Web浏览预测的Markov模型综述

Web访问模式挖掘研究的一个重要议题是Web浏览预测,Markov模型是一种经典的Web浏览预测模型.本文首先介绍了基本Markov浏览预测模型,包括基本Markov浏览行为模型,模型的学习训练及其在Web浏览预测问题中的应用;然后重点分析了扩展的Markov浏览预测模型,包括一序组合预测模型、高序模型、混合模型、隐Mark-ov模型、连续时间Markov模型等,综述了各种扩展模型所考虑的浏览预测问题的本质出发点、模型的学习方法及预测方法,最后分析了Markov浏览预测模型有待进一步研究的问题.     

Towards new forms of knowledge communication: the adaptive dimension of a web-based learning environment

Adaptive Educational Hypermedia Systems aim to increase the functionality of hypermedia by making it personalised to individual learners. The adaptive dimension of these systems mainly supports knowledge communication between the system and the learner by adapting the content or the appearance of hypermedia to the knowledge level, goals and other characteristics of each learner. The main objectives are to protect learners from cognitive overload and disorientation by supporting them to find the most relevant content and path in the hyperspace. In the approach presented in this paper, learners' knowledge level and individual traits are used as valuable information to represent learners' current state and personalise the educational system accordingly, in order to facilitate learners to achieve their personal learning goals and objectives. Learners' knowledge level is approached through a qualitative model of the level of performance that learners exhibit with respect to the concepts they study and is used to adapt the lesson contents and the navigation support. Learners' individual traits and especially their learning style represent the way learners perceive and process information, and are exploited to adapt the presentation of the educational material of a lesson. The proposed approach has been implemented through various adaptation technologies and incorporated into a prototype hypermedia system. Finally, a pilot study has been conducted to investigate system's educational effectiveness.     

基于约束条件随机场的Web数据语义标注

Web数据语义标注是Web信息抽取中的关键步骤.条件随机场是利用序列特征处理序列标注问题的经典方法.然而现有条件随机场模型无法综合利用已有的Web数据库信息和Web数据元素之间的逻辑关系,导致Web数据语义标注准确率不高.因此,提出一种约束条件随机场模型(CCRF).该模型通过引入可信约束和逻辑约束,有效利用了已有的Web数据库信息和Web数据元素之间的逻辑关系.为了克服现有条件随机场模型Viterbi推理方法无法综合利用这2类约束的不足,该模型采用整数线性规划推理方法,将两类约束同时引入推理过程.通过在多个领域的真实数据集上的实验结果表明,所提出的模型能够显著提高Web数据语义标注的性能,并且为Web信息抽取奠定了良好的基础.     

基于社会标注质量的文本分类模型框架

社会标注是一种用户对网络资源的大众分类,蕴含了丰富的语义信息,因此将社会标注应用到信息检索技术中有助于提高信息检索的质量。研究了一种基于社会标注的文本分类改进算法以提高网页分类的效果。由于社会标注属于大众分类,标注的产生具有很大的随意性,标注的质量差别很大,因此首先利用文档间的语义相似度以及标注间的语义相似度来对标注的质量进行量化评估。在此基础上对标注进行质量过滤,利用质量相对较好的标注对文档向量空间模型进行扩展,将文档表示成由文档单词以及文档标注信息组成的扩展向量。同时采用支持向量机分类算法进行分类实验。实验结果表明,通过对标注进行质量评估并过滤质量差的标注,同时结合文档内容以及标注来对文档能提高分类的效果,同传统的基于文档内容的分类算法相比,分类结果的F1度量值提高了6.2%。     

浅谈如何设计成功的网站导航

网站导航是网站设计成功的关键．它提供获取信息的途径．并加强用户对网站的理解。本文主要从网站导航的位置、表现形式及布局方面进行分析．就如何设计成功的网站导航．提出自己的看法。     

Modeling users on the World Wide Web based on cognitive factors,navigation behavior and clustering techniques

This paper focuses on modeling users’ cognitive styles based on a set of Web usage mining techniques on user navigation patterns and clickstream data. Main aim is to investigate whether specific clustering techniques can group users of particular cognitive style using measures obtained from psychometric tests and content navigation behavior. Three navigation metrics are proposed and utilized to find identifiable groups of users that have similar navigation patterns in relation to their cognitive style. The proposed work has been evaluated with two user studies which entail a psychometric-based survey for extracting the users’ cognitive styles, combined with a real usage scenario of users navigating in a controlled Web 2.0 environment. A total of 106 participants of age between 17 and 25 participated in the study providing interesting insights with respect to cognitive styles and navigation behavior of users. Studies like the reported one can be useful for modeling users and assist adaptive Web 2.0 environments to organize and present information and functionalities in an adaptive format to diverse user groups.     

