自适应超媒体系统探析

1.引言二十年来,超媒体已从实验原型发展成为世界上最流行的计算机应用,其中最成功的超媒体系统World Wide Web几乎成为信息高速公路的代名词。随着超媒体系统的类型、规模及复杂性的与日俱增,信息空间日益宠大,如何快速准确地展示用户所需信息成为当前研究的热点。传统的超媒体系统中采用一成不变(one-size-fits-all)的方法提供静态超媒体文档,要求超媒体文档的作者为不同用户撰写不同文档,以适应     

Hypermedia systems without links

Although there is no universally accepted definition of what a hypermedia system really is, most hypermedia specialists seem to agree on one basic issue. A hypermedia system contains some pieces of information (often called nodes or chunks) that are tied together by links. Links in fact have almost become a defining characteristic of hypermedia.In this paper we contend that the importance of links has been grossly exaggerated. Hypermedia systems in which links play only a limited role are quite conceivable. Indeed, many burning issues in current day hypermedia systems can be better resolved if other navigational techniques are used. We believe that the emphasis on links has caused a rather myopic view of hypermedia systems. A serious re-evaluation of the extent to which links are beneficial is important. This fact has been previously observed by others, the earliest being Van Dam's keynote address at 'Hypertext'87'. In this paper we propose a first significant step in using structure to replace links.     

Hypermedia systems development practices: a survey

Merely calling a system "Web-based" doesn't necessarily imply that its software design differs much from that of a traditional system. When Web-based systems assume hypermedia functionality they become substantively different from a design perspective. Hypermedia technologies support much richer user interfaces, more complex navigation mechanisms, and more varied forms of information than traditional computer systems. In recent years, hypermedia systems (particularly Web-based ones) have grown in complexity and scope as they've begun to involve critical organizational activities such as customer support, sales and marketing, and technical support.     

Using hypermedia in computer-aided instruction

The previous article in this issue (see ibid., 1996) described the Discover distributed interactive visualization system, which has been running at National Cheng-Kung University Hospital since 1993. Shortly after Discover was implemented, we observed that physicians were having trouble understanding and navigating through Discover processes for image analysis and generation. To address this problem, we developed a computer aided instruction mechanism based on hypermedia technology-multimedia with hypertext navigation. Hints (Hypermedia Information Network System) is built around the concept of hypercontrol-the use of a multimedia document to control hardware or software systems. It is currently being used with Discover at the university hospital. Physicians use this hypermedia network system to learn the processes of the discover visualization system and to help them standardize the way they examine images     

Navigation in hypermedia learning systems: experts vs. novices

With the advancement of Web technology, hypermedia learning systems are becoming more widespread in educational settings. Hypermedia learning systems present course content with non-sequential formats, so students are required to develop learning paths by themselves. Yet, empirical evidence indicates that not all students can benefit from hypermedia learning. Research into individual differences suggests that prior knowledge has significant effects on student learning in hypermedia systems, with experts and novices showing different preferences to the use of hypermedia learning systems and requiring different levels of navigation support. It is therefore essential to develop a mechanism to help designers understand the needs of experts and novices. To address this issue, this paper presents a framework to illustrate the needs of students with different levels of prior knowledge by analyzing the findings of previous research. The overall aim of this framework is to integrate students’ prior knowledge into the design of hypermedia learning systems. Finally, implications for the design of hypermedia learning systems are discussed.     

Hypermedia use by the Disadvantaged: Assessing a Health Information Program

Hypermedia, as an audiovisual tool that users can tailor to meet their individual information needs, has considerable potential for communicating about complex topics to naive users — including the educationally and economically disadvantaged. This study evaluates the ability of low-income, ethnically-diverse persons to successfully navigate a hypermedia health information program designed for their use. This study, using protocol analyses, detailed content analysis of videotapes, and questionnaire data from 32 African-American, Hispanic, Native American, and Anglo low-income women, found very positive overall user reactions to the program's understandability and case of use and identifies characteristic navigation patterns and some problems that these persons have in using such a hypermedia program. Some minor differences in responses and characteristic problems due to age, ethnicity, and education level were also found. The authors suggest guidelines for the development of such computer-based interactive programs for use by disadvantaged populations and other lay or naive adult users.

Adapting hypermedia for use by less sophisticated users poses special problems and offers special opportunities. Hypermedia use by disadvantaged persons is of particular interest in two respects: educationally and culturally disadvantaged persons provide a demanding benchmark for programs designed for lay users, and hypermedia itself may be better-suited than some traditional communication modalities for imparting information to the disadvantaged.     

