Dissertations / Theses on the topic 'Hybrid model'
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Weingarten, Leopold. "Physical Hybrid Model : Measurement - Experiment - Simulation." Thesis, Uppsala universitet, Fasta tillståndets fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-176412.
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A method has been developed, Physical Hybrid Model, to investigate the physical large scale electrical effects of a Battery Energy Storage System (BESS) on a distribution grid by scaling the response from a small size Research Development and Demonstration (RD&D) platform. In order to realize the model the control system of an existing RD&D platform was refurbished and stability of components ensured. The Physical Hybrid Model proceeds as follows: Data from a distribution grid are collected. A BESS cycle curve is produced based on analyzed measurements. Required BESS power and capacity in investigated grid is scaled down by factor k to that of the physical test installation of the RD&D platform. The scaled BESS cycle is sent as input to control of the battery cycling of the RD&D platform. The response from the RD&D platform is scaled – up, and used in simulation of the distribution grid to find the impact of a BESS. The model was successfully implemented on a regional distribution grid in southern Sweden.
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Wall, Wolfe. "A hybrid model of proton scattering /." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59833.
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A model is presented to describe pp and pp scattering in the c.m.s. energy range from 5 Gev to 1.8 Tev. Although some attention is paid to properties of the differential cross section, the primary focus is on parametrizing the forward amplitude in a manner consistent with experimental measurements of the total cross section, the rho parameter, and the forward slope. The model is a hybrid, employing Regge Theory for energy dependence, dipole form factors for momentum transfer distributions, and impact parameter eikonalization is used to unitarize the amplitude. The model is first motivated, then the results of fits to data are presented, and finally it is compared to a model based on hard scattering of partons.
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Monaghan, Anne. "Beyond transformative mediation : a hybrid model." Thesis, Ulster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581970.
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This research tests whether a third model or approach to mediation is possible, if not already in existence - a hybrid model. Two of the main approaches to mediation are explored - transformative and problem-solving - and the hypothesis that a process exists or could be developed that combines elements of both is tested. Transformative mediation was outlined in The Promise of Mediation by Bush and Folger in 1994 and for the purposes of this study John Wear Burton's work is examined as an example of problem-solving mediation. A number of case-studies around parading disputes in Northern Ireland are looked at in more detail as evidence of transformative and problem-solving practice; to test whether hybridity exists and/or whether a model combining elements of both transformative and problem-solving practice is feasible. The major division in mediation theory and practice at present is around where the focus of the process and the mediator's attention should lie. Transformative mediators argue it should focus on the relationship while problem-solving practitioners argue that sometimes those in conflict are not ready, willing or able to aim their attention there. Where this is the case, they argue the mediator should bank any progress or agreements, particularly where there is violence. Interviews with subjects included practitioners operating out of one or other main models of mediation and some who operated out of neither and had no formal training, having leaned their craft on the ground. This research makes a contribution to knowledge in the field as hybrid processes were either found to exist, as in the case of the Newry Good Relations Forum; or it was acknowledged that processes that focused on one element - either the relational or problem-solving - to the detriment of the other element remained contested, for example, the Drumcree dispute.
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Mei, Zhu. "Structural hybrid simulation with model updating of material constitutive model." Doctoral thesis, Università degli studi di Trento, 2018. https://hdl.handle.net/11572/368550.
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When hybrid simulation (HS) with substructures is employed for assessing the seismic behavior of a large complex structure, it is unrealistic to test all the components that may exhibit strong nonlinearity. Hence, the accuracy of the numerical substructure (NS) faces an increased challenge. To this end, this paper will emphasize on improving the accuracy of the NS in hybrid simulation based on the model updating approach. Most hybrid simulations with model updating (UHS) focus on updating the parameters of the component constitutive model (story shear model) leading to large modeling errors and the unknown detail responses. Moreover, the most extensively used component constitutive models, such as the Bouc-Wen model, are the models in a narrow sense because they are different for various RC members when the size of the component, boundary conditions, axial compression ratio, and the volumetric stirrup ratio are different from one component to the other. Thus, numerous parameters are needed to describe the displacement-force relations of different components, which leads to the huge computational burden. With this respect, this paper proposes a novel hybrid simulation approach based on identifying and updating the parameters of the material constitutive model. The main work and results are concluded as follows,
1. The unified constitutive model of unconfined and confined concrete is derived from the existing uniaxial concrete constitutive models by introducing the volumetric stirrup ratio.
2. To solve the problem that the relation of the measurements (force of the specimen of a RC member) and the identified parameters (concrete constitutive parameters) are difficult to analytical expressed, an OpenSees embedded unscented Kalman filter is proposed for parameter identification. To this end, several parts of the OpenSees source codes are developed and modified.
3. The proposed identification method and hybrid simulation based on updating the concrete constitutive parameters are respectively validated through a monotonic loading test on a RC column and a UHS on a RC frame. The results show that the convergence values of each parameter under various experimental cases are close to each other with a small variance, which indicates that the proposed identification method is robust and reliable. Comparing to the standard HS, the accuracy of the NS, hence the UHS, is significantly improved.
4. Apply the proposed UHS to a RC continuous rigid bridge with tall thin-walled piers. It concludes that the performance of the identification method is still quite good. Contrasting to the simpler structure, the improved accuracy of a large complex structure is even greater. Moreover, the accuracy of the NS can be greatly increased even though the model error is increased. By tuning the initial values of constitutive parameters, the negative influence of model error is decreased to further improve the precision of the NS. By observing the specimen, it is found that the thin-walled hollow section specimen is a bending-shear type damage mode and finally damaged due to the tensile rupture of the stirrup.
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Mei, Zhu. "Structural hybrid simulation with model updating of material constitutive model." Doctoral thesis, University of Trento, 2018. http://eprints-phd.biblio.unitn.it/2959/1/TESI_ZHU_MEI.pdf.
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When hybrid simulation (HS) with substructures is employed for assessing the seismic behavior of a large complex structure, it is unrealistic to test all the components that may exhibit strong nonlinearity. Hence, the accuracy of the numerical substructure (NS) faces an increased challenge. To this end, this paper will emphasize on improving the accuracy of the NS in hybrid simulation based on the model updating approach. Most hybrid simulations with model updating (UHS) focus on updating the parameters of the component constitutive model (story shear model) leading to large modeling errors and the unknown detail responses. Moreover, the most extensively used component constitutive models, such as the Bouc-Wen model, are the models in a narrow sense because they are different for various RC members when the size of the component, boundary conditions, axial compression ratio, and the volumetric stirrup ratio are different from one component to the other. Thus, numerous parameters are needed to describe the displacement-force relations of different components, which leads to the huge computational burden. With this respect, this paper proposes a novel hybrid simulation approach based on identifying and updating the parameters of the material constitutive model. The main work and results are concluded as follows,
1. The unified constitutive model of unconfined and confined concrete is derived from the existing uniaxial concrete constitutive models by introducing the volumetric stirrup ratio.
2. To solve the problem that the relation of the measurements (force of the specimen of a RC member) and the identified parameters (concrete constitutive parameters) are difficult to analytical expressed, an OpenSees embedded unscented Kalman filter is proposed for parameter identification. To this end, several parts of the OpenSees source codes are developed and modified.
3. The proposed identification method and hybrid simulation based on updating the concrete constitutive parameters are respectively validated through a monotonic loading test on a RC column and a UHS on a RC frame. The results show that the convergence values of each parameter under various experimental cases are close to each other with a small variance, which indicates that the proposed identification method is robust and reliable. Comparing to the standard HS, the accuracy of the NS, hence the UHS, is significantly improved.
4. Apply the proposed UHS to a RC continuous rigid bridge with tall thin-walled piers. It concludes that the performance of the identification method is still quite good. Contrasting to the simpler structure, the improved accuracy of a large complex structure is even greater. Moreover, the accuracy of the NS can be greatly increased even though the model error is increased. By tuning the initial values of constitutive parameters, the negative influence of model error is decreased to further improve the precision of the NS. By observing the specimen, it is found that the thin-walled hollow section specimen is a bending-shear type damage mode and finally damaged due to the tensile rupture of the stirrup.
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Sitanggang, Khairil Irfan. "Boussinesq-equation and rans hybrid wave model." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2795.
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Murphy, Hunter A. "Hybrid image/model based gaze-contingent rendering." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202498841/.
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Blais, Bruno. "Model-based visual inspection of hybrid circuits." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63928.
