有线无线一体化通信系统在煤矿的应用

介绍了矿用行政通信系统、调度通信系统、无线通信系统,提出了煤矿有线无线一体化通信系统解决方案,并介绍了该系统的组成、主要设备及功能特点。应用结果表明,该系统实现了矿井有线无线通信系统的有效融合,达到了统一调度指挥的目的。     

基于LINUX的嵌入式Email系统的设计与实现

嵌入式Email系统是类PC嵌入式系统,是嵌入式操作系统及其应用软件的一个重要组成部分,但是现有PC上的嵌入式Email系统都不能适应类PC嵌入式系统的硬件环境要求。文中采用了一种新的构建嵌入式Email系统的方法,设计与实现了清华嵌入式Email系统,可根据各种类PC嵌入式系统的不同要求进行定制。首先,论述了类PC嵌入式系统的硬件平台对嵌入式Email系统的苛刻要求,其次,描述了清华嵌入式Email系统的体系结构,接着,讨论了清华嵌入式Email系统的实现机制与原理,以及系统模型,最后,给出了嵌入式Email系统的特点。由于采用了现在流行的一种开放源码的组件,使得整个系统功能完善,并能够完全符合类PC嵌入式系统的要求。嵌入式Email系统已经在自主研制的掌上电脑HPC和交互式网络电视上成功地运行。     

过程控制训练仿真评估方法研究

评估系统是过程控制型仿真系统的重要组成部分,随着过程控制型仿真系统复杂性增大,其评估系统构建也日趋复杂.该文从一般性的角度对过程控制型仿真系统评估方法进行了探讨,对训练仿真系统中的过程事件进行了分类.针对训练目的,提出了过程控制训练仿真系统的评估标准.结合训练仿真系统的特点,提出了评估的假设前提和事件类型判定方法.以此基础改进了分步评估法并构建了训练仿真系统的评估模型.最后,以海上补给训练仿真系统实际项目为背景,实现了海上补给训练仿真系统评估系统.     

浅析入侵防御系统

为了让人们将入侵防御系统与入侵检测系统区分开来,该文首先介绍了入侵防御系统的产生,然后对入侵防御系统与入侵检测系统进行了比较,同时详细分析了入侵防御系统的工作原理。最后,根据安全技术的发展趋势,预测了入侵防御系统的发展方向。     

智能家居系统安全性方案研究

随着物联网技术的良好发展,智能家居系统得到了日渐广泛的应用,为使用者提供了智能化的家居生活体验。但是,智能家居系统也存在一定的安全隐患,因此,有必要强化智能家居系统的安全性方案设计,增强智能家居系统的安全性。本文简述了智能家居系统的概念和架构,浅析了智能家居系统的安全性模型,探究了智能家居系统安全性方案设计,以期为智能家居系统安全性方案研究提供借鉴。     

基于内容的Pub/Sub系统中分发器网络自重构的研究*

提出了提高基于内容的Pub/Sub系统健壮性和交互效率的系统自重构方法。该方法包括系统的恢复策略和系统的自组织策略。系统的恢复策略,预防了节点的意外崩溃造成的系统瘫痪;系统自组织策略, 有效地降低了系统的事件交互成本,提高了基于内容的Pub/Sub系统的效率。自重构方法在基于内容的Pub/Sub系统SOES中得到了体现。     

分布式计算机实时监控系统

针对目前实时监控系统的不足,设计了分布式的计算机实时监控系统.系统的设计充分体现了分布式数据库的特点,信息共享性好;同时系统采用红外检测技术,提高了系统的实时性.实验证明,系统达到了预期效果.     

基于校园网的网上支付系统设计

主要论述了基于校园网的网上支付系统的系统框架,详细介绍了网上支付系统的功能模块,并简要分析了系统的技术特点。     

计算机多媒体辅助教学网站的开发

该文分析了基于ASP的Web远程考试系统的发展要求。分析了Web下考试系统的基本原理,结合系统需求,给出了系统架构。对于系统的数据库设计给出了详细的表,最后对关键代码进行了分析。     

一类非拓扑等价混沌系统的自适应同步控制

基于自适应控制策略和Lyapumov稳定性理论,对一类非拓扑等价的Lorenz系统,Chen系统和Lu系统的同步控制问题进行了研究。通过构造适当的控制函数和设计参数的自适应控制律,实现了Lorenz系统与Chen系统,Lorenz系统与Lu系统的大范围渐近稳定同步,导出了两混沌系统同步的充分条件;数值仿真表明了该方法的有效性。     

