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 15 of 15 for “"impedance boundary condition"”.
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Integral-Equation Modelling of Metasurfaces via the Impedance Boundary Condition
L'abstract è presente nell'allegato / the abstract is in the attachment
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Investigating the Feasibility and Stability for Modeling Acoustic Wave Scattering Using a Time-Domain Boundary Integral Equation with Impedance Boundary Condition
… and are characterized by a frequency-dependent impedance. Converted into the time-domain using Fourier transforms, an impedance boundary condition can be used to simulate the acoustic wave scattering by geometric bodies treated with acoustic liners</p> <p>This work considers using either an …
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A comparison of analytical models and experimental results for the acoustic response in a non-rigid-wall enclosure
… response in any enclosure is determined by the boundary conditions at the interior surface of the enclosure walls, and the types of sources present. The analyses presented in this thesis assumed that the sources were either at the surface of the enclosure, or interior to the enclosure walls. …
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Augmented Surface Integral Equation Method for Low-Frequency Electromagnetic Analysis
… can be efficiently solved with appropriate preconditioning and fast algorithm acceleration. As required in many applications, a generalized impedance boundary condition (GIBC) formulation is developed to handle the skin effect rigorously and efficiently. It degenerates into traditional methods …
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Fast algorithm and surface integral equations for two-dimensional materials modeling
… aid of the electric field integral equation and impedance boundary condition, the surface currents on TMDC flakes can be calculated at fundamental frequencies. By applying three-fold rotational symmetry of the quadratically nonlinear susceptibility of TMDC monolayer, radial (or azimuthal) …
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Aeroacoustic computation of sound radiation from ducts
… the determination of a suitable non-reflecting boundary condition for duct acoustics is also undertaken. Using a novel formulation of the linearised Euler equations, the solver is applied to noise radiation from a realistic engine intake geometry with background mean flow. The accuracy of the …
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Linear and weakly nonlinear boundary layer acoustics in a lined duct
In this thesis I look at the effect of boundary layer flow on the acoustics of an acoustic lining. Acoustic linings are used in aircraft engine ducts to reduce the sound they produce. They typically consist of an array of Helmholtz resonators that are characterised by their impedance - a linear …
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High-Order Finite-Difference Schemes and Their Application to Computational Acoustics
… finite-difference schemes is the construction of boundary closures which simultaneously maintain the formal order of accuracy and the numerical stability of the overall scheme. In this thesis a hybrid seven-point, fourth-order stencil for computing spatial derivatives is presented and the time …
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Macro Basis Functions for Wire and Cable Coupling Analysis
… expensive and the resulting systems could be ill-conditioned. This dissertation proposes sets of macro basis functions (MBFs) for representing currents on wires and fields inside coaxial cables, to reduce the computational cost while preserving full-wave accuracy. MBFs reduce the solution space by …
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Mathematical Modelling of Acoustic Diffraction Noise Embracing Diverse Boundary Conditions
… theory to solve diffraction problems with linear boundary conditions prescribed distinctly on each side of a semi-infinite boundary. We choose this framework to reflect physical applications in subsequent parts. Key aspects covered in the technique include the multiplicative splitting of …
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Numerical investigation of slat noise attenuation using acoustic liners
… the far field acoustic signal. A time domain impedance boundary condition (TDIBC) is implemented to simulate the effect of the liner material directly. <br/>Both the high frequency tonal noise and low frequency broadband noise generated from the slat are investigated.<br/>For the high …
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Deterministic Design of Metasurface Antennas
L'abstract è presente nell'allegato / the abstract is in the attachment
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Numerical Techniques for the Automated Design of Metasurface Antennas
L'abstract è presente nell'allegato / the abstract is in the attachment
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Discontinuous Galerkin Based Multi-Domain Multi-Solver Technique for Efficient Multiscale Electromagnetic Modeling
… be directly obtained. In addition, some useful boundary conditions, including scattering boundary condition (SCBC), surface impedance boundary condition (SIBC) and impedance transition boundary condition (ITBC), are incorporated into the proposed DGFD framework to further improve its performance …
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Efficient Finite Element Electromagnetic Analysis for High-Frequency/High-Speed Circuits And Multiconductor Transmission Lines
… several other techniques to improve the matrix conditioning and extend full-wave solutions down to very low frequencies for a more robust broadband characterization of high-speed digital circuits. (4) A combined domain decomposition–model order reduction (DD–MOR) method for efficient full-wave …