In this study, the Electric Spark Discharge Method (ESDM) was employed with micro-electrical discharge machining (m-EDM) to create an electric arc that melted two electrodes in deionized water (DW) and fabricated nano-Au colloids through pulse discharges with a controlled on–off duration (TON–TOFF) and a total fabrication time of 1 min. A total of six on–off settings were tested under normal experimental conditions and without the addition of any chemical substances. Ultraviolet–visible spectroscopy (UV–Vis), Zetasizer Nano measurements, and scanning electron microscopy–energy dispersive X-ray (SEM–EDX) analyses suggested that the nano-Au colloid fabricated at 10–10 µs (10 µs on, 10 µs off) had higher concentration and suspension stability than products made at other TON–TOFF settings. The surface plasmon resonance (SPR) of the colloid was 549 nm on the first day of fabrication and stabilized at 532 nm on the third day. As the TON–TOFF period increased, the absorbance (i.e., concentration) of all nano-Au colloids decreased. Absorbance was highest at 10–10 µs. The SPR peaks stabilized at 532 nm across all TON–TOFF periods. The Zeta potential at 10–10 µs was −36.6 mV, indicating that no nano-Au agglomeration occurred and that the particles had high suspension stability.

In this study, TiO nanocolloids were successfully fabricated in deionized water without using suspending agents through using the electric spark discharge method at room temperature and under normal atmospheric pressure. This method was exceptional because it did not create nanoparticle dispersion and the produced colloids contained no derivatives. The proposed method requires only traditional electrical discharge machines (EDMs), self-made magnetic stirrers, and Ti wires (purity, 99.99%). The EDM pulse on time (T ) and pulse off time (T) were respectively set at 50 and 100 μs, 100 and 100 μs, 150 and 100 μs, and 200 and 100 μs to produce four types of TiO nanocolloids. Zetasizer analysis of the nanocolloids showed that a decrease in T increased the suspension stability, but there were no significant correlations between T and particle size. Colloids produced from the four production configurations showed a minimum particle size between 29.39 and 52.85 nm and a zeta-potential between -51.2 and -46.8 mV, confirming that the method introduced in this study can be used to produce TiO nanocolloids with excellent suspension stability. Scanning electron microscopy with energy dispersive spectroscopy also indicated that the TiO colloids did not contain elements other than Ti and oxygen.

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.

Along with the rapid development of sensing systems and wireless transmission technology, the scope of application of the IoT has substantially increased, and research and innovation that integrate artificial intelligence. This study integrated civil engineering and electrical engineering to establish a universal and modularized long-term sensing system. Aiming at positive construction in civil engineering, the campus of National Taipei University of Technology was used as the experimental site as a green campus. This paper focused on the cooling effect of the green roof and the temperature difference of the solar panel to effectively isolate the direct sunlight on the roof of the building. To achieve long-term monitoring, energy consumption must be minimized. Considering that the distance between sensor nodes in the experimental site was over dozens of feet, LoRa transmission technology was selected for data transmission. LoRa only consumes a small amount of energy during data transmission, and it can freely switch between work modes, achieving optimal power utilization efficiency. The greening-related research results indicated that the shade from solar panels on the rooftop could effectively reduce the temperature increase caused by direct sunlight on concrete surfaces. The temperature reduction effect was positively correlated with whether the solar panels provided shade. After 1 week of monitoring, we observed that having plants on the rooftop for greening negatively correlated with temperature reduction efficiency. Permeable pavement on the ground was positively correlated with temperature reduction efficiency. However, its temperature reduction efficiency was inferior to that of solar panel shading. The temperature difference between high-rise buildings and the ground was approximately 1–2 °C. At the same elevation, the temperature difference between buildings with and without greening was approximately 0.8 °C. Regarding the sensing system designed for this site, both hardware and software could be flexibly set according to the research purposes, precision requirements of the sites, and the measurement scope, thereby enabling their application in more fields.

For this study, electrical discharge machining (EDM) and the submerged arc discharge method (SADM) were used to melt a silver-copper composite metal in deionized water through concentrated arc energy in order to produce metal fluids containing nano-and submicron particles. The fabrication process did not require additional chemicals, and was simple and efficient. The critical processing parameters for EDM were the discharge voltage and current as well as the on-off duration for pulse discharge; the sample concentration could be controlled under appropriate conditions. The experimental results revealed that, through electronic system design and manufacturing (ESDM), silver-copper composite metal particles could be achieved at a nano to submicron level. In addition, the results obtained varied according to differences in the on-off duration regarding pulse discharge. In this study, when the discharging parameter (T on -T off ) was at 30 : 50, nanocomposite fluids with an optimal concentration and small particles were obtained. The application of EADM could enable the mass production of composite metal fluids or particles at low cost and high efficiency. Employing EADM for the fabrication of composite metal fluids or particles warrants research attention, and the process itself can be developed further.

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Metal nanoparticles are typically prepared by using a chemical method, and a suspension is added to control the particle size and concentration of the nanoparticles. In this study, a micro-electric discharge machine (micro-EDM) was used to melt bismuth into nanoparticles, thus yielding a colloidal solution. No chemicals were added during the manufacturing process, and pure water was used as the medium. The colloid was assessed using an electrohydraulic system, and process parameters were adjusted for optimization; additionally, the discharge pulse wave was analyzed. The proposed preparation process is simple, fast, and cost-effective; moreover, the manufacturing process allows for mass production and reduces environmental pollution. Experimental results revealed that the nano-bismuth (nano-bi) colloidal solution was successfully prepared by the micro-EDM, and absorption peaks in the UV-vis spectrum were observed at 234 and 237 nm. Moreover, to optimize the proportional–integral–derivative (PID) control parameters to be used in the micro-EDM to prepare the nano-bi colloidal solution, this study derived a mathematical model of the micro-EDM. MATLAB was used to obtain the PID parameters. The discharge success rate (74.1876%) for the nano-bi colloidal solution prepared using our method was higher than that (46.9196%) obtained for a nano-bi colloidal solution prepared using an online adaptation method.