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1
Gupta, Shailesh. „Mathematical Modeling of Thin Strip Casting Processes“. The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1391679731.
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Ramírez, Marco Aurelio (Ramírez-Argáez) 1970. „Mathematical modeling of D.C. electric arc furnace operations“. Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/8847.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2000.Vita.
Includes bibliographical references (leaves 236-240).
A fundamental study of the Direct Current Electric Arc Furnace (DC-EAF) for steel-making has been carried out through the development of a rigorous mathematical model. The mathematical representation involves the simultaneous solution of Maxwell's equations for the electromagnetic fields, and the turbulent fluid flow and heat transfer equations. In solving the arc and bath regions it was assumed ( and justified) that the arc-bath interactions are dominated by the behavior of the arc. In contrast to previous modeling investigations, this work relaxes some critical assumptions and provides a more realistic and comprehensive representation of the system. This work also examines and compares the relative merits of alternative electromagnetic and turbulence formulations, and addresses the role of induced currents and compressibility effects in the representation of the arc. Furthermore, due allowance was made to represent and analyze the effect of gas injection, the presence of a slag layer in the bath and changes in anode configuration at the bottom of the reactor. Because of a lack of experimental information on actual or pilot plant DC-EAF systems, different aspects of the model were validated using several sources of experimental data reported in the literature for related systems. These included measurements on welding arcs, laboratory scale high-intensity carbon arcs, electromagnetically driven metallic systems, and ladle metallurgy physical models. It was found that, in general, the agreement between measurements and predictions was good. A detailed analysis was carried out to examine the effect of process parameters (e.g., arc current, arc length, bath dimensions, anode arrangements, etc) on the behavior of the furnace (e.g., heat transfer to the bath, heating efficiency, mixing times in the bath, etc). Predictions from the arc model show that all the arc characteristics are strongly coupled and that the arc physics is governed by the expansion of the arc. From a parametric study it was found that when the arc region (defined by the 10,000 K isotherm) is plotted in dimensionless form, a universal shape for the arc can be defined, regardless of the values of arc current or arc length. This universality was restricted to the range of conditions analyzed in this thesis, to arcs struck between graphite cathodes in air, and does not include the jet impingement region on the bath surface. This common arc expansion behavior suggested the universal nature of other arc characteristics. Universal maps of temperature, magnetic: flux density, and axial velocity are also reported in terms of simple analytical expressions. The practical effects of the two main process parameters of the arc region,. i.e. the arc current and the arc length, were analyzed. It was found that increasing the arc length significantly increases the arc resistance and, consequently, the arc power, although this behavior reached asymptotic values at larger arc lengths. Increasing the arc current, however, does not affect the arc voltage. Thus, it is found that increasing the arc power increases the amount of energy transferred into the bath, but the heat transfer efficiency decreases. Therefore, the shorter the arc the more efficient is the heat transfer to the bath. It is also recognized that heat transfer from the arc to the bath is controlled by convection, although radiation can become an important mechanism, especially for large arc lengths. Results of the bath model indicate that, in the absence of inert gas stirring and with no slag present in the system, electromagnetic body forces dominate and are responsible for the fluid flow patterns in the system. The effects of the arc determine the distributions of temperature and other mixing characteristics in the bath. The bath model was used to evaluate the effect of the main process parameters and design variables on mixing, refractory wear, temperature stratification, and heat transfer efficiency. An increase in the arc length is detrimental to mixing but increases the rate of heating in the melt as a result of the increased arc power. Increasing arc current improves mixing and the heat transferred to the bath, but is likely to be detrimental to the life of the bottom refractory. The results also suggest that high furnace aspect ratios (taller and thinner arc furnaces) are highly recommended because an increase in the aspect ratio increases mixing, prevents refractory wear, and promotes arc heating efficiency. The arc configuration in the furnace can be changed to control fluid flow patterns in the bath to meet specific needs, such as better mixing, or to prevent refractory wear. The presence of a top layer of slag reduces mixing and increases overall liquid temperatures. Injection of gases through the bottom in eccentric operations generates complex flow patterns that improve mixing in regions away from the symmetry axis. It is the author's belief that this model is a useful tool for process analysis in the DC-EAF. It has the capability to address many issues of current and future concern and represents one component of a fundamental approach to the optimization of DC-EAF operations.
by Marco Aurelio Ramírez.
Ph.D.
3
Weens, William. „Mathematical modeling of liver tumor“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00779177.
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Comme démontre récemment pour la régénération du foie après un dommage cause par intoxication, l'organisation et les processus de croissance peuvent être systématiquement analyses par un protocole d'expériences, d'analyse d'images et de modélisation [43]. Les auteurs de [43] ont quantitativement caractérise l'architecture des lobules du foie, l'unité fonctionnelle fondamentale qui constitue le foie, et en ont conçu un modèle mathématique capable de prévoir un mécanisme jusqu'alors inconnu de division ordonnée des cellules. La prédiction du modèle fut ensuite validée expérimentalement. Dans ce travail, nous étendons ce modèle a l'échelle de plusieurs lobules sur la base de résultats expérimentaux sur la carcinogène dans le foie [15]. Nous explorons les scénarios possibles pouvant expliquer les différents phénotypes de tumeurs observés dans la souris. Notre modèle représente les hépatocytes, principal type de cellule dans le foie, comme des unités individuels avec un modèle a base d'agents centré sur les cellules et le système vasculaire est représenté comme un réseau d'objets extensibles. L'équation de Langevin qui modélise le mouvement des objets est calculée par une discrétisation explicite. Les interactions mécaniques entre cellules sont modélisées avec la force de Hertz ou de JKR. Le modèle est paramètre avec des valeurs mesurables a l'échelle de la cellule ou du tissue et ses résultats sont directement comparés avec les résultats expérimentaux. Dans une première étape fondamentale, nous étudions si les voies de transduction du signal de Wnt et Ras peuvent expliquer les observations de [15] où une prolifération instantanée dans les souris mutées est observée seulement si 70% des hépatocytes sont dépourvues d'APC. Dans une deuxième étape, nous présentons une analyse de sensibilité du modèle sur la rigidité de la vasculature et nous la mettons en relation avec un phénotype de tumeur (observe expérimentalement) où les cellules tumorales sont bien différentiées. Nous intégrons ensuite dans une troisième 'étape la destruction de la vasculature par les cellules tumorales et nous la mettons en relation avec un autre phénotype observe expérimentalement caractérise par l'absence de vaisseaux sanguins. Enfin, dans la dernière étape de notre étude nous montrons que des effets qui sont détectables dans les petits nodules tumoraux et qui reflètent les propriétés des cellules tumorales, ne sont plus présents dans la forme ou dans le phénotype des tumeurs d'une taille excédant la moitié de celle d'un lobule.
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Badekas, Paris. „Mathematical modeling of en route ATC intervention rates“. Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14746.
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Deering, Scott E. (Scott Earl) 1967. „Mathematical and physical modeling of flip-chip soldering processes“. Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11115.
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Saxena, Amit. „Mathematical modeling of horizontal twin roll thin strip casting process“. The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392309532.
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Groshong, Kimberly A. „Defining mathematical modeling for K-12 education“. The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534374871189434.
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Muthukumaran, Arun. „Foam-mat freeze drying of egg white and mathematical modeling“. Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18301.
