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Hebeler, Felix. "Modelling topographic uncertainty : impacts on large scale : environmental modelling /." Zürich, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000253809.
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López, Martinez Carlos. "Multidimensional speckle noise. Modelling and filtering related to sar data." Doctoral thesis, Universitat Politècnica de Catalunya, 2003. http://hdl.handle.net/10803/6921.
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Los Radares de Apertura Sintética, o sistemas SAR, representan el mejorejemplo de sistemas activos de teledetección por microondas. Debido a su naturaleza coherente, un sistema SAR es capaz de adquirir información dedispersión electromagnética con una alta resolución espacial, pero por otro lado, esta naturaleza coherente provoca también la aparición de speckle.A pesar de que el speckle es una medida electromagnética, sólo puede ser analizada como una componente de ruido debido a la complejidad asociadacon el proceso de dispersión electromagnética.Para eliminar los efectos del ruido speckle adecuadamente, es necesario un modelo de ruido, capaz de identificar las fuentes de ruido y como éstasdegradan la información útil. Mientras que este modelo existe para sistemasSAR unidimensionales, conocido como modelo de ruido speckle multiplicativo,éste no existe en el caso de sistemas SAR multidimensionales.El trabajo presentado en esta tesis presenta la definición y completa validación de nuevos modelos de ruido speckle para sistemas SAR multidimensionales,junto con su aplicación para la reducción de ruido speckle y la extracción de información.En esta tesis, los datos SAR multidimensionales, se consideran bajo una formulación basada en la matriz de covarianza, ya que permite el análisisde datos sobre la base del producto complejo Hermítico de pares de imágenesSAR. Debido a que el mantenimiento de la resolución especial es un aspectoimportante del procesado de imágenes SAR, la reducción de ruido speckleestá basada, en este trabajo, en la teoría de análisis wavelet.
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Darling, Paul Simon. "SAR modelling for ecological applications." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297315.
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Sun, Tianhua. "Modelling an SBR waste treatment system." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10330.
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The sequencing batch reactor (SBR), developed from batch reactor technology, has made significant progress in the past two decades with increasing use in wastewater treatment. However, there are still some important aspects of the system that need improvement. Modelling SBR system, developing lab methods for estimation of the model parameters, re-defining SBR design parameters and comparing SBR and continuous flow stirred tank reactor (CFSTR) systems were the four objectives of this thesis. Previous SBR models cannot predict an entire SBR operation cycle because they have some obvious deficiencies. No consideration of soluble microbial products (SMP) by the models is one of the deficiencies. These deficiencies were carefully reviewed and discussed before beginning the modelling work. A new mathematical model based on the standard Lawrence and McCarty model and IAWPRC model No. 1 has been developed for the SBR activated sludge system. In contrast with previous SBR models, the most important developments of the new model are involving expressions for SMP formed from substrate metabolism and released from activated sludge decay and classifying different basic chemical oxygen demand (COD) categories based on their biodegradabilities. In the new SBR model, total COD is divided into two parts: soluble and insoluble. The soluble part is further subdivided into easy-to-biodegrade substrate (EBS), difficult-to-biodegrade substrate (DBS) and biologically inert organic materials (IOM). The classification of COD makes it possible to describe the degradation process of organic substances more precisely. Quantitative batch test methods for the classification of the substrate have been devised to aid in characterizing and developing the coefficient values of the new SBR model. The batch test techniques were employed for measuring the three different (EBS, DBS and IOM) soluble COD fractions in the influent as well as the formation or release of these three types of substances from metabolism and sludge decay. The kinetic constants of the new model can also be estimated by the techniques. It was found that EBS degradation followed Monod kinetics and DBS degradation followed first-order kinetics. It was also found that the soluble COD released from substrate metabolism is closely related to the type of substrate degraded while the soluble COD released from activated sludge decay is not. (Abstract shortened by UMI.)
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Grover, Kevin Grover. "Studying forestry in Brazilian Amazonia using synthetic aperture radar." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387755.
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Engström, Iris. "Steady-state hydrogeological modelling in order to investigate groundwater sensitivity." Thesis, KTH, Mark- och vattenteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171824.
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Growing regions and tighter zoning in urban areas are pushing the hydrological bal-ances to establish new equilibriums which are causing a stress on the groundwater. Urbanization can affect the groundwater in several ways in which both raising and lowering of groundwater tables are a possibility. Both ways, sudden changes may bring on socioeconomic costs for the unprepared. Hydrogeological modelling creates the possibilities to visualise processes that cannot be seen with the naked eye. By combin-ing knowledge about the studied area from tests and measurements a conceptual model and additionally a numerical model can be created. To study the magnitude groundwater sensitivity to changes in land-cover a hydrogeological model was created using COMSOL multiphysics within the frame of a case study concerning a horse racetrack located in Täby, north of Stockholm. The model was calibrated against known data and was the applied on a future scenario where both the land-use and climate were changed. The outcome of the model showed that hydrogeological mod-elling is sensitive to the amount and quality of the in-data. Several insecurities in the results can be traced back to a lack of base material and by changing one parameter the result of other calibrated parameters would also change. Equifinality could thus be established to be a major issue when performing groundwater modelling. Further studies of relevant data requirements for different model objectives are required.
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Achermann, David. "Modelling, simulation and optimization of maintenance strategies under consideration of logistic processes /." Zürich : ETH, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000259627.
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Fournier, Mathew. "Investigations into the Shear Strength Reduction method using distinct element models." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2492.
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This thesis reports a detailed investigation into the use of the Shear Strength Reduction (SSR) method to determine factor of safety values in discontinuum models using the Universal Distinct Element Code. The SSR method depends on the definition of failure within the model and two different criteria were compared: the numerical unbalanced force definition and a more qualitative displacement-monitoring based method. A parametric study was first undertaken, using a simple homogeneous rock slope, with three different joint networks representing common kinematic states. Lessons learned from this study were then applied to a more complex case history used for validation of the SSR method.
The discontinuum models allow for the failure surface to propagate based on constitutive models that better idealize the rockmass than simpler methods such as limit equilibrium (e.g. either method of slices or wedge solutions) and even numerical continuum models (e.g. finite difference, finite element). Joints are explicitly modelled and can exert a range of influences on the SSR result. Simple elasto-plastic models are used for both the intact rock and joint properties. Strain-softening models are also discussed with respect to the SSR method. The results presented highlight several important relationships to consider related to both numerical procedures and numerical input parameters.
The case history was modelled similar to how a typical forward analysis would be undertaken: i.e. simple models with complexities added incrementally. The results for this case generally depict a rotational failure mode with a reduced factor of safety due to the presence of joints within the rockmass when compared to a traditional limit equilibrium analysis. Some models with large persistence of steeply dipping joints were able to capture the actual failure surface. Softening models were employed in order to mimic the generation and propagation of joints through the rockmass in a continuum; however, only discontinuum models using explicitly defined joints in the model were able to capture the correct failure surface.
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Kajaman, Aboajela. "Modelling and control of an activated sludge process using ASM2d and taking into account sludge floc distribution effects." Thesis, De Montfort University, 2015. http://hdl.handle.net/2086/11422.
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To reduce energy consumption, and to achieve the desired denitrification, the activated sludge process sometimes needs to operate at low dissolved oxygen concentrations. The ASM2d model describes the activated sludge process, if nitrification and denitrification occur during different phases in a sequencing batch reactor (SBR). Despite the widespread study of enhanced biological phosphorous removal, comprehensive sludge floc distribution model remains lacking that would better describe this process. Consequently, the integrated system model has been developed to understand the impact of floc at low DO concentrations, and during the process of biological nitrogen and phosphorous removal. In a wastewater treatment plant used in this study, the dissolved oxygen was controlled at a low concentration, 1.7〖gO_2 m〗^(-3), and the dispersion coefficient into the floc was found to be 〖D=1.2×10〗^(-4) m^2/day. Introduction of a number of effectiveness factors contributed to the development of the ASM2d model described herein. This developed model could be valuable for predicting process behaviours applicable under various configurations. Moreover, parameters and effectiveness factors for the model could be calibrated using a genetic algorithm approach. Optimisation was then achieved by controlling the solids retention time during the activated sludge process.
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Cochrane, Christopher Gordon. "Topographic modelling from SAR imagery of impact craters on Venus." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/11454.
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Tian, Xinna. "Study on mixing, modelling and control of an SCR system." Thesis, University of Strathclyde, 2016. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27075.
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In recent years, more and more research attention has been paid to the NOx emissions caused by marine diesel engines. Selective catalytic reduction (SCR) system has been proven to be an effective technology for the removal of NOx emitted from marine diesel engines. In order to comply with stringent International Maritime Organization (IMO) Tier III NOx emission regulations, a number of engine manufacturers have developed their own SCR systems with an option of installing SCR reactors before or after the turbines of engine turbochargers. This thesis focuses on modelling of evaporation and decomposition of urea-water-solution (UWS) droplets, design and optimisation of static mixers, modelling of an SCR reactor and developing model-based urea dosing control strategy. The amount of ammonia converted from UWS has a significant effect on the NOx removal efficiency of SCR systems. Due to a limited installation space for SCR systems on board, choosing the location of urea injection nozzle appropriately has become a critical issue for SCR system design. An evaporation and decomposition model of UWS droplets has been developed in this research in order to determine the total depletion time of a UWS droplet, which is helpful to calculate the proper length between the urea nozzle and reactor of an SCR system. In order to achieve a high NOx removal rate and reduce the quantity of NH₃ slip, static mixers are commonly used before SCR reactors to improve the mixing between ammonia and exhaust gases. 4 novel static mixers have been designed and the performance of the mixers is compared in the study. An experiment has been conducted to validate the mixing performance and pressure loss of the static mixers developed. It shows that there is a satisfied agreement between the simulation and experiment results. A mathematical model of SCR reactors has been established. The unknown parameters of the model are identified by minimising the error between the model predicted and measured values of both the temperature and the species concentration after the SCR reactor. The SCR reactor model is further used in a simulation for the purpose of developing model-based urea dosing control strategies. A state observer is used to determine the actual states in the reactor which supplies the mandatory information for developing model-based urea dosing control strategies. The NH₃ cross-sensitivity of NOx sensors can be described by a linear equation. The simulation results of the observer show that the NH₃ cross-sensitivity of NOx sensors can be neglected when estimating the actual states of the reactor if NH₃ is of a low concentration in the exhaust.
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López, Martinez Carlos. "Multidimensional speckle noise, modelling and filtering related to SAR data /." Köln : DLR, Bibliotheks- und Informationswesen, 2004. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015380575&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Edwards, Earl Peter Fitz-Gerald. "Digital surface modelling in developing countries using spaceborne SAR techniques." Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/10157/.
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Topographic databases at the national level, in the form of Digital Surface Models (DSMs), are required for a large number of applications which have been spurred on by the increased use of Geographic Information Systems (GIS). Ground-Based (surveying, GPS, etc.) and traditional airborne approaches to generating topographic information are proving to be time consuming and costly for applications in developing countries. Where these countries are located in the tropical zone, they are affected by the additional problem of cloud cover which could cause delays for almost 75% of the year in obtaining optical imagery. The Caribbean happens to be one such affected territory that is in need of national digital topographic information for its GIS database developments, 3D visualization of landscapes and for use in the digital ortho-rectification of satellite imagery. The use of Synthetic Aperture Radar (SAR), with its cloud penetrating and day/night imaging capabilities, is emerging as a possible remote sensing tool for use in cloud affected territories. There has been success with airborne single-pass dual antennae systems (e.g. STAR 3i) and the Shuttle Radar Topographic Mapping (SRTM) mission. However, the use of these systems in the Caribbean are restrictive and datasets will not be generally available. The launching of imaging radar satellites such as ERS-1, ERS-2, Radarsat-1 and more recently Envisat have provided additional opportunities for augmenting the technologies available for generating medium accuracy, low cost, topographic information for developing countries by using the techniques of Radargrammetry (StereoSAR) and Interferometric SAR (InSAR). The primary aim of this research was to develop, from scratch, a prototype StereoSAR system based on automatic stereo matching and space intersection algorithms to generate medium accuracy, low cost DSMs, using various influencing parameters without any recourse to ground control points. The result was to be a software package to undertake this process for implementation on a personal computer. The DSMs generated from Radarsat-1 and Envisat SAR imagery were compared with a reference surface from airborne InSAR and conclusions with respect to the quality of the StereoSAR DSMs are presented. Work required to further improve the StereoSAR system is also suggested.
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Iervolino, P. "Ship detection with SAR : modelling, designing and real data validation." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809956/.
