传统结构由于缺少冗余,忽略了不确定性因素的影响,更容易受到局部刚度损失的影响,文章针对载荷不确定性下破损-安全结构的设计问题提出了一种有效的基于响应面的可靠性拓扑优化方法,以提高结构的安全性,确保结构在发生局部破损时仍能满...传统结构由于缺少冗余,忽略了不确定性因素的影响,更容易受到局部刚度损失的影响,文章针对载荷不确定性下破损-安全结构的设计问题提出了一种有效的基于响应面的可靠性拓扑优化方法,以提高结构的安全性,确保结构在发生局部破损时仍能满足服役性能及可靠性要求.为此,建立了柔度概率约束下的结构体积比最小化的双循环可靠性拓扑优化模型,其中内层循环实施可靠性分析,外层循环实施拓扑优化.为了有效处理可靠性分析中响应函数关于随机变量的导数计算高成本问题,基于响应面方法建立了响应函数关于随机变量的显式表达式.详细推导了响应函数关于设计变量和随机变量的解析灵敏度列式,并采用移动渐近线方法(method of moving asymptotes,MMA)对优化问题进行求解.将基于响应面的可靠性拓扑优化方法与基于解析导数的方法作对比,并实施蒙特卡洛仿真验证了所提方法的有效性和优越性,讨论了随机载荷标准差对优化结果的影响.结果表明,本文方法可以有效设计满足指定可靠性水平的破损-安全结构,优化后结构可靠性指标的相对误差不超过1.3%,另外基于响应面的可靠性设计方法相对于基于解析导数的可靠性设计方法可节省约74%的可靠性分析时间.展开更多
航空航天等重要工程实践中,存在大量的不确定性信息,直接或间接影响着工程结构形式设计与结构性能评估工作的开展。为保证舱段结构在服役期的可靠性,工程上常采用安全系数法开展结构设计工作。传统的安全系数法可能设置过大的安全系数...航空航天等重要工程实践中,存在大量的不确定性信息,直接或间接影响着工程结构形式设计与结构性能评估工作的开展。为保证舱段结构在服役期的可靠性,工程上常采用安全系数法开展结构设计工作。传统的安全系数法可能设置过大的安全系数导致设计过于保守,也可能因未全面考虑多种不确定性因素的耦合而使得优化结构面临失效的风险。基于少样本不确定性的舱段结构可靠性拓扑优化设计方法,寻求在满足结构可靠性要求下,质量最轻的三维舱段结构拓扑优化构型。首先基于非概率凸集模型对不确定性变量进行量化,进而结合功能度量法将可靠性指标约束转化为功能度量以提高优化过程的稳健性。其次,采用一种序列单循环方法将原嵌套优化问题解耦,并采用材料场级数展开(Material Field Series Expansion,MFSE)方法大幅度减小拓扑优化设计变量数目,提高优化效率。最后,提供了二维平面应力单元算例、三维实体单元算例来验证方法的合理性与适用性。展开更多
Aimed at the difficulties in accurately, comprehensively and systematically evaluating the reliability of industrial wireless sensor networks （WSNs）, a time-evolving state transition-Monte Carlo （TEST-MC） evaluati...Aimed at the difficulties in accurately, comprehensively and systematically evaluating the reliability of industrial wireless sensor networks （WSNs）, a time-evolving state transition-Monte Carlo （TEST-MC） evaluation method and a novel network function value representation method are proposed to evaluate the reliability of the IWSNs. First, the adjacency matrix method is used to characterize three typical topologies of WSNs including the mesh network, tree network and ribbon network. Secondly, the network function value method is used to evaluate the network connectivity, and the TEST-MC evaluation method is used to evaluate network reliability and availability. Finally, the variations in the reliability, connectivity and availability of these three topologies are presented. Simulation results show that the proposed method can quickly analyze the reliability of the networks containing typical WSN topologies, which provides an effective method for the comprehensive and accurate evaluation of the reliability of WSNs.展开更多
Fault tolerant ability is an important aspect for overall evaluation of distributed system(DS). This paper discusses three measures for the evaluation: node/edge connectivity, number of spanning trees and synthetic co...Fault tolerant ability is an important aspect for overall evaluation of distributed system(DS). This paper discusses three measures for the evaluation: node/edge connectivity, number of spanning trees and synthetic connectivity. A numerical example for illustration and analysis is given, and the synthetic connectivity measure presented by this paper is proved to be rational and satisfactory.展开更多
