Background: Worldwide, about 300 million people have some kind of visual impairment (VI). Most people with VI are in the older age range, as visual deficits increase with age. It is not unusual that people with VI suffer both from neck pain or scapular area symptoms and reduced balance, which they consider to be symptoms of old age. However, their symptoms may not be attributable to age, but rather to poor vision. Aims: First, to identify associations between visual, musculoskeletal and balance symptoms in people engaging in near work every day and in people with VI. Second, to design and validate a suitable instrument for gathering information about visual, musculoskeletal and balance symptoms in people with VI. Third, to explore differences in perceived symptoms between VI patients and people with normal vision in cross-sectional studies and by following a group of age-related macular degeneration (AMD) patients in a longitudinal study. Fourth, to identify the most specific predictors of higher levels of visual, musculoskeletal and balance symptoms. Methods: A specific instrument was developed: the Visual, Musculoskeletal and Balance symptoms (VMB) questionnaire. Patients with VI were compared to an age-matched reference group with normal vision in three different studies in order to detect differences in self-reported symptoms between the groups. In addition, a follow-up was conducted in a group of AMD patients. Results: Patients with VI reported higher levels of VMB symptoms than controls, and this increased over time. Visual deficits and the need for visual enhancement increased the risk of VMB symptoms. Conclusion: People with VI run a potentially higher risk of VMB symptoms than age-matched controls.

A tomografia por emissão de pósitrons associada à tomografia computadorizada (PET/CT) é um dispositivo que combina as características de medicina nuclear (PET) e de radiologia (CT) obtendo imagens metabólicas (PET) e anatômicas sobrepostas (CT). Combinando as duas tecnologias de exames, o exame PET / CT permite aos médicos diagnosticar com maior precisão e identificar o câncer, doenças cardíacas e distúrbios cerebrais. O radiofármaco 18FFAc (fluoroacetato) é promissor para a detecção de tumores primários de próstata e de mama, utilizando a técnica de PET/CT. Estudos recentes mostram a eficácia do 18F-FAc na detecção de tumores que têm baixa captação de 18F-FDG (fluordesoxiglicose). O fluoroacetato é um substrato para a acetil-CoA sintase, enzima que metaboliza ácido fluorocitrato que não é mais metabolizado, levando à inibição da aconitase e do ácido tricarboxílico. O objetivo deste trabalho foi desenvolver um radiofármaco emissor de pósitron, 18F-FAc no IPEN-CNEN/SP em um acordo com o Hospital AC-Camargo / São Paulo. O íon fluoreto (18F-) foi produzido, usando os cíclotrons Cyclone 30 e 18 da IBA localizados no IPEN-CNEN/SP, através da irradiação de água enriquecida em 18O com prótons e dose integrada de 30μAh. A marcação do 18F-FAc foi realizada em um módulo de síntese TRACERlab MXFDG (GE), utilizando kits adquiridos da ABX. O controle de qualidade radioquímico de 18F-FAc foi realizado por cromatografia em camada fina TLC-SG 25 folhas de alumínio em tiras (1,5 x 12 cm ) usando como solvente clorofórmio:metanol (1:1). Para o controle de qualidade radionuclídico, amostras de 18F-FAc e 18F-Fluoreto foram analisadas por espectroscopia de raios-gama. A avaliação dos solventes residuais foi realizada por cromatografia em fase gasosa e a análise de kryptofix foi realizada por TLC utilizando tiras de TLC-SG, metanol:clorofórmio (9:1) como solvente e padrões de kryptofix 2.2.2. Os estudos de biodistribuição foram realizados com 18FFAc injetado em camundongos swiss sadios. Um procedimento reprodutível foi desenvolvido para o preparo do 18F-FAc com um rendimento de marcação de 37% (não corrigido) e 52% (corrigido para o decaimento) e estabilidade de 19 horas. A análise de controle de qualidade mostrou que o produto tinha as exigências adequadas para utilização, com