Gotowe bibliografie tematyczne / Equivalence Transport / Rozprawy doktorskie

Rozprawy doktorskie na temat „Equivalence Transport”

Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Equivalence Transport.
Autor: Grafiati
Data publikacji: 27 lipca 2024
Data aktualizacji: 29 lipca 2024

Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych

Wybierz rodzaj źródła:

Sprawdź 35 najlepszych rozpraw doktorskich naukowych na temat „Equivalence Transport”.

Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.

Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.

Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.

1

Rispo, Adrien. "Modélisation neutronique avancée des interfaces avec la chaîne SCIENCE V2 pour la remontée axiale du flux dans les réacteurs REP". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP034.

Pełny tekst źródła
Streszczenie:
L'objectif de la thèse est de comprendre puis réduire les biais sur la distribution axiale de puissance de la chaîne de calcul SCIENCE de FRAMATOME en comparaison aux simulations Monte-Carlo. L'enjeu industriel est d'estimer précisément la remontée de puissance en extrémité de colonne fissile, à l'interface avec le réflecteur. Cette surpuissance locale est nommée PIC1, pour pic de puissance dans le premier centimètre de combustible. Ce phénomène local étant très dépendant du type d'assemblage, les comparaisons sont réalisées pour six types d'assemblages différents représentatifs du parc français, afin de quantifier les écarts sur le PIC1. Une analyse des différentes sources de biais permet de déterminer une nouvelle structure du schéma actuel de SCIENCE, notamment sur l'équivalence réalisée dans le calcul des données du réflecteur axial, afin de réduire ces biais.Un nouveau schéma d'équivalence réflecteur est développé durant la thèse, permettant un gain en précision sur le PIC1 sur les configurations utilisées précédemment, ainsi que sur des configurations perturbées et avec un environnement. Il permet également un couplage avec le Monte-Carlo, en utilisant les sections efficaces homogénéisées comme données d'entrée pour l'échelle cœur. L'utilisation de plusieurs codes de transport déterministes montre l'importance du traitement 3D dans la résolution de l'équation de Boltzmann.Le nouveau schéma apporte également un gain de précision en évolution en comparant l'apport du nouveau schéma par rapport aux calculs équivalents avec SCIENCE de production et le Monte-Carlo. Une discussion sur la méthode d'implémentation de ce nouveau schéma dans SCIENCE de production est discutée, notamment sur la méthode de génération des sections efficaces à l'échelle réseau
The aim of this thesis is to understand and then reduce the biases in the axial power distribution between FRAMATOME's SCIENCE calculation chain and Monte-Carlo simulations. The industrial challenge is to accurately estimate the power increase at the bottom of the fissile column, at the interface with the reflector. This local overpower is called PIC1, for peak power in the first centimeter of fuel. As this local phenomenon highly depends on the assembly type, PIC1 comparisons are made for six different assembly types, all representative of the French fleet. An analysis of the various sources of bias is performed to determine a new calculation scheme for SCIENCE.A new reflector scheme based on an improved equivalence was developed during the thesis, enabling a gain in PIC1 accuracy for all configurations, but also on perturbed and with an environment configurations. It also enables a coupling with Monte Carlo, using homogenized cross sections as input data for the core level. The use of several deterministic transport codes demonstrates the importance of the 3D contribution to solve the Boltzmann equation.The new scheme also increases accuracy for depletion calculation. The way to implement the new scheme in SCIENCE for industrial studies is discussed, with an emphasis on the method to generate macroscopic cross-sections at the lattice level
Style APA, Harvard, Vancouver, ISO itp.
2

Sciannandrone, Daniele. "Acceleration and higher order schemes of a characteristic solver for the solution of the neutron transport equation in 3D axial geometries". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112171/document.

Pełny tekst źródła
Streszczenie:
Le sujet de ce travail de thèse est l’application de la méthode de caractéristiques longues (MOC) pour résoudre l’équation du transport des neutrons pour des géométries à trois dimensions extrudées. Les avantages du MOC sont sa précision et son adaptabilité, le point faible était la quantité de ressources de calcul requises. Ce problème est même plus important pour des géométries à trois dimensions ou le nombre d’inconnues du problème est de l’ordre de la centaine de millions pour des calculs d’assemblage.La première partie de la recherche a été dédiée au développement des techniques optimisées pour le traçage et la reconstruction à-la-volé des trajectoires. Ces méthodes profitent des régularités des géométries extrudées et ont permis une forte réduction de l’empreinte mémoire et une réduction des temps de calcul. La convergence du schéma itératif a été accélérée par un opérateur de transport dégradé (DPN) qui est utilisé pour initialiser les inconnues de l’algorithme itératif and pour la solution du problème synthétique au cours des itérations MOC. Les algorithmes pour la construction et la solution des opérateurs MOC et DPN ont été accélérés en utilisant des méthodes de parallélisation à mémoire partagée qui sont le plus adaptés pour des machines de bureau et pour des clusters de calcul. Une partie importante de cette recherche a été dédiée à l’implémentation des méthodes d’équilibrage la charge pour améliorer l’efficacité du parallélisme. La convergence des formules de quadrature pour des cas 3D extrudé a aussi été explorée. Certaines formules profitent de couts négligeables du traitement des directions azimutales et de la direction verticale pour accélérer l’algorithme. La validation de l’algorithme du MOC a été faite par des comparaisons avec une solution de référence calculée par un solveur Monte Carlo avec traitement continu de l’énergie. Pour cette comparaison on propose un couplage entre le MOC et la méthode des Sous-Groupes pour prendre en compte les effets des résonances des sections efficaces. Le calcul complet d’un assemblage de réacteur rapide avec interface fertile/fissile nécessite 2 heures d’exécution avec des erreurs de quelque pcm par rapport à la solution de référence.On propose aussi une approximation d’ordre supérieur du MOC basée sur une expansion axiale polynomiale du flux dans chaque maille. Cette méthode permet une réduction du nombre de mailles (et d’inconnues) tout en gardant la même précision.Toutes les méthodes développées dans ce travail de thèse ont été implémentées dans la version APOLLO3 du solveur de transport TDT
The topic of our research is the application of the Method of Long Characteristics (MOC) to solve the Neutron Transport Equation in three-dimensional axial geometries. The strength of the MOC is in its precision and versatility. As a drawback, it requires a large amount of computational resources. This problem is even more severe in three-dimensional geometries, for which unknowns reach the order of tens of billions for assembly-level calculations.The first part of the research has dealt with the development of optimized tracking and reconstruction techniques which take advantage of the regularities of three-dimensional axial geometries. These methods have allowed a strong reduction of the memory requirements and a reduction of the execution time of the MOC calculation.The convergence of the iterative scheme has been accelerated with a lower-order transport operator (DPN) which is used for the initialization of the solution and for solving the synthetic problem during MOC iterations.The algorithms for the construction and solution of the MOC and DPN operators have been accelerated by using shared-memory parallel paradigms which are more suitable for standard desktop working stations. An important part of this research has been devoted to the implementation of scheduling techniques to improve the parallel efficiency.The convergence of the angular quadrature formula for three-dimensional cases is also studied. Some of these formulas take advantage of the reduced computational costs of the treatment of planar directions and the vertical direction to speed up the algorithm.The verification of the MOC solver has been done by comparing results with continuous-in-energy Monte Carlo calculations. For this purpose a coupling of the 3D MOC solver with the Subgroup method is proposed to take into account the effects of cross sections resonances. The full calculation of a FBR assembly requires about 2 hours of execution time with differences of few PCM with respect to the reference results.We also propose a higher order scheme of the MOC solver based on an axial polynomial expansion of the unknown within each mesh. This method allows the reduction of the meshes (and unknowns) by keeping the same precision.All the methods developed in this thesis have been implemented in the APOLLO3 version of the neutron transport solver TDT
Style APA, Harvard, Vancouver, ISO itp.
3

Duarte, Gustavo Ignácio. "Integrabilidade de G-Estruturas". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/45/45131/tde-05072018-111337/.

Pełny tekst źródła
Streszczenie:
Esta dissertação tem como objetivo discutir sob quais condições uma G- estrutura é integrável. Primeiro apresentam-se fibrados principais, vetoriais e outras estruturas a elas associados como torção, espaços verticais, espaços horizontais e conexões. Depois apresentam-se a definição de G-estrutura, de integrabilidade de G-estruturas, com exemplos e as respectivas versões de integrabilidade e equivalência de G-estruturas. Finalmente, são descritas condições mais gerais que garantem a integrabilidade de G-estruturas.
This dissertation aims to discuss what are the conditions for the inte- grability of a G-structure. We begin presenting principal bundles, vectoer bundles, associated bundles and other structures related to them like torsion, vertical spaces, horizontal spaces and connections. After this, we present the definition of G-structure, integrability os G-structures with examples ans respectives versions of integrabilities and the equivalence of G-estructures. Finally, we describe more general conditions that ensure the integrability of G-structures.
Style APA, Harvard, Vancouver, ISO itp.
4

Loh, Shihk-Hurng. "Pharmacology and physiology of H'+- equivalent membrane transport in the mammalian ventricular mycocyte". Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390485.

Pełny tekst źródła
Style APA, Harvard, Vancouver, ISO itp.
5

Fernandes, Victor Santoro. "Desenvolvimento de método de análise de materiais equivalentes ao tecido humano por simulação Monte Carlo". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-12122017-130310/.

