An empirical investigation into the adoption of systems development methodologies

A postal survey was conducted to determine the following: the extent to which systems development methodologies are used in practice; the rating of their contribution to the development process; and the future trend in methodology adoption, whether the trend is toward increased usage or not. Among the main findings of the study were that 60 percent of the respondents were not using methodologies. Also, only six percent of respondents reported following a methodology rigorously. Finally, the forecast is not positive for methodology advocates: 79 percent of those not using a methodology indicated that they did not intend to adopt one.     

Ethernet技术在小区智能化中的应用

为解决目前国内小区智能化存在的问题,通过对国内小区智能化现状的调查,发现存在着太多的问题.技术标准不统一,系统兼容性很差,已建设好的小区智能化系统很多没有得到很好的利用,甚至成为摆设.提出在小区智能化建设中Ethernet技术不仅用于信息系统,同时取代标准不一的现场总线技术,应用于控制系统中,即完全基于Ethernet...     

Does not compute — old security vs new threats

??Does not compute?? was a catchphrase in old science fiction works. It was mostly uttered by robots that were in the unfortunate situation of having to understand the human conditions in computational logic. The robots frequently exploded in such cases. IT-security finds itself in a similar situation. It has to understand a new situation: a revolutionary change in the offense. Attackers have grown up. Resourceful, strategic perpetrators have appeared on the stage. Yet IT security cannot tackle these attackers. Its?? priorities are not aligned appropriately. This suggests the need for a paradigm change. But this is not easily evoked. Persistent uncertainties hamper the necessary decisions. And unfortunately, not the inflexible IT security, but other things might explode.     

Revisiting the need for formal education in visualization.

Defining visualization education is still a work in progress. Visualization education is not just a subject within computer science. Computer scientists are not always the appropriate choice to teach visualization courses on their own. Visualization is not just mastering a set of concepts but acquiring skills. Student should learn by doing, either using one tool or a variety of tools, depending on the course's focus.     

Aesthetics of navigational performance in hypertext

A hypertext learner navigates with a instinctive feeling for a knowledge. The learner does not know her queries, although she has a feeling for them. A learners navigation appears as complete upon the emergence of an aesthetic pleasure, called rasa. The order of arrival or the associational logic and even the temporal order are not relevant to this emergence. The completeness of aesthetics is important. The learner does not look for the intention of the writer, neither does she look for significance. Lexia has a suggestive power and she is suggested in the arrival of aesthetics. Hypertext learning does not depend on communication. The learner in her pleasure transgresses the bounds of space-time to be in communion with several writers/learners. Hypertext learning does not appear to be fundamentally different from the analog learning; however, in performance, as in navigation, the learner assumes a mental state that helps her in her emergence into aesthetic bliss, of an arrival to the completed lexial navigation. This completeness is owing to aesthetics and is not owing to either the semantics or the query-fulfilling qualities.     

基于Petri网的数据库系统并发控制活性分析

从数据库系统在时刻t的状态N出发,构造出相应的Petri网模型,进而构造出其可达标识图。通过分析可达标识图,可判断系统是否为死锁状态。若不是死锁状态,系统是否可能出现死锁,什么情况下系统肯定不会出现死锁。最后,给出了数据库系统中事务并发操作的死锁检测方法与避免措施。     

基于Petri网的并发系统活性分析

本文从数据库系统在时刻t的状态N出发，构造出相应的Petri网模型，进而构造出其可达标识图．通过分析可达标识图，可判断系统是否为死锁状态．若不是死锁状态，系统是否可能出现死锁，什么情况下系统肯定不会出现死锁．最后，给出了数据库系统中事务并发操作的死锁检测方法与避免措施．     

A note on knowledge-based programs and specifications

Summary. Knowledge-based program are programs with explicit tests for knowledge. They have been used successfully in a number of applications. Sanders has pointed out what seem to be a counterintuitive property of knowledge-based programs. Roughly speaking, they do not satisfy a certain monotonicity property, while standard programs (ones without tests for knowledge) do. It is shown that there are two ways of defining the monotonicity property, which agree for standard programs. Knowledge-based programs satisfy the first, but do not satisfy the second. It is further argued by example that the fact that they do not satisfy the second is actually a feature, not a problem. Moreover, once we allow the more general class of knowledge-based specifications, standard programs do not satisfy the monotonicity property either. Received: January 1997 / Accepted January 2000     

