Dissertations / Theses on the topic 'Coupling with floating object'

Dans cette Thèse de Doctorat, nous nous intéressons à deux problématiques: (i) le développement de stratégies de stabilisation pour des méthodes de type discontinuous Galerkin (DG) appliquées à des écoulements shallow-water fortement non-linéaires, (ii) le développement d'une stratégie de modélisation et de simulation numérique des interactions non-linéaires entre les vagues et un objet flottant en surface, partiellement immergé. Les outils développés dans le cadre du premier axe de travail sont mis à profit et valorisés au cours de la deuxième partie.Les méthodes de discrétisation de type DG d'ordre élevé présentent en général des problèmes de robustesse en présence de singularités de la solution. Ces singularités peuvent être de plusieurs natures: discontinuité de la solution, discontinuité du gradient ou encore violation de la positivité de la hauteur d'eau pour des écoulements à surface libre. Nous introduisons dans la première partie de ce manuscript deux approches de type Finite-Volume Subcells permettant d'apporter une réponse à ces problèmes de robustesse. La première approche repose sur une correction a priori du schéma DG associée à un limiteur TVB et un limiteur de positivité. La seconde approche s'appuie quant à elle sur une correction a posteriori permettant d'identifier avec une meilleure précision les cellules incriminée, ainsi que sur les propriétés de robustesse inhérentes au schéma Volumes-Finis limite d'ordre un. Cette seconde approche permet d'assurer la robustesse du schéma DG initial en présence de discontinuité, ainsi que la positivité de la hauteur d'eau, tout en préservant une excellente qualité d'approximation, bénéficiant d'une résolution de l'ordre de la sous-maille. De façon préliminaire, cette seconde approche est également étendue au cas de la dimension deux d'espace horizontal. De nombreux cas-test permettent de valider cette approche.Dans la seconde partie, nous introduisons une nouvelle stratégie numérique conçue pour la modélisation et la simulation des interactions non linéaires entre les vagues en eau peu profonde et un objet flottant partiellement immergé. Au niveau continu, l'écoulement situé dans le domaine extérieur est globalement modélisé par les équations hyperboliques non-linéaires de Saint-Venant, tandis que la description de l'écoulement sous l'objet se réduit à une équation différentielle ordinaire non linéaire. Le couplage entre l'écoulement et l'objet est formulé comme un problème au bord, associé au calcul de l'évolution temporelle de la position des points d'interface air-eau-objet. Au niveau discret, la formulation proposée s'appuie sur une approximation DG d'ordre arbitraire, stabilisée à l'aide de la méthode de correction locale des sous-cellules (a posteriori) introduite dans la première partie. L'évolution temporelle de l'interface air-eau-objet est calculée à partir d'une description Arbitrary Lagrangian-Eulerian (ALE) et d'une transformation appropriée entre la configuration initiale et celle dépendant du temps. Pour n'importe quel ordre d'approximation polynomiale, l'algorithme résultant est capable de: (1) préserver la loi de conservation géométrique discrète (DGCL), (2) garantir la préservation de la positivité de la hauteur d'eau au niveau des sous-cellules, (3) préserver la classe des états stationnaires au repos (well-balancing), éventuellement en présence d'un objet partiellement immergé.Plusieurs validations numériques sont présentées, montrant le caractère opératoire de cette approche, et mettant en évidence que le modèle numérique proposé: (1) permet effectivement de modéliser les différents types d'interactions vague / objet flottants, (2) calcul efficacement l' évolution temporelle des points de contact air-eau-objet et redéfinit en conséquence le nouveau maillage grâce à la méthode ALE, (3) gère avec précision et robustesse les possibles singularités de l'écoulement, (4) préserve la haute résolution des schémas DG au niveau des sous-cellules
In this Ph.D., we investigate two main research problems: (i) the design of stabilization patches for higher-order discontinuous-Galerkin (DG) methods applied to highly nonlinear free-surface shallow-water flows, (ii) the construction of a new numerical approximation strategy for the simulation of nonlinear interactions between waves in a free-surface shallow flow and a partly immersed floating object. The stabilization methods developed in the first research line are used in the second part of this work.High-order discontinuous-Galerkin (DG) methods generally suffer from a lack of nonlinear stability in the presence of singularities in the solution. Such singularities may be of various kinds, involving discontinuities, rapidly varying gradients or the occurence of dry areas in the particular case of free-surface flows. In the first part of this work, we introduce two new stabilization methods based on the use of Finite-Volume Subcells in order to alleviate these robustness issues. The first method relies on an a priori limitation of the DG scheme, together with the use of a TVB slope-limiter and a PL. The second one is built upon an a posteriori correction strategy, allowing to surgically detect the incriminated local subcells, together with the robustness properties of the corresponding lowest-order Finite-Volume scheme. This last strategy allows to ensure the nonlinear stability of the DG scheme in the vicinity of discontinuities, as well as the positivity of the discrete water-height, while preserving the subcell resolution of the initial scheme. This second strategy is also preliminary investigated in the two dimensional horizontal case. An extensive set of test-cases assess the validity of this approach.In the second part, we introduce a new numerical strategy designed for the modeling and simulation of nonlinear interactions between surface waves in shallow-water and a partially immersed surface piercing object. At the continuous level, the flow located in the textit{exterior} domain is globally modeled with the nonlinear hyperbolic shallow-water equations, while the description of the flow beneath the object reduces to a nonlinear ordinary differential equation. The coupling between the flow and the object is formulated as a free-boundary problem, associated with the computation of the time evolution of the spatial locations of the air-water-body interface. At the discrete level, the proposed formulation relies on an arbitrary-order discontinuous Galerkin approximation, which is stabilized with the a posteriori Local Subcell Correction method through low-order finite volume scheme introduced in the first part. The time evolution of the air-water-body interface is computed from an Arbitrary-Lagrangian-Eulerian (ALE) description and a suitable smooth mapping between the original frame and the current configuration. For any order of polynomial approximation, the resulting algorithm is shown to: (1) preserves the Discrete Geometric Conservation Law, (2) ensures the preservation of the water-height positivity at the subcell level, (3) preserves the class of motionless steady states (well-balancing), possibly with the occurrence of a partially immersed object.Several numerical computations and test-cases are presented, highlighting that the proposed numerical model(1) effectively allows to model all types of wave / object interactions, (2) efficiently provides the time-evolution of the air-water-body contact points and accordingly redefine the new mesh-grid thanks to ALE method (3) accurately handles strong flow singularities without any robustness issues, (4) retains the highly accurate subcell resolution of discontinuous Galerkin schemes

In the past decades, autonomous on-orbit servicing has become a priority for the space industry. One important application is refueling and servicing of satellites. This type of operation requires a system capable of autonomously capturing the client satellite, which is a free-floating object. In this work, a robotic manipulator is used for the interception task. The latter is divided in two phases : the approach and the capture. In the first phase, the pose of the client is estimated and its future trajectory predicted from visual data through a Kalman filter. This information is combined with the robot motion time from a trajectory generator in an iterative procedure to determine the time-optimal interception location. The trajectory of the manipulator is generated from a concatenation of quintics defining the acceleration profile. The robot desired configuration for capture is calculated using the concept of redundancy parameter. In the second phase of the interception, a close-range tracking algorithm is used for fine alignment and capture. The development of the complete interception scheme, simulation and experimental results are presented in this thesis, the latter obtained with the robot-airship facility in the Aerospace Mechatronics Laboratory.
Au cours des dernières décennies, l'utilisation de systèmes autonomes afin d'accomplir des tâches en orbite a reçu de plus en plus d'attention de la part de l'industrie aerospaciale. Le ravitaillement, la mise à jour et la réparation de satellites en orbite représente deux applications intéressantes de cette approche. De telles opérations requièrent un system capable de capturer un satellite défectueux (le client) de façon autonome. Dans le cas présent, un bras manipulateur robotisé est utilisé afin d'intercepter le client. L'interception se divise en deux parties distinctes : l'approche et la capture. La première phase consiste à estimer la pose et la trajectoire future du client à l'aide des données provenant d'un système de vision et d'un filtre de Kalman. Le lieu optimal où l'interception aura lieu est ensuite choisie par iteration en tenant compte des données du filtre et de celles du générateur de trajectoire du robot. Cet dernière est créée par la concaténation de polynômes du cinquième degrée définissant la courbe d'accélération des joints. Lors de la seconde phase, un algorithme de pistage est utilisé afin d'obtenir un alignment plus précis et de capturer le client. Cette thèse présente les détails de la méthode d'interception et expose les résultats de simulations numériques et d'expériences. Les résultats expérimentaux ont été obtenues à l'aide d'un bras manipulateur et d'un ballon à l'hélium imitant la trajectoire d'un satellite dans l'espace.

