企业Sendmail邮件服务器的创建

人们在Internet上最常使用的就是电子邮件,很多企业用户也经常使用电子邮件系统。在Unix系统中,Sendmail是应用最广的电子邮件服务器。本文将比较详细地介绍如何建立一个Sendmail电子邮件服务器,以满足企业的基本需求。     

构筑邮箱安全屏障——索思推出XPOST数位邮局系统

2月24日获悉,索思公司推出了采用独有H O O K挂件技术的最新加强版系统—XPOST数位邮局系统。它与Sendmail、Qmail、Postfix、Jetmail等英文邮件服务器具有良好的兼容性,可适应各种高低端服务器并提供高性能的大容量邮件服务。XPOST数位邮局系统具有WebMail和超级地址簿功能,方便用户使用邮件;它提供了邮件过滤、加密等安全配置,保证用户使用邮件的安全;内挂邮件防病毒引擎,可扫描并删除病毒;E-mail防火墙插件,能够实时过滤敏感字眼。XPOST数位邮局系统提供邮件发送监控、流量监控以及邮件监听等管理功能;支持无后台系统操作,管…     

邮件系统防止垃圾邮件攻击的安全方案的探讨

描述了邮件协议的工作原理,分析了可能出现垃圾邮件攻击的网络安全漏洞,对于目前主流邮件服务器系统Sendmail,Qmail, Lotus Domino,Exchange出现垃圾邮件主要原因、防止垃圾邮件的安全方案进行了探讨,并提出各系统相应的具体解决方案,这些方案在实际使用中取得较好的效果.     

创建企业级Internet邮件服务器

在企业的Internet应用中,如何建立一台高效、稳定、易管理的Internet邮件服务器是一项重要的工作。本文所讨论的是如何在Windows NT平台上搭建一个完整的Internet邮件服务器系统,以及如何实现邮件服务器复用等高级功能。     

JAVA实现基于LDAP的分布式WebMail系统

文章在讨论轻量级目录访问协议LDAP、Java技术和Qmail邮件服务器的基础上,设计并实现了一个分布式WebMail系统。该系统以Qmail作邮件代理、LDAP存放用户帐号信息、JSP技术编程,具有较好的可移植性、可扩充性和安全性。     

Qmail环境下安全邮件服务器解决方案

本文在讨论Qmail环境下如何建立安全邮件服务器的基础上，进一步探讨了防止“中继利用”和垃圾邮件”攻击邮件服务器的解决方案。     

新一代电子邮件系统

E-mail走近我们的生活早已不是什么新奇的话题了,速度快、操作方便、可以一信多发并附带声音图像等诸多特点使之成为了目前最流行的通信手段之一。我们知道,一个电子邮件系统的构建,除了必要的硬件(如邮件服务器)和客户端软件(如Microsoft Outlook、Foxmail)之外,最重要的就是服务器端的邮件系统软件。在Unix平台上,常用的邮件系统软件有Sendmail和Qmail,这两种软件已被某些Unix操作系统所     

基于Qmail的邮件过滤系统的设计与实现

对垃圾邮件的过滤能力是邮件服务器性能的重要标识之一,在MTA层次可以实现真正意义上的邮件过滤,并且可以有效防止邮件病毒。本文介绍了邮件过滤的基本原理,基于Qmail邮件服务器,用perl语言实现了一个邮件过滤系统应用实例。     

基于数据库的虚拟域邮件系统的构建

随着互联网应用的发展,简单地用Sendmail和POP3构建的邮件服务器,已经不能满足校园网用户的需求.本文介绍了一个用Postfix、OpenWebmail等自由软件构建虚拟域邮件系统的方案,该方案不仅支持Webmail、SMTP认证、磁盘限额等功能,而且解决了Sendmail用户平稳迁移问题,并用PHP实现了邮件用户网上注册和管理,大大减轻了邮件管理员维护的工作量.     

一种限定用户邮箱大小的实用方法

网络应用 目前,在Linux/Unix平台上,Sendmail因成为缺省安装的邮件服务器而得到非常广泛的应用。但是Sendmail本身并不具有限定用户邮箱大小的功能,所以,如果某些用户长时间不取信或设定了保留邮件副本,其信件将在服务器上不断堆积,以致邮箱越来越大,占用大量的硬盘空间,很多网络管理员对此都很有意见。这里介绍一种简单实用的方法,通过它,我们可以很方便灵活地对用户邮箱的大小进行设定。     

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.