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Merlin, J. H. "Hybrid mesons in the flux-tube model." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375288.
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Henry, Melvin Michael 1968. "Model-based estimation of probabilistic hybrid automata." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/82249.
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Bin, Hasnan Khalid. "Methodology to develop hybrid simulation/emulation model." Thesis, Sheffield Hallam University, 2005. http://shura.shu.ac.uk/19768/.
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Trends towards reduced life-time of products and globalised competition has increased pressure on manufacturing industries to be more responsive to changing needs of product markets. Consequently, the use of simulation to describe short term future performance of manufacturing system has become more significant than ever. An application of simulation that has attracted attention is for testing of control logic before commissioning on site by using a detailed simulation model called emulation model. However, though the success of using emulation particularly in improving cost-effectiveness of automated material handling system delivery has been acknowledged by industries and simulation model developers, the uptake for this technology is still low. The major inhibitors are the high costs of its model building as well as simulation and emulation models are perceived to be non convertible. The main objective, of this research is to establish a methodology to develop simulation model that can be converted into emulation model with ease, thus making emulation technology more affordable. The product of this research called the methodology to build Hybrid Simulation Emulation Model (HSEM) is a new approach of building emulation model comprising of three phases namely (1) development of base simulation model, (2) development of detail emulation model, and (3) integration of controller with the emulation model. Important requirements for HSEM are flexibility of adding details to the simulation model and inter process communication between model and real control system. To facilitate implementation of the methodology, it is essential that the simulation software package provide functionalities for modular model development, access and adding of codes, integration with other application and real time (RT) modelling. The methodology developed offers a more affordable emulation modelling and an opening for further research into the comprehensive support for the implementation of real time control system testing using emulation.
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Šandera, Čeněk. "Hybridní model metaheuristických algoritmů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234259.
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The main topic of this PhD thesis is metaheuristic algorithm in wider scope. The first chapters are dedicated to a description of broader context of metaheuristics, i.e. various optimization classes, determination of their omplexity and different approaches to their solutions. The consequent discussion about metaheuristics and their typical characteristics is followed by several selected examples of metaheuristics concepts. The observed characteristics serve as a base for building general metaheuristics model which is suitable for developing brand new or hybrid algorithms. The thesis is concluded by illustration of author’s publications with discussion about their adaptation to the proposed model. On the attached CD, there is also available a program implementation of the created model.
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Natter, Martin, and Markus Feurstein. "Correcting for CBC model bias. A hybrid scanner data - conjoint model." SFB Adaptive Information Systems and Modelling in Economics and Management Science, WU Vienna University of Economics and Business, 2001. http://epub.wu.ac.at/880/1/document.pdf.
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Choice-Based Conjoint (CBC) models are often used for pricing decisions, especially when scanner data models cannot be applied. Up to date, it is unclear how Choice-Based Conjoint (CBC) models perform in terms of forecasting real-world shop data. In this contribution, we measure the performance of a Latent Class CBC model not by means of an experimental hold-out sample but via aggregate scanner data. We find that the CBC model does not accurately predict real-world market shares, thus leading to wrong pricing decisions. In order to improve its forecasting performance, we propose a correction scheme based on scanner data. Our empirical analysis shows that the hybrid method improves the performance measures considerably. (author's abstract)Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"
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Werner, Quentin. "Model-based optimization of electrical system in the early development stage of hybrid drivetrains." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0109.
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Cette thèse analyse les challenges auxquels sont confrontés les composants électriques pour les systèmes de traction hybrides. L’analyse de ces composants et de leurs interactions en tant qu’entité indépendante est un sujet de recherche important afin de dimensionner de manière optimale le système au lieu de combiner des composants optimaux. Les véhicules hybrides sont un domaine de recherche qui suscite un grand intérêt parce qu’il s’agit d’une solution efficace à court terme afin de préparer la transition énergétique vers les véhicules à zéro émission. Malgré les avantages de cette solution, c’est un sujet de recherche complexe car les composants électriques doivent être intégrés dans un système de propulsion conventionnel. Ainsi le but de ce travail de recherche est axé sur la détermination de méthodes appropriées pour étudier les composants électriques et les contributions apportées par cette thèse visent à répondre à la problématique suivante : déterminer le niveau suffisant de détails pour modéliser les systèmes électriques pour les systèmes de traction pour véhicules hybrides afin d’identifier le dimensionnement idéal des composants pour différents systèmes pendant la phase de développement. Afin de résoudre cette problématique, ce rapport est divisé en quatre parties au sein de six chapitres. D’abord l’état de l’art des véhicules hybrides, des composants électriques ainsi que des méthodes d’optimisation associées sont présentés (chapitre 1). Ensuite, pour chaque composant (chapitre 2 à 4), des méthodes de modélisation appropriées sont déterminées afin de les modéliser mais aussi afin d’évaluer leur intégration dans le système de propulsion. Puis, une solution pour l’étude du système globale est déterminée à partir de l’analyse de travaux précédents (chapitre 5). Finalement, une approche d’optimisation est développée et permet d’analyser différents systèmes ainsi que l’influence de différents paramètres sur le dimensionnement (chapitre 6). Grâce à l’analyse du développement actuel et des travaux précédents sur le sujet ainsi qu’au développement d’outils de simulation, cette thèse étudie et analyse les relations entre le niveau de tension et de courant, et les performances du système dans différents cas. Les résultats permettent de déterminer l’influence de ces paramètres sur les composants ainsi que l’impact de l’environnement industriel sur les résultats. En tenant compte du cadre législatif actuel, les résultats convergent globalement tous dans la même direction : une réduction du niveau de tension, respectivement une augmentation du courant, entraine une amélioration du système global par rapport aux méthodes de dimensionnent actuelles. Ces observations sont liées à l’architecture, au cycle d’évaluation et à l’environnement considérés mais les méthodes et l’approche développée ont posé les bases pour étendre les connaissances dans le domaine de l’optimisation des véhicules hybrides. En plus de l’optimisation générale, des cas particuliers sont analysés afin de montrer la modularité des méthodes et l’influence de paramètres supplémentaires (système 48V ou convertisseur Boost). Afin de conclure, cette thèse a mis en place les bases pour l’étude des composants électriques pour les véhicules hybrides. De part un environnement fluctuant et les nombreuses technologies possibles, ce sujet suscite encore un grand intérêt et les points suivants peuvent être encore étudiés de manière plus détaillée : * Application des méthodes pour d’autres systèmes de propulsion (autre architectures hybrides, véhicule à pile à combustible ou tout électrique), * Étude de nouvelles technologies comme le carbure de silicium pour l’électronique de puissance, la machine à reluctance variable ou le sulfure de lithium pour les batteries, * Analyse d’autre cycle d’évaluation ainsi que leur cadre législatif, * Mise en place de structures additionnelles pour l’électronique de puissance, * Validations supplémentaires avec d’autres composantsThis work analyses the challenges faced by the electric components for traction purpose in hybrid drivetrains. It investigates the components and their interactions as an independent entity in order to refine the scope of investigation and to find the best combinations of components instead of the best components combinations. Hybrid vehicle is currently a topic of high interest because it stands for a suitable short-term solution towards zero emission vehicle. Despite its advantages, it is a challenging topic because the components need to be integrated in a conventional drivetrain architecture. Therefore, the focus of this work is set on the determination of the right methods to investigate only the electric components for traction purpose. The aim and the contributions of this work lies thereby in the resolution of the following statement: Determine the sufficient level of details in modeling electric components at the system level and develop models and tools to perform dynamic simulations of these components and their interactions in a global system analysis to identify ideal designs of various drivetrain electric components during the design process. To address these challenges, this work is divided in four main parts within six chapters. First the current status of the hybrid vehicle, the electric components and the associated optimization methods and simulation are presented (first chapter). Then for each component, the right modeling approach is defined in order to investigate the electrical, mechanical and thermal behavior of the components as well as methods to evaluate their integration in the drivetrain (second to fourth chapter). After this, a suitable method is defined to evaluate the global system and to investigate the interactions between the components based on the review of relevant previous works (chapter five). Finally, the last chapter presents the optimization approach considered in this work and the results by analyzing different system and cases (chapter six). Thanks to the analysis of the current status, previous works and the development of the simulations tools, this work investigates the relationships between the voltage, the current and the power in different cases. The results enable, under the considered assumptions of the work, to determine the influence of these parameters on the components and of the industrial environment on the optimization results. Considering the current legislative frame, all the results converge toward the same observation referred to the reference systems: a reduction of the voltage and an increase of the current leads to an improvement of the integration and the performance of the system. These observations are linked with the considered architecture, driving cycle and development environment but the developed methods and approaches have set the basis to extend the knowledge for the optimization of the electric system for traction purpose. Beside the main optimization, special cases are investigated to show the influence of additional parameters (increase of the power, 48V-system, machine technology, boost-converter…) In order to conclude, this work have set the basis for further investigations about the electric components for traction purpose in more electrified vehicle. Due to the constantly changing environment, the new technologies and the various legislative frame, this topic remains of high interest and the following challenges still need to be deeper investigated: * Application of the methods for other drivetrain architecture (series hybrid, power-split hybrid, fuel-cell vehicle, full electric vehicle), * Investigation of new technologies such as silicon-carbide for the power electronics, lithium–sulfur battery or switch reluctance machine, * Investigation of other driving cycle, legislative frame, * Integration of additional power electronics structure, * Further validation of the modeling approaches with additional components
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Gate, James Simon. "Applications of finite model theory : optimisation problems, hybrid modal logics and games." Thesis, Durham University, 2013. http://etheses.dur.ac.uk/7015/.