La thèse vise à étudier l’efficacité et la précision des solveurs NS et SWENSE pour simuler des structures fixes et flottantes. Les deux solveurs sont basés sur OpenFOAM et sont couplés indépendamment avec HOS pour la générationd’onde en termes de domaine et d’approche de décomposition fonctionnelle. Les solveurs sont testés pour trois applications. Les première et deuxième applications présentent l’interaction d’ondes de focalisation avec des cylindresfixes et mobiles et la troisième est l’interaction d’ondes régulières et irrégulières avec la sousstructure de type OC3 Hywind SPAR. Les méthodes et paramètres de génération d’ondes pour les solveurs NS et SWENSE sont discutés endétail pour les ondes régulières, irrégulières et focalisées. Pour vérification, l’incertitude du cas est quantifiée à l’aide de l’approche d’extrapolation de Richardson et validée avec les mesures expérimentales. Une réduction significative de lataille du maillage est prévue dans les deux approches. Pour l’étude de l’interaction des ondes de corps flottant, les amarres sont modélisées de deux façons : en considérant les lignes d’amarrage comme un ressort linéaire avec une raideur de ressort définie et un couplage avec un modèle d’amarrage dynamique (MoorDyn). Les résultats numériques de l’élévation de surface, des mouvements du corps et des tensions d’amarrage sont validés par rapport aux expériences menées dans le projet SOFTWIND, et l’efficacité et la précision des deux solveurs sont comparées
The thesis aims to study the effectiveness and accuracy of the NS and SWENSEbased solvers for simulating fixed and floating structures. Both solvers are OpenFOAM-based and are independently coupled with HOS for wave generation in terms of domain and functional decomposition approach. The solvers are tested for three applications. The first and second applications present the focusing wave interaction with fixed and moving cylinders and the third is the interaction of regular and irregular waves with the OC3 Hywind SPAR type substructure. The wave generating methods and parametersfor NS and SWENSE solvers are discussed in detail for regular, irregular, and focused waves. For verification, the case’s uncertainty is quantified using the Richardson extrapolation approach and validated with the experimental measurements.A significant reduction in the mesh size is predicted in both approaches. For the floating body wave interaction study, the moorings are modelled in two ways: by considering the mooring lines as a linear spring with defined spring stiffnessand coupling with a dynamic mooring model (MoorDyn). The numerical results of surface elevation, body motions, and mooring tensions are validated against the experiments carried out in the SOFTWIND project, and the efficiency andaccuracy of the two solvers are compared

This thesis examines how the objects that we visually perceive in the world are coupled to the actions that we make towards them. For example, a whole hand grasp might be coupled with an object like an apple, but not with an object like a pea. It has been claimed that the coupling of what we see and what we do is not simply associative, but is fundamental to the way the brain represents visual objects. More than association, it is thought that when an object is seen (even if there is no intention to interact with it), there is a partial and automatic activation of the networks in the brain that plan actions (such as reaches and grasps). The central aim of this thesis was to investigate how specific these partial action plans might be, and how specific the properties of objects that automatically activate them might be. In acknowledging that perception and action are dynamically intertwining processes (such that in catching a butterfly the eye and the hand cooperate with a fluid and seamless efficiency), it was supposed that these couplings of perception and action in the brain might be loosely constrained. That is, they should not be rigidly prescribed (such that a highly specific action is always and only coupled with a specific object property) but they should instead involve fairly general components of actions that can adapt to different situations. The experimental work examined the automatic coupling of simplistic left and right actions (e.g. key presses) to pictures of oriented objects. Typically a picture of an object was shown and the viewer responded as fast as possible to some object property that was not associated with action (such as its colour). Of interest was how the performance of these left or right responses related to the task irrelevant left or right orientation of the object. The coupling of a particular response to a particular orientation could be demonstrated by the response performance (speed and accuracy). The more tightly coupled a response was to a particular object orientation, the faster and more accurate it was. The results supported the idea of loosely constrained action plans. Thus it appeared that a range of different actions (even foot responses) could be coupled with an object's orientation. These actions were coupled by default to an object's X-Z orientation (e.g. orientation in the depth plane). In further reflecting a loosely constrained perception-action mechanism, these couplings were shown to change in different situations (e.g. when the object moved towards the viewer, or when a key press made the object move in a predictable way). It was concluded that the kinds of components of actions that are automatically activated when viewing an object are not very detailed or fixed, but are initially quite general and can change and become more specific when circumstances demand it.

Cohesion and coupling are considered amongst the most important properties to evaluate the quality of a design. In the context of OO software development, cohesion means relatedness of the public functionality of a class whereas coupling stands for the degree of dependence of a class on other classes in OO system. In this thesis, a new metric has been proposed that measures the class cohesion on the basis of relative relatedness of the public methods to the overall public functionality of a class. The proposed metric for class cohesion uses a new concept of subset tree to determine relative relatedness of the public methods to the overall public functionality of a class. A set of metrics has been proposed for measuring class coupling based on three types of UML relationships, namely association, inheritance and dependency. The reasonable metrics to measure cohesion and coupling are supposed to share the same set of input data. Sharing of input data by the metrics encourages the idea for the existence of mutual relationships between them. Based on potential relationships research questions have been formed. An attempt is made to find answers of these questions with the help of an experiment on OO system FileZilla. Mutual relationships between class cohesion and class coupling have been analyzed statistically while considering OO metrics for size and reuse. Relationships among the pairs of metrics have been discussed and results are drawn in accordance with observed correlation coefficients. A study on Software evolution with the help of class cohesion and class coupling metrics has also been performed and observed trends have been analyzed.

We present simultaneous Hubble Space Telescope (HST) WFC3+Spitzer IRAC variability monitoring for the highly variable young (similar to 20 Myr) planetary-mass object PSO J318.5-22. Our simultaneous HST + Spitzer observations covered approximately two rotation periods with Spitzer and most of a rotation period with the HST. We derive a period of 8.6. +/-. 0.1 hr from the Spitzer light curve. Combining this period with the measuredvsinifor this object, we find an inclination of 56 degrees.2. +/-. 8 degrees.1. We measure peak-to-trough variability amplitudes of 3.4%. +/-. 0.1% for Spitzer Channel 2 and 4.4%-5.8% (typical 68% confidence errors of similar to 0.3%) in the near-IR bands (1.07-1.67 mu m) covered by the WFC3 G141 prism-the mid-IR variability amplitude for PSO J318.5-22 is one of the highest variability amplitudes measured in the mid-IR for any brown dwarf or planetary-mass object. Additionally, we detect phase offsets ranging from 200 degrees to 210 degrees (typical error of similar to 4 degrees) between synthesized near-IR light curves and the Spitzer mid-IR light curve, likely indicating depth-dependent longitudinal atmospheric structure in this atmosphere. The detection of similar variability amplitudes in wide spectral bands relative to absorption features suggests that the driver of the variability may be inhomogeneous clouds (perhaps a patchy haze layer over thick clouds), as opposed to hot spots or compositional inhomogeneities at the top-of-atmosphere level.

Thesis (M.S.)--California Polytechnic State University, 2008.
Major professor: David Janzen, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Computer Science." "June 2008." Includes bibliographical references (leaves 57-62). Also available online. Also available on microfiche (1 sheet).

