Nevin Altunyurt

An equivalent circuit model for the wire-to-surface junction based on method of moments

A modified wire-to-surface junction basis function is proposed in this paper in order to facilitate the extraction of an equivalent circuit model for the wire-to-surface junction. The circuit extraction is based on an MPIE formulation. The extracted circuit model has been validated by the traditional EFIE formulation.

Accurate Evaluation of Field Interactions Between Cable Harness and Vehicle Body by a Multiple Scattering Method

Interactions between cable harness and vehicle body can be calculated using the full-wave method-of-moments (MoM) formulation. Although the full-wave MoM formulation can help us to calculate these interactions with great accuracy, it can be fairly time consuming when dealing with complex wire structures. On the other hand, the conventional multiconductor transmission-line theory can be used to obtain a simple model of the interactions, but only the effect of the transmission-line (TL)-mode current can be accounted for in this method. Starting with the complete electrical field integral equations, the current on a two-conductor thin wire structure due to incident field illumination can be decomposed into TL and antenna modes. Both modes can be solved using a SPICE solver in the form of Telegraphers equations. A proposed multiple scattering (MS) method based on a hybrid of TL and surface MoM can then be used to calculate interactions between thin wire structures, such as cable harness, and conductive surfaces, such as vehicle body. A test case shows that wire current computation using the proposed MS method takes less time but reaches the same accuracy compared to the full-wave MoM.

Multi-GPU Accelerated Admittance Method for High-Resolution Human Exposure Evaluation

Objective: A multi-graphics processing unit (GPU) accelerated admittance method solver is presented for solving the induced electric field in high-resolution anatomical models of human body when exposed to external low-frequency magnetic fields. Methods: In the solver, the anatomical model is discretized as a three-dimensional network of admittances. The conjugate orthogonal conjugate gradient (COCG) iterative algorithm is employed to take advantage of the symmetric property of the complex-valued linear system of equations. Compared against the widely used biconjugate gradient stabilized method, the COCG algorithm can reduce the solving time by 3.5 times and reduce the storage requirement by about 40%. The iterative algorithm is then accelerated further by using multiple NVIDIA GPUs. The computations and data transfers between GPUs are overlapped in time by using asynchronous concurrent execution design. The communication overhead is well hidden so that the acceleration is nearly linear with the number of GPU cards. Results: Numerical examples show that our GPU implementation running on four NVIDIA Tesla K20c cards can reach 90 times faster than the CPU implementation running on eight CPU cores (two Intel Xeon E5-2603 processors). Conclusion: The implemented solver is able to solve large dimensional problems efficiently. A whole adult body discretized in 1-mm resolution can be solved in just several minutes. Significance: The high efficiency achieved makes it practical to investigate human exposure involving a large number of cases with a high resolution that meets the requirements of international dosimetry guidelines.