Pełny tekst źródła
Streszczenie:
Materiais radiologicamente equivalentes ao tecido humano (Tissue Equivalent Material - TEM) têm a finalidade de evitar exposição injustificável à radiação de pacientes e são amplamente utilizados no controle de qualidade de equipamentos de diagnóstico por imagem. Esses materiais devem ser caracterizados para que se possa confiar em sua semelhança, em termos de suas propriedades de interação com a matéria, aos tecidos que substituem. Uma das maneiras de caracterizar os materiais é verificando se o espectro transmitido através deles se assemelha ao transmitido através do tecido que substituem. O método Monte Carlo (MC) é uma ferramenta útil no processo de caracterização dos TEM pois pode evitar o processo custoso de realizar experimentos de transmissão de raios-X. Esse trabalho investigou a aplicabilidade do método MC à caracterização de TEM de tecido mamário (bTEM) utilizados no controle de qualidade de equipamentos de mamografia. Para verificar a aplicabilidade do método MC, uma série de resultados de simulações foi comparada a resultados experimentais. Espectros de raios X transmitidos foram comparados diretamente através da média de seus resíduos reduzidos (Mean Weighted Squared Residuals - MWSR). Comparações foram feitas através de grandezas derivadas dos espectros. Essas grandezas foram: as camadas semi-redutoras (primeira e segunda), a energia média e a energia efetiva. Foi realizada uma discussão acerca da eficiência de cada uma dessas comparações, através da estimativa do poder de cada teste de hipótese. Os experimentos de transmissão de radiação foram realizados em duas instalações, no Laboratório de Dosimetria das Radiações e Física Medida da Universidade de São Paulo, onde foi utilizado um tubo de raios X com anodo de tungstênio adaptado para qualidades de feixe utilizadas em aplicações mamográficas, e no Centro de Desenvolvimento de Tecnologia Nuclear da Comissão Nacional de Energia Nuclear, equipado com um mamógrafo clínico com anodos de tungstênio e molibdênio. Diversas condições experimentais foram variadas para assegurar a robustez das conclusões, tais como as combinações anodo/filtro, os materiais constituintes dos bTEM, suas glandularidades, espessuras e as tensões de pico. Os espectros sem nenhuma atenuação (0 mm) também foram medidos e utilizados nas comparações. Os espectros foram medidos com um detector comercial de CdTe. Dosímetros termoluminescentes foram utilizados para estimar a dose depositada em diversas regiões do bTEM, e esses resultados foram também comparados às simulações. Além da estimativa do nível de exatidão alcançado pelo código de MC nas referidas condições, também se concluiu que o teste de hipótese do MWSR teve o maior poder estatístico, de 0,996. O MWSR foi o teste que demonstrou a compatibilidade dos espectros medidos o maior número de vezes. Esse teste aceitou 48% dos pares de espectros contra 40% de aceitação do teste da primeira camada semi-redutora, que foi o segundo teste com maior aceitação.
man radiologically tissue equivalent materials (TEM) have the purpose of avoiding unjustifiable irradiation of patients; they are largely used in the quality control of image diagnostic equipment. These materials must be characterized so that their similarity to the tissues they simulate can be relied upon, regarding their properties of interaction with radiation. One way of characterizing the materials is by checking the resemblance between their transmitted spectrum to the one of tissue they simulate. The Monte Carlo (MC) method is a useful tool in the TEM characterization process, since it may avoid the realization of costly experiments of transmitted X-ray spectrometry. MC may even dismiss preliminary experiments. This work investigated the applicability of the MC method to the characterization of breast tissue TEM (bTEM) used in the quality control of mammography equipment. To evaluate the applicability of the MC method, a series of simulation results was compared to experimental data. Transmitted spectra were directly compared through their mean weighted squared residues (MWSR), and by the comparisons of spectra derived quantities, as it is commonly done in the literature. These quantities were: the half value layers (first and second), the mean energy and the effective energy. A discussion about the efficiency of each one of these comparisons was made by estimating the statistical power of each hypothesis test. The radiation transmission experiments were carried out in two facilities: at the Laboratory of Radiation Dosimetry and Medical Physics of the University of São Paulo, where a tungsten anode X-ray tube adapted to mammographic applications was used. The rest of the experiments was done at the Nuclear Technology Development Center of the National Commission of Nuclear Energy, equipped with a clinical mammographic equipment with anodes composed by tungsten and molybdenum. Several experimental conditions were varied to ensure the robustness of the conclusions, such as the anode/filter combination, the bTEM constituent materials, their glandularities, thicknesses and peak voltages. Spectra with no attenuation (0 mm) were also measured and used in the comparisons. The spectral measurements were done with a commercial CdTe detector. Thermo-luminescent dosimeters were used to estimate the dose deposited at several regions inside the bTEM, and these results were also compared to simulations. In addition to estimating the level of accuracy achieved by the MC code in the mentioned conditions, it was also concluded that the highest statistical power was scored by the MWSR and it was of 0.996. The MWSR was also the test which attested this compatibility of the measured spectra the most. It accepted 48% of the spectra pair against 40% acceptance of the first half value layer test, which was the second test with most acceptance.
Style APA, Harvard, Vancouver, ISO itp.
6

Villafuerte, Francisco C. "Carbonic anhydrase activity and its role in membrane H+-equivalent transport in mammalian ventricular myocytes". Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:f355ea40-a6a8-45ed-bc78-408bec2c16d2.

Pełny tekst źródła
Streszczenie:
Carbonic anhydrases (CAs) are fundamental and ubiquitous enzymes that catalyse the reversible hydration of CO2 to form HCO3- and H+ ions. Evidence derived from heterologous expression systems has led to the proposal of a novel role for CA in intracellular pH regulation, where its physical and functional coupling to membrane H+ -equivalent transport proteins appears to enhance their activity. It has yet to be established whether such a functional association occurs naturally in wild-type cells. Additional evidence on CA activity in-vitro, has also suggested that certain CA isoforms are regulated by physiological changes of pH, an effect that may then affect their ability to enhance H+ -equivalent transport. No information, however, exists on the pH sensitivity of CA in intact cells. Finally, pharmacological inhibition of CA activity has been reported previously for various compounds, in addition to those designed specifically as CA inhibitors. It is possible that some compounds, currently used to inhibit membrane H+ transport, may also target CA. The present work has examined functional aspects of CA activity in ventricular myocytes isolated enzymically from rat heart, focusing on the potential role of C A in controlling sarcolemmal Na+/H+ exchange (NHE) and sarcolemmal Na+-HCO3- cotransport (NEC). NHE and NEC activity were estimated from the rate of recovery of intracellular pH (pHi), following an intracellular acid load in myocytes loaded with carboxy-SNARF-1 (a pH-sensitive fluorescent dye, used to measure pHi)). In other experiments, in-vitro CA activity was assessed from the time-course of pH change after addition of CO2-saturated water to a buffered solution containing either CA II or a cardiac homogenate. In further experiments, intracellular CA activity was assessed from the rate of CO2-induced fall of pHi. Three major results emerged, (i) In intact myocytes, CA activity doubles acid extrusion on sarcolemmal NBC, but has no effect on NHE activity. Facilitation of NBC activity by CA is likely to be mediated by an intracellular CA isoform. (ii) In-vitro and intracellular CA activity displays strong pH-dependence within the physiological pH range, activity declining with a fall of pH. (iii) The NHE inhibitor, cariporide, the bicarbonate transport inhibitors DIDS (4,4'- diisothiocyanatostilbene-2,2'-disulphonic acid) and S0859 (an experimental compound from Sanofi-Aventis), and the aquaporin blocker, pCMBS (p-chloromercuribenzene sulphonate), all showed strong inhibitory activity towards CA in-vitro, but had no effect on intracellular CA activity. Overall, the work provides the first clear demonstration of a functional role of CA activity in H+-equivalent transport in a wild-type cell. CA thus represents an important regulatory mechanism of H+ -equivalent transport. The pH sensitivity displayed by in-vitro and intracellular CA activity may also have significant functional consequences for pHi regulation. CA inhibition by various membrane transport inhibitors highlights the need for careful drug and experimental design, to avoid secondary inhibition of CA activity and its side-effects. The present work thus provides insight into the functional roles of CA, plus important new information on the enzyme's pharmacological properties.
Style APA, Harvard, Vancouver, ISO itp.
7

Rugaitis, Šarūnas. "Šiaulių miesto triukšmo šaltinių analizė". Bachelor's thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130821_131435-28848.

Pełny tekst źródła
Streszczenie:
Garso lygio matavimai Šiaulių mieste buvo atlikti geguţės mėnesį. Tyrimų vietos buvo pasirinktos gyvenamojoje aplinkoje prie didţiųjų prekybos centų „Akropolis“, „Tilţė“, „Bruklinas“ ir „Saulės miestas“, gyvenamojoje aplinkoje prie geleţinkelio stoties, Šiaulių reabilitacijos centro aplinkoje, prie J. Janonio gimnazijos, kuriai didţiausią triukšmą sukelia autotransportas ir šalia Jovaro progimnazijos. Palyginimui, tose pačiose vietose matavimai buvo ir savaitgalio metu. Didţiausias ekvivalentinis garso lygis išmatuotas šalia prekybos centro „Saulės miestas“. Aukštas triukšmo lygis uţfiksuotas taip pat prie J. Janonio gimnazijos.. Vidutinis triukšmo lygis šalia gyvenamųjų namų išmatuotas netoli prekybos centrų „Tilţė“, „Akropolis“, „Bruklinas“ bei Jovaro progimnazijos aplinkoje, kuriuose garso lygiai viršija leistiną ribą 1 - 4 dBA. Šiaulių reabilitacijos centro aplinkoje neleistinų viršijimų nebuvo aptikta. Savaitgalio matavimuose didţiausias ekvivalentinis garso lygis buvo išmatuotas prie prekybos centro „Saulės miestas“. Gyvenamojoje zonoje prie geleţinkelio stoties ekvivalentinis garso lygis, lyginant su autotransporto skleidţiamais lygiais viršijamas net 12 dBA.
Sound levels were measured in month of May. Research test sites were near residential areas next to shopping centres „Saulės miestas“, „Bruklinas“, „Akropolis“, „Tilţė“, also in residential area near city railway station, in Šiauliai rehabilitation centre area, nearby J.Janonis gymnasium, whereat majority of noise is caused by motor transport, and next to Jovaras progymnasium. In comparison all the measurements have been conducted also in weekend. Highest equivalent sound level was measured near J. Janonis gymnasium. Average sound levels were detected in residential areas near shopping centres „Tilţė“, „Akropolis“, „Bruklinas“ and also in Jovaras progymnasium area, in which the equivalent sound level was exceeded by 1-4 dBA respectively. The sound levels in area near Šiauliai rehabilitation centre did not exceed the limits. The results that were conducted in weekend showed that the highest equivalent sound level was measured near the shopping centre „Saulės miestas“. Utmost sound level was measured near the railway station, where equivalent sound level was exceeded by 12 dBA. Specific noise of the railway transport is the major cause for it.
Style APA, Harvard, Vancouver, ISO itp.
8

Horikawa, Carla Shizumi. "Transporte e morfologia de esquemas de tintas epóxi poliamina equivalentes à base de solvente e água". Universidade Federal de São Carlos, 2003. https://repositorio.ufscar.br/handle/ufscar/6370.

