Im Rahmen der vorliegenden Arbeit sollten anhand eines zweifaktoriellen Feldversuchs bestehend aus den Faktoren Fruchtfolge und Pflanzenschutz die Potenziale zur Reduktion von fruchtfolgebedingten Halmbasis- und Wurzelkrankheitserregern an Weizen (Triticum aestivum L.) durch eine geschickte Kombination von Energiefrüchten aufgezeigt werden. Ein Schwerpunkt lag hierbei auf Halmbasisfusarium und die Ausbreitung des Mykotoxins Deoxynivalenols (DON) von der Halmbasis bis in die Ähre. Hierzu wurden vier Fruchtfolgen mit einer unterschiedlichen Dichte an Ackerkulturen etabliert: (1) Maisdaueranbau, (2) Raps – Winterweizen, (3) Raps – Grünroggen/Mais – Winterweizen und (4) Raps – Winterweizen – Grünroggen/Mais – Winterweizen. Der Versuch wurde auf Versuchsflächen der Universitäten Göttingen und Rostock äquivalent angelegt. Die Erhebungen erfolgten in den Jahren 2010 und 2011. Die Bedeutung der halmbürtigen Mykotoxine für die Belastung des Korns wurde in ergänzenden Untersuchungen unter kontrollierten Bedingungen untersucht. Durch eine visuelle Befallsbonitur im Entwicklungsstadium (ES) der späten Milchreife (ES 77) erfolgte die Ermittlung der Befallshäufigkeit von Rhizoctonia cerealis, Oculimacula yallundae/acuformis, Fusarium spp. und Gaeumannomyces graminis var. tritici an der Halmbasis bzw. Wurzel von Weizen. Mykotoxinnachweise (ELISA-Test) des Leittoxins Deoxynivalenol (DON) und DNA-Quantifizierungen (qPCR) von toxinproduzierenden Fusariumarten in Pflanzen aus Feld-, Gewächshaus- und Klimakammerversuchen gaben weiterhin Aufschluss über die Mykotoxinbelastung der Pflanze und systemische Verlagerung von DON nach einem Befall der Halmbasis von Winterweizen mit Fusarium culmorum und F. graminearum. R. cerealis hatte mit einer Befallshäufigkeit von unter 0,5% in beiden Untersuchungsjahren 2010 und 2011 kaum eine Bedeutung. Erhöhte Befallshäufigkeiten konnten für G. graminis var. tritici mit ca. 20% im Jahr 2010 am Standort in Göttingen und 2011 am Standort in Rostock festgestellt werden. Die Befallswerte waren mit <5 sehr niedrig. Für O. yallundae/acuformis konnten leicht erhöhte Befallshäufigkeiten von maximal 25% bzw. 37% an den Standorten in Rostock und Göttingen im Jahr 2010 festgestellt werden. Im letzten Untersuchungsjahr waren die Befallshäufigkeiten mit 7% bzw. 15% an den Standorten Göttingen und Rostock auf einem niedrigen Niveau. Die zweijährigen Erhebungen in den Jahren 2010 und 2011 machten deutlich, dass Fusarium spp. der dominierende Erreger mit 28% am Standort in Göttingen und 63% am Standort in Rostock an der Halmbasis im Mittel der Jahre war. Es zeigte sich für das Abschlussjahr 2011, dass nach dem Jahreseffekt die Fruchtfolge (18% am Standort in Göttingen) bzw. die Interaktion aus Fruchtfolge und Jahreseffekt (19% am Standort in Rostock) den größten Einfluss auf die Befallshäufigkeit von Fusarium spp. hatte. Die Bewertung der Fruchtfolgen erfolgte anhand der Befallshäufigkeiten von O. yallundae/acuformis und Fusarium spp., die am häufigsten in dieser Untersuchung auftraten. Der Vergleich fand auf Grundlage der Befallshäufigkeiten in der Variante ohne Fungizidapplikation statt und wurde mit denen der Variante mit dem situationsbezogenen Pflanzenschutz verglichen. Es konnte festgestellt werden, dass bei beiden Krankheiten die kurze Fruchtfolge 2 (Raps-Weizen) die höchsten Befallshäufigkeiten aufwies. Eine Fungizidapplikation führte häufig zu einer Reduktion des Befalls in den einzelnen Fruchtfolgen, was aber nicht immer statistisch absicherbar war. Am stärksten