Le travail proposé dans cette thèse porte sur l’amélioration de l’efficacité énergétique et de la sûreté de fonctionnement de la Machine à Réluctance Variable (MRV). D’abord, nous avons présenté la commande de la MRV en modes moteur et générateur débitant sur bus continu. Pour le mode moteur, on cherche à réguler la vitesse de rotation et le couple, alors qu’en mode générateur, l’objectif de la commande est de maintenir constante la tension du bus malgré les fluctuations de la vitesse et de la charge. Une démarche itérative est proposée pour la maximisation du rendement global. Trois paramètres de réglage ont été choisis : L’angle d’amorçage (Ψ), l’angle de conduction (Θp) et le courant de référence des phases (Iref). L’efficacité de l’algorithme est évaluée à travers des simulations et des tests expérimentaux. Un rendement global maximal de 70% est atteint pour des vitesses et couples élevés. Ensuite, on s’est intéressé à la connexion de la Génératrice à Réluctance Variable (GRV) au réseau alternatif monophasé ou triphasé dans le cadre d’une application éolienne. La tension continue à la sortie de la GRV est convertie en une tension alternative par un convertisseur DC-AC. Le premier objectif est de maintenir la tension du bus continu à sa valeur nominale; le second est de contrôler la qualité du courant injecté dans le réseau. En monophasé, trois types de correcteur sont testés pour réguler le courant sinusoïdal (un correcteur PI, un correcteur Résonant et un correcteur Proportionnel-Résonant). En triphasé, une commande VQ dans le référentiel de Park est adoptée: La tension du bus continu est contrôlée à travers le courant id et la puissance réactive est contrôlée par le courant iq. Les résultats de simulation montrent qu’on obtient des courants quasi-sinusoïdaux avec un taux de distorsion harmonique inférieur à 1% aussi bien en monophasé qu’en triphasé. Enfin, pour améliorer la sûreté de fonctionnement de l’actionneur et réduire les coûts liés à l’utilisation de capteurs mécaniques, trois stratégies de commande sans capteur de position sont présentées. La première est basée sur la technique d’injection. La deuxième repose sur l’estimation du flux. La troisième s’appuie sur les observateurs adaptatifs. On trouve que la technique d’injection et la méthode basée sur la mesure du flux fonctionnent de façon complémentaire. La première est efficace en basses vitesses et ne dépend pas de la charge, la deuxième est performante en hautes vitesses et pour des charges élevées. L’observateur adaptatif proposé assure une convergence exponentielle de la position malgré le modèle analytique simplifié de l’inductance utilisé pour la synthèse. Son principal avantage réside dans sa robustesse aux variations paramétriques et au couple de charge qui est estimé. / The work proposed here focuses on the improvement of the energy efficiency and the safety of the Switched Reluctance Machine (SRM). First, the control of the SRM in motor and generator modes is presented. In motor mode, the speed and the torque are regulated, while in generator mode, the objective is to keep constant the DC bus voltage. An iterative optimization algorithm is proposed formaximizing the global efficiency. The analysis of the electromechanical energy conversion has shown that there is an optimal combination of the control variables - turn on angle (Ψ), conduction angle (Θp) and reference current (Iref) – to maximize the efficiency. The strategy is evaluated using intensive numerical simulations and experimental validation. Thanks to the optimization, the global efficiency reaches 70% almost from half the nominal speed to the maximum speed. Then, the Switched Reluctance Generator (SRG) is used as an AC generator for a Wind Energy Conversion (WEC) application. The produced DC power is converted into AC power by means of voltage inverter and delivered to the AC grid. The first issue of the WEC control is to maintain constant the output DC voltage despite the wind speed variations and the load uncertainty. The second issue is to control the quality of the current. In single-phase AC network, three controllers are tested to regulate the AC current (PI controller, Resonant controller, Proportional-Resonant controller). In three-phase AC network, a VQ control in Park’s frame is adopted: The DC bus voltage is controlled through the direct current and the reactive power injected into the grid is controlled through the quadrature current. Simulation results show that quasi-sinusoidal currents with a harmonic distortion rate less than 1% are obtained in both cases. Finally, we address the problem of sensorless control. In fact, the control of the SRM requires that the rotor position is known. A mechanical encoder is used generally to measure the position. The elimination of this position sensor would reduce the cost and packaging requirements of the drive. Three methods to estimate the rotor position are presented. The first one named inductance-method is an active as it is based on the pulse injection technique. The second one named flux-method is a passive one as it used the current measurement. The third one is based on the state observers for the flux, position, and velocity and load torque estimation. The simulations results have shown that the inductance-based method is efficient in low speed region and the flux-based one is more efficient in high-speed region. It is also shown that, observers are exponentially convergent even when a simple analytical modelling, that neglects saturation effect, is used to design the observer.

