基于复合左右手传输线结构的新型微带天线

基于复合左右手传输线结构的零阶谐振理论,提出了一种新型双层结构的微带天线,仿真结果表明该天线具有比单层微带天线更小的尺寸。研究了天线各结构参数对天线特性的影响,并对各参数进行了优化仿真。仿真结果表明该天线具有全向辐射特性,与传统微带天线相比,该天线具有体积小的特点。     

一款用于无线胶囊内窥镜的微带天线设计与仿真

基于时域有限差分方法,采用真实人体数字三维模型,仿真了天线在人体消化道内辐射情况,分析了天线结构参数对天线辐射性能的影响。针对无线胶囊内窥镜(Wireless Capsule Endoscopy,WCE)在人体消化道内工作特点,设计了一款能够用于发送消化道内图像数据的WCE微带天线,该微带天线谐振频率为500 MHz,输入回波损耗S11-10 dB时相对带宽为8%,带内VSWR2.0,最后采用仿真优化后的结构参数和材料制作了天线,并进行了测试,得到了满足实际应用要求的微带天线。     

适用于太赫兹通信系统的E形微带天线设计

设计了一种用于太赫兹通信系统的E形微带天线,并利用高频结构仿真软件(HFSS)对设计天线进行仿真。E形微带天线通过在矩形微带天线上加载两条平行缝隙槽以获得宽频带特性。仿真结果表明设计天线的-10dB相对带宽达到29%(从1.394THz到1.87THz),同时给出了该天线的驻波比曲线图和增益曲线图。研究结果显示该E形天线结构简单,能够满足无线通信系统的要求。     

新型电磁材料微带天线的综述

随着无线传输产品的普及,各种设备对天线的性能要求越来越高,研制具备较高性能的天线的必要性越来越突出。新型电磁材料由于其自身的特点,能够实现一般材料所不具备的电磁特性,在高性能微带天线设计中得到了广泛的应用。同时,由于设计参数的复杂化和设计目标的多重化,全局优化算法逐渐引入到了天线设计中来,以实现对微带天线贴片和新型电磁材料结构的优化设计,大幅提升微带天线的各项性能。     

新型电磁材料结构的微带天线设计

使用基于Matlab的遗传算法程序结合HFSS仿真,设计了一种具有表面波带隙特性的新型电磁材料结构,将其用于微带天线能够抑制表面波、提升增益.对优化记录进行保存和查询,有效地加快了算法优化进程.通过仿真对比表明:添加该新型电磁材料结构后的微带天线工作在5.8 GHz时,增益提升1.8dB,背瓣降低3.8dB,提升了天线对电磁信号的采集能力.     

基于双三角形谐振环结构左手材料的矩形微带贴片天线

设计了一种双三角形谐振环结构的左手材料,通过理论计算和仿真实验证明了其具有电磁左手材料性质;将双三角形谐振环结构的左手材料加载在矩形贴片微带天线上,并给出了矩形微带贴片天线的结构参数;利用HFSS仿真软件对比了加载左手材料前后矩形贴片微带天线的性能,仿真结果表明,左手材料的加载提高了天线的带宽,增大了天线的增益,有效地抑制了旁瓣。     

北斗宽波束“U”型槽双频微带天线的设计

基于北斗导航系统的实际通信需求,要求接收天线具有多频带、宽波束、小型化等特点,为此选定设计一款矩形贴片微带天线。结合微带天线的双频圆极化理论,采用同轴线的馈电方法,设计了一款在贴片上开“U”型槽的双频微带天线,使微带天线可以同时工作在北斗B2频段（1210±10MHz）和B3频段（1268±10MHz）,实现了微带天线的双频化,而且减小了天线尺寸。通过HFSS对该天线进行了仿真和参数优化,结果表明,天线回波损耗S11小于-20dB;天线增益大于3dB;双频内的轴比小于6dB;具有较宽的波束,较好的圆极化性能,较小的尺寸,可达到设计要求;而且,电路的设计方法简单,制作工艺简单,可为实际的应用提供参考。     

一种Peano结构的圆极化微带天线设计

在天线结构优化设计中,为了改善电磁带隙结构下阵元间距过大造成天线阵极化特性和增益性能下降的问题,提出设计了一种Peano结构下的圆极化微带天线.使用直接传输方法分析有限周期的一阶Peano结构的表面波带隙,将电磁带隙结构放在微带天线周围,通过减小电磁带隙结构和天线的间距,优化天线结构和天线的参数,缩小阵元之间的间距.仿真结果表明,与传统的电磁带隙结构微带天线相比,改进设计能有效减小圆极化天线阵中阵元间距,抑制阵元之间的互耦,提高阵元的方向性和天线阵性能.     

汽车发动机与传动系优化匹配的仿真研究

如何设计传动系参数以达到与汽车发动机的合理匹配是汽车设计中一个重要的组成部分.文中以汽车主减速比和各档传动比为设计变量,综合汽车动力性评价指标和经济性评价指标作为目标函数,建立了优化模型,应用优化规划理论对汽车传动系参数进行优化设计,开发出了一套汽车传动系参数优化设计的仿真软件,实现了汽车发动机与传动系的最佳匹配.文章最后以某载货汽车为例,利用该优化仿真软件进行了设计计算,仿真结果表明,该设计方法是可行的.     

共轴对称球面光学系统仿真模型设计

为了优化共轴对称球面光学系统的设计,对共轴对称球面光学系统进行了数字化模型的开发,设计了基于计算机仿真的数学模型.在此基础上运用模块化程序设计思想,设计了仿真模型的模块化结构,利用交互技术解决了实验参数的人机交互,并开发了仿真模型核心模块的程序代码,建立了完整的基于计算机系统的共轴时称球面光学系统仿真模型.该仿真模型实现了系统参数变化时成像效果的动态模拟,可以为优化设计提供仿真.     

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.