关于窃听与反窃听技术的分析

窃听与反窃听是在实际工作中经常会遇到的网络安全方面的技术问题，本文介绍了网络窃听原理及窃听程序的设计方法，分析了防范窃听的几种措施，并给出了检测窃听程序的几种方案。     

计算机无线局域网发展趋势

计算机通信的广泛应用促使无线局域网的迅速发展,论文介绍了无线局域网特点及其拓扑结构,介绍其产品分类及特点,追踪无线局域网的标准化进程,介绍了IEEE 802.11和HEPERLAN两种最流行的物理层和数据链路层标准,得出无线局域网系统未来发展趋势。     

二维溃坝水波MAC方法数值模拟

采用ＭＡＣ方法求解原始变量不可压缩非定常带自由面问题的Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程，对二维水坝瞬间溃决所产生的溃坝水波进行了数值模拟．计算结果表明，在坝溃决的很短时间范围内，液体运动的任一铅直断面上，均不符合静压分布，自由表面的形状类似一抛物线．     

宽带网满负荷试验对于UniLINK协议的验证

ＵｎｉＬＩＮＫ是一种基于现存有线电视网的介质访问控制层（ＭＡＣ）协议。该协议的设计适用于树型拓扑结构的宽带网络，且支持的距离从主控端到客户端可达１６０公里。ＵｎｉＬＩＮＫ协议基于一种改进的时分多路控制（ＴＤＭ）协议，支持固定、和保留三三种带宽分配策略，且会依据不同的网络负担动态地在三种策略中进行选择。目前，基于该协议的ＬＡＮＣｉｔｙ系列产品在上海有线电视台和上海交大的互联试验中被使用。基于该测试的     

具有模型不确定性的单值MAC鲁棒稳定性分析

给出基于脉冲响应模型下的单值模型算法控制(SMAC).采用一系列可能对象的脉冲响应来描述模型的不确定性,分析了SMAC闭环系统的鲁棒性,推导得出了几个鲁棒稳定性条件.这些结果有利于预测控制的设计和分析.     

集中式无线局域网的仿真

基于OPNET平台,构建出一个集中式无线局域网的仿真模型。对比分析了在轮询———应答MAC多址接入协议下,采用不同的物理层特征参数(跳频、直接序列)时,网络性能(吞吐量、媒体接入时延、丢包率)的差异,用以选取最佳解决方案。     

Oil Spill Dispersant Effectiveness Protocol. I: Impact of Operational Variables

The current U.S. Environmental Protection Agency protocol for testing the effectiveness of dispersants, the swirling flask test, has been found to give widely varying results in the hands of different testing laboratories. The sources of the ambiguities in the test were determined by considering several options in a rigorous systematic fashion. Options considered were variability among three operators and the variability and limitations of three analytical instruments in establishing a calibration curve for oil/dispersant mixtures. Other options included flask type, impact of operational variables (rotational speed, mixing time, settling time, and oil:dispersant ratio), development of a revised procedure for dispersant effectiveness, reproducibility and repeatability of the revised procedure, and development of selection criteria for screening of dispersants. A redesign of the test flask, which is characterized by having baffles with a stopcock at the bottom for sample collection, was deemed necessary to accomplish reproducibility within operator and between operators. The results indicated that the baffled flask provided a total coefficient of variation (variations within operator and between operators) less than 11% compared to above 100% in some cases for the swirling flask.     

Oil Spill Dispersant Effectiveness Protocol. II: Performance of Revised Protocol

The current U.S. Environmental Protection Agency (EPA) protocol for testing the effectiveness of dispersants for use in treating oil spills on the open water, the swirling flask test (SFT), has been found to give widely varying results in the hands of different testing laboratories. Part I addressed the sources of the ambiguities in the EPA SFT and the development of a new test referred to as the baffled flask test (BFT). In this part of the series, further experiments were conducted for estimating the repeatability of three operators in determining the effectiveness of 18 dispersants by both the EPA SFT and the BFT methods. Overall statistical analysis of the results indicated that the coefficient of variation by the BFT was only 7.8% compared to 21.9% for the EPA SFT. The mean percent effectiveness of the EPA SFT was only 19.7% as compared to 64.6% for the BFT. Proposed selection criteria for screening of dispersants for listing on the National Contingency Plan Product Schedule have been developed.     

The implementation of IEEE 802.16m protocol module for ns-3 simulator

This paper presents the first IEEE 802.16m medium access control (MAC) protocol module embedded in the network simulator version 3 (ns-3). The designed module provides a validation tool for researchers to verify simulated results related to the IEEE 802.16m. This module supports the basic MAC functions which includes an initial ranging (IR) function; four types of bandwidth request (BR) procedures; five types of standard-specified quality-of-service (QoS); a QoS-based transmission scheduler; an adaptive modulation and coding (AMC) selection function; a physical (PHY) layer with a channel propagation model. The designed module provides modification flexibility to adapt to other simulation modules. Various scenarios are simulated to show the capacity of the implemented IEEE 802.16m module in details. Results of different types of traffic are tested with the path loss effect on transmission to visualize the numeric capability of the module.     

MAC finite difference scheme for Stokes equations with damping on non-uniform grids

In this paper, we consider the numerical methods for stationary Stokes equations with damping. The mark and cell(MAC) method has been applied to discretize the problem on non-uniform grids. We establish the LBB condition and the stability for the MAC scheme. Then we obtain the second order super-convergence in L2 norm for both velocity and pressure on non-uniform grids. We also obtain the second order convergence for some terms of H1 norm of the velocity, and the other terms of H1 norm are second order convergence on uniform grids. Numerical experiments using the MAC scheme show agreement of the numerical results with theoretical analysis.