基于OPNET软件的动态源路由协议仿真实现

在MANET路由协议的研究与开发过程中．建模与仿真是评估不同方案的性能影响的一个非常重要的手段。利用OPNET仿真平台以及OPNET模型库中的无线节点模型构建了Ad hoc网络中动态源路由协议(DSR)仿真模型，对不同网络环境下的协议性能进行了分析比较，仿真结果表明，该算法对于对于移动环境下的动态路由适应性较好。     

Ad hoc网络按需路由协议DSR性能研究

该文对无线自组网Ad hoc的基于源驱动的按需路由选择协议DSR进行了系统研究,并利用通信网络仿真建模软件OPNET对全部采用固定节点的Ad hoc网络利用DSR作为其路由协议,分设场景进行仿真,并对DSR协议随着节点数增多所表现出来的性能进行了较为详尽的比较和分析。     

Ad hoc网络按需路由协议DSR性能研究

该文对无线自组网Ad hoc的基于源驱动的按需路由选择协议DSR进行了系统研究,并利用通信网络仿真建模软件OPNET对全部采用固定节点的Ad hoc网络利用DSR作为其路由协议,分设场景进行仿真,并对DSR协议随着节点数增多所表现出来的性能进行了较为详尽的比较和分析.     

基于OPNET的无线传感器网络仿真

OPNET是目前广泛使用的可用于网络仿真及协议分析等的仿真工具软件。本文以LEACH协议为例，阐述了基于OPNET平台进行无线传感器网络协议仿真的一般过程。首先本文简要描述了LEACH协议的网络模型以及能量模型，随后介绍了利用OPNET进行LEACH协议建模的步骤。最后给出并分析了仿真结果。     

移动Ad hoc网络仿真工具比较

仿真是移动Ad hoc网络研究的重要方法,仿真工具常用于新协议的设计和性能评估,以及大型复杂网络的构建和优化.文中详细介绍了OPNET、NS-2、GloMoSim/Qua1Net、OMNoT++的内部体系结构和对Ad hoc网络的支持,最后总结了四种仿真工具的特点和性能.     

基于Ad hoc的按需路由协议DSR的优化研究与实现

无线Ad hoc网络是一种不需要基础设施的自组织和自管理网络,网络中所有的节点同时具有终端和路由器的功能。因此网络可以通过节点路由发现机制转发分组,并进行路由维护。文中对DSR(动态源路由协议)的路由发现过程进行了优化,并采用OPNET仿真软件对基于DSR协议的Ad hoc网络的路由开销和时延等关键参数进行了仿真统计,分析了改进后的路由协议对网络质量的影响。     

Ad Hoc网络中两种按需路由协议的比较

Ad hoc网络的特征是多跳的无线连接，网络拓扑的频繁变化，以及需要有效的动态路由协议。重点比较Ad hoc网络中两种主要的按需路由协议：动态源路由（DSR）协议和Ad hoc按需距离矢量路由（AODV）协议。尽管DSR和AODV都是按需路由协议，但不同的协议机制导致了网络性能的显著差异。在OPNET仿真平台下，对采用不用路由协议的网络时延和吞吐量进行比较，从而分析不同的路由机制引起的网络性能差异。     

基于OPNET仿真平台的AODV协议的性能研究

AODV(Ad hoc On-demand Distance Vector Routing)路由协议是面向移动Adhoc网络的,在介绍了移动Ad hoc网络的特征、现有路由协议和AODV路由协议的发展过程之后,重点分析了AODV协议的特征、路由建立、维护过程,并基于OPNET平台仿真了AODV协议的性能(包括路由发现时间、协议效率、平均跳数、数据吞吐量),总结了目前AODV协议存在的问题及其改进的主要方法,最后对AODV协议改进的前景进行了预测。     

基于OPNET的Ad hoc路由协议比较与分析

在过去的几年中，人们对于Ad hoc网络进行了大量的研究，由于Ad hoc网络自身的特殊性，其路由协议的设计与传统固定网络有很大不同，因而也成了研究的焦点之一。丈中首先介绍了Ad hoc网络中的路由协议设计的几种策略，接着介绍了几种典型的Ad hoc路由协议，最后通过OPNET仿真并获取数据，通过考察路由发现时间、传输时延、路由跳数及网络吞吐量等性能指标，对两种典型路由协议进行综合评测，进而给出了结论，并对未来的研究指出了方向。     

短波Ad Hoc路由协议仿真与性能分析

为找到一种适合短波Ad hoc网络使用的路由协议,通过OPNET仿真软件对短波信道进行建模,在该模型的基础上对无线Ad Hoc常用的3种路由协议:优化链路状态路由(Optimized Link State Routing,OLSR)、反应式路由中的动态源路由(Dynamic Source Routing,DSR)和按需距离矢量(Ad hoc On Demand Distance Vector,AODV)进行仿真分析。仿真结果表明,OLSR路由协议网络时延最小、吞吐量最高和数据丢失率最低,其整体性能优于AODV及DSR路由协议,更适合于短波信道,但是OLSR路由协议也存在着开销高的不足,下一步可以针对降低路由开销进行研究。     

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.     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.