实时通讯网络的实时性能测试与分析

对1种应用较为广泛的实时通讯网络进行了性能测试和分析,提出了相应的测试方案与测试方法;通过对反射内存网络的基本读写测试、反射内存网络节点间数据传输测试和反射内存-广播内存网络间节点传输测试三部分,得出了相应情况下的利用反射内存进行实时数据通信的信息,对节点间数据读写速度有了大体的了解,同时经过相应测试对比也验证了关于其网络结构和工作原理的分析,为实际应用提供了相应参考。     

以太网物理层芯片光电特性测试研究

当前,以太网物理层芯片在诸多应用领域不可或缺,对以太网物理层芯片的功能性能要求也越来越高,因此,如何进行芯片功能性能方面的光电特性验证是亟待解决的问题。主要介绍了以太网物理层芯片验证的技术现状,提出符合以太网物理层芯片功能性能应用需求的光电特性测试方法,采用测试仪器（如示波器、逻辑分析仪、网络矢量分析仪等）和验证板卡对网络中物理接口的数据传输电特性和光特性进行测试,测试结果表明提出的测试方法达到了测试要求,满足了功能性能应用需求,进而提高了国产高可靠以太网物理层芯片验证的技术手段。     

卷积信道编码与物理层网络编码的联合设计

针对无人机作为中继平台在异步通信条件下数据传输误码率高的问题,提出将物理层网络编码与卷积信道编码联合设计的方案。在方案中,中继节点引入置信传播(Belief Propagation)算法,将信道译码和网络编码联合起来,解决了符号偏移和相位偏移对通信系统的影响。仿真结果显示,该方案与未进行信道编码和RA码信道编码方式相比误码率最低,提高了系统的鲁棒性,可以更好地抵制相位偏移和符号偏移对通信系统的影响,提高无人机的抗干扰能力。     

不同信道下无线传感网络物理层能耗性能分析

研究了在无线传感网络物理层中误码率对无线传感器节点能量消耗的影响。提高传输误码率可以降低节点能量消耗,但为了保证发送端信号能准确传输到接收端,错误帧将重传,会消耗许多能量。降低传输误码率则会增加节点能量消耗。为了平衡误码率对节点能量消耗的作用,在不同衰减模式下得到误码率的动态最优解,和传统的采用固定误码率传输信号相比,节点能量消耗得到很大优化。     

一种新的基于MQAM的PLNC去噪映射算法

物理层网络编码(Physical Layer Network Coding,PLNC)在高阶幅度和相位调制中存在星座点模糊现象。针对这一问题提出了一种物理层网络编码去噪映射算法。在该算法中,中继节点对接收信号进行星座点重新布局,按一定规律将星座点合并,经过处理后的信号星座点降低了一半,进而下行链路的调制阶数也降低了一半,星座图相邻点之间的欧氏距离变大,系统误码率性能得到提高;且中继节点只需解调-重映射-调制,处理复杂度低。通过计算机仿真验证了该算法的有效性。     

双向中继网络中的物理层网络编码方案

双向中继系统中的物理层网络编码可以有效的提高无线中继网络的吞吐量,受到了普遍关注。为了提升物理层网络编码在无线信道中的性能,提出了联合网络编码与信道编码设计思想。在联合信道编码-网络编码思想基础上,提出了一种结合LDPC信道编码和网络编码的线性性质来提升网络编码在双向中继系统中的性能,并最后给出该方案的误码率仿真图。     

基于CPCI总线的反射内存网络接口卡研制

反射内存网络具有协议简洁、组网简便、确定性延时等突出特点,因此在半实物仿真系统和分布式测控系统中有着广泛的应用;根据环形反射内存网络的组网需求,研制开发了一种具有CPCI接口的反射内存网络接口卡,实现了网络链路层和物理层的功能;同时,设计开发了Windows XP操作系统下的驱动程序,以API函数的形式实现了软件层的功能;研制中还构建了反射内存网络测试环境,进行了数据传输测试和DMA读写测试;实验结果表明基于CPCI总线的反射内存网络接口卡工作稳定、可靠,数据更新速率快。实验结果亦表明应当根据反射内存网络传输的数据帧数量适当的选用DMA或单次读写方式。     

一种基于BICM-ID的物理层网络编码联合设计方案

基于迭代比特交织编码调制(BICM-ID)提出了一种物理层网络编码与编码调制技术联合设计方案。该方案将编码调制技术和物理层网络编码联合设计,提高了网络吞吐量,通过设计一种星座映射方案,增大欧氏距离,降低误码率。此外,由于译码器部分只采用了一个SISO译码模块,编码译码方式采用卷积码,使得译码复杂度大大降低。     

无人机通信中的非对称物理层网络编码研究

物理层网络编码可以提高无线通信系统的性能。针对无人机组网通信的环境特点,建立了无人机组网通信中的非对称双向中继信道模型,研究了该模型中的物理层网络编码,提出了非对称多阶相移键控物理层网络编码方案,推导出该方案的中断概率、误码率等无人机组网通信系统的主要性能指标的理论表达式。通过实验,验证了所提出方案及其理论分析的正确性,分析了各种非对称相移键控调制方式下的系统性能,为物理层网络编码在无人机组网通信中的设计以及性能评估提供了理论依据。     

1000Base-T型网络物理层特征信号测试技术研究

物理层基于网络结构底层,负责网络电信号的发送、接收,当物理层性能状态出现问题时,将严重影响网络设备的通信质量,且故障点难以被发现排除。本文依据《IEEE 802.3-2000和ANSI X3.263-1995标准》对以太网物理层的相关要求,对1000Base-T型网络接口物理层一致性特征信号测试方法进行研究,结合数字示波器高级触发功能设计了能够准确捕获特定特征信号的测试方法,该方法能满足网络物理层一致性测试相关需求。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.