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Eggs are a rich source of high-quality proteins as they contain all amino acids necessary for the human body. They also contain all vitamins (except for vitamin C) and many essential minerals. Eggs mainly consist of egg white (albumen) and egg yolk. Egg white is mainly made up of proteins and has excellent foaming properties; it is widely used in the baking and confectionary industries (e.g., cake mixtures, meringue). Dehydration is widely used for the preservation of egg. Dehydrated egg products usually have a shelf life of one year under refrigeration. Spray drying and pan drying are widely used for producing egg powder. The higher drying temperature associated with these drying methods could adversely affect the nutritional value of egg. Freeze drying is well known for its excellent dehydrated product quality. The high cost of operation associated with freeze drying restricts its usage to high value products like coffee. Foam-mat drying can be used for the products that can be foamed to increase the surface area to improve the mass transfer rate. But the higher drying temperature involved in this method is not suitable for producing a high quality dehydrated product. Foam-mat freeze drying is one of the promising methods of drying, which tries to utilize the advantages of both freeze drying and foam-mat drying to produce better quality egg white powder. Preliminary experiments showed that the stability of foams made with egg white alone is not adequate for foam-mat freeze drying. Experiments were thus conducted using different stabilizers (Methyl cellulose, Propylene glycol alginate and Xanthan gum) to optimize foam stability. Bubble size distribution was determined using microscopy to understand foam structure. The results showed that Xanthan gum at 0.125% provide sufficient stability for freeze drying. Experiments were conducted to study foam-mat freeze drying of egg white, in an effort to determine the suitability of this method. The results showed that thLes œufs sont une bonne source de protéines de haute qualité, puisqu’ils contiennent tous les acides aminés nécessaires au corps humain. Les œufs contiennent aussi toutes les vitamines (à l’exception de la vitamine C), ainsi que plusieurs minéraux essentiels. Les œufs sont principalement constitués de l’albumine (blanc d’œuf) ainsi que le jaune d’œuf. L’albumine est principalement consituée de protéines et a d’excellentes propriétés de moussage. Elle est utilisée à grande échelle dans les industries boulangère et de la confiserie, par exemple dans les mélanges à gâteaux et de la meringue. On utilise beaucoup la déshydratation pour préserver les oeufs. Réfrigérés, les produits d’œuf déshydraté se conservent pendant un an. Le séchage par atomisation et le séchange par conduction sont couramment utilisés pour produire de la poudre d’œuf. Par contre, les températures élevées associées à ces méthodes de séchage pourraient compromettre la valeur nutritive des œufs. La cryodessication donne un produit déshydraté de très haute qualité, mais les coûts d’opération élevés limitent son utilisation qu’aux produits de haute valeur, tel le café. Le séchage par émulsion peut être utilisé lorsque les produits à sécher peuvent mousser, ce qui accroît la surface de contact et augmente le coefficient d'échange thermique. Cependant, les températures élevées associées à cette méthode ne conviennent pas à la production d’un produit déshydraté de haute qualité. La cryodessication par émulsion est une méthode de séchage prometteuse, puisqu’elle tire des avantages liés à la cryodessication et au séchage par émulsion pour produire de la poudre d’albumine de meilleure qualité. Des essais en laboratoire ont démontré que la stabilité des mousses de blanc d’œuf ne convient pas au séchage par émulsion. Des expériences ont donc été entreprises dans le but de trouver un stabiliseu
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Kriek, Andre. „RoboCup formation modeling“. Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2810.
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Thesis (MSc (Mathematical Sciences. Computer Science))--University of Stellenbosch, 2009.Since the late 1990s, the Robot Soccer World Cup has been used as a testing ground for new technology in the eld of robotic design and arti cial intelligence. This research initiative pits two teams of robots against each other in a game of soccer. It is hoped that the technology gained will enable the construction of a fully autonomous team of robot players to play a normal soccer game against a human team by the year 2050. In robot soccer matches, as in real soccer matches, inferring an opponent's strategy can give a team a major advantage. One important aspect of a team's strategy is the formation the team uses. Knowing the formations that an opposing team tends to take, enables a team to prepare appropriate countermeasures. This thesis will investigate methods to extract formation information from a completed soccer game. The results show that these methods can be used to infer a classical team formation, as well as other distinguishing characteristics of the players, such as which areas on the eld the players tend to occupy, or the players' movement patterns - both valuable items of information for a future opposition team.
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Yau, Shuk-Han Ada. „Numerical analysis of finite difference schemes in automatically generated mathematical modeling software“. Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35407.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 64-65).
by Shuk-Han Ada Yau.
M.S.
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Alagoz, Duriye Ece. „Mathematical Modeling Of Fluidized Bed Combustors With Radiation Model“. Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607489/index.pdf.
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Simultaneous solution of the conservation equations for energy and chemical species in conjunction with radiative transfer equation was carried out by coupling a previously developed and tested system model of fluidized bed combustion (FBC) to an existing radiation model.
The predictive accuracy of the coupled code was assessed by applying it to 0.3 MWt METU Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) Test Rig burning lignite in its own ash and comparing its predictions with the measured temperatures and concentrations of gaseous species along the combustor and radiative heat fluxes incident on the refractory-lined freeboard walls on two combustion tests, with and without recycle. The predictions of the coupled code were found to be in good agreement with the measurements.
For the investigation of the significance of coupling of the radiation model to the system model, temperature predictions of the coupled code were compared with those obtained by the original system model. It was found that the effect of incorporating a radiation model into the system model on the predictions was not significant because the high temperatures of refractory-lined freeboard walls and high surface to volume ratio of the test rig under consideration cause the incident radiative heat fluxes to be dominated by walls rather than the particle laden gas emissions. However, in industrial boilers, freeboard is surrounded by water-cooled membrane walls and boilers have much lower surface to volume ratio. In order to examine the effects of both on radiation in industrial boilers, an investigation was carried out on 16 MWt Stationary Fluidized Bed Boiler (SFBB) by applying radiation model, in isolation from the system model, to the freeboard of the boiler. It was found that in the boiler, incident radiative heat fluxes were dominated by particle laden gas emissions.
In brief, the coupled code proposed in this study proves to be a useful tool in qualitatively and quantitatively simulating the processes taking place in an atmospheric fluidized bed boilers.
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Alghamdi, Faisal. „Mathematical modeling of mean flow stress (MFS) during hot strip rolling for HSLA steels“. Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123280.
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Based on experimental results using hot torsion, the effect of 'time gap', i.e. the time between roughing and finishing in a hot rolling schedule simulation, on mean flow stress (MFS) behavior for high-strength-low-alloyed (HSLA) steels was investigated. Two types of hot deformation were studied: an 'average' schedule with constant interpass time, in which each pass is identical but the temperature is decreasing at a constant rate throughout the rolling schedule simulation. In this type of schedule, two different interpass times of 5 and 30 seconds were used to study the influence of precipitation hardening on the MFS behavior. For the 5 seconds interpass time, where solute drag is main mechanism responsible for preventing recrystallization, a new method was proposed to determine the temperature of no recrystallization (Tnr). The second type is based on an average schedule of 5 seconds interpass time but with incorporating time gaps of 10, 20 and 45 seconds at two different temperature ranges, i.e. above and below the temperature of no recrystallization (Tnr). Through the analysis of MFS vs. 1000/T diagrams, the results indicated phenomena such as static recrystallization and/or precipitation hardening take place during this time gap. A mathematical model for MFS prediction was developed and validated with hot torsion data. The evolution of grain size, precipitate weight fraction and the effect of fractional softening on strain accumulation were also predicted by the model. The model is able to predict the critical strain per pass and therefore the fractional softening associated to dynamic recrystallization. Generally, there is a good agreement between the experimental and predicted mean flow stress over the whole deformation schedule. However, some discrepancy on the MFS values was observed for the first few passes of finishing stage especially when precipitation hardening is more likely to occur. Finally, several points are suggested to accommodate this discrepancy for future work.A l'aide des résultats d'expériences qui utilisent la torsion à chaud, l'effet causé par «l'écart chronologique » est analysé (ex. le délai entre l'ébauchage et le finissage du schéma de laminage à chaud et le comportement de la contrainte d'écoulement moyenne des aciers à haute résistance mécanique). Deux types de déformation à chaud ont été étudiés : un schéma moyen au temps d'interpasse constante, dans lequel chaque passe est identique, dont la température diminue à un rythme régulier au cours du programme de laminage. Dans ce type de schéma, un intervalle de 5 et de 30 secondes sont utilisés afin d'étudier l'influence du durcissement structural sur le comportement de la contrainte d'écoulement moyenne. Aux 5 secondes d'interpasse, où le dragage est le mécanisme responsable qui empêche la recristallisation, une nouvelle méthode est proposée pour déterminer la température à laquelle la recristallisation n'est plus complète (Tnr). Pour ce qui est du 30 secondes d'interpasse, l'expérience s'inspire du schéma aux 5 secondes d'interpasse, en y ajoutant des intervalles de 10, 20 et 45 secondes à deux niveaux de température (ex. Au-dessus et en dessous de la température à laquelle la recristallisation n'est plus complète (Tnr). Selon les résultats d'analyse de la contrainte d'écoulement moyenne dans les diagrammes de 1000/T, des phénomènes tels que la recristallisation posttectonique et/ou le durcissement structural ont eu lieu durant ce temps d'attente. Un modèle mathématique servant à prédire la contrainte d'écoulement moyenne est développé et validé avec les données des expériences qui utilisent la torsion à chaud. L'évolution de la taille de grain, la fraction massive de précipité et l'effet d'adoucissement sur la déformation accumulée peuvent tous être calculés par le modèle. Ce dernier est capable de mesurer la déformation critique au cours d'une passe et ainsi, déduire l'adoucissement associé à la recristallisation syntectonique. En général, au niveau de la contrainte d'écoulement moyenne, l'hypothèse et le résultat d'expérience du schéma de déformation se rejoignent en grande partie. Toutefois, quelques divergences sur celle-ci sont observées durant les premières passes du finissage surtout lorsqu'un durcissement structural est plus susceptible à se produire. Finalement, plusieurs points sont suggérés dans le but de combler ces lacunes dans les expériences à venir.
