Main goal of this thesis is to design exhaust manifold for Formula Student car Dragon 3. Construction parameters follow requirements on high engine power and also have to meet some restrictions given by competition rules. Lotus Engine Simulation software was used for modelling the engine (originally from Husaberg FE 570 motorcycle) and for determination of influence of the exhaust parameters on power characteristics. This thesis is also dedicated to noise emitted by the exhaust system which is important due to Formula Student rules.

Excessive fluid-borne noise in hydraulic systems is a problem the fluid power industry has long struggled to address. Traditional noise control devices such as Helmholtz resonators, tuning coils, and Herschel-Quincke tubes are generally too large for fluid power systems unless the speed of sound in the device can be reduced. A compliant lining can achieve this effect, but compliance (and lossy compliance) has had little attention in noise control in general, and in fluid power in particular. One means to achieve compliance in these devices, especially at elevated pressures, is through a liner made of syntactic foam, which in this case is a urethane host matrix with embedded hollow, polymer microspheres. The material properties at elevated pressure are unknown by the liner manufacturer, but are known to be pressure- and temperature-dependent. Therefore, the effect of hydrostatic pressures from 2.1-21 MPa and temperatures from 20-45 C on the liner properties, thus the device performance, are studied. For a Helmholtz resonator, a theoretical model is fit to experimentally-measured transmission loss of the device using a least-squares routine, which solves the inverse problem for the complex bulk modulus of the liner. These material properties are used to compare a predictive model of a tuning coil to experimental data, and in a parameter study of a Herschel-Quincke tube. The compliance of the liner is found to lower the effective sound speed by an order of magnitude and decrease the volume of the cavity of a Helmholtz resonator by up to two orders of magnitude. This work is expected to result is more compact noise control devices for fluid power systems.

Sound generation and propagation in circular ducts for frequencies beyond the cut-on frequencies of several higher order acoustic modes is investigated. To achieve this, experimental and numerical set-ups are designed and used to research aeroacoustic interactions between in-duct components and to conceive noise mitigation strategies. Describing in-duct sound for frequencies with a moderate number of propagating modes is important, for example, for improving the noise emission from mid-size ventilation systems. Challenges that are largely unacknowledged in the literature involve efficient test rig design, quantification of limits in the methods, numerical modelling, and development of effective noise mitigation strategies for higher order modes. In this thesis, in-duct sound is mapped on a set of propagating pressure eigenmodes to describe aeroacoustic components as multi-ports with sound scattering (passive properties) and a source strength (active properties). The presented analysis includes genetic algorithms and Monte Carlo Methods for test rig enhancement and evaluation, multi-port network predictions to identify model limitations, and scale resolving (IDDES) and Linearized Navier Stokes computations for numerical multi-port eduction and the silencer design. It is first shown that test rig optimization improves the quality of multi-port data significantly. Subsequently, measurements on orifice plates are used to test the network prediction model. The model works with high accuracy for two components that are sufficiently separated. For small separations, strong coupling effects are observed for the source strength but not for the scattering of sound. The measurements are used for numerical validation, which gives reliable results for coupled and uncoupled systems. The total acoustic power of tandem orifices is predicted with less than 2 dB deviation and the passive properties for most frequencies with less than 5 % difference from the measurement. The numerical (FEM) models are also used to design a completely integrated silencer for spinning modes that is based on micro-perforated plates and gives broadband attenuation of 3-6 dB per duct diameter silencer length. The multi-port method is a powerful tool when describing aerodynamically decoupled in-duct components in the low- to mid-frequency range. Due to a robust passive network prediction, multi-port methods are particular interesting for the design of silencer stages. Furthermore, the demonstrated applicability to numerical data opens novel application areas. / <p>QC 20170522</p> / IdealVent

