Pub Date : 2024-02-08DOI: 10.1109/JMMCT.2024.3364084
Johan Helsing;Shidong Jiang;Anders Karlsson
This work concerns the design of perfectly conducting objects that are invisible to an incident transverse magnetic plane wave. The object in question is a finite planar waveguide with a finite periodic array of barriers. By optimizing this array, the amplitude of the scattered field is reduced to less than $10^{-9}$ times the amplitude of the incident plane wave everywhere outside the waveguide. To accurately evaluate such minute amplitudes, we employ a recently developed boundary integral equation technique, adapted for objects whose boundaries have endpoints, corners, and branch points.
{"title":"Design of Perfectly Conducting Objects That Are Invisible to an Incident Plane Wave","authors":"Johan Helsing;Shidong Jiang;Anders Karlsson","doi":"10.1109/JMMCT.2024.3364084","DOIUrl":"https://doi.org/10.1109/JMMCT.2024.3364084","url":null,"abstract":"This work concerns the design of perfectly conducting objects that are invisible to an incident transverse magnetic plane wave. The object in question is a finite planar waveguide with a finite periodic array of barriers. By optimizing this array, the amplitude of the scattered field is reduced to less than \u0000<inline-formula><tex-math>$10^{-9}$</tex-math></inline-formula>\u0000 times the amplitude of the incident plane wave everywhere outside the waveguide. To accurately evaluate such minute amplitudes, we employ a recently developed boundary integral equation technique, adapted for objects whose boundaries have endpoints, corners, and branch points.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"104-112"},"PeriodicalIF":2.3,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140014805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-25DOI: 10.1109/JMMCT.2024.3358327
Yang Su;Yu Mao Wu
The iterative physical optics (IPO) method is a valuable technique for analyzing coupled scattering problems. In contrast to the fast physical optics (FPO) method, this article proposes an iterative physical optics method based on quadratic quadrilateral patches (QIPO). Specifically, quadratic patches in the QIPO method offer higher-order accuracy in calculating normal vectors which greatly benefits the accuracy of the iterative induction current. Then, a lit-shadow judgment criterion is introduced, and a general iteration formulation for proposed method is presented. Additionally, new amplitude and phase function expressions suitable for the QIPO method are proposed to accurately compute the far-field results. It is also verified for the case of discretization with quadratic triangular patches (QTIPO). To address numerical singularities, the QIPO method considers a linear phase function, where closed-form solution are provided. The results demonstrate the effectiveness of the treatment in handling singular cases. The accuracy of the QIPO method is validated through comparisons with existing results. Finally, numerical examples confirm that the proposed method reduces the number of patches, minimizes the computational cost of induced current iteration, and accurately calculates far-field results.
{"title":"A Fast Iterative Physical Optics Method With Quadratic Amplitude and Phase Integral Terms","authors":"Yang Su;Yu Mao Wu","doi":"10.1109/JMMCT.2024.3358327","DOIUrl":"https://doi.org/10.1109/JMMCT.2024.3358327","url":null,"abstract":"The iterative physical optics (IPO) method is a valuable technique for analyzing coupled scattering problems. In contrast to the fast physical optics (FPO) method, this article proposes an iterative physical optics method based on quadratic quadrilateral patches (QIPO). Specifically, quadratic patches in the QIPO method offer higher-order accuracy in calculating normal vectors which greatly benefits the accuracy of the iterative induction current. Then, a lit-shadow judgment criterion is introduced, and a general iteration formulation for proposed method is presented. Additionally, new amplitude and phase function expressions suitable for the QIPO method are proposed to accurately compute the far-field results. It is also verified for the case of discretization with quadratic triangular patches (QTIPO). To address numerical singularities, the QIPO method considers a linear phase function, where closed-form solution are provided. The results demonstrate the effectiveness of the treatment in handling singular cases. The accuracy of the QIPO method is validated through comparisons with existing results. Finally, numerical examples confirm that the proposed method reduces the number of patches, minimizes the computational cost of induced current iteration, and accurately calculates far-field results.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"92-103"},"PeriodicalIF":2.3,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139727579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-23DOI: 10.1109/JMMCT.2024.3355976
Zhonggen Wang;Chenwei Li;Yufa Sun;Wenyan Nie;Xuejun Zhang;Pan Wang
The hyper basis functions (HBF)-based MoM has been proven to be an efficient numerical method to analyze broadband electromagnetic scattering problems. However, this method costs a lot of time to reconstruct the impedance matrix and reduced matrix at each frequency point. In order to solve the above problem, a novel method combining HBF-based MoM and compressive sensing (CS) has been proposed in this paper. The proposed method first applies the characteristic modes (CM) derived at the highest frequency point as the HBF for solving the scattering problems at lower frequency points, and performs sparse transform of the induced currents as the sparse basis for the CS framework. Then the measurement matrix is constructed using the method of uniformly extracting the impedance matrix by rows to obtain stable calculation results. Finally, according to the prior condition that a few CM are sufficient to characterize the surface currents approximately, the recovery algorithm is simplified least square method to reconstruct the current coefficients. Numerical simulation results show that it can significantly improve the efficiency of solving broadband electromagnetic problems compared with HBF-based MoM.