pureza radioquímica superior a 99,9%. Os estudos de biodistribuição em animais sadios mostraram a esperada captação em todos os órgãos medidos com eliminação renal e intestinal. / PET / CT (positron emission tomography / computed tomography) is a device that combines the features of diagnostic nuclear medicine (PET) and Radiology (CT) superimposing metabolic (PET) and anatomical (CT) images. By combining the two technologies examinations, the PET/CT scan allows physicians to diagnose more accurately and identify cancer, heart disease and brain disorders. The radiopharmaceutical 18F-FAc (fluoroacetate) is promising for application in detection of primary tumors of prostate and breast, using PET-CT techniques. Recent studies are showing the efficacy of the 18F-FAc in the detection of tumors that have low uptake of 18F-FDG (fluorodeoxyglucose). The fluoroacetate is a substrate for the enzyme acetyl-CoA synthase that metabolizes acid fluorcitric that, not being metabolized, causes inhibition of aconitase and inhibition of tricarboxylic acid. The aim of this work was to develop a positron emitting radiopharmaceutical, 18F-FAc at IPEN-CNEN/SP in agreement with Hospital AC-Camargo/ São Paulo. The 18F-fluoride ion was produced using the Cyclone 30 and 18 cyclotrons from IBA located at IPEN-CNEN/SP, by irradiating enriched 18O water with protons with integrated dose 30μAh. The labelling of 18F-FAc was performed in a synthesis module TRACERlab MXFDG (GE), using kits purchased from ABX. The radiochemical quality control of 18F-FAc was performed by Thin Layer Chromatography using TLC-SG 25 aluminium sheets strips (1.5 x 12 cm) and chloroform:methanol (1:1) as the solvent. For the radionuclidic quality control, samples of 18F-FAc and 18F-Fluoride were analysed by gama-ray spectroscopy. The evaluation of the residual solvents was performed by gas chromatography and the analysis of kryptofix was performed by TLC using TLC-SG strips, methanol:chloroform (9:1) as solvent and kryptofix 2.2.2 standards. Biodistribution studies were performed with 18F-FAc injected into healthy Swiss mice. A reliable procedure was developed for preparation of 18F-FAc with a labelling yield of 37% (uncorrected) and 52% (corrected for decay) and stability of 19 hours. The quality control analysis showed that the product had the proper requirements for use, with radiochemical purity exceeding 99.9%. The biodistribution studies in healthy animals showed the expected uptake results in all the measured organs with intestinal and renal elimination.

L’étiologie exacte des maladies inflammatoires chroniques de l’intestin (MICI) reste actuellement méconnue. Mais un déséquilibre de la flore bactérienne, plus connu sous le nom de dysbiose et se traduisant par une augmentation de bactéries potentiellement pathogènes versus une diminution de bactéries bénéfiques, est démontré en permanence. De précédentes études ont permis de mettre en évidence la présence de souches pathogènes d’E. coli chez les patients atteints de la maladie de Crohn (MC). Ces souches appartiennent au pathovar Adherent Invasive E. coli (AIEC) et sont caractérisées par leur capacité à adhérer et à envahir les cellules épithéliales intestinales, à survivre et à se multiplier dans les macrophages en induisant une synthèse intense de TNF. La mise en évidence de ce pathovar a essentiellement été réalisée sur des biopsies de patients présentant une MC. Et bien que les mécanismes de pathogénicité et de virulence de la souche AIEC soient clairement déterminés, il n’existe pas d’études approfondies sur la prévalence des AIEC au niveau des matières fécales chez les patients atteints de MICI en comparaison à des individus sains. Ainsi, ce projet de thèse s’inscrit dans une meilleure compréhension de l’implication de ce pathovar AIEC dans les MICI au niveau luminal. Cette thèse cible différents points: prévalence et détection des AIEC, leur proportion relative par rapport à la flore E. coli totale, leur capacité d'invasion, leur phylogroupe