大规模流媒体多播系统中动态流量控制机制

提出一种边缘到边缘的动态流量控制机制-e2e-DFCM.e2e-DFCM工作原理是:发送端视频网关SVG对携带视频流质量标识QLI的报文聚集并重新进行QoS等级映射,接收端视频网关RVG周期地发送延迟、报文丢失等多播流状态信息;SVG根据QLI和RVG反馈的多播流状态信息对报文进行重新映射和分类,并基于效用动态分配各等级带宽,一旦接收端的服务质量不满足要求(平均延迟、丢失率超出承受范围),RVG甚至要求降级,SVG将降低发送速率.最后给出的模拟验证了e2e-DFCM机制的有效性.     

高性能新型交换结构综述

 目前基于单级交换结构(single-stage switch)集中式调度的路由器已经不能满足Internet网络流量、网络规模和上层应用的快速发展.近年来,旨在提高路由器可扩展性、吞吐率、QoS能力的高性能交换技术,成为路由器技术研究中的一大热点.文章从体系结构、调度策略、QoS特性三个方面对高性能交换结构研究进展进行了综述,以可扩展性、实现复杂度、延迟和吞吐率保证、负载均衡及报文乱序为主要衡量指标分析比较了每一类交换结构调度算法的性能,最后提出下一步的研究课题和思路.     

Ag/Nd0.7Sr0.3MnO3陶瓷界面电输运性质研究

用渗银和银胶接触两种方法分别在多晶Nd_0.7Sr_0.3MnO₃陶瓷样品上制作电极,用两线和四线模式对两种接触界面的直、交流特性进行测量.结果发现:渗银电极与陶瓷样品之间具有很好的欧姆接触特性,两线、四线模式下的电阻测量值相近,并且没有电脉冲诱导电阻转变(EPIR)效应;而用银胶接触作电极时,V-I曲线表现出关于原点对称的非线性特征,并出现稳定的室温EPIR效应.两种不同方法制备的电极在交流电场下的输运也有很大差异:渗银电极阻抗 关键词： 界面 接触电阻 EPIR效应 钙钛矿结构锰氧化物     

求解薛定锷方程的有限元离散格点表象

提出了利用映射函数来调节有限元离散格点表象的格点分布,从而提高其数值效率．为了测试该新方法的数值效率,将其用于氢原子中电子的本征态和本征能量以及具有长程势的Cs₂分子三重态的振动能级的求解,并与最初的有限元离散格点表象方法作了比较．计算结果表明：利用格点映射的方法可以显著提高限元离散格点表象的数值效率     

一种多QoS需求的资源优化算法

用户的多QoS需求,使得网络服务中的动态资源属性值变化频繁,传统方法难于对这些动态资源进行分配.为解决这一问题,提出了一种处理多QoS需求的动态资源优化算法.算法引入混沌理论,结合优化算法与逼近理想解排序思想,将多个动态资源形成一个链表在这些资源的各个QoS需求间进行选择调度,并在迭代过程中使用并行算法来降低算法陷入局部最优解的可能性.实例验证了该算法求解该问题的可行性和有效性,具有较好的实际应用价值.     

强阿秒XUV激光脉冲下H_2+分子光电子能谱角分布非对称性

利用2D平面模型,求解了描述定向H_{_2}⁺分子和阿秒XUV脉冲相互作用的薛定谔方程,并求得光电子的角度分布．在计算模型中,采用基态1sσ_g和第一激发态2pσ_u的等比例混合态作为初始态,而激光脉冲的光子能量大于电离势,强度为10¹⁴ W/cm²． 计算结果表明,光电子角分布的非对称性和脉冲的宽度密切相关．这种非对称性实际上是由于初始态的基态和激发态的相干振荡而导致的．当使用长脉冲时,这种相干振荡的周期效应就会被平均而消失,从而产生的光电子能谱会呈对称角分布．     

Spin current and its heat effect in a multichannel quantum wire with Rashba spinben orbit coupling

Using the perturbation method, we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin—orbit coupling. The heat generated by the spin current is calculated. With the increase of the width of the quantum wire, the spin current and the heat generated both exhibit period oscillations with equal amplitudes. When the quantum-channel number is doubled, the oscillation periods of the spin current and of the heat generated both decrease by a factor of 2. For the spin current j_s,xy, the amplitude increases with the decrease of the quantum channel; while the amplitude of the spin current j_s,yx remains the same. Therefore we conclude that the effect of the quantum-channel number on the spin current j_s,xy is greater than that on the spin current j_s,yx. The strength of the Rashba spin—orbit coupling is tunable by the gate voltage, and the gate voltage can be varied experimentally, which implies a new method of detecting the spin current. In addition, we can control the amplitude and the oscillation period of the spin current by controlling the number of the quantum channels. All these characteristics of the spin current will be very important for detecting and controlling the spin current, and especially for designing new spintronic devices in the future.     

Eckardt叶轮二次流与射流尾迹结构研究

通过对Eckardt离心叶轮数值计算与实验结果的对比，分析半开式离心叶轮内部二次流的形成机理与分布，建立基本的半开式离心叶轮内部三维二次流模型；基于该二次流模型，对射流尾迹结构的特点与形成机理进行了详细的分析和说明。     

Room-temperature large photoinduced magnetoresistance in semi-insulating gallium arsenide-based device

It is still a great challenge for semiconductor based-devices to obtain a large magnetoresistance(MR) effect under a low magnetic field at room temperature. In this paper, the photoinduced MR effects under different intensities of illumination at room temperature are investigated in a semi-insulating gallium arsenide(SI-Ga As)-based Ag/SI–Ga As/Ag device. The device is subjected to the irradiation of light which is supplied by light-emitting diode(LED) lamp beads with a wavelength in a range of about 395 nm–405 nm and the working power of each LED lamp bead is about 33 mW. The photoinduced MR shows no saturation under magnetic fields(B) up to 1 T and the MR sensitivity S(S = MR/B) at low magnetic field(B = 0.001 T) can reach 15 T~(-1). It is found that the recombination of photoinduced electron and hole results in a positive photoinduced MR effect. This work implies that a high photoinduced S under a low magnetic field may be obtained in a non-magnetic semiconductor device with a very low intrinsic carrier concentration.