Dissertations / Theses on the topic 'Coupler curves'

This thesis addresses the kinematic analysis of mechanisms, in particular, the position analysis of kinematic chains, or linkages, that is, mechanisms with rigid bodies (links) interconnected by kinematic pairs (joints). This problem, of completely geometrical nature, consists in finding the feasible assembly modes that a kinematic chain can adopt. An assembly mode is a possible relative transformation between the links of a kinematic chain. When an assignment of positions and orientations is made for all links with respect to a given reference frame, an assembly mode is called a configuration. The methods reported in the literature for solving the position analysis of kinematic chains can be classified as graphical, analytical, or numerical. The graphical approaches are mostly geometrical and designed to solve particular problems. The analytical and numerical methods deal, in general, with kinematic chains of any topology and translate the original geometric problem into a system of kinematic analysis of all the Assur kinematic chains resulting from replacing some of its revolute joints by slider joints. Thus, it is concluded that the polynomials of all fully-parallel planar robots can be derived directly from that of the widely known 3-RPR robot. In addition to these results, this thesis also presents an efficient procedure, based on distance and oriented area constraints, and geometrical arguments, to trace coupler curves of pin-jointed Gr¨ubler kinematic chains. All these techniques and results together are contributions to theoretical kinematics of mechanisms, robot kinematics, and distance plane geometry. equations that defines the location of each link based, mainly, on independent loop equations. In the analytical approaches, the system of kinematic equations is reduced to a polynomial, known as the characteristic polynomial of the linkage, using different elimination methods —e.g., Gr¨obner bases or resultant techniques. In the numerical approaches, the system of kinematic equations is solved using, for instance, polynomial continuation or interval-based procedures. In any case, the use of independent loop equations to solve the position analysis of kinematic chains, almost a standard in kinematics of mechanisms, has seldom been questioned despite the resulting system of kinematic equations becomes quite involved even for simple linkages. Moreover, stating the position analysis of kinematic chains directly in terms of poses, with or without using independent loop equations, introduces two major disadvantages: arbitrary reference frames has to be included, and all formulas involve translations and rotations simultaneously. This thesis departs from this standard approach by, instead of directly computing Cartesian locations, expressing the original position problem as a system of distance-based constraints that are then solved using analytical and numerical procedures adapted to their particularities. In favor of developing the basics and theory of the proposed approach, this thesis focuses on the study of the most fundamental planar kinematic chains, namely, Baranov trusses, Assur kinematic chains, and pin-jointed Gr¨ubler kinematic chains. The results obtained have shown that the novel developed techniques are promising tools for the position analysis of kinematic chains and related problems. For example, using these techniques, the characteristic polynomials of most of the cataloged Baranov trusses can be obtained without relying on variable eliminations or trigonometric substitutions and using no other tools than elementary algebra. An outcome in clear contrast with the complex variable eliminations require when independent loop equations are used to tackle the problem. The impact of the above result is actually greater because it is shown that the characteristic polynomial of a Baranov truss, derived using the proposed distance-based techniques, contains all the necessary and sufficient information for solving the position
Esta tesis aborda el problema de análisis de posición de cadenas cinemáticas, mecanismos con cuerpos rígidos (enlaces) interconectados por pares cinemáticos (articulaciones). Este problema, de naturaleza geométrica, consiste en encontrar los modos de ensamblaje factibles que una cadena cinemática puede adoptar. Un modo de ensamblaje es una transformación relativa posible entre los enlaces de una cadena cinemática. Los métodos reportados en la literatura para la solución del análisis de posición de cadenas cinemáticas se pueden clasificar como gráficos, analíticos o numéricos. Los enfoques gráficos son geométricos y se diseñan para resolver problemas particulares. Los métodos analíticos y numéricos tratan con cadenas cinemáticas de cualquier topología y traducen el problema geométrico original en un sistema de ecuaciones cinemáticas que define la ubicación de cada enlace, basado generalmente en ecuaciones de bucle independientes. En los enfoques analíticos, el sistema de ecuaciones cinemáticas se reduce a un polinomio, conocido como el polinomio característico de la cadena cinemática, utilizando diferentes métodos de eliminación. En los métodos numéricos, el sistema se resuelve utilizando, por ejemplo, la continuación polinomial o procedimientos basados en intervalos. En cualquier caso, el uso de ecuaciones de bucle independientes, un estándar en cinemática de mecanismos, rara vez ha sido cuestionado a pesar de que el sistema resultante de ecuaciones es bastante complicado, incluso para cadenas simples. Por otra parte, establecer el análisis de la posición de cadenas cinemáticas directamente en términos de poses, con o sin el uso de ecuaciones de bucle independientes, presenta dos inconvenientes: sistemas de referencia arbitrarios deben ser introducidos, y todas las fórmulas implican traslaciones y rotaciones de forma simultánea. Esta tesis se aparta de este enfoque estándar expresando el problema de posición original como un sistema de restricciones basadas en distancias, en lugar de directamente calcular posiciones cartesianas. Estas restricciones son posteriormente resueltas con procedimientos analíticos y numéricos adaptados a sus particularidades. Con el propósito de desarrollar los conceptos básicos y la teoría del enfoque propuesto, esta tesis se centra en el estudio de las cadenas cinemáticas planas más fundamentales, a saber, estructuras de Baranov, cadenas cinemáticas de Assur, y cadenas cinemáticas de Grübler. Los resultados obtenidos han demostrado que las técnicas desarrolladas son herramientas prometedoras para el análisis de posición de cadenas cinemáticas y problemas relacionados. Por ejemplo, usando dichas técnicas, los polinomios característicos de la mayoría de las estructuras de Baranov catalogadas se puede obtener sin realizar eliminaciones de variables o sustituciones trigonométricas, y utilizando solo álgebra elemental. Un resultado en claro contraste con las complejas eliminaciones de variables que se requieren cuando se utilizan ecuaciones de bucle independientes. El impacto del resultado anterior es mayor porque se demuestra que el polinomio característico de una estructura de Baranov, derivado con las técnicas propuestas, contiene toda la información necesaria y suficiente para resolver el análisis de posición de las cadenas cinemáticas de Assur que resultan de la sustitución de algunas de sus articulaciones de revolución por articulaciones prismáticas. De esta forma, se concluye que los polinomios de todos los robots planares totalmente paralelos se pueden derivar directamente del polinomio característico del conocido robot 3-RPR. Adicionalmente, se presenta un procedimiento eficaz, basado en restricciones de distancias y áreas orientadas, y argumentos geométricos, para trazar curvas de acoplador de cadenas cinemáticas de Grübler. En conjunto, todas estas técnicas y resultados constituyen contribuciones a la cinemática teórica de mecanismos, la cinemática de robots, y la geometría plana de distancias. Barcelona 13-

A study is presented detailing experimental investigations of magnetization dynamics in nanostructured systems which are coupled magnetically. This work seeks to characterize the anisotropy of such systems through experimental techniques which probe microwave resonant absorption in the materials. A custom-built experimental setup, designed and assembled in our labs, is explained in detail. This setup allows for angular-dependent ferromagnetic resonance (FMR) measurements in the sample plane through vector network analyzer spectroscopy and is adaptable to two different types of coplanar waveguides. This technique has proven effective for characterization of multiple types of magnetic systems, including multilayered structures as detailed here, with different types of anisotropies while allowing us to draw analogies with more common characterization techniques. The angular FMR setup has been used to study coupled systems, such as those coupled through the Ruderman–Kittel–Kasuya–Yosida interaction as well as exchange-biased structures. These types of coupled systems have technological impacts and are highly applied in the components of magnetoresistive random access memory. Using this new characterization technique, properties of synthetic antiferromagnets have been revealed which had not been observed before. In addition to these experiments, magnetic susceptibility and FMR in exchange biased systems have been investigated at temperatures as low as 2 K. This investigation used a new FMR spectrometer and was one of the first studies to use this instrument. For the first time a new method of identifying several types of coupling which can be present in layered nanostructures is presented and supported through comparison with known techniques, thus connecting a new characterization technique for layered structures with decades-old procedures. Many results within this work are also supported theoretically with computer simulations.