ainsi que leur transmissibilité. A l’issue de ce travail, nous montrons que les AIEC sont retrouvés au niveau luminal chez les patients atteints de la MC mais également chez les patients présentant une rectocolite hémorragique, avec une détection des AIEC chez 33% et 2% respectivement. En outre, ces études ont permis de montrer une prévalence plus forte de ce pathovar dans les matières fécales d’individus sains (51%) en comparaison aux patients atteints de MICI. Et lorsque les AIEC sont présents, que ce soit chez les patients atteints de MICI et chez les témoins, ils représentent en moyenne 20 à 30% de la flore E. coli. Nous avons également pu montrer qu’il n’existe pas de différences significatives des scores d’invasion des isolats AIEC chez les patients atteints de MICI et chez les sujets sains. Certaines souches d’AIEC, isolées chez les patients atteints de MC et chez les sujets sains, ont été caractérisées génétiquement par la technique d’électrophorèse sur gel en champ pulsé. Sur ces souches, différents profils génétiques ont été obtenus attestant de la forte variabilité intra- et interindivuelle des AIEC. En conclusion, les AIEC, au vue de leur forte prévalence chez des sujets en bonne santé, seraient plutôt à reconsidérer comme des pathobionts ce qui définit un symbionte pouvant acquérir des propriétés virulentes chez un hôte prédisposé génétiquement en raison de facteurs environnementaux et/ou diététiques et ainsi favoriser l’inflammation intestinale. / Many studies have reported an imbalance of bacterial flora in patients with inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), defined as a dysbiosis, and resulting in an increase in potentially pathogenic bacteria versus a decrease in beneficial bacteria. Previous studies have highlighted the presence of pathogenic strains of E. coli in patients with CD. These strains belong to the pathovar Adherent Invasive E. coli (AIEC) and are characterized by their ability to adhere and invade intestinal epithelial cells, to survive and to multiply in macrophages by inducing an intense synthesis of TNF. In recent years, many studies established a link between AIEC pathovar and CD. Many of these studies have been performed on biopsies of patients with CD. And although the mechanisms of pathogenicity and virulence of the AIEC strain are clearly determined, there are no in-depth studies on the prevalence of AIEC in feces in IBD patients in comparison to healthy individuals. Thus, the goal of this thesis project is to better understand the involvement of AIEC pathovars in IBD at the luminal level. This thesis is based more precisely on the study of the prevalence of AIEC in feces of patients with IBD in comparison to healthy subjects, targeting different points: prevalence and detection of AIEC, their relative proportion compared to total E. coli flora, their invasion capacity, their phylogroup as well as their transmissibility. AIEC are found at luminal level in patients with CD but also in patients with UC, with detection of AIEC in 33% and 2% respectively. In addition, a higher prevalence of these pathovar is present in the feces of healthy individuals (51%) compared to patients with IBD. And when AIEC are present, both in IBD patients and in controls, they represent on average 20 to 30% of the E. coli flora. We have also been able to show that there are no significant differences in AIEC invasion scores in patients with IBD and in healthy subjects. Some AIEC strains, isolated in patients with CD and in healthy subjects, have been genetically characterized by pulsed-field gel electrophoresis. Different genetic profiles have been obtained attesting the high intra- and interindividual variability of AIEC strains. In conclusion, because of their high prevalence in healthy individuals, AIEC should be reconsidered as pathobionts, which defines a symbiont acquiring virulent properties in a genetically predisposed host due to environmental and / or dietary factors and thus promoting intestinal inflammation.

