Dissertations / Theses on the topic 'Soil surface parameter'

To date only very few bistatic measurements (airborne or in controlled laboratories) have been reported. Therefore most of the current remote sensing methods are still focused on monostatic (backscatter) measurements. These methods, based on theoretical, empirical or semi-empirical models, enable the estimation of soil roughness and the soil humidity (dielectric constant). For the bistatic case only theoretical methods have been developed and tested with monostatic data. Hence, there still remains a vital need to gain of experience and knowledge about bistatic methods and data. The main purpose of this thesis is to estimate the soil moisture and the soil roughness by using full polarimetric bistatic measurements. In the experimental part, bistatic X-band measurements, which have been recorded in the Bistatic Measurement Facility (BMF) at the DLR Oberpfaffenhofen, Microwaves and Radar Institute, will be presented. The bistatic measurement sets are composed of soils with different statistical roughness and different moistures controlled by a TDR (Time Domain Reflectivity) system. The BMF has been calibrated using the Isolated Antenna Calibration Technique (IACT). The validation of the calibration was achieved by measuring the reflectivity of fresh water. In the second part, bistatic surface scattering analyses of the calibrated data set were discussed. Then, the specular algorithm was used to estimate the soil moisture of two surface roughnesses (rough and smooth) has been reported. A new technique using the coherent term of the Integral Equation Method (IEM) to estimate the soil roughness was presented. Also, the sensitivity of phase and reflectivity with regard to moisture variation in the specular direction was evaluated. Finally, the first results and validations of bistatic radar polarimetry for the specular case of surface scattering have been introduced
Aktuell sind nur sehr wenige Messungen mit bistatischem Radar durchgeführt worden, sei es von Flugzeuggetragenen Systemen oder durch spezielle Aufbauten im Labor. Deshalb basieren die meisten der bekannten Methoden zur Fernerkundung mit Radar auf monostatis-chen Messungen der Rückstreuung des Radarsignals. Diese Methoden, die auf theoretischen, empirischen oder halb-empirischen Modellen basieren, ermöglichen die Schätzung der Oberfächenrauhigkeit und die Bodenfeuchtigkeit (Dielektrizitätskonstante). Im bistatischen Fall wurden bisher nur theoretische Modelle entworfen, die mittels monostatischer Messungen getestet wurden. Aus diesem Grund ist es von großer Bedeutung, Erfahrung und Wissen über die physikalischen Effekte in bistatischen Konfigurationen zu sammeln. Das Hauptziel der vorliegenden Dissertation ist es, anhand vollpolarimetrischer, bistatischer Radarmessungen die Oberfächenrauhigkeit und Bodenfeuchtigkeit zu bestimmen. Im experimentellen Teil der Arbeit werden die Ergebnisse bistatischer Messungen präsentiert, die in der Bistatic Measurement Facility (BMF) des DLR Oberpfaffenhofen aufgenommen wurden. Die Datensätze umfassen Messungen von Böden unterschiedlicher statistischer Rauhigkeit und Feuchtigkeit, die mittels eines Time Domain Reflectivity (TDR) Systems bestimmt werden. Zur Kalibration des BMF wurde die Isolated Antenna Calibration Technique (IACT) verwendet und anhand der Messung der Reflektivität von Wasser überprüft. Im zweiten Teil der vorliegenden Arbeit wird anhand der kalibrierten Daten eine Analyse der Oberflächenstreuung in bistatischen Konfigurationen vorgenommen. Im Anschluss daran wird mittels des Specular Algorithm eine Schätzung der Bodenfeuchte zweier Proben unter- schiedlicher Rauhigkeit (rau und fein) durchgeführt. Ein neues Verfahren zur Schätzung der Oberfächenrauhigkeit, das auf dem kohärenten Term der Integral Equation Method (IEM) basiert, wurde eingeführt. Daneben wird die Empfindlichkeit der Phase sowie der Reflektivität des vorwärtsgestreuten Signals gegenüber Veränderungen der Bodenfeuchtigkeit analysiert. Schließlich werden erste Ergebnisse und Validierungen bistatischer Radarpolarimetrie für den Fall der Vorwärtsstreuung präsentiert