{"title":"Fast Analysis of Broadband Electromagnetic Scattering Problems by Combining Hyper Basis Functions-Based MoM With Compressive Sensing","authors":"Zhonggen Wang;Chenwei Li;Yufa Sun;Wenyan Nie;Xuejun Zhang;Pan Wang","doi":"10.1109/JMMCT.2024.3355976","DOIUrl":"https://doi.org/10.1109/JMMCT.2024.3355976","url":null,"abstract":"The hyper basis functions (HBF)-based MoM has been proven to be an efficient numerical method to analyze broadband electromagnetic scattering problems. However, this method costs a lot of time to reconstruct the impedance matrix and reduced matrix at each frequency point. In order to solve the above problem, a novel method combining HBF-based MoM and compressive sensing (CS) has been proposed in this paper. The proposed method first applies the characteristic modes (CM) derived at the highest frequency point as the HBF for solving the scattering problems at lower frequency points, and performs sparse transform of the induced currents as the sparse basis for the CS framework. Then the measurement matrix is constructed using the method of uniformly extracting the impedance matrix by rows to obtain stable calculation results. Finally, according to the prior condition that a few CM are sufficient to characterize the surface currents approximately, the recovery algorithm is simplified least square method to reconstruct the current coefficients. Numerical simulation results show that it can significantly improve the efficiency of solving broadband electromagnetic problems compared with HBF-based MoM.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"84-91"},"PeriodicalIF":2.3,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139710586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-16DOI: 10.1109/JMMCT.2024.3354489
Qazi Mashaal Khan;Dan Kuylenstierna
This research delves into losses of X-band cavity resonators manufactured using additive manufacturing-selective laser melting (AM-SLM) compared to the standard subtractive manufacturing milling technology. Measured losses are benchmarked in terms of resonator (quality) $Q$ -factor. The measured data is further modelled using the Groiss and one-ball Huray models taking into account the implications of surface roughness and electrical conductivity. The unloaded $Q$ -factor is derived from frequency-dependent scattering ( $S$ ) parameters obtained from measurements and full-wave simulations. Surface roughness was found to impact the $Q$ -factor significantly and the resonant frequency marginally. Cavities based on AM-SLM technology exhibit higher roughness compared to milling and lowers the $Q$ -factor. A fusion of both manufacturing methods by milling AM-SLM cavity walls demonstrates an augmented $Q$ -factor compared to a directly printed cavity. In the study it was also found that the Groiss model tends to overestimate the $Q$ -factor owing to AM-SLM's rougher surface, while the one-ball Huray model furnishes precise projections by establishing a link between surface roughness and powder particles. Electrical conductivity's influence on $Q$ -factor was also investigated, showing negligible impact with increased surface roughness. Further, side walls of the AM-SLM cavity were more susceptible to surface roughness, compared to the cavity front walls due to higher surface current density. This study underscores the significance of analyzing surface roughness and electrical conductivity in AM-SLM cavity resonators and highlights the suitability of the one-ball Huray model for accurate $Q$ -factor prediction of microwave structures with rough surfaces.