reduzierten sich die Befallshäufigkeiten, wenn die Fruchtfolgen aufgelockert wurden. Durch die Eingliederung einer Maiskultur in Kombination mit einer Zwischenfrucht wurde die enge Raps-Weizen Folge unterbrochen, wie es in Fruchtfolge 3 (Raps-Zwischenfrucht/Mais-Weizen) zu erkennen war. Zusätzlich zeigte der unterschiedliche Aussaattermin (früh/spät) in den Anbausystemen einen hochsignifikanten Einfluss (p = 0,000) auf die Befallshäufigkeiten, insbesondere Frühsaaten förderten den Befall. Im Fall von Fusarium spp. zeigte der Vergleich der Fruchtfolgen 2 und 3 eine Reduktion der Befallshäufigkeit um ca. 70% an den Standorten in Göttingen und Rostock. Durch die Fungizidmaßnahme in Fruchtfolge 2 und 3 reduzierte sich der Befall am Standort in Göttingen um weitere 40-50%. Für O. yallundae/acuformis wurde der Unterschied der Fruchtfolgen 2 und 3 noch deutlicher. Die Befallshäufigkeiten reduzierten sich um nahezu 100% an den Standorten in Göttingen und Rostock. Der Vergleich zur Variante mit situationsbezogenem Pflanzenschutz in der Fruchtfolge 2 machte deutlich, dass die Pflanzenschutzmaßnahme den Befall signifikant um 50% reduzierte. Die Belastungen der Kornproben mit dem Mykotoxin DON waren sehr gering, wohingegen die Weizenstoppel der Fruchtfolge 4 in der Variante PS-F0 mit bis zu 6000 µg DON/kg TM kontaminiert war. Proben der Fruchtfolge 3 mit 33% Weizenanteil wiesen mit 2500 µg/kg TM die niedrigsten Gehalte an DON auf. In den Fruchtfolgen 2 und 4 mit 50% Weizenanteil wurden nahezu doppelt so hohe Mengen an DON festgestellt. Im Mittel reduzierte die Fungizidmaßnahme zu ES 31 und 51/55 den DON-Gehalt in der Stoppel signifikant um 50%. Der DON-Nachweis im Substrat der Ganzpflanze von Mais zeigte für den Maisdaueranbau leicht erhöhte Werte von 1800 µg DON/kg TM. Mit abnehmendem Maisanteil in der Fruchtfolge reduzierten sich die DON-Gehalte im Maissubstrat. In Proben der Fruchtfolge 4 mit 25% Maisanteil wurde ein um 80% geringerer DON-Gehalt ermittelt. Die ausgewiesene Grünroggensorte Borfuro wies nach künstlicher Infektion an der Halmbasis mit F. graminearum in Gewächshausversuchen über 4500 µg DON/kg TM in der Ganzpflanze zu ES 73 auf und war damit doppelt hoch mit DON kontaminiert wie eine konventionelle Roggensorte. Dieser signifikante Sortenunterschied wurde durch die Bestimmung pilzlicher DNA in der Halmbasis bestätigt. Durch den Rostocker Aktivitätstest mit hoch DON-belastetem Grünroggen im Mini-Batch Verfahren konnte gezeigt werden, dass DON keine inhibitorische Wirkung auf den Fermentationsprozess hat. Es wurde aber eine 10% geringere Gasausbeute in den Varianten mit kontaminiertem Material festgestellt. Kurze Fruchtfolgen mit Energiepflanzen (Raps–Weizen) führen zu nicht unerheblichen Befallshäufigkeiten von O. yallundae/acuformis und Fusarium spp. an der Halmbasis von Weizen. Eine Kombination der Energiefrüchte Raps, Mais und Weizen in Verbindung mit einem späten Saattermin und wendender Bodenbearbeitung verhindert fast vollständig das Auftreten von O. yallundae/acuformis und reduziert signifikant den Befall mit Fusarium spp. an Weizen. Fruchtfolgen mit einem hohen Anteil von Mais bzw. führen auch zu hohen Gehalten an DON im Ganzpflanzensubtstrat von Mais bzw. in der Halmbasis von Weizen. Zwar hat die Toxinbelastung des Ganzpflanzensubstrats von Mais keine negativen Auswirkungen auf den Gärprozess, aber ist die Gasausbeute reduziert. Es Auswirkungen von Fusariuminfektionen auf die Gärqualität von Mais sollten daher in weiteren Untersuchen näher betrachtet werden.