A study of magnetization dynamics experiments in nanostructured materials using the rf susceptibility tunnel diode oscillator (TDO) method is presented along with a extensive theoretical analysis. An original, computer controlled experimental setup that measures the change in susceptibility with the variation in external magnetic field and sample temperature was constructed. The TDO-based experiment design and construction is explained in detail, showing all the elements of originality. This experimental technique has proven reliable for characterizing samples with uncoupled magnetic structure and various magnetic anisotropies like: CrO2 , FeCo/IrMn and Co/SiO2 thin films. The TDO was subsequently used to explore the magnetization switching in coupled magnetic systems, like synthetic antiferromagnet (SAF) structures. Magnetoresistive random access memory (MRAM) is an important example of devices where the use of SAF structure is essential. To support the understanding of the SAF magnetic behavior, its configuration and application are reviewed and more details are provided in an appendix. Current problems in increasing the scalability and decreasing the error rate of MRAM devices are closely connected to the switching properties of the SAF structures. Several theoretical studies that were devoted to the understanding of the concepts of SAF critical curve are reviewed. As one can notice, there was no experimental determination of SAF critical curve, due to the difficulties in characterizing a magnetic coupled structure. Depending of the coupling strength between the two ferromagnetic layers, on the SAF critical curve one distinguishes several new features, inexistent in the case of uncoupled systems. Knowing the configuration of the SAF critical curve is of great importance in order to control its switching characteristics. For the first time a method of experimentally recording the critical curve for SAF is proposed in this work. In order to overcome technological limitations, a new way of recording the critical curve by using an additional magnetic bias field was explored.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
In this master’s thesis, the free and forced nonlinear vibrations of an simply supported isotropic cylindrical shell fluid-filled by an incompressible, inrotational and non-viscous fluid are analyzed. The internal fluid is described by a velocity potential and the effects of the fluid ́s free surface on the non-linear vibrations of the cylindrical shell are considered. The non-linear equations of motion are obtained by the Rayleigh-Ritz method, considering the deformation field and changes of curvature described by the nonlinear theories of Donnell and Sanders. The chosen displacement field of the cylindrical shell corresponds to a modal solution proposed by Gonçalves (1987) that were obtained by the perturbation method. A parametric study is carried out to analyze the free vibrations, using the Galerkin-Urabe method to obtain for each geometry a system of non-linear algebraic equations, being solved by the Newton-Raphson method and thus to obtaining a relation between the amplitude and frequency. The results for these analyses show that depending on the geometric conditions there is a great influence of the free surface consideration on the nonlinear dynamic behavior of the cylindrical shell. Finally, a study of the forced vibrations of cylindrical shells subjected to time-dependent lateral pressure is made applying the fourth-order Runge-Kutta method to solve the second-order differential equations in time in order to find the phase portraits and the time response of the cylindrical shell. The influence of the consideration of the free surface effect of the internal fluid on the forced response of the cylindrical shell is observed and it is possible to note that the consideration of the free surface causes the appearance of important peaks of resonance in the resonance curves of the cylindrical shell.
Nesta dissertação são analisadas as vibrações não lineares, livres e forçada, de uma casca cilíndrica isotrópica simplesmente apoiada e preenchida por um fluido irrotacional, incompressível e não viscoso, que pode ser descrito por um potencial de velocidade. Considera-se os efeitos da superfície livre deste fluido nas vibrações não lineares da casca cilíndrica. As equações de movimento não lineares foram obtidas pelo método de Rayleigh-Ritz e para descrever o campo de deformação e momento de curvatura foram adotadas as teorias não lineares de Donnell e Sanders. O campo de deslocamento da casca cilíndrica utilizado corresponde a uma solução modal propostapor Gonçalves (1987) que foram obtidas pelo método da perturbação. Realizou-se um estudo paramétrico para analisar as vibrações livres onde para cada geometria estudada foi aplicado o método de Galerkin-Urabe para obter um sistema de equações algébricas não lineares, sendo então resolvidas pelo método de Newton-Raphson e assim obtendo uma relação entre a amplitude e a frequência. Os resultados para estes estudos mostram que dependendo das condições geométricas há uma grande influência da consideração da superfície livre no comportamento dinâmico não linear da casca cilíndrica. Por fim, é feito um estudo das vibrações forçadas de cascas cilíndricas submetidas a uma pressão lateral dependente do tempo, onde por meio do método de Runge-Kutta de quarta ordem soluciona-se as equações ordinais diferenciais de segunda ordem no tempo afim de encontrar as curvas de ressonância, planos-fase e a resposta no tempo da casca cilíndrica que serão utilizadas para analisar a influência da consideração do efeito de superfície livre do fluido interno na resposta forçada da casca cilíndrica. Observa-se que a consideração da superfície livre provoca o aparecimento de importantes picos de ressonância nas curvas de ressonância da casca cilíndrica.

The thesis is performed in order to improve the curvic coupled engagement of a dog clutch situated in the transfer case of a truck. The dog clutch is used to engage the so called all-wheel-drive system of the truck. If the driver tries to engage the all-wheel-drive when truck’s rear wheels already skid, due to a slippery surface a relative rotational speed in the dog clutch will occur. This relative rotational speed will cause the dog clutch to bounce back of itself before engagement, or to not engage at all. The dog clutch has been redesigned to prevent this. Dynamic simulations using MD Adams have been made for the existing model, for the models created in previous works, and for the new model in order to figure out which of them will show the most stable engagement, at high relative rotational speed. The implemented simulations show that better results can be obtained. Separation into two parts of the disc pushed by the fork, shows that dog clutch’s engagement is faster and more stable, comparing to the original model and the other created models. The new model shows better coupling in the whole range of the relative rotational speed from 50 up to 120rpm.

The therapeutic alliance is a core element of successful treatment in therapy. Recent literature has explored variables that predict the alliance at various time points during therapy, but few studies have explored how the alliance develops over time and the factors that influence its rate of change. The current study addresses these questions by estimating latent growth-curve models to analyze how male and female partners' alliance scores develop over time and how adverse childhood experiences (ACEs) impact the development of the alliance during the first six sessions of therapy. Results from these analyses show that neither men nor women's ACEs had a significant effect on the rate of change in the alliance. A discussion of the attachment implications of these findings, as well as the limitations of this study and potential directions for future research are then presented.

Static techniques to measure different magnetic properties of coupled magnetic nanostructured systems is researched and documented with an extensive analysis of the tunnel diode oscillator (TDO). The VSM was used to obtain the major hysteresis loop for the samples and the TDO was used to measure the magnetic susceptibility. The magnetic susceptibility was employed to conceive the static critical curve. The thesis describes both equipments, VSM and TDO, that were used to obtain data for our experiments. Albeit a more comprehensive outlook on the TDO is provided. The theoretical functionality of TDO, previous successful applications for experiments, and the physical setup in the laboratory is explored. The novel addition of the double Helmholtz coil in this setup is described. The viability of replacement of the big electromagnet and the advantages of the Helmholtz coil are discussed. Magnetization dynamics in a series of FeCoB/Ru/FeCoB synthetic antiferromagnetic samples were investigated via reversible susceptibility measurements acquired through the TDO. The major hysteresis loop generated by the VSM were used to calculate the coercivity and magnetic saturation of the sample. The VSM and TDO were subsequently used to explore the magnetization switching in a di_erent coupled magnetic system, the exchange bias samples. A range of NiFe/FeMn samples were studied with varying thickness of the antiferromagnetic layer.

Coupled Thermo-Hydro-Mechanical (THM) behavior in geological porous media has been a subject of great interest in many geoengineering disciplines. Many attempts have been made to develop numerical prediction capabilities associated with topics such as the movement of pollutant plumes, gas injection, energy storage, geothermal energy extraction, and safety assessment of repositories for radioactive waste and spent nuclear fuel. This thesis presents a new numerical modeling approach and a new computer code for simulating coupled THM behavior in geological porous media in general, and compacted bentonite clays in particular, as buffer materials in underground radioactive waste repositories. New governing equations were derived according to the theory of mixtures, considering interactions among solid-phase deformation, flows of water and gases, heat transport, and phase change of water. For three-dimensional problems, eight governing equations were formulated to describe the coupled THM processes. A new thermal conductivity model was developed to predict the thermal conductivity of geological porous media as composite mixtures. The proposed model considers the combined effects of solid mineral composition, temperature, liquid saturation degree, porosity and pressure on the effective thermal conductivity of the porous media. The predicted results agree well with the experimental data for MX80 bentonite. A new water retention curve model was developed to predict the suction-saturation behavior of the geological porous media, as a function of suction, effective saturated degree, temperature, porosity, pore-gas pressure, and the rate of saturation degree change with time. The model was verified against experimental data of the FEBEX bentonite, with good agreement between measured and calculated results. A new finite element code (ROLG) was developed for modeling fully coupled thermo-hydro-mechanical processes in geological porous media. The new code was validated against several analytical solutions and experiments, and was applied to simulate the large scale in-situ Canister Retrieval Test (CRT) at Äspö Hard Rock Laboratory, SKB, Sweden, with good agreement between measured and predicted results. The results are useful for performance and safety assessments of radioactive waste repositories.
QC20100720
THERESA

