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1
Colella, Vanessa Stevens. "Participatory simulations : building collaborative understanding through immersive dynamic modeling." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/61099.
Повний текст джерела
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VISCONTI, IGOR FERREIRA. "MEASUREMENT-BASED LOAD MODELING FOR DYNAMIC SIMULATIONS ON ELECTRIC POWER SYSTEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16417@1.
Повний текст джерелаАнотація:
CENTRO DE PESQUISA DE ENERGIA ELÉTRICA<br>Este trabalho descreve uma metodologia para modelagem de cargas
elétricas, utilizando dados de tensão e corrente registrados durante distúrbios no
sistema de potência. Estes modelos são utilizados na representação de subsistemas
da rede elétrica em simulações computacionais que preveem o comportamento
dinâmico do sistema de potência após perturbações em suas condições normais de
operação.São apresentados resultados práticos da metodologia proposta, onde a
carga é definida como um sistema cuja saída é a variação da potência consumida e
a entrada é a variação da tensão, ambas medidas em barramentos de 69 kV da
Companhia Hidroelétrica do São Francisco (CHESF), ponto de entrega de energia
para concessionárias distribuidoras de energia do nordeste brasileiro. Estas
distribuidoras são modeladas como cargas, supridas pelo sistema de transmissão
da CHESF e todos os elementos consumidores de energia são agregados nestes
modelos equivalentes, parametrizados para simular o maior número de
contingências típicas medidas em cada um destes barramentos de carga.A
técnica de estimação de parâmetros dos modelos de cargas é o Algoritmo
Genético (AG) cujos resultados apresentaram precisão para a simulação de
contingências de características bem distintas, caracterizando a abrangência
alcançada no processo de identificação de sistemas.Ao final do trabalho são
apresentadas curvas de desvios de potência ativa e reativa causadas por
afundamentos de tensão, ambos registrados nos barramentos das subestações da
CHESF. Estas curvas foram utilizadas para estimar os parâmetros dos modelos,
obtidos individualmente para cada uma das subestações estudadas.<br>This work describes a measurement-based load modeling methodology,
using voltage and current data registered during power system disturbances. These
load models are used on computational simulations for predicting power system
stability after disturbances of system operational points. Practical results are
presented of the proposed methodology, defining load as a system whose output is
power deviation from its operational state and input is voltage sags, both
measured at 69 kV bus bars of São Francisco Hydroelectric Company (CHESF),
points of common coupling (PCC) between CHESF and local distribution utilities.
Therefore, distribution utilities are seen as loads supplied by CHESF’s
transmission system. All devices consuming power from the PCC are aggregated
into an equivalent model, parameterized to simulate most typical contingencies
measured by these 69kV load bars. Optimization technique used for load model
parameter estimation is Genetic Algorithm (GA), showing his flexibility on
implementation and good coverage and accuracy in the final results. At the end, it
will be presented a set of active and reactive power curves during and after
voltages sags, measured on CHESF’s substations. These curves were used as
estimation data to parameterize load models for each substation chosen.
3
Li, Tianyi. "Gradient-damage modeling of dynamic brittle fracture : variational principles and numerical simulations." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX042/document.
Повний текст джерелаАнотація:
Une bonne tenue mécanique des structures du génie civil en béton armé sous chargements dynamiques sévères est primordiale pour la sécurité et nécessite une évaluation précise de leur comportement en présence de propagation dynamique de fissures. Dans ce travail, on se focalise sur la modélisation constitutive du béton assimilé à un matériau élastique-fragile endommageable. La localisation des déformations sera régie par un modèle d'endommagement à gradient où un champ scalaire réalise une description régularisée des phénomènes de rupture dynamique. La contribution de cette étude est à la fois théorique et numérique. On propose une formulation variationnelle des modèles d'endommagement à gradient en dynamique. Une définition rigoureuse de plusieurs taux de restitution d'énergie dans le modèle d'endommagement est donnée et on démontre que la propagation dynamique de fissures est régie par un critère de Griffith généralisé. On décrit ensuite une implémentation numérique efficace basée sur une discrétisation par éléments finis standards en espace et la méthode de Newmark en temps dans un cadre de calcul parallèle. Les résultats de simulation de plusieurs problèmes modèles sont discutés d'un point de vue numérique et physique. Les lois constitutives d'endommagement et les formulations d'asymétrie en traction et compression sont comparées par rapport à leur aptitude à modéliser la rupture fragile. Les propriétés spécifiques du modèle d'endommagement à gradient en dynamique sont analysées pour différentes phases de l'évolution de fissures : nucléation, initiation, propagation, arrêt, branchement et bifurcation. Des comparaisons avec les résultats expérimentaux sont aussi réalisées afin de valider le modèle et proposer des axes d'amélioration<br>In civil engineering, mechanical integrity of the reinforced concrete structures under severe transient dynamic loading conditions is of paramount importance for safety and calls for an accurate assessment of structural behaviors in presence of dynamic crack propagation. In this work, we focus on the constitutive modeling of concrete regarded as an elastic-damage brittle material. The strain localization evolution is governed by a gradient-damage approach where a scalar field achieves a smeared description of dynamic fracture phenomena. The contribution of the present work is both theoretical and numerical. We propose a variationally consistent formulation of dynamic gradient damage models. A formal definition of several energy release rate concepts in the gradient damage model is given and we show that the dynamic crack tip equation of motion is governed by a generalized Griffith criterion. We then give an efficient numerical implementation of the model based on a standard finite-element spatial discretization and the Newmark time-stepping methods in a parallel computing framework. Simulation results of several problems are discussed both from a computational and physical point of view. Different damage constitutive laws and tension-compression asymmetry formulations are compared with respect to their aptitude to approximate brittle fracture. Specific properties of the dynamic gradient damage model are investigated for different phases of the crack evolution: nucleation, initiation, propagation, arrest, kinking and branching. Comparisons with experimental results are also performed in order to validate the model and indicate its further improvement
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Akkinapragada, Nagasmitha. "Dynamic modeling and simulations of solid oxide fuel cells for grid-tied applications." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/final_copy1_09007dcc8031997c.pdf.
Повний текст джерелаАнотація:
Thesis (M.S.)--University of Missouri--Rolla, 2007.<br>Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 17, 2007) Includes bibliographical references (p. 77-80).
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Endale, Turie Samson. "Gas Turbine Plant Modeling for Dynamic Simulation." Thesis, KTH, Kraft- och värmeteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93897.
Повний текст джерелаАнотація:
Gas turbines have become effective in industrial applications for electric and thermal energy production partly due to their quick response to load variations. A gas turbine power plant is a complex assembly of a varietyof components that are designed on the basis of aero thermodynamiclaws. This thesis work presents model development of a single-shaft gas turbine plant cycle that can operate at wide range of load settings in complete dynamic GTP simulator. The modeling and simulation has been done in Dymola 7.3, based on the Modelica programming language. The gas turbine plant model is developed on component-oriented basis. This means that the model is built up by smaller model classes. With this modeling approach, the models become flexible and user-friendly for different plant operational modes. The component models of the main steady-state compressor and turbine stages have been integrated with gas plenum models for capturing the performance dynamics of the gas turbine power plant. The method of assembly used for gas turbine plant integration is based on models of the components from an engineering process scheme. In order to obtain an accurate description of the gas-turbine working principle, each component is described by a non-linear set of both algebraic and first-order differential equations. The thesis project provides descriptions of the mathematical equations used for component modeling and simulation. A complete dynamic simulation of a gas-turbine plant has been performed by connecting the complete plant model with PI controllers for both design and off-design operating modes. Furthermore, turbine blade cooling has been studied to evaluate the changes in power output. This has been done to compare and analyze the blade cooling effect.
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Engström, Jesper, Elias Richloow, and Anders Wickström. "Modeling of Robotic Hand for Dynamic Simulation." Thesis, KTH, Maskinkonstruktion (Inst.), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171991.
