VoIP防火墙穿越方法的研究与比较

VoIP技术已经广泛应用于企业级的语音业务,但是为了安全性和节省IP地址的使用,目前大量的企业和局域网都采用Firewall/NAT技术连接到Internet.比较了传统的Firewall/NAT的穿越方案,并介绍和比较了较新的ICE和VPN穿越方式,描述了各种穿越方法的穿越机制,分析了各种方法的优缺点,并作了横向比较.     

加倍地做好自己的事情

改革开放以来,中国经济的高速发展引起全世界的高度关注,也一路伴随着西方发达国家对逆差、汇率、质量、环保、人权等方面的不断施压.而近来,随着部分别有用心之人利用火炬接力把北京奥运肆无忌惮地政治化,使双方的情绪也达到了对立新高潮.     

论网络时代医药企业的营销决策

传统的营销方式在网络时代已经不再占有优势,网络时代的营销也不仅仅是做个网站来展示自己的商品,而是通过人性化的服务来进一步推销自己的产品.传统意义上的市场营销,是指个人和群体通过创造并同他人交换产品和价值,以满足需求和欲望的一种社会和管理过程.     

三地路演,带来一路震撼——记2007年世冠AMESim车辆行业技术研讨会

在路演上海专场,笔者有幸与IMAGINE市场及销售总监Olivier DATRY、特种热动力应用事业部经理Cedric ROMAN、区域技术经理David MARAND及世冠公司总经理李京燕女士进行了深层次的交流.     

本地化,服务于中国用户——SolidWorks"老兵"写"新传"

作为SolidWorks在中国华南的增值软件经销商,智诚科技(ICT)公司一直以推动整个制造韭技术发展为己任,以先进的设诗理念引导中国的制造业紧跟世界最新潮流为目标.     

A hybrid time-delay prediction method for networked control system

This paper presents an Ethernet based hybrid method for predicting random time-delay in the networked control system.First,db3 wavelet is used to decompose and reconstruct time-delay sequence,and the approximation component and detail components of time-delay sequences are fgured out.Next,one step prediction of time-delay is obtained through echo state network(ESN)model and auto-regressive integrated moving average model(ARIMA)according to the diferent characteristics of approximate component and detail components.Then,the fnal predictive value of time-delay is obtained by summation.Meanwhile,the parameters of echo state network is optimized by genetic algorithm.The simulation results indicate that higher accuracy can be achieved through this prediction method.     

多起典型网络安全事件被成功处理——CNCERT/CC2007年网络安全事件处理部分案例介绍

恶意代码事件处理"Nimaya(熊猫烧香)"病毒事件处理"Nimaya(熊猫烧香)"病毒在2007年初出现流行趋势。该病毒具有感染、传播、网络更新、发起分布式拒绝服务攻击(DDoS)等功能。     

知识资本:中国参与全球创新网络的关键

对于当前世界发达经济实体中的领袖而言,中国到底是威胁还是机遇?在全球商业、工业、政府和学术观察人士中间,这一争论仍在延续.中国在全球工业中的显著作用已经无庸讳言.今天,中国制造了世界上50%的照相机、30%的空调和电视机、25%的洗衣机及接近23%的冰箱.制造业占中国GDP的53%,出口额的90%,进口额的85%以及吸引投资额的70%.中国是世界上(继美国、日本和德国之后)的第四大生产国,并正以惊人的增长速度向前发展.     

整合江湖谁称霸 AMD 780G对决NVIDIA MCP78

AMD 780G 作为超威派7系列整合芯片组掌门人,AMD 780G算得上乱世英雄,因为它是首款正式上市的DirectX 10整合主板,引领着整合江湖进入到另一个新"视"界.这款芯片组全面支持新一代K10处理器,支持Hyper Transport 3.0总线与PCI-E2.0显卡插槽,并且内建了性能等效于Radeon HD2400 PRO的显示核心,从而全面支持UVD高清解码引擎.另外,这款整合芯片组还特别对混合交火技术提供支持,从而让AMD 780G这位独行侠行走江湖一段时间后,便获得了众多派别的鼎立相助,江湖地位日渐攀升.     

单位局域网中ARP攻击的故障处理

1故障现象公安部上海消防研究所11台接入层交换机通过一台交换机和路由器进行级联,接入层交换机类型为ZXR102826(以下简称2826)。设备自开通两年以来一直运行正常,用户上网和下载上传均正常,但是在某个时刻该11台交换机上的40%用户无法上网,表现为打开网页出现"Internet Explorer不能链接到您请求的网页。此页可能暂时不可用。",但其余用户能正常上网,但表现为上网速度大幅度下降。     

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。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.