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41.
Smart card technology has evolved over the last few years following notable improvements in the underlying hardware and software platforms. Advanced smart card microprocessors, along with robust smart card operating systems and platforms, contribute towards a broader acceptance of the technology. These improvements have eliminated some of the traditional smart card security concerns. However, researchers and hackers are constantly looking for new issues and vulnerabilities. In this article we provide a brief overview of the main smart card attack categories and their corresponding countermeasures. We also provide examples of well-documented attacks on systems that use smart card technology (e.g. satellite TV, EMV, proximity identification) in an attempt to highlight the importance of the security of the overall system rather than just the smart card.  相似文献   
42.
In this paper, pair programming is empirically investigated from the perspective of developer personalities and temperaments and how they affect pair effectiveness. A controlled experiment was conducted to investigate the impact of developer personalities and temperaments on communication, pair performance and pair viability-collaboration. The experiment involved 70 undergraduate students and the objective was to compare pairs of heterogeneous developer personalities and temperaments with pairs of homogeneous personalities and temperaments, in terms of pair effectiveness. Pair effectiveness is expressed in terms of pair performance, measured by communication, velocity, design correctness and passed acceptance tests, and pair collaboration-viability measured by developers’ satisfaction, knowledge acquisition and participation. The results have shown that there is important difference between the two groups, indicating better communication, pair performance and pair collaboration-viability for the pairs with heterogeneous personalities and temperaments. In order to provide an objective assessment of the differences between the two groups of pairs, a number of statistical tests and stepwise Discriminant Analysis were used.
Ignatios DeligiannisEmail:

Panagiotis Sfetsos   is an Assistant Professor at the Department of Informatics at the Alexander Technological Educational Institute of Thessaloniki, Greece. He received his B.Sc. in Computer Science and Statistics from the University of Uppsala, Sweden (1981), and the Ph.D. degree in Computer Science from the Aristotle University of Thessaloniki (2007). His Ph.D. Thesis was on “Experimentation in Object Oriented Technology and Agile Methods”. His research interests include empirical software evaluation, measurement, testing, quality, agile methods and especially extreme programming. Ioannis G. Stamelos   is an Associate Professor of Computer Science at the Aristotle University of Thessaloniki, Dept. of Informatics. He received a degree in Electrical Engineering from the Polytechnic School of Thessaloniki (1983) and the Ph. D. degree in Computer Science from the Aristotle University of Thessaloniki (1988). He teaches object-oriented programming, software engineering, software project management and enterprise information systems at the graduate and postgraduate level. His research interests include empirical software evaluation and management, software education and open source software engineering. He is author of 90 scientific papers and member of the IEEE Computer Society. Lefteris Angelis   received his B.Sc. and Ph.D. degree in Mathematics from Aristotle University of Thessaloniki (A.U.Th.). He works currently as an Assistant Professor at the Department of Informatics of A.U.Th. His research interests involve statistical methods with applications in software engineering and information systems, computational methods in mathematics and statistics, planning of experiments and simulation techniques. Ignatios Deligiannis   is an Associate Professor at Alexander Technological Education Institute of Thessaloniki, Greece. His main interests are Object-Oriented software methods, and in particular design assessment and measurement. He received his B.Sc. in Computer Science from Lund University, Sweden, in 1979, and then worked for several years in software development at Siemens Telecommunications industry. He was member of ESERG (Empirical Software Engineering Research Group at Bournemouth University, UK). Currently, he is a research partner of Software Engineering Group::Plase laboratory, Aristotle University of Thessaloniki, Greece.   相似文献   
43.
