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Legrand, Juliette. "Simulation and assessment of multivariate extreme models for environmental data." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASJ015.
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L'estimation précise des probabilités d'occurrence des événements extrêmes environnementaux est une préoccupation majeure dans l'évaluation des risques. Pour l'ingénierie côtière par exemple, le dimensionnement de structures implantées sur ou à proximité des côtes doit être tel qu'elles résistent aux événements les plus sévères qu'elles puissent rencontrer au cours de leur vie. Cette thèse porte sur la simulation d'événements extrêmes multivariés, motivée par des applications aux hauteurs significatives de vagues, et sur l'évaluation de modèles de prédiction d'occurrence d'événements extrêmes.Dans la première partie du manuscrit, nous proposons et étudions un simulateur stochastique qui génère conjointement, en fonction de certaines conditions d'état de mer au large, des extrêmes de hauteur significative de vagues (Hs) au large et à la côte. Pour cela, nous nous appuyons sur l'approche par dépassements de seuils bivariés et nous développons un algorithme de simulation non-paramétrique de lois de Pareto généralisées bivariées. À partir de ce simulateur d'événements cooccurrents, nous dérivons un modèle de simulation conditionnel. Les deux algorithmes de simulation sont mis en oeuvre sur des expériences numériques et appliqués aux extrêmes de Hs près des côtes bretonnes françaises. Un autre développement est traité quant à la modélisation des lois marginales des Hs. Afin de prendre en compte leur non-stationnaritée, nous adaptons une extension de la loi de Pareto généralisée, en considérant l'effet de la période et de la direction pic sur ses paramètres.La deuxième partie de cette thèse apporte un développement plus théorique. Pour évaluer différents modèles de prédiction d'extrêmes, nous étudions le cas spécifique des classifieurs binaires, qui constituent la forme la plus simple de prévision et de processus décisionnel : un événement extrême s'est produit ou ne s'est pas produit. Des fonctions de risque adaptées à la classification binaire d'événements extrêmes sont développées, ce qui nous permet de répondre à notre deuxième question. Leurs propriétés sont établies dans le cadre de la variation régulière multivariée et de la variation régulière cachée, permettant de considérer des formes plus fines d'indépendance asymptotique. Ces développements sont ensuite appliqués aux débits de rivière extrêmes<br>Accurate estimation of the occurrence probabilities of extreme environmental events is a major issue for risk assessment. For example, in coastal engineering, the design of structures installed at or near the coasts must be such that they can withstand the most severe events they may encounter in their lifetime. This thesis focuses on the simulation of multivariate extremes, motivated by applications to significant wave height, and on the evaluation of models predicting the occurrences of extreme events.In the first part of the manuscript, we propose and study a stochastic simulator that, given offshore conditions, produces jointly offshore and coastal extreme significant wave heights (Hs). We rely on bivariate Peaks over Threshold and develop a non-parametric simulation scheme of bivariate generalised Pareto distributions. From such joint simulator, we derive a conditional simulation model. Both simulation algorithms are applied to numerical experiments and to extreme Hs near the French Brittanny coast. A further development is addressed regarding the marginal modelling of Hs. To take into account non-stationarities, we adapt the extended generalised Pareto model, letting the marginal parameters vary with the peak period and the peak direction.The second part of this thesis provides a more theoretical development. To evaluate different prediction models for extremes, we study the specific case of binary classifiers, which are the simplest type of forecasting and decision-making situation: an extreme event did or did not occur. Risk functions adapted to binary classifiers of extreme events are developed, answering our second question. Their properties are derived under the framework of multivariate regular variation and hidden regular variation, allowing to handle finer types of asymptotic independence. This framework is applied to extreme river discharges
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Li, Qinglan 1971. "Statistical downscaling and simulation of daily temperature extremes." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99521.
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There is now a broad scientific consensus that the global climate is changing in ways that could have a profound impact on human society and the natural environment over the coming decades. In particular, changes in the frequency and magnitude of extreme temperatures are likely to have more substantial impacts on the environment and human activities than changes in the mean temperature. The present study is therefore addressing three main objectives: (a) to propose a systematic data analysis method for characterizing the variability of daily extreme temperatures at different sites; (b) to develop new statistical downscaling models that could accurately describe the linkage between large-scale climate variables and the characteristics of temperature extremes at a local site; and (c) to develop a stochastic method for simulating accurately the extreme temperature processes.<br>Firstly, a systematic data analysis procedure was proposed for analyzing the variability of daily maximum (Tmax) and minimum (Tmin) temperature characteristics. The suggested procedure consists of performing a detailed statistical analysis of twelve relevant temperature indices that are important for various practical application purposes: mean of diurnal temperature range, frost season length, growing season length, freeze and thaw cycle, 90th percentile of Tmax, 10th percentile of Tmin, means and standard deviations of Tmax, Tmin, and the daily mean temperature. The suggested method was applied to the analysis of daily Tmax and Tmin data for 20 stations in Quebec. The available records used are different from station to station, varying from 44 years to 107 years. In general, it was found that, depending on the temperature index considered as well as on the particular season of the year, there are some significant increasing or decreasing trends at some locations in Quebec. Results of this analysis would provide valuable information on the temporal and spatial variations of daily extreme temperature processes in the region. Furthermore, it can be observed that no systematic spatial variability of the increasing or decreasing trends of any of the twelve temperature indices considered could be identified for a given area in Quebec.<br>Secondly, two new statistical downscaling models were proposed using the stepwise and robust regression methods in order to describe the linkage between largescale climate variables and the characteristics of Tmax and Tmin at a local site. The performance of these two models was tested using daily extreme temperature data available at Dorval Airport station in Quebec and the NCEP data for 25 different climate variables for the 1961-1990 period. It was found that the proposed stepwise and robust regression downscaling models can provide accurate estimates of fundamental statistical and physical properties of Tmax and Tmin. In addition, it has been observed that three climate variables, the mean sea level pressure, the 850hPa-geopotential height, and the near surface specific humidity, had the most significant effect on Tmax and Tmin at Dorval Airport. Furthermore, as compared with the popular SDSM model, the stepwise and robust regression models can provide more accurate estimates of the local Tmax and Tmin characteristics. In particular, the robust regression model was found to be the most accurate.<br>Finally, a new stochastic simulation procedure was developed in this study for simulating the Tmax and Tmin temperature time series at a local site using the combination of the first-order autoregressive AR(1) model and the SVD technique. Results of the evaluation of the proposed AR(1)-SVD simulation method using daily extreme temperature data at Dorval Airport for the 1961-1990 period have indicated the feasibility of this method in describing accurately the observed basic statistical properties (mean, standard deviation, and first order autocorrelation) of the daily Tmax and Tmin time series at a local site.
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Oesting, Marco [Verfasser]. "Analysis and simulation of multivariate and spatial extremes / Marco Oesting." Siegen : Universitätsbibliothek der Universität Siegen, 2019. http://d-nb.info/1238353541/34.
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Casson, Edward Anthony. "Stochastic methodology for the extremes and directionality of meteorological processes." Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287095.
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Wu, Elizabeth. "Spatio-Temporal Data Mining and Analysis of Precipitation Extremes." Thesis, The University of Sydney, 2008. https://hdl.handle.net/2123/28120.