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The request for maritime security and safety applications has increased in the recent past. In this scenario, Synthetic Aperture Radar (SAR) sensors are one of the most effective means thanks to their capability to get images independently from daylight and weather conditions. In the SAR ship-detection field, many algorithms have been presented in literature; however none of them has ever considered the aspects behind the interaction of the electromagnetic wave between the target and the surrounding sea. This thesis explores the electromagnetic interaction arising between the ship and the sea and, firstly, a novel model to evaluate the Radar Cross Section (RCS) backscattered from a canonical ship is derived. RCS is modelled according to Kirchhoff Approximation (KA) within the Geometric Optics (GO) solution. The probability density function relative to the double reflection contribution is derived for all polarizations and the new model is validated on SAR images showing a good match between the theoretical values and those ones measured on real SAR images. Then, a novel ship detector, based on the Generalized Likelihood Ratio Test (GLRT) where both the sea and the ship electromagnetic models are considered, is proposed. The GLRT is compared to the CFAR algorithm through Monte Carlo simulations in terms of ROCs (Receiver Operating Characteristic curves) and computational load at different bands (S, C and X). Performances are also compared through simulations with different orbital and scene parameters. The GLRT is then applied to datasets acquired from different sensors operating at different bands: the Target to Clutter Ratio (TCR) is computed and detection outcomes are compared with AIS data. Results show that the GLRT presents better ROCs and greatly improves the TCR, but its computational time is slower when compared to the CFAR algorithm. Finally, a new approach for ship-detection and ambiguities removal in LPRF (Low Pulse Repetition Frequency) SAR imagery is proposed. The method exploits the range migration pattern and is evaluated on a downsampled SAR image. The algorithm is able to reject the SAR azimuth ambiguities and can be adapted for the upcoming Maritime Mode of the future NovaSAR-S sensor.
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Hussaini, Nafiu. "Mathematical modelling and analysis of HIV transmission dynamics." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/5672.
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This thesis firstly presents a nonlinear extended deterministic Susceptible-Infected (SI) model for assessing the impact of public health education campaign on curtailing the spread of the HIV pandemic in a population. Rigorous qualitative analysis of the model reveals that, in contrast to the model without education, the full model with education exhibits the phenomenon of backward bifurcation (BB), where a stable disease-free equilibrium coexists with a stable endemic equilibrium when a certain threshold quantity, known as the effective reproduction number (Reff ), is less than unity. Furthermore, an explicit threshold value is derived above which such an education campaign could lead to detrimental outcome (increase disease burden), and below which it would have positive population-level impact (reduce disease burden in the community). It is shown that the BB phenomenon is caused by imperfect efficacy of the public health education program. The model is used to assess the potential impact of some targeted public health education campaigns using data from numerous countries. The second problem considered is a Susceptible-Infected-Removed (SIR) model with two types of nonlinear treatment rates: (i) piecewise linear treatment rate with saturation effect, (ii) piecewise constant treatment rate with a jump (Heaviside function). For Case (i), we construct travelling front solutions whose profiles are heteroclinic orbits which connect either the disease-free state to an infected state or two endemic states with each other. For Case (ii), it is shown that the profile has the following properties: the number of susceptible individuals is monotone increasing and the number of infectives approaches zero, while their product converges to a constant. Numerical simulations are shown which confirm these analytical results. Abnormal behavior like travelling waves with non-monotone profile or oscillations are observed.
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Mora, Pérez Javier. "Control-oriented modelling and diagnostics of diesel after-treatment catalysts." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/115937.
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[ES] Esta tesis doctoral abarca el desarrollo de algoritmos orientados a mejorar el sistema de control de emisiones en motores Diesel. Para este propósito, la inclusión en el vehículo de sensores embarcados como los de temperatura, los de NOx o el de NH3 permite realizar diagnóstico a bordo de los sistemas de post-tratamiento foco de este trabajo, los cuales son el DOC y el SCR. Así pues, el objetivo es el de satisfacer las normativas de diagnóstico a bordo para mantener las emisiones por debajo del umbral permitido por la normativa a lo largo del tiempo.
Los tests experimentales, incluyendo las medidas con analizador de gases, permiten tener una visión más amplia de las especies en la línea de escape. Complementariamente, se utilizan unidades nuevas y envejecidas para tener el efecto experimental del envejecimiento en los catalizadores. De esta manera, se analiza el efecto de la temperatura, el gasto de escape, las concentraciones de las especies y el envejecimiento en el DOC y en el SCR, así como la evaluación de algunas de las medidas relevantes realizadas por los sensores.
Las temperaturas tienen una influencia destacada en el funcionamiento de los catalizadores, por lo que se requiere la evaluación de las medidas de los sensores de temperatura, junto con el desarrollo de modelos de transmisión de calor, para alimentar las funciones a continuación desarrolladas. En este sentido, la medida lenta del sensor aguas arriba del DOC se mejora en condiciones transitorias mediante una técnica de fusión de la información basada en un filtro de Kalman. Luego, se presenta un modelo de transmisión de calor 1D y un modelo agrupado 0D, en los cuales se evalúan las entradas aguas arriba según el uso del modelo. Por otra parte, se presenta una técnica para estimar el incremento de temperatura debido a la oxidación de los pulsos de post-inyección en el DOC.
Se proponen modelos para ambos DOC y SCR para estimar el efecto del envejecimiento en las emisiones, en los cuales el factor de envejecimiento es modelado como un parámetro sintonizable que permite variar desde estados nuevos a envejecidos. Por una parte, un modelo agrupado 0D es desarrollado para el DOC con el propósito de estimar el desliz de HC y CO, el cual es validado en un WLTC para después ser usado en simulación. Por otra parte, un modelo 1D y un modelo 0D se desarrollan para el SCR, los cuales se usan a continuación para alimentar la estrategia de diagnóstico y para simulación.
Finalmente, las estrategias de diagnóstico se presentan para fallo total o retirada de DOC, así como para la estimación de la eficiencia en DOC y SCR. Por una parte, la primera estrategia se divide en pasiva y activa, en la que se usan post-inyecciones en la activa para excitar el sistema y confirmar el fallo total si es el caso. A continuación, la eficiencia del DOC se estima a través de una técnica indirecta en la que la temperatura de activación se detecta y se relaciona con el incremento de emisiones a través del modelo. Por otra parte, se desarrolla un observador para estimar el estado de envejecimiento del SCR, el cual está basado en un filtro de Kalman extendido. Sin embargo, para evitar asociar baja eficiencia del catalizador debido a pobre calidad de la urea inyectada, a envejecimiento del SCR, un indicador de la calidad de la urea se ejecuta en paralelo.[CAT] Esta tesi doctoral abasta el desenvolupament d'algoritmes orientats a millor el sistema de control d'emissions en motors Diesel. Per a este propòsit, la inclusió en el vehicle de sensor embarcats com els de temperatura, els de NOx o el d'NH3 permet realitzar el diagnòstic a bord dels sistemes de post-tractament focus d'este treball, els quals són el DOC i el SCR. Així doncs, l'objectiu és el de satisfer les normatives de diagnòstic a bord per a mantindre les emissions per baix de l'umbral permés per la normativa al llarg del temps. Els tests experimentals, incloent les mesures amb analitzador de gasos, permeten obtindre una visió més àmplia de les espècies en la línia d'escapament. Complementàriament, s'utilitzen unitats noves i envellides per tal de tindre l'efecte experimental de l'envelliment en els catalitzadors. D'aquesta manera, s'analitza l'efecte de la temperatura, la despesa d'escapament, les concentracions de les espècies i l'envelliment en el DOC i en el SCR, així com l'avaluació d'algunes mesures rellevants realitzades pels sensors. Les temperatures tenen una influència destacada en el funcionament dels catalitzadors, pel que es requerix l'avaluació de les mesures dels sensors de temperatura, junt amb el desenvolupament de models de transmissió de calor, per a alimentar les funcions a continuació desenvolupades. En este sentit, la mesura lenta del sensor a l'entrada del DOC es millora en condicions transitòries mitjançant una tècnica de fusió de la informació basada en un filtre de Kalman. Després, es presenta un model de transmissió de calor 1D i un model agrupat 0D, en els quals s'avaluen les entrades a l'entrada segons l'ús del model. Per altra banda, es presenta una tècnica per a estimar l'increment de temperatura degut a l'oxidació dels polsos de post-injecció en el DOC. Es proposen models per a DOC i SCR per a estimar l'efecte de l'envelliment en les emissions, en els quals es modela el factor d'envelliment com un paràmetre sintonitzable, que permet variar des d'estats nous a envellits. Per altra banda, un model agrupat 0D _es desenvolupat per al DOC amb el propòsit d'estimar la relliscada de HC i CO, el qual és validat en un WLTC per a després ser usat en simulació. Per altra banda, un model 1D i un model 0D es desenvolupen per al SCR, els quals s'usen a continuació per a alimentar l'estratègia de diagnòstic i per a simulació. Finalment, les estratègies de diagnòstic es presenten per a la fallada total o retirada del DOC, així com per a l'estimació de l'eficiència en DOC i SCR. Per altra banda, la primera estratègia es divideix en passiva i activa, en la que s'utilitzen post-injeccions en la activa per a excitar el sistema i confirmar la fallada total si es dona el cas. A continuació, l'eficiència del DOC s'estima a través d'una tècnica indirecta en la que la temperatura d'activació es detecta i es relaciona amb l'increment d'emissions a través del model. Per altra banda, es desenvolupa un observador per a estimar l'estat d'envelliment del SCR, el qual està basat en un filtre de Kalman extés. No obstant això, per a evitar associar baixa eficiència degut a pobre qualitat de l'urea injectada a l'envelliment del SCR, un indicador de la qualitat de l'urea s'executa en paral·lel.
[EN] This dissertation covers the development of algorithms oriented to improve the emission control system of Diesel engines. For this purpose, the inclusion of on-board sensors like temperature, NOx and NH3 sensors allows performing on-board diagnostics to the after-treatment systems focus of this work, which are the DOC and the SCR system. Then, the target is to meet on-board diagnostics regulations in order to keep emissions below a regulation threshold over time. Experimental tests, including gas analyzer measurements, allow having a wider view of the species in the exhaust line. Complementary, new and aged units are used in order to have the experimental effect of ageing on the catalysts. Then, the effect of temperature, exhaust mass flow, species concentrations and ageing is analyzed for DOC and SCR, in combination with the assessment of some relevant sensors measurements. As a result, the characteristics, opportunities and limitations extracted from experimental data are used as the basis for the development of models and diagnostics techniques. The assessment of temperature sensors measurements, along with the development of heat transfer models is required to feed temperature dependent functions. In this sense, the slow measurement of the DOC upstream temperature sensor is improved in transient conditions by means of a data fusion technique, based on a fast model and a Kalman filter. Then, a 1D and a 0D lumped heat transfer models are presented, in which the upstream inputs are assessed in relation to its use. On the other hand, a technique to estimate the temperature increase due to post-injection pulses oxidation is also presented. Both DOC and SCR models are proposed in order to estimate the effect of ageing on emissions, in which an ageing factor is modelled as a tunable parameter that allows varying from new to aged states. On the one hand, a 0D lumped model is developed for DOC in order to estimate the HC and CO species slip, which is validated in a WLTC and is then used for simulation. On the other hand, a 1D and a 0D models are developed for SCR, which are then used to feed the diagnostics strategy and for simulation. Finally, diagnostics strategies are presented for total failure or removal of DOC, as well as for efficiency estimation of DOC and SCR. On the one hand, the former strategy is separated into passive and active diagnostics, in which post-injections are used in active diagnostics in order to excite the system and confirm a total failure, in case. Then, the DOC efficiency estimation is done by means of an indirect technique in which the light-off temperature is detected and an emissions increase is related by means of the DOC ageing model. On the other hand, an observer to estimate the SCR ageing state is developed, which is based on an extended Kalman filter. However, in order to avoid associating low SCR efficiency to ageing, an indicator of the injected urea quality is developed to run in parallel.
Mora Pérez, J. (2018). Control-oriented modelling and diagnostics of diesel after-treatment catalysts [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/115937
TESIS
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Gustafsson, Magnus. "Evaluation of StochSD for Epidemic Modelling, Simulation and Stochastic Analysis." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-426227.
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Classical Continuous System Simulation (CSS) is restricted to modelling continuous flows, and therefore, cannot correctly realise a conceptual model with discrete objects. The development of Full Potential CSS solves this problem by (1) handling discrete quantities as discrete and continuous matter as continuous, (2) preserving the sojourn time distribution of a stage, (3) implementing attributes correctly, and (4) describing different types of uncertainties in a proper way. In order to apply Full Potential CSS a new software, StochSD, has been developed. This thesis evaluates StochSD's ability to model Full Potential CSS, where the points 1-4 above are included. As a test model a well-defined conceptual epidemic model, which includes all aspects of Full Potential CSS, was chosen. The study was performed by starting with a classical SIR model and then stepwise add the different aspects of the Conceptual Model. The effects of each step were demonstrated in terms of size and duration of the epidemic. Finally, the conceptual model was also realised as an Agent Based Model (ABM). The results from 10 000 replications each of the CSS and ABM models were compared and no statistical differences could be confirmed. The conclusion is that StochSD passed the evaluation.