Ce travail a pour cadre une collaboration entre le LMA et Thales Alenia Space. Nous nous intéressons au comportement des structures flexibles et plus particulièrement des mètres rubans qui ont la particularité de pouvoir, grâce à l'aplatissement de la section, s'enrouler ou développer des pliages localisés. Une première thèse a permis d'une part la mise au point d'un nouveau type de mètre ruban au déroulement maîtrisable thermiquement et d'autre part le développement d'un modèle plan de poutre à section flexible. Dans le travail de thèse présenté ici, nous proposons une version étendue de ce modèle adaptée à la simulation du comportement dynamique tridimensionnel des mètres rubans en grands déplacements et en grandes rotations. Ce modèle est dérivé de la théorie des coques et repose sur l'introduction d'hypothèses cinématiques et sthéniques adaptées. La déformation de la section est caractérisée par celle de sa ligne moyenne qui peut se déformer dans son plan par flexion et torsion mais non par extension, ainsi que hors de son plan par gauchissement de torsion. Les fortes variations de forme de la section dans son plan peuvent alors être décrites par une cinématique de type Elastica, tandis qu'une cinématique de type Vlassov est utilisée pour définir le gauchissement dans le repère local attaché à la section. Le modèle unidimensionnel est obtenu par intégration sur la section des expressions de la théorie des coques, une approche énergétique permet ensuite de formuler le problème associé qui est résolu grâce au logiciel de modélisation par éléments finis COMSOL.

The three dimensional Monte Carlo radiation transport model McArtim is extended to account for the simulation of the propagation of polarized radiation and the inelastic rotational Raman scattering which is the cause of the so called Ring effect. From the achieved and now sufficient precision of the calculated Ring effect new opportunities in optical absorption spectroscopy arise. In the calculation the method of importance sampling (IS) is applied. Thereby one obtains from an ensemble of Monte Carlo photon trajectories an intensity accounting for the elastic aerosol particle-, Cabannes- and the inelastic rotational Raman scattering (RRS) and simultaneously an intensity, for which Rayleigh scattering is treated as an elastic scattering process. By combining both intensities one obtains the so called filling-in (FI, which quantifies the filling-in of Fraunhofer lines) as a measure for the strength of the Ring effect with the same relative precision as the intensities. The validation of the polarized radiometric quantities and the Ring effect is made by comparison with partially published results of other radiation transport models. Furthermore the concept of discretisation of the optical domain into grid cells is extended by making grid cells arbitrarily joining into so called clusters, i.e. grid cell aggregates. Therewith the program is able to calculate derivatives of radiometrically or spectroscopically accessible quantities, namely the intensities at certain locations in the atmospheric radiation field and the light path integrals of trace gas concentrations associated thereto, i.e. the product of the DOAS (differential optical absorption spectroscopy) method, with respect to optical properties of aerosols and gases in connected spatial regions. The first and second order derivatives are validated through so called self-consistency tests. These derivatives allow the inversion of three dimensional tracegas and aerosol concentration profiles and pave the way down to 3D optical scattered light tomography. If such tomographic inversion scheme is based solely on spectral intensitites the available second order derivatives allows the consideration of the curvature in the cost function and therefore allows implementation of efficient optimisation algorithms. The influence of the instrument function on the spectra is analysed in order to mathematically assess the potential of DOAS to a sufficient degree. It turns out that the detailed knowledge of the instrument function is required for an advanced spectral analysis. Concludingly the mathematical separability of narrow band signatures of absorption and the Ring effect from the relatively broad band influence of the elastic scattering processes on the spectra is demonstrated which corresponds exactly to the DOAS principle. In that procedure the differential signal is obtained by approximately 4 orders of magnitude faster then by the separate modelling with and without narrow band structures. Thereby the fusion of the separated steps DOAS spectral analysis and subsequent radiation transport modeling becomes computationally feasible.

This thesis is concerned with the efficient numerical simulation of finite element based flexible multibody systems. Scaling operations are systematically applied to the governing index-3 differential algebraic equations in order to solve the problem of ill conditioning for small time step sizes. The importance of augmented Lagrangian terms is demonstrated. The use of fast sparse solvers is justified for the solution of the linearized equations of motion resulting in significant savings of computational costs. Three time stepping schemes for the integration of the governing equations of flexible multibody systems are discussed in detail. These schemes are the two-stage Radau IIA scheme, the energy decaying scheme, and the generalized-α method. Their formulations are adapted to the specific structure of the governing equations of flexible multibody systems. The efficiency of the time integration schemes is comprehensively evaluated on a series of test problems. Formulations for structural and constraint elements are reviewed and the problem of interpolation of finite rotations in geometrically exact structural elements is revisited. This results in the development of a new improved interpolation algorithm, which preserves the objectivity of the strain field and guarantees stable simulations in the presence of arbitrarily large rotations. Finally, strategies for the spatial discretization of beams in the presence of steep variations in cross-sectional properties are developed. These strategies reduce the number of degrees of freedom needed to accurately analyze beams with discontinuous properties, resulting in improved computational efficiency.

