Marcelo Perez - Academia.edu (original) (raw)
Papers by Marcelo Perez
Edge and feature points are basic low level primitives for image processing. The justification is... more Edge and feature points are basic low level primitives for image processing. The justification is that such points convey a lot of structural information about the surfaces of the objects captured in the imaging process. Because of this, edge and feature detection are two of the most common operations in image analysis. Despite the variety of operators available for these purposes, there are still some drawbacks common to most of them, even the more sophisticated ones. Among them, the problems of connectivity and shape of junctions by edge detectors, and the dichotomy between reliability of detection and localization accuracy for feature detectors are particularly outstanding. The present work proposes an adaptive implementation of the SUSAN method for edge and feature detection. The aim is the development of an algorithm that offers some performance improvement in tackling these limitations
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To characterize edges, this work proposes a zero-crossing detector that attempts to provide a mor... more To characterize edges, this work proposes a zero-crossing detector that attempts to provide a more precise localization of edges together with robustness to brightness and contrast variation in images. Since the algorithm aims to be insensitive to image histogram manipulations, it is based on zero-crossings of the second derivative, and not on first derivative measurements. In order to provide good localization while preserving the true shape of the edges, the detector is based on precise mathematical expressions that represent image derivatives as a vector field, instead of using the Laplacian as a scalar approximation for the image second derivatives. This way, the proposed detector can be viewed as a Marr-Hildreth operator with a more exact mathematical formulation. Finally, to avoid false responses and provide thin edges, some additional checking is performed over the edge candidate points. The method showed good results when compared with well-known edge detectors.
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Page 1. Reconstruction of Intermediate Views from Stereoscopic Images Using a Rational Filter CL ... more Page 1. Reconstruction of Intermediate Views from Stereoscopic Images Using a Rational Filter CL Pagliari, M. M. Perez and TJ Dennis Department of Electronic Systems Engineering, University of Essex Colchester, C 0 4 5UG, United Kingdom {clpagl, mdmper, tim} @essex.ac. ...
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IEEE Transactions on Industrial Electronics, 2006
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IEEE Transactions on Industrial Electronics, 2006
AbstractA control system for power smoothing using a switched reluctance machine (SRM) driving a... more AbstractA control system for power smoothing using a switched reluctance machine (SRM) driving a flywheel is pre-sented in this paper. Power smoothing is achieved by controlling the SRM to operate as a motor/generator, storing or retrieving energy from a rotating flywheel. ...
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A phase locked loop algorithm appropriated for DSP-based control implementations where the operat... more A phase locked loop algorithm appropriated for DSP-based control implementations where the operation of a static power converter needs to be synchronized with an AC network is presented. The operating principle of the proposed algorithm includes a multiplier, a filter, a feedback closed loop, and a voltage controlled oscillator (VCO) stage. As a result, a discrete sine (and cosine) signal is generated in perfect synchronism with the fundamental component of an external reference signal. Moreover, the sampling period of the algorithm is adjusted at each sampling instant such that an integer number of sampling periods is ensured per period of the external reference signal. This is mainly achieved by using an improved discrete rectangular window filter and a discrete controller. The algorithm code is simple, stable, and presents high noise rejection. The theoretical justification and various experimental tests are included
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Abstract Multilevel converters are used mainly in medium-voltage high-power applications. In this... more Abstract Multilevel converters are used mainly in medium-voltage high-power applications. In this field, switching losses are an important issue due to long term operation costs and cooling system design. Previous works have centered the analysis in comparing different topologies and semiconductors in relation to switching losses. However, switching losses are also closely related to the modulation method used to control the converter, since they are responsible of producing the commutations. This paper presents an in depth ...
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IEEE Transactions on Industrial Electronics, 2008
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IEEE Transactions on Industrial Electronics, 2010
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IEEE Transactions on Industrial Electronics, 2007
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IEEE Transactions on Industrial Electronics, 2007
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IEEE Transactions on Industrial Electronics, 2005
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IEEE Transactions on Industrial Electronics, 2010
Abstract Cascaded multilevel inverters synthesize a medium-voltage output based on a series conne... more Abstract Cascaded multilevel inverters synthesize a medium-voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltages and input currents and also outstanding availability due to their intrinsic component redundancy. Due to these features, the cascaded multilevel inverter has been recognized as an important alternative in the medium-voltage inverter market. This paper presents a survey of different topologies, ...
