This paper reviews the recent progress in photonic devices application of Ge-on-Si. Ge-on-Si materials and optical devices are suitable candidates for Si-based optoelectronic integration because of the mature epitaxia...This paper reviews the recent progress in photonic devices application of Ge-on-Si. Ge-on-Si materials and optical devices are suitable candidates for Si-based optoelectronic integration because of the mature epitaxial technique and the compatibility with Si complementary metal-oxide-semiconductor （CMOS） technology. Recently, the realities of electric-pump Ge light emitting diode （LED） and optical-pump pulse Ge laser, Ge quantum well modulator based on quantum Stark confined effect, waveguide Ge modulator based on Franz-Keldysh （FK） effect, and high performance near-infrared Ge detector, rendered the Si-based optoelectronic integration using Ge photonic devices. Ge-on-Si material is also an important platform to grow other materials on it for Si- based optoelectronic integration. InGaAs and GeSn have been grown on the Ge-on-Si. InGaAs LED and GeSn photodetector have been successfully fabricated as well.展开更多
Ship collision prevention has always been a hot topic of research for navigation safety.Recently,autonomous ships have gained much attention as a means of solving collision problems by machine control with a collision...Ship collision prevention has always been a hot topic of research for navigation safety.Recently,autonomous ships have gained much attention as a means of solving collision problems by machine control with a collision-avoidance algorithm.An important question is how to determine optimal path planning for autonomous ships.This paper proposes a path-planning method of collision avoidance for multi-ship encounters that is easy to realize for autonomous ships.The ship course-control system uses fuzzy adaptive proportion-integral-derivative(PID)control to achieve real-time control of the system.The automatic course-altering process of the ship is predicted by combining the ship-motion model and PID controller.According to the COLREGs,ships should take different actions in different encounter situations.Therefore,a scene-identification model is established to identify these situations.To avoid all the TSs,the applicable course-altering range of the OS is obtained by using the improved velocity obstacle model.The optimal path of collision avoidance can be determined from an applicable course-altering range combined with a scene-identification model.Then,the path planning of collision avoidance is realized in the multi-ship environment,and the simulation results show a good effect.The method conforms to navigation practice and provides an effective method for the study of collision avoidance.展开更多
基金Acknowledgements This work was supported by the National High Technology Research and Development Program of China （No. 2011AA010302）, the National Natural Science Foundation of China （Grant Nos. 61036003, 61176013, 60906035, 61177038）, and by Tsinghua National Laboratory for Information Science and Technology （TNList） Cross- discipline Foundation.
文摘This paper reviews the recent progress in photonic devices application of Ge-on-Si. Ge-on-Si materials and optical devices are suitable candidates for Si-based optoelectronic integration because of the mature epitaxial technique and the compatibility with Si complementary metal-oxide-semiconductor （CMOS） technology. Recently, the realities of electric-pump Ge light emitting diode （LED） and optical-pump pulse Ge laser, Ge quantum well modulator based on quantum Stark confined effect, waveguide Ge modulator based on Franz-Keldysh （FK） effect, and high performance near-infrared Ge detector, rendered the Si-based optoelectronic integration using Ge photonic devices. Ge-on-Si material is also an important platform to grow other materials on it for Si- based optoelectronic integration. InGaAs and GeSn have been grown on the Ge-on-Si. InGaAs LED and GeSn photodetector have been successfully fabricated as well.
基金supported by the Natural Science Foundation of China(grant no.52071249)the National Key Research and Development Program(grant no.2019YFB1600603).
文摘Ship collision prevention has always been a hot topic of research for navigation safety.Recently,autonomous ships have gained much attention as a means of solving collision problems by machine control with a collision-avoidance algorithm.An important question is how to determine optimal path planning for autonomous ships.This paper proposes a path-planning method of collision avoidance for multi-ship encounters that is easy to realize for autonomous ships.The ship course-control system uses fuzzy adaptive proportion-integral-derivative(PID)control to achieve real-time control of the system.The automatic course-altering process of the ship is predicted by combining the ship-motion model and PID controller.According to the COLREGs,ships should take different actions in different encounter situations.Therefore,a scene-identification model is established to identify these situations.To avoid all the TSs,the applicable course-altering range of the OS is obtained by using the improved velocity obstacle model.The optimal path of collision avoidance can be determined from an applicable course-altering range combined with a scene-identification model.Then,the path planning of collision avoidance is realized in the multi-ship environment,and the simulation results show a good effect.The method conforms to navigation practice and provides an effective method for the study of collision avoidance.
