Dans l'état actuel des connaissances, il est impossible de poser correctement toute la physique permettant de modéliser les hydrosystèmes dans leur ensemble, notamment à cause de la dynamique très contrastée des différents compartiments. Les modèles systémiques simplifient la représentation des hydrosystèmes en ne considérant que leurs flux d’échange. L’objet de ce travail est de proposer un outil de modélisation systémique fournissant des informations sur le fonctionnement physique des hydrosystèmes, tout en étant simple et parcimonieux. Ce modèle nommé MASH (pour Modélisation des Hydrosystèmes par Approche Systémique) est basé sur l’utilisation de fonctions de transfert paramétriques choisies en fonction de leur faible paramétrisation, leur caractère général et leur interprétation physique. Il est versatile, dans le sens que son architecture est modulable et que le nombre d’entrées, le nombre de fonctions de transfert en série et le type de fonctions de transfert utilisé est laissée à la discrétion de l’utilisateur. Ce modèle est inversé en utilisant de récentes avancées en apprentissage automatique grâce à une famille d’heuristiques basée sur l’intelligence en essaim nommé « optimisation par essaim de particule » (ou PSO pour « Particle Swarm Optimization »). Le modèle et ses algorithmes d’inversion sont testés sur un cas d’école synthétique, puis sur un cas d’application réel. / In the light of current knowledge, hydrosystems cannot be modelled as a whole since underlying physical principles are not totally understood. Systemic models simplify hydrosystem representation by considering only water flows. The aim of this work is to provide a systemic modelling tool giving information about hydrosystem physical behavior while being simple and parsimonious. This model, called HMSA (for Hydrosystem Modelling with a Systemic Approach) is based on parametric transfer functions chose for their low parametrization, their general nature and their physical interpretation. It is versatile, since its architecture is modular, and the user can choose the number of inputs, outputs and transfer functions. Inversion is done with recent machine learning heuristic family, based on swarm intelligence called PSO (Particle Swarm Optimization). The model and its inversion algorithms are tested first with a textbook case, and then with a real-world case.

A new way of adhering woven textile to a nonwoven backing was explored, the end product in mind being a sound absorbent panel. Today a hot melt adhesive is sprayed on the nonwoven with woven decorating textile put on top before compression molding. This method results in an uneven layer of adhesive with the consequence of decorating textile detaching from the nonwoven and thereby a high number of discarded products. The report investigates the possibility of using a bicomponent fiber as the adhesive. This would guarantee an even layer of adhesive and make the manufacturing process one step shorter. A bicomponent fiber of core/sheath construction with a low melting polymer in the sheath was incorporated in the nonwoven upon fabrication. In the main bulk of the nonwoven a smaller ratio of bicomponent to normal polyester fiber was used, enough to stabilize the nonwoven. For the top layer of the nonwoven a higher ratio was chosen. As the nonwoven is then compression molded under heat together with the decorating textile, the low melting sheath of the bicomponent fiber will melt and create bonds within the nonwoven as well as to the textile. The ratio in the top layer was varied as well as the pressure in compression molding. The adhesion strength between nonwoven and decorating textile was tested, and the sound absorbing properties of the different manufactured samples were compared. The sound absorbing parameter of air flow resistance was tested and sound absorption was tested using impedance tube with transfer function method. Further, a way of testing transmission loss was developed by the manufacturing of a custom built impedance tube, which was then compared to the transfer function method. The results showed that a higher bicomponent percentage gave higher sound absorption in lower frequencies, but a lower sound absorption in higher frequencies. The thickness of the samples gave a positive effect on the sound absorption in all frequencies. The conclusion is to recommend a thicker material, and choose bicomponent according to which frequencies that should be absorbed and what adhesion strength is needed for end product. / Program: Textilteknik

L’objectif de la thèse est le développement d'une stratégie pour quantifier expérimentalement le bruit indirect et le séparer du bruit direct, puisque le bruit direct et indirect co-existent dans la plupart des applications. La configuration retenue pour l'étude est un banc expérimental avec une tuyère et la stratégie proposée a pour l’objectif de mesurer les fonctions de transfert de la tuyère. Le premier chapitre définit les fonctions de transfert de la tuyère utilisée dans l'étude comme référence pour la validation de la stratégie. Le deuxième chapitre présente une configuration originale qui génère simultanément le bruit direct et indirect sans introduire la combustion. Le troisième chapitre détaille les méthodes pour évaluer les ondes acoustiques et d'entropie à partir des mesures de température et de pression. Le quatrième chapitre termine la première partie de la thèse en décrivant la stratégie avant de la tester avec les signaux expérimentaux et numériques de haute fidélité. La deuxième partie se concentre sur l'utilisation de la stratégie dans les simulations à grandes échelles d'un brûleur à combustion turbulente. Les simulations sont validées par des données expérimentales tandis que les signaux sont traités à quantifier le bruit direct et indirect de combustion dans la chambre. / The objective of the thesis is the development of a practical strategy to quantify experimentally indirect noise and to discriminate it from direct noise as they co-exist in most practical conditions. The configuration retained for the study is a test bench with a nozzle and the proposed the strategy relies on nozzle transfer functions. The first chapter defines the nozzle transfer functions used in the study as references for the validation of the strategy. The second chapter introduces an original setup that generates simultaneously direct and indirect noise without handling combustion. The third chapter details the methods to evaluate the acoustic and entropy waves from raw temperature and pressure signals. The fourth chapter closes the first part of the study by describing the strategy then testing it on high-fidelity simulation and experimental signals. The second part focuses on the use of the strategy in Large Eddy Simulations of a turbulent combustion test bench. Simulations are validated by experimental data then raw signals are processed to quantify the direct and indirect noise sources as well as the direct and indirect noise contributions.