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There exists an interesting relationships between two seemingly distinct fields: logic from the field of Model Theory, which deals with the truth of statements about discrete structures; and Computational Complexity, which deals with the classification of problems by how much of a particular computer resource is required in order to compute a solution. This relationship is known as Descriptive Complexity and it is the primary application of the tools from Model Theory when they are restricted to the finite; this restriction is commonly called Finite Model Theory. In this thesis, we investigate the extension of the results of Descriptive Complexity from classes of decision problems to classes of optimisation problems. When dealing with decision problems the natural mapping from true and false in logic to yes and no instances of a problem is used but when dealing with optimisation problems, other features of a logic need to be used. We investigate what these features are and provide results in the form of logical frameworks that can be used for describing optimisation problems in particular classes, building on the existing research into this area. Another application of Finite Model Theory that this thesis investigates is the relative expressiveness of various fragments of an extension of modal logic called hybrid modal logic. This is achieved through taking the Ehrenfeucht-Fraïssé game from Model Theory and modifying it so that it can be applied to hybrid modal logic. Then, by developing winning strategies for the players in the game, results are obtained that show strict hierarchies of expressiveness for fragments of hybrid modal logic that are generated by varying the quantifier depth and the number of proposition and nominal symbols available.
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Mosaffa, Payman. "Hybrid cell-centred/vertex model for multicellular systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/461678.
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This thesis presents a hybrid vertex/cell-centred approach to mechanically simulate planar cellular monolayers undergoing cell reorganisation. Cell centres are represented by a triangular nodal network, while the cell boundaries are formed by an associated vertex network. The two networks are coupled through a kinematic constraint which we allow to relax progressively. Cell-cell connectivity changes due to cell reorganisation or remodelling events, are accentuated. These situations are handled by using a variable resting length and applying an Equilibrium-Preserving Mapping (EPM) on the new connectivity, which computes a new set of resting lengths that preserve nodal and vertex equilibrium. As a by-product, the proposed technique enables to recover fully vertex or fully cell-centred models in a seamless manner by modifying a numerical parameter of the model. The properties of the model are illustrated by simulating monolayers subjected to imposed extension and during a wound healing process. The evolution of forces and the EPM are analysed during the remodelling events.Esta tesis presenta un modelo híbrido para la simulación mecánica de monocapas celulares. Este modelo combina métodos de vértices y centrados en la célula, y está orientado al análisis de deformaciones con reorganización celular. Los núcleos vienen representados por nodos que forman una malla triangular, mientras que las contornos (membranas y córtex) forman una malla poligonal de vértices. Las dos mallas se acoplan a través de una restricción cinemática que puede ser relajada de forma controlada. El estudio hace especial hincapié en los cambios de conectividad, tanto debidos a la reorganización celular como el remodelado del citoesqueleto. Estas situaciones se abordan a través de una longitud de referencia variable y aplicando un Mapeo con Conservación de Equilibrio (EPM) que minimiza el error en el equilibrio nodal y en los vértices. La técnica resultante puede ser adaptada progresivamente a través de un parámetro, dando lugar a un modelo exclusivamente de vértices o a uno de centros. Sus propiedades se ilustran en simulaciones de monocapas sujetas a una extensión impuesta y durante el proceso de cicatrizado de heridas. La evolución de las fuerzas y los efectos del EPM durante el remodelado se analizan en estos ejemplos.
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Vasilev, Viktor. "An interactive 3D interface for hybrid model specification." Thesis, Högskolan i Halmstad, Akademin för informationsteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-35366.
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To ease development and lower the entry barrier for new adopters many development environments offer visual means to edit complex data. Cyber-physical systems are a perfect candidate for such manipulations since they are usually described in the form of isolated, well defined components that can be manipulated individually. The physical parts of such systems often can be directly translated into real world objects and allowing the developer to interact with those in a familiar manner can greatly increase the usability and agility of the development process. In this thesis we focus on the exploration of interactive manipulation of hybrid system models. Our research examines a solution based on the Acumen simulation environment. We describe the tight integration between the textual model and 3D visualisation, go into detailed analysis of the implementation and use case-studies to illustrate concrete applications
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Zakaria, Mohamed Ramzy. "The hybrid model, and adaptive educational hypermedia frameworks." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/14247/.
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The amount of information on the web is characterised by being enormous, as is the number of users with different goals and interests. User models have been utilized by adaptive hypermedia systems generally and adaptive educational hypermedia systems (AEHS) particularly to personalize the amount of information they have with respect to each individual's knowledge, background and goals. As a result of the research described herein, a user model called the Hybrid Model has been developed. This model is both generic and abstract, and it extends other models used by AEHS by measuring users' knowledge levels with respect to different knowledge domains simultaneously by utilising well known techniques in the world of user modelling, specifically the Overlay model (which has been modified) and the Stereotype model. Therefore, using the Hybrid Model, AEHS will not be restricted to a single knowledge domain at anyone time. Thus, by implementing the Hybrid model, those systems can manage users' knowledge globally with respect to the deployed knowledge domains. The model has been implemented experimentally in an educational hypermedia system called WHURLE (Web-based Hierarchal Universal Reactive Learning Environment) to verify its aim - managing users' knowledge globally. Moreover, this implementation has been tested successfully through a user trial as an adaptive revision guide for a Biological Anthropology Course. Furthermore, the infrastructure of the WHURLE system has been modified to embrace the objective of the Hybrid Model. This has led to a novel design that provides the system with the capability of utilising different user models easily without affecting any of its component modules.
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Sproston, Jeremy James. "Model checking of probabilistic timed and hybrid systems." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391021.
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Bonilha, Murilo Weingarten. "A hybrid deterministic-probabilistic model for vibroacoustic studies." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242537.
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Chitilian, Varouj A. (Varouj Armen) 1976. "A hybrid deformable model 3-D segmentation algorithm." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80526.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 151).
by Varouj A. Chitilian.
S.B.and M.Eng.
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Young, Brady W. (Brady William). "Physical model of a hybrid electric drive train." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36821.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 36).
A motor and flywheel system was designed to simulate the dynamics of the electric drive train and inertial mass of a hybrid electric vehicle. The model will serve as a test bed for students in 2.672 to study the energy losses between the battery, motor, and kinetic energy of the car during acceleration and regenerative braking over a range of realistic driving profiles. The goal is to maintain fidelity to the dynamics of a road-worthy vehicle while making the model lab-safe and simple to operate. The model drive train will be designed on a one-to-one scale with the vehicle to be simulated. A motor and controller from an electric vehicle will be purchased to provide realistic electric drive for the system. The kinetic energy of the car will be simulated by a flywheel of equivalent mass. To keep the total energy in the system low enough to satisfy safety concerns, the system will be limited to simulating the motion of a light car moving up to ten miles per hour, representative of stop-and-go city traffic.
by Brady W. Young.
S.B.
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Stöver, Hanna. "Metaphor and relevance theory : a new hybrid model." Thesis, University of Bedfordshire, 2010. http://hdl.handle.net/10547/145619.
