某矿区防雷改造措施分析

针对某矿区220kV线路根据雷电分布图采取的差异性防雷措施效果不理想的问题,分析了风速对线路绕击性能的影响;并结合风速风向和雷电分布图,对该矿区采取以下防雷改造措施:在与风向垂直的线路区的背风侧安装线路避雷器防绕击;对属于危险区域且线路与季风垂直的区域,采用防低接地电阻和安装线路避雷器防反击和绕击;对属于危险区域但受季风影响不是很大的区域,降低杆塔接地电阻防反击。实际运行效果表明,采取防雷改造措施后该矿区线路取得了较好的防雷效果。     

Complexity of families of learning algorithms and estimation of the nonrandomness of extraction of empirical regularities

The paper presents a general approach to the evaluation of the complexity of classes of algorithms, so-called pVCD-method. To develop this method, all the examined families of models of empiric generalization were restricted to classes implementable on computers and, wider, by examining their partially recursive representations. Within the framework of the algorithmic approach, the concept of Kolmogorov’ complexity of algorithms for the recognition of properties or the extraction of regularities is proposed. The method proposed to evaluate the nonrandomness of the extraction of empirical regularities is based on this concept.     

Shared domains of competence of approximate learning models using measures of separability of classes

In this work we jointly analyze the performance of three classic Artificial Neural Network models and one Support Vector Machine with respect to a series of data complexity measures known as measures of separability of classes. In particular, we consider a Radial Basis Function Network, a Multi-Layer Perceptron, a Learning Vector Quantization, while the Sequential Minimal Optimization method is used to model the Support Vector Machine.We consider five measures of separability of classes over a wide range of data sets built from real data which have proved to be very discriminative when analyzing the performance of classifiers. We find that two of them allow us to extract common behavior patterns for the four learning methods due to their related nature. We obtain rules using these two metrics that describe both good or bad performance of the Artificial Neural Networks and the Support Vector Machine.With the obtained rules, we characterize the performance of the methods from the data set complexity metrics and therefore their common domains of competence are established. Using these domains of competence the shared good and bad capabilities of these four models can be used to know if the approximative models will perform well or poorly or if a more complex configuration of the model is needed for a given problem in advance.     

Characterization of robust stability of a class of interconnected systems

We consider robust stability analysis of a class of large scale interconnected systems. The individual subsystems may be different but they are assumed to share a property that characterizes a set of interconnection matrices which lead to stable overall systems. The main contribution of the paper is to show that, for the case where the network interconnection matrix is normal, (robust) stability verification can be simplified to a low complexity problem of checking whether the frequency response of the individual subsystems and the eigenvalues of the interconnection matrix can be mutually separated using a class of quadratic forms. Most interestingly, it is shown that this criterion is also necessary, in the sense that if the criterion is violated, an interconnection matrix of the same eigenvalue distribution can be found to make the overall system unstable.     

接入网网管系统112测试的设计

根据目前接入网网管系统112测试的现状，文中在已有的网管系统上设计了112测试模块。作为112测试中心与特定接入网设备的中介，该模块与112测试中心以112协议相沟通，接受从112测试中心发送过来的测试命令并将测试结果反馈给112测试中心；同时，与特定接入网设备以SNMP协议相沟通，根据112测试命令向该设备发送测试请求，并接受从设备反馈的测试结果。针对该设计方案，文中在WIN2000平台上，以Visual C 60作为开发工具，基于WIN SDK的方法，讨论了模块具体实现。     

提高可编程序控制器可靠性措施分析

可编程序控制器的稳定性高于一般的控制系统,但若使用不当,可编程序控制器控制系统的稳定性就会受到影响.详细介绍了如何提高可编程序控制器控制系统的抗干扰性能,使用、安装、调试可编程序控制器控制系统应注意的事项及采取的措施.     

Methods of Estimating the Envelope of Elastic Oscillations of the Flexible Spacecraft

A problem concerned with studying of dynamics of angular motion of large space structures and flexible spacecraft was considered. It stems from the need to take into account multiple elastic modes when analyzing and designing their control systems. It was proposed to seek a solution to this problem, which is especially noticeable when modeling processes with high-frequency oscillations, on the way to replacing the precise solution of the equations of these motions by an approximate solution, that is, to determine a relatively low-frequency envelope of the precise solution, which allows one to extend the step of integration and, therefore, reduce the time of modeling. Two approaches to estimating the envelop were proposed, and their efficiencies were compared by the example of modeling angular stabilization of the flexible satellite with five elastic modes.     

多总线的采煤机齿轮箱试验台监控系统设计

针对采煤机齿轮箱试验台的分布和数据传输的要求,设计了一种多总线的采煤机齿轮箱试验台监控系统,详细介绍了该系统的拓扑结构和通信的实现。基于各种通信协议的特点,该系统采用Modbus,Profibus-DP,TCP/IP总线方式实时采集现场数据并传输到主控制器,实现了数据的远程监控;基于组态软件WinCC开发出系统的通信状态监测界面,实现了通信状态的实时在线监测,方便工作人员及时了解整个系统的通信状态。     

Comparison of simulation models in terms of quantity and allocation of land change

Our article illustrates how to compare the outputs from models that simulate transitions among categories through time. We illustrate the concepts by comparing two land change models: Land Change Modeler and Cellular Automata Markov. We show how the modeling options influence the quantity and allocation of simulated transitions, and how to compare output maps from pairs of model runs with respect to a reference map of transitions during the validation interval. We recommend that the first step is to assess the quantity of each transition and to determine the cause of the variation in quantity among model runs. The second step is to assess the allocation of transitions and to determine the cause of the variation in allocation among model runs. The separation of quantity and allocation of the transitions is a helpful approach to communicate how models work and to describe pattern validation.     