To date only very few bistatic measurements (airborne or in controlled laboratories) have been reported. Therefore most of the current remote sensing methods are still focused on monostatic (backscatter) measurements. These methods, based on theoretical, empirical or semi-empirical models, enable the estimation of soil roughness and the soil humidity (dielectric constant). For the bistatic case only theoretical methods have been developed and tested with monostatic data. Hence, there still remains a vital need to gain of experience and knowledge about bistatic methods and data. The main purpose of this thesis is to estimate the soil moisture and the soil roughness by using full polarimetric bistatic measurements. In the experimental part, bistatic X-band measurements, which have been recorded in the Bistatic Measurement Facility (BMF) at the DLR Oberpfaffenhofen, Microwaves and Radar Institute, will be presented. The bistatic measurement sets are composed of soils with different statistical roughness and different moistures controlled by a TDR (Time Domain Reflectivity) system. The BMF has been calibrated using the Isolated Antenna Calibration Technique (IACT). The validation of the calibration was achieved by measuring the reflectivity of fresh water. In the second part, bistatic surface scattering analyses of the calibrated data set were discussed. Then, the specular algorithm was used to estimate the soil moisture of two surface roughnesses (rough and smooth) has been reported. A new technique using the coherent term of the Integral Equation Method (IEM) to estimate the soil roughness was presented. Also, the sensitivity of phase and reflectivity with regard to moisture variation in the specular direction was evaluated. Finally, the first results and validations of bistatic radar polarimetry for the specular case of surface scattering have been introduced.
Aktuell sind nur sehr wenige Messungen mit bistatischem Radar durchgeführt worden, sei es von Flugzeuggetragenen Systemen oder durch spezielle Aufbauten im Labor. Deshalb basieren die meisten der bekannten Methoden zur Fernerkundung mit Radar auf monostatis-chen Messungen der Rückstreuung des Radarsignals. Diese Methoden, die auf theoretischen, empirischen oder halb-empirischen Modellen basieren, ermöglichen die Schätzung der Oberfächenrauhigkeit und die Bodenfeuchtigkeit (Dielektrizitätskonstante). Im bistatischen Fall wurden bisher nur theoretische Modelle entworfen, die mittels monostatischer Messungen getestet wurden. Aus diesem Grund ist es von großer Bedeutung, Erfahrung und Wissen über die physikalischen Effekte in bistatischen Konfigurationen zu sammeln. Das Hauptziel der vorliegenden Dissertation ist es, anhand vollpolarimetrischer, bistatischer Radarmessungen die Oberfächenrauhigkeit und Bodenfeuchtigkeit zu bestimmen. Im experimentellen Teil der Arbeit werden die Ergebnisse bistatischer Messungen präsentiert, die in der Bistatic Measurement Facility (BMF) des DLR Oberpfaffenhofen aufgenommen wurden. Die Datensätze umfassen Messungen von Böden unterschiedlicher statistischer Rauhigkeit und Feuchtigkeit, die mittels eines Time Domain Reflectivity (TDR) Systems bestimmt werden. Zur Kalibration des BMF wurde die Isolated Antenna Calibration Technique (IACT) verwendet und anhand der Messung der Reflektivität von Wasser überprüft. Im zweiten Teil der vorliegenden Arbeit wird anhand der kalibrierten Daten eine Analyse der Oberflächenstreuung in bistatischen Konfigurationen vorgenommen. Im Anschluss daran wird mittels des Specular Algorithm eine Schätzung der Bodenfeuchte zweier Proben unter- schiedlicher Rauhigkeit (rau und fein) durchgeführt. Ein neues Verfahren zur Schätzung der Oberfächenrauhigkeit, das auf dem kohärenten Term der Integral Equation Method (IEM) basiert, wurde eingeführt. Daneben wird die Empfindlichkeit der Phase sowie der Reflektivität des vorwärtsgestreuten Signals gegenüber Veränderungen der Bodenfeuchtigkeit analysiert. Schließlich werden erste Ergebnisse und Validierungen bistatischer Radarpolarimetrie für den Fall der Vorwärtsstreuung präsentiert.