Pełny tekst źródła
Streszczenie:
Made available in DSpace on 2016-06-02T20:36:08Z (GMT). No. of bitstreams: 1 DissCSH.pdf: 1758353 bytes, checksum: d3f847407a82ae2f5dae75fdfa8f23d8 (MD5) Previous issue date: 2003-07-21
In the present work, anticorrosive properties of solvent borne and water based epoxy polyamine coatings were studied comparatively. First these studies were performed for the individual layers of these coatings, i.e., primer, under coating and topcoat, and, finally, for the set of the layers, which was named complete scheme (for both kinds of epoxy polyamine coatings). In the case of primers, the ionic migration resistance was evaluated, and the resistivity of solvent borne epoxy polyamine coating primer (PS) was bigger than that of water based epoxy polyamine coating primer. In water absorption studies, the individual layers and the complete scheme of the solvent borne epoxy polyamine coating had smaller values than those of the water based epoxy polyamine coatings. In the water transport studies, the individual layers and the complete scheme of the solvent borne epoxy polyamine coating had permeation coefficients smaller than those of the water based epoxy polyamine coating. The oxygen transport also was studied and, one more time, the individual layers of the solvent borne epoxy polyamine coating had permeation coefficients smaller than those of the water based epoxy polyamine coating. However, for the complete scheme, the water based epoxy polyamine coating permeation coefficient was smaller than the solvent borne epoxy polyamine coating one, both presented permeation values smaller than the individuals layers.
Neste trabalho foram estudadas as propriedades anticorrosivas das tintas epóxi-poliamina á base de solvente comparativamente com seu equivalente aquoso. Primeiramente, o estudo foi realizado nas camadas individuais que constituíam as tintas, ou seja, tinta de base ou primer, intermediário e acabamento e, finalmente, no conjunto, que foi denominado por esquema completo para ambos tipos de tintas. No caso dos primers avaliou-se a resistência à migração iônica, onde o primer solvente (PS) apresentou maior resistividade. O estudo de absorção de água tanto nas camadas individuais como no esquema completo das tintas epóxi poliamina à base de solvente apresentaram menores valores em relação as tintas à base de água. No estudo de transporte de água, as camadas individuais e o esquema completo das tintas epóxi poliamina à base de solvente apresentaram coeficientes de permeação menores do que os das tintas à base de água. O transporte de oxigênio também foi estudado e, mais uma vez, as camadas individuais apresentaram menores coeficientes de permeação para a tinta epóxi poliamina à base de solvente. No entanto, em relação aos esquemas completos, o conjunto à base de água apresentou menor coeficiente de permeação em relação àquele à base de solvente, ambos apresentaram coeficientes de permeação menores que os das camadas individuais.
Style APA, Harvard, Vancouver, ISO itp.
9

Palakurthi, Nikhil Kumar. "Direct Numerical Simulation of Liquid Transport Through Fibrous Porous Media". University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881191.

Pełny tekst źródła
Style APA, Harvard, Vancouver, ISO itp.
10

Llerar, Meza Gerónimo. "Upscaling nonreactive solute transport". Doctoral thesis, Universitat Politècnica de València, 2009. http://hdl.handle.net/10251/5848.

Pełny tekst źródła
Streszczenie:
This thesis focuses on solute transport upscaling. Upscaling of solute transport is usually required to obtain computationally efficient numerical models in many field applications such as, remediation of aquifers, environmental risk to groundwater resources or the design of underground repositories of nuclear waste. The non-Fickian behavior observed in the field, and manifested by peaked concentration profiles with pronounced tailing, has questioned the use of the classical advection-dispersion equation to simulate solute transport at field scale using numerical models with discretizations that cannot capture the field heterogeneity. In this context, we have investigated the use of the advection-dispersion equation with mass transfer as a tool for upscaling solute transport in a general numerical modeling framework. Solute transport by groundwater is very much affected by the presence of high and low water velocity zones, where the contaminant can be channelized or stagnant. These contrasting water velocity zones disappear in the upscaled model as soon as the scale of discretization is larger that the size of these zones. We propose, for the modeling solute transport at large scales, a phenomenological model based on the concept of memory functions, which are used to represent the unresolved processes taking place within each homogenized block in the numerical models. We propose a new method to estimate equivalent blocks, for which transport and mass transfer parameters have to be provided. The new upscaling technique consists in replacing each heterogeneous block by a homogeneous one in which the parameters associated to a memory functions are used to represent the unresolved mass exchange between highly mobile and less mobile zones occurring within the block. Flow upscaling is based on the Simple Laplacian with skin, whereas transport upscaling is based in the estimation of macrodispersion and mass transfer parameters as a result of the interpretation of the r
Llerar Meza, G. (2009). Upscaling nonreactive solute transport [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/5848
Palancia
Style APA, Harvard, Vancouver, ISO itp.
11

Joana, Geórgia Santos. "Estudo do alcance de elétrons com energias entre 110 eV e 50 KeV". CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2006. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=47.

Pełny tekst źródła
Streszczenie:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Existe um grande número de estudos que examina a dependência entre energia e alcance para elétrons com energias desde alguns keVs até centenas de MeVs. Porém, a descrição quantitativa do transporte de elétrons de baixa energia é um problema complexo, especialmente devido à não disponibilidade de dados confiáveis para as seções de choque dos diferentes mecanismos por meio dos quais elétrons interagem com a matéria. Uma vez que os modelos analíticos de transporte de elétrons ou são incompletos ou apresentam dificuldades até o momento intransponíveis, os códigos de Monte Carlo têm sido a alternativa adotada nestas abordagens e são hoje extensivamente utilizados. É sabido que na interação de radiações ionizantes com o tecido vivo podem ocorrer danos severos em estruturas nos níveis celular e sub-celular. Uma vez que a transferência de energia de radiações ionizantes para o meio ocorre predominantemente através da interação dos elétrons secundários produzidos por esta com o material, existe um interesse especial na determinação da relação entre energia inicial e alcance para elétrons; especialmente os de baixa energia. Neste trabalho é estudada a relação entre energia inicial e alcance em meio biológico para elétrons com energias entre 110 eV e 50 keV. Para tal foi utilizado o código de Monte Carlo PENELOPE com o qual foram realizadas simulações do transporte de elétrons de baixa energia (110 eV a 50 keV) e dos fótons secundários gerados por estes provenientes de uma fonte monoenergética isotrópica localizada no interior de um meio tecido equivalente homogêneo. A partir daí, as grandezas de interesse foram calculadas e analisadas.
Style APA, Harvard, Vancouver, ISO itp.
12

Kuparowitz, Tomáš. "Transport a ukládání náboje ve struktuře superkondenzátoru". Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-364610.

Pełny tekst źródła
Streszczenie:
Práce se zabývá studiem superkondenzátorů (SC). Výstupem je detailní studie principů přenosu náboje ve struktuře SC, ukládání energie a nový náhradní model SC, který je založen na fyzikálních zákonitostech a principech SC. Dále byl vytvořen matematický model SC, který popisuje chování náboje v jeho aktivní vrstvě. SC byly testovány metodami umělého stárnutí. Závislosti poklesu parametrů SC vlivem různých metodik stárnutí jsou v práci shrnuty.
Style APA, Harvard, Vancouver, ISO itp.
13

Hartikka, Alice, i Simon Nordenhög. "Emission Calculation Model for Vehicle Routing Planning : Estimation of emissions from heavy transports and optimization with carbon dioxide equivalents for a route planning software". Thesis, Linköpings universitet, Energisystem, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-178065.

Pełny tekst źródła
Streszczenie:
The transport sector is a major cause of emissions both in Sweden and globally. This master thesis aims to develop a model for estimating emissions from heavy transport on a specific route. The emissions can be used in a route planning software and help the driver choose a route that contributes to reduced emissions. The methodology was to investigate attributes, like vehicle-related attributes and topography, and their impact on transport emissions. The carbon dioxide, methane and nitrous oxide emissions were converted into carbon dioxide equivalents, which were incorporated as one cost together with a precalculated driving time as a second cost in a multi objective function used for route planning. Different tests were conducted to investigate the accuracy and the usability of the model. First, a validation test was performed, where the optimized routes were analyzed. The test showed that the model was more likely to choose a shorter route in general. The fuel consumption values largely met expectations towards generic values and measurements, that were gathered from research. A second test of the model made use of the driving time combined with the emissions in a multi objective function. In this test, a weighting coefficient was varied and analyzed to understand the possibility to find a value of the coefficient for the best trade-off. The result showed that the model generates different solutions for different coefficients and that it is possible to find a suitable trade-off between the driving time and emissions. Therefore, this study shows that there is a possibility to combine emission with other objectives such as driving time for route optimization. Finally, a sensitivity analysis was performed, where attribute factors and assumptions were varied to see how sensitive they were and, in turn, how much a change would impact the calculated emissions. The result from the sensitivity analysis showed that the changes in topography-attributes had less impact than changes on vehicle-related attributes. In conclusion, this thesis has built a foundation for route planning, based on the environmental aspect, for heavy transports.
Style APA, Harvard, Vancouver, ISO itp.
14

Pelčák, Jaromír. "Transport elektrického náboje v tantalovém kondenzátoru". Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-233579.