No presente trabalho é apresentado um conjunto de medidas de seção de choque do processo de fusão nuclear nos sistemas ANTPOT. 12 C + ANTPOT. 63, 65 CU, em um intervalo de energia correspondente à 0.91.8 vezes a barreira coulombiana. O método experimental utilizado foi a detecção dos resíduos de evaporação através da técnica de tempo de vôo, acoplado à um defletor eletrostático para separar as partículas provenientes do espalhamento elástico dos produtos de fusão. As vantagens e limitações do método são discutidas em detalhes. As funções de excitação de fusão dos sistemas citados foram analisadas via modelo de penetração de barreira unidimensional , utilizando vários potenciais nucleares. Dessa análise comprovou-se que a secção de choque de fusão é subestimada em energias em torno e abaixo da barreira coulombiana. Nesse sentido foi feito um cálculo, utilizando o código computacional CCFUS, que simula o acoplamento de canais, com a finalidade de descobrir quais canais contribuem para o processo de fusão nuclear em baixas energias. As seções de choque de fusão obtidas foram comparadas com outros sistemas - ANTPOT. 12 C + ANTPOT. 63, 65 CU.- que utilizam os mesmos núcleos-alvo. A comparação revelou que os sistemas ANTPOT. 12 C + ANTPOT. 63, 65 CU possuem o maior aumento de seção de choque de fusão subcoulombiana e esse fato pode estar relacionado à deformação estática do projétil. A comparação das distribuições da velocidade dos resíduos de evaporação para os dois de sistemas revelou um canal intenso para o sistema ANTPOT. 12 C + ANTPOT. 63 CU que não está presente para o outro sistema.
In this work we present cross-section measurements for nuclear fusion in the 12C+ 63,65 Cu system, at 12C energy range from 0.9 to 1.8 times the Coulomb barrier. In order to detect and to obtain the mass identification of the evaporation residues following the fusion process, the time of flight method was adopted in conjunction with an eletrostatic deflector capable of separating the evaporation residues from the beam particles. The limitation and advantadges of this method of measurement are discussed. The excitation functions for the above systems were analysed using the unidimensional barrier penetration model with different nuclear potentials. Theoretical fusion cross-section values obtained from this analysis were systematically smaller than our measured values, in the energy region below the Coulomb barrier. In order to discover which channel enhances the fusion cross-section in this region, a coupled channel calculation was performed, with the aid of CCFUS code. The experimental data for the above reactions were compared with the systems 12C+ 63,65 Cu, measured by our group. In this comparison, It was noted that the systems 12C+ 63,65 Cu have greater fusion cross section below the Coulomb barrier. This fact can be related to the static deformation of 12C. The comparison of velocity spectra of the evaporated residues for the two systems shows that 12C+63Cu has a strong reaction channel that was not present in the 12C+ 65Cu system.

Diese Arbeit untersucht die N = 4 super-Yang-Mills-Theorie bei schwacher Kopplung, mit dem Ziel eines tieferen Verständnisses von Größen der Theorie als Zustände des integrablen Modells dass der planaren Theorie zu Grunde liegt. Wir leiten On-Shell-Diagramme für Formfaktoren des chiralen Energie-Impuls-Tensor-Multipletts aus der BCFW-Rekursion her, und untersuchen deren Eigenschaften. Dies erlaubt die Herleitung eines Graßmannschen Integrals. Für NMHV-Formfaktoren bestimmen wir die Integrationskontur. Dies erlaubt es das Integral mit einer Twistor-String-Formulierung in Beziehung zu setzen. Mit Hilfe dieser Methoden zeigen wir dass Formfaktoren des chiralen Energie-Impuls-Tensor-Multipletts und On-Shell-Funktionen mit Einfügungen beliebiger Operatoren Eigenzustände integrabler Transfermatrizen sind. Diese Identitäten verallgemeinern die Yangsche Invarianz der On-Shell-Funktionen von Amplituden. Wir zeigen weiterhin dass ein Teil der Yangschen Symmetrien erhalten bleibt. Wir erweitern unsere Untersuchung auf nichtplanare On-Shell-Funktionen und zeigen dass sie ebenfalls solche Symmetrien besitzen. Weitere Identitäten mit Transfermatrizen werden hergeleitet, und zeigen insbesondere dass Diagramme auf Zylindern als Intertwiner fungieren. Als Schritt hin zur Berechnung der Eigenzustände des integrablen Modells zu höheren Schleifenordnungen untersuchen wir Einspuroperatoren. Hier erlaubt die Quantum Spectral Curve die nichtperturbative Berechnung ihres Spektrums, liefert jedoch keine Information zu den Zustände. Die QSC kann als Q-System verstanden werden, welches durch Baxter Q-Operatoren formulierbar sein sollte. Um darauf hinzuarbeiten untersuchen wir die Q-Operatoren nichtkompakter Superspinketten und entwickeln ein effiziente Methode zur Berechnung ihrer Matrixelemente. Dies erlaubt es das gesamte Q-System durch Matrizen für jeden Anregungssektor zu realisieren, und liefert die Grundlage für perturbative Rechnungungen mit der QSC in Operatorform.
This thesis investigates weakly coupled N = 4 super Yang-Mills theory, aiming at a better understanding of various quantities as states of the integrable model underlying the planar theory. We use the BCFW recursion relations to develop on-shell diagrams for form factors of the chiral stress-tensor multiplet, and investigate their properties. The diagrams allow to derive a Graßmannian integral for these form factors. We devise the contour of this integral for NMHV form factors, and use this knowledge to relate the integral to a twistor string formulation. Based on these methods, we show that both form factors of the chiral stress-tensor multiplet as well as on-shell functions with insertions of arbitrary operators are eigenstates of integrable transfer matrices. These identities can be seen as symmetries generalizing the Yangian invariance of amplitude on-shell functions. In addition, a part of these Yangian symmetries are unbroken. We furthermore consider nonplanar on-shell functions and prove that they exhibit a partial Yangian invariance. We also derive identities with transfer matrices, and show that on-shell diagrams on cylinders can be understood as intertwiners. To make progress towards the calculation of the higher loop eigenstates of the integrable model, we consider single trace operators, for which the Quantum Spectral Curve determines their spectrum non-perturbatively. This formulation however carries no information about the states. The QSC is an algebraic Q-system, for which an operatorial form in terms of Baxter Q-operators should exist. To initiate the development such a formulation we investigate the Q-operators of non-compact super spin chains and devise efficient methods to evaluate their matrix elements. This allows to obtain the entire Q-system in terms of matrices for each magnon sector. These can be used as input data for perturbative calculations using the QSC in operatorial form.

The telecommunications market is one of the large rapidly growing fields in today’s power supply industry due to the increasing demand for telecom distributed power supply (DPS) systems. The half-bridge LLC (Inductor-Inductor-Capacitor) resonant converter is currently the most attractive topology for the design and implementation of 24V/48V DC telecom power converters. The current doubler rectifier (CDR) converter topology was invented and described in the early 1950s which can offer the unique characteristic of halving the output voltage while doubling the output current compared to a standard rectifier. In this thesis, the current doubler converter topology with its unique characteristic is evaluated as a complementary solution to improve the LLC resonant converter performance, especially for the low output voltage and high output current telecommunication applications. A novel half-bridge LLC resonant current doubler converter (LLC-CDR) is proposed in this thesis which can offer several performance benefits compared to conventional LLC-standard rectifier design . The unique characteristics of the LLC-CDR topology can offer significant improvements by transformation of a 48V converter into a 24V converter with the same power density. This thesis introduces a new SPICE-based simulation model to analyse the operation of this novel LLC-CDR converter circuit design. This model can be used to define the critical component parameters for the LLC -CDR circuit output inductor values. It can also be used to predict the circuit overall performance under different load conditions. Both time-domain based transient simulation analysis and frequency-domain based AC analysis provided by this simulation model showed favourable results in comparison to bench measurement results on a prototype. The model provides a valuable insight to reveal some of the unique characteristics of this LLC -CDR topology. It demonstrates a proof of concept that the conventional LLC resonant converter can be easily redesigned for low voltage, high current applications by using the LLC-CDR topology without requiring a new design for the LLC resonant stage components and the power transformer. A new magnetic integration solution was proposed to significantly improve the overall performance in the LLC-CDR topology that had not been published before. The LLC-CDR converter hardware prototypes with two output inductors coupled and uncoupled configurations were extensively modelled, constructed and bench tested.Test results demonstrated the suitability of an integrated coupled inductors design for the novel LLC-CDR converter application. The integrated coupled inductors design can significantly improve the LLC-CDR converter frequency-domain based AC simulation analysis results. In addition, these results also illustrate the potential benefit of how the magnetic integration design in general could reduce the magnetic component size, cost, and weight compared to the uncoupled inductors design. Finally, a hardware prototype circuit was constructed based on a commercial 1800 W single phase telecom power converter to verify the operation of this novel half bridge LLC-CDR topology. The converter prototype successfully operated at both no load and full load conditions with the nominal output voltage halved from 48VDC to 24VDC, and doubled the output current to match the same output power density. It also demonstrates that the efficiency of this novel half bridge LLC –CDR is 92% compares to 90% of EATON’s commercial 24VDC LLC resonant converter, which can fulfill the research goals.

