Thèses sur le sujet « Multi-fidelity Analysi »
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MAININI, LAURA. « Multidisciplinary and multi-fidelity optimization environment for wing integrated design ». Doctoral thesis, Politecnico di Torino, 2012. http://hdl.handle.net/11583/2500000.
Texte intégralLe, Gratiet Loic. « Multi-fidelity Gaussian process regression for computer experiments ». Phd thesis, Université Paris-Diderot - Paris VII, 2013. http://tel.archives-ouvertes.fr/tel-00866770.
Texte intégralMuppana, Sai. « Multi-fidelity Design and Analysis of Single Hub Multi-rotor High Pressure Centrifugal Compressor ». University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553517075653458.
Texte intégralVenkatesan, Sreedhar, et Hanumantha Raju Hariprasad Banglore. « Probabilistic Analysis of Brake Noise : A Hierarchical Multi-fidelity Statistical Approach ». Thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-151009.
Texte intégralComputer Aided Engineering (cae) driven analysis is gaining grounds in automotive industry. Brake noise is one such place where cae simulations are gaining more attention. The presence of several uncertain parameters which affect brake noises and also the lack of basic understanding about brake noise, makes it difficult to make reliable decisions based on cae deterministic analyses alone.Therefore, the confidence level in cae analyses has to be increased to ensure cae analysis robustness. One way to achieve this is by incorporating the effects of different sources of uncertainty and variability in the cae analysis and estimating the probability of design failure. Such a reliability measure (i.e. probability of noise event occurrence or exceedance of noise level than a threshold) can provide car manufacturers with an idea about the costs of warranty claims due to brake noise and can be used as a metric to evaluate different design solutions, before the final design goes to the production stage. On one hand, using the high-fidelity models of brake/chassis system is generally computationally intensive, and thus, often only limited number of simula-tion runs are feasible for uncertainty analysis and design failure risk assessment. On the other hand, analyses on low-fidelity models, typically based on simplified assumptions during the development phase are fast but not always accu-rate. Striking for a good balance between efficiency and accuracy/robustness is an important task, when dealing with uncertainty/risk analysis of such complex dynamical systems To address these issues, a hierarchical multi-fidelity statistical approach has been adopted in this study, in order to estimate the probability of design failure. It employs a hierarchy of approximations to the system response computed with different fidelity by surrogate modelling, coarse spatial/temporal model mesh resolution variation, changing solver time step, etc., using probability theory, to relate information provided by approximate solu-tions to the target failure estimation. Using this approach opens up the possi-bility to use a low-fidelity models to accelerate the uncertainty quantification of complex brake/chassis systems, while granting unbiased estimation of system design failure risk/reliability. It also enables management of design changes, during fast iterations of the design process. This approach is used for studying one of the brake noise issue called creep groan, understand the root cause and providedesign proposals.
Loupy, Gaëtan J. M. « High fidelity, multi-disciplinary analysis of flow in realistic weapon bays ». Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/9091/.
Texte intégralStults, Ian Collier. « A multi-fidelity analysis selection method using a constrained discrete optimization formulation ». Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31706.
Texte intégralCommittee Chair: Mavris, Dimitri; Committee Member: Beeson, Don; Committee Member: Duncan, Scott; Committee Member: German, Brian; Committee Member: Kumar, Viren. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Lawson, Stephen James. « High performance computing for high-fidelity multi-disciplinary analysis of weapon bays ». Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533992.
Texte intégralMeckstroth, Christopher. « Incorporation of Physics-Based Controllability Analysis in Aircraft Multi-Fidelity MADO Framework ». University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1575557306181006.
Texte intégralRaj, Oliver Neal. « Multi-Fidelity Structural Modeling For Set Based Design of Advanced Marine Vehicles ». Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83377.
Texte intégralMaster of Science
Mola, Andrea. « Multi-physics and Multilevel Fidelity Modeling and Analysis of Olympic Rowing Boat Dynamics ». Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/28057.
Texte intégralPh. D.
Lickenbrock, Madeline Clare. « Multi-fidelity, Multidisciplinary Design Analysis and Optimization of the Efficient Supersonic Air Vehicle ». University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1608156251624819.
Texte intégralCzechowicz, Maciej P. « Analysis of vehicle rollover using a high fidelity multi-body model and statistical methods ». Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18106.
Texte intégralAustin, Jason Louis. « A Multi-Component Analysis of a Wind Turbine Gearbox Using a High Fidelity Finite Element Model ». The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1370441712.