Placement and compaction of the backfill behind an earth retaining wall may induce a vertical shear force at the soil-to-wall interface. This vertical shear force, or downdrag, is beneficial for the stability of the structure. A significant reduction in construction costs may result if the downdrag is accounted for during design. This potential reduction in costs is particularly interesting in the case of U.S. Army Corps of Engineers lock walls. A simplified procedure is available in the literature for estimating the downdrag force developed at the wall-backfill interface during backfilling of a retaining wall. However, finite element analyses of typical U.S. Army Corps of Engineers lock walls have shown that the magnitude of the downdrag force may decrease during operation of the lock with a rise in the water table in the backfill. They have also shown that pre- and post-construction stress paths followed by interface elements often involve simultaneous changes in shear and normal stresses and unloading-reloading. The hyperbolic formulation for interfaces (Clough and Duncan 1971) is accurate for modeling the interface response in the primary loading stage under constant normal stress. However, it has not been extended to model simultaneous changes in shear and normal stresses or unloading-reloading of the interface. The purpose of this research was to develop an interface model capable of giving accurate predictions of the interface response under field loading conditions, and to implement this model in a finite element program. In order to develop the necessary experimental data, a series of tests were performed on interfaces between concrete and two different types of sand. The tests included initial loading, staged shear, unloading-reloading, and shearing along complex stress paths. An extended hyperbolic model for interfaces was developed based on the results of the tests. The model is based on Clough and Duncan (1971) hyperbolic formulation, which has been extended to model the interface response to a variety of stress paths. Comparisons between model calculations and tests results showed that the model provides accurate estimates of the response of interfaces along complex stress paths. The extended hyperbolic model was implemented in the finite element program SOILSTRUCT-ALPHA, used by the U.S. Army Corps of Engineers for analyses of lock walls. A pilot-scale test was performed in the Instrumented Retaining Wall (IRW) at Virginia Tech that simulated construction and operation of a lock wall. SOILSTRUCT-ALPHA analyses of the IRW provided accurate estimates of the downdrag magnitude throughout inundation of the backfill. It is concluded that the extended hyperbolic model as implemented in SOILSTRUCT-ALPHA is adequate for routine analyses of lock walls.
Ph. D.

Dans un contexte de développement durable, la gestion des sols et des ressources en eau est un enjeu primordial non seulement d’un point de vue environnemental mais aussi socio-économique. L’humidité, la rugosité, la composition et la structure du sol sont des variables clés pour la compréhension et la modélisation des catastrophes naturelles telles que l’érosion, la sécheresse ou les inondations. Pour des sols nus agricoles (très propices au ruissellement), de nombreuses études ont déjà montré le potentiel des données RADAR acquises en bande C pour la cartographie de l'humidité et la rugosité du sol. Cependant l’application de ces méthodes dans un cadre opérationnel était limitée.Dans ce contexte, les travaux de cette thèse présentent un premier volet sur l’analyse de la sensibilité aux états de surface (EDS) du sol du signal en bande X du capteur TerraSAR-X à très haute résolution spatiale et temporelle. Différentes configurations TerraSAR-X ont été analysées et les résultats ont permis de définir les configurations instrumentales optimales pour caractériser chaque paramètre d’EDS du sol. La comparaison de la sensibilité du capteur TerraSAR-X à celle des capteurs en bande C montre que le capteur TerraSAR-X est sans conteste le plus adapté pour estimer et cartographier l’humidité du sol à des échelles fines (50 m²).Le second volet était de développer une méthode permettant d’estimer et de cartographier l’humidité des sols nus agricoles. Dans ce but, les méthodes d'inversion généralement utilisées en bande C ont été testées sur les données en bande X. La précision sur les estimations d’humidité issues de l'algorithme d’inversion du signal TerraSAR-X a été déterminée et l’applicabilité de la méthode sur de nombreux sites d'étude a été testée avec succès. Une chaine de traitements cartographiques allant de la détection des sols nus à l’estimation de l’humidité et ne nécessitant qu’une seule image TerraSAR-X a été développée. Cette chaine innovante de traitements cartographiques « automatique et autonome » devrait permettre d’utiliser les données TerraSAR-X pour cartographier l’humidité du sol en mode opérationnel
In the context of sustainable development, soil and water resources management is a key issue from not only the environmental point of view, but also from a socioeconomic perspective. Soil moisture, roughness, composition, and slaking crusts are some key variables used to understand and model natural hazards, such as erosion, drought and floods. For agricultural bare soils (most subject to runoff), numerous studies have already shown the potential of C-band RADAR data for the mapping of soil moisture and roughness. However, the application of these methods in operational settings remained limited.In this context, the first objective of this thesis was to analyse the sensitivity of X-band TerraSAR-X sensors to soil surface characteristics (SSC) at high spatial and temporal resolutions. Different TerraSAR-X configurations were evaluated and results were used to define the optimal instrumental configuration for the characterization of each SSC parameter. The comparison of TerraSAR-X sensor sensitivity with equivalent levels recorded with the C-band sensor showed that the TerraSAR-X sensor is undoubtedly the most suitable of the two when estimating and mapping soil moisture at a fine scale (50 m²).The second objective of this work was to develop a method to estimate and map soil moisture levels of agricultural bare soil. To achieve this goal, methods that are commonly used to retrieve soil moisture from C-band, have been tested on X-band data. The accuracy of soil moisture estimations using an empirical algorithm was determined, and validated successfully over numerous study sites. A mapping process based uniquely on TerraSAR-X data, both for bare soil detection and for the estimation of soil moisture content, was developed. This innovative chain of « automatic and autonomous» mapping processing steps should enable the utilization of TerraSAR-X data for the mapping of soil moisture levels in operational conditions

