USB总线微波功率计设计

为提高微波功率测量仪器与其他设备的兼容性,简化电路结构,设计了二极管检波式USB总线微波功率计.重点研究了微弱信号检测、高速USB总线和数字校准技术.经过对二极管检波、微弱信号检测、USB通信的优化设计,制作了功率计探头.设计了数字校准补偿算法,利用NI-VISA和多线程技术设计编写了功率计软件.试验表明,设计的USB...     

多波形射频功率测量技术

功率检波是测量射频信号功率的常用手段之一,采用对数检波的方式对某平台的多种射频信号进行功率测量,满足复杂条件下的装备地面检测和检修的需求。分析了对数检波的工作原理,对3种检波器进行了性能比较,并以对数检波器为基础进行了系统论证、电路设计和软件设计,分析了误差的来源,并对误差进行了校准,通过试验验证了设计的有效性。多波形检测时,不同的调制波形会产生不同的检波信号,需要进行相应的处理。校准是保证测量精度的必要手段,也是设备的软硬件设计和调试重点,通过标准信号源以频率、功率、波形和温度为参数进行组合校准。设备可在-40~65 ℃的环境温度下达到±2 dB的测量精度,具有环境适应性强、测试精度高的特点。     

便携式真峰值功率计设计

提出了一种便携式真峰值功率计的设计原理，详细介绍了便携式真峰值功率计的基本结构及其工作过程，论述了峰值检波、随机采样、自动测频、频响误差补偿技术与校准、测量软件的实现原理并给出了实现方案。按照该方案设计的便携式峰值功率计实现了对射频信号功率的准确快速测量。     

一种微波附件组合的设计与实现

在综合测试与诊断领域,随着被测系统复杂性的提高,对测试系统准确度要求进一步提高。文中设计实现了一种微波附件组合,主要由微波开关、衰减器、功率放大器和电源组成。该设备实现了各项技术指标要求,其中微波开关的驻波比在DC-1GHz时不大于1.3,在1GHz-18GHz时不大于1.5;衰减器的衰减量是40dB,精度是±3.5dB,驻波比不大于1.6;功率放大器的频率范围在0.9GHz～1.3GHz范围之内,输出功率不小于5W。该微波附件组合结合信号源、频谱仪、功率计及各类模拟器等射频仪器资源来实现射频测量通道的资源扩展、大功率信号的衰减调理、微波功率合成等功能。以满足被测试对象飞机系统中的微波射频系统、部件等微波信号性能测试的测试需求。     

泰克推出紧凑型射频、微波功率传感器/功率计

为微波和射频行业提供信号发生和分析解决方案的全球创新厂商--泰克公司日前宣布推出紧凑型射频(RF)和微波功率传感器/功率计产品系列,这些产品具备业内最快的测量速度,覆盖射频、微波频率范围,并提供从基本平均功率到脉冲     

泰克推出紧凑型射频、微波功率传感器/功率计 新产品系列提供业内最快的测量速度和先进的功能,同时无需归零和校准

<正>2011年12月14日,泰克公司推出紧凑型射频(RF)和微波功率传感器/功率计产品系列,这些产品具备业内最快的测量速度,覆盖射频、微波频率范围,并提供从基本平均功率到脉冲参数(pulse profiling)的广泛功率测量。泰克PSM功率计系列在全工作温度范围内已完全校准,无需传感器归零和功率计参考校准。     

泰克推出紧凑型射频、微波功率传感器／功率计

泰克公司推出紧凑型射频（RF）和微波功率传感器／功率计产品系列,这些产品具备超快的测量速度,覆盖射频、微波频率范围,并提供从基本平均功率到脉冲参数（pulsepr ofiling）的广泛功率测量。泰克PSM功率计系列在全工作温度范围内已完全校准,无需传感器归零和功率计参考校准。     

紧凑型射频、微波功率传感器／功率计

泰克公司日前宣布,推出紧凑型射频（RF）和微波功率传感器／功率计产品系列,这些产品具备业内最快的测量速度,覆盖射频、微波频率范围,并提供从基本平均功率到脉冲参数的广泛功率测量。泰克PSM功率计系列在全工作温度范围内已完全校准,无需传感器归零和功率计参考校准。     

泰克推出紧凑型射频、微波功率传感器/功率计

为微波和射频行业提供信号发生和分析解决方案的全球创新厂商——泰克公司日前宣布推出紧凑型射频(RF)和微波功率传感器/功率计产品系列,这些产品具备业内最快的测量速度,覆盖射频、微波频率范围,并提供从基本平均功率到脉冲参数(pulse     

微梁结构热偶微波功率传感器芯片的制作工艺

在微波技术研究中，微波功率是表征微波信号特性的一个重要参数，微波功率测量已成为电磁测量的重要部分，可应用于很多场合，如发射机输出功率（包括天线系统辐射的功率）和振荡器输出功率的测量，毫瓦计的校准，标准信号发生器的校准等。微波功率传感器是微波功率计探 头中的核心元件。微染结构热偶微波功率传感器芯片选择具有低电阻温度系数的Ta2N和高热电功率塞贝克系数的Si作为热 材料，利用半导体工艺和MEMS工艺制作，并最终研制成合格的芯片，芯片具有尺寸小，功耗低，灵敏度高，频带宽等特点，简要介绍了芯片的结构原理，并详细介绍了芯片的制作工艺。     

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.