Three of the most widely studied software dependency types are the structural, logical and semantic dependencies. Logical dependencies capture the degree of co-change between software artifacts. Semantic dependencies capture the degree to which artifacts, comments and names are related. Structural dependencies capture the dependencies in the source code of artifacts. Prior studies show that a combination of dependency analysis (e.g., semantic and logical analysis) improves accuracy when predicting which artifacts are likely to be impacted by ripple effects of software changes (though not to a large extent) compared to individual approaches. In addition, some dependencies could be hidden dependencies when an analysis of one dependency type (e.g., logical) does not reveal artifacts only linked by another dependency type (semantic). While previous studies have focused on combining dependency information with minimal benefits, this Thesis explores the consistency of these measurements, and whether hidden dependencies arise between artifacts, and in any of the axes studied. In this Thesis, 79 Java projects are empirically studied to investigate (i) the direct influence and the degree of overlap between dependency types on three axes (logical - structural (LSt); logical - semantic (LSe); structural - semantic (StSe)) (structural, logical and semantic), and (ii) the presence of hidden coupling on the axes. The results show that a high proportion of hidden dependencies can be detected on the LSt and StSe axes. Notwithstanding, the LSe axis shows a much smaller proportion of hidden dependencies. Practicable refactoring methods to mitigate hidden dependencies are proposed in the Thesis and discussed with examples.

Object-Oriented design and development dominates both commercial and open source software projects. One of the principal goals of object-oriented design is to aid reuse, and hence, reduce future maintenance efforts of software systems. However, the on-going maintenance of large-scale software systems (both changes and faults) continues to be a significant proportion of the lifecycle of the system and the total investment cost. Understanding and thus being able to predict - or even reduce - the impact of the contributing factors of future maintenance efforts of a software system is thus highly beneficial to software practitioners. In this Thesis we empirically study a large, commercial software system with the principal aim to determine the contributing factors to the change and fault propensity over a three-year period. We consider the object-oriented design context of the software, specifically its inheritance characteristics, coupling and cohesion properties, object-oriented design pattern participation, and size. We also explore the effect of refactoring and test classes in the software. Our results show that several aspects of the design context of a class have an impact to the change and fault-proneness of the software. Specifically, we show that classes with high afferent or efferent coupling are more change and fault-prone; we also identify a number of design patterns whose participants tend to have a higher change and fault propensity than non-participants and we identify a range of inheritance characteristics (in terms of depth of inheritance and number of children) that result in an increase to change and fault-proneness. Furthermore we show that refactoring is a commonly occurring maintenance activity, although it is largely limited to simpler types of refactorings. Finally, we provide some insight into the co-evolution of production and test code during refactoring.

Le projet principal de ce travail a porté sur l'étude des fluctuations hors d'équilibres de membranes lipidiques induites par la bactériorhodopsine (BR), une protéine transmembranaire activée par la lumière. Un protocole robuste pour l'incorporation de BR dans les systèmes mimétiques de membrane a été développé et les changements structurels induits par l'incorporation et l'activation de la BR ont été étudiés en détail par réflectivité spéculaire (neutrons et rayons X) et par réflectivité hors-spéculaire (rayons X). Nous avons pu observer un effet réversible induit par l'activité de la protéine sur la structure de la membrane et sur ses fluctuations. Ces résultats ouvrent la voie à l’étude du spectre des fluctuations hors-équilibres d’un système protéo-membranaire planaire, et à l’accès aux propriétés physiques de la membrane active. Dans un second projet nous avons étudié l’interaction entre deux bicouches lipidiques fortement chargées. Nous avons finement caractérisé la structure du système et clairement démontré que des interactions attractives existaient entre les bicouches chargées, en accord avec la théorie de couplage fort
The main project of this work was focused on the investigation of out-of-equilibrium fluctuation of phospholipid membranes induced by light-activated transmembrane protein bacteriorhodopsin (BR). A robust protocol for the BR incorporation into the membrane-mimic systems was developed and the induced structural changes caused by BR incorporation and activation with light were probed by means of neutron and X-ray specular and off-specular reflectometry. The reversible effect of light illumination on the protein activity (on /off) via its effect on the bilayer structure and fluctuation spectrum was demonstrated. These results open the way to investigate the active fluctuation spectrum of a planar membrane-protein system and to access the physical properties of the active membrane. The aim of the second project was to investigate the interaction between highly negatively charged DPPS lipid bilayers. We fully characterized the structure of the system and clearly demonstrated that attractive interactions existed between charged bilayers, in good agreement with Strong-Coupling theory

Actuellement, l’implémentation des services (modèles SOAP et RESTful) et de leurs applications clientes est de plus en plus basée sur la programmation par objet. Ainsi, les cadriciels orientés-objets pour les services Web sont essentiellement composés de deux couches : une couche à objets qui enveloppe une couche à services. Dans ce contexte, deux principes sont nécessaires pour la spécification de ces cadriciels : (i) En premier lieu, un couplage faible entre les deux couches, ce qui permet de cacher la complexité des détails techniques de la couche à services dans la couche à objets et de faire évoluer la couche à services avec un impact minimal sur la couche à objets (ii) En second lieu, une interopérabilité induite par le principe de substitution associée au sous-typage dans la couche à objets. Dans cette thèse, nous présentons d’abord les faiblesses existantes dans les cadriciels orientés-objets liés à ces deux principes. Ensuite, nous proposons une nouvelle spécification pour ces cadriciels en vue de résoudre ces problèmes. Comme application, nous décrivons la mise en œuvre de notre spécification dans le cadriciel cxf, à la fois pour SOAP et RESTful
Today, the implementation of services (SOAP and RESTful models) and of client applications is increasingly based on object-oriented programming languages. Thus, object-oriented frameworks for Web services are essentially composed with two levels: an object level built over a service level. In this context, two properties could be particularly required in the specification of these frameworks: (i)First a loose coupling between the two levels, which allows the complex technical details of the service level to be hidden at the object level and the service level to be evolved with a minimal impact on the object level, (ii) Second, an interoperability induced by the substitution principle associated to subtyping in the object level, which allows to freely convert a value of a subtype into a supertype. In this thesis, first we present the existing weaknesses of object-oriented frameworks related to these two requirements. Then, we propose a new specification for object-oriented Web service frameworks in order to resolve these problems. As an application, we provide an implementation of our specification in the cxf framework, for both SOAP and RESTful models

Nesta dissertação é apresentado o estudo dos transistores de porta flutuante (Floating Gate Transistor - FG Transistor), sua modelagem, e a análise do efeito da dose de ionização total (Total Ionizing Dose- TID) sobre os transistores FG. Para isto foi procurado e implementado um modelo de simulação elétrica do transistor FG em condições de leitura (análise DC), baseado no cálculo quantitativo da tensão na porta flutuante em função das tensões nos terminais do transistor, no valor de carga armazenado na porta flutuante e nos coeficientes de acoplamento capacitivo que apresentam este tipo de dispositivos. Para a análise do efeito TID, a tensão limiar do transistor MOS foi variada usando o método de simulação Monte Carlo, tendo em conta as variações da tensão limiar que apresentam os transistores FG submetidos na radiação ionizante. O estudo obteve como resultado a confirmação da perda de carga do FG à medida que é incrementada a dose de radiação, o que implica uma alteração na característica de retenção de carga que caracteriza as células de memórias não voláteis (Non Volatile Memory - NVM).
In this dissertation work, a study of the the floating gate Transistor (FG transistor) performed. The focus in the electrical modeling, and the analysis of the impact of the Total Ionizing Dose (TID) on the electrical performance of the device. Aiming electrical level simulation, different electric simulation models for the FG transistor in read conditions (DC analysis) were evaluated and the model best suited for implementation into the simulation tool was selected. The selected model is based on Floating Gate voltage calculation as a function of polarization voltage of the FG transistor terminals, the stored charge value in the Floating Gate and the capacitive coupling coefficient presented by this device. For the TID analysis the threshold voltage of the MOS transistor was shifted by means of a Monte Carlo simulation method, considering the threshold voltage variations when the FG transistor is subjected to the ionizing radiation.The analysis lead to the confirmation that the loss charge stored in the FG increases with the radiation dose, affecting the retention characteristics of the memory cells.

