Ibrar Shah

Semantic file annotation and retrieval on mobile devices

The rapid development of mobile technologies has facilitated users to generate and store files on mobile devices such as mobile phones and PDAs. However, it has become a challenging issue for users to efficiently and effectively search for files of interest in a mobile environment involving a large number of mobile nodes. This paper presents SemFARM framework which facilitates users to publish, annotate and retrieve files which are geographically distributed in a mobile network enabled by Bluetooth. The SemFARM framework is built on semantic web technologies in support of file retrieval on low-end mobile devices. A generic ontology is developed which defines a number of keywords, their possible domains and properties. Based on semantic reasoning, similarity degrees are computed to match user queries with published file descriptions. The SemFARM prototype is implemented using the Java mobile platform (J2ME). The performance of SemFARM is evaluated from a number of aspects in comparison with traditional mobile file systems and enhanced alternatives. Experimental results are encouraging showing the effectiveness of SemFARM in file retrieval. We can conclude that the use of semantic web technologies have facilitated file retrieval in mobile computing environments maximizing user satisfaction in searching for files of interest.

Selfish Flow Games in Non-cooperative Multi-radio Multi-channel Wireless Mesh Networks with Imperfect Information

Multi-Radio Multi-Channel capabilities in Wireless Mesh Networks can enormously increase backhaul connectivity, network throughput and fault tolerance as simultaneous transmissions can be achieved through multiple radios tuned to non-overlapping channels with minimum degree of interference. End user flows compete for channel resources along the end to end mesh backhaul path across multiple collision domains, which need high cooperation and trust. On the other hand, realistic mesh topologies span over different collision domains with a minimum degree of cooperation among the network users. This selfish behavior of end users degrades their individual fairness and affects the overall mesh backbone performance too. In this paper, we have proposed a novel multi-radio multi-channel game theoretic model in multiple collision domains, where flows of the network are considered as players of the game. Our analytical results show that Nash Equilibrium exists for such types of games and simulation results show that our distributed algorithm converges to a stable state in finite time with maximum fairness among the players.

Optimal Path Discovery with Mobility Management in Heterogeneous Mesh Networks

Wireless Mesh Networks (WMNs) is a promising technology for backhaul wireless connectivity in user premises due to its multi-hop nature, multi-radio multi-channel capabilities and stable power supplies. With proliferation of new and advanced access technologies, future WMN’s will bean integrated paradigm to provide seamless and ubiquitous connectivity to multi interface end user devices. Co-existence of multiple heterogeneous interfaces on wireless mesh routers increases overall network capacity, resilience and availability in the mesh backhaul as compared to homogenous radios mesh networks. In this paper, we present a novel architecture for heterogeneous WMN’s based on integrated IEEE 802.11/16/15technologies and discuss issues, possible solutions and future insight. We propose an optimal route algorithm along with radio assignment graph which captures the heterogeneity of radios. We also present a handover mechanism for seamless interface switch for mobile and static end user devices.

Performance Analysis of Proactive and Reactive Routing Protocols for Mobile Ad-hoc Grid in e-health Applications

The integration of mobile wireless devices into grids has recently drawn the attention of research community as this integration has resulted in new challenges. Mobile grid enables the mobility of a requesting user to share unused available resources on a network required in different applications in science, health and education. These handheld devices are not capable to cope with the existing demands of networks and applications. Heterogeneous interfaces, computational power, storage and display differences among these devices demands more research. In this paper we present analysis of different routing protocol’s behavior in a mobile ad-hoc grid environment, where best routing is the requirement of a grid application. These analyses were made based on a test scenario of e-health application in a mobile ad-hoc grid environment.

Growth Parameters for Films of Hydrothermally Synthesized One-Dimensional Nanocrystals of Zinc Oxide

Zinc oxide has been the focus of material research due to its potential applications in a variety of novel fields. The material exhibits anisotropic growth in the form of single crystal rods/wires of length in microns and thickness in several tens of nanometers through a facile and low temperature hydrothermal route wherein size, morphology, orientation, and growth rate are strongly dependent on a number of synthesis parameters. In this review article we intend to present/discuss the effects of important growth parameters of zinc oxide that have been reported in the literature. These parameters include concentration of the precursor solution, growth time, role of hexamine, synthesis temperature, pH of the precursor, and seeding layer deposited on a substrate.

Evaluation of linguistic similarity measurement techniques for ontology alignment

To bridge the semantic gap between different offered ontologies, Ontology Engineers have proposed and implemented various matching techniques during the last decade. Still, these techniques require more efforts and investigations to achieve better precision and recall for the set of alignments. The ontology alignment process consists of mainly three different stages; namely, String based, Linguistic based and Structure based. This paper presents the evaluation and analysis of various linguistic based ontology alignment techniques and their performance during the overall alignment process. For this purpose, we have included those linguistic matching tools which are widely used in the alignment systems whose performance is relatively better in terms of precision and recall during the tests conducted for Ontology Alignment Evaluation Initiative (OAEI). The results presented in this paper were obtained using benchmark ontologies used in OAEI conference. The results and analysis shows the significance of linguistic tools in the overall alignment process. The analysis presented in this paper can also be used as future guidelines for the research community who utilizes the linguistic matchers for finding the semantically equal entities from different ontologies.

Multi-Radio Multi-Channel assignment games in non-cooperative Wireless Mesh Networks with end user bargaining

Equipping routers in Wireless Mesh Networks with multiple radios tuned to multiple non-overlapping channels increases network connectivity and improves system throughput. On the other hand, selfish behavior of nodes during channel assignment can drastically decrease the network performance in a non-cooperative environment through protocol deviation. In this paper, we have addressed the problem of channel assignment to multiple radios in a multiple-collision domain Wireless Mesh Networks as a non-cooperative game. Analytical results show that Nash Equilibrium, which is not always social optimal due to multiple collision domains, exists under certain conditions. End users non-cooperative bargaining mechanism has been developed to increase the end-to-end achieved data rate of source nodes. Experimental results show that non-cooperative games with bargaining always perform better than Nash Equilibrium.