Pełny tekst źródła
Streszczenie:
The task of the thesis was studding of tantalum capacitors with solid electrolytes properties. Ta – Ta2O5 – MnO2 capacitor by its construction represents MIS structure, where tantalum anode has metal conductivity and MnO2 cathode is semiconductor. Isolation layer consists of tantalum pentoxide Ta2O5 with relative permitivity r = 27. Dielectric thickness is typically in range from 30 to 150nm. The capacitor charge is not only stored and accumulated on electrodes but also in localised states (oxide vacancies) in isolation layer. The capacitor connected in normal mode represents MIS structure polarized in reveres direction when the applied voltage higher potential barrier between semiconductor - MnO2 cathode and isolation of Ta2O5. The transport of charge carriers via isolation layer is determined by Poole-Frenkel mechanisms and tunnelling. Poole-Frenkel mechanism of charge transport is dominant in low intensity of electric field. Tunnelling determines current at higher electric field intensity. During low intensity of electric field ohmic component is also presented which is determined by volume of resistance of impurities in isolation layer due to donor states of oxygen vacancies. Based on the modelling of measured VA characteristics is possible to estimate determine dielectric thickness of Ta2O5 and determine share of Poole-Frenkelov and tunnel current and charge transportation. The thesis is described charge transport and charge concentration on tantalum capacitor in low frequency area and analysis of capacitor behaviour at frequency band. The first impulse for the thesis was an effort to create equivalent circuit diagram of tantalum capacitor in respect of its physical and electrical behaviour. There is an opportunity to study and determine electric charge transport and its accumulation based on the equivalent circuit diagram structure. There is also a chance to define and trace potential barriers and charge distribution in the capacitor structure based on an measurement and carried out experiments. This methodology and analysis consists of electrical characteristic determination to create physical model of the capacitor describing it function, properties and behaviour.
Style APA, Harvard, Vancouver, ISO itp.
15

Demir, Emrah, Martin Hrusovsky, Werner Jammernegg i Woensel Tom Van. "Green intermodal freight transportation: bi-objective modelling and analysis". Taylor & Francis, 2019. http://epub.wu.ac.at/6990/1/00207543.2019.pdf.

Pełny tekst źródła
Streszczenie:
Efficient planning of freight transportation requires a comprehensive look at wide range of factors in the operation and man- agement of any transportation mode to achieve safe, fast, and environmentally suitable movement of goods. In this regard, a combination of transportation modes offers flexible and environmentally friendly alternatives to transport high volumes of goods over long distances. In order to reflect the advantages of each transportation mode, it is the challenge to develop models and algorithms in Transport Management System software packages. This paper discusses the principles of green logistics required in designing such models and algorithms which truly represent multiple modes and their characteristics. Thus, this research provides a unique practical contribution to green logistics literature by advancing our understanding of the multi-objective planning in intermodal freight transportation. Analysis based on a case study from hinterland intermodal transportation in Europe is therefore intended to make contributions to the literature about the potential benefits from com bining economic and environmental criteria in transportation planning. An insight derived from the experiments conducted shows that there is no need to greatly compromise on transportation costs in order to achieve a significant reduction in carbon-related emissions.
Style APA, Harvard, Vancouver, ISO itp.
16

Repina, Maria. "Modélisation du transport réactif dans les milieux fracturés de verre nucléaire d’intérêt industriel". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM007/document.

Pełny tekst źródła
Streszczenie:
Comprendre l'altération du verre nucléaire dans un réseau de fracture au sein d'un bloc de verre vitrifié est important pour la sûreté du conditionnement des déchets nucléaires (quantification des risques associés au relâchement des radionucléides). L’évaluation de la performance du stockage géologique des déchets nucléaires passe obligatoirement par la modélisation de l’altération aqueuse d’un bloc de verre nucléaire fracturé, l’échelle de temps envisagée (plusieurs milliers d’années) dépassant toute possibilité d’expérience directe. Cette thèse vise donc à combler le fossé entre les simulations d'écoulement et de transport à l'échelle du réservoir et la modélisation à l'échelle micrométrique des processus interfaciaux verre-eau, en apportant l'évaluation quantitative de la dégradation aqueuse du verre à l'échelle d’un bloc.Pour aborder ce problème, les objectifs principaux de cette thèse ont été fixés comme suit : (i) la reproduction des résultats expérimentaux obtenus précédemment (pour quelques fractures modélisées de manière discrète en mode diffusif), (ii) l’analyse de l'impact des géométries de fractures sur la quantité de verre altéré pour quelques fissures modélisées de manière discrète, (iii) l’étude de la possibilité d'adaptation du modèle géochimique à la modélisation dans le cadre de l’approche milieu équivalent, (iv) la mise au point d'une méthodologie de caractérisation, (v) la modélisation géostatistique et géométrique de réseau de fractures à l’échelle d’un conteneur de verre, (vi) le calcul des paramètres équivalents diffusifs, hydrauliques et les paramètres qui contrôlent la cinétique de dissolution de verre, et au final, (vii) la modélisation de transport réactif à l’échelle d’un conteneur.À titre illustratif, la méthodologie de la caractérisation de réseau fracturé proposée, basée sur le traitement des images, a été appliquée aux images bidimensionnelles (2D) de haute résolution de deux blocs de verre. Cette application a permis de mettre en œuvre à la fois les données directes obtenues par mesures des paramètres d’un réseau fracturé de verre vitrifié et les données indirectes explicatives issues des simulations thermomécaniques. L’application a abouti à la création de multiples réalisations de tessellation de réseaux fracturés équivalents qui ont ensuite été utilisées comme représentations physiques pour les calculs de la perméabilité équivalente, de la diffusion équivalente et des paramètres contrôlant la cinétique de dissolution de verre borosilicaté. L'évolution de la quantité de verre altéré obtenue en effectuant la modélisation de transport réactif appliquée à plusieurs réalisations de la tessellation de réseau fracturé équivalent a été comparée aux données expérimentales d’un essai d'altération aqueuse d'un conteneur non radioactif de verre nucléaire. Les résultats montrent que la méthodologie conçue offre une opportunité pour mieux comprendre l'impact de la fracturation sur l'altération aqueuse du verre vitrifié et constitue un outil fiable permettant de prendre en compte différents scénarios d'évolution du stockage
Understanding the alteration of nuclear glass in a fracture network of a vitrified glass block is important for the safe conditioning of nuclear waste (quantification of the risks associated with radionuclide release). Performance assessment of geological nuclear waste repositories entails modelling of the long-term evolution of the fractured nuclear glass block aqueous alteration, because the considered time scale, of several thousands of years, is beyond the range of any direct experimental perspectives. This dissertation aims then to bridge the gap between the reservoir-scale flow and transport simulations and the micron-scale modeling of the glass-water interfacial processes, by bringing the quantitative evaluation of the glass aqueous degradation at the block scale.To tackle this issue, the main objectives of this thesis were fixed as follows: (i) reproduction of the experimental results previously obtained (for some fractures modeled in a discrete way in the diffusive mode),(ii) analysis of the impact of fractures geometries on the quantity of altered glass at the scale of some fractures modeled in a discrete way, (iii) investigation of the possibilities of the geochemical model adaptation for the equivalent homogenous modeling, (iv) establishment of a methodology for glass block fracture network characterization, (v) geostatistical and geometric modeling, (vi) calculation of the equivalent diffusive, hydraulic and glass dissolution kinetics controlling properties and (vii) upcoming reactive transport modeling at the scale of one canister.As an illustrative example, the proposed image processing-based fracture network characterization methodology was applied to two-dimensional (2D) high-resolution images of two blocks of vitrified glass. This application brought into service both hard data obtained by direct measurement of the fracture network and soft physics-based explanatory data and resulted in the creation of multiple realizations of fracture network equivalent tessellation that were further used as physical representation for the calculation of the equivalent hydraulic, diffusive, and alteration kinetics - controlling properties. The evolution of the quantity of altered glass obtained by conducting reactive transport modeling applied to several realizations of the equivalent fracture network tessellation was compared with the experimental data of the aqueous alteration test of a non-radioactive full-scale nuclear glass canister. The results show that implementation of the devised procedure presents an opportunity for better understanding the impact of fracturing on aqueous alteration of borosilicate glass and provides a reliable tool enabling different scenarios of repository evolution to be accounted for
Style APA, Harvard, Vancouver, ISO itp.
17

Walker, Scottie. "Spectrally-matched neutron detectors designed using computational adjoint SN for plug-in replacement of Helium-3". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49093.

Pełny tekst źródła
Streszczenie:
Neutron radiation detectors are an integral part of the Department of Homeland Security (DHS) efforts to detect the illicit trafficking of radioactive or special nuclear materials into the U.S. In the past decade, the DHS has deployed a vast network of radiation detection systems at various key positions to prevent or to minimize the risk associated with the malevolent use of these materials. The greatest portion of this detection burden has been borne by systems equipped with 3He because of its highly desirable physical and nuclear properties. However, a dramatic increase in demand and dwindling supply, combined with a lack of oversight for the existing 3He stockpile has produced a critical shortage of this gas which has virtually eliminated its viability for detector applications. A number of research efforts have been undertaken to develop suitable 3He replacements; however, these studies have been solely targeted toward simple detection cases where the overall detection efficiency is the only concern. For these cases, an insertion of additional detectors or materials can produce reaction rates that are sufficient, because the neutron spectral response is essentially irrelevant. However, in applications such as safeguards, non-proliferation efforts, and material control and accountability programs (MC&A), a failure to use detectors that are spectrally matched to 3He can potentially produce dire consequences. This is because these more difficult detection scenarios are associated with fissile material assessments for 239Pu and other actinides and these analyses have almost universally been calibrated to an equivalent 3He response. In these instances, a “simple” detector or material addition approach is neither appropriate nor possible, due to influences resulting from the complex nature of neutron scattering in moderators, cross sections, gas pressure variations, geometries, and surrounding structural interference. These more challenging detection cases require a detailed computational transport analysis be performed for each specific application. A leveraged approach using adjoint transport computations that are validated by forward transport and Monte Carlo computations and laboratory measurements can address these more complex detection cases and this methodology was utilized in the execution of the research. The initial task was to establish the fidelity of a computational approach by executing radiation transport models for existing BF3 and 3He tubes and then comparing the modeling results to laboratory measurements made using these identical devices. Both tubes were 19.6 cm in height, 1-inch in diameter, and operated at 1 and 4 atm pressure respectively. The models were processed using a combination of forward Monte Carlo and forward and adjoint 3-D discrete ordinates (SN) transport methods. The computer codes MCNP5 and PENTRAN were used for all calculations of a nickel-shielded plutonium-beryllium (PuBe) source term that provided a neutron output spectra equivalent to that of weapons-grade plutonium (WGPu). Once the computational design approach was validated, the adjoint SN method was used to iteratively identify six distinct plug-in models that matched the neutron spectral response and reaction rate of a 1-inch diameter 3He tube with a length of 10 cm and operating at 4 atm pressure. The equivalent designs consist of large singular tubes and dual tubes containing BF3 gas, 10B linings, and/or 10B-loaded polyvinyl toluene (PVT). The reaction rate for each plug-in design was also verified using forward PENTRAN and MCNP5 calculations. In addition to the equivalent designs, the adjoint method also yielded various insights into neutron detector design that can lead to additional designs using a combination of different detector materials such as BF3/10B-loaded PVT, 10B-lined tubes/10B-loaded PVT, etc.
Style APA, Harvard, Vancouver, ISO itp.
18

Repina, Maria. "Modélisation du transport réactif dans les milieux fracturés de verre nucléaire d’intérêt industriel". Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM007.

