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Partridge, Daniel. "Inverse Modeling of Cloud – Aerosol Interactions." Doctoral thesis, Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-60454.
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The role of aerosols and clouds is one of the largest sources of uncertainty in understanding climate change. The primary scientific goal of this thesis is to improve the understanding of cloud-aerosol interactions by applying inverse modeling using Markov Chain Monte Carlo (MCMC) simulation. Through a set of synthetic tests using a pseudo-adiabatic cloud parcel model, it is shown that a self adaptive MCMC algorithm can efficiently find the correct optimal values of meteorological and aerosol physiochemical parameters for a specified droplet size distribution and determine the global sensitivity of these parameters. For an updraft velocity of 0.3 m s-1, a shift towards an increase in the relative importance of chemistry compared to the accumulation mode number concentration is shown to exist somewhere between marine (~75 cm-3) and rural continental (~450 cm-3) aerosol regimes. Examination of in-situ measurements from the Marine Stratus/Stratocumulus Experiment (MASE II) shows that for air masses with higher number concentrations of accumulation mode (Dp = 60-120 nm) particles (~450 cm-3), an accurate simulation of the measured droplet size distribution requires an accurate representation of the particle chemistry. The chemistry is relatively more important than the accumulation mode particle number concentration, and similar in importance to the particle mean radius. This result is somewhat at odds with current theory that suggests chemistry can be ignored in all except for the most polluted environments. Under anthropogenic influence, we must consider particle chemistry also in marine environments that may be deemed relatively clean. The MCMC algorithm can successfully reproduce the observed marine stratocumulus droplet size distributions. However, optimising towards the broadness of the measured droplet size distribution resulted in a discrepancy between the updraft velocity, and mean radius/geometric standard deviation of the accumulation mode. This suggests that we are missing a dynamical process in the pseudo-adiabatic cloud parcel model.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.
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Mtchedlishvili, George. "Inverse modeling of tight gas reservoirs." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:bsz:105-5595821.
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In terms of a considerable increase the quality of characterization of tight-gas reservoirs, the aim of the present thesis was (i) an accurate representation of specific conditions in a reservoir simulation model, induced after the hydraulic fracturing or as a result of the underbalanced drilling procedure and (ii) performing the history match on a basis of real field data to calibrate the generated model by identifying the main model parameters and to investigate the different physical mechanisms, e.g. multiphase flow phenomena, affecting the well production performance. Due to the complexity of hydrocarbon reservoirs and the simplified nature of the numerical model, the study of the inverse problems in the stochastic framework provides capabilities using diagnostic statistics to quantify a quality of calibration and reliability of parameter estimates. As shown in the present thesis the statistical criteria for model selection may help the modelers to determine an appropriate level of parameterization and one would like to have as good an approximation of structure of the system as the information permits.
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Yarlagadda, Rahul Rama Swamy. "Inverse Modeling: Theory and Engineering Examples." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449724104.
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Qi, Te. "Inverse modeling to predict effective leakage area." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45942.
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The purpose of this research is to develop a new approach to estimate the effective leakage area using the inverse modeling process as an alternative to the blower door test. An actual office building, which is the head quarter of Energy Efficiency Hub, was used as an example case in this study.
The main principle of the inverse modeling process is comparing the real monitor boiler gas consumption with the result calculated from the EnergyPlus model with a dynamic infiltration rate input to find the best estimation of the parameter of effective leakage area (ELA). This thesis considers only the feasibility of replacing the blower door test with the calibration approach, so rather than attempting an automated calibration process based on inverse modeling we deal with generating a first estimate and consider the role of model uncertainties that would make the proposed method less feasible.
There are five steps of the whole process. First, we need to customize our own actual weather data (AMY) needed by the energy model (EnergyPlus model), which can help increase our quality of the result. Second, create the building energy model in EnergyPlus. Third, create a multi-zone model using CONTAM with different ELA estimation of each facade to calculate the dynamic infiltration rate of each ELA estimate. Fourth, input the dynamic infiltration rate got from the CONTAM model to EnergyPlus model and output the boiler energy consumption. Fifth, compare the boiler gas consumption from the model and the real monitor data and find the best match between the two and the corresponding ELA, which gives the best estimate from the whole inverse modeling process.
From the simulation result comparison, the best estimation of the total building ELA from the inverse modeling process is the 23437cm2 at 4pa, while the result from the blower door test is 10483cm2 at 4pa. Because of the insufficient information of the building and also the uncertainty of the input parameters, the study has not led to a definite statement whether the proposed calibration of the ELA with consumption data can replace a blower door test to get an equally valid or even better ELA estimate, but it looks feasible. As this this case study is done in a deterministic context, the full feasibility test should be conducted under uncertainty. A first step towards this will talk be discussed in chapter 4.
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Shen, Jian. "Water quality modeling as an inverse problem." W&M ScholarWorks, 1996. https://scholarworks.wm.edu/etd/1539616852.
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An inverse mathematical estuarine eutrophication model has been developed. The model provides a framework to estimate unknown parameters by assimilation of the concentration data of those state variables. The inverse model developed is a laterally integrated, two-dimensional, real-time model which consists of a hydrodynamic model, an eutrophication model and an adjoint model. The hydrodynamic model provides the dynamic fields for both the eutrophication model and the adjoint model. The eutrophication model simulates eight water quality state variables which are phytoplankton, organic nitrogen, ammonium nitrogen, nitrite-nitrate nitrogen, organic phosphorus, inorganic (ortho) phosphorus, carbonaceous biochemical oxygen demand and dissolved oxygen. The adjoint model is used during the processes of parameter estimation to provide the gradients of the cost function with respect to the unknown parameters. to increase the computational efficiency and reduce computer storage space, a decoupling scheme is implemented in the inverse model, in which the kinetic processes are decoupled from the physical transport for the purpose of numerical computation. An efficient preconditioning technique is introduced in the inverse model to speed up the rate of convergence. The experiments conducted in this study provide the information of the parameter identifiability and the field data requirement for the model calibration. The model experiments with hypothetical data sets show that the parameters can be accurately estimated for short period and long period model simulations under both constant and time-varying boundary conditions. The inverse model is convergent with different initial guess parameter values and under different environments. The inverse model was successfully applied to aid calibration of the eutrophication model of the tidal Rappahannock River, Virginia. With the use of the inverse model, the eutrophication model can be calibrated efficiently and systematically. The agreement between the model predictions and observations are very satisfactory. The studies show that the inverse model is also useful in addressing the important questions of whether the estimated parameters are unique and whether the sample data are sufficient to calibrate a model. Therefore, the inverse model may also serve as a tool in helping design a field program to collect data for model calibration.
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Remy, Benjamin. "Generative modeling for weak lensing inverse problems." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASP163.
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Le lentillage gravitationnelle, qui génère un effet de déformation des images de galaxies lointaines à travers l'influence de densités de matières massives dans la ligne de visée, est très prometteur pour répondre aux questions relatives à la matière noire et à l'énergie sombre. Cet effet permet de sonder directement la distribution de matière noire dans l'Univers, qui est invisible autrement. Dans le régime où ces déformations sont faibles, il est possible de cartographier la distribution de matières projetées dans la ligne de visée, appelée carte de masse, à partir de la mesure de la déformation d'un grand nombre de galaxies. Cependant, la reconstruction de ces cartes de masse est un problème inverse qui est mal posé, à cause de données manquantes et de bruits dans le signal mesuré, et nécessite donc de l'information à priori pour être résolu. L'objectif principal de cette thèse est d'utiliser les récentes avancées sur les modèles génératifs qui permettent de modéliser des distributions complexes dans des espaces de très haute dimension. Nous proposons en particulier une nouvelle méthode pour résoudre les problème inverses de hautes dimensions et mal posés en en caractérisant la distribution a posteriori complète. En apprenant la distribution a priori à partir de de simulations cosmologiques, nous pouvons reconstruire des cartes de masses de très hautes résolution, y compris aux petites échelles, tout en en quantifiant les incertitudes associées. L'objectif principal de cette thèse est d'utiliser les récentes avancées sur les modèles génératifs qui permettent de modéliser des distributions complexes dans des espaces de très haute dimension. Nous proposons en particulier une nouvelle méthode pour résoudre les problèmes inverses de haute dimension et mal posés en en caractérisant la distribution a posteriori complète. En apprenant la distribution a priori à partir de simulations cosmologiques, nous pouvons reconstruire des cartes de masse de très haute résolution, y compris aux petites échelles, tout en en quantifiant les incertitudes associées. De plus, nous présentons une nouvelle méthode de mesure du cisaillement gravitationnel en créant un modèle décrivant les données observées au niveau des pixels. Contrairement aux méthodes standards, cette méthode ne repose pas sur la mesure d'ellipticité des galaxies et introduit donc un nouveau paradigme pour la mesure du cisaillement gravitationnel. Nous proposons en particulier un modèle hiérarchique Bayésien, avec des composantes génératives apprises et des composantes analytiques physiques. Nous montrons que cela permet de résoudre le biais de modèles dans l'estimation du cisaillement gravitationnelGravitational lensing, which is the effect of the distortion of distant galaxy images through the influence of massive matter densities in the line of sight, holds significant promise in addressing questions about dark matter and dark energy. It reflects the distribution of total matter of the Universe and is therefore a promising probe for cosmological models. In the case where these distortions are small, we call it the weak gravitational lensing regime and a straightforward mapping exists between the matter distribution projected in the line of sight, called mass-map, and the measured lensing effect. However, when attempting to reconstruct matter mass-maps under conditions involving missing data and high noise corruption, this linear inverse problem becomes ill-posed and may lack a meaningful solution without additional prior knowledge. The main objective of this thesis is to employ recent breakthroughs in the generative modeling literature that enable the modeling of complex distribution in high-dimensional spaces. We propose in particular a novel methodology to solve high-dimensional ill-posed inverse problems, characterizing the full posterior distribution of the problem. By learning the high dimensional prior from cosmological simulations, we demonstrate that we are able to reconstruct high-resolution 2D mass-maps alongside uncertainty quantification. Additionally, we present a new method for cosmic shear estimation based on forward modeling of the observation at the pixel level. This represents a new paradigm for weak lensing measurement as it does not rely on galaxy ellipticities anymore. In particular, we propose to build a hybrid generative and physical hierarchical Bayesian model and demonstrate that we can remove the source of model bias in the estimation of the cosmic shear
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Akhtar, Farhan Hussain. "Use of inverse modeling in air quality management." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37213.
