,safety failure state and action failure state), we redefine type-3 operator in goal oriented(GO) method to descr... In order to conduct effective reliability analysis of retracting actuator with multi-state(success state,safety failure state and action failure state), we redefine type-3 operator in goal oriented(GO) method to describe three states of main charge of retracting actuator and improve type-15 operator in GO method to describe the logic relations of multi-state output. The quantitative and qualitative reliability analyses of retracting actuator are made based on GO method in this paper. The system state probability of retracting actuator is obtained through quantitative analysis, and its weakness is found through qualitative analysis. The analysis results show that GO method is effective to improve the reliability of retracting actuator, and this method is also feasible for reliability analysis of other complicated initiating explosive systems. 展开更多
关键词 retracting actuator goal oriented(GO) methodology OPERATOR multi-state reliability analysis
原文传递
Integrated importance measure for multi-state coherent systems of k level 被引量:2
9
作者 Xibin Zhao Shubin Si +2 位作者 Hongyan Dui Zhiqiang Cai Shudong Sun 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2013年第6期1029-1037,共9页
To verify the effectiveness of the integrated importance measure (IIM) for multi-state coherent systems of k level, the definition and physical meaning of IIM are demonstrated. Then, the improvement potential and Δ... To verify the effectiveness of the integrated importance measure (IIM) for multi-state coherent systems of k level, the definition and physical meaning of IIM are demonstrated. Then, the improvement potential and Δ-importance measures are generalized to multi-state coherent systems based on the system performance level, and the relationships between IIM and traditional importance measures are discussed. The characteristics of IIM are demonstrated in both series and parallel systems. Also, an application to an oil transportation system is given. The comparison results show that: (i) IIM has some useful properties that are not possessed by traditional importance measures; (ii) IIM is effective in evaluating the component role in multi-state systems when the component reliability and the failure rate are simultaneously considered. 展开更多
关键词 multi-state coherent system system performance level integrated importance measure system reliability
在线阅读 下载PDF
A voltage support control strategy based on three-port flexible multi-state switch in distribution networks 被引量:1
10
作者 Bo PENG Guorong ZHANG 《Plasma Science and Technology》 SCIE EI CAS CSCD 2020年第8期192-202,共11页
Voltage sags in power system may lead to serious problems such as the off-grid of distributed generation and electrical equipment failures.As a novel type of power electronic equipment,a flexible multi-state switch(FM... Voltage sags in power system may lead to serious problems such as the off-grid of distributed generation and electrical equipment failures.As a novel type of power electronic equipment,a flexible multi-state switch(FMSS)is capable to support the voltage during the grid faults.In this paper,a voltage control strategy to support the voltage in a distribution network is proposed by introducing three-port FMSS.The positive-negative-sequence compensation(PNSC)scheme is adopted to control the active and reactive current.This control scheme eliminates active power oscillations at the port of voltage sags and reduces coupling oscillations of other ports.Based on the characteristics of the voltage support under PNSC scheme,two voltage support strategies are proposed.A proportional-integral controller is introduced to provide the reactive power references,which eliminates the errors when estimating the grid voltage and impedance.A current limiting scheme is adopted to keep the port current in a safe range by adjusting the active and reactive power references.The voltage support strategies in two different voltage sags are simulated,and results show the feasibility and effectiveness of the proposed control strategies. 展开更多
