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2009

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Articles 1291 - 1320 of 1344

Full-Text Articles in Computer Sciences

Event-Detecting Multi-Agent Mdps: Complexity And Constant-Factor Approximation, Akshat Kumar, S. Zilberstein Jan 2009

Event-Detecting Multi-Agent Mdps: Complexity And Constant-Factor Approximation, Akshat Kumar, S. Zilberstein

Research Collection School Of Computing and Information Systems

Planning under uncertainty for multiple agents has grown rapidly with the development of formal models such as multi-agent MDPs and decentralized MDPs. But despite their richness, the applicability of these models remains limited due to their computational complexity. We present the class of event-detecting multi-agent MDPs (eMMDPs), designed to detect multiple mobile targets by a team of sensor agents. We show that eMMDPs are NP-Hard and present a scalable 2-approximation algorithm for solving them using matroid theory and constraint optimization. The complexity of the algorithm is linear in the state-space and number of agents, quadratic in the horizon, and exponential …


Computing Medoids In Large Spatial Datasets, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou Jan 2009

Computing Medoids In Large Spatial Datasets, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou

Research Collection School Of Computing and Information Systems

In this chapter, we consider a class of queries that arise in spatial decision making and resource allocation applications. Assume that a company wants to open a number of warehouses in a city. Let P be the set of residential blocks in the city. P represents customer locations to be potentially served by the company. At the same time, P also comprises the candidate warehouse locations because the warehouses themselves must be opened in some residential blocks.


A Comprehensive Study For Rfid Malwares On Mobile Devices, Qiang Yan, Yingjiu Li, Tieyan Li, Robert Huijie Deng Jan 2009

A Comprehensive Study For Rfid Malwares On Mobile Devices, Qiang Yan, Yingjiu Li, Tieyan Li, Robert Huijie Deng

Research Collection School Of Computing and Information Systems

Radio Frequency Identification (RFID) technique has been widely accepted as wireless identification standard in the business world. While RFID technique enables efficient collection of identification information, it also introduces new security risk due to the emerging of RFID malwares. This risk becomes increasingly severe due to the adoption of internet in RFID applications (e.g., track and trace in EPCglobal network) and the use of mobile devices as RFID readers. The prior work to defend the threat of RFID malwares has mainly focused on the protection of front-end tag-reader communications and back-end database systems. Less work has been conducted to defend …


Quality-Aware Collaborative Question Answering: Methods And Evaluation, Maggy Anastasia Suryanto, Ee Peng Lim, Aixin Sun, Roger Hsiang-Li Chiang Jan 2009

Quality-Aware Collaborative Question Answering: Methods And Evaluation, Maggy Anastasia Suryanto, Ee Peng Lim, Aixin Sun, Roger Hsiang-Li Chiang

Research Collection School Of Computing and Information Systems

Community Question Answering (QA) portals contain questions and answers contributed by hundreds of millions of users. These databases of questions and answers are of great value if they can be used directly to answer questions from any user. In this research, we address this collaborative QA task by drawing knowledge from the crowds in community QA portals such as Yahoo! Answers. Despite their popularity, it is well known that answers in community QA portals have unequal quality. We therefore propose a quality-aware framework to design methods that select answers from a community QA portal considering answer quality in addition to …


Localized Monitoring Of Knn Queries In Wireless Sensor Networks, Yuxia Yao, Xueyan Tang, Ee Peng Lim Jan 2009

Localized Monitoring Of Knn Queries In Wireless Sensor Networks, Yuxia Yao, Xueyan Tang, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Wireless sensor networks have been widely used in civilian and military applications. Primarily designed for monitoring purposes, many sensor applications require continuous collection and processing of sensed data. Due to the limited power supply for sensor nodes, energy efficiency is a major performance concern in query processing. In this paper, we focus on continuous kNN query processing in object tracking sensor networks. We propose a localized scheme to monitor nearest neighbors to a query point. The key idea is to establish a monitoring area for each query so that only the updates relevant to the query are collected. The monitoring …


