视频通信的网络自适应传输控制技术

针对视频传输中的拥塞控制问题，对网络自适应传输控制技术进行了研究，该技术综合了UDP与TCP的传输特性，能够对网络拥塞进行自适应控制。提出了该技术的技术框架和实现方案，并将其应用在一个端到端的视频传输系统中。实验结果表明，网络自适应传输控制技术可以为视频通信提供良好的传输质量保障。     

网络自适应传输控制策略研究

针对流媒体传输中的拥塞问题，对网络自适应传输控制进行了研究，结合RTP协议的传输特性，提出了一种基于带宽的网络自适应传输策略并阐述了这种策略的控制机理。该策略能够根据网络资源状况动态调节传输速率、匹配网络带宽，实现了网络自适应传输。     

基于光纤传输的数字视频系统的应用和优势

本文介绍了光纤传输网络的发展现状及趋势，提出了一种基于光纤传输网络的数字视频传输系统的应用和优势，并介绍了光纤传输特点，数字视频的指标、光纤视频传输设备，最后给出了一个基于多层光纤网络结构中系统设计时的应注意问题。     

基于UDP协议的视频图像传输的研究与实现

本文首先介绍了利用UDP协议进行视频网络传输的优点和不足。然后，根据视频网络传输的要求扩展了UDP协议，给UDP数据包定义了一个8个字节的包头结构，用来传送数据包的序列号、时戳等信息，且在发送端对传输进行光滑化处理，严格控制数据包发送间隔，减小了传输延迟，减小了拌动发生的可能性，从而保证了视频传输的有序性和正确性。最后，给出了一种在Delphi6.0下实现的视频传输的具体方法和流程。该软件能够满足多种网络平台上的视频传输的要求。     

双全桥无线电能双向传输和信息反向传输系统

针对无线电能和信息同时传输问题，提出采用双全桥结构实现电能双向和信息反向传输。首先，建立数学模型，推导电能传输方向和移相角之间的关系。其次，为实现电能反向传输信息，在电能传输主结构上增加新的磁接口传输信息。最后，通过仿真验证了结构的可行性，实现电能双向传输和信息反向传输。     

远程图像传输关键技术的研究

图像传输在图像监控系统中占有重要的地位。图像在传输过程中容易出现延时、抖动、失真等问题，本文对图像传输中的传输协议，传输方式，以及传输软件等一些关键技术进行了较为全面的分析，使图像传输的质量得到显著的提高。     

网络传输时延的测量方法

介绍了网络传输时延的基本概念，分析了影响网络传输时延的因素，给出了测量传输时延的3种方法，并对各种方法作一综合比较。     

基于现场总线网络图像传输的实现

采用基于小波变换的ADV611视频压缩芯片进行图像压缩，解决了视频数据过大的问题。设计了PROFIBUS-DP与Ethernet的网关模块来进行图像数据的传输，充分利用了现场总线传输快、带宽高的特点，并给出了传输系统的硬件组成。实验证明这种方法不仅能够在保证图像数据完整性和图像质量的同时，极大地延长了传输距离，提高了传输速度，减少了传输误差，还可以节约成本，避免重复投资。     

USB2．0传输类型分析

为了满足不同类型外围设备的设计与应用，USB传输协议定义了4种传输类型：控制传输、同步传输、中断传输和批量传输。例举了一个全速设备的端点描述符，从定义、结构、信息包大小、传输速度和错误检测等方面对4种传输类型进行了分析和研究。     

用KERMTT协议高效地传输汉字文件

ＫＥＲＭＩＴ是一种常用的微机间进行异步文件传输的协议，由于它只有７位数据位传输，在传输８位的汉字字符时先要进行变换，严重影响了传输效率，本文讨论了ＫＥＲＭＩＴ协议的主要特点，影响汉字传输效率的原因，并给出了一种改进方案。     

TD-SCDMA系统小区无线负荷研究与仿真

接纳控制是TD-SCDMA系统无线资源管理中一个重要方面，它建立在对各小区负荷的测量基础之上，因此，小区负荷的计算方法成为一个十分重要的研究问题。由接纳控制和小区负荷等概念入手，提出小区上、下行负荷估计算法，上行负荷算法基于对噪声恶化量的控制．因该值能很好的衡量系统的干扰状况；下行负荷算法主要参考基站发射的总功率，有着直观的物理意义。进一步分析了邻小区干扰与小区负荷之间的关系，为网络的优化提供了理论依据。相关重要变量关系做了仿真，算法得到验证。     

遥感卫星图像几何粗校正的数据并行方法研究

主要研究星上遥感图像的实时几何粗校正问题．卫星遥感图像现在一般都大到上万个像素行和列，采用传统的单个处理器的串行方式在星上进行实时处理是难以满足应用要求的．提出了一种在一维PE阵列的SIMD计算机上采用基于处理元阵列平移的数据并行校正方法，并根据NASA的LANDSAT-1卫星的有关的参数，对该方法进行了详细讨论，给出了具体的实现方法．通过对复杂性和加速比的讨论，表明该方法在性能上比采用单个处理器的串行方法提高了N倍．     

Impact of a transmission facility link failure on dynamic call routing circuit-switched networks under various circuit layout policies

A major transmission facility failure such as a fiber cut can significantly deteriorate the performance of a network by affecting multiple trunk groups in the network. To improve network performance various restoration options (pre-planned or real-time) in the traffic and/or the transmission facility network can be addressed. In this paper, we address the implication of various pre-planned circuit layout policies (based on trunk group diversity) on dynamic routing circuit-switched networks in the event of a failure. Using a network based on realistic data, we give results on comparative network performance under different circuit layout policies and on the effect of a failure depending on the time of the day it occurs. We observe that in the event of a failure, a network with trunk group diversity provides load balancing in terms of pairwise blocking and avoids isolation of traffic pairs compared to a network without trunk group diversity. However, in some instances, the overall network blocking may not be lower in a network with trunk group diversity compared to a network without trunk group diversity.     