Regarding the ground electrical connection in trucks and buses, the requirements of earthing in heavy-duty vehicles were gathered and evaluated. The most important problems in the state-of-the-art grounding devices are corrosion, electrical resistance and uncertainty in the mounting process, altogether with depreciation over time. The goal is to come up with new concepts that can give a more reliable and better ground connection into the frame with faster, easier and safer manufacturing operations. Several methods for attaching different ground connectors to the steel frame are going to be investigated, including bolted connections, press devices, soldering, brazing and local plating spots. It will be shown that the welding operation gives the best electrical results, while lowering mounting costs, time and variability. Two welded connectors are then going to be proposed as the best alternatives and a parallel investigation with both of them is going to be carried out. These new concepts, filed for patent protection, are going to be labelled as “SRM Welded ground stud” and “SRM Welded grounding nut”. The first of them consists of a plated steel threaded stud (M8 or M10) with a ring shaped contact surface built in one of the ends, where the Ø12 mm weld is to be performed onto the uncoated frame. The second concept comprises a stainless steel M10 round nut welded over a punched hole. The optimization will also cover different alternatives for plating metals, contact aid compounds and masking caps for both devices. The risk of mechanical weakening of the frame because of the new welded concepts is going to be tested for the case of the SRM Welded ground stud. The results will show an increase in fatigue resistance of at least 20% compared to the current ground screw. Furthermore, the strength of the welded interface will show higher proof load than the stud itself. The welded nuts, tested with torque loading, will show a sufficient performance as well. The electrical tests present an expected decrease in ground resistance of 40% for the welded stud and an increase of 28% for the welded nuts, compared with the current ground screw. The conclusion of this Master Thesis states the recommendation of the implementation of a new grounding method through the SRM Welded ground stud. Although, some modifications in the transportation process of the frames might be needed because of the new protruding parts, pointing an estimated distance of 20mm from the frame surface. / När det gäller jordad elanslutning i lastbilar och bussar, har kraven på jordning i tunga fordon samlats och utvärderats. De största problemen i de mest avancerade jordade enheterna är korrosion, elektriskt motstånd och osäkerhet i monteringsprocessen, sammantaget med avskrivning över tiden. Målet är att utveckla nya koncept som kan ge en bättre och mer tillförlitlig jordanslutning i ramen med snabbare, enklare och säkrare tillverkning. Flera metoder för att fästa olika mark kontakter till stålramen kommer att undersökas, bland annat skruvförband, pressanordning, lödning, hårdlödning och lokala pläteringsfläckar. Det kommer att visa att svetsning ger den bästa elektriska resultatet, samtidigt som monteringskostnader, tid och variabilitet minskar. Två svetsade kontakter kommer sedan att föreslås som de bästa alternativen och en parallell undersökning med dem båda kommer att genomföras. Dessa nya koncept, för vilka patentskydd har ansökts, kommer att märkas som “SRM Svetsade marktapp” och “SRM Svetsade jordmutter”. Den första av dem består av en pläterad stålgängad tapp med en ringformad kontaktyta byggt i en av ändarna, där svetsen skall utföras på den obelagda ramen. Det andra konceptet består av en rostfri rund mutter svetsad över ett stansat hål. Optimeringen kommer även att omfatta olika alternativ för pläterade metaller, kontaktstöds föreningar och maskeringslock för de båda enheterna. Risken för mekanisk försvagning av ramen på grund av det nya svetsade konceptet kommer att testas med avseende på fallet med SRM Svetsad bottenreglar. Resultaten visar en ökad utmattningshållfasthet på minst 20% jämfört med den nuvarande jordskruven. Dessutom kommer styrkan av den svetsade gränsytan uppvisa en högre provbelastning än tappen själv. De svetsade muttrarna, testade med momentbelastning, kommer också uppvisa en tillräcklig prestanda. De elektriska testerna presenterade en förväntad minskning av markmotståndet på 40% för svetsade tappar och en ökning med 28% för svetsade muttrar, jämfört med den nuvarande jordskruven. Slutsatsen av detta examensarbete anger en rekommendation av genomförandet av en ny jordningsmetod genom en SRM Svetsad marktapp. Trots detta kan vissa ändringar behövas i transportprocessen av ramarna på grund av de nya utskjutande delarna, vilka pekar från ramens yta med ett uppskattat avstånd av 20 mm.

