Le principe d’individualisation de la sanction pénale constitue, aujourd’hui, la pierre angulaire du droit pénal et de la procédure pénale française. Toutefois, un courant de pensée contemporain issu du mouvement américain Law and Economics a émergé progressivement en France. Celui-ci serait le seul à pouvoir apporter une réponse pertinente aux questions juridiques contemporaines, en se fondant sur le pragmatisme et l’efficacité. Cette logique a d’abord investi la procédure pénale, mais le droit de la peine n’y échappe pas. L’efficacité d’une mesure renvoie à un objectif atteint, c’est-à-dire l’absence de réitération d’infractions. Alors, comment l’individualisation de la peine peut-elle permettre d’accroître l’efficacité de la sanction pénale ? En effet, celle-ci doit permettre de rendre la peine équitable pour lui donner du sens. Ainsi, les différents législateurs n’ont eu de cesse de diversifier les mesures pouvant être prononcées par le juge, afin d’accompagner les délinquants et de les ramener à la vie collective. La doctrine considère qu’une peine est plus efficace lorsque le délinquant participe à la mesure ; il est donc possible d’en développer de nouvelles, qui permettront de responsabiliser le délinquant, en s’inspirant des mesures de justice restaurative, et en modifiant le prononcé de la peine. La césure du procès pénal permettrait ainsi de se diriger vers une peine juste, équitable et à la fois individualisée. / The principle of individualization of the punishment establishes, today, the cornerstone of the criminal law and the French criminal procedure. However, a contemporary current of thought from the American movement Law and Economics emerged gradually in France. This current would be the only one able to bring a relevant answer to the contemporary legal issues, basing itself on pragmatism and efficiency. This logic first invested the criminal procedure but the right of the punishment doesn’t escape it. The efficiency of a measure sends back to a reached objective, that is the absence of repetitive offenses. Then, how the sentencing according to the characteristics of the offender can allow to increase the efficiency of the punishment? Indeed, it shall allow the punishment to be fair and to give it meaning. For that purpose, the various legislators never stopped diversifying the measures which can be rendered by the judge to accompany offenders and bring them back in community life. This doctrine considers that a punishment is more effective when the offender takes part in the measure. It is therefore possible to develop new measures allowing to give offenders responsibilities, taking inspiration in measures of restorative justice, and to modify the render of the punishment. The césure of the penal trial would allow to head for a just punishment, fair and personalized.

Ao longo dos últimos 20 anos, o modelo de concessão de serviço público no Brasil, tem evoluído consideravelmente, com destaque para o setor elétrico, e especialmente o segmento de transmissão de energia elétrica. O arcabouço normativo vigente tem buscado garantir a prestação adequada do serviço mediante a avaliação de desempenho do serviço prestado, por empresas públicas ou privadas, numa visão da qualidade do produto e da continuidade ou disponibilidade do serviço para o usuário. Concomitantemente, surgiu e desenvolveu-se rápida e globalmente, o conceito de sustentabilidade, no qual o desenvolvimento sustentável deve satisfazer as necessidades da geração atual, sem que se comprometam as necessidades das gerações futuras (World Comission on Environment and Development WCED), compreendendo essencialmente as três dimensões econômica, social e ambiental (conceito de Triple Bottom Line 3BL), permitindo a captura do impacto das atividades das empresas e organizações por meio de indicadores definidos para cada uma das três dimensões. Ainda, nesse contexto, desenvolveu-se as novas técnicas de planejamento estratégico e de gestão de desempenho, baseados em indicadores, com destaque para a Teoria das Partes Interessadas (Stakeholders). Adicionalmente, os diversos métodos de avaliação econômica e de demonstração contábil das empresas também realizaram um movimento de convergência internacional, principalmente, para aplicação de análise de risco e de avaliação do valor adicionado, com uso do fluxo de caixa dos benefícios esperados, incluído o período da perpetuidade ou valor residual/terminal; e de padrões contábeis internacionais (a IFRIC 12), que altera a estrutura de composição do ativo, uma vez que a norma não permite o reconhecimento da infraestrutura relacionada à concessão no ativo imobilizado das concessionárias, prática atualmente comum no Brasil. Nesse contexto, o presente trabalho propõe a formulação de um novo indicador para a prestação do serviço público de transmissão de energia elétrica, a partir das informações sistematizadas nos Procedimentos de Rede do Operador Nacional do Sistema Elétrico (ONS) referentes aos diversos indicadores de desempenho apurados para a operação e manutenção da transmissão de energia elétrica, visando facilitar o acompanhamento da gestão dos ativos físicos, quanto aos requisitos contratuais de atualidade e conservação do serviço adequado, mediante a avaliação da perda