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This thesis proposes a comprehensive cognitive account of metaphor understanding that combines aspects of Relevance Theory (e.g. Sperber & Wilson 1986/95; Carston 2002) and Cognitive Linguistics, in particular ideas from Conceptual Metaphor Theory (e.g. Lakoff & Johnson 1980; Lakoff 1987; Johnson 1991) and Situated Conceptualization (e.g. Barsalou 1999; 2005). While Relevance Theory accounts for propositional aspects of metaphor understanding, the model proposed here additionally accounts for nonpropositional effects which intuitively make metaphor feel ‗special‘ compared to literal expressions. This is achieved by (a) assuming a further, more basic processing level of imagistic-experiential representations involving mental simulation patterns (Barsalou 1999; 2005) alongside relevance-theoretic inferential processing and (b) assuming processing of the literal meaning of a metaphorical expression at a metarepresentational level, as proposed by Carston (2010). The approach takes Tendahl‘s ‗Hybrid Theory of Metaphor‘ (2006), which also combines cognitive-linguistic with relevance-theoretic ideas, as a starting point. Like Tendahl, it incorporates the notion of conceptual metaphors (Lakoff & Johnson 1980), albeit in a modified form, thus accounting for metaphor in thought. Wilson (2009) suggests that some metaphors originate in language (as previously assumed by Relevance Theory) and others originate in thought (as previously assumed within Cognitive Linguistics). The model proposed here can account for both. Unlike Tendahl, it assumes a modular mental architecture (Sperber 1994), which ensures that the different levels of processing are kept apart. This is because each module handles only its own domain-specific input, here consisting of either propositional or imagistic-experiential representations. The propositional level, which remains the dominant processing route in utterance 3 understanding, as in Relevance Theory, receives some input from the imagistic-experiential level. This is mediated at a metarepresentational level, which turns the imagistic-experiential representations into propositional material to be processed at the inferential level in the understanding of literal expressions. In metaphor understanding, however, the literal meaning is not processed as meaning-constitutive content. As a result, the imagistic-experiential aspects of the literal meaning in question are not processed as propositional input. Rather, they are held at the metarepresentational level and experienced as strong impressions of the kind that only metaphors can communicate.
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Goodell, Brandon Grae. "Bifurcation Portrait of a Hybrid Spiking Neuron Model." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26666.
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A bifurcation portrait classifies the behavior of a dynamical system and how it transitions between different behaviors. A hybrid dynamical system displays both continuous and discrete dynamics and may display nonsmooth bifurcations. Herein, we analyze a novel hybrid model of a spiking neuron proposed by E.M. Izhikevich [9] that is based on a previous hybrid model with a convex spike-activation function f(x), but modified with a conductance reversal potential term. We analyze the model proposed by Izhikevich and obtain a bifurcation portrait for the continuous dynamics for an arbitrary convex spike activation function f(x). Both subcritical and supercritical Andronov-Hopf bifurcations are possible, and we numerically confirm the presence of a Bautin bifurcation for a particular choice of spike activation function. The model is capable of simulating common cortical neuron types and presents several possibilities for generalizations that may be capable of more complicated behavior.
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Tantrum, Jeremy. "Model based and hybrid clustering of large datasets /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8933.
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Pratap, Kadam Poonam. "Radiometric Calibration of a Hybrid RCWT Imaging Model." Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/339045.
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The applications of low-light imaging are widespread in areas such as biomedical imaging, remote sensing, ratiometric imaging, lithography, etc. The goal of this work is to develop a radiometrically scaled hybrid RCWT calculator to count the photons detected for such applications. The rigorous computation of different imaging models are discussed. An approach to calibrate the radiometry of the hybrid RCWT model for partially coherent illumination is presented. The diffraction from the object is evaluated rigorously using the hybrid RCWT model. A test bench is set up to validate the radiometrically scaled simulations. In all the cases considered, simulation and experiment agree within a 40% difference.
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Jiang, Peng. "A Hybrid Risk Model for Hip Fracture Prediction." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/579112.
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Hip fracture has long been considered as the most serious consequence of osteoporosis, which includes chronic pain, disability, and even death. In the elderly population, a femur fracture is very common. It is assessed that 50% of women aged 50 or older may experience a hip fracture in their remaining life. Hip fracture is among the most common injuries and can lead to substantial morbidity and mortality. In the US alone, over 250,000 hip fractures occur each year and this number is expected to double by the year 2040. Statistics indicate that over 20% of people who experience a hip fracture die within one year and only 25% have a total recovery. Femur fractures are now becoming a major social and economic burden on the health care system. In practice, it is very difficult to predict the femur fracture risks. One of the main reasons is that there is not a robust and easy-to-get measure to quantify the strength of the bone. Clinicians use bone mineral density (BMD) as an indicator of osteoporosis and fracture risk. Several studies showed that BMD cannot be used alone to identify bone strength. In fact, the majority of patients who suffer from fractures have normal or even higher BMD scores. There are a large number of risk factors that contribute to the occurrence of femur fracture, which should also be involved in predicting hip fracture risks. For example, age, weight, height, ethnicity and so on. Some of the factors might not have been identified yet. Thus, there will be a high level of uncertainty in the clinical dataset, which makes it difficult to construct and validate a hip risk prediction model. The objective of the dissertation is to construct an improved hip fracture risk prediction model. Due to the difficulty of obtaining experimental or clinical data, computational simulations might help increase the predictive ability of the risk model. In this research, the hip fracture risk model is based on a support vector machine (SVM) trained using a clinical dataset from the Women's Health Initiative (WHI). In order to improve the SVM-based hip fracture risk model, data from a fully parameterized finite element (FE) model is used to supplement the clinical dataset. This FE model allows one to simulate a wide range of geometries and material properties in the hip region, and provides a measure of risk based on mechanical quantities (e.g., strain). This dissertation presents new approaches to fuse the clinical data with the FE data in order to improve the predictive capability of the hip fracture risk prediction model. Two approaches are introduced in this dissertation to construct a hybrid risk model: an "augmented space" approach and a "computational patients" approach. This work has led to the construction of a new online hip fracture risk calculator with free access.
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Akermi, Imen. "A hybrid model for context-aware proactive recommendation." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30101/document.
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L'accès aux informations pertinentes, adaptées aux besoins et au profil de l'utilisateur est un enjeu majeur dans le cadre actuel caractérisé par une prolifération massive des ressources d'information hétérogènes. Le développement d'appareils mobiles équipés de plusieurs fonctionnalités telles que la caméra, le WIFI, la géo-localisation et bien plus d'autres permettent aux systèmes mobiles de recommandation actuels d'être hautement contextualisés et pouvant fournir à l'utilisateur des informations pertinentes au bon moment quand il en a le plus besoin, sans attendre qu'il établisse une interaction avec son appareil. C'est dans ce cadre que s'insère notre travail de thèse. En effet, nous proposons une approche de recommandation contextuelle et proactive dans un environnement mobile qui permet de recommander des informations pertinentes à l'utilisateur sans attendre à ce que ce dernier initie une interaction. Un système proactif peut prendre la forme d'un guide touristique personnalisé qui se base sur la localisation et les préférences de l'utilisateur pour suggérer à ce dernier des endroits intéressants sans qu'il fournisse, sa préférence ou une requête explicite. Cela permettra de réduire les efforts, le temps et l'interaction de l'utilisateur avec son appareil mobile et de présenter les informations pertinentes au bon moment et au bon endroit. Cette approche prend aussi en considération les situations où la recommandation pourrait déranger l'utilisateur. Il s'agit d'équilibrer le processus de recommandation contre les interruptions intrusives. En effet, il existe différents facteurs et situations qui rendent l'utilisateur moins ouvert aux recommandations. Comme nous travaillons dans le contexte des appareils mobiles, nous considérons que les applications mobiles telles que la caméra, le clavier, l'agenda, etc., sont de bons représentants de l'interaction de l'utilisateur avec son appareil puisqu'ils représentent en quelque sorte la plupart des activités qu'un utilisateur pourrait entreprendre avec son appareil mobile au quotidien, comme envoyer des messages, converser, tweeter, naviguer ou prendre des photosJust-In-Time recommender systems involve all systems able to provide recommendations tailored to the preferences and needs of users in order to help them access useful and interesting resources within a large data space. The user does not need to formulate a query, this latter is implicit and corresponds to the resources that match the user's interests at the right time. Our work falls within this framework and focuses on developing a proactive context-aware recommendation approach for mobile devices that covers many domains. It aims at recommending relevant items that match users' personal interests at the right time without waiting for the users to initiate any interaction. Indeed, the development of mobile devices equipped with persistent data connections, geolocation, cameras and wireless capabilities allows current context-aware recommender systems (CARS) to be highly contextualized and proactive. We also take into consideration to which degree the recommendation might disturb the user. It is about balancing the process of recommendation against intrusive interruptions. As a matter of fact, there are different factors and situations that make the user less open to recommendations. As we are working within the context of mobile devices, we consider that mobile applications functionalities such as the camera, the keyboard, the agenda, etc., are good representatives of the user's interaction with his device since they somehow stand for most of the activities that a user could use in a mobile device in a daily basis such as texting messages, chatting, tweeting, browsing or taking selfies and pictures
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Kronberg, Craig. "Economics of Hybrid Long-Haul Trucks." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_theses/210.