{"title":"Analysis of Q-Factor for AM-SLM Cavity Based Resonators Using Surface Roughness Models","authors":"Qazi Mashaal Khan;Dan Kuylenstierna","doi":"10.1109/JMMCT.2024.3354489","DOIUrl":"https://doi.org/10.1109/JMMCT.2024.3354489","url":null,"abstract":"This research delves into losses of X-band cavity resonators manufactured using additive manufacturing-selective laser melting (AM-SLM) compared to the standard subtractive manufacturing milling technology. Measured losses are benchmarked in terms of resonator (quality) \u0000<inline-formula><tex-math>$Q$</tex-math></inline-formula>\u0000-factor. The measured data is further modelled using the Groiss and one-ball Huray models taking into account the implications of surface roughness and electrical conductivity. The unloaded \u0000<inline-formula><tex-math>$Q$</tex-math></inline-formula>\u0000-factor is derived from frequency-dependent scattering (\u0000<inline-formula><tex-math>$S$</tex-math></inline-formula>\u0000) parameters obtained from measurements and full-wave simulations. Surface roughness was found to impact the \u0000<inline-formula><tex-math>$Q$</tex-math></inline-formula>\u0000-factor significantly and the resonant frequency marginally. Cavities based on AM-SLM technology exhibit higher roughness compared to milling and lowers the \u0000<inline-formula><tex-math>$Q$</tex-math></inline-formula>\u0000-factor. A fusion of both manufacturing methods by milling AM-SLM cavity walls demonstrates an augmented \u0000<inline-formula><tex-math>$Q$</tex-math></inline-formula>\u0000-factor compared to a directly printed cavity. In the study it was also found that the Groiss model tends to overestimate the \u0000<inline-formula><tex-math>$Q$</tex-math></inline-formula>\u0000-factor owing to AM-SLM's rougher surface, while the one-ball Huray model furnishes precise projections by establishing a link between surface roughness and powder particles. Electrical conductivity's influence on \u0000<inline-formula><tex-math>$Q$</tex-math></inline-formula>\u0000-factor was also investigated, showing negligible impact with increased surface roughness. Further, side walls of the AM-SLM cavity were more susceptible to surface roughness, compared to the cavity front walls due to higher surface current density. This study underscores the significance of analyzing surface roughness and electrical conductivity in AM-SLM cavity resonators and highlights the suitability of the one-ball Huray model for accurate \u0000<inline-formula><tex-math>$Q$</tex-math></inline-formula>\u0000-factor prediction of microwave structures with rough surfaces.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"75-83"},"PeriodicalIF":2.3,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139654885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-03DOI: 10.1109/JMMCT.2024.3349433
Thomas E. Roth;Samuel T. Elkin
In superconducting circuit quantum information technologies, classical microwave pulses are applied to control and measure the qubit states. Currently, the design of these microwave pulses uses simple theoretical or numerical models that do not account for the self-consistent interactions of how the qubit state modifies the applied microwave pulse. In this work, we present the formulation and finite element time domain discretization of a semiclassical Maxwell-Schrödinger method for describing these self-consistent dynamics for the case of a superconducting qubit capacitively coupled to a general transmission line network. We validate the proposed method by characterizing key effects related to common control and measurement approaches for transmon and fluxonium qubits in systems that are amenable to theoretical analysis. Our numerical results also highlight scenarios where including the self-consistent interactions is essential. By treating the microwaves classically, our method is substantially more efficient than fully-quantum methods for the many situations where the quantum statistics of the microwaves are not needed. Further, our approach does not require any reformulations when the transmission line system is modified. In the future, our method can be used to rapidly explore broader design spaces to search for more effective control and measurement protocols for superconducting qubits.
