Kuo-Hsiung Tseng

Rapid and efficient synthesis of silver nanofluid using electrical discharge machining

The electrical discharge machining (EDM) system has been proven feasible as a rapid and efficient method for silver nanofluid preparation. This study prepared the silver nano-fluid via EDMand investigated the relationship between its process parameters and product characteristics. The prior study had found that the silver nano-fluid prepared by EDMcontained both silver nanoparticles and silver ions. Silver ions had revealed the cause of the high suspension of the silver nanoparticles. To examine the relationship between the stability of silver nanofluid and the process parameters, this study quantified the relationship of process parameters to the material removal rate (MRR) of silver electrode and silver ion output rate (IOR) in the fluid, in order to achieve the most effective process parameter condition. Furthermore, the stability of silver nano-fluid was analyzed by various devices, including UV-Vis spectroscopy, size-distribution, and Zeta-potential analyzer. The effects of MRR, IOR, particle size, Zeta-potential, and optical properties of silver nanofluid under different process parameters are also discussed.

Load model effects on distance relay settings

The purpose of this paper is to study load model effects on distance protective relay settings in Taipowers transmission system. Five load models have been used in order to explore the effects of load characteristics on relay settings: (1) static ZIP model, (2) dynamic motor model, (3) composite model, (4) PTI IEEE model, and (5) exponential model. The major points of this study include (1) setting of impedance values for the three distance protective relay zones and the protection against loss of synchronicity in the outermost periphery, (2) exploring the effects of load models on impedance angles at the time of distance relay tripping, (3) study whether the load model will cause a malfunction in the distance relay when the system swings due to a sudden change in the power system, (4) analyze the coordination of the blocking time of the out-of-step blocking relay during system power swings, and (5) propose how to select a better load model for accuracy in relay settings.

Preparation of Metallic Aluminum Compound Particles by Submerged Arc Discharge Method in Aqueous Media

Fine metal particles are produced by chemical methods, which add surfactants to control particle size and concentration. This study used the submerged arc discharge method (SADM) to prepare metal fluid containing nanoparticles and submicron particles in pure dielectric fluid (deionized water or alcohol). The process is fast and simple, and it does not require the addition of chemical agents. The SADM uses electrical discharge machining (EDM) equipment, and the key parameters of the production process include discharge voltage, current, and pulse discharge on-off duration. This study added a capacitive component between the electrodes and the electrode Z-axis regulation in the control parameters to render the aluminum fluid process smooth, which is the main difference of this article from the literature. The experimental results showed that SADM can produce aluminum particles from nanometer to submicron grade, and it can obtain different compounds from different dielectric fluids. The dielectric fluids used in this study were deionized water and ethanol, and aluminum hydroxide Al(OH)3 particles with suspending power and precipitated aluminum particles were obtained, respectively. The preparations of metal colloid and particles by the SADM process have the characteristics of low cost, high efficiency, high speed, and mass production. Thus, the process has high research value and developmental opportunities.

Bacteriostatic Substrate by Conductivity Method and Electric Spark Discharge Method Combined with Electrospinning for Silver Dressing

This study uses the conductivity method, Electric Spark Discharge Method, and the electrospinning technique to develop a better silver-based antibacterial agent. The preparation process is free of chemical substances and also conforms to the green energy-saving process. The silver iodide was prepared in an iodine agar medium by using the conductivity method. Multiple bacteriostasis experiments showed that the molds grew in the position with iodine of the culture medium after 6 days, as well as in the position with silver iodide after 10 days. The results prove that silver iodide has better bacteriostatic ability than povidone iodine. The nanosilver colloid was prepared in the PVA solution by using the Electric Spark Discharge Method. UV-Vis, Zetasizer, and SEM-EDX analyses proved that the PVA solution contained nanosilver colloid with good suspension stability. Finally, the electrospinning technique was used to spin the PVA solution with nanosilver colloid into the PVA nanofibrous membrane. According to UV-Vis analysis, the absorption peak of this nanofibrous membrane is about 415 nm, meaning this nanofibrous membrane contains nucleate nanosilver colloid, and is very suitable for antiseptic dressing.

Motion artifacts in CT scans: a study by computer simulation and mechanical phantom

Computed tomography (CT) is one of the most important tools in the diagnosis of thoracic tumors. However, during the scanning process, respiratory motion causes changes in the position and shape of the tumor, creating motion artifacts in the CT scan. This can lead to misdiagnosis of the size and position of the tumor, and can affect the effectiveness of treatment. This study develops a computer model of the movement of the thorax, and simulates the movement of a lung tumor caused by breathing during a CT scan. We show that adjusting the CT slice thickness is sufficient to determine the center of displacement and maximum displacement of a tumor during normal breathing. This model can be applied in the clinical diagnostic use of CT equipment. It will assist in finding the position of lung tumors from motion artifacts in CT scans. The target margin for treatment can thus be defined more accurately, so that appropriate doses of radiation can be applied to the target area, and irradiation of healthy tissue avoided.

