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FORTE, Ruggero. "Multiphysics Optimization for Water-Cooled Breeding Blanket Design Enhancement." Doctoral thesis, Università degli Studi di Palermo, 2021. http://hdl.handle.net/10447/478128.
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The commercial feasibility of the first fusion power plant generation adopting D-T plasma is strongly dependent upon the self-sustainability in terms of tritium fueling. Within such a kind of reactor, the component selected to house the tritium breeding reactions is the breeding blanket, which is further assigned to heat power removal and radiation shielding functions. As a consequence of both its role and position, the breeding blanket is heavily exposed to both surface and volumetric heat loads and, hence, its design requires a typical multiphysics approach, from the neutronics to the thermo-mechanics. During last years, a great deal of effort has been put in the optimization of the breeding blanket design, with the aim of maximizing the tritium breeding and heat removal performances without undermining its structural integrity. In this dissertation, a derivative-free optimization method named “Complex method” is applied for the design optimization of the European DEMO Water-Cooled Lithium Lead breeding blanket concept. To this purpose, a potential tritium production performances-based objective function is defined and a multiphysics model of the blanket is developed inside COMSOL environment in order to solve the coupled thermo-mechanical problem, while the optimization algorithm implemented in MATLAB leads the design towards a minimum optimum point compliant with the prescribed requirements. Once the optimized design is obtained, its nuclear, thermal-hydraulic and structural performances are assessed by means of specific neutron transport and multiphysics simulations, respectively. Finally, the structural integrity is verified by means of the application of the RCC-MRx design criteria.
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Rodrigues, Dário Barros. "Target-specific multiphysics modeling for thermal medicine applications." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11296.
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Dissertation to obtain the degree of Doctor of Philosophy in Biomedical EngineeringThis thesis addresses thermal medicine applications on murine bladder hyperthermia and brain temperature monitoring. The two main objectives are interconnected by the key physics in thermal medicine: heat transfer. The first goal is to develop an analytical solution to characterize the heat transfer in a multi-layer perfused tissue. This analytical solution accounts for important thermoregulation mechanisms and is essential to understand the fundamentals underlying the physical and biological processes associated with heat transfer in living tissues. The second objective is the development of target-specific models that are too complex to be solved by analytical methods. Thus, the software for image segmentation and model simulation is based on numerical methods and is used to optimize non-invasive microwave antennas for specific targets. Two examples are explored using antennas in the passive mode (probe) and active mode (applicator). The passive antenna consists of a microwave radiometric sensor developed for rapid non-invasive feedback of critically important brain temperature. Its design parameters are optimized using a power-based algorithm. To demonstrate performance of the device, we build a realistic model of the human head with separate temperaturecontrolled brain and scalp regions. The sensor is able to track brain temperature with 0.4 °C accuracy in a 4.5 hour long experiment where brain temperature is varied in a 37 °C, 27 °C and 37 °C cycle. In the second study, a microwave applicator with an integrated cooling system is used to develop a new electro-thermo-fluid (multiphysics) model for murine bladder hyperthermia studies. The therapy procedure uses a temperature-based optimization algorithm to maintain the bladder at a desired therapeutic level while sparing remaining tissues from dangerous temperatures. This model shows that temperature dependent biological properties and the effects of anesthesia must be accounted to capture the absolute and transient temperature fields within murine tissues. The good agreement between simulation and experimental results demonstrates that this multiphysics model can be used to predict internal temperatures during murine hyperthermia studies.
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Han, Chanjuan. "Advanced Multiphysics Simulation and Characterization for the Multifunctional and Innovative Design of Energy Geosystem." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1524139196492659.
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AHMADI, DARMANI MOSTAFA. "Multiphysics Design of Interior Permanent Magnet Machines and Characterization of Innovative Hard Magnetic Material." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971120.
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Blakely, Cole David. "Uncertainty Quantification and Sensitivity Analysis of Multiphysics Environments for Application in Pressurized Water Reactor Design." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7256.
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The most common design among U.S. nuclear power plants is the pressurized water reactor (PWR). The three primary design disciplines of these plants are system analysis (which includes thermal hydraulics), neutronics, and fuel performance. The nuclear industry has developed a variety of codes over the course of forty years, each with an emphasis within a specific discipline. Perhaps the greatest difficulty in mathematically modeling a nuclear reactor, is choosing which specific phenomena need to be modeled, and to what detail.
A multiphysics computational environment provides a means of advancing simulations of nuclear plants. Put simply, users are able to combine various physical models which have commonly been treated as separate in the past. The focus of this work is a specific multiphysics environment currently under development at Idaho National Labs known as the LOCA Toolkit for US light water reactors (LOTUS).
The ability of LOTUS to use uncertainty quantification (UQ) and sensitivity analysis (SA) tools within a multihphysics environment allow for a number of unique analyses which to the best of our knowledge, have yet to be performed. These include the first known integration of the neutronics and thermal hydraulic code VERA-CS currently under development by CASL, with the well-established fuel performance code FRAPCON by PNWL. The integration was used to model a fuel depletion case.
The outputs of interest for this integration were the minimum departure from nucleate boiling ratio (MDNBR) (a thermal hydraulic parameter indicating how close a heat flux is to causing a dangerous form of boiling in which an insulating layer of coolant vapour is formed), the maximum fuel centerline temperature (MFCT) of the uranium rod, and the gap conductance at peak power (GCPP). GCPP refers to the thermal conductance of the gas filled gap between fuel and cladding at the axial location with the highest local power generation.
UQ and SA were performed on MDNBR, MFCT, and GCPP at a variety of times throughout the fuel depletion. Results showed the MDNBR to behave linearly and consistently throughout the depletion, with the most impactful input uncertainties being coolant outlet pressure and inlet temperature as well as core power. MFCT also behaves linearly, but with a shift in SA measures. Initially MFCT is sensitive to fuel thermal conductivity and gap dimensions. However, later in the fuel cycle, nearly all uncertainty stems from fuel thermal conductivity, with minor contributions coming from core power and initial fuel density. GCPP uncertainty exhibits nonlinear, time-dependent behaviour which requires higher order SA measures to properly analyze. GCPP begins with a dependence on gap dimensions, but in later states, shifts to a dependence on the biases of a variety of specific calculation such as fuel swelling and cladding creep and oxidation.
LOTUS was also used to perform the first higher order SA of an integration of VERA-CS and the BISON fuel performance code currently under development at INL. The same problem and outputs were studied as the VERA-CS and FRAPCON integration. Results for MDNBR and MFCT were relatively consistent. GCPP results contained notable differences, specifically a large dependence on fuel and clad surface roughness in later states. However, this difference is due to the surface roughness not being perturbed in the first integration. SA of later states also showed an increased sensitivity to fission gas release coefficients.
