产品外形协同设计系统的研究与实现*

提出了协同设计工作模式,给出了系统的工作流程,定义了用户的权限分配,研究了基于交互日志的传输方式,讨论了协同设计过程中的实时更新机制.最后采用了基于MVC的体系结构构建了一个原型系统,该系统在实际应用中,验证了该技术思路的正确性.     

面向智能电网的云计算技术研究

对面向智能电网的云计算技术进行了研究。首先,引入了云计算的基本概念,分析了它的关键特征。其次,将云计算和智能电网技术进行了融合,提出了智能云的概念。随后,深入研究了智能云的构建、资源管理和安全策略问题。最后,给出了结论和未来的研究工作。     

基于电磁感应的矿井探测方法研究及仿真

本文首先分析了矿井探测中遇到的信号干扰种类,结合噪声信号的特点,提出了基于电磁感应的矿井探测方法,给出了其原理图和设计原则.然后详细论述了电磁感应探测方法的具体实现,给出了各主要测试参数的计算公式,明确了在探测过程中需要采集的各种信号.为了验证提出的电磁感应探测方法,最后采用了MATLAB建立了仿真测试模型,并给出了仿真测试结果.     

数据交换在数字化校园中的作用与实现

本文首先概要介绍了数据交换的基础概念和现状,分析了现有的数据交换技术,研究了主要的数据交换机制,对数据映射、工作流技术进行了探讨,重点介绍了数据交换的技术。在理论研究的基础上,设计了一个基于标准XML数据格式和XSLT数据映射格式,结合工作流引擎的数据交换系统模型。该系统模型解决了校园网多个异构系统的数据集成和业务集成的问题,充分考虑了系统的安全性和扩展性,为校同网的信息化建设提供了很好的参考模型。     

发挥多媒体技术的优势,营造轻松的学习氛围

小学语文教学应用于多媒体技术,实现二者的整合,营造了宽松的学习环境,突出了学生的主体地位,激发了学生的创新意识。多媒体技术的应用为小学语文教学改革带来了机遇与挑战,为学生提供了全面的感性材料,活跃了教学气氛,激发了学习欲望。多媒体技术与小学语文教学有机结合,形成了一种全新的学习方式。本文试就发挥多媒体技术的优势,营造轻松的学习氛围进行了阐述。     

智能家居及其发展趋势

介绍了智能家居的发展历程,阐述了智能家居的定义和功能,介绍了其关键技术和嵌入式在智能家居中的应用,预测了其发展趋势,阐明了研究智能家居的重要意义,并指出了智能家居在控制系统、智能建筑系统和计算机领域的广泛运用,将使电子科学和计算机科学等科学中产生革命性的变革.     

基于LabVIEW的光纤惯组自动测试软件的设计与实现

针对传统惯组测试设备测试效率低、可扩展性差的缺点,基于LabVIEW设计开发了光纤惯组自动测试软件.针对软件实现的关键技术进行了研究,主要包括利用插件式的程序架构,设计了低耦合高内聚的测试模块,增强了软件的扩展性和可维护性;设计了详实的配置文件,实现了测试流程的自动化;同时利用多线程和定时循环的软件机制满足了高速数据采集的要求.实际应用证明,该软件提高了测试效率,促进了自动测试设备领域的新发展.     

天下视频Flash 制作下载转换通

宽带流行了,播客兴起了,FLV吃香了,菜鸟也坐不住了,迅即抱回了DV,开通了播客。历经N天修炼,Flash视频终于成为菜鸟的拿手好菜之一。播客的兴起,使得Flash视频(FLV)格式大行其道。究其原因,不外乎FLV视频避免了不安装特定视频插件就     

仿真技术在包装机械研制中的应用

该文阐述了传统的新产品的开发过程和利用计算机仿真技术开发新产品的过程,总结了这两种开发过程的特点,给出了系统仿真的一般步骤.介绍了计算机仿真技术及其在包装机械研制中的两个实际生产的例子,并总结了利用计算机仿真技术开发新产品的特点,它加快了新产品的研制和开发过程,提高了劳动生产率,降低了生产成本,保证了交货日期,提高了产品质量.因此,计算机仿真技术在包装机械研制领域将会得到越来越广泛的应用.     