Les voies sèches de valorisation du bois énergie sont de plus en plus exigeantes vis-à-vis de la qualité de la matière première et notamment quant à sa teneur en eau. Ainsi, une étape intermédiaire de préconditionnement, sur site industriel, tend à se développer. La mise en œuvre de séchoirs en continu est alors séduisante de par son faible coût et sa parfaite intégration dans la ligne de production. Cependant, elle n'est pas sans écueil : la variabilité de la biomasse et l'hétérogénéité des conditions climatiques au sein du séchoir rendent fastidieux le dimensionnement du séchoir et de la source de chaleur associée d'une part et la maximisation du flux matière d'autre part.Notre étude a pour ambition de développer un outil informatique d'aide à la conception et à l'optimisation de séchoirs en continu traversés par un lit condensé de particules de bois. Pour y parvenir, nous associons une approche expérimentale et une approche numérique du procédé. La démarche scientifique s'articule autour de deux échelles représentatives :- A l'échelle de la particule de bois, le modèle de Van Meel, reposant sur le concept de courbe caractéristique de séchage, est étendu : le couplage entre transferts de chaleur et de masse est rendu explicite. Nous disposons dès lors d'un modèle réactif et prédictif en conditions climatiques variables. Parallèlement, un premier dispositif expérimental original est conçu et construit pour l'étude du séchage de particules de bois isolées. Les données recueillies sont alors analysées en vue d'alimenter en paramètres et de valider le modèle semi-analytique ;- A l'échelle du séchoir, une modélisation double-échelle est adoptée pour tenir compte de l'évolution des conditions climatiques. Un soin particulier est apporté à la modélisation, se voulant être la plus proche possible des installations existantes : à ce titre, les transferts au niveau de la paroi du séchoir sont pris en compte, ainsi que la variabilité des particules de bois. Parallèlement, un second dispositif expérimental original est conçu et construit pour l'étude du séchage de particules disposées en lit. Les données recueillies sont alors confrontées aux simulations du modèle double-échelle.La validation du modèle s'étant révélée probante tant à l'échelle de la particule qu'à celle du séchoir, une utilisation du code pour l'aide à la conception et à l'optimisation d'installations industrielles a pu être envisagée. Ainsi, ce travail s'achève-t-il par deux études de cas à travers lesquelles nous explorons le potentiel du modèle pour maximiser le flux matière tout en garantissant la qualité du produit et l'efficacité énergétique du séchoir.

La zone sahélienne a connu une baisse des précipitations et d’importants changements d'utilisation des terres ces dernières décennies qui ont conduit à une forte régression du couvert ligneux. Pourtant, Guiera senegalesis J.F. Gmel est une Combretaceae semi-sempervirente, dont la dominance s'est accrue avec la pression agricole dans la bande soudano-sahélienne où elle joue un rôle socio-économique et agroforestier important. Elle constitue donc un bon modèle pour étudier les réponses hydriques du couvert ligneux actuel à la sécheresse et les modifications de ces réponses sous l'effet de la coupe.Les objectifs de ce travail de thèse étaient : 1) de caractériser et quantifier les processus de régulation hydrique chez G. senegalensis et de déterminer ses limites fonctionnelles, afin d’estimer sa marge de sécurité dans ses conditions actuelles de croissance, 2) d’estimer l’effet de la coupe annuelle sur ses processus de régulation et 3) d’analyser les variations de ses traits foliaires en fonction de la saison et des conditions de croissance.Les mesures et les observations ont été réalisées d’avril 2009 à février 2011 sur une jachère âgée, sur une jeune jachère et sur deux champs de mil adjacents aux deux jachères respectivement. A l'échelle de l'arbuste, le potentiel hydrique foliaire et la conductance stomatique ont été mesurés au cours de ces deux saisons de croissance sur un échantillon d'arbustes dans les trois types de couvert. Le taux de transpiration foliaire et la conductance hydraulique sol-feuille en ont été déduits. A l’échelle du rameau, ont été suivi la dynamique du nombre de feuilles, de la surface moyenne des feuilles, du diamètre moyen des tiges qui les portent. La durée de vie moyenne des feuilles et leur masse surfacique ont été mesurées. La courbe de vulnérabilité à la cavitation de l'espèce, qui est la perte de la conductivité hydraulique en fonction du potentiel hydrique, a été réalisée à partir de plusieurs segments de branches passés au CAVITRON en laboratoire.Les principaux résultats obtenus sont que la fermeture des stomates qui permet à l’espèce de réguler ses pertes en eau a lieu à un niveau faible de cavitation du xylème (30%). Ainsi, l’espèce peut survivre dans les conditions sahéliennes grâce à une « marge de sécurité » positive de +0,6 MPa. La régulation stomatique couplée à un ajustement foliaire permet à l’espèce de maintenir son équilibre hydrique au cours de la saison sèche chez les arbustes matures non perturbés. La baisse des potentiels hydriques foliaires de base et minimum en réponse à la sécheresse saisonnière est isohydrodynamique et est plus élevé chez les arbustes matures, suggérant que les repousses de l'année sont moins stressées. De plus, la coupe a pour effet de découpler l’ajustement foliaire de la régulation stomatique et entraîne une production de feuilles et une croissance des jeunes rameaux continues tout au long de l'année chez les repousses, grâce à une conductance hydraulique sol-feuille deux fois plus élevée que chez les arbustes matures. Enfin, la durée de vie des feuilles s’allonge avec l’âge des rameaux d'une année comme avec l'âge du peuplement, tandis que la masse surfacique foliaire augmente progressivement de la même façon quand on passe de la saison des pluies à la saison sèche, quel que soit l'âge du peuplement.Ces traits fonctionnels contribuent à ce que l’espèce puisse à la fois résister aux conditions de sécheresse dans lesquelles elle croît et ré-allouer de façon intense des ressources, stockées probablement dans les racines, à la reconstruction rapide de sa partie aérienne à la suite d'une coupe. Les limites d'une telle stratégie restent cependant à identifier, en particulier le seuil d'épuisement des ressources sous l'effet de la répétition annuelle des coupes
Sahel suffered from severe rainfall decreases combined to great changes in land use during the last decades that led to strong decrease in the woody cover. However, Guiera senegalesis J.F. Gmel is a semi-evergreen Combretaceae whose dominance rose with crop pressure in the Sudano-Sahelian band where it plays an important socio-economic role through agroforestry. Consequently, this is a good model to study hydric responses of the present woody cover to drought and the effect of cutting on these responses.The aims of this work were: 1) to characterize and quantify hydric regulation processes in G. senegalesis and to determine its specific functional limits, in order to estimate its safety margin in its current growth conditions, 2) to estimate cut effect on these processes and 3) to analyze variations of its leaf traits according to the season and its specific growth conditions.Measurements and observations were conducted from April 2009 to February 2011 on an old fallow, on a young fallow, and on the two crop fields adjacent to the two fallows respectively. At the shrub scale, leaf water potential and stomatal conductance were measured during the two growing seasons on shrub samples in the three cover type. The leaf transpiration rate and the soil-to-leaf conductivity were deduced. At the stem scale, the dynamics of the number of leaves, the mean leaf area (LMA), the mean diameter of the stems that carry them, the mean leaf life span, and the leaf mass per area were monitored. The species vulnerability curve to cavitation, which is the loss of conductivity as a function of the water potential, was obtained from several peaces of branches treated in a CAVITRON at the laboratory.The main results obtained were that the stomatal closure that allows species to regulate its water loss occurs at a low rate of xylem cavitation (30%). Thus, the species can survive in its Sahelian conditions thanks to a positive “safety margin” of +0.6 MPa. Stomatal regulation coupled with leaf adjustment allows the species to maintain its water balance during the dry season in mature and undisturbed shrubs. The decrease in predawn and midday leaf water potentials in response to seasonal drought was isohydrodynamic, and it was greater in mature shrubs, suggesting that current year resprouts are under less stress. In addition, cutting decouple leaf adjustment from stomatal regulation, leading to continuous leaf production and young stem growth all over the year, thanks to a soil-to-leaf conductivity seven times higher in the current year's resprouts than in the mature shrubs. Finally, leaf life span increases with the current year's stem age as well as with the stand age, while the LMA progressively increases from the rainy season to the dry season, similarly whatever the stand age.These functional traits contribute to the species resistance to the drought conditions under which it grows, but also, following the cutting, to intensively re-allocate resources, probably from the root reserve, to the fast re-building of the aerial part. However, the limits of such a strategy remain to be identified, especially the resource exhaustion threshold under repetitive yearly cutting