To address the two most critical issues in P2P file-sharing systems: efficient information discovery and authentic data acquisition, we propose a Gnutella-like file-sharing protocol termed Adaptive Gnutella Protocol (AGP) that not only improves the querying efficiency in a P2P network but also enhances the quality of search results at the same time. The reputation scheme in the proposed AGP evaluates the credibility of peers based on their contributions to P2P services and subsequently clusters nodes together according to their reputation and shared content, essentially transforming the P2P overlay network into a topology with collaborative and reputed nodes as its core. By detecting malicious peers as well as free-riders and eventually pushing them to the edge of the overlay network, our AGP propagates search queries mainly within the core of the topology, accelerating the information discovery process. Furthermore, the clustering of nodes based on authentic and similar content in our AGP also improves the quality of search results. We have implemented the AGP with the PeerSim simulation engine and conducted thorough experiments on diverse network topologies and various mixtures of honest/dishonest nodes to demonstrate improvements in topology transformation, query efficiency, and search quality by our AGP.
Alex DelisEmail:

Ioannis Pogkas   received his BS in Computer Science in 2007 and is currently pursuing postgraduate studies at the Department of Informatics and Telecommunications of the Univesrity of Athens. His research interests focus on search, reputation andtopology adaptation mechanisms in peer-to-peer networks. He is also interested in embedded and operating systems. Vassil Kriakov   received his B.S. and M.S. from Polytechnic University in 2001 and is now completing his doctoral studies at the Polytechnic Institute of New York University (NYU-Poly). His PhD research has been partially sponsored by a US Department of Education GAANN Graduate Fellowship. His research interests include distributed spatio-temporal data indexing, correlations in high-frequency data streams, and data management in grid and peer-to-peer networks. Zhongqiang Chen   is a senior software engineer at Yahoo! He holds a PhD in Computer Science and MS degrees in both Computer Science and Electrical Engineering all from Polytechnic University in Brooklyn, NY. He is a Computer Engineering MS and BS graduate of Tsinghua University, Beijing, P.R. China. He is interested in network security, information retrieval, and distributed computing and is the recipient of the 2004 Wilkes Award for outstanding paper contribution in The Computer Journal. Alex Delis   is a Professor of Computer Science at the University of Athens. He holds a PhD and an MS from the University of Maryland College Park as well as a Diploma in Computer Engineering from the University of Patras. His research interests are in distributed computing systems, networked information systems, databases and information security. He is a member of IEEE Computer Society, the ACM and the Technical Chamber of Greece.  相似文献   
44.
Designing controllers with diagnostic capabilities is important as in a feedback control system, detection and isolation of failures is generally affected by the particular control law used. Therefore, a common approach to control and failure diagnosis problems has significant merit. Controllers capable of performing failure diagnosis have additional diagnostic outputs to detect and isolate sensor and actuator faults. A linear such controller is usually called a four-parameter controller. Neural networks have proved to be a very powerful tool in the control systems area, where they have been used in the modelling and control of dynamical systems. In this paper, a neural network model of a controller with diagnostic capabilities (CDC) is presented for the first time. This nonlinear neural controller is trained to operate as a traditional controller, while at the same time it provides reproduction of the failure occurring either at the actuator or the sensor. The cases of actuator and sensor failure are studied independently. The validity of the results is verified by extensive simulations.A version of this paper under the title The Four-Parameter Controller. A Neural Network Implementation was presented at the IEEE Mediterranean Symposium on New Directions in Control Theory and Applications, Chania, Crete, Greece, June 21–23, 1993.  相似文献   
45.
Universal Access in the Information Society - Pervasive technologies such as Artificial Intelligence, Virtual Reality and the Internet of Things, despite their great potential for improved...  相似文献   
46.
Introducing high definition videos and images in object recognition has provided new possibilities in the field of intelligent image processing and pattern recognition. However, due to the large amount of information that needs to be processed, the computational costs are high, making the HD systems slow. To this end, a novel algorithm applied to sliding window analysis, namely Operator Context Scanning (OCS), is proposed and tested on the license plate detection module of a License Plate Recognition (LPR) system. In the LPR system, the OCS algorithm is applied on the Sliding Concentric Windows pixel operator and has been found to improve the LPR system’s performance in terms of speed by rapidly scanning input images focusing only on regions of interest, while at the same time it does not reduce the system effectiveness. Additionally, a novel characteristic is presented, namely, the context of the image based on a sliding windows operator. This characteristic helps to quickly categorize the environmental conditions upon which the input image was taken. The algorithm is tested on a data set that includes images of various resolutions, acquired under a variety of environmental conditions.  相似文献   
47.
