文件共享服务是对等网络中的一个重要应用,数据传输速率逐渐取代响应延迟成为影响用户体验的首要因素.文中研究了对等网络中的副本管理算法,这对于提高对等网络应用的可靠性,降低带宽消耗具有重要的意义.为了在广域网络存储系统中加速...文件共享服务是对等网络中的一个重要应用,数据传输速率逐渐取代响应延迟成为影响用户体验的首要因素.文中研究了对等网络中的副本管理算法,这对于提高对等网络应用的可靠性,降低带宽消耗具有重要的意义.为了在广域网络存储系统中加速文件共享并降低网络带宽消耗,文中提出了PLAR(Popularity and Locality-based Adaptive Replication)算法.PLAR采用了基于位置信息和流行度的复本管理算法,该算法还同时引入了混合式的服务器选择策略以及远程增强策略.PLAR算法在文中的Granary对等广域网存储系统中得到了实现.实验表明,通过PLAR算法下载速率平均能提高60%以上,有效提高了共享速度并减少带宽消耗.展开更多
In an acousto-optic modulator,the electrode shape plays an important role in performance,since it affects the distribution of the acoustic field.The acousto-optic modulator based on the conventional rectangular electr...In an acousto-optic modulator,the electrode shape plays an important role in performance,since it affects the distribution of the acoustic field.The acousto-optic modulator based on the conventional rectangular electrode has the problems of low energy efficiency and small modulation bandwidth due to an imperfect acoustic field.In this paper,a new serrated periodic electrode has been proposed for using acousto-optic modulator transducers.The proposed electrode has the following advantages.By using serrated periodic electrodes to suppress the sidelobes,the collimation of the acoustic field in the direction perpendicular to the light incidence is improved.This makes the acousto-optic modulator have a stable diffraction efficiency fluctuation and high energy efficiency.In addition,the electrode has a large divergence angle in the direction of light incidence,so a large bandwidth can be obtained.The simulations and experiments demonstrate that the serrated periodic electrode has an increased bandwidth and high energy efficiency.展开更多
Internet of Things （IoT） refers to an infrastructure which enables the forms of com- munication and collaboration between people and things, and between things themselves. In order to improve its performance, we pre...Internet of Things （IoT） refers to an infrastructure which enables the forms of com- munication and collaboration between people and things, and between things themselves. In order to improve its performance, we present a tradeoff between bandwidth and energy con- sumption in the loT in this paper. A service providing model is built to find the relation- ship between bandwidth and energy consump- tion using a cooperative differential game mo- del. The game solution is gotten in the condi- tion of grand coalition, feedback Nash equili- brium and intermediate coalitions and an allo- cation policy is obtain by Shapley theory. The results are shown as follows. Firstly, the per- formance of IoT decreases with the increasing of bandwidth cost or with the decreasing of en- ergy cost; secondly, all the nodes in the IoT com- posing a grand coalition can save bandwidth and energy consumption; thirdly, when the fac- tors of bandwidth cost and energy cost are eq- ual, the obtained number of provided services is an optimised value which is the trade-off between energy and bandwidth consumption.展开更多
机器类型通信设备(Machine Type Communication Device,MTCD)的成本与系统带宽密切相关,如何配置带宽以达到节约终端成本的效果,使得带宽的使用效率最大化十分重要。通过对终端成本模型进行数值建模,可以揭示带宽与成本之间的数学关系,...机器类型通信设备(Machine Type Communication Device,MTCD)的成本与系统带宽密切相关,如何配置带宽以达到节约终端成本的效果,使得带宽的使用效率最大化十分重要。通过对终端成本模型进行数值建模,可以揭示带宽与成本之间的数学关系,在第3代通用移动通信系统(Universal Mobile Telecommunications System,UMTS)中对MTCD成本进行数学建模,提出了一种基于成本效率的带宽优化方法。对该算法进行了理论分析和计算机仿真发现,所提带宽选择方法能够最大化单位成本的效益。仿真结果表明,MTCD的成本得到有效降低,并且功耗不会显著提升。展开更多
文摘文件共享服务是对等网络中的一个重要应用,数据传输速率逐渐取代响应延迟成为影响用户体验的首要因素.文中研究了对等网络中的副本管理算法,这对于提高对等网络应用的可靠性,降低带宽消耗具有重要的意义.为了在广域网络存储系统中加速文件共享并降低网络带宽消耗,文中提出了PLAR(Popularity and Locality-based Adaptive Replication)算法.PLAR采用了基于位置信息和流行度的复本管理算法,该算法还同时引入了混合式的服务器选择策略以及远程增强策略.PLAR算法在文中的Granary对等广域网存储系统中得到了实现.实验表明,通过PLAR算法下载速率平均能提高60%以上,有效提高了共享速度并减少带宽消耗.
