The Computer Journal - current issue

Combining Theory and Systems Building in Pervasive Computing

Hu, B., Hu, B., Callaghan, V., Lin, Z. — Tue, 02 Feb 2010 07:40:03 PST

Implementation of Learning Path in Process Control Model

Luo, J., Kong, W., Ge, L. — Tue, 02 Feb 2010 07:40:03 PST

Few e-Learning systems in pervasive environments take learning activities as a part of the learning process and give much flexibility to instructors to define a structural course which is helpful for students to navigate distributed learning resources. In this paper, we propose a process control model in Web-based e-Learning, and illustrate how to implement process control through learning path with workflow technology. This model improves the learning efficiency by providing instructors tools to design courses with learning paths and select the popular learning objects. It also enables students to achieve an orderly learning experience through defined learning path.

Detection Of Normal and Novel Behaviours In Ubiquitous Domestic Environments

Rivera-illingworth, F., Callaghan, V., Hagras, H. — Tue, 02 Feb 2010 07:40:03 PST

The importance of ubiquitous environments has increased in recent years as it has been recognized as a paradigm that can improve the quality of life of many sectors of the population especially care of elderly people by providing automated environments that adapt and respond to its inhabitants' needs. The aim of the work presented here is to provide a solution to the problem of recognition and detection of human behaviours inside ubiquitous environments by using a neural-network driven embedded agent working with online, real-time data from a network of unobtrusive low-level sensors. The final objective of this system was to classify a ‘normal’ pattern of activities, and sense deviations from it, which could be employed for home care applications.

A Policy-Driven Service Composition Method for Adaptation in Pervasive Computing Environment

Zhang, B., Shi, Y., Xiao, X. — Tue, 02 Feb 2010 07:40:03 PST

Service composition allows distributed application, such as multimedia application, to be composed from atomic service units and to adapt dynamically to users' requirements and environment conditions in pervasive computing system. It augments the adaptation action space for the application of pervasive computing. According to the multidimensional QoS (Quality of Service) requirement of pervasive computing system, we proposed a comprehensive service composition method to enhance the capability of application adaptation. First, according to a hierarchy policy model and a policy specification language, strengthened by event calculus, service discovery policy action integrating the situation of user, application, environment and resource can be triggered. Secondly, the proposed physical space model can support the location-aware service discovery and explicit range query to improve the efficiency of the query. To the end, an adaptation policy evaluation model is utilized to maximize an evaluation criterion–quality of satisfaction of users and environment by optimizing the optional service selection and the composition path. Through experiment and discussion of the algorithm, the paper further illustrates the great potential advantage of the solution to service composition.

Ant-based Energy-aware Disjoint Multipath Routing Algorithm for MANETs

Wu, Z.-Y., Song, H.-T. — Tue, 02 Feb 2010 07:40:03 PST

Ant-based routing protocols for mobile ad hoc networks (MANETs) have been widely explored, but most of them are essentially single-path routing methods that tend to impose a heavy burden on the hosts along the shortest path from source to destination. In this paper, we combine swarm intelligence and node-disjoint multipath routing to alleviate these problems. A novel approach called ant-based energy-aware disjoint multipath routing algorithm (AEADMRA) is proposed. AEADMRA is based on swarm intelligence and especially on the ant colony-based meta heuristic. AEADMRA can discover multiple energy-aware node-disjoint routing paths with a low routing overhead. Simulation results indicate that the performance of AEADMRA outperforms other pertinent algorithms.

A Rule-based Method for Improving Adaptability in Pervasive Systems

Lin, J., Song, C., Wang, H. — Tue, 02 Feb 2010 07:40:03 PST

There are two types of dynamic elements in a pervasive system: the first is where a context varies with shifting environments, and the second is where variables are defined by the dynamic requirements of an application. This makes improving adaptability to dynamic change an important topic in pervasive systems research. Currently, most of the efforts targeting improvements in adaptability focus on context-related issues, other variables being simply encoded in the program directly. This ignores the dynamic complexity of a pervasive system, resulting in poor system adaptability. In this paper, we propose a rule-based method in which the two types of change are separated from the program code. The changes are then stored and processed by means of corresponding rules. In our new method when a change occurs, the system needs only to modify the rules rather than the program code. This makes a pervasive system more robust in its adaptability to dynamic change. Experiments and examples are provided to evaluate the feasibility of the proposed method.