ou ganho na expectativa de vida útil dos componentes ou das funções de transmissão, a partir de uma idade determinada, ou seja, indicador de longevidade dos ativos físicos da concessão de transmissão de energia elétrica. Além disso, este mesmo indicador de longevidade pode ser usado na avaliação do valor de perpetuidade (estimativa do valor terminal) de empresas, quer pelo método tradicional de projeção dos fluxos de caixa descontado da perpetuidade ou pela simples abordagem comparativa da expectativa de vida útil ao final do período de concessão dos prestadores do serviço público. / Over the past 20 years, the model of public service concessions in Brazil, has evolved considerably, especially in the electricity sector, and the transmission segment of electricity. The existing regulatory framework has sought to ensure the proper provision of the service through the performance evaluation of the service provided by public or private, in view of product quality and continuity of service or availability to the user. Concomitantly, emerged and developed rapidly and globally, the concept of sustainability, in which \"sustainable development should meet the needs of present generation without compromising the needs of future generations\" (World Commission on Environment and Development - WCED) comprising essentially three economic, social and environmental (concept of Triple Bottom Line - 3BL), allowing you to capture the impact of corporate activities and organizations by means of indicators defined for each of the three dimensions. Still, in this context, new techniques of strategic planning and performance management were developed, based on indicators, notably the Theory of Stakeholders. Additionally, the various methods of economic evaluation and financial statement of companies have also made a movement of international convergence, especially for application of risk analysis and assessment of value added, using the cash flow of the expected benefits, including the period perpetuity or the residual value or terminal value, and international accounting standards (IFRIC 12), which alters the structure of asset composition, since the standard does not permit the recognition of infrastructure related to the granting of fixed assets in utilities, currently common practice in Brazil. In this context, this paper proposes the formulation of a new indicator for the provision of public electric power transmission, from the systematic information in the Grid Procedures of the Operador Nacional do Sistema Elétrico (ONS) for the different performance indicators established for the operation and maintenance of electric power transmission, to facilitate monitoring of the management of physical assets, the contractual requirements of current conservation and appropriate service, by assessing the loss or gain in life expectancy of the components or the functions transmission, from a certain age, ie, an indicator of longevity of the physical assets of the granting of electric power transmission. Furthermore, this same indicator of longevity can be used in assessing the value of perpetuity (estimated terminal value) of companies or by the traditional method of projection of cash flows discounted perpetuity or for the simple approach of comparative life expectancy of the end of the concession of public service providers.

My dissertation critiques Western culture’s vertical command of “growing up” to adult completion (rational, heterosexual, married, wealthy, professionally successful) as a reductionist itinerary of human movement leading to subjective sedimentations. Rather, my project proposes ways of “moving rhizomatically” by which it advances a notion of a machinic identity that moves continuously, contingently, and waywardly along less vertical, less excruciating and more horizontal, life-affirmative trails. To this end, my thesis proposes a “rhizomatic semiosis” as extrapolated from the philosophy of Gilles Deleuze and Félix Guattari to put forward a notion of language and, by implication, subjectivity, as dynamic and metamorphic. Rather than trying to figure out who the child is or what it experiences consciously, my project wishes to embrace an elusiveness at the heart of subjectivity to argue for continued identity creation beyond the apparently confining parameters of adulthood. This dissertation, then, is about the need to re-examine our ways of growing beyond the lines of teleological progression. By turning to Deleuze’s child, an intangible one that “makes desperate attempts to carry out a performance that the psychoanalyst totally misconstrues” (A Thousand Plateaus 13), I wish to shift focus away from the hierarchical, binary, and ideal model of “growing up” and toward a notion of movement that makes way for plural identities in their becoming. This endeavour reveals itself in particular in the work of John Wray, Todd Field, Peter Cameron, Sara Prichard, Michael Cunningham, and Cormac McCarthy, whose work has received little or no attention at all—a lacuna in research that exists perhaps due to these artists’ innovative approach to a minor literature that promotes the notion of a machinic self and questions the dominant modes of Western culture’s literature for, around, and of children.

