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Reconstrução tomográfica em SPECT: correcção da atenuação
Silvia De Francesco; Paulo J. S. G. FerreiraThis paper studies certain reconstruction algorithms which find application in computerized tomography. Special attention is devoted to SPECT and to the problem of attenuation and its correction. Several algorithms that have been proposed to perform attenuation correction are reviewed and compared. ; Neste artigo estudam-se certas classes de algoritmos de reconstrução que são especialmente...
Signal and Image Reconstruction: Minimum Dimension Methods in the Time and Freq...
Rui Jorge Ferreira da Costa; Paulo J. S. G. FerreiraThe reconstruction of signals and images is a common task in signal processing, with many applications. The deconvolution of signals is one of necessary steps to solve many inverse problem of practical importante, and tomography is an invaluable technique in medicine. Many other examples can be given. (...)Keywords: interpolation; reconstruction; extrapolation; samplingM.S., 1996more info. http://opac...
Fixed point problems: an introduction
Paulo J. S. G. FerreiraThis paper surveys a number of fundamental results on the existence and uniqueness of fixed points for certainclasses of possibly nonlinear operators. I do not try to be exhaustive, but merely to present the results that are more useful in the context of signal and image reconstruction. Some specific aspects pertaining to linear operators, and linear operators in finite dimensional spaces, are also discussed. I...
Teaching Signal Analysis to Electrical Engineering Students
Paulo J. S. G. Ferreira; Ana M. P. Tomé; Francisco VazThe techniques of harmonic analysis play a crucial role in Electrical engineering practice today. Any teacherknows that conveying these techniques is usually far from being an easy task. As for students, they do not exactly regard the subject as the simplest part of their curricula. One of the difficulties faced by the teacher concerns the number of concepts and tools that need to be taught. They include classi...
Teaching signal and image reconstruction algorithms
Paulo J. S. G. FerreiraSignal and image reconstruction are among the problems most often faced by whoever works in the broad field of multidimensional signal processing. Thus, an introductory course on this subject would probably be of interest to advanced Electrical Engineering students, specially those interested in telecomunications, information theory, or signal/ image processing in general. This paper is a report of my experienc...
Um erro comum no traçado de diagramas de Nyquist
Paulo J. S. G. FerreiraThere is a common misconception regarding Nyquist plots, or polar plots, of rational functions of nonzero type. The plots often show branches which tend to infinity while approaching either the real or imaginary axis. In this note it is shown that this is incorrect in general. The reasons behind this misconception are clarified. ; No decurso da minha actividade docente notei uma incorrecção basta...
Reconstrução tomográfica em SPECT: aspectos gerais
Silvia De Francesco; Paulo J. S. G. FerreiraThis paper is the first of two works devoted to the study of certain reconstruction algorithms which find application in computerized tomography. In this first paper we will study general aspects and computational issues in reference to tomographic reconstruction. The follow up paper will be exclusively concerned with the problem of attenuation in SPECTand its correction. ; Este artigo é o primeiro...
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