Path integral approaches have been widely used for long in both quantum mechanics as well as statistical mechanics. In addition to being a tool for obtaining the probability distributions of interest(wave functions in the case of quantum mechanics),these methods are very instructive and offer great insights into the problem. In this thesis, path integrals are extensively employed to study some very interesting problems in both equilibrium and non-equilibrium statistical mechanics. In the non-equilibrium regime, we have studied, using a path integral approach, a very interesting class of anomalous diffusion, viz. the L´evy flights. In equilibrium statistical mechanics, we have evaluated the partition function for a class of molecules referred to as the hindered rotors which have a barrier for internal rotation. Also, we have evaluated the exact quantum statistical mechanical propagator for a harmonic potential with a time-dependent force constant, valid under certain conditions. Diffusion processes have attracted a great amount of scientific attention because of their presence in a wide range of phenomena. Brownian motion is the most widely known class of diffusion which is usually driven by thermal noise. However ,there are other classes of diffusion which cannot be classified as Brownian motion and therefore, fall under the category of Anomalous diffusion. As the name suggests, the properties of this class of diffusion are very different from those for usual Brownian motion. We are interested in a particular class of anomalous diffusion referred to as L´evy flights in which the step sizes taken by the particle during the random walk are obtained from what is known as a L´evy distribution. The diverging mean square displacement is a very typical feature for L´evy flights as opposed to a finite mean square displacement with a linear dependence on time in the case of Brownian motion. L´evy distributions are characterized by an index α where 0 <α ≤ 2. When α =2, the distribution becomes a Gaussian and when α=1, it reduces to a Cauchy/Lorentzian distribution. In the overdamped limit of friction, the probability density or the propagator associated with L´evy flights can be described by a position space fractional Fokker-Planck equation(FFPE)[1–3]. Jespersen et al. [4]have solved the FFPE in the Fourier domain to obtain the propagator for free L´evy flight(absence of an external potential) and L´evy flights in linear and harmonic potentials. We use a path integral technique to study L´evy flights. L´evy distributions rarely have a compact analytical expression in the position space. However, their Fourier transformations are rather simple and are given by e−D │p│α where D determines the width of the distribution. Due to the absence of a simple analytical expression, attempts in the past to study L´evy flights using path integrals in the position space [5, 6] have not been very successful. In our approach, we have tried to make use of the elegant representation of the L´evy distribution in the Fourier space and therefore, we write the propagator in terms of a two-dimensional path integral –one over paths in the position space(x)and the other over paths in the Fourier space(p). We shall refer to this space as the ‘phase space’. Such a representation is similar to the Hamiltonian path integral of quantum mechanics which was introduced by Garrod[7]. If we try to perform the path integral over Fourier variables first, then what remains is the usual position space path integral for L´evy flights which is rather difficult to solve. Instead, we perform the position space path integral first which results in expressions which are rather simple to handle. Using this approach, we have obtained the propagators for free L´evy flight and L´evy flights in linear and harmonic potentials in the over damped limit [8]. The results obtained by this method are in complete agreement with those obtained by Jesepersen et al. [4]. In addition to these results, we were also able to obtain the exact propagator for L´evy flights in a harmonic potential with a time-dependent force constant which has not been reported in the literature. Another interesting problem that we have considered in the over damped limit is to obtain the probability distribution for the area under the trajectory of a L´evy particle. The distributions, again, were obtained for free L´evy flight and for L´evy flights subjected to linear and harmonic potentials. In the harmonic potential, we have considered situations where the force constant is time-dependent as well as time-independent. Like in the case of the over damped limit, the probability distribution for L´evy flights in the under damped limit of friction can also be described using a fractional Fokker-Planck equation, although in the full phase space. However, this has not yet been solved for any general value of α to obtain the complete propagator in terms of both position and velocity. Using our path integral approach, the exact full phase space propagators have been obtained for all values of α for free L´evy flights as well as in the presence of linear and harmonic potentials[8]. The results that we obtain are all exact when the potential is at the most harmonic. If the potential is higher than harmonic, like the cubic potential, we have used a semi classical