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The work in this thesis aimed to discover new ways to analyse and mine information about precipitation extremes in South America from spatio-temporal data. This was done in two ways. First, analysis was performed through the use of statistical measures that provided insight into the behaviour of precipitation extremes between regions. Second, a new spatio-temporal outlier detection algorithm was introduced to discover moving outliers from the data.
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VanLandingham, Steve. "Applications of Joint Tactical Simulation modeling." Thesis, Monterey, California. Naval Postgraduate School, 1997. http://hdl.handle.net/10945/7975.
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Approved for public release; distribution is unlimited<br>Advances in technology allow Computer Simulation Models (CSM) to be used as a powerful tool to aid military decision makers. This thesis explores the usefulness of one of these models, the Joint Tactical Simulation (JTS). First, this thesis outlines the information and tasks required to run JTS, which will give the reader a basic understanding of the program and how much effort it requires. Next, it describes the scenario presented in this thesis by detailing the methodology of terrain development, listing the assets required and the mission concept employed. It concludes by discussing some of the advantages and disadvantages of JTS followed by a reevaluation of the simulation and its possible uses. The concluding appendix is a tutorial that guides the reader through an amphibious assault modeled on the UNIX-based computer systems at the Naval Postgraduate School's (NPS) Secure Systems Technology Laboratory. It was designed to be accomplished in less than four hours and give the user an opportunity to run a simulation while conducting minimal interaction
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Revel, Aldric. "Nuclear forces at the extremes." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC227/document.
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L’émission de paires de neutrons par les noyaux riches en neutrons 18C et 20O (isotones N = 12) est étudié par réactions de knock-out d’un nucléon des faisceaux secondaires 19N et 21O, peuplant ainsi des états non liés jusqu’à 15 MeV au-dessus de leur seuil d’émission deux neutrons. L’analyse des corrélations des triples coïncidences fragment+n+n montre que la décroissance 19N(−1p)→18C → 16C+n+n est clairement dominée par l’émission directe de paires. Les corrélations n-n, les plus grandes jamais observées, suggèrent la prédominance d’un coeur de 14C entouré de quatre neutrons arrangés en paires très corrélées. De plus, une importante compétition du mode de décroissance séquentiel est observée dans la décroissance 21O(−1n) → 20O → 18O+n+n, interprétée par la déformation causée par le knock-out d’un neutron très lié ayant pour effet de casser le cœur de 16O et ainsi de réduire le nombre de paires.De plus, les états non liés du 26F et 28F sont étudiés. Les deux systèmes étant peuplés par knock-out d’un nucléon du 27F dans le cas du 26F et du 29Ne ou du 29F pour 28F. Cinq états ont été observés pour 26F avec en particulier l’état de plus basse énergie (0.39 MeV) identifié comme l’état 3+ résultant du couplage d5/2 ⊗ d3/2 . Pour 28F, cinq états ont aussi été observés et l’état fondamental (200 keV) a été identifié comme étant de parité négative, plaçant ainsi 28F dans l’îlot d’inversion<br>The emission of neutron pairs from the neutron-rich N = 12 isotones 18C and 20O has been studied by high-energy nucleon knockout from 19N and 21O secondary beams, populating unbound states of the two isotones up to 15 MeV above their two-neutron emission thresholds. The analysis of triple fragment-n-n correlations shows that the decay 19N(−1p) → 18C → 16C+n+n is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a 14C core surrounded by four neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay 21O(−1n) → 20O → 18O+n+n, attributed to its formation through the knockout of a deeply-bound neutron that breaks the 16O core and reduces the number of pairs.Moreover, unbound states in 26F and 28F have been studied. The two systems were probed using single-nucleon knockout reaction from secondary beams of 27F respectively in the case of 26F, and 29Ne and 29F for 28F. Five possible states have been identified in 26F, with in particular the lowest energy one (0.39 MeV) being identified as the 3+ state resulting from the d5/2 ⊗ d3/2 coupling. In the case of 28F, five unbound state have also been observed and in particular its ground state (200 keV) has been identified as a negative parity state, meaning that 28F is located inside the island of inversion
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Nykänen, Robin. "Simulation of Bolted Joint with Frictional Contacts." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74490.
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An easy and reliable way to join two or more components is to use a bolted joint. When torque is applied on the bolt head, a clamp force is achieved. However about 90% of this torque will be used just to overcome the friction in the interfaces. To be able to fasten these in an ecient and precise manner the friction in the bolt threads and underhead area is important to understand. This is currently investigated at Atlas Copco by using a friction test rig, FTR, which measures the clamp force, the total torque and the shank torque. To evaluate the test rig and also to be able to evaluate dierent friction models, a parameterised simulation model of a bolted joint is built. This is a 3D-model of the joint containing a bolt, a nut and a test specimen. The stiness and frictional behaviour of the FTR is used in the model to get a good comparison between these two. Dierent contact formulations and settings are tested to achieve a good model. Also, mesh size, step size and material models are evaluated to see the eect of these. The results show a good correlation between the FTR data and the simulation model. For the total torque to clamp force ratio a dierence of about 1% is achieved. The average dierence in shank torque and underhead torque is at 3.1% and -1.6% respectively. The pressure distribution for this model is shown to be unevenly distributed along the threads. This is minimized by softening the contact, but this instead increases the error between the FTR data and the simulation model. For the evaluation of friction models that are based on the contact pressure this needs to be investigated further to nd a good compromise between the contact pressure and the frictional behaviour.
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Sullivan, Mark James. "A methodology for evaluating a joint mobilizatoin plan using the Joint Theater Level Simulation (JTLS)." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA321112.
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Boucher, Alexandre. "Conditional joint simulation of random fields on block-support /." St. Lucia, Qld, 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17169.pdf.
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Bei, Yanhong. "Dynamic simulation of knee joint contact during human movement." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0002364.
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Griph, Sofie. "Electric Motor Controlled Joint Simulator." Thesis, Linköpings universitet, Reglerteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129753.
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Tightening systems are used in several industries, including assembly in the auto- motive industry and installation of computer hardware. Both the company mak- ing the tools and the customers need to know the performance of the tightening system to ensure that the screw joints tighten as desired. This can be done using a test joint system. High demands on safety as well as fast assembly speeds, puts high demands on the test equipment. The problem with the existing test joints is that they are hard to do repeatable tests on. The most common test joints are constructed us- ing mechanic or hydraulic systems. The mechanical systems have problems with wear of screws, changes in lubrication etc., while the hydraulic systems some- times are too slow. This master’s thesis is a study of whether it would be possible to construct a test joint using an electric motor. The electric motor together with a controller should simulate a screw joint so that the tool would perceive it as a real one. All investigation has been performed by system modeling and simulations in MATLAB. Four different control structures have been evaluated: a PID controller, one combined controller which uses feedforward from reference as well as distur- bance, one which is based on the same structure as the second but with an added inner current loop and the last one is an LQ controller. The conclusion is that it is possible to make a test joint using an electric motor and that the LQ controller seems to be the best choice. To prove the result, a few more aspects could be investigated more closely. One is to add a dynamic model of the tool, now only the reference to the tool is used. Another is to implement it on hardware.
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Barrowman, Mary Ann McCullen. "Evaluation of operation plans using the Joint Theater Level Simulation." Thesis, Monterey, California. Naval Postgraduate School, 1985. http://hdl.handle.net/10945/21317.
