Dissertations / Theses on the topic 'Heart valve modeling'
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Heinrich, Russell Shawn. "Assessment of the fluid mechanics of aortic valve stenosis with in vitro modeling and control volume analysis." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16664.
Full textBachlah, Dana Mohamad. "Modeling of the inner structural band of the aortic valve bio prosthesis." Bachelor's thesis, Igor Sikorsky Kyiv Polytechnic Institute, 2021. https://ela.kpi.ua/handle/123456789/43660.
Full textThe volume of the graduation work is 73 pages, contains 28 illustrations, 20 tables. In total 59 sources have been processed. Relevance: Aortic valve diseases lead to its severe dysfunction caused backflow on the valve or increased its resistance. The consequence of this pathology is severe heart failure, reduced duration and quality of life. The only treatment is surgical replacement of the valve with an artificial prosthesis or aortic valve plastic. Replacing of a sick aortic valve with an artificial prosthesis is an effective method of preventing heart failure, increasing duration and improving quality of life. Purpose: Modeling of the inner structural band of the aortic valve bio prosthesis. Tasks: to review literature on anatomy of blood vessels and heart valves; analyze and identify the problem; build inner structural band valve model in AutoCAD inventor; analyze the material options for the manufacture of the valve frame showed acceptable mechanical characteristics and biocompatibility. Main results: literature on related topics has been reviewed; comparative analysis of existing prototypes of artificial heart valves; selection of “biological nitinol”; 5 standard sizes of frame for aortic valve bio prosthesis was designed.
LaHaye, Stephanie Donna. "Discovering and Modeling Genetic Causes of Congenital Heart Disease." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492610446228702.
Full textGhotikar, Miheer S. "Aortic valve analysis and area prediction using bayesian modeling." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001369.
Full textGoddard, Aaron M. "A primarily Eulerian means of applying left ventricle boundary conditions for the purpose of patient-specific heart valve modeling." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6584.
Full textTHOMAS, VINEET SUNNY. "A Multiscale Framework to Analyze Tricuspid Valve Biomechanics." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1542255754172363.
Full textŠedivý, Dominik. "Proudění umělou srdeční chlopní." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241889.
Full textVan, Aswegen Karl. "Dynamic modelling of a stented aortic valve." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/1747.
Full textShojai, Leila. "Modelling of blood flow through heart valves and simulation of particle transport in blood." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/34645.
Full textDejvises, Jackravut. "Modelling of flexible heat demand and assessing its value in low carbon electricity systems." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10144.
Full textSpühler, Jeannette Hiromi. "Patient-Specific Finite Element Modeling of the Blood Flow in the Left Ventricle of a Human Heart." Doctoral thesis, KTH, Beräkningsvetenskap och beräkningsteknik (CST), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215277.
Full textQC 20171006
Sodhani, Deepanshu Verfasser], Stefanie [Akademischer Betreuer] [Reese, and Thomas [Akademischer Betreuer] Schmitz-Rode. "Artificial textile reinforced tubular aortic heart valves - multi-scale modelling and experimental validation / Deepanshu Sodhani ; Stefanie Reese, Thomas Schmitz-Rode." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1195237847/34.
Full textSodhani, Deepanshu [Verfasser], Stefanie [Akademischer Betreuer] Reese, and Thomas [Akademischer Betreuer] Schmitz-Rode. "Artificial textile reinforced tubular aortic heart valves - multi-scale modelling and experimental validation / Deepanshu Sodhani ; Stefanie Reese, Thomas Schmitz-Rode." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1195237847/34.
Full textGrasreiner, Sebastian. "Combustion modeling for virtual SI engine calibration with the help of 0D/3D methods." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2012. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-90518.
Full textModerne Ottomotoren spielen heute sowohl in konventionellen als auch hybriden Fahrzeugantrieben eine große Rolle. Aktuelle Konzepte sind hochvariabel bezüglich Ventilsteuerung, Kraftstoffeinspritzung und Laststeuerung und ihre Optimierungspotentiale erwachsen zumeist aus neuen Softwarefunktionen. Deren Applikation ist zeit- und kostenintensiv und soll durch virtuelle Methoden unterstützt werden. In der vorliegenden Arbeit wird ein physikalisches 0D Verbrennungsmodell für Ottomotoren aufgebaut und bis zur praktischen Anwendung geführt. Dafür wurde zuerst die Thermodynamik echtzeitfähig modelliert und im gesamten Motorenkennfeld abgeglichen. Der Aufbau eines neuen Turbulenzmodells auf Basis der quasidimensionalen k-epsilon-Gleichung ermöglicht anschließend, die veränderlichen Einflüsse globaler Ladungsbewegung auf die Turbulenz abzubilden. Für den Brennverzug wurde ein vereinfachtes Modell abgeleitet, welches den Übergang von laminarer zu turbulenter Flammenausbreitung nach der Zündung in den Vordergrund stellt. Der restliche Brennverlauf wird durch die physikalische Ermittlung der turbulenten Brenngeschwindigkeit in einem 0D Entrainment-Ansatz dargestellt. Nach Validierung aller Teilmodelle erfolgt die virtuelle Bedatung der Momentenstruktur und der Abgastemperaturfunktion für das Motorsteuergerät
Monleon, Jimenez Alex, and Roca David Villas. "Study of temperature raise in Gavleån river related to district cooling." Thesis, University of Gävle, Department of Building, Energy and Environmental Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-7129.