Повний текст джерелаАнотація:
KTHand is a robot hand designed within a doctoral thesis by Johan Tegin. KTHand is meant to be a simple construction, able to be produced for a low cost but still be functional thanks to feedback from tactile and position sensors. The mechanical construction of KTHand is based on three identical fingers, corresponding index finger, middle finger, and a thumb. Each finger consists of three movable links, called phalanges, connected by a leaf spring on the top. For the force actuation, a fishing line acting as a tendon is running through ducts in the phalanges. Each tendon is powered by a direct current motor in the hand, and this gives a finger three degrees of freedom (D.O.F.) with only one actuator, i.e. an under-actuated finger. To evaluate KTHand – simulations in the open-source software GraspIt! have been carried out. These simulations have been more or less successful, and a wish for simulation in another program has arisen. MSC ADAMS is a widely used and verified commercial program which is used for setting up advanced physical multibody simulations. ADAMS is fairly untested for the purpose of simulating robot hands and that is why it is of interest to see whether it is possible to successfully simulate the grasp dynamics of a robot hand, which is the topic for this thesis.As a starting point for the model design in ADAMS, a previously developed CAD model has been used since ADAMS provides the ability to import CAD files. To decrease the level of complexity, a number of simplifications have been done to the CAD model – unnecessary geometry such as screws and screw holes have been removed and curved lines in the geometry of the hand have been replaced by straight lines.After the simplified model was imported in ADAMS – joints, springs and contact conditions have been defined to obtain ranges of motion (R.O.M.) analogous to those of the physical prototype. To imitate the tendon which actuates a finger, a number of point forces have been defined. These point forces represent the reactive forces acting on the phalanges from the tendon. To perform a grasp simulation a number of different setups were used, each one with a different geometrical object to be grasped. Contact conditions between the hand and the objects were defined and the simulations were evaluated. The model can be used to simulate contact forces and how the hand interacts with different geometries. The conclusion of the simulations is that grasps based on shape give satisfying results while grasps based on friction force are of less accuracy. Friction conditions in ADAMS have turned out to be of low precision, and thus the grips based on friction become unrealistic.<br>KTHand är en robothand utformad inom en doktorsavhandling av Johan Tegin. KTHand är tänkt att vara en enkel konstruktion som ska kunna tillverkas för en låg kostnad samtidigt som den ska vara funktionell tack vare återkoppling av taktila givare och positionsgivare. KTHands mekaniska konstruktion är baserad på tre identiska fingrar, motsvarande pekfinger, långfinger och tumme. Varje finger är uppbyggt av tre rörliga länkar sammanfogade av en bladfjäder på ovansidan. Kraftstyrningen i ett finger utgörs av en fiskelina som löper genom hela fingret och får sin kraft av en likströmsmotor i handen. Detta ger ett finger med tre frihetsgrader aktuerat av en motor, alltså ett underaktuerat finger. För att utvärdera KTHand har simuleringar utförts i programmet GraspIt!. Dessa simuleringar har givit blandade resultat varför en önskan om simulering i annat program har uppkommit. MSC ADAMS är ett utbrett och välverifierat kommersiellt program som möjliggör avancerade fysikaliska flerkroppssimuleringar. ADAMS är dock ett tämligen oprövat program för just robothandssimulering och därför är det av intresse att utreda huruvida en robothands greppdynamik framgångsrikt kan simuleras i ADAMS och detta är ämnet som behandlas i den här rapporten. Sedan tidigare finns en utförlig CAD-modell av KTHand och denna har använts som utgångspunkt för modelluppbyggandet i ADAMS eftersom CAD-modeller kan importeras i detta program. För att bland annat minska komplexitetsnivån har den existerande CAD-modellen kraftigt förenklats på så vis att all, för ADAMS-modellen, onödig geometri som t.ex. skruvar och skruvhål har tagits bort. Vidare har även geometrin förenklats genom att kurviga kantlinjer har ersatts av raka dito. I ADAMS har leder och fjädrar definierats, rörelsetvång har införts genom att upprätta kontaktvillkor och kraftstyrning har lösts genom att införa krafter representerande de reaktionskrafter som uppkommer inne i fingrarna från den genomlöpande ”senan”. För att sedan simulera grepp har geometriska objekt skapats i ADAMS varefter kontaktvillkor definierats. Modellen kan användas för att simulera kontaktkrafter och hur handen interagerar med föremål av olika geometri. Slutsatsen av dessa simuleringar är att formbaserade grepp ger mer tillförlitliga resultat än friktionsbaserade grepp. Friktionsvilkoren i ADAMS har visat sig vara mindre tillförlitliga och på så sätt är de grepp som är starkt beroende av friktion ej verklighetstrogna.
7
Cooke, Joseph M. "NPSNET : flight simulation dynamic modeling using quaternions." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/27165.
Повний текст джерелаАнотація:
The Naval Postgraduate School (NPS) has actively explored the design and implementation of networked, realtime, three-dimensional battlefield simulations on low cost, commercially available graphics workstations. The most recent system, NPSNET, has improved in functionality to such an extent, that it is considered a low cost version of the Defense Advanced Research Project Agency's (DARPA) SIMNET system. In order to reach that level, it was necessary to economize in certain areas of the code so that real time performance occurred at an acceptable level. One of those areas was in aircraft dynamics. However, with 'off-the-shelf' computers becoming faster and cheaper, real-time and realistic dynamics are no longer an expensive option. The realistic behavior can now be enhanced through the incorporation of an aerodynamic model. To accomplish this task, a prototype flight simulator was built that is capable of simulating numerous types of aircraft simultaneously within a virtual world. Beside being easily incorporated into NPSNET, such a simulator will also provide the base functionality for the creation of a general purpose aerodynamic simulator that is particularly useful to aerodynamic students for graphically analyzing differing aircraft's stability and control characteristics. This system is designed for use on a Silicon Graphics workstation and uses the GL libraries. Computer Graphics, Animation, Simulation, Aerodynamics, Quaternions
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Harrell, Anthony F. "Molecular dynamic modeling and simulation for polymers." Thesis, Monterey, California. Naval Postgraduate School, 2012.
Знайти повний текст джерелаАнотація:
Approved for public release; distribution in unlimited.<br>Polymers have been widely used in various engineering applications. For more than a quarter century, the materials have been utilized intensively for the binding materials for composites. The material properties of the binding materials called matrix materials play an important role for the composite material behaviors. As a result, the objective of this study was to understand the mechanical properties of polymers. In particular, the goal was to develop insights as to how a molecular level structure is connected to the bulk properties of materials assuming homogeneity. To this end, molecular dynamics was used to model and simulate the polymeric behaviors. Polymeric chains were modeled using the bead and spring model along with interacting potentials. The study examined the effects of different sizes, densities, and numbers of molecules per chain on the shear moduli of the polymers. Furthermore, some preliminary study was also conducted for metallic particle reinforced polymer composites.
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Harrell, Anthony F. "Molecular dynamic modeling and simulation for polymers /." [United States] : Storming Media, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FHarrell.pdf.
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Nordbeck, Patric C. "Dynamics of Affordance Actualization." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504881864634251.
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Schmeißer, Andre [Verfasser]. "Contact Modeling Algorithms for Fiber Dynamics Simulations / Andre Schmeißer." München : Verlag Dr. Hut, 2016. http://d-nb.info/1115549960/34.
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Chakraborty, Sanjib. "Dynamic Modeling and Simulation of Digital Displacement Machine." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-85277.
Повний текст джерелаАнотація:
Improved efficiency, better controllability and low noise are the most demanding features form a displacement machine now-a-days. Most of the conventional displacement machines are basically a reciprocating pumping element controlled by valve plates or with the help of check valve [1]. This kind of hydraulic machines loose efficiency dramatically at partial displacement because all of the pistons remain at high pressure at the cycle time and due to pressure inside the piston leakage and shear losses increases. One approach to improve the efficiency of the displacement machine can be controlling each hydraulic piston by using programmable faster valves called digital valve. As the total displacement will be controlled digitally, the total system is called Digital Displacement Technology. In digital displacement machine it is possible to disconnect some of the pistons from the load and the piston will connect only with the low pressure side, minimizing losses due to leakage and shear. As the valve will control directly with digital controller it will eliminate the necessity of servo-hydraulic control required by conventional systems. Digital valves can open fully and close again with the input signal within one revaluation of the shaft, so it gives better control to the pumping element results reduction in hysteresis and increase the linearity of the pumping element. In Digital Displacement machines by controlling the valves pistons are connected with the machine when pressure is equal, but in the traditional machines piston connection was pre-determined with the shaft angle. By doing the piston control efficiency of the machine will improve and the sound generates for the decompression flow will be reduced [17]. Also energy storage and recovery can be possible by using accumulator.
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Siu, Daniel. "Stochastic Hybrid Dynamic Systems: Modeling, Estimation and Simulation." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4405.
Повний текст джерелаАнотація:
Stochastic hybrid dynamic systems that incorporate both continuous and discrete dynamics have been an area of great interest over the recent years. In view of applications, stochastic hybrid dynamic systems have been employed to diverse fields of studies, such as communication networks, air traffic management, and insurance risk models. The aim of the present study is to investigate properties of some classes of stochastic hybrid dynamic systems.
The class of stochastic hybrid dynamic systems investigated has random jumps driven by a non-homogeneous Poisson process and deterministic jumps triggered by hitting the boundary. Its real-valued continuous dynamic between jumps is described by stochastic differential equations of the It\^o-Doob type. Existing results of piecewise deterministic models are extended to obtain the infinitesimal generator of the stochastic hybrid dynamic systems through a martingale approach. Based on results of the infinitesimal generator, some stochastic stability results are derived. The infinitesimal generator and stochastic stability results can be used to compute the higher moments of the solution process and find a bound of the solution.
Next, the study focuses on a class of multidimensional stochastic hybrid dynamic systems. The continuous dynamic of the systems under investigation is described by a linear non-homogeneous systems of It\^o-Doob type of stochastic differential equations with switching coefficients. The switching takes place at random jump times which are governed by a non-homogeneous Poisson process. Closed form solutions of the stochastic hybrid dynamic systems are obtained. Two important special cases for the above systems are the geometric Brownian motion process with jumps and the Ornstein-Uhlenbeck process with jumps. Based on the closed form solutions, the probability distributions of the solution processes for these two special cases are derived. The derivation employs the use of the modal matrix and transformations.
In addition, the parameter estimation problem for the one-dimensional cases of the geometric Brownian motion and Ornstein-Uhlenbeck processes with jumps are investigated. Through some existing and modified methods, the estimation procedure is presented by first estimating the parameters of the discrete dynamic and subsequently examining the continuous dynamic piecewisely.