Development and Implementation of a Micro-electric Discharge Machine: Real-Time Monitoring System of Fabrication of Nanosilver Colloid

This Study synthesized the nanosilver colloid (NSC) via arc discharge. The electric force ionizes the deionized water (DW) inter electrode gap, and the plenty of electrons and ions are attracted by opposite electricity. The electrons and ions strike surface of the electrodes, and sputter the nanosilver particles (NSP). The NSP stably suspend in the DW without surface-active agent. It is a novel and rapid preparation in the standard temperature and pressure. Although the industrial electric discharge machine (EDM) could synthesize NSC, it’s too costly and big size. The self-designing micro-EDM that can real-time monitor the processing is substitute the industrial-EDM. By the spectrophotometry, the zetasizer and the scanning electron microscope validate the properties of the NSC that synthesized by the micro-EDM. The results show that the NSC is the same as the features of nanomaterials. The energy of the discharge can be controlled, that can determine the process time. The concentration of the NSP can effectively reduce the difference between the products of the NSC. As the arcing rate (AR) and the absorption peaks are highly correlated, the concentration of the NSP can be predicted during processing. It’s a speedy and preliminary determine of the concentration.

Spark Parameter Monitoring Feedback System for Preparation of Nanosilver Colloid in EDM

This study developed a system monitoring the electric discharge machines (EDM) discharge energy and success rate to replace conventional oscilloscope observation. By using logic circuit, the signals are transmitted to the PC monitoring platform in order to display the discharge success times, discharge success rate, and electrodes consumption energy. The advantage of the proposed system is the capability to observe real-time discharges and record the experimental conditions, as well as optimize the discharge parameter settings. The experimental results suggest that, in the preparation of nanosilver colloid, the cost-performance of Ton–Toff at 10–100 µs is the optimal setting. The monitoring system also can take advantage of the discharge success rate to control the energy consumption of the electrode to obtain the standardization of products. The results suggest that, while discharge success rate, electrodes weight loss and wavelength of the absorption peak are considerably accurate, but concentration accuracy is relatively poor. The discharge success rate monitoring system is an innovative method that can help to realize electric discharge processing, optimize product quality, and it may be a powerful processing tool in the future.

A Study of Antibioactivity of Nanosilver Colloid and Silver Ion Solution

The colloidal silver solution was successfully prepared in dielectric fluid by using electrical spark discharge (ESD) without any surfactants. It does not require the toxic chemical agents in the process, which may affect the effectiveness of nanosilver colloid as an antibacterial agent. Nanocolloidal silver produced by ESD is characterized as low cost, zero environmental pollution, continuous, and rapid mass production process. In order to test the effect of antibioactivity, nanosilver dough was tested; the silver nanofluid was prepared by ESD machine, made into dough at different concentrations, and fermented for three hours in order to observe changes in the diameter of the dough. The results showed that the effect of effectiveness of nanosilver at the concentration of 100 ppm was weak, whereas the effect of 60 ppm silver ion (100 ppm AgNO3) was significant, as the dissociation rate of silver ion concentration correlates to the antibioactivity.

Optimization of Microwave-Based Heating of Cellulosic Biomass Using Taguchi Method

This study discusses the application of microwave-based heating for the pretreatment of biomass material, with Pennisetum purpureum selected for pretreatment. The Taguchi method was used to plan optimization experiments for the pretreatment parameter levels, and to measure the dynamic responses. With a low number of experiments, this study analyzed and determined a parameter combination in which Pennisetum purpureum can be rapidly heated to 190 °C. The experimental results suggested that the optimal parameter combination is: vessel capacity of 150 mL (level 2), heating power of 0.5 kW (level 1), and mass of Pennisetum purpureum of 5 g (level 1). The mass of Pennisetum purpureum is a key factor affecting system performance. An eight-order ARX model (Auto-Regressive eXogeneous) was representative of the actual system performance, and the fit was 99.13%. The results proved that microwave-based heating, with the assistance of the Taguchi method for pretreatment of the biomass material, can reduce the parameter combination variations.

Preparation of Ag/Cu/Ti Nanofluids by Spark Discharge System and Its Control Parameters Study

This study selected silver, copper, and titanium as the research objects to explore the relationship between nanofluids properties and electrical discharge machining (EDM) processes. Regarding the products, UV-visible spectroscopy (UV-Vis) was applied to measure the concentration distribution of nanofluids; zeta-size analysis is applied for measuring nanometal particles’ Zeta-Potential and the size distribution of metallic particles in the fluid. Finally, various instruments, including scanning electron microscope (SEM), were applied to observe the shape, size, and composition ratio of metal particles after processing. According to the experimental results, the control of the discharge pulse time, in addition to affecting the concentration of metallic liquid and temperature in the process, affects the size of the metal particles after the process. As the resistivity of silver and copper is very low, at about  Ω·m, if is set to between 10~50 μs, good preparation efficiency can be obtained. The resistivity of titanium is  Ω·m, which is much larger than that of silver or copper. Hence, should be set to approximately 100 μs to achieve a good discharge success rate.