Full textThis project is a preliminary study in order to build a small power plant, located beside to Gavleån River. It has been designed with the aim of cooling a district of Gävle city, Sweden. That big project is carried out by the international consulting engineering company SWECO. The mentioned plant contains a thermodynamic cycle that takes water from the river and afterwards, it is returned back warmer. It will attempt to study the temperature raise downstream along the river due to the spill of hot water. In addition, it will try to quantify and weight which may be the importance of the increment of temperature compared to the entire river. This work could be vital for an environmental impact study. The thermo and fluid dynamic problem is going to be solved using typical procedure for numerical simulations. To do this, it will be used Computer Aided Design (CAD) to model Gavleån River path and Computational Fluent Dynamics (CFD) to predict the distribution of temperatures. Finally the results of the simulations will be analyzed and discussed to draw conclusions about the final temperature raise in Gavleån River.
Brejaud, Pascal. "Etude théorique et expérimentale d'un nouveau concept de moteur hybride thermique-pneumatique." Phd thesis, Université d'Orléans, 2011. http://tel.archives-ouvertes.fr/tel-00831692.
Full textГромик, Андрій Петрович, Андрей Петрович Громик, and A. P. Hromyk. "Математичне моделювання процесів теплопереносу в тонких пластинах." Thesis, Тернопільський національний технічний університет ім. Івана Пулюя, 2012. http://elartu.tntu.edu.ua/handle/123456789/1849.
Full textДисертація присвячена питанням математичного моделювання процесів теплопереносу в тонких пластинах різної геометричної форми, що описуються декартовою чи циліндричною системою координат, та побудові й дослідженню моделі випікання тонких плоских тістових заготовок. У роботі за найбільш загальних припущень у межах феноменологічної теорії теплопровідності вперше розроблено математичні моделі стаціонарного й нестаціонарного процесів теплопереносу в тонких пластинах у випадку, коли задача теплопереносу несиметрична відносно серединної площини пластини і коефіцієнти теплообміну з бічних поверхонь пластини різні. Методом головних розв’язків (фундаментальних функцій, функцій Коші та функцій Гріна) одержано у замкнутому вигляді точні розв’язки модельних крайових задач стаціонарного та нестаціонарного процесів теплопереносу для пластин різної конструкції. Для побудови головних розв’язків залучено відповідні інтегральні перетворення, породжені диференціальним оператором Фур’є чи диференціальним оператором Бесселя. Виконано аналітичне та комп’ютерне моделювання стаціонарного й нестаціонарного теплопереносу в процесах випікання тонких плоских тістових заготовок прямокутної та кругової форми. Досліджено вплив конструктивних і частотних (густинних) характеристик теплових джерел плити нагріву для забезпечення рівномірного нагріву тістових заготовок різних розмірів та отримання просторово-розподілених температурних розподілів заготовок з рівномірною інтенсивністю розподілу температур на їх поверхні.
