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A novel hydraulic fracture scattering simulation method in the hydrocarbon diagnosis is developed in this article. The traditional thin dielectric structure-based surface integral equation (TDS-SIE) is adopted for accurate and stable fracture scattering analysis. To improve the low simulation efficiency of conventional TDS-SIE, a higher order TDS-SIE (HO-TDS-SIE) is developed in this article. The junction vector bases are defined to extend TDS-SIE for the branched fractures. Moreover, the matrix normalization method is adopted to improve the conditioning of impedance matrices and accelerate the convergence rate. The excellent performance of this new HO-TDS-SIE solver for complex hydraulic fracture and network is validated by numerical experiments. To best of our knowledge, this is the first time to extend TDS-SIE into higher order scheme for accurate fracture scattering simulation. [ABSTRACT FROM AUTHOR]

This paper presents a novel accurate and stable current and charge integral equation (CCIE) solver for the low-frequency scattering of penetrable objects in layered medium (LM). To the best of our knowledge, this is the first time to extend CCIE into LM simulations at low frequency. In order to integrate the matrix-friendly LM Green’s functions (LMGFs) into CCIE, we have rederived them to define new quasi-vector/scalar potentials, which are able to annihilate the frequency singularity in the original LMGFs. Moreover, an effective preconditioner is adopted to improve the conditioning of impedance matrices. In comparison with other perconditioners, this method performs much better. The excellent performance of this new CCIE solver is then demonstrated by numerical experiments. [ABSTRACT FROM AUTHOR]

High-precision position control of linear-switched reluctance motor (LSRM) is important in motion-control industry. The static model-based controller sometimes cannot give satisfactory output performance due to the inherent nonlinearities of LSRM and the uncertainties of the system. In this paper, a self-tuning regulator (STR) based on the pole-placement algorithm is proposed for high-precision position tracking of the LSRM. Following the time-scale characteristics analysis of LSRM position-tracking system and force-characteristic investigation, the position-tracking model is treated as a second-order system. Different from the static model-based control schemes, the dynamic model of the LSRM can be obtained by online estimation. Also, some practical aspects are taken into account. Owing to the unmodeled dynamics and high-frequency measurement noises, there are some oscillations in the practical control signals, and they can be reduced by a properly designed filter. Both the simulation and experimental results demonstrate that, in the control of the proposed STR, the position-tracking system can reproduce the reference signal with the desired performance in harsh ambient. These results confirm that the method is effective and robust in the high-precision position tracking of LSRM. [ABSTRACT FROM PUBLISHER]