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Ivosevic, Milan Cairncross Richard A. Knight Richard. „Splat formation during thermal spraying of polymer particles : mathematical modeling and experimental analysis /“. Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1121.
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Wang, Shihu. „Computer Simulation and Mathematical Modeling of Reversibly Associated Polymers“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1275488088.
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Schliemann, Bernd F. „Analysis and modeling of the initiative tenet of current army operations doctrine“. Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/25091.
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Hwang, Dae Kun 1972. „Mathematical modeling of heterocyclic amines formation in meat patties during pan frying“. Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33778.
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The formation of heterocyclic amines (HAs) have been proven to be carcinogenic and mutagenic and these compounds have been found in cooked food such as meat, poultry, and fish. There are strong relationships between potential cancer development and HAs through intake of the cooked food.The yield of HAs along with the influence of fat content and soy protein on the formation of HAs were determined during heating (as in cooking) at different temperatures using the kinetic modeling approach. The formation of HAs is dependent on temperature, time, fat content, and soy protein. The increase of fat content in samples resulted in a lower concentration of HAs' concentrations and a lower activation energy of reaction. Fat apparently enhanced the formation of HAs in meats but diluted availability of precursors for reactions. An increase in soy protein concentration decreased the maximum concentration of HAs formed in the different cooking conditions.
Two different approaches were used in order to model the formation of HAs. First, an artificial neural network (ANN) was used with two data sets to train and test the ANN. An ANN consisting of 18 processing elements and two hidden layers showed the best performance for predicting the formation of HAs. Second, the formation of HAs were predicted using temperature profiles in a cooked sample during pan-frying. The temperature profiles in cooked meat patty were predicted using finite element method. The concentration of HAs depended on the meat patty's surface temperature developed during pan frying. The result of this study can be used to develop methods to reduce HAs in food thus optimize product quality and safety.
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Lebo, Matthew Jonathan. „Fractional Integration and Political Modeling“. Thesis, University of North Texas, 1999. https://digital.library.unt.edu/ark:/67531/metadc2229/.
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This dissertation investigates the consequences of fractional dynamics for political modeling. Using Monte Carlo analyses, Chapters II and III investigate the threats to statistical inference posed by including fractionally integrated variables in bivariate and multivariate regressions. Fractional differencing is the most appropriate tool to guard against spurious regressions and other threats to inference. Using fractional differencing, multivariate models of British politics are developed in Chapter IV to compare competing theories regarding which subjective measure of economic evaluations best predicts support levels for the governing party; egocentric measures outperform sociotropic measures. The concept of fractional cointegration is discussed and the value of fractionally integrated error correction mechanisms are both discussed and demonstrated in models of Conservative party support. In Chapter V models of presidential approval in the United States are reconfigured in light of the possibilities of fractionally integrated variables. In both the British and American case accounting for the fractional character of all variables allows the development of more accurate multivariate models.
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Chepete, Poloko. „Modeling of the factors affecting mathematical achievement of Form 1 students in Botswana based on the 2003 Trends in International Mathematics and Science Study“. [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3319920.
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Thesis (Ph.D.)--Indiana University, Dept. of Curriculum and Instruction, Mathmatics Education, 2008.Title from PDF t.p. (viewed on May 13, 2009). Source: Dissertation Abstracts International, Volume: 69-08, Section: A, page: 3074. Adviser: Frank K. Lester.
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Deshpande, Rutooj D. „UNDERSTANDING AND IMPROVING LITHIUM ION BATTERIES THROUGH MATHEMATICAL MODELING AND EXPERIMENTS“. UKnowledge, 2011. http://uknowledge.uky.edu/cme_etds/4.
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There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary.
One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result of lithium diffusion during charging and discharging operations. When lithium is inserted in either the positive or negative electrode, there is a volume change associated with insertion or de-insertion. Diffusion-induced stresses (DISs) can therefore cause the nucleation and growth of cracks, leading to mechanical degradation of the batteries. With different mathematical models we studied the behavior of diffusion induces stresses and effects of electrode shape, size, concentration dependent material properties, pre-existing cracks, phase transformations, operating conditions etc. on the diffusion induced stresses. Thus we develop tools to guide the design of the electrode material with better mechanical stability for durable batteries.
Along with mechanical degradation, chemical degradation of batteries also plays an important role in deciding battery cycle life. The instability of commonly employed electrolytes results in solid electrolyte interphase (SEI) formation. Although SEI formation contributes to irreversible capacity loss, the SEI layer is necessary, as it passivates the electrode-electrolyte interface from further solvent decomposition. SEI layer and diffusion induced stresses are inter-dependent and affect each-other. We study coupled chemical-mechanical degradation of electrode materials to understand the capacity fading of the battery with cycling. With the understanding of chemical and mechanical degradation, we develop a simple phenomenological model to predict battery life.
On the experimental part we come up with a novel concept of using liquid metal alloy as a self-healing battery electrode. We develop a method to prepare thin film liquid gallium electrode on a conductive substrate. This enabled us to perform a series of electrochemical and characterization experiments which certify that liquid electrode undergo liquid-solid-liquid transition and thus self-heals the cracks formed during de-insertion. Thus the mechanical degradation can be avoided. We also perform ab-initio calculations to understand the equilibrium potential of various lithium-gallium phases.
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Acuña-Agost, Rodrigo. „Mathematical modeling and methods for rescheduling trains under disrupted operations“. Phd thesis, Université d'Avignon, 2009. http://tel.archives-ouvertes.fr/tel-00453640.