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Inverse modeling has been used in the past to constrain atmospheric model parameters, particularly emission estimates, based upon ambient measurements. Here, inverse modeling is applied to air quality planning by calculating how emissions should change to achieve desired reduction in air pollutants. Specifically, emissions of nitrogen oxides (NOx = NO + NO2) are adjusted to achieve reductions in tropospheric ozone, a respiratory irritant, during an historic episode of elevated concentrations in urban Atlanta, GA. Understanding how emissions should change in aggregate without specifying discrete abatement options is particularly applicable to long-term and regional air pollution management. Using a cost/benefit approach, desired reductions in ozone concentrations are found for a future population in Atlanta, GA. The inverse method is applied to find NOx emission adjustments to reach this desired reduction in air pollution. An example of how emissions adjustments may aid the planning process in two neighborhoods is demonstrated using urban form indicators from a land use and transportation database. Implications of this method on establishing regional and market-based air quality management systems in light of recent legal decisions are also discussed. Both ozone and secondary particulate matter with diameters of less than 2.5μm (PM2.5) are formed in the atmosphere from common precursor species. Recent assessments of air quality management policies have stressed the need for pollutant abatement strategies addressing these mutual sources. The relative contribution of several important precursor species (NOx, sulfur dioxide, ammonia, and anthropogenic volatile organic compounds) to the formation of ozone and secondary PM2.5 in Atlanta during May 2007 - April 2008 is simulated using CMAQ/DDM-3D. This sensitivity analysis is then used to find adjustments in emissions of precursor species to achieve goal reductions for both ozone and secondary PM2.5 during a summertime episode of elevated concentrations. A discussion of the implications of these controls on air pollutant concentrations during the remaining year follows.
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Tang, Hui. "Forward and Inverse Modeling of Tsunami Sediment Transport." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77439.
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Tsunami is one of the most dangerous natural hazards in the coastal zone worldwide. Large tsunamis are relatively infrequent. Deposits are the only concrete evidence in the geological record with which we can determine both tsunami frequency and magnitude. Numerical modeling of sediment transport during a tsunami is important interdisciplinary research to estimate the frequency and magnitude of past events and quantitative prediction of future events. The goal of this dissertation is to develop robust, accurate, and computationally efficient models for sediment transport during a tsunami. There are two different modeling approaches (forward and inverse) to investigate sediment transport. A forward model consists of tsunami source, hydrodynamics, and sediment transport model. In this dissertation, we present one state-of-the-art forward model for Sediment TRansport In Coastal Hazard Events (STRICHE), which couples with GeoClaw and is referred to as GeoClaw-STRICHE. In an inverse model, deposit characteristics, such as grain-size distribution and thickness, are inputs to the model, and flow characteristics are outputs. We also depict one trial-and-error inverse model (TSUFLIND) and one data assimilation inverse model (TSUFLIND-EnKF) in this dissertation. All three models were validated and verified against several theoretical, experimental, and field cases.Ph. D.
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Nicot, Jean-Philippe. "Inverse modeling of subsurface environmental partitioning tracer tests /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Sadegh, Zadeh Kouroush. "Multi-scale inverse modeling in biological mass transport processes." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4123.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Biological Resources Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Pop, Eric 1975. "CMOS inverse doping profile extraction and substrate current modeling." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80565.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 95-101).
by Eric Pop.
S.B.and M.Eng.
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Zhao, Ning Ph D. Massachusetts Institute of Technology. "Reconstructing deglacial ocean ventilation using radiocarbon : data and inverse modeling." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108960.
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Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 137-149).
Significant changes occurred during the last deglaciation (roughly 10-20 thousand years (ka) before present) throughout the climate system. The ocean is a large reservoir of carbon and heat, however, its role during the deglaciation is still not well understood. In this thesis, I rely on radiocarbon measurements on fossil biogenic carbonates sampled from the seafloor to constrain deglacial ocean ventilation rates, using new data, an extensive data compilation, and inverse modeling. First, based on a sediment core that is absolutely dated from wooden remains, I argue that the deglacial ¹⁴C reservoir age of the upper East Equatorial Pacific was not very different from today. Combined with stable carbon isotope data, the results suggest that the deglacial atmospheric CO₂ rise was probably due to CO₂ released directly from the ocean (e.g., in the Southern Ocean) to the atmosphere rather than first mixed through the upper ocean. Then using a high-deposition-rate sediment core located close to deep water formation regions in the western North Atlantic, I show that compared to today, the mid-depth water production in the North Atlantic was probably stronger during the Younger Dryas cold episode, and weaker during other intervals of the late deglaciation. However, the change was not as large as suggested by previous studies. Finally, I compile published and unpublished deep ocean ¹⁴C data, and find that the ¹⁴C activity of the deep ocean mirrors that of the atmosphere during the past 25 ka. A box model of modern ocean circulation is fit to the compiled data using an inverse method. I find that the residuals of the fit can generally be explained by the data uncertainties, implying that the compiled data jointly do not provide strong evidence for basin-scale ventilation changes. Overall, this thesis suggests that, although deep ocean ventilation may have varied at some locations during the last deglaciation, the occurrence of basin-scale ventilation changes are much more difficult to be put on a firm footing. An imbalance between cosmogenic production and radioactive decay appears as the most natural explanation for the deglacial ¹⁴C activity decline observed in both the atmosphere and the deep ocean.
by Ning Zhao.
Ph. D.
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Lang, Charles WM. "Personalization Through the Application of Inverse Bayes to Student Modeling." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:16461031.
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Personalization, the idea that teaching can be tailored to each students’ needs, has been a goal for the educational enterprise for at least 2,500 years (Regian, Shute, & Shute, 2013, p.2). Recently personalization has picked up speed with the advent of mobile computing, the Internet and increases in computer processing power. These changes have begun to generate more and more information about individual students that could theoretically be used to power personalized education. The following dissertation discusses a novel algorithm for processing this data to generate estimates of individual level attributes, the Inverse Bayes Filter (IBFi).
A brief introduction to the use of Bayes Theorem is followed by a theoretical chapter and then two empirical chapters that describe alternately how the model is constructed, and how it performs on real student data. The theoretical chapter presents both the theory behind Inverse Bayes, including subjective probability, and then relates this theory to student performance. The first empirical chapter describes the prediction accuracy of IBFi on two proxies for students’ subjective probability, partial credit and cumulative average. This prediction performance is compared to the prediction accuracy of a modified Bayesian Knowledge Tracing model (KTPC) with IBFi performing reasonably, out-predicting the KTPC model on a per-student basis but not across all predictions.
In the second empirical chapter I validate the theory behind the Inverse Bayes Filter through testing whether student certainty (or confidence) improves prediction performance. The inclusion of student certainty is shown to improve the predictive performance of the model relative to models that do not use certainty. This evidence supports the IBFi model and its underlying theory, indicating that students’ judgments about their levels of certainty in their answers contains information that can be successfully identified by the model. A final summary chapter describes the consequences of using this model for education broadly.Human Development and Education
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Davis, Daniel T. "Solving inverse problems using Bayesian modeling to incorporate information sources /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/6103.
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Frandina, Peter. "VHDL modeling and synthesis of the JPEG-XR inverse transform /." Online version of thesis, 2009. http://hdl.handle.net/1850/10755.
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Morita, Lia Hanna Martins. "Degradation modeling for reliability analysis with time-dependent structure based on the inverse gaussian distribution." Universidade Federal de São Carlos, 2017. https://repositorio.ufscar.br/handle/ufscar/9120.
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Conventional reliability analysis techniques are focused on the occurrence of failures over time. However, in certain situations where the occurrence of failures is tiny or almost null, the estimation of the quantities that describe the failure process is compromised. In this context the degradation models were developed, which have as experimental data not the failure, but some quality characteristic attached to it. Degradation analysis can provide information about the components lifetime distribution without actually observing failures. In this thesis we proposed different methodologies for degradation data based on the inverse Gaussian distribution. Initially, we introduced the inverse Gaussian deterioration rate model for degradation data and a study of its asymptotic properties with simulated data. We then proposed an inverse Gaussian process model with frailty as a feasible tool to explore the influence of unobserved covariates, and a comparative study with the traditional inverse Gaussian process based on simulated data was made. We also presented a mixture inverse Gaussian process model in burn-in tests, whose main interest is to determine the burn-in time and the optimal cutoff point that screen out the weak units from the normal ones in a production row, and a misspecification study was carried out with the Wiener and gamma processes. Finally, we considered a more flexible model with a set of cutoff points, wherein the misclassification probabilities are obtained by the exact method with the bivariate inverse Gaussian distribution or an approximate method based on copula theory. The application of the methodology was based on three real datasets in the literature: the degradation of LASER components, locomotive wheels and cracks in metals.
