IP多播技术及其应用

本从IP多播技术的概念、基础知识，IP多播路由及其协议。IP多播路由中的隧道传输机制。IP多播技术的应用等方面。详细地介绍了IP多播技术及其应用。     

移动IP中的多播技术

本文结合距离向量多播路由技术（DVMRP）多播路由技术介绍了移运IP下的多播技术，指出其存在的问题，并给出了一个解决方案。     

IP多播路由协议技术及其标准

本主要分析了IP多播路由技术的产生,对IP多播体系结构及IP多播地址进行了阐述,并重点介绍了我国所规定的IP多播路由协议技术及其标准。     

关于IP多播路由协议的研究与分析

介绍分析了几种典型的IP多播路由协议，如距离向量多播路由协议、协议独立多播、多播开放最短路径优先和基于核心树的多播等，并对这几种IP多播路由协议进行了分析对比。     

IP多播中的路由技术

多播（ｍｕｌｔｉｃａｓｔ）是未来Ｉｎｔｅｒｎｅｔ中的一项重要业务。多播路由技术建立在点到点路由技术的基础上,介在寻路机制和路由结构上有很大区别。本介绍了ＩＰ多播机制、路由树的类型,以及目前已经应用的典型协议。     

IP多播中的路由技术

多播（ｍｕｌｔｉｃａｓｔ）是未来Ｉｎｔｅｒｎｅｔ中的一项重要业务。多播路由技术建立在点到点路由技术的基础上,但在寻路机制和路由结构上有很大区别。本文介绍了ＩＰ多播机制、路由树的类型,以及目前已经应用的典型协议。     

移动IP中的多播技术

本结合距离向量多播路由技术（DVMRP）介绍了移动IP下的多播技术，指出其存在的问题，并给出了一个解决方案。     

Ad Hoc网络中基于粒子群优化的QoS多播路由研究

针对Ad Hoc网络中带QoS约束的多播路由问题，提出了一种新的结合MAODV多播路由发现方法和粒．子群优化算法的QoS多播路由发现算法。仿真试验显示该算法较好地改进了端到端传输的代价、延时和带宽利用率，能够找到一棵消耗趋于最小、状态稳定的多播路由树。     

Ad Hoc网络中一种基于QoS的分布式多播路由算法

通过分析Ad Hoe网络的特点及基于QoS的多播路由问题，提出了一种新的分布式多播路由算法。实验和分析的结果表明，文中构造的路由方案成功地解决了Ad Hoe网中基于QoS的多播路由问题。当Ad Hoe网络的拓扑结构改变不太快时，本文提出的路由方案不仅满足了实时业务对网络带宽和端到端延时的要求，优化了路由树的代价，而且有效地控制了算法的复杂性并可适用于大规模的网络中。     

IP 多播路由协议的分析

分析介绍了几种典型的IP多播路由协议，如DVMRP、PIM、MOSPF和CBT等，并对这几种IP多播路由协议进行了分析对比。     

磁悬浮实验分析

本文通过磁悬浮实验装置,分析了磁悬浮力的两种理论算法,比较了这两种算法的误差并与实验结果做了对比,用软件仿真计算了单匝线圈等效模型的磁悬浮力的频变特性并与理论值对比。本文在此基础上提出了多匝线圈的等效建模方法。验证表明这种方法与实验结果更接近,能比较精确地计算出盘状线圈的受力情况。     

A New Solution for Simple Cooperative Relaying

In this paper we present a new simple cooperative relaying scheme. The proposed scheme is compared with simple cooperative schemes with virtual orthogonal space time block coding (OSTBC) and quasi orthogonal space time block coding (QOSTBC). Every of these three schemes includes one base station with two antennas, two relay stations each with a single antenna and one mobile station with a single antenna. The aim of the proposed scheme is to preserve, as much as it is possible bit error rate (BER) performance of the cooperative scheme with virtual OSTBC, but with increased code rate. It is shown that the presented scheme obviously outperforms simple cooperative scheme with virtual QOSTBC, while in comparison with simple cooperative scheme with virtual OSTBC has very similar BER performance and increased code rate.     