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A model of long-haul hybrid-electric trucks was developed and analyzed to identify the economic benefits of hybrids during the 2009 to 2030 timeframe. Variables that were studied included the trucks operating miles, vehicle life years, fuel efficiency, hybrid fuel efficiency, cost of hybrid truck technology and diesel fuel costs. The model was studied using a case study of long-haul tractors to determine the life cycle savings of hybrid trucks during the twenty-year time period. It was predicted that hybrid long-haul trucks will be an option for trucks that have a majority of their operating cost spent on fuel and the truck is capable of achieving an improved efficiency of five-percent or greater. It was concluded that hybrid trucks will become more economical than a conventional diesel truck and generate a savings for fleet owners by as early as the year 2014. Recommendation for further study is enclosed.
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Maheo, Aurèle. "Improving the Hybrid model MPI+Threads through Applications, Runtimes and Performance tools." Thesis, Versailles-St Quentin en Yvelines, 2015. http://www.theses.fr/2015VERS039V/document.
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Afin de répondre aux besoins de plus en plus importants en puissance de calcul de la part des applicationsnumériques, les supercalculateurs ont dû évoluer et sont ainsi de plus en plus compliqués àprogrammer. Ainsi, en plus de l’apparition des systèmes à mémoire partagée, des architectures ditesNUMA (Non Uniform Memory Access) sont présentes au sein de ces machines, fournissant plusieursniveaux de parallélisme. Une autre contrainte, la diminution de la mémoire disponible par coeur decalcul, doit être soulignée. C’est ainsi que des modèles parallèles tels que MPI (Message Passing Interface)ne permettent plus aux codes scientifiques haute performance de passer à l’echelle et d’exploiterefficacement les machines de calcul, et doivent donc être combinés avec d’autres modèles plus adaptésaux architectures à mémoire partagée. OpenMP, en tant que modèle standardisé, est un choix privilégiépour être combiné avec MPI. Mais mélanger deux modèles avec des paradigmes différents est unet âche compliquée et peut engendrer des goulets d’étranglement qui doivent être identifiés. Cette thèsea pour objectif d’aborder ces limitations et met en avant plusieurs contributions couvrant divers aspects.Notre première contribution permet de r éduire le surcoût des supports exécutifs OpenMP en optimisantle travail d’activation et de synchronisation des threads OpenMP pour les codes MPI+OpenMP. Dansun second temps, nous nous focalisons sur les opérations collectives MPI. Notre contribution a pourbut d’optimiser l’opération MPI Allreduce en réutilisant des unités de calcul inoccupées, et faisant intervenirdes threads OpenMP. Nous introduisons également le concept de collectives unifiées, impliquantdes tâches MPI et des threads OpenMP dans une même opération. Enfin, nous nous intéressons àl’analyse de performance et plus précisément l’instrumentation des applications MPI+OpenMP, et notredernière contribution consiste en l’implémentation et l’ évaluation de l’outil OpenMP Tools API (OMPT)dans le support exécutif OpenMP du framework MPC. Cet outil nous permet d’instrumenter des constructionsOpenMP et de conduire une analyse axée aussi bien du côté des applications que dessupports d’exécutionTo provide increasing computational power for numerical simulations, supercomputers evolved and arenow more and more complex to program. Indeed, after the appearance of shared memory systemsemerged architectures such as NUMA (Non Uniform Memory Access) systems, providing several levelsof parallelism. Another constraint, the decreasing amount of memory per compute core, has to bementioned. Therefore, parallel models such as Message Passing Interface (MPI) are no more sufficientto enable scalability of High Performance applications, and have to be coupled with another modeladapted to shared memory architectures. OpenMP, as a de facto standard, is a good candidate to bemixed with MPI. The principle is to use this model to augment legacy codes already parallelized withMPI. But hybridizing scientific codes is a complex task, bottlenecks exist and need to be identified. Thisthesis tackles these limitations and proposes different contributions following various aspects. Our firstcontribution reduces the overhead of the OpenMP layer by optimizing the creation and synchronizationof threads for MPI+OpenMP codes. On a second time, we target MPI collective operations. Our contributionconsists in proposing a technique to exploit idle cores in order to help the operation, with theexample of MPI Allreduce collective. We also introduce unified Collectives involving both MPI tasks andOpenMP threads. Finally, we focus on performance analysis of hybrid MPI+OpenMP codes, and ourlast contribution consists in the implementation of OpenMP Tools API (OMPT), an instrumentation tool,inside the OpenMP runtime of MPC framework. This tool allows us to instrument and profile OpenMPconstructs and allows the analysis of both runtime and application sides
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Castellanos, Carrazana Abel. "Performance model for hybrid MPI+OpenMP master/worker applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/283403.
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En el entorno actual, diversas ramas de las ciencias, tienen la necesidad de auxiliarse de la computación de altas prestaciones para la
obtención de resultados a relativamente corto plazo. Ello es debido fundamentalmente, al alto volumen de información que necesita ser
procesada y también al costo computacional que demandan dichos cálculos. El beneficio al realizar este procesamiento de manera distribuida y
paralela, logra acortar de manera notable los tiempos de espera en la obtención de los resultados.
Para soportar ello, existen fundamentalmente dos modelos de programación ampliamente extendidos: el modelo de paso de mensajes a través de
librerías basadas en el estándar MPI, y el de memoria compartida con la utilización de OpenMP. Las aplicaciones híbridas son aquellas que
combinan ambos modelos con el fin de aprovechar en cada caso, las potencialidades específicas del paralelismo en cada uno. Lamentablemente,
la práctica ha demostrado que la utilización de esta combinación de modelos, no garantiza necesariamente una mejoría en el comportamiento de
las aplicaciones. Existen varios parámetros que deben ser considerados a determinar la configuración de la aplicación que proporciona el mejor
tiempo de ejecución. El número de proceso que se debe utilizar, el número de hilos en cada nodo, la distribución de datos entre procesos e hilos,
y así sucesivamente, son parámetros que afectan seriamente elrendimiento de
la aplicación. El valor apropiado de tales parámetros depende, por una parte, de las características de arquitectura del sistema
(latencia de las comunicaciones, el ancho de banda de comunicación, el tamaño y la distribución de los niveles de memoria cache,
la capacidad de cómputo, etc.) y, por otro lado, de la características propias del comportamiento de la aplicación.
La contribución fundamental de esta tesis radica en la utilización de una técnica novedosa para la predicción del rendimiento y la
eficiencia de aplicaciones híbridas de tipo Master/Worker. En particular, dentro del mundo del aprendizaje automatizado, este método de
predicción es conocido como arboles de regresión basados en modelos análiticos. Los resultados experimentales obtenidos permiten ser
optimista en cuanto al uso de este algoritmo para la predicción de ambas métricas o para la selección de la mejor configuración de
parámetros de ejecución de la aplicación.In the current environment, various branches of science are in need of auxiliary high-performance computing to obtain relatively short-term results. This is mainly due to the high volume of information that needs to be processed and the computational cost demanded by these calculations. The benefit to performing this processing using distributed and parallel programming mechanisms is that it achieves shorter waiting times in obtaining the results. To support this, there are basically two widespread programming models: the model of message passing based on the standard libraries MPI and the shared memory model with the use of OpenMP. Hybrid applications are those that combine both models in order to take the specific potential of parallelism of each one in each case. Unfortunately, experience has shown that using this combination of models does not necessarily guarantee an improvement in the behavior of applications. There are several parameters that must be considered to determine the configuration of the application that provides the best execution time. The number of process that must be used,the number of threads on each node, the data distribution among processes and threads, and so on, are parameters that seriously affect the performance of the application. On the one hand, the appropriate value of such parameters depends on the architectural features of the system (communication latency, communication bandwidth, cache memory size and architecture, computing capabilities, etc.), and, on the other hand, on the features of the application. The main contribution of this thesis is a novel technique for predicting the performance and efficiency of parallel hybrid Master/Worker applications. This technique is known as model-based regression trees into the field of machine learning. The experimental results obtained allow us to be optimistic about the use of this algorithm for predicting both metrics and to select the best application execution parameters.