As técnicas convencionais de análise de confiabilidade são voltadas para a ocorrência de falhas ao longo do tempo. Contudo, em determinadas situações nas quais a ocorrência de falhas é pequena ou quase nula, a estimação das quantidades que descrevem os tempos de falha fica comprometida. Neste contexto foram desenvolvidos os modelos de degradação, que possuem como dado experimental não a falha, mas sim alguma característica mensurável a ela atrelada. A análise de degradação pode fornecer informações sobre a distribuição de vida dos componentes sem realmente observar falhas. Assim, nesta tese nós propusemos diferentes metodologias para dados de degradação baseados na distribuição gaussiana inversa. Inicialmente, nós introduzimos o modelo de taxa de deterioração gaussiana inversa para dados de degradação e um estudo de suas propriedades assintóticas com dados simulados. Em seguida, nós apresentamos um modelo de processo gaussiano inverso com fragilidade considerando que a fragilidade é uma boa ferramenta para explorar a influência de covariáveis não observadas, e um estudo comparativo com o processo gaussiano inverso usual baseado em dados simulados foi realizado. Também mostramos um modelo de mistura de processos gaussianos inversos em testes de burn-in, onde o principal interesse é determinar o tempo de burn-in e o ponto de corte ótimo para separar os itens bons dos itens ruins em uma linha de produção, e foi realizado um estudo de má especificação com os processos de Wiener e gamma. Por fim, nós consideramos um modelo mais flexível com um conjunto de pontos de corte, em que as probabilidades de má classificação são estimadas através do método exato com distribuição gaussiana inversa bivariada ou em um método aproximado baseado na teoria de cópulas. A aplicação da metodologia foi realizada com três conjuntos de dados reais de degradação de componentes de LASER, rodas de locomotivas e trincas em metais.
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Maerten, Frantz. "Geomechanics to solve geological structure issues : forward, inverse and restoration modeling." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20031.
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Différentes applications de l'élasticité linéaire en géologie structurale sont présentées dans cette thèse à travers le développement de trois types de codes numériques. Le premier utilise la modélisation directe pour étudier les déplacements et champs de contraintes autour de zones faillées complexes. On montre que l'ajout de contraintes inégalitaires, telles que la friction de Coulomb, permet d'expliquer l'angle d'initiation des dominos dans les relais extensifs. L'ajout de matériaux hétérogènes et d'optimisations, telles la parallélisation sur processeurs multi-coeurs ainsi que la réduction de complexité des modèles, permettent l'étude de modèles beaucoup plus complexes. Le second type de code numérique utilise la modélisation inverse, aussi appelée estimation de paramètres. L'inversion linéaire de déplacements sur les failles ainsi que la détermination de paléo-contraintes utilisant une approche géomécanique sont développées. Le dernier type de code numérique concerne la restoration de structures complexes plissées et faillées. Il est notamment montré qu'une telle méthode permet de vérifier l'équilibre de coupes géologiques, ainsi que de retrouver la chronologie des failles. Finalement, nous montrons que ce même code permet de lisser des horizons 3D faillés, plissés et bruités en utilisant la géomécaniqueDifferent applications of linear elasticity in structural geology are presented in this thesis through the development of three types of numerical computer codes. The first one uses forward modeling to study displacement and perturbed stress fields around complexly faulted regions. We show that incorporating inequality constraints, such as static Coulomb friction, enables one to explain the angle of initiation of jogs in extensional relays. Adding heterogeneous material properties and optimizations, such as parallelization on multicore architectures and complexity reduction, admits more complex models. The second type deals with inverse modeling, also called parameter estimation. Linear slip inversion on faults with complex geometry, as well as paleo-stress inversion using a geomechanical approach, are developed. The last type of numerical computer code is dedicated to restoration of complexly folded and faulted structures. It is shown that this technique enables one to check balanced cross-sections, and also to retrieve fault chronology. Finally, we show that this code allows one to smooth noisy 3D interpreted faulted and folded horizons using geomechanics
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Zhou, Haiyan. "Stochastic Inverse Methods to Identify non-Gaussian Model Parameters in Heterogeneous Aquifers." Doctoral thesis, Universitat Politècnica de València, 2011. http://hdl.handle.net/10251/12267.
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La modelación numérica del flujo de agua subterránea y del transporte de masa se está convirtiendo en un criterio de referencia en la actualidad para la evaluación de recursos hídricos y la protección del medio ambiente. Para que las predicciones de los modelos sean fiables, estos deben de estar lo más próximo a la realidad que sea posible. Esta proximidad se adquiere con los métodos inversos, que persiguen la integración de los parámetros medidos y de los estados del sistema observados en la caracterización del acuífero. Se han propuesto varios métodos para resolver el problema inverso en las últimas décadas que se discuten en la tesis. El punto principal de esta tesis es proponer
dos métodos inversos estocásticos para la estimación de los parámetros del modelo, cuando estos no se puede describir con una distribución gausiana, por ejemplo, las conductividades hidráulicas mediante la integración de observaciones del estado del sistema, que, en general, tendrán una relación no lineal con los parámetros, por ejemplo, las alturas piezométricas.
El primer método es el filtro de Kalman de conjuntos con transformación normal (NS-EnKF) construido sobre la base del filtro de Kalman de conjuntos estándar (EnKF). El EnKF es muy utilizado como una técnica de asimilación de datos en tiempo real debido a sus ventajas, como son la eficiencia y la capacidad de cómputo para evaluar la incertidumbre del modelo. Sin embargo, se sabe que este filtro sólo trabaja de manera óptima cuándo los parámetros del modelo y las variables de estado siguen distribuciones multigausianas. Para ampliar la aplicación del EnKF a vectores de estado no gausianos, tales como los de los acuíferos en formaciones fluvio-deltaicas, el NSEnKF propone aplicar una transformación gausiana univariada. El vector de estado aumentado formado por los parámetros del modelo y las variables de estado se transforman en variables con una distribución marginal gausiana.Zhou ., H. (2011). Stochastic Inverse Methods to Identify non-Gaussian Model Parameters in Heterogeneous Aquifers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/12267
Palancia
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Arruda, Michael. "Dynamic inverse resiliant control for damaged asymmetric aircraft: Modeling and simulation." Thesis, Wichita State University, 2009. http://hdl.handle.net/10057/2513.
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This paper presents the development and simulation of a dynamic inverse resilient control (DIRC) system that can recover a general aviation aircraft that has sustained damage to a lifting surface in ight, and is now asymmetrical. A new set of di erential equations of motion for the aircraft are derived that account for the asymmetries of the aircraft and for the dynamic e ects of the shift in the center of gravity away from the original body centered axis. The typical symmetric force and moment coe cient buildup is altered to include the inuences of asymmetric lift, drag, and control deection. For the simulation, a Raytheon Bonanaza F-33C y-by-wire testbed is selected since it has been used in both ight and simulation testing for prior Wichita State University research. Geometric, mass, and aerodynamic properties for the damaged aircraft are determined with conceptual design techniques. The DIRC consists of an inverse controller with decoupled ight controls and an adaptive system to correct the command signals for a damaged aircraft. Modeling errors between the inverse control and the actual aircraft are large. Adaptive Bias Correctors, a simpli ed neural network, are applied to adapt the controller to the modeling errors between the undamaged symmetric based inverse controller and damaged asymmetric aircraft. Adaptation happens fast enough to limit the bank angle excursion and bring the aircraft back to wings level ight. Simulations are performed with a MATLAB/Simulink R and a full 6DOF model of the aircraft. Tests show that for losses to the left wing, the DIRC can recover the aircraft until the available control authority is unable to counteract the asymmetric moments.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering
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Zhang, Huai-Min Ph D. Massachusetts Institute of Technology. "Application of an inverse model in the community modeling effort results." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/58152.
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Das, Sarit Kumar. "Monitoring and Inverse Dispersion Modeling to Quantify VOCs from MSW Landfill." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/1093.
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In USA, the Municipal Solid Waste (MSW) landfills accumulate about 130 million tons of solid waste every year. A significant amount of biodegradable solid waste is converted to landfill gas due to anaerobic stabilization by bacteria. These biochemical reactions produce volatile organic compounds (VOCs) like methane and others. Due to heterogeneity in refuse composition, unpredictable distribution of favorable environmental conditions for bacterial actions and highly uncertain pathway of gases, estimation of landfill gas emission for a particular landfill is complex. However, it is important to quantify landfill gases for health risk assessment and energy recovery purposes. This research is based on the monitoring and modeling methodology proposed by researchers at University of Central Florida is reported in this thesis. River Birch Sub-title D landfill, Westwego, LA was selected as the study area. The total emission calculated using the mathematical model ran on MATLAB is comparable with the result obtained from EPA LandGEM model, using historical waste deposition records
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Shen, Yongxing. "Modeling electrostatic force microscopy and related techniques : forward and inverse problems /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Biswas, Sampurna. "Structured & learnable regularizers for modeling inverse problems in fast MRI." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6547.