New methodologies and concepts for developing compact and energy efficient automotive exhaust systems have been studied. This originates in the growing concern for global warming, to which road transportation is a major contributor. The focus has been on commercial vehicles—most often powered by diesel engines—for which the emission legislation has been dramatically increased over the last decade. The emissions of particulates and nitrogen oxides have been successfully reduced by the introduction of filters and catalytic converters, but the fuel consumption, which basically determines the emissions of carbon dioxides, has not been improved accordingly. The potential reduction of fuel consumption by optimising the exhaust after-treatment system (assuming fixed after-treatment components) of a typical heavy-duty commercial vehicle is ~4%, which would have a significant impact on both the environment and the overall economy of the vehicle. First, methodologies to efficiently model complex flow duct networks such as exhaust systems are investigated. The well-established linear multiport approach is extended to include flow-acoustic interaction effects. This introduces an effective way of quantifying amplification and attenuation of incident sound, and, perhaps more importantly, the possibility of predicting nonlinear phenomena such as self-sustained oscillations—whistling—using linear models. The methodology is demonstrated on T-junctions, which is a configuration well known to be prone to self-sustained oscillations for grazing flow past the side branch orifice. It is shown, and validated experimentally, that the existence and frequency of self-sustained oscillations can be predicted using linear theory. Further, the aeroacoustics of T-junctions are studied. A test rig for the full determination of the scattering matrix defining the linear three-port representing the T-junction is developed, allowing for any combination of grazing-bias flow. It is shown that the constructive flow-acoustic coupling not only varies with the flow configuration but also with the incidence of the acoustic disturbance. Configurations where flow from the side branch joins the grazing flow are still prone to whistling, while flow bleeding off from the main branch effectively cancels any constructive flow-acoustic coupling. Two silencer concepts are evaluated: first the classic Herschel-Quincke tube and second a novel modified flow reversal silencer. The Herschel-Quincke tube is capable of providing effective attenuation with very low pressure loss penalty. The attenuation conditions are derived and their sensitivity to mean flow explained. Two implementations have been modelled using the multiport methodology and then validated experimentally. The first configuration, where the nodal points are composed of T-junctions, proves to be an example where internal reflections in the system can provide sufficient feedback for self-sustained oscillation. Again, this is predicted accurately by the linear theory. The second implementation, with nodal points made from Y-junctions, was designed to allow for equal flow distribution between the two parallel ducts, thus allowing for the demonstration of the passive properties of the system. Experimental results presented for these two configurations correlate well with the derived theory. The second silencer concept studied consists of a flow reversal chamber that is converted to a resonator by acoustically short-circuiting the inlet and outlet ducts. The eigenfrequency of the resonator is easily shifted by varying the geometry of the short circuit, thus making the proposed concept ideal for implementation as a semi-active device. Again the concept is modelled using the multiport approach and validated experimentally. It is shown to provide significant attenuation over a wide frequency range with a very compact design, while adding little or no pressure loss to the system. / QC 20110208

L'épilepsie du lobe temporal (ELT) est la forme la plus fréquente de l'épilepsie chez l'adulte. Elle se traduit par des crises spontanées et récurrentes, qui sont résistantes à tout traitement dans 90% des cas. Une agression initiale du cerveau (traumatisme crânien, méningite, convulsions fébriles etc.), est souvent à l'origine de la transformation d'un cerveau « sain » en cerveau épileptique. L'ensemble des processus responsables de cette transition s'appelle l'épileptogenèse. Pouvoir bloquer et/ou retarder l'épileptogenèse chez les patients à risque est une question de santé majeure. En plus des crises, l'ELT soulève d'autres questions. Elle est souvent associée à des déficits cognitifs, qui sont la conséquence de la réorganisation des circuits neuronaux. Ces déficits pourraient être traités de façon indépendante de l'épilepsie elle-même. Le projet de recherche de cette thèse s'inscrit dans ce cadre général. / Temporal Lobe Epilepsy (TLE) is the most common form of epilepsy in adults. It translates into spontaneous and recurrent seizures, which are resistant to any treatment in 90% of cases. An initial brain insult (head injury, meningitis, febrile seizures etc.), is often the cause of the transformation of a "healthy" brain into an epileptic one. The process responsible for this transition is called epileptogenesis. Blocking and/or delaying epileptogenesis in at-risk patients is a key issue for public health. In addition to the seizures, TLE raises other problems. It is often associated with cognitive deficits, which are the result of the reorganization of neuronal circuits. These deficits may be treated independently of epilepsy itself. The work presented here fits into this general framework.

