Stephen J. H. Yang

An optimal QoS-based Web service selection scheme

Quality-of-service (QoS) in Web services encompasses various non-functional issues such as performance, dependability and security, etc. As more and more Web services become available, QoS capability is becoming a decisive factor to distinguishing services. This study proposes an efficient service selection scheme to help service requesters select services by considering two different contexts: single QoS-based service discovery and QoS-based optimization of service composition. Based on QoS measurement metrics, this study proposes multiple criteria decision making and integer programming approaches to select the optimal service. Experimental results show that the scheme is not only efficient, but also works well for complicated scenarios.

A social network-based system for supporting interactive collaboration in knowledge sharing over peer-to-peer network

Knowledge sharing enables people in virtual communities to access relevant knowledge (explicit or tacit) from broader scope of resources. The performance in such environments is fundamentally based on how effectively the explicit and tacit knowledge can be shared across people, and how efficiently the created knowledge can be organized and disseminated to enrich digital content. This study will address how to apply social network-based system to support interactive collaboration in knowledge sharing over peer-to-peer networks. Results of this study demonstrate that applying such social network-based collaboration support to knowledge sharing helps people find relevant content and knowledgeable collaborators who are willing to share their knowledge.

Learning styles and cognitive traits - Their relationship and its benefits in web-based educational systems

Different learners have different needs; they differ, for example, in their learning goals, their prior knowledge, their learning styles, and their cognitive abilities. Adaptive web-based educational systems aim to cater individual learners by customizing courses to suit their needs. In this paper, we investigate the benefits of incorporating learning styles and cognitive traits in web-based educational systems. Adaptivity aspects based on cognitive traits and learning styles enrich each other, enabling systems to provide learners with courses which fit their needs more accurately. Furthermore, consideration of learning styles and cognitive traits can contribute to more accurate student modelling. In this paper, the relationship between learning styles, in particular the Felder-Silverman learning style model (FSLSM), and working memory capacity, a cognitive trait, is investigated. For adaptive educational systems that consider either only learning styles or only cognitive traits, the additional information can be used to provide more holistic adaptivity. For systems that already incorporate both learning styles and cognitive traits, the relationship can be used to improve the detection process of both by including the additional information of learning style into the detection process of cognitive traits and vice versa. This leads to a more reliable student model.

Ubiquitous Provision of Context Aware Web Services

Context-aware Web service is an interactive model between the context of service requesters and the services in Web-enabled environments. We envision that providing context-aware services is the first step toward ubiquitous Web services to enhance current Web-based e-business by finding right business partners, right business information, and right business services in the right place at the right time. The major contributions of this paper are the development of our context model and context aware service oriented architecture (CA-SOA). We have developed a context model to formally describe and acquire contextual information pertaining to the service requesters and services. Based on the model, we have constructed CA-SOA for ubiquitous Web service discovery and access based on service and requesters surrounding context

Fuzzy rule base systems verification using high-level Petri nets

In this paper, we propose a Petri nets formalism for the verification of rule-based systems. Typical structural errors in a rule-based system are redundancy, inconsistency, incompleteness, and circularity. Since our verification is based on Petri nets and their incidence matrix, we need to transform rules into a Petri nets first, then derive an incidence matrix from the net. In order to let fuzzy rule-based systems detect above the structural errors, we are presenting a Petri-nets-based mechanism. This mechanism consists of three phases: rule normalization, rules transformation, and rule verification. Rules will be first normalized into Horn clauses, then transform the normalized rules into a high-level Petri net, and finally we verify these normalized rules. In addition, we are presenting our approach to simulate the truth conditions which still hold after a transition firing and negation in Petri nets for rule base modeling. In this paper, we refer to fuzzy rules as the rules with certainty factors, the degree of truth is computed in an algebraic form based on state equation which can be implemented in matrix computation in Petri nets. Therefore, the fuzzy reasoning problems can be transformed as the liner equation problems that can be solved in parallel. We have implemented a Petri nets tool to realize the mechanism presented fuzzy rules in this paper.

Ubiquitous Provision of Context-Aware Web Services

Providing context-aware Web services refers to an adaptive process of delivering contextually matched Web services to meet service requesters’ needs at the moment. This article presents an ontology-based context model that enables formal description and acquisition of contextual information pertaining to both service requesters and services. The context model is supported by context query and phased acquisition techniques. We also report two context-aware Web services built on top of our context model to demonstrate how the model can be used to facilitate Web services discovery and Web content adaptation. Implementation details of the context elicitation system and the evaluation results of context-aware services provision are also reported.

Modeling imprecise requirements with fuzzy objects

Abstract One of the foci of the recent development in object-oriented modeling (OOM) has been the extension of OOM to fuzzy logic to capture and analyze informal requirements that are imprecise in nature. In this paper, a new approach to object-oriented modeling based on fuzzy logic is proposed to formulate imprecise requirements along four dimensions: (1) to extend a class by grouping objects with similar properties into a fuzzy class, (2) to encapsulate fuzzy rules in a fuzzy class to describe the relationship between attributes, (3) to evaluate the membership function of a fuzzy class by considering both static and dynamic properties, and (4) to model uncertain fuzzy associations between classes. The proposed approach is illustrated using the problem domain of a meeting scheduler system.

Composition and evaluation of trustworthy web services

Web service technology seamlessly enables integration of different software to fulfil dynamic business demands in a platform-neutral fashion. By means of standard interfaces, service requesters can obtain their desired functionalities through certain service discovery mechanism, and service providers can offer the functionality to service requesters without exposing details of provided services. However, the adoption of loosely coupled and distributed services will cause trustworthiness problems. In this paper, we use ontology to describe experience and we utilise statistical techniques along with Petri nets to conduct a trustworthy evaluation method for composite web services. The degree of trustworthiness of all involved services in an aggregated composite service will be evaluated by analysing past experiences so that the trustworthiness of the composite service could be estimated.

A Framework of Three Learning Activity Levels for Enhancing the Usability and Feasibility of Wireless Learning Environments.

The most recent advances in information technology have brought wireless communication and mobile devices to education. The wireless technology enhanced classroom (WiTEC) integrates a wireless local area network, mobile learning devices, and client-server architecture to support instruction and learning activities. This article introduces a framework that involves three learning activity levels—learning functions, learning episodes, and learning flows—as a basis for designing an integrated system that supports various types of learning activities in WiTEC. A teacher can use this system to generate new learning flows before class and to implement them during class. A two-stage evaluation was conducted in three 6th grade classes to investigate the usability and feasibility of the proposed system. The participating teachers indicated that the use of the three learning activity levels eased the burden of preparing, implementing and reviewing instruction and learning activities.

Universal Access and Content Adaptation in Mobile Learning

Universal access is known as the concept of facilitating accesses to the desired data according to the varying capabilities and characteristics of users [1]. Universal access aims to be capable of recognizing and responding to the presence of different context in a seamless, unobtrusive and often invisible way. To achieve this goal, two important issues need to be solved, they are context awareness and content adaptation. In this paper, context is referred to as contextual information that can be used to characterize the situation of an entity where an entity can be a person, a place, a physical or computational object [2]. The contextual information can be where and when the users are (time and space), as well as what the content are available nearby, and etc.