D2D协作边缘缓存系统中基于传输时延的缓存策略

为了满足5G系统低时延高可靠的需求,针对单缓存终端直传(D2D)协作边缘缓存系统,提出了一种基于传输时延的缓存策略.运用随机几何理论,将请求用户和空闲用户的动态分布建模为相互独立的齐次泊松点过程,综合考虑内容流行度、用户位置信息、设备传输功率以及干扰,推导出用户的平均传输时延与缓存概率分布的关系式.以平均传输时延为目标...     

LED用石墨烯复合透明电极厚度组合的仿真与优化

为降低石墨烯(Gr)透明电极与p-GaN之间的肖特基势垒与接触电阻,进行了将银、金、镍和铂四种金属或氧化镍作为中间层引入它们两者之间的尝试。使用有限元方法模拟研究了Gr与金属或氧化镍的不同厚度组合对LED的光、热和电特性的影响。发现:透明导电层的透光率和LED芯片的表面温度均随石墨烯和金属或氧化镍厚度的增加而降低;1.5nm的Ag、Ni、Pt,1nm Au或1nm的NiO_x分别与3层(3L)Gr复合时为优化厚度组合,其中,1.5nm Ni/3L Gr为最佳Gr/金属复合透明电极。     

Long‐Term Electrical and Mechanical Function Monitoring of a Human‐on‐a‐Chip System

The goal of human‐on‐a‐chip systems is to capture multiorgan complexity and predict the human response to compounds within physiologically relevant platforms. The generation and characterization of such systems is currently a focal point of research given the long‐standing inadequacies of conventional techniques for predicting human outcome. Functional systems can measure and quantify key cellular mechanisms that correlate with the physiological status of a tissue, and can be used to evaluate therapeutic challenges utilizing many of the same endpoints used in animal experiments or clinical trials. Culturing multiple organ compartments in a platform creates a more physiologic environment (organ–organ communication). Here is reported a human 4‐organ system composed of heart, liver, skeletal muscle, and nervous system modules that maintains cellular viability and function over 28 days in serum‐free conditions using a pumpless system. The integration of noninvasive electrical evaluation of neurons and cardiac cells and mechanical determination of cardiac and skeletal muscle contraction allows the monitoring of cellular function, especially for chronic toxicity studies in vitro. The 28‐day period is the minimum timeframe for animal studies to evaluate repeat dose toxicity. This technology can be a relevant alternative to animal testing by monitoring multiorgan function upon long‐term chemical exposure.     

基于误差理论的LED灯具光强分布测量精确度分析

基于误差理论将LED灯具光强分布测量结果与真值间的标准差作为测量精确度。在此基础上,分别以蝶型、朗伯型、聚光型配光分布的灯具为研究对象,对各灯具在选取不同角度间隔下测量得到的光强分布结果进行了分析,获得相应条件下的测量精确度和测量效率。结果表明,不同配光分布的灯具在测量光强分布时,为保证相同的测量精确度,所选的测量角度...     

Simple Detection Based on Soft‐Limiting for Binary Transmission in a Mixture of Generalized Normal‐Laplace Distributed Noise and Gaussian Noise

In this letter, a simplified suboptimum receiver based on soft‐limiting for the detection of binary antipodal signals in non‐Gaussian noise modeled as a generalized normal‐Laplace (GNL) distribution combined with Gaussian noise is presented. The suboptimum receiver has low computational complexity. Furthermore, when the number of diversity branches is small, its performance is very close to that of the Neyman‐Pearson optimum receiver based on the probability density function obtained by the Fourier inversion of the characteristic function of the GNL‐plus‐Gaussian distribution.     

车载通信方舱供电系统的设计与应用

结合工程实例,探讨如何设计高可靠性、安全的车载通信方舱不间断供电系统。由于车载通信方舱供电系统兼顾市电/电站集中供电方式,要确保通信系统稳定可靠、不间断地实施通信指挥,供电系统的设计尤为重要,除了满足一般供电系统的功能外,还应具有良好的机动性、环境适应性以及安全可靠等技术指标要求。文中从供电系统设计原则、设计过程等方面介绍了供电系统的设计方式,并分析了不间断电源的选型和蓄电池容量的选择等问题。     

α稳定分布下的加权平均最小p-范数算法

该文提出一种新的适用于α稳定分布噪声环境的自适应滤波算法,这种算法通过使加权平均误差函数的p-范数最小来实现自适应滤波.在这种算法的基础上,该文还得到两种新的动量LMP自适应算法.将这些新算法应用于估计AR模型的参数,计算机仿真的结果表明,该文提出的算法的性能比已有LMP算法的性能要更为优越.     

A class of generalized models for shadowed fading channels

The commonly used models for shadowed fading channels arise by compounding the Nakagami distribution with others such as the log-normal and gamma distributions. A distribution that is more flexible than the Nakagami distribution is the well known Weibull distribution. In this paper, we derive a collection of generalized models for shadowed fading channels by compounding the Weibull distribution with other distributions belong to some fifteen flexible families. We also illustrate the superior performance of these models over the standard Nakagami models.     

p型重掺杂应变Si1-xGex基区内建电场的物理机制

采用解析的方法计算了在基区掺杂为高斯分布,Ge组分分布为三角形分布和矩形三角形分布时基区内建电场的变化情况.重新拟合了价带有效态密度公式,并在计算内建电场时考虑了导带有效态密度的影响.发现加入Ge组分后引起的导带有效态密度变化、价带有效态密度变化以及禁带宽度变窄量变化对基区内建电场的影响要大于掺杂对内建电场的影响.Ge组分为三角形分布时,在总的Ge组分一定的条件下,内建电场从发射结到集电结逐渐变大.在任一给定位置x处,内建电场随着Ge组分的增加而增大.当Ge组分分布为矩形三角形分布时,对于给定的Ge组分转折点x1,基区内建电场从发射结到集电结缓慢地增大.在Ge组分恒定的区域,内建电场变化甚微,在Ge组分为线性缓变区域的同一位置x处,内建电场随Ge组分转折点x1的增大而缓慢地增大.此外,在x1附近内建电场变化有一个很大的陡坡.     

CDN与P2P结合的技术在流媒体分发和交付系统中的应用

从电信运营商的角度分析了CDN技术和P2P技术在流媒体分发和交付系统中各自的特点。在此基础上,将CDN与P2P技术相结合,提出CDN+P2P架构,并阐述了该架构实现流媒体分发和交付系统的优点。