Title from PDF of title page. / Document formatted into pages; contains 82 pages. / Thesis (M.S.E.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Image quality measures are used to optimize image processing algorithms and evaluate their performances. The only reliable way to assess image quality is subjective evaluation by human observers, where the mean value of their scores is used as the quality measure. This is known as mean opinion score (MOS). In addition to this measure there are various objective (quantitative) measures. Most widely used quantitative measures are: mean squared error (MSE), peak signal to noise ratio (PSNR) and signal to noise ratio (SNR). Since these simple measures do not always produce results that are in agreement with subjective evaluation, many other quality measures have been proposed. They are mostly various modifications of MSE, which try to take into account some properties of human visual system (HVS) such as nonlinear character of brightness perception, contrast sensitivity function (CSF) and texture masking. / ABSTRACT: In these approaches quality measure is computed as MSE of input image intensities or frequency domain coefficients obtained after some transform (DFT, DCT etc.), weighted by some coefficients which account for the mentioned properties of HVS. These measures have some advantages over MSE, but their ability to predict image quality is still limited. A different approach is presented here. Quality measure proposed here uses simple model of HVS, which has one user-defined parameter, whose value depends on the reference image. This quality measure is based on the average value of locally computed correlation coefficients. This takes into account structural similarity between original and distorted images, which cannot be measured by MSE or any kind of weighted MSE. The proposed measure also differentiates between random and signal dependant distortion, because these two have different effect on human observer. / ABSTRACT: This is achieved by computing the average correlation coefficient between reference image and error image. Performance of the proposed quality measure is illustrated by examples involving images with different types of degradation. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

<p>This study is a thesis for the Master of Science degree in Media Technology and Engineering at the Department of Science and Technology, Linkoping University. It was accomplished from November 2002 to May 2003. </p><p>Objective image quality measures play an important role in various image processing applications. In this paper quality measures applied on halftoned images are aimed to be in focus. Digital halftoning is the process of generating a pattern of binary pixels that create the illusion of a continuous- tone image. Algorithms built on this technique produce results of very different quality and characteristics. To evaluate and improve their performance, it is important to have robust and reliable image quality measures. This literature survey is to give a general description in digital halftoning and halftone image quality methods.</p>

Made available in DSpace on 2015-05-14T13:16:34Z (GMT). No. of bitstreams: 1 arquivototal.PDF: 1526331 bytes, checksum: 38e40aec6b111371aebd1a5cba081a3c (MD5) Previous issue date: 2009-04-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Epilepsy is a brain dysfunction characterized by the repeated tendency of the brain to cause epileptic crisis and by the neurobiological, cognitive, psychological and social consequences of this condition. In these terms, the aim of this work is to determine the visual sensory threshold of children and adolescents who have and who do not have epilepsy, analyzing possible alterations in the form related to this dysfunction. The sensory threshold is defined as the smallest intensity of incentive a human being is capable of detecting. The contrast sensitivity function (CSF) is the inverse of the threshold curve of contrast (1/CSF). This way, the CSF is a tool that allows us to label the answer of SV to visual patterns in low, medium and high levels of contrast and evaluate possible sensorial alterations associated with the visual processing. The main idea is that the elevation or reduction of the CSF can happen deem to sensorial, cognitive and behavioral alterations. Twenty volunteers participated on this study, from both genders, between 7 and 17 years of age, 10 of whom nonepileptic and 10 epileptic (tonic-clonic crisis). All of them presented either normal or corrected visual accuracy and were distributed in groups that were equivalent in age. The resolutions were taken from the psychophysical forced-choice method, using the static sine wave gratings with spatial frequencies of 0.25, 2.0 and 8.0 cpd (cycles per degree of visual