关键词 FLEXIBLE multi-state SWITCH voltage support low-voltage ride-through reactive power control
在线阅读 下载PDF
Optimal transmission lines assignment with maximal reliabilities in multi-source multi-sink multi-state computer network 被引量:1
11
作者 章筠 徐正国 +2 位作者 王文海 卢建刚 孙优贤 《Journal of Central South University》 SCIE EI CAS 2013年第7期1868-1877,共10页
The optimal transmission lines assignment with maximal reliabilities (OTLAMR) in the multi-source multi-sink multi-state computer network (MMMCN) was investigated. The OTLAMR problem contains two sub-problems: the MMM... The optimal transmission lines assignment with maximal reliabilities (OTLAMR) in the multi-source multi-sink multi-state computer network (MMMCN) was investigated. The OTLAMR problem contains two sub-problems: the MMMCN reliabilities evaluation and multi-objective transmission lines assignment optimization. First, a reliability evaluation with a transmission line assignment (RETLA) algorithm is proposed to calculate the MMMCN reliabilities under the cost constraint for a certain transmission lines configuration. Second, the non-dominated sorting genetic algorithm II (NSGA-II) is adopted to find the non-dominated set of the transmission lines assignments based on the reliabilities obtained from the RETLA algorithm. By combining the RETLA and the NSGA-II algorithms together, the RETLA-NSGA II algorithm is proposed to solve the OTLAMR problem. The experiments result show that the RETLA-NSGA II algorithm can provide efficient solutions in a reasonable time, from which the decision makers can choose the best solution based on their preferences and experiences. 展开更多
关键词 multi-state network reliability evaluation transmission lines assignments multi-objective optimization non-dominatedsorting genetic algorithm II
在线阅读 下载PDF
基于Fuzzy-DEMATEL-ISM的新能源汽车供应链韧性影响因素研究 被引量:3
12
作者 孙静 陈雨朵 《物流技术》 2025年第1期37-48,共12页
全球化和产业革命推动下,新能源汽车供应链面临潜在风险与挑战,提升供应链韧性对保障产业稳定和可持续发展至关重要。现有研究多侧重于提升路径、韧性测量和宏观政策,缺乏对影响因素系统性和层次性的研究。全面分析新能源汽车供应链韧... 全球化和产业革命推动下,新能源汽车供应链面临潜在风险与挑战,提升供应链韧性对保障产业稳定和可持续发展至关重要。现有研究多侧重于提升路径、韧性测量和宏观政策,缺乏对影响因素系统性和层次性的研究。全面分析新能源汽车供应链韧性的影响因素,识别关键因素,并剖析这些因素间的逻辑关系和层次结构,可为提升供应链韧性提供理论依据和实践指导。首先,通过文献分析法构建初步影响因素体系,并邀请专家对影响因素进行调查和筛选,从预测能力、响应能力、恢复能力、学习能力和可持续发展能力5个维度构建了包含20个影响因素的指标体系。然后,运用FuzzyDEMATEL模型识别关键影响因素,并通过ISM模型分析影响因素间的逻辑关系和层次结构。研究发现供应链数字化水平、智慧物流水平和供应链合作等8个因素为新能源汽车供应链韧性的关键影响因素,供应链可见性和财务实力是供应链韧性的根本因素,可持续发展能力对供应链韧性起最直接作用。基于研究结果,提出加强供应链数智化转型、深化供应链合作、构建ESG生态体系等建议,以提升新能源汽车供应链韧性。 展开更多
关键词 新能源汽车 供应链韧性 影响因素 fuzzy-DEMATEL-ISM
在线阅读 下载PDF
基于GOHBA-Fuzzy-PID算法的施肥控制系统优化研究
13
作者 黄友锐 陆森 +1 位作者 韩涛 刘权增 《农业机械学报》 北大核心 2025年第11期320-328,共9页
为满足中草药种植对灌溉精准施肥控制的需求,解决传统PID控制存在的超调大、响应慢等问题,本文提出一种基于全局优化蜜獾算法(GOHBA)与模糊PID结合的优化控制策略。利用GOHBA调节模糊PID控制器关键增益参数,以提升系统响应速度与稳定性... 为满足中草药种植对灌溉精准施肥控制的需求,解决传统PID控制存在的超调大、响应慢等问题,本文提出一种基于全局优化蜜獾算法(GOHBA)与模糊PID结合的优化控制策略。利用GOHBA调节模糊PID控制器关键增益参数,以提升系统响应速度与稳定性。在流量0.5、1.0、1.5、2.0 L/min条件下开展仿真,比较GOHBA-Fuzzy-PID与标准PID、常规Fuzzy-PID及HBA-Fuzzy-PID的控制性能。结果表明:GOHBA-Fuzzy-PID在不同流量下均展现出较小的超调量(16.7%~26.3%)和更短或相当的稳态时间(92~97 s),优于其他控制器,特别当流量为2.0 L/min时,其超调量仅为18.2%,显著低于传统算法。结果表明本文算法在非线性、时变的水肥一体化系统中展现出良好鲁棒性与应用潜力。 展开更多
关键词 水肥一体化 GOHBA-fuzzy-PID算法 精准施肥
在线阅读 下载PDF
基于改进型蜣螂算法Fuzzy-Smith-LADRC混凝投药 被引量:1
14