As a consequence of the recent deregulation in the electrical power production industry, there has been a shift in the traditional ownership of power plants and the way they are operated. To hedge their business risks, the many new private entrepreneurs enter into long-term service agreement (LTSA) with third parties for their operation and maintenance activities. As the major LTSA providers, original equipment manufacturers have invested huge amounts of money to develop preventive maintenance strategies to minimize the occurrence of costly unplanned outages resulting from failures of the equipments covered under LTSA contracts. As a matter of fact, a recent study by the Electric Power Research Institute estimates the cost benefit of preventing a failure of a General Electric 7FA or 9FA technology compressor at $10 to $20 million. Therefore, in this dissertation, a two-phase data analytics approach is proposed to use the existing monitoring gas path and vibration sensors data to first develop a proactive strategy that systematically detects and validates catastrophic failure precursors so as to avoid the failure; and secondly to estimate the residual time to failure of the unhealthy items. For the first part of this work, the time-frequency technique of the wavelet packet transforms is used to de-noise the noisy sensor data. Next, the time-series signal of each sensor is decomposed to perform a multi-resolution analysis to extract its features. After that, the probabilistic principal component analysis is applied as a data fusion technique to reduce the number of the potentially correlated multi-sensors measurement into a few uncorrelated principal components. The last step of the failure precursor detection methodology, the anomaly detection decision, is in itself a multi-stage process. The obtained principal components from the data fusion step are first combined into a one-dimensional reconstructed signal representing the overall health assessment of the monitored systems. Then, two damage indicators of the reconstructed signal are defined and monitored for defect using a statistical process control approach. Finally, the Bayesian evaluation method for hypothesis testing is applied to a computed threshold to test for deviations from the healthy band. To model the residual time to failure, the anomaly severity index and the anomaly duration index are defined as defects characteristics. Two modeling techniques are investigated for the prognostication of the survival time after an anomaly is detected: the deterministic regression approach, and parametric approximation of the non-parametric Kaplan-Meier plot estimator. It is established that the deterministic regression provides poor prediction estimation. The non parametric survival data analysis technique of the Kaplan-Meier estimator provides the empirical survivor function of the data set comprised of both non-censored and right censored data. Though powerful because no a-priori predefined lifetime distribution is made, the Kaplan-Meier result lacks the flexibility to be transplanted to other units of a given fleet. The parametric analysis of survival data is performed with two popular failure analysis distributions: the exponential distribution and the Weibull distribution. The conclusion from the parametric analysis of the Kaplan-Meier plot is that the larger the data set, the more accurate is the prognostication ability of the residual time to failure model.