Lastly a Loss of Coolant Accident was investigated with an integration of FRAPCON with the INL neutronics code PHISICS and system analysis code RELAP5-3D. The outputs of interest were ratios of the peak cladding temperatures (highest temperature encountered by cladding during LOCA) and equivalent cladding reacted (the percentage of cladding oxidized) to their cladding hydrogen content-based limits. This work contains the first known UQ of these ratios within the aforementioned integration. Results showed the PCT ratio to be relatively well behaved. The ECR ratio behaves as a threshold variable, which is to say it abruptly shifts to radically higher values under specific conditions. This threshold behaviour establishes the importance of performing UQ so as to see the full spectrum of possible values for an output of interest.
The SA capabilities of LOTUS provide a path forward for developers to increase code fidelity for specific outputs. Performing UQ within a multiphysics environment may provide improved estimates of safety metrics in nuclear reactors. These improved estimates may allow plants to operate at higher power, thereby increasing profits. Lastly, LOTUS will be of particular use in the development of newly proposed nuclear fuel designs.
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Fukumoto, Yutaka. "Particle Based Multiphysics Simulation for Applications to Design of Soil Structures and Micromechanics of Granular Geomaterials." Kyoto University, 2015. http://hdl.handle.net/2433/199374.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19050号
農博第2128号
新制||農||1032(附属図書館)
学位論文||H27||N4932(農学部図書室)
32001
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 村上 章, 教授 藤原 正幸, 教授 澤田 純男
学位規則第4条第1項該当
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Moreno, Navarro Pablo. "Multiphysics formulation and multiscale finite element discretizations of thermo-electro-magneto-mechanic coupling for smart materials design." Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2525.
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Les algorithmes numériques basés sur la méthode des éléments finis seront spécialisés dans l’analyse, la conception et l’optimisation de capteurs et d’actionneurs (S-A), ainsi que dans leur application aux structures intelligentes. Les S-A basés sur des actifs tangibles peuvent coupler plusieurs domaines, tels que les domaines mécanique, électrique, magnétique et thermique. Ils sont utilisés dans de nombreuses applications, notamment dans les structures intelligentes, la surveillance des dommages ou l’aérodynamique. Malgré l’expérience considérable de ces études, les étapes abordées consistent d’abord à développer une formulation thermodynamiquement cohérente à l’échelle macro pour introduire des modèles de plasticité; deuxièmement, fournir les outils permettant de prendre en compte les hétérogénéités des modèles multi-échelles pour les matériaux intelligents. L’objectif principal est la mise au point d’un code informatique de recherche permettant de simuler et d’étudier les performances, non seulement des S-A eux-mêmes, mais également des structures intelligentes dans lesquelles ces S-A seront montésNumerical algorithms based on the Finite Element Method will be specialized for Analysis, Design, and Optimization of Sensors and Actuators (S-A) and their Application to Smart Structures. The S-A based on tangible assets can couple several fields, such as mechanical, electrical, magnetic, and thermal. They are used in many applications, particularly in smart structures, damage monitoring, or aerodynamics. Despite the considerable experience in these studies, the steps addressed are first to develop a thermodynamically consistent formulation for macro-scale to introduce plasticity models; second, to provide the tools to take into account the heterogeneities of multi-scale models for smart materials. The main objective is the development of a research computer code to simulate and study the performance, not only of the S-A themselves but also of the smart structures in which these S-A will be mounted
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Vich, Ramis Maria del Mar. "Design of ensemble prediction systems based on potential vorticity perturbations and multiphysics. Test for western Mediterranean heavy precipitation events." Doctoral thesis, Universitat de les Illes Balears, 2012. http://hdl.handle.net/10803/84075.
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L'objectiu principal d'aquesta tesi és millorar l'actual capacitat de predicció de fenòmens meteorològics de pluja intensa potencialment perillosos a la Mediterrània occidental. Es desenvolupen i verifiquen tres sistemes de predicció per conjunts (SPC) que tenen en compte incerteses presents en els models numèrics i en les condicions inicials. Per generar els SPC s'utilitza la connexió entre les estructures de vorticitat potencial (VP) i els ciclons, a més de diferents esquemes de parametrització física. Es mostra que els SPC proporcionen una predicció més hàbil que la determinista. Els SPC generats pertorbant les condicions inicials han obtingut millor puntuació en verificacions estadístiques. Els resultats d'aquesta tesi mostren la utilitat i la idoneïtat dels mètodes de predicció basats en la pertorbació d'estructures de VP de nivells alts, precursors de les situacions ciclòniques. Els resultats i estratègies presentats pretenen ser un punt de partida per a futurs estudis que facin ús d'aquests mètodes.The main goal of this thesis is to improve the current prediction skill of potentially hazardous heavy precipitation weather events in the western Mediterranean region. We develop and test three different ensemble prediction systems (EPSs) that account for uncertainties present in both the numerical models and the initial conditions. To generate the EPSs we take advantage of the connection between potential vorticity (PV) structures and cyclones, and use different physical parameterization schemes. We obtain an improvement in forecast skill when using an EPS compared to a determinist forecast. The EPSs generated perturbing the initial conditions perform better in the statistical verification scores. The results of this Thesis show the utility and suitability of forecasting methods based on perturbing the upper-level precursor PV structures present in cyclonic situations. The results and strategies here discussed aim to be a basis for future studies making use of these methods.
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Guo, Dongzhi. "Design, Analysis, Modeling and Testing of a Micro-scale Refrigeration System." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/450.
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Chip scale refrigeration system is critical for the development of electronics with the rapid increase of power consumption and substantial reduction of device size, resulting in an emergent demand on novel cooling technologies with a high efficiency for the thermal management. In this thesis, active refrigeration devices based on Stirling cycle and an electrocaloric material, are designed and investigated to achieve a high cooling performance. Firstly, a new Stirling micro-refrigeration system composed of arrays of silicon MEMS cooling elements is designed and evaluated. The cooling elements are fabricated in a stacked array on a silicon wafer. A regenerator is placed between the compression (hot side) and expansion (cold side) diaphragms, which are driven electrostatically. Under operating conditions, the hot and cold diaphragms oscillate sinusoidally and out of phase such that heat is extracted to the expansion space and released from the compression space. A first-order of thermodynamic analysis is performed to study the effect of geometric parameters. Losses due to regenerator non-idealities and chamber heat transfer limitation are estimated. A multiphysics computational approach for analyzing the system performance that considers compressible flow and heat transfer with a large deformable mesh is demonstrated. The optimal regenerator porosity for the best system COP (coefficient of performance) is identified. To overcome the computational complexity brought about by the fine pillar structure in the regenerator, a porous medium model is used to allow for modeling of a full element. The analysis indicates the work recovery of the system and the diaphragm actuation are main challenges for this cooler design.The pressure drop and friction factor of gas flow across circular silicon micro pillar arrays fabricated by deep reactive ion etch (DRIE) process are investigated. A new correlation that considers the coupled effect of pillar spacing and aspect ratio, is proposed to predict the friction factor in a Reynolds v number range of 1-100. Silicon pillars with large artificial roughness amplitudes is also fabricated, and the effect of the roughness is studied in the laminar flow region. The significant reduction of pressure drop and friction factor indicates that a large artificial roughness could be built for pillar arrays in the regenerator to enhance the micro-cooler efficiency. The second option is to develop a fluid-based refrigeration system using an electrocaloric material poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer. Each cooling element includes two diaphragm actuators fabricated in the plane of a silicon wafer, which drive a heat transfer fluid back and forth across terpolymer layers that are placed between them. Finite element simulations with an assumption of sinusoidal diaphrahm motions are conducted to explore the system performance detailedly, including the effects of the applied electric field, geometric dimensions, operating frequency and externally-applied temperature span. Multiphysics modeling coupled with solid-fluid interaction, heat transfer, electrostatics, porous medium and moving mesh technique is successfully performed to verify the thermal modeling feasibility. The electrocaloric effect in thin films of P(VDF-TrFE-CFE) terpolymer is directly measured by infrared imaging at ambient conditions. At an electric field of 90 V/μm, an adiabatic temperature change of 5.2 °C is obtained and the material performance is stable over a long testing period. These results suggest that application of this terpolymer is promising for micro-scale refrigeration.