angle). During each experimental session, there were stimulus pares presented randomly (test stimulus and neutral), and the task of the participants was to choose always the test stimulus with one of the frequencies above. The criterion used was the one of three consecutive correct answers to low the contrast in one unity and just one mistake to increase the contrast in the same unity (20%). After each session, a sheet of results with the experimental situation was released and the six values of contrast were calculated by the reversions. The values of contrast obtained to each frequency were grouped in spreadsheets separated by condition (with or without epilepsy) and the big average was used as an estimative of the sensory threshold or of the sensibility to the contrast due to each spatial frequency tested. The analysis of variance (ANOVA) to repeated measures showed significant differences between the groups [F(1,238) = 11.80); p<0.01]. The analysis obtained with the help of the test posthoc Tukey HSD revealed a relevant dissimilarity only in the 0.25cpg (p<0.01)]. In other words, the results indicated an expressive alteration in the visual perception children and adolescents with epilepsy have. / A epilepsia é um distúrbio cerebral caracterizado pela predisposição persistente do cérebro para gerar crises epilépticas e pelas conseqüências neurobiológicas, cognitivas, psicológicas e sociais desta condição. Algumas pesquisas demonstram que distúrbios visuais são bastante freqüentes em pessoas com epilepsia. Nestes termos, o objetivo deste trabalho foi determinar o limiar sensório visual de crianças e adolescentes com e sem epilepsia, verificando possíveis alterações na percepção visual da forma relacionadas a este transtorno. O limiar sensório é definido como a menor intensidade de um estímulo que um ser humano é capaz de detectar. A função de sensibilidade ao contraste (FSC) é o inverso da curva de limiar de contraste (1/FSC). Assim, a FSC é uma ferramenta que permite caracterizar a resposta do SV para padrões visuais em níveis baixos, médios e altos de contraste e avaliar possíveis alterações sensoriais relacionadas ao processamento visual. A idéia principal é que a elevação ou redução da FSC pode está relacionada a alterações sensoriais, cognitivas e comportamentais. Participaram deste estudo, 20 voluntários de ambos os sexos com idades entre 7 e 17 anos, sendo 10 sem epilepsia e 10 com epilepsia (crises tônicoclônicas). Todos apresentavam acuidade visual normal ou corrigida e foram distribuídos pelos grupos atendendo ao critério de equivalência de idade. As medidas foram realizadas com o método psicofísico da escolha forçada, utilizando grade senoidal vertical estática com freqüências espaciais de 0,25; 2,0 e 8,0 cpg (ciclos por grau de ângulo visual). Durante cada sessão experimental, foram apresentados aleatoriamente pares de estímulos (estímulo de teste e neutro), e a tarefa dos participantes foi escolher sempre o estímulo de teste com uma das freqüências acima. O critério adotado foi o de três acertos consecutivos para diminuir o contraste em uma unidade, e apenas um erro para aumentar o contraste na mesma unidade (20%). Após cada sessão, o programa produzia uma folha de resultados com a situação experimental e os seis valores de contraste conseguidos pelas reversões. Os valores de contraste obtidos para cada freqüência foram agrupados em planilhas por condição (com e sem epilepsia) e a grande média foi utilizada como estimativa do limiar sensório ou da sensibilidade ao contraste em função de cada freqüência espacial testada. A análise de variância (ANOVA) para medidas repetidas mostrou diferenças significantes entre os dois grupos [F(1, 238) =11,80); p < 0,01]. Já a análise com o teste post-hoc Tukey HSD revelou diferença significante apenas na faixa de freqüências de 0,25 cpg (p < 0,01). Em termos gerais, os resultados demonstraram alteração significante na percepção visual da forma de crianças e adolescentes com epilepsia.

This study is a thesis for the Master of Science degree in Media Technology and Engineering at the Department of Science and Technology, Linkoping University. It was accomplished from November 2002 to May 2003. Objective image quality measures play an important role in various image processing applications. In this paper quality measures applied on halftoned images are aimed to be in focus. Digital halftoning is the process of generating a pattern of binary pixels that create the illusion of a continuous- tone image. Algorithms built on this technique produce results of very different quality and characteristics. To evaluate and improve their performance, it is important to have robust and reliable image quality measures. This literature survey is to give a general description in digital halftoning and halftone image quality methods.