Pełny tekst źródła
Streszczenie:
Comprendre l'altération du verre nucléaire dans un réseau de fracture au sein d'un bloc de verre vitrifié est important pour la sûreté du conditionnement des déchets nucléaires (quantification des risques associés au relâchement des radionucléides). L’évaluation de la performance du stockage géologique des déchets nucléaires passe obligatoirement par la modélisation de l’altération aqueuse d’un bloc de verre nucléaire fracturé, l’échelle de temps envisagée (plusieurs milliers d’années) dépassant toute possibilité d’expérience directe. Cette thèse vise donc à combler le fossé entre les simulations d'écoulement et de transport à l'échelle du réservoir et la modélisation à l'échelle micrométrique des processus interfaciaux verre-eau, en apportant l'évaluation quantitative de la dégradation aqueuse du verre à l'échelle d’un bloc.Pour aborder ce problème, les objectifs principaux de cette thèse ont été fixés comme suit : (i) la reproduction des résultats expérimentaux obtenus précédemment (pour quelques fractures modélisées de manière discrète en mode diffusif), (ii) l’analyse de l'impact des géométries de fractures sur la quantité de verre altéré pour quelques fissures modélisées de manière discrète, (iii) l’étude de la possibilité d'adaptation du modèle géochimique à la modélisation dans le cadre de l’approche milieu équivalent, (iv) la mise au point d'une méthodologie de caractérisation, (v) la modélisation géostatistique et géométrique de réseau de fractures à l’échelle d’un conteneur de verre, (vi) le calcul des paramètres équivalents diffusifs, hydrauliques et les paramètres qui contrôlent la cinétique de dissolution de verre, et au final, (vii) la modélisation de transport réactif à l’échelle d’un conteneur.À titre illustratif, la méthodologie de la caractérisation de réseau fracturé proposée, basée sur le traitement des images, a été appliquée aux images bidimensionnelles (2D) de haute résolution de deux blocs de verre. Cette application a permis de mettre en œuvre à la fois les données directes obtenues par mesures des paramètres d’un réseau fracturé de verre vitrifié et les données indirectes explicatives issues des simulations thermomécaniques. L’application a abouti à la création de multiples réalisations de tessellation de réseaux fracturés équivalents qui ont ensuite été utilisées comme représentations physiques pour les calculs de la perméabilité équivalente, de la diffusion équivalente et des paramètres contrôlant la cinétique de dissolution de verre borosilicaté. L'évolution de la quantité de verre altéré obtenue en effectuant la modélisation de transport réactif appliquée à plusieurs réalisations de la tessellation de réseau fracturé équivalent a été comparée aux données expérimentales d’un essai d'altération aqueuse d'un conteneur non radioactif de verre nucléaire. Les résultats montrent que la méthodologie conçue offre une opportunité pour mieux comprendre l'impact de la fracturation sur l'altération aqueuse du verre vitrifié et constitue un outil fiable permettant de prendre en compte différents scénarios d'évolution du stockage
Understanding the alteration of nuclear glass in a fracture network of a vitrified glass block is important for the safe conditioning of nuclear waste (quantification of the risks associated with radionuclide release). Performance assessment of geological nuclear waste repositories entails modelling of the long-term evolution of the fractured nuclear glass block aqueous alteration, because the considered time scale, of several thousands of years, is beyond the range of any direct experimental perspectives. This dissertation aims then to bridge the gap between the reservoir-scale flow and transport simulations and the micron-scale modeling of the glass-water interfacial processes, by bringing the quantitative evaluation of the glass aqueous degradation at the block scale.To tackle this issue, the main objectives of this thesis were fixed as follows: (i) reproduction of the experimental results previously obtained (for some fractures modeled in a discrete way in the diffusive mode),(ii) analysis of the impact of fractures geometries on the quantity of altered glass at the scale of some fractures modeled in a discrete way, (iii) investigation of the possibilities of the geochemical model adaptation for the equivalent homogenous modeling, (iv) establishment of a methodology for glass block fracture network characterization, (v) geostatistical and geometric modeling, (vi) calculation of the equivalent diffusive, hydraulic and glass dissolution kinetics controlling properties and (vii) upcoming reactive transport modeling at the scale of one canister.As an illustrative example, the proposed image processing-based fracture network characterization methodology was applied to two-dimensional (2D) high-resolution images of two blocks of vitrified glass. This application brought into service both hard data obtained by direct measurement of the fracture network and soft physics-based explanatory data and resulted in the creation of multiple realizations of fracture network equivalent tessellation that were further used as physical representation for the calculation of the equivalent hydraulic, diffusive, and alteration kinetics - controlling properties. The evolution of the quantity of altered glass obtained by conducting reactive transport modeling applied to several realizations of the equivalent fracture network tessellation was compared with the experimental data of the aqueous alteration test of a non-radioactive full-scale nuclear glass canister. The results show that implementation of the devised procedure presents an opportunity for better understanding the impact of fracturing on aqueous alteration of borosilicate glass and provides a reliable tool enabling different scenarios of repository evolution to be accounted for
Style APA, Harvard, Vancouver, ISO itp.
19

Nag, Subhra Sankar. "Stabilization of Hypoxia Inducible Factor by Cobalt Chloride Can Alter Renal Transepithelial Transport". Cleveland State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1536931227678351.

Pełny tekst źródła
Style APA, Harvard, Vancouver, ISO itp.
20

Boutahar, Jaouad. "Méthodes de réduction et de propagation d'incertitudes : application à un mùodèle de Chimie-Transport pour la modélisation et la stimulation des impacts". Marne-la-vallée, ENPC, 2004. https://pastel.archives-ouvertes.fr/tel-00007557.

Pełny tekst źródła
Streszczenie:
Dans une modélisation intégrée des impacts, l'objectif est de tester plusieurs scénarios d'entrées de modèle et/ ou d'identifier l'effet de l'incertitude des entrées sur les sorties de modèle. Dans les deux cas, un grand nombre de simulations de modèle sont nécessaires. Cela reste bien évidemment infaisable avec un modèle de Chimie-Transport à cause du temps CPU demandé. Pour surmonter cette difficulté, deux approches ont été étudiées dans cette thèse. La première consiste à construire un modèle réduit. Deux techniques ont été utilisées : la première est la méthode POD (Proper Orthogonal Decomposition) liée au comportement statistique du système. La seconde méthode est une méthode efficace de prétabulation fondée sur la troncature d'un développement multivariables de la relation Entrées/ sorties associé au modèle. La seconde est relative à la réduction du nombre de simulations demandé par la méthode Monte-Carlo classique de propagation d'incertitude. La technique utilisée ici est basée sur une représentation d'une sortie de modèle incertaine comme un développement de polynômes orthonormaux de variables d'entrées. Un autre point clé dans la modélisation intégrée d'impacts est de développer des stratégies de réduction des émissions en calculant des matrices de transfert sur plusieurs années de simulation. Une méthode efficace de calcul de ces matrices a été ainsi développée, notamment en définissant des scénarios "chimiquement" représentatifs. L'ensemble de ces méthodes a été appliqué au modèle POLAIR3D, modèle de Chimie-Transport développé dans le cadre de cette thèse
Style APA, Harvard, Vancouver, ISO itp.
21

Alves, Matheus Carvalho. "Cálculos dos coeficientes de conversão de dose equivalente e dose efetiva em termos da fluência para prótons utilizando simulador antropomórfico híbrido feminino e masculino na postura vertical e sentada e o código MCNPX". Pós-Graduação em Física, 2014. http://ri.ufs.br:8080/xmlui/handle/123456789/5299.