Scale modeling has been commonly used for architectural acoustics but use in other noise control areas is nominal. Acoustic scale modeling theory is first reviewed and then feasibility for small-scale applications, such as is common in the electronics industry, is investigated. Three application cases are used to examine the viability. In the first example, a scale model is used to determine the insertion loss of a rectangular barrier. In the second example, the transmission loss through parallel tubes drilled through a cylinder is measured and results are compared to a 2.85 times scale model with good agreement. The third example is a rectangular cuboid with a smaller cylindrical well bored into it. A point source is placed above the cuboid. The transfer function was measured between positions on the top of the cylinder and inside of the cylindrical well. Treatments were then applied sequentially including a cylindrical barrier around the well, a membrane cover over the opening, and a layer of sound absorption over the well. Results are compared between the full scale and a 5.7 times scale model and correlation between the two is satisfactory.

<p>The technique of volume rendering can be a powerful tool when visualizing 3D medical data sets. Its characteristic of capturing 3D internal structures within a 2D rendered image makes it attractive in the analysis. However, the applications that implement this technique fail to reach out to most of the supposed end-users at the clinics and radiology departments of today. This is primarily due to problems centered on the design of the Transfer Function (TF), the tool that makes tissues visually appear in the rendered image. The interaction with the TF is too complex for a supposed end-user and its capability of separating tissues is often insufficient. This thesis presents methods for detecting the regions in the image volume where tissues are contained. The tissues that are of interest can furthermore be identified among these regions. This processing and classification is possible thanks to the use of a priori knowledge, i.e. what is known about the data set and its domain in advance. The identified regions can finally be visualized using tissue adapted TFs that can create cleaner renderings of tissues where a normal TF would fail to separate them. In addition an intuitive user control is presented that allows the user to easily interact with the detection and the visualization.</p>

Fluorescent x-ray screens are used in medical x-ray diagnostics to absorb x-ray photons and convert these x-ray photons to visible light. The light distribution from these screens are then registered on photographic film to give an x-ray image. Both the sensitivity and the resolution characteristics of these systems are dependent on the x-ray photon energy. To enable a study of these and some other energy dependent characteristics of x-ray screens a number of almost monoener-getic radiation sources were constructed, tested with regard to their purity and calibrated. Both film and a photo-multiplier tube were used as light detectors.The sensitivity of screens with three different screen phosphors were studied as a function of the photon energy and large variations in sensitivity was found for different photon energies and screen phosphors. The light from the screens has been compared to the absorbed energy in the screens and this comparison shows that the energy dependence of the screens can approximately be predicted by calculations of the absorbed energy, except at low photon energies where other effects like increased light absorption in the screens is present.The modulation transfer factor (MTF) was studied both experimentally and theoretically as a function of photon energy. Two effects were shown to influence the energy dependence of the MTF. At low energies an increased light diffusion will destroy the MTF and at energies above the K-edge of the high-Z elements in the screens the production and re-absorption of K-radiation will deteriorate the MTF.Both the energy dependence of the screen-film sensitivity and the MTF have been calculated for some normally used spectral distributions from x-ray tubes and significant changes due to choice of kV and filtration of the beam were found. Other effects such as the number of interacting photons in the screens per unit area, contribution of K-radiation from one screen to the other, and light contribution to the front emulsion of the film compared to the back emulsion have also been investigated as a function of photon energy.Optimization of x-ray systems and clinical routines to give the lowest possible radiation dose to the patient with an acceptable image quality is an important task to carry out. The energy dependent characteristi es of x-ray screens studied in this work is a lead in the optimizing of the system with regard to choice of x-ray screens, film and radiation quality. / digitalisering@umu

The technique of volume rendering can be a powerful tool when visualizing 3D medical data sets. Its characteristic of capturing 3D internal structures within a 2D rendered image makes it attractive in the analysis. However, the applications that implement this technique fail to reach out to most of the supposed end-users at the clinics and radiology departments of today. This is primarily due to problems centered on the design of the Transfer Function (TF), the tool that makes tissues visually appear in the rendered image. The interaction with the TF is too complex for a supposed end-user and its capability of separating tissues is often insufficient. This thesis presents methods for detecting the regions in the image volume where tissues are contained. The tissues that are of interest can furthermore be identified among these regions. This processing and classification is possible thanks to the use of a priori knowledge, i.e. what is known about the data set and its domain in advance. The identified regions can finally be visualized using tissue adapted TFs that can create cleaner renderings of tissues where a normal TF would fail to separate them. In addition an intuitive user control is presented that allows the user to easily interact with the detection and the visualization.