Dans cette thèse, nous proposons des solutions pour la conception de systèmes de contrôle actif de vibration robustes (AVC). Le manuscrit de thèse comporte deux grandes parties.Dans la première, les problèmes d'incertitude paramétrique dans les systèmes de contrôle actif de vibration sont étudiés. En plus des incertitudes sur la fréquence des perturbations, nous avons trouvé que la présence de zéros complexes peu amortis soulevait des problèmes de conception difficiles, même pour des systèmes et des modèles parfaitement connus. Dans ce contexte, nous avons proposé des solutions pour le problème linéaire. Une procédure améliorée d'identification en boucle fermée a été développée pour réduire les incertitudes dans l'identification de ces zéros. Pour traiter les incertitudes sur la perturbation, l'adaptation de la fréquence est de toute façon incontournable.La seconde partie est consacrée au développement et/ou à l'amélioration de deux algorithmes, désormais classiques, de compensation par feedback adaptatif direct, fondés sur la paramétrisation de Youla-Kučera. Le premier résulte de l'amélioration d'un précédent travail (Landau et al., 2005) ; les contributions concernent la synthèse du contrôleur central robuste et l'utilisation optionnelle de la surparamétrisation du filtre Q-FIR (réponse à temps fini) avec pour effet de minimiser l'effet « waterbed » sur la fonction de sensibilité de sortie. Le second algorithme présente une structure hybride directe/indirecte qui utilise un filtre Q-IIR (à temps de réponse infini). Les améliorations sont dues principalement au dénominateur du filtre, obtenu à partir d'une estimation de la perturbation. Cette solution permet également de simplifier la conception du contrôleur central.Les algorithmes ont été testés, comparés et validés sur un procédé réel du laboratoire Gipsa-lab, dans le cadre d'un benchmark international. / In this thesis, solutions for the design of robust Active Vibration Control (AVC) systems are presented. The thesis report is composed of two main parts.In the first part of the thesis uncertainties issues in Active Vibration Control systems are examined. In addition of the uncertainties on the frequency of the disturbances it has been found that the presence of low damped complex zeros raise difficult design problems even if plant and models are perfectly known. Solutions for the linear control in this context have been proposed. In order to reduce the uncertainties in the identification of low complex zeros and improved closed loop identification procedure has been developed. To handle the uncertainties on the disturbance frequency adaptation has any way to be used.The second part is concerned with the further development and/or the improvement of the now classical direct adaptive feedback compensation algorithms using Youla Kucera controller parametrization. Two new solutions have been proposed in this context. The first one results from the improvement of a previous work (Landau et al., 2005). The contributions are a new robust central controller design to the optional use of over parameterization of the Q-FIR filter which aims to ensure a small waterbed effect for the output sensitivity function and therefore reducing the unwanted amplification. The second algorithm presents a mixed direct/indirect structure which uses a Q-IIR filter. The improvements are mainly the effect of the Q filter denominator, which is obtained from a disturbance identification. This solution in addition drastically simplifies the design of the central controller.The algorithms have been tested, compared and validated on an international benchmark setup available at the Control System Department of GIPSA-Lab, Grenoble, France.

This master‘s thesis deals with the design of modern process control algorithms suitable for SISO industrial control equipments. In this thesis the analysis of the controller design methodology using Mixed-sensitivity function is described. This method consists in shaping frequency characteristics of the sensitivity function and complementary sensitivity fiction using the weighting functions. The proposed H controllers are compared with the classical structure of a discrete PID controller with filtered derivative part. The proposed controllers are compared in terms of robustness, performance, complexity of the design and requirements necessary for their practical application (anti-windup, smooth switchover). Robustness of the controller is evaluated on the basis of modulus stability margin. Estimation of model´s parameters is solved least-square method. The proposed control system consists of an industrial PC and Automation Panel from the company B&R, decentralized system I/O and the real plant. Visualization for control workplace was created in the program Automation studio. This visualization is used to the easy transfer of information from a controlled process.

