622Mbps ATM网络线路加密机设计构想

介绍了一种可以加密ATM网络的声音、数据、图像信息,其上限速率为622Mbps的ATM网络线路加密机设计构想,设计构想考虑了密钥管理功能的实现。     

依靠弯道控导河势流路

在天然河道中，河势演变虽具有一定的随机性，但仍有一定的规律可循，在一个河段内，一般可归纳出2－3条基本流路，为控制河势变化，需要选择出一条基本流路进行河道整治，当连续发生枯水期或洪水期时，部分河段的河势可能出现大的变化，为防止不利河势向下游传播，可修建较长的龙头弯道工程，利用龙头弯道工程分段调整，控导河势，保持河势稳定。     

也谈轻型钢结构房屋柱基设计

对柱脚抗剪键的设置和计算中所取用的荷载组合提出个人观点,同时对轻钢结构柱脚螺栓受拉计算提出注意事项.     

基于"替换法"的汉字加、解密实现技术

文章讨论的基于“替换法”的汉字信息加、解密实现技术,改变了传统的汉字加密结果,使加密后的密文仍是可以识别和再利用的汉字,发送者可以在任何可编辑汉字的通讯设备上发送和接收密文,确保中文信息传输过程中的安全性。加、解密算法实现的代码语言为VFP6.0。     

IP电话的实现及其关键技术

IP电话在推出后短短十年的时间以其低价、高效、灵活的特点迅速发展起来。本文介绍了IP电话的基本结构，比较了IP电话与普通电话的优缺点，讨论了IP电话的相关协议及关键技术，在这些基础上进一步指出IP电话的发展趋势，相信IP将成为未来信息通信的主导技术。     

Interactive key frame selection model

Video summarization can provide a fine representation of the content of video stream and reduce a large amount of data involved in video indexing, browsing, and retrieval. Moreover, Key frame selection is an important step in the research of content-based video analysis and retrieval. Although there exist a variety of methods for key frame selection, they are heuristic and closed systems, which cannot dynamically generate video summary with user’s preference. In this paper, an M-estimator and epipolar line distance constraint camera motion estimation algorithm is introduced as camera parameters is an important motion feature for key frame selection, and Broyden-Fletcher-Goldfarb-Shanno (BFGS) method is applied to optimize estimated parameters. Moreover, since Interactive Computing is a novel-computing model that represents the transition of algorithm to interaction, an interactive model of key frame selection (IKFS) is presented as a result of improving the model of key frame selection (KFS). The model of KFS and IKFS are proved to satisfy the criterion of induction and coinduction, respectively. Experimental results show that the processing scheme generates flexible and desirable summarizations whose distortion rate is lower than current method. Above all, IKFS is an extension to KFS.     

局域网通讯安全的实现

尽管当前有许多维护网络安全的策略，但是局域网内部通讯安全却往往被忽略，文章首先分析当前一些安全策略在维护局域网内部通讯安全的不足，然后提出一种具有加密功能的以太网网卡，用以解决局域网内部通讯的安全问题。     

On the design of multiple key hashing files for concurrent orthogonal range retrieval between two disks

This paper concerns the following problem: given a set of multi-attribute records, a fixed number of buckets and a two-disk system, arrange the records into the buckets and then store the buckets between the disks in such a way that, over all possible orthogonal range queries (ORQs), the disk access concurrency is maximized. We shall adopt the multiple key hashing (MKH) method for arranging records into buckets and use the disk modulo (DM) allocation method for storing buckets onto disks. Since the DM allocation method has been shown to be superior to any other allocation methods for allocating an MKH file onto a two-disk system for answering ORQs, the real issue is knowing how to determine an optimal way for organizing the records into buckets based upon the MKH concept.

A performance formula that can be used to evaluate the average response time, over all possible ORQs, of an MKH file in a two-disk system using the DM allocation method is first presented. Based upon this formula, it is shown that our design problem is related to a notoriously difficult problem, namely the Prime Number Problem. Then a performance lower bound and an efficient algorithm for designing optimal MKH files in certain cases are presented. It is pointed out that in some cases the optimal MKH file for ORQs in a two-disk system using the DM allocation method is identical to the optimal MKH file for ORQs in a single-disk system and the optimal average response time in a two-disk system is slightly greater than one half of that in a single-disk system.     

Key processing with control vectors

A method is presented for controlling cryptographic key usage based on control vectors. Each cryptographic key has an associated control vector that defines the permitted uses of the key within the cryptographic system. At key generation, the control vector is cryptographically coupled to the key by way of a special encryption process. Each encrypted key and control vector are stored and distributed within the cryptographic system as a single token. Decryption of a key requires respecification of the control vector. As part of the decryption process, the cryptographic hardware verifies that the requested use of the key is authorized by the control vector. This article focuses mainly on the use of control vectors in cryptosystems based on the Data Encryption Algorithm.     

视频特技切换台的原理与功能

本文较系统、通俗地介绍了模拟视频特技切换台的矩阵输入、混合/效果放大器(M/E)、下游键、系统控制和同步发生器等电路单元,介绍了特技切换台的切换、混合、扫变、键控的基本原理和功能。