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。     

A method of defuzzification based on the approach of areas' ratio

The new method of defuzzification of output parameters from the base of fuzzy rules for a Mamdani fuzzy controller is given in the paper. The peculiarity of the method is the usage of the universal equation for the area computation of the geometric shapes. During the realization of fuzzy inference linguistic terms, the structure changes from the triangular into a trapezoidal shape. That is why the universal equation is used. The method is limited and can be used only for the triangular and trapezoidal membership functions. Gaussian functions can also be used while modifying the proposed method. Traditional defuzzification models such as Middle of Maxima − MoM, First of Maxima − FoM, Last of Maxima − LoM, First of Suppport − FoS, Last of Support − LoS, Middle of Support − MoS, Center of Sums − CoS, Model of Height − MoH have a number of systematic errors: curse of dimensionality, partition of unity condition and absence of additivity. The above-mentioned methods can be seen as Center of Gravity − CoG, which has the same errors. These errors lead to the fact that accuracy of fuzzy systems decreases, because during the training root mean square error increases. One of the reasons that provokes the errors is that some of the activated fuzzy rules are excluded from the fuzzy inference. It is also possible to increase the accuracy of the fuzzy system through properties of continuity. The proposed method guarantees fulfilling of the property of continuity, as the intersection point of the adjustment linguistic terms equals 0.5 when a parametrized membership function is used. The causes of errors and a way to delete them are reviewed in the paper. The proposed method excludes errors which are inherent to the traditional and non- traditional models of defuzzification. Comparative analysis of the proposed method of defuzzification with traditional and non-traditional models shows its effectiveness.     

Schematic classification problems and their solution

The necessity arises in a variety of tasks to classify items on the basis of the presence of one of a number of criterial sets of co-related feature values. Such sets are called class characteristics. Because such classification problems require the identification of characteristics on the basis of limited training information, they entail a difficult search problem. Consideration of the differences between the theoretical models underlying characteristic and volume pattern generators suggests a schematic approach. Schemata, sets of commonly co-occuring features values, are probabilistic indicators of class membership whenever the characteristics are unknown but the characteristic model prevails. Formal and algorithmic solutions to the classification problem when exemplars are simple (consist only of M feature or attribute values) are described. The relevance of these procedures to problems involving general (relational) data structures is also indicated.     

可拓聚类的科教人际网络节点重要性动态分析方法

目前大多数研究对复杂社会网络关键节点影响力的识别都是静态的，缺乏动态变化的分析。采用可拓聚类方法对动态变化下的科教人际网络进行量化分析，首先以多属性决策法计算每个节点重要性，再利用变异系数权重法计算得该节点综合重要性量值，之后划分等级并取标准正域和正域区间，利用可拓关联函数计算每个节点与每个等级的关联度，关联度值最大的等级即为该节点对应等级，最后分析同一社会网络节点在不同时间点的重要性等级变化。可拓聚类方法尝试从动态上对网络节点重要性进行把握，最后通过实例验证了该方法的有效性。     

Interface as Exordium: The Rhetoric of Interactivity

In this article, I outline how the interface of new media functions rhetorically as an exordium to engage users and to dispose them to persuasion. The modular, networked, and interactive nature of new media requires an interface: a central place of interaction for the technological, human, social, and cultural aspects of new media. I propose that the interface functions rhetorically through three modes of interactivity, including multi-directionality, manipulability, and presence. By understanding these modes of interactivity and how they function to create various degrees of interaction and engagement, we can begin to develop the analytic tools needed to increase critical awareness of the interface. A rhetorical understanding of the interface enables us and our students to see that the shape and design of the interface is not natural and inevitable. The design of the interface is a design of human experience and, as such, the interface becomes a locus of power. The modes of interactivity it deploys are capable of enabling empowerment and enacting rhetorical patterns of control.     

HUYGENS' PRINCIPLE,PHYSICS AND COMPUTERS

We discuss the emergence of topology from a consideration of set extensions in General Systems Theory. Boundaries arise in a natural way, separating independent elements or regions of the system. Our aim is a unification of Etter theory, Kron's method of Tearing and Jessel's formulation of Huygens' Principle. This should make explicit the equivalence between the objective, structural, holographic and the subjective, relative definitions of information, sought in Bowden (1994b), reprinted in this Special Issue. It connects the abstract generalisations of Schrodinger's equation and Bom's rule derived in probabilistic Etter theory with the real world of electrical and other physical phenomena in General Physical Systems Theory. This paper can be considered as a continuation of Bowden (1990; 1994a) and as a response to Bowden (1994b), reprinted in this issue.