基于结构特性的超媒体模型

将超媒体的结构特性与形式语言学理论相结合,提供了一种有效地分析超媒体动态结构的特性的方法,该方法将超毁体组件集合映射为语言中的抽象符号集合,组件集合之上的链映射为语言中建立单词的方法,超媒体的结构化机械制映射为语言中的抽象符号集号,组件集合之上的链映射为语言中建立单词的方法,超媒体的结构化机制映射为语言中描述单词集合构造机制的语法,超媒体模拟为转换机,“链引导”动作模拟为“匹配对”序列,“链引导”的计算结果产生与上下文无关文法相对应的虚拟文档,从而为进一步研究超媒体的浏鉴语义及其它动态特性提供了理论基础。     

Towards A New Authoring Methodology for Large-Scale Hypermedia Applications

As the amount of information technology increases, managing information resources, so that the correct people can find the information easily, becomes a critical issue. Hypermedia systems are considered one solution to this problem as they provide a means for representing higher level relationships between the underlying information. However, the amount of information available electronically is increasing at an accelerated rate. Using standard hypermedia authoring techniques, the effort required managing and maintaining large-scale hypermedia systems is enormous. Hypermedia authoring in the large requires new methodologies if it is going to be feasible.This paper presents a new model for building and structuring large-scale hypermedia applications. It describes a case study that explored the delivery of hypermedia information in an industrial environment on a small scale. Models and techniques developed for that case study were then refined and augmented so they could support the construction of large-scale hypermedia systems. In order to support such endeavors a new linking model is presented that allows the author to explicitly represent abstract concepts contained within the underlying information and interconnect them in some meaningful manner. A prototype system applying this linking technique is presented.     

Expert system for IE student advisement

Student advising is a key function within an academic environment. An expert system may be used as a first line of response to students' advising needs. The system currently under development, uses hypermedia as the interface between user and hidden expert system routines. Hypermedia allows use of user oriented facilities (icon driven menus, branching following user requests, digitized photographs, video discs, animation, etc). The software architecture chosen is that of a hypergraph with embedded, distributed expert systems.     

Software process modeling languages: A systematic literature review

ContextOrganizations working in software development are aware that processes are very important assets as well as they are very conscious of the need to deploy well-defined processes with the goal of improving software product development and, particularly, quality. Software process modeling languages are an important support for describing and managing software processes in software-intensive organizations.ObjectiveThis paper seeks to identify what software process modeling languages have been defined in last decade, the relationships and dependencies among them and, starting from the current state, to define directions for future research.MethodA systematic literature review was developed. 1929 papers were retrieved by a manual search in 9 databases and 46 primary studies were finally included.ResultsSince 2000 more than 40 languages have been first reported, each of which with a concrete purpose. We show that different base technologies have been used to define software process modeling languages. We provide a scheme where each language is registered together with the year it was created, the base technology used to define it and whether it is considered a starting point for later languages. This scheme is used to illustrate the trend in software process modeling languages. Finally, we present directions for future research.ConclusionThis review presents the different software process modeling languages that have been developed in the last ten years, showing the relevant fact that model-based SPMLs (Software Process Modeling Languages) are being considered as a current trend. Each one of these languages has been designed with a particular motivation, to solve problems which had been detected. However, there are still several problems to face, which have become evident in this review. This let us provide researchers with some guidelines for future research on this topic.     

Modeling the dynamic behavior of hypermedia applications

Hypermedia applications can be defined as collections of interactive and multimedia documents that are organized as a hypertext net. The development of hypermedia applications poses specific problems, such as the need for modeling sophisticated navigational structures, interactive behaviors, and harmonic presentations involving the synchronization of contents. Moreover, the increasing popularity of Internet based systems has put stress on the lack of mechanisms to formally specify security policies when designing hypermedia applications. Traditional design models and methodologies are not suitable for hypermedia applications and the up-to-now developed hypermedia oriented models do not cover the whole set of design needs. In this context, we present Labyrinth, a hypermedia oriented model providing formal elements to describe the static structure and dynamic behavior of this kind of nonlinear, multisensory, and interactive applications     

Stackmaker: An Environment for Creating Hypermedia Learning Material

Hypermedia has for some time now been proposed as an adjunct to printed material within the educational process. However, creating a highly interconnected hypermedia network is complex and time consuming, with overviews of the content and structure of the information seemingly essential in order to avoid the disorientation and cognitive overload problems often described.