{"title":"Maxwell-Schrödinger Modeling of a Superconducting Qubit Coupled to a Transmission Line Network","authors":"Thomas E. Roth;Samuel T. Elkin","doi":"10.1109/JMMCT.2024.3349433","DOIUrl":"https://doi.org/10.1109/JMMCT.2024.3349433","url":null,"abstract":"In superconducting circuit quantum information technologies, classical microwave pulses are applied to control and measure the qubit states. Currently, the design of these microwave pulses uses simple theoretical or numerical models that do not account for the self-consistent interactions of how the qubit state modifies the applied microwave pulse. In this work, we present the formulation and finite element time domain discretization of a semiclassical Maxwell-Schrödinger method for describing these self-consistent dynamics for the case of a superconducting qubit capacitively coupled to a general transmission line network. We validate the proposed method by characterizing key effects related to common control and measurement approaches for transmon and fluxonium qubits in systems that are amenable to theoretical analysis. Our numerical results also highlight scenarios where including the self-consistent interactions is essential. By treating the microwaves classically, our method is substantially more efficient than fully-quantum methods for the many situations where the quantum statistics of the microwaves are not needed. Further, our approach does not require any reformulations when the transmission line system is modified. In the future, our method can be used to rapidly explore broader design spaces to search for more effective control and measurement protocols for superconducting qubits.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"61-74"},"PeriodicalIF":2.3,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139473800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-22DOI: 10.1109/JMMCT.2023.3345798
Xinling Yu;José E. C. Serrallés;Ilias I. Giannakopoulos;Ziyue Liu;Luca Daniel;Riccardo Lattanzi;Zheng Zhang
We propose Physics-Informed Fourier Networks for Electrical Properties (EP) Tomography (PIFON-EPT), a novel deep learning-based method for EP reconstruction using noisy and/or incomplete magnetic resonance (MR) measurements. Our approach leverages the Helmholtz equation to constrain two networks, responsible for the denoising and completion of the transmit fields, and the estimation of the object's EP, respectively. We embed a random Fourier features mapping into our networks to enable efficient learning of high-frequency details encoded in the transmit fields. We demonstrated the efficacy of PIFON-EPT through several simulated experiments at 3 and 7 T (T) MR imaging, and showed that our method can reconstruct physically consistent EP and transmit fields. Specifically, when only 20% of the noisy measured fields were used as inputs, PIFON-EPT reconstructed the EP of a phantom with $leq 5%$ error, and denoised and completed the measurements with $leq 1%$ error. Additionally, we adapted PIFON-EPT to solve the generalized Helmholtz equation that accounts for gradients of EP between inhomogeneities. This yielded improved results at interfaces between different materials without explicit knowledge of boundary conditions. PIFON-EPT is the first method that can simultaneously reconstruct EP and transmit fields from incomplete noisy MR measurements, providing new opportunities for EPT research.
我们提出了用于电特性（EP）断层扫描的物理信息傅立叶网络（PIFON-EPT），这是一种基于深度学习的新方法，用于利用有噪声和/或不完整的磁共振（MR）测量结果重建电特性。我们的方法利用亥姆霍兹方程来约束两个网络，分别负责传输场的去噪和补全，以及对象 EP 的估计。我们在网络中嵌入了随机傅立叶特征映射，以便高效学习发射场中的高频细节编码。我们通过 3 T 和 7 T 磁共振成像的几个模拟实验证明了 PIFON-EPT 的功效，并表明我们的方法可以重建物理上一致的 EP 和发射场。具体来说，当只有20%的噪声测量场被用作输入时，PIFON-EPT重建的幻影EP误差为5%，去噪并完成测量的误差为1%。此外，我们对 PIFON-EPT 进行了调整，以求解广义亥姆霍兹方程，该方程考虑了非均质间 EP 的梯度。这改进了不同材料界面的结果，而无需明确了解边界条件。PIFON-EPT 是第一种能从不完整的噪声磁共振测量中同时重建 EP 和透射场的方法，为 EPT 研究提供了新的机遇。
{"title":"PIFON-EPT: MR-Based Electrical Property Tomography Using Physics-Informed Fourier Networks","authors":"Xinling Yu;José E. C. Serrallés;Ilias I. Giannakopoulos;Ziyue Liu;Luca Daniel;Riccardo Lattanzi;Zheng Zhang","doi":"10.1109/JMMCT.2023.3345798","DOIUrl":"https://doi.org/10.1109/JMMCT.2023.3345798","url":null,"abstract":"We propose Physics-Informed Fourier Networks for Electrical Properties (EP) Tomography (PIFON-EPT), a novel deep learning-based method for EP reconstruction using noisy and/or incomplete magnetic resonance (MR) measurements. Our approach leverages the Helmholtz equation to constrain two networks, responsible for the denoising and completion of the transmit fields, and the estimation of the object's EP, respectively. We embed a random Fourier features mapping into our networks to enable efficient learning of high-frequency details encoded in the transmit fields. We demonstrated the efficacy of PIFON-EPT through several simulated experiments at 3 and 7 T (T) MR imaging, and showed that our method can reconstruct physically consistent EP and transmit fields. Specifically, when only 20% of the noisy measured fields were used as inputs, PIFON-EPT reconstructed the EP of a phantom with \u0000<inline-formula><tex-math>$leq 5%$</tex-math></inline-formula>\u0000 error, and denoised and completed the measurements with \u0000<inline-formula><tex-math>$leq 1%$</tex-math></inline-formula>\u0000 error. Additionally, we adapted PIFON-EPT to solve the generalized Helmholtz equation that accounts for gradients of EP between inhomogeneities. This yielded improved results at interfaces between different materials without explicit knowledge of boundary conditions. PIFON-EPT is the first method that can simultaneously reconstruct EP and transmit fields from incomplete noisy MR measurements, providing new opportunities for EPT research.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"49-60"},"PeriodicalIF":2.3,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139399804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-20DOI: 10.1109/JMMCT.2023.3334563
Suman Yadav;Gourav Kumar Suman;Ram Krishna Mehta
DC bias in high-voltage DC transformers, arising from converter operations and DC transmission, poses significant challenges to their performance. The detrimental effects of DC bias primarily manifest in increased temperature, jeopardizing the safe operation of the transformers. This article presents a novel approach by extending the utilization of the Thermal Equivalent Circuit (TEC) to accurately predict temperatures at different elements of a converter transformer under DC bias conditions. Specifically designed for a 240 MVA converter transformer, the TEC incorporates capacitances and dynamic resistances as model parameters. Additionally, an electro-thermal finite element model is implemented to comprehensively analyze the transformer's behavior under varying levels of DC bias. To estimate the TEC parameters, a hybrid GWO-CS (Grey Wolf Optimization – Cuckoo Search) algorithm is employed based on measured values. Furthermore, the paper highlights the impact of DC bias on the converter transformer's life expectancy, considering the aging acceleration factor.