Finally, some simulated stochastic hybrid dynamic processes are presented to illustrate the aforementioned parameter-estimation methods. One simulated insurance example is given to demonstrate the use of the estimation and simulation techniques to obtain some desired quantities.
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Qiu, Fasheng. "A Framework for Group Modeling in Agent-Based Pedestrian Crowd Simulations." Digital Archive @ GSU, 2010. http://digitalarchive.gsu.edu/cs_diss/56.
Повний текст джерелаАнотація:
Pedestrian crowd simulation explores crowd behaviors in virtual environments. It is extensively studied in many areas, such as safety and civil engineering, transportation, social science, entertainment industry and so on. As a common phenomenon in pedestrian crowds, grouping can play important roles in crowd behaviors. To achieve more realistic simulations, it is important to support group modeling in crowd behaviors. Nevertheless, group modeling is still an open and challenging problem. The influence of groups on the dynamics of crowd movement has not been incorporated into most existing crowd models because of the complexity nature of social groups. This research develops a framework for group modeling in agent-based pedestrian crowd simulations. The framework includes multiple layers that support a systematic approach for modeling social groups in pedestrian crowd simulations. These layers include a simulation engine layer that provides efficient simulation engines to simulate the crowd model; a behavior-based agent modeling layers that supports developing agent models using the developed BehaviorSim simulation software; a group modeling layer that provides a well-defined way to model inter-group relationships and intra-group connections among pedestrian agents in a crowd; and finally a context modeling layer that allows users to incorporate various social and psychological models into the study of social groups in pedestrian crowd. Each layer utilizes the layer below it to fulfill its functionality, and together these layers provide an integrated framework for supporting group modeling in pedestrian crowd simulations. To our knowledge this work is the first one to focus on a systematic group modeling approach for pedestrian crowd simulations. This systematic modeling approach allows users to create social group simulation models in a well-defined way for studying the effect of social and psychological factors on crowd’s grouping behavior. To demonstrate the capability of the group modeling framework, we developed an application of dynamic grouping for pedestrian crowd simulations.
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Rao, Dhananjai M. "Study of Dynamic Component Substitutions." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1060366173.
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Call, Anson Jay. "Dynamic modeling and simulation of a snake-like robot." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/19523.
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Shim, Hyunju. "An xml-based diagrammatic dynamic modeling and simulation system." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000950.
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McKenna, Kyra Patricia. "Real-time interactive dynamic mesh modeling : laparoscopic surgical simulation." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492022.
Повний текст джерелаАнотація:
This thesis presents the results of research into interactive deformable mesh modeling for the purposes of simulating organ tissue. The research was based on developing a deformable model applicable to the development a low cost laparoscopic surgical simulator with a minimally specified hardware configuration. Modeling a dynamic deformable mesh involved developing the following key components: a physical algorithmic model to controls model deformation, real-time collision detection and response, mesh adaptation, mesh cutting and tool-organ interaction. For this research work, the components were developed and implemented to create a basic experimental surgical simulator. The components involve novel implementations and optimizations features and results demonstrate their application to model defonnable real-time interactive mesh.
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Hilbig, Travis. "Scratch Modeling of Polymeric Materials with Molecular Dynamics." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc149608/.
Повний текст джерелаАнотація:
It is impossible to determine the amount of money that is spent every replacing products damaged from wear, but it is safe to assume that it is in the millions of dollars. With metallic materials, liquid lubricants are often used to prevent wear from materials rubbing against one another. However, with polymeric materials, liquid lubricants cause swelling, creating an increase in friction and therefore increasing the wear. Therefore, a different method or methods to mitigate wear in polymers should be developed. For better understanding of the phenomenon of wear, scratch resistance testing can be used. For this project, classic molecular dynamics is used to study the mechanics of nanometer scale scratching on amorphous polymeric materials. As a first approach, a model was created for polyethylene, considering intramolecular and intermolecular interactions as well as mass and volume of the CH2 monomers in a polymer chain. The obtained results include analysis of penetration depth and recovery percentage related to indenter force and size.
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Wu, Han. "Dislocation Dynamics Simulations of Plasticity in Cu Thin Films." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc500046/.
Повний текст джерелаАнотація:
Strong size effects in plastic deformation of thin films have been experimentally observed, indicating non-traditional deformation mechanisms. These observations require improved understanding of the behavior of dislocation in small size materials, as they are the primary plastic deformation carrier. Dislocation dynamics (DD) is a computational method that is capable of directly simulating the motion and interaction of dislocations in crystalline materials. This provides a convenient approach to study micro plasticity in thin films. While two-dimensional dislocation dynamics simulation in thin film proved that the size effect fits Hall-Petch equation very well, there are issues related to three-dimensional size effects. In this work, three-dimensional dislocation dynamics simulations are used to study model cooper thin film deformation. Grain boundary is modeled as impenetrable obstacle to dislocation motion in this work. Both tension and cyclic loadings are applied and a wide range of size and geometry of thin films are studied. The results not only compare well with experimentally observed size effects on thin film strength, but also provide many details on dislocation processes in thin films, which could greatly help formulate new mechanisms of dislocation-based plasticity.
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Karatas, Soner. "Leo Satellites: Dynamic Modelling, Simulations And Some Nonlinear Attitude Control Techniques." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607196/index.pdf.
Повний текст джерелаАнотація:
In this thesis nonlinear control method techniques are investigated to control the attitude of Low Earth Orbit satellites. Nonlinear control methods are compared with linear control methods. Simulations are done using Matlab and Simulink software and BILSAT-1 parameters are used in the simulations. Reaction wheels are used as the actuator.
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Dallaire, Jonathan. "Thermal conductivity of carbon nanotubes from equilibrium molecular dynamics simulations : sensitivity to modeling and simulation parameters." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29017/29017.pdf.
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Vajre, Chetan D. "Modeling Dynamic Interactions in a Software Development Project." [Tampa, Fla. : s.n.], 2003. http://purl.fcla.edu/fcla/etd/SFE0000096.
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Bånkestad, Maria. "Modeling, Simulation and Dynamic control of a Wave Energy Converter." Thesis, KTH, Numerisk analys, NA, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134104.
Повний текст джерелаАнотація:
The energy in ocean waves is a renewable energy resource not yet fully exploited. Research in converting ocean energy to useful electricity has been ongoing for about 40 years, but no one has so far succeed to do it at sufficiently low cost. CorPower Ocean has developed a method, which in theory can achieve this. It uses a light buoy and a control strategy called Phase Control. The purpose of this thesis is to develop a mathematical model of this method - using LinearWave Theory to derive the hydrodynamic forces - and from the simulated results analyze the energy output of the method. In the process we create a program that will help realizing and improving the method further. The model is implemented and simulated in the simulation program Simulink. On the basis of the simulated results, we can concludes that the CorPower Ocean method is promising. The outcome shows that the energy output increases - up to five times- compared to conventional methods.<br>Vågenergi är en förnyelsebar energikälla som ännu inte utnyttjas fullt ut. Forskning inom konvertering av vågenergi till användbar elektricitet har pågått i cirka 40 år, men ingen har hittills lyckas att göra det tillräckligt kostnadseffektivt. CorPower Ocean har utvecklat en metod, som i teorin kan uppnå detta. De använder en lätt boj och en kontrollstrategi kallad Phase Control. Syftet med detta examensarbete är att utveckla en matematisk modell av metoden -genom att använda Linear Wave Theory för att härleda de hydrodynamiska krafterna -och från de simulerade resultaten analysera energiutbytet. Under arbetets gång skapades också ett simuleringsprogram som hjälpmedel till att realisera och förbättra metoden. Modellen implementeras och simuleras i programmet Simulink. Utifrån de simulerade resultaten kan vi dra slutsatsen att CorPower Oceans metod är lovande. Resultatet visar att energiutbytet ökar -upp till fem gånger - jämfört med konventionella metoder.
25
Tinker, Matthew Michael. "Wheel loader powertrain modeling for real-time vehicle dynamic simulation." Thesis, University of Iowa, 2006. http://ir.uiowa.edu/etd/75.
Повний текст джерела
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ALBUQUERQUE, GIL RUDGE CAVALCANTI DE. "MODELING AND SIMULATION OF THE DYNAMIC OF SURFACE MOORED BUOYS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=13395@1.
Повний текст джерелаАнотація:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>Um método para a simulação dinâmica bi-dimensional de bóias cilíndricas
de superfície, sujeitas à ação de ondas e ancorada ao fundo marinho através de
uma linha flexível é apresentado neste trabalho. O modelo de elementos finitos
adotado por Lustosa (2002) é empregado na descrição do movimento do cabo de
ancoragem, onde elementos de vigas de Euler-Bernoulli de dois nós são
empregados, com a cinemática do movimento descrita através de grandezas
referidas ao sistema local co-rotacionado. No modelo numérico, são consideradas
as não-linearidades geométricas resultantes dos grandes deslocamentos da linha e
que causam o acoplamento das rigidezes axial e flexional. Na caracterização do
movimento da linha consideram-se os seguintes efeitos: peso próprio, empuxo,
carregamento hidrodinâmico da correnteza marinha, deslocamentos impostos pela
unidade flutuante, forças de inércia e, se presente, a ação de flutuadores. Os
deslocamentos do cabo são obtidos da solução do sistema algébrico de equações
não-lineares, resultante da integração temporal de Newmark das equações
diferenciais temporais do movimento, cuja convergência é garantida através do
método iterativo de Newton-Raphson. Para a bóia, considerada para efeito de
análise como indeformável, três graus-de-liberdade são considerados: dois de
deslocamentos lineares e um de deslocamento angular. As ondas de superfície,
monocromáticas e bi-dimensionais, são representadas no modelo através da teoria
linear de Airy associada à modificação empírica de Wheeler (Wheeler, 1969).
