Papers by Author: Wen Yuh Jywe

Abstract: The construction of Fabry-Perot interferometer is very simple and it has been already utilized in different measurement systems. The result of displacement measurement is obviously influenced by the tilt angles of measurement mirror, if a Fabry-Perot interferometer is utilized for displacement measurement. Hence, the measuring range of current systems is rather small (less than 1 mm). The goal of this investigation is to develop a Fabry-Perot interferometer for large travelling range (till 60 mm) by aid of compensation of tilt angles with an angular sensor, piezo translators, control mechanism and self-designed software. To verify the measuring characteristic of the self-developed Fabry-Perot interferometer, some comparison measurements have been performed. A commercial laser interferometer serves as reference standard and the differences between Fabry-Perot interferometer and the commercial Laser interferometer are measured. Through experimental tests, the differences are less than 0.3 m in the full measurement range. The results show that the Fabry-Perot interferometer can meet the measuring requirement with high accuracy of sub-micrometer order and large measurement range.

Abstract: This paper presents PID tuning rules for first-order plus integrator systems. These tuning rules are derived by optimizing the integrated absolute errors of set point and load disturbance responses under robustness and bandwidth constrains. For deriving the tuning formulas, PID controllers for some normalized systems were designed. The relationship between the controller parameters, the parameters that characterize the system dynamics and the normalized gain crossover frequency are determined and the tuning formulas are then derived. Experimental results are provided to demonstrate the effectiveness of these tuning rules.

Abstract: A new optical encoder system is presented for displacement measurement by the curve fitting method. In this paper, another pondering model is based on the previous development. That is the new measurement method using a homemade periodical gray level code, which can be used to replace the traditional doublet grating. A high precision is achieved by a fitting method with one single-frequency harmonic function. The experiment result shows that the concept is feasible.

Abstract: Conventional levels can be employed to measure just one dimensional inclinations each time, and are frequently used to measure inclination, straightness and flatness. There are two disadvantages when such levels are used to measure two dimensional inclinations (such as flatness): (1) two measurement steps are needed to measure two orthogonal directions in flatness; and (2) the two directions cannot be perfectly perpendicular to each other because of setting errors. This paper describes the development of a novel optoelectronic level which employs a simple pendulum, reflection mirror, 2D PSD and laser diode. In this system, a laser light is projected onto reflection mirror 1 which is fixed on a simple pendulum, and mirror 1 reflects the light to mirror 2 which is fixed on a fixture, and mirror 2 reflects the light to the 2D PSD. Thus, the inclination measurement result can be obtained from the output of the PSD. This paper establishes a novel system and describes the complete experiment. The A-axis rotation angle from approximately -1.3 to 1.3 degrees can be measured with an accuracy of 2 arc sec, and the B-axis rotation angle from approximately -1.7 to 1.7 degrees can be measured with an accuracy of 3 arc sec.

Abstract: This study presents an analysis of surfactant added by CuO and Al2O3 nano-sized particles of different percentages. After adding suspending nanocrystalline particles into lubricant of machines, the nano-sized particles will augment the heat transfer characteristics of fluids. Some former studies showed that such liquids pose a great potential for heat transfer enhancement. By applying nanofluids to heat transfer of machine lubricant, this paper attempts to explore dominating factors of heat transfer performance from various weight concentrations of nano-sized particles, the correlation among wall temperature, heat flux, rotational Reynolds number, Nusselt number, Grashof number and rotational Grashof number of four different concentrations. The results show that nano-sized particle lubricant offer a better heat transfer performance than typical lubricants. Since random movement and diffusing effect of nano-sized particles are one crucial factor for an increased heat transfer coefficient, adding 3.5% weight concentration nano-sized particle lubricant will produce an optimum heat transfer performance among Case I~IV.