炉温微机控制系统优化设计

提出了炉温微机控制系统的优化设计方法,描述了硬件系统总体设计及工作原理,系统软件设计及主要流程.由于采用了一系列的优化设计和优化措施,该电阻炉微机控温系统取得了很好的效果.     

A Novel Approach to Solve the FMS Formation Problem

We propose in this paper a genetic algorithm (GA)-based approach to solve the Flexible Manufacturing System (FMS) formation problem. First, we divide the unity of machines into small groups or cells using Group Technology (GT). And an option for considering the minimization of workload variation between cells is included. Then the implementation is done using GA. When using GA, the designer is allowed to specify the number of cells and impose lower and upper bounds on cell size. This makes the GA scheme flexible for solving the FMS formation problems.     

访问控制原理与实现

随着计算机与网络系统的迅速发展,计算机系统提供的功能越来越强,同样,对于系统安全保护的要求也越来越高,系统中有众多的软件和硬件需要保护。例如硬件有各种内存、缓存,各种外部设备和接口等。软件有操作系统、文件、堆栈等。为保护资源的安全,早期通过对要保护的文件读写设置口令,用户只能利用口令访问该文件实现。这样用户需了解每个要访问文件的读写口令,很     

电子商务安全隐患及其对策

分析了电子商务的安全需求、面临的主要安全问题,并在对入侵行为进行分类研究的基础上,对电子商务活动流程的描述和脆弱点分析中研究了其安全对策.     

信息网络安全体系设计

网络信息安全的最终任务是保护信息的安全,为此,需要制定合理的安全体系,在安全体系指导下综合应用各种安全理论与技术。本文结合作者的体会,介绍安全体系设计知识。一个好的安全体系必须充分考虑安全需求、安全威胁、安全技术、安全指标、安全法规、安全实施、安全产品和安全代价等各方面的要素。本文侧重于从技术角度介绍安全体系设计的思路。     

Parallel Implementation of a Low Order Algorithm for Dynamics of Multibody Systems on a Distributed Memory Computing System

In this paper, a new hybrid parallelisable low order algorithm, developed by the authors for multibody dynamics analysis, is implemented numerically on a distributed memory parallel computing system. The presented implementation can currently accommodate the general spatial motion of chain systems, but key issues for its extension to general tree and closed loop systems are discussed. Explicit algebraic constraints are used to increase coarse grain parallelism, and to study the influence of the dimension of system constraint load equations on the computational efficiency of the algorithm for real parallel implementation using the Message Passing Interface (MPI). The equation formulation parallelism and linear system solution strategies which are used to reduce communication overhead are addressed. Numerical results indicate that the algorithm is scalable, that significant speed-up can be obtained, and that a quasi-logarithmic relation exists between time needed for a function call and numbers of processors used. This result agrees well with theoretical performance predictions. Numerical comparisons with results obtained from independently developed analysis codes have validated the correctness of the new hybrid parallelisable low order algorithm, and demonstrated certain computational advantages.     

在Windows环境下开发应力测试系统控制软件的研究

讨论了在Ｗｉｎｄｏｗｓ环境下用 Ｄｅｌｐｈｉ３开发半导体应力自动测量系统控制软件的方法和关键细节。介绍硬件与软件调试中要注意的问题。对 Ｗｉｎｄｏｗｓ环境下开发控制硬件工作的软件进行了探讨。     

非线性滤波及其在GPS航姿系统中的应用

ＧＰＳ航姿系统中如何快速、可靠地解算出航向姿态,依赖于载波相位模糊度的确定。对于测量噪声较在的接收机或模糊度只有浮点解的情况来说,ｋａｌｍａｎ滤波技术是确定模糊度的有效方法之一,但其滤波需要较长的时间。为了加快滤波的收敛速度,缩短ＧＰＳ航姿系统的初始化过程,文中提出了基于基线长度约束的非线性Ｋａｌｍａｎ滤波方法,并通过实验研究结果证明,该方法是确实可行的。     

Controlling IP Spoofing through Interdomain Packet Filters

The distributed denial-of-service (DDoS) attack is a serious threat to the legitimate use of the Internet. Prevention mechanisms are thwarted by the ability of attackers to forge or spoof the source addresses in IP packets. By employing IP spoofing, attackers can evade detection and put a substantial burden on the destination network for policing attack packets. In this paper, we propose an interdomain packet filter (IDPF) architecture that can mitigate the level of IP spoofing on the Internet. A key feature of our scheme is that it does not require global routing information. IDPFs are constructed from the information implicit in border gateway protocol (BGP) route updates and are deployed in network border routers. We establish the conditions under which the IDPF framework correctly works in that it does not discard packets with valid source addresses. Based on extensive simulation studies, we show that, even with partial deployment on the Internet, IDPFs can proactively limit the spoofing capability of attackers. In addition, they can help localize the origin of an attack packet to a small number of candidate networks.     

NetWare／FOXPRO数据库应用系统的安全

FOXPRO RDBMS是一种安全性很弱的关系数据库管理系统,而一般的FOXPRO数据库应用系统除了口令字机制之外,也很少有其它的保护措施。为此,本文提出一种称为“角色-视图”关系的适应于办公室环境的数据库访问控制策略。在这种策略的指导下,利用NO-VELL NetWare网络操作系统的安全机制,设计了一个在应用层上的FOXPRO数据库系统安全体系。本文所做的研究工作有两个特点：一是数据库系统安全的关键功能利用操作系统和机制来实现,所以系统整体在安全性、性能和开发费用上有较好的平衡;二是整个安全体系的设计符合安全工程的一般开发流程。