Forças resultantes da ação das ondas sobre a bóia de superfície são obtidas através
da integração numérica da equação proposta por Chitrapu et al. (1998) que
compõe-se de um termo viscoso - resultante da parcela de arrasto da equação de
Morison - e de um termo não-viscoso - considerado como resultante da soma da
força de Froude-Krylov (Chakrabarti, 1987) à parcela de inércia da equação de
Morison -. A integração numérica desta equação sobre a superfície “molhada”
instantânea do cilindro é realizada, a cada incremento de tempo da análise,
empregando-se o método da quadratura adaptativa de Simpson. Finalmente, na
integração temporal das equações de movimento da bóia de superfície utiliza-se o
método de Runge-Kutta de quinta ordem, com o controle adaptável do passo
temporal. O procedimento descrito foi implementado em um programa de
computador e os resultados obtidos de algumas análises numéricas comparados
com os fornecidos por outras simulações independentes, de forma a verificar a
adequabilidade da formulação proposta no estudo da dinâmica de bóias flutuantes.<br>In this work a method for two-dimensional dynamic analysis of a cylindrical
buoy under surfaced waves and moored to the seafloor by a flexible riser is
presented. The finite element model used to describe the dynamics of the maritime
line was developed by Lustosa (2002). This is a two node beam element based on
the Euler-Bernoulli theory, with the element kinematics referred to a co-rotacional
coordinate system attached to the element. The model considers the representation
of geometric non-linearities due to the line motion large displacements resulting in
axial-bending couplings in the element total stiffness representation. The element
displacements in the line are due to the following external loadings: self weight,
buoyancy force, hydrodynamic forces due to maritime currents, surface buoy
imposed displacements, the forces of inertia, and, if present, the action of floaters.
The buoy two displacements and one rotation degrees-of-freedom are measured at
its center of gravity and are obtained from the solution of the non-linear algebraic
system resulting from the Newmark temporal integration of the differential
equations of motion, which solution convergence is granted by a Newton-
Rapshon iterative method. The linear wave theory - Airy Theory -, associated to
the Wheeler empirical modification, is used in this work to represent the
monochromatic bi-dimensional surface waves. To obtain the wave forces acting
on the surface buoy while in motion, the numerical integration of the equation
presented by Chitrapu et al. (1998) is employed. This is the result of a two part
equation: the first is evaluated as the Morison viscous drag force and, in a second
part, is the sum of the - Froude-Krylov - and the Morison inertia forces. The
numerical integration of the resulting equation is evaluated over the instantaneous
wet surface of the buoy, in each time-step, using the adaptive recursive Simpson´s
method. Finally the temporal integration of the buoy equations of motion are
evaluated using a fifth-order Runge-Kutta method, with an adaptive control of the
temporal time step. This procedure has been implemented in a computer program
and the results obtained from some numerical analysis are compared to the ones
obtained from independent simulations, so as to verify the ability of this proposed
method to describe the dynamic of floating buoys.
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TIEN, JOAO MIGUEL TRUONG DINH. "DYNAMIC OF ONE-DIMENSIONAL VISCOELASTIC STRUCTURES: MODELING AND NUMERICAL SIMULATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1985. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33512@1.
Повний текст джерелаАнотація:
COMISSÃO NACIONAL DE ENERGIA NUCLEAR<br>No presente trabalho são introduzidas considerações sobre modelos constitutivos viscoelasticos e suas formulações. É apresentada uma teoria de estruturas uni-dimensionais imersas no espaço tri-dimensional, a partir de uma formulação diferencial, permitindo-se a análise de problemas no contexto de
grandes deformações.(caracteristicas não-lineares). Adota-se uma lei constitutiva viscoelastica linear, sob forma diferencial. São resolvidos três problemas planos que caracterizam a aplicação do modelo proposto: 1) Viga reta engastada submetida em sua extremidade livre a uma força não-seguidora compressiva cuja direção coincide com a do eixo longitudinal da viga na configuração indeformada. 2) Viga curve bi-rotulada com ambas as extremidades Fixas carregada uniformemente. 3) Viga reta engastada submetida em sua extremidade livre a uma força cíclica perpendicular ao eixo longitudinal da viga na configuração indeformada. Nos dois primeiros problemas é adotada a hipótese quasi-estatica, conservando a influência da inercia apenas no terceiro problema quando é feito um estudo comparativo entre o modelo elástico e o viscoelástico. São propostos os métodos numéricos de solução para os casos viscoelásticos quasi-estáticos - baseados num acoplamento do Método do Tiro (Runge-Kutta de Quarta ordem / Steffensen); considerando o problema espacial, e de Euler Modificado; na evolução temporal - e para o caso dinâmico, valendo-se da aproximação de diferenças finitas para avaliar as velocidades e acelerações.<br>In the present work, considerations about viscoelastic cosntitutive models and their formulations are introduced. A theory of unidimensionail structures embeded in the tri-dimensional space is presented in a differential formula, allowing the analysis of problems in the large deformations point of view. A linear viscoelastic consitutive law is adopted in a differential representation. Three plane problems which characterize the application of the proposed model are solved: 1) Straight cantilever subjected, at the free end, to a compressive non follower force. The direction of this force coincides with the longitudinal axis of the beam at the undeformed configuration; 2) Curved bean with fixed supports at the ends, under
uniform charge. 3) Straight cantilaver subjected at the free end to a cyclic force, perpendicularly to the longitudinal axis of the beam at the undeformed confiquration. In the two first problems; the quasistatic hypothesis is adopted the inertial influence being considered only at the third problems, where a comparative study between the elastic and the viscoelastic models is carried out. The numerical methods for the solution in the quasistatic viscoelastic cases are proposed - based in a coupling between the shooting method (Runge-Kutta of fourth order/Steffensen) for the spatial problem and the Modified Euler Method for the temporal evolution - as well as for the solution of the dynamical case - employing an approximation by finite differences for the evaluations of the velocities and accelerations.
28
Rothenhöfer, Gerald S. (Gerald Sven). "Design, dynamic modeling, simulation and feedback control of hydrostatic bearing." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39888.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.<br>Includes bibliographical references (p. 113).<br>A hydrostatic bearing carriage (Hydrocline) that uses an open face linear motor to drive the carriage as well as to preload the hydrostatic bearings has been developed by Professor Alexander Slocum and Gerald Rothenhöfer of the Massachusetts Institute of Technology's Mechanical Engineering Department. The Hydrocline is made to cope with the increasing requirements for accuracy in silicon wafer grinding machines. The prototype was built of aluminum oxide ceramic due to its high stiffness-to-weight ratio, low thermal expansion and corrosion resistance. In order to keep the cost of manufacturing as low as possible, a modular design that uses micron-level precision ceramic beams was chosen. Initial testing of the prototype carriage indicates that it has the following performance specifications: a vertical load capacity exceeding 5000N (theoretical limit at 12000N, max. pressure of pumps); a carriage pitch error of 0.7arc seconds; a yaw error of 0.7arc seconds; a roll error of +/- 0.6arcsec a vertical straightness at the center of the carriage of +/-0.75microns; and a vertical stiffness of the carriage of 900N per micron (load range from 0 to 1000N).<br>(cont.) A dynamic model of the hydrostatic bearing and fluid supply system has been developed and accurately predicts the performance of the Hydrocline. The model has been used to simulate a feedback control loop that adjusts the bearing supply flow such that changes in load can be compensated and theoretically infinite stiffness can be reached. In first experiments on a specially designed test setup the measured static stiffness of the single pocket test bearing could be increased by a factor 8 (load range 45 to 270N). The dynamic stiffness of the bearing could be increased by a factor of 2.5.<br>by Gerald S. Rothenhöfer.<br>S.M.
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Kittivatcharapong, S. "A dynamic simulation of a quadruped with impulsive collision modeling /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487853913100029.
Повний текст джерела
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Chatelier, Adrien. "Modeling questions for numerical simulations of aeronautical combustors." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC061/document.