La simulation numérique des éoliennes flottantes est essentielle pour le développement des Energies Marines Renouvelables. Les outils de simulation classiquement utilisés supposent un écoulement stationnaire sur les rotors. Ces théories sont généralement assez précises pour calculer les forces aérodynamiques et dimensionner les éoliennes fixes (à terre ou en mer) mais les mouvements de la plateforme d’une éolienne flottante peuvent induire des effets instationnaires conséquents. Ceux-ci peuvent par exemple impacter la force de poussée sur le rotor. Cette thèse de doctorat cherche à comprendre et à quantifier les effets de l’aérodynamique instationnaire sur la tenue à la mer des éoliennes flottantes, dans différentes conditions de fonctionnement. L’étude montre que les forces aérodynamiques instationnaires impactent les mouvements de la plateforme lorsque le rotor est fortement chargé. Les modèles quasi-stationnaires arrivent néanmoins à capturer la dynamique des éoliennes flottantes avec une précision suffisante pour des phases de design amont. Les éoliennes flottantes à axe vertical sont elles aussi étudiées pour des projets offshore puisqu’elles pourraient nécessiter des coûts d’infrastructure réduits. Après avoir étudié l’influence de l’aérodynamique instationnaire sur la tenue à la mer de ces éoliennes, une comparaison est menée entre éoliennes flottantes à axe horizontal et à axe vertical. Cette dernière subit une importante poussée aérodynamique par vents forts, induisant de très grands déplacements et chargements
Accurate numerical simulation of thesea keeping of Floating Wind turbines (FWTs) is essential for the development of Marine Renewable Energy. State-of-the-art simulation tools assume a steady flow on the rotor. The accuracy of such models has been proven for bottom-fixed turbines, but has not been demonstrated yet for FWTs with substantial platform motions. This PhD thesis focuses on the impact of unsteady aerodynamics on the seakeeping of FWTs. This study is done by comparing quasi-steady to fully unsteady models with a coupled hydro-aerodynamic simulation tool. It shows that unsteady load shave a substantial effect on the platform motion when the rotor is highly loaded. The choice of a numerical model for example induces differences in tower base bending moments. The study also shows that state of the art quasi-steady aerodynamic models can show rather good accuracy when studying the global motion of the FWTs. Vertical Axis Wind Turbines (VAWTs) could lower infrastructure costs and are hence studied today for offshore wind projects. Unsteady aerodynamics for floating VAWT sand its effects on the sea keeping modelling have been studied during the PhD thesis,leading to similar conclusions than for traditional floating Horizontal Axis Wind Turbines (HAWTs). Those turbines have been compared to HAWTs. The study concludes that, without blade pitch control strategy, VAWTs suffer from very high wind thrust at over-rated wind speeds, leading to excessive displacements and loads. More developments are hence needed to improve the performance of such floating systems

Les travaux décrits dans ce document abordent le problème du couplage dynamique homme-système haptique. Nous proposons une étude de ce couplage basée sur l'hypothèse d'un système hybride temporaire. Selon cette hypothèse, le système formé lors du couplage peut être considéré comme un système dynamique dont les deux parties ne peuvent pas être séparées. Ce sujet est pluridisciplinaire, se situant à l'intersection des sciences cognitives, de l'automatique et de l'haptique. La première partie du document comporte un état de l'art sur l'analyse du couplage dans ces trois domaines, une description de la problématique et de la méthode à utiliser pour notre étude ainsi qu'une proposition des typologies du geste. Lors de cette étude du couplage, nous nous intéressons à un groupe de gestes particuliers, notamment le geste périodique et le geste passif dans une situation de simulation haptique ainsi qu'aux modèles d'interaction capables de les générer. La méthode générale, consiste à définir des approches pour la modélisation du couplage main-système haptique pour ensuite réaliser une analyse du système couplé à partir d'une acquisition des données du système lors du couplage et en utilisant des méthodes d'identification de paramètres issus de l'automatique pour caractériser les modèles. La dernière partie, décrit la mise en place du dispositif pour l'analyse expérimentale du couplage en situation de simulation avec une interaction haptique. Ce dispositif permet l'acquisition des données du geste pour l'analyse. Nous présentons également, l'étude réalisée sur le simulateur haptique afin d'établir l'équivalence entre les paramètres virtuels introduits et issus du simulateur et des paramètres physiques réels. Ensuite, nous décrivons l'analyse expérimentale des différentes situations de couplage proposées. Les expériences effectuées lors de cette étude ont été réalisées sur la plateforme temps réel ERGON_X, conçue par l'ACROE/ICA. Les résultats de ces expériences ont permis de quantifier les modèles du geste et d'observer ses composantes, selon les modèles établis. Mots clés : haptique, interface haptique, interfaces homme-machine, simulation temps réel, couplage homme-objet, geste, modélisation physique, identification de paramètres
The work described in this document deals with the problem of human-haptic system dynamic coupling. We propose a study of this kind of coupling based on the hypothesis of a temporary hybrid system. Under this hypothesis, the system formed during the coupling can be considered as a dynamic system in which the two parties that compose it cannot be separated. This is multidisciplinary topic, situated at the intersection of cognitive science, automation and haptics. The first part of the document includes a state of the art on the analysis of coupling in these three areas, the description of the problem and the methodology for the study as well as a proposal of gesture typology. In this study of coupling, we are interested in a particular group of actions, such as periodic movement and passive gesture in a situation of haptic simulation and also, in the interaction models able to generate them. The general method is to define the approaches for modeling the hand-haptic device coupling and then perform an analysis of the coupled system by acquiring system data during the coupling and using parameter identification methods to characterize the models. The final section describes the implementation of the device for the experimental analysis of coupling during simulation with a haptic interaction. This device allows data acquisition for gesture analysis. We also present the study of the haptic simulator to establish the equivalence between virtual parameters introduced to and returned by the simulator and real physical parameters. Then, we describe the experimental analysis of different proposed coupling situations. The experiments performed for this study were performed using the real-time platform ERGON_X, designed by ACROE / ICA. The results of these experiments were used to quantify gesture models and to observe its components, according to established models. Keywords: haptic, haptic interface, human-machine interfaces, real-time simulation, human-object coupling, gesture, physical modeling, parameter identification

This dissertation defines "modular-objective coupling", and shows that programming language designs which imply reduced modular-objective coupling reduce complexity of remodularizations--behaviour-preserving restructurings for which the only intended goals are to change program source code structure. We explicitly distinguish between two points of view on program structure: modular structure--the structure of a program as a set of static text documents, and objective structure--the structure of a program as a dynamic computational model during execution. We define modular-objective coupling as the degree to which changes in modular structure imply changes to objective structure, for a given programming language. We use the term remodularization to refer to any behaviour-preserving source code restructuring, for which the only intended goal is to change modular structure. We argue that programming languages with strong modular-objective coupling introduce accidental complexity into remodularizations, by requiring complex objective structure changes to achieve intended modular structure changes. Our claim is that a programming language design which implies reduced modular-objective coupling reduces remodularization complexity in the language. To validate this claim, we first present SubjectJ, a subject-oriented programming system that extends Java. The design of Java implies strong modular-objective coupling, while SubjectJ is designed for reduced modular-objective coupling. We then perform a series of remodularization case studies comparing Java and SubjectJ. Our results suggest that remodularizations are less complex in SubjectJ.

