Факультет електроніки та інформаційних технологій (ЕлІТ)
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Item Control of Structural and Magnetic Properties of Polycrystalline Co2FeGe Films via Deposition and Annealing Temperatures(MDPI, 2021) Vovk, A.; Bunyaev, S.A.; Štrichovanec, P.; Vovk, N.R.; Постольний, Богдан Олександрович; Postolnyi, Bohdan Oleksandrovych; Apolinario, A.; Pardo, J.Á.; Algarabel, P. A.; Kakazei, G.N.; Araujo, J.P.Thin polycrystalline Co2FeGe films with composition close to stoichiometry have been fabricated using magnetron co-sputtering technique. Effects of substrate temperature (TS) and postdeposition annealing (Ta) on structure, static and dynamic magnetic properties were systematically studied. It is shown that elevated TS (Ta) promote formation of ordered L21 crystal structure. Variation of TS (Ta) allow modification of magnetic properties in a broad range. Saturation magnetization ~920 emu/cm3 and low magnetization damping parameter ~ 0.004 were achieved for TS = 573 K. This in combination with soft ferromagnetic properties (coercivity below 6 Oe) makes the films attractive candidates for spin-transfer torque and magnonic devices.Item Building of a digital model of aluminum electrolysis modes(Journal of Physics: Conference Series, 2021) Vereschagina, E.A.; Zolkin, A.L.; Лавров, Євгеній Анатолійович; Lavrov, Yevhenii Anatoliiovych; Fakhertdinova, D.I.; Dragulenko, V.V.The article discusses the issues of constructing a digital model of aluminum electrolysis modes. This model allows to achieve the specified criteria of the production process on the basis of scientific processing of historical data accumulated during the industrial production of aluminum at factories using a mathematical apparatus as well as to obtain recommendations on the values of control parameters. The study is aimed at achieving the business goals of the company's management in particular on increasing of the profits by improving the quality and quantity of products with reduced production costs.Item Analysis of information security issues in corporate computer networks(IOP Conference Series: Materials Science and Engineering, 2021) Лавров, Євгеній Анатолійович; Lavrov, Yevhenii Anatoliiovych; Zolkin, A.L.; Aygumov, T.G.; Chistyakov, M.S.; Akhmetov, I.V.This article discusses the main problems associated with information security in corporate networks and ensuring the reliable operation of information systems and the services they provide. Information security is understood as the security of information resources and information systems, as well as the supporting infrastructure from accidental or deliberate influences of a natural or artificial nature, fraught with harm to the owners or users of information resources. Currently, there are major changes in information security issues. They relate to the methods of work of attackers, the conditions of crimes commited in the computer sphere, as well as the consequences of illegal activities.Item Adhesion and friction in hard and soft contacts: theory and experiment(Tsinghua University Press, 2021) Popov, V.L.; Li, Q.; Ляшенко, Яків Олександрович; Liashenko, Yakiv Oleksandrovych; Pohrt, R.This paper is devoted to an analytical, numerical, and experimental analysis of adhesive contacts subjected to tangential motion. In particular, it addresses the phenomenon of instable, jerky movement of the boundary of the adhesive contact zone and its dependence on the surface roughness. We argue that the "adhesion instabilities" with instable movements of the contact boundary cause energy dissipation similarly to the elastic instabilities mechanism. This leads to different effective works of adhesion when the contact area expands and contracts. This effect is interpreted in terms of “friction” to the movement of the contact boundary. We consider two main contributions to friction: (a) boundary line contribution and (b) area contribution. In normal and rolling contacts, the only contribution is due to the boundary friction, while in sliding both contributions may be present. The boundary contribution prevails in very small, smooth, and hard contacts (as e.g., diamond-like-carbon (DLC) coatings), while the area contribution is prevailing in large soft contacts. Simulations suggest that the friction due to adhesion instabilities is governed by "Johnson parameter". Experiments suggest that for soft bodies like rubber, the stresses in the contact area can be characterized by a constant critical value. Experiments were carried out using a setup allowing for observing the contact area with a camera placed under a soft transparent rubber layer. Soft