为了解决物联网信道资源有限的问题以及提高物联网系统的信息时效性,考虑了包括一个主用户(primary user,PU)和两个次用户(secondary user,SU)节点的多接入认知无线电(CR)物联网系统模型。在PU工作状态和SU数据队列稳定的约束下,分别分...为了解决物联网信道资源有限的问题以及提高物联网系统的信息时效性,考虑了包括一个主用户(primary user,PU)和两个次用户(secondary user,SU)节点的多接入认知无线电(CR)物联网系统模型。在PU工作状态和SU数据队列稳定的约束下,分别分析了第一个SU节点在先来先服务(first come first served,FCFS)、后来先服务(last come last served,LCLS)以及包丢弃队列下的平均信息年龄(age of information,AoI),推导了在阈值策略下第二个SU节点的平均AoI。然后,提出了使第一个SU平均AoI最小化,并且第二个SU的平均AoI低于给定阈值的优化问题。优化问题的约束条件是凸的,但所得到的目标函数是非凸的,故引入了一种次优技术,利用双层凸优化算法得到最优解。仿真结果给出了所考虑优化算法在不同系统参数下的性能,该算法在不同系统参数和多天线影响下的性能表现良好。后续工作可以考虑扩展到两个以上次用户的CR物联网系统。展开更多
Consider the optimal dividend problem for an insurance company whose uncontrolled surplus precess evolves as a spectrally negative Levy process. We assume that dividends are paid to the shareholders according to admis...Consider the optimal dividend problem for an insurance company whose uncontrolled surplus precess evolves as a spectrally negative Levy process. We assume that dividends are paid to the shareholders according to admissible strategies whose dividend rate is bounded by a constant. The objective is to find a dividend policy so as to maximize the expected discounted value of dividends which are paid to the shareholders until the company is ruined. In this paper, we show that a threshold strategy （also called refraction strategy） forms an optimal strategy under the condition that the Levy measure has a completely monotone density.展开更多
In this paper, we consider the dual risk model in which periodic taxation are paid according to a loss-carry-forward system and dividends are paid under a threshold strategy. We give an analytical approach to derive t...In this paper, we consider the dual risk model in which periodic taxation are paid according to a loss-carry-forward system and dividends are paid under a threshold strategy. We give an analytical approach to derive the expression of gδ(u) (i.e. the Laplace transform of the first upper exit time). We discuss the expected discounted tax payments for this model and obtain its corresponding integro-differential equations. Finally, for Erlang (2) inter-innovation distribution, closedform expressions for the expected discounted tax payments are given.展开更多
In this paper, we consider the dual of the generalized Erlang (n) risk model under a threshold dividend strategy. We derive an integrodifferential equation satisfied by the expectation of the discounted dividends unti...In this paper, we consider the dual of the generalized Erlang (n) risk model under a threshold dividend strategy. We derive an integrodifferential equation satisfied by the expectation of the discounted dividends until ruin. The case when profits follow an exponential distribution is solved.展开更多
Because of the illposedness of soft field, the quality of EIT images is not satisfied as expected. This paper puts forward a threshold strategy to decrease the artifacts in the reconstructed images by modifying the so...Because of the illposedness of soft field, the quality of EIT images is not satisfied as expected. This paper puts forward a threshold strategy to decrease the artifacts in the reconstructed images by modifying the solutions of inverse problem. Threshold strategy is a kind of post processing method with merits of easy, direct and efficient. Reconstructed by Gauss-Newton algorithm, the simulation image’s quality is improved evidently. We take two performance targets, image reconstruction error and correlation coefficient, to evaluate the improvement. The images and the data show that threshold strategy is effective and achievable.展开更多
文摘为了解决物联网信道资源有限的问题以及提高物联网系统的信息时效性,考虑了包括一个主用户(primary user,PU)和两个次用户(secondary user,SU)节点的多接入认知无线电(CR)物联网系统模型。在PU工作状态和SU数据队列稳定的约束下,分别分析了第一个SU节点在先来先服务(first come first served,FCFS)、后来先服务(last come last served,LCLS)以及包丢弃队列下的平均信息年龄(age of information,AoI),推导了在阈值策略下第二个SU节点的平均AoI。然后,提出了使第一个SU平均AoI最小化,并且第二个SU的平均AoI低于给定阈值的优化问题。优化问题的约束条件是凸的,但所得到的目标函数是非凸的,故引入了一种次优技术,利用双层凸优化算法得到最优解。仿真结果给出了所考虑优化算法在不同系统参数下的性能,该算法在不同系统参数和多天线影响下的性能表现良好。后续工作可以考虑扩展到两个以上次用户的CR物联网系统。
基金Supported by the National Natural Science Foundation of China(No.10771119,No.11171179)the Research Fund for the Doctoral Program of Higher Education of China(No.20093705110002)The research of Kam C.Yuen was supported by a university research grant of the University of Hong Kong
文摘Consider the optimal dividend problem for an insurance company whose uncontrolled surplus precess evolves as a spectrally negative Levy process. We assume that dividends are paid to the shareholders according to admissible strategies whose dividend rate is bounded by a constant. The objective is to find a dividend policy so as to maximize the expected discounted value of dividends which are paid to the shareholders until the company is ruined. In this paper, we show that a threshold strategy （also called refraction strategy） forms an optimal strategy under the condition that the Levy measure has a completely monotone density.
文摘In this paper, we consider the dual risk model in which periodic taxation are paid according to a loss-carry-forward system and dividends are paid under a threshold strategy. We give an analytical approach to derive the expression of gδ(u) (i.e. the Laplace transform of the first upper exit time). We discuss the expected discounted tax payments for this model and obtain its corresponding integro-differential equations. Finally, for Erlang (2) inter-innovation distribution, closedform expressions for the expected discounted tax payments are given.
文摘In this paper, we consider the dual of the generalized Erlang (n) risk model under a threshold dividend strategy. We derive an integrodifferential equation satisfied by the expectation of the discounted dividends until ruin. The case when profits follow an exponential distribution is solved.
文摘Because of the illposedness of soft field, the quality of EIT images is not satisfied as expected. This paper puts forward a threshold strategy to decrease the artifacts in the reconstructed images by modifying the solutions of inverse problem. Threshold strategy is a kind of post processing method with merits of easy, direct and efficient. Reconstructed by Gauss-Newton algorithm, the simulation image’s quality is improved evidently. We take two performance targets, image reconstruction error and correlation coefficient, to evaluate the improvement. The images and the data show that threshold strategy is effective and achievable.
基金Supposed by the Fundamental Research Funds for the Central Universities of China and Jiangxi Agricultural University Youth Science Foundation(09003326)