Modelling Situation Awareness For Context‐Aware Decision Support, Yu-Hong Feng, Teck-Hou Teng, Ah-Hwee Tan Jan 2009

Modelling Situation Awareness For Context‐Aware Decision Support, Yu-Hong Feng, Teck-Hou Teng, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

Situation awareness modelling is popularly used in the command and control domain for situation assessment and decision support. However, situation models in real-world applications are typically complex and not easy to use. This paper presents a Context-aware Decision Support (CaDS) system, which consists of a situation model for shared situation awareness modelling and a group of entity agents, one for each individual user, for focused and customized decision support. By incorporating a rule-based inference engine, the entity agents provide functions including event classification, action recommendation, and proactive decision making. The implementation and the performance of the proposed system are demonstrated …


A Formal Concept Analysis Approach To Association Rule Mining: The Quicl Algorithms, David T. Smith Jan 2009

A Formal Concept Analysis Approach To Association Rule Mining: The Quicl Algorithms, David T. Smith

CCAC Theses and Dissertations

Association rule mining (ARM) is the task of identifying meaningful implication rules exhibited in a data set. Most research has focused on extracting frequent item (FI) sets and thus fallen short of the overall ARM objective. The FI miners fail to identify the upper covers that are needed to generate a set of association rules whose size can be exploited by an end user. An alternative to FI mining can be found in formal concept analysis (FCA), a branch of applied mathematics. FCA derives a concept lattice whose concepts identify closed FI sets and connections identify the upper covers. However, …


Insulation Condition Assessment Of Power Transformers Using Accelerated Ageing Tests, Mohammad Mirzaie, Ahmad Gholami, Hamid Reza Tayebi Jan 2009

Insulation Condition Assessment Of Power Transformers Using Accelerated Ageing Tests, Mohammad Mirzaie, Ahmad Gholami, Hamid Reza Tayebi

Turkish Journal of Electrical Engineering and Computer Sciences

Thermal stress due to losses and environment temperature causes degradation to paper/oil insulation systems in transformers, even at operating temperature. Experience indicates that thermal ageing of oil and paper in power transformers leads to the change of some insulation characteristics. In this paper, insulating papers immersed in oil have been acceleratory aged at 140, 150, and 160 °C under laboratory conditions. Some of the oil properties, such as water content, breakdown voltage, acidity, together with the aged insulating paper properties such as electric strength, dielectric dissipation factor and tensile strength were measured and analyzed. Also, insulation system conditions under thermal …


Accurate Prediction Of Crosstalk For Rc Interconnects, Selahatti̇n Sayil, Merlyn Rudrapati Jan 2009

Accurate Prediction Of Crosstalk For Rc Interconnects, Selahatti̇n Sayil, Merlyn Rudrapati

Turkish Journal of Electrical Engineering and Computer Sciences

This work proposes an accurate crosstalk noise estimation method in the presence of multiple RC lines for use in design automation tools. The method correctly models the loading effects of non switching aggressors and aggressor tree branches using resistive shielding effect and realistic exponential input waveform. Noise peak and width expressions derived show very good results in comparison to HSPICE results. Results show that average error for noise peak is 4.1% and for the width is 6.8% while allowing for very fast analysis.


Softcomputing Identification Techniques Of Asynchronous Machine Parameters: Evolutionary Strategy And Chemotaxis Algorithm, Nouri Benaïdja Jan 2009

Softcomputing Identification Techniques Of Asynchronous Machine Parameters: Evolutionary Strategy And Chemotaxis Algorithm, Nouri Benaïdja

Turkish Journal of Electrical Engineering and Computer Sciences

Softcomputing techniques are receiving attention as optimisation techniques for many industrial applications. Although these techniques eliminate the need for derivatives computation, they require much work to adjust their parameters at the stage of research and development. Issues such as speed, stability, and parameters convergence remain much to be investigated. This paper discusses the application of the method of reference model to determine parameters of asynchronous machines using two optimisation techniques. Softcomputing techniques used in this paper are evolutionary strategy and the chemotaxis algorithm. Identification results using the two techniques are presented and compared with respect to the conventional simplex technique …