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Contemporary Magnetic Resonance imaging technology has enabled structural, anatomical and functional assessment of various organ systems by allowing in-vivo visualization of those organs in terms of the biophysical parameters of the tissue. MRI still suffers from the slow image acquisition. The prolonged scan time enforces trade-offs between image quality and image acquisition time, often resulting in low spatial resolution, low signal to noise ratio, presence of artifacts resulting from patient or physiological motion. Therefore, the inverse problems that arise from MR image reconstruction tend to maximize image quality from minimally acquired signal observations. We study study the manipulation of the number of observations, based on the knowledge of the underlying image structure.
We start with studying an existing two step acquisition technique that seems to produce high quality reconstructions of dynamic MR images. We consider the recovery of a matrix X, which is simultaneously low rank and joint sparse, from few measurements of its columns using a two-step algorithm. Here, X captures a dynamic cardiac time-series. Our main contribution is to provide sufficient conditions on the measurement matrices that guarantee the recovery of such a matrix using a particular two-step algorithm. We illustrate the impact of the sampling pattern on reconstruction quality using breath held cardiac cine MRI and cardiac perfusion MRI data, while the utility of the algorithm to accelerate the acquisition is demonstrated on MR parameter mapping.
In the next study, another structure is explored, where the underlying static image is assumed to be piece-wise constant. Here, we consider the recovery of a continuous domain piecewise constant image from its non-uniform Fourier samples using a convex matrix completion algorithm. We assume the discontinuities/edges of the image are localized to the zero levelset of a bandlimited function. The proposed algorithm reformulates the recovery of the unknown Fourier coefficients as a structured low-rank matrix completion problem. We show that exact recovery is possible with high probability when the edge set of the image satisfies an incoherency property, dependent on the geometry of the edge set curve.
In the previous two studies, the acquisition time burden is manipulated by exploiting the inherent structure of the image to be recovered. We call this the self-learning strategy, where the structure is learned from the current set of measured data. Finally, we consider exemplar learning, where population generic features (structures) are learned from stored examples or training data. We introduce a novel framework to combine deep-learned priors along with complementary image regularization penalties to reconstruct free breathing and ungated cardiac MRI data from highly undersampled multi-channel measurements. This work showed the benefit in combining the deep-learned prior that exploits local and population generalizable redundancies together with self-learned priors, which capitalizes on patient specific information including cardiac and respiratory patterns. is facilitated by the proposed framework.
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Lv, Ling. "Linking Montane Soil Moisture Measurements to Evapotranspiration Using Inverse Numerical Modeling." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3323.
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The mountainous areas in the Intermountain West (IMW) of the North America are considered as the major water reservoir for the Western US. Summer evapotranspiration (ET) and soil moisture are key factors affecting the annual water yield in the montane region of the IMW. This research estimated ET of four common vegetation types (aspen, conifer, grass, and sage) and areal soil moisture in an advanced instrumentation site located at the T.W. Daniel Experimental Forest (TWDEF). Among instrumented forest research sites worldwide, TWDEF is one of a few with triplicate measures of meteorological parameters, radiation, and soil moisture within four common vegetation types in the IMW. This unique dataset enables study and understanding of the ecological and hydrological responses to climate change in Utah and the IMW region. In a second phase of this study, summer water uses from the four common vegetation types were simulated using a numerical simulation model, Hydrus-1D. The simulation was informed by soil moisture measurements at three depths (0.1 m, 0.25 m, and 0.5 m) and by ET measured from an eddy covariance tower. The results confirmed the value of numerical simulations as a viable alternate method to estimated ET where no direct ET measurements are available. It also provided comparison of water use by these vegetation species including both high and low water years. In the third phase of this study, a comparison was made between the intermediate-scale areal soil moisture measured by a Cosmic-ray neutron probe (CRNP) and the in situ TDT soil moisture network at the TWDEF site. Improved correlations were obtained, especially after shallow rainfall events, by including numerically simulated soil moisture above 0.1 m where no measurements were available. The original CRNP calibration exhibited a dry bias during spring/early summer, leading to the need for a site-specific enhanced calibration, which improved the accuracy of the CRNP soil moisture estimate at the TWDEF site.
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Zhou, Liting. "Integration of robotic inverse kinematic routines in an algorithmic 3D modeling software." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
Find full textAbstract:
An industrial manipulator equipped with an automatic clay extruder is used to realize a machine that can manufacture additively clay objects. The desired geometries are designed by means of a 3D modeling software and then sliced in a sequence of layers with the same thickness of the extruded clay section. The profiles of each layer are transformed in trajectories for the extruder and therefore for the end-effector of the manipulator.
The goal of this thesis is to improve the algorithm for the inverse kinematic resolution and the integration of the routine within the development software that controls the machine (Rhino/Grasshopper).
The kinematic model is described by homogeneous transformations, adopting the Denavit-Hartenberg standard convention. The function is implemented in C# and it has been preliminarily tested in Matlab. The outcome of this work is a substantial reduction of the computation time relative to the execution of the algorithm, which is halved.
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Nilsson, Isak. "Inverse Modeling of Biomechanical Tongue Control : From Articulation Data to Muscle Activation." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153771.
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We map real articulation data for five Swedish phonemen sequences onto parameters of a biomechanical tongue model that produces movement and muscle activations from position data. The movement produced is broadly correct and could likely be improved by a more fine tuned mapping. The muscle activations were found to vary between simulations using the same data but matched well with previous studies on muscle activity for vowels.
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Santoni, Gregory Winn. "Fluxes of Atmospheric Methane Using Novel Instruments, Field Measurements, and Inverse Modeling." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10941.
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The atmospheric concentration of methane \((CH_4)\) - the most significant non-\(CO_2\) anthropogenic long-lived greenhouse gas - stabilized between 1999 and 2006 and then began to rise again. Explanations for this behavior differ but studies agree that more measurements and better modeling are needed to reliably explain the model-data discrepancies and predict future change. This dissertation focuses on measurements of \(CH_4\) and inverse modeling of atmospheric \(CH_4\) fluxes using field measurements at a variety of spatial scales. We first present a new fast-response instrument to measure the isotopic composition of \(CH_4\) in ambient air. The instrument was used to characterize mass fluxes and isofluxes (a isotopically-weighted mass flux) from a well-studied research fen in New Hampshire. Eddy-covariance and automatic chamber techniques produced consistent estimates of both the \(CH_4\) fluxes and their isotopic composition at sub-hourly resolution. We then characterize fluxes of \(CH_4\) from aircraft engines using measurements made with the same instrument during the Alternative Aviation Fuel Experiment (AAFEX), a study that aimed to determine the atmospheric impacts of alternative fuel use in the growing aviation industry. Emissions of \(CO_2\), \(CH_4\), and \(N_2O\) from different synthetic fuels were statistically indistinguishable from those of the widely used JP-8 jet fuel. We then present airborne observations of the long-lived greenhouse gas suite – \(CO_2\), \(CH_4\), \(N_2O\), and CO – during two aircraft campaigns, HIPPO and CalNex, made using a similar instrument built specifically for the NCAR HIAPER GV aircraft. These measurements are compared to data from other onboard sensors and show excellent agreement. We discuss the details of the end-to-end calibration procedures and the data quality-assurance and quality-control (QA/QC). Lastly, we quantify a top-down estimate of California’s \(CH_4\) emission inventory using the CalNex \(CH_4\) observations. Observed \(CH_4\) enhancements above background concentrations are simulated using a lagrangian transport model driven by validated meteorology. A priori source-specific emission inventories are optimized in a Bayesian inversion framework to show that California’s \(CH_4\) budget is 1.6 ± 0.34 times larger than the current estimate of California’s Air Resources Board (CARB), the body charged with enforcing the California Global Solutions Act and tracking emission changes over time. Findings highlight large underestimates of emissions from cattle and natural gas infrastructure.Earth and Planetary Sciences
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Lee, Zachary Ka Fai 1967. "A new inverse-modeling-based technique for sub-100-nm MOSFET characterization." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9709.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 151-158).
Performance and density of VLSI circuits have been rapidly improving over the years as transistors are miniaturized. As MOSFET transistor gates are scaled to the sub- I 00 nm regime, however, subtle details of the two-dimensional (2D) and three-dimensional (3D) redistribution of dopants, due to thermal diffusion during the fabrication process, strongly determine the short channel effects, which ultimately limit device operation and performance. In order to suppress short-channel effects, extensive use of non-uniform doping profiles are found in modem devices. Among these are the super-steep retrograde (SSR) channel profile, characterized by a low dopant concentration near the surface and a high dopant concentration at some depth from the surface, and the halo doping, characterized by a laterally non-uniform doping profile across the device channel. In order to engineer a device having good short-channel characteristics and performance, through dopant engineering, the 2D dopant distribution must be known accurately. A 2D doping profile characterization technique is therefore very important. Not only should it enable device engineering, but it can also be used as a tool for process monitoring and characterization. One dimensional ( l D) profiling techniques such as the C-V method and SIMS have been widely used. Direct 2D techniques, however, have met with less success. The first goal of this thesis is to offer a solution to this problem by developing an inverse modeling- based 20 doping profile characterization technique using subthreshold 1-V characteristics that (1) does not require special test structures, (2) is able to extract 20 doping profiles of devices with very short channel-lengths, (3) is immune to parasitic capacitances and noise, (4) has low sensitivity to gate area variations, (5) has low dependence on mobility, (6) is non-destructive, and (7) uses easily obtainable data. A second goal of the thesis is to demonstrate that knowledge of the 2D distribution of dopants can be used to calibrate transport (mobility) models, leading to highly accurate predictive capabilities useful for device design. An inverse-modeling-based transport model calibration methodology is then discussed. Lastly, parasitic effects such as source/ drain series resistance, that are important for device design, and may have an impact on the accuracy in simulating high-current 1-V characteristics, are discussed and analyzed.
by Zachary K. Lee.
