Previous research in force control has focused on the choice of appropriate servo implementation without corresponding regard to the choice of mechanical hardware. This report analyzes the effect of mechanical properties such as contact compliance, actuator-to-joint compliance, torque ripple, and highly nonlinear dry friction in the transmission mechanisms of a manipulator. A set of requisites for high performance then guides the development of mechanical-design and servo strategies for improved performance. A single-degree-of-freedom transmission testbed was constructed that confirms the predicted effect of Coulomb friction on robustness; design and construction of a cable-driven, four-degree-of- freedom, "whole-arm" manipulator illustrates the recommended design strategies.

En la zona costera mediterránea se llevan a cabo una gran cantidad de actividades socioeconómicas. En estas áreas los eventos meteorológicos son un factor importante para su manejo y gestión. Esto ha generado la necesidad de mejorar el conocimiento y la predicción de eventos como las tormentas de oleaje. Por ello, se ha planteado como objetivo principal de esta tesis la caracterización y simulación numérica de tormentas de oleaje.La generación del oleaje es el resultado del sistema acoplado océano - atmósfera. Esta interface y los flujos de momentum entre ambas capas ha sido de interés y ha generado una gran cantidad de investigaciones. Un avance importante ha sido el desarrollo de los modelos de tercera generación de oleaje, capaces de predecir espectros de oleaje a partir de campos de viento. Estos modelos que constituyen la base de esta tesis, consideran el aporte de energía por el viento, la disipación e interacciones no lineales entre ondas.Para este trabajo se han utilizado los modelos WAM y SWAN junto con mediciones de oleaje en la costa catalana. Para forzar los modelos se han utilizado campos de vientos de los modelos atmosféricos MASS ARPEGE. Se han utilizado también datos de viento de estaciones meteorológicas costeras.El viento y oleaje en la franja costera catalana están caracterizados principalmente por componentes del este, noroeste y del sur. Para el caso de tormentas con impacto en la costa, las del este son las más intensas, pero las tormentas del Noroeste pueden generar condiciones de riesgo para la navegación.Se han descrito tormentas características de la costa catalana, considerando su dirección, duración, e intensidad. De manera paralela se han analizado mas detalladamente dos eventos particulares que se registraron en Noviembre 2001 y Marzo-Abril 2002. Ambas tormentas presentaron oleaje de componente principal del este y una cantidad importante de espectros bimodales. Esta característica no se había estudiado a detalle con anterioridad y se debe al oleaje swell del este y a la rotación de los vientos en la costa catalana para volverse del noroeste generando localmente un sistema de oleaje en esta dirección. Debido a esto, la anchura espectral se comporto de manera opuesta a la esperada, pero mostró ser un indicador de la complejidad del estado del mar por lo que se propone que sea utilizada en la estimación del coeficiente de arrastre.Se han utilizado los modelos de oleaje en diferentes situaciones: en un dominio idealizado, en los eventos de Noviembre y Marzo - Abril y durante el invierno 2002 -2003. Los resultados muestran diferencias entre modelos en tiempo y espacio. Utilizando el parámetro integrado de Hs el SWAN mostró un mejor comportamiento para la detección de tormentas. Sin embargo el espectro del WAM mostró en la mayoría de los casos aproximarse mas al espectro medido. Una parte de los errores registrados en los modelos durante las tormentas, se debieron a la mala simulación de la bimodalidad la cual a su vez se debe a una mala resolución espacial y temporal tanto de los modelos de viento como de oleaje. La correcta definición espacial de las islas en el mediterráneo mostró ser poco significante para la validación de las predicciones en la zona costera catalana.Finalmente debemos decir que a pesar de que este trabajo ha avanzado en el conocimiento del oleaje en la costa catalana y el comportamiento de los modelos, este solo es el principio y se debe de dar continuidad a este esfuerzo. Una manera (indispensable) es mejorando las observaciones disponibles e incluir medidas espaciales (satélite, por ejemplo) para la mejor descripción y validación de los modelos. / Many socio-economic activities take place on the Mediterranean coast. Meteorological events are an important factor for the proper management and administration of these activities in this area.This has inspired an improvement of knowledge and forecasting of environmental phenomena such as wave storms. Thus, the main objective of this dissertation is the characterisation and numerical simulation of wave storms.The generation of wind waves are the result of the coupled system which connects the air and the ocean. This layer, and its fluxes, have been of great interest and generated a large amount of research. The development of third generation wave models has been an important step. Such models are able to reproduce directional wave spectra from wind fields taking into consideration wind energy input, dissipation and non-linear interactions. These models are the basis of this dissertation.For this work, we have used the WAM and SWAN models, together with the wind and wave measures on the Catalan coast. The forcing winds came from the MASS and ARPEGE atmospheric models.The wind and waves on the Catalan coast are characterised by an east, northwest and south component. For coastal damage, the storms from the east cause the most severe coastal damage while the northwest storm can create risky conditions for navigation.Typical storms on the Catalan coast are described, taking into account the direction, duration, and significant wave height. Additionally, it was studied in detail two severe storms that were measured during November 2001 and March-April 2002. Both storms presented a mean eastern wave component, however, a large amount of bimodal spectra were found. This feature had not been studied before at this area and it is produced due to the wind rotation (to northwest) at the coast because of the orography. This produces a different behaviour of the spectral width than expected, but such a parameter was an indicator of the complexity of the sea state and thus it is proposed to apply it in the drag coefficient estimation.The wave models were applied under different situations: idealised domain, November 2001 and March-April storms and during a winter period. The results show differences between models in time and space. When considering significan wave height, the SWAN model showed a better behaviour for storm detection. However, the spectral shape was better predicted by WAM. Part of the errors were due to the bad simulation of bimodal features, and at the same time, this was produced by the coarse time and spatial resolution of wind and wave models.Finally we have to outline that this work is an advance in the knowledge of waves on the Catalan coast and the behaviour of the models. However, this is only the beginning and an effort should be made for the continuos development and improvement on this topic. A good start is by increasing the wind and wave measurements available including spatial measures, such as satellite, for the better description and model validation.