Parameter Identification Of A Separately Excited Dc Motor Via Inverse Problem Methodology, Mounir Hadef, Mohamed Rachid Mekideche Jan 2009

Parameter Identification Of A Separately Excited Dc Motor Via Inverse Problem Methodology, Mounir Hadef, Mohamed Rachid Mekideche

Turkish Journal of Electrical Engineering and Computer Sciences

Identification is considered to be among the main applications of inverse theory and its objective for a given physical system is to use data which is easily observable, to infer some of the geometric parameters which are not directly observable. In this paper, a parameter identification method using inverse problem methodology is proposed. The minimisation of the objective function with respect to the desired vector of design parameters is the most important procedure in solving the inverse problem. The conjugate gradient method is used to determine the unknown parameters, and Tikhonov's regularization method is then used to replace the original …


Pca Based Protection Algorithm For Transformer Internal Faults, Erdal Kiliç, Okan Özgönenel, Ömer Usta, Dave Thomas Jan 2009

Pca Based Protection Algorithm For Transformer Internal Faults, Erdal Kiliç, Okan Özgönenel, Ömer Usta, Dave Thomas

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper a new protection scheme is introduced to detect and identify transformer winding faults. The new approach is based on artificial neural networks (ANNs) using radial basis functions (RBFs) and the principal component analysis (PCA). The nonlinear system's input and output data is manipulated without considering any model of the system. This approach is used to detect and identify internal short circuit faults of a three phase custom built transformer. The suggested technique is also able to distinguish between the fault and magnetizing inrush current. The test studies carried out shows that the proposed method leads to satisfactory …


Polymorphic Worm Detection Using Strong Token-Pair Signatures, Burak Bayoğlu, İbrahi̇m Soğukpinar Jan 2009

Polymorphic Worm Detection Using Strong Token-Pair Signatures, Burak Bayoğlu, İbrahi̇m Soğukpinar

Turkish Journal of Electrical Engineering and Computer Sciences

Malicious software has become a big threat to information systems, which are widely used to store, transfer and process information for many critical assets. Worms are one of the most harmful network-enabled malicious software that can threaten networks and applications. Two main characteristics of worms distinguish them from the well-known virus programs and as a result are much more dangerous than the virus programs. First, they do not need to attach themselves to an existing program. Second, worms do not require end-user interaction to realize the intended attack. Therefore, a large number of victims can be infected in a short …


An Intelligent Face Features Generation System From Fingerprints, Şeref Sağiroğlu, Necla Özkaya Jan 2009

An Intelligent Face Features Generation System From Fingerprints, Şeref Sağiroğlu, Necla Özkaya

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a novel intelligent system based on artificial neural networks was designed and introduced for generating faces from fingerprints with high accuracy. The proposed system has a number of modules including two feature enrolment modules for acquiring the fingerprints and faces into the system, two feature extractors for extracting the feature sets of fingerprint and face biometrics, an artificial neural network module that was configured with the help of Taguchi experimental design method for establishing relationships among the biometric features, a face re-constructor for building up face features from the results of the system, and a test module …


Cdm Based Controller Design For Nonlinear Heat Exchanger Process, Erkan İmal Jan 2009

Cdm Based Controller Design For Nonlinear Heat Exchanger Process, Erkan İmal

Turkish Journal of Electrical Engineering and Computer Sciences

Most processes are nonlinear, and their control is a difficult yet important problem. The heat exchanger is an example onesuch nonlinear process. In the present paper, the effect of process nonlinearity on the performance of set point tracking and disturbance rejection in two controller methods is investigated. Initially, afirst order plus dead time (FOPDT) model of the process is obtainedvia a software known as Loop-Pro Trainer. Then, the PI-controller tuning values are computed using the internal model control (IMC) correlations based on truncated (first-order) Taylor series approximation. Next, another controller is designed using the coefficient diagram method (CDM). Finally, the …