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Commercial active-front-rectifiers based upon three-phase voltage source topologies are capable o... more Commercial active-front-rectifiers based upon three-phase voltage source topologies are capable of both supplying or absorbing reactive power from the electrical distribution system while serving as high DC power supplies. This is an important feature in industrial facilities where high power factor operation is of concern. This paper shows that the available range of reactive power in such topologies depends upon the actual active power being supplied by the topology to the load. Moreover, both the voltage and current source based topologies have limited and variable maximum reactive power compensation capabilities. In fact, both topologies are capable of providing maximum reactive power compensation when supplying 0.707 pu active power when operating passive loads in the rectifier mode. Extended analysis shows that during regeneration both topologies are also capable of supplying or absorbing limited amounts of reactive power from the electrical distribution system. Simulated and experimental results confirm the theoretical considerations
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Hybrid multi-cell converters present a highly nonlinear power distribution at each cell. Moreover... more Hybrid multi-cell converters present a highly nonlinear power distribution at each cell. Moreover, the cells with smaller DC link voltage can regenerate power, even if the load is not active. This paper shows the active power distribution in terms of the modulation index, highlighting the regenerative operation. The active power is calculated based on the fundamental term of the switching pattern obtained by the nearest level or round modulation. The round modulation technique is described as a comparison algorithm to allow a mathematical analysis. This paper shows that low power cells present a regenerative operation which depends on the modulation technique and does not depend of the load type. The modulation index rates of regenerative operation are found, as example, for a three-cell hybrid multi- cell converter for two different asymmetries.
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IEEE Transactions on Industrial Electronics, 2009
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Abstract Multilevel converters can reach medium-voltage operation, increasing the efficiency in h... more Abstract Multilevel converters can reach medium-voltage operation, increasing the efficiency in high power applications. Among the existing multilevel converter topologies, modular multilevel converter provides the advantages of high modularity, availability and high power quality. Moreover, the main advantage compared to cascaded multilevel converters is the absence of input transformer; reducing the size, cost and cooling requirements. When used as AC-AC converter, it usually requires a sophisticated controller to decouple the input ...
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Bookmarks Related papers MentionsView impact
Proceedings of The IEEE, 2009
Multilevel converters are considered today as the state-of-the-art power-conversion systems for h... more Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.
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Edge and feature points are basic low level primitives for image processing. The justification is... more Edge and feature points are basic low level primitives for image processing. The justification is that such points convey a lot of structural information about the surfaces of the objects captured in the imaging process. Because of this, edge and feature detection are two of the most common operations in image analysis. Despite the variety of operators available for these purposes, there are still some drawbacks common to most of them, even the more sophisticated ones. Among them, the problems of connectivity and shape of junctions by edge detectors, and the dichotomy between reliability of detection and localization accuracy for feature detectors are particularly outstanding. The present work proposes an adaptive implementation of the SUSAN method for edge and feature detection. The aim is the development of an algorithm that offers some performance improvement in tackling these limitations
Bookmarks Related papers MentionsView impact
To characterize edges, this work proposes a zero-crossing detector that attempts to provide a mor... more To characterize edges, this work proposes a zero-crossing detector that attempts to provide a more precise localization of edges together with robustness to brightness and contrast variation in images. Since the algorithm aims to be insensitive to image histogram manipulations, it is based on zero-crossings of the second derivative, and not on first derivative measurements. In order to provide good localization while preserving the true shape of the edges, the detector is based on precise mathematical expressions that represent image derivatives as a vector field, instead of using the Laplacian as a scalar approximation for the image second derivatives. This way, the proposed detector can be viewed as a Marr-Hildreth operator with a more exact mathematical formulation. Finally, to avoid false responses and provide thin edges, some additional checking is performed over the edge candidate points. The method showed good results when compared with well-known edge detectors.
Bookmarks Related papers MentionsView impact
Page 1. Reconstruction of Intermediate Views from Stereoscopic Images Using a Rational Filter CL ... more Page 1. Reconstruction of Intermediate Views from Stereoscopic Images Using a Rational Filter CL Pagliari, M. M. Perez and TJ Dennis Department of Electronic Systems Engineering, University of Essex Colchester, C 0 4 5UG, United Kingdom {clpagl, mdmper, tim} @essex.ac. ...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2006
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2006
AbstractA control system for power smoothing using a switched reluctance machine (SRM) driving a... more AbstractA control system for power smoothing using a switched reluctance machine (SRM) driving a flywheel is pre-sented in this paper. Power smoothing is achieved by controlling the SRM to operate as a motor/generator, storing or retrieving energy from a rotating flywheel. ...