{"title":"Enhanced Thermodynamic Modeling of Converter Transformer Influenced by DC Bias","authors":"Suman Yadav;Gourav Kumar Suman;Ram Krishna Mehta","doi":"10.1109/JMMCT.2023.3334563","DOIUrl":"https://doi.org/10.1109/JMMCT.2023.3334563","url":null,"abstract":"DC bias in high-voltage DC transformers, arising from converter operations and DC transmission, poses significant challenges to their performance. The detrimental effects of DC bias primarily manifest in increased temperature, jeopardizing the safe operation of the transformers. This article presents a novel approach by extending the utilization of the Thermal Equivalent Circuit (TEC) to accurately predict temperatures at different elements of a converter transformer under DC bias conditions. Specifically designed for a 240 MVA converter transformer, the TEC incorporates capacitances and dynamic resistances as model parameters. Additionally, an electro-thermal finite element model is implemented to comprehensively analyze the transformer's behavior under varying levels of DC bias. To estimate the TEC parameters, a hybrid GWO-CS (Grey Wolf Optimization – Cuckoo Search) algorithm is employed based on measured values. Furthermore, the paper highlights the impact of DC bias on the converter transformer's life expectancy, considering the aging acceleration factor.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"36-48"},"PeriodicalIF":2.3,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138822201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the analytical-cum-numerical-based mathematical model for the multiphysics simulation of a high-speed unipolar axial eddy current brake (ECB). The operating principle and the necessary multiphysics simulation for an ECB are introduced. An analytical method is developed for high-speed ECB operation to search coarse parameters in the preliminary design technique. The model uses the behavior of the eddy currents on the plate during high-speed operation. A radial multiplier is incorporated to satisfy electromagnetic physics. The axisymmetric property of the disk reduces the disk geometry to an equivalent 2D domain where the estimated loss is defined. The ohmic loss from the analytical model is transferred to the numerical thermal model to evaluate temperature distribution. The convective heat transfer coefficient, which is a crucial variable in boundary conditions, is defined using the correlations between the Nusselt and Reynolds numbers. The steady-state heat diffusion equation is solved in the domain for three different speeds. The results show that the ohmic loss on the disk saturates and the temperature of the disk reduces during high-speed operations.
