Dynamic duty cycle and adaptive contention window based QoS-MAC protocol for wireless multimedia sensor networks

Rapid penetration of small, customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. While the need to minimize the energy consumption has driven significant researches in wireless sensor networks, offering some precise quality of service (QoS) for multimedia transmission over sensor networks has not received significant attention. However, the emerging new applications like video surveillance, telemedicine and traffic monitoring needs transmission of wireless multimedia over sensor networks. Naturally, offering some better QoS for wireless multimedia over sensor networks raises significant challenges. The network needs to cope up with battery-constraints, while providing improved QoS (end-to-end delay and bandwidth requirement). This calls for a suitable sensory MAC protocol capable of achieving application-specific QoS. In this paper, we have proposed a new QoS-based sensory MAC protocol, which not only adapts to application-oriented QoS, but also attempts to conserve energy without violating QoS-constraints. Performance modeling, analysis and simulation results demonstrate that the proposed protocol is capable of providing lower delay and better throughput, at the cost of reasonable energy consumption, in comparison to other existing sensory MAC protocols.     

网上电子支付系统分析

介绍了电子支付系统的基本概念,重点讨论了基于SET协议下电子支付系统的结构、支付流程,以及支付系统中所涉及的各项费用。     

桥CA在B2B EC中的应用与实现

分析了不同的PKI体系结构,论述了不同PKI信任域间实现互连存在的困难。为了解决在B2B EC模式下不同企业CA间的相互认证问题,提出了利用桥CA对不同企业的CA进行交叉认证的解决方案。     

基于OCSP协议的证书状态查询系统

证书状态查询是PKI系统中的一个关键问题,OCSP是解决这个问题的一种重要机制。本文分析并改进了OCSP协议,并在此基础上设计了一种高效的证书状态查询系统。文中对该系统的重要组成部分以及关键技术进行了详细的论述。     

Performance evaluation of priority CSMA-CA mechanism on ISA100.11a wireless network

The International Society of Automation recently released ISA100.11a as an open standard for reliable wireless networks for industrial automation. ISA100.11a uses the TDMA scheme in the medium access layer to provide deterministic services. However, ISA100.11a adopts the CSMA-CA mechanism with priorities for retransmission from failure on dedicated links, sporadic data, and network configuration.This paper evaluates ISA100.11a CSMA-CA by simulation, considering the effects of backoff procedures and priority settings to probability of collision and successful use of slots. It's demonstrated that a high number of priority classes enable better network utilization resulting in less number of packets exceeding their lifetime.     

Texture analysis of poly-adenylated mRNA staining following global brain ischemia and reperfusion

Texture analysis provides a means to quantify complex changes in microscope images. We previously showed that cytoplasmic poly-adenylated mRNAs form mRNA granules in post-ischemic neurons and that these granules correlated with protein synthesis inhibition and hence cell death. Here we utilized the texture analysis software MaZda to quantify mRNA granules in photomicrographs of the pyramidal cell layer of rat hippocampal region CA3 around 1 h of reperfusion after 10 min of normothermic global cerebral ischemia. At 1 h reperfusion, we observed variations in the texture of mRNA granules amongst samples that were readily quantified by texture analysis. Individual sample variation was consistent with the interpretation that animal-to-animal variations in mRNA granules reflected the time-course of mRNA granule formation. We also used texture analysis to quantify the effect of cycloheximide, given either before or after brain ischemia, on mRNA granules. If administered before ischemia, cycloheximide inhibited mRNA granule formation, but if administered after ischemia did not prevent mRNA granulation, indicating mRNA granule formation is dependent on dissociation of polysomes. We conclude that texture analysis is an effective means for quantifying the complex morphological changes induced in neurons by brain ischemia and reperfusion.     

基于Agent动态网络的疾病传播模型

提出一个基于Agent动态网络的疾病传播模型,研究疾病在人群中传播扩散的动态过程。在扩展疾病传播的SIR模型基础上,利用不同的个体状态描述各阶段病情。在二维规则网络上,通过增加个体自主移动性构建动态社会网络,并考虑个体异质性和所采取的防护措施对疾病传播的影响。仿真结果表明,该模型较好地反映了动态社会网络和个体适应性行为对疾病传播的影响,并与实际情况基本保持一致。     

基于中国剩余定理的入侵容忍CA方案

在介绍和分析了中国剩余定理和t-out-of-n秘密共享方案的基础上,提出了一个基于中国剩余定理的门限数字签名方案和一个基于离散对数的零知识证明方法.设计了一个具有入侵容忍功能的认证机构,并将中国剩余定理与RSA结合实现签字运算.此系统不仅有效地解决了私钥的秘密共享,而且减少了系统的计算量,提高了系统的运算效率.     

电子交易系统中文本安全传输方案的研究

为了提高电子交易系统中文本传输的可靠、快速、保密、安全性能，本文提出了一套基于SET协议、采用散列函数SHA计算消息摘要、将椭圆曲线公钥算法和AES私钥算法相结合，实现对电子文本加密、解密、签名及验证等功能的解决方案。文中阐述了从算法设计到方案实现的具体过程。     

EPICS控制系统中的Oracle数据库采集

介绍EPICS(Experimental physics and industrial control system)控制系统中针对Oracle的数据库采集。深入剖析了EPICS通讯协议、Oracle联网协议，详细介绍了采集软件的体系结构和实现方法，最后对EPICS稳定性做了测试。本文给出了采集程序对控制系统影响的测试结果和采集程序运行情况。