Диссертационная работа посвящена вопросам математического моделирования процессов теплопереноса в тонких пластинах различной геометрической формы, описываемых декартовой или цилиндрической системами координат, а также построению и исследованию модели выпекания тонких плоских тестовых заготовок. В работе при наиболее общих предположениях в пределах феноменологической теории теплопроводности впервые разработано математические модели стационарного и нестационарного процессов теплопереноса для тонких изотропных пластин различной геометрии в декартовой и цилиндрической системах координат. Рассмотрен наиболее общий случай, когда задача теплопередачи асимметрична относительно срединной плоскости пластины и коэффициенты теплообмена с боковых поверхностей пластины разные. Как следствия выписаны решения для случаев, когда задача теплопередачи асимметрична или симметрична относительно срединной плоскости пластины и коэффициенты теплообмена с боковых поверхностей пластины равные. Методом главных решений (фундаментальных функций, функций Коши и функций Грина) в замкнутом виде получено точные решения модельных краевых задач стационарного и нестационарного процессов теплопереноса для пластин разной конструкции (прямоугольный клин, полоса-пластина, полуполоса-пластина, прямоугольная пластина; неограниченная цилиндрически-изотропная пластина с круговым вырезом и неограниченная клиновидная цилиндрически-изотропная пластина с вырезом в виде кругового сектора, цилиндрически-изотропная круговая пластина и цилиндрически-изотропная пластина в виде кругового сектора, цилиндрически-изотропная кольчатая пластина и кольчатая клиновидная цилиндрически-изотропная пластина). Для построения главных решений привлечены соответствующие интегральные преобразования для однородных сред, порожденные дифференциальным оператором Фурье (ось, полуось, сегмент), интегральные преобразования Фурье относительно угловой переменной, интегральные преобразования, порожденные дифференциальным оператором Бесселя (интегральные преобразования Вебера, Ганкеля 1-го и 2-го рода относительно радиальной переменной). Как следствия из общих решений получены наиболее часто встречаемые в инженерной практике случаи модельных задач для задания на границе пластины: распределения температуры по поверхности пластины в любой момент времени; плотности теплового потока; температуры окружающей среды и закона теплообмена между поверхностью тела и окружающей средой, а также их возможных комбинаций. Выполнено аналитическое и компьютерное моделирование стационарного и нестационарного теплопереноса в процессах выпекания тонких плоских тестовых заготовок прямоугольной и круговой формы. В результате компьютерного моделирования получено пространственно-распределенные температурные распределения заготовок с равномерной интенсивностью распределения температур на их поверхностях, на основании которых исследовано влияние конструктивных и частотных (плотностных) характеристик тепловых источников плиты нагревания для обеспечения равномерного нагревания тестовых заготовок разных размеров. Проведенный анализ дает возможность осуществлять обоснование более равномерных режимов нагревания и теплопереноса, что в целом существенно влияет на энерго- и ресурсосберегательные показатели теплоэнергетических и теплонагревательных установок.
The thesis is devoted to mathematical modeling of heat transfer in thin plates of different geometry described by Cartesian or cylindrical coordinate system, and the construction and study of models of thin flat baking dough preparations. In this dissertation, the most common assumptions within the phenomenological theory of heat was first formed mathematical models of stationary and non-stationary processes of heat transfer in thin plates where heat transfer problem is asymmetric relative to the median plane of the plate and the heat transfer coefficients of the lateral surfaces of the plate are different. The method of principal solutions (basic functions, Cauchy functions and Green's functions) are obtained in closed form exact solutions of boundary value problems modeling stationary and non-stationary processes of heat transfer to plates of various designs. To construct the main solutions involving the generation of the corresponding integral transformations differential operator Fourier or Bessel differential operator. Done the analytical and computer modeling of steady and unsteady heat transfer in the process of baking dough thin flat pieces of rectangular and circular shapes. The influence of structural and frequency (density) characteristics of thermal sources of heating plate to ensure uniform heating of the dough pieces in different sizes and a spatially distributed temperature distributions billets with uniform intensity distribution of temperature at the surface.
Auñón, García Ángel. "Development and validation of a virtual engine model for simulating standard testing cycles." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/168906.