作者 王文成 余智科 郑诗翰 《电子测量技术》 北大核心 2025年第3期10-17,共8页
二十届三中全会强调全面落实深化改革水利任务,其中居民饮用水是重点民生任务,混凝工艺是饮用水处理的关键环节。由于混凝过程具有大时滞特性,故对于原水水质频繁变化的控制系统,常规的PID控制不能达到满意的效果。为此,将一种不依赖系... 二十届三中全会强调全面落实深化改革水利任务,其中居民饮用水是重点民生任务,混凝工艺是饮用水处理的关键环节。由于混凝过程具有大时滞特性,故对于原水水质频繁变化的控制系统,常规的PID控制不能达到满意的效果。为此,将一种不依赖系统精确模型的线性自抗扰控制器(LADRC)应用于系统中,利用扩张观测器对混凝控制系统中出现的扰动进行估计并补偿,同时设计史密斯预估器(Smith)与模糊控制器(Fuzzy)相结合的自适应史密斯控制器来消除大时滞对控制效果的影响,提出Fuzzy-Smith-LADRC控制器。针对控制器参数调节困难而引入改进型蜣螂算法(MSIDBO)进行参数整定。改进型算法对DBO算法中初始种群分布不均匀、易陷入局部最优解等问题进行优化,使得MSIDBO能快速收敛并更好平衡全局探索与局部开发能力。系统模型精确时,该控制方法比PID控制的调节时间减少279 s和超调量降低8%,比DMC控制的调节时间减少40 s,系统模型变化时,相比LADRC具有更好的抗干扰性与鲁棒性。 展开更多
关键词 混凝工艺 模糊史密斯预估-线性自抗扰 改进蜣螂算法 参数优化
原文传递
IDBO-Fuzzy-PID控制器在立磨机液压控制中的应用
15
作者 李玲 刘佳芸 +2 位作者 李瑶 程福安 解妙霞 《中南大学学报(自然科学版)》 北大核心 2025年第9期3724-3736,共13页
为解决立磨机液压控制系统存在的非线性、时变性问题,本文提出了一种基于改进蜣螂算法(improved dung beetle optimizer,IDBO)的模糊PID控制器(IDBO-Fuzzy-PID)。首先,基于立磨机液压位置控制系统模型,设计模糊PID控制器以实时调整控制... 为解决立磨机液压控制系统存在的非线性、时变性问题,本文提出了一种基于改进蜣螂算法(improved dung beetle optimizer,IDBO)的模糊PID控制器(IDBO-Fuzzy-PID)。首先,基于立磨机液压位置控制系统模型,设计模糊PID控制器以实时调整控制参数;其次,针对DBO算法存在的种群多样性匮乏、全局搜索能力弱、易陷局部最优等不足,引入佳点集与反向学习、自适应繁殖偷窃及自适应混合变异3种策略进行改进,并通过多类型测试函数验证IDBO收敛速度及求解精度;最后,构建联合仿真平台,验证控制器在随机干扰与系统参数波动条件下的控制性能。研究结果表明:本文提出的IDBO-Fuzzy-PID控制器具有良好的跟踪性能与时变适应性,系统平衡点附近上升、调节时间最短,基本无超调至目标位移;在外界扰动条件下,液压杆振幅降至0.252 mm,较PID控制器降幅达71.3%,其抗干扰性能最优;在系统参数波动条件下,其稳定性未受显著影响,正弦波跟踪性能最优。该控制器通过动态调整参数以快速补偿液压杆位移的偏差,有效抑制了磨辊的波动,提升了磨粉工艺的稳定性。 展开更多
关键词 立磨机 液压控制 模糊PID控制 蜣螂优化算法 联合仿真
在线阅读 下载PDF
Importance Analysis of a Multi-state System Based on Direct Partial Logic Derivatives and Multi-valued Decision Diagrams 被引量:1
16
作者 古莹奎 李晶 《Journal of Donghua University(English Edition)》 EI CAS 2014年第6期789-792,共4页
Importance analysis quantifies the critical degree of individual component. Compared with the traditional binary state system,importance analysis of the multi-state system is more aligned with the practice. Because th... Importance analysis quantifies the critical degree of individual component. Compared with the traditional binary state system,importance analysis of the multi-state system is more aligned with the practice. Because the multi-valued decision diagram( MDD) can reflect the relationship between the components and the system state bilaterally, it was introduced into the reliability calculation of the multi-state system( MSS). The building method,simplified criteria,and path search and probability algorithm of MSS structure function MDD were given,and the reliability of the system was calculated. The computing methods of importance based on MDD and direct partial logic derivatives( DPLD) were presented. The diesel engine fuel supply system was taken as an example to illustrate the proposed method. The results show that not only the probability of the system in each state can be easily obtained,but also the influence degree of each component and its state on the system reliability can be obtained,which is conducive to the condition monitoring and structure optimization of the system. 展开更多
关键词 multi-state system(MSS) importance analysis reliability multi-valued decision diagram(MDD) direct partial logic derivative(DPLD) diesel engine fuel supply system
在线阅读 下载PDF
蜣螂算法优化Fuzzy-PID的超声波电源频率控制研究
17
作者 蔡华锋 夏彪 田亮 《重庆理工大学学报(自然科学)》 北大核心 2025年第9期209-216,共8页
超声波焊接过程中换能器受到温度、阻抗波动等影响会产生谐振频率漂移现象,针对超声波电源频率跟踪精度低、动态响应慢的问题,提出一种蜣螂算法(dung beetle optimizer,DBO)优化模糊PID(fuzzy-PID)的频率复合控制策略。通过建立超声波... 超声波焊接过程中换能器受到温度、阻抗波动等影响会产生谐振频率漂移现象,针对超声波电源频率跟踪精度低、动态响应慢的问题,提出一种蜣螂算法(dung beetle optimizer,DBO)优化模糊PID(fuzzy-PID)的频率复合控制策略。通过建立超声波焊接电源的Simulink仿真模型,系统对比了传统PID、模糊PID、粒子群(PSO)优化的模糊PID以及蜣螂算法优化的模糊PID 4种控制方法下系统的动态特性。研究结果表明:蜣螂优化算法通过定向滚球机制和动态权重调整策略,有效实现了模糊论域参数的自适应整定,提高了频率控制精度,并能在负载阻抗突变情况下快速跟踪到换能器谐振频率。 展开更多