Le mémoire traite de la machine à réluctance variable en proposant d'une manière simultanée et du point de vue conception des solutions à ses deux inconvénients majeurs à savoir les ondulations de couple et les efforts radiaux. Les premières se propagent le long de la chaine de transmission diminuant ainsi le confort des usagers et les deuxièmes sont à l’origine d’une nuisance sonore. Dans une première partie et en s’intéressant à une structure axiale caractérisée par une faible force radiale, un bilan sur cette structure est donc établi. En effet, une configuration à deux stators et un rotor est la plus adéquate pour éventuellement remplacer la machine radiale de référence. Cette structure axiale est comparée à cette machine de référence après avoir établi des règles de passage d’une structure à une autre. Un premier passage est effectué en gardant le même encombrement et un deuxième passage en dimensionnant la machine axiale pour satisfaire le même cahier des charges que la machine radiale. Dans une deuxième partie, le travail s’oriente vers la modification de la structure radiale de la machine de référence et son optimisation. Plusieurs modifications sont proposées dont une structure avec une cale magnétique qui est la plus performante. Des optimisations géométriques à l’aide de l’algorithme génétique sur un point de fonctionnement sont ensuite effectuées pour remédier aux deux problèmes. A la fin, un récapitulatif de plusieurs structures optimisées est proposé pour servir de référence. Le choix de la machine la plus adéquate pourra donc être effectué en faisant un compromis entre la maximisation du couple, la réduction de ses ondulations et la réduction des efforts radiaux
This report deals with switched reluctance motor by offering design solutions to the drawbacks of torque ripples and radial forces in the same time. Torque ripples reduce the user comfort and radial forces are the origin of noise. In the first part, an axial structure characterized by low radial force is analysed. Indeed, an axial configuration with two stators and one rotor is the most appropriate to replace the reference radial machine. Ones the rules of passage from one structure to another are established, the axial structure is then compared to the reference one. A first passage is made by keeping the same volume and a second one by sizing the axial machine with the same specifications as the radial one. In the second part, the work concerns the modification of radial structure of the reference machine and its optimization. Several modifications are proposed including a structure with a magnetic wedge which is the most efficient. Geometric optimization using genetic algorithm are then performed on operating points to remedy the both problems. In the end, several optimized structures are proposed. The choice of the most suitable machine can be done by making a compromise between the torque maximization, reducing its ripples and reducing radial forces

Cette thèse a pour objectif ultime d'améliorer notre compréhension de la réflexion de la lumière sur des surfaces micro-courbes, en particulier lorsque les dimensions physiques des surfaces (rayons de courbure de l'ordre de 50-300 μm) sont comparables aux paramètres dimensionnels d'un faisceau optique Gaussien, typique des faisceaux issus d'une fibre optique ou d'un microlaser. A cet effet, une étude théorique et des simulations numériques ont été menées ; elles ont été confrontées à une étude expérimentale. Pour ce faire, la réalisation des micro-miroirs à concavité contrôlée n'étant pas chose aisée, un premier jalon de cette thèse a consisté à atteindre les avancées technologiques nécessaires à la réalisation de tels micro-miroirs(par procédé de gravure plasma de type DRIE) en vue de leur caractérisation expérimentale. Une motivation importante du choix de ce sujet est son potentiel applicatif à la réalisation de micro-bancs optiques sur puce silicium, de sorte à augmenter les capacités de couplage et de manipulation de lumière de façon intégrée dans un espace ultra-compact. A titre d'illustration des possibilités de la nouvelle micro-instrumentation optique que nous proposons, nous avons conçu et réalisé un microsystème de balayage spatial à grand angle (110°) d'un faisceau laser dont le spot optique ne se déforme pas tout au long de l'opération de balayage, ce qui en fait, entre autres, la pièce maîtresse de systèmes portables d'imagerie médicale par tomographie à cohérence optique
The ultimate objective of this thesis is to improve our understanding of light reflection on micro-curved surfaces, especially when the physical dimensions of the surfaces (radii of curvature in the order of 50-300 microns) are comparable to typical dimensional parameters of a Gaussian optical beam, such as those coming from an optical fiber or from a micro-laser. To this end, a theoretical study and numerical simulations were conducted; they were confronted with an experimental study. To do this, the realization of micro-mirrors controlled concavity being not easy, a first step of this thesis was to achieve the technological advances necessary for the realization of such micro-mirrors (by plasma etching method of DRIE type) for their subsequent experimental characterization. An important motivation for choosing this topic is its potential application in the production of micro-optical benches on a silicon chip, so as to increase the coupling efficiencies and capabilities of manipulation of light, in an integrated way and in an ultra compact space. As an illustration of the new micro-optical instrumentation which is attainable, we have designed and implemented a micro-device able of wide-angle (110 °) spatial scanning of a laser beam, the optical spot being not deformed during the scanning operation, which makes this device, the centerpiece of portable medical imaging systems by optical coherence tomography, among others