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Harun, Muhamad Noor. "Computational wear simulation for metal-on-metal hip joint replacement." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444062.
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Starke, Gregory Richard. "Numerical simulation of implant-bone interaction following cementless joint replacement." Doctoral thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/9258.
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Bibliography: leaves 143-154.<br>The advent of cemented joint replacements has revolutionised the management of patients suffering from chronic arthritis. However, establishing a durable bond between the prosthesis and the surrounding bone remains a considerable problem. As a result, cementless implants have been developed. These components rely on the ingrowth of bone into a porous coating, which covers a portion of the component surface, to achieve the required mechanical interlock. Once mineralised bone tissue has formed within .the porous surface, a stable bond results which will be maintained by the normal bone turnover processes, thereby providing long term attachment. However, one of the problems associated with the use of cementless implants is the unpredictability of the extent of bone ingrowth. The process of osseo-integration is greatly influenced by the magnitude of the micro-motion between the implant and the surrounding bone. Large movements inhibit ingrowth, and may result in the formation of an interfacial fibrous tissue layer. In addition, interface strains will influence the early repair process and guide long term bone remodelling within this region. A numerical model for the prediction of bone formation within the porous surface has been developed. The evolution laws consider the early repair activity, possible fibrous tissue formation, and long term remodelling, as a function of the history of inelastic relative displacements and elastic interface strains. The model is based on the development of an isoparametric interface element, which is suitable for implementation into a non-linear finite element code. In the unbonded condition, the contact is governed by a Coulomb friction formulation. The position and shape of the Coulomb yield surface is altered according to the evolution equations, which govern the development of mineralised tissue within the surface porosity. The strain history and post-operative time are then used to develop a stimulus coefficient, which determines the course of the interface tissue development. If bone tissue is predicted, the subsequent interfacial material will be governed by a remodelling algorithm for the prediction of the long term response. If the bond strength is exceeded, fracture occurs and the joint may open or slide, thus returning to its original, unbonded, state. In the event of large micro-motions, the yield surface and material formulation are altered to include fibrous tissue. The model is used to predict the development of interfacial tissues at the porous surface of a tibial tray component, with a central peg and a PCA (Howmedica, Inc.) femoral stem. Although many factors influence interfacial tissue development, mechanical loads are assumed to be dominant. In the short term, the relationship between micro-motion and interface tissue response has been shown. However, long term remodelling of interfacial tissues has not been widely demonstrated and, therefore, additional experimental data is required to validate the current long term remodelling predictions.
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Bull, Anthony Michael James. "Measurement and computer simulation of knee kinematics." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/8379.
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Cwick, Mark J. "Analysing amphibious logistics capabilities in the Joint Theater Level Simulation (JTLS)." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA319408.
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Thesis (M.S. in Operations Research) Naval Postgraduate School, September 1996.<br>"September 1996." Thesis advisor(s): S.H. Parry. Includes bibliographical references (p. 61-62). Also available online.
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Knight, Lucy. "Finite elements simulation of surface wear in total knee joint replacement." Thesis, University of Southampton, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500828.
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Dalne, Sarang G. "A Finite Element Simulation of the Temporomandibular Joint of a Pig." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1258727561.
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Wysocki, Stefan. "Joint Euler-Lagrange method for moving surfaces in large-eddy simulation." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10214.
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Continuous growth of computing power strongly encourages engineers to rely more on computational fluid dynamics for the design and testing of new technological solutions. The fast development of these new tools goes along with the increasing availability of high-performance computers, which are necessary to simulate realistic industrial applications. The presented immersed boundary (IB) method is applicable to simple and complex geometries with static and moving boundaries, where fluids interact with the solid structures. The formulation of the method is based on the Eulerian and Lagrangian principles and its key characteristics are its simple formulation and computational efficiency. Furthermore the nature of the method allows the simulations of flows in complex geometries without having to generate complex meshes. The spatial discretization is based on a fixed Cartesian mesh for the Eulerian variables and boundary movements are tracked with Lagrangian particles. Large- Eddy simulations of flows in simple and complex geometries demonstrate the performance of the applied immersed boundary method. Simple cases include the simulation of an isothermal pipe flow and the flow around a sphere. In the first instance, the fluid flows around a static sphere. In the second case the sphere moves relative to the grid for identical flow conditions. Simulations of complex geometries include the investigation of an isothermal and reactive opposed jet flow with perforated and fractal grids. The simulations require cell sizes near the resolution of direct numerical simulations. The injection phase of a piston-cylinder arrangement, assuming constant pressure, is also investigated with the proposed IB method. Good statistical results for first and second moments are achieved for all investigated cases, although the applied grids have to be fine enough to accurately resolve the wall shear stresses. In addition, the concept of using Lagrangian particles has been applied to immiscible flows. Particles are used to improve the accuracy of scalar transport and initial results of simple, two-dimensional test cases are presented.
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Buchta, Christian. "Modeling market scenarios for simulation studies on the joint segmentation and positioning problem." SFB Adaptive Information Systems and Modelling in Economics and Management Science, WU Vienna University of Economics and Business, 1999. http://epub.wu.ac.at/934/1/document.pdf.
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Mazanec, in Baier and Mazanec (1999), suggests a simulation environment for studying joint segmentation/positioning strategies for brands competing in a product class. The simulation operates on three-way data: consumers rate the set of brands on a set of dimensions, compare their perceptual brand profiles to their preferential profile, and make a choice. In the present paper a modeling framework for generation of such market data is suggested. First models of consumers perceptual/preferential positions are discussed. Second a model linking brand perceptions to consumers is suggested where the degree of perceptual competition between brands is explicitly modeled. Third a model linking consumers perceptions and preferences completes the data model from which a simulation can depart. (author's abstract)<br>Series: Working Papers SFB "Adaptive Information Systems and Modelling in Economics and Management Science"
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Carandente, Mario. "FE simulation of the SPR process to predict joint characteristics : innovation report." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/94058/.
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Self-pierce riveting (SPR) is the core joining technology used by Jaguar Land Rover (JLR) to join aluminium & mixed material body in white (BIW). Currently, the application of this process has a serious constraint to the business due to the high investment and intensive labour required by physically testing joint feasibility. This is a critical issue especially where different stacks need to be joined by one SPR gun. In this case, the selection of a common rivet/die combination which suits different material stacks requires labour intensive work that in some cases can create long delays during a vehicle development and commissioning. In this context, the development of a simulation technique, based on Finite Element Analysis (FEA), could allow virtual assessment of the manufacturing feasibility of a joint. This will enable significant business benefits including: saving time, costs and materials requirement for the experimental trials. Three major challenges need to be addressed: short CPU time, accuracy and robustness in order for its application in a manufacturing environment. To achieve these objectives, detailed numerical methods capable of reproducing the key factors affecting the experimental process like tooling, boundary conditions and material plastic deformation are developed. For the first time, a thermo-mechanical finite element model for simulation of the SPR process has been proposed. This allowed consideration of the increase in temperature due to friction and plastic deformation generated during the rivet insertion. The effect of thermal softening and strain hardening were characterized for the development of the substrate material model and their influence on the numerical simulation was assessed. This study has been validated via production line data and a significantly high level of correlation between simulation and experimental data for over 1000 joints representative of a vehicle platform has been achieved. The application of the developed simulation technique will enable several business benefits such as significant reduction of engineering time and costs in contrast to the experimental procedure. These advantages allow a smooth implementation of the SPR process in a JLR production line by providing engineering recommendations rapidly and consistently. All these features, combined with accuracy and robustness have enabled the application of the developed tool into JLR business.