Повний текст джерелаАнотація:
La conception de chambres de combustion aéronautiques requiert un compromis entre les différents phénomènes physiques présents, comme les interactions entre la flamme et la turbulence, les pertes thermiques, la dynamique de flamme ou l'évaporation du carburant et son mélange. De nombreux outils numériques existent dans la littérature pour prédire ce genre d'écoulements réactifs turbulents. Les modèles de turbulence instationnaires, par exemple LES (Large Eddy Simulation), sont un excellent compromis pour la prédiction du mélange dans des configurations réalistes. L'approche de chimie tabulée représente un équilibre attrayant entre coût de calcul et précision pour la prédiction de structure de flamme. Dans cette thèse, des modèles de turbulence avancés et de chimie tabulée sont appliqués à des configurations complexes afin d'évaluer leur capacité à prédire la structure de flammes turbulentes. La prédiction de la FDF (Flame Describing Function) par le modèle F-TACLES (Filtered TAbulated Chemistry for Large Eddy Simulations) est comparé à des données expérimentales pour une flamme swirlée, prémélangée et non-adiabatique. La FDF est bien prédite pour une large plage de fréquences et deux niveaux de fluctuations de vitesse. L'origine des différences est analysée. La première application du modèle F-TACLES à un brûleur diphasique est proposée. Le brûleur choisi est la flamme jet diphasique KIAI, récemment étudié au CORIA. Une comparaison détaillée avec l'expérience est faite et montre que F-TACLES est capable de prédire la bonne forme de flamme. Le modèle ZDES (Zonal Detached Eddy Simulation) est étudié dans la configuration TLC, un injecteur aéronautique réaliste. En non-réactif, la ZDES est validée par rapport aux mesures de vitesse expérimentales et comparée à des résultats de LES. En conditions réactives, la prédiction des profils de température dans la chambre de combustion est grandement améliorée en ZDES<br>The design of aeronautical combustion chambers requires a precise balance between the different physical phenomena involved, such as flame-turbulence interaction, heat losses, flame dynamics or fuel evaporation and mixing. Numerous numerical tools exist in the literature to predict these kinds of turbulent reacting flows. The unsteady turbulence models, for example LES (Large Eddy Simulation), represent an excellent compromise for the prediction of the mixing in realistic configurations. The tabulated chemistry approach is an attractive trade-off between computation cost and accuracy for predicting the structure of flames. In this thesis, advanced turbulence and tabulated chemistry models are applied to complex configurations in order to assess their ability to predict the structure of turbulent flames. The prediction of the FDF (Flame Describing Function) by the F-TACLES (Filtered TAbulated Chemistry for Large Eddy Simulations) model is compared to experimental data for a non-adiabatic premixed swirled flame. The FDF is well predicted for a wide range of frequencies and two velocity fluctuation levels. The origin of the discrepancies is analyzed. The first application of the F-TACLES model in a two-phase burner is proposed. The chosen burner is the KIAI spray jet flame, recently studied at CORIA. A detailed comparison with the experiments is performed and shows that F-TACLES is able to predict the correct flame shape. The ZDES (Zonal Detached Eddy Simulation) model is studied in a realistic aeronautical injector, the TLC configuration. In cold conditions, the ZDES is validated against velocity measurements and compared to LES results. In reacting conditions, the prediction of temperature profiles in the combustion chamber is greatly improved in the ZDES
31
Jones, Philip Edward James. "Evaluation of water distribution system monitoring using stochastic dynamic modeling." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/40441.
Повний текст джерелаАнотація:
A stochastic dynamic constituent transport model was developed, capable of simulating the operation of a water distribution system containing pumps and storage tanks, and subject to random demands and contaminant inputs. Long term operation of a hypothetical small town water supply system containing one pump station and one storage tank was simulated while the system was subjected to external contaminant inputs. Repeated simulations were made under different regimes of external contamination applied to the tank, the pump station and at system nodes, and internal contamination representing biofilm effects based on assumed relationships between flow velocities and bioflim cell detachment. Seven sampling plans representing regulatory requirements and industry practice were applied during the simulation to evaluate their ability to detect the contamination under a presence/absence criterion.
The simulations were able to identify contamination patterns and provide information useful in the definition of sampling plans. Time of sampling was found to be as important as location. This was true both within the monitoring period, and particularly within the diurnal cycle of demand. Spreading samples over different days within the monitoring period rather than sampling all on one day, always improved contaminant detection. Detection by plans based on fixed times and locations were very sensitive to those times and locations.
There was no best plan suitable for all situations tested. The better sampling plans were those that captured the temporal and spatial contamination patterns present in the system. No consistent advantage was noted from sampling in proportion to population served or in locating sampling nodes systematically instead of randomly. The location and timing of sampling for most plans could be improved with the knowledge of actual contamination patterns and timing provided by the model.
The presence of a storage tank was found to have a strong influence on hydraulic patterns and the location and timing of contamination reaching different parts of the system.<br>Ph. D.
32
Gbetchi, Kokouvi. "Multi-scale modeling of thermo-mechanical dynamic damage in quasi-brittle materials." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0049.
Повний текст джерелаАнотація:
Sous l’effet des impacts mécaniques, les structures constituées de matériaux fragiles peuvent être exposés à la rupture dynamique. La modélisation appropriée des mécanismes de rupture à différentes échelles d’observation et la prédiction de l’endommagement thermomécanique dans ces matériaux sont essentielles pour la conception de structures fiables. Des observations expérimentales sur la rupture dynamique des matériaux fragiles montrent des effets de refroidissement et d’échauffement importants à proximité d’une pointe de fissure. La modélisation du couplage thermomécanique lors de la rupture fragile a été entreprise, en général, sans tenir compte des aspects microstructuraux. L’objectif de cette thèse est de développer une procédure pour obtenir des lois d’endommagement thermomécaniques dans lesquelles l’évolution de l’endommagement est déduite à partir de la propagation des microfissures et des effets thermiques associés à l’échelle petite du matériau. Nous utilisons la méthode d’homogénéisation asymptotique pour obtenir la réponse macroscopique thermomécanique et d’endommagement du solide. Pour la propagation des microfissures, en mode I ou II, un critère de type Griffith est adopté. Des sources de chaleur sont considérés aux pointes des microfissures en mouvement, en lien avec l’énergie dissipée pendant la propagation. Nous considérons aussi des sources de chaleur représentant la dissipation par frottement sur les lèvres des microfissures qui se propagent en mode de cisaillement. Grâce à une analyse énergétique combinée avec la méthode d’homogénéisation nous obtenons des lois d’endommagement macroscopiques. Dans le système thermoélastique et d’endommagement ainsi obtenu, on identifie de forts couplages entre les champs mécaniques et thermiques. Le calcul des coefficients effectifs nous a permis d’étudier la réponse locale prédite par les nouveaux modèles. Cette réponse montre des effets de vitesse de déformation, de taille de la microstructure, de dégradation des propriétés thermoélastiques et des évolutions thermiques spécifiques engendrées par la microfissuration et le frottement à l’échelle petite du matériau. Dans l’équation macroscopique de la température, on retrouve des termes sources de chaleur distribuées en lien avec les dissipations d’endommagement et de frottement. L’implémentation de modèles d’endommagement dans un logiciel d’éléments finis nous a permis d’effectuer des simulations numériques à l’échelle des structures. Nous avons reproduit numériquement certains tests expérimentaux publiés dans la littérature concernant la rupture rapide d’échantillons de PMMA sous sollicitation d’impact. Les résultats des simulations obtenus sont en bon accord avec les observations expérimentales<br>Under impact mechanical loadings, structural components made of brittle materials may be exposed to dynamic failure. The appropriate modeling of the failure mechanisms at different scales of observation and the prediction of the corresponding thermomechanical damage evolution in such materials is essential for structural reliability predictions. Experimental observations on dynamic failure in brittle materials report important cooling and heating effects in the vicinity of the crack tip. Theoretical modeling of the thermo-mechanical coupling during fracture have been generally undertaken without accounting for microstructural aspects. The objective of the present thesis is to develop a procedure to obtain macroscopic thermo-mechanical damage laws in which the damage evolution is deduced from the propagation of microcracks and the associated small-scale thermal effects in the material. We use the asymptotic homogenization method to obtain the macroscopic thermo-mechanical and damage response of the solid. A Griffith type criterion is assumed for microcracks propagating in modes I or II. Heat sources at the tips of microcracks are considered as a consequence of the energy dissipated during propagation. Frictional heating effects are also considered on the lips of microcracks evolving in the shear mode. An energy approach is developed in combination with the homogenization procedure to obtain macroscopic damage laws. The resulting thermoelastic and damage system involves strong couplings between mechanical and thermal fields. Computation of the effective coefficients allowed us to study the local response predicted by the new models. The macroscopic response exhibits strain-rate sensitivity, microstructural size effects, degradation of thermoelastic properties and specific thermal evolutions due to microcracking and frictional effects at the small scale. Distributed heat sources are present in the macroscopic temperature equation linked to damage and frictional dissipations. The implementation of the proposed damage models in a FEM software allowed us to perform numerical simulations at the structural level. We reproduced numerically experimental tests reported in the literature concerning the rapid failure of PMMA samples impact. The results obtained in the simulations are in good agreement with the experimental observations
33
Ball, George LeRoy. "A spatial dynamic approach to ecological modeling: Simulating fire spread." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/184986.
Повний текст джерелаАнотація:
The objective of this dissertation is to develop a new research tool, PROMAP, which will allow the construction of models that satisfy the requirement of spatial distribution and hierarchical interactions within a dynamic framework. An analysis of the form of ecosystems is followed by an examination of current attempts at ecosystem modeling using spatial relationships. An examination of the analytical procedures used in the spatial modeling process, results in a set of criteria that a suitable modeling system should incorporate. These criteria are: the use of real numbers; iterative processing; flexible data retrieval; and neighborhood analytical procedures. The basic configuration of PROMAP is discussed with an emphasis on the mathematical procedures and the capability for designing cellular automata within the system. The representation of biophysical systems into a set of spatial transition functions is described in relation to the development of nested hierarchies called Q-morphisms. Having established the design of PROMAP, a suitable test is devised using the simulation of surface fire spread. A model called FIREMAP is developed and the results are compared to expected fire shapes under Zero State Conditions. These conditions are defined as uniform fuel, zero slope and zero wind with additional factors held constant. Other simulations of fire spread are made by relaxing the conditions to achieve wind driven fires and the response to potential impediments to fire spread. The response of the simulation shows an accurate correspondence between the simulation and the expected fire shape. As a final test of the model, all restrictions are removed and a simulation is made under actual conditions of complex terrain, and non-uniform fuels using data collected on the San Carlos Apache Indian Reservation in southeast Arizona. Deficiencies of PROMAP and FIREMAP are discussed as well as future implications for the FIREMAP model as a management tool.