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Eivarsson, Nils, Malin Bohman, Emil Grosfilley, and Axel Lundberg. "Design and Simulation of Terahertz Antenna for Spintronic Applications." Thesis, Uppsala universitet, Institutionen för materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-412982.
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Spintronics is a spin-electronic field where the electron spinangular momentum, in conjunction with charge, is used to read andwrite information in magnetic sensors and logic circuits, e.g. hard disk drive (HDD), magnetic random access memory (MRAM) and broadband TeraHertz (THz) emitters. To realize the THz operations of the spin logic circuits THz manipulation of the magnetic state is pivotal. This THz manipulation of the magnetic state in anti-ferromagnetic magnetic materials can be realized by coupling the materials with THz antennas. On the other hand, these antennas enhance the THz amplitude of spin-electronic THz emitters when coupled with its output. Therefore, these THz antennas can not only be coupled with the input of magnetic logics to improve the efficiency of magnetic sate manipulation in logic devices but also with the output of the spintronic THz emitters to enhance the generated THz signal amplitude. In this project, we have examined four types of antennas: h-dipole, spiral, bow-tie, and a sub-THz antenna. All the antennas are placed on top of a MgO substrate material for simplicity. However, a bow-tie antenna is also fabricated on an antiferromagnetic substrate of TmFeO3 to check this antenna’s reliability to manipulate its magnetic state. We have studied the impact of antenna geometries on the generated electric field amplitude. We have optimized each antenna for maximum electric field norm profile, with an increase of 30% for the h-dipole and spiral antennas, and an increase of 100% for the bow-tie antenna. However, in this project we were not able to find any general conclusions about what geometrical parameters can further amplify the generated electric field. None of the antennas generated a large enough peak-to-peak electric field amplitude to manipulate the magnetic state of anti-ferromagnetic materials. However, they did successfully amplify the spintronic THz emitter output and could certainly be useful in that regard.
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Назаренко, Сергей Александрович. "Компьютерные технологии мультифизических процессов." Thesis, ЛІРА, 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/29723.
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В докладе описаны формализованные на единой комплексной научно-методологической базе компьютерные технологии мультифизических процессов. Основополагающим компонентом анализа мультифизических проблем является построение связанных моделей. Приведены примеры реализованных разработок физико-механических процессов.The rapid development of CAD/CAM/CAE/CIM/PLM systems is a worldwide trend. The research includes a brief summary of main scientific results of multidisciplinary modeling of loaded structures and technological systems. The basic component analyses of multiphysics problems are to build related models. Examples of implemented applications of physical and mechanical processes in the manufacture are presented.
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Caglar, Ahmet. "Design And Experimental Testing Of An Adsorbent Bed For A Thermal Wave Adsorption Cooling Cycle." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614754/index.pdf.
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Poor heat and mass transfer inside the adsorbent bed of thermal wave adsorption cooling cycles cause low system performance and is an important problem in the adsorbent bed design. In this thesis, a new adsorbent bed is designed, constructed and tested to increase the heat and mass transfer in the adsorbent bed. The adsorbent bed is constructed from a finned tube in order to enhance the heat transfer. Additionally, the finned bed geometry is theoretically modeled and the model is solved time dependently by using Comsol Multiphysics software program. The distributions of dependent variables, i.e. temperature, pressure and amount adsorbed, are simulated and plotted in Comsol Multiphysics. In the model, the dependent variables are computed by solving the energy, mass and momentum transfer equations in a coupled way and their variations are investigated two-dimensionally. The results are presented with multicolored plots in a 2-D domain. Furthermore, a parametric study is carried out for determining factors that enhance the heat and mass transfer inside the adsorbent bed. In this parametric study, the effects of several design and operational parameters on the dependent variables are investigated. In the experimental study, the finned tube is tested using natural zeolite-water and silica gel-water working pairs. Temperature, pressure and amount adsorbed variations inside the adsorbent bed at various operating conditions are investigated. After that, a second adsorbent bed with a larger size is constructed and tested. The effect of the particle diameter of the adsorbent is also investigated. The experimental and theoretical results are compared.
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Rezk, Kamal. "CFD as a tool for analysis of complex geometry : Perspectives on time efficient simulations of interior household appliance components." Licentiate thesis, Karlstads universitet, Avdelningen för energi-, miljö- och byggteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-6687.
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Throughout recent years, computer based programs has been applied to solve and analyze industrial problems. One of these developed programs is the Computational Fluid Dynamics (CFD) program. The purpose of implementing CFD analysis is to solve complex flow behavior which is not possible with ordinary calculus. The extensive application of CFD in the industry is a result of improved commercial CFD codes in terms of more advance partial differential equations (PDE) describing various physical phenomena, CAD and mesh-grid generating tools and improved graphical user interfaces (GUI). Today, CFD usage has extended to fields such as aerodynamic, chemical process engineering, biomedical engineering and drying technology. As there is an on-going expansion of CFD usages in the industry, certain issues need to be addressed as they are frequently encountered. The general demand for simulation of larger control volumes and more advanced flow processes result in extensive requirement of computer resources. Numerous complex flow topics today require computer cluster networks which are not accessible for every company. The second issue is the implementation of commercial CFD codes in minor industrial companies is utilized as a black box based on the knowledge on fluid mechanic theory. A vital part of the simulation process is the evaluation of data through visual analysis of flow patterns, analysis on the sensitivity of the mesh grid, investigation of quantitative parameters such as pressure loss, velocity, turbulence intensity etc. Moreover, increased partnerships between industry and the academic world involving various CFD based design processes generally yields to a verbal communication interface which is a crucial step in the process given the fact of the level of dependency between both sides. The aim of this thesis is to present methods of CFD analysis based on these issues. In paper I, a heuristically determined design process of the geometry near the front trap door of an internal duct system was achieved by implementing the CFD code COMSOL MultiPhysics as a communication tool. The design process was established by two counterparts in the project in which CFD calculations and geometry modifications were conducted separately. Two design criteria presenting the pressure drop in duct and the outflow uniformity was used to assess geometry modifications conducted by a CAD-engineer. The geometry modifications were based on visual results of the flow patterns. The geometry modifications confirmed an improvement in the geometry as the pressure drop was reduced with 23% and the uniformity was increased with 3%. In paper II, volume-averaged equations were implemented in a tube-fin heat exchanger in order to simulate airflow. Focus was on achieving a correct volume flow rate and pressure drop (V-p) correlation. The volume averaged model (VAM) is regarded as a porous medium in which the arrangement of fins and tube bundles are replaced with volume-averaged equations. Hence, the computational time was reduced significantly for the VAM model. Moreover, experimental results of the (V-p) correlation showed good agreement with the VAM model.