Texte intégralRaub, Corey Bevan. « Geometric analysis of axisymmetric disk forging ». Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1172778393.
Texte intégralWeston, David Bruce. « High Fidelity Time Accurate CFD Analysis of a Multi-stage Turbofan at Various Operating Points in Distorted Inflow ». BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5604.
Texte intégralGu, Xiangyu [Verfasser], Eike [Akademischer Betreuer] Stumpf et Arthur [Akademischer Betreuer] Rizzi. « Application of Computational Aerodynamic Analysis and Optimization in a Multi-Fidelity Distributed Overall Aircraft Design System / Xiangyu Gu ; Eike Stumpf, Arthur Rizzi ». Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/116185388X/34.
Texte intégralHebbal, Ali. « Deep gaussian processes for the analysis and optimization of complex systems : application to aerospace system design ». Thesis, Lille, 2021. http://www.theses.fr/2021LILUI016.
Texte intégralIn engineering, the design of complex systems, such as aerospace launch vehicles, involves the analysis and optimization of problems presenting diverse challenges. Actually, the designer has to take into account different aspects in the design of complex systems, such as the presence of black-box computationally expensive functions, the complex behavior of the optimized performance (e.g., abrupt change of a physical property here referred as non-stationarity), the multiple objectives and constraints involved, the multi-source information handling in a multi-fidelity framework, and the epistemic and aleatory uncertainties affecting the physical models. A wide range of machine learning methods are used to address these various challenges. Among these approaches, Gaussian Processes (GPs), benefiting from their Bayesian and non-parametric formulation, are popular in the literature and diverse state-of-the-art algorithms for the design of complex systems are based on these models.Despite being widely used for the analysis and optimization of complex systems, GPs, still present some limitations. For the optimization of computationally expensive functions, GPs are used within the Bayesian optimization framework as regression models. However, for the optimization of non-stationary problems, they are not suitable due to the use of a prior stationary covariance function. Furthermore, in Bayesian optimization of multiple objectives, a GP is used for each involved objective independently, which prevents the exhibition of a potential correlation between the objectives. Another limitation occurs in multi-fidelity analysis where GP-based models are used to improve high-fidelity models using low-fidelity information. However, these models usually assume that the different fidelity input spaces are identically defined, which is not the case in some design problems.In this thesis, approaches are developed to overcome the limits of GPs in the analysis and optimization of complex systems. These approaches are based on Deep Gaussian Processes (DGPs), the hierarchical generalization of Gaussian processes.To handle non-stationarity in Bayesian optimization, a framework is developed that couples Bayesian optimization with DGPs. The inner layers allow a non-parametric Bayesian mapping of the input space to better represent non-stationary functions. For multi-objective Bayesian optimization, a multi-objective DGP model is developed. Each layer of this model corresponds to an objective and the different layers are connected with undirected edges to encode the potential correlation between objectives. Moreover, a computational approach for the expected hyper-volume improvement is proposed to take into account this correlation at the infill criterion level as well. Finally, to address multi-fidelity analysis for different input space definitions, a two-level DGP model is developed. This model allows a joint optimization of the multi-fidelity model and the input space mapping between fidelities.The different approaches developed are assessed on analytical problems as well as on representative aerospace vehicle design problems with respect to state-of-the-art approaches
Saeedi, Mehran [Verfasser], Kai-Uwe [Akademischer Betreuer] Bletzinger, Carlo Luigi [Gutachter] Bottasso, Ernst [Gutachter] Rank et Kai-Uwe [Gutachter] Bletzinger. « Multi-Fidelity Aeroelastic Analysis of Flexible Membrane Wind Turbine Blades / Mehran Saeedi ; Gutachter : Carlo Luigi Bottasso, Ernst Rank, Kai-Uwe Bletzinger ; Betreuer : Kai-Uwe Bletzinger ». München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1152006541/34.
Texte intégralBunnell, Spencer Reese. « Real Time Design Space Exploration of Static and Vibratory Structural Responses in Turbomachinery Through Surrogate Modeling with Principal Components ». BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8451.
Texte intégralCulina, Antica. « With or without you : pair fidelity and divorce in monogamous birds ». Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:6f2d3c09-712c-4f1f-838a-4a23fe5c85d1.
Texte intégral(6852506), Gowtham Manikanta Reddy Tamanampudi. « REDUCED FIDELITY ANALYSIS OF COMBUSTION INSTABILITIES USING FLAME TRANSFER FUNCTIONS IN A NONLINEAR EULER SOLVER ». Thesis, 2019.