La courbe de sensibilité au contraste – la façon selon laquelle la sensibilité diffère selon les fréquences spatiale – a été mesurée pour la première fois en 1956 (Schade, 1956). Elle diffère d’individu en individu et, quoiqu’elle ait été observée pour la première fois il y a plus de 60 ans, certains facteurs ayant un impact sur ces différences individuelles sont mal compris. La figure de Campbell-Robson est une grille sinusoïdale dont la fréquence spatiale varie sur l’axe des x et le contraste varie sur l’axe des y, de sorte que l’observateur perçoit une courbe directement sur la figure. Si cette figure contenait de l’information sur la courbe de sensibilité au contraste d’un individu, elle aurait pu être utilisée pour développer une méthode rapide permettant de mesurer la courbe de sensibilité au contraste. Or, les résultats de l’article 1 montrent qu’il n’existe que peu d’information à propos de la courbe de sensibilité au contraste dans la figure de Campbell-Robson. La maturation de la sensibilité au contraste n’est pas bien comprise. Puisque les études antérieures ont utilisé, entre autres, des méthodes et des tâches différentes, les résultats rapportés par ces études sont contradictoires. Nous nous sommes penchés sur la question dans l’article 2 en utilisant une méthode objective pour mesurer la sensibilité au contraste pour une grande étendue de fréquences spatiales (0.5 à 30 cycles par degré) et une grande étendue d’âges (4 à 27 ans). Au lieu d’utiliser l’âge comme variable catégorielle en séparant les participants en groupes, nous avons utilisé une méthode de régression locale (LOESS) pour utiliser l’âge comme variable continue et ainsi obtenir plus de précision sur l’âge de maturation. Les résultats montrent que la sensibilité devient semblable à celle d’un adulte autour de 12 ans pour les fréquences spatiales basses et hautes, et autour de 17 ans pour les fréquences spatiales moyennes. Après l’âge, la culture dans laquelle une personne grandit est un autre facteur pouvant avoir un impact sur la sensibilité au contraste. Dans l’article 3, nous avons vérifié l’effet de la culture sur la courbe de sensibilité au contraste en la mesurant de deux manières différentes chez des participant.es chinois.es et canadien.nes. Les résultats montrent que la courbe de sensibilité au contraste ne semble pas être différente chez les deux cultures. Compte tenu de différences interculturelles dans les fixations oculaires sur les visages, nous avons vérifié s’il existe des différences dans les fréquences spatiales contenues dans la représentation interne des visages chez les deux cultures. Nos résultats montrent que les participant.es chinois.es utilisent de plus basses fréquences spatiales et les participant.es canadien.nes utilisent de plus hautes fréquences spatiales pour reconnaître les visages. En somme, les résultats présentés dans cette thèse permettent de mieux comprendre les différences individuelles dans la sensibilité au contraste. / The contrast sensitivity function – the curve defining the way in which sensitivity differs according to spatial frequencies – was first measured in 1956 (Schade, 1956). The contrast sensitivity function differs from person to person and, although it was observed over 60 years ago, some factors which have an impact on these individual differences are not well understood. The Campbell-Robson figure is a sinusoidal grating on which the spatial frequency varies on the x axis and contrast varies on the y axis, resulting in a perceived curve, between the grating and the perceived gray area of the grating, directly on the figure. If this figure contained information on the contrast sensitivity function, it would have been useful to develop a quick method to measure it. However, the results of article 1 show that there is little information on the contrast sensitivity function contained in the Campbell-Robson chart. The way in which contrast sensitivity matures is not well understood. Because anterior studies used, among other things, different methods and tasks, the results they report vary greatly and are often contradictory. We have studied the question in article 2, using an objective method to measure contrast sensitivity for a large array of spatial frequencies (0.5 to 30 cycles per degree) and a large span of ages (4 to 27 years). Instead of using age as a categorial variable by separating the participants in age bins, we used a local regression technique (LOESS) in order to use age as a continuous variable and obtain a more precise estimate of the maturation age of contrast sensitivity. Results show that sensitivity becomes similar to an adult’s around 12 years old for low and high spatial frequencies, and around 17 years old for mid-range spatial frequencies. Other than age, the culture in which a person grows up is another factor that could have an impact on contrast sensitivity. In article 3, we verified the effect of culture on the contrast sensitivity function by measuring it using two different methods in Chinese and Canadian participants. Results don’t show that the contrast sensitivity function differs between the two cultures. Because of intercultural differences in ocular fixations on faces, we further verified if there are differences in the spatial frequencies contained in the internal representations of faces in the two cultures. Our results show that Chinese participants use lower spatial frequencies and Canadian participants use higher spatial frequencies when identifying faces. In sum, the results presented in this thesis help better understand individual differences in contrast sensitivity.