Une etude theorique utilisant un modele de simulation, base sur l'approximation scalaire des champs, a permis d'estimer la sensibilite du coefficient de diffusion a une variation relative des parametres de surface, en fonction des caracteristiques radar. Les resultats ont montre que la configuration, jugee optimale, pour une mesure de l'humidite de surface necessite l'utilisation simultanee de deux polarisations (hh et vv), un angle d'incidence eleve (35**(o)) et une frequence de la bande x

This thesis analyzes the hydro-mechanical behavior under a generalized stress state of a compacted mixture of sand (30%) and clayey (70%) at a low density. The experimental study focuses on the analysis of shear strength at different stress paths and at different initial suction values (as-compacted), and the response to collapse due to saturation. For the investigation a conventional triaxial equipment and a hollow cylinder apparatus with automatic control of internal and external chamber pressures, back pressure and axial stress and torque were used. The equipment was not adapted for the measurement of deformations of unsaturated soils, being necessary a calibration of the volumes of the chambers and the relation with the change of volume of the sample. Preliminary tests were performed to better understand the studied of the mixture, like compaction tests, retention curve, oedometer compressibility tests and direct shear and obtain strength, suction and permeability parameters. The shear strength was analyzed through tests carried out in conventional triaxial equipment and in hollow cylinder apparatus, with different stress paths, changing the stress state, valued by parameter b (or Lode angle) and different compaction water content. Low deformation cyclic tests were performed to obtain the shear module in hollow cylinder, using two types of soil, the sand / clayey mixture and a MX-80 bentonite, seeking to analyze the possibilities of testing with the equipment and compare it to the results obtained in other. The results showed that the module obtained in other equipment is greater than those found in hollow cylinder, approaching with increasing deformations, behavior observed for both materials. The collapse tests were performed with constant mean stress (p= 200kPa), different values of deviator stress (q= 10, 75, 185kPa) and different intermediate stress values (b= 0, 0,5, 0,8). The results of the shear strength allowed to define the variation of the critical state line with the Lode angle and the matric suction. Different yield surface models were used for isotropic and anisotropic surface, to verify the rotation of the surface and observe the presence of anisotropic behavior. In all models the change in the critical state line due to the Lode angle was considered. The yield surfaces adjusted well to the experimental results, considering the inclination of the surface and the dependence of the Lode angle. It was observed that the size of the yield surface depends on the suction and the state of tension applied and, a relationship of the parameters was proposed, in order to normalize the yield surface. It was noted that the surface has an inclination due to static compaction, which can be obtained by compaction stresses. It was also observed that this inclination may change depending on the value of b applied to the stress path. Saturation tests under generalized load were analyzed using the BBM model (Barcelona Basic Model) and showed a greater dependence on the magnitude of the deviator stress applied than on the variation of parameter b, and presented a good relationship with the total deformation values. An empirical equation was proposed to estimate the potential for collapse for the different values of b in hollow cylinder, triaxial and oedometer tests.
Esta tesis analiza el comportamiento hidro-mecánico bajo un estado generalizado de tensiones de una mezcla de arena (30%) y arcilla (70%) compactada a una baja densidad. El estudio experimental se centra en el análisis de la resistencia al corte a diferentes trayectorias tensionales a diferentes valores de succión inicial (post compactación) y, a la respuesta al colapso debido la saturación. Para la investigación, se utilizó un equipo triaxial convencional y un equipo de cilindro hueco con control automático de las presiones de cámara interna y externa, de cola y de tensión axial y torque. El equipo no estaba adaptado para la medición de deformaciones de suelos no saturados, siendo necesario una calibración de los volúmenes de las cámaras y la relación con el cambio de volumen de la muestra. Se realizaron ensayos preliminares de compactación, curva de retención, ensayos de compresibilidad edométrica y corte directo, para conocer mejor la mezcla estudiada y obtener parámetros de resistencia, succión y permeabilidad. La resistencia al corte fue analizada a través de ensayos ejecutados en equipo triaxial convencional y en un equipo de cilindro hueco, con diferentes trayectorias tensionales y variando el estado de tensiones, valorado por el parámetro b (o ángulo de Lode) y a diferentes humedades de compactación. Se realizaron ensayos de deformación cíclica a baja deformación para la obtención del módulo de corte en cilindro hueco, utilizando dos tipos de suelo, la mezcla arena/arcilla y una bentonita MX-80, buscando analizar las diferentes posibilidades de ensayos con el equipo y compararlo a los resultados obtenidos en otros equipos. Los resultados mostraron que el módulo obtenido en otros equipos es mayor inicialmente que los encontrados en cilindro hueco, acercándose con el aumento de las deformaciones, comportamiento observado para ambos materiales. Los ensayos de saturación fueron realizados con tensión media constante (p=200kPa), diferentes valores de tensión desviadora (10, 75, 185kPa) y diferentes valores de b (0, 0.5, 0.8). Los resultados de los ensayos de resistencia al corte permitieron definir la variación de la línea de estado crítico con el ángulo de Lode y la succión matricial. Se utilizaron diferentes modelos para la superficie de fluencia, isótropa y anisótropa, para analizar el comportamiento del material y observar la presencia de un comportamiento anisótropo. En todos los modelos se consideró el cambio en la línea de estado crítico debido al ángulo de Lode. Las superficies de fluencia se ajustaron bien a los resultados experimentales, considerando la inclinación de la superficie y la dependencia del ángulo de Lode. Se observó que el tamaño de la superficie de fluencia depende de la succión y del estado de tensión aplicado y, se propuso una relación de los parámetros, a fin de normalizar las superficies de fluencia. Se notó que la superficie presenta una inclinación debido la compactación estática, la cual puede ser obtenida por las tensiones de compactación. También se observó que esta inclinación puede sufrir cambios dependiendo del valor de b aplicado a la trayectoria de tensión. Los ensayos de saturación bajo carga generalizada fueron analizados utilizando el modelo BBM (Barcelona Basic Model) y mostraron una dependencia mayor de la magnitud de la tensión desviadora aplicada que de la variación del parámetro b, y presentó buena relación con los valores totales de deformación. Se propuso una ecuación empírica para estimar el potencial de colapso para los diferentes valores de b en ensayos en cilindro hueco, triaxial y edómetro.