The permanent magnet switched reluctance motor (PMSRM) is hybrid dc motor which has the potential to be more effect than the switched reluctance (SRM) and permanent magnet (PM) motors. The PMSRM has a both a salient rotor and stator with permanent magnets placed directly onto the face of common pole stators. The PMSRM is wound like the SRM and can be controlled by the same family of converters. The addition of permanent magnets creates nonlinearities in both the governing electrical and mechanical equations which differentiate the PMSRM from all other classes of electric motors. The primary goal of this thesis is to develop a cohesive and comprehensive control strategy for the PMSRM so as to demonstrate its operation and highlight its efficiency. The control of the PMSRM starts with understanding its region of operation and the underlying torque production of the motor. The selection of operating region is followed by a both linear and nonlinear electrical modeling of the motor and the design of current controllers for the PMSRM. The electromechanical model of the motor is dynamically simulated with the addition of a closed loop speed controller. The speed controller is extended to add an efficiency searching algorithm which finds the operating condition with the highest efficiency online. / Master of Science

A finalidade inicial deste estudo foi desenvolver um modelo computacional multifísico de um acionamento eletrônico, composto por um motor de relutância 4/2 bifásico, um conversor eletrônico de potência, um controlador, os componentes mecânicos estruturais do motor e os acoplamentos entre os diferentes domínios físicos. Para a implementação do modelo proposto, foram utilizados recursos de simulações numéricas e acopladas do MEF (Método dos Elementos Finitos) em uma plataforma de simulação multifísica, de modo a realizar acoplamento entre três áreas do conhecimento: circuitos elétricos, campos eletromagnéticos e componentes mecânicos estruturais e de vibração. Uma vez desenvolvido o modelo multifísico, este foi associado a um procedimento de otimização dos ângulos de disparo que utiliza um modelo de algoritmos genéticos e, como um conjunto, estes foram aplicados na redução da vibração e da ondulação de torque do motor de relutância chaveado, resultando em uma nova metodologia para a abordagem desses problemas. De modo a comprovar os resultados obtidos nas simulações, foram realizados diversos ensaios experimentais para a validação de cada etapa do desenvolvimento, tais como levantamento das formas de onda de tensão e correntes, ensaios de vibração, etc. Os modelos desenvolvidos foram testados em função de modificações realizadas tanto nos parâmetros de controle do acionamento, como também em função de modificações mecânicas estruturais na geometria do rotor. / The initial purpose of this study was developing a multi-physical computational model of a power electronic motor drive, composed to a 2-Phase Switched Reluctance Motor (SRM) 4/2, a power electronic converter, a controller, motor mechanical and structural components and the coupling among different physical domains. For implementing of the proposed model, it was used FEM (Finite Element Method) coupled and numerical simulations resources in a multi-physic simulation platform, in order to accomplish the coupling among the three areas of knowledge: electrical circuits, electromagnetic fields and structural and mechanics components and vibration. Once finished the multi-physical model, it was associated with a optimization procedure of firing angles which uses genetic algorithm model and, as a whole, it was applied on the SRM vibration and torque ripple reduction, resulting in a new methodology to approaching these problems. In order to prove obtained simulation results, it was carried out several experimental tests to validate each development stage, such as the voltage and currents wave forms mapping, vibration tests, etc. The developed models were tested as much function of drive control parameters as the rotor geometry mechanical and structural modifications.

