Dissertationen: „Drive simulation model“

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League, Richard B. „Bond graph model and computer simulation of a hydrostatic drive test stand“. Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/50042.

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A hydrostatic drive test stand was constructed to aid in the instruction of the characteristics of hydrostatic transmissions and to develop a time-varying load in a shaft to compare torque transducers. A mathematical model of the device was derived using the bond graph approach and was implemented using the Advanced Continuous Simulation Language (ACSL). The test stand was used to obtain experimental data to try to refine the model parameters. To facilitate the measurement of system flows, a microprocessor-based digital flow indicator was developed. Steady-state tests were performed at various constant pump swashplate angles; for the dynamic tests, the pump swashplate angle was cycled from zero degrees to 6.5 degrees.
Master of Science
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Starke, Martin, Benjamin Beck, Denis Ritz, Frank Will und Jürgen Weber. „Frequency based efficiency evaluation - from pattern recognition via backwards simulation to purposeful drive design“. Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71072.

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The efficiency of hydraulic drive systems in mobile machines is influenced by several factors, like the operators’ guidance, weather conditions, material respectively loading properties and primarily the working cycle. This leads to varying operation points, which have to be performed by the drive system. Regarding efficiency analysis, the usage of standardized working cycles gained through measurements or synthetically generated is state of the art. Thereby, only a small extract of the real usage profile is taken into account. This contribution deals with process pattern recognition (PPR) and frequency based efficiency evaluation to gain more precise information and conclusion for the drive design of mobile machines. By the example of an 18 t mobile excavator, the recognition system using Hidden – Markov - Models (HMM) and the efficiency evaluation process by means of backwards simulation of measured operation points will be described.

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Almén, Marcus. „Driver Model for Mission-Based Driving Cycles“. Thesis, Linköpings universitet, Fordonssystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-140158.

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When further demands are placed on emissions and performance of cars, trucks and busses, the vehicle manufacturers are looking to have cheap ways to evaluate their products for specific customers' needs. Using simulation tools to quickly compare use cases instead of manually recording data is a possible way forward. However, existing traffic simulation tools do not provide enough detail in each vehicle for the driving to represent real life driving patterns with regards to road features. For the purpose of this thesis data has been recorded by having different people drive a specific route featuring highway driving, traffic lights and many curves. Using this data, models have then been estimated that describe how human drivers adjust their speed through curves, how long braking distances typically are with respect to the driving speed, and the varying deceleration during braking sequences. An additional model has also been created that produces a speed variation when driving on highways. In the end all models are implemented in Matlab using a traffic control interface to interact with the traffic simulation tool SUMO. The results of this work are promising with the improved simulation being able to replicate the most significant characteristics seen from human drivers when approaching curves, traffic lights and intersections.

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Zsolt, Pap Levente. „Model Predictive Control of Electric Drives -Design, Simulation and Implementation of PMSM Torque Control“. Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-240365.

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The thesis deals with the design of a permanent magnet synchronous machine controller that isimplemented on an embedded platform to replace the off-the-shelf controller currently being used in theelectric race car of the KTH Formula Student team. Software implementation of the control algorithmwas tested in laboratory environment on the hardware prototype of a 2-level three-phase voltage sourceinverter.Field oriented control and finite control set model predictive control algorithms were implemented insimulation environment. The latter performed better in terms of reducing switching activity and torqueripple, but needs vastly more computational resources due to its nature of being an online optimizationproblem. Trade-off curve of phase current harmonic distortion and switching activity showed that themodel prediction control algorithm performs better in the low frequency range (1-20 kHz). Obtainedsimulation results were used for power electronics component selection.Field oriented control was implemented on a TMS320F28335 DSP. SPI communication was employedto configure gate driver circuits and perform error handling. The DSP program follows interrupt basedorganization and the main control loop runs on the variable frequency of the pulse width modulation.Low voltage test results on three-phase inductive-resistive load showed that the controller outputssinusoidal current. Efficiency measurement, high voltage and motor testing were hindered by interferencefrom the Silicon-Carbide MOSFETs that prohibited correct operation of hardware.
Den här uppsatsen handlar om designen och implementeringen av en motorstyrning för en permanen- magnetiserad synkronmotor, med syfte att ersätta standardmotorstyrningsenheten i KTH Formula Students tävlingsbil. Implementationen av styralgoritmen testades experimentellt tillsammans med en prototyptillverkad frekvensomriktare i labbmiljö. Regleralgoritmer för field oriented control och finite control set model predictive control implementerades och testades i simuleringsmiljö. Den senare algoritmen visade sig prestera bättre i form av lägre vridmomentsoscillationer trots lägre switch-frekvens men den kräver samtidigt mer beräkningskraft. Övertonsinnehållet (THD) i fasströmmarna som funktion av switchfrekvensen undersöktes för de båda regleralgoritmerna, algoritmen för model predictive control gav lägre THD vid lägre frekvenser (1-20 kHz). Simuleringsresultaten användes för att motivera valet av komponenter till frekvensomriktaren. Regleralgoritmen för field oriented control implementerades och testades experimentellt med hjälp av ett utvecklingskort (TMS320F28335) från Texas Instruments. SPI-kommunikation användes för att konfigurera drivkretsana samt för att utläsa felkoder. Experimentalla tester som utfördes på låg spänningsnivå visade att strömmen till lasten var sinusformad. Mätning av verkningsgrad och provning tillsammans med motorn på en högre spänningsnivå gick inte att geno av att de snabba switchförloppen i kiselkarbidtransistorerna störde ut motorstyrningen.

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Abdul-Jalal, Rifqi I. „Engine thermal management with model predictive control“. Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/24274.

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The global greenhouse gas CO2 emission from the transportation sector is very significant. To reduce this gas emission, EU has set an average target of not more than 95 CO2/km for new passenger cars by the year 2020. A great reduction is still required to achieve the CO2 emission target in 2020, and many different approaches are being considered. This thesis focuses on the thermal management of the engine as an area that promise significant improvement of fuel efficiency with relatively small changes. The review of the literature shows that thermal management can improve engine efficiency through the friction reduction, improved air-fuel mixing, reduced heat loss, increased engine volumetric efficiency, suppressed knock, reduce radiator fan speed and reduction of other toxic emissions such as CO, HC and NOx. Like heat loss and friction, most emissions can be reduced in high temperature condition, but this may lead to poor volumetric efficiency and make the engine more prone to knock. The temperature trade-off study is conducted in simulation using a GT-SUITE engine model coupled with the FE in-cylinder wall structure and cooling system. The result is a map of the best operating temperature over engine speed and load. To quantify the benefit of this map, eight driving styles from the legislative and research test cycles are being compared using an immediate application of the optimal temperature, and significant improvements are found for urban style driving, while operation at higher load (motorway style driving) shows only small efficiency gains. The fuel consumption saving predicted in the urban style of driving is more than 4%. This assess the chance of following the temperature set point over a cycle, the temperature reference is analysed for all eight types of drive cycles using autocorrelation, lag plot and power spectral density. The analysis consistently shows that the highest volatility is recorded in the Artemis Urban Drive Cycle: the autocorrelation disappears after only 5.4 seconds, while the power spectral density shows a drop off around 0.09Hz. This means fast control action is required to implement the optimal temperature before it changes again. Model Predictive Control (MPC) is an optimal controller with a receding horizon, and it is well known for its ability to handle multivariable control problems for linear systems with input and state limits. The MPC controller can anticipate future events and can take control actions accordingly, especially if disturbances are known in advance. The main difficulty when applying MPC to thermal management is the non-linearity caused by changes in flow rate. Manipulating both the water pump and valve improves the control authority, but it also amplifies the nonlinearity of the system. Common linearization approaches like Jacobian Linearization around one or several operating points are tested, by found to be only moderately successful. Instead, a novel approach is pursued using feedback linearization of the plant model. This uses an algebraic transformation of the plant inputs to turn the nonlinear systems dynamics into a fully or predominantly linear system. The MPC controller can work with the linear model, while the actual control inputs are found using an inverse transformation. The Feedback Linearization MPC of the cooling system model is implemented and testing using MathWork Simulink®. The process includes the model transformation approach, model fitting, the transformation of the constraints and the tuning of the MPC controller. The simulation shows good temperature tracking performance, and this demonstrates that a MPC controller with feedback linearization is a suitable approach to thermal management. The controller strategy is then validated in a test rig replicating an actual engine cooling system. The new MPC controller is again evaluated over the eight driving cycles. The average water pump speed is reduced by 9.1% compared to the conventional cooling system, while maintaining good temperature tracking. The controller performance further improves with future disturbance anticipation by 20.5% for the temperature tracking (calculated by RMSE), 6.8% reduction of the average water pump speed, 47.3% reduction of the average valve movement and 34.0% reduction of the average radiator fan speed.