Under hösten 2019 har Vattenfall Research & Development byggt en experimentell jordfyllningsdamm i Älvkarleby med dimensionerna 20x15x4 meter. Delar av experimentdammen är konventionellt konstruerade och har installerats med geoteknisk utrustning som utgörs av bland annat inklinometrar och portrycksgivare. Andra delar av experimentdammen har byggts in med defekter som ska representera åldersrelaterade skador eller utförandefel vid konstruktion. Experimentdammen ger möjlighet att under realistiska och kontrollerade förhållanden studera det mekaniska beteendet i samband med fyllning av vatten och vidare drift med hjälp av den geotekniska instrumenteringen samt med stöd av numerisk modellering. I detta examensarbete, som utgör en del av Luleå tekniska universitets forskningsprojekt mot experimentdammen, har experimentdammens beteende i form av deformationer och portryck studerats under uppfyllnad och drift fram till sommaren 2021. Detta har utförts genom simuleringar i det finita elementprogrammet PLAXIS 2D 2019 för en tvärsektion av experimentdammen i plant-deformationstillstånd. Mätpunkterna i modellen har baserats på faktisk placering av den geotekniska instrumenteringen. Den finita elementmodellen av experimentdammen har konstruerats och fyllts med vatten enligt dokumentation från fält. En flödes-deformationsanalys, med den konstitutiva modellen Hardening Soil och den hydrauliska modellen van Genuchten, har tillämpats för att modellera den simultana utvecklingen av portryck och deformationer under uppfyllnad. Materialparametervärden för den finita elementmodelleringen har erhållits från Vattenfall R&D, relevant litteratur och från fält- och laboratorieförsök. I fält har vattenvolymeterförsök utförts på tätkärnan och i laboratoriemiljö har modifierad proctorpackning, dränerade konventionella triaxialförsök, permeabilitetsförsök och övertryckskapillarimeterförsök utförts på tätkärnans material. Resultatet från övertryckskapillarimeterförsök har anpassats mot den hydrauliska modellen van Genuchten för att uppskatta en vattenbindningskurva som beskriver det icke-linjära förhållandet mellan jordens vatteninnehåll och porundertryck, det vill säga det omättade förhållandet. Vattenbindningskurvor för övriga materialzoner har uppskattats baserat på litteratur. Verktyget PLAXIS SoilTest har använts för att optimera materialparametervärden för tätkärnan mot resultat från utförda triaxialförsök. Materialparametrarna E50ref, Eoedref, Eurref, m, c, och ϕ har optimerats fram till brott i triaxial belastning. En känslighetsanalys har utförts för reduktion av filterzonernas och stödfyllningens styvhetsmoduler och deras inverkan på horisontella deformationer i dammkroppen under uppfyllnad. Känslighetsanalysen indikerar att finfiltrets styvhetsmoduler har störst inverkan och grovfiltrets styvhetsmoduler har minst inverkan på de horisontella deformationerna. Studiens resultat visar att magnituden av horisontella och vertikala deformationer kommer vara som störst i den övre delen av dammkroppen och uppgår där till 3,5 respektive 4,0 mm. Dammkroppens huvudsakliga rörelse kommer vara i nedströms riktning och det observerades hur en kontaktzon mellan uppströms filterzon och tätkärnan utgör en gräns för riktning av deformationer. Faktiskt uppmätta rörelser i installerade inklinometrar kunde inte jämföras mot deformationer i den finita elementmodellen eftersom författarens tolkning indikerar på att botten av inklinometrarna har rört på sig, och mätpunkterna i botten av modellen är fixerade. Modellen visar hur en fördröjd utveckling av vattenmättnad sker genom tätkärnan, där uppströms sida av tätkärnan reagerar snabbare på förändringar i vattennivå jämfört med nedströms sida av tätkärnan som uppvisar en fördröjd respons. Vid en sänkning av vattennivån observerades hur tätkärnan håller kvar vatten ovan portryckslinjen medan de grövre materialen dränerar i takt med vattennivåns sänkning. Utvecklingen av de simulerade portrycken i modellen under uppfyllnad och drift överensstämmer bra med de uppmätta portrycken i experimentdammen, när portrycken är positiva. Det observeras hur den finita elementmodellen överskattar negativa portryck (porundertryck). Portrycken i modellen når ett stadigt tillstånd ungefär 115 dagar efter att fyllningen av vatten påbörjats. Den finita elementmodellen lyckas att återge det teoretiska beteendet av jordfyllningsdammar under fyllning i form av huvudsakliga riktningar av deformationer och utveckling av vattenmättnad i tätkärnan. Denna studie bidrar till en djupare förståelse för experimentdammens, och i allmänhet jordfyllningsdammars, mekaniska beteende under uppfyllnad. Resultaten från den finita elementmodellen kan ur ett dammsäkerhetsperspektiv användas för erhålla indikationer på utvecklingen av deformationer, portryck och vattenmättnadsgrad i jordfyllningsdammar under uppfyllnad, och även under en tillfällig sänkning av vattennivån under den första fyllningen. Studien ger också indikationer på vilka materialparametrar som är viktiga vid numerisk modellering av mekaniskt beteende i jordfyllningsdammar.
During the autumn of 2019, Vattenfall Research & Development constructed an experimental embankment dam in Älvkarleby with the dimensions 20x15x4 metres. Parts of the experimental dam are conventionally constructed and have been equipped with geotechnical instrumentation which consist of, among other things, inclinometers and pore pressure transducers. Other parts of the experimental dam have built in defects to represent age-related damages or execution errors during construction. The experimental embankment dam provides the opportunity to, under realistic and controlled conditions, study the mechanical behaviour during filling of water and operation by means of the geotechnical instrumentation and the use of numerical modelling. In this master’s thesis, which forms part of Luleå University of Technology’s research project towards the experimental dam, the behaviour of the experimental dam in terms of deformations and pore pressures have been studied during filling and operation until the summer of 2021. This has been performed by simulations in the finite element program PLAXIS 2D 2019 for a cross section of the experimental dam under plane-strain conditions. Measuring points in the model have been based on the actual location of the geotechnical instrumentation. The finite element model of the experimental dam has been constructed and filled according to documentation from field. A fully-coupled flow deformation analysis, with the constitutive model Hardening Soil and hydraulic model van Genuchten, has been utilised to model the simultaneous development of pore pressure and deformations during filling. Values of material parameters for the finite element modelling have been received from Vattenfall R&D, relevant literature and from field- and laboratory tests. In the field, balloon tests have been performed on the core material. In laboratory environment, modified proctor compaction tests, drained conventional triaxial tests, permeability tests and pressure plate tests have been performed on the core material. Results from the pressure plate tests have been adapted to the hydraulic model van Genuchten to estimate a soil-water characteristic curve in order to describe the non-linear relation between the water content and suction in the soil, i.e. unsaturated conditions. Soil-water characteristic curves for the other material zones have been estimated based on literature. The tool PLAXIS SoilTest has been used to optimise material parameter values of the core against the results from conducted triaxial tests. The material parameters E50ref, Eoedref, Eurref, m, c, and ϕ have been optimised until failure in triaxial loading. A sensitivity analysis has been carried out, by reducing stiffness moduli of the filter zones and the shoulder material, to investigate the influence on horizontal deformations in the dam body during filling. The sensitivity analysis indicates that the stiffness moduli of the fine filter have the largest impact and the stiffness moduli of the coarse filter have the least impact on the horizontal deformations. The results of the study show that the magnitude of horizontal and vertical deformations will be largest in the upper part of the dam body and amounts to 3.5 and 4.0 mm, respectively. The main movement of the dam body will be in the downstream direction and it was observed how a contact zone between the upstream filter zone and the core forms a boundary for direction of deformations. Actual measured movements in the installed inclinometers could not be compared to deformations in the finite element model because the author’s interpretation indicates that the bottom of the inclinometers have moved, and the measuring points at the bottom of the model are fixed. The model shows how a delayed development of saturation occur through the core, where the upstream side of the core responds more quickly to changes in water level compared with the downstream side of the core which show a delayed response. At a lowering of the water level, it was observed how the core retains water above the phreatic line while the coarser materials drain as the water level decreases. Development of the simulated pore pressures in the model during filling and operation corresponds well with the measured pore pressures in the experimental dam, when the pore pressures are positive. It is observed how the finite element model overestimates negative pore pressures (suction). The pore pressures in the model reaches a steady state approximately 115 days after filling of water started. The finite element model succeeds in reproducing the theoretical behaviour of embankment dams during filling in terms of main directions of deformations and development of saturation in the core. This study contributes to a deeper understanding of the experimental dam, and in general mechanical behaviour of embankment dams during filling. The results from the finite element model can be used from a dam safety perspective to obtain indications on the development of deformations, pore pressures and degree of saturation in embankment dams during filling, and also for a temporary lowering of the water level during the first filling. The study also provides indications of which material parameters that are of importance in numerical modelling of mechanical behaviour in embankment dams.

Gelfill (GF) is made of tailings, water, binder and chemical additives (Fillset, sodium silicate gel). The components of GF are combined and mixed on the surface and transported (by gravity and/or pumping) to the underground mine workings, where the GF can be used for both underground mine support and tailings storage. Thermal (T), hydraulic (H), and mechanical (M) properties are important performance criteria of GF. The understanding of these engineering properties and their evolution with time are still limited due to the fact that GF is a new cemented backfill material. In this thesis, the evolution of the thermal, hydraulic, mechanical, and microstructural properties of small GF samples are determined. Various binder contents of Portland cement type I (PCI) are used. The GF is cured for 3, 7, 28, 90, and 120 days. It is found that the thermal, hydraulic and mechanical properties are time-dependent or affected by the degree of binder hydration index. Furthermore, a relationship is found between the compressive strength and the saturated hydraulic conductivity of the GF samples. The unsaturated hydraulic properties of GF samples have also been investigated. The outcomes show that unsaturated hydraulic conductivity is influenced by the degree of binder hydration index and binder content, especially at low suction ranges. Simple functions are proposed to predict the evolution of air-entry values (AEVs), residual water content, and fitting parameters from the van Genuchten model with the degree of hydration index (α). Furthermore, two columns are built to simulate the coupled thermo-hydro-mechanical (THM) behaviour of GF under drained and undrained conditions. The obtained results from the GF columns are compared with the small samples. It is observed that the mechanical properties, hydraulic properties (suction and water content), and temperature development are strongly coupled. The magnitude of these THM coupling factors is affected by the size of the GF. The findings also show that the mechanical, hydraulic and thermal properties of the GF columns are different from samples cured in plastic moulds.