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Sachs, Julia [Verfasser]. "Model-Based Optimization of Hybrid Energy Systems / Julia Sachs." Aachen : Shaker, 2016. http://d-nb.info/1101185112/34.
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Lee, Hyun Seung. "A HYBRID MODEL FOR DTM GENERATION FROM LIDAR DATA." MSSTATE, 2004. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11022004-053808/.
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This dissertation introduces an innovative technique to extract ground elevation models using small-footprint LIDAR data. This technique consists of a preprocessing step, ground modeling, and interpolation. In the preprocessing step, much of the non-terrain points are eliminated using a histogram-based clustering technique. Then, in the ground modeling stage, the information such as elevation and slope between nearest neighbor points is extracted. This step corresponds to an outlier detection process. In this stage, residuals and gradient indices for elevation and slope, are introduced. These indices are investigated for a constructed 95% confidence interval to discard the remaining non-terrain points. Finally, using spline interpolation, a smooth ground surface is generated. Experimental results show that the presented technique is more robust and yields better results compared to existing techniques, such as linear prediction, modified linear prediction, and adaptive smoothing, in terms of the root mean squared error, absolute mean, and absolute standard deviation. Furthermore, the possibility of using a ground trend model developed from specific tree height measurements is investigated. For this analysis, a statistical regression analysis model is used. Performing this analysis, a 0.63 R-squared value is obtained. This result indicates that the LIDAR ground surface obtained from the presented algorithm is related to the true ground surface.
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Sundström, Christofer. "Model Based Vehicle Level Diagnosis for Hybrid Electric Vehicles." Doctoral thesis, Linköpings universitet, Fordonssystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-105487.
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When hybridizing a vehicle, new components are added that need to be monitored due to safety and legislative demands. Diagnostic aspects due to powertrain hybridization are investigated, such as that there are more mode switches in the hybrid powertrain compared to a conventional powertrain, and that there is a freedom in choosing operating points of the components in the powertrain via the overall energy management and still fulfill the driver torque request. A model of a long haulage truck is developed, and a contribution is a new electric machine model. The machine model is of low complexity, and treats the machine constants in a different way compared to a standard model. It is shown that this model describes the power losses significantly better when adopted to real data, and that this modeling improvement leads to better signal separation between the non-faulty and faulty cases compared to the standard model. To investigate the influence of the energy management design and sensor configuration on the diagnostic performance, two vehicle level diagnosis systems based on different sensor configurations are designed and implemented. It is found that there is a connection between the operating modes of the vehicle and the diagnostic performance, and that this interplay is of special relevance in the system based on few sensors. In consistency based diagnosis it is investigated if there exists a solution to a set of equations with analytical redundancy, i.e. there are more equations than unknown variables. The selection of sets of equations to be included in the diagnosis system and in what order to compute the unknown variables in the used equations affect the diagnostic performance. A systematic method that finds properties and constructs residual generator candidates based on a model has been developed. Methods are also devised for utilization of the residual generators, such as initialization of dynamic residual generators, and for consideration of the fault excitation in the residuals using the internal form of the residual generators. For demonstration, the model of the hybridized truck is used in a simulation study, and it is shown that the methods significantly increase the diagnostic performance. The models used in a diagnosis system need to be accurate for fault detection. Map based models describe the fault free behavior accurately, but fault isolability is often difficult to achieve using this kind of model. To achieve also good fault isolability performance without extensive modeling, a new diagnostic approach is presented. A map based model describes the nominal behavior, and another model, that is less accurate but in which the faults are explicitly included, is used to model how the faults affect the output signals. The approach is exemplified by designing a diagnosis system monitoring the power electronics and the electric machine in a hybrid vehicle, and simulations show that the approach works well.
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Saad, Sameh M. I. "Design and analysis of a flexible hybrid assembly model." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240491.
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Gerlach, Jorg C. "Culture model for hepatocytes in hybrid liver support bioreactors." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248963.
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Liu, Enjie. "A hybrid queueing model for fast broadband networking simulation." Thesis, Queen Mary, University of London, 2002. http://qmro.qmul.ac.uk/xmlui/handle/123456789/3815.
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This research focuses on the investigation of a fast simulation method for broadband telecommunication networks, such as ATM networks and IP networks. As a result of this research, a hybrid simulation model is proposed, which combines the analytical modelling and event-driven simulation modelling to speeding up the overall simulation. The division between foreground and background traffic and the way of dealing with these different types of traffic to achieve improvement in simulation time is the major contribution reported in this thesis. Background traffic is present to ensure that proper buffering behaviour is included during the course of the simulation experiments, but only the foreground traffic of interest is simulated, unlike traditional simulation techniques. Foreground and background traffic are dealt with in a different way. To avoid the need for extra events on the event list, and the processing overhead, associated with the background traffic, the novel technique investigated in this research is to remove the background traffic completely, adjusting the service time of the queues for the background traffic to compensate (in most cases, the service time for the foreground traffic will increase). By removing the background traffic from the event-driven simulator the number of cell processing events dealt with is reduced drastically. Validation of this approach shows that, overall, the method works well, but the simulation using this method does have some differences compared with experimental results on a testbed. The reason for this is mainly because of the assumptions behind the analytical model that make the modelling tractable. Hence, the analytical model needs to be adjusted. This is done by having a neural network trained to learn the relationship between the input traffic parameters and the output difference between the proposed model and the testbed. Following this training, simulations can be run using the output of the neural network to adjust the analytical model for those particular traffic conditions. The approach is applied to cell scale and burst scale queueing to simulate an ATM switch, and it is also used to simulate an IP router. In all the applications, the method ensures a fast simulation as well as an accurate result.
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Hulcher, Zachary R. "Resolution effects in the hybrid strong/weak coupling model." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/111887.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 33-34).
Within the context of a hybrid strong/weak coupling model of jet quenching, we study the consequences of the fact that the plasma produced in a heavy ion collision cannot resolve the substructure of a collimated parton shower within it to arbitrary resolution. We introduce a screening length parameter, LRes, proportional to the inverse of the local temperature in the plasma, estimating the value of the proportionality constant from both weakly coupled QCD calculations and holographic calculations appropriate in strongly coupled plasma. We then modify the hybrid model so that when a parton in a jet shower splits, its two offspring are initially treated as unresolved, and are only treated as two separate partons losing energy independently after they are separated by a distance LRes. This modification delays the quenching of partons with intermediate energy, resulting in the survival of more hadrons in the final state with PT in the several GeV range. We demonstrate that this effect modifies the jet shapes and jet fragmentations functions, as it makes it more probable for particles carrying a small fraction of the jet energy at larger angles from the jet axis to survive their passage through the quark-gluon plasma. We analyze the consequences of different choices for the value of the resolution length LRes on both partonic and hadronic jet shapes and fragmentation functions, as well as on missing-PT observables. More generally, we discuss the qualitative consequences, and importance, of including the effects of finite resolution.
by Zachary R. Hulcher.
S.B.
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Selles, Anthony. "Hybrid model : investigating bilingual language production through code-switching." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31373.