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Dunn, Charles, and Stanley H. Evans. "Network and database design in support of the Joint Theater Level Simulation." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23327.
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The purpose of this thesis was to determine the feasibility of incorporating a Sun Workstation into a Command and Control station to aid players in the execution of their roles in the Joint Theater Level Simulation. This entailed reviewing the possibility of eliminating the Postprocessor from the analysis phase of the game play. The Joint Theater Level Simulation is a theater independent computer game that models two-sided air, ground and naval combat, utilized for warfare training, joint operational and planning and doctrinal analysis. The products of this thesis will interface the Sun Workstation with the wargame's host computer, the VAX-11, to provide the players the capability to access and analyze game data to improve their decision making ability. To meet this end, several software products were produced which specifically interfaced with the VAX-11, Sun Workstation and Ethernet. Theses. (FR)
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Pascucci, Fiammetta. "A Positon Based Approach to Ragdoll Simulation." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9396.
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<p>Create the realistic motion of a character is a very complicated work.</p><p>This thesis aims to create interactive animation for characters in three dimensions using position based approach. Our character is pictured from ragdoll, which is a structure of system particles where all particles are linked by equidistance constraints.</p><p>The goal of this thesis is observed the fall in the space of our ragdoll after creating all constraints, as structure, contact and environment constraints.</p><p>The structure constraint represents all joint constraints which have one, two or three Degree of Freedom (DOF).</p><p>The contact constraints are represented by collisions between our ragdoll and other objects in the space.</p><p>Finally, the environment constraints are represented by means of the wall constraint.</p><p>The achieved results allow to have a realist fall of our ragdoll in the space.</p>
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El-Gohary, Mahmoud Ahmed. "Joint Angle Tracking with Inertial Sensors." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/661.
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The need to characterize normal and pathological human movement has consistently driven researchers to develop new tracking devices and to improve movement analysis systems. Movement has traditionally been captured by either optical, magnetic, mechanical, structured light, or acoustic systems. All of these systems have inherent limitations. Optical systems are costly, require fixed cameras in a controlled environment, and suffer from problems of occlusion. Similarly, acoustic and structured light systems suffer from the occlusion problem. Magnetic and radio frequency systems suffer from electromagnetic disturbances, noise and multipath problems. Mechanical systems have physical constraints that limit the natural body movement. Recently, the availability of low-cost wearable inertial sensors containing accelerometers, gyroscopes, and magnetometers has provided an alternative means to overcome the limitations of other motion capture systems. Inertial sensors can be used to track human movement in and outside of a laboratory, cannot be occluded, and are low cost. To calculate changes in orientation, researchers often integrate the angular velocity. However, a relatively small error or drift in the measured angular velocity leads to large integration errors. This restricts the time of accurate measurement and tracking to a few seconds. To compensate that drift, complementary data from accelerometers and magnetometers are normally integrated in tracking systems that utilize the Kalman filter (KF) or the extended Kalman filter (EKF) to fuse the nonlinear inertial data. Orientation estimates are only accurate for brief moments when the body is not moving and acceleration is only due to gravity. Moreover, success of using magnetometers to compensate drift about the vertical axis is limited by magnetic field disturbance. We combine kinematic models designed for control of robotic arms with state space methods to estimate angles of the human shoulder and elbow using two wireless wearable inertial measurement units. The same method can be used to track movement of other joints using a minimal sensor configuration with one sensor on each segment. Each limb is modeled as one kinematic chain. Velocity and acceleration are recursively tracked and propagated from one limb segment to another using Newton-Euler equations implemented in state space form. To mitigate the effect of sensor drift on the tracking accuracy, our system incorporates natural physical constraints on the range of motion for each joint, models gyroscope and accelerometer random drift, and uses zero-velocity updates. The combined effect of imposing physical constraints on state estimates and modeling the sensor random drift results in superior joint angles estimates. The tracker utilizes the unscented Kalman filter (UKF) which is an improvement to the EKF. This removes the need for linearization of the system equations which introduces tracking errors. We validate the performance of the inertial tracking system over long durations of slow, normal, and fast movements. Joint angles obtained from our inertial tracker are compared to those obtained from an optical tracking system and a high-precision industrial robot arm. Results show an excellent agreement between joint angles estimated by the inertial tracker and those obtained from the two reference systems.
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Sloan, Thomas Douglas. "Repetitive use of Joint Theater Level Simulation (JTLS) for investigation of headquarters effectiveness." Thesis, Monterey, California : Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23105.
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This thesis presents a two-part analysis of excellence criteria for fleet combat replacement squadrons. Part one focuses on the qualitative issues and management techniques identified in outstanding fleet combat replacement squadrons. Part two develops and presents a regression model for predicting a fleet replacement squadron pilot's carrier qualification grade. The model was derived using standard linear regression techniques and the SPSSx software package of the Naval Postgraduate School. CNO (OP-59) sponsored the quantitative portion of the analysis. Approximately 1,300 student aviator training records from fiscal 1986 through 1987 were surveyed to generate the data base for the study. Eleven independent variables were used to predict expected student carrier qualification scores. Two additional models for predicting fleet combat replacement carrier qualification grades and advanced jet training command carrier qualification grades are presented. Functions of the model for a directed detailing capacity were given and additional research topics were recommended. Keywords: Pilot training; Strike aviation training; Predicting carrier qualification success; Excellence; Aviation training; Fleet combat replacement squadron; Carrier qualification
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Lopes, Marcio Ferrao. "Bias-Free Joint Simulation of Multi-Factor Short Rate Models and Discount Factor." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29396.
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This dissertation explores the use of single- and multi-factor Gaussian short rate models for the valuation of interest rate sensitive European options. Specifically, the focus is on deriving the joint distribution of the short rate and the discount factor, so that an exact and unbiased simulation scheme can be derived for risk-neutral valuation. We see that the derivation of the joint distribution remains tractable when working with the class of Gaussian short rate models. The dissertation compares three joint and exact simulation schemes for the short rate and the discount factor in the single-factor case; and two schemes in the multifactor case. We price European floor options and European swaptions using a twofactor Gaussian short rate model and explore the use of variance reduction techniques. We compare the exact and unbiased schemes to other solutions available in the literature: simulating the short rate under the forward measure and approximating the discount factor using quadrature.
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Alsassa, Salma. "Two-dimentional complex modeling of bone and joint infections using agent-based simulation." Thesis, Brest, 2019. http://www.theses.fr/2019BRES0022.