This master´s thesis focuses on effect of acoustic microclimate in non-production buildings to human. Within elaboration this topic was made measurment acoustic power level and created protocols by valid technical standards and law. I dedicate to damping noise and aerodynamic noise in airconditioning in part topic analysis. The part aplication on real object deal with assessment current status and draft measure for improve acoustic ratio in laboratories in center of research located in Brno. That includes describe of air-cndition unit and development two variants and their rating.

Diploma thesis is bent on engineering design exhaust manifold for motor Formula SAE. Drive unit is here used atmospheric water-cooled gas- engine from motorcycle Yamaha YZF R6, 2005 model year. The design of the exhaust manifold is drawn to fulfil Formula SAE conditions.

[EN] This Thesis is focused on the development and implementation of efficient numerical methods for the acoustic modelling and design of noise control devices in the exhaust system of combustion engines. Special attention is paid to automotive perforated dissipative silencers, in which significant differences are likely to appear in their acoustic behaviour, depending on the temperature variations within the absorbent material. Also, material heterogeneities can alter the silencer attenuation performance. Therefore, numerical techniques considering all these features are required to guarantee the accuracy of the results. A literature review is carried out, mainly related to one-dimensional models, as well as to acoustic models for absorbent materials and perforated surfaces. However, plane wave model limitations make indispensable using alternative multidimensional methods. In addition, the possibility of using new acoustic elements is explored. These elements have as an objective being a potential alternative to the fibrous absorbent materials, which can have a negative impact on health. The Thesis considers the use of microperforated and sintered surfaces. The latter have, in some cases, a nearly constant acoustic impedance, whose value depends, among others, on the thickness and porosity of the plates. To avoid the limitations of plane wave models, a finite element (FE) approach is proposed for the acoustic analysis of dissipative silencers including a perforated duct with uniform axial mean flow and an outer chamber with a heterogeneous distribution of the absorbent material. On the other hand, property variations can be also produced by temperature gradients. In this case, a hybrid FE model has been derived for perforated dissipative silencers including: (1) Thermal gradients in the central duct and the chamber; (2) A perforated passage carrying non-uniform axial mean flow. A FE approach has been implemented to solve the pressure-based wave equation for a non-moving heterogeneous medium, associated with the chamber. Also, the governing equation in the central duct has been written and solved in terms of an acoustic velocity potential to allow the presence of an axially inhomogeneous flow. The coupling between both regions has been carried out by means of a perforated duct and its acoustic impedance, adapted here to include absorbent material heterogeneities and mean flow effects. It has been found that the presence of non-homogeneities can have a significant influence on the acoustic attenuation of a silencer and should be included in the theoretical models. Optimization techniques for industrial noise control devices are relevant, since they lead to the production of elements with better characteristics. Evolutionary algorithms are emergent techniques able to obtain a solution, even in those problems in which the traditional optimization have difficulties. Optimization techniques are combined with the FE method to achieve the maximum attenuation in the frequency range of interest. A multichamber silencer optimization problem is defined and several analyses are carried out to obtain the most suitable configuration for each application. Under certain assumptions of axial uniformity, several techniques have been considered to reduce the computational effort of a full 3D FE analysis for dissipative silencers with temperature gradients and mean flow. These are based on a decomposition of the acoustic field into transversal and axial modes within each silencer subdomain, and a matching procedure of the modal expansions at the silencer area changes through the continuity conditions of the acoustic fields. The relative computational efficiency and accuracy of predictions for the matching techniques are studied, including point collocation at nodes and Gauss points and also mode-matching with weighted integration. All of them provide accurate predictions of the attenuation and improve the computational cost of a FE calculation / [ES] Esta Tesis se centra en el desarrollo e implementación de métodos numéricos eficientes para el diseño y modelado de componentes de la línea de escape en motores de combustión interna. Merecen especial atención los silenciadores disipativos perforados de automóviles, ya que su comportamiento acústico puede sufrir variaciones importantes debidas a las variaciones de temperatura en el material absorbente, así como a las heterogeneidades de la fibra. Por tanto, se requieren técnicas numéricas que consideren estos casos para garantizar la precisión de los resultados. Se lleva a cabo una revisión bibliográfica que recoge los modelos de onda unidimensionales, así como modelos acústicos de materiales absorbentes y superficies perforadas. Sin embargo, las limitaciones de los primeros hacen indispensable el uso de modelos multidimensionales. Además se explora la posibilidad de usar nuevos elementos acústicos, cuyo objetivo es ser una alternativa potencial a los materiales absorbentes, que pueden tener un efecto negativo sobre la salud. La Tesis considera el uso de superficies microperforadas y sinterizadas. Estas últimas en algunos casos presentan una impedancia casi constante, cuyo valor depende, entre otras cosas, del espesor y la porosidad de las placas. Para evitar las limitaciones de los modelos de onda plana, se propone un enfoque en elementos finitos (EF) para el análisis acústico de silenciadores disipativos que incluyen un conducto con flujo medio axial uniforme y una cámara externa con una distribución heterogénea de material