System reliability optimization problem of multi-source multi-sink flow network is defined by searching the optimal components that maximize the reliability and minimize the total assignment cost. Therefore, a genetic...System reliability optimization problem of multi-source multi-sink flow network is defined by searching the optimal components that maximize the reliability and minimize the total assignment cost. Therefore, a genetic-based approach is proposed to solve the components assignment problem under budget constraint. The mathematical model of the optimization problem is presented and solved by the proposed genetic-based approach. The proposed approach is based on determining the optimal set of lower boundary points that maximize the system reliability such that the total assignment cost does not exceed the specified budget. Finally, to evaluate our approach, we applied it to various network examples with different numbers of available components;two-source two-sink network and three-source two-sink network.展开更多
In wireless sensor networks(WSNs) with single sink,the nodes close to the sink consume their energy too fast due to transferring a large number of data packages,resulting in the "energy hole" problem.Deployi...In wireless sensor networks(WSNs) with single sink,the nodes close to the sink consume their energy too fast due to transferring a large number of data packages,resulting in the "energy hole" problem.Deploying multiple sink nodes in WSNs is an effective strategy to solve this problem.A multi-sink deployment strategy based on improved particle swarm clustering optimization(IPSCO) algorithm for WSNs is proposed in this paper.The IPSCO algorithm is a combination of the improved particle swarm optimization(PSO) algorithm and K-means clustering algorithm.According to the sink nodes number K,the IPSCO algorithm divides the sensor nodes in the whole network area into K clusters based on the distance between them,making the total within-class scatter to minimum,and outputs the center of each cluster.Then,multiple sink nodes in the center of each cluster can be deployed,to achieve the effects of partition network reasonably and deploy multi-sink nodes optimally.The simulation results show that the deployment strategy can prolong the network lifetime.展开更多
大跨桥梁多模态涡激振动控制受限于传统线性吸振器的窄频特性。非线性能量阱惯容器(nonlinear energy sink inerter,NESI)结合宽频吸振与质量放大效应,具备多模态控制潜力,但其性能易受自质量、装配误差等附加位移影响。针对桥梁风致多...大跨桥梁多模态涡激振动控制受限于传统线性吸振器的窄频特性。非线性能量阱惯容器(nonlinear energy sink inerter,NESI)结合宽频吸振与质量放大效应,具备多模态控制潜力,但其性能易受自质量、装配误差等附加位移影响。针对桥梁风致多模态涡激振动控制,提出基于NESI的控制方法。通过理论分析与数值模拟,研究了附加位移效应对NESI控制性能的影响。研究表明,附加位移导致NESI刚度与阻尼的有效参数范围偏移,引发1∶2次频率比共振,涡激振动抑制效率降低53.7%。此外,相较于阻尼比,NESI的控制性能对桥梁模态频率和初始激励幅值更为敏感。当存在附加位移时,NESI控制性能对频率比和激励幅值变化均表现出显著退化,尤其在频率比小于1区域内性能波动剧烈。进一步研究表明,适当提高质量比与惯质比虽可在一定程度上缓解附加位移带来的性能损失,但在频率比小于1的条件下仍难以实现稳定控制。展开更多
非线性能量汇(nonlinear energy sink, NES)在被动控制中有着广阔的应用前景,然而这一领域的研究主要集中在单向吸振器上,这限制了其在实际应用中对多向振动的适用性。设计了一种多向NES,利用相互正交的两组钢丝绳结构,实现了单振子空...非线性能量汇(nonlinear energy sink, NES)在被动控制中有着广阔的应用前景,然而这一领域的研究主要集中在单向吸振器上,这限制了其在实际应用中对多向振动的适用性。设计了一种多向NES,利用相互正交的两组钢丝绳结构,实现了单振子空间任意方向自适应吸振。基于拉格朗日方程建立了系统多向振动控制方程,采用了谐波平衡法对稳态响应进行近似解析分析,并利用四阶龙格-库塔法进行数值验证,其后研究了多向NES的减振效果。结果表明,多向单振子NES能够有效地抑制多向振动,对任意单向激励也同样有效。该研究为NES在多向振动控制中的应用及设计提供了参考。展开更多
文摘System reliability optimization problem of multi-source multi-sink flow network is defined by searching the optimal components that maximize the reliability and minimize the total assignment cost. Therefore, a genetic-based approach is proposed to solve the components assignment problem under budget constraint. The mathematical model of the optimization problem is presented and solved by the proposed genetic-based approach. The proposed approach is based on determining the optimal set of lower boundary points that maximize the system reliability such that the total assignment cost does not exceed the specified budget. Finally, to evaluate our approach, we applied it to various network examples with different numbers of available components;two-source two-sink network and three-source two-sink network.
