Analysis of asynchronous online discussion forums for collaborative learning

Online discussion forums are well suited for collaborative learning systems. Much of the currently available research indicates that effectively designed collaborative learning systems motivate and enhance learning experiences of the participants which in turn lead to enhanced learning outcomes. This paper develops taxonomy of the asynchronous online discussion forums with the aims of increasing the understanding and awareness of various types of asynchronous discussion forums. The taxonomy is framed by constructivist pedagogical principles of asynchronous online discussion forum. The key attributes of online discussions and the factors influencing the discussion forum&rsquo;s design are identified. The taxonomy will help increase the online course designers&rsquo; ability to design more effective learning experiences for student success and satisfaction. It will also help researchers to understand the various features of the asynchronous discussion forums. The article concludes with implications for pedagogy and suggestions for the direction of future theoretical and empirical research.<br /

Parallel I/O scheduling in the presence of data duplication on multiprogrammed cluster computing systems

The widespread adoption of cluster computing as a high performance computing platform has seen the growth of data intensive scientific, engineering and commercial applications such as digital libraries, climate modeling, computational chemistry, computational fluid dynamics and image repositories. However, I/O subsystem performance has not been keeping pace with processor and memory performance, and is fast becoming the dominant factor in overall system performance.&nbsp; Thus, parallel I/O has become a necessity in the face of performance improvements in other areas of computing systems. This paper addresses the problem of parallel I/O scheduling on cluster computing systems in the presence of data replication.&nbsp; We propose two new I/O scheduling algorithms and evaluate the relative performance of the proposed policies against two existing approaches.&nbsp; Simulation results show that the proposed policies perform substantially better than the baseline policies.<br /

Enhancing RFID tag resistance against cloning attack

In its current form, RFID system are susceptible to a range of malevolent attacks. With the rich business intelligence that RFID infrastructure could possibly carry, security is of paramount importance. In this paper, we formalise various threat models due tag cloning on the RFID system. We also present a simple but efficient and cost effect technique that strengthens the resistance of RFID tags to cloning attacks. Our techniques can even strengthen tags against cloning in environments with untrusted reading devices.<br /

Determining service trustworthiness in inter loud computing environments

Deployment of applications and scientific workflows that require resources from multiple distributed platforms are fuelling the federation of autonomous clouds to create cyber infrastructure environments. As the scope of federated cloud computing enlarges to ubiquitous and pervasive computing, there will be a need to assess and maintain the trustworthiness of the cloud computing entities. In this paper, we present a fully distributed framework that enable interested parties determine the trustworthiness of federated cloud computing entities.<br /

An authorization policy management framework for dynamic medical data sharing

In this paper, we propose a novel feature reduction approach to group words hierarchically into clusters which can then be used as new features for document classification. Initially, each word constitutes a cluster. We calculate the mutual confidence between any two different words. The pair of clusters containing the two words with the highest mutual confidence are combined into a new cluster. This process of merging is iterated until all the mutual confidences between the un-processed pair of words are smaller than a predefined threshold or only one cluster exists. In this way, a hierarchy of word clusters is obtained. The user can decide the clusters, from a certain level, to be used as new features for document classification. Experimental results have shown that our method can perform better than other methods.<br /

An online credential management service for InterGrid computing

Grid users and their jobs need credentials to access grid resources and services. It is important to minimize the exposure of credentials to adversaries. A practical solution is needed that works with existing software and is easy to deploy, administer, and maintain. Thus, credential management services are the wave of the future for virtual organizations such as Grid computing. This paper describes architecture of a scalable, secure and reliable on-line credential management service called SafeBox for InterGrid computing platform. SafeBox provides InterGrid users with secure mechanism for storing one or multiple credentials and access them based on need at anytime from anywhere.<br /

Energy-Efficient Management of Data Center Resources for Cloud Computing: A Vision, Architectural Elements, and Open Challenges

Cloud computing is offering utility-oriented IT services to users worldwide. Based on a pay-as-you-go model, it enables hosting of pervasive applications from consumer, scientific, and business domains. However, data centers hosting Cloud applications consume huge amounts of energy, contributing to high operational costs and carbon footprints to the environment. Therefore, we need Green Cloud computing solutions that can not only save energy for the environment but also reduce operational costs. This paper presents vision, challenges, and architectural elements for energy-efficient management of Cloud computing environments. We focus on the development of dynamic resource provisioning and allocation algorithms that consider the synergy between various data center infrastructures (i.e., the hardware, power units, cooling and software), and holistically work to boost data center energy efficiency and performance. In particular, this paper proposes (a) architectural principles for energy-efficient management of Clouds; (b) energy-efficient resource allocation policies and scheduling algorithms considering quality-of-service expectations, and devices power usage characteristics; and (c) a novel software technology for energy-efficient management of Clouds. We have validated our approach by conducting a set of rigorous performance evaluation study using the CloudSim toolkit. The results demonstrate that Cloud computing model has immense potential as it offers significant performance gains as regards to response time and cost saving under dynamic workload scenarios.Comment: 12 pages, 5 figures,Proceedings of the 2010 International Conference on Parallel and Distributed Processing Techniques and Applications (PDPTA 2010), Las Vegas, USA, July 12-15, 201

Performance of smart antennas with receive diversity in wireless sensor networks

In this paper we propose a Geometrically Based Single Bounce Elliptical Model (GBSBEM) for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. The system model assumes a cluster based wireless sensor network (WSN) which collects information from the sensors, filters and modulates the data and transmit it through a wireless channel to be collected at the receiver. We first develop a GBSBE model and based on this model we develop our channel model. Use of Smart antenna system at the receiver end, which exploits various receive diversity combining techniques like Maximal Ratio Combining (MRC), Equal Gain Combining (EGC), and Selection Combining (SC), adds novelty to this system. The performance of these techniques have been proved through matlab simulations and further ahead based on different number of antenna elements present at the receiver array, we calculate the performance of our system in terms of bit-error-rate (BER). Based on the transmission power we quantify for the energy efficiency of our communication model.<br /

An approach to filtering RFID data streams

RFID is gaining significant thrust as the preferred choice of automatic identification and data collection system. However, there are various data processing and management problems such as missed readings and duplicate readings which hinder wide scale adoption of RFID systems. To this end we propose an approach that filters the captured data including both noise removal and duplicate elimination. Experimental results demonstrate that the proposed approach improves missed data restoration process when compared with the existing method.<br /

Analysis of networked RFID system reliability

The ability to uniquely identify individual objects is essential in many applications such as manufacturing, distribution logistics, access control, anti-counterfeiting and healthcare. Radio Frequency Identification (RFID) technology provides one solution for automatic identification of entities using radio waves. Although there is considerable potential in deploying RFID technology, reliability is a key challenge that requires careful attention for RFID to deliver its inherent benefits. In this paper, we highlight the reliability challenges in RFID technology and we analyze the reliability aspects of RFID technology and their major causes. We will also discuss techniques to improve the reliability of RFID systems.<br /