Smart-Context: A Context Ontology for Pervasive Mobile Computing

Moore, P., Hu, B., Wan, J. — Tue, 02 Feb 2010 07:40:04 PST

This paper addresses context in intelligent context-aware systems to support personalised service provision and cooperative computing. Context processing, context modelling, ontology, and OWL are introduced and a context reasoning ontology presented. Context implementation reduces to a decision problem which is characterised as one of selecting from a number of potential options based on the relationship between the values that describe the input and the solution, the modelling school of decision analysis attempts to construct an explicit model of such relationships, usually in the form of decision trees. An overview of decision trees with parametric design considerations is presented. Comparisons with related research are drawn and an evaluation and simulation of Smart-Context is presented. RDF/S with OWL and Jena provide an effective basis for autonomous decision making using processing rules, and the issue is one of implementation in adaptable and tractable solutions. A conclusion with open research questions is presented with consideration of potential directions for future research.

Modelling Bidders in Sequential Automated Auctions

Velan, K. — Tue, 02 Feb 2010 07:40:04 PST

Auctions are mechanisms that formalize the rules with which automated trading schemes can be conducted, and in this paper we model the interaction of bidder and seller agents in sequential computerized auctions. We study the outcome of strategies that a designated ‘special bidder’ (SB) may follow in the presence of a collection of other bidders in an English auction, under the assumption that the SB can make bids based on its observation of the ongoing auction as a collective system. In our model, bidding and sale events are continuous time random processes with discrete state-space, where the state-space represents the current value of the most recent bid. We obtain analytical solutions that allow the evaluation of measures of interest to the SB such as the probability of winning, the savings with respect to the maximum payable price in the event of a win and the expected waiting time to win. We examine the effects of the SB's time to bid, and study how its decisions may be selected so as to optimize the SB's measures of interest.

A Simulation Model Supporting Time and Non-time Metrics for Web Service Composition

Wu, Z., Xiong, N., Park, J. H., Kim, T.-H., Yuan, L. — Tue, 02 Feb 2010 07:40:04 PST

A next generation network (NGN) exploits advanced multiple broadband, quality of service (QoS)-enabled service technologies. The NGN is aimed at users and service-related functions, including web services. Recently, web service composition (WSC) has become a new approach for overcoming many difficult problems confronted by B2B e-commerce, inter-organization workflow management, enterprise application integration etc. Due to the uncertainty of the NGNs and various web services, the performance of the WSC cannot be ensured. How to model it and predict its performance becomes a difficult problem for WSC. In this paper, we propose a novel performance simulation model for WSC, called STPM⁺. The STPM⁺ model can support modeling and simulating the time and non-time QoS metrics. Based on the stochastic timed colored Petri net, the STPM⁺ model can simulate and predict multiple QoS metrics, such as cost, reliability, reputation and so on. To examine the validation of our STPM⁺ model, we have designed and realized a visual performance simulation tool, called VisualWSCPE. Based on VisualWSCPE, we have fulfilled some simulation experiments. The experiment results demonstrate the feasibility and efficiency of the STPM⁺ model.

Resource-Aware Multimedia Content Delivery: A Gambling Approach

Allani, M., Garbinato, B., Pedone, F. — Tue, 02 Feb 2010 07:40:04 PST

In this paper, we propose a resource-aware solution to achieving reliable and scalable stream diffusion in a probabilistic model, i.e. where communication links and processes are subject to message losses and crashes, respectively. Our solution is resource-aware in the sense that it limits the memory consumption, by strictly scoping the knowledge each process has about the system, and the bandwidth available to each process, by assigning a fixed quota of messages to each process. We describe our approach as gambling in the sense that it consists in accepting to give up on a few processes sometimes, in the hope of better serving all processes most of the time. That is, our solution deliberately takes the risk not to reach some processes in some executions, in order to reach every process in most executions. The underlying stream diffusion algorithm is based on a tree-construction technique that dynamically distributes the load of forwarding stream packets among processes, based on their respective available bandwidths. Simulations show that this approach pays off when compared to traditional gossiping, when the latter faces identical bandwidth constraints.