The aim of the study was to find benefits derived from the natural propagation and the use of guava plants and fruit by people living in rural areas of KwaZulu-Natal, looking at guava as a source of food, income, medicinal uses, shade, a source of fuel and use for agricultural purposes like fencing; and also assessing Conservation of the Agricultural Resource Act (CARA), Act 43 of 1983 relating to guava plant as invasive species. The Act states that all alien invader species and weeds should be controlled or removed depending on the category. CARA states that plants in category one are declared as alien invasive plants and are not allowed to grow on the land or appear on the water surface. Plants under this category may not be transported or allowed to disperse e.g. Psidium x durbanensis (Durban guava). Category two plants are invader species that have a potential value, plants that are used by the people as a source of income and food. These species can be retained if they grow in special areas demarcated for the purpose (an orchard). If these species are found outside demarcated areas they are to be removed e.g. Psidium guava (guava). Category three species are mostly plants with ornamental value which are not allowed to occur anywhere unless they were already in existence when the regulation came into effect e.g. Psidium guineense (brazillian guava) and Psidium cattleianum (strawberry guava). The study focused on selected areas of KwaZulu-Natal,: Umgungundlovu district municipality (Richmond local municipality) and Uthungulu district municipality. Richmond represented the midlands areas and Uthungulu the coastal areas to reflect two different areas of KwaZulu-Natal. To investigate this study the researcher used telephonic interviews with 23 Extension officials, questionnaires to guide focus group discussions which were conducted with 28 community groups that were involved in guava usage. Informal observation surveys were also carried out with five markets (stall holders) selling guava and guava products. Informal observations in two supermarkets and two home industries were also conducted. The results showed that people in rural areas still use this resource (guava) as a source of fuel (wood), medicine (especially the leaves and bark), fruit for own consumption (either processed or raw) and income generation. The impact of the legislation on rural poor communities is negative as guavas sustain livelihoods and the costs of applying for permits are prohibitive. People are illiterate yet they have to apply for special permits to plant this useful species because the regulation stipulates that guava plants must be controlled if dispersed outside demarcated areas. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

My dissertation critiques Western culture’s vertical command of “growing up” to adult completion (rational, heterosexual, married, wealthy, professionally successful) as a reductionist itinerary of human movement leading to subjective sedimentations. Rather, my project proposes ways of “moving rhizomatically” by which it advances a notion of a machinic identity that moves continuously, contingently, and waywardly along less vertical, less excruciating and more horizontal, life-affirmative trails. To this end, my thesis proposes a “rhizomatic semiosis” as extrapolated from the philosophy of Gilles Deleuze and Félix Guattari to put forward a notion of language and, by implication, subjectivity, as dynamic and metamorphic. Rather than trying to figure out who the child is or what it experiences consciously, my project wishes to embrace an elusiveness at the heart of subjectivity to argue for continued identity creation beyond the apparently confining parameters of adulthood. This dissertation, then, is about the need to re-examine our ways of growing beyond the lines of teleological progression. By turning to Deleuze’s child, an intangible one that “makes desperate attempts to carry out a performance that the psychoanalyst totally misconstrues” (A Thousand Plateaus 13), I wish to shift focus away from the hierarchical, binary, and ideal model of “growing up” and toward a notion of movement that makes way for plural identities in their becoming. This endeavour reveals itself in particular in the work of John Wray, Todd Field, Peter Cameron, Sara Prichard, Michael Cunningham, and Cormac McCarthy, whose work has received little or no attention at all—a lacuna in research that exists perhaps due to these artists’ innovative approach to a minor literature that promotes the notion of a machinic self and questions the dominant modes of Western culture’s literature for, around, and of children.