Ph.D.
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Neviackas, Andrew. "Inverse fire modeling to estimate the heat release rate of compartment fires." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7290.
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Thesis (M.S.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Fire Protection Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Liu, Xiang. "Identification of indoor airborne contaminant sources with probability-based inverse modeling methods." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337124.
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Williams, Derrik 1961. "Geostatistical analysis and inverse modeling of the upper Santa Cruz Basin, Arizona." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/191963.
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Data from the Upper Santa Cruz basin are analyzed to determine parameters for input into a groundwater model. The geostatistical interpolation and averaging technique of kriging are used to obtain prior estimates of log- transmissivity. These estimates are enhanced with specific-capacity data by means of regression and co-kriging. Parameters of the log- transmissivity semi-variogram model are improved using a maximum likelihood technique. Hydraulic head measurements are kriged in two ways, by universal kriging and by using an iterative generalized least squares method of semi-variogram and drift estimation. An inverse method for steady state conditions is used to estimate optimum transmissivity and mountain front recharge for modeling purposes. Input includes the prior transmissivity estimates, their covariance, and steady state head data. Results are judged on six criteria: (1) log-likelihood function, (2) head objective function, (3) mean weighted head residual, (4) mean squared weighted head residual, (5) residual coefficient of variation, and (6) a Chi-square fit. None of these criteria is sufficient to define a best estimate, but taken together, they point toward a possible optimum set of parameters.
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Shirzaei, Manoochehr. "Crustal deformation source monitoring using advanced InSAR time series and time dependent inverse modeling." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2011/5077/.
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Crustal deformation can be the result of volcanic and tectonic activity such as fault dislocation and magma intrusion. The crustal deformation may precede and/or succeed the earthquake occurrence and eruption. Mitigating the associated hazard, continuous monitoring of the crustal deformation accordingly has become an important task for geo-observatories and fast response systems. Due to highly non-linear behavior of the crustal deformation fields in time and space, which are not always measurable using conventional geodetic methods (e.g., Leveling), innovative techniques of monitoring and analysis are required.
In this thesis I describe novel methods to improve the ability for precise and accurate mapping the spatiotemporal surface deformation field using multi acquisitions of satellite radar data. Furthermore, to better understand the source of such spatiotemporal deformation fields, I present novel static and time dependent model inversion approaches. Almost any interferograms include areas where the signal decorrelates and is distorted by atmospheric delay. In this thesis I detail new analysis methods to reduce the limitations of conventional InSAR, by combining the benefits of advanced InSAR methods such as the permanent scatterer InSAR (PSI) and the small baseline subsets (SBAS) with a wavelet based data filtering scheme. This novel InSAR time series methodology is applied, for instance, to monitor the non-linear deformation processes at Hawaii Island. The radar phase change at Hawaii is found to be due to intrusions, eruptions, earthquakes and flank movement processes and superimposed by significant environmental artifacts (e.g., atmospheric). The deformation field, I obtained using the new InSAR analysis method, is in good agreement with continuous GPS data. This provides an accurate spatiotemporal deformation field at Hawaii, which allows time dependent source modeling.
Conventional source modeling methods usually deal with static deformation field, while retrieving the dynamics of the source requires more sophisticated time dependent optimization approaches. This problem I address by combining Monte Carlo based optimization approaches with a Kalman Filter, which provides the model parameters of the deformation source consistent in time. I found there are numerous deformation sources at Hawaii Island which are spatiotemporally interacting, such as volcano inflation is associated to changes in the rifting behavior, and temporally linked to silent earthquakes.
I applied these new methods to other tectonic and volcanic terrains, most of which revealing the importance of associated or coupled deformation sources. The findings are 1) the relation between deep and shallow hydrothermal and magmatic sources underneath the Campi Flegrei volcano, 2) gravity-driven deformation at Damavand volcano, 3) fault interaction associated with the 2010 Haiti earthquake, 4) independent block wise flank motion at the Hilina Fault system, Kilauea, and 5) interaction between salt diapir and the 2005 Qeshm earthquake in southern Iran.
This thesis, written in cumulative form including 9 manuscripts published or under review in peer reviewed journals, improves the techniques for InSAR time series analysis and source modeling and shows the mutual dependence between adjacent deformation sources. These findings allow more realistic estimation of the hazard associated with complex volcanic and tectonic systems.Oberflächendeformationen können eine Folge von vulkanischen und tektonischen Aktivitäten sein, wie etwa Plattenverschiebungen oder Magmaintrusion. Die Deformation der Erdkruste kann einem Erdbeben oder einem Vulkanausbruch vorausgehen und/oder folgen. Um damit drohende Gefahren für den Menschen zu verringern, ist die kontinuierliche Beobachtung von Krustendeformationen eine wichtige Aufgabe für Erdobservatorien und Fast-Responce-Systems geworden. Auf Grund des starken nicht-linearen Verhaltens von Oberflächendeformationsgebiet in Zeit und Raum, die mit konventionellen Methoden nicht immer erfasst werden (z.B., Nivellements), sind innovative Beobachtungs- und Analysetechniken erforderlich. In dieser Dissertation beschreibe ich Methoden, welche durch Mehrfachbeobachtungen der Erdoberfläche nit satellitengestützem Radar eine präzise und akkurate Abbildung der raumzeitlichen Oberflächendeformationen ermöglichen. Um die Bildung und Entwicklung von solchen raumzeitlichen Deformationsgebieten besser zu verstehen, zeige ich weiterhin neuartige Ansätze zur statischen und zeitabhängigen Modellinversion. Radar-Interferogramme weisen häufig Gebiete auf, in denen das Phasensignal dekorreliert und durch atmosphärische Laufzeitverzögerung verzerrt ist. In dieser Arbeit beschreibe ich wie Probleme des konventionellen InSAR überwunden werden können, indem fortgeschrittene InSAR-Methoden, wie das Permanent Scatterer InSAR (PSI) und Small Baseline Subsets (SBAS), mit einer Wavelet-basierten Datenfilterung verknüpft werden. Diese neuartige Analyse von InSAR Zeitreihen wird angewendet, um zum Beispiel nicht-lineare Deformationsprozesse auf Hawaii zu überwachen. Radar-Phasenänderungen, gemessen auf der Pazifikinsel, beruhen auf Magmaintrusion, Vulkaneruption, Erdbeben und Flankenbewegungsprozessen, welche durch signifikante Artefakte (z.B. atmosphärische) überlagert werden. Mit Hilfe der neuen InSAR-Analyse wurde ein Deformationsgebiet ermittelt, welches eine gute Übereinstimmung mit kontinuierlich gemessenen GPS-Daten aufweist. Auf der Grundlage eines solchen, mit hoher Genauigkeit gemessenen, raumzeitlichen Deformationsgebiets wird für Hawaii eine zeitabhängige Modellierung der Deformationsquelle ermöglicht. Konventionelle Methoden zur Modellierung von Deformationsquellen arbeiten normalerweise mit statischen Daten der Deformationsgebiete. Doch um die Dynamik einer Deformationsquelle zu untersuchen, sind hoch entwickelte zeitabhängige Optimierungsansätze notwendig. Dieses Problem bin ich durch eine Kombination von Monte-Carlo-basierten Optimierungsansätzen mit Kalman-Filtern angegangen, womit zeitlich konsistente Modellparameter der Deformationquelle gefunden werden. Ich fand auf der Insel Hawaii mehrere, raumzeitlich interagierende Deformationsquellen, etwa Vulkaninflation verknüpft mit Kluftbildungen und Veränderungen in bestehenden Klüften sowie zeitliche Korrelationen mit stillen Erdbeben. Ich wendete die neuen Methoden auf weitere tektonisch und vulkanisch aktive Gebiete an, wo häufig die eine Interaktion der Deformationsquellen nachgewiesen werden konnte und ihrer bedeutung untersucht wurde. Die untersuchten Gebiete und Deformationsquellen sind 1) tiefe und oberflächliche hydrothermale und magmatische Quellen unterhalb des Campi Flegrei Vulkans, 2) gravitationsbedingte Deformationen am Damawand Vulkan, 3) Störungsdynamik in Verbindung mit dem Haiti Beben im Jahr 2010, 4) unabhängige blockweise Flankenbewegung an der Hilina Störungszone, und 5) der Einfluss eines Salzdiapirs auf das Qeshm Erdbeben im Süd-Iran im Jahr 2005. Diese Dissertation, geschrieben als kumulative Arbeit von neun Manuskripten, welche entweder veröffentlicht oder derzeit in Begutachtung bei ‘peer-review’ Zeitschriften sind, technische Verbesserungen zur Analyse von InSAR Zeitreihen vor sowie zur Modellierung von Deformationsquellen. Sie zeigt die gegenseitige Beeinflussung von benachbarten Deformationsquellen, und sie ermöglicht, realistischere Einschätzungen von Naturgefahren, die von komplexen vulkanischen und tektonischen Systemen ausgehen.