基于uClinux嵌入式远程环境在线监测系统的开发

该文分析了现有主要环境在线监测系统存在的问题,进行了嵌入式远程环境在线监测系统的总体设计,探讨了基于uClinux的嵌入式环境监测点系统的关键技术,给出了相应的实现过程,提出了基本的解决方案。     

A method of defuzzification based on the approach of areas' ratio

The new method of defuzzification of output parameters from the base of fuzzy rules for a Mamdani fuzzy controller is given in the paper. The peculiarity of the method is the usage of the universal equation for the area computation of the geometric shapes. During the realization of fuzzy inference linguistic terms, the structure changes from the triangular into a trapezoidal shape. That is why the universal equation is used. The method is limited and can be used only for the triangular and trapezoidal membership functions. Gaussian functions can also be used while modifying the proposed method. Traditional defuzzification models such as Middle of Maxima − MoM, First of Maxima − FoM, Last of Maxima − LoM, First of Suppport − FoS, Last of Support − LoS, Middle of Support − MoS, Center of Sums − CoS, Model of Height − MoH have a number of systematic errors: curse of dimensionality, partition of unity condition and absence of additivity. The above-mentioned methods can be seen as Center of Gravity − CoG, which has the same errors. These errors lead to the fact that accuracy of fuzzy systems decreases, because during the training root mean square error increases. One of the reasons that provokes the errors is that some of the activated fuzzy rules are excluded from the fuzzy inference. It is also possible to increase the accuracy of the fuzzy system through properties of continuity. The proposed method guarantees fulfilling of the property of continuity, as the intersection point of the adjustment linguistic terms equals 0.5 when a parametrized membership function is used. The causes of errors and a way to delete them are reviewed in the paper. The proposed method excludes errors which are inherent to the traditional and non- traditional models of defuzzification. Comparative analysis of the proposed method of defuzzification with traditional and non-traditional models shows its effectiveness.     

An approach to the synthesis of fuzzy stabilization systems with a priori unknown model of an object

A method of synthesis of fuzzy stabilization systems for a broad class of dynamic objects under the assumption that the mathematical model of the object is not known a priori is proposed. The control is formulated in the form of a proportional law of adjustment as a function of a macro-variable; the square of the Euclidean norm of the phase variables is adopted as the macro-variable. An analogous variable characterizes the distance of the object from the equilibrium position. Despite the simplicity of the control law, its sign remains constant due to the fact that the macro-variable is positive-definite over the entire phase space. The switching times of the signals are determined by fuzzy identification of the system’s dynamic modes on the basis of measurement of the derivatives of the macro-variable.     

Complement of Source Equation of Elastic Line

A new notion of joint, defined in terms of the state of motor (active or locked) and type of the elastic or rigid element, gear and/or link that follows after the motor, is introduced. Special attention is paid to the motion of the flexible links in the robotic configuration. The paper deals with the relationship between the equation of elastic line equilibrium, the “Euler–Bernoulli approach” (EBA), and equation of motion at the point of elastic line tip, the “Lumped-mass approach” (LMA). The Euler–Bernoulli equations (which have for a long time been used in the literature) should be expanded according to the requirements of the motion complexity of elastic robotic systems. The Euler–Bernoulli equation (based on the known laws of dynamics) should be supplemented with all the forces that are participating in the formation of the elasticity moment of the considered mode. This yields the difference in the structure of Euler–Bernoulli equations for each mode. The stiffness matrix is a full matrix. Mathematical model of the actuators also comprises coupling between elasticity forces. Particular integral of Daniel Bernoulli should be supplemented with the stationary character of elastic deformation of any point of the considered mode, caused by the present forces. General form of the elastic line is a direct outcome of the system motion dynamics, and cannot be described by one scalar equation but by three equations for position and three equations for orientation of every point on that elastic line. The choice of reference trajectory is analyzed. Simulation results are shown for a selected robotic example involving the simultaneous presence of elasticity of the gear and of the link (two modes), as well as the environment force dynamics.     

3 Laser transmission joining in microtechnology

The laser is a joining tool which is particularly suitable for the application in microtechnology. The process variant laser transmission joining can be used both for welding thermoplastics and bonding of silicon and glass. The investigations presented in this paper cover detailed examinations of both processes. Concerning laser transmission welding of plastics it is examined how far the content of carbon black in the material influences the formation of the weld seam. It is shown that the optical depth of penetration, the weld seam width as well as the formation of the weld morphology differ with varying content of carbon black. Selective laser radiation bonding (SLB) is a novel method for joining silicon and glass based on the transmission heating of the interface of both joining partners and the thermo-chemical principles of silicon direct bonding. SLB shows advantages in reference to the thermal load of sensitive components like sensors and to the selectivity of the joining geometry. In this study the principle method of SLB and the latest advances like the integration of the thermal process control in the laser processing head will be presented. Also experimental test results of the process with constant laser power and thermal process control and the comparison of them will be shown.An erratum to this article can be found at     