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Matiaško, Dušan. „Modely a simulace pochodů bezemisního mini-exkavátoru s elektrickým pohonem“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442805.

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The diploma thesis dealt with a partial problem of conversion of the mini-excavator E19 by Bobcat with an internal combustion engine to emission-free propulsion. The main task was design and construction of electrical and hydraulic circuits focusing on the drive of a mini-excavator. The simulations verified the properties and behavior of the mini-excavator under different conditions and initial settings. The results were comfirmed by experimental measurements. The output of the simulations recommended adjustments to the values of individual parameters depending on the travel speed but also the efficiency of the entire machine.

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Wittwer, Max. „Modelling and Design of a Test Rig to investigate the dynamic behaviour of a Servo driven Powertrain“. Master's thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232565.

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In the present work a simulation model for examining the fundamental dynamic behaviour of a servo driven powertrain is developed. This powertrain consists of a permanent magnet synchronous motor, a cycloidal gearbox and a torque motor to apply a load. On basis of this model the selection of components for the design of a test rig is possible. This leads to the constructive draft of the test rig. In order to model the system, the fundamentals give a brief overview of the components incorporated in the test rig system. With ais of the specified task the simulation purpose is defined and the modelling process enabled. The subsequent system analysis is performed intensively to decompose the system into subsystems, which are then investigated to find the optimal modelling approach for the given simulation task. Particular emphasis is put on the investigation of the cycloidal gearbox subsystem and it shows, that approaches for modelling the dynamic behaviour of the gearbox as a whole have only been published partially. Therefore, the available modelling approaches are analysed and suitable models are developed as conceptual models. Those will be formalised and implemented in Matlab/Simulink. The model is verified and simulation experiments are performed, that help in the selection of suitable test rig components. On basis of a flexible test rig, finally the constructive draft is presented.

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Křepela, Jan. „Dynamické vlastnosti osy C pro multifunkční soustružnické centrum“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233982.

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his Disertation thesis involves the creating of the simulation model of the C axis drive over mentioned machine and them verification on the prototype of this machine. C axis is controlled with position feedback. Simulation model was created before the realisation of the machine prototype for the preliminary identification of the dynamic behaviours in the working cycles and them opportunity of the realisation this conception. C axis is constructed with worm gear and is controlled with help of Master-Slave drive. This torque drive eliminates the production backlash in the worm gear. The multifunction turning center, where is used this C axis, is determinate for heavy duty roughing cutting of the forged peaces, where is problem with dynamic stability of the cutting process. Simulation model includes the problems with multi-body mass system, friction on the worm gear, self locking, damping on the worm gear and the optimization of the parametrs for many regulators. Simulation model was verified on the prototype of the machine. Achieved results bring the new knowledge, which are used for simulation complicated machine nodes and this knowledge is used for research and developing of the similar mechatronics system.

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9

Liu, Chang. „Drive-By Bridge Damage Identification Through Virtual Simulations“. Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31624.

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With massive infrastructures built in US, timely condition assessment of these infrastructures becomes critical to daily traffic and economics. Due to high cost, long time consumption of direct condition assessment methods, such as closing traffic for sensor installation and monitoring, indirect bridge monitoring has become a promising method. However, the technology is in its initial stage and needs substantial refinement. In this research, virtual simulation approaches, both in 2D and 3D, are used to model the bridge and vehicle interaction through ABAQUS. Artificial Damages were embedded to the model according to different locations and different levels of intensities. With the modelled outcomes, the hypothesis of identifying damages through the responses of the vehicle will be tested. From the simulated vehicle responses, bridge frequencies and damage locations and sizes could be identified accurately through short time flourier transformation and mode shape difference.

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Hu, Bo. „Model compiler driven device modeling and circuit simulation /“. Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/6054.

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11

Guermazi, Sahar. „Model-driven co-simulation of Cyber-Physical Systems“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS333/document.

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Les CPS intègrent des composants physiques et des composants logiciels. Ils sont particulièrement difficiles à modéliser et à vérifier. En effet, de par la nature hétérogène de leurs composants, leur conception nécessite l’utilisation de différents formalismes de modélisation. Les modèles de ces systèmes combinent à la fois des formalismes à temps continu, et d’autres à événements discrets, pour représenter respectivement leurs composants physiques et logiciels. La vérification de l'ensemble du système nécessite donc la composition de ces composants. La vérification globale peut être réalisée par co-simulation des différents composants. En particulier, la norme FMI offre une interface normative pour coupler plusieurs simulateurs dans un environnement de co-simulation, nommé « Master ». Celui-ci est chargé de fournir un algorithme pour une synchronisation efficace des différents composants du système, nommés FMU. Cependant, FMI est initialement conçu pour la co-simulation des processus physiques, avec un support limité des formalismes à événements discrets qui est modèle de calcul et de communication largement utilisé dans les environnements de modélisation spécifiques au logiciel. En particulier, aucune des solutions actuelles de co-simulation basées sur FMI ne permet de le prendre en considération les modèle UML. La thèse défendue dans ce document est que l'ingénierie système en général bénéficierait de l’intégration des modèles UML dans une approche de co-simulation basée sur la norme FMI. Cela permettra à un grand nombre de concepteurs logiciels d’évaluer le comportement de leurs composants logiciels dans un environnement simulé, et donc de les aider à faire les meilleurs choix de conception le plus tôt possible dans leur processus de développement. Cela pourrait également ouvrir de nouvelles perspectives intéressantes pour les ingénieurs système des CPS, en leur permettant d'envisager l’utilisation d’un langage largement utilisé pour la modélisation des composants logiciels de leurs systèmes. L'objectif de cette thèse est de définir et formaliser un environnement de co-simulation basé sur la norme FMI pour les CPS et intégrant des modèles UML pour la partie logicielle. Nous abordons principalement la question d’adaptation entre la sémantique d’exécution définie dans UML et celle de FMI. Notre contribution intervient à deux niveaux : localement, au niveau des modèles UML, et globalement au niveau du « Master ». Localement, nous mettons en place une approche incrémentale où nous abordons différents types de systèmes à événements discrets caractérisant les composants logiciels. Nous basons nos propositions sur les normes OMG fUML et PSCS qui définissent une sémantique d’exécution précise pour un sous-ensemble de UML. Ces deux normes constitue notre socle de définition nous donne une base intéressante et formelle pour l'intégration des modèles UML dans les approches de co-simulation de CPS. Pour chaque type de système, nous identifions d'abord un ensemble de règles pour le modéliser avec UML et les éventuelles extensions à fUML dans le cas où la sémantique d'exécution des éléments UML requis n’est pas définie dans fUML. Ensuite, au niveau global, nous proposons un algorithme de « Master » pour chaque type de systèmes. Les algorithmes de « Master » reposent sur l'adaptation de la sémantique d’exécution des modèles UML et celle de FMI. Sur cette base, le « Master » est capable de propager les données entre les composants et de les stimuler aux bonnes dates durant la simulation. L'approche est illustrée par des cas d'utilisation du domaine des bâtiments intelligents, où l’objectif est d’évaluer différentes stratégies de gestion d'énergie. Ces stratégies représentent des composants logiciels à différents niveaux de contrôle d’un bâtiment pour des fins d’optimisation de son auto-consommation en électricité
Cyber Physical Systems (CPS) are integrations of physical and computational components. CPS are difficult to model and verify because the heterogeneous nature of their components requires many different modeling formalisms. The global verification of the system can be achieved by co-simulation. FMI standard offers a standard interface to couple two or more simulators in a co-simulation environment, known as master. This latter is responsible for providing an algorithm with efficient orchestration and synchronization of the involved components, known as FMUs. However, FMI was originally intended for co-simulation of physical processes, with limited support for formalisms such as DE and Dara-Flow, even if this kind of formalisms are commonly used to model the logic of software parts of a system. In particular, while UML is the reference standard for software modeling and is very commonly used in industry, none of the present-day FMI-based co-simulation solutions consider UML models. Our thesis is that system engineering in general would greatly benefit from the consideration of UML in FMI-based co-simulation approach. It would indeed enable a significant number of software designers to evaluate the behavior of their software components in their simulated environment, as soon as possible in their development processes, and therefore make early and better design decisions. It would also open new interesting perspectives for CPS system engineers, by allowing them to consider a widely used modeling language for the software parts of their systems. In this context, the objective of this work is to define an FMI-based co-simulation environment for CPS with integration of UML models for software part. Our contribution is twofold: locally at the level of UML models, and globally at the master level. At the local level, we set up an incremental approach where we address different kinds of discrete event systems characterizing the computational components. We base our proposals on OMG standards fUML and PSCS which define precise execution semantics for a subset of UML. They provide an interesting and formal basis for the integration of UML models in CPSs co-simulation approaches. For each kind of system, we first identify a set of rules to model it with UML and potential extensions to fUML in case where execution semantics of the required UML elements are not defined by fUML. Then, at the global level, we propose a master algorithm for each kind of systems. The proposed masters take into account not only external and internal dependencies between components and their capabilities, but also and especially their models of time. They rely on adaptation of fUML semantics to that of the FMI API. Based on these adaptations, the master algorithm is able both to propagate data between components and to trigger them at the correct points of time. The approach is illustrated with use cases from the energy domain where the purpose is to verify energy management strategies defined as software components at different levels of the control module of an energy system

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Bhargava, Rajat. „Simulation models for variable speed electric drives“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq22571.pdf.