关键词 超声波电源 超声焊接 蜣螂优化算法 模糊PID 频率跟踪
在线阅读 下载PDF
A multi-state weather generator for daily precipitation for the Torne River basin, northern Sweden/western Finland
18
作者 David RAYNER Christine ACHBERGER Deliang CHEN 《Advances in Climate Change Research》 SCIE CSCD 2016年第1期70-81,共12页
This paper describes a new weather generator e the 10-state empirical model e that combines a 10-state, first-order Markov chain with a non-parametric precipitation amounts model. Using a doubly-stochastic transition-... This paper describes a new weather generator e the 10-state empirical model e that combines a 10-state, first-order Markov chain with a non-parametric precipitation amounts model. Using a doubly-stochastic transition-matrix results in a weather generator for which the overall precipitation distribution(including both wet and dry days) and the temporal-correlation can be modified independently for climate change studies. This paper assesses the ability of the 10-state empirical model to simulate daily area-average precipitation in the Torne River catchment in northern Sweden/western Finland in the context of 3 other models: a 10-state model with a parametric(Gamma) amounts model; a wet/dry chain with the empirical amounts model; and a wet/dry chain with the parametric amounts model. The ability to accurately simulate the distribution of multi-day precipitation in the catchment is the primary consideration.Results showed that the 10-state empirical model represented accumulated 2- to 14-day precipitation most realistically. Further, the distribution of precipitation on wet days in the catchment is related to the placement of a wet day within a wet-spell, and the 10-state models represented this realistically, while the wet/dry models did not. Although all four models accurately reproduced the annual and monthly averages in the training data, all models underestimated inter-annual and inter-seasonal variance. Even so, the 10-state empirical model performed best.We conclude that the multi-state model is a promising candidate for hydrological applications, as it simulates multi-day precipitation well, but that further development is required to improve the simulation of interannual variation. 展开更多
关键词 Weather generator multi-state Torne River PRECIPITATION
在线阅读 下载PDF
The Mechanical Stabilization and Multi-States of the Stretched VWF A2 Domain
19
作者 Xubin Xie Ying Fang Jianhua Wu 《医用生物力学》 EI CAS CSCD 北大核心 2019年第A01期80-81,共2页
At the vascular injury sites,the ultra-large (UL) multimeric von willebrand Factor (VWF) is released in response to physiological and pathophysiological stimuli,and mediates platelet adhesion,aggregation,and cross-lin... At the vascular injury sites,the ultra-large (UL) multimeric von willebrand Factor (VWF) is released in response to physiological and pathophysiological stimuli,and mediates platelet adhesion,aggregation,and cross-linking to maintain hemostasis.This UL-VWF is specifically cleaved by ADAMTS13(A Disintegrin And Metalloprotease with a ThromboSpondintype-1 motif,member 13)to prevent microvascular thrombosis.Each VWF monomer consists of five types of repeat domains in the order of D1-D2-D’-D3-A1-A2-A3-D4-C1-C2-C3-C4-C5-C6-CK,in which the A2 domain contains the ADAMTS13cleavage site(Tyr1605-Met1606),exposure of which requires mechanical or chemical stimuli.Under flows,fluid shear stress regulates VWF degradation and size distribution through opening the A2 domain and exposing its cleavage site for ADAMTS13.VWF A2 domain contains a C-terminal vicinal disulfide bond,a calcium binding sites,and a flexibleα4-less-loop.These unique structure features together make A2 more sensitive to mechanical