Dynamic Denoising of Tracking Sequences

©2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.DOI: 10.1109/TIP.2008.920795In this paper, we describe an approach to the problem of simultaneously enhancing image sequences and tracking the objects of interest represented by the latter. The enhancement part of the algorithm is based on Bayesian wavelet denoising, which has been chosen due to its exceptional ability to incorporate diverse a priori information into the process of image recovery. In particular, we demonstrate that, in dynamic settings, useful statistical priors can come both from some reasonable assumptions on the properties of the image to be enhanced as well as from the images that have already been observed before the current scene. Using such priors forms the main contribution of the present paper which is the proposal of the dynamic denoising as a tool for simultaneously enhancing and tracking image sequences.Within the proposed framework, the previous observations of a dynamic scene are employed to enhance its present observation. The mechanism that allows the fusion of the information within successive image frames is Bayesian estimation, while transferring the useful information between the images is governed by a Kalman filter that is used for both prediction and estimation of the dynamics of tracked objects. Therefore, in this methodology, the processes of target tracking and image enhancement "collaborate" in an interlacing manner, rather than being applied separately. The dynamic denoising is demonstrated on several examples of SAR imagery. The results demonstrated in this paper indicate a number of advantages of the proposed dynamic denoising over "static" approaches, in which the tracking images are enhanced independently of each other

VolumeEVM: A new surface/volume integrated model

Volume visualization is a very active research area in the field of scien-tific visualization. The Extreme Vertices Model (EVM) has proven to be a complete intermediate model to visualize and manipulate volume data using a surface rendering approach. However, the ability to integrate the advantages of surface rendering approach with the superiority in visual exploration of the volume rendering would actually produce a very complete visualization and edition system for volume data. Therefore, we decided to define an enhanced EVM-based model which incorporates the volumetric information required to achieved a nearly direct volume visualization technique. Thus, VolumeEVM was designed maintaining the same EVM-based data structure plus a sorted list of density values corresponding to the EVM-based VoIs interior voxels. A function which relates interior voxels of the EVM with the set of densities was mandatory to be defined. This report presents the definition of this new surface/volume integrated model based on the well known EVM encoding and propose implementations of the main software-based direct volume rendering techniques through the proposed model.Postprint (published version

Image Segmentation Using Active Contours Driven by the Bhattacharyya Gradient Flow

©2007 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.DOI: 10.1109/TIP.2007.908073This paper addresses the problem of image segmentation by means of active contours, whose evolution is driven by the gradient flow derived froman energy functional that is based on the Bhattacharyya distance. In particular, given the values of a photometric variable (or of a set thereof), which is to be used for classifying the image pixels, the active contours are designed to converge to the shape that results in maximal discrepancy between the empirical distributions of the photometric variable inside and outside of the contours. The above discrepancy is measured by means of the Bhattacharyya distance that proves to be an extremely useful tool for solving the problem at hand. The proposed methodology can be viewed as a generalization of the segmentation methods, in which active contours maximize the difference between a finite number of empirical moments of the "inside" and "outside" distributions. Furthermore, it is shown that the proposed methodology is very versatile and flexible in the sense that it allows one to easily accommodate a diversity of the image features based on which the segmentation should be performed. As an additional contribution, a method for automatically adjusting the smoothness properties of the empirical distributions is proposed. Such a procedure is crucial in situations when the number of data samples (supporting a certain segmentation class) varies considerably in the course of the evolution of the active contour. In this case, the smoothness properties of the empirical distributions have to be properly adjusted to avoid either over- or underestimation artifacts. Finally, a number of relevant segmentation results are demonstrated and some further research directions are discussed

Recent advances in open billiards with some open problems

Much recent interest has focused on "open" dynamical systems, in which a classical map or flow is considered only until the trajectory reaches a "hole", at which the dynamics is no longer considered. Here we consider questions pertaining to the survival probability as a function of time, given an initial measure on phase space. We focus on the case of billiard dynamics, namely that of a point particle moving with constant velocity except for mirror-like reflections at the boundary, and give a number of recent results, physical applications and open problems.Comment: 16 pages, 1 figure in six parts. To appear in Frontiers in the study of chaotic dynamical systems with open problems (Ed. Z. Elhadj and J. C. Sprott, World Scientific

Analysis and optimization of the hardware design of a sic mosfet based power converter with sic schottky diodes utilizing a split output topology