{"title":"Multiphysics Analysis of a High-Speed Eddy Current Brake","authors":"Sandeep Mohan Nayak;Mangal Kothari;Abhishek Sarkar;Soumya Ranjan Sahoo","doi":"10.1109/JMMCT.2023.3333386","DOIUrl":"https://doi.org/10.1109/JMMCT.2023.3333386","url":null,"abstract":"This paper presents the analytical-cum-numerical-based mathematical model for the multiphysics simulation of a high-speed unipolar axial eddy current brake (ECB). The operating principle and the necessary multiphysics simulation for an ECB are introduced. An analytical method is developed for high-speed ECB operation to search coarse parameters in the preliminary design technique. The model uses the behavior of the eddy currents on the plate during high-speed operation. A radial multiplier is incorporated to satisfy electromagnetic physics. The axisymmetric property of the disk reduces the disk geometry to an equivalent 2D domain where the estimated loss is defined. The ohmic loss from the analytical model is transferred to the numerical thermal model to evaluate temperature distribution. The convective heat transfer coefficient, which is a crucial variable in boundary conditions, is defined using the correlations between the Nusselt and Reynolds numbers. The steady-state heat diffusion equation is solved in the domain for three different speeds. The results show that the ohmic loss on the disk saturates and the temperature of the disk reduces during high-speed operations.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"27-35"},"PeriodicalIF":2.3,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138468117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-16DOI: 10.1109/JMMCT.2023.3333563
Roberto D. Graglia;Paolo Petrini
Successful three-dimensional finite element codes for Maxwell's equations must include and deal with all four types of geometrical shapes: tetrahedra, bricks, prisms, and quadrangular-based pyramids. However, pyramidal elements have so far been used very rarely because the basis functions associated with them have complicated expression, are complex in derivation, and have never been comprehensively validated. We recently published a simpler procedure for constructing higher-order vector bases for pyramid elements, so here we fill a gap by discussing a whole set of test case results that not only validate our new curl-conforming bases for pyramids, but which enable validation of other codes that use pyramidal elements for finite element method applications. The solutions of the various test cases are obtained using either higher order elements or multipyramidal meshes or both. Furthermore, the results are always compared with the solutions obtained with classical tetrahedral meshes using higher order bases. This allows us to verify that purely pyramidal meshes and elements give numerical results of comparable accuracy to those obtained with multitetrahedral meshes that use elements of the same order, essentially requiring the same number of degrees of freedom. The various results provided here also show that higher order vector bases always guarantee a superior convergence of the numerical results as the number of degrees of freedom increases.
{"title":"Assessing Curl-Conforming Bases for Pyramid Cells","authors":"Roberto D. Graglia;Paolo Petrini","doi":"10.1109/JMMCT.2023.3333563","DOIUrl":"https://doi.org/10.1109/JMMCT.2023.3333563","url":null,"abstract":"Successful three-dimensional finite element codes for Maxwell's equations must include and deal with all four types of geometrical shapes: tetrahedra, bricks, prisms, and quadrangular-based pyramids. However, pyramidal elements have so far been used very rarely because the basis functions associated with them have complicated expression, are complex in derivation, and have never been comprehensively validated. We recently published a simpler procedure for constructing higher-order vector bases for pyramid elements, so here we fill a gap by discussing a whole set of test case results that not only validate our new curl-conforming bases for pyramids, but which enable validation of other codes that use pyramidal elements for finite element method applications. The solutions of the various test cases are obtained using either higher order elements or multipyramidal meshes or both. Furthermore, the results are always compared with the solutions obtained with classical tetrahedral meshes using higher order bases. This allows us to verify that purely pyramidal meshes and elements give numerical results of comparable accuracy to those obtained with multitetrahedral meshes that use elements of the same order, essentially requiring the same number of degrees of freedom. The various results provided here also show that higher order vector bases always guarantee a superior convergence of the numerical results as the number of degrees of freedom increases.","PeriodicalId":52176,"journal":{"name":"IEEE Journal on Multiscale and Multiphysics Computational Techniques","volume":"9 ","pages":"20-26"},"PeriodicalIF":2.3,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10319679","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138435637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-23DOI: 10.1109/JMMCT.2023.3326774
Chang Yang;Dan Jiao
In this work, we develop a kernel-independent and purely algebraic method, Nested Construction Method, which can construct a rank-minimized ${mathcal H}^{2}$ -matrix with low complexity based on prescribed accuracy. The time cost of this method in generating each cluster basis and coupling matrix is of $O(k n log {n})$ , while the memory consumption scales as $O(k^{2})$ , where $k$ is the rank of the cluster basis, and $n$ is cluster size. The accuracy and efficiency of the proposed method are demonstrated by extensive numerical experiments. In addition to surface integral equations, the proposed algorithms can also be applied to solving other electrically large integral equations.
在这项工作中，我们开发了一种核无关的纯代数方法，即嵌套构造方法，它可以在规定精度的基础上构造一个低复杂度的秩最小化${mathcal H}^{2}$-矩阵。该方法生成每个簇基和耦合矩阵的时间成本为$O(k n log {n})$，而内存消耗为$O(k^{2})$，其中$k$为簇基的秩，$n$为簇大小。大量的数值实验证明了该方法的准确性和有效性。除了曲面积分方程外，所提出的算法也可应用于求解其他大型电积分方程。
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