The land (or ‘terrestrial’) biosphere strongly influences the exchange of carbon, energy and water between the land surface and the atmosphere. The size of the land carbon store and the magnitude of the interannual variability of the carbon exchange make models of the land surface a vital component in climate models. This thesis addresses two aspects of land surface modelling: soil respiration and phenology modelling, using different techniques with the goal of improving model representation of land-atmosphere interaction. The release of heat associated with soil respiration is neglected in the vast majority of large-scale models but may be critically important under certain circumstances. In this thesis, the effect of this heat release is considered in two ways. Firstly, a deliberately simple model for soil temperature and soil carbon, including biological heating, is constructed to investigate the effect of thermal energy generated by microbial respiration on soil temperature and soil carbon stocks, specifically in organic soils. Secondly, the mechanism for biological self-heating is implemented in the Joint UK Land Environment Simulator (JULES), in order to investigate the impacts of the extra feedback in a complex model. With the intention of improving estimates of the parameters governing modelled land surface processes, a data assimilation system based on the JULES land surface model is presented. The ADJULES data assimilation system uses information from the derivative of JULES (or adjoint) to search for a locally optimum parameter set by calibrating against observations. In this thesis, ADJULES is used with satellite-derived vegetation indices to improve the modelling of phenology in JULES.

Estimates of the physical parameters of the soil surface, namely moisture content and surface roughness, are important for hydrological and agricultural studies, as they appear to be the two major parameters for runoff forecasting in an agricultural watershed. Radar has high potentiality for the remote measurement of soil surface parameters. In particular, the investigation of the radar backscattering response of bare soil surfaces is an important issue in remote sensing because of its capacity for retrieving the desired physical parameters of the surface. The objective of this study is to formulate and to constrain a methodology for solving the inverse problem for the operational retrieval of soil surface roughness and moisture. To separate the effects of the different parameters on the measured signal over complex areas, multi-technique concepts (multi-polarization, multi-angular, multi-sensor, multi-frequency, and multi-temporal) are the main solution. In this work, based on a simulation study, three different configurations, multi-polarization, multi-frequency and multi-angular, are compared to obtain the best configuration for estimating surface parameters and the multi-angular configuration gives the best results. Based on these results, this study was continued according to five different phases: (1) A new index, the NBRI (Normalized radar Backscatter soil Roughness Index), using the multi-angular approach was presented. This index can estimate and classify surface roughness in agricultural fields using two radar images with different incidence angles. (2) A new linear empirical model to estimate soil surface moisture using RADARSAT-1 data was proposed. This model can provide soil moisture with reduced errors of estimation compared to other linear models. (3) Inversion of the surface parameters using nonlinear classical methods. In this case, the Newton-Raphson method, an iterative numerical method, was used in the retrieval algorithm to solve the inverse problem. (4) In this phase, the neural network technique, with a dynamic learning method, was applied to invert the soil surface parameters from the radar data. The results were obtained through performance testing on two different input schemes (one and two data series) and two different databases (theoretical and empirical). The advantage of the multi-angular set with measured data is apparent. These results are the best in this study. (5) Finally, a novel genetic algorithm (GA) was developed to retrieve soil surface parameters. In this study, it is shown that the genetic algorithms, as an optimization technique, can estimate simultaneously soil moisture and surface roughness from only one radar image.