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Le diagnostic et la prise en charge des infections ostéo-articulaires (IOA) sont souvent complexes occasionnant une perte osseuse irréversible. La variabilité intra et inter-patient en terme de présentation clinique rend impossible le recours à une description systématique ou à une analyse statistique pour le diagnostic et l'étude de cette pathologie. Le développement d'IOA résulte d'interactions complexes entre les mécanismes cellulaires et moléculaires du tissu osseux et les bactéries. L'objectif de cette thèse est de modéliser l'IOA afin de simuler le comportement du système suite à des interactions au niveau cellulaire et moléculaire en utilisant l'approche de modélisation à base d'agents. Nous avons utilisé une méthode basée sur l'analyse bibliographique pour extraire les caractéristiques du modèle et les utiliser pour deux aspects. Le premier consiste en l'élaboration de la structure du modèle en identifiant les agents et les interactions, et le deuxième concerne l'estimation quantitative des différents paramètres du modèle. La réponse du système BJI aux différentes tailles d’inoculum bactérien a été simulée par la variation de différents paramètres. L'évolution des agents simulés a ensuite été analysée en utilisant une modélisant par des systèmes dynamiques non linéaires et une méthodologie "Datadriven", grâce auxquelles nous avons décrit le système d'IOA et identifié des relations plausibles entre les agents. Le modèle a réussi à présenter la dynamique des bactéries, des cellules immunitaires innées et des cellules osseuses au cours de la première étape de l'IOA et pour différentes tailles d'inoculum bactérien. La simulation a mis en évidence les conséquences sur le tissu osseux résultant du processus de remodelage osseux au cours de l'IOA. Ces résultats peuvent être considérés comme une base pour une analyse plus approfondie et pour la proposition de différentes hypothèses et scénarios de simulation qui pourraient être étudiés dans ce laboratoire virtuel<br>Bone and joint infections are one of the most challenging bone pathologies that associated with irreversible bone loss and long costly treatment. The high intra and inter patient's variability in terms of clinical presentation makes it impossible to rely on the systematic description or classical statistical analysis for its diagnosis or studying. The development of BJI encompasses a complex interplay between the cellular and molecular mechanisms of the host bone tissue and the infecting bacteria. The objective of this thesis is to provide a novel computational modeling framework that simulates the behavior resulting from the interactions on the cellular and molecular levels to explore the BJI dynamics qualitatively and comprehensively, using an agent-based modeling approach. We relied on a meta-analysis-like method to extract the quantitative and qualitative data from the literature and used it for two aspects. First, elaborating the structure of the model by identifying the agents and the interactions, and second estimating quantitatively the different parameters of the model. The BJI system’s response to different microbial inoculum sizes was simulated with respect to the variation of several critical parameters. The simulation output data was then analyzed using a data-driven methodology and system dynamics approach, through which we summarized the BJI complex system and identified plausible relationships between the agents using differential equations. The BJI model succeeded in imitating the dynamics of bacteria, the innate immune cells, and the bone cells during the first stage of BJI and for different inoculum size in a compatible way. The simulation displayed the damage in bone tissue as a result of the variation in bone remodeling process during BJI. These findings can be considered as a foundation for further analysis and for the proposition of different hypotheses and simulation scenarios that could be investigated through this BJI model as a virtual lab
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Elfving, Filip. "Simulation of laser welding in sandwich rocket nozzle." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-36830.
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This bachelor thesis has been carried out at GKN Aerospace. GKN is a member of European Space Agency, designing and manufacturing rocket-nozzles for the Ariane rockets. The manufacturing process entails many welds. Weld-simulations have been made to investigate stresses and plastic strains on simplified geometries. Plastic strains have been evaluated parallel and normal to the weld for plate geometries of shell-elements with rectangular cross-section and sandwich-cross-section, using the FEM-program MSC.marc. Results shows that plate width and length have negligible effect on the plastic strains when one weld is made. A comparison between a sandwich-sector cone and a sandwich plate was made, to investigate how plastic strains and stresses were affected of geometry. Plastic strains and stresses parallel the weld are the same. Plastic strains and stresses normal the weld are affected by changing geometry. Studies on differences in stresses between solid and shell elements propose use of solid elements near the weld region, if stresses are of interest.
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Froberg, Robert Bryan. "Improving the Methodology to Estimate Joint Logistics Over-the-Shore Operational Throughput and Duration." Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/31566.
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Joint Logistics Over-the-Shore (JLOTS) is the method the United States (US) Army and Navy use to discharge cargo from large seafaring vessels onto a bare beach when an enemy force has denied access to a deep-water port or the ports have been damaged by natural disasters, terrorist actions, sabotaged by military forces, etc. The last large scale, published analytic study on JLOTS was conducted in 1993 during the Ocean Venture 93 exercise at Camp Lejeune, NC; since that time, nearly the entire US Army inventory of wheeled vehicles have been replaced and tracked systems have increased in size and weight with the additions of reactive armor tiles and urban survival kits. The current estimation method for determining how long a JLOTS operation will take relies on the median duration values in order to determine total operational length.
This research shows that the JLOTS activity duration medians published in current military doctrine are no longer representative of the current inventory of US Army vehicles. New planning factors are defined based on JLOTS subject matter expert opinions as well as a new method of JLOTS duration estimation is described through the use of discrete-event simulation. The results of the proposed duration estimation method were compared to both the existing methodology using both the published planning factors and the new planning factors defined through subject matter expert opinion. In both comparisons the current estimation method was found to consistently overestimate operational throughput while underestimating duration since it fails to capture the queuing actions that occur in a resource constrained environment such as JLOTS.
It is the recommendation of this research that a time and motion study be conducted on JLOTS operations in order to more accurately define the probability distributions associated with JLOTS activities. These distributions would replace the triangular distributions defined by subject matter experts in this research in order to generate a more accurate estimate of JLOTS duration and throughput. More accurate estimates for JLOTS operations will enable cost savings by providing maritime transportation providers with greater fidelity on scheduling while reducing the time these ships are vulnerable to enemy actions.
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Tweedle, Valerie. "Simulation Model of Ray Patterning in Zebrafish Caudal Fins." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23181.
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The bony fin rays of the zebrafish caudal fin are a convenient system for studying bone morphogenesis and patterning. Joints and bifurcations in fin rays follow predictable spatial patterns, though the mechanisms underlying these patterns are not well understood. We developed simulation models to explore ray pattern formation mechanisms in growing fins. In all models, the fin ray growth rates are based on quantitative experimental data. The different models simulate ray joint formation and bifurcation formation using different hypothetical mechanisms. In the most plausible model, ray joint and bifurcation formation result from the accumulation of two substances, arbitrarily named J and B. Model parameters were optimized to find the best fit between model output and quantitative experimental data on fin ray patterns. The model will be tested in the future by evaluating how well it can predict fin ray patterns in different fin shapes, mutant zebrafish fins, and other fish species.
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Rolseth, Anton, and Anton Gustafsson. "Implementation of thermomechanical laser welding simulation : Predicting displacements of fusing A AISI304 T-JOINT." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-19946.
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Laser welding is an advanced joining technique with the capability to form deep, narrow, and precise welds. Numerical models are used to simulate the process in attempts of predicting distortions and stresses in the material. This is done to reduce physical testing, optimize processes and enable integrated product- and process development. The Virtual Manufacturing Process research group at University of Skövde wishes to increase their knowledge on modeling options of thermomechanical simulations to grant local industries these benefits. A numerical model for the laser welding process was developed in ABAQUS. This was done by examining the macrograph structure of a simple weld and applied to a stainless-steel T-joint welding application. The macrograph data was used to calibrate a mathematical heat source model. User subroutine DFLUX was used to enable movement of the heat source and element activation was used to simulate the fusion of the two parts. A T-joint welding experiment was carried out to measure deflection and the result was compared to numerical simulations. Different combinations of heat source models, coupling type and element activation was compared in relation to predicting the deflection. Computational time and modeling complexity for the techniques was also considered.The results showed that a 3D Gaussian heat source model will imitate the keyhole weld achieved superior to the compared 2D model. The 3D model provides greater flexibility since it enables combinations of any geometrical bodies. It was shown that element activation has a significant contribution on part stiffness and thus resulting distortions. To implement element activation a fully coupled analysis is required. The deflection of the fully coupled 3D simulation with element activation showed a 9% deviance in deflection compared with experiments.