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13

Alt, Aaron J. „Profile Driven Partitioning Of Parallel Simulation Models“. University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1407406955.

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14

Brumbulli, Mihal. „Model-driven development and simulation of distributed communication systems“. Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2015. http://dx.doi.org/10.18452/17233.

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Verteilte Kommunikationssysteme haben in den letzten Jahren enorm an Bedeutung gewonnen, insbesondere durch die Vielzahl von Anwendungen in unserem Alltag. Die Heterogenität der Anwendungen und Anwendungsdomänen spricht für die Komplexität solcher Systeme und verdeutlicht die Herausforderungen, mit denen ihre Entwickler konfrontiert sind. Der Schwerpunkt dieser Arbeit liegt auf der Unterstützung des Entwicklungsprozesses von Anwendungen für verteilte Kommunikationssysteme. Es gibt zwei Aspekte, die dabei berücksichtigt werden müssen. Der erste und offensichtlichste ist die Unterstützung der Entwicklung der Anwendung selbst, die letztendlich auf der vorhandenen verteilten Kommunikationsinfrastruktur bereitgestellt werden soll. Der zweite weniger offensichtliche, aber genauso wichtige Aspekt besteht in der Analyse der Anwendung vor ihrer eigentlichen Installation. Anwendungsentwicklung und analyse sind also "zwei Seiten der gleichen Medaille". Durch die Berücksichtigung beider Aspekt erhöht sich jedoch andererseits der Aufwand bei der Entwicklung. Die Arbeit kombiniert und erweitert vorhandene Technologien entsprechend dem modellgetriebenen Entwicklungsparadigma zu einer einheitlichen Entwicklungsmethode. Die Eigenschaften der Anwendung werden in einer vereinheitlichten Beschreibung erfasst, welche sowohl die automatische Überführung in Installationen auf echten Infrastrukturen erlaubt, als auch die Analyse auf der Basis von Modellen. Darüber hinaus wird der Entwicklungsprozess mit zusätzlicher Unterstützung bei der Visualisierung der Analyse ergänzt. Die Praktikabilität des Ansatzes wird anschließend anhand der Entwicklung und Analyse einer Anwendung zur Erdbebenfrühwarnung unter Beweis gestellt.
Distributed communication systems have gained a substantial importance over the past years with a large set of examples of systems that are present in our everyday life. The heterogeneity of applications and application domains speaks for the complexity of such systems and the challenges that developers are faced with. The focus of this dissertation is on the development of applications for distributed communication systems. There are two aspects that need to be considered during application development. The first and most obvious is the development of the application itself that will be deployed on the existing distributed communication infrastructure. The second and less obvious, but equally important, is the analysis of the deployed application. Application development and analysis are like "two sides of the the same coin". However, the separation between the two increases the cost and effort required during the development process. Existing technologies are combined and extended following the model-driven development paradigm to obtain a unified development method. The properties of the application are captured in a unified description which drives automatic transformation for deployment on real infrastructures and/or analysis. Furthermore, the development process is complemented with additional support for visualization to aid analysis. The defined approach is then used in the development of an alarming application for earthquake early warning.

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Kesaraju, Vishnu Sharma. „An Integrated Simulation Environment Combining Process-Driven and Event-Driven Models“. Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1238779995.

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Zheng, Pengjun. „A microscopic simulation model of merging operation at motorway on ramps“. Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289589.

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Sellgren, Ulf. „Simulation-driven design : Motives, Means, and Opportunities“. Doctoral thesis, KTH, Maskinkonstruktion, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2875.

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Efficiency and innovative problem solving are contradictory requirements for productdevelopment (PD), and both requirements must be satisfied in companies that strive to remainor to become competitive. Efficiency is strongly related to ”doing things right”, whereasinnovative problem solving and creativity is focused on ”doing the right things”.Engineering design, which is a sub-process within PD, can be viewed as problem solving or adecision-making process. New technologies in computer science and new software tools openthe way to new approaches for the solution of mechanical problems. Product datamanagement (PDM) technology and tools can enable concurrent engineering (CE) bymanaging the formal product data, the relations between the individual data objects, and theirrelation to the PD process. Many engineering activities deal with the relation betweenbehavior and shape. Modern CAD systems are highly productive tools for conceptembodiment and detailing. The finite element (FE) method is a general tool used to study thephysical behavior of objects with arbitrary shapes. Since a modern CAD technology enablesdesign modification and change, it can support the innovative dimension of engineering aswell as the verification of physical properties and behavior. Concepts and detailed solutionshave traditionally been evaluated and verified with physical testing. Numerical modeling andsimulation is in many cases a far more time efficient method than testing to verify theproperties of an artifact. Numerical modeling can also support the innovative dimension ofproblem solving by enabling parameter studies and observations of real and syntheticbehavior. Simulation-driven design is defined as a design process where decisions related tothe behavior and performance of the artifact are significantly supported by computer-basedproduct modeling and simulation.A framework for product modeling, that is based on a modern CAD system with fullyintegrated FE modeling and simulation functionality provides the engineer with tools capableof supporting a number of engineering steps in all life-cycle phases of a product. Such aconceptual framework, that is based on a moderately coupled approach to integratecommercial PDM, CAD, and FE software, is presented. An object model and a supportingmodular modeling methodology are also presented. Two industrial cases are used to illustratethe possibilities and some of the opportunities given by simulation-driven design with thepresented methodology and framework.
QC 20100810

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Durrani, Faisal. „Using large eddy simulation to model buoyancy-driven natural ventilation“. Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12488.

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The use of Large Eddy Simulation (LES) for modelling air flows in buildings is a growing area of Computational Fluid Dynamics (CFD). Compared to traditional CFD techniques, LES provides a more detailed approach to modelling turbulence in air. This offers the potential for more accurate modelling of low energy natural ventilation which is notoriously difficult to model using traditional CFD. Currently, very little is known about the performance of LES for modelling natural ventilation, and its computational intensity makes its practical use on desk top computers prohibitive. The objective of this work was to apply LES to a variety of natural ventilation strategies and to compile guidelines for practitioners on its performance, including the trade-off between accuracy and cost.

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Zheng, Yue. „Driver model for a software in the loop simulation tool“. Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265668.

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For this project, a Software-In-the-Loop (SIL) simulation tool is used at Scania (“VTAB” – Virtual Truck and Bus), which simulates the submodels of the mechanical vehicle components together with the real control units. The simulation tool contains the following submodels: Engine model, Drivetrain model, Drive cycle model, Restbus model, and Driver model. The simulated human driver submodel in the restbus model outputs two pedal control signals to the control unit, namely the gas and brake pedals. With these two pedal signals, the control unit decides the modes of mechanical vehicle components. This driver model needs to be reworked to obtain a better velocity following performance. Two controllers, fuzzy PI anti-windup and backward calculation, are implemented in the driver model and compared by the velocity tracking accuracy and the pedal switching frequency. In the comparison and analysis section, two different cycles and two weights of payload are simulated. The simulation results demonstrate that both controllers can improve the driver model’s velocity tracing accuracy. Further, the fuzzy PI anti-windup controller is better when considering pedal signals fluctuation frequency and implementation complexity.
För detta projekt används ett simuleringsverktyg Software-In-the-Loop (SIL) på Scania (“VTAB” - Virtual Truck and Bus), vilket simulerar submodellerna för de mekaniska fordonskomponenterna tillsammans med de verkliga styrenheterna. Simuleringsverktyget innehåller följande submodeller: Motormodell, Drivmotormodell, Drivcykelmodell, Restbusmodell och Drivermodell. Den simulerade submodellen för mänsklig förare i restbussmodellen kommer att sända två pedalsstyrsignaler till styrenheten, nämligen gas och broms. Med dessa två pedalsignaler kan styrenheten avgöra lägen av mekaniska fordonskomponenter. Denna drivrutinmodell måste omarbetas för att få en bättre hastighetsspårnings presentationsförmåga. Två styrenheter, fuzzy PI anti-windup och bakåtberäkning, implementeras i förarmodell och jämförs respektive med hastighetsspårningsnoggrannhet och pedalväxelfrekvens. I jämförelseoch analysavsnittet simuleras två olika cyklar och två nyttolast. Simuleringsresultaten visar att båda kontrollerna kan förbättra förarmodellens hastighetsspårningskapacitet. Vidare är fuzzy PI-anti-windup-kontroller bättre när man tar hänsyn till pedalsignalernas fluktueringsfrekvens och implementeringskomplexitet

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Hoult, W. „A neuromuscular model for simulating driver steering torque“. Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604261.