Cette thèse aborde l'un des sujets les plus discutés et en vogue dans le domaine de l'économie, à savoir le lien entre le développement économique et la qualité environnementale. En particulier, on met l’accent sur les effets du développement économique—tant dans ses dimensions économique, sociale que politique—sur la qualité de l'environnement pour les économies en développement et en transition. Le chapitre I, divisé en trois phases clés, à savoir la revue de la littérature théorique, la partie empirique et la revue de la littérature empirique, contribue à la littérature en donnant diverses informations sur le lien entre la croissance économique et la pollution de l'environnement dans les économies en développement et en transition. Globalement, les résultats révèlent que des études empiriques récentes, parvenant à réduire certaines lacunes suggérées par la théorie, pourraient en effet indiquer un certain consensus sur la relation entre la croissance et la pollution, à savoir la validité de l'hypothèse de la Courbe de Kuznets Environnementale (CKE). Le chapitre II examine le lien pollution-croissance dans les pays d'Europe Centrale et Orientale (PECO), en ajoutant à la littérature empirique l’utilisation de l'hypothèse étendue de l'CKE comme cadre théorique. D'une part, il révèle un lien de croissance non linéaire entre le PIB et le CO2 agrégé, qui est fortement robuste pour différents estimateurs et variables de contrôle. En revanche, l'analyse au niveau des pays révèle que la relation entre le PIB et le CO2 se caractérise par une grande diversité dans les PECO. Ainsi, malgré une tendance globale à la hausse, certains PECO ont réussi à assurer à la fois un PIB plus élevé et une réduction des émissions de CO2. Du point de vue politique, les décideurs de l'UE pourraient accorder plus d'attention à ces pays, c'est-à-dire envisager une intégration plus rigoureuse des hétérogénéités des pays et, en même temps, soutenir la croissance économique sans nuire à l'environnement. Le chapitre III étudie la réponse des émissions de CO2 agrégées et sectorielles résultant des perturbations externes du PIB et de l'urbanisation, en supposant un canal de transmission qui intègre deux des éléments clés utilisés dans la lutte contre la dégradation de l'environnement—les énergies renouvelables et l'efficacité énergétique. Les résultats, robustes à plusieurs spécifications alternatives, indiquent que la production globale, l'urbanisation et l'intensité énergétique augmentent les émissions totales de CO2, tandis que les énergies renouvelables ont l'effet inverse. Par ailleurs, en ce qui concerne la réponse du CO2 aux chocs de production et d'urbanisation, le modèle suggère que ces pays atteindront le seuil maximum qui conduirait à un changement de la tendance des émissions à la baisse. Cependant, les résultats varient en fonction du niveau de revenu et du statut des pays sur la ratification/l'adhésion au Protocole de Kyoto. Ensuite, l'analyse sectorielle montre que les transports, les bâtiments et les secteurs non-combustion sont plus susceptibles de contribuer à l'augmentation des niveaux futurs de CO2. En général, ce chapitre peut fournir des informations précieuses sur les perspectives de durabilité environnementale dans les pays en développement. Le chapitre IV explore les effets de la stabilité politique sur la dégradation de l'environnement, donnant une perspective renouvelée sur ce sujet dans les pays en développement. Il montre qu'une évolution non linéaire en forme de cloche décrit la relation entre les variables au niveau agrégé. De plus, bien que ce résultat reste stable pour plusieurs spécifications alternatives, nous identifions des hétérogénéités significatives dans les caractéristiques distinctes des pays et les mesures alternatives de pollution. En outre, des estimations désagrégées révèlent des schémas contrastés pour la relation entre le CO2 et la stabilité politique. (...)
This thesis tackles one of the most debatable and in vogue topics in economics, namely the economic development and environmental quality nexus. Notably, it studies the economic development's effects—in terms of its economic, social, and political dimensions—on the environmental quality for developing and transition economies. Chapter I, which is divided into three key phases, namely theoretical review, empirical exercise, and empirical review, contributes to the literature by giving various insights regarding the link between economic growth and environmental pollution in developing and transition economies. Overall, it reveals that the recent empirical studies, indeed, succeeding to curtail some of the deficiencies suggested by theoretical contributions, might indicate a certain consensus regarding pollution-growth nexus and Environmental Kuznets Curve (EKC) hypothesis validity. Chapter II examines the pollution-growth nexus in Central and Eastern European (CEE) countries, adding to the related empirical literature using the extended EKC hypothesis as a theoretical background. On the one hand, it unveils an increasing nonlinear link between GDP and CO2 at the aggregate level, which is powerfully robust to different estimators and control variables. On the other hand, the country-level analysis reveals that the relationship between GDP and CO2 is characterized by much diversity among CEE countries. Thus, despite an aggregated upward trend, some CEE countries managed to secure both higher GDP and lower CO2 emissions. From a policy perspective, EU policymakers could pay more attention to these countries and amend the current unique environmental policy to account for country-heterogeneities to support economic growth without damaging the environment. Chapter III investigates the aggregated and sector-specific CO2 emissions' responsiveness following exogenous shocks to growth and urbanization, considering a transmission scheme that incorporates two of the widely used instruments in mitigating environmental degradation—renewables and energy efficiency. First, robust to several alternative specifications, the results indicate that output, urbanization, and energy intensity increase the aggregated CO2 emissions, while renewable energy exhibits an opposite effect. Moreover, regarding the CO2 responsiveness in the aftermath of output and urbanization shocks, the pattern may suggest that these countries are likely to attain the threshold that would trigger a decline in CO2 emissions. However, the findings are sensitive to both countries' economic development and Kyoto Protocol ratification/ascension status. Second, the sector-specific analysis unveils that the transportation, buildings, and non-combustion sector exhibits a higher propensity to increase the future CO2 levels. Generally, this chapter may provide useful insights concerning environmental sustainability prospects in developing states. Chapter IV explores the effects of political stability on environmental degradation, giving a renewed perspective on this topic in developing states. It shows that a nonlinear, bell-shaped pattern characterizes the relationship between variables at the aggregate level. Moreover, while this result is robust to a broad set of alternative specifications, significant heterogeneities are found regarding countries' distinct characteristics and alternative pollution measures. Besides, the country-specific estimates unveil contrasting patterns regarding the relationship between CO2 and political stability. Broadly speaking, the findings suggest that both the formal and informal sides of political stability play a vital role in mitigating CO2 pollution in developing countries, and may provide meaningful insights for policymakers. (...)

碩士
國立高雄第一科技大學
機械與自動化工程研究所
102
The dimensional synthesis of linkage includes three types: function generation, motion generation and path generation, where the path generation is to generate the dimensions of a linkage that the coupler curve is identified with the specified curve. The more points they fit, the better the result. Path generation is applied to various mechanism design for searching of dimensional synthesis of four-bar linkage to fit the desired coupler curve. Since the coupler curve is a multivariable nonlinear curve, the optimization method is always used to find the dimensions of linkage for matching of the coupler curve. The object of this paper is to apply the equation of couple curve with Genetic Algorithm to generate the dimension of six-bar linkage for matching two separated coupler curves. The Watt-II type of six-bar linkage is selected for its combination of two four-bar linkage that could generate two separated coupler curve. Two position vector loops are derived to analyze the motion of six-bar mechanism. Then, bases on the connectivity of linkage to get the length of each link and relevant angles. Next, adjusts the objective function for the optimum design by utilizing the relationship between the coordinate points and the curve equation. Finally, combines with the Genetic Algorithm and the proposed optimum model to find the optimal dimensions of the six-bar linkage and the position of fixed axle that is identical with the specified double coupler curves. The results are successfully applied to find the dimensions of a six-bar rear suspension mechanism of mountain bike.

博士
國立成功大學
機械工程學系碩博士班
93
This dissertation presents the triangular nomograms for spherical four-bar linkages generating symmetrical coupler curves, and proposes a methodology for the optimal synthesis of spherical four-bar path generators without defects with the aid of the initial guesses provided by the triangular nomograms. 　　The geometric conditions, design parameters, and kinematic properties of the spherical crank-rockers, double-cranks, double-rockers, and non-Grashof double-rockers tracing symmetrical coupler curves are analyzed comprehensively. According to the results of kinematic analysis for these spherical four-bar linkages, some special symmetrical coupler curves are found and investigated, and the corresponding geometric relations for them are used to derive the implicit equations consisting of the dimensional parameters. Nine triangular nomograms for the spherical four-bar linkages are then presented for the determination of dimensional parameters of a linkage generating the desired coupler curve without further calculation. Therefore, these triangular nomograms can be served as important tools for the design of spherical four-bar path generators. 　　In order to avoid the order defect, circuit defect, and branch defect that may occur in the synthesis results, the dissertation studies the characteristics of circuits and branches of spherical four-bar path generators and also presents a suitable and effective identification method for each defect. Hence, the identification methods are integrated with the optimization problem for the dimensional synthesis of spherical four-bar path generators without defects based on the initial guesses obtained from the triangular nomograms. 　　Two examples are illustrated to show that the integration of the triangular nomograms with the optimization scheme presented in the dissertation is effective for the synthesis of spherical four-bar path generators.