Remote sensing of spring phenology in boreal regions: A free of snow-effect method using NOAA-AVHRR and SPOT-VGT data (1982-2004)

Measurements of spring phenological dates in boreal regions using NDVI can be affected by snowmelt. This impacts the analysis of interannual variations in phenology and the estimates of annual carbon fluxes. For these two objectives, snowmelt effect must be removed from the phenological detection. We propose a methodology for determining the date of onset of greening in the 1982-2004 period using SPOT-VEGETATION (VGT) and NOAA Advanced Very High Resolution Radiometer (AVHRR) data. From 1998 onwards, the date of onset of greening is taken as the date at which the Normalized Difference Water Index (NDWI), calculated from SPOT-VGT near and short-wave infrared bands, starts increasing. This index decreases with snowmelt but increases with vegetation greening. For the 1982-2001 period, the date of onset of greening is the date at which AVHRR-NDVI equals a pixel specific threshold (PST), determined using the results of the NDWI method in the years common to the two datasets. The methods are validated using in situ measurements of the dates of leaf appearance. RMSE of 6.7 and 7.8 days, respectively, is found using NDWI-VGT and PST-NOAA methodologies, and the difference between the two methodologies in the common years is small. Very importantly, the dates are not biased. The interannual variations of the 23-year spring phenology dataset on the study area in northern Eurasia are analysed. In average over the study area, an advance of 8 days and a delay of 3.6 days are, respectively, found over the periods 1982-1991 and 1993-2004. These results confirm and complete previous studies about the greening trend, remove the uncertainty due to snow, and may improve carbon budget calculations.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).     

Spark平台下聚类算法的性能比较

通过实验,从运行时间、加速比、可扩展性和规模增长性4个方面比较了 Spark平台中3种典型的聚类算法即K-means聚类算法、二分K-means聚类算法和高斯混合聚类算法 的性能。实验结果表明:1)随着节点个数的增加,3种算法对百兆以上规模数据集聚类的运行时间明显减少;2)当数据集规模大于500MB时,3种算法的加速比均有明显提高,且随着节点个数的增加,加速比近似于线性增长;3)3种算法的可扩展性随着节点个数的增加而降低,当数据集规模大于500MB时,相对于K-means和高斯混合算法,二分K-means算法的可扩展性最差;4)当数据集规模大于100MB时,高斯混合算法的规模增长性远高于K-means和二分K-means算法。     

协作机器人的构型分析研究

针对协作机器人的构型分析研究,得出了偏置是影响机器人构型的一个重要因素。首先,对现有典型协作机器人的构型进行分析,通过构型间的内在联系与演化过程得到构型之间的差异。然后利用构型之间的差异引出了偏置的定义,并通过偏置对关节运动范围的影响将其分为S型偏置和Y型偏置。最后以全局性能指标、工作空间体积指标和灵活工作空间指标为性能评价标准,对iiwa、Sawyer、Yumi三种典型构型的性能进行了仿真。通过对比分析可知,偏置的存在使构型的全局性能和工作空间体积性能降低,但对灵活工作空间性能有提高作用。结果表明偏置是影响机器人性能的重要因素,该分析研究为协作机器人的构型设计提供了理论依据。     

Overview of ATM networks: functions and procedures

The purpose of this paper is to present an overview of the ATM technique. The basic principles of the ATM transfer technique, the B-ISDN layered protocol reference model, as well as the architecture and the main functions of the ATM network, are described in this tutorial. In particular, we present the main characteristics of the ATM technique, the structure of the ATM cell, the functions which deal with the protection from errored cells (HEC procedure) and the identification of the boundaries of the ATM cells (cell delineation and scrambling). The VP/VC concept is explained in detail, and the main principles and functions of the three lowest layers (Physical, ATM and Adaptation) of the B-ISDN layered protocol reference model are surveyed. The issue of Quality of Service parameters in ATM networks is reviewed, and the problem of the allocation of the network resources in response to user demands, as well as the problems of congestion control, Usage Parameter Control (UPC) and traffic modelling in ATM networks, are assessed. Finally, we present ‘possible’ sets of traffic characterization parameters, and show how possible B-ISDN sources can be modelled according to the basic on-off ATM traffic source model.