evaluation where, we extremize the action using an optimal path and further, account for fluctuations around this optimal path. Such potentials are very useful in describing the problem of escape of a particle over a barrier. The barrier crossing problem is very extensively studied for Brownian motion (Kramers problem) and the associated rate constant has been calculated in a variety of methods, including the path integral approach. We are interested in its L´evy analogue where we consider the escape of a particle driven by a L´evy noise over a barrier. On extremizing the action which depends both on phase space variables, we arrived at optimal paths in both the position space as well as the space of the conjugate variable, p. The paths form an infinite hierarchy of instant on paths, all of which have to be accounted for in order to obtain the correct rate constant. Care has to be taken while accounting for fluctuations around the optimal path since these fluctuations should be independent of the time-translational mode of the instant on paths. We arrived at an ‘orthogonalization’ scheme to perform the same. Our procedure is valid in the limit when the barrier height is large(or when the diffusion constant is very small), which would ensure that there is small but a steady flux of particles over the barrier even at very large times. Unlike the traditional Kramers rate expression, the rate constant for barrier crossing assisted by L´evy noise does not have an exponential dependence on the barrier height. The rate constant for wide range of α, other than for those very close to α = 2, are proportional to Dμ where, µ ≈ 1 and D is the diffusion constant. These observations are consistent with the simulation results obtained by Chechkin et al. [9]. In addition, our approach when applied to Brownian motion, gives the correct dependence on D. In equilibrium statistical mechanics we have considered two problems. In the first one, we have evaluated the imaginary time propagator for a harmonic oscillator with a time-dependent force constant(ω2(t))exactly, when ω2(t) is of the form λ2(t) - λ˙(t)where λ(t) is any arbitrary function of t. We have made use of Hamiltonian path integrals for this. The second problem that we considered was the evaluation of the partition function for hindered rotors. Hindered rotors are molecules which have a barrier for internal rotation. The molecule behaves like free rotor when the barrier is very small in comparison with the thermal energy, and when the barrier is very high compared to thermal energy, it behaves like a harmonic oscillator. Many methods have been developed in order to obtain the partition function for a hindered rotor. However, most of them are some what ad-hoc since they interpolate between free-rotor and the harmonic oscillator limits. We have obtained the approximate partition function by writing it as the trace of the density matrix and performing a harmonic approximation around each point of the potential[10]. The density matrix for a harmonic potential is in turn obtained from a path integral approach[11]. The results that we obtain using this method are very close to the exact results for the problem obtained numerically. Also, we have devised a proper method to take the indistinguishability of particles into account in internal rotation which becomes very crucial while calculating the partition function at low temperatures.

The three dimensional Monte Carlo radiation transport model McArtim is extended to account for the simulation of the propagation of polarized radiation and the inelastic rotational Raman scattering which is the cause of the so called Ring effect. From the achieved and now sufficient precision of the calculated Ring effect new opportunities in optical absorption spectroscopy arise. In the calculation the method of importance sampling (IS) is applied. Thereby one obtains from an ensemble of Monte Carlo photon trajectories an intensity accounting for the elastic aerosol particle-, Cabannes- and the inelastic rotational Raman scattering (RRS) and simultaneously an intensity, for which Rayleigh scattering is treated as an elastic scattering process. By combining both intensities one obtains the so called filling-in (FI, which quantifies the filling-in of Fraunhofer lines) as a measure for the strength of the Ring effect with the same relative precision as the intensities. The validation of the polarized radiometric quantities and the Ring effect is made by comparison with partially published results of other radiation transport models. Furthermore the concept of discretisation of the optical domain into grid cells is extended by making grid cells arbitrarily joining into so called clusters, i.e. grid cell aggregates. Therewith the program is able to calculate derivatives of radiometrically or spectroscopically accessible quantities, namely the intensities at certain locations in the atmospheric radiation field and the light path integrals of trace gas concentrations associated thereto, i.e. the product of the DOAS (differential optical absorption spectroscopy) method, with respect to optical properties of aerosols and gases in connected spatial regions. The first and second order derivatives are validated through so called self-consistency tests. These derivatives allow the inversion of three