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A linear neuromuscular model was developed and incorporated within a driver/vehicle model. Optimal control was used to minimise metabolic energy and path-following error. Simultaneous feed-forward and feedback operation was observed, with the stretch reflex loop acting to reject disturbances. A trade-off between minimising the feedback error signal and energy consumption exists that has not been previously identified. A non-linear, Huxley/Zahalak-based model of an agonist/antagonist muscle pair connected to a second order load was implemented (the ‘MDM’ model). Mechanistic and energy consumption predictions compare favourably with published data. The model was linearized, to allow incorporation within a linear neuromuscular framework. A suitable model structure was fitted using parametric methods. A novel, linear, energy consumption model was proposed. A parameter study of the MDM model was carried out. Variable natural length behaviour was observed, consistent with real muscle operation. Findings suggested that the stretch reflex gain is not large enough to account for low frequency behaviour observed by some researchers for ‘stochastic disturbance’ type experiments. An optimal controller representing cognitive influence was shown to account for this behaviour. A Box-Jenkins method for identifying intrinsic and reflex dynamics models (on the basis of reflex delay) was developed and validated. The impact of the stretch reflex gain and noise levels on identification success was investigated. Intrinsic and reflex models were identified from eight test subjects’ data. The closed-loop neuromuscular model agreed well with measured data, and was generally consistent with MDM model predictions. Low frequency control action and changes in stretch reflex dynamics were observed, stemming from cognitive influence. Other researchers have failed to account for this.

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Daniels, Oskar. „Driver-truck models for software-in-the-loop simulations“. Thesis, Linköpings universitet, Fordonssystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-111515.

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By using vehicle-to-vehicle communication, vehicles can cooperate in many waysby sending positions and other relevant data between each other. One popularexample is platooning where many, especially heavy vehicles, drive on a trailwith short distances resulting in a reduction of air resistance. To achieve a goodefficiency of the platooning it is required that vehicle fleets are coordinated, sothat the percentage of time for driving in platoon is maximized without affectingthe total driving time and distance too much. For large fleets, this is a complexoptimization problem which would be difficult to solve by only using the realworld as the test environment. To provide a more adaptable test environment for the communication and platooningcoordination, an augmented reality with virtual vehicles (“Ghost trucks")with relevant communication abilities are developed. In order to realise the virtualtesting environment for trucks, Scania initiated a project that could be dividedinto the workload of three master theses. This thesis involved the part ofdeveloping the virtual vehicles, which include the development of a truck modeland a driver model. The developed truck model consists of a single track vehicle model and severalpowertrain models of different complexity provided by Scania. Additionally, thedriver model consists of steering wheel and speed controls in order to keep thetruck on a safe distance from the lead truck and stay on a preferred lane. The keyfeature of the driver-truck model is its modular design, which provides great flexibilityin selecting the level of detail for each component. The driver-truck modelcan be duplicated and simulated together in real time and performs platooningwith each other in a road system based on the real world. As the driver-truckmodel is module based, it can easily be extended for future purposes with morecomplex functions. The driver-truck model is implemented in Simulink and the simulation performancefor different model complexity is evaluated. It is demonstrated that theflexibility of the developed model allows a balanced decision to be made betweenrealistic truck behavior and simulation speed. Furthermore, multi-truck simulationsare performed using the model, which demonstrate the effectiveness of themodel in the evaluation of truck platooning operations.

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Schafrik, Steven Joseph. „A New Style of Simulation Model for Mining Systems“. Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35285.

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The algorithms for the mathematical modeling to predict productivity of underground room-and-pillar mining systems are well-known and documented. These algorithms consider the time-varying relationships between mining equipment for a given geometry of operations as well as other constraints. This study presents a newly developed, user-friendly visual simulation computer tool for the Windows environment. This tool can be easily customized and utilized by field engineers and will help mine operators plan the optimum mining sequence for different mine geometries and equipment layouts. Program output includes monitoring of shift data, equipment utilization indices, and so forth. The simulation technique can be used with any environment. Use of the system is demonstrated in different mining equipment configurations. Development and validation of the system was aided by the Peabody Group.
Master of Science

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Knopp, Tobias. „Finite element simulation of buoyancy-driven turbulent flows“. Doctoral thesis, [S.l.] : [s.n.], 2003. http://webdoc.sub.gwdg.de/diss/2003/knopp/knopp.pdf.

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Dingus, Thomas A. „Development of models for detection of automobile driver impairment“. Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45721.

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Two of the leading causes of automobile accidents are driver impairment due to alcohol and drowsiness. Apparently, a relatively large percentage of these accidents occur because drivers are unaware of the degree to which they are impaired due to these sources. The purpose of this research was to develop models which could detect driver impairment due to alcohol, drowsiness, or the combination of alcohol and drowsiness, and which could be practically implemented in an automobile. Such detection models, if successfully implemented in conjunction with a system to warn an impaired driver of his or her condition, could potentially save hundreds of lives each year. Six driver-subjects operated a computer controlled driving simulator during each of four conditions. The four conditions consisted of a control condition, an alcohol condition, a sleep-deprived condition, and a combination alcohol and sleep-deprived condition. Moderate levels of alcohol and sleep deprivation were used for this study. Nineteen performance and behavioral measures were collected during this study. Each measure was evaluated singly and in combination with other measures to determine potential value for detection of driver impairment. Detection models were then formulated using the most promising detection measures. The results indicated that a useful on-board drowsiness impairment detection device is possible and practical for highway driving. This device would also, in all likelihood, provide useful detection information regardless of whether low to moderate amounts of alcohol were present in a drowsy driver. The results also showed that on-board alcohol impairment detection may be possible at moderate to high BAC.
Master of Science

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Anderson, Ross Michael. „Stochastic models and data driven simulations for healthcare operations“. Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92055.

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Thesis: Ph. D., Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2014.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 251-257).
This thesis considers problems in two areas in the healthcare operations: Kidney Paired Donation (KPD) and scheduling medical residents in hospitals. In both areas, we explore the implications of policy change through high fidelity simulations. We then build stochastic models to provide strategic insight into how policy decisions affect the operations of these healthcare systems. KPD programs enable patients with living but incompatible donors (referred to as patient-donor pairs) to exchange kidneys with other such pairs in a centrally organized clearing house. Exchanges involving two or more pairs are performed by arranging the pairs in a cycle, where the donor from each pair gives to the patient from the next pair. Alternatively, a so called altruistic donor can be used to initiate a chain of transplants through many pairs, ending on a patient without a willing donor. In recent years, the use of chains has become pervasive in KPD, with chains now accounting for the majority of KPD transplants performed in the United States. A major focus of our work is to understand why long chains have become the dominant method of exchange in KPD, and how to best integrate their use into exchange programs. In particular, we are interested in policies that KPD programs use to determine which exchanges to perform, which we refer to as matching policies. First, we devise a new algorithm using integer programming to maximize the number of transplants performed on a fixed pool of patients, demonstrating that matching policies which must solve this problem are implementable. Second, we evaluate the long run implications of various matching policies, both through high fidelity simulations and analytic models. Most importantly, we find that: (1) using long chains results in more transplants and reduced waiting time, and (2) the policy of maximizing the number of transplants performed each day is as good as any batching policy. Our theoretical results are based on introducing a novel model of a dynamically evolving random graph. The analysis of this model uses classical techniques from Erdos-Renyi random graph theory as well as tools from queueing theory including Lyapunov functions and Little's Law. In the second half of this thesis, we consider the problem of how hospitals should design schedules for their medical residents. These schedules must have capacity to treat all incoming patients, provide quality care, and comply with regulations restricting shift lengths. In 2011, the Accreditation Council for Graduate Medical Education (ACGME) instituted a new set of regulations on duty hours that restrict shift lengths for medical residents. We consider two operational questions for hospitals in light of these new regulations: will there be sufficient staff to admit all incoming patients, and how will the continuity of patient care be affected, particularly in a first day of a patients hospital stay, when such continuity is critical? To address these questions, we built a discrete event simulation tool using historical data from a major academic hospital, and compared several policies relying on both long and short shifts. The simulation tool was used to inform staffing level decisions at the hospital, which was transitioning away from long shifts. Use of the tool led to the following strategic insights. We found that schedules based on shorter more frequent shifts actually led to a larger admitting capacity. At the same time, such schedules generally reduce the continuity of care by most metrics when the departments operate at normal loads. However, in departments which operate at the critical capacity regime, we found that even the continuity of care improved in some metrics for schedules based on shorter shifts, due to a reduction in the use of overtime doctors. We develop an analytically tractable queueing model to capture these insights. The analysis of this model requires analyzing the steady-state behavior of the fluid limit of a queueing system, and proving a so called "interchange of limits" result.
by Ross Michael Anderson.
Ph. D.