34
Mariotte, Guilhem. "Dynamic Modeling of Large-Scale Urban Transportation Systems." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSET010/document.
Повний текст джерелаАнотація:
La congestion en milieu urbain est un enjeu majeur que ce soit d’un point vue économique, social ou environnemental. À court et moyen terme, l’utilisation de la simulation dynamique du trafic routier peut permettre d’analyser et de guider des politiques d’optimisation des infrastructures existantes. Aujourd’hui, du fait de la complexité des systèmes de transport, les outils de modélisation classiques sont limités à des échelles géographiques peu étendues (de l’ordre du quartier). À grande échelle, le temps de calcul devient rapidement un facteur limitant tout comme le calibrage et la scénarisation. Néanmoins les dernières décennies ont vu l’apparition d’une nouvelle génération de modèles bien adaptés aux métropoles urbaines. Ceux-ci sont basés sur une relation phénoménologique entre la production de déplacements et le nombre de véhicules dans une zone spatiale d’un réseau routier, appelée Diagramme Fondamental de Zone (Macroscopic Fundamental Diagram, MFD). Cette relation, validée empiriquement sur de nombreuses villes, a permis d’étudier différentes méthodes de contrôle du trafic pour une ville entière, mais a été peu utilisée à des fins de prévision de la congestion. L’objectif de cette thèse est de proposer un premier outil opérationnel de simulation et d’analyse des grands réseaux de métropoles, en utilisant et développant les modèles de trafic basés sur la relation MFD. Cet outil doit posséder un cadre théorique cohérent qui puisse convenir à des applications telles que la prévision d’états de trafic, le développement de nouvelles politiques de contrôle, l’estimation de pollutions liées au trafic, etc. Les contributions de la thèse portent sur deux aspects. Le premier est l’analyse des propriétés mathématiques et physiques des modèles existants, en incluant une formalisation complète de la gestion de plusieurs longueurs de parcours au sein d’une même zone urbaine. En particulier, cette formalisation traite de la distinction des trajets internes à la zone et des problèmes de flux convergents et divergents pour les trajets traversant la zone lorsque la congestion se propage d’une zone à l’autre. Le deuxième aspect est la proposition d’un nouveau modèle basé sur la distance individuelle parcourue à l’intérieur d’une zone urbaine (trip-based). Cette approche permet d’individualiser les usagers (auparavant représentés sous forme de flux continus) et donc de définir plus finement leurs caractéristiques, en vue de coupler leurs déplacements à des modèles d’affectations sur différentes routes. Enfin, des exemples d’application illustrant diverses collaborations sont donnés en dernière partie de la thèse. La simulation du trafic sur l’aire urbaine du Grand Lyon (France) y est présentée, ainsi que de nouveaux modules de modélisation de la recherche de parking ou de contrôle périphérique. Cette thèse est partie intégrante d’un projet européen ERC intitulé MAGnUM : Approche multi-échelle et multimodale de la modélisation du trafic pour une gestion durable de la mobilité urbaine<br>Congestion in urban areas has become a major issue in terms of economic, social or environmental impact. For short or mid term, using dynamic road traffic simulation can help analyzing and providing guidelines to optimization policies of existing infrastructures. Today, because of the complexity of transport systems, classical modeling tools are limited to small geographical areas (of a district size). Computational time, together with simulation calibration, are notably very constraining at large scales. However, a new generation of models designed for metropolitan areas has arisen over the past decades. These models are based on a phenomenological relationship between travel production and the number of vehicles in a given spatial area of a road network, known as the Macroscopic Fundamental Diagram (MFD). This relationship, supported by empirical evidences from several cities around the world, has allowed the study of different traffic control schemes at a whole city scale, but was rarely used for traffic state forecasting. The aim of this PhD is to propose an efficient modeling tool, based upon the concept of MFD, to simulate and analyze traffic states in large metropolitan areas. The theoretical framework of this tool must be consistent and applicable for traffic state forecasting, development of new control policies, traffic emission estimation, etc. There are two major contributions in this PhD. The first one is analyzing the mathematical and physical properties of existing models, and formalizing the dynamics of several trip lengths inside the same urban zone. In particular, this formalization distinguishes between internal trips and trips crossing the zone. Flow merging and diverging issues are also addressed when congestion propagates from one zone to another. The second contribution is proposing a new trip-based model based on individual traveled distance. This approach allows to treat users independently (previously represented with continuous flows), and thus to define their characteristics more precisely to couple their trips with assignment models on different paths. Finally, examples of application from various collaborations are given in the last part of this thesis. It includes a simulation study of the Grand Lyon urban area (France), as well as new modules to simulate search-for-parking or perimeter control. This PhD is part of a European ERC project entitled MAGnUM: Multiscale and Multimodal Traffic Modeling Approach for Sustainable Management of Urban Mobility
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Fonseca, James E. "Temporal and Steric Analysis of Ionic Permeation and Binding in Na+,K+-ATPase via Molecular Dynamic Simulations." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1210868607.
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Nosek, Michael. "Modeling helicopter dynamic loads using artificial neural networks." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-08182009-040457/.
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Shukeir, Malik. "Modeling of irradiation effect on the plasticity of alpha-Iron using dislocation dynamics simulations : plasticity through multi-scale modeling." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS363.
Повний текст джерелаАнотація:
Ce travail vise à reproduire les interactions individuelles entre les dislocations vis et les boucles induites par l'irradiation en utilisant les simulations de dynamique des dislocations en accord avec les simulations de dynamique moléculaire. Un tel accord se caractérise par la reproduction de la réaction et avoir un valeur des contraintes critiques résolues pour franchir les obstacles. Cette approche fournit le moyen de calibrer notre code de dynamique des dislocations avec les paramètres des simulations de dynamique moléculaire. Par conséquent, il permet d'effectuer des simulations massives à l'échelle mésoscopique. Dans ce cadre, ce travail se compose de deux parties, une identification du modèle énergétique et une identification des mécanismes élémentaires. Dans la première partie, nous proposons une procédure de calibrage de la tension ligne basée sur le mécanisme d'Orowan en utilisant une étude de sensibilité. Dans la deuxième partie, nous avons identifié les mécanismes de glissement dévié et le maclage/antimaclage comme étant essentiels pour reproduire les interactions individuelles de dislocation-boucle. Les simulations de la dynamique des dislocations sont réalisées à l'aide d'un code nodal 3D appelé NUMODIS, où les développements récents dans ce code sont présentés. Un des caractéristiques de ce code est sa capacité à gérer et contrôler les collisions entre les segments des dislocations. Cela se fait au moyen en utilisant un ensemble d'algorithmes génériques avec un minimum de règles locales<br>This work aims to reproduce the individual interactions between screw dislocations and radiation-induced loops using dislocation dynamics in good agreement with molecular dynamics simulations. Such agreement is characterized by reproducing the dynamics of the reaction and obtaining the critical resolved stress to overcome the obstacles. This approach provides the mean to calibrate our dislocation dynamics code with parameters from the molecular dynamics simulations. Consequently, it permits to perform massive simulations at the mesoscopic scale. In this scope, this work consists of two parts, an identification of the energetic model and identification of elementary mechanisms. In the first part we propose a procedure to calibrate the line tension based on Orowan's mechanism using a sensibility study. In the second part, we have identified the cross-slip and twining/anti-twinning mechanisms to be essential to reproduce the individual dislocation-loop interactions. The dislocation dynamics simulations are done using a 3D nodal code called NUMODIS, where the recent developments in this code are presented. The uniqueness of this code is its ability to manage and control collisions and core reactions between dislocation segments. This is done through a set of generic algorithms with the minimum amount of local rules
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Høifødt, Herman. "Dynamic Modeling and Simulation of Robot Manipulators : The Newton-Euler Formulation." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13275.
Повний текст джерелаАнотація:
Dynamic modeling means deriving equations that explicitly describes the relationship between force and motion in a system. To be able to control a robot manipulator as required by its operation, it is important to consider the dynamic model in design of the control algorithm and simulation of motion. In general there are two approaches available; the Euler-Lagrange formulation and the Newton-Euler formulation. This thesis explains briefly the differences of the formulations, and then research the Newton-Euler method in detail. A complete derivation of the method is derived, and an automated framework for applying the method on any serial manipulator with revolute joints is presented. By using the framework, the Newton-Euler formulation is applied on a modern industrial manipulator with six degrees of freedom. The dynamic parameters of the system are estimated, and the validity of the resulting dynamic model is verified by several simulations in open and closed loop.The simulations show that the system is unstable in open loop, and that it achieves global asymptotic stability in closed loop with gravity compensation, by including PD controllers with independent joint control. The latter is a confirmation of a mathematical proof based on a Lyapunov stability analysis, which is presented as well. Equivalent simulations of the dynamic model of the same manipulator derived by the standard Euler-Lagrange formulation show that the efficiency of recursive procedures is way higher that treating the manipulator as a whole.A suggestion for future work is performing thorough dynamic parameter identification. An improved model can ultimately be implemented in the controller of the manipulator, and optimized for a specific job task.