dimensional tracegas and aerosol concentration profiles and pave the way down to 3D optical scattered light tomography. If such tomographic inversion scheme is based solely on spectral intensitites the available second order derivatives allows the consideration of the curvature in the cost function and therefore allows implementation of efficient optimisation algorithms. The influence of the instrument function on the spectra is analysed in order to mathematically assess the potential of DOAS to a sufficient degree. It turns out that the detailed knowledge of the instrument function is required for an advanced spectral analysis. Concludingly the mathematical separability of narrow band signatures of absorption and the Ring effect from the relatively broad band influence of the elastic scattering processes on the spectra is demonstrated which corresponds exactly to the DOAS principle. In that procedure the differential signal is obtained by approximately 4 orders of magnitude faster then by the separate modelling with and without narrow band structures. Thereby the fusion of the separated steps DOAS spectral analysis and subsequent radiation transport modeling becomes computationally feasible.:1.1. Radiation Transport Modeling and Atmospheric State Inversion 1.2. Vector RTE Solution Methods 1.3. Scope of the Thesis 1.4. Outline of the Thesis 2.1. General Structure 2.1.1. Chemical Composition of the Gas Phase 2.1.2. The Troposphere, Temperature and Pressure Vertical Structure 2.1.3. The Stratosphere 2.2. Aerosols and Clouds 2.2.1. Classification and Morphology 2.2.2. Water Related Particle Growth and Shrinking Processes 2.2.3. Size Spectra and Modes 3.1. Electromagnetic Waves 3.1.1. Maxwell\''s Equations 3.1.2. Measurement of Electromagnetic Waves 3.1.3. Polarization State of EM Waves 3.1.4. Stokes Vectors 3.2. Scattering and Absorption of EM Waves by Molecules and Particles 3.2.1. General Description of Scattering and Coordinate Systems 3.2.2. Molecular Scattering 3.2.3. Molecular Absorption Processes and Electronic Molecular States 3.2.4. Scattering On Spherical Particles - Mie Theory 3.3. Mathematical Description of Radiation Transport 3.3.1. Radiance and Irradiance 3.3.2. Absorption, Scattering and Extinction Coefficients 3.3.3. Optical Thickness and Transmission 3.3.4. Scattering 3.3.5. Incident (Ir)Radiance 3.3.6. The Black Surface Single Scattering Approximation 3.3.7. Radiative Transfer Equations 4.1. General Monte Carlo Methods 4.1.1. Numerical Integration 4.1.2. Importance Sampling and Zero Variance Estimates 4.1.3. Optimal Sampling 4.1.4. Sampling from Arbitrary Distributions 4.2. Path Generation or Collision Density Estimation 4.2.1. Discretization of the Optical Domain into Cells and Clusters 4.2.2. RTE Integral Form 4.2.3. Formal Solution of the IRTE 4.2.4. Overview on Monte Carlo RTE Solution Algorithms 4.2.5. Crude Monte Carlo 4.2.6. Sequential Importance Sampling (SIS) or Path Generation 4.3. Importance Sampling in Monte Carlo SIS Radiative Transfer 4.3.1. Weights for Alternate Kernels 4.3.2. Weights in the Calculation of RTE Functional Estimates 4.3.3. Application of IS to Mie Phase Functions Scatter Angle Sampling 5.1. Radiances, Intensities and the Reciprocity Theorem 5.1.1. Scalar Radiance Estimates 5.1.2. Backward Monte Carlo Scalar Radiance 5.1.3. Vector Radiances 5.2. Radiance Derivatives 5.2.1. Variables for Radiance Derivatives 5.3. Validation of Functionals 5.3.1. Validation of Vector Radiances 5.3.2. Validation of Radiance Derivatives 6.1. A Simply Structured Instrument Forward Model 6.2. Pure Atmospheric Spectra and Absorption 6.2.1. Direct Light Spectra 6.2.2. Scattered Sun Light Spectra 6.3. (D)OAS from the Perspective of Radiative Transfer Modeling 6.3.1. (Rest) Signatures of Weakly Absorbing Gases 6.3.2. Spectroscopic Measurements and Standard DOAS 6.4. DOAS Analysis Summary 6.4.1. DSCD Retrieval 6.4.2. Inversion 7.1. RRS-Modified RTE 7.1.1. RRS Cross Sections for Scattering out and into a Wavelength 7.1.2. Modification of the RTE Loss and Source Terms 7.2. Intensity Estimates Considering Rotational Raman Scattering 7.2.1. RRS in the Path Sampling Procedure 7.2.2. Adjoint RRS Correction Weights 7.2.3. Local Estimates of Intensities with RRS 7.2.4. Intensity Estimates 7.3. Ring Spectra 7.3.1. Elastic Biasing of the Local Estimates 7.3.2. Cumulative Weights and Local Estimates 7.3.3. Test of the Elastic Biasing 7.4. Validation 7.4.1. Comparison to an Analytic Single Scattering Code 7.4.2. Single Scattering Model Including Rotational Raman Scattering 7.4.3. Multiple Scattering Model Comparison 7.4.4. Comparison with A Measurement 7.4.5. Validation of Approximate Methods For Ring Effect Modeling 7.5. Summary and Discussion 8.1. Status and Summary 8.1.1. Ring-Effect and Absorption Corrected Radiances 8.1.2. Derivatives of Radiometric Quantities Accessible Through Spectroscopy 8.1.3. Polarization 8.1.4. Time Integrated Sensitivities for 3D UV/vis/NIR Remote Sensing 8.2. Outlook A.1. Zero Variance Estimates A.2. Free Path Length Sampling in a Homogeneous Medium A.3. Cumulative Differential Scatter Cross Sections A.3.1. Cardanic formulas A.3.2. Rayleigh and Raman Phase Functions A.3.3. Henyey-Greenstein Model A.3.4. Legendre Polynomial Phase Function Model A.3.5. Table Methods A.4. Greens Function in the Derivation of the IRTE A.5. Source Code For Stokes Vector Transformation Plot B.1. 1st Order Derivatives B.2. 2nd Order Derivatives B.3. Hessian of Integrals Depending on Many Variables C.1. Slit Function f Derivatives C.2. Signal Sn Derivatives C.3. Chi Square Spline Fitting C.3.1. Constrained Non-Linear Least Square Problem C.3.2. Spline Fitting C.3.3. Jacobians and Hessian