Magistro darbe tiriami dinaminio proceso perdavimo spyruokle ypatumai bei galimybės, ir kaip tą panaudoti spyruoklėmis vibroizoliuotų atramų diagnostikai. Buvo sukurta tyrimo metodika ir spyruoklės įėjimo ir išėjimo charakteristikoms gauti atitinkamas matavimo stendas. Naudojant impulsinio tipo signalą, buvo gautas sistemos savųjų virpesių spektras, taip pat sistema buvo žadinama vibratoriumi, siekiant ištirti ir įvertinti spyruoklės perdavimo funkciją esant nerezonansiniams dažniams. Analizuojant išmatuotas realizacijas, buvo išvesta perdavimo funkcija. Darbą sudaro 7 dalys: įvadas, literatūros apžvalga ir analizė, eksperimentiniai tyrimai, tyrimo rezultatai, rekomendacijos, išvados ir pasiūlymai, literatūros sąrašas. Darbo apimtis – 44 p. teksto be priedų, 41 iliustr., 31 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai. / Particulars of the problem of the dynamics transfer function of the spring and possibilities for diagnostics of the support bearings which are insulated from the external body by the resilient elements are developed in this article. During this research work the investigation methodology was found and suitable research stand was made as well. The impulse type input signal was submitted to the system to observe free oscillations in the stand. Also the system was excited by electromagnetic vibrator to research transfer function of the spring. Finally using the output and input signals at the spring ends the transfer function was derived. The thesis consists of 7 parts: introduction, rewiew of references and analisys, experimentation investigations, experimentation results, recommendations, conclusions and suggestions, the list of the references. Thesis consist of: 44 p. of text without appendixes, 41 pictures, 31 bibliographical entries. Appendixes included.

Preponderant visual interface use for conveying information from machine to human admits failures due to overwhelming the visual channel. This thesis investigates the suitability of auditory feedback and certain related design choices in settings involving background speech. Communicating a tele-operated vehicle’s tilt angle was the focal application. A simulator experiment with pitch feedback on one system variable, tilt angle, and its safety threshold was conducted. Manipulated in a within-subject design were: (1) presence vs. absence of speech, (2) discrete tilt alarm vs. discrete alarm and tilt sonification (continuous feedback), (3) tilt sonification vs. tilt and threshold sonification, and (4) linear vs. quadratic transfer function of variable to pitch. Designs with both variable and reference sonification were found to significantly reduce the time drivers spent exceeding the safety limit compared to the designs with no sonification, though this effect was not detected within the set of conditions with background speech audio.

For successful identification of structural defects in plates and pipes, it is essential to understand structural wave propagation characteristics such as dispersion relations. Analytical approaches to identify the dispersion relations of homogeneous, simple plates and circular pipes have been investigated by many researchers. However, for plates or pipes with irregular cross-sectional configurations or multi-layered composite structures, it is almost impossible to obtain the analytical dispersion relations and associated mode shapes. In addition, full numerical modeling approaches such as finite element (FE) methods are not economically feasible for high (e.g., ultrasonic) frequency analyses where an extremely large number of discretized meshes are required, resulting in significantly expensive computation. In order to address these limitations, Hybrid Analytical/Finite Element Methods (HAFEMs) are developed to model composite plates and pipes in a computationally-efficient manner. When a pipe system is used to transport a fluid, the dispersion curves obtained from a “hollow” pipe model can mislead non-destructive evaluation (NDE) results of the pipe system. In this study, the HAFEM procedure with solid elements is extended by developing fluid elements and solid-fluid boundary conditions, resulting in the dispersion curves of fluid-filled pipes. In addition, a HAFEM-based acoustic transfer function approach is suggested to consider a long pipe system assembled with multiple pipe sections with different cross-sections. For the validation of the proposed methods, experimental and full FE modeling results are compared to the results obtained from the HAFEM models. In order to detect structural defect locations in shell structures from defect-induced, subtle wave reflection signals and eliminate direct-excitation-induced and boundary-reflected, relatively-strong wave signals, a time-frequency MUSIC algorithm is applied to ultrasonic wave data measured by using an array of piezoelectric transducers. A normalized, structurally-damped, cylindrical 2-D steering vector is proposed to increase the spatial resolution of time-frequency MUSIC power results. A cross-shaped array is selected over a circular or linear array to further improve the spatial resolution and to avoid the mirrored virtual image effects of a linear array. Here, it is experimentally demonstrated that the proposed time-frequency MUSIC beamforming procedure can be used to identify structural defect locations on an aluminum plate by distinguishing the defect-induced waves from both the excitation-generated and boundary-reflected waves.