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Bilingual language production is an area of psycholinguistic research that has received recent attention. Experimental evidence from bilingual word production tasks has shown that both languages share representation at the mental lexicon, meaning that concepts will lead to the activation of the target lemma from both languages. Investigations into how bilinguals organise two grammatical systems has largely come from cross-linguistic syntactic priming. Syntactic priming is a phenomenon in which speakers are likely to repeat a syntactic structure in which they have recently experienced: cross-linguistic syntactic priming is when a speaker uses a syntactic structure in one language because they have recently experienced that structure from the other language. Together, the study of the bilingual lexicon and syntactic representations have led to the development of models of bilingual language production. A more recent experimental paradigm is the forced code-switching task in which participants are required to code-switch in some experimental trials. The forced code-switching task is the experimental method used in this thesis. This thesis aims to use this experimental task to test my proposed model of bilingual language production, the Hybrid model. The Hybrid model proposes an architecture of the bilingual lemma stratum that differs from previous models of bilingual language production. The Hybrid model assumes that lexical items from one language can be produced using the syntactic structure of the other language. In this thesis I report seven experiments testing the proposed lemma stratum of the Hybrid model. Experiment 3.1 investigated the production of prenominal adjectives of English and postnominal adjectives of Spanish during code-switching between Spanish and English to see whether speakers would use the lexical items from one language with the word order of the other language. The results showed that speakers almost exclusively used the word order dictated by the language in which they produced the lexical items. This did not support the proposed lemma stratum of the Hybrid model. Experiments 4.1 and 4.2 investigated gender agreement of possessive pronouns during code-switching between Spanish and English to see if the possessive pronoun from one language could be produced using the gender agreement rules from the other language. The results showed that English-Spanish and Spanish-English bilinguals sometimes produced possessive pronouns in one language with the gender agreement rules from the other language. It was demonstrated that this effect was not due to a misunderstanding of the gender agreement rules of the participants' second language. These results support the proposed lemma stratum of the Hybrid model. Experiments 5.1 and 5.2 investigated gender agreement of possessive determiners during code-switching between French and English to see if the possessive determiner from one language could be produced using the gender agreement rules from the other language. The results showed that English-French and French-English bilinguals sometimes produced possessive determiners in one language with the gender agreement rules from the other language. It was demonstrated that this effect was not due to a misunderstanding of the gender agreement rules of the participants' second language. These results support the proposed lemma stratum of the Hybrid model. Experiments 6.1 and 6.2 investigated the production of determiners during code-switching between German and English. Of specific interest was whether English determiners would be produced more often than German determiners because German determiners hold case information whereas English determiners do not. In Experiment 6.1 participants were forced to code-switch before an accusative NP. The results showed that English determiners were sometimes produced within the German NPs, but German determiners were not used within the English NPs. In Experiment 6.2 participants were forced to code-switch before a dative NP. The results showed that participants almost exclusively produced the determiner in the same language as the target noun. Analysing the frequencies of the determiner used within the experimental session, the different pattern of results between Experiments 6.1 and 6.2 may be a result of a competition for selection between determiner forms. To conclude the thesis I discuss the implications of these findings, what they mean for the Hybrid model, and directions for future research.
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Hulcher, Zachary R. "Resolution effects in the hybrid strong/weak coupling model." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111887.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 33-34).
Within the context of a hybrid strong/weak coupling model of jet quenching, we study the consequences of the fact that the plasma produced in a heavy ion collision cannot resolve the substructure of a collimated parton shower within it to arbitrary resolution. We introduce a screening length parameter, LRes, proportional to the inverse of the local temperature in the plasma, estimating the value of the proportionality constant from both weakly coupled QCD calculations and holographic calculations appropriate in strongly coupled plasma. We then modify the hybrid model so that when a parton in a jet shower splits, its two offspring are initially treated as unresolved, and are only treated as two separate partons losing energy independently after they are separated by a distance LRes. This modification delays the quenching of partons with intermediate energy, resulting in the survival of more hadrons in the final state with PT in the several GeV range. We demonstrate that this effect modifies the jet shapes and jet fragmentations functions, as it makes it more probable for particles carrying a small fraction of the jet energy at larger angles from the jet axis to survive their passage through the quark-gluon plasma. We analyze the consequences of different choices for the value of the resolution length LRes on both partonic and hadronic jet shapes and fragmentation functions, as well as on missing-PT observables. More generally, we discuss the qualitative consequences, and importance, of including the effects of finite resolution.
by Zachary R. Hulcher.
S.B.
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Modi, Rishit Bipinkumar. "Control-Oriented Thermal Model for a Hybrid Vehicle Battery." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/98661.
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In a bid to reduce vehicular emissions, automobile manufacturers are moving towards elec- tric and hybrid vehicles. Most hybrid vehicles use Lithium-ion batteries as energy storage systems. Lithium-ion batteries have a narrow range of temperature within which they can be operated efficiently. Operation of Lithium-ion batteries outside this range decreases the life of batteries and reduces performance of the vehicle. Due to this limitation, it is important to prevent overheating of Lithium-ion batteries. Battery pack studied in this work has a fan system for air-cooling the cells. The battery management system (BMS) in the battery pack functions to keep the temperature of the cells within allowable limits by either regulating the fan speed or communicating with the vehicle controller to adjust magnitude of applied current. BMS used in the work is equipped with limited number of temperature sensors that can measure surface temperature of few cells in the battery pack. Additional temper- ature information can be used for better thermal control of the cells in the battery pack. Lithium-ion cells are known to have a measurable temperature gradient when operating un- der extreme conditions. As a result, the surface temperature of cells as measured by the temperature sensors in BMS is not always representative of the maximum cell temperature. To overcome these limitations, a simplified transient thermal model predicting core and sur- face temperature of cell is presented in this work. This model can be implemented in a BMS for real-time control of cell temperature. The thermal model is validated against data avail- able from testing the battery pack. Different current profiles, representative of real-world driving scenarios, are applied to the thermal model and the temperature rise of cells under those conditions is studied. For an array of cells, the thermal model predicts significant
temperature rise along the airflow direction, suggesting the use of last cell temperature for thermal control. For short duration, high magnitude of current pulses, temperature rise is shown to be similar for same thermal energy deposited by different current pulses. The maximum thermal energy that can be deposited in the battery by a current pulse can be determined for given conditions of airflow rate, continuous current and air inlet temperature. The maximum magnitude of thermal energy that can be deposited by a peak current pulse to limit cell temperature is shown to be a function of current magnitude squared and the pulse duration time. For multiple current pulses applied to the battery pack, the model can evaluate the minimum time interval between current pulses to keep the temperature of cells within prescribed limits. The minimum time required between two current pulses is shown to decrease by increasing the airflow rate through the battery pack. By increasing the airflow rate, the battery pack is able to operate at a higher continuous current without exceeding the temperature limit.Master of Science
In a bid to reduce vehicular emissions, automobile manufacturers are moving towards electric and hybrid vehicles. Most hybrid vehicles have an energy storage system in addition to the conventional Internal Combustion (I.C.) engine. Lithium-ion batteries are used as energy storage systems in most hybrid vehicles due to their high energy density, long life and low self discharge rate. Lithium-ion batteries can be operated efficiently only in a narrow range of temperature. Operating these batteries outside of this temperature range results in their faster degradation which results in lower performance of hybrid vehicle. Due to this limi- tation, prevention of overheating in Lithium-ion batteries is extremely important. To keep the operation of Lithium-ion batteries within specified temperature limits, most batteries in hybrid vehicles are equipped with battery management systems (BMS). The BMS monitors cell voltage, cell temperature and applied current and keeps the temperature of cells within allowable limits. BMS of the battery pack used in this work has fan system for air-cooling the individual cells, and can lower the temperature rise of the cells by varying the fan speed. This BMS has limited temperature sensors that can predict surface temperature of few cells of the battery pack. Additional temperature information can be used to improve thermal control of the battery pack. This work presents a simplified thermal model that can be used in controller of a BMS to improve thermal control of cells and keep the temperature of cells within specified limits.
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Sterley, Christopher. "Characteristic function pricing with the Heston-LIBOR hybrid model." Master's thesis, Faculty of Commerce, 2019. http://hdl.handle.net/11427/31273.
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We derive an approximate characteristic function for a simplified version of the Heston-LIBOR model, which assumes a constant instantaneous volatility structure in the underlying LIBOR market model. We also implement measures to improve the numerical stability of the characteristic function derived in this dissertation as well as the one derived by Grzelak and Oosterlee. The ultimate aim of the dissertation is to prevent these characteristic functions from exploding for given parameter values.
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Wright, James Frederick Carleton University Dissertation Geography. "A hybrid model for predicting permafrost occurrence and thickness." Ottawa, 1995.
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Takahashi, Ribeka. "A Hybrid Bishop-Hill Model for Microstructure Sensitive Design." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3528.