This thesis deals with the design and realization of wireless power charging circuit for embedded systems. The research section focuses on the various ways and technologies used in applications of wireless power transfer. The theoretical part also briefly characterizes resonant inductive coupling and critical parameters of the transfer. This is followed by realization of various variants of transfer coils and electromagnetic oscillators. Wireless power charging prototype system is created and used for testing purposes to find optimal configuration of resonator. The hardware unit presented in the final part of the thesis exploits microcontroller and implemented software is extended by foreign object detection algorithm along with method to monitor battery charging state.

Human sensorimotor control is remarkably adept at utilising contextual information to learn and recall systematic sensorimotor transformations. Here, we investigate the motor representations that underlie such learning, and examine how motor memories acquired based on different contextual information interact. Using a novel three-dimensional robotic manipulandum, the 3BOT, we examined the spatial transfer of learning across various movement directions in a 3D environment, while human subjects performed reaching movements under velocity-dependent force field. The obtained pattern of generalisation suggested that the representation of dynamic learning was most likely defined in a target-based, rather than an extrinsic, coordinate system. We further examined how motor memories interact when subjects adapt to force fields applied in orthogonal dimensions. We found that, unlike opposing fields, learning two spatially orthogonal force fields led to the formation of separate motor memories, which neither interfered with nor facilitated each other. Moreover, we demonstrated a novel, more general aspect of the spontaneous recovery phenomenon using a two-dimensional force field task: when subjects learned two orthogonal force fields consecutively, in the following phase of clamped error feedback, the expression of adaptation spontaneously rotated from the direction of the second force field, towards the direction of the first force field. Finally, we examined the interaction of sensorimotor memories formed based on separate contextual information. Subjects performed reciprocating reaching and object manipulation tasks under two alternating contexts (movement directions), while we manipulated the dynamics of the task in each context separately. The results suggested that separate motor memories were formed for the dynamics of the task in different contexts, and that these motor memories interacted by sharing error signals to enhance learning. Importantly, the extent of interaction was not fixed between the context-dependent motor memories, but adaptively changed according to the task dynamics to potentially improve overall performance. Together, our experimental and theoretical results add to the understanding of mechanisms that underlie sensorimotor learning, and the way these mechanisms interact under various tasks and different dynamics.

This project examines how the quality of a code generator used in an Object-Relational Mapping (ORM) framework can be improved in terms of maintainability, testability and reusability by changing the design from a top-down perspective to a bottom up. The resulting generator is tested in a case study to verify that the new design is more cohesive and less coupled than an existing code generator.

Les notations semi-formelles et formelles semblant complémentaires, leur couplage semble un cadre intéressant pour pouvoir bénéficier de leurs avantages respectifs tout en diminuant leurs points faibles. En effet, d'une part, les notations semi-formelles qui pêchent par leur précision sont de bons vecteurs de communication dont le coût de formation est raisonnable ; d'autre part, les langages formels apportent la précision et le potentiel de raisonnement manquant aux notations semi-formelles. Dans ce travail, nous proposons une approche de traduction de modèles semi-formels objet en des spécifications formelles en Z ou en Object-Z afin de fournir un couplage bénéfique de ces deux types de spécifications. Nous cherchons à rendre nos propositions les plus utilisables possible en en montrant trois bénéfices avérés : un guide méthodologique pour l'expression des contraintes annotant un modèle objet, une aide à la vérification des modèles et de leurs contraintes et des raisonnements informels sur la sémantique de modèles simples. Nous avons aussi développé un outil de support à notre approche, RoZ qui permet de faire cohabiter les notations semi-formelles et formelles. Enfin nous étudions une autre approche de couplage, la vérification de cohérence par méta-modélisation pour laquelle nous proposons des règles de cohérence entre le modèle objet et Z. Ce travail nous permet de comparer cette approche avec notre stratégie de traduction afin de mieux comprendre leurs avantages et leurs inconvénients
Semi-formal and formal notations being complementary, their joint use could define an interesting framework in order to take advantage of their good points by reducing their drawbacks. On the one hand, semi-formal notations which are imprecise are good communication vectors with affordable training cost ; on the other hand, formal languages bring precision and their reasoning abilities which miss to semi-formal notations. In this work, we propose a translation approach from semi-formal object models to formal specifications in Z and Object-Z so as to offer a powerful integration of these two kinds of specifications. We want to make our proposals the most useful possible by showing three established advantages : a methodological guidance to express constraints annotating an object model ; an help to check the models and their constraints and informal reasoning about the semantics of simple models. We also have developed a tool, RoZ that supports our approach by making semi-formal and formal notations live together. Finally, we study another integration approach, the consistency checking by meta-modelling for which we propose consistency rules between the object model and Z. This work enables us to compare this approach with our translation strategy to understand their advantages and drawbacks

Ce travail de thèse, propose un schéma numérique d'ordre élevé, distribuantle résidu (RD) pour l'approximation d'un problème hydro-sédimentairehyperbolique non conservatif, couplant les modèles de Grass et de Saint-Venant. Il fait appel à des méthodes de Runge-Kutta à variation totale diminuanteet de stabilisation (méthode de décentrement amont, dit Upwind),avec ou sans adjonction de limiteurs et présente de bonnes propriétés.L'une des facettes importantes de ce qui a été réalisée, repose sur la conceptionet le développement d'un programme Python 2D-espace, sous la formed'un logiciel faisant appel à un ensemble de modules créés pour l'occasion.Le développement du code de calcul, qui se propose d'approcher la solutiondu problème hydro-sédimentaire, a été e_ectué avec une orientation Objetet pour être e_cace sur calculateur parallèle (utilisant le parallélisme multithreadsOpenMP). L'une des particularités du schéma numérique dans cecadre, est liée à son application à des quadrangles.Un programme 1D-espace, qui se présente également sous forme de logiciel,a aussi été mis en place. Pour des raisons de portabilité et d'e_catité, il aété écrit multilangages (Python-Fortran : via numpy.ctypes pour Python etvia l'interface standard de Fortran pour C). Le schéma RD avec ou sansadjonction de limiteurs de _ux, a été implémenté à la manière d'un schémaprédicteur-correcteur. Des comparaisons avec d'autres schémas ont été e_ectuées a_n de montrer son e_cacité, son ordre de précision élevé a été mis enévidence, et la C-propriété a été testée. Les tests ont révélé que, pour le casd'un transport d'un pro_l sédimentaire parabolique, c'est le limiteur de _uxMUSCL MinMod, qui est le plus adapté parmi ceux testés.Dans le cas scalaire, des tests numériques ont été réalisés a_n de validerle second ordre de précision
The present work, proposes a high order Residual Distribution (RD) numericalscheme to solve the non conservative hyperbolic problem, coupling Shallow Water and Grass equations. It uses Total Value Diminishing Runge Kutta and stabilisation Upwind methods, with or without limiters. It also has some good properties.A part of the work realised in this thesis, is about the conception and the developpement of a 2D-space Python program, under the form of a software,using a set of moduls created for the occasion. the code developpement, whichis said to approach the _uid-sediment model, coupling Shallow-Water and sedimentequations, has been made with an Object orientation and in orderto be e_cient on parallel architecture (using multithreads OpenMP parallelism). One of the features of the scheme in this case, is due to its application on quadrangles.A 1D-space program, also writen as a software, has been estabished. In order to be portable and e_cient, It has been developped multilinguals (Python- Fortran : by numpy.ctypes for Python and by standart interface FORTRAN for C). The RD scheme with or without Flux Limiters, has been implemented like predictor-corrector one. Comparisons with other schemes results have been realised, in order to show its e_ciency, moreover its high order accuracy has been focus on, and the C-proprerty has been tested. The tests show that MUSCL MinMod _ux limiters, is the most adaptated for a dune test case, between all tested.In the scalar case, numerical tests have been realised, for validating the secondorder of accuracy

Master’s thesis is focused on making the acquaintance of EMC issues and ways of electromagnetic field scanner RS321 utilization for pre-compliance measurements. First part contains analysis of available equipment’s influence on measurement results on the basis of gathered specification. Next part includes an example measurement used as operational manual for scanner and its controlling program. The most important part is correction evaluation for performed EMI measurement of signal generator using its EMC certification protocol and application of gained correction curve on independent EMI measurement of device tested by EMC testing laboratory. Other possibilities of scanner utilization are mentioned in the next chapters. Last part of the thesis contains suitability evaluation of EMC scanner on the basis of findings from performed measurements.