Full text[CA] Les noves regulacions en matèria d'emissions d'efecte d'hivernacle i qualitat de l'aire han conduït la evolució tecnològica dels motors de combustió interna durant els darrers anys. Les millores en el procés de la combustió, la sobrealimentació, la gestió tèrmica, els sistemes de postractament i tècniques com la recirculació de gasos d'escapament, han permès que els motors de combustió interna d'avui dia siguen cada vegada més nets. L'adopció a Europa del nou cicle d'homologació WLTP, que considera un cicle de conducció més realista que el seu predecessor el NEDC, així com la necessitat d'avaluar les emissions de gasos contaminants en diferents escenaris de temperatura ambient i humitat, suposen un repte per als fabricants a l'hora de dissenyar i optimitzar els seus motors. En aquest context, el modelatge unidimensional del motor ofereix la possibilitat de desenvolupar i provar diferents solucions amb la suficient precisió, al mateix temps que agilitza el procés de disseny del motor i reduïx els costos derivats d'aquest. L'objectiu d'aquesta tesi és el de desenvolupar un model complete de motor virtual que permeta simular condicions transitòries de règim de gir i grau de càrrega, així com diferents condicions ambientals de pressió i temperatura. Amb aquest model de motor es pretén predir les principals variables termo-fluidodinàmiques en diferents punts del motor i les emissions contaminants alliberades en l'escapament. Per altra banda, l'arrancada en fred i el funcionament a baixes temperatures están associats a un major consum, majors emissions d'hidrocarburs (HC) i monòxid de carboni (CO), així com majors emissions d'òxids de nitrògen (NOx) degudes a la desactivació dels sistemes de recirculació de gasos d'escapament. Per a pal·liar aquestos efectes indesitjats, una opció és aconseguir que el sistema de postractament arribe a la seua temperatura d'activació el més prompte possible. En aquest treball, aquest objectiu s'aborda mitjançant dues solucions. Per una banda, s'ha investigat la possibilitat d'augmentar la temperatura dels gasos en l'escapament per mitjà d'un sistema de distribució variable. Amb aquest mètode s'ha aconseguit reduïr les emissions de CO i HC al voltant d'un 40-50 % i les emissions de NOx fins a un 15 % durant la primera fase del cicle WLTC, acosta d'una penalització en el consum de combustible. Per altra banda, també s'ha estudiat la possibilitat d'aïllar tèrmicament el sistema d'escapament. En aquest cas, és possible reduir les emissions de CO i HC vora un 30 % sense millorar les de NOx .
[EN] The new regulations regarding greenhouse emissions and air quality have led the technological progress of the internal combustion engines during the recent years. Improvements in the combustion process, turbocharging, thermal management, after-treatment systems and techniques such as the exhaust gases recirculation, have resulted in cleaner internal combustion engines. The adoption of the new type approval test in Europe, so-called WLTP, which represents a more realistic driving cycle than its forerunner the NEDC, as well as the need to evaluate pollutant emissions at different conditions of ambient temperature and altitude, represent a challenge for manufacturers when it comes to design and optimise their engines. In this context, one-dimensional engine models offer the possibility to develop and test different solutions with enough accuracy, while hastening the engine design process and reducing its costs. The main objective of this thesis is to develop a complete virtual engine model able to simulate transient conditions of engine speed and load, as well as different ambient conditions of pressure and temperature. The engine model is used to predict the main thermo-and fluid dynamic variables at different engine locations and the tailpipe pollutant emissions. Furthermore, engine cold start and its operation at low temperature is associated to a greater fuel consumption, hydrocarbon (HC) and carbon monoxide (CO) emissions; as well as more nitrogen oxide (NOx) emissions due to the deactivation of the exhaust gases recirculation systems. A solution to mitigate these negative effects is to heat up the after-treatment system so as to achieve its activation temperature as soon as possible. In the work presented, this goal is addressed through two different standpoints. On the one hand, variable valve timing systems have been studied as a way to increase the exhaust gases temperature. With this option it is possible to reduce CO and HC emissions by 40-50 % and NOx emissions by 15 % during the first stage of the WLTC cycle, at the expense of a penalty in the fuel consumption. On the other hand, the thermal insulation of the exhaust system has also been studied with the same objective. In this case, it is possible to reduce CO and HC emissions by 30 %, while not improving NOx ones.
The author wishes to acknowledge the financial support received through the FPI S2 2018 1048 grant of Programa de Apoyo para la Investigación y Desarrollo (PAID) of Universitat Politècnica de València.
Auñón García, Á. (2021). Development and validation of a virtual engine model for simulating standard testing cycles [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/168906
TESIS
Williston, Kyle Alexander. "Numerical Modeling of Large-Displacement Fluid-Structure Interaction: Preliminary Study Aimed at Analysis of Heart Valve Dynamics." 2012. http://hdl.handle.net/10222/15320.
Full textTatsiy, Roman, Marta Stasiuk, Oleg Pazen, and Sergiy Vovk. "Modeling of Boundary-Value Problems of Heat Conduction for Multilayered Hollow Cylinder." Thesis, 2018. http://hdl.handle.net/123456789/5207.
Full textTatsiy, Roman, Marta Stasiuk, Oleg Pazen, and Sergiy Vovk. "Modeling of Boundary-Value Problems of Heat Conduction for Multilayered Hollow Cylinder." Thesis, 2018. http://hdl.handle.net/123456789/5208.
Full textChaudhri, Masroor Mansoor. "Modelling of blood flow through mechanical heart valves using large eddy simulation." 2004. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=95164&T=F.
Full textТацій, Р. М., М. Ф. Стасюк, О. Ю. Пазен, and С. Я. Вовк. "Modeling of Boundary-Value Problems of Heat Conduction for Multilayered Hollow Cylinder ." Thesis, 2018. http://hdl.handle.net/123456789/5484.
