以武汉在建的天兴洲大桥南岸引桥大跨度连续刚构桥为研究对象,运用AN SY S对其动力特性进行了分析.得到了成桥状态下结构的自振特性及有效振型参与质量,确定了运用反应谱法对地震作用进行振型组合时所必须的振型阶数,并结合反应谱法和...以武汉在建的天兴洲大桥南岸引桥大跨度连续刚构桥为研究对象,运用AN SY S对其动力特性进行了分析.得到了成桥状态下结构的自振特性及有效振型参与质量,确定了运用反应谱法对地震作用进行振型组合时所必须的振型阶数,并结合反应谱法和时程分析法对该桥进行了地震反应分析,分别得到各概率地震作用下结构的反应最大值,同时比较了两种方法的分析结果.根据“三水准”设防原则,分析评价了该桥的综合抗震性能,为该桥的建设和抗震设计提供了参考,也为进一步研究该类桥型的抗震性能提供了分析基础.分析结果表明,该桥具有足够的抗震能力,能够满足预期的设计性能.展开更多
Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA stra...Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA strategy, which might not be suited to the dynamic network environment. In this paper, we propose a multi-strategy DSA(MS-DSA) system, where the primary and the secondary system share spectrum resources with multiple DSA strategies simultaneously. To analyze the performance of the proposed MS-DSA system, we model it as a continuous-time Markov chain(CTMC) and derive the expressions to compute the corresponding performance metrics. Based on this, we define a utility function involving the concerns of effective throughput, interference quantity on primary users, and spectrum leasing cost. Two optimization schemes, named as spectrum allocation and false alarm probability selection, are proposed to maximize the utility function. Finally, numerical simulations are provided to validate our analysis and demonstrate that the performance can be significantly improved caused by virtues of the proposed MS-DSA system.展开更多
为了减少物联网环境中对用户身份的漏报率,该文将传统的身份认证和行为认证相结合,提出了一种基于物联网的动态用户行为认证机制。建立了用户行为认证集,论述了整个机制的实现过程。论述了确定的充分行为认证和不确定的必要行为认证,同...为了减少物联网环境中对用户身份的漏报率,该文将传统的身份认证和行为认证相结合,提出了一种基于物联网的动态用户行为认证机制。建立了用户行为认证集,论述了整个机制的实现过程。论述了确定的充分行为认证和不确定的必要行为认证,同时给出了每个认证过程的随机Petri网(Stochastic Petri Net,SPN)模型,并用Petri网量化分析了该机制对性能的影响和认证漏报率。理论分析表明:该机制在提高用户认证机制的安全性方面具有显著效果,同时性能良好。展开更多
文摘以武汉在建的天兴洲大桥南岸引桥大跨度连续刚构桥为研究对象,运用AN SY S对其动力特性进行了分析.得到了成桥状态下结构的自振特性及有效振型参与质量,确定了运用反应谱法对地震作用进行振型组合时所必须的振型阶数,并结合反应谱法和时程分析法对该桥进行了地震反应分析,分别得到各概率地震作用下结构的反应最大值,同时比较了两种方法的分析结果.根据“三水准”设防原则,分析评价了该桥的综合抗震性能,为该桥的建设和抗震设计提供了参考,也为进一步研究该类桥型的抗震性能提供了分析基础.分析结果表明,该桥具有足够的抗震能力,能够满足预期的设计性能.
基金supported in part by the National Natural Sciences Foundation of China (NSFC) under Grant 61525103the National Natural Sciences Foundation of China under Grant 61501140the Shenzhen Fundamental Research Project under Grant JCYJ20150930150304185
文摘Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA strategy, which might not be suited to the dynamic network environment. In this paper, we propose a multi-strategy DSA(MS-DSA) system, where the primary and the secondary system share spectrum resources with multiple DSA strategies simultaneously. To analyze the performance of the proposed MS-DSA system, we model it as a continuous-time Markov chain(CTMC) and derive the expressions to compute the corresponding performance metrics. Based on this, we define a utility function involving the concerns of effective throughput, interference quantity on primary users, and spectrum leasing cost. Two optimization schemes, named as spectrum allocation and false alarm probability selection, are proposed to maximize the utility function. Finally, numerical simulations are provided to validate our analysis and demonstrate that the performance can be significantly improved caused by virtues of the proposed MS-DSA system.
文摘为了减少物联网环境中对用户身份的漏报率,该文将传统的身份认证和行为认证相结合,提出了一种基于物联网的动态用户行为认证机制。建立了用户行为认证集,论述了整个机制的实现过程。论述了确定的充分行为认证和不确定的必要行为认证,同时给出了每个认证过程的随机Petri网(Stochastic Petri Net,SPN)模型,并用Petri网量化分析了该机制对性能的影响和认证漏报率。理论分析表明:该机制在提高用户认证机制的安全性方面具有显著效果,同时性能良好。