Bookmarks Related papers MentionsView impact
A phase locked loop algorithm appropriated for DSP-based control implementations where the operat... more A phase locked loop algorithm appropriated for DSP-based control implementations where the operation of a static power converter needs to be synchronized with an AC network is presented. The operating principle of the proposed algorithm includes a multiplier, a filter, a feedback closed loop, and a voltage controlled oscillator (VCO) stage. As a result, a discrete sine (and cosine) signal is generated in perfect synchronism with the fundamental component of an external reference signal. Moreover, the sampling period of the algorithm is adjusted at each sampling instant such that an integer number of sampling periods is ensured per period of the external reference signal. This is mainly achieved by using an improved discrete rectangular window filter and a discrete controller. The algorithm code is simple, stable, and presents high noise rejection. The theoretical justification and various experimental tests are included
Bookmarks Related papers MentionsView impact
Abstract Multilevel converters are used mainly in medium-voltage high-power applications. In this... more Abstract Multilevel converters are used mainly in medium-voltage high-power applications. In this field, switching losses are an important issue due to long term operation costs and cooling system design. Previous works have centered the analysis in comparing different topologies and semiconductors in relation to switching losses. However, switching losses are also closely related to the modulation method used to control the converter, since they are responsible of producing the commutations. This paper presents an in depth ...
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2008
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2010
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2007
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2007
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2005
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2010
Abstract Cascaded multilevel inverters synthesize a medium-voltage output based on a series conne... more Abstract Cascaded multilevel inverters synthesize a medium-voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltages and input currents and also outstanding availability due to their intrinsic component redundancy. Due to these features, the cascaded multilevel inverter has been recognized as an important alternative in the medium-voltage inverter market. This paper presents a survey of different topologies, ...
Bookmarks Related papers MentionsView impact
Commercial active-front-rectifiers based upon three-phase voltage source topologies are capable o... more Commercial active-front-rectifiers based upon three-phase voltage source topologies are capable of both supplying or absorbing reactive power from the electrical distribution system while serving as high DC power supplies. This is an important feature in industrial facilities where high power factor operation is of concern. This paper shows that the available range of reactive power in such topologies depends upon the actual active power being supplied by the topology to the load. Moreover, both the voltage and current source based topologies have limited and variable maximum reactive power compensation capabilities. In fact, both topologies are capable of providing maximum reactive power compensation when supplying 0.707 pu active power when operating passive loads in the rectifier mode. Extended analysis shows that during regeneration both topologies are also capable of supplying or absorbing limited amounts of reactive power from the electrical distribution system. Simulated and experimental results confirm the theoretical considerations
Bookmarks Related papers MentionsView impact
Hybrid multi-cell converters present a highly nonlinear power distribution at each cell. Moreover... more Hybrid multi-cell converters present a highly nonlinear power distribution at each cell. Moreover, the cells with smaller DC link voltage can regenerate power, even if the load is not active. This paper shows the active power distribution in terms of the modulation index, highlighting the regenerative operation. The active power is calculated based on the fundamental term of the switching pattern obtained by the nearest level or round modulation. The round modulation technique is described as a comparison algorithm to allow a mathematical analysis. This paper shows that low power cells present a regenerative operation which depends on the modulation technique and does not depend of the load type. The modulation index rates of regenerative operation are found, as example, for a three-cell hybrid multi- cell converter for two different asymmetries.
Bookmarks Related papers MentionsView impact
IEEE Transactions on Industrial Electronics, 2009
Bookmarks Related papers MentionsView impact
Abstract Multilevel converters can reach medium-voltage operation, increasing the efficiency in h... more Abstract Multilevel converters can reach medium-voltage operation, increasing the efficiency in high power applications. Among the existing multilevel converter topologies, modular multilevel converter provides the advantages of high modularity, availability and high power quality. Moreover, the main advantage compared to cascaded multilevel converters is the absence of input transformer; reducing the size, cost and cooling requirements. When used as AC-AC converter, it usually requires a sophisticated controller to decouple the input ...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Proceedings of The IEEE, 2009
Multilevel converters are considered today as the state-of-the-art power-conversion systems for h... more Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.
Bookmarks Related papers MentionsView impact