碩士
崑山科技大學
資訊管理研究所
106
The two most commonly used metrics in systems developed using object-oriented techniques are coupling and cohesion. Coupling degree refers to the degree of interdependence between software components in the system, and cohesion refers to the degree of correlation between methods and attributes in software components. A system with good software quality must have a good design, and many literatures also point out that a good object-oriented design system should have low coupling and high cohesion. The main contribution of this research is to provide an improved version of the coupling metric calculation proposed by past scholars. For this study, the new version of the measurement method not only corrects the missing information in the past, but also provides a more robust software-coupled metrology gauge, which can be used to measure the coupling of a system and its subsystems. Can be used as an effective measure of software quality testing.

Nonlinear coupling problems between the multiple bodies or between the mooring/riser and the offshore platform are incorporated in the CHARM3D-MultiBody, a fully coupled time domain analysis program for multiple bodies with moorings and risers. The nonlinear spring connection module and the three dimensional beam module are added to appropriately solve the structural connection problem. The nonlinear spring connection module includes the hydro-pneumatic tensioner module with the friction & stick/slip implementation, the tendon/mooring disconnection (breakage/unlatch) module with the tendon down-stroke check, and the contact spring with the initial gap with the friction force implemented. The nonlinear coupling may happen in many places for the offshore floating structures, such as hydro-pneumatic tensioner, tendon of TLP down stroke at the bottom joint, stick-slip phenomena at the tie down of the derrick and most of the fender-to-steel or steel-to-steel contact problem with initial gap during the installation. The mooring/tendon broken and unlatch can be a nonlinear connection problem once the transient mode is taken into account. Nonlinearity of the stiffness and friction characteristics of the tensioner combined with stick-slip behavior of riser keel joint is investigated. The relationship between tensions and strokes for hydro-pneumatic tensioner is based on the ideal gas equation where the isotropic gas constant can be varied to achieve an optimum stroke design based on tensioner stiffness. A transient effect of tendon down-stroke and disconnection on global performance of ETLP for harsh environmental condition is also investigated by incorporating the nonlinear boundary condition of the FE tendon model in CHARM3D. The program is made to be capable of modeling the tendon disconnection both at the top and the bottom connection as well as the down stroke behavior for the pinned bottom joint. The performance of the tie-down clamp of derrick is also investigated by using six degrees of freedom spring model and the three(3) dimensional FE beam model. The coupling of the TLP motion with the reaction force at the tie-down clamp is considered by using exact nonlinear dynamic equations of the motion with the reaction forces modeled with the spring or FE beam model. The method reduces too much conservatism when we design the tie-down system by the conventional method, in which all the environmental forces are combined without the phase lag effect between them. The FE beam model is also applied to the connectors between the semisubmersible and the truss for the pre-service and in-place conditions to be verified with the model test results, which shows good agreements.

碩士
國立交通大學
資訊工程學系
84
The coupling and cohesion metrics played an important role in structured software. Information flow is a major source of coupling or cohesion, while message passings define the information flow in an object-oriented program.In the thesis, we present a set of methods to measure the coupling and cohesionof an object-oriented program based on information flow. An evaluation according to Weyuker's properties is made for the metrics. Besides, following the frameworkproposed by Basili et al. and the validation methodology proposed by Schneidewind,we constructed an experiment to validate our metrics and several coupling metricspreviously proposed in the literature. The quality factors selected in the experiment are mainly concerned with the modification of a class. Four validitycriteria that provide statistical models are used to analyze the data. The experimental results show that our proposed coupling and inheritance coupling metrics are better than the rest. In our five coupling and cohesion metrics forclasses and class hierarchies, three metrics ICH(C), ICP(C) and IH_ICP(C) satisfyall the validity criteria; that is, they provide the quality assessment functions, quality control functions and quality prediction functions.Keywords: coupling and cohesion metrics, the validation methodology, validity criteria, quality assessment functions, quality control functions, quality prediction functions.

碩士
國立臺灣大學
工程科學及海洋工程學研究所
101
This research investigated numerical study of spar type and semi-submersible type floating wind turbine doing motion under the coupling of aerodynamic and hydrodynamic loads. We use computational fluid dynamics package and solve the flow field by using Reynolds-averaged Navier-Stokes equations (RANS) solver with a proper turbulent model and also use the java code to compute the mooring line force. NREL 5MW is choosed as our wind turbine. For the onshore simulation case, the result is verified with the NREL simulation results, the errors are less than 8%. And the offshore simulation case is the wind turbine doing pitch motion or doing surge, heave and pitch motion simultaneously in the wave height 4 m, wave period 10 s regular head wave with uniform wind speed 11.4 m/s. The simulation result shows that the rotor power changes dramatically because of the wind turbine’s pitch motion. And if we consider the real wind turbine control system situation, the average power will be reduced. In the case of the spar type floating wind turbine doing doing surge, heave and pitch motion simultaneously, the result shows that the spar type floating wind turbine has the pitch angle range from -3.59 to -6.03 degrees, and the rotor power change is up to +32 % to -36 %, and the average power is reduced by 1.39%, and if we consider the real wind turbine control system situation, the average power is reduced by 9.17 %. In the case of the semi-submersible type floating wind turbine doing doing surge, heave and pitch motion simultaneously, the result shows that the spar type floating wind turbine has the pitch angle range from -3.50 to -5.04 degrees, and the rotor power change is up to +6 % to -10 %, and the average power is reduced by 0.99%, and if we consider the real wind turbine control system situation, the average power is reduced by 2.61 %. According to this research, we recommend the semi-submersible floating platform in order to reduce the floating wind turbine’s power loss.

碩士
中原大學
工業工程研究所
93
Abstract Companies in the supply chain system are facing constant change and environmental uncertainty. Companies need to work on the tight interaction and co-ordination among all the partners in the supply chain system. Supply chain management requires coordination of every facility and keeps flexibility of the system to improve the customer service level simultaneously. Maintainability of information systems for the supply chain system to meet the company requirements becomes an issue as the business environment changes constantly and rapidly. The information system needs to response swiftly and correctly; therefore a system with good maintainability can fulfill this demand. As object oriented analysis and design methods are widely applied, the assessment on the quality of object-oriented designs are more important. To evaluate the quality of object-oriented design, appropriate metrics and evaluation techniques are crucial to the quality measurement. To save the costs and efforts in writing computer codes, assessing the software quality at the early stage of the development cycle is beneficial to the companies. This research proposes a methodology to evaluate designs of object-oriented information system with coupling metrics, and the measurements can be used as guidelines for modification of the object oriented designs. The method can be applied at the design stage of the system development cycle to measure the maintainability. There are two parts of the coupling measurement: the static evaluation of the class diagram and the dynamic evaluation of the sequence diagram. After the static metrics are calculated from the class diagram, the designers may consider the modification of the class diagram based on the metric values. The dynamic metrics from the sequence diagram can predict the coupling of objects in the real system. Based on the RosetttaNet standard, two different object-oriented designs for the same ordering system were generated. After both class diagrams and sequence diagrams were evaluated with dynamic and static metrics, two real Java codes of both designs were also generated for a maintainace experiment. The experiment result shows the design with lower couplings in the class diagram and sequence diagram has better maintaince outcome with less code modifications.

The U-curves of five different test objects, three of which contain a rod floating object at different positions within the gap, are characterised. During the testing, a high speed camera was used to photograph the discharges. The results are compared to Rizk’s theoretical model for determining the flashover voltage of gaps with floating objects are presented. It is concluded that the position of the floating object within the gap affects which discharge mechanism exists in each of the gaps. The effect that each discharge mechanism has on the flashover voltage and time to crest of the gap is shown. Time interval photographs are presented showing the formation of a discharge channel due to the streamer mechanism. In evaluating the high speed photographs it is seen that the extent of the branching of the discharge channel is a function of the time to crest of the applied impulse, more branching is evident for shorter times to crest.