A finalidade inicial deste estudo foi desenvolver um modelo computacional multifísico de um acionamento eletrônico, composto por um motor de relutância 4/2 bifásico, um conversor eletrônico de potência, um controlador, os componentes mecânicos estruturais do motor e os acoplamentos entre os diferentes domínios físicos. Para a implementação do modelo proposto, foram utilizados recursos de simulações numéricas e acopladas do MEF (Método dos Elementos Finitos) em uma plataforma de simulação multifísica, de modo a realizar acoplamento entre três áreas do conhecimento: circuitos elétricos, campos eletromagnéticos e componentes mecânicos estruturais e de vibração. Uma vez desenvolvido o modelo multifísico, este foi associado a um procedimento de otimização dos ângulos de disparo que utiliza um modelo de algoritmos genéticos e, como um conjunto, estes foram aplicados na redução da vibração e da ondulação de torque do motor de relutância chaveado, resultando em uma nova metodologia para a abordagem desses problemas. De modo a comprovar os resultados obtidos nas simulações, foram realizados diversos ensaios experimentais para a validação de cada etapa do desenvolvimento, tais como levantamento das formas de onda de tensão e correntes, ensaios de vibração, etc. Os modelos desenvolvidos foram testados em função de modificações realizadas tanto nos parâmetros de controle do acionamento, como também em função de modificações mecânicas estruturais na geometria do rotor. / The initial purpose of this study was developing a multi-physical computational model of a power electronic motor drive, composed to a 2-Phase Switched Reluctance Motor (SRM) 4/2, a power electronic converter, a controller, motor mechanical and structural components and the coupling among different physical domains. For implementing of the proposed model, it was used FEM (Finite Element Method) coupled and numerical simulations resources in a multi-physic simulation platform, in order to accomplish the coupling among the three areas of knowledge: electrical circuits, electromagnetic fields and structural and mechanics components and vibration. Once finished the multi-physical model, it was associated with a optimization procedure of firing angles which uses genetic algorithm model and, as a whole, it was applied on the SRM vibration and torque ripple reduction, resulting in a new methodology to approaching these problems. In order to prove obtained simulation results, it was carried out several experimental tests to validate each development stage, such as the voltage and currents wave forms mapping, vibration tests, etc. The developed models were tested as much function of drive control parameters as the rotor geometry mechanical and structural modifications.

