Electromagnetic imaging of three-dimensional dielectric objects with Newton minimization

Etminan, Aslan; Sadeghi, Alireza; Gürel, L.

doi:10.1109/aps.2014.6904766

Cited by 5 publications

(2 citation statements)

References 5 publications

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“…We used the steepest-descent method [47,48] to minimize the cost function. If the cost difference between two consecutive iterations is less than a predetermined value, the algorithm is terminated.…”

Section: Circuit Model Of All N Loopsmentioning

confidence: 99%

Accelerating the co-simulation method for the design of transmit array coils for MRI

Sadeghi‐Tarakameh

Kazemivalipour

Gundogdu

et al. 2020

Magn Reson Mater Phy

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Objective Accelerating the co-simulation method for the design of transmit array (TxArray) coils is studied using equivalent circuit models. Materials and methods Although the co-simulation method dramatically reduces the complexity of the design of TxArray coils, finding the optimum solution is not trivial since there exist many local minima in the optimization problem. We propose to utilize an equivalent circuit model of the TxArray coil to obtain a proper initial guess for the optimization process of the co-simulation method. To prove the concept, six different TxArray coils (i.e., three degenerate birdcage coils (DBC), two dual-row head coils, and one elliptical body TxArray coil) with two different loading strategies (cylindrical phantom and human head/body model) at 3 T field strength are investigated theoretically; as an example study, an eight-channel head-DBC is constructed using the obtained values. Results This approach accelerates the design process more than 20-fold for the coils that are investigated in this manuscript. Conclusion A fast and accurate method for tuning and decoupling of a TxArray coil can be achieved using its equivalent circuit model combined with the co-simulation method.

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Section: Circuit Model Of All N Loopsmentioning

confidence: 99%

Accelerating the co-simulation method for the design of transmit array coils for MRI

Sadeghi‐Tarakameh

Kazemivalipour

Gundogdu

et al. 2020

Magn Reson Mater Phy

View full text Add to dashboard Cite

show abstract

“…the conductivity and permittivity distribution of 2-D [2] and 3-D investigation domains [3], as is the distorted Born iterative method [4], [5]. Other related works include utilizing the steepest descent method local minimizer to solve the inverse scattering problems [6] and perfect electric conductors [7]. Due to the nonlinearity of the inverse problem, the main disadvantage of microwave imaging systems based on local optimization algorithms is the convergence to one of the multiple local minima of the cost function, which may not necessarily be the desired solution (global solution).…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Imaging of Dielectric Objects Using a Multidirectional-Search-Based Simulated Annealing

Etminan

Moghaddam

2018

IEEE J. Multiscale Multiphys. Comput. Tech.

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In this paper, we introduce a global optimization method that is a novel combination of the simulated annealing method and the multi-directional search algorithm. We demonstrate the use of the algorithm for a microwave-imaging system to obtain the electrical properties of objects. The proposed global optimizer significantly improves the performance and speed of the simulated annealing method by utilizing a nonlinear simplex search, starting from an initial guess, and taking effective steps in obtaining the global solution of the minimization problem. Due to the efficient performance of the proposed global optimization method, we are able to obtain the shape, location, and material properties of the target without considering any a priori information about them. The accuracy and applicability of the proposed imaging method is demonstrated with some numerical results in which two-dimensional images of multiple objects are successfully reconstructed. Based on the optimization techniques utilized in the inverse-scattering problems, microwave imaging methods could be classified as two major groups, namely, local and global optimization methods. Due to the substantially higher speed of convergence in local optimization algorithms [1], they have been more popular in solving the inverse problsms. Born iterative method, for example, is widely used as an effective imaging method to obtain

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Microwave imaging of dielectric objects using a combination of simulated annealing and multi-directional search

Etminan

Moghaddam

2017

2017 IEEE International Symposium on Antennas and Propagation &Amp; USNC/URSI National Radio Science Meeting

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Electromagnetic imaging of three-dimensional dielectric objects with Newton minimization

Cited by 5 publications

References 5 publications

Accelerating the co-simulation method for the design of transmit array coils for MRI

Accelerating the co-simulation method for the design of transmit array coils for MRI

Electromagnetic Imaging of Dielectric Objects Using a Multidirectional-Search-Based Simulated Annealing

Microwave imaging of dielectric objects using a combination of simulated annealing and multi-directional search

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