碩士
國立清華大學
電子工程研究所
102
Over the past few decades, the importance of sustainable development had been rooted in people’s mind deeply. Therefore, the energy harvesting and power IC technology becomes the key issues. How to get a good balance between the breakdown voltage and the on-resistance is critical in designing power devices. Typical power devices are fabricated by special process that need the extra wire bonding to connect the system circuit and the power device. So the high cost is a major problem of this. The general MOSFET’s breakdown voltage is affected by surface peak electric field. It causes the MOSFET’s gate dielectric reliability getting worse. In the previous work, a Floating Field Plate MOSFET (FFP-MOSFET) was fabricated by 28nm CMOS process. With floating gate as its field plate, its depletion region will be extended, reduces the drain-side peak electric-field. However, FFPMOS suffers from large on-resistance. This work presents a GGCFFPMOS which introduce external capacitors between the floating gates. Measurement results show that gated-breakdown voltage is successfully extended. Furthermore, the trade-off between the breakdown voltage and the on-resistance improves. Without special process defined drift region or extra masks, this device is formed by pure logic process and allow for high flexibility.

碩士
國立清華大學
電子工程研究所
103
Semiconductor manufacturing technology has followed the prediction of Moore’s Law in past decades, and the size of transistors scaled down continually. To overcome the issue of leakage current and the on current level, researchers come up with new structures and process method. In the CMOS logic process under 20nm, we change to 3D structure which has gate covering the fin. We can make the depletion region fully surround the substrate in FinFET structure, and this design leads to low leakage current and excellent gate control. It is advantage to scale down the device. When the thickness of gate dielectric scales down, the method to detect the antenna effect needs to be changed. We can connect the gate to metal layer which has big area, and observe the subthreshold swing, threshold voltage, transconductance and TDDB results of the transistor. And we can use these parameters to detect the influences of antenna effect. Also, we can use some measurement skills to detect the plasma induced damage. For example, C-V measurement, gate leakage current measurement. But as the dielectric thickness scales down, the FN leakage current will go through the dielectric directly, and the damage will not show in the parameters of transistor, and we will underestimate the damage due to antenna effect. So we need another methods or devices to trace the plasma induced damage. In this paper, we propose a structure using contact coupling floating gate, and we use it to pass the high voltage to floating gate to attract the charges from substrate in the plasma process. We can store the charges in the floating gate and quantitatively and qualitatively analyze the damage due to plasma charging. This device can be used as the test pattern on the wafer in the processes. We can put it on the different locations and connect it to different metal layers. Researchers can detect the damage on time and focus on the issue by simple measurement. It will help a lot in the process of wafer.