Pełny tekst źródła
Streszczenie:
Ionizing radiation has a harmful potential to humans, so the protection of workers and public individuals is fundamental for the safe use of radiation in different practical purpose. Therefore, is necessary to set exposure limits to radiation using dosimetric quantities such as equivalent dose and effective dose. However equivalent and effective dose are not directly measured, so it is necessary calculate conversion coefficients (CC¡¦s) which relates this quantities with measured quantities such as particles fluence. In the literature exposure scenarios are, in general, built with simulator in the standing posture, but exposure of individuals to radiation can occur in other posture, so the aim of this work is calculate and compare the absorbed dose-to-fluence conversion coefficients (DT/ ¶) and effective dose-to-fluence conversion coefficients (E/ ¶) for the female hybrid simulator (UFHADF) in the standing and sitting posture and for the male hybrid simulator (UFHADM) in the standing posture using the Monte Carlo code MCNPX for monoenergetic protons from 2 MeV to 10 GeV and in the antero posterior (AP), postero anterior (PA), right lateral (RLAT), left lateral (LLAT), rotational (ROT) and isotropic (ISO) exposure scenarios. Comparing the CC¡¦s between standing and sitting posture of UFHADF simulator, it was observed that in the AP and PA irradiation geometry the relative differences in the head, chest and the superior abdomen organs were not relevant. However in the others irradiation geometries, for some organs in the abdomen and chest region differences in CC¡¦s were observed. The organs that presented more differences in CC¡¦s were uterus (538 % in RLAT geometry), bladder (80 % in ROT geometry) and ovaries (2861 % in LLAT geometry) since this organs are located in the lower abdominal region, in which the position of legs and arms are different between standing and sitting posture. Calculate the DT/ ¶ e E/ ¶ nconversion coefficients using simulator in the sitting posture is important to estimate more precisely the dose in individuals exposed to radiation in actual scenarios.
As radiacoes ionizantes tem um potencial danoso aos seres humanos e, por isso, a protecao de trabalhadores e de individuos do publico e essencial para o uso seguro das mesmas nos diversos fins praticos. Desta forma, e necessario estabelecer limites de exposicao com relacao a estes tipos de radiacao e, para tanto, sao utilizadas grandezas dosimetricas como a dose equivalente e a dose efetiva. Como a dose equivalente e a dose efetiva nao sao medidas diretamente faz-se necessario o calculo de coeficientes de conversao (CC¡¦s) em ambito computacional, pois eles relacionam estas grandezas com grandezas mensuraveis, como a fluencia de particulas. Como na literatura os cenarios de exposicao sao, em geral, construidos com simuladores implementados na postura vertical e nem sempre a exposicao de individuos a radiacao ocorre nessa postura, esse trabalho tem como finalidade, utilizar o codigo de transporte de radiacao Monte Carlo MCNPX e o simulador antropomorfico adulto feminino UFHADF nas posturas vertical e sentada e o simulador masculino UFHADM na postura vertical para obter e comparar os coeficientes de conversao para dose absorvida (DT) e dose efetiva (E) em termos da fluencia (£X) (DT/£X e E/£X) para protons monoenergeticos de 2 MeV ate 10 GeV, para os cenarios de irradiacao antero-posterior (AP), postero-anterior (PA), lateral direito (RLAT), lateral esquerdo (LLAT), rotacional (ROT) e isotropico (ISO). Na comparacao dos CC¡¦s entre o simulador UFHADF nas posturas vertical e sentada, foi observado que a diferenca relativa entre os CC¡¦s nos orgaos da regiao da cabeca, do torax e do abdomen superior nao foram relevantes nas geometrias de irradiacao AP e PA. Ja nas demais geometrias de irradiacao, para alguns orgaos da regiao do abdomen e torax diferencas nos CC¡¦s foram observadas. Os orgaos que mais apresentaram diferencas nos CC¡¦s foram o utero (538 % na geometria RLAT), a bexiga (80 % na geometria ROT) e os ovarios (2861 % na geometria LLAT) que se localizam na regiao abdominal inferior, regiao onde ha a diferenca na posicao das pernas e bracos do simulador. Assim, o calculo dos coeficientes de conversao DT/ ¶ e E/ ¶ utilizando simuladores antropomorficos na postura sentada e importante para uma estimativa mais precisa da dose em individuos submetidos a cenarios reais de exposicao a radiacao.
Style APA, Harvard, Vancouver, ISO itp.
22

Dahlberg, Erik, i Weronica Fohlén. "Hållbarhetsutvärdering - LCSA Analys : av trucksystem inom intern materialhantering". Thesis, Högskolan i Skövde, Institutionen för handel och företagande, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15175.

Pełny tekst źródła
Streszczenie:
Allt fler organisationer väljer att jobba med hållbar utveckling, på grund av att det kan ses som en konkurrenskraft. Att arbeta med hållbar utveckling kan innefatta att utföra hållbarhetsutvärderingar, vilket kan göras genom metoden LCSA analys. Syftet med det här arbetet är att utvärdera och analysera ett producerande företags nuvarande klimatpåverkan sett till koldioxidekvivalentutsläpp från intern materialhantering som sker med dieseltruckar. Vidare syftar även arbetet till att visa hur en hållbarhetsutvärdering kan utföras för att påvisa ekologisk, ekonomisk samt social påverkan. I arbetet utförs en hållbarhetsutvärdering av trucksystem, för att identifiera det teoretiskt bästa alternativet, i jämförelse med ett fallföretags nuläge. Den metod som används för hållbarhetsutvärderingen är LCSA analys. Utöver resultatet från hållbarhetsutvärderingen tas även hänsyn till gränssnittet mellan teoretiskt och praktiskt bästa trucksystemalternativ.  Fallföretaget Volvo GTO i Skövde, har i dagsläget 18 dieseldrivna motviktstruckar, vilka har olika kapacitet och varierande arbetsuppgifter. Det nuvarande drivmedlet för samtliga truckar är Diesel Mk1. Fallföretagets flöden i dagsläget ställer generellt höga krav på truckarnas tekniska kapacitet gällande exempelvis åkhastighet, körning i uppförslutning, dragkraft samt lyft- och sänkhastighet. De 18 dieseltruckarna bidrog under år 2017 med ett klimatpåverkande utsläpp om cirka 237 ton koldioxidekvivalenter, sett till hela livscykeln för Diesel Mk1 samt truckflottans totala drifttider.  Gällande hållbarhetsutvärderingen LCSA analys, utförs den på trucksystem drivna av Diesel Mk1, HVO-Diesel, blybatterier samt litiumjonbatterier inom kapaciteterna 3,5, 5 och 8 ton. Analysen tar hänsyn till de tre pelarna inom hållbar utveckling.  Vidare tas hänsyn till trucksystemens tekniska specifikationer, vilket jämförs mot den nuvarande dieseltruckflottan. Generellt kan en lägre teknisk prestanda ses hos de eldrivna trucksystemen, vilket kan påverka möjligheten att implementera de hos fallföretaget. Teoretiskt lägst ekologisk och social påverkan kan ses hos de litiumjonbatteridrivna trucksystemen, lägst påverkan inom den ekonomiska pelaren har blybatteridrift. Ställt mot fallföretagets nuvarande flöden och behov, rekommenderar författarna HVO-Dieseldrivna trucksystem, då de har samma tekniska kapacitet samt lägre ekologisk och social påverkan. Avgränsningar har gjorts för analyserna i rapporten, gällande processgränser och påverkande faktorer. För framtida hållbarhetsutvärderingar rekommenderar författarna att större processgränser och fler påverkande faktorer tas hänsyn till, för att identifiera samtlig påverkan inom pelarna. I rapporten återfinns exempel på påverkan utanför valda processgränser, såsom utsläpp som påverkar över tid och exploatering. Under arbetets gång har informationsgap uppmärksammats inom olika områden. När det gäller forskning kring hållbarhetsutvärderingar saknas beprövade metoder. Därför efterfrågas enklare analysmetoder inom hållbar utveckling. Gap i forskning angående truckteori är något som också uppmärksammats.
The amount of organizations that choose to work with sustainability is increasing due to the potential competitiveness it causes. Working with sustainability may include sustainability evaluations, which can be done through the LCSA analysis method. The purpose of this report is to evaluate and analyze a manufacturing company's current climate impact due to carbon dioxide equivalent emissions from diesel-powered forklifts within internal material handling. Further, the report aims to illustrate how a sustainability evaluation can be conducted to identify ecological, economic and social impact. In the report, a sustainability evaluation of forklift systems is performed to identify the theoretically best alternative, compared to a case company's current situation. The method used for the sustainability evaluation is LCSA analysis. In addition to the results of the sustainability evaluation, the interface between theoretically and practically best forklift system alternatives is considered.  The case company Volvo GTO in Skövde, currently have 18 diesel-powered forklifts, which have different capacities and functions. The current fuel for all forklifts is Diesel Mk1. The flows today generally set high demands on the forklifts technical capacity, for example on, travel speed, climbing ability, traction force and lifting and lowering speed. In the year 2017, the 18 diesel-powered forklifts contributed with a climate impact of approximately 237 tonnes of carbon dioxide equivalents, considering the entire life cycle of Diesel Mk1 and the forklift fleets total run time.  Regarding the sustainability evaluation LCSA analysis, it is performed on forklift systems powered by Diesel Mk1, HVO-Diesel, lead acid batteries and lithium-ion batteries within the capacities 3.5, 5 and 8-tonne. The analysis considers the three pillars of sustainability. Further, the technical specifications of the forklift systems are considered and compared with the current diesel-powered fleet. Generally, a lower technical capacity can be seen in the electric forklift systems, which may affect the ability to implement those at the case company. Theoretically lowest ecological and social impact can be seen within the lithium-ion battery-powered forklift systems, the lowest impact on the economic pillar is seen in the lead acid battery systems. Based on the case company's current flows and demands, the authors recommend HVO-Diesel-powered forklift systems, as they have the same technical capabilities as well as lower ecological and social impacts. Limitations has been set for the reports analyzes, regarding process boundaries and impact indicators. For future sustainability evaluations, the authors recommend that wider process boundaries and more impact indicators are applied to identify the total impact within the pillars of sustainability. The report comprehends examples of impact beyond selected process boundaries, such as emissions affecting over time or exploitation. During the progress of this report, information gaps have been discovered in different areas. Regarding research of sustainability evaluations, proven methods are lacking. Therefore, established methods for evaluation are desired. A gap in research of forklift theory has also been noted.
Style APA, Harvard, Vancouver, ISO itp.
23

Maciel, Hugo Emerich. "Avaliação de modelos de permeabilidade em meios porosos não consolidados". Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9498.