De nos jours, environ 3000 huiles essentielles sont produites et utilisées dans le monde avec des champs d'application aussi variés que la cosmétique, la parfumerie l'agro-alimentaire, la pharmacie et l'aromathérapie. Ces huiles sont extraites des hespéridés ou des plantes aromatiques et médicinales. Étant donné que la culture de ces matières premières implique généralement l'application de pesticides, la présence de tels résidus dans les huiles essentielles ne peut pas être écartée. Compte tenu du nombre important de pesticides employés et des nombreux champs d'application des huiles essentielles, il apparaît nécessaire, afin d'assurer la santé du consommateur, de disposer d'une méthode d'analyse multi-résidus capable de doser les pesticides dans les huiles essentielles. L'état de l'art des méthodes d'analyse lié à cette problématique a révélé un manque évident de performance des méthodes actuelles aussi bien en termes de limite de détection que du nombre de pesticides analysés. Ce mémoire propose donc la mise au point d'une méthode d'analyse multi-résidus de pesticides dans les huiles essentielles par couplage de la chromatographie liquide et de la spectrométrie de masse, technologie la plus à même de répondre à la problématique au vue de la bibliographie. Après avoir mis en évidence les performances du nouveau mode d'acquisition Scheduled SRM, disponible sur le spectromètre de masse 4000 QTrap, pour la détection et la quantification de 250 pesticides dans un solvant déterminé, l'importance de considérer la nature de la matrice, aussi bien dans les méthodes de préparation que lors de l'analyse de l'échantillon, a ensuite été démontrée en étudiant deux huiles essentielles représentatives (lavandin et citron). Enfin, la méthode d'analyse multi-résidus LC-MS/MS a été appliquée à la recherche de pesticides dans des échantillons réels d'huiles essentielles. Elle a démontré sa capacité à détecter, quantifier et identifier les pesticides dans ces matrices au travers de l'utilisation d'un mode d'acquisition couplé SRM-EPI faisant appel aux spécificités du spectromètre de masse hybride et notamment de sa trappe d'ion linéaire. Ce travail a de plus révélé l'importance de disposer d'une telle méthode au regard du nombre de pesticides détectés dans les échantillons et de leurs concentrations relativement élevées. Celles-ci peuvent en effet atteindre des teneurs supérieures au milligramme par litre dans les huiles essentielles analysées.

En los últimos años, investigadores de diferentes laboratorios y universidades han mostrado un interés creciente en el estudio del motor de reluctancia autoconmutado (SRM). Aunque sus aplicaciones industriales son escasas se presenta como una alternativa a los accionamientos convencionales debido a su construcción simple y robusta, a sus bajos costes de manufactura y a su elevado rendimiento, además de poder escoger entre diversas topologías de convertidor estático, prácticamente todas tolerantes a fallos.En esta tesis se hacen aportaciones al diseño y al dimensionamiento de SRM trifásicos para un margen de potencias comprendido entre 0,25 kW y 10 kW, partiendo de las ecuaciones básicas de la conversión electromecánica, dedicando especial atención a la saturación. Se hacen contribuciones a la caracterización del SRM mediante métodos analíticos, numéricos y experimentales, comparando los resultados obtenidos con los diferentes métodos.Inicialmente se abordan temas de carácter general, como son la ubicación del SRM en el marco de los accionamientos eléctricos, una breve introducción histórica y sus aplicaciones industriales actuales, su constitución y principio de funcionamiento, así como la producción de par.A continuación se presentan las pautas básicas de diseño de la estructura electromagnética para el rango de potencias entre 0,25 kW y 10 kW, aplicadas a la construcción de dos prototipos de 3 fases con configuraciones polares 6/4 y 12/8. Se procede a la caracterización magnética de los prototipos construidos utilizando métodos analíticos, numéricos y experimentales, efectuando una comparación de los resultados obtenidos con cada método.Posteriormente se procede al estudio de modelos que permiten la simulación del SRM, modelos lineales sin considerar el efecto de la saturación y modelos no lineales. Dentro de los modelos no lineales, se presenta el ajuste de las curvas de magnetización mediante diferentes alternativas novedosas, aplicadas al caso de que se conozcan todas las curvas de magnetización y al caso de que únicamente se disponga de su conocimiento en las posiciones alineada y no alineada. Se procede a la simulación de los prototipos diseñados y construidos utilizando los modelos propuestos con control mediante pulso único y con control de histéresis, comparándose los resultados obtenidos con resultados experimentales.Seguidamente se efectúa un estudio de la influencia de diversas variables constructivas de la estructura electromagnética sobre la base de los dos prototipos, variables como el entrehierro, el número de espiras, los ángulos polares, la anchura de los yugos y el material magnético utilizado. También se estudia la influencia de diversas variables de control sobre el funcionamiento del motor, como la influencia del ángulo de disparo, del ángulo de conducción y de la referencia de corriente.Se presentan los resultados experimentales de los ensayos de laboratorio efectuados en los dos prototipos, y se efectúa una propuesta final de metodología en el proceso de dimensionamiento.Finalmente se relacionan las aportaciones realizadas, se presentan las conclusiones y se apuntan futuras líneas de trabajo.