signal than other VWF A subdomains,i.e.A1 and A3 domains.It is believed that A2 is first bound with and then cleaved by ADAMTS13,together with force-induced conformation transformation.To reveal molecular basis of this two-step model of VWF hydrolyzation by ADAMTS13,we here examined stretch-induced unfolding processes of VWF A2 domain in more detail by Steered molecular dynamics(SMD)simulations,with the use of crystal structure of VWF A2(PDB ID 3GXB),and observed that there were multiple quasi-stable conformations of stretched A2 until itsβ4-strand and a3-helix were pulled away the central hydrophobic core and the cleavage sites were fully accessible to solvent.Our MD simulation data showed that,in unfolding,at first,the cleavage site residue Tyr1605 was exposed partially and binding sites for Spacer domain of ADAMTS13 were exposed to a high level whenα6-helix was separated from A2 body;then,withβ6-strand and a5-helix been pulled away,the binding sites for Cysrich domain of ADAMTS13 was exposed completely while the exposure degree of Tyr1605 was not improved;further,separation ofβ5-strand andα4-less-loop made Tyr1605 and Met1606 and the respective binding sites for ADAMTS13 Spacer domain,Cys-rich domain,and Disintegrin-like domain be fully exposed to reach the optimal catalytic state;lastly,withβ4-strand separation,the cleavage sites and binding sites all were overstretched,leading to mismatch of ADAMTS13 and A2 conformation especially in the binding sites.This conformational mismatch may cause reduction of ADAMTS13 hydrolysis efficiency.Furthermore,the data of SMD simulations under constant forces demonstrated that,the stretched A2 conformation had different quasi-stable states,which all had the better mechanical stability within simulation time of 100 ns;and the conformational transformation from one state to another must overcome their respective potential barriers.The hydrolysis efficiency should depend on each state of the stretched A2 conformation,because of the exclusive matched-degree of A2 and ADMATS13.This computer prediction on the mechanical stability and multi-states of stretched A2 provides a novel insight into the mechano-chemical regulation on cleavage of A2 by ADAMTS13.It would be helpful for design of related drug targeting the binding sites on A2 and exosites on ADAMTS13 for the treatment of patients with acquired TTP. 展开更多
关键词 VWF PROTEIN UNFOLDING SMD ADMATS13 multi-state of PROTEIN
原文传递
Reliability Improvement of Large Multi-state Series-parallel Systems
20
作者 Bozena Kwiatuszewska-Sarnecka 《International Journal of Automation and computing》 EI 2006年第2期157-164,共8页
In the paper, excess methods for improving the reliability of multi-state series-parallel systems are presented: for the hot reserve of single components, the cold reserve of single components, and the mixed (hot an... In the paper, excess methods for improving the reliability of multi-state series-parallel systems are presented: for the hot reserve of single components, the cold reserve of single components, and the mixed (hot and cold) reserve of single components. A process is also introduced to improve the reliability of these methods by replacing their components with more reliable ones. New theorems for multi-state limit reliability functions in homogeneous and non-homogeneous series-parallel large systems composed of components with improved reliability are presented, and applied to compare the effects of these systems in different reliability improving methods. 展开更多
关键词 Reliability improvement multi-state system large system limit reliability function.
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部