The hand is a marvellous organ. With our hands, we explore the world by contacting and manipulating the objects that we are interested in. The hand also presents one of the most complex structures in the body for its numerous degrees of freedom at the level of the joints and muscles. Because of these characteristics and for its peculiar shape, “the hand in action” is capable of complex skills. Due to the complexity of “the hand in action”, previous studies at first focused on classifying different hand postures and configurations based on anatomical and functional categorizations, considering the thumb, the fingers and the palm shaping in a huge range of motor tasks. Within a specific set of hand movements, multiple components were taken into account: the type of grip, the activation of muscle synergies, and in combination with object properties. An additional way to consider hand complexity was to count the number of muscles involved, the forces and the momentums produced, along with the neuromuscular connections. Indeed the act of prehension has been defined as "the application of functionally effective forces by the hand to an object for a task, given numerous biomechanical constraints". Aside from the behavioural and biomechanical studies, neuroscientists looked into the neurophysiology of the hand in action from a top-down perspective by focusing their attention on the brain-hand connection in order to investigate how such a complex apparatus is controlled. The main question then was: “How does the brain control the hands?” Actions have been shown to be represented in the brain during action execution, observation, and even during motor imagery. A neural model of the representation of movements was proposed to understand how action pre-planning can be transformed into a sequence of actual movements and where action representations are generated in the neural structures. Other lines of research have been followed to attempt to discover links between brain activity during mental imagery. Indeed, mental imagery, or motor imagery, is a pure mental state of an action, and can be considered as the ability to generate a conscious simulation of self-acting. Studying brain activity while a person is imagining performing an action, provides the opportunity to investigate how our motor system deals with planning in the absence of an actual action. These types of studies became available at the end of the past century when the development of new technology (e.g., fMRI and TMS) gradually overcame the difficulty of testing brain activity non-invasively. Since that time, studies significantly increased our understanding about the link between hand movements and relative brain activity. However, laboratory's studies limit the natural motor coordination as the one performed by people in everyday life. Grasping indeed is a complex action and its complexity is particularly expressed when the action is performed without constraints. This concept was well expressed by Newell and his model provides a valid perspective by suggesting that complex forms of motor behaviour could be viewed as products of self-organization arising from interactions between task, environment and organism constraints. Napier (1956) already recommended the necessity to incorporate as much complexity as possible in hand action when research is carried out. The core idea of the present study is to investigate the neural correlates of the hand in action during motor imagery. To address this issue, we will first deal with the studies that considered the hand’s shape in relation to its functions. Then we will tackle the problem from a neuronal level of analysis with particular attention to the studies that considered action imagination. Following this literature review, we will then point out some still-open questions and then state our research hypothesis. Two separate experiments will be described: “Grip-dependent cortico-spinal excitability during grasping imagination and execution” (Experiment 1), and “Motor system resonance for movement direction and amplitude during imagery and motor performance” (Experiment 2). Experiment 1 Studies converge in indicating a substantial similarity of the rules and mechanisms underlying execution, observation and imagery of actions, along with a large overlapping of their neural substrates. Recent transcranial magnetic stimulation (TMS) studies have demonstrated a muscle-specific facilitation of the observer’s motor system for force requirement and type of grip during grasping observation. However, whether similar fine-tuned muscle-specificity occurs even during imagination, when subjects are free to select the most convenient grip configuration, is still unknown. Here we applied TMS over the primary motor cortex and measured the corticospinal excitability (MEP) in three muscles (FDI, ADM and FDS) while subjects imagined grasping spheres of different dimensions and materials. This range of object weights and sizes allowed subjects to freely imagine the most suitable grip configuration among several possibilities. Activation measured during grasping imagination has been also compared to that obtained during real execution (EMG recorded from the same muscles). We found that during imagination of grasping small objects, the FDI muscle was more active than the ADM and the FDS, whereas the opposite pattern was found for big objects. Imagination of medium size objects, instead, required an equal involvement of the three muscles. The same pattern was observed when subjects were asked to perform the action. This suggests that during imagination, the cortico-spinal system is modulated in a muscle-specific/grip-specific way, as if the action would be really performed. However, when force was required (i.e. for the aluminum objects), the motor activation obtained during action execution was more fine-tuned to object dimensions than the activation recorded during imagination, suggesting a separate processing and control of force production. These findings underline a dissociation in grasp kinematics versus grasp kinetics depending on object properties. Experiment 2 Transcranial Magnetic Stimulation studies have shown that the motor system is facilitated by the sole imagination of motor actions. However, it is not clear whether the individual’s motor system resonates bilaterally and selectively for task parameters as movement direction and amplitude. To investigate this issue we apply a single pulse Transcranial Magnetic Stimulation (TMS) over the left and right primary motor cortex (M1) of healthy subjects that had to imagine to grasp and to rotate a clock hour hand, having a starting position at noon, toward four different hours: 2, 5, 7 and 10. Rotations toward 7 and 10 hours were in counter-clockwise direction, but required small movement amplitudes at 10 and large at 7 hour. Conversely, rotations toward 2 and 5 hours followed a clockwise direction and required small movement amplitude at 2 and a large at 5 hour. TMS motor evoked potentials were recorded from three hand muscles and movement imagined with the right and the left hand. Results showed that during motor imagery, the motor system activates the hand-intrinsic muscles specifically for movement direction by showing a mirroring pattern between the right and the left side of the motor cortex. Interestingly none muscle modulation, nor for hand-intrinsic or extrinsic, was observed for movement amplitude suggesting either that amplitude is modulated during the ongoing of the action or that selective inhibition is present in decreasing the otherwise elevated muscle activity evoked. We suggest that the plausibility of a movement is computed in regions upstream the primary motor cortex, and that motor imagery is a higher-order process not fully constrained by the rules that govern motor execution.
The hand is a marvellous organ. With our hands, we explore the world by contacting and manipulating the objects that we are interested in. The hand also presents one of the most complex structures in the body for its numerous degrees of freedom at the level of the joints and muscles. Because of these characteristics and for its peculiar shape, “the hand in action” is capable of complex skills. Due to the complexity of “the hand in action”, previous studies at first focused on classifying different hand postures and configurations based on anatomical and functional categorizations, considering the thumb, the fingers and the palm shaping in a huge range of motor tasks. Within a specific set of hand movements, multiple components were taken into account: the type of grip, the activation of muscle synergies, and in combination with object properties. An additional way to consider hand complexity was to count the number of muscles involved, the forces and the momentums produced, along with the neuromuscular connections. Indeed the act of prehension has been defined as "the application of functionally effective forces by the hand to an object for a task, given numerous biomechanical constraints". Aside from the behavioural and biomechanical studies, neuroscientists looked into the neurophysiology of the hand in action from a top-down perspective by focusing their attention on the brain-hand connection in order to investigate how such a complex apparatus is controlled. The main question then was: “How does the brain control the hands?” Actions have been shown to be represented in the brain during action execution, observation, and even during motor imagery. A neural model of the representation of movements was proposed to understand how action pre-planning can be transformed into a sequence of actual movements and where action representations are generated in the neural structures. Other lines of research have been followed to attempt to discover links between brain activity during mental imagery. Indeed, mental imagery, or motor imagery, is a pure mental state of an action, and can be considered as the ability to generate a conscious simulation of self-acting. Studying brain activity while a person is imagining performing an action, provides the opportunity to investigate how our motor system deals with planning in the absence of an actual action. These types of studies became available at the end of the past century when the development of new technology (e.g., fMRI and TMS) gradually overcame the difficulty of testing brain activity non-invasively. Since that time, studies significantly increased our understanding about the link between hand movements and relative brain activity. However, laboratory's studies limit the natural motor coordination as the one performed by people in everyday life. Grasping indeed is a complex action and its complexity is particularly expressed when the action is performed without constraints. This concept was well expressed by Newell and his model provides a valid perspective by suggesting that complex forms of motor behaviour could be viewed as products of self-organization arising from interactions between task, environment and organism constraints. Napier (1956) already recommended the necessity to incorporate as much complexity as possible in hand action when research is carried out. The core idea of the present study is to investigate the neural correlates of the hand in action during motor imagery. To address this issue, we will first deal with the studies that considered the hand’s shape in relation to its functions. Then we will tackle the problem from a neuronal level of analysis with particular attention to the studies that considered action imagination. Following this literature review, we will then point out some still-open questions and then state our research hypothesis. Two separate experiments will be described: “Grip-dependent cortico-spinal excitability during grasping imagination and execution” (Experiment 1), and “Motor system resonance for movement direction and amplitude during imagery and motor performance” (Experiment 2). Experiment 1 Studies converge in indicating a substantial similarity of the rules and mechanisms underlying execution, observation and imagery of actions, along with a large overlapping of their neural substrates. Recent transcranial magnetic stimulation (TMS) studies have demonstrated a muscle-specific facilitation of the observer’s motor system for force requirement and type of grip during grasping observation. However, whether similar fine-tuned muscle-specificity occurs even during imagination, when subjects are free to select the most convenient grip configuration, is still unknown. Here we applied TMS over the primary motor cortex and measured the corticospinal excitability (MEP) in three muscles (FDI, ADM and FDS) while subjects imagined grasping spheres of different dimensions and materials. This range of object weights and sizes allowed subjects to freely imagine the most suitable grip configuration among several possibilities. Activation measured during grasping imagination has been also compared to that obtained during real execution (EMG recorded from the same muscles). We found that during imagination of grasping small objects, the FDI muscle was more active than the ADM and the FDS, whereas the opposite pattern was found for big objects. Imagination of medium size objects, instead, required an equal involvement of the three muscles. The same pattern was observed when subjects were asked to perform the action. This suggests that during imagination, the cortico-spinal system is modulated in a muscle-specific/grip-specific way, as if the action would be really performed. However, when force was required (i.e. for the aluminum objects), the motor activation obtained during action execution was more fine-tuned to object dimensions than the activation recorded during imagination, suggesting a separate processing and control of force production. These findings underline a dissociation in grasp kinematics versus grasp kinetics depending on object properties. Experiment 2 Transcranial Magnetic Stimulation studies have shown that the motor system is facilitated by the sole imagination of motor actions. However, it is not clear whether the individual’s motor system resonates bilaterally and selectively for task parameters as movement direction and amplitude. To investigate this issue we apply a single pulse Transcranial Magnetic Stimulation (TMS) over the left and right primary motor cortex (M1) of healthy subjects that had to imagine to grasp and to rotate a clock hour hand, having a starting position at noon, toward four different hours: 2, 5, 7 and 10. Rotations toward 7 and 10 hours were in counter-clockwise direction, but required small movement amplitudes at 10 and large at 7 hour. Conversely, rotations toward 2 and 5 hours followed a clockwise direction and required small movement amplitude at 2 and a large at 5 hour. TMS motor evoked potentials were recorded from three hand muscles and movement imagined with the right and the left hand. Results showed that during motor imagery, the motor system activates the hand-intrinsic muscles specifically for movement direction by showing a mirroring pattern between the right and the left side of the motor cortex. Interestingly none muscle modulation, nor for hand-intrinsic or extrinsic, was observed for movement amplitude suggesting either that amplitude is modulated during the ongoing of the action or that selective inhibition is present in decreasing the otherwise elevated muscle activity evoked. We suggest that the plausibility of a movement is computed in regions upstream the primary motor cortex, and that motor imagery is a higher-order process not fully constrained by the rules that govern motor execution.

碩士
國立臺灣大學
應用力學研究所
107
When we were young,most of us had experience of skipping stones at a pond.Past experience has taught us that we should choose a flat stone,and throw it obliquely.While stones skipping,it moves very fast.We can’t analyze directly by our eyes. In this thesis,we used finite element analysis—LS-PrePost to discuss factors(e.g.,angle between stones and water surface,angle between stones and initial velocity,spin velocity,velocity)which effect the number of bounces.Finding the best number of bounces and predicting number of bounces are our target.Besides,we derive the relation between the ratio of outbound velocity and incidence velocity is cosine of the angle between stones and water surface plus angle between stones and initial velocity.Here we define cosine of the angle between stones and water surface plus angle between stones and initial velocity as a coefficient of restitution.By this coefficient of restitution,it’s easily to know the velocity after richocheting.The velocity after richocheting go with minimum velocity for bouncing can predict the number of bounces. If the the ratio of outbound velocity and incidence velocity is large,it means less energy dissipation after each bounce.The ratio of outbound velocity and incidence velocity is affected by angle between stones and water surface, angle between stones and initial velocity.After analyzing our data,We found out it’s better to choose angle as small as you can. We set an angle between stones and water surface before throwing.In order to prevent angle change,we will give spin velocity at the beginning to offer gyroscopic effect.Gyroscopic effect can stabilize angle.If we want to get more bounces,intuitively we speed up the incident velocity.We have to keep angle as a constant,so we also speed up angular velocity.The angular speed must increase in accordance with the multiple of the incidence speed increase. In this thesis,we derive the equation of predicting the number of bounces.We also found out the best factors to achieve the most number of bounces.