Browsing by Author "Hou, Y. J."

Now showing 1 - 2 of 2

Lasing characteristics at different band edges in GaN photonic crystal surface emitting lasers
(2010-02-15)
Chen, S. W.
;
Lu, T. C.
;
Hou, Y. J.
;
Liu, T. C.
;
Kuo, H. C.
We have investigated the lasing characteristics of GaN-based two-dimensional photonic crystal surface emitting lasers (PCSELs) with different PC lattice constants by using angled resolved spectroscopy. Due to the Bragg diffraction theory, normalized frequency of lasing wavelength of PCSELs can be exactly matched with three distinct band-edge frequencies (Gamma 1, K2, and M3) in the photonic band diagram. The three band-edge frequencies (Gamma 1, K2, and M3) have different emission angles corresponding to the normal direction of the sample (0 degrees, 29 degrees, and 59.5 degrees).
Modelling and Control of Quad Hybrid Engine Levitating Platform
(2020-01-01)
Hou, Y. J.
;
Chen, T. L.
;
機械工程學系
;
Department of Mechanical Engineering
This research aims to develop trajectory controls for a levitation platform which is powered by rocket fuel. This control task is to regulate the platform for 3D trajectory followings and suspension in the air, which is different from that of the most rocket systems. To cope with the challenges of slow thrust response and coupled vehicle dynamics, we proposed a control system that consists of 4 independent loops for the height, yaw angle, x-position, y-positions, respectively. The developed controllers include 4 PID compensators for the flow rate throttling system, and four double phase lead and two lead-lag compensators for the vehicle dynamics. According to the simulation results, the levitation platform can follow a designated trajectory well when there exist external torques disturbance. (both 1 N-m step inputs and 0.1 N-m Gaussian distributed input) and 2% thrust force oscillations.