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A method is presented for adapting the classical Bishop-Hill model to the requirements of elastic/yield-limited design in metals of arbitrary crystallographic texture. The proposed Hybrid Bishop-Hill (HBH) model, which will be applied to ductile FCC metals, retains the `stress corners' of the polyhedral Bishop-Hill yield surface. However, it replaces the `maximum work criterion' with a criterion that minimizes the Euclidean distance between the applicable local corner stress state and the macroscopic stress state. This compromise leads to a model that is much more accessible to yield-limited design problems. Demonstration of performance for the HBH model is presented for an extensive database for oxygen free electronic (OFE) copper. The study also implements the HBH model to the polycrystalline yield surface via standard finite element analysis (FEA) tools to carry out microstructure-sensitive design. Anisotropic elastic properties are incorporated into the FEA software, as defined by the sample texture. The derived local stress tensor is assessed using the HBH approach to determine a safety factor relating to the distance from the yield surface, and thereby highlighting vulnerable spots in the component and obtaining a quantitative ranking for suitability of the given design. By following standard inverse design techniques, an ideal microstructure (meaning texture in this context) may be arrived at. The design problems considered is a hole-in-plate configuration of sheets loaded in uniaxial tension and simple compliant mechanisms. The further improvement of HBH model is discussed by introducing geometrically necessary dislocation (GND) densities in addition to the crystal orientations procedure in standard microstructure-based method. The correlations between crystal orientations and GND densities are studied. The shape of the yield surface most influenced by the texture of the material, while the volume of the envelope scales in accordance with the GND density. However, correlations between crystal orientation and GND content modify the yield surface shape and size. While correlations between GND density and crystal orientation are not strong for most copper samples, there are sufficient dependencies to demonstrate the benefits of the detailed four-parameter model. The four-parameter approach has potential for improving estimates of elastic-yield limit in all polycrystalline FCC materials.
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Li, Yuntao. "Federated Learning for Time Series Forecasting Using Hybrid Model." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254677.
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Time Series data has become ubiquitous thanks to affordable edge devices and sensors. Much of this data is valuable for decision making. In order to use these data for the forecasting task, the conventional centralized approach has shown deficiencies regarding large data communication and data privacy issues. Furthermore, Neural Network models cannot make use of the extra information from the time series, thus they usually fail to provide time series specific results. Both issues expose a challenge to large-scale Time Series Forecasting with Neural Network models. All these limitations lead to our research question:Can we realize decentralized time series forecasting with a Federated Learning mechanism that is comparable to the conventional centralized setup in forecasting performance?In this work, we propose a Federated Series Forecasting framework, resolving the challenge by allowing users to keep the data locally, and learns a shared model by aggregating locally computed updates. Besides, we design a hybrid model to enable Neural Network models utilizing the extra information from the time series to achieve a time series specific learning. In particular, the proposed hybrid outperforms state-of-art baseline data-central models with NN5 and Ericsson KPI data. Meanwhile, the federated settings of purposed model yields comparable results to data-central settings on both NN5 and Ericsson KPI data. These results together answer the research question of this thesis.Tidseriedata har blivit allmänt förekommande tack vare överkomliga kantenheter och sensorer. Mycket av denna data är värdefull för beslutsfattande. För att kunna använda datan för prognosuppgifter har den konventionella centraliserade metoden visat brister avseende storskalig datakommunikation och integritetsfrågor. Vidare har neurala nätverksmodeller inte klarat av att utnyttja den extra informationen från tidsserierna, vilket leder till misslyckanden med att ge specifikt tidsserierelaterade resultat. Båda frågorna exponerar en utmaning för storskalig tidsserieprognostisering med neurala nätverksmodeller. Alla dessa begränsningar leder till vår forskningsfråga:Kan vi realisera decentraliserad tidsserieprognostisering med en federerad lärningsmekanism som presterar jämförbart med konventionella centrala lösningar i prognostisering?I det här arbetet föreslår vi ett ramverk för federerad tidsserieprognos som löser utmaningen genom att låta användaren behålla data lokalt och lära sig en delad modell genom att aggregera lokalt beräknade uppdateringar. Dessutom utformar vi en hybrid modell för att möjliggöra neurala nätverksmodeller som kan utnyttja den extra informationen från tidsserierna för att uppnå inlärning av specifika tidsserier. Den föreslagna hybrida modellen presterar bättre än state-of-art centraliserade grundläggande modeller med NN5och Ericsson KPIdata. Samtidigt ger den federerade ansatsen jämförbara resultat med de datacentrala ansatserna för både NN5och Ericsson KPI-data. Dessa resultat svarar tillsammans på forskningsfrågan av denna avhandling.
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Sundbrandt, Markus. "Control of a Ground Source Heat Pump using Hybrid Model Predictive Control." Thesis, Linköpings universitet, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71369.
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The thesis has been conducted at Bosch Thermoteknik AB and its aim is to develop a Model Predictive Control (MPC) controller for a ground source heat pump which minimizes the power consumption while being able to keep the inside air temperature and Domestic Hot Water (DHW) temperature within certain comfortintervals. First a model of the system is derived, since the system consists of both continuous and binary states a hybrid model is used. The MPC controller utilizes the model to predict the future states of the system, and by formulating an optimizationproblem an optimal control is achieved. The MPC controller is evaluated and compared to a conventional controller using simulations. After some tuning the MPC controller is capable of maintaining the inside air and DHW temperature at their reference levels without oscillating too much. The MPC controller’s general performance is quite similar to the conventional controller, but with a power consumption which is 1-3 % lower. A simulation using an inside air temperature reference which is lowered during the night is also conducted, it achieved a power consumption which was 7.5 % lower compared to a conventional controller.
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Huda, Shamsul. "Hybrid training approaches to Hidden Markov Model-based acoustic models for automatic speech recognition." Thesis, University of Ballarat, 2008. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/39435.
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Yu, Hsiang-Pai, and 游翔百. "Constructing Hybrid Credit Scoring Model." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/71398712783685563702.
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碩士國立交通大學
工業工程與管理系所
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Credit scoring is an essential task for banks and loan companies in the last few decades. The demand of developing a credit scoring model with reliable accuracy has become an urgent issue. Among many studies of credit scoring, artificial neural network (ANN) is a promising technique to achieve high accuracy of classification compared to existing conventional techniques. However, the poor explanation power makes ANN difficult to produce interpretable result. This drawback also decreases the power of ANN applied in practical problems. The objective of this study is to propose a hybrid credit scoring model which is combined with CART and other algorithms to enhance the accuracy of credit scoring model, and increase the interpretable capability as well. Financial loan companies can employ this study when establishing their credit scoring models.
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Ashrafullina, Ksenia. "Hybrid Model for Regulating Carbon." Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-278886.
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The objective of this dissertation is to review the instruments used to reduce carbon emissions, discuss the emission trading introduced by the European Emission Trading System and tentatively suggest further improvements. We shall look at carbon emissions as a negative externality and explore the theoretical foundations of carbon taxation and cap-and-trade systems as well as their possible interactions, conflicts and synergies. We shall also look at the risks associated with using carbon regulation in the ELI, mainly carbon leakage and lack of international compliance with regulatory mechanisms, especially in the developing countries. On a practical side, we shall focus on the structure and performance of the carbon reduction policies during the three phases - NAP1, NAP2 and NAP3, paying close attention to free allocation and auctioning. Finally we shall discuss risk-reduction methods, focusing on a potential hybrid model combining both cap-and-trade and taxation with a percentage of the revenues redistributed to the developing world to stimulate climate change agenda.
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Yang, Chih-Wei, and 楊智為. "A Hybrid Model of HO-IRT and HO-DINA Models." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/13533650739777251686.
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博士國立臺中教育大學
教育測驗統計研究所
102
In recent years, some higher-order item response theory (HO-IRT) models and higher-order DINA (HO-DINA) models were proposed. HO-IRT models can provide the overall ability and domain abilities estimators simultaneously. HO-DINA can provide the overall ability and cognitive diagnosis information in the same model. The purpose of this study is to develop a hybrid model of HO-IRT and HO-DINA models which is called multilevel DINA (ML-DINA). The first level is overall ability and the second level is domain abilities. The third level is cognitive attributes based on DINA model. The feasibility of the proposed model is investigated by a simulation study with variables (regression coefficients, number of subscales, sample sizes, item parameters). The major findings of this study are summarized as follows: 1. The overall ability, domain abilities, cognitive attributes, regression coefficients and item parameters, are estimated simultaneously in this model. 2. The accuracy of the estimates was relatively unaffected by the sample size. 3.The more accurate estimates of ML-DINA, when the regression coefficients were larger than 0.7. 4. Better estimates in both abilities scales can be obtained when more subscales were tested. 5.The higher quality of guessing and slip parameters brought about better item parameter estimation and classification accuracy. 6. The prior distribution associated with hierarchical structure were useful to increase the pattern correct classification rate.