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Em engenharia, a modelagem computacional desempenha um papel importante na concepção de produtos e no desenvolvimento de técnicas de atenuação de ruído. Nesse contexto, esta tese investiga a intensidade acústica gerada pela radiação sonora de superfícies vibrantes. De modo específico, a pesquisa enfoca a identificação das regiões de uma fonte sonora que contribuem efetivamente para potência sonora radiada para o campo afastado, quando a frequência de excitação ocorre abaixo da frequência crítica de coincidência. São descritas as fundamentações teóricas de duas diferentes abordagens. A primeira delas, denominada intensidade supersônica (analítica) é calculada via transformadas de Fourier para fontes sonoras com geometrias separáveis. A segunda, denominada intensidade útil (numérica) é calculada através do método dos elementos de contorno clássico para fontes com geometrias arbitrárias. Em ambas, a identificação das regiões é feita pela filtragem das ondas não propagantes (evanescentes). O trabalho está centrado em duas propostas, a saber. A primeira delas, é a apresentação implementação e análise de uma nova técnica numérica para o cálculo da grandeza intensidade útil. Essa técnica constitui uma variante do método dos elementos de contorno (MEC), tendo como base o fato de as aproximações para as variáveis acústicas pressão e velocidade normal serem tomadas como constantes em cada elemento. E também no modo peculiar de obter a velocidade constante através da média de um certo número de velocidades interiores a cada elemento. Por esse motivo, a técnica recebe o nome de método de elemento de contorno com velocidade média (AVBEMAverage Velocity Boundary Element Method). A segunda, é a obtenção da solução forma fechada do campo de velocidade normal para placas retangulares com oito diferentes combinações de condições contorno clássicas. Então, a intensidade supersônica é estimada e comparada à intensidade acústica. Nos ensaios numéricos, a comparação da intensidade útil obtida via MEC clássico e via AVBEM é mostrada para ilustrar a eficiência computacional da técnica aqui proposta, que traz como benefício adicional o fato de poder ser utilizada uma malha menos refinada para as simulações e, consequentemente, economia significativa de recursos computacionais. / In engineering computational modeling plays an important role in product design and development techniques for noise attenuation. In such context, this thesis investigates the acoustic intensity generated by sound radiation from vibrating surfaces. Specifically, the research focuses on the identification that effectively contribute to the radiated sound power into the far-field, especially when the driven frequency occurs below the critical coincidence frequency. The theoretical formulations of two different approaches are described. The first one, called supersonic intensity (analytical) is calculated via Fourier transforms for noise sources with separable geometries. The second, called useful intensity (numerical) is calculated by the method of boundary elements to classic fonts with arbitrary geometries. In both, the identification of regions is done by filtering the non propagating waves (evanescent). The work is focused on the presentation, implementation and analysis of a new numerical technique for calculating the magnitude useful intensity. This technique is a variant of the method-boundary element (BEM), based on the fact that the approximations for the acoustic pressure and normal speed variables are taken as constant in each element. Also in particular way to obtain constant speed by mean of a number of speeds interior of each element. For this reason, the technique is called the Average Velocity Boundary Element Method . The closed form solution of the normal velocity field for rectangular plates in eight cases with distinct combinations of classical boundary conditions is also obtained. Then, the supersonic intensity is estimated and compared to the acoustic intensity. Numerical experiments are performed comparing to the useful intensity via the conventional BEM with theAVBEM in order to illustrate the positive computational features of the method. The numerical results indicate that the proposed method is much more computationally effcient than its standard BEM counterpart, it enabling the use of a coarser mesh.