Pełny tekst źródła
Streszczenie:
Conselho Nacional de Desenvolvimento Científico e Tecnológico
As simulações computacionais tem sido amplamente empregadas no estudo do escoamento darciano e não-darciano em meios porosos consolidados e não-consolidados. Neste trabalho, através de uma nova formulação para a equação de Forchheimer, foram identificadas duas novas propriedades denominados fator de comportamento do fluido, que atua paralelamente a permeabilidade, e permeabilidade equivalente global, resultado da relação anterior. Este comportamento foi estudado e validado através da implementação de um aparato experimental e um código computacional baseado no modelo de regressão-linear que, além disso, demonstrou que o escoamento, ainda que em regime não darciano, comporta-se linearmente como a equação de Darcy, ainda que o coeficiente angular desta diminuiu de acordo com a faixa do número de Reynolds atingida, sendo esta dependente do tipo de leito empregado. Ainda neste trabalho, foi implementado o método de otimização R2W para estimar os parâmetros da equação de Kozeny-Carman a partir de dados experimentais obtidos por Dias et al, a fim de simular o escoamento darciano em meios porosos. Por fim, foi alcançada excelente concordância entre os dados simulados pelo método R2W / equação de Kozeny-Carman e os dados reais.
Computer simulations have been widely used in the study of Darcys flow and non-Darcy porous media in consolidated and non-consolidated. In this work, through a new formulation for the Forchheimer equation, we have been identified two new called Fluid Factor Behavior properties, which acts parallel to permeability, and overall equivalent permeability result of the previous relationship. This behavior has been studied and validated through implementation of an experimental apparatus and a computer code based on the linear regression model, moreover, it demonstrated that flow, even in non darciano system behaves linearly as the Darcy, however, the slope of this decreased according to the range of Reynolds numbers reached, this being dependent on the type of bed used. Although this work was implemented R2W optimization method to estimate the parameters of Kozeny-Carman equation from experimental data provided in the literature in order to simulate the darciano flow in porous media. Finally, it achieved excellent agreement between the data simulated by R2W method / Kozeny-Carman equation and actual data.
Style APA, Harvard, Vancouver, ISO itp.
24

ANGELOCCI, LUCAS V. "Estudo de casos clínicos em radioterapia através do sistema de planejamento AMIGOBrachy". reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26926.

Pełny tekst źródła
Streszczenie:
Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-12-21T11:30:16Z No. of bitstreams: 0
Made available in DSpace on 2016-12-21T11:30:16Z (GMT). No. of bitstreams: 0
O sucesso de uma radioterapia depende do correto planejamento da dose a ser entregue ao volume alvo. Na braquiterapia, modalidade da radioterapia onde um radioisótopo selado é implantado intracavitariamente ou intersticialmente no paciente, há menos avanços em sistemas de planejamento de tratamento computacionais do que na teleterapia, amplamente mais utilizada nos serviços típicos. Porém, a braquiterapia, quando aplicável, é preferível por poupar tecidos sadios vizinhos de uma dose desnecessária. O AMIGOBrachy, um sistema de planejamento para braquiterapia de interface amigável, compatibilidade com outros sistemas comerciais em uso e integrado ao código MCNP6 (Monte Carlo N-Particle Transport Code v. 6) foi desenvolvido no Centro de Engenharia Nuclear do Instituto de Pesquisas Energéticas e Nucleares (CEN-IPEN) e atualmente está em processo de validação. Este trabalho contribuiu para este processo, avaliando três diferentes casos clínicos através do AMIGOBrachy com o formalismo do TG43 da AAPM (Associação Americana de Física Médica), protocolo que rege a dosimetria em braquiterapia, e comparando seus resultados com as distribuições de dose calculadas por outros sistemas comerciais consagrados: Varian BrachyVision TM (Varian Medical Systems; Palo Alto, CA, EUA) e Nucletron Oncentra® (Elekta; Estocolmo, Suécia). Os resultados obtidos estão dentro de uma faixa de concordância de ±10%, estando mais discrepantes em regiões muito próximas do aplicador, onde os sistemas de planejamento comerciais e o AMIGOBrachy divergem devido aos diferentes métodos de cálculo. Em pelo menos dois terços da região de interesse, porém, a dose concordou em uma faixa de ±3% para os três casos. Também foram realizadas simulações utilizando o formalismo do TG186 da AAPM, que considera heterogeneidades no tecido, para avaliar o impacto dos mesmos na dose. Em adição ao processo de validação, também foi realizado um estudo em braquiterapia oftálmica para posterior inserção de um módulo adicional ao AMIGOBrachy; para isso, um modelo de olho humano foi desenvolvido utilizando geometria UM (Unstructured Mesh), para validação com o código MCNP6, que apenas nesta versão demonstra um novo recurso capaz de simular uma geometria híbrida: parcialmente analítica, parcialmente UM. O modelo considera dez diferentes estruturas no olho humano: esclera, coroide, retina, corpo vítreo, córnea, câmara anterior, lente, nervo óptico, parede do nervo óptico, e um tumor definido de forma arbitrária crescendo da superfície externa do globo ocular em direção ao seu centro. Os resultados foram comparados com um modelo de olho puramente analítico modelado com o MCNP6 e tomado como referência. Os resultados foram satisfatórios em todas as simulações desenvolvidas, exceto para as estruturas do nervo óptico e sua parede, que devido ao seu pequeno tamanho e distância da fonte, mostraram erros relativos maiores, mas ainda menores que 10%, e não representam problema de preocupação clínica uma vez que recebem doses muito pequenas. Discutiu-se também a eficácia e problemas encontrados nessa nova capacidade do código MCNP de simular geometrias híbridas, uma vez que é recente e ainda apresenta deficiências, que tiveram que ser contornadas no presente trabalho.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Style APA, Harvard, Vancouver, ISO itp.
25

Roušar, Ladislav. "Meze pohybu a kvantifikace množství dnových splavenin pro štěrkonosné toky". Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-234551.

Pełny tekst źródła
Streszczenie:
Doctoral thesis in detail and comprehensively deals with mechanic of incipient bedload motion for gravel-bed rivers. This study based on theoretical knowledge, experimental researches, numerical models and field survey extends present knowledge concerning with incipient bedload motion and sediment transport at small relative height and hydraulically rough surface bed for turbulent unaerated free surface flow. Incipient bedload motion and sediment transport have been determined for homogeneous and inhomogeneous bed materials. For homogeneous bed material the velocity profiles have been described by different methods in near the bed. Further, hydraulic flow resistance has been evaluated. In the case of inhomogeneous bed material, static armouring and influence of surface layer sorting on hydraulic roughness have been investigated. The correctness of obtained knowledge has been confirmed on the object of nature-inspired river widening. Results shown, among others, that incipient bedload motion does not depend on relative height or final armouring of surface layer to what extend hydraulic roughness is influenced.
Style APA, Harvard, Vancouver, ISO itp.
26

Pečeliūnas, Robertas. "Automobilio svyravimai ekstremalaus stabdymo metu". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050224_192006-55801.

Pełny tekst źródła
Streszczenie:
The suspension of the motor vehicle is one of the most important elements of the flexible mounted and inflexible mounted masses of the vehicle bodywork, and most attention is paid to its exploration and improvement. Analysis of models of equivalent oscillation systems of motor vehicles testifies that the evaluation of motor vehicle oscillations and modelling of its motion modes is still very topical and requires further research. Suspension models of motor vehicles offered in publications regard only the influence of road irregularities, and the modernisation of these models is directed towards the improvement of passengers’ comfort. However not much research has been done on the influence of oscillations of flexible mounted and inflexible mounted masses of the bodyworks of vehicles in the process of braking; also there is not much investigation of the post-accident identification of the vehicle’s movement mode corresponding to the deformations of the suspension and the longitudinal pitch of the bodywork. Research of oscillations in the conditions of emergency braking is primarily important for the work in two practical directions: 1) improvement of calculation methods of motor vehicle’s response to external impact in the conditions of real operation; 2) further improvement of research methods on the road, and analysis of fait accompli road accidents related to oscillations in the emergency braking. Methodology defining the oscillations occurring in the braking may be applied... [to full text]
Style APA, Harvard, Vancouver, ISO itp.
27

Steiner, Christophe. "Résolution numérique de l'opérateur de gyromoyenne, schémas d'advection et couplage : applications à l'équation de Vlasov". Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAD033/document.

Pełny tekst źródła
Streszczenie:
Cette thèse propose et analyse des méthodes numériques pour la résolution de l'équation de Vlasov. Cette équation modélise l'évolution d'une espèce de particules chargées sous l'effet d'un champ électromagnétique. La première partie est consacrée à une analyse mathématique de schémas semi-Lagrangiens résolvant l'équation de transport linéaire qui constituent la brique de base des méthodes de splitting directionnel.Des méthodes de résolution de l'équation de Vlasov couplée à l'équation de Poisson, dans le cas où uniquement le champ électrique est considéré, sont optimisées dans la seconde partie. Il s'agit d'optimisation en temps de calcul par l'utilisation de cartes graphiques (GPU) et l'utilisation d'un maillage non homogène.Dans la troisième et dernière partie, nous étudierons une méthode numérique de calcul de l'opérateur de gyromoyenne intervenant dans la théorie gyrocinétique que nous appliquerons à l'équation de quasi-neutralité
This thesis proposes and analyzes numerical methods for solving the Vlasov equation. This equation models the evolution of a species of charged particles under the effet of an electromagnetic field. The first part is devoted to a mathematical analysis of semi-Lagrangian schemes solving the linear transport equation which is the basic building block of directional splitting methods.Solving methods for the Vlasov equation coupled to the Poisson equation, in the case where only the electric field is considered, are optimized in the second part. This optimization relates to the time of calculation by the use of Graphics Processing Unit (GPU) and the use of an inhomogeneous mesh.In the third and final part, we study a numerical method for calculating the gyroaverage operator involved in gyrokinetic theory. This method will be applied to solve the quasi-neutrality equation
Style APA, Harvard, Vancouver, ISO itp.
28

Penny, Melissa. "Mathematical modelling of dye-sensitised solar cells". Queensland University of Technology, 2006. http://eprints.qut.edu.au/16270/.