Full textТацій, Р. М., М. Ф. Стасюк, О. Ю. Пазен, and С. Я. Вовк. "Modeling of Boundary-Value Problems of Heat Conduction for Multilayered Hollow Cylinder ." Thesis, 2018. http://hdl.handle.net/123456789/5485.
Full textIonasec, Razvan Ioan [Verfasser]. "Patient-specific modeling and quantification of the heart valves from multimodal cardiac images / Razvan Ioan Ionasec." 2010. http://d-nb.info/1009698133/34.
Full textMashishi, Daniel. "Modeling average monthly rainfall for South Africa using extreme value theory." Thesis, 2020. http://hdl.handle.net/10386/3399.
Full textThe main purpose of modelling rare events such as heavy rainfall, heat waves, wind speed, interest rate and many other rare events is to try and mitigate the risk that might arise from these events. Heavy rainfall and floods are still troubling many countries. Almost every incident of heavy rainfall or floods might result in loss of lives, damages to infrastructure and roads, and also financial losses. In this dissertation, the interest was in modelling average monthly rainfall for South Africa using extreme value theory (EVT). EVT is made up mainly of two approaches: the block maxima and peaks-over thresh old (POT). This leads to the generalised extreme value and the generalised Pareto distributions, respectively. The unknown parameters of these distri butions were estimated using the method of maximum likelihood estimators in this dissertation. According to goodness-of-fit test, the distribution in the Weibull domain of attraction, Gumbel domain and generalised Pareto distri butions were appropriate distributions to model the average monthly rainfall for South Africa. When modelling using the POT approach, the point process model suggested that some areas within South Africa might experience high rainfall in the coming years, whereas the GPD model suggested otherwise. The block maxima approach using the GEVD and GEVD for r-largest order statistics also revealed similar findings to that of the GPD. The study recommend that for future research on average monthly rainfall for South Africa the findings might be improved if we can invite the Bayesian approach and multivariate extremes. Furthermore, on the POT approach, time-varying covariates and thresholds are also recommended.
National Research Foundation (NRF) and South African Weather Service (SAWS)
Deep, Debanjan. "A study of blood flow in normal and dilated aorta." Thesis, 2013. http://hdl.handle.net/1805/4440.
Full textAtherosclerotic lesions of human beings are common diagnosed in regions of arte- rial branching and curvature. The prevalence of atherosclerosis is usually associated with hardening and ballooning of aortic wall surfaces because of narrowing of flow path by the deposition of fatty materials, platelets and influx of plasma through in- timal wall of Aorta. High Wall Shear Stress (WSS) is proved to be the main cause behind all these aortic diseases by physicians and researchers. Due to the fact that the atherosclerotic regions are associated with complex blood flow patterns, it has believed that hemodynamics and fluid-structure interaction play important roles in regulating atherogenesis. As one of the most complex flow situations found in cardio- vascular system due to the strong curvature effects, irregular geometry, tapering and branching, and twisting, theoretical prediction and in vivo quantitative experimental data regarding to the complex blood flow dynamics are substantial paucity. In recent years, computational fluid dynamics (CFD) has emerged as a popular research tool to study the characteristics of aortic flow and aim to enhance the understanding of the underlying physics behind arteriosclerosis. In this research, we study the hemo- dynamics and flow-vessel interaction in patient specific normal (healthy) and dilated (diseased) aortas using Ansys-Fluent and Ansys-Workbench. The computation con- sists of three parts: segmentation of arterial geometry for the CFD simulation from computed tomography (CT) scanning data using MIMICS; finite volume simulation of hemodynamics of steady and pulsatile flow using Ansys-Fluent; an attempt to perform the Fluid Structure Simulation of the normal aorta using Ansys-Workbench. Instead of neglecting the branching or smoothing out the wall for simplification as a lot of similar computation in literature, we use the exact aortic geometry. Segmen- tation from real time CT images from two patients, one young and another old to represent healthy and diseased aorta respectively, is on MIMICS. The MIMICS seg- mentation operation includes: first cropping the required part of aorta from CT dicom data of the whole chest, masking of the aorta from coronal, axial and saggital views of the same to extract the exact 3D geometry of the aorta. Next step was to perform surface improvement using MIMICS 3-matic module to repair for holes, noise shells and overlapping triangles to create a good quality surface of the geometry. A hexahe- dral volume mesh was created in T-Grid. Since T-grid cannot recognize the geometry format created by MIMICS 3-matic; the required step geometry file was created in Pro-Engineer. After the meshing operation is performed, the mesh is exported to Ansys Fluent to perform the required fluid simulation imposing adequate boundary conditions accordingly. Two types of study are performed for hemodynamics. First is a steady flow driven by specified parabolic velocity at inlet. We captured the flow feature such as skewness of velocity around the aortic arch regions and vortices pairs, which are in good agreement with open data in literature. Second is a pulsatile flow. Two pulsatile velocity profiles are imposed at the inlet of healthy and diseased aorta respectively. The pulsatile analysis was accomplished for peak systolic, mid systolic and diastolic phase of the entire cardiac cycle. During peak systole and mid-systole, high WSS was found at the aortic branch roots and arch regions and diastole resulted in flow reversals and low WSS values due to small aortic inflow. In brief, areas of sudden geometry change, i.e. the branch roots and irregular surfaces of the geom- etry experience more WSS. Also it was found that dilated aorta has more sporadic nature of WSS in different regions than normal aorta which displays a more uniform WSS distribution all over the aorta surface. Fluid-Structure Interaction simulation is performed on Ansys-WorkBench through the coupling of fluid dynamics and solid mechanics. Focus is on the maximum displacement and equivalent stress to find out the future failure regions for the peak velocity of the cardiac cycle.
