GIS中矢量图形的结构分析与VC++中的实现

简要讨论了GIS各类矢量图形元素间的空间拓朴结构及基位置关系 ,并用VC 6 . 0及MFC具体分析了圆弧与多边形区域的相交关系及实现。为利用VC开发专用图形软件提供了有用帮助。     

光纤综合业务局域网

本文扼要地介绍了把光通信技术和计算机技术组合应用,以光纤为传输介质,组成一个以一根光纤同时传输图象信息、话音信息、文字真迹信息和数据信息等不同业务的综合业务局域网。并叙述了网络的拓扑形式、功能、用途及光端机的构成,计算机的作用等。     

基于PON网络的自助装维支撑系统的研究与开发

本文介绍如何让装维人员能够非常直观、简单地通过手机自助查找PON网络装维过程中的问题,很好地落实国家＂宽带中国＂、＂光网城市＂战略,让装维人员利用3G移动互联网技术解决FTTx装维过程中的问题就是我们研究的课题。     

MST-based topology control with NLOS location error compensation for location-aware networks

The topology control algorithms can improve the network capacity and network lifetime in location-aware networks. The topology control algorithms require accurate locations of mobile nodes or distances between each of the mobile nodes. The IEEE 802.15.4a-based location-aware networks can provide precise ranging distance between two mobile nodes. The mobile nodes can obtain their accurate locations by using accurate ranging distances. However, in the IEEE 802.15.4a networks, the ranging distance has a large measurement error in non-line-of-sight (NLOS) conditions. In this paper, we propose MST-based topology control with NLOS location error compensation algorithm to improve location accuracy and prevent mobile nodes from connecting to unstable links in NLOS condition. Performance evaluation shows the proposed algorithm constructs a topology map which has low location errors with considering the instability of NLOS links in NLOS condition.     

基于ZBrush的真人头部模型的设计与实现

Zbrush是一款数字雕刻和绘画软件,能够让制作者无约束自由创作,其拥有强大的建模功能,能够创建出非常精细的模型以及生成合理的纹理贴图、置换贴图、法线贴图与其他三维软件相结合,Zbrush已广泛应用于电影特效、游戏、广告等行业中。本文介绍了基于Zbrush的真人头部模型的设计与实现从"高模的制作"—>"模型的拓扑"—>"UV编辑"—>"绘制贴图"基本流程以及制作中的要领,带初学者进入神奇的三维雕刻世界。     

A novel Topology Aggregation approach for shared protection in multi-domain networks

Routing for shared protection in multi-domain networks is more difficult than that in single-domain networks because of the scalability requirements. We propose a novel approach for shared protection routing in multi-domain networks where the key feature is a special Topology Aggregation. In this Topology Aggregation, only some potential intra-domain paths (intra-paths for short) are selected for carrying working and backup traffic between domain border nodes. The abstraction of each intra-path to a virtual edge makes the original multi-domain network to become an aggregated network. On the aggregated network, a single-domain routing algorithm for shared protection can be applied for obtaining the complete routing solutions. The experiments show that the proposed approach is scalable. Moreover it is close to the optimal solution in single-domain networks and outperforms the previously proposed scalable solutions in multi-domain networks.     

三相电压源型逆变器故障容错综述

在诸如航空航天、机车牵引、核工业、石油化工等领域,电力电子装置已成为控制过程中的关键设备。一旦电力电子装置出现故降,整个系统便丧失了正常工作的能力,尤其在航空、军事等重要场合,将会造成灾难性的事故。本文主要介绍了三相两电平电压源型逆变器功率开关器件故降容错拓扑结构,着重探讨了三相四开关逆变器控制方案,为故障容错方面的研究工作提供一个初步的指南。     

Using databases in history teaching

Abstract In recent years, considerable interest has been shown in the classroom use of historical databases. Several database programs for microcomputers have become available, and as far as history teaching is concerned, they appear to have been mainly used for the analysis of mid-nineteenth century census schedules. At the same time, it is not clear that the curricular issues concerning the use of these programs has been fully explored. The purpose of this article is to raise these issues and to relate them to the use of several database programs currently used in classroom history teaching.     

An approach of topology optimization of multi-rigid-body mechanism

Topology synthesis of multi-rigid-body mechanisms has always been a very important stage in the mechanism design process. In most cases, the topology of the multi-rigid-body mechanism for particular task is obtained by designers’ experience and ingenuity, rather than automatic approach. In this work, an approach of topology optimization of multi-rigid-body mechanisms is investigated. The core process of the approach is an automatic optimization design process. In this approach, we construct kinematics mapping from truss structures to the joint-linked mechanisms, which transforms the topology optimization problem of multi-body system into the truss structure optimization problem. We also develop a new strategy for topology optimization of statically determinate truss, the advantage of which lies in the ability dealing with statically determinate truss topology optimization problem compared to the existing methods. By automatically optimizing the topology of the truss structure, the topology of the multi-rigid-body mechanism is optimized automatically, accordingly. Here, we utilize the investigated approach to design suitable layout for multi-rigid-body micro-displacement amplifying mechanisms (MMAMs) with a large amplification ratio (>50). The layout consists of not only the topology information of the mechanism, but also the dimension parameters of the mechanism. The procedure of the approach is carried out in steps, and a human–computer interaction program has been developed for it. Using the developed program, different MMAMs are achieved. Meanwhile, the direct kinematics analysis of the MMAMs is achieved automatically, the existence of dead point position in the mechanism within movement range is checked and the micro-displacement amplification ratio is calculated out. The computing results are validated by the ADAMS^® motion simulation, which proves that the achieved MMAMs fully fulfill the functional requirement. Along with two of the achieved MMAMs, the approach is explained, its functionality is shown, its advantages, limitations, some open problems and future works are discussed.     

Topology optimization of stiffened plate/shell structures based on adaptive morphogenesis algorithm

This article proposes an adaptive morphogenesis algorithm to design stiffened plate/shell structures in a growth manner. The idea of this work is inspired by researches in leaf venation which indicates that the adaptive growth of leaf vein provides the relatively large structure with an effective reinforcement. This excellent performance is regarded as the contribution of two primary morphological features: branching and hierarchy. To apply the growth mechanism of leaf venation into stiffened plate/shell structures, a mathematical model describing the growth process is established. Based on this, the adaptive morphogenesis algorithm is developed to make stiffeners “grow” step by step. Besides, the “stiffness transforming operation”, a numerical treatment, is introduced to enable stiffeners to grow along arbitrary directions in the FEM model, which guarantees the design more optimized than previous methods. To obtain a further verification of the proposed method, a comparison between the proposed method and three typical methods is implemented. This comparison shows that the proposed method endows the designed object with a more excellent performance than others. Therefore, the proposed method is competent in the stiffened plate/shell structure design.