On considère le problème de contrôle optimal de temps minimal pour des systèmes affine et mono-entrée en dimension finie, avec conditions initiales et finales fixées, où le contrôle scalaire prend ses valeurs dans un intervalle fermé. Lors de l'application d'une méthode de tir pour résoudre ce problème, on peut rencontrer des obstacles numériques car la fonction de tir n'est pas lisse lorsque le contrôle est bang-bang. Pour ces systèmes, dans le cas bang-bang, un concept théorique de temps conjugué a été défini, toutefois les algorithmes de calcul direct sont difficiles à appliquer. En outre, les questions théoriques et pratiques de la théorie du temps conjugué sont bien connues dans le cas lisse, et des outils efficaces de mise en oeuvre sont disponibles. On propose une procédure de régularisation pour laquelle les solutions du problème de temps minimal dépendent d'un paramètre réel positif suffisamment petit et sont définis par des fonctions lisses en temps, ce qui facilite l'application de la méthode de tir simple. Sous des hypothèses convenables, nous prouvons un résultat de convergence forte des solutions du problème régularisé vers la solution du problème initial, lorsque le paramètre réel tend vers zéro. Le calcul des temps conjugués pour les trajectoires localement optimales du problème régularisé est standard. Nous prouvons, sous des hypothèses appropriées, la convergence du premier temps conjugué du problème régularisé vers le premier temps conjugué du problème de contrôle bang-bang initial, quand le paramètre réel tend vers zéro. Ainsi, on obtient une procédure algorithmique efficace pour calculer les temps conjugués dans le cas bang-bang. / In this thesis we consider a minimal time control problem for single-input control-affine systems in finite dimension with fixed initial and final conditions, where the scalar control take values on a closed interva1. When applying a shooting method for solving this problem, one may encounter numerical obstacles due to the fact that the shooting function is non smooth whenever the control is bang-bang. For these systems a theoretical concept of conjugate time has been defined in the bang-bang case, however direct algorithms of computation are difficult to apply. Besides, theoretical and practical issues for conjugate time theory are well known in the smooth case, and efficient implementation tools are available. We propose a regularization procedure for which the solutions of the minimal time problem depend on a small enough real positive parameter and are defined by smooth functions with respect to the time variable, facilitating the application of a single shooting method. Under appropriate assumptions, we prove a strong convergence result of the solutions of the regularized problem towards the solution of the initial problem, when the real parameter tends to zero. The conjugate times computation of the locally optimal trajectories for the regularized problem falls into the standard theory. We prove, under appropriate assumptions, the convergence of the first conjugate time of the regularized problem towards the first conjugate time of the initial bang-bang control problem, when the real parameter tends to zero. As a byproduct, we obtain an efficient algorithmic way to compute conjugate times in the bang-bang case.

A tomografia por emissão de pósitrons associada à tomografia computadorizada (PET/CT) é um dispositivo que combina as características de medicina nuclear (PET) e de radiologia (CT) obtendo imagens metabólicas (PET) e anatômicas sobrepostas (CT). Combinando as duas tecnologias de exames, o exame PET / CT permite aos médicos diagnosticar com maior precisão e identificar o câncer, doenças cardíacas e distúrbios cerebrais. O radiofármaco 18FFAc (fluoroacetato) é promissor para a detecção de tumores primários de próstata e de mama, utilizando a técnica de PET/CT. Estudos recentes mostram a eficácia do 18F-FAc na detecção de tumores que têm baixa captação de 18F-FDG (fluordesoxiglicose). O fluoroacetato é um substrato para a acetil-CoA sintase, enzima que metaboliza ácido fluorocitrato que não é mais metabolizado, levando à inibição da aconitase e do ácido tricarboxílico. O objetivo deste trabalho foi desenvolver um radiofármaco emissor de pósitron, 18F-FAc no IPEN-CNEN/SP em um acordo com o Hospital AC-Camargo / São Paulo. O íon fluoreto (18F-) foi produzido, usando os cíclotrons Cyclone 30 e 18 da IBA localizados no IPEN-CNEN/SP, através da irradiação de água enriquecida em 18O com prótons e dose integrada de 30μAh. A marcação do 18F-FAc foi realizada em um módulo de síntese TRACERlab MXFDG (GE), utilizando kits adquiridos da ABX. O controle de qualidade radioquímico de 18F-FAc foi realizado por cromatografia em camada fina TLC-SG 25 folhas de alumínio em tiras (1,5 x 12 cm ) usando como solvente clorofórmio:metanol (1:1). Para o controle de qualidade radionuclídico, amostras de 18F-FAc e 18F-Fluoreto foram analisadas por espectroscopia de raios-gama. A avaliação dos solventes residuais foi realizada por cromatografia em fase gasosa e a análise de kryptofix foi realizada por TLC utilizando tiras de TLC-SG, metanol:clorofórmio (9:1) como solvente e padrões de kryptofix 2.2.2. Os estudos de biodistribuição foram realizados com 18FFAc injetado em camundongos swiss sadios. Um procedimento reprodutível foi desenvolvido para o preparo do 18F-FAc com um rendimento de marcação de 37% (não corrigido) e 52% (corrigido para o decaimento) e estabilidade de 19 horas. A análise de controle de qualidade mostrou que o produto tinha as exigências adequadas para utilização, com pureza radioquímica superior a 99,9%. Os estudos de biodistribuição em animais sadios mostraram a esperada captação em todos os órgãos medidos com eliminação renal e intestinal. / PET / CT (positron emission tomography / computed tomography) is a device that combines the features of diagnostic nuclear medicine (PET) and Radiology (CT) superimposing metabolic (PET) and anatomical (CT) images. By combining the two technologies examinations, the PET/CT scan allows physicians to diagnose more accurately and identify cancer, heart disease and brain disorders. The radiopharmaceutical 18F-FAc (fluoroacetate) is promising for application in detection of primary tumors of prostate and breast, using PET-CT techniques. Recent studies are showing the efficacy of the 18F-FAc in the detection of tumors that have low uptake of 18F-FDG (fluorodeoxyglucose). The fluoroacetate is a substrate for the enzyme acetyl-CoA synthase that metabolizes acid fluorcitric that, not being metabolized, causes inhibition of aconitase and inhibition of tricarboxylic acid. The aim of this work was to develop a positron emitting radiopharmaceutical, 18F-FAc at IPEN-CNEN/SP in agreement with Hospital AC-Camargo/ São Paulo. The 18F-fluoride ion was produced using the Cyclone 30 and 18 cyclotrons from IBA located at IPEN-CNEN/SP, by irradiating enriched 18O water with protons with integrated dose 30μAh. The labelling of 18F-FAc was performed in a synthesis module TRACERlab MXFDG (GE), using kits purchased from ABX. The radiochemical quality control of 18F-FAc was performed by Thin Layer Chromatography using TLC-SG 25 aluminium sheets strips (1.5 x 12 cm) and chloroform:methanol (1:1) as the solvent. For the radionuclidic quality control, samples of 18F-FAc and 18F-Fluoride were analysed by gama-ray spectroscopy. The evaluation of the residual solvents was performed by gas chromatography and the analysis of kryptofix was performed by TLC using TLC-SG strips, methanol:chloroform (9:1) as solvent and kryptofix 2.2.2 standards. Biodistribution studies were performed with 18F-FAc injected into healthy Swiss mice. A reliable procedure was developed for preparation of 18F-FAc with a labelling yield of 37% (uncorrected) and 52% (corrected for decay) and stability of 19 hours. The quality control analysis showed that the product had the proper requirements for use, with radiochemical purity exceeding 99.9%. The biodistribution studies in healthy animals showed the expected uptake results in all the measured organs with intestinal and renal elimination.