We review the ideas behind Kron's Method of Tearing and Jessel's Principle of Secondary sources (both special cases of the above theory) and their equivalence. We follow Hiley's argument in Hiley (1996) to show how Schrodinger's equation can be thought of as specifying the evolution of (a series of) tearings in continuous space. These can be shown on a commutative diagram as a series of similarity transforms. We compare this with Etter's derivation (Etter, 1998). We describe briefly a recently published derivation of Maxwell's equations from a non-commutative algebra and show how they fit onto a related commutative diagram. Finally we make some comments on applications of the general theory to computer systems. This paper is a series of vignettes of work in progress. It is designed to point the direction of work to come in Constructive Physics.     

OpenFlow技术与商业价值

针对目前流行的OpenFlow技术,本文提出OpenFlow的标准进展、商业价值和连通性测试。该方法根据控制层面和转发层面相分离的技术,采用移动研究院内网拓扑进行测试。实验结果表明,通过在BigSwitch controler上进行相关命令配置就可实现二层的OpenFlow交换机互联的不同网段主机的通信。OpenFlow是SDN技术中一种关键的接口协议,SDN是对网络的抽象, OpenFlow是对单个转发面设备的抽象。OpenFlow交换机和Control er的出现为新型互联网（NGN）体系结构的研究提供了实验途径。     

Inflation function of the money supply and level of unemployment under equilibrium conditions in a market system

Based on a mathematical model of market self-regulation of inflation, it is shown that a positive inflation rate is the necessary condition of annual economic growth. Inflation is less by one than the product of money deflator and production deflator. The money deflator is proportional to the money supply in annual circulation, and it is inversely proportional to the cost of the capital invested in production sphere. The production deflator is an increasing function of the level of unemployment. An analysis of market self-regulation of inflation is illustrated by the example of the Ukraine economy. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 146–161, July–August 2007.     

Scenario-based requirements capture for human factors integration

Scenarios have been used by many engineering disciplines to assist the quality of their professional application to systems throughout a system life-cycle. At early phases of the system life-cycle, Systems and Software Engineers have adopted the Use Case as a means of representing system requirements through the address of user functions. Furthermore, usability engineers also use scenarios as a means of promoting better usability of systems throughout the system life-cycle. Moreover, all practitioners of the mentioned disciplines use some form of requirements capture and trace throughout the system life-cycle. However, in general Human Factors (HF) and Human Factors Integration (HFI) practitioners do not. This paper examines the efficacy of the multi disciplinary use of scenarios to assist the capture of HFI and system requirements. Such an approach benefits the early establishment of requirements and thus supports system life-cycle trace and matching of both physical and cognitive functions. Any views expressed are those of the author(s) and do not necessarily represent those of MOD or any other UK government department.     

基于XML的中间层交互技术的研究

由于HTML自身的不足．所以无法适应Web发展的复杂性和多变性，也不利于机器之间的数据交换和信息传递，通过对XML和HTML作多个角度的对比，文中提出将XML作为载体实现Web上的动态交互。首先从XML的自身特点出发，分析了XML驱动下的Web体系结构，从而得出基于XML的中间层交互技术的实现原理．重点研究了如何设计与XML相匹配的Web数据库，用XML查询数据库的实现方法，以及如何构造从XML到数据库的映射关系，具体包括从XIviL的DTD或者Schema出发来设计数据库的结构或者从数据库本身出发来构造与之相适应的DTD或Schema，最后分析了浏览XML格式信息的诸多策略。     

Innovative uses of ICT in Chilean schools

Abstract This paper presents some of the results of the study of seven cases of innovative pedagogical practices using ICT. The study was performed in the framework of the application of SITES M2 in Chile. The results are divided in two sections. First is a summary of each case, highlighting its innovative characteristics that serve as models of 'good practice' for Chilean teachers. Second, the results of the analysis of what teachers did are outlined; the impact on students and the type of teaching and learning activities in use. Results show that these projects did not provide evidence of having impact on students' learning as defined in the national curriculum. However, they show that students participating in these projects could learn other things, had the opportunity to develop abilities defined as cross-curricular and practised ICT related skills. The analysis of the teaching and learning activities highlights some deficiencies in the way that teachers implement new teaching strategies.