absorbente. Por otro lado, la variación de las propiedades también puede producirse por gradientes térmicos. En este caso, se propone una formulación híbrida de EF para silenciadores disipativos perforados que incluye: (1) Gradientes térmicos en el conducto central y la cámara; (2) Un conducto perforado que canaliza flujo medio axial no uniforme. Se ha implementado una formulación de EF para resolver la ecuación de ondas en términos de presión para el medio estacionario heterogéneo asociado a la cámara. Además, la ecuación asociada al conducto central, expresada en términos de potencial de velocidad acústica, permite la presencia de flujo axial no uniforme. El acoplamiento entre ambas regiones se ha realizado mediante un conducto perforado y su impedancia acústica y se ha adaptado para incluir la citada falta de homogeneidad. Se ha visto que las heterogeneidades pueden influir notablemente en la atenuación acústica de un silenciador, debiéndose incluir en los modelos teóricos. Las técnicas de optimización para componentes industriales de control de ruido son importantes, ya que producen elementos con mejores características. Los algoritmos evolutivos son técnicas emergentes capaces de obtener una solución, incluso cuando la optimización tradicional tiene dificultades. Las técnicas de optimización se combinan con el MEF para conseguir la máxima atenuación posible en el rango de frecuencias de interés. Se ha definido un problema de optimización de un silenciador multicámara y se han llevado a cabo varios análisis para obtener la configuración más adecuada para cada caso. Bajo ciertas hipótesis de uniformidad axial, se han considerado varias técnicas para reducir el coste computacional de un análisis 3D completo para silenciadores disipativos con gradientes de temperatura y flujo medio. Éstas se basan en la descomposición del campo acústico en modos axiales y transversales dentro de cada subdominio, y un procedimiento de acoplamiento de las expansiones modales en los cambios de sección del silenciador mediante las condiciones de continuidad de los campos acústicos. Se estudia la eficiencia computacional y precisión de las predicciones de las técnicas de acoplamiento, incluyendo colocación puntual en nodos y puntos de Gauss, así como ajuste modal. Todos ellos proporcionan predicciones precisas de la atenuación mejorando el coste / [CA] Aquesta Tesi es centra en el desenvolupament i implementació de mètodes numèrics eficients per al disseny i modelatge de components de la línia d'escapament en motors de combustió interna. Mereixen especial atenció els silenciadors dissipatius perforats d'automòbils, ja que el seu comportament acústic pot patir variacions importants degudes a les variacions de temperatura en el material absorbent, així com a les heterogeneïtats de la fibra. Per tant, es requereixen tècniques numèriques que considerin aquests casos per garantir la precisió dels resultats. Es porta a terme una revisió bibliogràfica que recull els models d'ona unidimensionals, així com models acústics de materials absorbents i superfícies perforades. No obstant això, les limitacions dels primers fan indispensable l'ús de models multidimensionals. A més s'explora la possibilitat d'usar nous elements acústics amb l'objectiu que siguen una alternativa potencial als materials absorbents, que poden tenir un efecte negatiu sobre la salut. La Tesi considera l'ús de superfícies microperforades i sinteritzades. Aquestes últimes en alguns casos presenten una impedància gairebé constant. El seu valor depèn, entre altres coses, del gruix i la porositat de les plaques. Per evitar les limitacions dels models d'ona plana, es proposa un enfocament amb elements finits (EF) per a l'anàlisi acústic de silenciadors dissipatius que inclouen un conducte amb flux mig axial uniforme i una càmera externa amb una distribució heterogènia de material absorbent. D'altra banda, la variació de les propietats també es pot produir per gradients tèrmics. En aquest cas, es proposa una formulació híbrida d'EF per silenciadors dissipatius perforats que inclou: (1) Gradients tèrmics en el conducte central i la càmera; (2) Un conducte perforat que canalitza flux mig axial no uniforme. S'ha implementat una formulació d'EF per resoldre l'equació d'ones en termes de pressió per al medi estacionari heterogeni associat a la càmera. A més, l'equació associada al conducte central, expressada en termes de potencial de velocitat acústica, permet la presència de flux axial no uniforme. L'acoblament entre les dues regions s'ha realitzat mitjançant un conducte perforat i la seva impedància acústica i s'ha adaptat per incloure la esmentada falta d'homogeneïtat. S'ha vist que les heterogeneïtats poden influir notablement en l'atenuació acústica d'un silenciador i s'han d'incloure en els models teòrics. Les tècniques d'optimització per a components industrials de control de soroll són importants, ja que produeixen elements amb millors característiques. Els algoritmes evolutius són tècniques emergents capaces d'obtenir una solució, fins i tot quan l'optimització tradicional té dificultats. Les tècniques d'optimització es combinen amb el mètode d'elements finits (MEF) per aconseguir la màxima atenuació possible en el rang de freqüències d'interès. S'ha definit un problema d'optimització d'un silenciador multicàmera i s'han dut a terme diverses anàlisis per obtenir la configuració més adequada per a cada cas. Sota certes hipòtesis d'uniformitat axial, s'han considerat diverses tècniques per reduir el cost computacional d'una anàlisi 3D complet per silenciadors dissipatius amb gradients de temperatura i flux mig. Aquestes es basen en la descomposició del camp acústic en modes axials i transversals dins de cada subdomini, i un procediment d'acoblament de les expansions modals en els canvis de secció del silenciador mitjançant les condicions de continuïtat dels camps acústics. S'estudia l'eficiència computacional i precisió de les prediccions de les tècniques d'acoblament, incloent col·locació puntual en nodes i punts de Gauss, així com ajust modal. Tots ells proporcionen prediccions precises de l'atenuació millorant el cost computacional d'EF. / Sánchez Orgaz, EM. (2016). Advanced numerical techniques for the acoustic modelling of materials and noise control devices in the exhaust system of internal combustion engines [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/64090

