“民生新闻”研究:还有多少空间?——电视民生新闻研究(2003-2005)述评

本文在查阅、梳理这些论文的基础上,分析国内学界“民生新闻”的研究现状、研究涉及的主要内容及存在的不足,找出研究者尚未探寻的空间。     

Cryptanalysis of two password authenticated key exchange protocols based on RSA

In 2002, Zhu et al. proposed a password-based authenticated key exchange protocol based on RSA. Many researchers pointed out that Zhu et al.'s protocol is vulnerable to off-line dictionary attack. In 2003, Yeh et al. proposed an improved protocol. Recently, Lo and Yang-Wang pointed out that Yeh et al.'s improved protocol is also vulnerable to offline dictionary attack. To avoid this weakness existed in Yeh et al.'s protocol, Lo and Yang-Wang proposed two improved protocols. However, in this letter, we show that the Lo protocol is vulnerable to an active off-line dictionary attack and the Yang-Wang protocol is vulnerable to a passive off-line dictionary attack.     

Terahertz Semiconductor Quantum Well Devices

For eventually providing terahertz science with compact and convenient devices,terahertz (1～10THz) quantum-well photodetectors and quantum-cascade lasers are investigated. The design and projected detector performance are presented together with experimental results for several test devices,all working at photon energies below and around optical phonons. Background limited infrared performance (BLIP) operations are observed for all samples (three in total) ,designed for different wavelengths. BLIP temperatures of 17,13, and 12K are achieved for peak detection frequencies of 9.7THz(31μm) ,5.4THz(56μm) ,and 3.2THz(93μm) ,respectively. A set of THz quantum-cascade lasers with identical device parameters except for doping concentration is studied. The δ-doping density for each period varies from 3.2 × 1010 to 4. 8 × 1010cm-2. We observe that the lasing threshold current density increases monotonically with doping concentration. Moreover, the measurements for devices with different cavity lengths provide evidence that the free carrier absorption causes the waveguide loss also to increase monotonically. Interestingly the observed maximum lasing temperature is best at a doping density of 3.6 × 1010cm-2.     

Synchronized transform-limited operation of 10-GHz colliding pulse mode-locked laser

We report a 10-GHz colliding pulse mode-locked laser fabricated with integrated active-passive waveguides. The laser fabrication adopted a deep reactive ion etching and single-step metal-organic vapor phase epitaxy regrowth process for forming the buried heterostructure waveguide. Clean output pulses resulted from laterally tilting the active-passive interface and effectively suppressing residual back-reflections at the interface. Hybrid mode-locking resulted in a synchronized transform-limited sech/sup 2/optical waveform. Pulsewidth, chirp, timing jitter, and frequency-locking range were investigated through systematic device biasing condition optimization.     

秦山核电基地外围环境水体放射性水平监测

自1992年，浙江省辐射环境监测站对秦山核电基地外围环境放射性水平进行了连续的监督性监测。1992～2004年，基地外围环境水体放射性水平的监测结果表明：秦山核电基地外围地区陆地环境淡水（饮用水、湖塘水、井水）中总α、总β、^90Sr、^137Cs平均浓度分别为67、157、4．4、0．3mBq／L，^3H为1．4Bq／L，雨水中^3H为2．0Bq／L；正常排放下，基地附近海域水样中^90Sr、^137Cs平均浓度分别为1．4、0．7mBq／L，^3H为I．0Bq／L；第一期核电厂三回路冷却水总β、^90Sr、^137Cs平均浓度分别为2．6、4．1、1．0mBq／L，^3H为2．IBq／L，排放口海水^3H平均浓度为1．4Bq／Lo与运行前本底值和对照点监测值相比，秦山核电基地外围环境水体放射性水平在正常波动范围内，基地外围环境陆地淡水和附近海域海水没有受到放射性污染。     

基于嵌入式系统的Internet接口开发

针对目前大部分基于单片机、DSP和PLC等底层设备直接上网存在的困难,本文提出一种基于嵌入式系统的Internet接口实现方法,实现了低端设备与因特网的互连,为智能家电、智能大厦和远程监控等领域提供了一个经济快捷的通用接口,大大缩短了系统原有的开发周期。     

基于安全电子交易协议(SET)的网上银行身份认证

论文针对电子商务的发展对电子支付环境提出的要求,分别论述了安全电子交易协议、椭圆曲线密码的功能,比较了安全电子交易协议与SSL协议之间的差异以及椭圆曲线密码相对于RSA的优势,并由此讨论了基于椭圆曲线密码体制实现安全电子交易协议的身份认证。     

基于ORACLE/EJB的汉字模糊同音查询的实现

针对MIS领域以发音为检索条件的需求，在分析同音查询及模糊同音查询的基础上，基于ORACLE数据库和EJB组件，提出了一个简单而实用的解决方法并给出了实例验证。此方法具有简单实用、易维护、易集成和易扩展等优点。     

基于Petri网技术的交通信号相位调节研究

提出了一种将Petri网技术应用干交通信号控制系统之中的策略。应用Petri网对典型的交叉路口进行建模分析，通过设定相位次序来提高交通效率。该模型能够有效地描述交通过程中的动态行为，利于分析和验证，并且易于实现。     

基于PC104的水下航行器导航系统设计

导航系统是水下航行器的重要组成部分，为了实现水下航行器的精确导航，采用了以PC104工控计算机为核心、GPS定位和惯性导航相结合的导航系统的改进方案，给出了导航系统的工作原理及基本硬件组成，介绍了惯性测量单元、GPS、电子罗盘等传感器与主控计算机进行通讯的各个软件模块的功能，并使用了异步卡尔曼滤波器进行数据融合与航位推算；该系统在提高导航精度的同时还具有通用性，可适用于不同类型的水下航行器。