复杂网络环境下的DSR路由协议性能仿真

DSR是用于多跳无线Ad hoc网络的一个简单高效的路由协议,DSR协议由路由发现和路由维持两部分组成,允许节点在Ad hoc网络中发现、维持到任意节点的源路由.文章详细介绍了DSR协议的特点并利用Opnet Modeler 10.5构建了小规模(50节点)和大规模(100节点)复杂的(所有节点同时移动、所有节点既是源节点又是目的节点)移动自组网模型,通过改变节点移动速度及发送分组大小,对DSR路由算法的平均路由发现时间、平均路由长度、吞吐量、数据分组平均端到端的时延、及分组交付率在两种场景下进行了仿真分析和性能比较.     

基于DSR的改进型综合源路由协议

在无线Mesh网络中,动态源路由(Dynamic Source Routing,DSR)协议是一种广泛应用的协议,其路由的建立与维护都从源节点发起。然而,由于DSR协议在路由发现与建立的过程中存在局限性,因此仍需要进一步研究。基于DSR协议通过引入一种综合了路径负载率、时延和跳数的负载均衡机制,并加入能量状态监控和多径路由,提出了一种改进型综合源路由协议(Improved Comprehensive Multi-path Source Routing,ICMSR),能够更好地实现网络负载均衡,节约网络能源,提升网络性能。最后,使用Opnet仿真验证了算法的有效性。仿真结果表明,改进协议在网络生存时间、分组投递率、端到端时延和网络吞吐量等性能指标上,相较于现有DSR协议都有较大的提升。     

GDSR：一种基于车载自组网的分组路由协议

针对DSR路由协议因节点频繁移动,路由发现和路由维护过程频繁发生,导致数据传输的时延增加和丢包率增加的问题.在DSR路由协议基础上,提出一种带有分组的DSR路由协议（GDSR）.该协议通过K-medoids聚类算法合理地选择组头,使得分组路由协议更加适合车载自组网的多变的拓扑结构.仿真结果表明,带有分组的GDSR路由协议能够降低数据传输的端到端的时延和丢包率.     

基于能量改进的DSR路由协议性能分析

本文简要介绍了Ad hoc网络中路由协议的特殊性，指出节点能量是Ad hoc网络中影响系统路由生存时间的关键性因素。在无线按需路由协议DSR的基础上，提出一种基于节点能量高低增加延时函数来选择路径的协议EDSR。仿真结果显示EDSR相对于DSR提高了系统生存时间。     

基于Q学习算法的Ad Hoc网络自适应DSR协议研究

提出了一种用于Ad Hoc网络改进的基于Q学习算法的自适应动态源路由(DSR)协议。该协议能在网络状态较好的情况下减小开销,在网络状况较差的情况下改善端到端时延和吞吐量性能。仿真结果表明,自适应Q-DSR协议能够提升传统DSR协议的性能,是简单高效的路由协议。     

基于蚁群优化的移动P2P网络路由选择算法

因为移动P2P网络具有动态性而且移动节点能量受限,提升移动P2P数据传输效率至关重要.利用蚁群优化算法,将蚂蚁的信息素与节点的能量和通信带宽结合起来,在蚁群选择路径时,减少其寻优路径上的信息素浓度,根据概率路由表中信息素的浓度对路由选择策略进行调整,避免网络拥塞和个别节点能量消耗过快,提出了一种移动P2P网络的多路径路由选择算法.实验结果表明,与EDSR路由协议相比,提出的算法能够降低节点的分组丢失率和端到端的平均时延,提高了网络的生存周期.     

Ad hoc网络两种按需路由协议性能分析

Ad hoc网络是一种无需依赖于事先布设的基础设施,而仅依靠网络内部节点之间的协作,就能够完成节点间通信的网络。比较了Ad hoc网络两种主流的按需路由协议：动态源路由协议,自组网按需距离矢量路由协议。使用基于ns-2的仿真模型进行仿真,并通过分组交付率、平均端到端时延、标准化路由负荷、对两种按需路由协议进行评估。实验结果表明即使DSR和AODV协议都是按需路由协议,但它们采取的路由机制的不同,导致它们的性能表现的巨大差异。     

高动态无线自组网路由协议设计

针对节点快速移动过程中网络建立时间较长,数据端到端传输时延无法得到可靠保 障,并且由于维护动态网络连接性造成网络开销较大等方面的问题,提出了一种无线自组网 路由协议,通过分簇算法快速将网络分为多个簇,每个簇包括簇首节点、成员节点和簇间网 关节点。该协议能够应用于快速移动节点构成的高动态无线自组织网络中,实现了先应式和 反应式路由算法进行了有机结合,能够在快速变化的拓扑结构中为未知路由提供优化的路由 结果,利用较小的网络开销实现网络快速构建和数据端到端的实时传输。     

MANET中基于DSR的一种最小能耗路由协议

如何高效地利用无线节点的有限能量是移动Ad Hoc网络(MANET)路由协议的一个重要考虑因素.鉴于动态源路由协议(DSR)没有考虑节点的能量限制,本文基于DSR协议提出了一种节能路由算法:MECP-DSR.它采用每报文能量消耗最小作为路由选取标准,并且在发送数据报文时对节点的发射功率进行控制.该文的仿真结果表明,MECP-DSR大大降低了节点的能量消耗,有效提高了移动Ad Hoc无线网络的生存期.     

基于第一跳节点累积的AODV协议改进

利用DSR协议的源路由策略,对AODV协议进行修改——在其路由发现过程中,将第一跳节点的地址信息添加到路由消息中。中间节点接收路由消息后,建立或者更新到达第一跳节点的路由。将修改后的协议称为AODV-FA协议,并在ns2中模拟仿真其路由性能。结果表明:相较于AODV协议,AODV-FA在分组传输率、平均端到端时延和归一化路由负载3个路由性能上均有提升。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.