Water availability has been of great concern in the State of Texas and many other places worldwide. During 1997-2003, pursuant to the 1997 Senate Bill 1, the Texas Commission on Environmental Quality (TCEQ), its partner agencies, and contractors developed a Water Availability Modeling (WAM) System based on the Water Rights Analysis Package (WRAP) model, developed at Texas A&M University. WAM has been widely applied in the State of Texas and because of its convenience, applications, and capabilities, it is planned to be implemented in other States and Countries. This thesis addresses different aspects of WAM, including conditional reliability modeling, firm yield analysis following classic and recently developed methodologies, evaluating the impact of different considerations on reliability analyses, simplification of complex WAM datasets and the display of WRAP results into ArcMap. Conditional reliability modeling evaluates short term diversion/storage reliabilities based on an initial storage level. WRAP-CON has been evaluated and improved, in addition a new modeling methodology has been developed, in which probabilities of occurrence for each hydrologic sequence is based on the relationship between storage and future flows. Recently developed WRAP capabilities have been evaluated, providing users new tools and increased flexibility. Some of these improvements are firm yield analysis, cycling and dual simulation. In addition to improved software, guidelines have also been developed, including a set to simplify extremely large WAM datasets, while maintaining the effect of all the other water rights in a basin.

Cette thèse est consacrée a l'étude de l'implantation du langage Prolog sur les architectures parallèles Mimd sans mémoire commune. Nous présentons le modèle opéra qui exploite implicitement le parallélisme ou le Prolog pour repartir dynamiquement l'évaluation des programmes sur les différents nœuds du réseau de processeurs. Le système opéra est de type multisequentiel: il n'y a parallélisation que lorsqu'un processeur est inoccupé. Ce système se décompose en une partie operative chargée de l'évaluation du programme Prolog, et une partie contrôle chargée de l'allocation des travaux aux processeurs de la partie operative. Les principaux problèmes de ce type de systèmes sont d'une part le choix de représentation en mémoire de l'arbre ou ainsi que la gestion des liaisons multiples, et d'autre part, le contrôle de l'allocation des différentes branches de l'arbre aux machines abstraites qui effectuent des évaluations séquentielles. La technique de régulation de charge utilisée est fondée sur des méthodes heuristiques. L'ordonnanceur d'opera travaille sur une image approchée de l'état global du système obtenu par échantillonnage des états locaux de chaque unités de travail. Un prototype d'opera a été réalisé sur un réseau de transputers reconfigurable dynamiquement: le supernode. Cette propriété a ete mise a profit dans notre implantation pour réduire les couts de communication. Les communications sont effectuées en parallèle avec le calcul. Le prototype réalisé fournit des gains de performances importants et opera figure parmi les systèmes Prolog parallèles les plus efficaces a l'heure actuelle

