The emission wavelength of InGaN/GaN dot-in-wire LED can be tuned by modifying the nanowire diameter,but it causes mismatched angular distributions between blue,green,and red nanowires because of the excitation of dif...The emission wavelength of InGaN/GaN dot-in-wire LED can be tuned by modifying the nanowire diameter,but it causes mismatched angular distributions between blue,green,and red nanowires because of the excitation of different waveguide modes.Besides,the far-field radiation patterns and light extraction efficiency are typically calculated by center dipoles,which fails to provide accurate results.To address these issues,we first compare the simulation results between central dipole and dipole cloud with experimental data.Next,we calculate and analyze the display metrics for full-color nanowire LEDs by 3D dipole cloud.Finally,we achieve unnoticeable angular color shift within±20°viewing cone for augmented reality(AR)and virtual reality(VR)displays with an improved light extraction efficiency.展开更多
Planetary gear train plays a significant role in a helicopter operation and its health is of great importance for the flight safety of the helicopter. This paper investigates the effects of a planet carrier plate crac...Planetary gear train plays a significant role in a helicopter operation and its health is of great importance for the flight safety of the helicopter. This paper investigates the effects of a planet carrier plate crack on the dynamic characteristics of a planetary gear train, and thus finds an effec- tive method to diagnose crack fault. A dynamic model is developed to analyze the torsional vibra- tion of a planetary gear train with a cracked planet carrier plate. The model takes into consideration nonlinear factors such as the time-varying meshing stiffness, gear backlash and viscous damping. Investigation of the deformation of the cracked carrier plate under static stress is performed in order to simulate the dynamic effects of the planet carrier crack on the angular displacement of car- rier posts. Validation shows good accuracy of the developed dynamic model in predicting dynamic characteristics of a planetary gear train. Fault features extracted from predictions of the model reveal the correspondence between vibration characteristic and the conditions （length and position） of a planet carrier crack clearly.展开更多
文摘The emission wavelength of InGaN/GaN dot-in-wire LED can be tuned by modifying the nanowire diameter,but it causes mismatched angular distributions between blue,green,and red nanowires because of the excitation of different waveguide modes.Besides,the far-field radiation patterns and light extraction efficiency are typically calculated by center dipoles,which fails to provide accurate results.To address these issues,we first compare the simulation results between central dipole and dipole cloud with experimental data.Next,we calculate and analyze the display metrics for full-color nanowire LEDs by 3D dipole cloud.Finally,we achieve unnoticeable angular color shift within±20°viewing cone for augmented reality(AR)and virtual reality(VR)displays with an improved light extraction efficiency.
基金co-supported by the National Basic Research Program of China(2014CB046402)the Natural Science Foundation of China(Grant No.51175014)‘‘111" Project
文摘Planetary gear train plays a significant role in a helicopter operation and its health is of great importance for the flight safety of the helicopter. This paper investigates the effects of a planet carrier plate crack on the dynamic characteristics of a planetary gear train, and thus finds an effec- tive method to diagnose crack fault. A dynamic model is developed to analyze the torsional vibra- tion of a planetary gear train with a cracked planet carrier plate. The model takes into consideration nonlinear factors such as the time-varying meshing stiffness, gear backlash and viscous damping. Investigation of the deformation of the cracked carrier plate under static stress is performed in order to simulate the dynamic effects of the planet carrier crack on the angular displacement of car- rier posts. Validation shows good accuracy of the developed dynamic model in predicting dynamic characteristics of a planetary gear train. Fault features extracted from predictions of the model reveal the correspondence between vibration characteristic and the conditions （length and position） of a planet carrier crack clearly.
基金National Natural Science Foundation of China (Nos.11874373,12174412,12174413)Youth Innovation Promotion Association of the Chinese Academy of Sciences (No.2021241)+1 种基金Scientific Instrument Developing Project of the Chinese Academy of Sciences (No.YJKYYQ20180023)the CAS Project for Young Scientists in Basic Research (No.YSBR-091)。