This paper proposes a two-stage system for text detection in video images. In the first stage, text lines are detected based on the edge map of the image leading in a high recall rate with low computational time expenses. In the second stage, the result is refined using a sliding window and an SVM classifier trained on features obtained by a new Local Binary Pattern-based operator (eLBP) that describes the local edge distribution. The whole algorithm is used in a multiresolution fashion enabling detection of characters for a broad size range. Experimental results, based on a new evaluation methodology, show the promising overall performance of the system on a challenging corpus, and prove the superior discriminating ability of the proposed feature set against the best features reported in the literature.  相似文献   
48.
A repairable queueing model with a two-phase service in succession, provided by a single server, is investigated. Customers arrive in a single ordinary queue and after the completion of the first phase service, either proceed to the second phase or join a retrial box from where they retry, after a random amount of time and independently of the other customers in orbit, to find a position for service in the second phase. Moreover, the server is subject to breakdowns and repairs in both phases, while a start-up time is needed in order to start serving a retrial customer. When the server, upon a service or a repair completion finds no customers waiting to be served, he departs for a single vacation of an arbitrarily distributed length. The arrival process is assumed to be Poisson and all service and repair times are arbitrarily distributed. For such a system the stability conditions and steady state analysis are investigated. Numerical results are finally obtained and used to investigate system performance.  相似文献   
49.
This communication reports on the results of a web accessibility audit of public Web sites in Greece. The audit was conducted in 2008 by the Human Computer Interaction Laboratory of the Institute of Computer Science of FORTH, in its capacity as the Greek National Contact Centre of the European Design for All e-Accessibility Network. In an earlier e-Accessibility study in 2004, that evaluated approximately 250 public and commercial Web sites in Greece, 73% of the sample failed to meet the most basic requirements for web accessibility (). Four years later, in the context of a re-audit, a similar sample was examined for compliance with the same web accessibility standard (WCAG 1.0), as set by the Web Accessibility Initiative of the World Wide Web Consortium. The accessibility checks were conducted during the period from March to September 2008. A comparison of the results indicates that although new web development technologies may have been employed, instead of improving the overall status of e-accessibility, this has resulted in a serious deterioration in overall accessibility levels. Such findings—85% of sites failed to comply with Level A—suggest that Greek Web sites are likely to present even more significant access barriers to people with disability than in the past. As Web Accessibility is poorly understood and, until today, new platforms have failed to deliver products that conform to WCAG, the need emerges for a concrete legislative framework to set accessibility specifications for all public Web sites in Greece.  相似文献   
50.
A novel pose normalization method based on 3D object reflective symmetry is presented. It is a general purpose global pose normalization method; in this paper it is used to enhance the performance of a 3D object retrieval pipeline. Initially, the axis-aligned minimum bounding box of a rigid 3D object is modified by requiring that the 3D object is also in minimum angular difference with respect to the normals to the faces of its bounding box. To estimate the modified axis-aligned bounding box, a set of predefined planes of symmetry are used and a combined spatial and angular distance, between the 3D object and its symmetric object, is calculated. By minimizing the combined distance, the 3D object fits inside its modified axis-aligned bounding box and alignment with the coordinate system is achieved. The proposed method is incorporated in a hybrid scheme, that serves as the alignment method in a 3D object retrieval system. The effectiveness of the 3D object retrieval system, using the hybrid pose normalization scheme, is evaluated in terms of retrieval accuracy and demonstrated using both quantitative and qualitative measures via an extensive consistent evaluation on standard benchmarks. The results clearly show performance boost against current approaches.  相似文献   
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