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Russi, Luigi. "modeling the pressure drop and thermal profile of a novel solid oxide fuel cell stack design with a homogenized approach." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Le celle a combustibile a ossidi solidi (SOFCs) rappresentano una tecnologia chiave in uno scenario di decarbonizzazione delle attività umane per i prossimi anni.
Gli stack attualmente disponibili presentano elevati gradienti di temperatura e grandi perdite di carico attraverso lo stack, così come distribuzioni di corrente disuniformi, problemi di perdita di contatto e di deterioramento.
Un innovativo design dello stack, detto"Chessboard", è stato ideato al DTU Energy.
La determinazione dei campi di temperatura, pressione e velocità nello stack tramite simulazione risulta fondamentale per valutare la qualità di un certo design. Infatti non sempre è possibile misurare sperimentalmente grandezze fisiche locali all'interno dello stack.
In questo lavoro un modello tridimensionale (3D) dello stack è stato costruito. L'approccio modellistico utilizzato si basa sulla tecnica di omogenizzazione. Un metodo efficiente a livello computazionale basato sull'utilizzo di una geometria semplificata, ma con proprietà termofisiche anisotropiche che rispecchino la vera geometria dello stack per reincrementare il livello di dettaglio.
Fra tutte le fisiche che descrivono i fenomeni in una SOFC, solo il moto dei fluidi e la trasmissione del calore sono effettivamente risolte dal modello nell'attuale stadio di sviluppo, mentre i fenomeni elettrochimici sono definiti come parametri in ingresso.
Una volta impostato il modello, è stato eseguito uno studio parametrico, con lo scopo di ottenere i profili di temperatura e pressione in funzione delle dimensioni dello stack, dell'eccesso d'aria, della pressione in ingresso dell'aria e della dimensione dei pori. Individuando quindi una finestra di esercizio sicura per i 4 parametri considerati.
Dai risultati si evince che è possibile trovare diverse combinazioni di parametri che soddisfino l'obiettivo di progetto dato da limiti sui materiali costituenti lo stack, tutto questo con dei tempi di risoluzione nell'ordine dei minuti.
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Xu, Ye. "Kilowatt Three-phase Rotary Transformer Design for Permanent Magnet DC Motor with On-rotor Drive System." Thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-27781.
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The aim of this thesis is to design a kilowatt three-phase step-down rotary transformer for a permanent magnet DC motor. The permanent magnet DC motor has an on-rotor drive system, and therefore requiring a power supply that can transfer power to its drive unit without mechanical contact. The rotary transformer has a detached magnetic coupling structure that qualifies it as a potential method for the wireless power transfer. This thesis studies the rotary transformer as a static device, focusing on its core loss. By using a transient finite element analysis of COMSOL Multiphysics and an iron loss prediction model, the rotary transformer was optimized in terms of efficiency and power density for the on-rotor drive system through proper material selection and geometry exploration. After this, a mechanical design, which based on a literature review of the influences of manufacturing processes on electrical steels, was proposed for realizing the core fabrication and the rotary transformer assembly. The results show that the rotary transformer can step down 400 V/50 Hz three-phase voltage to 13.15V in a Delta-wye connection and output 1.17kW power over an air-gap of 0.3mm with 95.94% overall efficiency. The proposed mechanical design enables the transformer to minimize the core loss and the manufacturing cost. Without using resonant inductive coupling, this transformer design simplifies the power supply for the motor, thereby decreasing the motor manufacturing and maintenance cost.
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Jebari, Nessrine. "Design and Microfabrication of a Biosensor Integrating Magnetofluidic Manipulation and Direct-Field Capacitive Sensing." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST132.
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Les maladies inflammatoires chroniques nécessitent un diagnostic précoce, un pronostic et une prise en charge personnalisée, ce qui peut être réalisé grâce à un suivi non invasif en temps réel de biomarqueurs inflammatoires tels que les cytokines et les protéines de phase aiguë. La sueur, un biofluide accessible et riche en informations, offre un milieu prometteur pour ce type de suivi. Cependant, les biocapteurs actuels pour la sueur sont confrontés à des défis en termes de sensibilité et de spécificité en raison des faibles concentrations de ces biomarqueurs et de la composition complexe de la sueur. Cette thèse présente un nouveau biocapteur combinant la manipulation de nanoparticules magnétiques (NPM) avec la détection capacitive en champ direct (DF-CS). Le biocapteur génère un gradient de champ magnétique contrôlé pour concentrer les immunocomplexes dans une zone de détection capacitive définie, permettant une analyse rapide, quantitative et sans marquage des biomarqueurs. Cette méthode améliore la sensibilité en réduisant les interférences de fond et élimine le besoin d'une fonctionnalisation complexe de la surface. De plus, elle permet la détection de plusieurs analytes, simplifiant la fabrication et améliorant potentiellement la stabilité et la reproductibilité du capteur. Des simulations multiphysiques 3D complètes à l'aide de COMSOL Multiphysics ont été effectuées pour optimiser la conception et les paramètres opérationnels du biosenseur. Ces simulations ont modélisé les interactions entre les champs magnétiques, fluidiques et électriques au sein du dispositif, prédisant une augmentation significative de la sensibilité de la détection capacitive allant jusqu'à 42,48 % à 85 % d'occupation des NPM. Un processus de microfabrication rigoureux en 26 étapes a été développé pour obtenir les structures magnétomicrofluidiques et capacitives. La biocompatibilité a été améliorée grâce à des revêtements de Parylène C et un nouveau protocole de collage à basse température à 45°C a été établi pour les interfaces Parylène C-Parylène C. La caractérisation expérimentale a validé les simulations, confirmant le piégeage magnétique efficace dans la zone de détection. Les mesures de capacitance et d'impédance dans l'air et l'eau déionisée ont démontré la réactivité du capteur aux changements de l'environnement diélectrique. À 200 kHz dans l'eau déionisée, le dispositif R500 a montré une diminution de 17,6 % de la capacitance et de 18,6 % de l'impédance par rapport à l'air, tandis que le dispositif R1000 a présenté des diminutions plus importantes de 25,5 % et 9,5 %, respectivement. Ces résultats démontrent la capacité du capteur à détecter les variations des propriétés diélectriques, une condition essentielle pour la détection des NPM liés aux biomarqueurs dans le biofluide. Les travaux futurs se concentreront sur la fonctionnalisation des NPM avec des anticorps ciblant les biomarqueurs pro-inflammatoires et l'évaluation des performances du capteur dans les échantillons de sueur, notamment la sensibilité, la spécificité et la limite de détectionChronic inflammatory diseases require early diagnosis, prognosis, and personalized management. Real-time, non-invasive monitoring of biomarkers like cytokines and acute-phase proteins in