WLAN无线网络小知识

距离与速率如果两台无线设备相互靠近，它们将以两个接口所支持的最高传输速率进行通信。但是，如果以最高传输速率进行通信，传输的距离可能小于较低传输速率传输的距离。这就是WLAN无线网络接口要提供自动选择传输速率机制的原因。如果相互移开一些距离，WLAN无线网络接口将自动降低传输速率，但只有在需要保持无线连接时才会这样。如果再相互靠近一些，自动选择传输速率机制又将自动提高传输速率，以达到尽可能最高的传输速率并提供可靠通信。如果通信失败，无线客户机适配器将以相同的数据传输速率重新传输“丢失的报文”。如果第二次尝试也失败了，无线接口将自动切换至另一种较低的传输速率，然后再次尝试传输。数据传输速率越低，无线范围越大，从而有助于传输报文。     

连接计算机打印接口的CAN总线适配卡设计

本文提出了一种计算机与ＣＡＮ通信的方法，使重新定义的计算机打印接口与具有ＣＡＮ接口的适配卡相连。适配卡以双向“透明”的方式实现两者之间的通信，文中详细阐述了适配卡的软硬件设计。     

Java产品简介(五)

Ｊａｖａ媒体与通信应用编程接口Ｊａｖａ媒体与通信应用编程接口扩展了Ｊａｖａ平台，实现了丰富多彩的媒体内容与高级通信功能的集成化。丰富多彩的媒体与增强通信相结合Ｊａｖａ媒体与通信应用编程接口由一组类库组成，它们运用完善的媒体和通信功能丰富了Ｊａｖａ应用...     

C51编程在I2C总线接口通信中的应用

文中分析了I^2C总线接口的通信原理，以X1228日历／时钟芯片的I^2C总线接口通信为例，讨论了C51的编程技术和用户函数的定义方法，最后给出了动态活动定时监视记录仪中时间设定与定时功能实现的应用程序。     

例题7 VB的串行口通信编程

串行通信在许多领域被广泛应用，标准的RS232接口已成为许多通信设备的标准接口。微机与微机、微机与外设、微机与上端机（例如：单片机）都可以通过RS232接口进行方便的连接，以实现控制外设和传输数据等目的。因此，实际工程中经常需要用到通信口方面的编程。Visual Basic的通信控件有功能强大、速度快、易于掌握等许多优点。     

PC机键盘剖析和应用

本文介绍标准微机键盘与PC机的接口规范，分析键盘的串口通讯协议和接口的工作时序，提出一种全新的利用键盘接口实现单片机系统和PC机通信以及单片机和PC机键盘通信的方案，并给出设计实例，通过实例为外部单片机系统与PC机通信以及单片机和PC机键盘通信提供了一条有效的途径。     

USB接口在通信方面的研究和应用

该文先对USB接口在通信方面的应用做了一定的研究后，提出了一个用USB接口来实现的通信系统，整个系统包括硬件电路，固件及Windows设备驱动程序。接着分析了USB接口芯片USBN9602的原理及其应用电路设计。分析了USB Windows设备驱动程序的原理。最后编程实现了USB Windows设备驱动程序。实验结果证明，此USB接口系统，测试数据传输率可达500kbps左右，符合通信设备的需要。     

基于OPC通信协议的冗余系统设计

以用于远程控制的对象连接与嵌入(OPC)标准接口为例,研究了在OPC标准接口的基础上,增加冗余通信功能和冗余切换功能。采用两路冗余接口通信和判断冗余接口通信状态的方法,实现了两条冗余通信链路的切换。采用冗余接口通信和冗余切换机制技术,实现了冗余系统的设计,满足了单一故障原则。通过在核电厂仪控系统中的实际应用,冗余的通信链路实现了正常接口通信功能和满足了核电厂对冗余系统的设计要求。研究结果证明了通过该冗余接口通信的方式实现的冗余系统在稳定性和可靠性上满足核电厂设计要求。     

基于VC++6.0的DeviceNet应用层协议的实现

本文用PCI接口芯片（PCI9052）、CAN控制器（SJA1000）设计了监控计算机与DeviceNet网络的接口，并用DriverStudio为该接口开发驱动程序。以Visual C＋＋6．0为工具开发符合DeviceNet应用层协议的通信软件，实现对DeviceNet设备的监控。     

基于PCA的软件UART设计

随着网络技术和通信技术的不断发展，对单片机的通信能力要求越来越高，异步通信技术以通信速度高、成本低、可靠性高等特点广泛应用在各种控制系统以及远程通信中，尤其适合多机或联网的应用。目前普遍应用的MCS-51系列和其他一些专用的单片机通常只具有一个UART接口，而在实际应用中往往需要两个或更多的UART接口与其他器件设备通信。一般的解决方法是用带双串口的单片机或专门的器件外扩串口，但这都会使系统的开发成本大幅提高，仍然不能满足用户的需求。本设计利用SST单片机所提供的PCA模块通过软件方式实现串行通信的异步传送，通信可靠性高，不会增加开发成本，且程序具有很好的移植性。     

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.