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Touraille, Luc. „Application of Model-Driven Engineering and Metaprogramming to DEVS Modeling & Simulation“. Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00914327.

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The multiplication of software environments supporting DEVS Modeling & Simulation is becoming a hindrance to scientific collaboration. Indeed, the use of disparate tools in the community makes the exchange, reuse and comparison of models very difficult, preventing practitioners from building on previous works to devise models of ever-increasing complexity. Tool interoperability is not the only issue raised by the need for models of higher and higher complexity. As models grow, their development becomes more error-prone, and their simulation becomes more resource-consuming. Consequently, it is necessary to devise techniques for improving simulators performance and for providing thorough model verification to assist the practitioner during model design. In this thesis, we propose two innovative approaches for DEVS Modeling & Simulation that tackle the aforementioned issues. The first contribution described in this document is a model-driven environment for modeling systems with the DEVS formalism, named SimStudio. This environment relies on Model-Driven Engineering to provide a high-level framework where practitioners can create, edit and visualize models, and automatically generate multiple artifacts, most notably model specifications compatible with various DEVS simulators. The core of SimStudio is a platform-independent metamodel of the DEVS formalism, which provides a pivot format for DEVS models. Based on this metamodel, we developed several model verification features as well as many model transformations that can be used to automatically generate documentation, diagrams or code targeting various DEVS platforms. Thus, SimStudio gives a proof of concept of the integration capabilities that a DEVS standard would provide; as a matter of fact, the metamodel presented in this thesis could possibly serve as a basis for such a standard. The second contribution of this thesis is DEVS-MetaSimulator (DEVS-MS), a DEVS library relying on metaprogramming to generate simulation executables that are specialized and optimized for the model they handle. To do so, the library performs many computations during compilation, resulting in a simulation code where most overhead have been eliminated. The tests we conducted showed that the generated programs were very efficient, but the performance gain is not the only feature of DEVS-MS. Indeed, through metaprogramming, DEVS-MS can also assert the correctness of models by verifying model characteristics at compile-time, detecting and reporting modeling errors very early in the development cycle and with better confidence than what could be achieved with classical testing.

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Turley, Carole. „Calibration Procedure for a Microscopic Traffic Simulation Model“. Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1747.pdf.

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Lewis, Martin Gary Charles. „Are torque-driven simulation models limited by an assumption of monoarticularity?“ Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/9120.

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Subject-specific forward-dynamics simulation models of human movement incorporating torque generators have typically represented the torque at a joint based on the kinematics of only that joint. Representing the net torque exerted at a joint by considering the kinematics of two joints ought to better represent the torques exerted by the two-joint biarticular muscles. In this study two-joint torque generator representations including monoarticular and biarticular torque components and single-joint torque generator representation of the lower limb were determined for a single male participant using strength measurements collected on an isovelocity dynamometer. For plantar flexion, knee flexion, knee extension torques, a two-joint representation was found to offer better agreement with torques measured on an isovelocity dynamometer than a single joint representation when the joint angle of a secondary joint was changed by 37˚ or more. In addition a two-joint representation should account for the biarticular knee flexor and extensor contributions to hip joint torques. Two subject-specific simulation models of squat jumping, one with single-joint torque generators and another with two-joint torque generators were created to establish the necessity for two-joint torque representation in whole-body simulation models of human movement. Including the two-joint torque generators was shown to provide better agreement with a participant performance than a single-joint torque-driven simulation model. The simulation of a maximal effort human movement should include two-joint torque representations when both of the following characteristics are present in the task to be simulated: a) the task does not have a large initial whole-body momentum; b) the task involves multiple joint kinematics with a large biarticular muscle contribution. A single-joint torque representation was effective when the kinematics of the secondary joint were similar to those which were present during torque measurements. Therefore if the simulated task involves similar kinematics at both joints then a single-joint representation may be sufficient.

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De, Wet Nico. „Model driven communication protocol engineering and simulation based performance analysis using UML 2.0“. Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/6392.

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Includes bibliographical references.
The automated functional and performance analysis of communication systems specified with some Formal Description Technique has long been the goal of telecommunication engineers. In the past SDL and Petri nets have been the most popular FDT's for the purpose. With the growth in popularity of UML the most obvious question to ask is whether one can translate one or more UML diagrams describing a system to a performance model. Until the advent of UML 2.0, that has been an impossible task since the semantics were not clear. Even though the UML semantics are still not clear for the purpose, with UML 2.0 now released and using ITU recommendation Z.109, we describe in this dissertation a methodology and tool called proSPEX (protocol Software Performance Engineering using XMI), for the design and performance analysis of communication protocols specified with UML.

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Ahmad, Aftab. „Effective development of haptic devices using a model-based and simulation-driven design approach“. Doctoral thesis, KTH, Maskinkonstruktion (Avd.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-144216.

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Virtual reality (VR)-based surgical simulators using haptic devices can increase the effectiveness of surgical training for surgeons when performing surgical procedures in hard tissues such as bones or teeth milling. The realism of virtual surgery through a surgical simulator depends largely on the precision and reliability of the haptic device, which reflects the interaction with the virtual model. The quality of perceptiveness (sensation, force/torque) depends on the design of the haptic device, which presents a complex design space due to its multi-criteria and conflicting character of functional and performance requirements. These requirements include high stiffness, large workspace, high manipulability, small inertia, low friction, high transparency, and cost constraints. This thesis proposes a design methodology to improve the realism of force/torque feedback from the VR-based surgical simulator while fulfilling end-user requirements. The main contributions of this thesis are: 1. The development of a model-based and simulation-driven design methodology, where one starts from an abstract, top-level model that is extended via stepwise refinements and design space exploration into a detailed and integrated systems model that can be physically realized. 2. A methodology for creating an analytical and compact model of the quasi-static stiffness of a haptic device, which considers the stiffness of actuation systems, flexible links and passive joints. 3. A robust design optimization approach to find the optimal numerical values for a set of design parameters to maximize the kinematic, dynamic and kinetostatic performances of a 6-degrees of freedom (DOF) haptic device, while minimizing its sensitivity to variations in manufacturing tolerances and cost, and also satisfying the allowed variations in the performance indices. 4. A cost-effective approach for force/torque feedback control using force/torque estimated through a recursive least squares estimation. 5. A model-based control strategy to increase transparency and fidelity of force/torque feedback from the device by compensating for the natural dynamics of the device, friction in joints, gravity of platform, and elastic deformations.

QC 20140415

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Xie, Xuping. „Large Eddy Simulation Reduced Order Models“. Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77626.

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This dissertation uses spatial filtering to develop a large eddy simulation reduced order model (LES-ROM) framework for fluid flows. Proper orthogonal decomposition is utilized to extract the dominant spatial structures of the system. Within the general LES-ROM framework, two approaches are proposed to address the celebrated ROM closure problem. No phenomenological arguments (e.g., of eddy viscosity type) are used to develop these new ROM closure models. The first novel model is the approximate deconvolution ROM (AD-ROM), which uses methods from image processing and inverse problems to solve the ROM closure problem. The AD-ROM is investigated in the numerical simulation of a 3D flow past a circular cylinder at a Reynolds number $Re=1000$. The AD-ROM generates accurate results without any numerical dissipation mechanism. It also decreases the CPU time of the standard ROM by orders of magnitude. The second new model is the calibrated-filtered ROM (CF-ROM), which is a data-driven ROM. The available full order model results are used offline in an optimization problem to calibrate the ROM subfilter-scale stress tensor. The resulting CF-ROM is tested numerically in the simulation of the 1D Burgers equation with a small diffusion parameter. The numerical results show that the CF-ROM is more efficient than and as accurate as state-of-the-art ROM closure models.
Ph. D.

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Price, Jeremy C., und Michael S. Moore. „NETGEN: A MODEL-DRIVEN TOOL FOR RAPID PROTOTYPING AND SIMULATION OF NETWORK-BASED FLIGHT TEST SYSTEMS“. International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604528.

