多普勒效应下星间光通信系统的仿真性能分析

构建卫星光通信系统的仿真模型,在不同信道传输环境下,对相干和非相干检测下的卫星光通信系统性能进行了分析比较.结果表明:在具有相同的轨道的星间光链路之间,由于相对速度恒定,不存在多普勒效应,采取相干检测下的系统误比特率要小于非相干检测下的系统误比特率;当卫星处于不同的轨道时,存在多普勒效应,相干检测下的系统误比特率要远远大于非相干检测下的系统误比特率;在现有的条件下,当存在多普勒效应时,宜采用非相干检测来进行检测解调.     

LTE系统下行链路中HARQ技术的研究与仿真

介绍了LTE系统中HARQ技术原理;以III型HARQ为研究对象,搭建了基于HARQ的LTE系统下行链路仿真平台,并对加入HARQ技术前后的LTE系统误块率进行了仿真比较。结果表明,HARQ技术不仅有效降低了LTE系统的误块率,而且使LTE系统在较低的信噪比情况下仍可获得与未采用HARQ技术时高信噪比情况相同甚至更好的通信质量,即能提高小区覆盖边缘用户和无线信道质量较差的用户的通信质量。     

Linux下基于MPEG4IP的实时授课同步技术和实现方法

从多媒体通信中的关键技术媒体同步技术入手,提出了一种以GNU Linux为运行平台的实时授课系统的同步技术和实现方法.该授课系统以MPEG4IP流媒体处理平台为基础,实现了教师授课视音频和授课屏幕数据三种媒体从采集、传输到回放的同步功能.围绕上述三个方面进行展开,重点阐述了同步的实现机制和开发技术.最后,总结了研究工作,并阐述了下一步的研究改进方向.     

基于免疫计算的IDS误警率问题研究

误警率较高是入侵检测系统（IDS）存在的一个主要问题,极大影响了检测结果的可信性。形式化分析了IDS可信问题与误报率的关系以及异常IDS误警率问题产生原因,借鉴生物免疫系统,提出了基于人工免疫思想,动态构建正常系统轮廓,抑制误警率的方法。给出了抗原、抗体的形式化描述及检测的具体过程,并进行了仿真和对比实验。理论分析和实验表明,该方法有效降低了IDS的误警率。     

可信云服务

云服务是一类依托于云计算平台的新兴网络服务,其外包服务模式以及云平台自身的安全风险引起了用户的信任问题.云服务可信与否成为用户业务向云迁移的最大顾虑.如何构建安全可信的云服务,成为近年来研究领域的热点之一.该文在分析云计算安全威胁的基础上,提出了可信云服务的定义,并从用户信任预期、安全威胁来源和技术针对的安全目标等角度对可信云服务研究技术的类型进行了划分;然后,系统地梳理了数据存储外包、计算外包、虚拟机外包等典型云服务的安全可信研究工作;最后,探讨了可信云服务的未来研究趋势.     

生物信息学和化学信息学网络研究平台的构建

生物信息学和化学信息学均需要利用计算机和网络作为其研究平台,从网络中获取数据,利用远程计算机完成计算分析任务;同时,生物信息学和化学信息学软件分布在Unix、Linux和Windows等不同的操作系统平台上。因此,对从事生物信息与化学信息学研究的工作者来说,拥有一个通用的跨系统的网络研究平台将会如虎添翼。本论文研究立足于山东省生物信息工程技术研究中心现有的网络硬件设备,通过网络架构的构建和软件设置建立了一个开放、方便、实用的网络研究平台。利用该平台,用户可以在指定网域内任意一台计算机上获取研究数据,提交计算、研究任务,也可以借助任意一台Windows或Linux PC工作站图形远程登录中心的UNIX／Linux／Windows服务器进行工作,实现校内的数据、计算、图形等资源的共享,节省了网络和计算资源,方便了研究工作的开展。     

基于海床特征地貌的水下导航方法研究

在简要分析现有自主导航方法的基础上,给出了一种基于海床特征地貌,实施水下匹配导航的快速准确算法.研究了基于小波与改进型SSDA相结合的快速匹配算法,并给出了从粗匹配到精匹配的实施过程.为消除误匹配问题的影响,提出了基于距离和方位约束的匹配方法,实现了误匹配的有效检测和修正.实际海上导航试验验证了上述方法的正确性.     

无线光PPM+PWM的性能分析

为了解决无线光通信中常用的调制方式开关键控(On-Off Keying,OOK)误比特率高,脉冲位置调制单位传信率低的问题,提出了一种新的调制方式--脉冲宽度位置调制技术.详细分析了 PPM+PWM调制技术的单位传信率和误比特率,用Matlab软件首次成功实现了调制方式的编译码,并在在相干和非相下技术检测下,对采用调制方式的系统进行了仿真.分析和仿真结果表明,PPM+PWM是一种单位传信率优于 PPM,误比特率小于OOK的调制技术.     

