Abstract One aim of the semantic web is to build large knowledge bases distributed over the internet. Knowledge management systems that gather, merge and make available the information physically stored in multiple locations suffer from consistency and data fragmentation issues due to node failures. In this paper we address such problems and we present an architecture for managing reliable SPARQL queries... One aim of the semantic web is to build large knowledge bases distributed over the internet. Knowledge management systems that gather, merge and make available the information physically stored in multiple locations suffer from consistency and data fragmentation issues due to node failures. In this paper we address such problems and we present an architecture for managing reliable SPARQL queries with consistent results over a P2P-shared RDF storage. The RDF-storage is composed of peer nodes organized in a ring topology based on a Distributed Hash Table (DHT) where each node provides an entry point that enables clients outside the network to query the knowledge base using atomic, disjunctive, and conjunctive SPARQL queries. The consistency of the results is increased using a data redundancy algorithm that replicates each RDF triple in multiple nodes so that, in the case of peer failure, other peers can retrieve the data needed to solve the queries. Additionally a load distribution algorithm is used to maintain a uniform distribution of the data among the participating peers by dynamically changing the key space assigned to each node in the DHT. The performance of this approach is then evaluated by monitoring the effectiveness of the load balancing and redundancy algorithm and the overhead introduced on the network load in both a static (only join events) and a dynamic scenario. Read More Read Less

Abstract This paper describes and evaluates an intelligent wheelchair, adapted for severely disabled persons with mobility impairement. The wheelchair concept is an assistive device that allows the user to select arbitrary local destinations through a tactile screen interface. The device incorporates an automatic navigation system based on a vision system and knowledge base that drives the wheelchair, avoiding obstacles even in... This paper describes and evaluates an intelligent wheelchair, adapted for severely disabled persons with mobility impairement. The wheelchair concept is an assistive device that allows the user to select arbitrary local destinations through a tactile screen interface. The device incorporates an automatic navigation system based on a vision system and knowledge base that drives the wheelchair, avoiding obstacles even in unknown and dynamic scenarios, providing the disabled person with a high degree of autonomy, independent from a particular environment, i.e., not restricted to predefined conditions. In this paper a system is proposed to enable an efficient use of the knowledge base for the perception and navigation of the environment. To support this task, a vision system has been developed in parallel with other sensors. The architecture of the vision system is basically modular to enable a flexible transfer of data between the different modules, and makes any further modification possible and easy. The execution of the different tasks is coordinated by the central module called the supervisor which triggers each module at the appropriate time in order to control the behavior of the wheelchair. One of the most important module in the system is the knowledge base module which uses the acquired and predicted data to construct a scene model. This model is the main interpretation of th environment, since it reflects the perception and prediction processes necessary to a robust and secure navigation. The results indicated that this robotic wheelchair effectively provided mobility and autonomy to the target population. Read More Read Less

Abstract Existing intrusion detection techniques emphasize on building intrusion detection model based on all features provided. But not all the features are relevant ones and some of them are redundant and useless. This paper proposes and investigates identification of effective network features for Probing attack detection using PCA method to determine an optimal feature set. An appropriate feature set helps to... Existing intrusion detection techniques emphasize on building intrusion detection model based on all features provided. But not all the features are relevant ones and some of them are redundant and useless. This paper proposes and investigates identification of effective network features for Probing attack detection using PCA method to determine an optimal feature set. An appropriate feature set helps to build efficient decision model as well as a reduced feature set. Feature reduction will speed up the training and the testing process considerably. This paper proposes a strategy to focus on intrusion detection involving statistical analysis of both attack and normal traffics based on the DARPA 1998 dataset as the training data. DARPA 1998 dataset was also used in the experiments as the test data. Experimental results show a reduction in training and testing time while maintaining the detection accuracy within acceptable range. Read More Read Less

Abstract This paper discusses and evaluates the design and the implementation of a Community-centric Mobile Service Environment (COMSE), where all services are developed with Web technologies. The service environment is built on a distributed communication platform that is implemented using a DHT-based peer-to-peer (P2P) protocol. The interaction between P2P overlay networks and Web-based services is realised with a mobile middleware component... This paper discusses and evaluates the design and the implementation of a Community-centric Mobile Service Environment (COMSE), where all services are developed with Web technologies. The service environment is built on a distributed communication platform that is implemented using a DHT-based peer-to-peer (P2P) protocol. The interaction between P2P overlay networks and Web-based services is realised with a mobile middleware component called P2P Daemon. By using P2P Daemon as a gateway, Web-based services are able to utilise P2P overlay networks for community management, service publishing and discovery, as well as data storage. This case study highlights the opportunities of using P2P and Web technologies collaboratively in mobile settings. Special focus is on technical evaluation of the COMSE with two pilot services that were tested by genuine users in a real usage environment. As performance criteria, we used nodes’ messaging load, success ratio of P2P operations, and latencies of successful P2P operations. The evaluation results show that it is technically feasible for mobile nodes to use Web-based services in community-centric P2P overlay networks. Our findings suggest that the load inflicted on mobile nodes for maintaining small-sized P2P overlay networks is at an acceptable level, since the mobile nodes are able to stay online up to 8 hours before running out of battery. Read More Read Less

Abstract Agile processes can be applied to any software process for effective response to changing requirements during the development process and effective communication among stakeholders. There is lack of surveys related to agile processes in large web development enterprises in the world and the current state of adoption of agile processes by large enterprises is still unknown. A survey has been... Agile processes can be applied to any software process for effective response to changing requirements during the development process and effective communication among stakeholders. There is lack of surveys related to agile processes in large web development enterprises in the world and the current state of adoption of agile processes by large enterprises is still unknown. A survey has been conducted in this research based on questionnaire and interviews in five large Jordanian enterprises to examine the process models adopted by these enterprises, the extent to which these enterprises are using agile processes, and finally to examine the problems associated with large web applications’ development. The results of this survey showed that there is a weakness in adoption of agile processes in large Jordanian enterprises and the Extreme Programming (XP) is well known agile process by the developers working in these enterprises. According to survey results, we suggested recommendations related to adoption of XP agile process in large enterprises. Read More Read Less