Reading skills and children’s navigation strategies in hypertext

Prior research has identified two important navigation strategies that have a clear impact on hypertext comprehension: link selection and overview processing strategies. The first relate to the order in which students select hyperlinks while trying to comprehend a hypertext, whereas the second relate to when and for how long students process navigation overviews, a text device that conveys the text structure by displaying sections, titles and their relations. Most prior research in navigation strategies has been conducted with undergraduate students. We extend prior research by exploring the navigation strategies used by sixth-graders while reading a hypermedia system. We also investigate how reading skills relate to the use of navigation strategies, and how both shape students’ comprehension in hypertext. Results from an electronic reading study replicated in sixth-graders the results on navigation strategies previously found in undergraduate samples. In addition, the results revealed that reading skills predicted the use of link selection but not of overview processing strategies. We discuss our results in light of new models of electronic reading proficiency, and propose some instructional guidelines to improve children’ electronic reading proficiency.     

Analysis of learners' navigational behaviour and their learning styles in an online course

Providing adaptive features and personalized support by considering students' learning styles in computer‐assisted learning systems has high potential in making learning easier for students in terms of reducing their efforts or increasing their performance. In this study, the navigational behaviour of students in an online course within a learning management system was investigated, looking at how students with different learning styles prefer to use and learn in such a course. As a result, several differences in the students' navigation patterns were identified. These findings have several implications for improving adaptivity. First, they showed that students with different learning styles use different strategies to learn and navigate through the course, which can be seen as another argument for providing adaptivity. Second, the findings provided information for extending the adaptive functionality in typical learning management systems. Third, the information about differences in navigational behaviour can contribute towards automatic detection of learning styles, helping in making student modeling approaches more accurate.     

ASP．NET2．0的网站导航的实现

在以往的网站开发中,网站导航的实现是以大量代码的重写和很高的维护成本为代价的,随着动态网页技术的进一步的发展和Web2．0时代的到来,以及ASP．NET2．0的推出,网站导航模块的实现从原来的大量的代码重写中解放了出来,结构更加清晰,开发的成本更低,维护也更加简单了。本文主要分析和介绍ASP．NET2．0中网站导航是如何实现的。     

基于本体的语义标注原型评述

实现语义Web构想的关键是利用本体词汇来标注Web资源,如Web页、服务等,基于本体的语义标注原型就是用于支持内容创建者在Web页中添加语义元数据,使其内容被人和机器所理解。本文首先简介现有基于本体的标注原型,然后从不同角度综述了各原型,并进行了对照比较,最后指出了现有原型的不足。     

The perceived utility of standard ontologies in document management for specialized domains

A user-based document management system has been developed for small communities on the Web. The system is based on the free annotation of documents by users. A number of annotation support tools are used to suggest possible annotations, including suggesting terms from external ontologies. This paper outlines some evaluation data on how users actually interact with the system in annotating their document especially on the use of standard ontologies. Results indicate that although an established external taxonomy can be useful in proposing annotation terms, users appear to be very selective in their use of the terms proposed and to have little interest in adhering to the particular hierarchical structure provided.     

Concepts for improved visualization of Web link attributes

This paper discusses methods to generate and display automatically additional hyperlink information to the users of the World Wide Web. Current Web browsers make it hard to predict what will happen if a link is followed: users get different information than they expect, a new window may be opened, a download starts, or the destination object is just not available. Instead of giving an appropriate notification in advance, users have to follow a link, check whether the document contains the expected information, get back, try another link etc. However, usually it is possible to obtain additional hyperlink information from several sources like link anchor tags, the user's history and Web servers. Furthermore, with little enhancements, Web servers may include even more additional information to the hyperlinks in Web documents. These can be displayed before users select a link to improve navigation and reduce the cognitive overhead. In this paper several types of Web hyperlink information are listed, potential methods to present these facts are compared, the prototype implementation of the proposed concept — called by us HyperScout — is presented, and further developments are discussed.     

Content annotation for the semantic web: an automatic web-based approach

Semantic Annotation is required to add machine-readable content to natural language text. A global initiative such as the Semantic Web directly depends on the annotation of massive amounts of textual Web resources. However, considering the amount of those resources, a manual semantic annotation of their contents is neither feasible nor scalable. In this paper we introduce a methodology to partially annotate textual content of Web resources in an automatic and unsupervised way. It uses several well-established learning techniques and heuristics to discover relevant entities in text and to associate them to classes of an input ontology by means of linguistic patterns. It also relies on the Web information distribution to assess the degree of semantic co-relation between entities and classes of the input domain ontology. Special efforts have been put in minimizing the amount of Web accesses required to evaluate entities in order to ensure the scalability of the approach. A manual evaluation has been carried out to test the methodology for several domains showing promising results.     