La maintenance prédictive joue un rôle important dans le maintien des systèmes de production continue car elle peut aider à réduire les interventions inutiles ainsi qu'à éviter des pannes imprévues. En effet, par rapport à la maintenance conditionnelle, la maintenance prédictive met en œuvre une étape supplémentaire, appelée le pronostic. Les opérations de maintenance sont planifiées sur la base de la prédiction des états de détérioration futurs et sur l'estimation de la vie résiduelle du système. Dans le cadre du projet européen FP7 SUPREME (Sustainable PREdictive Maintenance for manufacturing Equipment en Anglais), cette thèse se concentre sur le développement des modèles de détérioration stochastiques et sur des méthodes d'estimation de la vie résiduelle (Remaining Useful Life – RUL en anglais) associées pour les adapter aux cas d'application du projet. Plus précisément, les travaux présentés dans ce manuscrit sont divisés en deux parties principales. La première donne une étude détaillée des modèles de détérioration et des méthodes d'estimation de la RUL existant dans la littérature. En analysant leurs avantages et leurs inconvénients, une adaptation d’une approche de l'état de l'art est mise en œuvre sur des cas d'études issus du projet SUPREME et avec les données acquises à partir d’un banc d'essai développé pour le projet. Certains aspects pratiques de l’implémentation, à savoir la question de l'échange d'informations entre les partenaires du projet, sont également détaillées dans cette première partie. La deuxième partie est consacrée au développement de nouveaux modèles de détérioration et les méthodes d'estimation de la RUL qui permettent d'apporter des éléments de solutions aux problèmes de modélisation de détérioration et de prédiction de RUL soulevés dans le projet SUPREME. Plus précisément, pour surmonter le problème de la coexistence de plusieurs modes de détérioration, le concept des modèles « multi-branche » est proposé. Dans le cadre de cette thèse, deux catégories des modèles de type multi-branche sont présentées correspondant aux deux grands types de modélisation de l'état de santé des système, discret ou continu. Dans le cas discret, en se basant sur des modèles markoviens, deux modèles nommés Mb-HMM and Mb-HsMM (Multi-branch Hidden (semi-)Markov Model en anglais) sont présentés. Alors que dans le cas des états continus, les systèmes linéaires à sauts markoviens (JMLS) sont mis en œuvre. Pour chaque modèle, un cadre à deux phases est implémenté pour accomplir à la fois les tâches de diagnostic et de pronostic. A travers des simulations numériques, nous montrons que les modèles de type multi-branche peuvent donner des meilleures performances pour l'estimation de la RUL par rapport à celles obtenues par des modèles standards mais « mono-branche ». / Predictive maintenance plays a crucial role in maintaining continuous production systems since it can help to reduce unnecessary intervention actions and avoid unplanned breakdowns. Indeed, compared to the widely used condition-based maintenance (CBM), the predictive maintenance implements an additional prognostics stage. The maintenance actions are then planned based on the prediction of future deterioration states and residual life of the system. In the framework of the European FP7 project SUPREME (Sustainable PREdictive Maintenance for manufacturing Equipment), this thesis concentrates on the development of stochastic deterioration models and the associated remaining useful life (RUL) estimation methods in order to be adapted in the project application cases. Specifically, the thesis research work is divided in two main parts. The first one gives a comprehensive review of the deterioration models and RUL estimation methods existing in the literature. By analyzing their advantages and disadvantages, an adaption of the state of the art approaches is then implemented for the problem considered in the SUPREME project and for the data acquired from a project's test bench. Some practical implementation aspects, such as the issue of delivering the proper RUL information to the maintenance decision module are also detailed in this part. The second part is dedicated to the development of innovative contributions beyond the state-of-the-are in order to develop enhanced deterioration models and RUL estimation methods to solve original prognostics issues raised in the SUPREME project. Specifically, to overcome the co-existence problem of several deterioration modes, the concept of the "multi-branch" models is introduced. It refers to the deterioration models consisting of different branches in which each one represent a deterioration mode. In the framework of this thesis, two multi-branch model types are presented corresponding to the discrete and continuous cases of the systems' health state. In the discrete case, the so-called Multi-branch Hidden Markov Model (Mb-HMM) and the Multi-branch Hidden semi-Markov model (Mb-HsMM) are constructed based on the Markov and semi-Markov models. Concerning the continuous health state case, the Jump Markov Linear System (JMLS) is implemented. For each model, a two-phase framework is carried out for both the diagnostics and prognostics purposes. Through numerical simulations and a case study, we show that the multi-branch models can help to take into account the co-existence problem of multiple deterioration modes, and hence give better performances in RUL estimation compared to the ones obtained by standard "single branch" models.