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Maccari, Pietro <1992>. "Modelling and Uncertainty Quantification application to SA simulation codes in advanced SMR." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10122/1/Thesis_PHD_Maccari.pdf.
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In the framework of a global transition to a low-carbon energy mix, the interest in advanced nuclear Small Modular Reactors (SMRs) has been growing at the international level. Due to the high level of maturity reached by Severe Accident Codes for currently operating rectors, their applicability to advanced SMRs is starting to be studied. Within the present work of thesis and in the framework of a collaboration between ENEA, UNIBO and IRSN, an ASTEC code model of a generic IRIS reactor has been developed. The simulation of a DBA sequence involving the operation of all the passive safety systems of the generic IRIS has been carried out to investigate the code model capability in the prediction of the thermal-hydraulics characterizing an integral SMR adopting a passive mitigation strategy. The following simulation of 4 BDBAs sequences explores the applicability of Severe Accident Codes to advance SMRs in beyond-design and core-degradation conditions.
The uncertainty affecting a code simulation can be estimated by using the method of Input Uncertainty Propagation, whose application has been realized through the RAVEN-ASTEC coupling and implementation on an HPC platform. This probabilistic methodology has been employed in a study of the uncertainty affecting the passive safety system operation in the DBA simulation of ASTEC, providing a further characterization of the thermal-hydraulics of this sequence. The application of the Uncertainty Quantification method to early core-melt phenomena has been investigated in the framework of a BEPU analysis of the ASTEC simulation of the QUENCH test-6 experiment. A possible solution to the encountered challenges has been proposed through the application of a Limit Surface search algorithm.
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Linden, Sandra van der. "Icy rivers heating up : modelling hydrological impacts of climate change in the (sub)arctic /." Amsterdam : Utrecht : Koninklijk Nederlands Aardrijkskundig Genootschap ; Faculteit Ruimtelijke Wetenschappen, Universiteit Utrecht, 2002. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=010495642&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Wahle, Christian. "Die Technik der Weil-Restriktion für Huber- und Berkovich-Räume und Anwendungen zu adischen Néron-Modellen /." Münster, 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000252276.
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Tansey, Kevin James. "Monitoring and modelling surface moisture in north-east Jordan using ERS SAR data." Thesis, University of Leicester, 1999. http://hdl.handle.net/2381/30384.
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To assess the usefulness of a remote sensing approach to soil moisture monitoring in desert regions, a time series of ERS-1 and ERS-2 SAR images were acquired between March 1995 and April 1998 of the north-eastern desert of Jordan. Previous research has demonstrated the sensitivity to soil moisture and surface roughness of the backscatter coefficient of the ERS SAR system. The following objectives were addressed: (1) To assess and exploit the ability of the ERS SAR instrument to monitor geomorphological and hydrological changes in the desert environment. (2) To calibrate theoretical microwave scattering models using field reference data (soil moisture, surface roughness, soil texture, climatic parameters and vegetation) and assess their application to desert environments. (3) To simulate the dependence of the backscatter coefficient on soil moisture fluctuations and surface roughness changes with the aim of improving the understanding of microwave interactions with desert surfaces. (4) To investigate the potential for extraction of quantitative soil moisture estimates from ERS SAR data. Analysis of multitemporal backscatter coefficients, expressed in decibels (dB), for some desert surfaces show fluctuations of up to 6 dB during or after periods of rainfall. Basalt boulder or stone surfaces show very stable backscatter properties regardless of soil moisture conditions. This is because the roughness parameter dominates the scattering mechanism. Detailed analysis of surface roughness measurements and calculations are presented. To understand the scattering processes, the physical optics (PO), geometric optics (GO), small perturbation (SP) and integral equation models (IEM) were calibrated using field data. The results show the limitations of using the PO, GO and SP models in this natural environment, caused by the restrictive model validation domains. The calibration of the IEM yielded much better results, correlation coefficients greater than 0.8 were achieved between predicted and observed backscatter coefficients. Retrieval of soil moisture estimates with the IEM yielded a confidence level of 80%.
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Sternberg, My, and Julia Lindstedt. "Svenska modellen en självklarhet? : Arbetsgivares syn på förhållande till fackförbund." Thesis, Stockholms universitet, Sociologiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-156504.
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Syftet med studien var att förstå arbetsgivarsidans syn på förhållandet till fackliga organisationer och undersöka huruvida detta förhållande förklarar varför den svenska modellen fungerar så bra som den gör. För att uppnå målet med studiens ställdes följande frågeställningar: Hur ser arbetsgivarrepresentanter på förhållandet till fackförbund? Hur bidrar arbetsgivarrepresentanternas syn på fackförbunden till den svenska modellens framgång och fortlevnad? För att besvara dessa frågeställningar genomfördes sju semistrukturerade intervjuer med arbetsgivarrepresentanter i Stockholms största företag. Dessa resultat analyserades mot ett teoretiskt ramverk från tre tongivande sociologers gemensamma beröringspunkter kring kollektiva idéer. Tidigare studier inom området har dominerats av kvantitativ forskning om hur arbetsgivare sett på fackförbund i förhandlingssammanhang. Denna uppsats avser därmed att fylla en kunskapslucka av en djupare förståelse för arbetsgivarrepresentanters syn på fackförbund. Resultaten från studien visar på att arbetsgivarrepresentanterna främst har en positiv syn på förhållandet till fackförbunden, men att det även finnas aspekter där de ser problem. Den positiva synen tenderar också att bidra till den svenska modellens framgång och fortlevnad. Det förekommer däremot resultat som visar på motsatsen. Det finns därmed ett behov av vidare studier inom området för att reda ut det tvetydliga resultaten.
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Abidi, Amna. "Imperfect RDF Databases : From Modelling to Querying." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2019. http://www.theses.fr/2019ESMA0008/document.
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L’intérêt sans cesse croissant des données RDF disponibles sur le Web a conduit à l’émergence de multiple et importants efforts de recherche pour enrichir le formalisme traditionnel des données RDF à des fins d’exploitation et d’analyse. Le travail de cette thèse s’inscrit dans la continuation de ces efforts en abordant la problématique de la gestion des données RDF en présence d’imperfections (manque de confiance/validité, incertitude, etc.). Les contributions de la thèse sont comme suit: (1) Nous avons proposé d’appliquer l’opérateur skyline sur les données RDF pondérées par des mesures de confiance (Trust-RDF) dans le but d’extraire les ressources les plus confiantes selon des critères définis par l’utilisateur. (2) Nous avons discuté via des méthodes statistiques l’impact des mesures de confiance sur le Trust-skyline.(3) Nous avons intégré à la structure des données RDF un quatrième élément, exprimant une mesure de possibilité. Pour gérer cette mesure de possibilité, un cadre langagier appropriée est étudié, à savoir Pi-SPARQL, qui étend le langage SPARQL aux requêtes permettant de traiter des distributions de possibilités. (4) Nous avons étudié une variante d’opérateur skyline pour extraire les ressources RDF possibilistes qui ne sont éventuellement dominées par aucune autre ressource dans le sens de l’optimalité de ParetoThe ever-increasing interest of RDF data on the Web has led to several and important research efforts to enrich traditional RDF data formalism for the exploitation and analysis purpose. The work of this thesis is a part of the continuation of those efforts by addressing the issue of RDF data management in presence of imperfection (untruthfulness, uncertainty, etc.). The main contributions of this dissertation are as follows. (1) We tackled the trusted RDF data model. Hence, we proposed to extend the skyline queries over trust RDF data, which consists in extracting the most interesting trusted resources according to user-defined criteria. (2) We studied via statistical methods the impact of the trust measure on the Trust-skyline set.(3) We integrated in the structure of RDF data (i.e., subject-property-object triple) a fourth element expressing a possibility measure to reflect the user opinion about the truth of a statement.To deal with possibility requirements, appropriate framework related to language is introduced, namely Pi-SPARQL, that extends SPARQL to be possibility-aware query language.Finally, we studied a new skyline operator variant to extract possibilistic RDF resources that are possibly dominated by no other resources in the sense of Pareto optimality
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Mazoyer, Marie. "Impact du processus d'activation sur les propriétés microphysiques des brouillards et sur leur cycle de vie." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0025/document.
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Les brouillards sont des systèmes météorologiques complexes mettant en oeuvre des processus de fine échelle, et l'interaction subtile entre processus radiatifs, dynamiques, turbulents et microphysiques qui les régit rend leur prévision difficile. Les gouttelettes d'eau qui composent les brouillards sont formées par l'activation des particules d'aérosols, et comprendre l'impact des propriétés des aérosols sur le cycle de vie du brouillard reste un défi. L'objectif de cette thèse est d'analyser l'impact du processus d'activation sur la microphysique des brouillards et sur leur cycle de vie. Elle s'articule sur deux volets, expérimental et numérique. Dans le cadre du projet PréViBoss, une plateforme de mesures in-situ des propriétés du brouillard a été déployée durant les hivers 2010-2013 au SIRTA au sud de Paris. Les données microphysiques ont fourni la distribution dimensionnelle des particules d'aérosols et des gouttelettes, et ont informé sur la capacité des particules d'aérosols à agir en tant que noyaux de condensation nuageux (CCN). Elles sont analysées afin de documenter les propriétés du brouillard et leur évolution au cours de leur cycle de vie. La particularité de ce travail réside dans le grand nombre d'épisodes de brouillard analysés. Ainsi, 48 épisodes ont permis d'étudier l'évolution microphysique des brouillards et 23 épisodes ont permis d'étudier le processus d'activation à la formation des brouillards à travers une méthode originale. Les valeurs de sursaturation critique et les concentrations de CCN ont été caractérisées et reliées aux propriétés des aérosols (distribution, concentration et hygroscopicité). Il s'avère que c'est la valeur de la sursaturation détermine la concentration de gouttelettes, indépendamment de la concentration de particules d'aérosols activables disponibles. L'évolution microphysique des 48 épisodes de brouillards suit 4 phases aux comportements distincts, et est principalement régie par les processus de condensation/évaporation et activation/dé-activation. La concentration caractéristique en gouttelettes des brouillards est déterminée durant la première phase, elle est ensuite modulée au cours du cycle de vie du brouillard. Des simulation en mode LES d'un cas de brouillard observé lors de PréViBoss ont ensuite été réalisées avec le modèle Méso-NH, afin d'évaluer l'impact de la microphysique sur la durée de vie du brouillard. Elles permettent d'explorer précisément les interactions entre aérosols et processus physiques. Un schéma microphysique à deux moments a été utilisé au sein duquel deux schémas d'activation ont été comparés: le premier diagnostique une sursaturation maximale, alors que le second considère une évolution pseudo-pronostique de la sursaturation selon Thouron et al. (2012). Contrairement au premier, le second schéma calcule les valeurs de sursaturations réellement atteintes. Il permet de tenir compte de processus supplémentaires non considérés par le schéma actuel comme la condensation ou le mélange. Les concentrations de CCN calculées avec ce nouveau schéma sont significativement moins élevées, mais restent toutefois surestimées par rapport aux observations. La représentation de la dynamique pourrait en être responsable. Des tests de sensibilité à la concentration d'aérosols montrent un impact limité sur le cycle de vie du brouillard, excepté pour des cas extrêmes, pour lesquels une très faible concentration d'aérosols retarde la dissipation du brouillard. Ce sont les conditions dynamiques, thermodynamiques et de surface qui pilotent principalement le cycle de vie du brouillard à travers leur impact sur la stabilité de la couche limite. En outre, la prise en compte d'hétérogénéités de surface modifie très sensiblement le cycle de vie du brouillard au travers de la turbulence qu'elles génèrent. La variabilité spatio-temporelle qui en découle doit ainsi être prise en compte dans de futurs dispositifs expérimentauxFogs are complex meteorological systems dealing with fine scale processes. Their lifecycles are closely related to the interactions between radiation, fog dynamics, turbulence and fog microphysics that make their forecasting difficult. Fogs are formed by the activation of aerosols particles into water droplets. To date, understanding the impact of the aerosols properties on the fog life cycle remains still challenging. This thesis aims at investigating the impact of activation processes on fog microphysics and lifecycles. In the framework of the PréViBoss project, in-situ measurements of fog properties were performed during winters 2010 to 2013 at the SIRTA site in the south of Paris. A detailed characterization of aerosols and fog microphysics, including number size spectrum of both particles under dry and wet conditions and droplets, was performed in order to investigate the aerosols efficiency to act as cloud condensation nuclei (CCN). A large number of case studies are presented, which include 23 case studies on fog formation from the activation of aerosols and 48 fog events on the temporal evolution of fog microphysics. An original method has been used to investigate the link between supersaturation values and concentrations of CCN with aerosols properties (distribution, concentration and hygroscopicity). We show that supersaturation values determine the droplets concentration, independently of the concentration of aerosols. The evolution of fog microphysics of the 48 cases follows 4 phases with distinct behaviours, driven by condensation/evaporation and deactivation/ activation processes. The fog droplets concentration is determined during the first phase, then it fluctuate around this value during fog life cycle. Large eddy simulation of fog cases observed during PréViBoss are performed with the Meso-NH model to evaluate the impact of microphysics on fog lifetime. It allows to explore the close interactions between aerosols and physical processes. A two moments scheme is used for microphysic and two schemes for supersaturation have been evaluated, the first one estimate the maximal supersaturation and the second one considers a pseudoprognostic evolution of supersaturation following Thouron et al. (2012). Much lower supersaturation values were obtained with the second scheme. Addtional processes, such as condensation or mixing that were not included in previous scheme, are modeled. While CCN concentrations obtained with this new scheme are lower, they remain higher than the observations. We postulate that this behaviour could be due to the representation of dynamics. Sensibilitiy tests for different aerosols concentrations reveal a weak impact on fog life cycle. Only for extreme cases where the aerosol concentrations are low, the fog dissipation is delayed. This study shows that the fog life cycle is mainly driven by thermodynamics, dynamics and surface conditions through their impact on boundary layer stability. Moreover, surface heterogeneities greatly modify fog life cycle trough turbulent motions and should be considered for future experimental studies
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Taulis, Mauricio. "Groundwater characterisation and disposal modelling for coal seam gas recovery." Thesis, University of Canterbury. Civil Engineering, 2007. http://hdl.handle.net/10092/3104.