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ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada
When network-centric flight test system components are developed concurrently, it is necessary to produce relevant simulated network traffic for exercising the network devices and other processing subsystems prior to system integration. Having an accurate and repeatable pattern of simulated network traffic is extremely important for debugging and subsystem integration. The simulated network traffic must be both representative of the real system and repeatable to aid test efforts. Our solution to this problem was to develop a model-driven network traffic generator – NETGEN. Using NETGEN to resolve errors, stress test, and verify requirements, we have achieved otherwise unattainable correctness, reliability, and success in our systems.

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Thorenz, Carsten. „Model adaptive simulation of multiphase and density driven flow in fractured and porous media“. Hannover : Inst. für Strömungsmechanik und Elektronisches Rechnen im Bauwesen, 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964524406.

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Özbay, Kaan. „A dynamic traffic simulation/assignment model in the context of Advanced Driver Information Systems /“. This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10222009-125053/.

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Neto, Valdemar Vicente Graciano. „A simulation-driven model-based approach for designing software-intensive systems-of-systems architectures“. Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-06072018-110150/.

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Context: Software-intensive systems have been increasingly interoperated forming alliances termed as Systems-of-Systems (SoS). SoS comprises a collection of systems joined to achieve a set of missions that none of the systems can accomplish on its own. Each constituent system keeps its own management, goals, and resources while coordinating within the SoS and adapting to meet SoS goals. Applications of SoS range from traffic control to emergency response and crisis management. As SoS often support critical domains, such systems must be correct by dealing with malfunction or defects and avoiding failures that could cause extensive damage and losses to the users. Problem: Correct SoS operations depend on a precise specification and a rigorous attestation of its operational consistency. However, besides limitations on languages to jointly capture SoS structure and behavior, predictions on the SoS operational consistency rely on constituent systems not totally known at design-time. Therefore, SoS have been developed and deployed without evaluating their operations, since current languages do not support such precision in evaluation. Objectives: This thesis provides solutions founded on a formal architectural description language to support an early evaluation of SoS operation regarding SoS structure and behavior by means of simulations. Contribution: The main contributions of this project comprise (i) a model transformation approach for automatically producing simulation models from SoS software architecture descriptions, combining SoS structure and behavior description in a same solution, (ii) a SoS software architecture evaluation method for SoS operation prediction considering the inherent changes that can occur, (iii) environment modelling and automatic generation of stimuli generators to sustain the SoS simulation, delivering data to feed such simulation, and (iv) a method for the automatic synchronization between the runtime descriptive architecture (changed at runtime due to dynamic architecture) and its original prescriptive architecture based on model discovery and recovery mechanisms and a backward model transformation. Evaluation: We conducted case studies to assess our solutions using Flood Monitoring SoS and Space SoS. Results: Our solutions support a high accuracy to (i) produce fault-free and fully operational simulations for SoS software architectures, (ii) support evaluation and prediction of SoS operation at design-time, (iii) automatically generate stimuli generators to sustain and feed the simulation execution, and (iv) maintain the synchronization between the runtime architecture and the intended version of the SoS architecture. Conclusions: We concluded that the proposed solutions advance the state of the art in SoS software architecture evaluation by offering solutions to predict the SoS operations effectiveness to maintain a continuous operation despite architectural changes, providing more trust for users that futurely shall rely on SoS services.
Contexto: Sistemas intensivos em software tem sido interoperados para formar alianças conhecidas como Sistemas-de-Sistemas (SoS). Domínios de aplicação de SoS variam do controle de tráfego ao gerenciamento de situações de crises e emergência. Devido à criticidade destes domínios, tais sistemas precisam ser confiáveis e robustos, lidando com potenciais defeitos e mal funcionamento, e evitando falhas que poderiam causar ameaças à integridade dos usuários. Problema: O funcionamento correto de um SoS depende da especificação precisa e da garantia rigorosa da consistência de suas operações. Entretanto, além das limitações nas linguagens quanto à especificação de ambos estrutura e comportamento do SoS, prever seu comportamento depende da especificação de constituintes que não são totalmente conhecidos em tempo de projeto e de seu comportamento emergente. Neste sentido, SoS têm sido desenvolvidos e implantados sem a devida avaliação de seus comportamentos, uma vez que as linguagens disponíveis atualmente não dão suporte a uma especificação precisa destes comportamentos. Objetivos: Este projeto de doutorado relata avanços teóricos e práticos fundamentados em uma linguagem de descrição arquitetural formal para permitir a predição e avaliação do comportamento e estrutura dos SoS com base em simulações. Contribuições: As principais contribuições deste projeto envolvem (i) uma transformação de modelos para produzir automaticamente modelos de simulação para descrições de arquitetura de software de SoS, combinando estrutura e comportamento em uma mesma solução, (ii) um método de avaliação de arquitetura de software de SoS para prever o comportamento do SoS considerando sua dinâmica inerente, (iii) modelagem do ambiente e derivação automática de geradores de estímulos entregando dados continuamente e sustentando a execução de simulações de SoS, e (iv) um método para promover a sincronização automática entre modelos descritivos e prescritivos de arquitetura de software de SoS baseados em mecanismos de descoberta e recuperação de modelos, e transformação de modelos reversa. Avaliação: Estudos de caso foram conduzidos para avaliar as soluções nos domínios de Monitoramento de Enchentes e Espacial. Resultados: As abordagens propostas exibem alta acurácia no que tange (i) a produzir simulações operacionais e sem falhas para arquiteturas de software de SoS, (ii) ao suporte á avaliação, ainda em tempo de projeto, do comportamento que emerge da operação do SoS, (iii) à derivação automática de geradores de estímulos para entrega contínua de dados e manutenção da execução das simulações geradas, e (iv) à manutenção do alinhamento entre os modelos descritivos e prescritivos da arquitetura do SoS avaliado. Conclusões: Conclui-se que as abordagens propostas avançam o estado da arte no projeto de arquiteturas de Software de SoS ao permitir prever, em tempo de projeto, como o SoS vai operar em tempo de execução, permitindo estabelecer estratégias para manter a simulação rodando, e sua operação contínua, mesmo com as mudanças arquiteturais inerentes ao seu funcionamento, provendo mais confiabilidade para os usuários futuramente dependerão de seus serviços.

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Ozbay, Kaan. „A dynamic traffic simulation/assignment model in the context of Advanced Driver Information Systems“. Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/45254.

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Growing congestion problems of many metropolitan areas which cause excessive traffic delay, instability of travel time generated the need for the development of an Intelligent Vehicle Highway System (IVHS) program that is capable of making significant improvements in mobility, highway safety, and productivity on highways and urban streets. The success of such real time control system highly depends on the new methods that address dynamic traffic assignment. Thus there is an urgent need for an effective dynamic assignment model. The main objective of this research is to emphasize the importance of dynamic traffic assignment for Advanced Driver Information Systems (ADIS) which is one of the major components of IVHS and to present a practical traffic assignment model that is capable of running in real time and which can accurately predict link travel times, queue build up, and network performance. DYNTRAS (DYNamic Traffic Simulation Assignment), a simulation /assignment model is developed. The model uses an incremental loop that assigns a portion of the Origin-Destination matrix, and simulates the movement of the vehicles. Then, it updates travel times and assigns an additional portion of the O-D matrix. In contrast to traditional traffic assignment models like "capacity restraint" and “incremental assignment" techniques that do not consider time dimension, DYNTRAS incorporates time as a third dimension by keeping track of the vehicle movements in time. As a result, it is capable of predicting time-dynamic impacts of congestion and effects of diverted traffic on traffic flow more realistically. The model is applied to a test network. “Several experimental factors are varied to test the sensitivity of the model. The results obtained are presented and general conclusions are derived. The differences between dynamic and static traffic assignment results are also discussed by considering results obtained from both methods. The model needs to be calibrated using real traffic data. According to the results obtained, it needs to be validated. In addition, its long computation time should be reduced to be able to use it for real time applications.
Master of Science

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Kiefer, Konstanze. „Simulation of high-cycle fatigue-driven delamination in composites using a cohesive zone model“. Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25155.

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In this PhD thesis several published strategies for the simulation of high-cycle fatigue-driven delamination using cohesive elements are investigated in mode I using an efficient analytical model which eliminates the numerical errors involved in a finite element simulation. A detailed sensitivity study of all the models is performed with respect to the element size and the cycle-jump. The models are then compared and their advantages and disadvantages highlighted. For two of the models improvements are proposed and investigated using the analytical model. Necessary conditions for a successful fatigue model are then highlighted and a new model is proposed. A sensitivity study demonstrates a very good performance of this model. The new fatigue degradation strategy is implemented into a user defined element (UEL) within the commercial finite element software ABAQUS. Two simulations are then performed for pure mode I and mode II fatigue-driven delamination. The new strategy is shown to achieve good agreement with the input Paris law and is also shown to perform well in comparison with FE implementations of some of the published cohesive element strategies for fatigue-driven growth of delamination.

