International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Plasma basic ion implantation (PBII) with high negative voltage pulses has been applied to test specimens in a sterilization process as a technique suitable for three-dimensional workpieces. Pulsed high negative voltage was applied to the electrode in this process at the gas pressure of oxygen. It was reported that the PBII process reduced the numbers of active Bacillus pumilus cells using self-ignited plasma N₂ gas generated by only pulsed voltages. The number of bacteria survivors was reduced by 10^-5with a few min exposure. As the ion energy is the most important processing parameter, a simple method to estimate the oxygen ion energy calculated using distribution for oxygen in Si implanted by PBII was estimated. In this work, the Effect of Plasma Density on Residual Bacterial Number and Applied Voltage is studied.

Electron beam lithography (EBL) is a key technology for the fabrication of new generation integral circuits and devices of electronics, photonics and nano-engineering. The computer simulation of the processes of electron exposure and development of the resist profiles in EBL is important for the optimization of this expensive technology process, due to the expensive equipment used in microelectronic fabrication, the use of sophisticated materials and the long chain of sequential steps required to obtain the desired microand nano-structure. In this work investigation of the exposure and the development of Poly-methyl methacrylate resist (PMMA) with 100 nm thickness on Si substrate is presented. Different simulation techniques are implemented for the estimation of the distribution of the absorbed energy in the sample during electron beam exposure and for the development of the resist profile. Results from Monte Carlo simulation softwares CASINO, TREM, SELID are presented.

This article discusses a modelling approach for the welded seam form obtained by electron beam welding based on experimental data and types of mathematical functions. The process of electron beam welding is carried out by dividing the electron beam into two parts, resulting in the formation of two liquid baths. The samples that are welded are made of stainless steel with a change in process parameters: the distance between the two electron beam parts and the ratio of the power distribution between the two beam parts, the frequency of the deflection signal, the beam current, and the welding speed. Focusing current is of constant value. The weld cross sections shown in different process parameters are used to evaluate their shape using standard mathematical function – Gaussian functions.

Electron beam lithography (EBL) is one of the few “top-down” methods and EBL is becoming increasingly widespread in R&D and small volume production due to its flexibility and mask-less nature, very high (sub-10 nm) resolution and accuracy and in many cases EBL is the only possible alternative. In this paper, obtained experimental and simulation results for EBL nano-patterning using the high-resolution electron beam resist Hydrogen Silsesquioxane (HSQ) are presented and discussed. The influence of EBL process parameters such as exposure dose, resist thickness and development process conditions on the obtained developed images is studied. The applied simulation tool for the resists’ characteristics evaluation is suitable for a precise control of obtained image dimensions in the resist applied as a masking layer for nano-patterning. This investigation and simulation of the characteristics of the studied e-beam resist aim to improve the resolution of the nano-dimensioned electron beam lithography and results for nano-lithography applications are also presented.

Electron beam melting and refining (EBMR) is one of the modern and widely used technologies which is employed industrially for melting and metal purification. Experimental investigations, computational modeling and optimization approaches are indispensable tools in the study of this ecological technology, for the development and optimization of effective technological schemes and their application to different materials as well as for reducing the price of the pure metals produced. On the basis of experimental and theoretical studies performed, data and results of practical importance for various applications of EBMR are obtained and summarized (for Cu, Ta, Hf, Ti, Au, etc.). The obtained results allow us to formulate requirements on the process parameters and are important and useful in view of studying, controlling and optimizing the quality and purity of the new materials obtained by recycling of metal scrap by EBM.

Experimental investigation of the modification of starch by grafting acrylamide using electron beam irradiation in order to synthesize water-soluble copolymers having flocculation abilities is performed. The influence of the variation of the parameters acrylamide/starch (AMD/St) weight ratio, electron beam irradiation dose and dose rate, as well as the presence or absence of metallic silver nanoparticles is investigated. The characterization of graft copolymers was carried out by monomer conversion coefficient, residual monomer concentration, intrinsic viscosity and Huggins’ constant. Models, describing the dependencies of the quality characteristics (their means and variances) from the process parameters, are estimated by implementation of the robust engineering approach in the case of qualitative and quantitative factors. Multi-criteria optimization involving requirements for economic efficiency, assurance of low toxicity, high copolymer efficiency in flocculation process and good solubility in water is also presented.

Rapid globalization requires for students, teachers, and researchers to have good education, logical thinking, problem-solving, comparative, and research skills, excellent expressiveness, and broad scientific knowledge. This work outlines some of the newest and most important approaches and trends in the universities’ education system aiming at achieving better results. Some of the latest main projects and examples of good practices related to the application of these approaches and to the international education in Japan, Bulgaria and the United States are also introduced in the paper.