查询词典 problem

In this paper, the concept of network security and security structures of OSI and Internet is introduced, and various threats confronting the computer network are also discussed. Several kinds of network information security technologies, including firewall technology, virtual private network, intrusion detection system, data encryption technology, identity authentication and security protocol etc. are also examined. The security of internal network is the biggest problem in the construction of each network. The solution to this problem lies in setting up a firewall. The theory of a firewall and the approach to its actualization is studied. Intrusion detection system, an important part of the computer network security system, has gained extensive attention. IDS monitors the computer and network traffic for intrusion and suspicious activities. It not only detects the intrusion from the extranet hacker, but also the intranet users. The emergence of virtual private network paves the way for realizing secure connection of LAN quickly and at a relatively low cost. The concept, function, key techniques, including the tunnel technology, and the ways to realize VPN are expounded in this paper. Also introduced is the data encrypt network technology, which is called the soul of computer network security, such as digital digest, digital signature, digital certificate, digital encrypt arithmetic and so on. At the same time, the principle and the process of implementing network security by digital certificate and digital signature, the basic principle and characters of security protocols, and finally, three of the security protocols, concerning the security problems in network, IPsec, SLL and SET are analyzed in detail Computer network system should be a system of dynamic defence, both dynamic and static, passive as well as active, and even offensive, combined with management and technology.

本文系统地介绍了网络安全的概念、OSI及Internet的安全体系结构，并讨论了计算机网络面临的各种安全威胁；内部网络的安全问题是每个建网单位面临的最大问题，可以认为防火墙技术是解决网络安全的一个主要手段，本文研究了防火墙的原理及其实现手段；作为一种主动的防御措施，入侵检测系统作为网络系统安全的重要组成部分，得到了广泛的重视，TDS对计算机和网络资源上的恶意使用行为进行识别和响应，不仅检测来自外部的入侵行为，也监督内部用户的未授权活动；虚拟专用网技术的出现，为实现网络间的连接提供了快速安全但又相对便宜的手段，本文较深入的探讨了实现VPN的隧道技术，并对VPN的概念、功能、实现途径、基本构成、关键技术及发展前景等问题进行了全面论述；数据加密技术是网络安全核心技术之一，本文从数据加密算法、数字摘要、数字签名及数字证书等几方面简要介绍了数据加密技术，并分析用数字证书和数字签名实现网络安全的原理和过程；对安全协议的基本原理、主要特点进行了较为深入的研究，并就网络的安全性问题剖析了三种安全协议：IPsec协议、SLL协议和SET协议。

Based on internal variable theory and damage theory, a damage-rheologic constitutive equation for one dimensional problem was then developed, and it was extended to three dimensional problem.

根据对试验结果的进一步分析，在总结前人工作的基础上，提出了岩石类材料的损伤演化的概率——遗传模型，建立了材料的一维流变损伤本构方程，并将其推广至三维问题。

This is a very first bottom of the sea diorama I've made, having thought long and easy over the problem, encasement on 3 sides should give a good impression of under the waves, the diver with no bubbles was a disappointment, I asked and got several replies on this problem as to the colour of the seabed, so going with a mix of sand and mud, I thought this would cover most of the angles.

这是我做的最早的海底场景，考虑了很久，易于问题，三面装箱应该提供一个好的水下效果，潜水员没有气泡令人失望，在这个问题我询问并获得若干的答复，如海床的颜色，与之相配的沙子和淤泥，我认为这将涵盖了最多的角度。

In 1976, S. Chandrasekhar solved the decoupling problem of the Dirac equation with non-zero rest mass in a Kerr background, thus provided the possibility of attacking the problem of the Hawking evaporation of Dirac particles.

在Kerr背景时空中求解Dirac方程是一个长期没有解决的问题。1976年Chandrasekhar成功地找到了Kerr背景时空中静止质量不为零的Dirac方程的退耦和分离变量的量子方程。

Then, the problem of using yard engines becomes the problem of directed paths decomposition for directed graph.

通过分析运用调机时区集合上的偏序结构特点，可以知道使用调机问题的实质是偏序集合的全序分解问题。

The numerical algorithms of the direct acoustic scattering problem with the Dirichlet boundary condition is studied,which is the foundation of the inverse acoustic scattering problem.

数值求解Dirichlet边界条件下的声波障碍散射正问题，这是声波散射反问题的研究基础。

First, we extend the general finite element method from the function surface to the parameter function. Second, we bring this kind of method into the design of rational Bézier minimal surface. Third, we transform the problem of Dirichlet energy function into the problem of minimizing a discrete objective function.

首先推广了函数曲面中的有限元方法，进而研究如何针对参数曲面使用有限元方法，并把该方法引入到有理Bézier极小曲面造型的设计中，从而将连续的Dirichlet能量函数极小化问题，转化为一个离散形式的目标函数的极小化问题。

Therefore, based on probability theory and its links with the Dirichlet problem, we propose a new numerical method for the Dirichlet problem to remove the above weaknesses.

为此，本文以概率理论及其与Dirichlet问题之间的联系为基础，提出了一种Dirichlet问题的数值方法，以解决上述存在的种种问题。

In Chapter 1, the present conditions of numerical methods for the Dirichlet problem, the probability theory which connects with the Dirichlet problem, and the essence and characteristics of the probabilistic numerical method are summarized.

第一章综述了Dirichlet问题数值解的现状、与Dirichlet问题密切联系的概率理论以及概率数值方法的实质和特点。

On Dirichlet Problem of Singular Quasilinear Elliptic Equations;;Mathematics Analysis of Combustion Problem

中文题名奇异拟线性椭圆型方程Dirichlet问题；燃烧问题的数学分析

Nowadays, most of research are to build a transmutative Petri Nets through adding controlling place sets, controlling arc sets and controlling policy to the basic Petri Nets, while the Controlled Petri Nets could be used to argue many controlling theory problems conveniently and to induce many logically and physically supervisory and solve the Event Feedback Controlling Problems and State Feedback Controlling Problem in DEDS supervisory theory.

目前大多数的研究表现为在变形后的受控Petri网基础上，利用各种方法求得各种逻辑型、结构型控制器，解决DEDS监控理论中的事件反馈控制问题与状态反馈控制问题。

On one hand, there are discussions with the works council and union about extension of short time working up to the end of September.

一方面，有讨论，工程理事会和联盟关于延长工作时间短至9月底。