1．3μmDH-SLD的性能与工作电流和温度的关系

全面地测试并分析了掩埋双异质结型超辐射激光二极管模块的输出光功率、光谱和消光比与注入电流及温度的变化关系。得到：DH—SLD显示了软阈值特性,其输出光功率随注入电流的增大而增加,随管芯温度的升高而降低。温度不变时,当注入电流小于110mA(约)时,峰值波长随注入电流的增大而减小,当注入电流大于110mA(约)时,峰值波长随注入电流的增大有所增大;峰值波长随温度升高而增大。3dB带宽随注入电流的增大而减小,随温度的升高而略有增大。消光比随注入电流和温度的升高而变化。     

A reliability study of the lead-free solder connections of miniature chip components on hybrid circuits

The results of the influence of lead-free solder paste, design and process parameters on the attachment reliability of chip surface-mounted components (SMCs) on thick-film conductor pads are presented. The purpose of the investigation was to compare the quality of the soldered joints made with new solder pastes that do not contain lead with joints soldered with standard SnPb solders. The miniature zero-ohm chip resistors were soldered with selected lead-free solder pastes. The visual appearance of the solder joint according to the standards of lead-free soldered components was compared with components soldered with SnPb solders. On the test sample with soldered chip resistors connected in series, the solder-joint resistance was measured before and after temperature cycling. On the same test sample the solder-joint resistance changes were measured with impedance spectroscopy. After temperature cycling the damaged samples were analysed with SEM and EDS. The reliability test results after temperature cycling indicate two lead-free solder pastes that are the most convenient for chip-component soldering on thick-film conductor pads with the reliability of the joints being equal or better than solder joints with Pb-containing solder paste.     

QPSO与K-Medoids相结合的带障碍空间聚类新算法

分析了现有的带障碍约束空间聚类算法,针对基于PSO优化的带障碍约束的K-Me足,提出了QPSO与K-Medoids算法结合的带障碍空间聚类新算法(QKSCO).在带障碍约束的空间条件下,该算法依据蚁群格网障碍距离作为聚类依据,引入了QPSO的快速全局收敛的特性,使之与K-Medoids算法的局部收敛特性相得益彰.实验结...     

High-speed InP/InGaAs avalanche photodiodes with a compositionallygraded quaternary layer

InP/InGaAs avalanche photodiodes (APDs) with a compositionally graded quaternary layer at the heterointerface between the InGaAs absorption and InP multiplication regions were fabricated and tested. A comparison of samples with the graded layer and with conventional three quaternary layers showed that the frequency characteristics for samples with the graded layer did not deteriorate at a low bias voltage even below -100°C, unlike APDs with three InGaAsP layers. Thus, no hole trapping occurred at the InP/InGaAs heterointerface with the graded layer. A sample with the graded layer showed a cutoff frequency exceeding 9 GHz at a low multiplication factor of 2. The authors found InP/InGaAs APDs with the compositionally graded quaternary layer to be useful over a wide temperature range     

1.55 mu m multiquantum-well lasers with record performance obtained by atmospheric pressure MOVPE using organometallic phosphorus precursor

The recently available precursor biphosphinoethane (BPE) was used, alongside with phosphine and with tertbutylphosphine (TBP), to grow advanced multiquantum-well (MQW) laser wafers with five quaternary, compressive strained wells. The lowest threshold current densities and the lowest optical losses were obtained with BPE. In particular, the lowest threshold current density, 328 A/cm/sup 2/, is a record among published values for lasers with five wells. In this comparison, the wafer grown with phosphine came a close second and that grown with TBP was third.<>     

生长系统对高阻区熔硅单晶径向电阻率变化的影响

分别采用L4375-ZE区熔炉和CFG/1400P区熔炉,生长了N型、(1.5～4.5)×103Ω.cm和P型、(1.0～5.0)×104Ω.cm两种规格的高阻区熔硅单晶,单晶的直径为52～54 mm,晶向为<111>。经对单晶的电阻率及其径向分布进行检测对比后发现,在加热线圈几何结构(包括上下表面角度、内径尺寸及台阶设计)基本相同、单晶生长速率相同且上、下晶轴旋转具有相同配置的情况下,不同的单晶生长系统所生长的单晶,其电阻率径向均匀性有明显差异,用L4575-ZE区熔炉生长的单晶的电阻率径向分布更均匀。     

液体介质三维光子晶体禁带可调性能研究

研究了宽频折射率可调液体介质在三维光子晶体上的应用。设计了完美结构的液体光子晶体,采用 平面波展开法和有限时域差分法研究了液体介质的介电常数对光子晶体带隙的影响规律;采用光固化快速成型技 术制造了完美结构光子晶体模型,通过灌注不同介电常数的液体介质,发现液体光子晶体的电磁带隙频率随液体媒 介介电常数的升高而向低频移动,其禁带相比于传统液晶可调光子晶体有所拓宽。     

数字图像拼接篡改盲取证技术研究

研究图像的篡改识别问题,由于数字图像能够被轻易的篡改并且很难发现改动痕迹,对篡改像素不融合现象识别不清,导致图像篡改很难被肉眼识别。为解决上述问题,从篡改者的角度对目前流行的篡改手段做了新的分类,详细分析了各种篡改取证技术的优缺点。提出了一种基于统计特征分类的盲检测算法,实验表明,从图像的双谱幅值和相角检测可以准确识别出篡改后的图像,为篡改图像的识别提供了依据。