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En raison de problèmes opérationnels et d'autres événements inattendus, un grand nombre d'incidents se produisent quotidiennement dans les systèmes de transport ferroviaire. Certains d'entre eux ont un impact local, mais quelques fois, essentiellement dans les réseaux ferroviaires plus saturés, des petits incidents peuvent se propager à travers tout le réseau et perturber de manière significative les horaires des trains. Dans cette thèse doctorale, nous présentons le problème de réordonnancement de plan de circulation ferroviaire en cas d'incident comme la problématique de créer un plan de circulation provisoire de manière à minimiser les effets de la propagation des incidents. Ce travail est issu du projet MAGES (Module d'Aide à la Gestion des Sillons) qui développe des systèmes de régulation pour le trafic ferroviaire. Nous présentons deux modèles différents qui permettent de trouver des solutions à ce problème : Programmation Linéaire en Nombres Entiers (PLNE) et Programmation Par Contraintes (PPC). Du fait de la nature fortement combinatoire du problème et de la nécessité de répondre rapidement aux incidents, il ne paraît pas raisonnable d'envisager une résolution exacte. Les méthodes correctives proposées consistent donc à explorer un voisinage restreint des solutions : right-shift rescheduling; une méthode basée sur des coupes de proximité; une méthode d'analyse statistique de la propagation des incidents (SAPI) et un méthode basée sur la PPC. Additionnellement, certaines de ces méthodes ont été adaptées sous forme d'algorithmes itératifs avec l'objectif d'améliorer progressivement la solution quand le temps d'exécution le permet. SAPI est une des principales contributions de cette thèse. SAPI intègre les concepts de right-shift rescheduling avec les coupes de proximité. Du fait de la taille des réseaux en jeu et du nombre de circulations, les phénomènes complexes de propagation d'un incident font qu'il est très difficile de connaitre de manière précise les événements qui seront affectés. Toutefois, il est tout de même envisageable d'évaluer la probabilité qu'un événement soit affecté. Pour calculer cette probabilité, un modèle de régression logistique est utilisé avec des variables explicatives dérivées du réseau et des circulations. Diverses variantes de ces méthodes sont évaluées et comparées en utilisant deux réseaux ferroviaires localisés en France et au Chili. À partir des résultats obtenus, il est possible de conclure que SAPI est meilleure que les autres méthodes en terme de vitesse de convergence vers l'optimum pour les instances de petite taille et moyenne alors qu'une méthode coopérative PNLE/PPC est capable de trouver des solutions pour les instances de plus grande taille. La difficulté de comparer SAPI avec d'autres méthodes présentées dans la littérature nous a encouragés à appliquer la méthode à un autre problème. Ainsi, cette méthodologie a été également adaptée au problème de réordonnancement de passagers, vols et appareils (avions) en cas de perturbations, problème originalement proposé dans le contexte du Challenge ROADEF 2009. Les résultats montrent que SAPI est efficace pour résoudre ce problème avec des solutions au-dessus de la moyenne des équipes finalistes en obtenant la troisième place du challenge
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Davary, Kamran. „Soil moisture redistribution modeling with artificial neural networks“. Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36905.
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This study sought to investigate the application of artificial neural networks (ANN) and fuzzy inference systems (FIS) to variably saturated soil moisture (VSSM) redistribution modelling. An enhanced approach to such modelling, that lessens computation costs, facilitates input preparation, handles data uncertainty, and realistically simulates soil moisture redistribution, was our main objective.An initial review of existing soil hydrology models provided greater insight into current modelling challenges and a general classification of the models. The application of AI techniques as alternative tools for soil hydrology modelling was explored.
A one-dimensional (1D) model based on ANN and FIS was developed. To estimate fluxes more accurately, multiple ANNs were trained and combined by way of an FIS. The main body of the model employed the ANN-FIS module to model soil moisture redistribution throughout the profile. When tested against the SWAP93 model, the ANN-FIS model gave a good match and maximum error of <8%; however, it did not show a notable computation cost shift.
The investigation proceeded with development of another ANN-based 1D modelling approach. This time, the soil profile or flow region, regardless of its depth, was divided into ten equal parts (compartments). The ANN was trained to estimate moisture patterns for a whole soil profile, from the previous day's soil moisture pattern and boundary conditions, and the current day's boundary conditions. The model was tested against SWAP93 where an average SCORE of 90.4 indicated a good match. The computation cost of the ANN-based model was about one-third that of SWAP93.
At this point the study sought to develop a 3D modelling approach. The ANN was trained to estimate the nodal soil moisture changes through time under the influence of six neighbouring nodes (in a 3D space, two on each axis). The model's accuracy was tested against the SWMS-3D model. An average SCORE of 91 and a 15-fold decrease in computation costs showed a quite acceptable performance. Results suggest that this approach is potentially capable of realistically modelling 3D VSSM redistribution with less computation time.
Finally, pros and cons of these ANN-based modelling approaches are compared and contrasted, and some recommendations on future work are given.
22
George, Gary R. „New methods of mathematical modeling of human behavior in the manual tracking task“. Diss., Online access via UMI:, 2008.
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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008.Includes bibliographical references.
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Horn, Jonathan Douglas. „EcoLE-FisH-YP: Mathematical modeling of Lake Erie yellow perch recruitment and population dynamics“. The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282003300.
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Torgerson, Scott Robert. „Mathematically modeling the effects of low-level learning in combat simulations and war games“. Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/25097.
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Yee, Sean P. „Students' Metaphors for Mathematical Problem Solving“. Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1340197978.
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Robison, Pamula J. „Mathematical Modelling of Biofilm Growth and Decay Through Various Deliveries of Antimicrobial“. University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1258769688.
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Crosby, Jacy Rebecca. „Modeling and Synergy Testing of Drug Combination Data: A Pharmacokinetic Analysis“. UNF Digital Commons, 2008. http://digitalcommons.unf.edu/etd/143.
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In this paper, we present and implement a method to assess the mathematical synergy of two-drug combinations based on a stochastic model. The drugs in question are two isomers that are applied to the human eye via a liquid eye drop. Techniques applied to the data in this paper can be applied to other two-drug combination studies.
We derive the mean and the variance terms of the drug combination "effects" in closed form using Ito's method of stochastic differential equations. The model fit of the data to the individual subject is examined by both statistical and graphical methods. Two estimation methods in SAS, PROC NUN and PROC NLMIXED, are used to estimate model parameters. We perform simulation and power studies using R software to show the strengths of the proposed approach in estimating the model parameters.
From this research, we find that the combination of drugs under study is synergistic in nature. We also confirm that the proposed stochastic model is appropriate.
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Saldamli, Levon. „PDEModelica : a high-level language for modeling with partial differential equations /“. Doctoral thesis, Linköping : Department of Computer and Information Science, Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7281.
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Govorun, Maria. „Pension and health insurance, phase-type modeling“. Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209447.
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Depuis longtemps les modèles de type phase sont utilisés dans plusieurs domaines scientifiques pour décrire des systèmes qui peuvent être caractérisés par différents états. Les modèles sont bien connus en théorie des files d’attentes, en économie et en assurance.La thèse est focalisée sur différentes applications des modèles de type phase en assurance et montre leurs avantages. En particulier, le modèle de Lin et Liu en 2007 est intéressant, parce qu’il décrit le processus de vieillissement de l’organisme humain. La durée de vie d’un individu suit une loi de type phase et les états de ce modèle représentent des états de santé. Le fait que le modèle prévoit la connexion entre les états de santé et l’âge de l’individu le rend très utile en assurance.
Les résultats principaux de la thèse sont des nouveaux modèles et méthodes en assurance pension et en assurance santé qui utilisent l’hypothèse de la loi de type phase pour décrire la durée de vie d’un individu.
En assurance pension le but d’estimer la profitabilité d’un fonds de pension. Pour cette raison, on construit un modèle « profit-test » qui demande la modélisation de plusieurs caractéristiques. On décrit l’évolution des participants du fonds en adaptant le modèle du vieillissement aux causes multiples de sortie. L’estimation des profits futurs exige qu’on détermine les valeurs des cotisations pour chaque état de santé, ainsi que l’ancienneté et l’état de santé initial pour chaque participant. Cela nous permet d’obtenir la distribution de profits futurs et de développer des méthodes pour estimer les risques de longevité et de changements de marché. De plus, on suppose que la diminution des taux de mortalité pour les pensionnés influence les profits futurs plus que pour les participants actifs. C’est pourquoi, pour évaluer l’impact de changement de santé sur la profitabilité, on modélise séparément les profits venant des pensionnés.
En assurance santé, on utilise le modèle de type phase pour calculer la distribution de la valeur actualisée des coûts futurs de santé. On développe des algorithmes récursifs qui permettent d’évaluer la distribution au cours d’une période courte, en utilisant des modèles fluides en temps continu, et pendant toute la durée de vie de l’individu, en construisant des modèles en temps discret. Les trois modèles en temps discret correspondent à des hypothèses différentes qu’on fait pour les coûts: dans le premier modèle on suppose que les coûts de santé sont indépendants et identiquement distribués et ne dépendent pas du vieillissement de l’individu; dans les deux autres modèles on suppose que les coûts dépendent de son état de santé.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Rao, Rashmi Jayathirtha. „Modeling learning behaviour and cognitive bias from web logs“. The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492560600002105.