En esta tesis se hacen contribuciones a la simulación interactiva de motores de reluctancia autoconmutados desde la perspectiva de la ingeniería concurrente.En primer lugar, después de una breve introducción histórica, se sitúa el motor de reluctancia autoconmutado (SRM) en el marco de los accionamientos eléctricos y se introducen los principios básicos de la ingeniería concurrente utilizando el prototipado rápido de accionamientos eléctricos.En segundo lugar se presenta la constitución del accionamiento con SRM y sus principios de funcionamiento. Se especifican los antecedentes en el modelado de los SRM y se presenta un tratamiento original de las curvas de magnetización.Seguidamente se trata la simulación de los accionamientos eléctricos desde la perspectiva de la ingeniería concurrente. Tras estudiar la evolución de la simulación (analógica, numérica, analógica digital, multidisciplinar, física, etc.), se muestran los procedimientos de la ingeniería concurrente que parten del modelado del accionamiento con SRM usando las técnicas SIL (Software In the Loop) que permiten escoger y ajustar los controles más adecuados usando un prototipo virtual del accionamiento y que integra los procedimientos utilizados en las técnicas HIL (hardware in the loop), concretándose todo ello en una plataforma digital para el desarrollo de los accionamientos con SRM.A continuación se procede, después de hacer una descripción general del accionamiento programado, a detallar los programas utilizados en la simulación interactiva de los diferentes componentes (convertidor estático, detectores de posición, sensores de corriente, cargas, etc) del accionamiento completo con SRM, considerando diferentes estrategias de control (pulso único, control de corriente mediante histéresis y PWM) y condiciones de funcionamiento (régimen permanente, transitorios y faltas).Posteriormente, se diseña una plataforma para el desarrollo de accionamientos con SRM en tiempo real mediante un entorno de prototipado rápido. Esta plataforma es flexible modular y robusta permitiendo; configurar distintas topologías del convertidor, implementar distintas estrategias de control en tiempo real tanto para el convertidor como para el accionamiento, evitando los problemas habituales de prueba y ajuste, que tanto tiempo hacen perder en el diseño convencional de accionamientos, para centrar la atención y los esfuerzos en los conceptos y aspectos clave de los accionamientos con SRM.Una vez construida la plataforma de desarrollo, esta se utiliza para contrastar y validar los resultados obtenidos mediante la simulación SIL, constatándose además la capacidad de la plataforma para el desarrollo de accionamientos de SRM, así como sus ventajas para la enseñanza e investigación en este tipo de accionamientos. Finalmente, se enumeran las aportaciones realizadas, se presentan las conclusiones finales y se describen futuras líneas de investigación. / In this thesis, contributions are made to the interactive simulation of switched reluctance motors (SRMs) from the perspective of concurrent engineering.Firstly, after a brief introduction to the history of switched reluctance motors (SRMs), they are placed in the context of electric drives. The basic principles of concurrent engineering are then described by means of the rapid prototyping of electric drives.Secondly, the design of drives using SRMs and the principles behind their operation are presented. An overview of SRM modeling is given and an original treatment of magnetization curves is presented.Subsequently, the simulation of electric drives from the perspective of concurrent engineering is carried out. After a study of how simulation (analogical, numerical, analogical-digital, multidisciplinary and physical) has evolved, the procedures of concurrent engineering are demonstrated. The procedures start out by modeling drives with SRMs using SIL (software-in-the-loop) techniques. This makes it possible to choose and to fit the most suitable controls by using a virtual prototype of the drive and integrating the procedures used in HIL (hardware-in-the-loop) techniques. The final outcome is a digital platform for the development of drives using SRMs.After a general description of the drive, the programs used in the interactive simulation of the components (static converters, position detectors, current sensors, loads, etc.) of the complete drive with an SRM are described. Various strategies ranging from control (single pulse, control of current by means of hysteresis and PWM) to conditions of operation (permanent, transitory and faulty schemes) are also considered.A platform for the development of drives using SRMs in real time by means of rapid prototyping is designed. This platform is flexible, modular and robust, which makes it possible to configure different topologies for the converter and to implement different control strategies in real time for the converter and the drive. This avoids the habitual problems of testing and adjusting, which take up a great deal of time in conventional drive design, thus making it possible to focus on the drive's conceptual features.Once the development platform has been built, it is used to validate the results obtained by means of SIL simulation. The platform's capacity to contribute to the development of SRM drives and its advantages for teaching and research in this particular field are demonstrated.Finally, all the original contributions are put forward, the conclusions are presented and future lines of research are described.