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Coal Seam Gas (CSG) is a form of natural gas (mainly methane) sorbed in underground coal deposits. Mining this gas involves drilling a well directly into an underground coal seam, and pumping out the water (CSG water) flowing through it. Presently, CSG is under exploration in New Zealand (NZ); however, there is concern about CSG water disposal in NZ mainly because of the controversy that this activity has generated in some basins in the United States (US). The first part of this thesis studies CSG water from a well in Maramarua (NZ) and compares it to water from US basins. The NZ CSG water from this well had high pH (7.8), alkalinity in the order of 360 mg/l as CaCO₃, high sodium (334 mg/l), bicarbonate (435 mg/l), and chloride (146 mg/l). These ions also occur in US CSG waters, and their concentrations follow the same trend - high sodium, bicarbonate, and chloride with low calcium, magnesium, and sulphate concentrations. Prior to this work, little detailed analyses of CSG water quality variability from a well had been carried out. A Factor Analysis of 33 Maramarua samples was conducted and revealed that about one third of the variations were due to sample degassing, which induced calcium carbonate precipitation - this was supported by experimental work (sample sparging) and geochemical modelling (MINTEQA2). This finding is important for CSG water management because, as calcium concentrations decrease, higher SAR values are generated, and this can cause problems if CSG waters are disposed on land. In the second part, this thesis assesses the potential environmental effects of disposing CSG waters in NZ by formulating management options and a simple wastewater treatment system. This was carried out by studying the ecological response (soils, plant, and aquatic life) resulting from CSG water disposal operations in the US, and by applying relevant salinity and sodicity guidelines to the interaction between soils and CSG waters from Maramarua. This work showed that similar problems are likely to occur in NZ if CSG water disposal takes place without proper controls. Such a study has never been carried out in a region before actual CSG development has taken place, so this work shows how to quantify the effects arising from CSG water disposal prior to full scale production. This can be particularly useful for CSG stakeholders wanting to develop this resource in other regions around the world. A simple treatment system using Ngakuru zeolites has proven effective in reducing the SAR of Maramarua CSG water. Laboratory results indicate that these zeolites work by exchanging sodium cations in the water by other cations contained within the zeolite structure but with slow ion exchange kinetics. The calculated sodium absorption capacity for these natural zeolites ranged from 11.3 meq/100g to 16.7 meq/100g (flow-through conditions without previous regeneration). In addition, these experiments showed that the ion exchange process is accompanied by some dissolution (sulphate, boron, TOC, sodium, calcium, magnesium, potassium and reactive silica), but mainly at the beginning of the treatment process. Nevertheless, using this system, 180 grams of zeolite material were used to treat an initial 1.83 litres of Maramarua CSG water thus reducing potential soil infiltration problems to nil. As more CSG water was treated, the zeolites kept reducing SAR values but at a lesser rate until 4.53 litres of CSG water had been treated. A step-by-step methodology to assess treatment design options for these materials has been developed and will aid future researchers and engineers. This thesis presents the first comprehensive study of CSG water management in NZ. It also presents an ion exchange treatment system using natural zeolites already available in NZ. In conclusion, the research finds that, whether through adequate management or active treatment, CSG waters can be safely disposed without creating major environmental problems, and can even be used in beneficial applications.
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Faria, Bernardes Daniel. "Information Diffusion in Complex Networks : Measurement-Based Analysis Applied to Modelling." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-01001763.
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Understanding information diffusion on complex networks is a key issue from a theoretical and applied perspective. Epidemiology-inspired SIR models have been proposed to model information diffusion. Recent papers have analyzed this question from a data-driven perspective. We complement these findings investigating if epidemic models calibrate with a systematic procedure are capable of reproducing key spreading cascade properties. We first identify a large-scale, rich dataset from which we can reconstruct the diffusion trail and the underlying network. Secondly, we examine the simple SIR model as a baseline model and conclude that it was unable to generate structurally realistic spreading cascades. We found the same result examining model extensions to which take into account heterogeneities observed in the data. In contrast, other models which take into account time patterns available in the data generate qualitatively more similar cascades. Although one key property was not reproduced in any model, this result highlights the importance of taking time patterns into account. We have also analyzed the impact of the underlying network structure on the models examined. In our data the observed cascades were constrained in time, so we could not rely on the theoretical results relating the asymptotic behavior of the epidemic and network topological features. Performing simulations we assessed the impact of these common topological properties in time-bounded epidemic and identified that the distribution of neighbors of seed nodes had the most impact among the investigated properties in our context. We conclude discussing identifying perspectives opened by this work.
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Jebali, Fatma. "Formal framework for modelling and verifying globally asynchronous locally synchronous systems." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAM036/document.
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Un système GALS (Globalement Asynchrone, Localement Synchrone) est un ensemble de composants synchrones qui évoluent en même temps, chacun à propre rythme, et qui communiquent de manière asynchrone. Cette thèse propose un environnement formel de modélisation et de vérification dédié aux systèmes GALS, en se focalisant sur le comportement asynchrone.Notre environnement s’appuie sur un langage formel que nous avons conçu nommé GRL (GALS Représentation Language). GRL permet la spécification comportementale des composants synchrones, de la communication asynchrone, et des contraintes sur les rythmes des composants ainsi que sur les valeurs que prennent les entrées des composants. Pour analyser les spécifications GRL, nous utilisons CADP, une boîte à outils logicielle permettant la vérification de processus concurrents asynchrones par des techniques d'exploration d’espaces d’états. Dans ce but, nous avons défini une traduction de GRL vers LNT, un langage de spécification supporté par CADP. La traduction est implémentée dans un outil appelé GRL2LNT, permettant ainsi la génération automatique d’espaces d'états à partir de spécifications GRL.Pour permettre la vérification formelle des spécifications GRL, nous avons conçu un langage de propriétés nommé muGRL, qui est interprété sur les espaces d’états de GRL. Le langage muGRL est basé sur un ensemble de patrons qui capturent les propriétés des systèmes concurrents et des systèmes GALS, réduisant ainsi la complexité d'utiliser les logiques temporelles classiques. La sémantique de muGRL est définie par traduction vers MCL, le langage de logique temporelle fourni par CADP. Enfin, nous illustrons l’usage de GRL, muGRL et CADP pour la modélisation et la vérification d’applications GALS concrètes, comprenant des études de cas industriellesA GALS (Globally Asynchronous, Locally Synchronous) system consists of several synchronouscomponents that evolve concurrently, each with its own pace, and communicatealtogether asynchronously. This thesis proposes a formal modelling and verificationframework dedicated to GALS systems, with a focus on the asynchronous behaviour.As a cornerstone of our framework, we have designed a formal language, named GRL(GALS Representation Language). GRL enables the behavioural specification of synchronouscomponents, asynchronous communication, and constraints involving bothcomponent paces and the data carried by component inputs. To analyse GRL specifications,we took advantage of the CADP software toolbox for the verification of asynchronousconcurrent processes, using state space exploration techniques. For this purpose,we defined a translation from GRL to the LNT specification language supportedby CADP. The translation was implemented by a tool named GRL2LNT, thus enablingstate spaces to be automatically derived from GRL specifications.To enable the formal verification of GRL specifications, we designed a property specificationlanguage, named muGRL, which is interpreted on GRL state spaces. The muGRLlanguage is based on a set of patterns capturing properties of concurrent and GALSsystems, which reduces the complexity of using full-fledged temporal logics. The semanticsof muGRL are defined by a translation into the MCL temporal logic supported byCADP. Finally, we illustrated how GRL, muGRL, and CADP can be applied to modeland verify concrete GALS applications, including industrial case-studies
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Tran, Quoc-Tran. "Some contributions to financial market modelling with transaction costs." Thesis, Paris 9, 2014. http://www.theses.fr/2014PA090036/document.
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Cette thèse traite plusieurs problèmes qui se posent pour les marchés financiers avec coûts de transaction et se compose de quatre parties.On commence, dans la première partie, par une étude du problème de couverture approximative d’une option Européenne pour des marchés de volatilité locale avec coûts de transaction proportionnelles.Dans la seconde partie, on considère le problème de l’optimisation de consommation dans le modèle de Kabanov, lorsque les prix sont conduits par un processus de Lévy.Dans la troisième partie, on propose un modèle général incluant le cas de coûts fixes et coûts proportionnels. En introduisant la notion de fonction liquidative, on étudie le problème de sur-réplication d’une option et plusieurs types d’opportunités d’arbitrage.La dernière partie est consacrée à l’étude du problème de maximisation de l’utilité de la richesse terminale d’une portefeuille sous contraintes de risqueThis thesis deals with different problems related to markets with transaction costs and is composed of four parts.In part I, we begin with the study of assymptotic hedging a European option in a local volatility model with bid-ask spread.In part II, we study the optimal consumption problem in a Kabanov model with jumps and with default risk allowed.In part III, we sugest a general market model defined by a liquidation procès. This model is more general than the models with both fixed and proportional transaction costs. We study the problem of super-hedging an option, and the arbitrage theory in this model.In the last part, we study the utility maximization problem under expected risk constraint
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Giustarini, Laura [Verfasser], and Thomas [Akademischer Betreuer] Udelhoven. "Integrating remote sensing information from SAR sensors and hydraulic modelling / Laura Giustarini ; Betreuer: Thomas Udelhoven." Trier : Universität Trier, 2016. http://d-nb.info/1197807314/34.
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Elbialy, Samy Gamal Khedr. "Potential of Spaceborne X & L-Band SAR-Data for Soil Moisture Mapping Using GIS and its Application to Hydrological Modelling: the Example of Gottleuba Catchment, Saxony / Germany." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-66626.
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Hydrological modelling is a powerful tool for hydrologists and engineers involved in the planning and development of integrated approach for the management of water resources. With the recent advent of computational power and the growing availability of spatial data, RS and GIS technologies can augment to a great extent the conventional methods used in rainfall runoff studies; it is possible to accurately describe watershed characteristics in particularly when determining runoff response to rainfall input. The main objective of this study is to apply the potential of spaceborne SAR data for soil moisture retrieval in order to improve the spatial input parameters required for hydrological modelling. For the spatial database creation, high resolution 2 m aerial laser scanning Digital Terrain Model (DTM), soil map, and landuse map were used. Rainfall records were transformed into a runoff through hydrological parameterisation of the watershed and the river network using HEC-HMS software for rainfall runoff simulation. The Soil Conservation Services Curve Number (SCS-CN) and Soil Moisture Accounting (SMA) loss methods were selected to calculate the infiltration losses. In microwave remote sensing, the study of how the microwave interacts with the earth terrain has always been interesting in interpreting the satellite SAR images. In this research soil moisture was derived from two different types of Spaceborne SAR data; TerraSAR-X and ALOS PALSAR (L band). The developed integrated hydrological model was applied to the test site of the Gottleuba Catchment area which covers approximately 400 sqkm, located south of Pirna (Saxony, Germany). To validate the model historical precipitation data of the past ten years were performed. The validated model was further optimized using the extracted soil moisture from SAR data. The simulation results showed a reasonable match between the simulated and the observed hydrographs. Quantitatively the study concluded that based on SAR data, the model could be used as an expeditious tool of soil moisture mapping which required for hydrological modelling.