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Buckman, Kevin D. „A Mathematical Model of Biofilm Growth and Decay with Applications of Antimicrobial“. University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1333910050.
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SURANA, RAJESH R. „HIGH STRAIN FUNCTIONALLY GRADED BARIUM TITANATE AND ITS MATHEMATICAL CHARACTERIZATION“. University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1096650232.
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Erson, E. Zeynep. „Development, Integration and Simulation of Multiscale Mathematical Models of Physiological Processes: A Software Engineering Perspective“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1289789036.
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Faborode, Jumoke O. „Predictive modeling of sulfide removal in tray aerators“. Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4633.
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Hydrogen sulfide is commonly found in many Florida potable groundwater supplies. Removing sulfur species, particularly hydrogen sulfide is important because if left untreated, sulfide can impact finished water quality, corrosivity, create undesirable taste and odor, and oxidize to form visible turbidity and color. This document presents the results of a study designed to investigate the removal efficiencies of a variety of tray aerators in Central Florida in order to develop a predictive mathematical model that could be used to determine tray effectiveness for sulfide removal. A literature review was performed that indicated there was limited information regarding the removal of hydrogen sulfide using conventional tray aerators, and no information regarding the removal of total sulfide from tray aerators. There was significantly more information available in the literature regarding the usefulness of sulfide removal technologies from water supplies. Consequently, the lack of literature regarding sulfide removal using tray aerators suggested that there was a need for additional research focused on sulfide removal from water flowing thru tray aerators. Several water purveyors that relied on tray aerators as a part of their water treatment operations were contacted and requested to participate in the study; three water purveyors agreed to allow the University of Central Florida (UCF) to enter their secured sites to collect samples and conduct this study. The three facilities included the UCF‘s water treatment plant located in Orlando and situated in eastern Orange County, the City of Lake Hamilton‘s water treatment plant located in west-central Polk County, and the Sarasota-Verna water treatment plant located in western Sarasota County. An experimental plan was developed and field sampling protocols were implemented to evaluate sulfide removal in commonly used tray aerators at the three drinking water treatment facilities. Total sulfide concentrations passing through the trays were determined in the field at each site using a standard iodometric analytical technique. In addition, other water quality parameters collected included dissolved oxygen, pH, temperature, conductivity, turbidity, alkalinity, hardness, total dissolved solids and total suspended solids; these samples were collected and analyzed either in the field or at the UCF laboratory. A first-order empirical model was developed that predicted sulfide removal in tray aerators. The model‘s constant was evaluated with respect to the water‘s proton concentration [H+], the tray aerator‘s surface area, and hydraulic flow rate thru the trays. The selected model took the form of C[sub]=C[sub]0 (10[super]-kn) where C[sub]n is the sulfide remaining after aeration in mg/L, C[sub]0 is the sulfide entering the distribution tray in mg/L, n is the number of tray stages in the aerator, and k=(0.00248)(H+)[super]-0.397(Area0[super]0.584(Flow)[super]-1.17. From the empirical model, it was shown that sulfide removal was negatively impacted as the proton concentration (H+) decreased, and flow increased. Conversely, it was observed that increased sulfide removal occurred as the available tray aerator surface area increased. The combined parameters of proton concentration, flow rate, and area were statistically evaluated and used to develop an empirical constant that could be used in a first order model to predict sulfide removal in tray aerators. Using a site-specific derived experimental (empirical) constant, a water purveyor could use the developed model from this work to accurately predict sulfide removal in a tray aerator by simply measuring the total sulfide content in any raw groundwater supply and then providing the desired number of tray stages available for treatment.ID: 029050889; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2010.; Includes bibliographical references (p. 83-87).
M.S.
Masters
Department of Civil, Environmental, and Construction Engineering
Engineering and Computer Science
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Simoni, Giulia. „Modeling Startegies for Computational Systems Biology“. Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/254361.
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Mathematical models and their associated computer simulations are nowadays widely used in several research fields, such as natural sciences, engineering, as well as social sciences. In the context of systems biology, they provide a rigorous way to investigate how complex regulatory pathways are connected and how the disruption of these processes may contribute to the develop- ment of a disease, ultimately investigating the suitability of specific molecules as novel therapeutic targets. In the last decade, the launching of the precision medicine initiative has motivated the necessity to define innovative computational techniques that could be used for customizing therapies. In this context, the combination of mathematical models and computer strategies is an essential tool for biologists, which can analyze complex system pathways, as well as for the pharmaceutical industry, which is involved in promoting programs for drug discovery.
In this dissertation, we explore different modeling techniques that are used for the simulation and the analysis of complex biological systems. We analyze the state of the art for simulation algorithms both in the stochastic and in the deterministic frameworks. The same dichotomy has been studied in the context of sensitivity analysis, identifying the main pros and cons of the two approaches. Moreover, we studied the quantitative system pharmacology (QSP) modeling approach that elucidates the mechanism of action of a drug on the biological processes underlying a disease. Specifically, we present the definition, calibration and validation of a QSP model describing Gaucher disease type 1 (GD1), one of the most common lysosome storage rare disorders. All of these techniques are finally combined to define a novel computational pipeline for patient stratification. Our approach uses modeling techniques, such as model simulations, sensitivity analysis and QSP modeling, in combination with experimental data to identify the key mechanisms responsible for the stratification. The pipeline has been applied to three test cases in different biological contexts: a whole-body model of dyslipidemia, the QSP model of GD1 and a QSP model of cardiac electrophysiology. In these test cases, the pipeline proved to be accurate and robust, allowing the interpretation of the mechanistic differences underlying the phenotype classification.
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Simoni, Giulia. „Modeling Startegies for Computational Systems Biology“. Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/254361.
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Mathematical models and their associated computer simulations are nowadays widely used in several research fields, such as natural sciences, engineering, as well as social sciences. In the context of systems biology, they provide a rigorous way to investigate how complex regulatory pathways are connected and how the disruption of these processes may contribute to the develop- ment of a disease, ultimately investigating the suitability of specific molecules as novel therapeutic targets. In the last decade, the launching of the precision medicine initiative has motivated the necessity to define innovative computational techniques that could be used for customizing therapies. In this context, the combination of mathematical models and computer strategies is an essential tool for biologists, which can analyze complex system pathways, as well as for the pharmaceutical industry, which is involved in promoting programs for drug discovery.
In this dissertation, we explore different modeling techniques that are used for the simulation and the analysis of complex biological systems. We analyze the state of the art for simulation algorithms both in the stochastic and in the deterministic frameworks. The same dichotomy has been studied in the context of sensitivity analysis, identifying the main pros and cons of the two approaches. Moreover, we studied the quantitative system pharmacology (QSP) modeling approach that elucidates the mechanism of action of a drug on the biological processes underlying a disease. Specifically, we present the definition, calibration and validation of a QSP model describing Gaucher disease type 1 (GD1), one of the most common lysosome storage rare disorders. All of these techniques are finally combined to define a novel computational pipeline for patient stratification. Our approach uses modeling techniques, such as model simulations, sensitivity analysis and QSP modeling, in combination with experimental data to identify the key mechanisms responsible for the stratification. The pipeline has been applied to three test cases in different biological contexts: a whole-body model of dyslipidemia, the QSP model of GD1 and a QSP model of cardiac electrophysiology. In these test cases, the pipeline proved to be accurate and robust, allowing the interpretation of the mechanistic differences underlying the phenotype classification.
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Ely, David P. „Preparing Teachers to Integrate Computer Programming Into Mathematical Problem Solving“. The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1478266333504353.
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Altinoklar, Hatice. „A Mathematical Modeling Study On The Feasibility Of Disposing Partially Treated Domestic Wastewater Using Soil Pile Systems“. Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607944/index.pdf.
