模拟电路故障诊断字典法的前向多层神经网络实现

讨论了一种利用ＢＰ算法的前向多层神经网络，建立并可快速查找电路故障字典的方法，该方法对单硬故障的识别与定位快捷而有效，同时利用了神经网络的联想功能和鲁棒性，有效地克服了容差因素对故障定位的影响。     

用支路撕裂法进行大规模模拟电路故障诊断的新算法

本文首先介绍最近出现的一种用支路撕裂法进行的大规模模拟电路的故障诊断算法,讨论了该算法的容差问题。然后将故障预测技术、替代理论和迭加定理运用到支路撕裂法中,得到一个新的故障诊断方程,并给出了一种新的算法。还讨论了算法的并行处理问题。研究结果证明,当连续监测网络时,新算法的在线计算时间和容差问题均较原算法有很大的改进。     

基于节点电压增量方程的含容差轨道电路软故障诊断

为了解决轨道电路容差的存在使得相关的故障诊断理论方法难以用于实际工程,分析了轨道电路的容差特性,提出了基于灵敏度分析的消除容差对故障诊断影响的方法,并在此基础上提出了基于节点电压增量方程的含容差轨道电路软故障字典法.该方法是对含容差线性模拟电路故障诊断方法的拓展,也适用于一般线性模拟电路.仿真验证结果表明,所提出的方法可以有效地实现含容差轨道电路的软故障诊断.     

基于差流检测的直流接地探测方法及装置研究

研究了直流系统接地故障探测方法及装置．直流系统支路发生接地故障产生接地漏电流,形成支路差流,采用自激振荡式直流微电流传感器(DCTA-1)离线测量直流系统各支路的差流,判别接地故障,从而提出一种直流系统接地故障的探测方法,称为"差流法"．实验结果表明,在使用DCTA-1传感器的条件下,该方法能迅速准确地定位接地故障,简单实用,灵敏度高．     

广义反投影定位K故障

提出容差模拟电路故障诊断的新方法一广义反投影法．它的故障定位准确率与当今最精良的定位法（非线性最小二乘法）相当．而在线计算时间仅是非线性最小二乘法的１／20     

电路故障诊断的支路代替法和模糊聚类法

本文提出了一种利用非口器和零口器进行模拟电路故障诊断的新方法,不受拓扑条件限制,不需要求解方程。同时讨论了存在容差时故障支路的分类问题,并提出了一种新的分类方法——模糊聚类法,克服了传统方法的漏判和误判现象,使算法更加可靠。     

可诊断非线性电路直流故障的神经网络方法

测后诊断速度和诊断精度是模拟电路故障诊断性能的主要衡量指标。文中将神经网络的自学习和分类技术应用于非线性电路直流故障诊断，把反向传播（ＢＰ）网络训练成一部能诊断软、硬单故障的故障字典。考虑元件参数容差对诊断的影响，提出了优选训练样本的具体方法。此外，重新定义了ＢＰ网络的输出误差函数，使网络在训练时有较大的自由度。ＢＰ网络高度并行的信息处理能力决定了这种新型故障字典的诊断速度非常快。仿真实验结果表明，神经网络方法的综合性能要优于传统的故障字典法。     

用模糊数学方法进一步研究模拟电路故障诊断中的容差问题

本文以探索模拟电子线路的实际故障诊断为目标,对故障定位中的容差效应作了进一步的研究,得到些有益的结果。首先,本文论述了故障定位法的一般形式,在非标称电路(即元件存在容差、测试存在误差的实际电路)的故障定位中提出了更合理的统计判定指数。然后用模糊数学的方法对模糊节点进行综合评判。根据故障度较客观地查出因容差效应而漏判的故障节点。并且上述方法在计算机上进行过模拟验证,诊断效果良好。     

用模糊集观点诊断模拟电路的故障

本文运用模糊集的概念,探求容差电路故障定位的方法,提出了有关故障节点定位的电压判据和电流判据,并建立了相应的隶属关系。可以将故障定位于只含故障节点集的子电路上。     

采用BP网络建立模拟电路故障诊断交流字典方法

介绍了两种采用BP网络实现模拟电路交流故障字典的方法，主要目的是提供一种简单的机制，能够对模拟电路进行智能诊断。合理大小的ANN能够实现对受容差影响的模拟电路故障的智能诊断。用白噪音法介绍了优选样本的具体方法和如何产生白噪音。此外，还简略介绍了多频测试法。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。