Variance And Kurtosis-Based Characterization Of Resonances In Stochastic Transmission Lines: Local Versus Global Random Geometries, Ousmane Sy, Martijn Van Beurden, Bastiaan Michielsen, Antonius Tijhuis Jan 2009

Variance And Kurtosis-Based Characterization Of Resonances In Stochastic Transmission Lines: Local Versus Global Random Geometries, Ousmane Sy, Martijn Van Beurden, Bastiaan Michielsen, Antonius Tijhuis

Turkish Journal of Electrical Engineering and Computer Sciences

A stochastic method is proposed to characterize electromagnetic couplings involving geometrically perturbed transmission lines. A combined exploitation of suitably defined statistical tools is presented to appreciate the intensity of the dispersion of response variables both physically via the variance, and statistically through the kurtosis or fourth-order moment. The usefulness of this method to analyze resonances is illustrated by the study of a transmission line affected by two different types of random geometrical perturbations, viz. a local deformation modeled by a wavelet and global sinusoidal undulations.


Weak Penetration And Radiation Through Apertures In Conducting Bodies Of Revolution, Korkut Yeği̇n Jan 2009

Weak Penetration And Radiation Through Apertures In Conducting Bodies Of Revolution, Korkut Yeği̇n

Turkish Journal of Electrical Engineering and Computer Sciences

The simplest way to solve for penetration through small apertures in conducting surfaces is to treat the body as a scatterer and determine the interior field as the sum of the incident field and the scattered field contributed by the current induced on the surface of the body. However, it is well known that, if the aperture is very small or if the penetrated field is very weak this method yields very inaccurate results, which, in turn, prohibits proper design of electronic systems, especially for electromagnetic compatibility and interference. Previously, alternative integral equations formulations were proposed to remedy this problem …


Experimantal Characterization And Equivalent Circuit Extraction Of Nanowires For Signal Integrity Applications, Giulio Antonini, Marco Di Clerico, Antonio Orlandi, Vittorio Ricchiuti, Maurizio Passacantando, Sandro Santucci Jan 2009

Experimantal Characterization And Equivalent Circuit Extraction Of Nanowires For Signal Integrity Applications, Giulio Antonini, Marco Di Clerico, Antonio Orlandi, Vittorio Ricchiuti, Maurizio Passacantando, Sandro Santucci

Turkish Journal of Electrical Engineering and Computer Sciences

This paper illustrates the design steps of a printed circuit board used as test vehicles for the measurement of the electrical properties of carbon nanotube's deposit. The board has been built and used for the measurements. The measured data are post-processed in order to extract the required properties of the only nanotubes. An equivalent circuit is extracted for further use in EDA simulators and the IEEE P1597 Standard is used to compare the results.


Conductive Emi Noise Measurement For Switched Reluctance Drive, Hao Chen, Xiaohui Qiu, Yang Zhao Jan 2009

Conductive Emi Noise Measurement For Switched Reluctance Drive, Hao Chen, Xiaohui Qiu, Yang Zhao

Turkish Journal of Electrical Engineering and Computer Sciences

The component parts of the tested four-phase Switched Reluctance drive are described with the four-phase 8/6 structure double salient reluctance motor, the four-phase asymmetric bridge power converter and the 89C52 MCU digital controller. The conductive electromagnetic interference noise measurement equipment is described with the function of separated common-mode noise and differential-mode noise. The tested results of common-mode noise and differential-mode noise of the tested Switched Reluctance drive are presented and the tested results of frequency spectrum are given.


Emc Education At The University Of Technology Zurich, Gökhan Apaydin, Ni̇yazi̇ Ari Jan 2009

Emc Education At The University Of Technology Zurich, Gökhan Apaydin, Ni̇yazi̇ Ari

Turkish Journal of Electrical Engineering and Computer Sciences

This paper illustrates educational issues in electromagnetic compatibility (EMC) engineering in Switzerland and presents the contents of courses and practical materials for EMC education at the University of Technology Zurich. After giving the fundamentals of theoretical part, practical applications have been given to make students and engineers aware of EMC issues and its problems.