COSTA, Roner Ferreira da. Estudo de sensibilidade do modelo Brams variáveis dos parâmetros de superfície do Nordeste do Brasil. 2007. 76 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2007.
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In this work a numeric experiment was accomplished with the model BRAMS (Brazilian Regional Atmospheric Modeling System) with the purpose of studying the changes in the surface variables due to the variations of the surface parameters as soil moisture and the vegetation class in the Northeast of Brazil which are input in BRAMS. They were made three simulations, the first (simulation control) it was initialized with the standard files of the own model, the second simulation was maintained the class of vegetation pattern (Deciduous shrub) and just altering the soil moisture and the third simulation alters the vegetation for semi-desert besides reducing the humidity of the soil. Also a validation of the model was accomplished with a soil humidity made calculations starting from observed data of precipitation. It is verified that the humidity of the soil and the vegetation have a strong influences on the climate of the Northeast area of Brazil; however it is not very significant in the weather forecast.
Neste trabalho foi realizado um experimento numérico com o modelo BRAMS (Brazilian Regional Atmospheric Modeling System) com a finalidade de estudar as mudanças verificadas nas variáveis de superfície devido às variações dos parâmetros de superfície tais como, umidade do solo e a classe de vegetação no Nordeste do Brasil que alimentam o BRAMS. Foram feitas três simulações, a primeira (simulação controle) foi inicializadas com os arquivos padrões do próprio modelo, a segunda simulação foi mantido a classe de vegetação padrão (Deciduous shrub) alterando apenas a umidade do solo e a terceira simulação altera a vegetação para semi-deserto além de reduzir a umidade do solo. Também foi realizada uma validação do modelo com uma umidade de solo calculada a partir de dados observados de precipitação. Verifica-se que a umidade do solo e a vegetação têm uma forte influência sobre o clima da região Nordeste do Brasil, porém não é muito significativa na previsão do tempo.

Selon la feuille de route des industriels de la microélectronique (ITRS), la dimension critiqueminimum des MOSFET en 2026 ne devrait être que de 6 nm [1]. La miniaturisation du CMOS reposeessentiellement sur deux approches, à savoir la réduction des dimensions géométriques physiques etdes dimensions équivalentes. La réduction géométrique des dimensions conduit à la diminution desdimensions critiques selon la " loi " de Moore, qui définit les tendances de l'industrie dessemiconducteurs. Comme la taille des dispositifs est réduite de façon importante, davantage d'effortssont consentis pour maintenir les performances des composants en dépit des effets de canaux courts,des fluctuations induites par le nombre de dopants.... [2-4]. D'autre part, la réduction des dimensionséquivalentes devient de plus en plus importante de nos jours et de nouvelles solutions pour laminiaturisation reposant sur la conception et les procédés technologiques sont nécessaires. Pour cela,des solutions nouvelles sont nécessaires, en termes de matériaux, d'architectures de composants et detechnologies, afin d'atteindre les critères requis pour la faible consommation et les nouvellesfonctionnalités pour les composants futurs ("More than Moore" et "Beyond CMOS"). A titred'exemple, les transistors à film mince (TFT) sont des dispositifs prometteurs pour les circuitsélectroniques flexibles et transparents.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Neste trabalho foi realizado um experimento numÃrico com o modelo BRAMS (Brazilian Regional Atmospheric Modeling System) com a finalidade de estudar as mudanÃas verificadas nas variÃveis de superfÃcie devido Ãs variaÃÃes dos parÃmetros de superfÃcie tais como, umidade do solo e a classe de vegetaÃÃo no Nordeste do Brasil que alimentam o BRAMS. Foram feitas trÃs simulaÃÃes, a primeira (simulaÃÃo controle) foi inicializadas com os arquivos padrÃes do prÃprio modelo, a segunda simulaÃÃo foi mantido a classe de vegetaÃÃo padrÃo (Deciduous shrub) alterando apenas a umidade do solo e a terceira simulaÃÃo altera a vegetaÃÃo para semi-deserto alÃm de reduzir a umidade do solo. TambÃm foi realizada uma validaÃÃo do modelo com uma umidade de solo calculada a partir de dados observados de precipitaÃÃo. Verifica-se que a umidade do solo e a vegetaÃÃo tÃm uma forte influÃncia sobre o clima da regiÃo Nordeste do Brasil, porÃm nÃo à muito significativa na previsÃo do tempo.
In this work a numeric experiment was accomplished with the model BRAMS (Brazilian Regional Atmospheric Modeling System) with the purpose of studying the changes in the surface variables due to the variations of the surface parameters as soil moisture and the vegetation class in the Northeast of Brazil which are input in BRAMS. They were made three simulations, the first (simulation control) it was initialized with the standard files of the own model, the second simulation was maintained the class of vegetation pattern (Deciduous shrub) and just altering the soil moisture and the third simulation alters the vegetation for semi-desert besides reducing the humidity of the soil. Also a validation of the model was accomplished with a soil humidity made calculations starting from observed data of precipitation. It is verified that the humidity of the soil and the vegetation have a strong influences on the climate of the Northeast area of Brazil; however it is not very significant in the weather forecast.