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Moretto, Irene. "Aspetti numerici nell'applicazione del modello SIR." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/22165/.
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Questo lavoro si concentra sull'applicazione del classico modello a compartimenti di Kermack–McKendrick (SIR), per controllare l'andamento dell'epidemia COVID-19 in Italia, utilizzando i dati messi a disposizione dal Dipartimento della Protezione Civile italiano, relativi alla regione Veneto. L'implementazione di tale modello pone interessanti problemi legati sia alla soluzione numerica del problema inverso, attraverso cui avviene la calibrazione dei parametri del modello, che alla soluzione numerica dei problemi differenziali richiesti all'interno della calibrazione e successivamente in fase di previsione.
Un primo obiettivo di questa tesi è quello di fare un'analisi dei metodi numerici per risolvere il sistema di equazioni differenziali che descrive il modello SIR e determinare, attraverso opportuni confronti, l'algoritmo più adatto a risolvere il problema di calibrazione. Inoltre, si è studiata una modifica del SIR che prevede l'utilizzo di parametri come funzioni dipendenti dal tempo, nota come modello forzato, con l'obiettivo di ottenere un migliore adattamento della curva epidemiologica in base alle misure di contenimento introdotte.
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Jestin, Camille. "Modélisation analogique du glissement sur une faille." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAH017/document.
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La présence de défauts sur les surfaces des failles tectoniques peut modifier le comportement de la rupture sur ces interfaces. Cependant, le rôle de ces hétérogénéités reste difficile à quantifier du fait de la résolution limitée de l’imagerie des failles en profondeur. Une approche analogique permettant de préciser l’impact des hétérogénéités dans la propagation de la fracture est présentée ici. Cette analyse repose, tout d’abord, sur l’utilisation d’un montage expérimental assurant le suivi de la propagation d’une fracture sous contrainte de traction normale au plan de rupture (mode I). Le dispositif utilisé, mettant en jeu un suivi acoustique et optique de l’avancée du front de fracture, nous amène à déterminer l’impact des aspérités sur le partitionnement de l’énergie entre processus sismiques et asismiques. Nous faisons le lien entre efficacité de radiation et vitesse de rupture, localement perturbée par la présence de microstructures le long de l’interface. Afin d’étendre nos résultats à d’autres modes de rupture, plus fréquemment observés lors de ruptures le long de failles tectoniques, nous nous intéressons à l’adaptation de notre montage expérimental pour l’observation d’une fracture se propageant en mode de cisaillement (mode III). L’analyse des propriétés morphologiques et dynamiques de l’avancée d’un front de rupture en mode III révèle des résultats semblables à ceux obtenus en mode I. Cela suggère que les résultats obtenus en mode I peuvent être étendus aux autres modes de rupturesThe presence of defaults on the surface of tectonic faults can affect the behaviour of the rupture along those interfaces. However, because of the limited resolution of the faults imaging at depth, the implication of these heterogeneities remains hard to quantify. We present here an analogic approach enabling the precision of the impact of the heterogeneities on the fracture propagation. On one hand, this analysis lays on the use of an experimental setup ensuring the monitoring of a fracture propagating under an imposed stress, normal to the rupture interface (mode I). The used model, implying an acoustic and an optical monitoring of the fracture front advance, leads us to the determination of the impact of asperities on the energy partitioning between seismic and aseismic processes. We make the link between radiation efficiency and rupture velocity, locally affected by the presence of microstructures along the interface. On another hand, to extend our results to other rupture modes, which are observed more often during rupture on tectonic faults, we get interested in the adaptation of our experimental setup for the observation of a fracture propagating under shear stress (mode III). The analysis of morphologic and dynamic properties of the mode III crack advance shows results similar to those obtained for mode I. This suggests eventually that the results observed in mode I can be extended to other rupture modes
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Randuineau, Benoît. "Interactions entre pathogènes : quels impacts sur la santé publique ?" Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066645/document.
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L'étude des pathogènes est un des piliers des progrès en santé publique des dernières décennies. Actuellement, un axe principal qui reste à explorer pour poursuivre ces progrès réside dans l'étude des interactions entre les différents pathogènes qui circulent dans les mêmes populations. En effet, comme n'importe quel être vivant, un pathogène s'inscrit dans un écosystème avec lequel il interagit grandement et qui comporte, entre autres, d'autres pathogènes. Dans cette thèse nous nous sommes intéressés aux implications de ces interactions à différents niveaux. Tout d'abord, un large travail bibliographique a été mené afin d'identifier les interactions déjà connues et référencées, d'en tirer une catégorisation claire et utile, de souligner les manques actuels de la littérature dans ce domaine et d'introduire le concept de susceptibilité réalisée. Dans une seconde partie, il a s'agit d'explorer les conséquences dynamiques possibles de certaines interactions identifiées précédemment et de tenter de développer des méthodes largement utilisables de détection d'interactions à partir de données populationnelles. Enfin, la dernière partie se penche sur le cas particulier de la Dengue, dont les quatre sérotypes interagissent fortement entre eux, et des possibles conséquences de ces interactions pour la vaccination contre cette maladie. Cette thèse apporte une nouvelle vision de la dynamique des pathogènes, en les intégrant dans le cadre plus large de la communauté de pathogènes. Elle ouvre sur les possibles progrès des méthodes statistiques et comment les modèles théoriques pourraient aider à la compréhension des communautés de pathogènesThe study of pathogens is a keystone of considerable progress for Public Health in the last decades. Nowadays, a promising field of study are interactions between pathogens circulating in the same populations. Indeed, just as any living species, a pathogen is part of an ecosystem, and within this ecosystem it interacts with numerous things, including other pathogens. In this PhD thesis we have been interested in the consequences of such interactions at several scales. Firstly a wide bibliographic work has been accomplish in order to identify known and documented interactions. From this work we propose several categories of interactions and point out the gaps in this literature. Then we explored the potential consequences on population of several interactions described in the first part, and tested promising methods to detect such interaction from population-scale data. Lastly we focused on the specific example of dengue, where four strongly interacting serotypes and current vaccine developments rise the issue of the interference between interactions and Public Health policies. A broader vision of pathogens dynamics rises from the embedding of pathogens into a community, and this vision could benefit from progress in statistical methods and theoretical models
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Mazzilli, Naomi. "Sensibilité et incertitude de modélisation sur les bassins méditerranéens à forte composante karstique." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20188/document.
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Les aquifères karstiques sont associés à des enjeux importants en termes à la fois de gestion de la ressource en eau et de gestion du risque d'inondation. Ces systèmes sont caractérisés par une structure fortement hétérogène et un fonctionnement non-linéaire. Cette thèse est consacrée à l'étude de la sensibilité et de l'incertitude associés à la modélisation numérique des écoulements en milieu karstique. De façon systématique, l'analyse de sensibilité est utilisée comme outil afin de répondre aux questions suivantes: (i) la calibration est-elle possible ? (ii) la calibration est-elle robuste ? (iii) est-il possible de réduire l'équifinalité via une calibration multi-objectif ou multi-variable ?Cette contribution met en évidence le potentiel des méthodes locales d'analyse de sensibilité. En dépit des limitations inhérentes à cette approche (approximation locale et perturbation d'un facteur à la fois), l'analyse locale permet une compréhension fine du fonctionnement du modèle, pour un coût de calcul réduit.Par ailleurs, cet travail souligne l'intérêt d'une calibration multi-variable par rapport à une calibration multi-objectif, dans une optique de réduction de l'équifinalitéKarst aquifers are associated with key issues for water resource management and also for flood risk mitigation. These systems are characterized by a highly heterogeneous structure and non-linear functioning. This thesis addresses the sensitivity and uncertainty associated with the numerical modelling of groundwater flow in karst systems. As a systematic approach, sensitivity analysis has been used to answer the following questions:(i) is it possible to calibrate the model ? (ii) is the calibration robust ? (iii) is it possible to reduce equifinality, through multi-objective calibration or through multi-variable calibration ? This contribution stresses the potentialities of local sensitivity analyses. Despite their inherent limitations (local approximation), local analyses have proved to bring valuable insights into the general behaviour of complex, non-linear flow models, at little computational cost. Besides, this contribution also stresses the interest of multi-variable calibration as compared to multi-objective calibration, as regards equifinality reduction
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Herculano, Miguel Colburn. "Modelling long-term worker´s compensation : an application to a general insurance company." Master's thesis, Último nome, Primeiro nome. data de publicação. "Título". Dissertação de Mestrado. Universidade de Lisboa. Instituto Superior de Economia e Gestão, 2013. http://hdl.handle.net/10400.5/6043.
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Mestrado em Ciências ActuariaisThis paper resumes the main findings from modeling life underwriting risks to which Worker´s Compensation is exposed. Models presented aim to shorten the path between ad hoc procedures in place and the new capital requirements foreseen by Solvency II. The legal framework of this line of business is primarily explained as it is determinant for modeling purposes. We then provide a discussion about risk models in use, major options, assumptions and other relevant issues that were regarded when modeling this line of business.
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Braun, Mathias. "Reduced Order Modelling and Uncertainty Propagation Applied to Water Distribution Networks." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0050/document.
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Les réseaux de distribution d’eau consistent en de grandes infrastructures réparties dans l’espace qui assurent la distribution d’eau potable en quantité et en qualité suffisantes. Les modèles mathématiques de ces systèmes sont caractérisés par un grand nombre de variables d’état et de paramètres dont la plupart sont incertains. Les temps de calcul peuvent s’avérer conséquents pour les réseaux de taille importante et la propagation d’incertitude par des méthodes de Monte Carlo. Par conséquent, les deux principaux objectifs de cette thèse sont l’étude des techniques de modélisation à ordre réduit par projection ainsi que la propagation spectrale des incertitudes des paramètres. La thèse donne tout d’abord un aperçu des méthodes mathématiques utilisées. Ensuite, les équations permanentes des réseaux hydrauliques sont présentées et une nouvelle méthode de calcul des sensibilités est dérivée sur la base de la méthode adjointe. Les objectifs spécifiques du développement de modèles d’ordre réduit sont l’application de méthodes basées sur la projection, le développement de stratégies d’échantillonnage adaptatives plus efficaces et l’utilisation de méthodes d’hyper-réduction pour l’évaluation rapide des termes résiduels non linéaires. Pour la propagation des incertitudes, des méthodes spectrales sont introduites dans le modèle hydraulique et un modèle hydraulique intrusif est formulé. Dans le but d’une analyse plus efficace des incertitudes des paramètres, la propagation spectrale est ensuite évaluée sur la base du modèle réduit. Les résultats montrent que les modèles d’ordre réduit basés sur des projections offrent un avantage considérable par rapport à l’effort de calcul. Bien que l’utilisation de l’échantillonnage adaptatif permette une utilisation plus efficace des états système pré-calculés, l’utilisation de méthodes d’hyper-réduction n’a pas permis d’améliorer la charge de calcul. La propagation des incertitudes des paramètres sur la base des méthodes spectrales est comparable aux simulations de Monte Carlo en termes de précision, tout en réduisant considérablement l’effort de calculWater distribution systems are large, spatially distributed infrastructures that ensure the distribution of potable water of sufficient quantity and quality. Mathematical models of these systems are characterized by a large number of state variables and parameter. Two major challenges are given by the time constraints for the solution and the uncertain character of the model parameters. The main objectives of this thesis are thus the investigation of projection based reduced order modelling techniques for the time efficient solution of the hydraulic system as well as the spectral propagation of parameter uncertainties for the improved quantification of uncertainties. The thesis gives an overview of the mathematical methods that are being used. This is followed by the definition and discussion of the hydraulic network model, for which a new method for the derivation of the sensitivities is presented based on the adjoint method. The specific objectives for the development of reduced order models are the application of projection based methods, the development of more efficient adaptive sampling strategies and the use of hyper-reduction methods for the fast evaluation of non-linear residual terms. For the propagation of uncertainties spectral methods are introduced to the hydraulic model and an intrusive hydraulic model is formulated. With the objective of a more efficient analysis of the parameter uncertainties, the spectral propagation is then evaluated on the basis of the reduced model. The results show that projection based reduced order models give a considerable benefit with respect to the computational effort. While the use of adaptive sampling resulted in a more efficient use of pre-calculated system states, the use of hyper-reduction methods could not improve the computational burden and has to be explored further. The propagation of the parameter uncertainties on the basis of the spectral methods is shown to be comparable to Monte Carlo simulations in accuracy, while significantly reducing the computational effort
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Ganigué, Pagès Ramon. "Partial nitritation of landfill leachate in a SBR prior to an anammox reactor : operation and modelling." Doctoral thesis, Universitat de Girona, 2010. http://hdl.handle.net/10803/7805.