Charikinya, Edson. "A modelling framework to determine the value proposition of microwave treatment of mineral ores." Thesis, 2011. http://hdl.handle.net/10019.1/6498.
Full textENGLISH ABSTRACT: The extraction of mineral values from ore requires liberation of the minerals followed by separation. Liberation is achieved by size reduction operations which are inefficient processes typically accounting for up to 70% of the energy consumption in a mineral concentrator (Tromans, 2008). As the grade of ores reserves declines, future viability of mineral operations will be determined by the costs of comminution. Recent work has shown that microwave treatment of secondary crusher product at specific microwave energy consumption of the order of 1 kWh/t reduces the work index of the ore and increases grade and recovery in batch flotation tests. Improved liberation at coarse sizes was also demonstrated (Kingman, 2006). Based on these findings work is ongoing to commercialise the technology. The objective of this study is to develop a modelling framework to determine the value proposition of microwave treatment of ore. It was noted that various models exist in literature for modelling of mineral processing flotation flow sheets, but these models do not incorporate the feed ore liberation property as an input variable in their calculations. Thus, a fundamentally derived property based model was identified as appropriate for flow sheet modelling of microwave treated ore, as it utilised liberation as an indirect variable in calculating the flotation rate constant through the use of contact angle to describe particle surface hydrophobicity. The model was successfully incorporated into the flotation flow sheet units developed in HSC Chemistry and used with Mineral Liberation Analyser (MLA) data to investigate the effects of changes in feed ore liberation on rougher cell flotation recovery. Different liberation scenarios based around modification of porphyry copper flotation feed were created. A sensitivity analysis of the various feed stream liberation scenarios was carried out to test the ability of the model to effectively model the differences in downstream processing of microwave treated and untreated ores. For a single flotation cell of size 85 m3 with a solids feed flow rate of 890 tph, it was observed that below a certain size (120 μm in the case of the porphyry copper ore) changes in flotation feed liberation had no significant effect on value mineral recovery. Significant differences in value mineral recovery were observed only at coarser sizes above 120 μm. The results indicated that improvement in recovery of value minerals due to improved liberation from applying microwave technology has size limits and is significantly dependent on the feed grind size. Feed grind size sensitivity analysis was then carried on the same single cell flow sheet utilising feeds with the same mineralogy but with different grind sizes. The results indicated that maximum benefits from the application of microwave technology would be best obtained by utilising coarse grinding at sizes between P70 = 200 μm and P70 = 300 μm for the porphyry copper ores considered in this study. Coarse grinding appears to be the best way to exploit improved liberation in downstream processing of microwave treated ores. Investigations similar to those carried out on the single cell flotation flow sheet were then carried out on a continuous plant rougher flotation flow sheet. The flow sheet consisted of nine rougher cells in series each with a volume of 85 m3 with a solids feed flow rate of 890 tph into the bank of rougher cells. The results indicated that there was no significant difference in final rougher bank overall cumulative recovery at fine grind sizes below a P70 grind size of 120 μm with improvements in feed ore liberation. Feed grind size sensitivity analysis showed a significant variation in cumulative recovery at coarse grind sizes of above P70 = 129 μm .This variation was attributed to improvements in flotation feed ore value mineral liberation from locked composite particles to the maximum possible theoretical liberation scenario of fully liberated value mineral particles. A 7.2 percentage point improvement in cumulative value mineral overall recovery and a 2 to 3 percentage point improvement in enrichment ratio was also observed above the P70 = 250 μm grind sizes after improving the flotation feed ore value mineral particle liberation of a typical flotation plant feed to a maximum. The increases in grade and cumulative recovery at coarse sizes were attributed to improvements to the flotation plant feed ore value mineral particle liberation. From the results, it was concluded that microwave technology application will offer greater benefits in downstream processing of coarse ground ores.