In recent years, the use of power electronic devices for energy conversion with semiconductors such as silicon carbide (SiC) or gallium nitride (GaN) are replacing silicon due to their high thermal conductivity, efficiency, resistance, and the possibility of smaller and thinner designs. For this reason, in order to evaluate the improvement potential of these systems, it is beneficial to realize experimental setups that emulate real operating conditions in order to verify the correct performance of these systems. In this context and based on the previous work done by Giorgio Ferrara, this thesis focuses on the analysis and identification of improvements of a SiC MOSFET-based power electronic converter with the aim of suggesting and studying different solutions that ensure a high-performance operation that allows its correct implementation in motor traction and grid-connected applications. During the thesis work, it is carried out an in-depth analysis of the voltage peaks between drain and source originated by the fast switching of the MOSFET to evaluate the use of Snubber capacitors and it is made a new hardware design of the gate driver board using isolated gate drivers to improve the dynamic behaviour in the switching transients of the SiC transistors and provide safety and robustness to the system. Finally, maintaining the original design of the converter, it implements the split output topology to evaluate possible solutions to the problems of electromagnetic interference (EMI) and the crosstalk effect that occurs with high frequency switchingNegli ultimi anni, l'uso di dispositivi elettronici di potenza per la conversione dell'energia con semiconduttori come il carburo di silicio (SiC) o il nitruro di gallio (GaN) sta sostituendo il silicio grazie alla sua elevata conducibilità termica, all'efficienza, alla resistenza e alla possibilità di realizzare disegni più piccoli e sottili. Per questo motivo, al fine di valutare il potenziale di miglioramento di questi sistemi, è utile realizzare set-up sperimentali che emulino le condizioni operative reali, in modo da poter eseguire diversi test per verificare il corretto comportamento di questi sistemi. In tale contesto e a partire dal precedente lavoro effettuato per Giorgio Ferrara, la presente tesi si concentra nell' analisi e nidentificazione di miglioramenti di un convertitore di potenza DC-AC a commutazione, al fine di proporre e studiare diverse soluzioni che garantiscano le elevate prestazioni che assicurano la sua corretta implementazione in applicazioni di trazione a motore e di connessione alla rete. Durante il lavoro di tesi, si analizza in dettaglio il fenomeno di picchi di tensione tra drain e source causato per la commutazione veloce del MOSFET e si valuta l'utilizzo di condensatori snubber; in più si realizza un nuovo disegno hardware della board di gate driver utilizzando gate driver isolati per migliorare il comportamento dinamico nei transitori di commutazione dei transistor SiC e per fornire sicurezza e robustezza al sistema. Per finire, mantenendo il disegno originale del convertitore, implementa la topologia di uscita Split Output per valutare possibili soluzioni ai problemi di interferenza elettromagnetica (EMI) e all'effetto diafonia che si produce con la commutazione ad alta frequenzaObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.5 - Augmentar la investigació científica i millorar la capacitat tecnològica dels sectors industrials de tots els països, en particular els països en desenvolupament, entre d’altres maneres fomentant la innovació i augmentant substancialment, d’aquí al 2030, el nombre de persones que treballen en el camp de la investigació i el desenvolupa­ment per cada milió d’habitants, així com la despesa en investigació i desenvolupament dels sectors públic i priva

Analysis and optimization of the hardware design of a sic mosfet based power converter with sic schottky diodes utilizing a split output topology

In recent years, the use of power electronic devices for energy conversion with semiconductors such as silicon carbide (SiC) or gallium nitride (GaN) are replacing silicon due to their high thermal conductivity, efficiency, resistance, and the possibility of smaller and thinner designs. For this reason, in order to evaluate the improvement potential of these systems, it is beneficial to realize experimental setups that emulate real operating conditions in order to verify the correct performance of these systems. In this context and based on the previous work done by Giorgio Ferrara, this thesis focuses on the analysis and identification of improvements of a SiC MOSFET-based power electronic converter with the aim of suggesting and studying different solutions that ensure a high-performance operation that allows its correct implementation in motor traction and grid-connected applications. During the thesis work, it is carried out an in-depth analysis of the voltage peaks between drain and source originated by the fast switching of the MOSFET to evaluate the use of Snubber capacitors and it is made a new hardware design of the gate driver board using isolated gate drivers to improve the dynamic behaviour in the switching transients of the SiC transistors and provide safety and robustness to the system. Finally, maintaining the original design of the converter, it implements the split output topology to evaluate possible solutions to the problems of electromagnetic interference (EMI) and the crosstalk effect that occurs with high frequency switchingNegli ultimi anni, l'uso di dispositivi elettronici di potenza per la conversione dell'energia con semiconduttori come il carburo di silicio (SiC) o il nitruro di gallio (GaN) sta sostituendo il silicio grazie alla sua elevata conducibilità termica, all'efficienza, alla resistenza e alla possibilità di realizzare disegni più piccoli e sottili. Per questo motivo, al fine di valutare il potenziale di miglioramento di questi sistemi, è utile realizzare set-up sperimentali che emulino le condizioni operative reali, in modo da poter eseguire diversi test per verificare il corretto comportamento di questi sistemi. In tale contesto e a partire dal precedente lavoro effettuato per Giorgio Ferrara, la presente tesi si concentra nell' analisi e nidentificazione di miglioramenti di un convertitore di potenza DC-AC a commutazione, al fine di proporre e studiare diverse soluzioni che garantiscano le elevate prestazioni che assicurano la sua corretta implementazione in applicazioni di trazione a motore e di connessione alla rete. Durante il lavoro di tesi, si analizza in dettaglio il fenomeno di picchi di tensione tra drain e source causato per la commutazione veloce del MOSFET e si valuta l'utilizzo di condensatori snubber; in più si realizza un nuovo disegno hardware della board di gate driver utilizzando gate driver isolati per migliorare il comportamento dinamico nei transitori di commutazione dei transistor SiC e per fornire sicurezza e robustezza al sistema. Per finire, mantenendo il disegno originale del convertitore, implementa la topologia di uscita Split Output per valutare possibili soluzioni ai problemi di interferenza elettromagnetica (EMI) e all'effetto diafonia che si produce con la commutazione ad alta frequenzaObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.5 - Augmentar la investigació científica i millorar la capacitat tecnològica dels sectors industrials de tots els països, en particular els països en desenvolupament, entre d’altres maneres fomentant la innovació i augmentant substancialment, d’aquí al 2030, el nombre de persones que treballen en el camp de la investigació i el desenvolupa­ment per cada milió d’habitants, així com la despesa en investigació i desenvolupament dels sectors públic i priva