В работе рассматриваются двумерная популяционная модель типа «хищник–жертва» с учетом конкуренции жертв и конкуренции хищников за отличные от жертв ресурсы, а также трехмерная популяционная модель типа «хищник–две жертвы» с учетом внутривидовой и межвидовой конкуренции жертв и конкуренции хищников за отличные от жертв ресурсы. Проводится анализ существования и устойчивости аттракторов моделей, строятся бифуркационные диаграммы и типичные фазовые портреты. Для стохастических моделей проводится анализ чувствительности аттракторов на основе теории функции стохастической чувствительности. С использованием аппарата доверительных областей: эллипсов и эллипсоидов для равновесий, а также полос и торов – для циклов, изучаются стохастические феномены: переходы между аттракторами, генерация большеамлитудных колебаний, вымирание популяций. Изучаются вероятностные механизмы вымирания популяций. / The thesis considers a two-dimensional population model of the «predator–prey» type, taking into account the competition of preys and competition of predators for resources different from the preys, and also a three-dimensional population model of the «predator–two preys» type, with intraspecific and interspecific competition of preys and competition predators for resources other than preys. An analysis is made of the existence and stability of attractors. Bifurcation diagrams and typical phase portraits are constructed. For stochastic models, an analysis of the sensitivity of attractors is carried out based on stochastic sensitivity function teqnique. Using the confidence domain method: ellipses or ellipsoids for equilibria and bands or tor for cycles, following stochastic phenomena are studied: transitions between attractors, the generation of large amplitude oscillation and the extinction of populations. The probabilistic mechanisms of extinction of populations are studied.

Работа содержит описание построения доверительной полосы стохастического хаоса и реализацию алгоритмов исследования n-мерных моделей. В работе рассматривается дискретная модель, представленная в виде нелинейной динамической системы разностных уравнений, которая описывает динамику взаимодействия потребителей. Выделяются две задачи, которые были поставлены и выполнены в рамках данной работы для расширения программного инструментария исследования динамических систем такого рода. Для двумерного случая осуществляется стохастический анализ чувствительности хаоса через построение доверительной области с использованием критических линий. Помимо этого, описывается разработанный и реализованный алгоритм построения внешней границы хаоса. Производится переход к n-мерному варианту модели (взаимодействие n потребителей). Выделяется 4 алгоритма для исследования n-мерной модели: 1. построение фазовой траектории, 2. построение бифуркационной диаграммы, 3. построение карты режимов, 4. построение показателей Ляпунова. Описывается реализация данных алгоритмов с уклоном в параллельные вычисления. Реализация алгоритмов выполнена на языке программирования C# (платформа .NET) в виде консольного приложения для запуска параллельных вычислений на вычислительном кластере УрФУ. / The work contains description of confidence band construction of a stochastic chaos and realization of algorithms for n-dimensional models studying. The thesis considers a discrete model presented in the form of a nonlinear dynamic system of difference equations, which describes the dynamic of consumer interaction. There are two task that were set and performed in this work to expand the software tools for research dynamic sys-tems of this kind. For the two-dimensional case, a stochastic analysis of the sensitivity of chaos is carried out through the construction of a confidence band using critical lines. In addition, there is description and implementation of algorithm, that can build outer boundary of chaos. A transition is made to the n-dimensional version of the model (interaction of n consumers). There are 4 algorithms for studying the n-dimensional model: 1. phase trajectory building, 2. bifurcation diagram building, 3. mode map building, 4. Lyapunov components building. Algorithm implementation is described with a bias in parallel computations. The algorithms are implemented with C# programming language (.NET platform) in the form of a console application for running parallel computations on the computing cluster of the Ural Federal University.