基金supported by the National Key Research and Development Program of China(Nos.2021YFB3602500 and 2021YFB3602502)。
文摘In an acousto-optic modulator,the electrode shape plays an important role in performance,since it affects the distribution of the acoustic field.The acousto-optic modulator based on the conventional rectangular electrode has the problems of low energy efficiency and small modulation bandwidth due to an imperfect acoustic field.In this paper,a new serrated periodic electrode has been proposed for using acousto-optic modulator transducers.The proposed electrode has the following advantages.By using serrated periodic electrodes to suppress the sidelobes,the collimation of the acoustic field in the direction perpendicular to the light incidence is improved.This makes the acousto-optic modulator have a stable diffraction efficiency fluctuation and high energy efficiency.In addition,the electrode has a large divergence angle in the direction of light incidence,so a large bandwidth can be obtained.The simulations and experiments demonstrate that the serrated periodic electrode has an increased bandwidth and high energy efficiency.
基金ACKNOWLEDGEMENT We gratefully acknowledge anonymous revie- wers who read drafts and made many helpful suggestions. This work was supported by the National Natural Science Foundation of China under Grant No. 61202079 the China Post- doctoral Science Foundation under Grant No. 2013M530526+2 种基金 the Foundation of Beijing En- gineering the Fundamental Research Funds for the Central Universities under Grant No. FRF-TP-13-015A and the Technology Centre for Convergence Networks and Ubiquitous Services.
文摘Internet of Things （IoT） refers to an infrastructure which enables the forms of com- munication and collaboration between people and things, and between things themselves. In order to improve its performance, we present a tradeoff between bandwidth and energy con- sumption in the loT in this paper. A service providing model is built to find the relation- ship between bandwidth and energy consump- tion using a cooperative differential game mo- del. The game solution is gotten in the condi- tion of grand coalition, feedback Nash equili- brium and intermediate coalitions and an allo- cation policy is obtain by Shapley theory. The results are shown as follows. Firstly, the per- formance of IoT decreases with the increasing of bandwidth cost or with the decreasing of en- ergy cost; secondly, all the nodes in the IoT com- posing a grand coalition can save bandwidth and energy consumption; thirdly, when the fac- tors of bandwidth cost and energy cost are eq- ual, the obtained number of provided services is an optimised value which is the trade-off between energy and bandwidth consumption.
文摘机器类型通信设备(Machine Type Communication Device,MTCD)的成本与系统带宽密切相关,如何配置带宽以达到节约终端成本的效果,使得带宽的使用效率最大化十分重要。通过对终端成本模型进行数值建模,可以揭示带宽与成本之间的数学关系,在第3代通用移动通信系统(Universal Mobile Telecommunications System,UMTS)中对MTCD成本进行数学建模,提出了一种基于成本效率的带宽优化方法。对该算法进行了理论分析和计算机仿真发现,所提带宽选择方法能够最大化单位成本的效益。仿真结果表明,MTCD的成本得到有效降低,并且功耗不会显著提升。
