Papers by Author: Tsing Tshih Tsung

Abstract: . This study presents the dynamic calibration of pressure sensors using a developed liquid step wave generator. This approach is sufficient to display the transient response of pressure sensors in the time and frequency domains and it depends on the performance of pressure generators. In this study, the liquid step wave generator was developed via a reformed spool valve generating a liquid step wave with a short rise time that current generators have not achieved so far. A small sensing cavity, where maintains the liquid step wave, and a contact seal were adopted herein to limit the pressure transient of the fluid in the generator, such that the rise time and the bandwidth of the liquid step wave can reach 30.0 µs and 10.4 kHz. The experimental results not only display the performance of the liquid step wave generator, but also reveal the dynamic characteristics of three different test pressure sensors using the developed liquid step wave generator.

Abstract: One hydraulic pressure generator has been developed with a unique rotating valve and the waveform of generated waves is approximately square-like shape under the low rotating speed. The generated wave has advantages for research in the dynamic characteristics of hydraulic components. The unique rotating valve consists of a rotor and stator which have a number of rectangle grooves precisely milled on the peripheries of the rotor and stator as fluid channels. The rotating rotor alternately switches the fluid channels to open and close state, therefore the waveform is close to square in principle. The pressure transient on the generated wave plays a major role and influences dynamic performances of generated wave. For analyzing the performances of the generator, one sensitivity pressure transducer mounted on the outlet of the generator to measure waveform in time domain. In addition, through Fourier series expansion the spectrum of generated waves clearly indicates the harmonic components of generated waves. Results show the waveform is close to square-like under the low rotating speed in time domain. In the frequency domain, the spectrum of the generated wave demonstrates the bandwidth is abundant. Thus, the generator could be one kind of function generator to performing the calibration of the hydraulic components.

Abstract: This paper describes an innovative system to produce nanoparticles based on the theory of gas condensation in producing nanoparticles. In a vaccuum environment, the system used the energy produced by high frequency induction to vaporize a pure zinc rod inside the crucible. During the vaporization the chamber was filled with He gas, so the high-temperatured vaporized metal can undergo momentum exchange with He gas and at the same time, induce the vaporized metal to move to the cold trap. Upon reaching the wall of the cold condenser, the vaporized metal instantly condensed, forming nanoparticles. The TEM image shows that their average diameter was 30 nm, and the size was very consistent. In addition, the Zeta potential and average diameter of the ZnO nanofluid was also measured under different pH conditions to determine the stability of the ZnO nanofluid. Moreover, in order to verify the practicability of the fabricated ZnO nanoparticles, the ZnO nanofluid was inspected by UV/Vis absorption spectrum, and the results show that ZnO nanoparticles absorption ability was within a wavelength range from 350nm to 550nm.

Abstract: In this paper investigates the dynamic stability of Fe3O4 magnetorheological fluid produced by Submerged Arc Nanoparticle Synthesis System which our team has modified, that is, the dynamic stability of magnetic microparticle in Brownian motion. Through this modified system, parameters such as the exact peak current, the time of discharge and off time, and voltage can be preset. The results of the experiment show that the Fe3O4 magnetorheological fluid produced by the modified submerged arc nanoparticle synthesis system has wt 20% and vol 1% surfactants after being mixed with water. After being placed aside for one day and 15 days respectively, the average diameters of the two nanofluid measured with particle size analyzer and TEM are both 40nm. Furthermore, after analyzed through Brookhaven ZetaPlus the zeta potential of the two nanofluid both reach 40mv, which proves that the magnetic nanofluid show superior performance of suspension.

Abstract: This study developed a square-like pressure wave generator as an excitation source to test dynamic characteristics of pressure sensors. The developed generator can generate a square-like pressure wave of as high as 2 kHz and can achieve high-frequency switching by utilizing the differential principle through a series of mechanical rotations between the revolving spindle and revolving ring. The square-like pressure wave generated is input into the hydraulic system while the output voltage signals given by the pressure sensor can be analyzed by spectrum analysis to obtain dynamic characteristics of the pressure sensor

Abstract: The low-pressure control methods for an arc-submerged nanoparicle synthesis system (ASNSS) was proposed and developed for brake nanofluids. In the process, a copper bar is melted and vaporized in insulating liquid for core formation with crystallization suppressed to derive nanofluid that contains nanometer copper particles in DOT3 brake fluid. Two technical advances associated with nanoparticle synthesis were achieved. One is the novel pressure control technique developed for nanoparticle fabrication. The other is the verification that the constant low-operating pressure. Pressure operating plays important role in determining the characteristics of the prepared nanoparticles in brake fluids. From the experimental processes, pressure control of the ASNSS was identified as crucial to success of nanoparticles synthesis. To achieve the desired pressure control, a vacuum chamber was developed as a nanoparticle accumulator and low-pressure reservoir. The chamber was controlled by the proposed flow –valve feedback control system and integrated with the ASNSS. The pressure control equipment of the ASNSS was effectively developed to prepare desired copper-oxide brake nanofluids with well-controlled size.

Abstract: The purpose of this paper is to analyze and compare the dynamic characteristics of various structure pressure sensors using the Improved Pressure Square Wave Generator (IPSWG). The developed IPSWG is a signal generator that creates pressure square waves as an excitation source. The dynamic characteristics of pressure sensor in hydraulic systems can be measured and evaluated effectively due to the high excitation energy. The method is also useful for dynamic testing and characterization for a high frequency range, which cannot be performed by the traditional methods, such as the hammer kit excitation, sweeping frequency pressure wave, and random frequency wave. Result shows that piezoelectric sensors (quartz) have a largest gain margin and overshoot. The strain gauge sensor has a smaller gain margin and overshoot. The piezoelectric sensor is more suitable for measuring dynamic pressure.

Abstract: This article presents the development of an automatic on-line measurement system for characterizing a nanoparticle manufacturing process known as Arc Spray Nanoparticle Synthesis System (ASNSS). The ASNSS has been developed to generate metal nanoparticles and to explore the optimum system parameters for producing the desired nanopowders. Preliminary experimental results indicate that the size of nanoparticles, widely ranging from 10nm to 300nm, is significantly affected by the process parameters such as operating pressure, temperature, electrical current and type of dielectric liquid used. The on-line measurement system was developed to provide an effective multi-solution for characterizing the nanoparticle synthesis process and for monitoring the manufacturing quality of the ASNSS. Experiments were conducted to identify the optimum sampling period and volume of the particle suspension for accurate sampling and data acquisition. Experimental results revealed that a sampling duration of 20 minutes and a dielectric volume of 40 c.c. can achieve effective data representation while maximizing the sampling efficiency.

Abstract: This study aims to investigate the temperature effect on particle size of copper oxide nanofluid produced under optimal parameters of the Arc Spray Nanoparticle Synthesis System (ASNSS) developed in this research. The purpose is to understand the aggregation feature of copper oxide nanofluid in a higher-than-room-temperature environment and to analyze its size change and the motion behavior of suspended nanoparticles. This study employs an ambient temperature controller to maintain the environment temperature within the scope of normal fluid work temperature to obtain data on the change in suspended particles of copper oxide nanofluid under varying temperatures and through change of time. Experimental result shows that the particle size distribution of copper oxide nanofluid changes when the temperature rises due to the slight absorption and aggregation phenomena between particles, and that the change in environmental temperature can accelerate the aggregation of copper oxide nanofluid, which can affect its stability in application. However, the change in particle size distribution will gradually stabilize for a longer duration of constant temperature.