contacts show a great variety of instabilities when sliding with low velocity – depending on the indentation depth and the shape of the contacting bodies. These instabilities can be classified as "microscopic" caused by the roughness or chemical inhomogeneity of the surfaces and "macroscopic" which appear also in smooth contacts. The latter may be related to interface waves which are observed in large contacts or at small indentation depths. Numerical simulations were performed using the Boundary Element Method (BEM).Item An experimental study on third-body particle transport in sliding contact(University of Nis, 2021) Li, Q.; Ляшенко, Яків Олександрович; Liashenko, Yakiv Oleksandrovych; Starcevic, J.An experiment is designed to study the third-body particle transport in a rough contact. To study the influence of particles in a pure form, it is assured that the first bodies have no contact and the sliding is very slow, so that the process can be considered as quasistatic. An example of sliding contact of a 3D printed “rough body” on small spheres artificially located on a rubber layer is presented. The trajectory of particles during the sliding is captured for studying their movement and the correlation to the fluctuation of normal and tangential force.Item Crystal Structure, Phase State, and Magnetoresistive Properties of Nanostructured Thin-Film Systems Based on Permalloy and Noble Metals(G. V. Kurdyumov Institute for Metal Physics of the N.A.S. of Ukraine, 2022) Пазуха, Ірина Михайлівна; Pazukha, Iryna Mykhailivna; Шкурдода, Юрій Олексійович; Shkurdoda, Yurii OleksiiovychWe review and analyse the literature data on the experimental results dealing with the crystal structure, phase state, and magnetoresistive properties of nanostructured thin-film systems based on NixFe1–x permalloy and noble metals prepared by the methods of co-evaporation and layer-by-layer condensation. As shown, regardless of preparation methods, the phase state of systems stays as two-phase one. Upon high-temperature annealing, the formation of solid solutions is possible. As shown, in the case of applying of layer-by-layer condensation method, the value of the magnetoresistive effect depends on the thickness of the magnetic and nonmagnetic layers. In the case of applying the co-evaporation method, the determining parameters are the concentrations of the components and the total thickness of the system. The annealing-temperature effect on magnetoresistive properties of nanostructured thin-film systems based on permalloy and noble metals is analysed.Item Effect of Ru Interlayer thickness on Electrophysical Properties of Co/Ru/Co three-layer film systems(Vasyl Stefanyk Precarpathian National University, 2022) Логвинов, Андрій Миколайович; Lohvynov, Andrii Mykolaiovych; Чешко, Ірина Володимирівна; Cheshko, Iryna Volodymyrivna; Пазуха, Ірина Михайлівна; Pazukha, Iryna Mykhailivna; Tyschenko, K.V.; Пилипенко, Олександр Валерійович; Pylypenko, Oleksandr Valeriiovych; Zahorulko, A.Yu.У даній роботі були проведені дослідження структурно-фазового стану та електрофізичних властивостей тришарових плівкових систем Co/Ru/Co/Sub при зміні товщини шару Ru, dRu = 5-20 нм. Було показано, що як у свіжо сконденсованому стані, так і після відпалювання до 800 К, фазовий стан системи відповідає ГЩП-Co + ГЩП-Ru. Були отримані залежності питомого опору та температурного коефіцієнту опору як функції dRu. Показано, що зміна величини питомого опору на першому циклі термообробки стає тим більш сильною, чим більше товщина шару Ru. Величина температурного коефіцієнту опору має порядок 104 та збільшується з 5,05104 до 6,42104 K1 при зміні товщини dRu в діапазоні 0-20 нм.Item Phase transformations during the doping of zinc chloride and silver nitrate into calcium phosphates(Karagandy University of the name of academician E.A. Buketov, 2022) Sagidugumar, A.N.; Turlybekuly, A.; Dogadkin, D.; Погребняк, Олександр Дмитрович; Pohrebniak, Oleksandr Dmytrovych; Kantay, N.; Sadibekov, A.This article shows the results of a study on a biocomposite material based on calcium phosphate doped with ZnCl and AgNO3. Calcium phosphates are mainly used in dentistry and orthopedics due to their excellent bi-ocompatibility, osteoconductive properties and similarity to the inorganic components of human bone. The main objective of the study is to investigate the morphology, elemental and phase composition, and physico-chemical properties of the obtained material. The test material is obtained in the form of a suspension and subjected to ultrasonic treatment. The microstructure and phase composition of the obtained biocomposites are studied by SEM, XRD, FTIR methods. It is possible to obtain dicalcium phosphate dihydrate (DCPD) by the presented methods, and the results demonstrate a partial replacement of calcium atoms by zinc atoms. X-ray phase analysis shows that Ca(HPO4) (H2O)2 phases as well as CaZn2 (PO4)2(H2O)2 and AgCl phases were formed during the reaction. Fourier transform infrared spectroscopy revealed that the obtained samples con-tain the groups HPO42 and PO43, with the group PO42 replacing the group CO32. The biocomposite materials could be of great interest in the biomedical field, including the development of coatings that prevent or delay the development of bacterial biofilm.Item Effect of Bilayer Thickness and Bias Potential on the Structure and Properties of (TiZr/Nb)N Multilayer Coatings as a Result(MDPI, 2022) Rakhadilov, B.; Погребняк, Олександр Дмитрович; Pohrebniak, Oleksandr Dmytrovych; Sagdoldina, Z.; Buitkenov, D.; Beresnev, V.; Mukhamedova, A.This work is devoted to the study of the formation of nanostructured multilayer coatings (TiZr/Nb)N on the surface of an AISI 321 steel substrate depending on the deposition parameters of the Arc-PVD method. The results of the X-ray diffraction analysis showed the formation of solid solution (TiNb)N and ZrN in the multilayer coatings with an FCC structure, "-NbN with a hexagonal structure, as well as with a small volume fraction of the "-Ti2N and -Nb2N phase. On the basis of phase composition data, it is possible to assume that an increase in the number of bilayers leads to a decrease in the nitrogen concentration in the bilayers and, consequently, to a decrease in the volume fraction of "-NbN and -Nb2N nitrides. In all investigated systems obtained at 100 V and 200 V bias potentials, "-NbN is the main phase. The study of the element distribution over the thickness of the (TiZr/Nb)N coating confirms the results of the X-ray diffraction analysis. The use of the structure model in the form of alternating layers allows for significantly improving the adhesion characteristics of the protective coating, as well as ensuring their high hardness. Based on the experimental results, it is possible to analyze changes in the mechanical and tribological properties of multilayer coatings depending on the number of applied bilayers. The results of the study of the elastic modulus and hardness of multilayer coatings (TiZrNb)N with different numbers of bilayers showed that a large number of bilayers (small thickness of each individual layer) shows the lowest value of hardness. It is assumed that as the bilayer thickness decreases, the coating characteristics are closer to the monolayer alloy than to the multilayer structure.Item Rotors of Vertical-Axial Wind Turbines Assembled in Bearings and Aerodynamic Characteristics of a Blade with Unclosed Wing Profile(Sciendo, 2022) Panda, A.; Rozhkova, L.; Кузнєцов, Едуард Геннадійович; Kuznietsov, Eduard Hennadiiovych; Нагорний, Володимир В`ячеславович; Nahornyi, Volodymyr ViacheslavovychIn world practice, traditional blades used in high-speed wind turbines, both horizontal-axial and vertical-axial, have a wing-shaped profile. However, for horizontal-axial wind turbines, blades with such a profile have a fairly narrow range of operating values of the angle of attack of the incoming air flow and a low value of the moment of pulling from place. As for vertical-axial wind turbines, the self-starting of the rotor with wing blades is completely absent and additional devices are needed to start the rotor into operation. In order to ensure the self-starting of the rotor and the operation of the wind turbine at high and low wind speeds, a new shape of the blade profile was developed, called non-closed wing profile. The concept of the development is that the blade should have a configuration in which the pulling force is involved at the beginning of the movement, and then, with the establishing of the movement, a lifting force would arise, which acquires a prevailing character in the operating mode. The article presents the results of experimental studies of the aerodynamic characteristics of the developed non-closed wing blades. One of the results obtained is to determine the effect of the thickness of the blade profile on the range of values of subcritical angles of attack of the incoming air flow and the differences between the nature and range of changes in the coefficients of lifting force and pulling force in a traditional wing blade and a blade with a non-closed wing profile. Studies of the rotor model of a vertical-axial wind turbine with non-closed wing blades have confirmed the presence of its self-starting and operability even at low wind speeds.