Depth of machining and dimensional accuracy are important parameters in assessing the quality of microelectrical discharge machining (EDM); therefore, enhancement of these two entities is highly essential. The optimal process parameters in microEDM are significantly influenced by the electrode material, which directly affects the machining quality. In this study, depth of machining ([Formula: see text] co-ordinate) and overcut (OVC) in microEDM with carbon-coated electrode were selected; and capacitance ([Formula: see text]), voltage ([Formula: see text]), and rotary tool (RT) were the process parameters. The experimental work was performed on a titanium alloy (Ti-6 Al-4 V) with a thin film-coated microtool electrode. The surface of the tungsten carbide microtool electrode was coated with carbon and the thickness of the coating was approximately five microns. The results show that the Taguchi–multi-objective optimization based on ratio analysis (MOORA) — analytic hierarchy process (AHP) is the best combination for performing a simple and concise calculation in the machining process; and [Formula: see text] V results in higher machining efficiency with [Formula: see text] pF and [Formula: see text] rpm. Our results show that the quality of the machined surface and machining accuracy in microEDM using coated electrode at optimal parameters are good.
In powder-mixed electrical discharge machining (PMEDM), the application of low-frequency vibrations to a workpiece is considered beneficial to the machining quality. This study evaluates the average surface roughness (Ra) of SKD61 steel workpieces subjected to low-frequency vibrations during PMEDM using a Cu electrode and titanium powder. Specifically, Taguchi’s L25 experimental design method is used to evaluate the influence of the following process parameters: current, pulse-on time, concentration, push pressure, frequency, and amplitude. The analysis of variance technique is used to determine the minimum Ra (Ra[Formula: see text]) value. The results show that Ra is most and least strongly influenced by [Formula: see text] and [Formula: see text], respectively. Further, Ra[Formula: see text] is found to be 1.03 [Formula: see text]m.
Antibiotics like rifampicin are often persistent in the environment. When entering the water, it causes antimicrobial resistance that affects the ecosystem and accumulates in the aquatic organisms and affects human health through the food chain. In this study, titanium dioxide was doped with neodymium (0.01 to 0.8%) using the sol-gel hydrothermal method. TiO2/Nd was then coated on rice husk ash to produce a modified TiO2/Nd/rice husk ash material containing 0.36% (w/w) Nd. The structural characteristics and photocatalytic properties of the materials were analyzed by X-ray diffraction, energy dispersive X-ray, transmission electron microscopy, scanning electron microscopy, forbidden zone energy, and specific surface area. The TiO2/Nd material exhibited a higher photocatalytic decomposition capacity than TiO2 and depended on the Nd content. The rifampicin removal efficiency of TiO2/Nd materials with 0.36 to 0.80% Nd contents was approximately 40% higher than that of TiO2/Nd containing 0.01 to 0.28% Nd. A new photocatalytic TiO2/Nd/rice husk ash material was developed to decompose rifampicin. The rifampicin-degrading efficiency of TiO2/Nd and TiO2/Nd/rice husk ash material reached approximately 86 and 75%, respectively, within 90 min under sunlight. Although a lower efficiency was obtained, the TiO2/Nd/rice husk ash material was selected to degrade rifampicin residue in water via the photocatalytic process (under sunlight) because of its advantages such as requirement of a small amount and easy recovery. In the rifampicin removal process, k values were found to match the zero- and first-order kinetics. In particular, for TiO2/Nd and TiO2/Nd/rice husk ash under solar irradiation, R2 values reached approximately 0.98. These results have been previously published as a preprint.
In this paper, we develop a new encryption scheme based on the ELGAMAL encryption algorithm and the degree of difficulty of the discrete logarithm problem (DLP). In public key cryptography, a secret key is often used for a long period of time, thus expelling the secret key. Moreover, devices used to calculate cryptography can also be physically attacked, leading to the secret key being exposed. This paper proposes a new encryption scheme to reduce the risk of revealing a secret key.
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