AFRIKAANSE OPSOMMING: Die ekstraksie van mineraalwaardes uit erts vereis bevryding van die minerale gevolg deur skeiding. Bevryding word bereik deur verkleiningsprosedures wat ondoeltreffende prosesse is en wat gewoonlik vir tot 70% van die energieverbruik in ʼn mineraalkonsentreerder verantwoordelik is (Tromans, 2008). Algaande die graad van ertsreserwes afneem, sal toekomstige lewensvatbaarheid van mineraalprosesse bepaal word deur die koste van vergruising. Onlangse werk het getoon dat mikrogolfbehandeling van sekondêre vergruiserproduk by spesifieke mikrogolf-energieverbruik van ongeveer 1 kWh/t die werkindeks van die erts verminder en die graad en opbrengs in lotflottasietoetse verhoog. Verbeterde bevryding by growwer groottes is ook aangetoon (Kingman, 2006). Werk gaan voort op grond van hierdie bevindinge ten einde die tegnologie te kommersialiseer. Die doel van hierdie navorsing is om ʼn modelleringsraamwerk te ontwikkel om die waardeproposisie van mikrogolfbehandeling van erts te bepaal. Daar is in die literatuur afgekom op verskeie modelle vir die modellering van vloeidiagramme vir flottasie van mineraalverwerking, maar hierdie modelle inkorporeer nie die voerertsbevrydingseienskap as ʼn insetveranderlike in hulle berekeninge nie. ʼn Fundamentele afgeleide eienskapgebaseerde model is geïdentifiseer as geskik vir vloeidiagrammodellering van mikrogolfbehandelde erts, aangesien dit bevryding as ʼn indirekte veranderlike by die berekening van die flotteertempokonstante aangewend het deur die gebruik van kontakhoek om hidrofobisiteit van die deeltjieoppervlak te beskryf. Die model is suksesvol in eenhede van die flottasievloeidiagram wat in HSC Chemistry ontwikkel is, geïnkorporeer en tesame met data van die mineraalbevrydingsontleder (MBO) gebruik om die gevolge van veranderinge in voerertsbevryding op die opbrengs van voorskeiselflottasie te ondersoek. Verskillende bevrydingscenario’s is geskep wat óm die modifisering van porfierkoperflotteringstoevoer heen gebaseer is. ʼn Sensitiwiteitsontleding van die verskillende voerstroombevrydingscenario’s is uitgevoer om die vermoë van die model om die verskille in stroomaf-verwerking van mikrogolfbehandelde en onbehandelde ertse te toets, doeltreffend te modelleer. In die geval van ʼn enkele flottasiesel van 85 m3 groot met ʼn vastestof-toevoervloeitempo van 890 tph, is waargeneem dat veranderinge in flottasietoevoer-bevryding benede ʼn sekere grootte (120 μm in die geval van die porfierkopererts) geen beduidende uitwerking op die opbrengs van die waardemineraal gehad het nie. Beduidende verskille in die opbrengs van die waardemineraal is slegs by growwer groottes bo 120 μm waargeneem. Die resultate het daarop gedui dat verbetering in die opbrengs van waardeminerale as gevolg van verbeterde bevryding ná die toepassing van mikrogolftegnologie beperkinge ten opsigte van grootte het en opvallend afhanklik is van die toevoermaalgrootte. Sensitiwiteitstoetsing van toevoermaalgrootte is daarna op dieselfde enkele selvloeidiagram wat voerders met dieselfde mineralogie gebruik uitgevoer, maar met verskillende maalgroottes. Die resultate het daarop gedui dat maksimum voordele van die toepassing van mikrogolftegnologie die beste verkry sou word deur gebruik van growwe maling by groottes tussen P70 = 200 μm en P70 = 300 μm vir die porfierkoperertse wat in hierdie navorsing in oorweging geneem is. Growwe maling skyn die beste manier te wees om verbeterde bevryding in stroomaf-verwerking van mikrogolfbehandelde ertse te eksploiteer. Ondersoeke soortgelyk aan dié wat op die vloeidiagram van die enkelselflottasie uitgevoer is, is toe op ʼn deurlopende vloeidiagram van die aanlegvoorskeierflottasie uitgevoer. Die vloeidiagram het bestaan uit nege voorskeiselle in serie elk met ʼn volume van 85 m3 met ʼn vastestof-toevoervloeitempo van 890 tph in die ry voorskeiselle. Die resultate het daarop gedui dat daar geen aanmerklike verskil in algemene kumulatiewe opbrengs van die finale voorskeiry by fyn maalgroottes benede ʼn P70-maalgrootte van 120 μm met verbeteringe in voerertsbevryding was