Trouver le texte intégralCombustion instability, a complex phenomenon observed in combustion chambers is due to the coupling between heat release and other unsteady flow processes. Combustion instability has long been a topic of interest to rocket scientists and has been extensively investigated experimentally and computationally. However, to date, there is no computational tool that can accurately predict the combustion instabilities in full-size combustors because of the amount of computational power required to perform a high-fidelity simulation of a multi-element chamber. Hence, the focus is shifted to reduced fidelity computational tools which may accurately predict the instability by using the information available from the high-fidelity simulations or experiments of single or few-element combustors. One way of developing reduced fidelity computational tools involves using a reduced fidelity solver together with the flame transfer functions that carry important information about the flame behavior from a high-fidelity simulation or experiment to a reduced fidelity simulation.
To date, research has been focused mainly on premixed flames and using acoustic solvers together with the global flame transfer functions that were obtained by integrating over a region. However, in the case of rockets, the flame is non-premixed and distributed in space and time. Further, the mixing of propellants is impacted by the level of flow fluctuations and can lead to non-uniform mean properties and hence, there is a need for reduced fidelity solver that can capture the gas dynamics, nonlinearities and steep-fronted waves accurately. Nonlinear Euler equations have all the required capabilities and are at the bottom of the list in terms of the computational cost among the solvers that can solve for mean flow and allow multi-dimensional modeling of combustion instabilities. Hence, in the current work, nonlinear Euler solver together with the spatially distributed local flame transfer functions that capture the coupling between flame, acoustics, and hydrodynamics is explored.
In this thesis, the approach to extract flame transfer functions from high-fidelity simulations and their integration with nonlinear Euler solver is presented. The dynamic mode decomposition (DMD) was used to extract spatially distributed flame transfer function (FTF) from high fidelity simulation of a single element non-premixed flame. Once extracted, the FTF was integrated with nonlinear Euler equations as a fluctuating source term of the energy equation. The time-averaged species destruction rates from the high-fidelity simulation were used as the mean source terms of the species equations. Following a variable gain approach, the local species destruction rates were modified to account for local cell constituents and maintain correct mean conditions at every time step of the nonlinear Euler simulation. The proposed reduced fidelity model was verified using a Rijke tube test case and to further assess the capabilities of the proposed model it was applied to a single element model rocket combustor, the Continuously Variable Resonance Combustor (CVRC), that exhibited self-excited combustion instabilities that are on the order of 10% of the mean pressure. The results showed that the proposed model could reproduce the unsteady behavior of the CVRC predicted by the high-fidelity simulation reasonably well. The effects of control parameters such as the number of modes included in the FTF, the number of sampling points used in the Fourier transform of the unsteady heat release, and mesh size are also studied. The reduced fidelity model could reproduce the limit cycle amplitude within a few percent of the mean pressure. The successful constraints on the model include good spatial resolution and FTF with all modes up to at least one dominant frequency higher than the frequencies of interest. Furthermore, the reduced fidelity model reproduced consistent mode shapes and linear growth rates that reasonably matched the experimental observations, although the apparent ability to match growth rates needs to be better understood. However, the presence of significant heat release near a pressure node of a higher harmonic mode was found to be an issue. This issue was rectified by expanding the pressure node of the higher frequency mode. Analysis of two-dimensional effects and coupling between the local pressure and heat release fluctuations showed that it may be necessary to use two dimensional spatially distributed local FTFs for accurate prediction of combustion instabilities in high energy devices such as rocket combustors. Hybrid RANS/LES-FTF simulation of the CVRC revealed that it might be necessary to use Flame Describing Function (FDF) to capture the growth of pressure fluctuations to limit cycle when Navier-Stokes solver is used.
The main objectives of this thesis are:
1. Extraction of spatially distributed local flame transfer function from the high fidelity simulation using dynamic mode decomposition and its integration with nonlinear Euler solver
2. Verification of the proposed approach and its application to the Continuously Variable Resonance Combustor (CVRC).
3. Sensitivity analysis of the reduced fidelity model to control parameters such as the number of modes included in the FTF, the number of sampling points used in the Fourier transform of the unsteady heat release, and mesh size.
The goal of this thesis is to contribute towards a reduced fidelity computational tool which can accurately predict the combustion instabilities in practical systems using flame transfer functions, by providing a path way for reduced fidelity multi-element simulation, and by defining the limitations associated with using flame transfer functions and nonlinear Euler equations for non-premixed flames.