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-02-08T11:32:13Z No. of bitstreams: 1 Sílvio Jordan Brescovici_.pdf: 3631171 bytes, checksum: 010b5e74a677aa0d5375bcd957fb341e (MD5) / Made available in DSpace on 2017-02-08T11:32:13Z (GMT). No. of bitstreams: 1 Sílvio Jordan Brescovici_.pdf: 3631171 bytes, checksum: 010b5e74a677aa0d5375bcd957fb341e (MD5) Previous issue date: 2016-12-08 / UNISINOS - Universidade do Vale do Rio dos Sinos / Partindo da premissa de que nem a teoria nem a prática estão pacificadas, o estudo procura mapear as funções da controladoria e o alinhamento das práticas com as teorias, o que de fato ocorre, e como ocorre em determinado conjunto de empresas de médio porte. As empresas deste nicho têm se deparado com um progresso expressivo do seu grau de complexidade, o que por sua vez exigem novos mecanismos de controles organizacionais. Além disso, o crescente interesse pela implementação da controladoria nas empresas, e pela formação de controllers em universidades e outros institutos. Essas e outras motivações merecem uma investigação acadêmica que oxigene os conceitos, apresente as funções da controladoria no seu dia-a-dia, não sem antes abordar: o ordenamento da teoria vigente disciplinados pela categorização proposta, a análise da situação hierárquica da controladoria nas organizações, a influência da controladoria sobre a contabilidade, a sua competência na gestão de riscos e a identificação das práticas da controladoria no que diz respeito ao orçamento e ao composto estratégico. Para a execução deste trabalho a pesquisa empírica conta com a participação de seis empresas, todas de médio porte com características heterogêneas, que enriqueceram e focalizaram, a partir de suas diferentes características e abordagens, as práticas efetivamente exercidas pela controladoria, o que acabou por revelar também seu modelo de gestão. A metodologia empregada apresenta uma abordagem quantitativa e qualitativa, baseada em estudos de casos múltiplos, com caráter exploratório. Após o emprego de entrevistas semiestruturadas, foi aplicado o questionário em escala Likert e a pesquisa documental sobre os sujeitos da pesquisa: diretores, controladoria e profissionais adjuntos. Os resultados indicam que as funções ainda são ditadas pelo entendimento dos gestores, contudo o caráter transversal da controladoria e o conhecimento e as habilidades do controller são determinantes. Por fim, a análise do alinhamento das evidências desta pesquisa com a teoria fornece um tratado atualizado e aponta que a controladoria é estratégica, e quanto mais estratégica na organização, maior será o benefício. / Assuming that neither theory nor practice are appeased, the study seeks to map the functions of controlling and the alignment between practices and theories, expounding what actually occurs and how it occurs in certain set of medium-sized companies. Companies in this niche have come up with significant progress in their degree of complexity, which in turn require new organizational control mechanisms. In addition, there is a growing interest in the implementation of controllership by companies, and for the training of controllers in universities and other institutes. These and other motives deserve an academic research that oxygenate the concepts, present the controllership functions in their day-to-day, not without first addressing: the ordering of current theory disciplined by the proposed categorization, analysis of the hierarchical situation of control in organizations, the influence of the control over accounting, its competence in risk management and the identification of control practices with respect to the budget and the strategic compound. Six companies participate of this empirical research for the execution of this work. They are all medium-sized companies with heterogeneous characteristics that enriched and focused practices exercised effectively by the controller, because of their different characteristics and approaches, which ultimately also reveal the controller’s management perspective. The methodology presents a quantitative and qualitative approach based on multiple case studies, with exploratory appeal. After the implementation of semi-structured interviews, the questionnaire in Likert scale and the documentary research was applied on the subjects: directors, controllership, and associate professionals. The results indicate that the functions are still dictated by the managers' understanding, however, the transversal character of controllership and the knowledge and skills of the controller are determinant. Finally, the analysis of the alignment between theory and the evidences of this research provides an updated treatise, which points out that the controllership is strategic. Lastly, the more strategic the controllership is in an organization, the greater the benefit.