Upgrading, catching up, and shooting for par [PC market economics]

In general it is not odd for buyer and seller to have different perspectives. Indeed, ever since PCs migrated from the hobbyist community into the business community, such a difference has existed in the PC market. Buyers and sellers are not playing on the same course. Why does this matter? Because most PC engineers I know do not talk to their biggest customers-business managers. As a result, most PC engineers do not understand how their biggest customers think on the most basic level. These problems illustrate a more general economic phenomenon that goes to the heart of how computer technology spreads in the US economy     

TAPON-MT: A versatile framework for semantic labelling

Semantic labelling refers to the problem of assigning known labels to the elements of structured information from a source such as an HTML table or an RDF dump with unknown semantics. In the recent years it has become progressively more relevant due to the growth of available structured information in the Web of data that need to be labelled in order to integrate it in data systems. The existing approaches for semantic labelling have several drawbacks that make them unappealing if not impossible to use in certain scenarios: not accepting nested structures as input, being unable to label structural elements, not being customisable, requiring groups of instances when labelling, requiring matching instances to named entities in a knowledge base, not detecting numeric data, or not supporting complex features. In this article, we propose TAPON-MT, a framework for machine learning semantic labelling. Our framework does not have the former limitations, which makes it domain-independent and customisable. We have implemented it with a graphical interface that eases the creation and analysis of models, and we offer a web service API for their application. We have also validated it with a subset of the National Science Foundation awards dataset, and our conclusion is that TAPON-MT creates models to label information that are effective and efficient in practice.     

Further comments on "Aggregation matrix for the reduced-order continued fraction expansion model of Chen and Shieh"

Abstract-Contrary to what has been proposed in a recent paper, a reduced model by a continued fraction expamion method is not generally an aggregated model we observe in the example given by the authors themselves that the aggregation relationship is not valid.     

The use of technology as one of the possible means of performing instructor tasks: Putting technology acceptance in context

For many instructors in higher education, use of a learning management system (LMS) is de facto mandatory. Nevertheless, instructors often have much freedom in deciding which functionalities of the LMS they use; that is, whether they perform each individual instructor task using the LMS. Alternatively, they may perform one specific instructor task using alternative means, or, quite often, not perform it at all. The current Technology Acceptance model (TAM) fails to describe this decision process accurately, as TAM (1) does not focus on the level of the individual task; (2) does not make a distinction between not performing a task and performing a task using alternative means; and (3) does not recognize one important factor that affects the performance of a specific task—task importance. A test of three different models shows that the decision process is best represented as a two-step process. First, influenced by task importance, a choice is made to either perform a specific task or not. Second, after the decision has been made to perform the task, and influenced by the usefulness and ease of use of the LMS, a choice is made between performing the task using the LMS and using alternative means.     

The use of technology as one of the possible means of performing instructor tasks: Putting technology acceptance in context

For many instructors in higher education, use of a learning management system (LMS) is de facto mandatory. Nevertheless, instructors often have much freedom in deciding which functionalities of the LMS they use; that is, whether they perform each individual instructor task using the LMS. Alternatively, they may perform one specific instructor task using alternative means, or, quite often, not perform it at all. The current Technology Acceptance model (TAM) fails to describe this decision process accurately, as TAM (1) does not focus on the level of the individual task; (2) does not make a distinction between not performing a task and performing a task using alternative means; and (3) does not recognize one important factor that affects the performance of a specific task—task importance. A test of three different models shows that the decision process is best represented as a two-step process. First, influenced by task importance, a choice is made to either perform a specific task or not. Second, after the decision has been made to perform the task, and influenced by the usefulness and ease of use of the LMS, a choice is made between performing the task using the LMS and using alternative means.     