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Xie, Xuping. "Approximate Deconvolution Reduced Order Modeling." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/78043.
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This thesis proposes a large eddy simulation reduced order model (LES-ROM) framework for the numerical simulation of realistic flows. In this LES-ROM framework, the proper orthogonal decomposition (POD) is used to define the ROM basis and a POD differential filter is used to define the large ROM structures. An approximate deconvolution (AD) approach is used to solve the ROM closure problem and develop a new AD-ROM. This AD-ROM is tested in the numerical simulation of the one-dimensional Burgers equation with a small diffusion coefficient ( ν= 10⁻³).Master of Science
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Wolf, Ailco, and Ailco Wolf. "Comprehensive geostatistical based parameter optimization and inverse modeling of North Avra Valley, Arizona." Thesis, The University of Arizona, 2002. http://hdl.handle.net/10150/626825.
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Geostatistical based optimization was applied to the North A vra Valley ground water
model to estimate the transmissivity field and boundary conditions that minimize the
difference of the modeled and measured head. The Sequential Self-Calibration (SSC)
method was used for the inverse modeling and optimization. SSC is an iterative technique
that combines geostatistics with an optimization routine to condition both transmissivity
and head fields to measured data. Two calibration methodologies were compared. In the
first, the inflow and outflow boundary conditions are adjusted to minimize head residuals,
using the uniform geometric mean transmissivity field and the subsequent SSC calibrated
transmissivity field is based on those initial boundary conditions. The second method ran
the model independent optimization software PEST in series with SSC. This approach
calibrates the inflow and outflow boundary conditions and transmissivity field iteratively
against the head residuals. As a consequence, the inflow and outflow boundary conditions
are optimized against the final geostatistical based transmissivity field used in the model.
The serial PEST-SSC calibration method produces consistently better results with respect
to head residuals, by an average of 27 .1 percent. The resulting calibrated transmissivity
fields of both methods were compared using stochastic error analysis, showing similar
results for both methods. A final model run was done employing the PEST-SSC method
for a more detailed analysis. This resulted in a relative error ( O'head residuals I head-range) of only 1.5 percent.
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Forsberg, Lars. "On the Normal Inverse Gaussian Distribution in Modeling Volatility in the Financial Markets." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2002. http://publications.uu.se/theses/91-554-5298-1/.
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Zhang, Yonggen, Marcel G. Schaap, Alberto Guadagnini, and Shlomo P. Neuman. "Inverse modeling of unsaturated flow using clusters of soil texture and pedotransfer functions." AMER GEOPHYSICAL UNION, 2016. http://hdl.handle.net/10150/622504.
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Characterization of heterogeneous soil hydraulic parameters of deep vadose zones is often difficult and expensive, making it necessary to rely on other sources of information. Pedotransfer functions (PTFs) based on soil texture data constitute a simple alternative to inverse hydraulic parameter estimation, but their accuracy is often modest. Inverse modeling entails a compromise between detailed description of subsurface heterogeneity and the need to restrict the number of parameters. We propose two methods of parameterizing vadose zone hydraulic properties using a combination of k-means clustering of kriged soil texture data, PTFs, and model inversion. One approach entails homogeneous and the other heterogeneous clusters. Clusters may include subdomains of the computational grid that need not be contiguous in space. The first approach homogenizes within-cluster variability into initial hydraulic parameter estimates that are subsequently optimized by inversion. The second approach maintains heterogeneity through multiplication of each spatially varying initial hydraulic parameter by a scale factor, estimated a posteriori through inversion. This allows preserving heterogeneity without introducing a large number of adjustable parameters. We use each approach to simulate a 95 day infiltration experiment in unsaturated layered sediments at a semiarid site near Phoenix, Arizona, over an area of 50 x 50 m(2) down to a depth of 14.5 m. Results show that both clustering approaches improve simulated moisture contents considerably in comparison to those based solely on PTF estimates. Our calibrated models are validated against data from a subsequent 295 day infiltration experiment at the site.
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Fu, Jianlin. "A markov chain monte carlo method for inverse stochastic modeling and uncertainty assessment." Doctoral thesis, Universitat Politècnica de València, 2008. http://hdl.handle.net/10251/1969.
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Unlike the traditional two-stage methods, a conditional and inverse-conditional simulation approach may directly generate independent, identically distributed realizations to honor both static data and state data in one step. The Markov chain Monte Carlo (McMC) method was proved a powerful tool to perform such type of stochastic simulation. One of the main advantages of the McMC over the traditional sensitivity-based optimization methods to inverse problems is its power, flexibility and well-posedness in incorporating observation data from different sources. In this work, an improved version of the McMC method is presented to perform the stochastic simulation of reservoirs and aquifers in the framework of multi-Gaussian geostatistics.
First, a blocking scheme is proposed to overcome the limitations of the classic single-component Metropolis-Hastings-type McMC. One of the main characteristics of the blocking McMC (BMcMC) scheme is that, depending on the inconsistence between the prior model and the reality, it can preserve the prior spatial structure and statistics as users specified. At the same time, it improves the mixing of the Markov chain and hence enhances the computational efficiency of the McMC. Furthermore, the exploration ability and the mixing speed of McMC are efficiently improved by coupling the multiscale proposals, i.e., the coupled multiscale McMC method. In order to make the BMcMC method capable of dealing with the high-dimensional cases, a multi-scale scheme is introduced to accelerate the computation of the likelihood which greatly improves the computational efficiency of the McMC due to the fact that most of the computational efforts are spent on the forward simulations. To this end, a flexible-grid full-tensor finite-difference simulator, which is widely compatible with the outputs from various upscaling subroutines, is developed to solve the flow equations and a constant-displacement random-walk
particle-tracking method, which enhances the comFu, J. (2008). A markov chain monte carlo method for inverse stochastic modeling and uncertainty assessment [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1969
Palancia
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Li, Liangping. "Upscaling and Inverse Modeling of Groundwater Flow and Mass Transport in Heterogeneous Aquifers." Doctoral thesis, Universitat Politècnica de València, 2011. http://hdl.handle.net/10251/12268.
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Dividimos el trabajo en tres bloques:
En el primer bloque, se han revisado las técnicas de escalado que utilizan una media simple, el método laplaciano simple, el laplaciano con piel y el escalado con mallado no uniforme y se han evaluado en un ejercicio tridimensional de escalado de la conductividad hidráulica. El campo usado como referencia es una realización condicional a escala fina de la conductividad hidráulica del experimento de macrodispersión realizado en la base de la fuerza aérea estadounidense de Columbus en Misuri (MADE en su acrónimo inglés). El objetivo de esta sección es doble, primero, comparar la efectividad de diferentes técnicas de escalado para producir modelos capaces de reproducir el comportamiento observado del movimiento del penacho de tritio, y segundo, demostrar y analizar las condiciones bajo las cuales el escalado puede proporcionar un modelo a una escala gruesa en el que el flujo y el transporte puedan predecirse con al ecuación de advección-dispersión en condiciones aparentemente no fickianas. En otros casos, se observa que la discrepancia en la predicción del transporte entre las dos escalas persiste, y la ecuación de advección-dispersión no es suficiente para explicar el transporte en la escala gruesa. Por esta razón, se ha desarrollado una metodología para el escalado del transporte en formaciones muy heterogéneas en tres dimensiones. El método propuesto se basa en un escalado de la conductividad hidráulica por el método laplaciano con piel y centrado en los interbloques, seguido de un escalado de los parámetros de transporte que requiere la inclusión de un proceso de transporte con transferencia de masa multitasa para compensar la pérdida de heterogeneidad inherente al cambio de escala. El método propuesto no sólo reproduce el flujo y el transporte en la escala gruesa, sino que reproduce también la incertidumbre asociada con las predicciones según puede observarse analizando la variabilidad del conjunto de curvas de llegada.Li ., L. (2011). Upscaling and Inverse Modeling of Groundwater Flow and Mass Transport in Heterogeneous Aquifers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/12268
Palancia
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Izumi, Tomoki. "Inverse Modeling of Variably Saturated Subsurface Water Flow in Isothermal/Non-isothermal Soil." Kyoto University, 2012. http://hdl.handle.net/2433/157730.
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Kyoto University (京都大学)0048
新制・論文博士
博士(農学)
乙第12659号
論農博第2766号
新制||農||1003(附属図書館)
学位論文||H24||N4700(農学部図書室)
29737
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 河地 利彦, 教授 村上 章, 教授 川島 茂人
学位規則第4条第2項該当
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Oevelen, Johannes van. "The structure of marine benthic food webs: combining stable isotope techniques and inverse modeling." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/291113869.
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Djomehri, Ihsan Jahed 1976. "Comprehensive inverse modeling for the study of carrier transport models in sub-50nm MOSFETs." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8011.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 123-129).