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Els lixiviats d'abocadors urbans són aigües residuals altament contaminades, que es caracteritzen per les elevades concentracions d'amoni i el baix contingut de matèria orgànica biodegradable. El tractament dels lixiviats a través dels processos de nitrificació-desnitrificació convencionals és costós a causa de la seva elevada demanda d'oxigen i la necessitat d'addició d'una font de carboni externa. En els darrers anys, la viabilitat del tractament d'aquest tipus d'afluents per un procés combinat de nitritació parcial-anammox ha estat demostrada. Aquesta tesi es centra en el tractament de lixiviats d'abocador a través d'un procés de nitritació parcial en SBR, com un pas preparatori per a un reactor anammox. Els resultats de l'estudi han demostrat la viabilitat d'aquesta tecnologia per al tractament de lixiviats d'abocador. El treball va evolucionar des d'una escala inicial de laboratori, on el procés va ser testat inicialment, a uns exitosos experiments d'operació a llarg termini a escala pilot. Finalment, la tesi també inclou el desenvolupament, calibració i validació d'un model matemàtic del procés, que té com a objectiu augmentar el coneixement del procés.Urban landfill leachate are highly contaminated wastewater, usually characterised by high ammonium concentrations and low biodegradable organic matter content. Treating leachate through conventional nitrification-denitrification processes is expensive due to its high oxygen demand and the requirement of a supplementary external carbon source. In recent years, the feasibility of treating such streams with a low C:N ratio by a combined partial nitritation-anammox process has been demonstrated. This thesis deals with the treatment of landfill leachate by a partial nitritation-SBR, as a preparative step for an anammox reactor. The results of the study have demonstrated the feasibility of this technology for the treatment of landfill leachate. The work evolved from initial lab-scale studies, where the process was first tested, to a successful long-term experiment at pilot-scale. In addition, the thesis also includes the development, calibration and validation of a mathematical model of the process, aiming at increasing process knowledge.
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Bourgin, François. "Comment quantifier l’incertitude prédictive en modélisation hydrologique ? : Travail exploratoire sur un grand échantillon de bassins versants." Thesis, Paris, AgroParisTech, 2014. http://www.theses.fr/2014AGPT0016/document.
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La modélisation hydrologique permet de quantifier la transformation pluie-débit au sein d’un bassin versant. Bien que les modèles parviennent généralement à représenter de manière acceptable le fonctionnement des bassins versants, cette représentation, nécessairement simplifiée, reste imparfaite, et une quantification des incertitudes est souhaitable. Cette thèse s’intéresse à la quantification de l’incertitude prédictive en modélisation hydrologique. Le principal objectif de nos travaux est d’explorer différentes méthodes qui permettent d’associer à des simulations ou des prévisions de débits déterministes des distributions probabilistes. Nous distinguons le contexte de simulation du contexte de prévision et adoptons dans ces deux cas une démarche comparative et pragmatique qui permet d’évaluer différentes approches sur un large échantillon de bassins versants français, à l’aide de critères d’évaluation adaptés. En simulation, nos travaux ont porté sur deux méthodes liées à l'estimation des paramètres des modèles hydrologiques, la méthode GLUE et le calage bayésien, ainsi que sur deux approches plus pragmatiques, l'approche multi-modèles, et le post-traitement statistique. Nos résultats suggèrent que les approches telles que GLUE qui ne s'appuient que sur un ensemble de différents jeux de paramètres ne parviennent pas, en général, à représenter de manière adéquate l'incertitude prédictive totale. L'utilisation d'un modèle d'erreur extérieur au fonctionnement interne du modèle hydrologique est nécessaire. Les méthodes de post-traitement suffisamment flexibles pour caractériser les erreurs résiduelles obtenues en calage parviennent à refléter de manière plus satisfaisante les marges d'erreurs du modèle hydrologique utilisé. Nous proposons également une méthode qui permet d'obtenir une estimation de l'incertitude prédictive pour les bassins non jaugés, au moyen d'un transfert des marges d'erreurs constatées sur les bassins jaugés. Les résultats indiquent que la méthode est prometteuse et fournit dans la plupart des cas des intervalles de confiance fiables et fins sur les sites non-jaugés. En prévision, nos travaux ont porté d'une part sur la comparaison de différentes méthodes de post-traitement statistique, et d'autre part sur l'interaction entre l'assimilation de données et le post-traitement au sein d'une chaîne de prévision hydrologique d'ensemble. Les résultats obtenus montrent l'importance de la prise en compte de l'évolution de l'incertitude prédictive en fonction de l'échéance de prévision et mettent en évidence les gains de performance qui peuvent être obtenus quand la quantification de l'incertitude s'appuie sur une meilleure caractérisation de la situation de la situation de prévision. Enfin, nos travaux indiquent que l'utilisation conjointe de l'assimilation de données et d'une méthode de post-traitement permet d'améliorer les performances d'une chaîne de prévision hydrologique d'ensembleHydrological modelling aims to quantify the rainfall-runoff relationship at the catchment scale. Although hydrological models are generally able to provide an acceptable representation of the catchment behaviour, this representation is necessarily simplified and imperfect, as a consequence an evaluation of uncertainties is desirable. This thesis focuses on the quantification of predictive uncertainty in hydrological modelling. Our main objective was to explore several methods that can be used to complete the deterministic predictions of a rainfall-runoff model with probabilistic distributions. Two prediction cases were distinguished, namely simulation and forecast. We set up a comparative framework to evaluate different uncertainty quantification methods on a large set of French catchments. In simulation mode, we focused on two methods related to the parameter estimation issue, the GLUE uncertainty method and the Bayesian framework, as well as two more pragmatic approaches, a multi-model approach and the post-processing method. Our results suggest that the GLUE-like methods based on ensembles of various parameter sets do not provide an adequate representation of the total predictive uncertainty. An external model error is necessary. Post-processing methods that are flexible enough to adequately describe the residual errors of the hydrological model obtained during calibration give more satisfactory estimates of the modelling uncertainty. We also present a method able to transfer model uncertainty estimates from gauged to ungauged catchments. Our results demonstrate that the method holds interesting perspectives, providing in most cases reliable and sharp uncertainty bounds at ungauged locations. In a forecasting context, we compared several post-processing methods and evaluated the interactions between data assimilation and post-processing in an ensemble forecasting modelling chain. Results show the crucial role of the lead time on the estimates of predictive uncertainty. They also suggest that some improvement can be achieved when the evolution of flows is better taken into account by a post-processing method. Last, we investigated the interactions between data assimilation and post-processing in hydrological ensemble forecasting and showed the benefits of using both in an ensemble forecast system
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Wang, Yuwei. "Evolution of microservice-based applications : Modelling and safe dynamic updating." Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAS009.
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Les architectures à base de microservices permettent de construire des systèmes répartis complexes composés de microservices indépendants. Le découplage et la modularité des microservices facilitent leur remplacement et leur mise à jour de manière indépendante. Depuis l'émergence du développement agile et de l'intégration continue (DevOps et CI/CD), la tendance est aux changements de version plus fréquents et en cours d'exécution des applications. La réalisation des changements de version est effectuée par un processus d'évolution consistant à passer de la version actuelle de l'application à une nouvelle version. Cependant, les coûts de maintenance et d'évolution de ces systèmes répartis augmentent rapidement avec le nombre de microservices.L'objectif de cette thèse est de répondre aux questions suivantes~:Comment aider les ingénieurs à mettre en place une gestion de version unifiée et efficace pour les microservices et comment tracer les changements de version dans les applications à base de microservices ?Quand les applications à base de microservices, en particulier celles dont les activités sont longues, peuvent-elles être mises à jour dynamiquement sans arrêter l'exécution de l'ensemble du système ? Comment la mise à jour doit-elle être effectuée pour assurer la continuité du service et maintenir la cohérence du système ?En réponse à ces questions, cette thèse propose deux contributions principales. La première contribution est constituée de modèles architecturaux et d'un graphe d'évolution pour modéliser et tracer la gestion des versions des microservices. Ces modèles sont construits lors de la conception et utilisés durant l'exécution. Cette contribution aide les ingénieurs à abstraire l'évolution architecturale afin de gérer les déploiements lors d'une reconfiguration, et fournit la base de connaissances nécessaire à un intergiciel de gestion autonomique des activités d'évolution. La deuxième contribution est une approche basée sur les instantanés pour la mise à jour dynamique (DSU) des applications à base de microservices. Les instantanés répartis cohérents de l'application en cours d'exécution sont construits pour être utilisés dans la spécification de la continuité du service, l'évaluation des conditions de mise à jour sûre et dans la mise en œuvre des stratégies de mise à jour. La complexité en nombre de messages de l'algorithme DSU n'est alors pas égale à la complexité de l'application répartie, mais correspond à la complexité de l'algorithme de construction d'un instantané réparti cohérentMicroservice architectures contribute to building complex distributed systems as sets of independent microservices. The decoupling and modularity of distributed microservices facilitates their independent replacement and upgradeability. Since the emergence of agile DevOps and CI/CD, there is a trend towards more frequent and rapid evolutionary changes of the running microservice-based applications in response to various evolution requirements. Applying changes to microservice architectures is performed by an evolution process of moving from the current application version to a new version. The maintenance and evolution costs of these distributed systems increase rapidly with the number of microservices.The objective of this thesis is to address the following issues: How to help engineers to build a unified and efficient version management for microservices and how to trace changes in microservice-based applications? When can microservice-based applications, especially those with long-running activities, be dynamically updated without stopping the execution of the whole system? How should the safe updating be performed to ensure service continuity and maintain system consistency?In response to these questions, this thesis proposes two main contributions. The first contribution is runtime models and an evolution graph for modelling and tracing version management of microservices. These models are built at design time and used at runtime. It helps engineers abstract architectural evolution in order to manage reconfiguration deployments, and it provides the knowledge base to be manipulated by an autonomic manager middleware in various evolution activities. The second contribution is a snapshot-based approach for dynamic software updating (DSU) of microservices. The consistent distributed snapshots of microservice-based applications are constructed to be used for specifying continuity of service, evaluating the safe update conditions and realising the update strategies. The message complexity of the DSU algorithm is not the message complexity of the distributed application, but the complexity of the consistent distributed snapshot algorithm
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Auzerais, Anthony. "Impact d'un cylindre vertical sur la dynamique sédimentaire sous l'action d'un courant." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMLH02/document.
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Les travaux portent sur l’étude de la formation de motifs sédimentaires à l’aval d’un cylindre vertical soumis à un courant. Le cylindre simule une fondation monopieu d’éolienne en mer, ou une pile de pont. Une modélisation théorique est développée. Les résultats obtenus sont en bon accord avec les résultats expérimentaux acquis au cours de la thèse. Une étude préliminaire expérimentale et théorique sur le tri sédimentaire au voisinage du cylindre est également effectuéeThis work concerns the study of sediment patterns formation downstream a vertical cylinder under a steady current. The cylinder simulates an offshore monopile foundation, or a bridge pile. A theoretical modeling is developed. The results are in good agreement with the experimental results obtained in the framework of this PhD. An experimental and theoretical preliminary study on sediment segregation in the vicinity of the cylinder is also performed
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Girinon, Mathieu. "Développement d’un modèle numérique sur l’étude de l’intégrité des surfaces en perçage." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEE003/document.
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L’intégrité de surface a un rôle significatif sur la tenue en fatigue des composants usinés. Des spécifications particulières émergent de la part des fabricants et particulièrement de ceux de l’aéronautique. Les trous percés sont des zones critiques à partir desquelles des endommagements peuvent se produire. Néanmoins les contraintes résiduelles sont peu étudiées en perçage. Elles émanent de phénomènes multi-physiques issus de l’opération de perçage difficilement identifiables à cause du confinement du trou. Ce rapport présente les travaux expérimentaux et numériques mis en œuvre au cours de la thèse. Le projet s’est d’abord focalisé autour de l’identification des phénomènes physiques mis en jeu pendant l’opération de perçage pour différents modes de lubrification et sur l’analyse des contraintes résiduelles sur la surface du trou percé. Ce premier volet expérimental a posé les bases de compréhension nécessaires au développement des modèles numériques.Les développements numériques s’articulent autour de deux axes. Le premier consiste à représenter l’opération de perçage. L’état de l’art ainsi qu’une étude préalable ont permis d’identifier les difficultés liées à la modélisation numérique d’une opération de perçage pour des longueurs percées significatives. Le premier modèle développé répond à cette problématique et détermine les sollicitations induites par le perçage nécessaires au calcul des contraintes résiduelles. Le deuxième axe de développement numérique permet de prédire les contraintes résiduelles présentes dans une pièce percée à partir des chargements issus du premier modèleThe surface integrity has a significant impact on the fatigue life of the machined parts. New requirements appear from manufacturers and especially from aeronautical industrialists. Drilling holes are critical and can damage the component. Nevertheless, residual stresses are not studied a lot in drilling processes. The residual stresses created are a result of multi-physical phenomena during drilling processes. It is difficult to identify them due to the confinement of the hole. In the current study, experimental tests are realized and numerical model of drilling surface integrity was developed. First, experimental works were performed in several lubrication conditions to understand physical phenomena which lead to residual stresses in the drilled workpiece. The numerical developments are set-up about two sections. The first numerical model represents the drilling operation. The state of the art and an initial study were shown that the actual numerical models are not able to simulate a drilling operation in an important drilling depth. So the first numerical model gives an estimation of loads induced by the drilling operation and necessary to compute residual stresses. Finally, the second numerical model simulates residual stresses in a drilled part taking in account loads provided
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van, Beijma Sybrand Jucke. "Remote sensing-based mapping and modelling of salt marsh habitats based on optical, LiDAR and SAR data." Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/32455.