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El análisis de la respuesta mecánica de piezas alargadas que experimentan grandes desplazamientos y rotaciones constituye un campo en el que se han producido avances significativos en las tres últimas décadas, tanto desde el punto de vista de la formulación de modelos físicos como de la búsqueda de soluciones numéricas. El ámbito de aplicación de este tipo de modelos se separa quizás del abanico de problemas de los que tradicionalmente se ha ocupado la ingeniería civil, aproximándose más a situaciones propias de otras disciplinas, como la aeronáutica, la robótica o la biomecánica. Dentro de la variedad de modelos en una dimensión desarrollados para el análisis no lineal de piezas alargadas, el propuesto por Simó como extensión del trabajo de Reissner es capaz de reproducir rotaciones arbitrariamente grandes de las secciones transversales. Su sencillez conceptual y la potencia de las soluciones numéricas basadas en él lo hanconvertido en referencia obligada y punto de partida de muchas investigaciones recientes. El propio Simó introdujo la denominación de \emph{modelo geométricamente exacto de piezas alargadas} para referirse a él. No obstante, el modelo de Reissner--Simó no está libre de dificultades. Éstas derivan principalmente del tratamiento exacto de las rotaciones, que exige trabajar en un espacio de configuraciones no lineal ni conmutativo. Esta tesis examina los fundamentos del modelo geométricamente exacto y su conexión con la teoría no lineal de la elasticidad. La relación entre variables materiales y espaciales a través de la transformación definida por la rotación de cada sección establece el método de análisis. En un primer paso se ha desarrollado completamente la cinemática del modelo y las ecuaciones de campo en sus dos facetas --material y espacial--, lo que ha permitido sistematizar el proceso deductivo y aportar algunos resultados teóricos novedosos. El análisis del problema desde el punto de vista variacional ha puesto de manifiesto las conexiones / Lázaro Fernández, CM. (2005). Formulación material y espacial del modelo geometricamente exacto de piezas alargadas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1872

Curved and skewed I-girder bridges exhibit torsional displacements of the individual girders and of the overall bridge cross-section under dead loads. As a result, the girder webs can be plumb in only one configuration. If the structure is built such that the webs are plumb in the ideal no-load position, they generally cannot be plumb under the action of the structure's steel or total dead load; hence, twisting of the girders is unavoidable under dead loads. The deflected geometry resulting from these torsional displacements can impact the fit-up of the members, the erection requirements (crane positions and capacities, the number of temporary supports, tie down requirements, etc.), the bearing cost and type, and the overall strength of the structure. Furthermore, significant layover may be visually objectionable, particularly at piers and abutments. If the torsional deflections are large enough, then the cross-frames are typically detailed to compensate for them, either partially or fully. As specified in Article C6.7.2 of the AASHTO LRFD Specifications, different types of cross-frame detailing methods are used to achieve theoretically plumb webs under the no-load, steel dead load, or total dead load conditions. Each of the cross-frame detailing methods has ramifications on the behavior and constructability of a bridge. Currently, there is much confusion and divergence of opinion in the bridge industry regarding the stage at which steel I girder webs should be ideally plumb and the consequences of out-of-plumbness at other stages. Furthermore, concerns are often raised about potential fit-up problems during steel erection as well as the control of the final deck geometry (e.g., cross-slopes and joint alignment). These influences and ramifications of cross-frame detailing need to be investigated and explained so that resulting field problems leading to needless construction delays and legal claims can be avoided. This dissertation addresses the influence of cross-frame detailing on curved and/or skewed steel I girder bridges during steel erection and concrete deck placement by conducting comprehensive analytical studies. Procedures to determine the lack-of-fit forces due to dead load fit (DLF) detailing are developed to assess the impact of different types of cross-frame detailing. The studies include benchmarking of refined analytical models against selected full scale experimental tests and field measurements. These analytical models are then utilized to study a variety of practical combinations and permutations of bridge parameters pertaining to horizontal curvature and skew effects. This research develops and clarifies procedures and provides new knowledge with respect to the impact of cross-frame detailing methods on: 1) constructed bridge geometries, 2) cross-frame forces, 3) girder stresses, 4) system strengths, 5) potential uplift at bearings, and 6) fit-up during erection. These developments provide the basis for the development of refined guidelines for: 1) practices to alleviate fit-up difficulties during erection, 2) selection of cross-frame detailing methods as a function of I-girder bridge geometry characteristics, and 3) procedures to calculate the locked-in forces due to DLF cross-frame detailing.