FPGA中网络通信协议栈的裁剪及其全硬件实现

针对基于FPGA的嵌入式系统中软件网络协议栈需要内置CPU的不足,阐述了采用全硬件方式实现网络协议栈的必要性,并提出了适合的网络通信协议栈裁剪方案.该协议栈包含精简的UDP、IP、以及MAC层驱动,可完成常规的网络通信.协议栈完全采用硬件描述语言编写,并在FPGA中实现.实验结果表明,该协议栈只占用2K逻辑资源,能以100Mbps的速率在FPGA与PC之间进行数据传输,为基于FPGA的系统调试及运行提供了一种简易的高速通信手段.     

KNXnet/IP协议安全性分析与改进

KNXnet/IP协议作为欧洲安装总线(EIB)协议的扩展应用,提高了EIB系统的传输速率并满足了智能管理的需求,但分析表明以IP网络作为骨干网的KNXnet/IP协议在安全性要求较高的应用领域内面临严重的威胁。在分析现有IP网络安全机制及嵌入式系统特点的基础上,提出适用于EIB系统的安全加密通信协议,该安全协议以非对称加密算法为基础,使用自定义的密钥交换协议管理密钥集,设备之间使用对称加密算法通信,具有对原协议架构改动较小、提供数据透明传输的特点,协议的原型实现证明了其可行性和安全性。     

基于TCP/IP协议的串口网关实时性的建模与分析

在传统串口设备通过标准TCP/IP协议接入Internet的过程中,需要设计一种基于工业以太网的串口数据通讯和控制系统,其数据通讯的实时性是衡量控制系统的一个重要指标.因此,为了分析串行数据通信系统的实时性能,建立了串口数据包传送时间延迟的数学模型,并以ARM9系列的AT91ARM9200微处理器和LXT971ALE网络接口芯片等为基础构建嵌入式系统,移植Linux,并在RH Linux 9.0为ARM处理器提供的交叉开发工具的平台下,以实测数据试验误差验证了该模型的准确性和普遍性,从而为开发人员对各种串口设备的参数设置提供理论指导.     

基于广播式以太网的IP语音系统性能分析

本文简单介绍了基于IP的语音系统(VoIP)的工作原理、网络结构及其应用前景．重点分析了基于IP的语音系统(VoIP)在网络性能方面的特性、通过建立数学模型，用非常具体详尽的数据说明了基于广播式以太网的VoIP系统的网络分布特性和带宽利用率等性能指标以及各指标之间的关系，论证了该系统的可行性。     

基于TCP/IP协议的嵌入式多串口网关的设计

以 ARM9系列的 AT91ARM9200 微处理器和LXT971ALE网络接口芯片等构建嵌入式系统,移植 Linux,并在 RH Linux9.0 为 ARM 处理器提供的交叉开发工具下,完成基于 TCP/IP 协议的多串口网关的设计.该设备支持服务器和客户机模式,为传统串口设备通过标准 TCP/IP 协议接入 Internet 提供了一种低成本解决方案.     

Effects of measurement errors on psychometric measurements in ergonomics studies: Implications for correlations,ANOVA, linear regression,factor analysis,and linear discriminant analysis

This paper aims to demonstrate the effects of measurement errors on psychometric measurements in ergonomics studies. A variety of sources can cause random measurement errors in ergonomics studies and these errors can distort virtually every statistic computed and lead investigators to erroneous conclusions. The effects of measurement errors on five most widely used statistical analysis tools have been discussed and illustrated: correlation; ANOVA; linear regression; factor analysis; linear discriminant analysis. It has been shown that measurement errors can greatly attenuate correlations between variables, reduce statistical power of ANOVA, distort (overestimate, underestimate or even change the sign of) regression coefficients, underrate the explanation contributions of the most important factors in factor analysis and depreciate the significance of discriminant function and discrimination abilities of individual variables in discrimination analysis. The discussions will be restricted to subjective scales and survey methods and their reliability estimates. Other methods applied in ergonomics research, such as physical and electrophysiological measurements and chemical and biomedical analysis methods, also have issues of measurement errors, but they are beyond the scope of this paper. As there has been increasing interest in the development and testing of theories in ergonomics research, it has become very important for ergonomics researchers to understand the effects of measurement errors on their experiment results, which the authors believe is very critical to research progress in theory development and cumulative knowledge in the ergonomics field.     

Macroergonomics and patient safety: The impact of levels on theory, measurement, analysis and intervention in patient safety research

The study and practice of patient safety has seen a surge over the last 10 years. New resident training and staffing policies, health information technologies, error reporting systems, team models of care, training methods, patient involvement, information handoff strategies, just cultures, and many other interventions have been mandated or attempted to improve the safety of patient care. While some of these interventions focus on individual providers and others focus on organization-level changes, little, if any, patient safety research has purposefully sought to understand how variables at different levels, such as the provider level or organization level, interact to impact patient safety outcomes such as errors, adverse drug events, or patient harm. Looking at relationships across levels is important because adverse events might be related to variables at different levels; consider that adverse events may be nested within patients, patients nested within nurses and physicians, nurses and physicians nested within shifts, shifts nested within hospital units, and so forth. Because these nested levels exist, they may exert as yet untested influence on the levels below. In this paper the impact of levels on theory, measurement, analysis and intervention in patient safety research is discussed.     

Influence of polling technologies on student engagement: An analysis of student motivation,academic performance,and brainwave data

This study compared clicker technology against mobile polling and the Just-in-Time Teaching (JiTT) strategy to investigate how these methods may differently affect students' anxiety, self-efficacy, engagement, academic performance, and attention and relaxation as indicated by brainwave activity. The study utilized a quasi-experimental research design. To assess the differences between the effects of clickers and mobile polling, the study collected data from two courses at a large research university in Taiwan in which 69 students used either clickers or mobile polling. The results showed that mobile polling along with the JiTT strategy and in-class polls reduce graduate students' anxiety, improve student outcomes in an environment comprising both graduate and undergraduate students, and increase students' attention during polling. However, brainwave data revealed that during the polling activities, students' attention in the clicker and mobile polling groups respectively increased and decreased. Students nowadays do not find smartphones a novelty; however, incorporating them into class is still a potentially effective way to increase student attention and provide a direct way for instructors to observe the learning effects of lectures and improve their teaching approach on that basis.