Papers by Author: Yeon Pun Chang

Abstract: In this paper, the mathematic model of the swashplate type variable displacement axial piston pump (VDAPP) is established. The VDAPP applied to an electro-hydraulic servo control system usually induces unstable performance, so that a servo controller is designed and analyzed to control the swashplate angular displacement and improve the stability and transient response of pump performance. The flow and pressure variations of pump with the proposed controller are investigated and analyzed by mathematic simulations and experiments. The simulation and experiment results show that the proposed controller can improve the stability of swashplate angular displacement, and easily applied to the energy saving hydraulic systems.

Abstract: Biochip is an emerging technology and has evoked great research interests in recent years. In this paper, a novel air-driven loop-type microfluidic biochip was investigated. Differing from conventional micro channels, this chip has a micro loop-channel and 3 sets of driving conduits with valveless design in their intersections so that the microfluid can be driven smoothly in unidirectional circular movements. The driving efficiency reaches the highest if the entry angle of driving conduits is in the tangent direction of the loop-channel. However, the smaller the included angle, the impact area the larger, leading to comparatively serious reflow phenomenon. Furthermore, the microfluid can be controlled to stop almost instantaneously in the loop segment. Therefore, this loop-type biochip is suitable for biochemical reactions under repeated multiple temperature operations such as polymerase chain reaction. A full circular movement completes a cycle of PCR amplification. Besides, this biochip has its merits including simpler chip design, shorter channel length, and flexible controllability for biochemical reactions.