Changes in oculomotor functions before and after loading of a 3-D visually-guided task by using a head-mounted display

Changes in visual and oculomotor functions were tested in eight young volunteer subjects after performing a 3-D visually-guided task for 25min. The visual stimuli were given by using a head-mounted display. No significant change was detected in the AC/A ratio and the stereo-acuity. Changes were found in refraction and ocular convergence. Slight but significant hyperopic changes were detected in refraction after the task. The mean amplitude of convergence eye movement elicited by test Stimuli after the task was significantly changed in the pooled data. They were significantly reduced when the subjects were tested by the disparity step of 0.7°, but significantly increased when tested by the step of 6°. The mean amplitudes were not significantly changed after the task when the subjects were tested by the intermediate disparity steps of 1.5 and 3°. In data obtained for each subject, the amplitude of ocular convergence evoked by test stimuli after the task was reduced significantly in most subjects. In the majority of subjects, however, the results were not consistently significant when they were tested by step stimuli with different disparities. In only a few subjects, the changes were consistently significant except when the largest disparity was tested. On the other hand, the mean peak velocities of ocular convergence after the task were not significantly changed in the pooled data. In individual subjects, the changes of velocities of ocular convergence evoked by test stimuli after the task were more variable: they increased in some subjects but decreased in other subjects. Consequently, in only one subject, both amplitudes and peak velocities of ocular convergence tested by the-disparity steps of 0.7, 1.5 and 3° were consistently reduced after the task. The changes in refraction or ocular convergence found in this study were relatively small, and were not in the pathological range. The significance of these data are discussed. The results of the present study provide the basis for the more detailed analyses of the human factor in the head-mounted display.     

基于多结构元顺序形态变换的灰度图像边缘检测

在简要介绍顺序形态变换的基本概念及相关性质和对顺序形态变换进行边缘检测的原理进行阐述,以及对结构元素和百分位对边缘检测的影响进行讨论的基础上,根据图像形态学多刻度形态滤波的思想,从抑制噪声的角度对基本边缘检测算子进行推广和扩展,首先构造了3种边缘检测算子,并从理论上分析了算子的特性;然后将多结构元与图像边缘进行匹配,提出了3种广义顺序形态边缘检测算子并给出了一般表达形式;最后着重探讨了多结构元素及二重混合顺序形态变换百分位值p、q的选取原则.实验结果表明,该边缘检测算子在抑制噪声对图像边缘的影响和保持图像细节方面,优于传统的边缘检测算子和普通的形态边缘检测器.     

Learning medical alarms whilst performing other tasks

Two studies are reported which first observe, and then attempt to replicate, the cognitive demands of intensive care unit (ICU) activity whilst concurrently learning audible alarms. The first study, an observational study in an ICU ward, showed that the alarms are very frequent and co-occur with some activities more than others. The three most frequently observed activities observed in the ICU were drugs (calculation, preparation and administration), patient observation and talking. The cognitive demands of these activities were simulated in a second, laboratory-based experiment in which alarms were learned. The results showed that performance in the alarm task generally improved as participants were exposed to more repetitions of those alarms, but that performance decrements were observed in the secondary tasks, particularly when there were two or three of them. Some confusions between the alarms persisted to the end of the study despite prolonged exposure to the alarms, confusions which were likely caused by both acoustic and verbal labelling similarities.

Practitioner Summary: The cognitive demands of working in an ICU were observed and simulated whilst alarms were learned. Alarms should generally avoid sharing similar rhythmic (and other) characteristics. The simulation task described here could be used for testing alarm learning without requiring a clinical environment.     

免疫学原理在入侵检测中的应用研究

评述了近年来免疫原理在入侵检测中的应用,着重讨论抗体克隆选择学说、免疫网络学说和危险模式理论的应用研究现状,对所采用的免疫机制和算法进行了总结,并介绍了研究的热点问题。最后在分析入侵检测方法存在问题的基础上,探讨了今后研究的方向。     

甘肃景电灌区次生盐化土壤的性质及其发生机理

本文对甘肃景电灌区次生盐化土壤的理化性质进行了研究 .该区次生盐渍化土壤主要为硫酸盐氯化物和氯化物硫酸盐型 ,水溶性钠离子在阳离子中占绝对优势 .土壤通体碳酸钙含量很高 ,并有少量的石膏 .钠离子饱和度很高 ,具有钠质特性或钠质化现象 ,盐化与钠质化同时进行 .在此基础上对次生盐渍化的机理和改良进行了讨论     