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There is much interest in the ability of Remote Sensing (RS) technologies for mapping natural environments. Meanwhile, coastal zones need monitoring in order to find a balance between human use and sustainable functioning of coastal zone ecosystems. This research explores methods for characterising coastal salt marsh zone habitats using multi-source RS data, focussing on under-exploited Synthetic Aperture Radar (SAR) remote sensing data, thereby providing additional information in support of the mapping of natural habitats in coastal zones. This research examined the use of quad-polarimetric airborne S-band and X-band SAR data, in conjunction with optical and LiDAR RS data variables, for assessment of environmental parameters, mapping and modelling of salt marsh habitats in a research area set in the Llanrhidian salt marshes in Wales. In the first analysis it was researched how SAR descriptors (backscatter intensity and polarimetric decomposition variables) were affected by salt marsh environmental and botanical factors. It was found that SAR backscatter from the most seaward pioneer zone of the salt marsh was most affected by soil moisture variations. Differences in botanical structure caused variations in SAR backscatter mechanisms active in different habitats. In the second analysis habitat mapping was carried out with optical, LiDAR and SAR variables, with the supervised classifiers Support Vector Machine (SVM) and Random Forest (RF). With these classifiers accurate salt marsh habitat maps were produced, the most accurate classification achieved was 78.20% with RF based on all available RS variables. The last research experiment involved multivariate regression analysis of correlations between RS variables and biophysical parameters vegetation cover, height and volume and showed that multivariate SVM regression was the most accurate technique for all three biophysical parameters. This research indicated that SAR is complementary to optical and LiDAR data for ecological mapping and therefore recommended to be included in similar ecological studies.
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Wiberg, Sara. "Matematisk vardagskompetens : Svenska gymnasielärares syn och undervisningspraxis." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-78645.
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Syftet med denna studie var att undersöka lärares syn och undervisningspraxis när det handlar om matematisk vardagskompetens. Fyra lärare intervjuades var för sig. När lärarnas svar analyserades framkom en likartad syn, att matematisk vardagskompetens handlar om den matematik man behöver för att klara sig i sin egen vardag. Denna syn går i linje med den definition som Organisation for Economic Co-operation and Development, OECD, har tagit fram och som dessutom är den som forskning i allmänhet refererar till. De uppgifter med fokus på matematisk vardagskompetens som lärarna ger till sina elever handlar både om att klara den egna vardagen och att klara sig i en framtida vardag som vuxen och yrkesarbetare. Lärarnas undervisningspraxis skiljer sig åt då det kommer till matematisk vardagskompetens. En av lärarna har ett tydligt samarbete med yrkeslärarna och eleverna får således mycket matematisk vardagskompetens i undervisningen. Lärarna försöker i övrigt få med det i matematikundervisningen för att motivera eleverna för densamma. Hur detta sker är mer eller mindre strukturerat beskrivet. Brist på tid, för stora undervisningsgrupper och avsaknad av samarbete med yrkeslärarna nämns som faktorer som begränsar hur stort fokus lärarna har på matematisk vardagskompetens i undervisningen.The aim of this study was to investigate teachers’ views and teaching praxes when it comes to mathematical literacy. Four teachers were interviewed individually. When the teachers’ answers were analyzed, an analogous view was displayed, that mathematical literacy is about the mathematics one needs to be able to cope with one’s own everyday life. This view corresponds to the definition Organisation for Economic Co-operation and Development, OECD, has presented and that research in general refers to. The assignments with focus on mathematical literacy, that the teachers give their students, deals both with managing one’s own everyday life and a future everyday as an adult and skilled worker. The teachers’ teaching praxes differ when it comes to mathematical literacy. One of the teachers has a clear cooperation with the vocational teachers and the students receive therefore much mathematical literacy in the teaching. The teachers try, otherwise, to teach mathematical literacy to motivate the students for the teaching. How this is fulfilled is more or less structurally described. Deficiency of time, too large teaching groups and want of cooperation with the vocational teachers are mentioned as factors confining the focus the teachers have on mathematical literacy in the teaching.
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Garcia-Rosales, G. "Effet de la température sur la rétention de U(VI) par SrTiO$_3$." Phd thesis, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00200303.
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L'étude des mécanismes de sorption de l'ion uranyle sur le substrat SrTiO$_3$ en fonction de la température a fait l'objet de cette étude. Tout d'abord, une caractérisation physico¬chimique a été réalisée à l'aide de plusieurs techniques structurales (DRX, FTIR) et morphologique (MEB). La spectroscopie XPS a permis d'identifier deux sites de surface (Ti¬OH et Sr-OH). En utilisant les titrages potentiométriques de SrTiO$_3$ à différentes températures, les caractéristiques acido-basiques ont été déterminées. Ensuite, la simulation des titrages potentiométriques, entre 25 et 90°C, a été réalisée à l'aide du code FITEQL, les constantes d'équilibre ainsi obtenues montrent une nette variation avec la température: la protonation du site $\equiv Sr – OH$ suit un processus endothermique tandis que la déprotonation du site $\equiv Ti – OH$ implique un processus exothermique. A partir de ces constantes d'équilibre, les grandeurs thermodynamiques, enthalpie et entropie de protonation/déprotonation ont été calculées en utilisant la relation de van't Hoff. Les études de sorption de l'ion uranyle sur le substrat SrTiO$_3$ ont été réalisées dans un intervalle de pH de 0.5 à 5. Les sauts de sorption ainsi obtenus montrent une nette augmentation du pourcentage de sorption avec l'augmentation de la température, traduisant un phénomène globalement endothermique. Deux sites de sorption différents ont été identifiés à la surface du solide par SLRTIF. Ils sont associés aux temps de vie de fluorescence de l'uranyle sorbé de 12 $\pm$ 2 et 60 $\pm$ 5 $\mu$s. Les sauts de sorption ont été modélisés à l'aide du code FITEQL en utilisant le modèle à capacitance constante. Cette simulation des sauts de sorption a été réalisée en tenant compte des résultats de l'étude structurale (deux sites de surface $\equiv Sr - OH$ et $\equiv Ti – OH$ et formation de complexe surfacique de sphère interne bidendate, mononucléaire) et des données obtenues dans la modélisation des titrages potentiométriques. Les équilibres de sorption modélisés ont confirmé la formation de deux complexes de surface de caractère bidendate : [($\equiv SrOH)($\equivTiOH)UO_2]^{2+}$ et [($\equiv TiOH)($\equivTiO)UO_2]^{2+}$. Suite à l'obtention des constantes thermodynamiques obtenues par cette simulation, la relation van't Hoff a été appliquée pour déterminer les variations d'enthalpie et d'entropie associés au processus de sorption. Finalement, une étude sur les transferts d'énergie a été présentée entre deux ions sorbés sur le solide SrTiO$_3$. Ainsi, le transfert d'énergie non-radiatif des ions Tb$^{3+}$ vers les ions EU$^{3+}$ a été étudié. L'application du modèle de Inokuti-Hirayama et Dexter a conduit à l'évaluation du rayon de la sphère d'interaction (2,7-3,4 Å) entre les deux ions (Tb$^{3+}$ et EU$^{3+}$)
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Belleudy, Clément. "Modélisation des transferts d’air et leur impact sur le comportement hygrothermique de l'enveloppe des bâtiments." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREA0002/document.
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Dans un contexte de durcissement des règlementations thermiques, la maîtrise de l'étanchéité à l'air des bâtiments est essentielle pour atteindre les objectifs de consommation énergétique. Les fuites d'air parasites à travers l'enveloppe, dues aux défauts de conception ou à une mauvaise mise en oeuvre, mènent à une surconsommation énergétique, mais aussi à des pathologies liées à l'humidité, mettant en péril la durabilité du bâti et la santé des occupants. Le risque lié à l'humidité est particulièrement présent dans les cas des enveloppes légères à ossature bois, sensibles aux transferts d'air.Il est donc nécessaire de mieux comprendre et de quantifier l'impact de ces transferts d'air sur le champ hygrothermique et sur le flux de chaleur au niveau d'un défaut d'étanchéité. Dans ce but, deux modèles numériques traitant les transferts couplés 'air-chaleur' et couplés 'air-chaleur-humidité' sont développés. Le second modèle est d'abord validé en 1D à l'aide de benchmarks numériques. Ensuite, des mesures de température dans un isolant en ouate de cellulose traversé par un flux d'air humide sont comparées avec les sorties des modèles. Une bonne concordance mesures-modèles est obtenue. Le modèle 'air-chaleur-humidité' s'avère plus précis pour prédire le champ de température que le modèle 'air-chaleur'.Suite à cette validation 2D du modèle couplé 'air-chaleur-humidité', celui-ci est appliqué à une géométrie de défaut complexe, mettant en jeu des isolants poreux perméables à l'air en contact avec des fines lames d'air. Ce défaut se veut réaliste, puisqu'il est issu de campagnes de mesures nationales qui ont permis d'identifier les points sensibles des enveloppes à ossature bois vis à vis des fuites d'air parasites. Des simulations sont réalisées avec des conditions aux limites variables en température et humidité sur des temps longs (quatre ans), en exfiltration et en infiltration d'air. Ces études permettent de dégager certaines tendances vis-à-vis des risques liés à l'humidité. Ainsi, l'exfiltration provoque une humidification significative de l'assemblage tandis que l'infiltration mène à un séchage. Une méthodologie pour évaluer les flux thermiques à l'échelle du défaut est également proposée.Dans une dernière partie, une approche simplifiée est proposée pour prendre en compte l'impact des défauts d'étanchéité à l'air sur la déperdition thermique à l'échelle bâtiment. La perte thermique supplémentaire générée par un défaut d'étanchéité peut être caractérisée par un coefficient de perte thermique propre au défaut, et le couplage du flux d'air avec l'enveloppe a une influence significative sur l'évaluation du flux déperditif total. Enfin, l'influence des transferts d'humidité sur les tendances observées est discutéeWithin the context of more stringent buildings codes, mastering airtightness is of importance to achieve energy efficient buildings. Unintended air leakage through the building envelope, which is due to bad design and poor workmanship, not only increases energy consumption, but also leads to moisture disorders, affecting building durability and occupants health. This moisture risk is present in particular for lightweight structures such as timber frame buildings, which are sensitive to air leakage.It is therefore necessary to better understand and to assess the impact of unintented air transfers on the hygrothermal field and the heat flux in the vicinity of an airtightness defect. To this end, two numerical models are developped, dealing with Heat-Air (HA) and Heat-Air-Moisture (HAM) transfer respectively. The HAM model is firstly validated in 1D using numerical benchmarks from literature. Then, temperature measurements in a cellulose insulation layer subjected to moist air flow are compared with the models outputs, and good agreement is obtained. The HAM model provides a better prediction of the temperature field compared to the HA model.Following this 2D experimental validation of the HAM model, it is applied to a complex defect geometry, including porous insulation materials and thin air gaps. This defect is meant to be realistic, as it is drawn from a measurement campaign aiming to identify typical envelope leakage points encountered in timber frame buildings.Long term simulations are performed under transient temperature and humidity conditions, in case of air exfiltration and air infiltration. This study helps identifying tendencies towards moisture risk: infiltrating air flow dries the assembly whereas exfiltrating air flow humidifies it. A methodology to assess heat fluxes through the defect is presented.Finally, a simplified approach is derived from the detailed HAM-model, to take into account the contribution of airtightness defects on the total heat loss on the building scale. It is shown that the additional heat loss induced by an airtightness defect may be described by a specific heat loss coefficient. In addition, the coupling between air flow and envelope has a significant impact on total heat flux calculations. The influence of moisture transfers on observed tendencies is also discussed
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Karatsori, Theano. "Caractérisation et modélisation de UTBB MOSFET sur SOI pour les technologies CMOS avancées et applications en simulations circuits." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT035/document.
