Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 60 for “"Adjoint Method"”.
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Centrifugal compressor return channel shape optimization using adjoint method
… gradient-based optimization process using the adjoint method and its application to centrifugal compressor return channel loss reduction. A proper objective function definition and a generalized geometry parametrization and manipulation algorithm were developed, and the appropriate adjoint …
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Applications of the Discrete Adjoint Method in Computational Fluid Dynamics
The discrete adjoint method allows efficient evaluation of the derivative of a function I(s) with respect to parameters s in situations where I depends on s indirectly, via an intermediate variable w(s), which is computationally expensive to evaluate. In this thesis two applications of this method …
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Viscosity stabilized adjoint method for unsteady compressible Navier-Stokes equations
Design optimization methods are a popular tool in computational fluid dynamics for designing components or finalizing the flow parameters of a system. The adjoint method accelerates the design process by providing gradients of the design objective with respect to the system parameters. But, …
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Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method
The finite element method has been shown to be a powerful tool in computational engineering with recent application to electromagnetics and fluid dynamics. However, achieving the high orders of accuracy easily available to the finite element method has proven difficult due to conforming …
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An exact and consistent adjoint method for high-fidelity discretization of the compressible flow equations
Methods and computing hardware advances have enabled accurate predictions of complex compressible turbulence phenomena, such as the generation of jet noise that motivates the present effort. However, limited understanding of underlying physical mechanisms restricts the utility of such predictions …
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Development of S3D and Adjoint Design Methods for Efficient Aerodynamic Design of Three-Dimensional High-Speed Compressor Blades
In the second part of the study, an adjoint design method was employed for compressor design to broaden the range of design capability, to facilitate 3D design applications, and to complement the S3D design method. An adjoint design code was developed, based on a 3D compressor flow analysis code, …
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Sensitivities in Option Pricing Models
… cost function. In this thesis we highlight the adjoint method for computing gradients of the cost function in the context of gradient based optimization and show its importance. We derive the continuous adjoint equations with appropriate boundary conditions for three main option pricing models: …
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An adjoint-based optimization method using the solution of gray-box conservation laws
… optimization can be efficiently solved by the adjoint method, which computes the gradient of the objective to the design variables. Traditionally, the adjoint method has not been able to be implemented in "gray-box" conservation law simulations. In gray-box simulations, the analytical and …
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Production and analysis of a Southern Ocean state estimate
… and open northern boundary at 24.7°S) using the adjoint method. A cost function compares the model state to data from CTD synoptic sections, hydrographic climatology, satellite altimetry, and XBTs. Costs attributed to control variable perturbations ensure a physically realistic solution. An …
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Production and analysis of a Southern Ocean state estimate
… and open northern boundary at 24.7 S) using the adjoint method. A cost function compares the model state to data from CTD synoptic sections, hydrographic climatology, satellite altimetry, and XBTs. Costs attributed to control variable perturbations ensure a physically realistic solution. An …
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Adjoint-based particle defect yield modeling
… function of photonic devices and circuits. The adjoint method previously used in optimization is modified and implemented to facilitate the simulation of the impact of defects in silicon photonic devices. More specifically, we demonstrate the methodology to build both component-level and …
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Computational design, sensitivity analysis and optimization of fuel reforming catalytic reactor
… system of equations is solved by Newton’s method. The catalytic partial oxidation of methane over a rhodium catalyst in one channel of a coated honeycomb reactor is studied three-dimensionally, and eight gas-phase species (CH4, CO2, H2O, N2, O2, CO, OH and H2) are considered for the …
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Optimization of neural network feedback control systems using automatic differentiation
… to solve, whether using analytic or numerical methods. This thesis examines the application of an adjoint method for optimal feedback control, which combines various algorithmic techniques into an original numerical method. In the method investigated here, a neural network defines the control …
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New methods for sensitivity analysis of chaotic dynamical systems
Computational methods for sensitivity analysis are invaluable tools for fluid dynamics research and engineering design. These methods are used in many applications, including aerodynamic shape optimization and adaptive grid refinement. However, traditional sensitivity analysis methods break down …
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Coefficient recovery in parabolic initial boundary value problems
… the Backus-Gilbert approach, modified with an adjoint method, to construct an approximate solution to the problem. We show the results of numerical experiments for the single, spatial variable case and then apply the method to related problems.
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Fundamental limits to local density of states in absorptive system
… produce high LDOS. A novel shape optimization method based on the adjoint method is presented in this work, several numerical methods (BEM, CGAL, etc.) and optimization methods are implemented to enable more efficient evaluation and reduce the computation costs.
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Modelling the floating-catalyst method for carbon nanotube production
… function is minimised using a gradient-based method. An adjoint method is used to calculate the gradient of the objective function with respect to the model parameters. This decomposition rate of thiophene in a hydrogen atmosphere is then used to compare the decomposition of ferrocene and …
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On the Viscoelastic Deformation of the Earth
… in this way, it is first necessary to have a method of forward modelling the processes, that is, calculating the deformation due to a given forcing and in an earth model with a given structure. Given this, a way of calculating derivatives of measurements of the deformation with respect to the …
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Theoretical and computational studies in seismic tomography
… the Earth on a range of lengthscales, with the method of waveform inversion being a promising and relatively recent development. In this work, we present new theoretical methods which may contribute to the study and solution of seismic tomography inverse problems. In particular, we set out the …
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Uncertainty quantification in ocean state estimation
… The estimation system is based on the "adjoint method" solution of an unconstrained least-squares optimization problem formulated with the method of Lagrange multipliers for fitting the dynamical ocean model to observations. The dynamical consistency requirement of ocean state estimation …
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