easily accessible biofluids is crucial. Sweat offers a promising medium, but current biosensors face challenges due to low biomarker concentrations and complex sweat composition. This thesis presents a novel biosensor that combines magnetic nanoparticle (MNP) manipulation with direct field capacitive sensing (DF-CS). The biosensor generates a controlled magnetic field gradient to concentrate immunocomplexes in a defined capacitive detection zone, enabling rapid, quantitative, and label-free biomarker analysis. This method enhances sensitivity by reducing background interference and eliminates the need for complex surface functionalization. Additionally, it enables multiplex detection, simplifying fabrication and potentially improving the sensor's stability and reproducibility. Comprehensive 3D multiphysics simulations using COMSOL Multiphysics were conducted to optimize the biosensor's design and operational parameters. These simulations modeled the interactions between magnetic, fluidic, and electric fields within the device, predicting a significant increase in capacitive sensing sensitivity of up to 42.48% at 85% MNP occupancy. A rigorous 26-step microfabrication process was developed to achieve the magnetofluidic and capacitive structures. Biocompatibility was enhanced using Parylene C coatings, and a novel low-temperature bonding protocol at 45°C was established for Parylene C-Parylene C interfaces. Experimental characterization validated the simulations, confirming effective magnetic trapping in the detection zone. Capacitance and impedance measurements in air and deionized water demonstrated the sensor's responsiveness to changes in the dielectric environment. At 200 kHz in deionized water, the R500 device showed a 17.6% decrease in capacitance and an 18.6% increase in impedance compared to air, while the R1000 device exhibited larger increases of 25.5% and 9.5%, respectively. These results demonstrate the sensor's ability to detect variations in dielectric properties, a critical requirement for detecting MNPs bound to biomarkers in biofluids. Future work will focus on functionalizing MNPs with antibodies targeting pro-inflammatory biomarkers and evaluating the sensor's performance in sweat samples, specially in terms of sensitivity, specificity, and limit of detection
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Orellana, Sebastian. "Développement et amélioration de structures mobiles embarquées dans les interconnexions des puces microélectroniques : Etude du contact mécanique et électrique." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM070/document.
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Ces dernières années la miniaturisation des microsystèmes atteint la limite physique de leur développement. Ainsi une de voie d’innovation dans l’industrie des semiconducteurs est l’intégration des fonctionnalités supplémentaires au sein des composants déjà existants.Le projet consiste à intégrer, dans une même couche métallique d’interconnexion CMOS, un MEMS capable, par sa rotation, d’établir un contact électrique.Les verrous se situent dans la libération des parties mobiles par dissolution de l’oxyde environnant (déformation hors plan sous l’effet des contraintes résiduelles, stiction, présence de résidus qui empêchent le contact), dans l’actionnement (densité de courant, répétabilité, durabilité, fiabilité) ainsi que, la capacité d’établir un vrai contact électrique à faible résistance (aire réelle / apparente du contact des surfaces rugueuses, pollution du contact).Le travail réalisé a porté sur la conception, le design et la simulation des microsystèmes afin de surmonter ces difficultés et / ou d’étudier le comportement et mesurer les effetsIn recent years the miniaturization of microsystems is reaching the physical limit of its development. Thus, a path of innovation in the semiconductor industry is additional functionalities in existing components.The project consists to integrate a MEMS, within the same metal interconnect of CMOS layer which, by rotating, can establish an electrical contact.The obstacles are in the release of the moving parts by dissolution of the surrounding oxide (out of plane deformation under the effect of residual stress, stiction, residues which prevent contact), in the actuation (current density repeatability, durability, reliability) and, for ohmic switches, the ability to establish a real electrical contact with low resistance (real / apparent area of contact with rough surfaces, contact pollution).The work carried out has focused on conception (design) and simulation of microsystems to overcome these difficulties and / or to study the behavior and measure the effects
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Taha, Hoda. "Cοnceptiοn de moteurs à aimants permanents à flux axial ou radial à haute vitesse pour l'entraînement d." Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMLH25.
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Cette thèse se concentre sur la conception de moteurs à aimants permanents à haute vitesse et faible puissance, spécifiquement destinés à l'entraînement d'un compresseur contrarotatif. L'objectif principal est de garantir une intégration directe et compacte du moteur, tant en termes de longueur que de volume, dans les roues du compresseur. Pour répondre à ces exigences, plusieurs topologies de moteurs à flux axial, à flux radial, ainsi qu'une structure novatrice à entrefer conique, ont été modélisées et évaluées. Ces évaluations incluent une analyse approfondie des performances électromagnétiques et thermiques, visant à maximiser le rendement des moteurs à haute vitesse. Une attention particulière a été portée à l'étude des pertes électromagnétiques, qui deviennent significatives à ces vitesses élevées, pour chacune des topologies considérées. En parallèle, des analyses mécaniques détaillées ont été réalisées sur des rotors discoïdes, peu documentés dans la littérature, ainsi que sur des rotors cylindriques, afin de caractériser leur comportement mécanique à une vitesse de rotation de 90 000 tr/min. Les contraintes liées à la fabrication ont orienté le choix final vers une topologie à flux radial, dont le prototypage est actuellement en coursThis thesis focuses on the design of high-speed, low-power permanent magnet motors specifically intended for driving a counter-rotating compressor. The primary objective is to ensure direct and compact integration of the motor, both in terms of length and volume, within the compressor wheels. To meet these requirements, several motor topologies—axial flux, radial 268 flux, and an innovative conical airgap structure—were modeled and evaluated. These evaluations included an in-depth analysis of electromagnetic and thermal performance, aimed at maximizing motor efficiency at high speeds. Particular attention was given to the study of electromagnetic losses, which become significant at these high speeds, for each of the considered topologies. In parallel, detailed mechanical analyses were conducted on disc-shaped rotors, which are sparsely documented in the literature, as well as on cylindrical rotors, to characterize their mechanical behavior at a rotational speed of 90,000 rpm. Manufacturing constraints ultimately led to the selection of the radial flux topology, which is currently under prototyping
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Ristagno, Baptiste. "Machines à commutateur mécanique pour traction automobile : modélisation et optimisation." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0122.