This paper describes an environment designed to remove much of the burden of creating such support facilities, allowing the teacher to concentrate on the content and structure of the information presented.     

Modelling hypermedia and web applications: the Ariadne Development Method

The development process of hypermedia and web systems poses very specific problems that do not appear in other software applications, such as the need for mechanisms to model sophisticated navigational structures, interactive behaviors, interfaces with external applications, security constraints and multimedia compositions. Even though experience, modelling skills and abstractions can be borrowed from existing software design methods, such as object-oriented modelling, hypermedia developers need specific mechanisms to analyze and design using entities that belong to the hypermedia domain (such as nodes, links, anchors and space and time-based relationships). Moreover, hypermedia methods should provide mechanisms to deal with all the aforementioned features in a progressive and integrated way. In this paper, we present the Ariadne Development Method (ADM), a software engineering method that proposes a systematic, flexible, integrative and platform-independent process to specify and evaluate hypermedia and web applications. ADM has been shown particularly useful in complex systems involving a huge number of users with different abilities to access information, with a complex structure where a huge number of nodes have to be organized in a clear way to produce specifications that are discussed by people with an heterogeneous background. This is the case of ARCE, a Latin American project where 21 countries are cooperating to produce a web platform to improve assistance in disaster mitigation situations.     

CAI中的智能超媒体技术研究

将智能化行为引入到超媒体系统中,在超媒体的链和结点中嵌入知识或规则,允许链进行计算和推理,使链具有动态跟踪与动态引导功能,使得媒体信息具有更丰富的表现特性,这是智能超媒体的主要研究的内容。文章探讨了智能超媒体的相关实现技术,建立了ＣＡＩ领域的相关知识与推理模型,设计与实现了网上多媒体ＣＡＩ系统中的智能超媒体功能。     

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.     

软件恢复技术研究

1.问题的提出——软件衰老 1.1 软件衰老概念在最近的很多研究中讨论了“软件衰老”现象。软件衰老是指伴随着软件的运行,系统资源逐渐耗尽或运行错误逐渐积累所导致的系统性能持续下降乃至挂起停机的现象。软件衰老现象是软件可靠性的大敌,有着非常严重的危害作用,在普通的计算中,它可能影响到结果的获取和效率,在战争和国防中,其危害就难以估量了。在文[16]中记述了在海湾战争时,美军正是因为“爱国者”导弹拦截控制系统中的一个软件衰老问题,对伊拉克“飞毛腿”导弹的拦截判断出错,致死美军     

基于Petri网超媒体模型的分析与比较

超媒体建模研究是当前一个重要研究方向。基于Petri网理论的模型是对有向图模型的改进,与其他模型比较,能够更好地刻画超媒体系统。原因如下:Petri网是一个二部有向图,适合于说明超媒体的链接机制;Petri网是一种天然的具有并行执行语义的自动机,模型可以自然地表达超媒体系统中的动态执行语义;Petri网能够说明各种顺序、并发和同步活动,满足描述多媒体表现的需要;利用Petri网的图形特性和严格的数学基础,人们可以检查和分析超媒体中的潜在问题。该文着重对四个典型的基于Petri网的超媒体模型:MHPN、HCPN、MORENA和HTSPN模型进行分析和比较。     

Interactive hypermedia applications: A model and its implementation

By referring to the object-oriented efforts of the Multimedia and Hypermedia information coding Expert Group (MHEG), and the augmented Petri net model, we present a formal definition of the multimedia hypermedia Petri net (MHPN) model. Through this proposed model, issues of authoring, rendering and synchronization of multimedia information (i.e. structure authoring, spatial temporal relationships, user interaction, etc.) can all be laid to rest. We have implemented a testbed system, the Petri net object information system (POIS), which offers considerable potential for the development of distributed hypermedia applications. The testbed has been implemented on an IBM-PC486 under Windows 3.1. We are now in the process of porting the testbed model to Windows NT.     

基于Agent模型的开放超媒体个性化

该文提出了基于Agent模型所实现的开放超媒体个性化,利用分布对象技术实现Agent机制,并定义了多Agent之间通信的语义。利用这种Agent机制实现了开放超媒体个性化的开发框架,可实现各种个性化行为,以解决现有超媒体存在的问题。     

超媒体系统中的人工智能方法

一、什么是超媒体近年来迅速崛起的多媒体(multimedia)技术,是一种使计算机具有交互式地综合处理和管理文字、图形、图象、声音、视频等多种媒体能力的技术,必将使计算机技术发生一