Direct quantitative 2-D characterization of sub-50 nm MOSFETs continues to be elusive. This research develops a comprehensive indirect inverse modeling technique for extracting 2-D device topology using combined log(I)-V and C-V data. An optimization loop minimizes the error between a broad range of simulated and measured electrical characteristics by adjusting parameterized profiles. The extracted profiles are reliable in that they exhibit decreased RMS error as the doping parameterization becomes increasingly comprehensive of doping features. The inverse modeling methodology pieces together complementary MOSFET data sets such as capacitance of the gate stack, 1-D doping analysis, subthreshold I-V which is a strong function of 2-D doping, and C-V data which is especially sensitive to the source/drain. Combining the data sets enhances the extracted profiles. Such profiles serve as a basis for tuning diffusion coefficients in order to realistically calibrate modern process simulators.
(cont.) The important application of this technique is in the calibration of carrier transport models. With an accurate device topology, the transport model parameters can be adjusted to predict the onstate behavior. Utilizing a mobility model that conforms to the experimental effective field dependence and including a correction for parasitic resistance, the transport model for an advanced NMOS generation at various gate lengths and voltages is calibrated. Employing the Energy Balance model yields an energy relaxation value valid over all devices examined in this work. Furthermore, what has been learned from profile and transport calibration is used in investigating optimal paths for sub-20 nm MOSFET scaling. In a study of candidate architectures such as double-gate, single-gate, and bulk-Si, metrics for the power versus performance trade-off were developed. To conclude, the best trade-off was observed by scaling as a function of gate length with a single near-mid-gap workfunction.
by Ihsan J. Djomehri.
Ph.D.
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Pacitti, Arnaud. "Nonlinear modeling of elastic cables : experimental data-based tension identification via static inverse problem." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1142/document.
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La connaissance de la tension dans les câbles de pont est un élément de diagnostic important, tant à l'échelle du câble qu'à celle de l'ouvrage dont il fait partie.Le présent travail de thèse propose une méthode d'évaluation de la tension parméthode inverse à partir d'une formulation variationnelle mixte de câble géométriquement exact permettant de coupler simplement et à bas coût un modèle universel de câble et des capteurs d'utilisation courante tels que des jauges de déformation et des capteurs de déplacement. Contrairement à de nombreuses méthodes existantes, la méthode pésentée ne nécessite pas une connaissance fine des paramètres du câble pour évaluer sa tension.Les choix de modélisation faits sont motivés par une étude approfondie des différentes typologies des câbles présents sur ouvrage et par une étude bibliographique qui tente de synthétiser l'immense littérature disponible dans le domaine des câbles. La modélisation retenue est issue de la théorie des lignes déformables des frères Cosserat, dont nous présentons les variantes avec et sans rigidité de flexion.Les moyens d'essai utilisés pour la validation expérimentale de la méthode mise au point ont été conçus et réalisés au cours du présent travail. Le montage expérimental imaginé permet d'appliquer la méthode inverse sur un câble montoron multicouches de 21 m de long et 22 mm de diamètre. Les essais sont réalisés à 6 différents niveaux de tension échelonnés par paliers de 30 kN de 55 kN à 205 kN. Ils montrent l'efficacité de la méthode sur le câble testé et la pertinence de son déploiement à venir sur d'autres typologies de câblesKnowledge of the tension in bridge cables is important not only to diagnostic the cable itself but also the construction it belongs to.The work presented in this thesis proposes to evaluate the tension of a geometrically exact cable using a static inverse method from a mixed variational formulation, by coupling simply and cheaply a universal cable model with usual sensors, such as displacement sensors and strain gauges. Contrarily to existing methods, a good knowledge of the cable's parameters, such as it length or weight per unit length, is not required.Combining a thorough study of various cable typologies encountered on bridges and the vast amounts of material available in the bibliography covering cables, lead to the modeling following the elastic theory of rods developed by the Cosserat brothers, François and Eugène, elaborating on their theory of rods with and without flexural stiffness.The experimental apparatus, designed and built in the course of this study, allowed to successfully validate the developed inverse method on a multilayered strand cable 21 m long and 22 mm in diameter at several tension levels. The universal aspect of the model introduced and its successful validation encourages its implementation to other cable typologies
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Osorio, Murillo Carlos Andres. "Design and Implementation of an Inverse Modeling Framework Using the Method of Anchored Distributions." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4339.
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Estimation of spatial random fields (SRFs) such as transmissivity or porosity is required for predicting groundwater flow and subsurface contaminant movement. Similarly, distributed parameter fields such as terrain roughness and evapotranspiration coefficients are required by other areas of environmental and earth sciences modeling. This dissertation presents an inverse modeling framework for characterizing SRFs called MAD#, which is an end-user software implementation of the Bayesian inverse modeling technique Method of Anchored Distributions (MAD). The MAD# framework allows modelers to “wrap” existing simulation modeling tools using an extensible driver architecture that exposes model parameters to the inversion engine. A compelling aspect of this model wrapping approach is that it does not require end-users to modify model configuration files; rather the model driver manages dynamic changes to model input and configuration files at run time. The MAD# framework is implemented in an open source software package with the goal of significantly lowering the barrier to using inverse modeling in education, research, and resource management. Toward this end, we introduce and test an intentionally simple user interface for simulation configuration, model driver integration, spatial domain and model output visualization, and evaluation of model convergence.
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Tixier, Eliott. "Variability modeling and numerical biomarkers design in cardiac electrophysiology." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066325/document.
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Cette thèse de doctorat est consacrée à l'étude de la variabilité observée dans les mesures d'électrophysiologie (i.e. l'activité électrique des tissus biologiques) cardiaque et à la conception de biomarqueurs numériques extraits de ces mesures. Les applications potentielles sont nombreuses, pouvant aller d'une meilleure compréhension des modèles électrophysiologiques existants à l'évaluations des effets nocifs de médicaments en passant par le diagnostic de pathologies cardiaques. Les modèles d'électrophysiologie cardiaque présentés dans ce travail sont, soit des équations différentielles ordinaires (EDOs), soit des équations aux dérivées partielles (EDPs), selon qu'ils concernent l'échelle cellulaire ou l'échelle du tissu. Dans les deux cas, ces modèles sont hautement non linéaires et nécessitent d'intenses ressources computationnelles. Nous adoptons l'approche suivante : de prime abord, nous développons des outils numériques afin de répondre à des problèmes généraux, au-delà de l'électrophysiologie. Puis, nous appliquons ces outils à des mesures synthétiques d'électrophysiologie dans différents scénarios réalistes et, lorsque cela est possible, à des mesures expérimentales. Dans la première partie de cette thèse, nous présentons une méthode générale pour estimer la densité de probabilité de paramètres incertains de modèles basés sur des EDOs ou des EDPs. La méthode est non intrusive et repose sur des évaluations "hors-ligne" du modèle direct, ce qui la rend en pratique computationellement moins dispendieuse que d'autres approches plus sophistiquées. La méthode est illustrée avec des mesures synthétiques et expérimentales d'électrophysiologie. Dans la seconde partie de cette thèse, nous présentons une méthode de sélectionde biomarqueurs à partir des sorties de modèles en vue d'effectuer des tâches de classification ou de résoudre des problèmes d'estimation de paramètres. La méthode repose sur la résolution d'un problème d'optimisation creux. La méthode est illustrée avec des modèles simples et ensuite appliquée à des mesures synthétiques, incluant des enregistrements d'électrocardiogramme, et à des données expérimentales obtenues à partir de mesures de matrices de microélectrodesThis PhD thesis is dedicated to the study of the variability observed in cardiac electrophysiology (i.e. the electrical activity of biological tissues) measurements and to the design of numerical biomarkers extracted from these measurements. The potential applications are numerous, ranging from a better understanding of existing electrophysiology models to the assessment of adverse effects of drugs or the diagnosis of cardiac pathologies. The cardiac electrophysiology models considered in the present work are either ODEs or PDEs depending on whether we focus on the cell scale or the tissue scale. In both cases, these models are highly non-linear and computationally intensive. We proceed as follows: first we develop numerical tools that address general issues and that are applicable beyond the scope of cardiac electrophysiology. Then, we apply those tools to synthetic electrophysiology measurements in various realistic scenarios and, when available, to real experimental data. In the first part of this thesis, we present a general method for estimating the probability density function (PDF) of uncertain parameters of models based on ordinary differential equations (ODEs) or partial differential equations (PDEs). The method is non-instrusive and relies on offline evaluations of the forward model, making it computationally cheap in practice compared to more sophisticated approaches. The method is illustrated with generic PDE and ODE models. It is then applied to synthetic and experimental electrophysiology measurements. In the second part of this thesis, we present a method to extract and select biomarkers from models outputs in view of performing classication tasks or solving parameter identification problems. The method relies on the resolution of a sparse optimization problem. The method is illustrated with simple models and then applied to synthetic measurements, including electrocardiogram recordings, and to experimental data obtained from micro-electrode array measurements
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Hu, Rongjing. "Molecular modeling studies of HIV-1 reverse transcriptase and some of its inhibitors." Paris 7, 2009. http://www.theses.fr/2009PA077050.