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Les travaux de recherches menés dans cette thèse s'inscrivent dans un contexte d'électrification du secteur automobile en réponse aux préoccupations environnementales. Cette thèse concerne la modélisation et l'optimisation de machines à commutateur mécanique pour la motorisation électrique de petits véhicules mono- ou bi- place. Les machines à collecteur représentent une alternative crédible par leur compétitivité, leur robustesse et leur fiabilité principalement dues à l'absence d'électronique de puissance. Néanmoins, elles nécessitent des dispositifs de compensation et d'aide à la commutation dont l'absence peuvent dégrader leurs performances. L'alimentation par commutateur mécanique rend nécessaire la prise en compte de la dynamique électrique dans la modélisation numérique par éléments finis. C'est pourquoi, il est crucial de développer un modèle permettant un couplage fort au sens de la formulation variationnelle du problème magnétique, du circuit électrique externe et enfin du problème électrocinétique de circulation des courants à l'interface du commutateur. Dans ce contexte, l'utilisation d'une plateforme de modélisation ouverte ONELAB a abouti au développement d'un modèle original de projection des propriétés physiques et des sources sur un maillage fixe. Cette méthode permet de s'affranchir du remaillage lors de processus itératifs tels que l'optimisation géométrique ou encore la prise en compte du mouvement. Cette méthode a abouti au couplage dynamique du problème magnétique et du circuit électrique externe à la formulation électrocinétique de l'ensemble balais-collecteur ainsi qu'à des perspectives de simulations multi-physiques à cette interface. Enfin, le choix d'un algorithme d'optimisation adapté aux modèles numériques (boîte noire à fort coût d'évaluation) a permis de développer un outil de dimensionnement des machines à commutateur mécanique adapté à une grande variété de structures en réponse à un cahier des charges industrielThe research work carried out in this thesis is part of a context of vehicle electrification in response to environmental concerns. This thesis focuses on the modeling and optimization of commutator machines used in powertrains of small electric vehicles. This kind of machines represents an alternate solution due to their competitiveness, robustness and reliability mainly due to the absence of power electronics. Nevertheless, they require compensation windings and commutation poles to improve their performances. Commutator power supply makes it necessary to take into account electrical dynamics in numerical magnetic modeling by finite elements. That is why, it is crucial to develop a model allowing a strong coupling in the sense of the variational formulation, of magnetic problem, external electrical circuit and finally current flow problem at the commutator interface. In this context, the use of a modeling opensource platform ONELAB has led to the development of an original model that performs projection of physical properties and sources on a fixed mesh. This method avoids remeshing during iterative processes such as geometric optimization or movement modeling. This method has led to the dynamic coupling of the magnetic problem and the external electrical circuit to the current flow formulation at the commutator interface as well as to prospects for multi-physical simulations at this interface. Finally, the choice of an optimization algorithm adapted to the numerical models (black box with a high evaluation cost) allowed the development of a tool for the design of commutator machines adapted to many topologies in order to fulfill industrial requirements
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Zhang, Yue. "Design and multi-physical fields analysis of high speed permanent magnet machines." Thesis, Queen's University Belfast, 2018. https://pure.qub.ac.uk/portal/en/theses/design-and-multiphysical-fields-analysis-of-high-speed-permanent-magnet-machines(0ec1f9e7-c2b9-4e46-b974-d1f7b932d9ab).html.
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Due to the advantages of high power density, high efficiency and compact size, high speed permanent magnet machines (HSPMMs) have found wide application in industrial areas. Compared with a conventional speed permanent magnet machine, a HSPMM rotor can reach speeds of more than 10,000 rpm, which brings challenges with regard to electromagnetic, thermal and mechanical aspects of machine design. The higher power density also results in larger power loss per unit volume; due to the small machine size, machine thermal dissipation becomes difficult. Moreover, air frictional loss rises dramatically when the rotor is in high speed operation and this may also further increase rotor temperature. Therefore, research into HSPMM power losses and improving machine thermal dissipation capability is of significant interest. HSPMM mechanical issues also need to be considered to ensure safe and reliable machine operation. As rotor speeds rise, rotor strength becomes prominent and critical as the permanent magnets are vulnerable to the large centrifugal force. In addition, the machine rotor should also have enough rigidity and avoid operating at critical speeds. As such, this dissertation focuses on HSPMM design and research. Multi-physical fields analysis of a HSPMM is carried out to calculate machine power losses and temperature distribution, with factors influencing machine performance considered; HSPMM rotor mechanical research and analysis are also carried out and presented in this study. Firstly, the HSPMM design methodology and process are illustrated with machine rotor parameters, PM material, pole numbers and rotor sleeve considered for a 150 kW, 17000 rpm HSPMM. Then, HSPMM performance for different machine stator structures and PM pole arc pole pitches is investigated using the Finite Element Method (FEM) for the machine operating at both no load and full load conditions; HSPMM electromagnetic performance and how it is impacted by machine parameters is also studied. HSPMM power losses are comprehensively investigated in the following chapter. As machine core loss can be significantly increased with increasing machine frequency, it is critical to accurately estimate HSPMM iron loss. Based on the machine iron core magnetic field variation that is obtained by FEM analysis, machine steel iron core loss estimation for HSPMM is performed using an improved method with the influences of alternating and rotating magnetic fields, as well as harmonics effects, considered for high precision. Then the HSPMM air gap magnetic flux density distribution considering machine stator slotting effect is also analytically calculated with its effectiveness verified by FEM results. Then rotor eddy current loss is studied by time-stepping FEM, while the effects of rotor sleeve dimensions and properties, copper shielding composite rotor structure, air gap length, as well as slot opening width are further researched in depth. A PM bevelling method is also proposed and investigated to reduce HSPMM rotor eddy current loss while having little effect on machine output torque. Then a fluid field analysis is carried out to study HSPMM rotor air frictional loss when the rotor is in high speed operation. According to the characteristics of a machine axial forced air cooling system, the HSPMM temperature distribution is investigated by 3-D fluid–thermal coupling CFD modelling with the calculated power losses results. The machine thermal analysis theory and modelling method are also detailed and further explained. HSPMM thermal performance variation due to impacting factors of cooling air velocity, rotor eddy current loss and sleeve thermal conductivity are also comprehensively investigated and studied in this dissertation. The designed HSPMM is prototyped, and temperature experimental tests are also carried out to verify the effectiveness of the research and analysis for HSPMM. Then, thick-walled cylinder theory is introduced to study rotor mechanical strength analytically, while it also verifies the FEM calculation results. Then based on FEM analysis, HSPMM rotor stress distribution is investigated with sleeve material effects on rotor strength discussed. In order to alleviate the rotor sleeve stress, three pole filler materials are comparatively studied, while the temperature impacts on rotor mechanical stress is further considered; sleeve thickness and the interference between PM and sleeve are investigated in an integrated fashion for HSPMM rotor strength analysis, with some conclusions also drawn for HSPMM rotor mechanical design. HSPMM rotor critical speeds are also calculated by the established 3D rotor dynamic analysis FEM model to ensure the rotor is operating in a desirable condition.