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The soil pile system (SPS) is a wastewater infiltration system used for secondary and tertiary treatment of wastewater. The purpose of this study is to perform a feasibility study to assess the applicability of SPS for treatment and safe disposal of domestic wastewaters, using a simplistic steady-state flow analytical modeling and a numerical transient unsaturated flow and transport modeling approaches. It is also aimed to develop guidelines for the design and operation of field scale SPS using the results of modeling studies.
The analytical modeling approach (AMA) was used to assess total coliform and chlorine attenuation efficiency in a SPS with clay loam soil. Analytical modeling results showed that SPS can treat wastewater in terms of total coliform and chlorine. Thus, in the light of findings of analytical modeling study, a pilot scale field study was conducted for the identifying the design and operational characteristics of a field scale system. Numerical modeling approach was used to evaluate the impact on contaminant removal of transient nature of wastewater infiltration and redistribution through clay loam soil pile. The results of numerical and analytical models were compared to assess the effect of flow regime on contaminant removal efficiencies. Results show that there is no significant difference between removal efficiencies achieved by numerical and analytical models. Whereupon, analytical model was used to assess behavior of SPS with different soil types, namely silt loam, loam, and sandy loam soils.
Model results indicated that SPS can be effective reducing chlorine and total coliform concentrations of wastewater below discharge standards. Results also indicated that SPS is highly sensitive to soil thickness, infiltration rate, soil bulk density and most importantly decay rate coefficients and the performance of SPS is dependent on the design, construction, operation characteristics and soil-environmental conditions of the system.
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Khodaverdi, Afaghi Mahtab. „Application of artificial neural network modeling in thermal process calculations of canned foods“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0033/MQ64381.pdf.
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Xi, Jiahe. „Cardiac mechanical model personalisation and its clinical applications“. Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:0db4cf52-4f64-4ee0-8933-3fb49d64aee6.
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An increasingly important research area within the field of cardiac modelling is the development and study of methods of model-based parameter estimation from clinical measurements of cardiac function. This provides a powerful approach for the quantification of cardiac function, with the potential to ultimately lead to the improved stratification and treatment of individuals with pathological myocardial mechanics. In particular, the diastolic function (i.e., blood filling) of left ventricle (LV) is affected by its capacity for relaxation, or the decay in residual active tension (AT) whose inhibition limits the relaxation of the LV chamber, which in turn affects its compliance (or its reciprocal, stiffness). The clinical determination of these two factors, corresponding to the diastolic residual AT and passive constitutive parameters (stiffness) in the cardiac mechanical model, is thus essential for assessing LV diastolic function. However these parameters are difficult to be assessed in vivo, and the traditional criterion to diagnose diastolic dysfunction is subject to many limitations and controversies. In this context, the objective of this study is to develop model-based applicable methodologies to estimate in vivo, from 4D imaging measurements and LV cavity pressure recordings, these clinically relevant parameters (passive stiffness and active diastolic residual tension) in computational cardiac mechanical models, which enable the quantification of key clinical indices characterising cardiac diastolic dysfunction. Firstly, a sequential data assimilation framework has been developed, covering various types of existing Kalman filters, outlined in chapter 3. Based on these developments, chapter 4 demonstrates that the novel reduced-order unscented Kalman filter can accurately retrieve the homogeneous and regionally varying constitutive parameters from the synthetic noisy motion measurements. This work has been published in Xi et al. 2011a. Secondly, this thesis has investigated the development of methods that can be applied to clinical practise, which has, in turn, introduced additional difficulties and opportunities. This thesis has presented the first study, to our best knowledge, in literature estimating human constitutive parameters using clinical data, and demonstrated, for the first time, that while an end-diastolic MR measurement does not constrain the mechanical parameters uniquely, it does provide a potentially robust indicator of myocardial stiffness. This work has been published in Xi et al. 2011b. However, an unresolved issue in patients with diastolic dysfunction is that the estimation of myocardial stiffness cannot be decoupled from diastolic residual AT because of the impaired ventricular relaxation during diastole. To further address this problem, chapter 6 presents the first study to estimate diastolic parameters of the left ventricle (LV) from cine and tagged MRI measurements and LV cavity pressure recordings, separating the passive myocardial constitutive properties and diastolic residual AT. We apply this framework to three clinical cases, and the results show that the estimated constitutive parameters and residual active tension appear to be a promising candidate to delineate healthy and pathological cases. This work has been published in Xi et al. 2012a. Nevertheless, the need to invasively acquire LV pressure measurement limits the wide application of this approach. Chapter 7 addresses this issue by analysing the feasibility of using two kinds of non-invasively available pressure measurements for the purpose of inverse parameter estimation. The work has been submitted for publication in Xi et al. 2012b.
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Kamonpatana, Pitiya. „MATHEMATICAL MODELING AND MICROBIOLOGICAL VERIFICATION OF OHMIC HEATING OF SOLID-LIQUID MIXURES IN CONTINUOUS FLOW OHMIC HEATER SYSTEMS“. The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343490087.
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Carman, Benjamin Andrew. „Repairing Redistricting: Using an Integer Linear Programming Model to Optimize Fairness in Congressional Districts“. Ohio University Honors Tutorial College / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1619177994406176.
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Meesumrarn, Thiraphat. „Simulation of Dengue Outbreak in Thailand“. Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248484/.
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The dengue virus has become widespread worldwide in recent decades. It has no specific treatment and affects more than 40% of the entire population in the world. In Thailand, dengue has been a health concern for more than half a century. The highest number of cases in one year was 174,285 in 1987, leading to 1,007 deaths. In the present day, dengue is distributed throughout the entire country. Therefore, dengue has become a major challenge for public health in terms of both prevention and control of outbreaks. Different methodologies and ways of dealing with dengue outbreaks have been put forward by researchers. Computational models and simulations play an important role, as they have the ability to help researchers and officers in public health gain a greater understanding of the virus's epidemic activities.
In this context, this dissertation presents a new framework, Modified Agent-Based Modeling (mABM), a hybrid platform between a mathematical model and a computational model, to simulate a dengue outbreak in human and mosquito populations. This framework improves on the realism of former models by utilizing the reported data from several Thai government organizations, such as the Thai Ministry of Public Health (MoPH), the National Statistical Office, and others. Additionally, its implementation takes into account the geography of Thailand, as well as synthetic mosquito and synthetic human populations. mABM can be used to represent human behavior in a large population across variant distances by specifying demographic factors and assigning mobility patterns for weekdays, weekends, and holidays for the synthetic human population. The mosquito dynamic population model (MDP), which is a component of the mABM framework, is used for representing the synthetic mosquito population dynamic and their ecology by integrating the regional model to capture the effect of dengue outbreak. The two synthetic populations can be linked to each other for the purpose of presenting their interactions, and the Local Stochastic Contact Model for Dengue (LSCM-DEN) is utilized. For validation, the number of cases from the experiment is compared to reported cases from the Thailand Vector Borne Disease Bureau for the selected years.
This framework facilitates model configuration for sensitivity analysis by changing parameters, such as travel routes and seasonal temperatures. The effects of these parameters were studied and analyzed for an improved understanding of dengue outbreak dynamics.
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Wise, Andre. „A spatial approach to edge effect modelling for plantation forestry“. Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85876.