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Alrashdan, Khaled Rasheed. "A virtual environment for the modelling, simulation and manufacturing of orthopaedic devices." Thesis, Brunel University, 2011. http://bura.brunel.ac.uk/handle/2438/8840.
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The objective of this work is to investigate whether the game physics based modelling is accurate enough to be used in modelling the motion of the human body, in particular musculoskeletal motion. Hitherto, the implementation of game physics in the medical field focused only on anatomical representation for education and training purposes. Introducing gaming platforms and physics engines into orthopaedics applications will help to overcome several difficulties encountered in the modelling of articular joints. Implementing a physics engine (PhysX), which is mainly designed for video games, handles intensive computations in optimized ways at an interactive speed. In this study, the capabilities of the physics engine (PhysX) and gaming platform for modelling and simulating articular joints are evaluated. First, a preliminary validation is carried out for mechanical systems with analytical solutions, before constructing the musculoskeletal model to evaluate the consistency of gaming platforms. The developed musculoskeletal model deals with the human joint as an unconstrained system with 6 DOF which is not available with other joint modeller. The model articulation is driven by contact surfaces and the stiffness of surrounding tissues. A number of contributions, such as contact modelling and muscle wrapping, have been made in this research to overcome some existing challenges in joint modelling. Using muscle segmentation, the proposed technique effectively handles the problem of muscle wrapping, a major concern for many; thus the shortest path and line of action are no longer problematic. Collision behaviour has also shown a stable response for colliding as well as resting objects, provided that it is based on the principles of surface properties and the conservation of linear and angular momentums. The precision of collision detection and response are within an acceptable tolerance controllable by varying the mesh density. An image based analysis system is developed in this thesis, mainly in order to validate the proposed physics based modelling solution. This minimally invasive method is based on the analysis of marker positions located at bony positions with minimal skin movement. The image based system overcomes several challenges associated with the currently existing methods, such as inaccuracy, complication, impracticability and cost. The analysis part of this research has considered the elbow joint as a case study to investigate and validate the proposed physics based model. Beside the interactive 3D simulation, the obtained results are validated by comparing them with the image based system developed within the current research to investigate joint kinematics and laxity and also with published material, MJM and results from experiments performed at the Brunel Orthopaedic Research and Learning Centre. The proposed modelling shows the advantageous speed, reliability and flexibility of the proposed model. It is shown that the gaming platform and physics engine provide a viable solution to human musculoskeletal modelling. Finally, this thesis considers an extended implementation of the proposed platform for testing and assessing the design of custom-made implants, to enhance joint performance. The developed simulation software is expected to give indicative results as well as testing different types of prosthetic implant. Design parameterization and sensitivity analysis for geometrical features are discussed. Thus, an integrated environment is proposed to link the real-time simulation software with a manufacturing environment so as to assist the production of patient specific implants by rapid manufacturing.
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Charlebois, Michael A. Pecha Keith E. "Historical analysis of the Battle of LIttle Bighorn utilizing the Joint Conflict and Tactical Simulation (JCATS /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FCharlebois%5FPecha.pdf.
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Thesis (M.A. in Defense Analysis Special Operations/Low Intensity Conflict)--Naval Postgraduate School, June 2004.<br>Thesis advisor(s): Gordon McCormick, Bard Mansager. Includes bibliographical references (p. 119-120). Also available online.
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Hull, J. W. Jr. "JOINT COMMUNICATIONS, NAVIGATION, IDENTIFICATION STIMULATORS (CNIS)." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608314.
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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>This paper provides a current review of a new installed system test facility (ISTF) capability for the Air Force and Navy. The requirements, design characteristics, and status of the joint-service Communications, Navigation, Identification Simulator (CNIS) developments will be covered along with their relationships with the Air Force’s Avionics Test and Integration Complex (ATIC) and the Navy’s Air Combat Environment Test and Evaluation Facility (ACETEF) ISTFs. These developments provide the services an interactive spatially, temporally, and tactically coherent signal environment for development and operational test and evaluation. The Joint Communications Simulator (JCS) and Joint Data Link Simulator (JDLS) capabilities, integration aspects, and development schedules (2000 IOC) will also be addressed. Finally, installed system test and evaluation concepts, both Air Force and Navy, using the simulators will be previewed to assist upcoming development programs in identifying potential applications.
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Dars, Ghulam Hussain. "Climate Change Impacts on Precipitation Extremes over the Columbia River Basin Based on Downscaled CMIP5 Climate Scenarios." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/979.
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Hydro-climate extreme analysis helps understanding the process of spatio-temporal variation of extreme events due to climate change, and it is an important aspect in designing hydrological structures, forecasting floods and an effective decision making in the field of water resources design and management. The study evaluates extreme precipitation events over the Columbia River Basin (CRB), the fourth largest basin in the U.S., by simulating four CMIP5 global climate models (GCMs) for the historical period (1970-1999) and future period (2041-2070) under RCP85 GHG scenario.
We estimated the intensity of extreme and average precipitation for both winter (DJF) and summer (JJA) seasons by using the GEV distribution and multi-model ensemble average over the domain of the Columbia River Basin. The four CMIP5 models performed very well at simulating precipitation extremes in the winter season. The CMIP5 climate models showed heterogeneous spatial pattern of summer extreme precipitation over the CRB for the future period. It was noticed that multi-model ensemble mean outperformed compared to the individual performance of climate models for both seasons.
We have found that the multi-model ensemble shows a consistent and significant increase in the extreme precipitation events in the west of the Cascades Range, Coastal Ranges of Oregon and Washington State, the Canadian portion of the basin and over the Rocky Mountains. However, the mean precipitation is projected to decrease in both winter and summer seasons in the future period.
The Columbia River is dominated by the glacial snowmelt, so the increase in the intensity of extreme precipitation and decrease in mean precipitation in the future period, as simulated by four CMIP5 models, is expected to aggravate the earlier snowmelt and contribute to the flooding in the low lying areas especially in the west of the Cascades Range. In addition, the climate change shift could have serious implications on transboundary water issues in between the United States and Canada. Therefore, adaptation strategies should be devised to cope the possible adverse effects of the changing the future climate so that it could have minimal influence on hydrology, agriculture, aquatic species, hydro-power generation, human health and other water related infrastructure.
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Mabuma, Joffrey [Verfasser], and Wolfgang [Akademischer Betreuer] Ehlers. "Multi-field modelling and simulation of the human hip joint / Joffrey Mabuma. Betreuer: Wolfgang Ehlers." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2014. http://d-nb.info/1058860305/34.
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Freye, Jeffrey T. "Design of experiment analysis for the Joint Dynamic Allocation of Fires and Sensors (JDAFS) simulation." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Jun%5FFreye.pdf.