一种新型电力系统在线防误闭锁装置

电气误操作是威胁电力系统安全运行的责任事故,可能造成大面积停电、电气设备毁坏、系统振荡瓦解,甚至造成人身伤亡.现有的防误闭锁装置不能实现电气操作的在线防误闭锁,以及变电站之间操作的防误闭锁.基于这种情况提出了一种将RFID数字操作票和在线防误闭锁控制器相结合的新型电力系统在线防误闭锁装置,该装置能对电力系统操作起到很好...     

智能变电站继电保护运维防误技术研究及应用

在智能变电站继电保护过程中,传统运维防误技术存在及时率低的问题。通过计算智能变电站继电保护运行动态基线,设计智能变电站继电保护运行防误技术,管理智能变电站继电保护运维防误数据,以可视化的方式,完成智能变电站继电保护运维防误。实验结果表明,设计的运维防误技术,运维防误及时率明显高于对照组,能够解决传统技术及时率低的问题。     

基于操作流程图的人为差错辨识方法

提出操作流程图的概念,利用操作流程图来辨识人为差错。提供了操作流程图的3种基本模块,分析了如何建立操作流程图,给出利用操作流程图进行人为差错路径辨识算法,算法所得到的结果与事件树的结果是完全一致的。讨论了操作流程图针对事件树的优势及其发展趋势。     

Factors affecting accuracy in the quality control checking of fresh produce labels: A situational and laboratory‐based exploration

Manufacturing industries often rely on quality control staff to ensure mistakes are detected before products are shipped to customers. Undetected errors can result in large financial and environmental costs to packaging companies and supermarkets but the contributors to such error are underexplored. The research reported in this paper investigated human error in the quality control checking of information displayed on the labels which accompany packaged fresh produce. Initial work sought to understand the demands of label‐checking in the packhouse environment, through interviews with key quality control staff, in situ observations, and the study of historical error data held by a fresh produce packaging company. This study highlighted the dynamic and cognitively challenging environment in which label‐checking occurred, while the historical error data indicated both the scale of the packhouse's work and the infrequency of error occurring. In a separate strand of laboratory‐based research, experienced and novice label‐checkers were presented with a simulated label‐checking task and a battery of computerized and pen‐and‐paper tests. These tasks were administered to determine whether cognitive abilities could predict label‐checking accuracy in a controlled laboratory environment. Stronger abilities in two cognitive processes (information processing speed and inhibition) predicted greater overall accuracy and higher detection of labeling errors. In identifying potential contributors to human error in the quality control checking of product labels both in situ and in the laboratory, the results are relevant to manufacturing, wherever information is printed on labels, especially when labeling processes depend upon human data entry and human quality control checking.     

Situation awareness,human error,and organizational learning in sociotechnical systems

In many organizations, the performance of individuals and teams is negatively affected by human error. Studies have shown that these errors can be reduced or even prevented by learning from them and by developing an understanding of error causation and its consequences. The ability to detect, understand, and anticipate errors refers to situation awareness (SA). Although SA is not limited to human error and it is more closely linked with decision making, it is a prerequisite for error reduction in complex sociotechnical work settings. The main objectives of this study were threefold: First, a model that can explain the interrelations between human error, SA, and organizational learning in sociotechnical systems was developed. Secondly, functional and dysfunctional factors that affect human error, SA, and organizational learning were identified. Thirdly, a research methodology was selected and adapted to empirically test the model in a real‐world sociotechnical task environment. To do so, an SA performance test and a human error questionnaire were used to examine SA and respective learning modes of 108 assembly‐line workers in the manufacturing industry. The final test results supported the central assumptions of the applied model. The article concludes by discussing applications in the field of sociotechnical systems analysis, team training, human performance programs, and high‐reliability organizations.     

The validation of three human reliability quantification techniques - THERP, HEART and JHEDI: part 1 - technique descriptions and validation issues

This is the first of a set of three papers reviewing the validity of three Human Reliability Assessment (HRA) techniques used in the UK to predict human performance in high risk industries. The techniques are used to determine the risks inherent in such industries due to human error, and also the benefit in terms of risk reduction by having human operators in the system. These techniques culminate in a quantitative human error probability for each error or failure identified, predicting how often errors or failed performance will occur. The major question with such an approach is whether such probabilities are accurate. This key validation question is answered in the second paper, which reports the results of a large and independent validation experiment.

Once a technique achieves some degree of predictive validity, the next question becomes whether such a technique can consistently produce valid and accurate results. This is called the reliability of the technique, and is dependent upon its consistency of usage by different assessors. Consistency can only be analysed by investigating the detailed usage of the techniques, and such an analysis is reported in the third paper in this series. The advantage of such an analysis is that it can also lead to specification of practical guidance for practitioners, and may lead to derivation of ways to improve the reliability and consistency of usage of specific HRA techniques. This first paper introduces the three techniques themselves, and reviews the major validation criteria and issues which should be considered when trying to determine if such techniques work.     