Interest in converting portions of the large volumes of flood control storage capacity in federal multiple-purpose reservoirs in Texas and elsewhere to water supply and other conservation purposes has been growing for some time. Evaluation of storage reallocations involving tradeoffs between flood control and conservation purposes in multiple-purpose, multiple-reservoir systems represents a new area for applying the Water Rights Analysis Package (WRAP) and Texas Water Availability Modeling (WAM) System. A system of 12 multiple-purpose reservoirs operated by the U.S. Army Corps of Engineers (USACE) and Brazos River Authority (BRA) was adopted as a case study in this research to develop and test expanded WRAP/WAM-based methods for analyzing modifications in reservoir storage allocations and related system operations. The research consisted of the following tasks: ? The Brazos River Basin WRAP input dataset from the Texas WAM System (Brazos WAM) has a 1940-1997 hydrologic period-of-analysis. The research included developing and applying methods to extend the period-of-analysis to 1900-2007 providing a better representation of river basin hydrology. The methodology developed could potentially be used to update the other river basin datasets in the statewide WAM System. ? The Brazos WAM has 3,830 control points, 670 reservoirs, and hundreds of water rights. The research included developing and applying methods to create a much easier-to-apply condensed dataset focused on the USACE/BRA reservoir system and associated water rights that have only 48 control points and 14 reservoirs. ? The WRAP/WAM System was developed based on a monthly computational time step. The research included applying developmental methodologies for converting a monthly model to a daily time step that includes disaggregation of monthly naturalized flows to daily flows, calibration of flow routing coefficients, and incorporation of forecasting in the simulation. ? The WRAP/WAM System is designed for assessing water supply reliabilities and stream flow and storage frequencies from the perspective of conservative purposes. The research added flood risk indices to the WRAP modeling system in order to address tradeoffs between flood control and conservation purposes. ? The WRAP/WAM-based simulation study performed with the modified WAM dataset developed in this research demonstrates the improvements in water supply capabilities and tradeoffs with flood control associated with various reservoir storage reallocation strategies and other modifications in reservoir system operations.

A study is conducted to test the dynamics of the 33ft Wave-Adaptive Modular Vessel (WAM-V) when outfitted with different suspension systems.  Instrumented with an array of sensors, the vessel is tested with two different suspension arrangements to characterize how they affect WAM-V dynamics, and to ultimately select a suspension that is most suitable for the 33ft WAM-V and other vessels that are planned for the future. Optimizing the suspension can reduce the magnitude of accelerations at the payload tray, benefiting both the operator and the payload.  Reduced accelerations can significantly improve comfort and risk of injury to the operator, while also lessening the likelihood of any damage to any sensitive cargo onboard.  The stock suspension components are characterized through in-house tests conducted at the Center for Vehicle Systems and Safety (CVeSS) at Virginia Tech (VT).  Based on the stock characterizations, new suspension components are chosen to better fit the needs of the 33ft WAM-V. Sea trials are conducted with both suspension systems at the Combatant Craft Division (CCD), a division of the Naval Surface Warfare Center, Carderock Division (NSWCCD), in Norfolk, VA to quantitatively and qualitatively determine the differences between the two suspensions.  The 33ft WAM-V is instrumented with a series of accelerometers and potentiometers for measuring accelerations and displacements.  The data is analyzed for the sea trials conducted at CCD and the results of the analysis indicate that the suspension selection can significantly affect the transmission of shock and vibrations from the pontoons to the operator or payload tray.  Both suspensions are able to mitigate a significant amount of the shocks seen at the pontoons, however, the results do not definitively show which suspension is the better of the two.  This is due to the fact that each suspension is not subjected to the exact same wave conditions, and  therefore the resulting suspension dynamics vary.  For instance, during a 2-foot wave event, the new suspension attenuates more shock than the stock suspension, 76% versus 71%.  However, during a 4-foot wave event, the stock suspension attenuates more shock than the new suspension, 66% versus 60%. Additionally, the suspension selection can significantly influence the ride height.  The stock suspension provides a 70/30 ratio between extension and compression stroke, while the new suspension provides a 50/50 ratio.  The more balanced split between the extension and compression strokes allow for better utilizing the total available stroke for the suspension in both directions.  This significantly reduces the resulting high-g impacts since the suspension does not frequently bottom out when the vessel is subjected to a large wave. It is recommended that the results of this study be extended through laboratory dynamic testing that allows for more repeatable dynamic events than sea trials in order to better establish the influence of each suspension parameter on the vessel dynamics.  Such tests will also allow for a better understanding of the dynamics of the vessel in response to various inputs at the pontoons, both subjectively (visually) and objectively (through measurements). / Master of Science