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Arruda, Michael. "Dynamic inverse resiliant control for damaged asymmetric aircraft: Modeling and simulation." Thesis, Wichita State University, 2009. http://hdl.handle.net/10057/2513.
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This paper presents the development and simulation of a dynamic inverse resilient control (DIRC) system that can recover a general aviation aircraft that has sustained damage to a lifting surface in ight, and is now asymmetrical. A new set of di erential equations of motion for the aircraft are derived that account for the asymmetries of the aircraft and for the dynamic e ects of the shift in the center of gravity away from the original body centered axis. The typical symmetric force and moment coe cient buildup is altered to include the inuences of asymmetric lift, drag, and control deection. For the simulation, a Raytheon Bonanaza F-33C y-by-wire testbed is selected since it has been used in both ight and simulation testing for prior Wichita State University research. Geometric, mass, and aerodynamic properties for the damaged aircraft are determined with conceptual design techniques. The DIRC consists of an inverse controller with decoupled ight controls and an adaptive system to correct the command signals for a damaged aircraft. Modeling errors between the inverse control and the actual aircraft are large. Adaptive Bias Correctors, a simpli ed neural network, are applied to adapt the controller to the modeling errors between the undamaged symmetric based inverse controller and damaged asymmetric aircraft. Adaptation happens fast enough to limit the bank angle excursion and bring the aircraft back to wings level ight. Simulations are performed with a MATLAB/Simulink R and a full 6DOF model of the aircraft. Tests show that for losses to the left wing, the DIRC can recover the aircraft until the available control authority is unable to counteract the asymmetric moments.<br>Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering
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Sarkar, Soumen. "Dynamic modeling of an articulated forestry machine for simulation and control." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27255.
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Recently, robotic technology has begun to play an important role in forestry operations. An important class of forestry machines is comprised of systems equipped with a mobile platform fitted with an articulated arm carrying a tree processing head. The dynamics of such systems are needed for simulation and control purposes. In contrast to conventional industrial manipulators, which are mounted on stationary bases, a mobile manipulator is dynamically coupled with its base. Base compliance, non-linearity and coupled dynamics result in positioning inaccuracies which in turn give rise to control problems.<br>The dynamics of the FERIC forwarder forestry machine including its compliant tires were developed and implemented symbolically in compact form with the help of an iterative Newton-Euler dynamic formulation. Various models with increasing complexity were derived. Based on a simplified dynamics model, a valve-sizing methodology was developed and used to size hydraulic proportional valves of the machine's actuators.<br>System parameters have been obtained by various methods, including use of blueprints, weighing, solid modeling and various experiments. A set-point feedforward controller was designed and the machine's responses for various inputs were obtained to analyze the dynamic behavior of the system. Although initial simulations were done in Matlab and Simulink, C programs were developed for increased speed of execution. In addition, techniques to minimize computation time have been developed and applied to result in almost real time simulation.
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Sarkar, Soumen. "Dynamic modeling of an articulated forestry machine for simulation and control." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29628.pdf.
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Kim, Taewoo. "A 3D XML-based modeling and simulation framework for dynamic models." [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE1000134.
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Thesis (Ph. D.)--University of Florida, 2002.<br>Title from title page of source document. Document formatted into pages; contains xii, 132 p.; also contains graphics. Includes vita. Includes bibliographical references.
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Eastbourn, Scott Michael. "Modeling and Simulation of a Dynamic Turbofan Engine Using MATLAB/Simulink." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1340582603.
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Daryabak, Mehdi. "Modeling line-commutated converter HVDC transmission systems using dynamic phasors." IEEE, 2013. http://hdl.handle.net/1993/31632.
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This thesis develops the dynamic phasor model of a line-commutated converter (LCC) high-voltage direct current (HVDC) transmission system. The mathematical definition and properties of dynamic phasors are utilized to model both the dc-side and the ac-side of a LCC-HVDC transmission system as well as 6-pulse Graetz bridge, which is the building block of such a system.
The developed model includes low-frequency dynamics of the systems, i.e., fundamental frequency component (50 Hz) at the ac-side and dc component at the dc-side, and removes high-frequency transients. The developed model, however, is capable of accommodating higher harmonics if necessary. The model is also able to simulate the system during abnormal modes of operations such as unbalanced operation and commutation failure. In order to develop the dynamic phasor model of a line-commutated converter, the concept of switching functions is utilized.
The developed model is capable of capturing large-signal transients of the system as well as steady state operating conditions. The model can be used in order to decrease the computational intensity of LCC-HVDC simulations. The developed model in this thesis enables the user to consider each harmonic component individually; this selective view of the components of the system response is not possible to achieve in conventional electromagnetic transient simulations.<br>October 2016
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Oguz, Cihan. "Control-oriented modeling of discrete configuration molecular scale processes applications in polymer synthesis and thin film growth /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19867.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2008.<br>Committee Chair: Gallivan, Martha A.; Committee Member: Hess, Dennis; Committee Member: Lee, Jay H.; Committee Member: Li, Mo; Committee Member: Ludovice, Pete.
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Paothong, Arnut. "Dynamic Processes in Network Goods: Modeling, Analysis and Applications." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4558.
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The network externality function plays a very important role in the study of economic network industries. Moreover, the consumer group dynamic interactions coupled with network externality concept is going to play a dominant role in the network goods in the 21st century. The existing literature is stemmed on a choice of externality function with certain quantitative properties. The utility function coupled with the network externality function is used to investigate static properties of rational equilibrium. The aim of this work is to systematically initiate a development of quantitative effects of the concept of network externality and its influence on the characteristics of network market equilibrium.
We introduce several basic concepts, notably, network externality process and network goods. Formulating a principle of network externality, we developed a mathematical dynamic model (1) for the network externality process. A closed form solution of the mathematical model was determined and analyzed (2). The presented qualitative and quantitative analysis provides a systematic and unified way of constructing the existing network externality function. The solution process is called "Generalized Network Externality Function (GNEF)". Moreover, our study of quantitative description, parametric representation of attributes and sensitivity analysis of network externality process provides a tool for planning, policy and performance for network goods (3).
In the absence of desired data set, we presented an illustration to exhibit the significance of GNEF. We used two types of data sets on the US banking asset and deposit. Employing nonlinear regression methods and data sets, we developed statistical models for the US banking asset and deposit, and constructed two normalized the US banking deposit models (4). Finally, using the concept of theory of relative growth and GNEF (4), we developed two dynamic models for the network externality for the US banking asset with respect to the US banking deposit as a financial market share (5).
Incorporating the GNEF (2) in the consumer utility function, a concept of market share adjustment function is introduced and utilized to develop dynamic models for existing rational and static expectation processes (6). In fact, the role and scope of dynamic models of market share adjustment process are extended to the well-known adaptive expectation and its extension process (7). Using a fixed point theorem and the method of upper and lower solutions of discrete time processes, the existence of equilibrium states of developed dynamic models of market share adjustment processes are established in a systematic way (8). Furthermore, the qualitative properties (stability and oscillatory) of equilibrium states are investigated in terms of model and speed of adjustment parameters. Moreover, the system parameter space is decomposed according to qualitative properties (stability, instability and oscillatory) and the type of expectation processes.
Very recently, the idea of local network externality is utilized to characterize the rational equilibrium (under fulfilled expectation assumptions). From the study on two-scale network dynamic model of human mobility process an eco-socio-culture interactions, we note that heterogeneity in the network goods consumer community generates a local network externality. Furthermore, dynamic models of adaptive expectation processes (6,7) for network goods provide tool to extend the characterization of rational equilibrium study to static, current and lagged adaptive types equilibriums. Here, we treat the consumer decision to be a dynamic process. We formulate a dynamic structural representation of a consumer network structure, structure of utility function and decision rule under the influence of local network externality concept (9). For the consumer network structure, we generalize the one-dimensional Hotelling location line model to multi-dimensional location (10). This formulation generates a mathematical model for a consumer decision dynamic process (11). The byproduct of the dynamic model leads to an agent-based simulation model (12). The simulation model is employed to investigate different types of consumer decision dynamic market equilibriums. Moreover, prototype illustrations are given to exhibit the association between network attributes and its market equilibriums.
We extend the work of two firms (duopoly) into multi-firms (oligopoly and monopolistic competition). This work shed light on the policies for manager to meet performance goal of their firm in network goods industry.
In future, we propose to extend this work to incorporate random fluctuations, to remove restrictions and the local and global economic framework in the 21st century.
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Ozunlu, Ozcan Mutlu. "Dynamic modeling of an excavator during digging and simulating the motion." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12610571/index.pdf.