博士
國立成功大學
機械工程學系
86
The shape of coupler curves is complicated and abundant, and it has many engineering applications. However, the investigation on the coupler curve of aspatial linkage with five and more links is limited due to its algebraic complexity. The purpose of this work is to present a systematic approach for investigating the properties of the coupler curves generated by all 3R2C linkages. The mathematical software, Mathematica, is used in the derivation ofthe related equations. First, the coordinate systems of 3R2C linkages are established based on the dual number notation. Then, the 3×3 matrix with dualelements is used to derive the loop closure equations of the linkages. After that, the displacement equations are derived and all joint variables are expressed in terms of input and output variables. The parametric equations of the coupler curve are found by the D-H matrix. Finally, homogeneous coordinate is introduced to those displacement equations, and the order and some critical properties of the coupler curve are investigated based on the theories of algebraic curve and analytical geometry of three dimensions. The results show that the proposed method can be applied effectively on the examination of order, class, freedom, and imaginary circular point of all 3R2Clinkages. Also, their applications in dimensional synthesis are also discussed. The results are helpful for the further analysis and dimensional synthesis of 3R2C linkages. And, since the presented method is systematic, it can be applied to the investigation on the coupler curves of other spatial five-bar linkages.

碩士
國立成功大學
土木工程學系
106
In this paper the authors extend the finite layer methods for simply-supported, laminated composite plates to those for simply-supported, doubly curved (DC) shells with thickness- material properties. The specified temperature conditions are prescribed on the top and bottom surfaces of the DC shell. A two-phase composite material is considered with two different models of the material properties (i.e., the power-law and sigmoid function models) according to the volume fractions of the constituents through the thickness direction of the shell. The effective material properties are estimated using the Mori-Tanaka model. A unified weak-form formulation of the finite doubly curve layer (FDCL) methods is derived on the basis of Reissner’s mixed variational theorem (RMVT), and the system equations in the shell domain are derived. The accuracy and convergence rate of these RMVT-based FDCL methods are validated by comparing their solutions with the quasi three-dimensional and accurate two-dimensional solutions available in the literature.

碩士
國立清華大學
動力機械學系
82
In this study, symmetrical coupler curve mech- anism was obtained with adepting motion generation to synthesize two and three precise points. The solution for symmetrical coupler curve mechanism through two precise points is a plane. The extent of solution will be wider than that of three precise points due to one more precise restricted points, thus the solution for three precise points is a collection of some certain points. For two precise points problem, in addition to length of linkage and transmission angle,such res- tricted condition as symmetric axis and mechanical advantage (M.A) should be also taken into consi- deration to achieve the optimal mechanism. Besides, the problem of three precise points concerning with certain M.A is mentioned as well as Grashoff problem and Branch problem. Finally, their planar solution and characteristecs can be reched with the help of computer graphics and ani- mated simulation.

This thesis analyzes different light localization phenomena in waveguide arrays. We report on the observation of quasi-Bloch oscillations, a new type of dynamic localization in the spatial evolution of light in curved, coupled optical waveguides. The delocalization and final relocalization of an optical beam in a waveguide array is shown by spatially resolving the optical intensity at various propagation distances. Through comparison to different structures, quasi-Bloch oscillations are shown to be robust beyond the nearest-neighbor tight-binding approximation.

碩士
國立中正大學
機械系
90
In this paper four control points are defined to control and regulate the coupler curve of the Watt-I type six-bars linkages. The relation between linkages size and four control points on the coupler curve are set up with back-propagation neural networks. By using the system which has been trained, we can change the shape of the coupler curve with moving control points and result the Watt-I type six-bars linkages. 　　First, we decompose six-bars linkages to become two vector circuit of the four-bars linkages and then use the branch of the linkages to find the relationship between numbers of the coupler curve and linkages. Second, we make the training data and testing data by using the symmetrical characteristic of the coupler curve. Third, training these data with back-propagation neural networks, establishing the relationship between control points and linkages size, and let network system which has been trained well to be the system function of the synthesis of the coupler curve. Finally, to develop the computer program of coupler curve of the Watt-I type six-bars linkages by using the system function. Let user can synthesize coupler curve and the size of Watt-I type six-bars linkages easy and fast.

碩士
國立中正大學
機械系
87
The purpose of this paper is to propose a methodology to synthesize a four-bar linkage with a desired coupler curve. In this method, four control points are defined to determine the shape of the desired coupler curve. By employing a radial-basis-function neural network, a coupler curve generator is established to relate the control points to the size of the four-bar linkage. When one of the control points is moved, the shape of the coupler curve will be changed and the corresponding four-bar linkage well be generated. In this paper, four control points of a coupler curve is defined based on the symmetry and divide equally characteristics. Next, according to Grashof’s criterion, the range of the length of links is determined to classify the linkages into several types. In each type, various linkages with different sizes are generated to produce their coupler curves and the corresponding control points. The sizes and the control points form training pairs for the RBF neural network. Finally, the computer program for the RBF neural network is implemented in the PC Window environment by C++ computer language. This paper provides a novel approach for the generation of the coupler curves. Using an RBF neural network as a core, the coupler curve generator is compact and efficient. The results of this paper are beneficial to the dimensional synthesis of linkages.

碩士
國立臺北科技大學
光電工程系
106
In this paper, ultrahigh-resolution and ultrabroad-range refractive index sensors are fabricated by using high-refractive-index dual curved waveguides. The width of waveguide and the radius of curvature of the dual curved waveguide are simulated to achieve the design of the refractive index sensor. Compared with most of the refractive index sensor research, most of the spectrum measurement methods, using the spectrometers can not only be integrated and the detection range is not large, so we propose that the energy detection method can not only combine the integrated detectors to achieve integration but also can increase the measurement range by using high refractive index materials. This structure which can reduce process difficulty and time is relatively simple to use a single material in the process than other surface plasma resonance biosensor. In this thesis, the conformal transformation theory is used to convert the curved waveguide into a straight waveguide, and the width and radius of curvature parameters of the semiconductor material in the curved waveguide are calculated. The finite time domain difference method (FDTD) is used to solve the actual electromagnetic field. The mutual propagation and coupling in the waveguide, and the change of the light intensity at the output end of the inner waveguide when changing the refractive index of the environment are discussed, and the quasi-linear result is obtained. The structure is designed in the near-infrared band, λ= 1.55 um, and the maximum refractive index range is 1-3, and the refractive index unit is 6.6×10-10 RIU. This simulation result is the highest detection range and highest refractive index resolution in current sensor research.

Moisture can significantly affect flexible pavement performance. As such, it is crucial to remove moisture as quickly as possible from the pavements, mainly to avoid allowing moisture into the pavement subgrade. In the 1990s the Indiana Department of Transportation (INDOT) adopted an asphalt pavement drainage system consisting of an open-graded asphalt drainage layer connected to edge drains and collector pipes to remove moisture from the pavement system.

Over the intervening two decades, asphalt pavement materials and designs have dramatically changed in Indiana, and the effectiveness of the pavements drainage system may have changed. Additionally, there are challenges involved in producing and placing open-graded asphalt drainage layers. They can potentially increase costs, and they tend to have lower strength than traditional dense-graded asphalt pavement layers.

Given the potential difficulties, the overall objective of this research was to evaluate the effectiveness of the INDOT’s current flexible pavement drainage systems given the changes to pavement cross-sections and materials that have occurred since the open-graded drainage layer was adopted. Additionally, the effectiveness of the filter layer and edge drains were examined.

Laboratory experiments were performed to obtain the hydraulic properties of field-produced asphalt mixture specimens meeting INDOT’s current specifications. The results were used in finite element modeling of moisture flow through pavement sections. Modeling was also performed to investigate the rutting performance of the drainage layers under various traffic loads and subgrade moisture conditions in combination with typical Indiana subgrade soils. The modeling results were used to develop a design tool that can assist the pavement designer in more accurately assessing the need for pavement drainage systems in flexible pavements.