Cette thèse porte sur le diagnostic et le pronostic pour l’aide à la maintenance de systèmes complexes. Elle présente deux approches de diagnostic/pronostic qui permettent de générer les indicateurs utiles pour l’optimisation de la stratégie de maintenance. Plus précisément, ces approches permettent d’évaluer l’état de santé et de prédire la durée de vie résiduelle du système. Les approches présentées visent en particulier à pallier le problème d’absence d’indicateurs de dégradation. Les développements sont fondés sur l’utilisation d’observateurs, de formalisme de Modèle de Markov Caché, des méthodes d’inférences statistiques et des méthodes de prédiction de séries temporelles à base d’apprentissage afin de caractériser et prédire les modes de fonctionnement du système. Les deux approches sont illustrées sur des exemples de dégradation d’un système de régulation de niveau d’eau, d’une machine asynchrone et d’une batterie Li-Ion. / The research presented in this thesis deals of diagnosis and prognosis of complex systems. It presents two approaches that generate useful indicators for optimizing maintenance strategies. Specifically, these approaches are used to assess the level of degradation and estimate the Remaining Useful Life of the system. The aim of these approaches is to overcome for the lack of degradation indicators. The developments are based on observers, Hidden Markov Model formalism, statistical inference methods and learning-based methods in order to characterize and predict the system operating modes. To illustrate the proposed failure diagnosis/prognosis approaches, a simulated tank level control system, an induction motor and a Li-Ion battery were used.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Em engenharia, a modelagem computacional desempenha um papel importante na concepção de produtos e no desenvolvimento de técnicas de atenuação de ruído. Nesse contexto, esta tese investiga a intensidade acústica gerada pela radiação sonora de superfícies vibrantes. De modo específico, a pesquisa enfoca a identificação das regiões de uma fonte sonora que contribuem efetivamente para potência sonora radiada para o campo afastado, quando a frequência de excitação ocorre abaixo da frequência crítica de coincidência. São descritas as fundamentações teóricas de duas diferentes abordagens. A primeira delas, denominada intensidade supersônica (analítica) é calculada via transformadas de Fourier para fontes sonoras com geometrias separáveis. A segunda, denominada intensidade útil (numérica) é calculada através do método dos elementos de contorno clássico para fontes com geometrias arbitrárias. Em ambas, a identificação das regiões é feita pela filtragem das ondas não propagantes (evanescentes). O trabalho está centrado em duas propostas, a saber. A primeira delas, é a apresentação implementação e análise de uma nova técnica numérica para o cálculo da grandeza intensidade útil. Essa técnica constitui uma variante do método dos elementos de contorno (MEC), tendo como base o fato de as aproximações para as variáveis acústicas pressão e velocidade normal serem tomadas como constantes em cada elemento. E também no modo peculiar de obter a velocidade constante através da média de um certo número de velocidades interiores a cada elemento. Por esse motivo, a técnica recebe o nome de método de elemento de contorno com velocidade média (AVBEMAverage Velocity Boundary Element Method). A segunda, é a obtenção da solução forma fechada do campo de velocidade normal para placas retangulares com oito diferentes combinações de condições contorno clássicas. Então, a intensidade supersônica é estimada e comparada à intensidade acústica. Nos ensaios numéricos, a comparação da intensidade útil obtida via MEC clássico e via AVBEM é mostrada para ilustrar a eficiência computacional da técnica aqui proposta, que traz como benefício adicional o fato de poder ser utilizada uma malha menos refinada para as simulações e, consequentemente, economia significativa de recursos computacionais. / In engineering computational modeling plays an important role in product design and development techniques for noise attenuation. In such context, this thesis investigates the acoustic intensity generated by sound radiation from vibrating surfaces. Specifically, the research focuses on the identification that effectively contribute to the radiated sound power into the far-field, especially when the driven frequency occurs below the critical coincidence frequency. The theoretical formulations of two different approaches are described. The first one, called supersonic intensity (analytical) is calculated via Fourier transforms for noise sources with separable geometries. The second, called useful intensity (numerical) is calculated by the method of boundary elements to classic fonts with arbitrary geometries. In both, the identification of regions is done by filtering the non propagating waves (evanescent). The work is focused on the presentation, implementation and analysis of a new numerical technique for calculating the magnitude useful intensity. This technique is a variant of the method-boundary element (BEM), based on the fact that the approximations for the acoustic pressure and normal speed variables are taken as constant in each element. Also in particular way to obtain constant speed by mean of a number of speeds interior of each element. For this reason, the technique is called the Average Velocity Boundary Element Method . The closed form solution of the normal velocity field for rectangular plates in eight cases with distinct combinations of classical boundary conditions is also obtained. Then, the supersonic intensity is estimated and compared to the acoustic intensity. Numerical experiments are performed comparing to the useful intensity via the conventional BEM with theAVBEM in order to illustrate the positive computational features of the method. The numerical results indicate that the proposed method is much more computationally effcient than its standard BEM counterpart, it enabling the use of a coarser mesh.