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The aim of this study is to perform the dynamic force analysis of a 3-degrees-of-freedom excavator during digging the soil and to simulate the motion on computer screen. Standard load calculations are done statically, therefore the effects of forces changing with time on the system cannot be observed. The dynamic analysis method used in the thesis is Recursive Newton &ndash<br>Euler Method and the numerical analysis method for simulation is 4th Order Runge &ndash<br>Kutta Method. After this study, the effects of sudden velocity changes<br>i.e, accelerational movements on construction machines, positions of bodies and dynamic forces on joints will be appointed and it will be possible to plan and control the motion.
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Yigit, Cemil. "Theoretical modeling and computer simulations of protein adsorption onto soft polymeric layers." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17528.
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Proteinadsorption ist in vielen biotechnologischen Anwendungen ubiquitär und ein zentrales Forschungsfeld in der Physik der weichen Materie. Das Verstehen der treibenden Kräfte hinter der Proteinadsorption würde zu einer besseren Kontrolle des Adsorptionsprozesses führen und die Entwicklung von Biosystemen mit beispielloser Funktionalität ermöglichen. In der vorliegenden Arbeit wird die Proteinadsorption an weichen polymerartigen Biomaterialien sowie deren physikalische Wechselwirkungen unter Verwendung von zwei unterschiedlichen neu entwickelten Ansätzen theoretisch untersucht. Im ersten Teil wird ein neues mehrkomponentiges kooperatives Bindungsmodell entwickelt, um die Gleichgewichts-Adsorption von Proteinen auf Mikrogelen zu beschreiben. Es war somit möglich, die wahre treibende Kraft der Proteinadsorption zu identifizieren, die hauptsächlich elektrostatischen Ursprungs ist. Eine Errungenschaft des kooperativen Bindungsmodells ist die Vorhersage der kompetitiven Proteinadsorption und -desorption auf das Mikrogel, die auf thermodynamischen Parametern der Adsorption von Proteinen einzelner Sorten basiert. Vergleiche zwischen Experimenten mit binären Proteinmischungen und theoretischen Berechnungen zeigten sehr gute Übereinstimmungen. Der zweite Teil fokussiert auf Protein-Wechselwirkungen mit Polyelektrolyten, um Adsorptionsprozesse auf mikroskopischer Ebene zu erklären. Dafür wurden geladene fleckige Partikel konstruiert und als Proteinmodelle verwendet, während ein einfaches Kugel-Feder-Modell für das Polyelektrolyt und Polyelektrolytbürste benutzt wurde. Ein zentraler Aspekt war die Bestimmung der freien Energie, das Potential der mittleren Kraft (PMF), für die Komplexbildung der beiden Bestandteile mit Vergleichen zur Modellentwicklungen. Die Simulationsergebnisse legen ein komplexes Wechselspiel von elektrostatischen Kräften und Ionenfreisetzungsmechanismen dar, die für die starken attraktiven Wechselwirkungen in den PMFs verantwortlich sind.<br>Protein adsorption is ubiquitous in many biotechnological applications and has become a central research field in soft matter. Understanding the driving forces behind protein adsorption would allow a better control of the adsorption process and the development of biosystems with unprecedented functionality. In this thesis, protein adsorption onto soft polymeric biomaterials and their physical interactions is studied theoretically by using two different and newly developed approaches. In the first part, a novel multi-component cooperative binding model is developed to describe the equilibrium adsorption of proteins onto microgels. It was thus possible to correctly identify the true driving force behind the protein adsorption which was found to be mainly of electrostatic origin. A key achievement by the cooperative binding model is the prediction of competitive protein adsorption and desorption onto the microgel that is based on thermodynamic parameters related to single-type protein adsorption without any variable parameters. Comparisons between experimental data of binary protein mixtures and theoretical calculations have shown excellent agreements. The second part is focused on protein interactions with polyelectrolyte materials to elucidate adsorption processes on a microscopic level. For this purpose, charged patchy particles are constructed and used as protein models while a simple bead-spring model is employed for the polyelectrolyte and polyelectrolyte brush. A central aspect was the determination of the associated free energy, the potential of mean force (PMF), on the complex formation between the two constituents with comparisons to theoretical model developments. The simulation results evidenced a complex interplay of electrostatic forces and ion release mechanisms to be responsible for the strong attractive interactions observed in the PMFs.
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Ye, Wei. "Nano-epitaxy modeling and design: from atomistic simulations to continuum methods." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50304.
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The dissertation starts from the understanding of dislocation dissipation mechanism due to the image force acting on the dislocation. This work implements a screw dislocation in solids with free surfaces by a novel finite element model, and then image forces of dislocations embedded in various shaped GaN nanorods are calculated. As surface stress could dramatically influence the behavior of nanostructures, this work has developed a novel analytical framework to solve the stress field of solids with dislocations and surface stress. It is successfully implemented in this framework for the case of isotropic circular nanowires (2D) and the analytical result of the image force has been derived afterwards. Based on the finite element analysis and the analytical framework, this work has a semi-analytical solution to the image force of isotropic nanorods (3D) with surface stress. The influences of the geometrical parameter and surface stress are illustrated and compared with the original finite element result. In continuation, this work has extended the semi-analytical approach to the case of anisotropic GaN nanorods. It is used to analyze image forces on different dislocations in GaN nanorods oriented along polar (c-axis) and non-polar (a, m-axis) directions. This work could contribute to a wide range of nanostructure design and fabrication for dislocation-free devices.
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Kewlani, Gaurav. "Large eddy simulations of premixed turbulent flame dynamics : combustion modeling, validation and analysis." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93863.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 293-300).<br>High efficiency, low emissions and stable operation over a wide range of conditions are some of the key requirements of modem-day combustors. To achieve these objectives, lean premixed flames are generally preferred as they achieve efficient and clean combustion. A drawback of lean premixed combustion, however, is that the flames are more prone to dynamics. The unsteady release of sensible heat and flow dilatation in combustion processes create pressure fluctuations which, particularly in premixed flames, can couple with the acoustics of the combustion system. This acoustic coupling creates a feedback loop with the heat release that can lead to severe thermoacoustic instabilities that can damage the combustor. Understanding these dynamics, predicting their onset and proposing passive and active control strategies are critical to large-scale implementation. For the numerical study of such systems, large eddy simulation (LES) techniques with appropriate combustion models and reaction mechanisms are highly appropriate. These approaches balance the computational complexity and predictive accuracy. This work, therefore, aims to explore the applicability of these methods to the study of premixed wake stabilized flames. Specifically, finite rate chemistry LES models that can effectively capture the interaction between different turbulent scales and the combustion fronts have been implemented, and applied for the analysis of premixed turbulent flame dynamics in laboratory-scale combustor configurations. Firstly, the artificial flame thickening approach, along with an appropriate reduced chemistry mechanism, is utilized for modeling turbulence-combustion interactions at small scales. A novel dynamic formulation is proposed that explicitly incorporates the influence of strain on flame wrinkling by solving a transport equation for the latter rather than using local-equilibrium-based algebraic models. Additionally, a multiple-step combustion chemistry mechanism is used for the simulations. Secondly, the presumed-PDF approach, coupled with the flamelet generated manifold (FGM) technique, is also implemented for modeling turbulence-combustion interactions. The proposed formulation explicitly incorporates the influence of strain via the scalar dissipation rate and can result in more accurate predictions especially for highly unsteady flame configurations. Specifically, the dissipation rate is incorporated as an additional coordinate to presume the PDF and strained flamelets are utilized to generate the chemistry databases. These LES solvers have been developed and applied for the analysis of reacting flows in several combustor configurations, i.e. triangular bluff body in a rectangular channel, backward facing step configuration, axi-symmetric bluff body in cylindrical chamber, and cylindrical sudden expansion with swirl, and their performance has been be validated against experimental observations. Subsequently, the impact of the equivalence ratio variation on flame-flow dynamics is studied for the swirl configuration using the experimental PIV data as well as the numerical LES code, following which dynamic mode decomposition of the flow field is performed. It is observed that increasing the equivalence ratio can appreciably influence the dominant flow features in the wake region, including the size and shape of the recirculation zone(s), as well as the flame dynamics. Specifically, varying the heat loading results in altering the dominant flame stabilization mechanism, thereby causing transitions across distinct- flame configurations, while also modifying the inner recirculation zone topology significantly. Additionally, the LES framework has also been applied to gain an insight into the combustion dynamics phenomena for the backward-facing step configuration. Apart from evaluating the influence of equivalence ratio on the combustion process for stable flames, the flame-flow interactions in acoustically forced scenarios are also analyzed using LES and dynamic mode decomposition (DMD). Specifically, numerical simulations are performed corresponding to a selfexcited combustion instability configuration as observed in the experiments, and it is observed that LES is able to suitably capture the flame dynamics. These insights highlight the effect of heat release variation on flame-flow interactions in wall-confined combustor configurations, which can significantly impact combustion stability in acoustically-coupled systems. The fidelity of the solvers in predicting the system response to variation in heat loading and to acoustic forcing suggests that the LES framework can be suitably applied for the analysis of flame dynamics as well as to understand the fundamental mechanisms responsible for combustion instability. KEY WORDS - large eddy simulation, LES, wake stabilized flame, turbulent premixed combustion, combustion modeling, artificially thickened flame model, triangular bluff body, backward facing step combustor, presumed-PDF model, flamelet generated manifold, axi-symmetric bluff body, cylindrical swirl combustor, particle image velocimetry, dynamic mode decomposition, combustion instability, forced response.<br>by Gaurav Kewlani.<br>Ph. D.