The study of cis-regulatory elements (CREs) will allow for increased understanding of regulation and lead to insight regarding the mechanisms governing growth, development, health, and disease. The aim of this study was to characterize the de novo in silico predictions of Arabidopsis CREs. Eight synthetic and 30 native promoter-constructs containing an eGFP/GUS reporter protein were generated for cold, genotoxic, heat, osmotic, and salt stress; the circadian clock; ABA signaling; root and epidermis tissue. Constructs were stably transformed into A. thaliana Col-0 and the effects of the CREs were evaluated by in planta stress or tissue assays using GUS expression levels. Results reveal a novel genotoxic element that specifically directs GUS expression in rosette leaves during genotoxic stress. Results also look promising for novel epidermis and root-specific elements. Results of these assays validate the de novo prediction pipeline's ability to identify novel and known CREs related to abiotic stress.

The study of cis-regulatory elements (CREs) will allow for increased understanding of regulation and lead to insight regarding the mechanisms governing growth, development, health, and disease. The aim of this study was to characterize the de novo in silico predictions of Arabidopsis CREs. Eight synthetic and 30 native promoter-constructs containing an eGFP/GUS reporter protein were generated for cold, genotoxic, heat, osmotic, and salt stress; the circadian clock; ABA signaling; root and epidermis tissue. Constructs were stably transformed into A. thaliana Col-0 and the effects of the CREs were evaluated by in planta stress or tissue assays using GUS expression levels. Results reveal a novel genotoxic element that specifically directs GUS expression in rosette leaves during genotoxic stress. Results also look promising for novel epidermis and root-specific elements. Results of these assays validate the de novo prediction pipeline's ability to identify novel and known CREs related to abiotic stress.