基金the Key Project of the National Natural Science Foundation of China(No.61134009)National Natural Science Foundations of China(Nos.61473077,61473078)+4 种基金Program for Changjiang Scholars from the Ministry of Education,ChinaSpecialized Research Fund for Shanghai Leading Talents,ChinaProject of the Shanghai Committee of Science and Technology,China(No.13JC1407500)Innovation Program of Shanghai Municipal Education Commission,China(No.14ZZ067)the Fundamental Research Funds for the Central Universities,China(No.15D110423)
文摘In wireless sensor networks(WSNs) with single sink,the nodes close to the sink consume their energy too fast due to transferring a large number of data packages,resulting in the "energy hole" problem.Deploying multiple sink nodes in WSNs is an effective strategy to solve this problem.A multi-sink deployment strategy based on improved particle swarm clustering optimization(IPSCO) algorithm for WSNs is proposed in this paper.The IPSCO algorithm is a combination of the improved particle swarm optimization(PSO) algorithm and K-means clustering algorithm.According to the sink nodes number K,the IPSCO algorithm divides the sensor nodes in the whole network area into K clusters based on the distance between them,making the total within-class scatter to minimum,and outputs the center of each cluster.Then,multiple sink nodes in the center of each cluster can be deployed,to achieve the effects of partition network reasonably and deploy multi-sink nodes optimally.The simulation results show that the deployment strategy can prolong the network lifetime.
文摘大跨桥梁多模态涡激振动控制受限于传统线性吸振器的窄频特性。非线性能量阱惯容器(nonlinear energy sink inerter,NESI)结合宽频吸振与质量放大效应,具备多模态控制潜力,但其性能易受自质量、装配误差等附加位移影响。针对桥梁风致多模态涡激振动控制,提出基于NESI的控制方法。通过理论分析与数值模拟,研究了附加位移效应对NESI控制性能的影响。研究表明,附加位移导致NESI刚度与阻尼的有效参数范围偏移,引发1∶2次频率比共振,涡激振动抑制效率降低53.7%。此外,相较于阻尼比,NESI的控制性能对桥梁模态频率和初始激励幅值更为敏感。当存在附加位移时,NESI控制性能对频率比和激励幅值变化均表现出显著退化,尤其在频率比小于1区域内性能波动剧烈。进一步研究表明,适当提高质量比与惯质比虽可在一定程度上缓解附加位移带来的性能损失,但在频率比小于1的条件下仍难以实现稳定控制。
文摘非线性能量汇(nonlinear energy sink, NES)在被动控制中有着广阔的应用前景,然而这一领域的研究主要集中在单向吸振器上,这限制了其在实际应用中对多向振动的适用性。设计了一种多向NES,利用相互正交的两组钢丝绳结构,实现了单振子空间任意方向自适应吸振。基于拉格朗日方程建立了系统多向振动控制方程,采用了谐波平衡法对稳态响应进行近似解析分析,并利用四阶龙格-库塔法进行数值验证,其后研究了多向NES的减振效果。结果表明,多向单振子NES能够有效地抑制多向振动,对任意单向激励也同样有效。该研究为NES在多向振动控制中的应用及设计提供了参考。