February: Eventful horizon

February proved to be an interesting month on the virus front, in large part due to the controversy surrounding many of the newly discovered malware threats. Not only could vendors not agree on names, in one case they could not agree on whether the malware was a worm or a Trojan Horse — or even specifically what the malware proposed to do. Even the motive behind a worm became the subject of debate. However, the disagreements between anti-virus vendors were not the only common theme played out in the month of February.     

Understanding the success of strategic IT benchmarking—Exploring the role of the individual level

IT organizations use strategic IT benchmarking (SITBM) to improve business-IT alignment or for developing IT strategies. However, SITBM often does not result in the desired outcomes. Because the extant literature does not contribute to improving SITBM success, we conduct a deductive-inductive study to understand which factors distinguish successful and unsuccessful SITBM. We find that traditional project-level factors do not explain SITBM success; they are necessary but not sufficient. Rather, we show that the individual level is instrumental for explaining SITBM success, especially by ensuring the buy-in of relevant project team members – a perspective not yet discussed by pertinent literature.     

基于凸松弛方法的医学 B 超图像快速分割

利用活动轮廓线方法进行图像分割的一个重要缺陷是目标函数是非凸的, 这不仅使得分割结果容易陷于局部极小, 而且还使得一些快速算法无法开展.本文首先从贝叶斯风险估计的方法出发,针对B超幅度图像, 给出一种基于Rayleigh分布的活动轮廓线模型. 然后结合凸松弛的方法,得到一个新的放松的凸模型.原有模型和放松后模型的关系可由定理1给出. 最后结合分裂Bregman算法, 给出基于B超分割模型的快速算法.与传统梯度下降法相比较,本文提出的算法不仅能得到全局最优解,而且在算法收敛速度上也 大大优于梯度下降法.     

The future of PGP on the Internet

The opinion of many truly knowledgeable in the areas of security in general, and Internet security in particular, is that the only true security will come from full encryption. If the messages you send are encrypted, what does it matter if they are intercepted and viewed by unauthorized individuals? If an intruder breaks into your system or network and finds that all files are encrypted, what secretes will leak, what vital information can be altered without user knowledge? If your encryption algorithm is solid, and your encryption keys are both good (i.e. not readily guessed) and secure (i.e. not readily stolen — not written on a post-it note on your VDT, not written on the last page of your desk diary, not kept in a clear text file on your disk or sent in clear text on a LAN, etc.), and if you maintain complete, current and correct backups of all critical files (which you should certainly do, independent of any Internet connectivity), then at worst you may suffer inconveniences as a result of security breaches.     

The New Frontier Issues for Cognition Technology

Cognitive engineering has developed enormously over the last fifteen years. Yet, despite many excellent research projects and publications, its full potential has not been embraced into mainstream system design. This paper will examine the reasons for this failure and argue that the problem is not simply inertia or lack of education. There are strong organisational influences that cause resistance to this particular approach. The discipline itself has characteristics that make it fragile in the modern corporate structure. In addition, the cognitive engineers themselves are not blameless in the equation. They appear to have done exactly what they criticise the engineering community for doing: they have packaged their product in a manner that is not ‘user friendly’ to its target population, not structured to suit its application, and not output in the format required. Suggestions will be made to rectify the situation: a list of actions is proposed for practising cognitive engineers to make their product more likely to enjoy widespread uptake.     

基于并行容错网的对等服务器集群的设计与实现

为了提高服务器系统的可靠性、可用性和性能,并改变目前非对称式服务器集群资源利用率低的状况,我们提出了一种新的服务器集群实现方案一基于并行容错网的对等服务器集群。在服务器集群的实现中,我们采用了软件集群的方法,设计实现了服务器集群管理层和并行容错通信层。     

基于信任度的授权委托模型

在开放式环境中,信任管理是最常用的一种访问控制方法．但是,目前存在的信任管理系统存在以下不足：（1）没有刻画实体之间的信任程度,与现实情况不相符合;（2）委托深度没有得到很好的控制．针对上述问题,提出了一种基于信任度的授权委托模型——TBAD模型（Trustworthiness-Based Authorization Delegation model）,探讨了TBAD模型的一致性验证算法,并结合具体实例对TBAD模型的使用进行了说明．