通过多信道传送多密码来提高系统的信息安全性

随着计算机技术和信息技术的飞速发展,信息安全不仅是军事外交领域独有的东西,更变成与我们日常生活紧密相关的一个组成部分。在我们现在的日常生活中,时时刻刻都在和密码以及信息安全打交道,而密码作为信息安全保护的一把钥匙,在其中扮演着＂守护神＂的角色。所以,密码的安全使用或者说不被窃取就显得至关重要了,像诸如各种银行卡、网上银行、门禁卡以及各种购物卡会员卡等的密码保障都在其中。本文着重就密码传输方面的安全性来讨论其对系统信息安全性的影响。     

Complexity-reduced ICI cancellation for OFDM system over doubly-selective channels

In doubly-selective fading wireless channel,the conventional orthogonal frequency division multi-plexing(OFDM)receivers for inter-carrier interference(ICI)compensation require extensive computa-tions.To obtain an effective balance between performance and complexity,the whole channel responsematrix was decomposed into a sequence of submatrix,and then a novel equalizer based on minimum meansquare error(MMSE)criterion was presented to combat the ICI.Furthermore,a simple ordering-baseddecision-feedback equa...     

WBHF通信中大气脉冲干扰的仿真与实现

本文针对短波信道中大气脉冲干扰的特点,采用宽带模型对其进行仿真和实现。对大气脉冲干扰的三个参数:脉冲幅度,脉冲持续时间,脉冲间隔时间分别建模并阐述具体实现方案和实现步骤。其中脉冲幅度采用Hall模型;脉冲持续时间,脉冲间隔时间采用Fishman等人提出的两种状态的更新过程模型,并用典型参数在Matlab中进行了仿真和实现。     

一类信道分布的分解

信道在通信系统的一般模型中占有重要的地位.信道分布作为概率和可测函数都与信号的取值集合和信号取值的时间集合有着密切的关系.利用测度论的技巧,在形式上将信道分布分解为四部分,每一部分可以看作信号由某种的输入空间到相同或不同输出空间的信源,这种分解有助于对信源的其他性质和函数空间上算子性质的讨论.     

LVR-60R催化裂化催化剂的应用与优化

炼油催化装置因自身条件限制,对催化剂单程转化率和生焦产量等方面要求苛刻,本文开发的LVR-60R催化剂,与国内常用LV-23催化剂相比,重油转化能力和生焦选择性等性能方面都有明显的提高.LVR-60R催化剂使用过程平稳,流化良好,试用优化后,主要指标达到国外催化剂水平.目前LVR-60R催化剂已成为南充炼油化工总厂催化裂化装置的主力催化剂,试验结果显示,装置总液收收率和焦炭产率达到了国外催化剂先进水平.     

GSM空中接口

GSM——泛欧数字蜂窝通信系统,是目前全球移动通信用户使用最多的系统。GSM数字蜂窝通信系统在整个系统中有多个接口,其中无线接口Um,即空中接口,是系统最重要的接口。     

Dempster-Shafer （D-S） algorithm with credit scale in spectrum sensing

In cognitive radio, the detection probability of primary user affects the signal receiving performance for both primary and secondary users significantly. In this paper, a new Dempster-Shafer (D-S) algorithm with credit scale for decision fusion in spectrum sensing is proposed for the purpose to improve the performance of detection in cognitive radio. The validity of this method is established by simulation in the environment of multiple cognitive users who know their signal to noise ratios (SNR) and a central node. The channels between the cognitive users and the central node are considered to be additive white Gaussian noise (AWGN). Compared with traditional data fusion rules, the proposed D-S algorithm with credit scale provides a better detection performance.     

色质联用分析炮制工艺对侧柏叶挥发油的影响

侧柏叶为中医临床用于各种出血症之常用药物之一，历来有生用与制用之分，现今一般认为侧柏叶具有清热凉血、止咳祛痰、生发乌发的作用；侧柏炭则偏于收涩止血，多用于各种出血症．侧柏叶所含主要成分为黄酮类、鞣酸、挥发油等等．侧柏叶中挥发油的作用国外学者研究涉及较少，仅有人用气液层析和氧化铝层析从侧柏的针叶和树枝中分离出挥发油，     

A relay selection scheme based on geometric optimum in cooperative cognitive systems over mixed channels

This paper proposes a relay selection scheme based on geometric optimum principle to maximize the cognitive link＇ s connectivity with limited interference to primary user in cooperative cognitive systems. A dual-hop cognitive relay system is considered, in which the channel impulse response follows independent non-identical distribution （i. n. d. ） each hop, such as Rician, Rayleigh and Nakagami-m distribution. Then, closed-form expressions in terms of outage probability and average bit error rate （ABER） are obtained using amplify-and-forward （AF） relaying protocol over such mixed fading channels. Furthermore, the best range of the relay is derived. Extensive simulation re- suits are conducted to verify the theoretical analysis, which is useful to the network optimal design.