In the network virtualization environments, one of the most challenges is how to map the virtual networks(VNs) onto a shared substrate network managed by an infrastructure provider(In P), which is termed as virtual ne...In the network virtualization environments, one of the most challenges is how to map the virtual networks(VNs) onto a shared substrate network managed by an infrastructure provider(In P), which is termed as virtual network embedding problem. Prior studies on this issue only emphasize on maximizing the revenue or minimizing the energy consumption while ignoring the reliability requirements of end-users. In our work, we incorporate the reliability probability into the virtual network embedding process with an aim to improve the Qo S/Qo E of end users from a new perspective. We devised two novel reliable virtual network embedding algorithms called RRW-Max Match and RDCC-VNE based on RW-Max Match and DCC-VNE, respectively. Extensive simulations demonstrated that the efficiency of our proposed algorithms is better than those of two primitive algorithms in terms of the reliability demands, the acceptance ratio of virtual networks and the long-term average revenue.展开更多
The traffic bottleneck plays a key role in most of the natural and artificial network. Here we present a simply model for bottleneck dynamical characteristics consideration the reliability on the complex network by ta...The traffic bottleneck plays a key role in most of the natural and artificial network. Here we present a simply model for bottleneck dynamical characteristics consideration the reliability on the complex network by taking into account the network topology characteristics and system size. We find that there is a critical rate of flow generation below which the network traffic is free but above which traffic congestion occurs. Also, it is found that random networks have larger critical flow generating rate than scale free ones. Analytical results may be practically useful for designing networks, especially for the urban traffic network.展开更多
We introduce the generalized rumor spreading model and investigate some properties of this model on different complex social networks. Despite pervious rumor models that both the spreader-spreader (SS) and the spreade...We introduce the generalized rumor spreading model and investigate some properties of this model on different complex social networks. Despite pervious rumor models that both the spreader-spreader (SS) and the spreader-stifler (SR) interactions have the same rate α, we define α(1) and α(2) for SS and SR interactions, respectively. The effect of variation of α(1) and α(2) on the final density of stiflers is investigated. Furthermore, the influence of the topological structure of the network in rumor spreading is studied by analyzing the behavior of several global parameters such as reliability and efficiency. Our results show that while networks with homogeneous connectivity patterns reach a higher reliability, scale-free topologies need a less time to reach a steady state with respect the rumor.展开更多
文摘传统结构由于缺少冗余,忽略了不确定性因素的影响,更容易受到局部刚度损失的影响,文章针对载荷不确定性下破损-安全结构的设计问题提出了一种有效的基于响应面的可靠性拓扑优化方法,以提高结构的安全性,确保结构在发生局部破损时仍能满足服役性能及可靠性要求.为此,建立了柔度概率约束下的结构体积比最小化的双循环可靠性拓扑优化模型,其中内层循环实施可靠性分析,外层循环实施拓扑优化.为了有效处理可靠性分析中响应函数关于随机变量的导数计算高成本问题,基于响应面方法建立了响应函数关于随机变量的显式表达式.详细推导了响应函数关于设计变量和随机变量的解析灵敏度列式,并采用移动渐近线方法(method of moving asymptotes,MMA)对优化问题进行求解.将基于响应面的可靠性拓扑优化方法与基于解析导数的方法作对比,并实施蒙特卡洛仿真验证了所提方法的有效性和优越性,讨论了随机载荷标准差对优化结果的影响.结果表明,本文方法可以有效设计满足指定可靠性水平的破损-安全结构,优化后结构可靠性指标的相对误差不超过1.3%,另外基于响应面的可靠性设计方法相对于基于解析导数的可靠性设计方法可节省约74%的可靠性分析时间.