nie. Sensitiwiteitsontleding van voermaalgrootte het ʼn beduidende variasie in kumulatiewe opbrengs by growwe maalgroottes van bo P70 = 129 μm getoon. Hierdie variasie is toegeskryf aan verbeteringe in waardemineraalbevryding van flottasietoevoererts uit geslote saamgestelde deeltjies tot die maksimum moontlike teoretiese bevrydingscenario van ten volle bevryde waardemineraaldeeltjies. ʼn Persentasiepuntverbetering van 7.2 in die kumulatiewe algemene opbrengs van waardemineraal en ʼn persentasiepuntverbetering van 2 tot 3 in die verrykingsratio is ook bo die P70 = 250 μmmaalgroottes waargeneem ná verbetering van die bevryding van die waardemineraaldeeltjies van die flottasietoevoererts van ʼn tipiese flottasieaanlegtoevoer tot die maksimum. Die toenames in graad en kumulatiewe opbrengs by growwe groottes is toegeskryf aan verbeteringe in die bevryding van die waardemineraaldeeltjies van die flottasietoevoererts. Op grond van die resultate is daar tot die gevolgtrekking gekom dat toepassing van mikrogolftegnologie groter voordele in stroomaf-verwerking van grofgemaalde ertse sal bied.
Pranoto, Bayu, and 尤卞藤. "Performance characteristic modeling of hybrid proton conducting solid oxide fuel cell (pSOFC) and micro gas turbine (MGT) system using a double bypass valve for heat management." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/20543560654441914584.
Full text國立中央大學
機械工程學系
104
Abstract Conducting Proton-Solid Oxide Fuel Cell (pSOFC), by attaching Micro Gas Turbine (MGT) is oneof the outstanding hybrid system nowadays. The intermediate temperature of pSOFC (around 700 – 800 [0C])is used to raise the performance of micro gas turbine in apower plantsystem. pSOFC has a lower temperature characteristic than old type of SOFC, which can afford more rapid start up/down and improve durability. A new model is proposed in the research based on themodels developed by earlier researchers.The proposed hybrid system is simulated using Matlab-Simulink. Simulations were performed to study the behavior of the pSOFC-MGT hybrid system by changing respective parameters such as pressure, steam to carbon ratio, and fuel utilization.In our research, we proposed, three different configurations by changing the bypass position in my proposed system i.e., with placing the bypass(i) after the combustor, (ii) after turbine, and (iii) after the combustor and turbine. The results show that the higher operating pressure will reduce system efficiency for configuration 1 and 2, and increase the efficiency for configuration 3. The effect of raising Steam to Carbon Ratio will reduce the efficiency of configuration 1 for anoperating pressure of 1 – 2 [bar], but it increasesthe efficiency of configuration 2 and configuration 3. The higherfuel utilization will increase the efficiency for all configurations. For bypass ratio variation, increase in bypass ratio will increase the efficiency of all configurations. Considering all the results ofconfiguration 3 provide the best performance compared to configuration 1 and 2 in all three models. The efficiencies of configuration 1, configuration 2, and configuration 3 are 49%, 63%, and68% respectively. The study obtained that using the overall heat exchanger over 5 W/K will not give an effect to configuration 3 performance so much. The cost analysis can be taken into consideration bychoosing an appropriate device to build a configuration 3 model. The exergy analysis has a same tendency with energy analysis, but it will different in value. Due to the exergy destruction during the process, the value of energy is higher than exergy. To know an amount of exergy destruction, it carried out thecalculations based on the amount of entropy generation and found the devices that have lost exergy from the largest to the smallest in a sequence is combustor 60.2[kW], pSOFC 22.8 [kW] Compressor 21.7 [kW], Pump 5.5 [kW], Fuel Heater 0.9 [kW], reformer 0.7 [kW], water heater 0.4 [kW], air heater 0.23 [kW], and MGT 0.21 [kW]. Keywords: Proton-Conducting Solid Oxide Fuel Cell (pSOFC), Micro Gas Turbine (MGT), Matlab-Simulink, Hybrid configuration mode