Nested and interleaved direct sequence spread spectrum to enhance CDMA security and bit error rate performance

Two new methods, the nested direct sequence spread spectrum and interleaved direct sequence spread spectrum, are introduced in view of the previously investigated spread spectrum methods. In the nested direct sequence method, the security is maintained, and the cross‐correlation between different codes resulting in multi‐user interference that corresponds to BER performance is improved, while in the interleaved direct sequence spread spectrum, the security is improved and BER performance is maintained. Both methods are analysed by mathematical relations as well as computer simulations and are compared with the existing methods. Copyright © 2016 John Wiley & Sons, Ltd.     

浅谈我国石油钻机司钻控制系统存在的问题

从设计心理学和人机工程学的角度对国产石油钻机司钻控制系统进行调查,发现普遍存在问题。本着“以人为本”的设计理念,对设计发展方向提出一些建议。     

多个终端同时接入ISDN的技术问题

本文描述了多个终端同时接入 ISDN 时,在 S/T 接口的控制枝术和传输性能分析,井给出了 S/T 接口激活/解除激活的试验电路.     

异步CDMA在多径环境下的最优接收算法

讨论了多用户异步ＣＤＭＡ系统中多径信号的最大然检测问题,同时给出算法的具体实现,算法中,每一条多和戏信号等效为一个独立的单用户。算法的复杂度分析表明,虽然等效用户数增加,但是实际检测算法的复杂渡并没有增加,其结果有助于分析ＣＤＭＡ接收机性能的上限。     

ATM信令适配层协议的软件实现

随着ＡＴＭ技术的发展,Ｂ－ＩＳＤＮ的终端或网络设备不要避免地要实现必备的信令功能,ＳＡＡＬ在宽带ＩＳＤＮ信令系统中处于最基本的位置。运用面向对象的方法对ＳＡＡＬ的软件实现进行了研究。     

A Fuzzy-Based Approach to Stereotype Selection in Hypermedia

This paper presents a stereotype-based user model for adaptive hypermedia systems. We use a suitable algebraic fuzzy structure which can adequately reflect some features of the user in the model, and apply this model to adapt the navigation and the content of hypermedia nodes to the user's needs. The model includes temporal representations of the user and approximates every real user by a set of stereotypes, from which the one realizing the best approximation can always be extracted. The set of stereotypes is the support set of the structure and the operations defined therein may be supplied with adequate semantics which allow for the selection of the stereotype.     

A Comparison of Measures for Detecting Natural Shapes in Cluttered Backgrounds

We propose a new measure of perceptual saliency and quantitatively compare its ability to detect natural shapes in cluttered backgrounds to five previously proposed measures. As defined in the new measure, the saliency of an edge is the fraction of closed random walks which contain that edge. The transition-probability matrix defining the random walk between edges is based on a distribution of natural shapes modeled by a stochastic motion. Each of the saliency measures in our comparison is a function of a set of affinity values assigned to pairs of edges. Although the authors of each measure define the affinity between a pair of edges somewhat differently, all incorporate the Gestalt principles of good-continuation and proximity in some form. In order to make the comparison meaningful, we use a single definition of affinity and focus instead on the performance of the different functions for combining affinity values. The primary performance criterion is accuracy. We compute false-positive rates in classifying edges as signal or noise for a large set of test figures. In almost every case, the new measure significantly outperforms previous measures.     

基于MATLAB的图形用户界面(GUI)设计

MATLAB6.x的GUIDE是专门用于图形用户界面 (GUI)程序设计的快速开发环境。从介绍GUIDE入手 ,结合具体的软件图形界面实例 ,给出了利用GUIDE制作图形用户界面的基本方法。在该例子中 ,利用GUIDE设计的界面不仅可以对输入的数据进行曲线拟合 ,建立数学模型 ,而且还可以通过此模型作进一步的预测和分析 ,界面友好 ,具有开放性 ,方便用户不断地完善和扩充其功能。