Linux环境下基于Socket的网络通信

随着Linux操作系统的不断推广,Linux环境下的Socket开发和研究已成为人们关注的热点。Socket既适用于同一台计算机上的进程间通信,也适用于网络环境中的进程间通信。它已成为当前许多操作系统的网络API,也是网络操作系统中必不可少的基础功能。因特网为网络中的应用提供了两种类型的服务:由TCP协议提供的面向连接服务和由UDP协议提供的无连接服务。     

在TCP/IP网络支持下的Client/Server编程技术

一、引言 1.网络应用程序接口socket介绍 通常用户可利用网络操作系统提供的命令,如ftp,rcp,rcmd,rlogin等来进行网络操作。但用户应用程序则需要利用TCP/IP提供的网络应用程序接口(API)来实现进程间通信。TCP/IP提供的网络API主要是socket。socket的目的是解决网间网进程通信问题,一般UNIX系统进程通信是在同一台主机内不同的进程间的通信,主要是利用进程通信机制(IPC)来实现的,通信双方可用各自的进程号来标识。但是在网络上进程间通信就比较复杂了,此时大部分通信是发     

基于PXA250和Linux嵌入式系统在机器人遥操作中的设计与实现

本文介绍了基于PXA250和Linux嵌入式系统的硬件及软件设计与实现.描述了基于PXA250嵌入式系统硬件设计原理,探讨了Linux操作系统裁剪及生成适合嵌入式的Linux操作系统.给出了全双工串行口通信和网络socket通信编程设计与实现.     

Linux Socket编程及其在无线网关中的应用

介绍了Linux环境下的socket编程，构建了基于嵌入式Linux和MPC852T微处理器的无线网关平台，通过Linux socket编程实现了无线网关平台与无线终端的网络通信，并给出了实验结果。     

Linux下ATM Socket编程

主要阐述Linux操作系统下异步转移模式 (ATM)基于套接字 (socket)的编程方法 ,并将其与传统的基于TCP IP的套接字编程方法作了比较。     

vsocket:一种基于RDMA的兼容标准套接字加速方法

为了兼容Linux标准套接字，同时利用RDMA提高使用套接字的程序的性能，提出在上层应用与底层RDMA之间搭建一个中间件——Viscore Socket adaptor(简称vsocket);通过拦截socket API,将上层应用通过套接字收发的数据流无缝转接到RDMA承载上。vsocket绕过管理收发缓冲区的内核，针对TCP和UDP分别实现了用户空间的内存管理机制，使用RC类型的RDMA网络支持TCP加速，使用UD类型的RDMA网络支持UDP加速，并重用Linux UDP来辅助其路由。实验结果表明vsocket能够保证Linux标准套接字接口的兼容性，提升网络性能，摆脱Linux内核网络协议栈的限制，改善收发数据的延迟与带宽。     

在Linux环境下SIP通信的实现

SIP(Session Initiatioan Protocol)协议是由IETF工作组于1997年7月提出的,是应用层的控制协议,能建立、调整和终止多媒体的呼叫和会话。SIP协议是基于文本方式的,即以明文方式传输。SIP消息包括请求消息、应答消息。SIP协议侧重于将IP电话作为因特网上的一个应用,并且也采用RTP作为媒体传输的协议。本文在SIP通信过程中,采用面向连接的TCP来传输SIP的交互信令,采用面向无连接的UDP协议进行实时音频流传输。本设计是在Linux操作系统下,用套接字(socket)来实现的。设计实现了SIP协议的整个通信过程。最后,提出了进一步开发的设想。     

Linux环境下基于Socket的网络通信研究

Linux作为一种更为自由的开源操作系统,随着信息技术的不断发展,也在不断的推广过程中,在Linux环境下基于Socket的网络通信也成为了研究的热点,由于Socket不单是用于单机进程之间的通信,而且也能够适用于网络通信,在Linux环境下具有很强的适用性.该文研究了Socket接口以及其在Linux环境下的通信网络...     

基于ARM-Linux的Ad-hoc组网

针对传统通信系统不能满足在无任何网络情况下的通信需求现状,设计并实现了一种由 ARM-Linux 系统及其外围部件组成的无线自组网（Ad-hoc）的通信方案.在 ARM11平台上完成了 Linux2.6.36操作系统和RT3070无线通信模块的驱动程序移植.利用基于TCP/IP协议的socket编程,编写测试程序,进行节点间无线通信传输实验.实验结果表明：本文搭建的Ad-hoc网络,可以用最少的资源和成本,实现节点间可靠的无线高速率通信,具有现实应用意义.     

基于Netlink机制的1553B协议通用接口设计

Netlink是Linux系统下的一种全新的协议族,其实现了进程间通信功能.文中在参考了linux操作系统下Netlink机制和1553B协议的实现,研究了将1553B协议和基于Netlink机制的socket套接字相结合之后,设计了一套基于Netlink机制的1553B协议通用接口.该套接口的实现是通过Netlink通信机制对socket下的协议栈进行了扩展和定义.文中实现了基于Netlink机制下使用socket API传输1553B数据的功能.通过实验验证了通用接口的便利性.     

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.