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Dupé, Valérie. "Conception multidisciplinaire de microsystèmes autonomes." Phd thesis, Bordeaux 1, 2011. http://tel.archives-ouvertes.fr/tel-00858692.
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Toute action naturelle crée de l'énergie perdue qui pourrait être exploitée pour alimenter nos appareils électriques et mobiles. Nos environnements physiques disposent d'un nombre élevé de micro-sources d'énergies ; certes chacune est de faible puissance, mais leur multiplicité pourrait s'avérer significative, notamment dans le cadre du fonctionnement de microsystèmes. C'est le principe précédent qui a conduit nos travaux sur la problématique de la conception de microsystèmes autonomes. Ainsi, pour être innovante, l'ingénierie de microsystèmes doit à la fois s'appuyer sur la culture de l'électronique, de la mécanique mais aussi de l'énergétique. Le processus de conception est fortement pluridisciplinaire et son efficacité réside dans la capacité à mettre en oeuvre des méthodologies et des outils : - de conception collaborative, - de capitalisation des connaissances techniques, - d'ingénierie multi-physique, - d'ingénierie intégrée. Sur le base de ces fondamentaux, nous avons développé un outil d'aide à la conception. La méthodologie sous-jacente permet : 1- l'analyse et la structuration d'un problème de conception d'un microsystème autonome : cette phase conduit l'identification, la description fonctionnelle et environnementale du système et de son environnement. 2- la modélisation des connaissances : une analyse architecturale conduit à la description des composants et des interactions liées au microsystème (directement ou indirectement) puis à la modélisation des comportements, 3- la qualification énergétique et le couplage physique : la réutilisation structurée des modèles de connaissances est pilotée pour coupler les modèles physiques et décrire les sources, les puits et les mécanismes énergétiques des environnements, 4- la conduite de la recherche de concepts innovants : la base de connaissances, les critères de qualification et la description fonctionnelle préalablement construits sont agencés dans une seule méthode de conception virtuelle pour rechercher des concepts de solutions innovants, 5- le pré-dimensionnement : tout en assurant l'intégration des outils spécialisés de simulation (méthode des éléments finis et simulation fonctionnelle), le prédimensionnement de microsystèmes autonomes est supportée selon un schéma synthétique, assurant un raisonnement abductif (ou bottom-up). La conjonction des raisonnements physiques, l'intégration des méthodes et des cultures métiers, l'exploration virtuelle des espaces de solutions et la modélisation constituent les bases d'un nouveau moyen d'aide à la conception de microsystèmes autonomes. Cette approche a été déployée pour la conception d'un capteur piézoélectrique autonome.
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Cenni, Fabio. "Modélisation à haut niveau de systèmes hétérogènes, interfaçage analogique /numérique." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00721972.
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L'objet de la thèse est la modélisation de systèmes hétérogènes intégrant différents domaines de la physique et à signaux mixtes, numériques et analogiques (AMS). Une étude approfondie de différentes techniques d'extraction et de calibration de modèles comportementaux de composants analogiques à différents niveaux d'abstraction et de précision est présentée. Cette étude a mis en lumière trois approches principales qui ont été validées par la modélisation de plusieurs applications issues de divers domaines: un amplificateur faible bruit (LNA), un capteur chimique basé sur des ondes acoustiques de surface (SAW), le développement à plusieurs niveaux d'abstraction d'un capteur CMOS vidéo, et son intégration dans une plateforme industrielle. Les outils développés sont basés sur les extensions AMS du standard IEEE 1666 SystemC mais les techniques proposées sont facilement transposables à d'autres langages tels que VHDL-AMS ou Verilog-AMS utilisés en conception de dispositifs mixtes.
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Appel, Bradley. "Multiphysics Design and Simulation of a Tungsten-Cermet Nuclear Thermal Rocket." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11649.
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The goal of this research is to apply modern methods of analysis to the design of a tungsten-cermet Nuclear Thermal Rocket (NTR) core. An NTR is one of the most viable propulsion options for enabling piloted deep-space exploration. Concerns over fuel safety have sparked interest in an NTR core based on tungsten-cermet fuel. This work investigates the capability of modern CFD and neutronics codes to design a cermet NTR, and makes specific recommendations for the configuration of channels in the core.
First, the best CFD practices available from the commercial package Star-CCM+ are determined by comparing different modeling options with a hot-hydrogen flow experiment. Next, through grid convergence and sensitivity studies, numerical uncertainty is shown to be a small contributor to overall uncertainty; while fuel thermal conductivity, hydrogen specific heat, and fission energy deposition are found to have a large impact on simulation uncertainty. The model-form error is then estimated by simulation of a NERVA fuel element from an NRX-A6 engine test, where the peak temperature matches measured data to within 2.2%. Using a combination of Star-CCM+ and MCNP for neutronics, typical uncertainties are estimated at 3% for predicting fuel temperature, 2% for hydrogen temperature, and 5% for pressure.
The second part uses the aforementioned analysis methods in a parametric study to determine what coolant channel size and distribution is optimum for a 10 klbf-thrust cermet NTR core. By varying the channel diameter and pitch-to-diameter ratio (p/d), it is found that a diameter of 0.12 cm with a p/d of 1.8 results in the lightest core with a peak temperature of 2850 K. The study also shows that element-by-element mass flow rate zoning is the best method for handling radial power peaking. In addition, a detailed simulation of a cermet design developed at the Argonne National Laboratory shows that modifications to the historical fuel element design are required to avoid overheating.
The final part investigates the ability of Star-CCM+ to model fuel element failure modes. Through a combination of uncertainty quantification and a parametric analysis, this thesis ultimately lays a groundwork for future detailed design of cermet NTR fuel elements.
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"Multiphysics Design Optimization Model for Structural Walls Incorporating Phase Change Materials." Master's thesis, 2013. http://hdl.handle.net/2286/R.I.18135.
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abstract: Buildings consume a large portion of the world's energy, but with the integration of phase change materials (PCMs) in building elements this energy cost can be greatly reduced. The addition of PCMs into building elements, however, becomes a challenge to model and analyze how the material actually affects the energy flow and temperatures in the system. This research work presents a comprehensive computer program used to model and analyze PCM embedded wall systems. The use of the finite element method (FEM) provides the tool to analyze the energy flow of these systems. Finite element analysis (FEA) can model the transient analysis of a typical climate cycle along with nonlinear problems, which the addition of PCM causes. The use of phase change materials is also a costly material expense. The initial expense of using PCMs can be compensated by the reduction in energy costs it can provide. Optimization is the tool used to determine the optimal point between adding PCM into a wall and the amount of energy savings that layer will provide. The integration of these two tools into a computer program allows for models to be efficiently created, analyzed and optimized. The program was then used to understand the benefits between two different wall models, a wall with a single layer of PCM or a wall with two different PCM layers. The effect of the PCMs on the inside wall temperature along with the energy flow across the wall are computed. The numerical results show that a multi-layer PCM wall was more energy efficient and cost effective than the single PCM layer wall. A structural analysis was then performed on the optimized designs using ABAQUS v. 6.10 to ensure the structural integrity of the wall was not affected by adding PCM layer(s).Dissertation/Thesis
M.S. Civil and Environmental Engineering 2013
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Huang, Chih-ping, and 黃志平. "Optimal Design of Heat Transfer Phenomena by the Integration of Experiment, SCGM, and Multiphysics Package on the High Power LED Array." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/30783752788817090205.