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-03-21T16:56:36Z No. of bitstreams: 1 PGCS12DA031.pdf: 1064335 bytes, checksum: d022b9552e24f8051aefd3e5284d93dd (MD5) / Made available in DSpace on 2018-03-21T16:56:36Z (GMT). No. of bitstreams: 1 PGCS12DA031.pdf: 1064335 bytes, checksum: d022b9552e24f8051aefd3e5284d93dd (MD5) Previous issue date: 2012-05-04 / Capes / In soils of low fertility and commonly not fertilized, it is assumed that during the development of forest species, stands they can absorb less labile forms of nutrients. This situation implies on more specific soil analysis because the classical methods estimate only the readily available nutrients, difficulting the diagnosis of soil fertility and fertilizer recommendation for forests. The objective of this study was to analyze labile and non-labile forms of carbon (C), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) of soil in forests of Pinus taeda in the first rotation (17 years of cultivation) and third rotation (49 years of continuous pine cultivation) in different soil layers up to 80 cm depth. The relative content of soil carbon in fulvic acid decreased from first to third rotation and humic acids increased from first to third rotation, indicating that with the increase of time use with forests, there is the transformation of more labile carbon in more stable forms. These results show that the total organic carbon may not be a good indicator of the changes in the soil carbon dynamics under pine forests, and that fractions of organic matter may be more reliable. With time, the moderately labile inorganic P acted as a sink of soil P, increasing its levels from first to third rotation, while the labile inorganic (Pi-Pi-RTA and NaHCO3) and labile organic (Po-NaHCO3) acted as a source of P, suggesting that the analysis of available P in soils under pine forests should take into account these fractions. The soil on older use with pine forest showed lower levels and stocks of K, Ca and Mg and non-exchangeable Ca and K. Both, P, K and Mg showed great reserve in non-labile forms that may be available in the long term, unlike Ca, which showed labile and total concentrations too low. Thus, while the available forms of P, K and Mg could be replenished by other forms of these nutrients in the soil, regardless of replenishment through fertilization, the export of Ca by wood without its replacement may drastically limit the Ca supply for next pine rotations / Em solos de baixa fertilidade e comumente não fertilizados, supõe-se que as espécies florestais podem absorver formas menos lábeis de nutrientes que são disponibilizados ao longo da rotação florestal. No entanto a avaliação desta situação é complexa, pois os métodos clássicos estimam apenas os teores prontamente disponíveis, dificultando o diagnóstico da fertilidade do solo e a definição da necessidade de adubação. O objetivo deste trabalho foi analisaros teores e estoques de diferentes formas decarbono, fósforo, potássio, cálcio e magnésio do solo em florestas de Pinus taeda L. em primeira rotação (17 anos de cultivo) e terceira rotação (49 anos de cultivo sucessivo) em diferentes camadas do solo até 80 cm de profundidade. O solo em terceira rotação teve seu conteúdo relativo de carbono em ácidos fúlvicos menor e o de ácidos húmicos maior, quando comparado à floresta em primeira rotação, indicando que com o aumento do tempo de uso com florestas há a transformação de formas mais lábeis de carbono em formas mais estáveis. Os teores totais não são bons indicadores de modificações do C na superfície do solo e as frações da matéria orgânica podem ser utilizadas para diagnosticar a dinâmica da matéria orgânica do solo em florestas de Pinus. A fração de P inorgânico moderadamente lábil (Pi-NaOH) foi 47% maior na floresta em 3ª rotação de Pinus, enquanto as frações inorgânicas lábeis (Pi-RTA e Pi-NaHCO3) e orgânicas lábeis (Po-NaHCO3) foram maiores nos solos sob primeira rotação, sugerindo a existência de uma modificação das formas de fósforo e que, diferentes formas desse nutriente podem contribuir com a disponibilidade de P em solos sob florestas de Pinus. A floresta há mais tempo cultivada com Pinus taeda apresentou menores teores e estoques de K trocável (extraído por NH4OAc.), Ca e Mg trocáveis (KCl), K não-trocável (HNO3) e de Ca semi-total (Água régia). Tanto o P como o K e Mg apresentaram grande reserva em formas não lábeis (ou não trocáveis e semitotais) que poderão vir a ser disponibilizadas em longo prazo, diferentemente do Ca, que apresentou teores lábeis e totais muito baixos. Assim, enquanto as formas disponíveis de P, K e Mg poderiam ser reabastecidas por outras formas destes nutrientes no solo, independente de reposição via fertilização, a exportação sem nenhuma reposição de Ca poderá limitar drasticamente a disponibilidade deste nutriente no solo