Le travail de cette thèse a consisté à concevoir, réaliser et optimiser un montage expérimental de Polarisation Dynamique Nucléaire multi-échantillons pour des applications biomédicales en Imagerie Spectroscopique par Résonance Magnétique. Ce montage est constitué d'un aimant à fort champ magnétique (3,35T), dans lequel se place un système cryogénique à bain d'hélium (He4) liquide pompé pouvant atteindre des températures inférieures à 1,2K. Un ensemble d'inserts permet d'effectuer les différentes étapes du processus PDN dont l'irradiation des échantillons par un champ micro-onde (f=94GHz et P=50mW) et le suivi de leur polarisation par Résonance Magnétique Nucléaire. Ce système permet de polariser jusqu'à trois échantillons, de volume proche de 1mL, à des taux de polarisation de quelques pourcents. Il présente une forte autonomie supérieure à quatre heures, autorisant ainsi la polarisation de molécules à longues constantes de temps de polarisation. La possibilité de disposer quasi-simultanément, après dissolution, de plusieurs échantillons fortement polarisés ouvre la voie à de nouvelles applications dans le domaine de l'imagerie biomédicale

The purpose of this dissertation is to develop and evaluate techniques for improvement of seasonal streamflow forecasts in the Upper Rio Grande (URG) basin in the U.S. Southwest. Three techniques are investigated. The first technique is an investigation of the effects of the El Ni??o/Southern Oscillation (ENSO) on temperature, precipitation, snow water equivalent (SWE), and the resulting streamflow at a monthly time scale, using data from 1952 to 1999 (WY). It was seen that the effects of ENSO on temperature and precipitation were confined to certain months, predominantly at the beginning and end of the winter season, and that the effect of these modulations of temperature and precipitation by ENSO can be seen in the magnitude and time variation of SWE and streamflow. The second part is a comparison of the use for snowmelt-runoff modeling of the newly available snowcover product based on imagery from the satellite-borne Moderate Resolution Imaging Spectroradiometer (MODIS) with the long-time standard snowcover product from the National Hydrological Remote Sensing Center (NOHRSC). This comparison is made using the Snowmelt Runoff Model (SRM) in two watersheds located inside the URG basin. This comparison is important because the MODIS snowcover product could greatly improve the availability of snowcover information because of its high spatial (500m) and temporal (daily) resolutions and extensive (global) coverage. Based on the results of this comparison, the MODIS snowcover product gives comparable snowcover information compared to that from NOHRSC. The final part is an investigation of streamflow forecasting using mass-balance models. Two watersheds used in the comparison of MODIS and NOHRSC snowcover products were again used. The parameters of the mass-balance models are obtained in two different ways and streamflow forecasts are made on January 1st, February 1st, March 1st and April 1st. The first means of parameter estimation is to use the parameter values from 1990 to 2001 SRM streamflow simulations and the second means is by optimization. The results of this investigation show that mass-balance models show potential to improve the long-term streamflow forecasts in snowmelt-dominated watersheds if dependable precipitation forecasts can be provided.