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Thesis (MScFor)--Stellenbosch University, 2013.ENGLISH ABSTRACT: One of the major objectives in plantation forestry is to achieve a high level of homogeneity of distribution and dimension of trees within the stand. Precise planting geometries, intensive silviculture and genetic selection are used to achieve this homogeneity. However, a natural variability is still introduced by micro-‐site conditions and disturbances. A substantial source of variation is caused by edge effects of neighbouring stands or other land use forms. The edge effect causes trees at the stand edge to develop differently from trees in the interior of the stand. The overarching objective of this study is to simulate the edge effect based on average stand interior variables as typically received from an enumeration and spatial information on the current and historic stand neighbourhood. With re-‐introducing this natural variance as well as its spatial pattern, we expect to derive improved planning information. A major aim is thus separating the effect of the edge interaction from the other factors contributing to stand variance and quantifying the result in terms of stand output. A methodology is introduced for quantifying interaction at stand edges between a given stand and its neighbouring stands over its lifetime. Transferring the edge interaction value from the edges to all the trees within the stand is then done by applying inverse distance weighting interpolation from the edges to the tree position within the stand. Once an edge interaction value has been calculated for each point, the extent of the edge effect is quantified. The spatial extent of the edge effect is derived empirically from an existing fully spatially mapped stand by means of breakpoint regression. The expected variance as a result of edge influence is then quantified by producing a set of models, which can reproduce the effect of the edge interaction on tree height, diameter and volume. The edge effect is treated as a dynamic interaction for which the temporal aspect needs to be considered, because the current spatial structure of a stand is influenced by its current neighbourhood, but also by the historic development of the neighbourhood in relation to the stand in question. Each stand therefore undergoes an edge effect which is completely unique to that stand, within a given time period. For this reason the presented methodology is a spatial-‐temporal one, aimed at providing a way in which growth and yield forest modelling can be augmented by the inclusion of the edge effect in a practical way. To explicitly quantify edge effects, the natural variance had to be separated into a component explained by edge effect and a second component introduced by other factors such as micro site conditions and disturbance. The second component is treated as an unexplained residual variance. In order to provide a realistic simulation of a stand output at a finer, tree level, this second stand variance needs nonetheless to be quantified. The variance attributable to factors other than the edge effect is mimicked by generating a random number by means of a parameterised stochastic process based on the variance of the inner stand region, which is beyond the reach of the edge effect. In this way, a realistic spatial pattern of a plantation forest stand, taking into account the edge effect and combining it with the natural stand variance is achieved. This study, within the field of plantation forest management, aspires to land use optimization both in terms of productive capacity estimation and for the provision of information for effective land use management planning. It makes use of open source software resources namely the R framework and QGIS and explores aerial stereophotogrammetry as an option for data collection.
AFRIKAANSE OPSOMMING: Een van die hoofdoelwitte in plantasie bosbou praktyk is hoё vlakke van homogeniteit met betrekking tot die verspreiding en die dimensies van die bome in die plantasie opstand. Simetriese aanplantings, intensiewe bosboupraktyk en genetiese seleksie word gebruik om hierdie homogeniteit te verkry. Natuurlike verskille word egter nog steeds gevind as gevolg van groeiplek mikro toestande en ander versteurings in die opstand. Een van die hoofbronne van hierdie variasie is die randeffekte van buurplantasies en ander gebruike van grond. Hierdie randeffekte veroorsaak dat bome aan die rand van die opstand anders ontwikkel as die bome binne in die opstand. Die oorhoofse doelwit met hierdie navorsing is om die randeffekte te simuleer. Hierdie randeffekte is gegrond op die gemiddelde binneopstand boom veranderlikes soos afgelei uit die opmeting en uit ruimtelike inligting oor die huidige en geskiedkundige toestande in die omgewing. As hierdie natuurlike variasies asook die ruimtelike patrone weer in berekening gebring word, verwag ons om beter beplanningsinligting te bekom. ’n Belangrike doelwit tydens hierdie navorsing is dus om die effek van die rand-‐interaksie te skei van die effek van ander faktore wat bydra tot variasies binne-‐in die opstand en om die resultaat in terme van plantasie produksie te kwantifiseer. ’n Metodiek word voorgestel vir die kwantifisering van die interaksie op die rande tussen die opstand en die buuropstande tydens die leeftyd van die opstand. Die oorplasing van die rand interaksie waarde van die rand af na al die bome in die plantasie word dan gedoen deur om geweegde inverse afstand interpolasie vanaf die rand tot by die ligging van die boom, toe te pas. As die rand interaksie waarde vir elke punt bereken is, kan die omvang van die randeffek gekwantifiseer word. Die ruimtelike omvang van die rand effek is, met die gebruik van breekpunt regressie, empiries afgelei van ’n bestaande ten volle karteerde plantasie. Die verwagte variasie as gevolg van die randeffek word dan met die gebruik van ’n stel modelle gekwantifiseer, wat dan die effek van die rand interaksie op boomhoogte, deursnit en volume kan weergee. Die randeffek word as ’n dinamiese interaksie beskou waarvan die tydsaspek in ag geneem moet word, want die huidige ruimtelike struktuur van die plantasie word beïnvloed deur die huidige omgewing asook deur die historiese ontwikkeling van die omgewing met betrekking tot die opstand onder bespreking. Elke opstand ondergaan ’n randeffek wat uniek is aan daardie plantasie op die gegewe tydstip. Die doelwit is om ’n wyse te vind waarvolgens groei-‐en-‐opbrengs plantasie modellering deur die insluiting van randeffek op ’n praktiese wyse, aangevul kan word. Om hierdie rede is die aanbevole metodiek ruimtelik-‐tydelik en gerig daarop om ’n wyse te vind waarvolgens groei-‐en-‐opbrengs modellering deur die insluiting van die randeffek, op ’n praktiese wyse aangevul kan word. Om randeffek eksplisiet te kwantifiseer, moes die natuurlike afwyking gedeel word in die komponent wat die gevolg is van die randeffek, en ’n tweede komponent wat die gevolg is van ander faktore soos mikroligging toestande en versteurings. Die tweede komponent word behandel as ’n onverklaarde oorblywende afwyking. Hierdie tweede plantasie afwyking moet nogtans kwantifiseer word om sodoende ’n realistiese simulasie van plantasie opbrengs op ’n fyner boom vlak te verkry. Die afwyking wat toegeskryf kan word aan faktore buiten die randeffek, word nageboots deur om ’n lukrake nommer (wat gebaseer word op die afwyking van die binne-‐plantasie gebied wat buite die strekwydte van die randeffek is) deur middel van ‘n geparameteriseerde stogastiese proses te genereer. Sodoende word ’n realistiese ruimtelike patroon van ’n plantasie opstand verkry, wat die randeffek in ag neem en dit kombineer met die natuurlike plantasie afwyking.
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Qi, Rui. „Optimization and optimal control of plant growth : application of GreenLab model for decision aid in agriculture“. Phd thesis, Châtenay-Malabry, Ecole centrale de Paris, 2010. http://tel.archives-ouvertes.fr/tel-00494918.
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The objective of the thesis is to improve plant yield through optimization and optimal control based on the GreenLab plant growth model. Therefore, the thesis proposed a methodology for investigation of plant yield improvement，whose characteristics are that (1) investigations are all based on the functional-structural plant growth model GreenLab and (2) heuristic optimization algorithm and optimal control techniques are applied to the plant growth model in order to improve plant yield. By applying optimization techniques on different species of plants (crops or trees) and for different kinds of optimization problems, common characteristics that a plant with high yield should possess were obtained. The optimal results in the thesis revealed the source-sink dynamics during the plant growth. The optimization results can be considered as references to guide breeding for ideotype and to improve cultivation modes. The optimization application of GreenLab could thus be possibly used to the agricultural decision support system.To achieve the aims of the thesis, the thesis investigated the effects of endogenous factors and exogenous environmental factors of plant growth on plant yield separately. First, given environmental conditions, the thesis investigated endogenous factors, and then the thesis did optimal control on exogenous environmental factors given plant genotype. Therefore, the problems investigated in the thesis consist of general optimization problems and optimal control problems.The main contributions of the thesis include following issues: According to the species of plants, single optimization problems, multi-objective optimization problems and optimization problems with constraints with respect to plant endogenous factors were formulated and investigated, in order to find the ideotype of plants with high plant yield. A population based algorithm is more suitable for the optimization problems in this thesis. Due to its better performance compared with other heuristic optimization algorithms, all optimization problems were solved by a population-based, heuristic optimization algorithm, namely Particle Swarm Optimization (PSO). Optimal control on the pruning strategy was formulated and investigated in the thesis. As GreenLab can be considered as discrete dynamic system and the objective function of the optimal control problem is analytical, the gradient based method, which is based on the variational approach and Lagrange theory, was used to solve the optimal control problem. Moreover, the optimal solutions were compared with the ones found by PSO, in order to validate the PSO method. The insect population dynamics was modeled mathematically, which was compatible with the plant model GreenLab in terms of spatial and temporal scales, to study the effect of biotic factors on plant growth. The interaction among plants, pests and auxiliaries was implemented, and the ecosystem model, which involves the three tri-trophic components, was thus developed in the thesis. The tri-trophic ecosystem model can simulate the insect population dynamics and the plant growth with consideration of the interaction of insects. Moreover, the tri-trophic ecosystem model considered the partition of individuals in the insect population among plant organs, which is not taken into account in the previous works. A global sensitivity analysis method Morris method was used to analyze the most important parameters and the least influential parameters to model outputs of interest. Through optimization on pest management techniques, the optimal strategies of the application of the pest management techniques were obtained. Estimation of GreenLab parameters with about 400 sets of observation data of 44 tomato genotypes was done in the thesis, by using a generalized non-linear least square algorithm. Taking the estimated parameter values as parameter space, the GreenLab model parameters were optimized, in order to maximize the fruit yield. Through the analysis of the correlation of estimated and optimal parameters with the fruit yield by statistical analysis methods, the most important parameters that result in the difference of fruit yield were found. According to the correlation and optimization results, the phenotypic differences among genotypes were explained from the physiological point of view.