贵州开阳地区土壤中硒的地球化学特征

以贵州开阳地区典型土壤为对象,研究了开阳地区土壤中硒元素的含量、分布及影响因素。结果表明,开阳地区土壤中硒的背景值高,其含量远高于全国土壤背景值;硒在土壤剖面上的分布存在空间差异,总体趋势是硒在表土层聚集;土壤中硒含量受土壤成土母质的控制。同时,表生地球化学作用、生物作用以及人类活动也深刻影响它们在土壤中的重新分配。     

Feature extraction by autoregressive spectral analysis using maximum likelihood estimation: internal carotid arterial Doppler signals

Abstract: In this study, Doppler signals recorded from the internal carotid artery (ICA) of 97 subjects were processed by personal computer using classical and model-based methods. Fast Fourier transform (classical method) and autoregressive (model-based method) methods were selected for processing the ICA Doppler signals. The parameters in the autoregressive method were found by using maximum likelihood estimation. The Doppler power spectra of the ICA Doppler signals were obtained by using these spectral analysis techniques. The variations in the shape of the Doppler spectra as a function of time were presented in the form of sonograms in order to obtain medical information. These Doppler spectra and sonograms were then used to compare the applied methods in terms of their frequency resolution and the effects in determination of stenosis and occlusion in the ICA. Reliable information on haemodynamic alterations in the ICA can be obtained by evaluation of these sonograms.     

The psychophysical lifting capacities of Chinese subjects

The psychophysical lifting capacity (MAWL) of twelve subjects was determined in this study. The subjects were all young Chinese males who performed lifting tasks in three lifting ranges (floor to knuckle, floor to shoulder, and knuckle to shoulder) and four lifting frequencies (one-time maximum, 1 lift/min, 4 lifts/min, and 6 lifts/min). The oxygen uptake (1/min) and heart rate (beats/min) were recorded while subjects were lifting. Upon completion of each lifting task, the subjects were required to rate their perceived exertion levels. The statistical analyses results indicated the following. Chinese subjects have smaller body size and MAWLs compared with past studies using the US population. The MAWLs decreased with an increase in lifting frequencies. The decrements of MAWL due to lifting frequencies were in agreement with the results of past studies. However, there were larger decreases due to lifting ranges. The MAWLs of the floor to knuckle height lift were the largest, followed by the MAWLs of the floor to shoulder height lift, and the MAWLs of the knuckle to shoulder height lift. The measured physiological responses were considered similar to those obtained in past studies. Subjects' perceived stress levels increased with the lifting frequency and the upper extremities received the most stress for the total range of lifting tasks. The comparisons of the Chinese MAWLs with the NIOSH lifting guidelines for limits (AL and MPL) indicated that the vertical discounting factor in the guidelines should be modified before the NIOSH limits can be applied to non-Western populations.     

Manual materials handling: a survey of risks,and the selection and training of workers in Singapore

A survey of 83 plants employing safety officers indicated that in 66% of them, workers were involved in manual lifting. The average number of manual lifting tasks was three per plant. Only about 6% of the total workforce were involved in manual lifting. Using the NIOSH Lifting Guidelines, the survey revealed that 30% of the lifting tasks were above the Maximum Permissible Limit, 50% were between the Maximum Permissible Limit and the Action Level, and only 20% were below the Action Level. A majority of the plants used a self-selection method to match a worker to the physical demands of a given manual lifting task. Training of workers in manual materials handling was provided by 76% of the plants. The principal methods of training included a poster campaign and demonstration of lifting techniques. The basic handling skills were taught in 90% of the plants. The content of training was incomplete, however, and further improvement was necessary.     

两种简化规则的模糊控制系统的分析比较

该文采用两种简化控制规则的方法设计了模糊控制系统,一种为双闭环模糊控制的方法,另一种为分离变量的模糊控制方法。通过一级倒立摆的仿真实验,该文给出了两种控制系统的控制曲线,说明了两种方案的有效性和良好的控制性能,同时对两种控制系统从设计思想、系统结构、控制性能等方面作了分析比较,指出了其在设计思想上的相似和不同之处,分析了两种控制系统产生相应控制效果的原因,并分别指出了两种方法各自的优势和局限性。