文摘航空航天等重要工程实践中,存在大量的不确定性信息,直接或间接影响着工程结构形式设计与结构性能评估工作的开展。为保证舱段结构在服役期的可靠性,工程上常采用安全系数法开展结构设计工作。传统的安全系数法可能设置过大的安全系数导致设计过于保守,也可能因未全面考虑多种不确定性因素的耦合而使得优化结构面临失效的风险。基于少样本不确定性的舱段结构可靠性拓扑优化设计方法,寻求在满足结构可靠性要求下,质量最轻的三维舱段结构拓扑优化构型。首先基于非概率凸集模型对不确定性变量进行量化,进而结合功能度量法将可靠性指标约束转化为功能度量以提高优化过程的稳健性。其次,采用一种序列单循环方法将原嵌套优化问题解耦,并采用材料场级数展开(Material Field Series Expansion,MFSE)方法大幅度减小拓扑优化设计变量数目,提高优化效率。最后,提供了二维平面应力单元算例、三维实体单元算例来验证方法的合理性与适用性。
基金The International S&T Cooperation Program of China(No.2015DFA10490)the National Natural Science Foundation of China(No.61571113,61240032)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20130092110060)
文摘Aimed at the difficulties in accurately, comprehensively and systematically evaluating the reliability of industrial wireless sensor networks （WSNs）, a time-evolving state transition-Monte Carlo （TEST-MC） evaluation method and a novel network function value representation method are proposed to evaluate the reliability of the IWSNs. First, the adjacency matrix method is used to characterize three typical topologies of WSNs including the mesh network, tree network and ribbon network. Secondly, the network function value method is used to evaluate the network connectivity, and the TEST-MC evaluation method is used to evaluate network reliability and availability. Finally, the variations in the reliability, connectivity and availability of these three topologies are presented. Simulation results show that the proposed method can quickly analyze the reliability of the networks containing typical WSN topologies, which provides an effective method for the comprehensive and accurate evaluation of the reliability of WSNs.
文摘Fault tolerant ability is an important aspect for overall evaluation of distributed system(DS). This paper discusses three measures for the evaluation: node/edge connectivity, number of spanning trees and synthetic connectivity. A numerical example for illustration and analysis is given, and the synthetic connectivity measure presented by this paper is proved to be rational and satisfactory.
基金supported by "the Fundamental Research Funds for the Central Universities" of China University of Petroleum(East China)(Grant No.18CX02139A)the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2014FQ018)+3 种基金the National Natural Science Foundation of China(Grant No.61471056)the National Basic Research Program(973)of China(Grant No.2012CB315801)the Research on coordinated management and control technology of network and satellite multi-domain network resources(Grant No.17-H863-01-ZT-001-001-02)the China research project on key technology strategy of infrastructure security for information network development
文摘In the network virtualization environments, one of the most challenges is how to map the virtual networks(VNs) onto a shared substrate network managed by an infrastructure provider(In P), which is termed as virtual network embedding problem. Prior studies on this issue only emphasize on maximizing the revenue or minimizing the energy consumption while ignoring the reliability requirements of end-users. In our work, we incorporate the reliability probability into the virtual network embedding process with an aim to improve the Qo S/Qo E of end users from a new perspective. We devised two novel reliable virtual network embedding algorithms called RRW-Max Match and RDCC-VNE based on RW-Max Match and DCC-VNE, respectively. Extensive simulations demonstrated that the efficiency of our proposed algorithms is better than those of two primitive algorithms in terms of the reliability demands, the acceptance ratio of virtual networks and the long-term average revenue.
基金Supported by National Natural Science Foundation of China under Grant Nos.70871009 and 70801005Beijing Natural Science Foundation under Grant No 8102029+1 种基金Program for New Century Excellent Talents in University under Grart No.NCET-09-0208the Foundation of State Key Laboratory of Rail Traffie Control,and Safety under Grant No.RCS2010ZT001
文摘The traffic bottleneck plays a key role in most of the natural and artificial network. Here we present a simply model for bottleneck dynamical characteristics consideration the reliability on the complex network by taking into account the network topology characteristics and system size. We find that there is a critical rate of flow generation below which the network traffic is free but above which traffic congestion occurs. Also, it is found that random networks have larger critical flow generating rate than scale free ones. Analytical results may be practically useful for designing networks, especially for the urban traffic network.
文摘We introduce the generalized rumor spreading model and investigate some properties of this model on different complex social networks. Despite pervious rumor models that both the spreader-spreader (SS) and the spreader-stifler (SR) interactions have the same rate α, we define α(1) and α(2) for SS and SR interactions, respectively. The effect of variation of α(1) and α(2) on the final density of stiflers is investigated. Furthermore, the influence of the topological structure of the network in rumor spreading is studied by analyzing the behavior of several global parameters such as reliability and efficiency. Our results show that while networks with homogeneous connectivity patterns reach a higher reliability, scale-free topologies need a less time to reach a steady state with respect the rumor.