Two Dimensional Ebg Structures For Multiband Noise Mitigation, Antonio Orlandi, Antonio Ciccomancini Jan 2009

Two Dimensional Ebg Structures For Multiband Noise Mitigation, Antonio Orlandi, Antonio Ciccomancini

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper a two dimensional (2D) electromagnetic Bandgap (EBG) structure is proposed for multi band noise mitigation in PWR/GND plane pairs. Excellent noise suppression (-60 dB) is achieved in multiple bands within the range 0--8 GHz with a low start frequency. Because of the 2D EBG, no additional metal layer is required. Signal Integrity analysis is also studied by modelling a microstrip to stripline transition (both single ended and differential) and by evaluating insertion loss, TDR as well as eye diagram.


Development Of A Magnetic Field Model And Insertion~Into A Commercial Electromagnetic Simulator, Priscila Fernandez Lopez, Christian Arcambal, Yolanda Vives Gilabert, Abhishek Ramanujan, David Baudry, Anne Louis, Belahcene Mazari Jan 2009

Development Of A Magnetic Field Model And Insertion~Into A Commercial Electromagnetic Simulator, Priscila Fernandez Lopez, Christian Arcambal, Yolanda Vives Gilabert, Abhishek Ramanujan, David Baudry, Anne Louis, Belahcene Mazari

Turkish Journal of Electrical Engineering and Computer Sciences

To take into account~certain ElectroMagnetic Compatibility (EMC) aspects~and especially to evaluate the magnetic fields radiated by electronic components, different radiated emission models have been created. Within IRSEEM, a magnetic field model based on equivalent sources (electric dipoles) placed on a plane has been developed. Thus, this paper presents the modelling procedure that requires~magnetic near-field measurements and matrix inversion methods. Concerning the measurements of the field radiated by the component under test,~a near-field test bench with a loop antenna is used to~quantify the tangential components of the magnetic field in amplitude and phase. Then, these data are used as input to …


Electromagnetic Compatibility Engineering Education: Problems, Challenges And Perspectives, Levent Sevgi̇ Jan 2009

Electromagnetic Compatibility Engineering Education: Problems, Challenges And Perspectives, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

Education and training problems and challenges in EMC Engineering are discussed. The necessity of physics-based modeling (theory) and hands-on training (practice) are emphasized. An introductory level EMC lecture and a short course outline are given for modern EMC education.


New Esd Standard And Influence On Test Equipment Requirements, Nicholas Wright Jan 2009

New Esd Standard And Influence On Test Equipment Requirements, Nicholas Wright

Turkish Journal of Electrical Engineering and Computer Sciences

The IEC61000-4 series of standards form a basic framework for the immunity and emissions testing of electrical and electronic equipment. They are the basis for EN standards used to test CE compliance of electrical and electronic products sold within the European Union. After a period of relative stability, changes are being introduced, designed to improve reliable application of the basic standards and ensure that the same results are obtained no matter where the tests are performed. Many changes relate to the calibration procedures for the test equipment. The surge standard, IEC61000-4-5, was revised at Edition 2 to amend impulse performance …


Parameter Optimization For Image Denoising Based On Block Matching And 3d Collaborative Filtering, Ramu Pedada, Emin Kugu, Jiang Li, Zhanfeng Yue, Yuzhong Shen, Josien P.W. Pluim (Ed.), Benoit M. Dawant (Ed.) Jan 2009

Parameter Optimization For Image Denoising Based On Block Matching And 3d Collaborative Filtering, Ramu Pedada, Emin Kugu, Jiang Li, Zhanfeng Yue, Yuzhong Shen, Josien P.W. Pluim (Ed.), Benoit M. Dawant (Ed.)