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Ce travail est consacré à la modélisation des interactions entre la transcriptase inverse du HIV-1 et quelques-uns de ses inhibiteurs. Dans un premier temps, les méthodes de corrélation structure-activité (QSAR 2D) sont comparées et permettent de sélectionner les méthodes non linéaires comme SVM ou PPR. Le docking moléculaire est ensuite employé pour préciser la conformation des inhibiteurs en interaction avec leur récepteur. Ceci permet de réaliser des études QSAR 3D qui tiennent compte de la véritable conformation des inhibiteurs en interaction avec la protéine. Ces études permettent de préciser les facteurs structuraux et chimiques (position, taille, hydrophobicité des substituants, liaisons H,. . ) favorables à l'activité. La dynamique moléculaire permet quant à elle de préciser les types d'interaction (Van der Waals, électrostatiques, liaisons H,. . . ) protéine-inhibiteur et de calculer les énergies d'interaction. On montre que ces dernières sont corrélées à l'activitéThis work is devoted to modelling the interactions between HIV-1 reverse transcriptase and some of its inhibitors. First, structure-activity (QSAR 2D) correlation techniques are compared. This permits selecting non linear methods such as SVM or PPR. Molecular docking is then performed to determine the precise conformation of inhibitors when interacting with the receptor. This allows carrying out QSAR 3D studies taking into account the real conformation of the inhibitors interacting with the protein. These studies yield new information relative to structural and chemical factors (location, size, hydrophobicity of the substituents, H-bonding,. . ) favourable to activity. Molecular dynamics brings still more precise date relative to the different protein-inhibitor interaction types (Van der Waals, electrostatic, H-bonds) and to determine the interaction energies. It is shown that they are correlated with bioactivity
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Sakimoto, Takahiro. "Étude de fracture inverse pendant les essais DWTT." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM081.
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Pour les gazoducs, la résistance à la propagation ductile est reliée à la fraction surfacique de “shear area” mesurée dans l’essai Drop Weight Tear Test (DWTT). Récemment, un mode de rupture “inverse” a parfois été observé sur les éprouvettes DWTT dans cas d’aciers ayant une énergie Charpy très élevée. Ceci est un problème car la résistance à la propagation fragile est alors sous-estimée dans la cas d’aciers à haute ténacité. Une procédure pour évaluer l’effet de la rupture inverse manque encore. De plus, le mécanisme conduisant à la rupture inverse n’a pas été expliqué en détail. Il est donc important de développer des modèles de simulations permettant d’interpréter les essais DWTT présentant une rupture “inverse”. Cette étude vise à proposer un modèle de rupture pour l’essai DWTT représentant la rupture ductile en biseau ainsi que la rupture fragile. Cette étude comprend : (i) une modèle de plasticité anisotrope, (ii) une simulation de la rupture en biseau, (iii) un modèle de transition ductile—fragile. Bien décrire la plasticité est nécessaire pour bien estimer les contraintes et déformations dans la zone de fissuration. La rupture ductile est représentée avec un modèle GTN incluant un terme de germination dépendent du paramètre de Lode. La rupture fragile est étudiée avec le modèle de Beremin appliqué après simulation de la rupture ductile. A la lumière de cette simulation, il est possible de mieux comprendre l’essai DWTT. Ces résultats seront utiles pour promouvoir l’emploi des aciers à haute ténacité pour les gazoducs sous haute pressionFor the gas line-pipe, resistance to brittle fracture propagation is related to shear area fraction measured in Drop Weight Tear Test (DWTT). Recently, “so-called” inverse fracture is sometimes observed in DWTT specimens for line-pipe with high Charpy absorbed energy. The main problem of the inverse fracture is that the resistance to brittle fracture propagation is underestimated in case of high toughness steels. However, the rational guidelines to evaluate the effect of inverse fracture are still missing. Moreover, the mechanism of inverse fracture has not yet been clarified in details. It is important to establish the simulation models representing the DWTT fracture surface to clarify the mechanisms of inverse fracture. This study aims at the simulation model representing the slant ductile fracture and ductile to brittle transition during DWTT. The study includes the description of: (i) the anisotropic plastic behavior, (ii) slant ductile behavior and (iii) ductile to brittle transition behavior. The description of anisotropic plastic behavior is needed to be able to precisely estimate strains and stresses within the structures. The slant ductile fracture behavior is numerically investigated by using the GTN model with additional secondary void nucleation. The brittle fracture is studied by extending the Beremin model to brittle fracture initiation after slant ductile fracture. This study discusses the mechanism of inverse fracture during DWTT from these simulation results. This research results will be helpful to be able to use high toughness steels for natural gas line-pipes with high pressure transmission
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Inforsato, Leonardo. "Determinação das propriedades hidráulicas do solo pelo método de evaporação monitorada por atenuação de radiação gama." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/64/64134/tde-12112018-141229/.
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Modelos matemáticos são comumente utilizados no estudo da dinâmica da água no solo não-saturado. A principal equação para se quantificar esta dinâmica é a equação diferencial de Richards. Sua solução direta é impossível na maioria dos casos, necessitando de métodos numéricos, dos quais se destaca a utilização das funções de condutividade e de retenção de água de Van Genuchten - Mualem para obtenção da solução numérica. Diante disto, o objetivo deste trabalho foi apresentar um novo método para a obtenção dos parâmetros de Van Genuchten - Mualem, que utiliza a modelagem inversa de dados de teores de água medidos periodicamente e obtidos por experimento de evaporação assistido por atenuação de radiação gama, para a modelagem inversa foi utilizado o software Hydrus-1D. O método foi testado em amostras com diferentes texturas, colhidas em 11 localidades na região de Piracicaba-SP. Dos conjuntos de exemplares analisados, apenas um apresentou resultado insatisfatório, concluindo que o método é válidoMathematical models are commonly used in studies of water dynamics in unsaturated soil. The main equation to quantify water the dynamics is the differential Richards equation. Its analytical solution is impossible in almost all cases, requiring numerical methods, among which the Van Genuchten - Mualem water conductivity and water retention functions are frequently used to obtain the numerical solution. The objective of this work is to present a new method to obtain the Van Genuchten - Mualem parameters, using the inverse modeling of water content data measured periodically by gamma radiation attenuation in evaporating samples. Hydrus-1D software was used for the inverse modeling. The method was tested in samples with different textures, collected in 11 locations in the region of Piracicaba, state of São Paulo, Brazil. Of the sets of samples analyzed, only one presented an unsatisfactory result, concluding that the method is valid
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Moberg, Stig. "Modeling and Control of Flexible Manipulators." Doctoral thesis, Linköpings universitet, Reglerteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-60831.
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Industrial robot manipulators are general-purpose machines used for industrial automation in order to increase productivity, flexibility, and product quality. Other reasons for using industrial robots are cost saving, and elimination of hazardous and unpleasant work. Robot motion control is a key competence for robot manufacturers, and the current development is focused on increasing the robot performance, reducing the robot cost, improving safety, and introducing new functionalities. Therefore, there is a need to continuously improve the mathematical models and control methods in order to fulfil conflicting requirements, such as increased performance of a weight-reduced robot, with lower mechanical stiffness and more complicated vibration modes. One reason for this development of the robot mechanical structure is of course cost-reduction, but other benefits are also obtained, such as lower environmental impact, lower power consumption, improved dexterity, and higher safety. This thesis deals with different aspects of modeling and control of flexible, i.e., elastic, manipulators. For an accurate description of a modern industrial manipulator, this thesis shows that the traditional flexible joint model, described in literature, is not sufficient. An improved model where the elasticity is described by a number of localized multidimensional spring-damper pairs is therefore proposed. This model is called the extended flexible joint model. The main contributions of this work are the design and analysis of identification methods, and of inverse dynamics control methods, for the extended flexible joint model. The proposed identification method is a frequency-domain non-linear gray-box method, which is evaluated by the identification of a modern six-axes robot manipulator. The identified model gives a good description of the global behavior of this robot. The inverse dynamics problem is discussed, and a solution methodology is proposed. This methodology is based on the solution of a differential algebraic equation (DAE). The inverse dynamics solution is then used for feedforward control of both a simulated manipulator and of a real robot manipulator. The last part of this work concerns feedback control. First, a model-based nonlinear feedback control (feedback linearization) is evaluated and compared to a model-based feedforward control algorithm. Finally, two benchmark problems for robust feedback control of a flexible manipulator are presented and some proposed solutions are analyzed.
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Xu, Dongbo [Verfasser], and Andreas [Gutachter] Erdmann. "Inverse Image Modeling for Defect Detection and Optical System Characterization / Dongbo Xu ; Gutachter: Andreas Erdmann." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2016. http://d-nb.info/1120120608/34.
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Bedida, Kirthi. "AN APPROACH TO INVERSE MODELING THROUGH THE INTEGRATION OF ARTIFICIAL NEURAL NETWORKS AND GENETIC ALGORITHMS." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/493.
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A hybrid model integrating predictive capabilities of Artificial Neural Network (ANN) and optimization feature of Genetic Algorithm (GA) is developed for the purpose of inverse modeling. The proposed approach is applied to Superplastic forming of materials to predict the material properties which characterize the performance of a material. The study is carried out on two problems. For the first problem, ANN is trained to predict the strain rate sensitivity index m given the temperature and the strain rate. The performance of different gradient search methods used in training the ANN model is demonstrated. Similar approach is used for the second problem. The objective of which is to predict the input parameters, i.e. strain rate and temperature corresponding to a given flow stress value. An attempt to address one of the major drawbacks of ANN, which is the black box behavior of the model, is made by collecting information about the weights and biases used in training and formulating a mathematical expression. The results from the two problems are compared to the experimental data and validated. The results indicated proximity to the experimental data.