CAD/CAM 中 Undo/Redo 技术的研究

介绍了一种基于实体模型的ＣＡＤ／ＣＡＭ系统的Ｕｎｄｏ／Ｒｅｄｏ操作实现技术．它支持多层次嵌套的ＣＡＤ／ＣＡＭ建模环境．因而当用户在ＣＡＤ／ＣＡＭ系统环境中建模时,可以方便地对模型进行Ｕｎｄｏ／Ｒｅｄｏ编辑操作．     

SAP系统安全机制研究

通过笔者在项目实践中对SAP系统的深入了解,对SAP系统采用的安全机制,包括身份管理、权限管理、数据库可靠性支持,数据交互完整性保护、数据传输安全以及日志审计等方面进行了阐述.     

Windows删除文件的取证分析

随着计算机犯罪案件成指数增长,基于Windows的取证分析技术日益普遍,而犯罪嫌疑人掩盖证据最通常的做法就是将有用证据删除,因此,对这些删除文件进行取证分析显得更为重要.删除文件中很可能包含和案件相关的重要证据,如用户数据文件、声音文件等,文章结合数据恢复技术和Windows删除机制特点,提出了一种对Windows删除文件的取证分析方法,能够获取更多的用户信息,为重构案情,了解用户行为提供了更有效的依据.     

Windows7操作系统关键内存防攻击研究

GS Stack Protection、SafeSEH、Heap Protection、DEP、ASLR技术是Windows 7操作系统内存保护机制的关键技术,这五种技术对缓解缓冲区溢出攻击起到显著作用.文章以对Windows 7的内存保护机制的原理分析为基础,测试了Windows 7环境下绕过这些保护机制的可能性;最后对Windows 7内存保护机制抵御缓冲区溢出攻击的整体效果进行了分析,指出Windows7仍然不能完全抵御缓冲区溢出攻击,并讨论了更全面提高系统安全性的改进方案.     

矿井采空区无线传感器网络路由协议研究

研究和设计了一种适用于煤矿采空区的无线传感器网络路由机制。首先对LEACH协议的簇头选举机制进行了改进,在计算阀值时添加剩余能量参数,然后采用改进后的协议和多径路由机制设计了煤矿采空区无线传感器网络路由算法,最后通过NS-2仿真平台进行了实验。实验结果表明,改进后的协议与原协议相比,提高了网络中节点的能量有效性,延长了网络的生命周期。     

晶体振荡器温频特性自动测试系统

针对传统的人工手动方式对晶体输出频率随温度的变化进行测试和分析,存在着跟踪性能差、数据处理效率低、人为误差大和测试结果无法保存等诸多问题,设计开发了基于GPIB总线和485总线的自动测试系统,系统利用Mscomm控件和agt3494控件很方便地实现了PC对仪器设备的通信、参数设置以及数据读写,测试软件采用面向对象、消息机制的程序设计方法,增强了可读性、可移植性和故障处理能力,数据处理部分重点介绍了调用Excel数据分析功能函数的方法,简化了处理过程,最后试验表明,采用自动测试系统,效率比手工测试提高10倍以上,并且同时完成了数据分析及曲线、方程、报表的生成,大大提高了准确性,由此可知系统实用性强、实用价值高。     

应用型本科院校离散数学课程建设

介绍应用型本科院校离散数学课程建设的过程。从课程建设的目标、教学内容、教学方式方法、考试机制和网络教学环境等方面阐述离散数学课程的建设情况,重点介绍多种行之有效的教学方法。     

Restrictive mechanism of flow control among non-cooperative Internet users

The flow and congestion control methods based on one-shot game model with non-cooperative game theory can explain the non-cooperative behavior of Internet users.However,the low effciency of equilibrium solutions affects their utility.Here the behavior of flow and congestion control based on infinitely repeated game models is addressed;the repeated and infinitely repeated flow and congestion control game model is presented; the existence and optimization of the Nash equilibrium point are proved;the discount ...     

基于免疫赦免机制的智能分布式入侵检测系统

入侵检测系统是在网络系统遭受攻击之前进行拦截和响应的一种积极主动的安全防护系统。分布式智能入侵检测系统DIIDS(Distributed Intelligent Intrusion Detection System)就是在分布式环境中将人工智能技术应用于入侵检测中,从而可以提高IDS(Intrusion Detection System)的检测的实时性、准确性和容错性。本文设计了一种基于免疫赦免机制的DIIDS。该方法以降低入侵检测系统的时延性与提高入侵检测系统的智能性、恢复能力为核心,改善入侵检测系统的实时性。为实现用户信息的安全转移和检测系统自身的免疫进化,构建了一种免疫赦免智能Agent植入机制(IPAT),从而提高了系统的可用性。     

Two new control signal approaches for obtaining the MRAS-CDM and a real-time application

The coefficient diagram method (CDM) is one of the most effective control design methods. It creates control systems that are very stable and robust with responses without the overshoot and small settling time. Furthermore, all control parameters of the control systems are changed by varying some adjustment parameters in CDM depending on the demands. The model reference adaptive systems (MRAS) are the systems that follow and change the control parameters according to a given model reference system. There are several methods to combine the CDM with MRAS. One of these is to use the MRAS parameters as a gain of the CDM parameters. Another is to directly use the CDM parameters as the MRAS parameters. In the industrial applications, the system parameters can be changed frequently, but if the controller, by self-tuning, recalculates and develops its own parameters continuously, the system becomes more robust. Also, if the poles of the controlled systems approach the jw axis, the response of the closed-loop MRAS becomes more and more insufficient. In order to obtain better results, CDM is combined with a self-tuning model reference adaptive system. Systems controlled by a model reference adaptive controller give responses with small or without overshoot, have small settling times, and are more robust. Thus, in this paper, a hybrid combination of MRAS and CDM is developed and two different control structures of the control signal are investigated. The two methods are compared with MRAS and applied to real-time process control systems.