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Thesis (M.S. in Operations Research)--Naval Postgraduate School, June 2007.<br>Thesis Advisor(s): Lucas, Thomas W. . "June 2007." Description based on title screen as viewed on August 15, 2007. Includes bibliographical references (p. 135-137). Also available in print.
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Nailah, Firdausiyah. "MULTI-AGENT SIMULATION USING ADAPTIVE DYNAMIC PROGRAMMING BASED REINFORCEMENT LEARNING FOR EVALUATING JOINT DELIVERY SYSTEMS." Kyoto University, 2018. http://hdl.handle.net/2433/235076.
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Gauthier, Paul. "Tibio-femoral Joint Contact Mechanics: An In-vitro Simulation with a 6 DOF Static Knee Simulator." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34184.
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Introduction: Understanding the relationship between muscle loads crossing the knee joint and knee joint mechanics is critical for understanding knee stability and the effects of altered muscle forces on healthy and ACL injured knees. In vitro measurement can be used to elucidate this if the simulation is biofidelic, allowing the physiological levels of applied loads to dictate the tibiofemoral kinematics in all degrees of freedom (DoF). The objectives of this study were to describe and apply the University of Ottawa knee simulator as well as measure the reliability of the device. In addition, this device was used to quantify the effect of muscle loads and anterior cruciate ligament (ACL) resection on contact mechanics and kinematics of the tibiofemoral joint. Methods: Muscle forces were determined from an electromyography-driven musculoskeletal model of a healthy male during gait. Six knee specimens were loaded into the simulator and subjected to 100%, 75% and 50% in vivo muscle forces applied through the 6 simulated muscles, in addition to a quadriceps weakness and a hamstring weakness condition. Tibiofemoral mechanics were measured with all 5 loading conditions before and after ACL transection. Results: With the ACL intact, very high reliability in contact area and pressures among loading conditions were observed as the intra-class correlation coefficients (ICC) ranged from 0.932 to 0.99. After ACL transection, reliability remained very high as ICCs ranged from 0.926 to 0.99. In all simulated conditions, muscle forces maintained the knee joint in a stable position resulting in minimal kinematic differences, but altered contact mechanics in both the ACL and non-ACL condition. Removal of the ACL significantly reduced both the medial and lateral contact areas in all loading conditions compared to the ACL intact condition. Conclusion: In summary, the UOKS has demonstrated high reliability within repeated measures. Additionally, small, normally undetectable alterations in joint kinematics resulted in significant alterations to contact mechanics, which can be linked to the degenerative process.
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Suggs, Jeremy F. (Jeremy Floyd) 1976. "Simulation of anterior cruciate ligament injury and reconstruction using a 3D finite element knee joint model." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/89369.
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Menk, Alexander. "Simulation of complex microstructural geometries using X-FEM and the application to solder joint lifetime prediction." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2519/.
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In electronic devices solder joints form a mechanical as well as an electrical connection between the circuit board and the component (e.g. a chip or a resistor). Temperature variations occurring during field use cause crack initiation and crack growth inside the joints. Accurate prediction of the lifetime requires a method to simulate the damage process based on microstructural properties. Numerical simulation of developing cracks and microstructural entities such as grain boundaries and grain junctions gives rise to several problems. The solution contains strong and weak discontinuities as well as weak singularities. To obtain reasonable solutions with the finite element method (FEM) the element edges have to align with the cracks and the grain boundaries, which imposes geometrical restrictions on the mesh choice. Additionally, a large number of elements has to be used in the vicinity of the singularities which increases the computational effort. Both problems can be circumvented with the extended finite element method (X-FEM) by using appropriate enrichment functions. In this thesis the X-FEM will be developed for the simulation of complex microstructural geometries. Due to the anisotropy of the different grains forming a joint and the variety of different microstructural configurations it is not always possible to write the enrichment functions in a closed form. A procedure to determine enrichment functions numerically is explained and tested. As a result, a very simple meshing scheme, which will be introduced here, can be used to simulate developing cracks in solder joint microstructures. Due to the simplicity of the meshing algorithm the simulation can be automated completely. A large number of enrichment functions must be used to realize this. Well-conditioned equation systems, however, cannot be guaranteed for such an approach. To improve the condition number of the X-FEM stiffness matrix and thus the robustness of the solution process a preconditioning technique is derived and applied. This approach makes it possible to develop a new and fully automated procedure for addressing the reliability of solder joints numerically. The procedure relies on the random generation of microstructures. Performing crack growth calculations for a series of these structures makes it possible to address the influence of varying microstructures on the damage process. Material parameters describing the microstructure are determined in an inverse procedure. It will be shown that the numerical results correspond well with experimental observations.
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Nguyen, Vienny N. "Development of a Finite Element Model of an Ant Neck Joint for Simulation of Tensile Loading." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1342457030.
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Pecha, Keith E., and Michael A. Charlebois. "Historical analysis of the Battle of Little Bighorn utilizing the Joint Conflict and Tactical Simulation (JCATS)." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1174.
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Approved for public release; distribution is unlimited<br>The purpose of this thesis is to determine which of three competing theories of what occurred at the Battle of Little Bighorn is the most plausible by utilizing the Joint Conflict and Tactical Simulation (JCATS) program developed by Lawrence Livermore National Laboratory. There are many practical gains that JCATS can provide today's military with regard to training and educating soldiers for future conflicts. JCATS can be used to train soldiers in planning and executing missions in ways not feasible with conventional field training exercises utilizing live bodies and real vehicles. It is also increasingly being used for actual mission planning. However, very little has been done using JCATS to war-game past operations. There are two points to be gained by using JCATS to model a historical battle such as the Battle of Little Bighorn. First, it validates the ability of JCATS to accurately model actual historical scenarios while identifying many of the specific limitations of the program. If the military is going to use computer simulations such as JCATS in lieu of field training exercises to train soldiers, it must first be determined if the program produces realistic results. Modeling an actual battle and comparing the results of the program with what actually occurred is one means of doing so. Second, modeling historical battles, particularly defeats, may assist in discovering lessons learned. In a field training exercise, a defeated force can be brought back to life and given another opportunity to apply the lessons learned from its previous defeat. Real battles afford no such opportunity. Computer modeling of past battles would allow military planners to isolate individual events and decisions and study their impact on the outcome.<br>Major, United States Army
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Amankwah, Kofi. "THE IMPACT OF LOWER EXTREMITY PASSIVE JOINT PROPERTIES ON STANDING FUNCTION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1081532731.
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Conroy, Sara A. "A simulation study of bivariate Wiener process models for an observable marker and latent health status." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1452015350.
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Andraéy, Erik. "Development of verified FE simulation method on crimp joint with gasket : A combined experimental and numerical study." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-21924.