三角形域上的超限插值方法

在三角形域上构造对边界曲线和跨界导数插值的三角曲面是计算机辅助几何设计和计算机图形学等领域中的基本问题.此类问题称为三角形域上的超限插值问题.对现有三角形域上的超限插值方法进行了综述,并对现有三角形域上的超限插值方法以具体实例进行了比较.最后讨论了现有三角形域上的超限插值方法中有待进一步解决的问题.     

色彩在版面设计中的应用与研究

在商业设计中,版面设计是一个建立在准确功能诉求与市场定位的基础之上,以有效传播为导向的视觉传达艺术。色彩作为大众视觉语言,是商业设计中一个十分重要的元素。本文主要针对色彩在版面设计中的应用进行探索与研究。从版面设计中的色彩理论知识到色彩运用技巧,进行了详尽的讨论与分析,借以提升对色彩主色调、冷暖色、明色与暗色等各个方向上的把控能力,在此基础上进一步研究色彩在心理反应方面的普遍规律,利用其作为版面设计的有力武器,使色彩成为真正的行销工具。     

VALIDATION OF FIRST-ORDER RULE-BASED SYSTEMS1

Knowledge base validation and knowledge base refinement aim to help the expert to improve an existing knowledge base. They deal with the final knowledge acquisition phase and rely on a quality measurement of an existing knowledge base. We present our approach to knowledge base refinement, which is based on results in the domain of knowledge base validation. Our approach is based on a general consistency definition of a knowledge base and on a study of causes of knowledge base inconsistency. Our approach relies significantly on a differentiation of sure and expert knowledge in the knowledge base. We have implemented a system that has two phases: one computational phase decides on the consistency of a knowledge base, and, if necessary, a second phase helps the expert to interactively update the knowledge base. We present some related work in the domain. We illustrate the use of our system with an example.     

Optimization on a Grassmann manifold with application to system identification

In this paper, we consider the problem of optimization of a cost function on a Grassmann manifold. This problem appears in system identification in the behavioral setting, which is a structured low-rank approximation problem. We develop an optimization approach based on switching coordinate charts. This method reduces the optimization problem on the manifold to an optimization problem in a bounded domain of a Euclidean space. We compare the proposed approach with state-of-the-art methods based on data-driven local coordinates and Riemannian geometry, and show the connections between the methods. Compared to the methods based on the local coordinates, the proposed approach allows to use arbitrary optimization methods for solving the corresponding subproblems in the Euclidean space.     

Experience with a genetic algorithm implemented on a multiprocessor computer

Numerical experiments were conducted to find out the extent to which a Genetic Algorithm (GA) may benefit from a multiprocessor implementation, considering, on one hand, that analyses of individual designs in a population are independent of each other so that they may be executed concurrently on separate processors, and, on the other hand, that there are some operations in a GA that cannot be so distributed. The algorithm experimented with was based on a gaussian distribution rather than bit exchange in the GA reproductive mechanism, and the test case was a hub frame structure of up to 1080 design variables. The experimentation engaging up to 128 processors confirmed expectations of radical elapsed time reductions comparing to a conventional single processor implementation. It also demonstrated that the time spent in the nondistributable parts of the algorithm and the attendant cross-processor communication may have a very detrimental effect on the efficient utilization of the multiprocessor machine and on the number of processors that can be used effectively in a concurrent manner. Three techniques were devised and tested to mitigate that effect, resulting in efficiency increasing to exceed 99 percent. Of particular interest to the user, corresponding elapsed time compression factors approaching 128 are realized on 128 processors. Received October 18, 2000     

广告创意及发展趋势浅谈

广告创意绝不仅仅只是色块、图像、字体的简单排列组合,而是一门关于人性的学问。杰出的广告创意既不是一味追求对产品功效进行夸大,也不是运用艺术化的手法对产品进行空洞虚饰,而是需要建立在对消费者人性予以洞察、分析、研究的基础之上,实现广告信息的单纯化、清晰化、戏剧化,并最终使广告在消费者脑海中留下深刻而难以磨灭的印象。唯有如此,广告创意才真正的实现科学与艺术的完美结合,成为令人叫好叫座的经典。     

How trainee teachers of IT approach teaching their subject

Abstract  This paper explores the nature of Information Technology (IT) as a separate subject in the secondary school curriculum. It reports on research carried out with a cohort of specialist IT post-graduate trainee teachers at a local university. The paper explores IT trainees' approach to teaching their subject and describes their strong focus on purpose when teaching IT. Important characteristics of the purposeful approach are the use of authentic data; the transformation of data by pupils; and a focus on problem solving within a context to which pupils can relate. However in their work in schools, trainees found constraints on developing a strong focus on purpose in their lessons. They were encouraged to experiment but felt they needed more support to carry out purposeful activities with pupils. The implications of this research on teacher training and on the value of IT as a curriculum subject are discussed.