L'un des enjeux les plus importants à l'heure actuelle pour l'utilisation efficace d'une architecture parallèle est le développement de techniques de régulation de charge appropriées. La mise en oeuvre d'un système logique parallèle efficace se heurte également à cette même exigence. Cette thèse est consacrée à l'étude des mécanismes et stratégies d'évaluation parallèles pour la conception et la réalisation de l'environnement de programmation Prolog parallèle PLoSys. PLoSys se place dans la catégorie des systèmes logiques adoptant un modèle d'exécution multi-séquentiel. Ce modèle exploite automatiquement le parallélisme OU inhérent à la sémantique des programmes Prolog "pur" sur des architectures sans mémoire commune. Dans cette classe de systèmes, la parallélisation est guidée dynamiquement par la stratégie de régulation adoptée en fonction des ressources de calcul disponibles. Afin d'élaborer une fonction de régulation de charge appropriée, nous avons choisi l'utilisation d'une technique de modélisation dans le but d'émuler le comportement réel du système sur une architecture parallèle existante. Notre approche repose sur la représentation de l'exécution d'un programme PROLOG par un graphe de tâches acyclique. L'exécution de ce graphe de tâches permet l'émulation de l'évaluation du programme PROLOG sur l'architecture ciblée. Nous analysons les principaux problèmes liés à la conception d'une fonction de régulation de charge efficace, pour le système PLoSys, à travers un environnement d'évaluation implanté sur un réseau de Transputers : le MegaNode. Les principaux résultats d'analyse des différentes stratégies de régulation de charge sont présentés et évalués.

This diploma thesis focuses on implementation issues of ADS-B in the airspace of Czech republic and Europe. Our introduction contains a review of necessity of this system and describes ADS-B. The next part addresses the legislation of this system in detail, also sums up the state of its implementation and the plan of implementation. Our conclusion shows the problems connected with the system , offers their solution and views for the future.

<p>In order to understand how waves influence the exchange of momentum, latent heat and other parameters, between the ocean surface and the atmosphere, one can use models. A coupling between a wave model and an atmospheric regional climate model, for the Baltic Sea, will be performed at the Meteorology Institute in Uppsala University. The wave model is a state of the art, third generation wave model called WAM.</p><p>The new version of the WAM model (cycle 4) needs to be validated. The aim of this thesis is to perform this validation and also to investigate what meteorological forcing one should use to achieve best results. Two different types of forcing are analyzed, ERA40 reanalysis and the RCA climate model. In order to do this, observations from six different buoys in the Baltic Sea will be compared with the model output from WAM. The parameters that will be compared in this study are significant wave height, direction and peak period.</p><p>A consistent phenomenon for all the buoys is a slightly overestimation by the model of what the rate of this increases with increasing wave height. If one compares the model output when WAM are forced with the RCA climate model and when it is forced with ERA40 reanalysis, the differences between them are notable but not large. ERA40 is slightly better.</p><p>Significant wave height is quite good and gives a reasonably result. Some buoys and periods are better and some are worse. There are some differences for the significant wave height between the east coast and the west coast of Sweden, when forcing the model with RCA. It is slightly better on the west coast. On the contrary, the results from ERA40 are very coherent. The quality of the hindcast for the direction and the peak period, in contrast to the significant wave height, is not that good. The results are not bad, but it only gives a rough picture of the sea state.</p>

In order to understand how waves influence the exchange of momentum, latent heat and other parameters, between the ocean surface and the atmosphere, one can use models. A coupling between a wave model and an atmospheric regional climate model, for the Baltic Sea, will be performed at the Meteorology Institute in Uppsala University. The wave model is a state of the art, third generation wave model called WAM. The new version of the WAM model (cycle 4) needs to be validated. The aim of this thesis is to perform this validation and also to investigate what meteorological forcing one should use to achieve best results. Two different types of forcing are analyzed, ERA40 reanalysis and the RCA climate model. In order to do this, observations from six different buoys in the Baltic Sea will be compared with the model output from WAM. The parameters that will be compared in this study are significant wave height, direction and peak period. A consistent phenomenon for all the buoys is a slightly overestimation by the model of what the rate of this increases with increasing wave height. If one compares the model output when WAM are forced with the RCA climate model and when it is forced with ERA40 reanalysis, the differences between them are notable but not large. ERA40 is slightly better. Significant wave height is quite good and gives a reasonably result. Some buoys and periods are better and some are worse. There are some differences for the significant wave height between the east coast and the west coast of Sweden, when forcing the model with RCA. It is slightly better on the west coast. On the contrary, the results from ERA40 are very coherent. The quality of the hindcast for the direction and the peak period, in contrast to the significant wave height, is not that good. The results are not bad, but it only gives a rough picture of the sea state.