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When developing drivetrain cooling modules for commercial vehicles, the top priority is the strength of the products. The reason lays within the structural change that companies are undergoing where the warehouses are minimized and the companies are relying on the transportation of commercial vehicles. If a drivetrain cooling module would fail to maintain a targeted temperature range of the drivetrain, there is not long until the vehicle is forced to a stop. At worst, the downtime of commercial vehicles can cause companies to come to a halt as well. Therefore, developing verified FE simulation methods together with strength verification tests, are some of the core activities to ensure the strength of the cooling modules before implementation in vehicles. One of the methods that have not been sufficiently verified regards how to perform structural FEA on a crimp joint with a gasket. A crimp joint is established through a hemming process, where the aluminium header tabs are crimped over the polyamide tank, creating a watertight seal together with a gasket. The objective of this master’s thesis is to verify the existing simulation methods of the crimp joint and determine the margin of error with respect to strains. The objective of this thesis is also to develop a verified FE simulation method with a lower margin of error compared to the existing methods. The verification of the methods has been conducted through a comparison between numerical results and an experimental stress analysis, where the strain located on the header is measured with strain gauges in a pressure pulsation rig. The average margin of error found on the three existing methods of simulating the crimp joint was 39,7%, 13,4%, and 11,5% located on the outer bottom dimensioning radius of the crimp joint at a pressure of 100 kPa. However, the method used to determine the margin of error was found to be invalid, but the margin of error is only slightly affected by the verification method where the existing methods still are insufficiently representing the crimp joint. The method of determining the margin of error was then corrected for the development of the new method to represent the crimp joint in the FE model. The developed method in this thesis has an average margin of error of 6,9% at 100, 160, 220, and 260 kPa.<br>Vid utveckling av kylarmoduler för drivlinor som appliceras i kommersiella fordon, är högsta prioritet att säkerhetsställa hållfastheten hos produkterna. Anledningen ligger kring den strukturomvandling som företag genomgår där storleken på lagerlokaler minskar och företagen väljer att förlita sig på transporterna som utförs av kommersiella fordon istället. Ifall en kylarmodul inte skulle klara av att bibehålla ett bestämt temperaturintervall hos drivlinan så dröjer det inte länge förens fordonet tvingas att stanna. I värsta fall kan fordonets stillestånd påverka ett företag att tvingas stanna i väntan. Därför är utveckling av FE simuleringsmetoder tillsammans med utmattningstest, några av de kärnaktiviteter som utförs för att säkerhetsställa hållfastheten av kylarmodulerna innan de implementeras i fordon. En av de metoder som ännu inte blivit tillräckligt verifierat gäller hur man utför FEA på ett falsförband med packning. Falsförbandet skapas genom en falsningsprocess där ändplåten av aluminium falsas över polyamidtanken, vilket skapar ett vattentätt förband med hjälp av packningen. Omfattningen av detta examensarbete gäller att verifiera de existerande simuleringsmetoderna av falsförbandet och bestämma felmarginalen med avseende på töjningar. Omfattningen av examensarbetet innefattar även ett utvecklingsarbete av en ny FE simuleringsmetod med en lägre felmarginal jämfört med de existerande metoderna. Verifieringen av metoderna sker genom en jämförelse mellan de numeriska resultaten och en experimentell spänningsanalys där töjningen på ändplåten är uppmätt med hjälp av trådtöjningsgivare i en tryckpulsationsrigg. Den genomsnittliga felmarginalen av de tre existerande metoderna för att simulera falsförbandet var 37,9%, 13,4%, och 11,5% vid den nedre dimensionerande yttre radien på falsförbandet vid ett tryck på 100 kPa. Den använda metoden för att bestämma felmarginalen upptäcktes senare vara felaktig, men det resulterar endast i små förändringar av den bestämda felmarginalen, de existerande simuleringsmetoderna är fortfarande sedda som otillräckliga. Metoden för att bestämma felmarginalen korrigerades sedan inför utvecklandet av den nya FE simuleringsmetoden av falsförbandet. Den utvecklade metoden i detta examensarbete har en genomsnittlig felmarginal på 6,9% vid 100, 160, 220 och 260 kPa.
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Bricker, David A. "Analysis of Joint Effects of Refraction and Turbulence on Laser Beam Propagation in the Atmosphere." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1386973427.
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Lelonkiewicz, Jarosław Roman. "Cognitive mechanisms and social consequences of imitation." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/23490.
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When interacting, people imitate each other. This tendency is truly ubiquitous and occurs in many different situations and behaviours. But what causes it? Several mechanisms have been proposed to contribute to imitation. In this thesis, I focus on three candidate mechanisms: simulation, temporal adaptation, and the goal to affiliate with others. I start by discussing different imitative behaviours, and reviewing the evidence that imitation might at times emerge spontaneously. I also review the evidence suggesting that the three candidate mechanisms might be involved in such emergent imitation. Then, I present three sets of experiments. In the first set, I investigate the role of simulation in language processing. In three experiments, I test the hypothesis that comprehenders use their language production system to simulate their interlocutor, which in turn facilitates their ability to predict the next word they will see or hear. I manipulate whether participants read the sentences silently or aloud and measure their ability to predict the final word of a sentence. My results demonstrate that prediction is enhanced when people use their production system during reading aloud. This gives some credence to the idea that simulation is routinely engaged in language processing, which in turn opens up a possibility that it may contribute to linguistic imitation. In the second set of experiments, I investigate whether temporal adaptation leads agents to imitate features of their partner’s actions. In three experiments, I test this by manipulating the partner’s response speed and the information about the partner’s actions. I show that agents imitate response speed when they are able to observe the partner. Moreover, they adapt to the specific temporal pattern of their partner’s actions. These findings provide evidence for the engagement of the temporal adaptation mechanism during motor interactions, and for its involvement in imitation. In the third set of experiments, I turn to the hypothesis that people engage in linguistic imitation because they want to harness the social benefits it brings. I investigate a key assumption of this hypothesis: that imitation has positive consequences for the social interaction. In three experiments, I manipulate whether participants’ word choice is imitated or counter-imitated by their conversational partner and measure how it affects the participants’ evaluation of the interaction and the partner, and their willingness to cooperate with the partner. I find evidence that linguistic imitation has positive social consequences. These results are consonant with the claim that imitation is motivated by the goal to affiliate and foster social relations. Taken together, these findings suggest that imitation might occur both in motor actions and language, and that it might have diverse causes. My work on language suggests that the tendency to linguistically imitate others could both result from the simulation mechanism, and be motivated by the goal to affiliate. My work on motor actions shows that automatic temporal adaptation contributes to emergent imitation during interactions. This research is conducive to the greater aim of cross-examining the currently known mechanisms of imitation.
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Miller, Thomas Edward S. M. Massachusetts Institute of Technology. "Real time bottom reverberation simulation in deep and shallow ocean environments." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/103576.
Full textAbstract:
Thesis: S.M., Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (page 77).<br>Due to the costs involved and time required to perform experiments at sea, it is important to provide accurate simulations of the ocean environment. Using the ray tracing code, BELLHOP, the Mission Oriented Operating Suite (MOOS), methods outlined by the Naval Research Laboratory (NRL) for bottom reverberation, and MATLAB, a model will be developed to incorporate the effects of bottom reverberation into the BELLHOP suite of code. This will be accomplished by using BELLHOP to generate a ray trace and eigen ray file. Then a MATLAB script will take the BELLHOP information and calculate the reverberation level using the NRL model by measuring the amplitude and reverberation at a receiver array simulated on the ocean floor. These reverberation values will then be used to determine the reverberation level at the source due to these bottom interactions. Testing of the simulation will include deep and shallow ocean profiles and multiple sound speed profiles (SSP). Following this testing, the goal is to implement the model in existing C++ code used for the testing of AUV systems. The ability to accurately model the ocean will not only allow for testing of autonomy code in the laboratory, but also make it possible to refine and calibrate code making ship time more efficient.<br>by Thomas Edward Miller.<br>S.M.