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Burke, Dave. „The mechanics of the contact phase in trampolining“. Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/16744.

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During the takeoff for a trampoline skill the trampolinist should produce sufficient vertical velocity and angular momentum to permit the required skill to be completed in the aerial phase without excessive horizontal travel. The aim of this study was to investigate the optimum technique to produce forward somersault rotation. A seven-segment, subject-specific torque-driven computer simulation model of the takeoff in trampolining was developed in conjunction with a model of the reaction forces exerted on the trampolinist by the trampoline suspension system. The ankle, knee, hip, and shoulder joints were torque-driven, with the metatarsal-phalangeal and elbow joints angle-driven. Kinematic data of trampolining performances were obtained using a Vicon motion capture system. Segmental inertia parameters were calculated from anthropometric measurements. Viscoelastic parameters governing the trampoline were determined by matching an angle-driven model to the performance data. The torque-driven model was matched to the performance data by scaling joint torque parameters from the literature, and varying the activation parameters of the torque generators using a simulated annealing algorithm technique. The torque-driven model with the scaled isometric strength was evaluated by matching the performance data. The evaluation produced close agreement between the simulations and the performance, with an average difference of 4.4% across three forward rotating skills. The model was considered able to accurately represent the motion of a trampolinist in contact with a trampoline and was subsequently used to investigate optimal performance. Optimisations for maximum jump height for different somersaulting skills and maximum rotation potential produced increases in jump height of up to 14% and increases of rotation potential up to 15%. The optimised technique for rotation potential showed greater shoulder flexion during the recoil of the trampoline and for jump height showed greater plantar flexion and later and quicker knee extension before takeoff. Future applications of the model can include investigations into the sensitivity of the model to changes in initial conditions, and activation, strength, and trampoline parameters.

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Filla, Reno. „Operator and Machine Models for Dynamic Simulation of Construction Machinery“. Licentiate thesis, Linköping : Linköpings universitet, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4092.

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40

Koksal, Algin Ceren Fatma. „Ontology Driven Development For Hla Federates“. Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611943/index.pdf.

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This thesis puts forth a process for ontology driven distributed simulation through a case study. Ontology is regarded as a domain model, including objects, attributes, methods and object relations. The case study involves trajectory simulation. A trajectory simulation is a piece of software that calculates the flight path and other parameters of a munition, such as its orientation and angular rates, from launch to impact. Formal specification of trajectory simulation domain is available as a domain model in the form of an ontology, called Trajectory Simulation ONTology (TSONT). Ontology driven federation development process proposed in this thesis is executed in three steps. The first step is to analyze the TSONT and to create instances of individuals guided by the requirements of the targeted simulation application, called Puma Trajectory Simulation. Puma is the simulation of a ficticious air-to-ground guided bomb. The second step is to create the High Level Architecture(HLA) Federation Object Model (FOM) using Puma Simulation individuals. FOM will include the required object and interaction definitions to enable information exchange among federation members, including the Puma federate and the Exercise Manager federate. Transformation from the ontology to FOM is realized in two ways: manually, and by using a tool called OWL2OMT. The third step is to implement the Trajectory Simulation federation based on the constructed FOM. Thus, the applicability of developing HLA federates and the federation under the guidance of ontology is demonstrated.

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41

Higgs, Bryan James. „Emotional Impacts on Driver Behavior: An Emo-Psychophysical Car-Following Model“. Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64901.

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This research effort aims to create a new car-following model that accounts for the effects of emotion on driver behavior. This research effort is divided into eight research milestones: (1) the development of a segmentation and clustering algorithm to perform new investigations into driver behavior; (2) the finding that driver behavior is different between drivers, between car-following periods, and within a car-following period; (3) the finding that there are patterns in the distribution of driving behaviors; (4) the finding that driving states can result in different driving actions and that the same driving action can be the result of multiple driving states; (5) the finding that the performance of car-following models can be improved by calibration to state-action clusters; (6) the development of a psychophysiological driving simulator study; (7) the finding that the distribution of driving behavior is affected by emotional states; and (8) the development of a car-following model that incorporates the influence of emotions.
Ph. D.

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42

Ohiero, Peter Obongha. „Development of fast multi-system simulation models for permanent magnet synchronous motor and generator drive systems“. Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6585/.

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This research project investigates the development and validation of alternative simulation models for voltage source inverter fed permanent magnet synchronous machine drive systems which can rapidly and accurately analyse and evaluate the performance of PM machine drives and associated control system designs. Traditionally simulations have been conducted using switching models and state space average value methods. The simulation of switching models is time consuming and that of state space averaging involves complex mathematical transformation to d-q axis, with additional circuitry and this limits their application in a time critical design process. Even if the complex calculations of state space are overcome, the proposed model can still achieve better results. This thesis presents the development of fast multi system simulation models for permanent magnet synchronous motor and generator drive systems. The fast simulation model: Average Voltage Estimation Model (AVEM) was developed for two-level, three phase VSI-fed PMSM drive systems and two-level three phase full-scale back-back VSI incorporated in a PMSG wind energy conversion system. The method uses the principle of control strategy and switching function to derive the average phase voltage in one switching period and then uses the average voltages to drive piecewise-linear voltage sources across the terminals of the permanent magnet synchronous machine and three phase system. A voltage source inverter loss model was also developed and incorporated into the AVEM to simulate the drive system power flow and its performance evaluated. The average voltage estimation model is also used to estimate and simulate the energy output of the variable speed PMSG wind energy conversion system. Practical implementation of this technique is achieved using a DSP based controller and validation made through comparison of the DSP AVEM energy estimation method with calculated energy. The study also presents the development of detailed VSI switching models for a variable speed PMSM and a PMSG wind energy conversion system which serve as benchmarks for the proposed AVEM models. A detailed description of both models will be presented. Since models require a control strategy: these control strategies were also developed using the carrier-based sinusoidal (SPWM) and implemented with PI regulators. In the permanent magnet synchronous generator wind energy conversion system application, the SPWM is applied to control the speed of the generator side converter to track maximum power as wind speed varies using the developed passive MPPT control technique and controls the AC load side converter to maintained constant DC link voltage. The sinusoidal PWM control provides a simplified control suitable for the variable speed PMSM drive system and the PMSG wind energy conversion system. Lastly, this thesis presents a detailed development of an experimental test rig. The test rig is developed to provide flexibility for the validation and comparison of the results of both simulation models against real practical implementations for PMSM drive system and PMSG wind energy conversions system. Several simulation case studies were performed using the PORTUNUS simulation package to validate and analyse the steady state accuracy of the proposed average voltage estimation model and control system against the switching model. Experiments were also carried out to validate the results of the simulation models. The simulation models results are presented and compared with experimental results. Suitable steady state performance analysis of two-level, three phase voltage source inverter fed permanent magnet synchronous motor and two-level three phase full scale back-back voltage source inverter with permanent magnet synchronous generator drive simulation and experimental performance are also carried out. The results show good agreement of the proposed average voltage estimation model with the switching model and experimental data, and where necessary the reasons for differences are discussed. The simulation of the AVEM is approximately 50 times faster than the switching model. The limitation of the proposed model is also discussed; mainly it cannot be used for the study and analysis of the internal dynamics of the voltage source inverter. The results from the proposed modelling method utilising the average voltage estimation confirm that this method can be used as an alternative to the detailed switching model for fast simulation and steady state analysis of PM machine drive systems given the advantages of speed, simplicity and ease of implementation. Note that the proposed model is only used for steady state performance analysis; however, in future its application can be extended to transient analysis. In addition, the model is not about maximium power point tracking techniques but it can accommodate maximium power point tracking techniques. It should also be highlighted that exactly the same digital control block is used in both the switching and AVEM models thus allowing a true comparison of controller behaviour. The model developed in this research project has application beyond PMSM drive system and PMSG wind energy conversion system. It can be applied to modelling, simulation and control of other electrical machine drives such as induction machines, switched reluctance machines and three-phase VSI-fed systems.

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Sturrock, Zoe. „Numerical simulations of sunspot rotation driven by magnetic flux emergence“. Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/10129.