This thesis discusses the use of a cooperative multiple robot system as applied to distributed tracking and sampling of a boundary edge. Within this system the boundary edge is partitioned into subsegments, each allocated to a particular robot such that workload is balanced across the robots. Also, to minimize the time between sampling local areas of the boundary edge, it is desirable to minimize the difference between each robot’s progression (i.e. phase) along its allocated sub segment of the edge. The paper introduces a new distributed controller that handles both workload and phase balancing. Simulation results are used to illustrate the effectiveness of the controller in an Autonomous Underwater Vehicle (AUV) under ice edge sampling application. Successful results from experimentation with three iRobot(R) Creates are also presented.

This thesis discusses the interaction between inflation, living standards, and political change in Soviet/Russian history. It traces the establishment and evolution of the Soviet monetary system, inflationary episodes, and their consequences. The goal of this study is to show how inflation affects the lives of ordinary people and how it has contributed to larger changes in Soviet history. Sources include economic statistics and analysis from articles and monographs, as well as first-hand accounts from interviews and newspapers. The results show that inflation was a factor in both the rise and the fall of the Soviet Union. Russia's first hyperinflation (1917-1923) nearly destroyed the economy, and the Bolsheviks were forced to stabilize prices. The Soviet system of price controls prevented inflation, but it also created persistent shortages of food and consumer goods. Mikhail Gorbachev tried to alleviate these problems, but his efforts resulted instead in Russia's second hyperinflation (1992-1993).

Large silencers used in the power generation industry usually have a very large cross section at the inlet and outlet. Higher-order modes will populate the inlet and outlet even at very low frequencies. Although the silencer itself is often modeled by a three-dimensional analysis tool such as the boundary element method (BEM) or finite element method (FEM), a direct computation of the transmission loss (TL) from the BEM or FEM model can be challenging without incorporating certain forms of modal expansion. A so-called “impedance-to-scattering matrix method” is proposed to extract the modes at the inlet and outlet from the BEM impedance matrix based on the point collocation method. The BEM impedance matrix relates the sound pressures at the inlet and outlet to the corresponding particle velocities, while the scattering matrix relates the modes at the inlet and outlet. Normally there are more boundary elements than the total number of modes at the inlet and outlet, and a least-squares procedure is used to condense the element-based impedance matrix to the mode-based scattering matrix. The TL computation will follow if a certain form of the incident wave is assumed and the outlet is non-reflective. Several commonly used inlet/outlet configurations are considered in this dissertation, which include axisymmetric, non-axisymmetric circular, and rectangular inlet/outlet shapes. In addition to the single inlet and outlet silencers, large multi-inlet and multi-outlet silencers are also investigated. Besides the collocation-based impedance-to-scattering matrix method, an integral-based impedance-to-scattering matrix method based on the reciprocal identity is also proposed for large silencer analysis. Although it may be more time-consuming to perform the additional numerical integration, an integral-based method is free of any uncertainties associated with collocation points. The computational efficiency, accuracy and stability are compared between two proposed methods. One bonus effect of producing the scattering matrix is that it can also be used to combine subsystems in series connection. The Redheffer’s star product is introduced to combine scattering matrices of subsystems. In the design stage, rapid assessment of the silencer performance is always preferred. However, the existing analytical approaches are only suitable for simple dissipative silencers such as straight lined ducts. A two-dimensional first-mode semi-analytical solution is developed to quickly evaluate the performance of tuned dissipative silencers below the cut-off frequency. The semi-analytical solution can also serve as a validation tool for the BEM.

This research deals with determining the acoustic attenuation of heating, ventilation, and air conditioning (HVAC) ductwork. A finite element approach was developed for calculating insertion loss and breakout transmission loss. Procedures for simulating the source and receiving rooms were developed and the effect of structureborne flanking was included. Simulation results have been compared with measurements from the literature and the agreement is very good. With a good model in place, the work was extended in three ways. 1) Since measurements on full-scale equipment are difficult, scale modeling rules were developed and validated. 2) Two different numerical approaches were developed for evaluating the transmission loss of silencers taking into account the effect of higher order modes. 3) A power transfer matrix approach was developed to assess the acoustic performance of several duct components connected in series.