Conselho Nacional de Desenvolvimento Científico e Tecnológico
The possibility of mapping soil properties using soil spatial prediction functions (SSPFe) is a reality. But is it possible to SSPFe to estimate soil properties such as the particlesize distribution (psd) in a young, unstable and geologically complex geomorphologic surface? What would be considered a good performance in such situation and what alternatives do we have to improve it? With the present study I try to find answers to such questions. To do so I used a set of 339 soil samples from a small catchment of the hillslope areas of central Rio Grande do Sul. Multiple linear regression models were built using landsurface parameters (elevation, convergence index, stream power index). The SSPFe explained more than half of data variance. Such performance is similar to that of the conventional soil mapping approach. For some size-fractions the SSPFe performance can reach 70%. Largest uncertainties are observed in areas of larger geological heterogeneity. Therefore, significant improvements in the predictions can only be achieved if accurate geological data is made available. Meanwhile, SSPFe built on land-surface parameters are efficient in estimating the psd of the soils in regions of complex geology. However, there still are questions that I couldn t answer! Is soil mapping important to solve the main social and environmental issues of our time? What if our activities were subjected to a social control as in a direct democracy, would they be worthy of receiving any attention?
A possibilidade de mapear as propriedades dos solos através do uso de funções de predição espacial de solos (FPESe) é uma realidade. Mas seria possível construir FPESe para estimar propriedades como a distribuição do tamanho de partículas do solo (dtp) em um superfície geomorfológica jovem e instável, com elevada complexidade geológica e pedológica? O que seria considerado um bom desempenho nessas condições e que alternativas temos para melhorá-lo? Com esse trabalho tento encontrar respostas para essas questões. Para isso utilizei um conjunto de 339 amostras de solo de uma pequena bacia hidrográfica de encosta da região Central do RS. Modelos de regressão linear múltiplos foram construídos com atributos de terreno (elevação, índice de convergência, índice de potência de escoamento). As FPESe explicaram mais da metade da variância dos dados. Tal desempenho é semelhante àquele da abordagem tradicional de mapeamento de solos. Para algumas frações de tamanho o desempenho das FPESe pode chegar a 70%. As maiores incertezas ocorrem nas áreas de maior heterogeneidade geológica. Assim, melhorias significativas nas predições somente poderão ser alcançadas se dados geológicos acurados forem disponibilizados. Enquanto isso, FPESe construídas a partir de atributos de terreno são eficientes em estimar a dtp de solos de regiões com geologia complexa e elevada instabilidade. Mas restam dúvidas que não consegui resolver! O mapeamento de solos é importante para a resolução dos principais problemas sociais e ambientais do nosso tempo? E se nossas atividades estivessem submetidas ao controle da população como em uma democracia direta, seriam elas dignas de receber atenção?