Post-error expression of speed and force while performing a simple,monotonous task with a haptic pen

Control errors often occur in repetitive and monotonous tasks, such as manual assembly tasks. Much research has been done in the area of human error identification; however, most existing systems focus solely on the prediction of errors, not on increasing worker accuracy. The current study examines force responses before, during and after errors in a simulated assembly line task in order to determine an optimal feedback system for error reduction. Confirming previous findings, enhanced movement speed and reduced force occurred before erroneous trials and slowing occurred after erroneous trials. Given the results, we suggest a haptic feedback system which stimulates users to exert increased force levels after completing an erroneous task in order to increase degree of control and re-build worker confidence and thereby reduce overall error rate.     

Errors enacted during endoscopic surgery-a human reliability analysis

The aim of the study was to document the nature and incidence of surgical errors enacted during laparoscopic surgery in order to direct future research and surgical training. A modified Human Reliability Analysis (HRA) approach, based on direct observation, was adopted to categorise and record errors encountered during the practice of laparoscopic cholecystectomy. This study confirmed the applicability and usefulness of an observational methodology in the assessment of human error in endoscopic surgical performance. The study identified aspects of the design and usage of instruments, surgical training and the differences between tasks which needed further directed research in order to identify underlying performance shaping factors (PSFs) and so reduce error rates.     

Human errors and violations in computer and information security: the viewpoint of network administrators and security specialists

This paper describes human errors and violations of end users and network administration in computer and information security. This information is summarized in a conceptual framework for examining the human and organizational factors contributing to computer and information security. This framework includes human error taxonomies to describe the work conditions that contribute adversely to computer and information security, i.e. to security vulnerabilities and breaches. The issue of human error and violation in computer and information security was explored through a series of 16 interviews with network administrators and security specialists. The interviews were audio taped, transcribed, and analyzed by coding specific themes in a node structure. The result is an expanded framework that classifies types of human error and identifies specific human and organizational factors that contribute to computer and information security. Network administrators tended to view errors created by end users as more intentional than unintentional, while errors created by network administrators as more unintentional than intentional. Organizational factors, such as communication, security culture, policy, and organizational structure, were the most frequently cited factors associated with computer and information security.     

交替测量式掘进机定位系统误差建模与分析

交替测量式掘进机定位技术在多次交替测量过程中会产生累计测量误差,从而影响掘进机定位精度。目前主要围绕单次测量误差产生原因、误差分布规律及误差减小方法展开研究,未有针对多次交替测量误差分布规律的研究成果。通过分析交替测量式掘进机定位系统工作原理及定位过程,构建了掘进机定位误差模型。采用作图法验证误差模型的正确性,结果表明作图法与误差模型得到的定位误差基本一致,二者仅存在10^-3数量级误差。通过误差模型研究了角度测量误差、测距误差、推移步长及掘进机与测量平台间距对掘进机定位误差的影响,结果表明:角度测量误差越大,定位误差曲线的曲率越大,即误差增大越快,且Y_T轴定位误差增大速度远大于X_T轴;测距误差对X_T轴定位误差影响较大,测距误差越小,初始X_T轴定位误差越小,但误差变化速度不受影响;随着推移步长增大,Y_T轴定位误差曲线曲率增大,即Y_T轴定位误差增大速度加快;掘进机与测量平台间距和推移步长对掘进机定位误差的影响基本是等效的。采用正交试验方法分析了各因素对掘进机定位误差的影响程度,结果表明:测距误差对X_T轴定位误差影响最大,其次为角度测量误差,推移步长和掘进机与测量平台间距影响最小且二者影响程度一致;角度测量误差对Y_T轴定位误差影响最大,其次为推移步长和掘进机与测量平台间距且二者影响程度一致,测距误差影响最小。通过极差分析方法得到了降低定位误差的最优参数组合。     

一种以人为中心的风险评估算法

从人为差错的辨识、概率计算和后果量化三个方面讨论人因事件风险评估的流程,并针对这三个关键问题设计相关的解决方案。针对人为差错辨识问题,设计一种统一的人为差错基本分类框架,作为差错辨识过程的模板库;针对人为差错概率计算问题,提出首先计算人为差错总体概率,然后结合历史事故统计资料计算具体差错模式发生概率的新方法;针对后果量化问题,按照先定性后定量的原则,设计一种后果量化值的确定方法。     

基于云环境下的科研管理服务平台建设研究

以云环境下的科研管理服务平台建设为研究对象,通过云计算的体系架构搭建具有分布式存储、虚拟化应用的科研管理服务平台,平台用户包括管理员、科研管理服务工作者和科研人员三种用户,平台提供的功能主要包括用户管理、科研管理、科研服务管理、系统管理。服务平台利用HDFS分布式文件系统功能对海量的数据进行处理,通过实践的应用证明了该平台对科研课题的申报和科研统计具有很好的服务能力,极大的提高科研管理服务的效率,推动科研项目成果的转化规范化发展。