Pełny tekst źródła
Streszczenie:
This thesis presents a mathematical model of the nanoporous anode within a dyesensitised solar cell (DSC). The main purpose of this work is to investigate interfacial charge transfer and charge transport within the porous anode of the DSC under both illuminated and non-illuminated conditions. Within the porous anode we consider many of the charge transfer reactions associated with the electrolyte species, adsorbed dye molecules and semiconductor electrons at the semiconductor-dye- electrolyte interface. Each reaction at this interface is modelled explicitly via an electrochemical equation, resulting in an interfacial model that consists of a coupled system of non-linear algebraic equations. We develop a general model framework for charge transfer at the semiconductor-dye-electrolyte interface and simplify this framework to produce a model based on the available interfacial kinetic data. We account for the charge transport mechanisms within the porous semiconductor and the electrolyte filled pores that constitute the anode of the DSC, through a one- dimensional model developed under steady-state conditions. The governing transport equations account for the diffusion and migration of charge species within the porous anode. The transport model consists of a coupled system of non-linear differential equations, and is coupled to the interfacial model via reaction terms within the mass-flux balance equations. An equivalent circuit model is developed to account for those components of the DSC not explicitly included in the mathematical model of the anode. To obtain solutions for our DSC mathematical model we develop code in FORTRAN for the numerical simulation of the governing equations. We additionally employ regular perturbation analysis to obtain analytic approximations to the solutions of the interfacial charge transfer model. These approximations facilitate a reduction in computation time for the coupled mathematical model with no significant loss of accuracy. To obtain predictions of the current generated by the cell we source kinetic and transport parameter values from the literature and from experimental measurements associated with the DSC commissioned for this study. The model solutions we obtain with these values correspond very favourably with experimental data measured from standard DSC configurations consisting of titanium dioxide porous films with iodide/triiodide redox couples within the electrolyte. The mathematical model within this thesis enables thorough investigation of the interfacial reactions and charge transport within the DSC.We investigate the effects of modified cell configurations on the efficiency of the cell by varying associated parameter values in our model. We find, given our model and the DSC configuration investigated, that the efficiency of the DSC is improved with increasing electron diffusion, decreasing internal resistances and with decreasing dark current. We conclude that transport within the electrolyte, as described by the model, appears to have no limiting effect on the current predicted by the model until large positive voltages. Additionally, we observe that the ultrafast injection from the excited dye molecules limits the interfacial reactions that affect the DSC current.
Style APA, Harvard, Vancouver, ISO itp.
29

Penny, Melissa. "Mathematical modelling of dye-sensitised solar cells". Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16270/1/Melissa_Penny_Thesis.pdf.

Pełny tekst źródła
Streszczenie:
This thesis presents a mathematical model of the nanoporous anode within a dyesensitised solar cell (DSC). The main purpose of this work is to investigate interfacial charge transfer and charge transport within the porous anode of the DSC under both illuminated and non-illuminated conditions. Within the porous anode we consider many of the charge transfer reactions associated with the electrolyte species, adsorbed dye molecules and semiconductor electrons at the semiconductor-dye- electrolyte interface. Each reaction at this interface is modelled explicitly via an electrochemical equation, resulting in an interfacial model that consists of a coupled system of non-linear algebraic equations. We develop a general model framework for charge transfer at the semiconductor-dye-electrolyte interface and simplify this framework to produce a model based on the available interfacial kinetic data. We account for the charge transport mechanisms within the porous semiconductor and the electrolyte filled pores that constitute the anode of the DSC, through a one- dimensional model developed under steady-state conditions. The governing transport equations account for the diffusion and migration of charge species within the porous anode. The transport model consists of a coupled system of non-linear differential equations, and is coupled to the interfacial model via reaction terms within the mass-flux balance equations. An equivalent circuit model is developed to account for those components of the DSC not explicitly included in the mathematical model of the anode. To obtain solutions for our DSC mathematical model we develop code in FORTRAN for the numerical simulation of the governing equations. We additionally employ regular perturbation analysis to obtain analytic approximations to the solutions of the interfacial charge transfer model. These approximations facilitate a reduction in computation time for the coupled mathematical model with no significant loss of accuracy. To obtain predictions of the current generated by the cell we source kinetic and transport parameter values from the literature and from experimental measurements associated with the DSC commissioned for this study. The model solutions we obtain with these values correspond very favourably with experimental data measured from standard DSC configurations consisting of titanium dioxide porous films with iodide/triiodide redox couples within the electrolyte. The mathematical model within this thesis enables thorough investigation of the interfacial reactions and charge transport within the DSC.We investigate the effects of modified cell configurations on the efficiency of the cell by varying associated parameter values in our model. We find, given our model and the DSC configuration investigated, that the efficiency of the DSC is improved with increasing electron diffusion, decreasing internal resistances and with decreasing dark current. We conclude that transport within the electrolyte, as described by the model, appears to have no limiting effect on the current predicted by the model until large positive voltages. Additionally, we observe that the ultrafast injection from the excited dye molecules limits the interfacial reactions that affect the DSC current.
Style APA, Harvard, Vancouver, ISO itp.
30

Campobasso, Alessandra. "Modelling scenarios of contaminant transport in an equivalent porous medium". Doctoral thesis, 2022. http://hdl.handle.net/11589/238078.

Pełny tekst źródła
Streszczenie:
Groundwater represents the largest supply of drinking water in the world (25-40%). Increasing urban development and increasing industrial activities, growing water demand due to climate change, and the consequent increase in urban runoff volumes due to the presence of sealed surfaces are causing ad-verse effects on groundwater both quantitatively and qualitatively. To address water stress, Managed Aquifer Recharge (MAR) represents an engineered ap-proach to water security. MAR techniques aim to recharge the aquifer under controlled conditions for the purpose of subsequent recovery or as a barrier to prevent seawater intrusion. The reuse of urban water to implement this strate-gy is adopted from the perspective of environmental sustainability. However, the presence of residual contaminants in the injected stream challenges the feasibility of this solution because it may affect human health. In this context, the site modeled in the present work is located adjacent to the municipality of Avetrana, a place in which a confluence will be built from a channel in order to collect stormwater and floodwater thus protecting the town. The case study has a high level of hydraulic disturbance that makes it necessary to evaluate the vulnerability to pollution of the karst aquifer, which is characterized by a low anti-pollution capacity and therefore very fragile. As a result, it was necessary to perform a numerical simulation of groundwater flow and mass transport in the affected area. FEFLOW software, based on the finite element method, was used to determine the three-dimensional numerical groundwater model. The groundwater flow field was obtained by inputting boundary conditions and pa-rameters derived from hydrogeological field surveys and literature review. Spe-cifically, the methodology involved developing the conceptual hydrogeologic model of the aquifer and then modeling the mass transport of a hypothetical contaminant under different scenarios. Considering that the input conditions in the transport model represent ex-treme and occasional situations, the modeling performed showed that the geo-logic structure represents a potential barrier to pollution. To sum up, the purpose of this study was to make the model a good approx-imation of the groundwater system and to provide reference to prevent pollu-tion in karst aquifers.
Style APA, Harvard, Vancouver, ISO itp.
31

Rosa, Massimiliano. "Properties of the SN[subscript] - equivalent integral transport operator and the iterative acceleration of neutral particle transport methods". 2007. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2085/index.html.

Pełny tekst źródła
Style APA, Harvard, Vancouver, ISO itp.
32

Patel, Amin. "Transport-theory-equivalent diffusion coefficients for node-homogenized neutron diffusion problems in CANDU lattices". Thesis, 2010. http://hdl.handle.net/10155/87.

Pełny tekst źródła
Streszczenie:
Calculation of the neutron flux in a nuclear reactor core is ideally performed by solving the neutron transport equation for a detailed-geometry model using several tens of energy groups. However, performing such detailed calculations for an entire core is prohibitively expensive from a computational perspective. Full-core neutronic calculations for CANDU reactors are therefore performed customarily using two-energy-group diffusion theory (no angular dependence) for a node-homogenized reactor model. The work presented here is concerned with reducing the loss in accuracy entailed when going from Transport to Diffusion. To this end a new method of calculating the diffusion coefficient was developed, based on equating the neutron balance equation expressed by the transport equation with the neutron balance equation expressed by the diffusion equation. The technique is tested on a simple twelve-node model and is shown to produce transport-like accuracy without the associated computational effort.
UOIT
Style APA, Harvard, Vancouver, ISO itp.
33

Northum, Jeremy Dell. "Simulation and Analysis of a Tissue Equivalent Proportional Counter Using the Monte Carlo Transport Code FLUKA". Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-8013.

Pełny tekst źródła
Streszczenie:
The purpose of this study was to determine how well the Monte Carlo transport code FLUKA can simulate a tissue-equivalent proportional counter (TEPC) and produce the expected delta ray events when exposed to high energy heavy ions (HZE) like in the galactic cosmic ray (GCR) environment. Accurate transport codes are desirable because of the high cost of beam time, the inability to measure the mixed field GCR on the ground and the flexibility they offer in the engineering and design process. A spherical TEPC simulating a 1 um site size was constructed in FLUKA and its response was compared to experimental data for an 56Fe beam at 360 MeV/nucleon. The response of several narrow beams at different impact parameters were used to explain the features of the response of the same detector exposed to a uniform field of radiation. Additionally, an investigation was made into the effect of the wall thickness on the response of the TEPC and the range of delta rays in the tissue-equivalent (TE) wall material. A full impact parameter test (from IP = 0 to IP = detector radius) was performed to show that FLUKA produces the expected wall effect. That is, energy deposition in the gas volume can occur even when the primary beam does not pass through the gas volume. A final comparison to experimental data was made for the simulated TEPC exposed to various broad beams in the energy range of 200 - 1000 MeV/nucleon. FLUKA overestimated energy deposition in the gas volume in all cases. The FLUKA results differed from the experimental data by an average of 25.2 % for yF and 12.4 % for yD. It is suggested that this difference can be reduced by adjusting the FLUKA default ionization potential and density correction factors.
Style APA, Harvard, Vancouver, ISO itp.
34

Karlekar, Kirtish. "Design, Fabrication And Characterization Of Low-Scattering Transport Regime Tissue-Equivalent Phantom And Their Use In Time-Domain NIR Imaging". Thesis, 2004. https://etd.iisc.ac.in/handle/2005/1212.

Pełny tekst źródła
Style APA, Harvard, Vancouver, ISO itp.
35

Karlekar, Kirtish. "Design, Fabrication And Characterization Of Low-Scattering Transport Regime Tissue-Equivalent Phantom And Their Use In Time-Domain NIR Imaging". Thesis, 2004. http://etd.iisc.ernet.in/handle/2005/1212.

Pełny tekst źródła
Style APA, Harvard, Vancouver, ISO itp.
Możesz być także zainteresowany bibliografiami na temat „Equivalence Transport” dla innych typów źródeł:
Artykuły w czasopismach
Oferujemy zniżki na wszystkie plany premium dla autorów, których prace zostały uwzględnione w tematycznych zestawieniach literatury. Skontaktuj się z nami, aby uzyskać unikalny kod promocyjny!

Do bibliografii