Une analyse bibliographique montre que si l'architecture des parties aeriennes est bien connue chez le mais, il n'en est pas de meme du systeme racinaire. Nous avons donc entrepris un travail de synthese a ce sujet. Dans la premiere partie de cette etude, les parametres descriptifs de la structure racinaire sont definis. Leur evolution au cours du cycle est ensuite caracterisee en conditions habituelles de culture, et, en rhizotrons. Quatre categories de racines primaires ont pu etre mises en evidence

碩士
國立中央大學
太空科學研究所
84
The inversion of the random surface roughness and soil moisture from radar backscattering coefficient is an important subject in remote sensing. The relations between the radar backscattering coefficient and surface roughness and soil moisture are a highly nonlinear. In this article, we first develop an inversion method based on a soil scattering model and a dynamic learning neural network, and then apply this method to the surface parameters retrieval from SAR image. In order to understand the relations between the soil dielectric constant and moisture content, we perform a series of measurements using two methods: dielectric probe and free space, and examine the consistency of the two methods. The interactions of electromagnetic wave and soil surface is very complicated. Since the soil scattering model proposed is accounted for single scattering from surface alone, this is quite different from the real world condition. So we apply the target decomposition theorem to single out the single scattering term from the SAR image to improve the inversion results.

碩士
國立臺灣大學
土木工程學研究所
87
The objection of this research is using Continuous Surface Wave (CSW) seismic test to acquire the in-situ Rayleigh wave dispersion curve, and according to the dispersion curve to inverse the dynamic parameters of soil layers. The content includes that: 1.the method of CSW test and its analysis process, 2.establishes the wave-propagation matrix in a multi-layered medium to get the theoretical dispersion curve, 3.bulids the inversion model by optimization method, and 4.discussing the inversion results of field tests in different sites. In the theoretical, according to the wave propagation theory, elasticity theory, stress continuous conditions, and deformation harmonic conditions…etc. to establish the governing equation of Rayleigh wave propagation behavior in the multi-layered medium. By inputting the boundary conditions, we could get the dispersion function of Rayleigh wave phase velocity, and then overcoming the numerical problems a theoretical dispersion curve is obtained. As to the inversion, preceding guesses the initial soil parameters by simplify method, and matches theoretical and experimental dispersion curves according to the optimization method of simplex algorithm. Adjusting the parameters and the calculations repeated until the two dispersion curves match to a predetermined accuracy. For making the above procedure automatically, we implemented a computer program FBADC (forward and backward analysis of dispersion curve). For evaluation and verification of the results, the new CSW test has been used to determine the in-site dispersion curves of five different sites in Taipei and one in Hua-Lien, and the shear wave velocities obtained from FBADC are compared with results from SCPT at the same locations.

碩士
中原大學
化學工程研究所
92
SiO2 nanoparticles were prepared from tetraethylortho-silicate (TEOS) by using a sol-gel process. The effects of composition of reactants and reaction conditions were discussed. It was found that the size of silica nanoparticles would be changed with those parameters. Basically, particle size would be increase with the TEOS and NH3 concentrations, but decreased with the reaction temperature. Furthermore, particle size increased with water concentration at lower concentration levels of water; however, it decreased with water concentrations at higher concentration levels of water. Particle size would also become bigger because of the lower dielectric constant of solvent. Besides, with the increasing of NH3 and water concentrations, particle size distribution was more uniform. Hence, in order to prepare SiO2 nanoparticles, it is the better way to limit the concentration of TEOS, NH3 and water, and don’t choose a solvent with lower dielectric constant. Higher reaction temperature also favors to synthesize SiO2 nanoparticles. In this study, the synthesis conditions for preparing SiO2 nanoparticles (21.32 nm) were found to be TEOS=0.05 mole, NH3=0.23 mole, H2O=0.55 mole, reaction temperature=60℃ . The response surface methodology (RSM) was also used to analyze the effect of parameters (NH3, water, reaction temperature) on the response variables (particle size and particle size distribution). We observed that these three parameters were all remarkable to the response variable of particle size. Nevertheless, NH3 concentration was more remarkable to the particle size distribution.

This thesis is focused on the problem of the determination of shear surfaces of slope instabilities (including fossil ones) from the results of the complex of logging methods. It describes the steps taken during data measurement, processing, and interpretation. All the data comes from the measurements conducted in the boreholes carried out for the geotechnical survey of the sliding area in the immediate proximity of the D8 highway or measurements in a well from the Děčín-Loubí locality. On the second mentioned locality, due to a different well construction, a more extensive logging complex could be carried out. After locating shear surfaces in a slope instability, a comparsion was made to determine whether the results in neighboring boreholes corresponded to each other, and to evaluate which methods (or combination of methods) suits best for the task.