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La motivation de cette thèse est deux des principaux problèmes soulevés par la mise à l'échelle des appareils de la nouvelle ère dans la conception MOSFET contemporaine: le développement d'un modèle de courant de drain analytique et compact, valable dans toutes les régions d'opération, décrivant précisément les caractéristiques Id-Vg et Id-Vd des dispositifs FDSOI à canaux courts et l'étude des problèmes de fiabilité et de variabilité de ces transistors évolués à l'échelle nanométrique. Le chapitre II fournit une base théorique et technique pour une meilleure compréhension de cette thèse, en mettant l'accent sur les paramètres électriques MOSFET critiques et les techniques d'extraction. Il démontre les méthodologies de Y-Function et de Split-CV pour la caractérisation électrique dans divers types de semiconducteurs. L'influence du niveau de l'oscillateur du signal AC sur la mesure de la mobilité efficace par la technique Split-CV dans MOSFET est également analysée. Une nouvelle méthodologie basée sur la fonction Lambert W qui permet d'extraire les paramètres MOSFET sur la gamme de tension de grille complète, permettant de décrire la transition entre les regions en dessous et au dessus du seuil, malgré la réduction de la tension d'alimentation. Enfin, certains éléments de base concernant le bruit à basse fréquence (LFN) sur la caractérisation MOSFET sont décrits. Le chapitre III présente la modélisation analytique et compacte du courant de drain dans les MOSFET FDSOI à l'échelle nanométrique. Des modèles analytiques simples pour les tensions de seuil de la grille avant et arrière et les facteurs d'idéalité ont été développés en termes de paramètres de géométrie du dispositif et de tensions de polarisation appliquées avec contrôle de la grille arrière. Un modèle analytique et compact de courant de drain a été développé pour les MOSFET FDSOI UTBB légèrement dopés avec contrôle de la grille arrière, prenant en compte la géométrie réduite et d'autres effets importants dans ces technologies et implémenté en Verilog-A pour la simulation des circuits dans Cadence Spectre. Le chapitre IV traite des problèmes de fiabilité dans les transistors FDSOI. La dégradation par des porteurs chauds des nMOSFET UTBB FDSOI decananométrique a été étudiée dans différentes conditions de stress de drain et de grille. Les mécanismes de dégradation ont été identifiés grâce à des mesures LFN à température ambiante dans les domaines de la fréquence et du temps. Un modèle de vieillissement HC est proposé permettant de prédire la dégradation du dispositif stressé dans différentes conditions de polarisation, en utilisant de paramètres uniques déterminés pour chaque technologie extraits par des mesures. Enfin, les caractéristiques de stress NBTI et le comportement de relaxation après stress sous la polarisation positive des pMOSFET UTBB FDSOI de grille HfSiON ont été étudiés. Un modèle pour le NBTI a été développé en considérant les mécanismes de piégeage/dépiégeage des trous, en fonction de la température et de la tension de polarisation. Le chapitre V présente des études sur les problèmes de variabilité dans les dispositifs décananométriques. Les principales sources de courant de drain et de grille de la variabilité locale ont été étudiées. Dans cet aspect, un modèle de courant de drain de la variabilité locale, valable pour toute condition de polarisation de grille et de drain, a été développé. Les principaux paramètres MOSFET de variabilité locale et globale ont été extraits par ce modèle pour différentes technologies CMOS (Bulk 28nm, FDSOI 14nm, Si bulk FinFET 14nm, nanofils Si/SiGe sous 15nm). L’impact de la variabilité du courant de drain sur les circuits de Cadence Spectre est présenté. Un résumé de cette thèse est présenté au chapitre VI, qui souligne les principales contributions à la recherche et les orientations de recherche futures sont suggéréesΤhe motivation for this dissertation is two of the main issues brought up by the scaling of new-era devices in contemporary MOSFET design: the development of an analytical and compact drain current model, valid in all regions of operation describing accurately the transfer and output characteristics of short-channel FDSOI devices and the investigation of reliability and variability issues of such advanced nanoscale transistors. Chapter II provides a theoretical and technical background for the better understanding of this dissertation, focusing on the critical MOSFET electrical parameters and the techniques for their extraction. It demonstrates the so-called Y-Function and Split-CV methodologies for electrical characterization in diverse types of semiconductors. The influence of AC signal oscillator level on effective mobility measurement by split C-V technique in MOSFETs is also analyzed. A new methodology based on the Lambert W function which allows the extraction of MOSFET parameters over the full gate voltage range, enabling to fully capture the transition between subthreshold and above threshold region, despite the reduction of supply voltage Vdd is presented. Finally, some basic elements concerning the low frequency noise (LFN) on MOSFETs characterization are described. Chapter III presents the analytical drain current compact modeling in nanoscale FDSOI MOSFETs. Simple analytical models for the front and back gate threshold voltages and ideality factors have been derived in terms of the device geometry parameters and the applied bias voltages with back gate control. An analytical compact drain current model has been developed for lightly doped UTBB FDSOI MOSFETs with back gate control, accounting for small geometry and other significant in such technologies effects and implemented via Verilog-A code for simulation of circuits in Cadence Spectre. Chapter IV is dealing with reliability issues in FDSOI transistors. The hot-carrier degradation of nanoscale UTBB FDSOI nMOSFETs has been investigated under different drain and gate bias stress conditions. The degradation mechanisms have been identified by combined LFN measurements at room temperature in the frequency and time domains. Based on our analytical compact model of Chapter III, an HC aging model is proposed enabling to predict the device degradation stressed under different bias conditions, using a unique set of few model parameters determined for each technology through measurements. Finally, the NBTI stress characteristics and the recovery behavior under positive bias temperature stress of HfSiON gate dielectric UTBB FDSOI pMOSFETs have been investigated. A model for the NBTI has been developed by considering hole-trapping/detrapping mechanisms, capturing the temperature and bias voltage dependence. In Chapter V studies of variability issues in advanced nano-scale devices are presented. The main sources of drain and gate current local variability have been thoroughly studied. In this aspect, a fully functional drain current mismatch model, valid for any gate and drain bias condition has been developed. The main local and global variability MOSFET parameters have been extracted owing to this generalized analytical mismatch model. Furthermore, the impact of the source-drain series resistance mismatch on the drain current variability has been investigated for 28nm Bulk MOSFETs. A detailed statistical characterization of the drain current local and global variability in sub 15nm Si/SiGe Trigate nanowire pMOSFETs and 14nm Si bulk FinFETs has been conducted. Finally, a complete investigation of the gate and drain current mismatch in advanced FDSOI devices has been performed. Finally, the impact of drain current variability on circuits in Cadence Spectre is presented. An overall summary of this dissertation is presented in Chapter VI, which highlights the key research contributions and future research directions are suggested
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Lind, Philip. "A study of modelling the energy system of an ice rink sports facility : Modelling the heating and cooling of ABB arena syd and implementation of renewable energy sources using TRNSYS." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-40054.
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Environmental issues are important challenges for today’s society. Lots of the energy used by humans comes from fossil energy sources resulting in the environmental threats. A considerable amount of this energy is used in the building sector. Industrial buildings and sports facilities are large users of energy and thus becomes very interesting in an optimization point of view. Modelling of the systems allows for cheap and effective optimizing of the energy usage and effectivity measures can be investigated and implemented. This study creates a model of the indoor ice rink arena of ABB arena syd in Västerås using TRNSYS as the main software for simulation. Focus is placed on the heating of the arena through heat pumps and district heating, and cooling of the ice in the arena using cooling machines. The effect of PV as well as a battery storage in the arena is also investigated as an effectiveness scenario. The results from the study revealed that it is possible to simulate the heating demand for the arena, accurately identifying the normal demand as well as the instances when the demand peaks and the magnitude of the peaks. It is also possible to simulate the cooling demand for the ice over extended time periods. However, this study could not identify the peaks for cooling demand. It is also beneficial for the system to install PV, but not a battery storage. With current price levels for electricity it is however not a very beneficial deal. With higher electricity prices the investment is preferable. The study also concludes that TRNSYS can be used for modelling an ice rink sports arena, however it leaves room for improvement on that aspect.
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Lemaire, Vincent. "Modélisation de l'aérosol organique : impact sur la pollution longue-distance en Europe." Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1057/document.
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La pollution particulaire recouvre de nombreux enjeux sanitaires et climatiques en Europe et dans le monde. Les aérosols organiques, qui représentent une fraction importante de la pollution particulaire, sont une matière complexe, émise directement sous forme condensée ou résultant de l'oxydation d'un très grand nombre de composés organiques volatiles dans l'atmosphère. En raison de la grande variété de ses sources d'émissions, qu'elles soient d'origine biogénique ou anthropique, la composition et les processus de formation et de vieillissement chimique des aérosols organiques restent aujourd'hui associés à de nombreuses interrogations. L'observation sur le terrain de la formation de la matière organique et de son évolution au sein des masses d'air étant difficile à mettre en œuvre, la modélisation reste un outil complémentaire indispensable pour simuler l'aérosol organique et suivre son transport sur de longues distances. C'est pourquoi ces travaux se sont attachés dans un premier temps à identifier les processus majeurs gouvernant aussi bien la formation que le vieillissement photochimique de la fraction organique des particules. En se basant sur une méthodologie innovante, un schéma chimique opérationnel dédié à l'émission et à l'oxydation de composés semi-volatiles a été développé pour les modèles de qualité de l'air. Son implémentation et son évaluation au sein du modèle CHIMERE a été réalisée par confrontation aux données des campagnes estivales et hivernales de la campagne MEGAPOLI. Enfin ces travaux se sont également attachés à implémenter dans CHIMERE et à discuter des mécanismes d'oligomérisation des composés organiques en phase condensée, phénomène qui est aujourd'hui reconnu comme l'un des processus majeur du vieillissement de l'aérosol organiqueNowadays, particular pollution is at the center of many environmental concerns because of its health effects and of its interactions with climate issues. Organic aerosols represent an important part of particular matter. They can be directly emitted as particulate matter or results from the oxidation of many different volatile organic compounds in the atmosphere. Owing to the large variety of its biogenic and anthropogenic emission sources, organic aerosol composition as well as its formation and chemical aging processes are still questioning. Field observations of organic aerosol aging and transport are quite complex to set up. This is why modeling tools remain a necessary complementary approach to describe the formation and long-range transport of the organic fraction of particulate matter. For these reasons, this work focused on the identification and the simulation of some of the main processes controlling the formation and photochemical aging of organic aerosols. Based on an innovating approach, we developed an operational chemical scheme for air quality models dedicated to the simulation of semi-volatile primary compound emission and oxidation. Its implementation and its evaluation in the CHIMERE model have been conducted through a comparison with the summer and winter MEGAPOLI campaign database. In parallel, one objective of this work was to implement oligomerization processes in our model, since it is now recognized that this process is one major pathway for organic aerosol aging
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Haglund, Therese, and Anna Rahm. "Vad styr mikroföretags val av revisor? : En kvalitativ studie av fem mikroföretag i Uppsala." Thesis, Uppsala University, Department of Business Studies, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8620.
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Shang, Lei, and lei shang@ieee org. "Modelling of Mobile Fading Channels with Fading Mitigation Techniques." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20061222.113303.
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This thesis aims to contribute to the developments of wireless communication systems. The work generally consists of three parts: the first part is a discussion on general digital communication systems, the second part focuses on wireless channel modelling and fading mitigation techniques, and in the third part we discuss the possible application of advanced digital signal processing, especially time-frequency representation and blind source separation, to wireless communication systems. The first part considers general digital communication systems which will be incorporated in later parts. Today's wireless communication system is a subbranch of a general digital communication system that employs various techniques of A/D (Analog to Digital) conversion, source coding, error correction, coding, modulation, and synchronization, signal detection in noise, channel estimation, and equalization. We study and develop the digital communication algorithms to enhance the performance of wireless communication systems. In the Second Part we focus on wireless channel modelling and fading mitigation techniques. A modified Jakes' method is developed for Rayleigh fading channels. We investigate the level-crossing rate (LCR), the average duration of fades (ADF), the probability density function (PDF), the cumulative distribution function (CDF) and the autocorrelation functions (ACF) of this model. The simulated results are verified against the analytical Clarke's channel model. We also construct frequency-selective geometrical-based hyperbolically distributed scatterers (GBHDS) for a macro-cell mobile environment with the proper statistical characteristics. The modified Clarke's model and the GBHDS model may be readily expanded to a MIMO channel model thus we study the MIMO fading channel, specifically we model the MIMO channel in the angular domain. A detailed analysis of Gauss-Markov approximation of the fading channel is also given. Two fading mitigation techniques are investigated: Orthogonal Frequency Division Multiplexing (OFDM) and spatial diversity. In the Third Part, we devote ourselves to the exciting fields of Time-Frequency Analysis and Blind Source Separation and investigate the application of these powerful Digital Signal Processing (DSP) tools to improve the performance of wireless communication systems.