Research on Control Strategy of Free-Piston Stirling Power Generating System

As a clean and fuel adaptive alternative power plant, the Stirling power generating system has drawn attention of experts and scholars in the energy field. In practical application, the instability of free-piston Stirling power generating system caused by abrupt load change is an inevitable problem. Thus, methods to improve the output frequency response and stability of the free-piston Stirling power generating system are necessary. The model of free-piston Stirling power generating system is built by isothermal analysis firstly, and the initial control strategy based on given voltage system is put forward. To further improve the performance of power system, a current feedback decoupling control strategy is proposed, and the mathematical model is established. The influence of full decoupled quadrature-direct (d-q) axis currents is analyzed with respect to the output voltage adjusting time and fluctuation amplitude under the variations of piston displacement and output load. The simulation results show that the system performance is significantly improved, but the dynamic regulation lags caused by the decoupled current control still exist. To solve this problem and improve the performance of decoupled-state feedback current control that relies on parameter accuracy, internal model control based on sliding mode (IMC-SM) current decoupling control strategy is proposed, the system model is established, and then the performance of voltage ripple in generating mode is improved. Finally, the test bench is built, and the steady state and transient voltage control performances are tested. The feasibility and priority of the control strategy is verified by experiment and simulation results

Video Synchronization And Its Application To Object Transfer

In video post-production applications, camera motion analysis and alignment are important in order to ensure the geometric correctness and temporal consistency. In this paper, we trade some generality in estimating and aligning camera motion for reduced computational complexity and increased image-based nature. The main contribution is to use fundamental ratios to synchronize video sequences of distinct scenes captured by cameras undergoing similar motions. We also present a simple method to align 3D camera trajectories when the fundamental ratios are not able to match the noisy trajectories. Experimental results show that our method can accurately synchronize sequences even when the scenes are totally different and have dense depths. An application on 3D object transfer is also demonstrated. © 2009 Elsevier B.V