Individual differences and behavioral metrics involved in modeling web navigation

This paper presents an empirical study aiming at investigating individual differences and behavioral metrics involved in modeling web navigation. Factors that have an influence on web navigation behavior were identified with the aid of task analysis, and their relevance in predicting task outcomes (performance, satisfaction, perceived disorientation) was tested with the aid of multiple regression analysis. Several types of navigation metrics were calculated based on web logging data and used as indicators of user characteristics and task outcomes. Results show that spatial-semantic cognitive mechanisms seem to be crucial in adequately performing web navigation tasks. The fact that user characteristics and task outcomes can be estimated with reasonable accuracy based on navigation metrics suggests the possibility of building adaptive navigation support in web applications.     

四旋翼无人机自适应导航控制

研究四旋翼(Quadrotor)无人机导航控制问题。针对传统的四旋翼无人机导航控制方法的目标定位误差和实时性差问题,提出了基于CLOS技术的导航控制方法。采用CLOS技术所开发的导航控制系统使得四旋翼无人机能够在移动停机坪完成自主导航和着陆的任务,并详细研究了导航控制系统的设计和仿真。仿真结果显示了所设计的导航控制系统的性能和有效性,可应用于四旋翼无人机的实时导航。     

Theory and experiments in SmartNav rover navigation

This paper describes theoretical and experimental results using the SmartNav rule-free fuzzy rover navigation system. SmartNav divides the terrain perceived by the rover into a number of circular sectors, and evaluates each sector using goal and safety preference factors to differentiate between preferred and unpreferred terrain sectors. The goal-preference factor is used to make sector evaluation based on the sector orientation relative to the designated goal position. The safety-preference factors are used to make sector evaluations on the basis of the sector local and regional terrain hazards. Three methods are developed to blend the three sector evaluations in order to find the effective preference factor for each sector. Two sector selection methods are then described in which the sector preference factors are used to find the heading command for the rover. The rover speed command is also computed based on the goal distance and safety-preference factor of the chosen sector. The above navigation steps are continuously repeated throughout the rover motion. Experimental results are presented to demonstrate the navigational capabilities of SmartNav using a commercial Pioneer 2AT rover traversing a simulated Martian terrain at the JPL Mini Mars Yard.

---

     

Magpie: Experiences in supporting Semantic Web browsing

Magpie has been one of the first truly effective approaches to bringing semantics into the web browsing experience. The key innovation brought by Magpie was the replacement of a manual annotation process by an automatically associated ontology-based semantic layer over web resources, which ensured added value at no cost for the user. Magpie also differs from older open hypermedia systems: its associations between entities in a web page and semantic concepts from an ontology enable link typing and subsequent interpretation of the resource. The semantic layer in Magpie also facilitates locating semantic services and making them available to the user, so that they can be manually activated by a user or opportunistically triggered when appropriate patterns are encountered during browsing. In this paper we track the evolution of Magpie as a technology for developing open and flexible Semantic Web applications. Magpie emerged from our research into user-accessible Semantic Web, and we use this viewpoint to assess the role of tools like Magpie in making semantic content useful for ordinary users. We see such tools as crucial in bootstrapping the Semantic Web through the automation of the knowledge generation process.     

惯性导航系统陀螺漂移补偿算法研究

分析了几种计算惯导系统导航陀螺漂移的方法，构思了一种组合导航系统模式，在水下即可完成对惯导的校正，对导航陀螺漂移进行补偿。同时还提出了对导航陀螺漂移补偿的优化组合算法。理论分析及计算机仿真结果均表明，应用该组合导航系统可大大提高潜艇的导航定位精度和隐蔽性。     

Supporting subject matter annotation using heterogeneous thesauri: A user study in Web data reuse

We performed a user experiment in which museum professionals used vocabularies from the Web for annotating the subject matter of museum objects. In this paper, we study the requirements on the underlying RDF dataset, search algorithms and user interface design in a real world setting. We identify the advantages of reusing vocabularies from the Web and discuss how and to what extent the disadvantages can be overcome. The study is performed at the Print Room of the Rijksmuseum Amsterdam, where currently a large collection of prints, photographs and drawings is being catalogued. We report on the analysis of the current practice of professional cataloguers, the iterative design of an annotation tool and a qualitative evaluation of this tool with a user experiment in a realistic annotation environment. We discuss our findings in terms of their impact on the RDF data, the semantic search functionality and the user interface.