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Magnetic flux continually emerges from the Sun, rising through the solar interior, emerging at the photosphere in the form of sunspots and expanding into the atmosphere. Observations of sunspot rotations have been reported for over a century and are often accompanied by solar eruptions and flaring activity. In this thesis, we present 3D numerical simulations of the emergence of twisted flux tubes from the uppermost layers of the solar interior, examining the rotational movements of sunspots in the photospheric plane. The basic experiment introduces the mechanism and characteristics of sunspot rotation by a clear calculation of rotation angle, vorticity, magnetic helicity and energy, whereby we find an untwisting of the interior portion of the field, accompanied by an injection of twist into the atmospheric field. We extend this model by altering the initial field strength and twist of the sub-photospheric tube. This comparison reveals the rotation angle, helicity and current show a direct dependence on field strength. An increase in field strength increases the rotation angle, the length of fieldlines extending into the atmosphere, and the magnetic energy transported to the atmosphere. The fieldline length is crucial as we predict the twist per unit length equilibrates to a lower value on longer fieldlines, and hence possesses a larger rotation angle. No such direct dependence is found when varying the twist but there is a clear ordering in rotation angle, helicity, and energy, with more highly twisted tubes undergoing larger rotation angles. We believe the final angle of rotation is reached when the system achieves a constant degree of twist along the length of fieldlines. By extrapolating the size of the modelled active region, we find rotation angles and rates comparable with those observed. In addition, we explore sunspot rotation caused by sub-photospheric velocities twisting the footpoints of flux tubes.

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Pop, Adrian. „Integrated Model-Driven Development Environments for Equation-Based Object-Oriented Languages“. Doctoral thesis, Linköping : Department of Computer and Information Science, Linköpings universitet, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11416.

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Sumi, Selina Jahan. „Eco-Hydrology Driven Evaluation of Statistically Downscaled Precipitation CMIP5 Climate Model Simulations over Louisiana“. Thesis, University of Louisiana at Lafayette, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1594512.

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Statistically downscaled CMIP5 precipitation data are available at higher spatial resolution compared to global climate models. The downscaled climate models have been used in many hydrological applications. However, limited numbers of studies focused on downscaled CMIP5 precipitation data for Louisiana. Statistically downscaled precipitation data for Louisiana is critically needed for various water resources engineering, planning and design purposes. This study has focused on assessing the skill of CMIP5 climate models in reproducing observed precipitation of Louisiana and application of CMIP5 precipitation data to analyze the impact of precipitation on hydrology (salinity and water level). Assessment of CMIP5 precipitation showed that statistically downscaled and bias corrected precipitation data reproduce observed average annual precipitation. But for other statistics (standard deviation), model data are not the same as observation data. The bias correction procedure ensured that models would reproduce the observed average precipitation. The maps of correlation distance for the models do not match with that of observation. This may be an indication that bias correction does not force the model to perform better in all statistics except annual average. Based on the analysis over climate divisions, it can be stated that spatial and temporal aggregation enables the models to perform better than gridded dataset. Application of CMIP5 precipitation data indicates that precipitation has a significant effect on salinity and almost zero effect on water level. Different salinity variables control the hydrologic and habitat suitability indices in coastal Louisiana. The cell-based analysis shows that different variables have different degrees of effect on vegetation and species (brown shrimp and oyster). Some species thrive in a high salinity environment while some others in low salinity. The uncertainty in the salinity and water level may occur due to insufficient data and boundary conditions provided in the Eco-hydrology model environment.

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Braghieri, Giovanni. „Application of robust nonlinear model predictive control to simulating the control behaviour of a racing driver“. Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/275524.

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The work undertaken in this research aims to develop a mathematical model which can replicate the behaviour of a racing driver controlling a vehicle at its handling limit. Most of the models proposed in the literature assume a perfect driver. A formulation taking human limitations into account would serve as a design and simulation tool for the automotive sector. A nonlinear vehicle model with five degrees of freedom under the action of external disturbances controlled by a Linear Quadratic Regulator (LQR) is first proposed to assess the validity of state variances as stability metrics. Comparison to existing stability and controllability criteria indicates that this novel metric can provide meaningful insights into vehicle performance. The LQR however, fails to stabilise the vehicle as tyres saturate. The formulation is extended to improve its robustness. Full nonlinear optimisation with direct transcription is used to derive a controller that can stabilise a vehicle at the handling limit under the action of disturbances. The careful choice of discretisation method and track description allow for reduced computing times. The performance of the controller is assessed using two vehicle configurations, Understeered and Oversteered, in scenarios characterised by increasing levels of non- linearity and geometrical complexity. All tests confirm that vehicles can be stabilised at the handling limit. Parameter studies are also carried out to reveal key aspects of the driving strategy. The driver model is validated against Driver In The Loop simulations for simple and complex manoeuvres. The analysis of experimental data led to the proposal of a novel driving strategy. Driver randomness is modelled as an external disturbance in the driver Neuromuscular System. The statistics of states and controls are found to be in good agreement. The prediction capabilities of the controller can be considered satisfactory.

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Svensson, Marcus, und Daniel Haraldsson. „Integrating Design Optimization in the Development Process using Simulation Driven Design“. Thesis, Linköpings universitet, Maskinkonstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157374.

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This master thesis has been executed at Scania CV AB in Södertälje, Sweden. Scania is a manufacturer of heavy transport solutions, an industry which is changing rapidly in order to meet stricter regulations, ensuring a sustainable future. Continuous product improvements and new technologies are required to increase performance and to meet markets requirements. By implementing design optimization in the design process it enables the potential of supporting design exploration, which is beneficial when products with high performance are developed. The purpose was to show the potential of design optimization supported by simulation driven design as a tool in the development process. To examine an alternative way of working for design engineers, elaborating more competitive products in terms of economical and performance aspects. Furthermore, to minimize time and iterations between divisions by developing better initial concept proposals. The alternative working method was developed iteratively in parallel with a case study. The case study was a suction strainer and were used for method improvements and validation, as well as decision basis for the included sub-steps. The working method for implementing design optimization and simulation driven design ended up with a procedure consisted of three main phases, concept generation, detail design and verification. In the concept generation phase topology optimization was used, which turned out to be a beneficial method to find optimized solutions with few inputs. The detail design phase consisted of a parameterized CAD model of the concept which then was shape optimized. The shape optimization enabled design exploration of the concept which generated valuable findings to the product development. Lastly the optimized design was verified with more thorough methods, in this case verification with FE-experts. The working method was tested and verified on the case study component, this resulted in valuable knowledge for future designs for similar components. The optimized component resulted in a performance increase where the weight was decrease by 54% compared with a reference product.

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Xu, Ying. „TWO-DIMENSIONAL SIMULATION OF SOLIDIFICATION IN FLOW FIELD USING PHASE-FIELD MODEL|MULTISCALE METHOD IMPLEMENTATION“. Lexington, Ky. : [University of Kentucky Libraries], 2006. http://lib.uky.edu/ETD/ukymeen2006d00524/YingXu_Dissertation_2006.pdf.

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Thesis (Ph. D.)--University of Kentucky, 2006.
Title from document title page (viewed on January 25, 2007). Document formatted into pages; contains: xiii, 162 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 151-157).

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Wilkerson, Jaxon. „Handoff of Advanced Driver Assistance Systems (ADAS) using a Driver-in-the-Loop Simulator and Model Predictive Control (MPC)“. The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595262540712316.

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Erlandsson, Andreas. „Simulation driven design : An iterative approach for mechanical engineers with focus on modal analysis“. Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-28980.

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This thesis of 15 hp has been implemented at Halmstad University, in collaboration with Saab Dynamics in Linköping. Saab Dynamics is a company operating in the defence industry where competition is tough. This necessitates new ways to increase efficiency in the company, which is the basis for this thesis. Saab Dynamics wants to introduce simulation driven design. Since Saab Dynamics engineers have little experience of simulation, required a user methodology with clear guidelines. Due to lack of time, they chose to assign the task to students, which resulted in this thesis. The aim of the thesis is to develop a methodology in mechanical design, where the designer uses the FE analysis early in the design process to develop the structures' mechanical properties. The methodology should be seen as a guide and a source of information to enable an iterative approach with FE-analysis, which is the basis of simulation-driven design. The iterative process of simulation driven design, which can lead to reduced lead times and cost savings in the design process. The work was carried out by three students from the mechanical engineering program between December 2014 and May 2015. Because of the scale of the project, it has been carried out by a total of three students with individual focus areas. The work has followed a self-developed method and the project began with theoretical studies of the topic to get an understanding of what has been done and what research in simulation driven design. Then conducted an empirical study on the Saab Dynamics in Linköping, in order to increase understanding of how the design process looks like. Meanwhile, sustainable development and ethical aspects has been taken into account. Much time has been devoted to investigate the possibilities and limitations of 3D Experience, which is Dassault Systèmes latest platform for 3D modelling- and simulation software. 3D Experience is the software, the methodology is based on. This thesis has resulted in a methodology for simulating at the designer level that the project team in consultation with the supervisor at Saab Dynamics managed to adapt to the company's requirements.

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