This thesis describes a novel method to reversibly and safely block nerve conduction using a low frequency alternating current (LFAC) waveform at 1 Hz applied through a bipolar extrafascicular electrode. This work follows up on observations made on excised mammalian peripheral nerves and earthworm nerve cords. An<i> in-situ</i> electrophysiology setup was used to assess the LFAC<br>waveform on propagating action potentials (APs) within the cervical vagus nerve in anaesthetized Sprague-Dawley rats (n = 12). Two sets of bipolar cuff or hook electrodes were applied unilaterally to the cervical vagus nerve, which was crushed rostral to the electrodes to exclude reflex effects<br>on the animal. Pulse stimulation was applied to the rostral electrode, while the LFAC conditioning waveform was applied to the caudal electrode. The efferent volley, if unblocked, elicits acute bradycardia and hypotension. The degree of block of the vagal stimulation induced bradycardia<br>was used as a biomarker. Block was assessed by the ability to reduce the bradycardic drive by monitoring the heart rate (HR) and blood pressure (BP) during LFAC alone, LFAC with vagal stimulation, and vagal stimulation alone. LFAC applied via a hook electrode (n = 7) achieved 86.6 +/- 11% block at current levels 95 +/- 38 uAp (current to peak). When applied via a cuff electrode (n = 5) 85.3 +/- 4.60% block was achieved using current levels of 110 +/- 65 uAp. Furthermore, LFAC was explored on larger vagal afferent fibers in larger human sized nerve bundles projecting to effects mediated by a reflex. The effectiveness of LFAC was assessed in an <i>in-situ</i> electrophysiological setup on the left cervical vagus in anaesthetized domestic swine (n = 5). Two bipolar cuff electrodes were applied unilaterally to the cervical vagus nerve, which was crushed caudal to the electrodes to eliminate cardiac effects. A tripolar extrafascicular cuff electrode was placed most rostral on the nerve for recording of propagating APs induced by<br>electrical stimulation and blocked via the LFAC waveform.<br>Standard pulse stimulation was applied to the left cervical vagus to induce the Hering-Breuer reflex. If unblocked, the activation of the Hering-Breuer reflex would cause breathing to slow down and potentially cease. Block was quantified by the ability to reduce the effect of the Hering-Breuer<br>reflex by monitoring the breathing rate during LFAC alone, LFAC and vagal stimulation, and vagal stimulation alone. LFAC achieved 87.2 +/- 8.8% (n = 5) block at current levels of 0.8 +/- 0.3 mAp. Compound nerve action potentials (CNAP) were monitored directly. They show changes<br>in nerve activity during LFAC, which manifests itself as the slowing and amplitude reduction of components of the CNAPs. Since the waveform is balanced, all forward reactions are reversed, leading to a blocking method that is similar in nature to DC block without the potential issues of<br>toxic byproduct production. These results suggest that LFAC can achieve a high degree of nerve block in both small and large nerve bundles, resulting in the change in behavior of a biomarker, <i>in-vivo </i>in the mammalian nervous system at low amplitudes of electrical stimulation that are within the water window of the electrode.<br>