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碩士國立臺南大學
機電系統工程研究所碩士班
98
Abstract LED is a green light source that has more energy saving and longer lifetime than the traditional light. In fact, the input power of LED is about 15% to 30% converted into visible light, the remaining power is about 70% to 85% converted into heat. Because of the greater efficiency of LED, the LED''s market has been favored gradually. The advantages of LED are small size, long lifetime, good luminous efficiency, energy saving, environmental protection and faster startup. It is applied to the different field, likes traffic signal and large outdoor billboards, and LED plays an important role in the LED backlight and solid-state lighting applications. The purpose of this study is to investigate the thermal concentration of high power LED array to achieve optimal design. Because the high temperature will occur in high power LED arrays, which lead to the phenomena of heat concentration and non-uniform temperature will affect the lifetime, stability, and reliability of the LED. Consequently, the heat dissipation of high power LED becomes an important condition to promote the usage of efficiency. This research uses the experiments combining the simplified conjugate gradient method (SCGM) and the multiple physics software (COMSOL) to propose an optimal method. The results show that this proposed method can design high power LED arrays to achieve the best uniform temperature distribution. We are looking forware to the proposed method is helpful for solving the heat problem of high power LED array.
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(8066141), Nazanin Maani. "CFD MODELING IN DESIGN AND EVALUATION OF AN ENDOVASCULAR CHEMOFILTER DEVICE." Thesis, 2019.
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Intra-Arterial Chemotherapy (IAC) is a preferred treatment for the primary liver cancer, despite its adverse side-effects. During IAC, a mixture of chemotherapeutic drugs, e.g. Doxorubicin, is injected into an artery supplying the tumor. A fraction of Doxorubicin is absorbed by the tumor, but the remaining drug passes into systemic circulation, causing irreversible heart failure. The efficiency and safety of the IAC can be improved by chemical filtration of the excessive drugs with a catheter-based Chemofilter device, as proposed by a team of neuroradilogists.
The objective of my work was to optimize the hemodynamic and drug binding performance of the Chemofilter device, using Computational Fluid Dynamics (CFD) modeling. For this, I investigated the performance of two distinct Chemofilter configurations: 1) a porous “Chemofilter basket” formed by a lattice of micro-cells and 2) a non-porous “honeycomb Chemofilter” consisting of parallel hexagonal channels. A multiscale modeling approach was developed to resolve the flow through a representative section of the porous membrane and subsequently characterize the overall performance of the device. A heat and mass transfer analogy was utilized to facilitate the comparison of alternative honeycomb configurations.
A multiphysics approach was developed for modeling the electrochemical binding of Doxorubicin to the anionic surface of the Chemofilter. An effective diffusion coefficient was derived based on dilute and concentrated solution theory, to account for the induced migration of ions. Computational predictions were supported by results of in-vivo studies performed by collaborators. CFD models showed that the honeycomb Chemofilter is the most advantageous configuration with 66.8% drug elimination and 2.9 mm-Hg pressure drop across the device. Another facet of the Chemofilter project was its surface design with shark-skin inspired texturing, which improves the binding performance by up to 3.5%. Computational modeling enables optimization of the chemofiltration device, thus allowing the increase of drug dose while reducing systemic toxicity of IAC.
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Suryadevara, Vinay Kumar. "Low power steering electrodes within microfluidic channels for blood cancer cell separation for MRD applications." Thesis, 2015. http://hdl.handle.net/1805/10048.
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Indiana University-Purdue University Indianapolis (IUPUI)In this study, a novel model for manipulating cancer blood cells based on multi-stage micro channels under varied low field concepts is proposed. Steering Device approach was followed to manipulate the cancer cells based on their various differential potentials across their membranes. The proposed approach considers the size and the surface potential as well as the iso electronic structure of the cells. These research objectives emphasize the separation of the cells in the blood stream, and differentiates various blood cells and tumors for further analysis within the microfluidic channels. The dimensions of the channel sets the required electric field for manipulating the cancer cells within the channels using low electrode voltage function. The outcomes of this research may introduce a new diagnostic approach of finding the minimum residual disease (MRD) scans, early detection and analysis scans. This thesis provides a mathematical model, detailing the theory of the cell sorting device, manipulating the blood cancer cells and design of the device structure are also detailed, leading to the optimum research parameters and process. A Computer Aided Design (CAD) was used to model the multi-cell sorting lab-on-chip device, details of hardware and software were used in the simulation of the device various stages. Reverse engineering to configure the potentials for sorting mechanism needs is discussed. The thesis work also presents a comparative study of this sorting mechanism and the other commercially available devices. The practical model of the proposed research is laid out for future consideration.
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Garbin, Carlos Henrique Cano. "Analysis of the fire effect on loadbearing LSF walls and design of experimental test setup." Master's thesis, 2019. http://hdl.handle.net/10198/23199.
Full textAbstract:
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáThis work present a study of the fire behaviour of loadbearing LSF walls. This study was made with the development of model in finite elements and parametric analysis to evaluete the effects of steel section and plasterboard thickness on the fire resistance. It was also design the experimental test setup for future experimental researchs in IPB facilities. The model was developed with the use of shell elements for the steel structure and solid elements for the boards. It was made mechanic, termal and termo-mechanic simulations, that were validated with the use of experimental tests results previous realized in University of Queensland. The parametric analysis demostrated that the plasterboard thickness was of little effect in the fire behaviour of the wall, close to 3.5% of increase in the temperature evolution, what can be explained by the composite panel utilized. The steel section thickness however presented a greater influence, 58.15% of increase of the loadbeaing capacity of the wall.
Este trabalho apresenta um estudo do comportamento ao fogo de paredes portantes de LSF. Este estudo foi feito com o desenvolvimento de modelo em elementos finitos e análise paramétrica para avaliar os efeitos da seção de aço e da espessura da placa de gesso na resistência ao fogo. Também foi projetada a configuração do teste experimental para futuras pesquisas experimentais nas instalações do IPB. O modelo foi desenvolvido com a utilização de elementos de casca para a estrutura de aço e elementos sólidos para as placas. Foram feitas simulações mecânicas, térmicas e termo-mecânicas, que foram validadas com a utilização de resultados de testes experimentais realizados anteriormente na Universidade de Queensland. A análise paramétrica demonstrou que a espessura da placa de gesso teve pouco efeito no comportamento ao fogo da parede, cerca de 3,5% de aumento na evolução da temperatura, o que pode ser explicado pelo painel compósito utilizado. A espessura da seção de aço no entanto apresentou maior influência, 58,15% do aumento da capacidade de carga da parede.