Electrical & Computer Engineering Faculty Publications

Clinical MRI images are generally corrupted by random noise during acquisition with blurred subtle structure features. Many denoising methods have been proposed to remove noise from corrupted images at the expense of distorted structure features. Therefore, there is always compromise between removing noise and preserving structure information for denoising methods. For a specific denoising method, it is crucial to tune it so that the best tradeoff can be obtained. In this paper, we define several cost functions to assess the quality of noise removal and that of structure information preserved in the denoised image. Strength Pareto Evolutionary Algorithm 2 (SPEA2) …


Quirky, Not Quacky: Quantum Computing For Librarians, Jill Cirasella Jan 2009

Quirky, Not Quacky: Quantum Computing For Librarians, Jill Cirasella

Publications and Research

This slideshow introduces librarians and non-scientists to the relatively young field of quantum computing.


A Unified Resource Platform For The Rapid Development Of Scalable Web Applications, Russell Palmiter Jan 2009

A Unified Resource Platform For The Rapid Development Of Scalable Web Applications, Russell Palmiter

Master's Theses

This thesis presents Web Utility Kit (WUT): a platform that helps to simplify the process of creating modern web applications. It addresses the need to simplify the web development process through the creation of a hosted service that provides access to a unified set of resources. The resources are made available through a variety of protocols and formats to help simplify their consumption. It also provides a uniform model across all of its resources making multi-resource development an easier and more familiar task. WUT saves the time and cost associated with deployment, maintenance, and hosting of the hardware and software …


A Semiotic Analysis Of Unified Modeling Language Graphical Notations, Keng Siau, Yuhong Tian Jan 2009

A Semiotic Analysis Of Unified Modeling Language Graphical Notations, Keng Siau, Yuhong Tian

Research Collection School Of Computing and Information Systems

Unified modeling language (UML) is the standard modeling language for object-oriented system development. Despite its status as a standard, UML has a fuzzy formal specification and a weak theoretical foundation. Semiotics, the study of signs, provides a good theoretical foundation for UML research because graphical notations (or visual signs) of UML are subjected to the principles of signs. In our research, we use semiotics to study the effectiveness of graphical notations in UML. We hypothesized that the use of iconic signs as UML graphical notations leads to representation that is more accurately interpreted and that arouses fewer connotations than the …


Distributed Utility-Based Rate Adaptation Protocols For Prioritized, Quasi-Elastic Flows, Sharanya Eswaran, Matthew P. Johnson, Archan Misra, Thomas La Porta Jan 2009

Distributed Utility-Based Rate Adaptation Protocols For Prioritized, Quasi-Elastic Flows, Sharanya Eswaran, Matthew P. Johnson, Archan Misra, Thomas La Porta

Research Collection School Of Computing and Information Systems

This paper considers rate adaptation for streaming multimedia data in a wireless sensor network (WSN) consisting of multiple missions, where each mission subscribes to data streams from multiple sensors, and each sensor's data is utilized by multiple heterogenous missions. We specifically consider the application of the distributed network utility maximization (NUM) framework to a previously unconsidered scenario where the different missions have different priorities, as well as minimum utility demands. When all the utility demands are feasible, we first show that the addition of a penalty for failing to reach the minimum utility demand to the base NUM protocol leads …


Control-Theoretic, Mission-Driven, Optimization Techniques For Wireless Sensor Networks, Archan Misra, Sharanya Eswaran, Thomas La Porta Jan 2009

Control-Theoretic, Mission-Driven, Optimization Techniques For Wireless Sensor Networks, Archan Misra, Sharanya Eswaran, Thomas La Porta

Research Collection School Of Computing and Information Systems

Network Utility Maximization (NUM) techniques, which cast resource sharing problems as one of distributed utility maximization, have been investigated for a variety of optimization problems in wireless and wired networks. Our recent work has extended the NUM framework to consider the case of resource sharing by multiple competing missions in a military-centric wireless sensor network (WSN) environment. Our enhanced NUM-based protocols provide rapid and dynamic mission-based adaptation of tactical wireless networks to support the transport of sensor data streams with very small control overhead. In particular, we focus specifically on mechanisms that capture the joint nature of mission utilities and …