工矿供电系统谐波治理新方法研究

针对现有无源滤波器滤波效果较差,易出现谐振过电压、谐波放大等现象的问题,提出一种基于基波谐振原理的谐波治理新方法。该方法在电网与无源滤波器之间的三相线路中分别串联一组由电感和电容组成的基波谐振电路,迫使谐波电流最大限度地流入无源滤波器,从而大幅提升滤波器的效率。实验结果表明,增加基波谐振电路后,电流畸变率从10.6%下降为0.942%,滤波效果更佳。     

Conversion of units of measurement

Algorithms are presented for converting units of measurement from a given form to a desired form. The algorithms are fast, are able to convert any combination of units to any equivalent combination, and perform dimensional analysis to ensure that the conversion is legitimate. Algorithms are also presented for simplification of symbolic combinations of units. Application of these techniques to perform automatic unit conversion and unit checking in a programming language is described     

对目标电磁特性进行计算的几何模型探讨

在对目标电磁特性进行计算时，需建立计算目标的几何模型，并按精度要求在计算机中存储。显示和处理。在与用户进行人机交互的情况下，按照用户提出的精度、效率和产生数据量的具体要求，计算并输出对目标模型的四边形表面剖分数据。本文主要论述建立计算目标的几何模型需解决的主要问题和常用方法。     

政府机关网络中信息推送的应用研究

在政府机关网络中，公务员希望按照行政管理事务性质订阅具有类型化、个性化的信息，并定点定时地推送他他们的桌面上。为此，运用CORBA的事件服务和通知服务，研究了信息推送的技术框架，在此框架上提出了一个适合政府机关网络中信息推送的实施方案。     

基于窗口按钮的用户权限管理

比较现有MIS中常见的权限管理解决方法，提出了一种新颖的数据库设计方案，记录用户对其授权菜单对应窗口的权限值，并设计了以窗口中按钮的操作权限为目标，给用户分配权限的系统管理模块，成功地解决了细化到窗口按钮的用户权限管理问题。     

两种程控数字交换机割接的实现方法

为优化网络资源配置,提高设备实占率,要求非主流机型NEAX61∑程控交换机退网,并介绍了由NEAX61∑割接至主流机型S1240程控交换机的实现方法。     

数据库的规范化理论与非规范化设计

关系数据库设计的目标就是要得到一组关系模式来组成一个最优的数据库模式,使得我们既不必存储不必要的重复数据,又可以方便地查询数据。这组关系模式首先要用关系规范化理论规范化,构造好的逻辑结构,然后根据需要,从提高数据库性能的角度,进行非规范化处理。规范化和非规范化各有其优缺点,需要我们根据实际需求权衡处理。     

遗传规划算法在化合物设计、筛选研究中的应用

采用计算机科学中新兴的遗传规划算法思想，结合化学物质的本质特点，运用进化操作来实现化合物的合成设计和筛选。文中针对算法运用讨论了函数集、终止集问题，通过计算元素组成的字符串的化合价的结果来确定适应度函数，既符合化学学科的本质规律，又满足了算法的要求。通过复制、交换和突变操作，经过多代次的进化终止，取得了满意的结果。文章还针对其实用性，从化学本质出发，提出了建议和研究方向。可以说本文是遗传规划在化学化合物合成筛选中运用的成功探索，同时也为进一步研究打下了坚实的基础。     

Comparison of different methods of load carriage

There are many different ways in which loads may be carried, and the mode of load carriage adopted can be determined by factors such as weight, shape and size of the load, the duration for which it has to be carried, the terrain, climate and the physical characteristics and condition of the individual and the clothing he wears as well as his personal preference. It is generally more expensive in terms of energy cost to carry loads on the head, in the hands or arms, or attached to the legs, than to carry the load closely attached to the trunk as when using a backpack. A combined front-and backpack, or carriage of loads around the waist, tend to incur the lowest energy cost for a given load, as lateral and anteroposterior stability is optimized. However, there may be chest restriction and a limitation to evaporate body cooling, and donning and doffing problems may mitigate against the adoption of this method. Hand or arm carriage usually leads to local muscle fatigue rather quickly. Despite this, for convenience, over short distances or for intermittent load carriage, people will often choose to carry loads in their arms or hands.

This paper describes six separate experiments that we have conducted in our laboratory. In general, they show that there is seldom a single ‘best’ way to carry a load, and it is often difficult to clearly and objectively distinguish the physiological effects and the effects on the performance of the individual, of different methods of load carriage. We believe that it is wise to supplement objective physiological measurements with subjective opinion. However, it is important that the subjective data should be gathered as objectively as possible, by using appropriate experimental designs, carefully structured questionnaire techniques and standardized subjective rating methods. We have also found it profitable to conduct field studies to supplement our laboratory experiments. In general heavy loads should not be attached to small muscle groups, and optimum use should be made of the large muscle groups of the body in order to minimize fatigue and local muscular discomfort. There is a ‘knack’ to load carriage, and that ‘knack’ lies in the practical implementation of elementary principles.     

水下传感器网络节点定位信号检测的设计

针对水下环境的特殊性和水声定位系统的要求,为降低检测水声定位信号的复杂度和硬件资源消耗,能够准确检测定位基站发射的水声定位信号,为目标基站的定位提供实时、快速的时延信息,根据水声定位信号的特点,采用码元匹配检波和编码定位信号相关的方法,确定水声定位信号的到达时间,并以FPGA为平台利用VHDL语言对水声定位信号的检测设...     

Failure of the Routh-Hurwitz method of reduction

The Routh-Hurwitz reduction method is shown to have a serious disadvantage in that the reduced model may approximate the nondominant poles of the system and hence lead to erroneous approximations. A numerical example is given to compare the Routh-Hurwitz method to the Padé approximation method.