The analysis of high-field RF field-tissue interactions requires high-performance finite-difference time-domain (FDTD) computing. Conventional CPU-based FDTD calculations offer limited computing performance in a PC environment. This study presents a graphics processing unit (GPU)-based parallel-computing framework, producing substantially boosted computing efficiency (with a two-order speedup factor) at a PC-level cost. Specific details of implementing the FDTD method on a GPU architecture have been presented and the new computational strategy has been successfully applied to the design of a novel 8-element transceive RF coil system at 9.4 T. Facilitated by the powerful GPU-FDTD computing, the new RF coil array offers optimized fields (averaging 25% improvement in sensitivity, and 20% reduction in loop coupling compared with conventional array structures of the same size) for small animal imaging with a robust RF configuration. The GPU-enabled acceleration paves the way for FDTD to be applied for both detailed forward modeling and inverse design of MRI coils, which were previously impractical.

In this paper, we propose a hybrid coordinated control method based on port-controlled Hamiltonian and backstepping to improve the position tracking performance for two degree of freedom SCARA robot. The port-controlled Hamiltonian (PCH) control is designated to ensure the stability of the system, and the backstepping control targets to improve the response speed of the system. Exponential function is used as a coordination function to achieve the coordinated control strategy to adapt to the position tracking control of 2-DOF SCARA robot. This hybrid coordination control system not only realizes a quick tracking control, but also improves the steady-state performance of the output signal. The simulation results show that when the external interference exists in the mechanical system of a 2-DOF SCARA robot, the hybrid tracking control system takes on the advantages of both methods, which shows good dynamic performance, good steady-state performance, and strong resistance to external interference.

This paper proposes a novel nonlinear control scheme based on energy-shaping (ES) principle and state error port-controlled Hamiltonian (PCH) systems for unmanned surface vehicles (USV) system. The PCH model of three degrees of freedom for USV kinetics system is established. By the ES principle, interconnection assignment and damping injection method is applied to the speed and heading control of the closed-loop USV system to realize an overall stability of control mechanism. Simulation results show that the validity and stability of control algorithm can be satisfied with the performance in speed and heading tracking of which the high simplification and portability make it applicable to the various region.