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Boyaval, Sébastien. „Mathematical modelling and numerical simulation in materials science“. Phd thesis, Université Paris-Est, 2009. http://tel.archives-ouvertes.fr/tel-00499254.
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In a first part, we study numerical schemes using the finite-element method to discretize the Oldroyd-B system of equations, modelling a viscoelastic fluid under no flow boundary condition in a 2- or 3- dimensional bounded domain. The goal is to get schemes which are stable in the sense that they dissipate a free-energy, mimicking that way thermodynamical properties of dissipation similar to those actually identified for smooth solutions of the continuous model. This study adds to numerous previous ones about the instabilities observed in the numerical simulations of viscoelastic fluids (in particular those known as High Weissenberg Number Problems). To our knowledge, this is the first study that rigorously considers the numerical stability in the sense of an energy dissipation for Galerkin discretizations. In a second part, we adapt and use ideas of a numerical method initially developped in the works of Y. Maday, A.T. Patera et al., the reduced-basis method, in order to efficiently simulate some multiscale models. The principle is to numerically approximate each element of a parametrized family of complicate objects in a Hilbert space through the closest linear combination within the best linear subspace spanned by a few elementswell chosen inside the same parametrized family. We apply this principle to numerical problems linked : to the numerical homogenization of second-order elliptic equations, with two-scale oscillating diffusion coefficients, then ; to the propagation of uncertainty (computations of the mean and the variance) in an elliptic problem with stochastic coefficients (a bounded stochastic field in a boundary condition of third type), last ; to the Monte-Carlo computation of the expectations of numerous parametrized random variables, in particular functionals of parametrized Itô stochastic processes close to what is encountered in micro-macro models of polymeric fluids, with a control variate to reduce its variance. In each application, the goal of the reduced-basis approach is to speed up the computations without any loss of precision
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Strandh, Jenny. „A study of solid and liquid inclusion separation at the steel-slag interface“. Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-307.
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Nakrani, Sunil. „Biomimetic and autonomic server ensemble orchestration“. Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534214.
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This thesis addresses orchestration of servers amongst multiple co-hosted internet services such as e-Banking, e-Auction and e-Retail in hosting centres. The hosting paradigm entails levying fees for hosting third party internet services on servers at guaranteed levels of service performance. The orchestration of server ensemble in hosting centres is considered in the context of maximising the hosting centre's revenue over a lengthy time horizon. The inspiration for the server orchestration approach proposed in this thesis is drawn from nature and generally classed as swarm intelligence, specifically, sophisticated collective behaviour of social insects borne out of primitive interactions amongst members of the group to solve problems beyond the capability of individual members. Consequently, the approach is self-organising, adaptive and robust. A new scheme for server ensemble orchestration is introduced in this thesis. This scheme exploits the many similarities between server orchestration in an internet hosting centre and forager allocation in a honeybee (Apis mellifera) colony. The scheme mimics the way a honeybee colony distributes foragers amongst flower patches to maximise nectar influx, to orchestrate servers amongst hosted internet services to maximise revenue. The scheme is extended by further exploiting inherent feedback loops within the colony to introduce self-tuning and energy-aware server ensemble orchestration. In order to evaluate the new server ensemble orchestration scheme, a collection of server ensemble orchestration methods is developed, including a classical technique that relies on past history to make time varying orchestration decisions and two theoretical techniques that omnisciently make optimal time varying orchestration decisions or an optimal static orchestration decision based on complete knowledge of the future. The efficacy of the new biomimetic scheme is assessed in terms of adaptiveness and versatility. The performance study uses representative classes of internet traffic stream behaviour, service user's behaviour, demand intensity, multiple services co-hosting as well as differentiated hosting fee schedule. The biomimetic orchestration scheme is compared with the classical and the theoretical optimal orchestration techniques in terms of revenue stream. This study reveals that the new server ensemble orchestration approach is adaptive in a widely varying external internet environments. The study also highlights the versatility of the biomimetic approach over the classical technique. The self-tuning scheme improves on the original performance. The energy-aware scheme is able to conserve significant energy with minimal revenue performance degradation. The simulation results also indicate that the new scheme is competitive or better than classical and static methods.
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Mercat, Christian. „Analyse Complexe Discrète“. Habilitation à diriger des recherches, Université Montpellier II - Sciences et Techniques du Languedoc, 2009. http://tel.archives-ouvertes.fr/tel-00439782.
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Ma contribution principale porte sur la géométrie différentielle discrète, spécialement la géométrie conforme discrète. Les champs d'application principaux que j'étudie sont l'imagerie par ordinateur et les systèmes intégrables, tant les systèmes intégrables discrets que les systèmes statistiques intégrables. Ma thèse sur le modèle d'Ising a identifié la criticité dans le modèle de taille fini comme un point où le fermion, une observable particulière, devient holomorphe pour une structure conforme discrète sous-jacente. À l'université de Melbourne, je me suis intéressé avec Paul Pearce aux modèles ADE qui sont une généralisation du modèle d'Ising, dans le but (inachevé mais en bonne voie) d'y identifier un analogue discret de l'algèbre des opérateurs vertex (les conditions de bord conformes et intégrables) et des blocs conformes, en particulier dans l'espoir de comprendre la criticité comme une compatibilité à l'holomorphie discrète. À l'université technique de Berlin, avec Alexander Bobenko et son équipe, j'ai compris la nature intégrable du modèle associé à l'holomorphie discrète (linéaire et quadratique) et utilisé les outils très puissants de cette théorie (isomonodromie, transformations de Darboux-Bäcklund, finite-gap) pour mettre à jour la position centrale de l'analyse complexe discrète dans la hiérarchie des systèmes intégrables discrets. À Montpellier, dans l'équipe Arith dirigée par Valérie Berthé, j'ai appliqué cette théorie dans le cadre de la géométrie différentielle discrète, particulièrement dans le cadre voxellique de la géométrie digitale.
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De, Vega Rodrigo Miguel. „Modeling future all-optical networks without buffering capabilities“. Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210455.
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In this thesis we provide a model for a bufferless optical burst switching (OBS) and an optical packet switching (OPS) network. The thesis is divided in three parts. In the first part we introduce the basic functionality and structure of OBS and OPS networks. We identify the blocking probability as the main performance parameter of interest.
In the second part we study the statistical properties of the traffic that will likely run through these networks. We use for this purpose a set of traffic traces obtained from the Universidad Politécnica de Catalunya. Our conclusion is that traffic entering the optical domain in future OBS/OPS networks will be long-range dependent (LRD).
In the third part we present the model for bufferless OBS/OPS networks. This model takes into account the results from the second part of the thesis concerning the LRD nature of traffic. It also takes into account specific issues concerning the functionality of a typical bufferless packet-switching network. The resulting model presents scalability problems, so we propose an approximative method to compute the blocking probability from it. We empirically evaluate the accuracy of this method, as well as its scalability.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished