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Sensitivity Analysis of Network Parameters With Electromagnetic FrequencyDomain Simulators
"... Abstract—A new practical approach to sensitivity analysis of the network parameters of highfrequency structures with commercial fullwave electromagnetic (EM) solvers is proposed. We show that the computation of the linearnetwork parameter derivatives in the designparameter space does not require ..."
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Abstract—A new practical approach to sensitivity analysis of the network parameters of highfrequency structures with commercial fullwave electromagnetic (EM) solvers is proposed. We show that the computation of the linearnetwork parameter derivatives in the designparameter space does not require an adjointproblem solution. The sensitivities are computed outside the EM solver, which simplifies the implementation. We discuss: 1) features of commercial EM solvers which allow the user to compute network parameters and their sensitivities through a single fullwave simulation; 2) the accuracy of the computed derivatives; and 3) the overhead of the sensitivity computation. Through examples based on FEMLAB and FEKO simulations, comparisons are made with the forward finitedifference derivative estimates in terms of accuracy and CPU time. Index Terms—Adjointvariable methods, design automation, frequencydomain analysis, sensitivity analysis. I.
TRANSIENT ADJOINT SENSITIVITIES FOR DISCON TINUITIES WITH GAUSSIAN MATERIAL DISTRIBU TIONS
, 2010
"... Abstract—We present a novel approach for adjoint transient sensitivity analysis with respect to discontinuities with spacedependent materials exhibiting known distribution. Our approach integrates the Time Domain TransmissionLineModeling (TDTLM) with the Adjoint Variable Method (AVM). Using only ..."
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Abstract—We present a novel approach for adjoint transient sensitivity analysis with respect to discontinuities with spacedependent materials exhibiting known distribution. Our approach integrates the Time Domain TransmissionLineModeling (TDTLM) with the Adjoint Variable Method (AVM). Using only one extra TDTLM simulation, the sensitivities of the observed response with respect to all the parameters of the Gaussian distribution are obtained. The accuracy of our sensitivity analysis approach is illustrated through a number of different 2D and 3D examples. Using the previous sensitivities, gradient–based optimization technique is applied to exploit in the location and profile of various inhomogeneous material Gaussian distribution for inverse problems. This method can be repeated for any continuous or discontinuous distributions that exist in electromagnetic imaging for space dependent materials like cancer detection. 1.
SENSITIVITY ANALYSIS OF SCATTERING PARAMETERS AND ITS APPLICATIONS SENSITIVITY ANALYSIS OF SCATTERING PARAMETERS AND ITS APPLICATIONS By
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the past five years, to the happiness and sharing with my family and friends.
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"... Boundary shape optimization is a technique to search for an optimal shape by modifying the boundary of a device with a prespecified topology. We consider boundary shape optimization of acoustic horns in loudspeakers and brass wind instruments. A horn is an interfacial device, situated between a sou ..."
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Boundary shape optimization is a technique to search for an optimal shape by modifying the boundary of a device with a prespecified topology. We consider boundary shape optimization of acoustic horns in loudspeakers and brass wind instruments. A horn is an interfacial device, situated between a source, such as a waveguide or a transducer, and surrounding space. Horns are used to control both the transmission properties from the source and the spatial power distribution in the farfield (directivity patterns). Transmission and directivity properties of a horn are sensitive to the shape of the horn flare. By changing the horn flare we design transmission efficient horns. However, it is difficult to achieve both controllability of directivity patterns and high transmission efficiency by using only changes in the horn flare. Therefore we use simultaneous shape and socalled topology optimization to design a horn/acousticlens combination to achieve high transmission efficiency and even directivity. We also design transmission efficient interfacial devices without imposing an upper constraint on the mouth diameter. The results demonstrate that there appears to be a natural limit on the optimal mouth diameter. We optimize brasswind instruments with respect to its intonation properties. The instrument
1 EXTRACTING THE DERIVATIVES OF NETWORK PARAMETERS FROM FREQUENCYDOMAIN ELECTROMAGNETIC SOLUTIONS
"... Abstract: We present a methodology for extracting the gradients of the network parameters in the design parameter space from fullwave highfrequency solutions provided by commercial electromagnetic (EM) solvers. We consider frequencydomain solvers. We show that the derivatives of network parameter ..."
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Abstract: We present a methodology for extracting the gradients of the network parameters in the design parameter space from fullwave highfrequency solutions provided by commercial electromagnetic (EM) solvers. We consider frequencydomain solvers. We show that the derivatives of network parameters such as the Y, Z, and Sparameters can be obtained from the fullwave solution with little overhead. Our approach exploits the theory of adjoint sensitivity analysis applied to selfadjoint problems. When the system matrix generated by the solver is symmetric (selfadjoint), such as in the finiteelement method, the approach is unconditionally applicable. For the method of moments, which usually generates an asymmetric system matrix, it is applicable with a convergent solution. Our method requires that the solver gives access to: 1) the system matrix, and 2) the solution vector. Also, the user needs to have limited control over the meshing such that the mesh size and structure do not change as shape design parameters are perturbed. The design parameters may relate to both the shape and the materials of the structure. The gradient information is intended for gradientbased optimization, advanced modeling techniques, and for tolerance analysis.