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

Table of Contents

• MACHINES

  • Changes in the mass moment of inertia of the planetary gear mechanism reduced to the axis of the sun gear depending on the ratio between the radii of the sun and planet gears

    • Sasko Milev
    • Blagoja Nestorovski
    • Darko Tasevski
    • Zoran Dimitrovski

    pg(s) 126-129

    • Abstract
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    Direct Planetary gear mechanism normally consists of a single central gear at the center, an internal (ring) gear around the outside, some number of planet gears that go in between and a planet carrier. They are used to reduce or multiply the number of revolutions. For correct selection of the torque of the driving machine, it is necessary to know the moment of inertia of the planetary gear mechanism, which directly depends on the mass moment of inertia of the planetary gear mechanism and the angular acceleration. In this paper is analyzed the impact of the ratio of the radii of the central and planet gears on the mass moment of inertia of the planetary gear mechanism reduced to the axis of the central gear at a constant diameter of the internal gear. The changes in the reduced mass moment of inertia depending on the number of planet gears was also analyzed.

  • Dynamic behavior of RC structures with post-tensioned slabs

    • Enkeleda Kokona
    • Helidon Kokona

    pg(s) 130-134

    • Abstract
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    The seismic behaviour of RC structures is one of the main factors in the design of buildings. For the best performance, a series of factors such as: the geometry in plan and height, the physical characteristics of the materials used, time of construction or the choice of the type of horizontal structure are listed. The scope of this presentation is the impact of post-tensioned slabs and dynamic response of RC structure using the response spectrum method according to EC2 & EC8, by 3D Model FEM solution (ETABS software).

• TECHNOLOGIES

  • Prototype and social implementation of handmade plastic bottle lanterns with colored lightemitting diodes, milk, and water for disaster preparedness

    • Mayumi Tanaka
    • Hiroaki Okino
    • Keiko Ishihara
    • Yuko Iwahori
    • Satoru Tada
    • Masayuki Yamauch
    • Koji Kakugawa
    • Takeshi Tanaka
    • Katia Vutova

    pg(s) 136-138

    • Abstract
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    In recent years, natural disasters have occurred almost annually in Japan, causing great damage. Power outages in disasterstricken areas have occasionally forced victims to resort to outdoor campfires or indoor candles for lighting. Prolonged bad weather during such events makes it difficult to safely secure lighting, which could have a negative influence on people’s health. To address this issue, we used white light-emitting diodes (LEDs) as the light source and fabricated handmade lanterns by filling a 500 mL plastic bottle with tap water and adding 1–2 drops of milk. In this study, an LED light source casing was constructed using a three-dimensional printer, achieving a stable light scattering effect. Red, green, blue, and yellow LEDs were used for the lantern, considering people’s preferences for colored handmade lanterns. An additional light source case was easily made from cardboard, and a bamboo light source case was also constructed.

  • Optimization of a casting technology with the tools of Magmasoft software package

    • Angel Velikov
    • Georgi Evt. Georgiev
    • Raul Turmanidze

    pg(s) 139-142

    • Abstract
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    The latest version of MAGMASOFT software package – MAGMA6.1 is used to simulate and optimize a casting formation. The alloy AlSi7Mg was used for this purpose. The casting is intended for the production of a wire connector for high voltage power transmission networks. Die casting method is used. The results obtained from the stimulation of pouring and crystallization of the casting are presented. Based on the located defects and the analysis performed, changes of the technology were made, which ultimately ensure the formation of a defect-free and soundness casting.

• MATERIALS

  • Investigation of hardness and tensile strength ratio of a polyethylene blend

    • Konstantin Chukalov

    pg(s) 143-145

    • Abstract
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    In this paper, the results of Shore D hardness and tensile strength according to ISO 10319 were investigated. The results were processed statistically by creating a trend line and regression analysis in order to study in details the existing relationship

  • Luminescent properties of sol-gel synthesized ZrO2 and Sm2O3 coatings on glass

    • Stancho Yordanov
    • Mihaela Aleksandrova
    • Vladimir Petkov
    • Shaban Usun
    • Mariana Pavlova

    pg(s) 146-149

    • Abstract
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    Thin coatings of zirconia oxide (ZrO2) and samarium oxide (Sm2O3) on glass have been prepared by using sol-gel method and dip coating technique. Materials were characterized in detail by X-ray diffraction. The luminescent properties at room temperature were also investigated. Excitation and emission spectra of ZrO2 coating consists of broad bands with maximums at 318 and 365 nm respectively.
    The photoluminescence measurements of samarium coating suggest that can be efficiently excited with 700 nm and consist of emission bands centered at 567, 603, 639 and 707 nm, consistent with characteristic Sm3+ transitions. The CIE (Commission Internationale de L’Eclairage) chromatic coordinates, color purity and color correlated temperature were determined.

  • Ensuring Clean Waterways: The Essential Role of Neutralization in Treating Technological Wastewater

    • Dragana Božić
    • Ljiljana Avramović
    • Vanja Trifunović
    • Emina Požega
    • Vesna Marjanović
    • Zoran Avramović
    • Saša Marjanović

    pg(s) 150-151

    • Abstract
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    The treatment of technological wastewater through a neutralization process is essential for adjusting the chemical properties of the water. This method aims to ensure that the wastewater meets established discharge limits, thereby protecting aquatic ecosystems and improving water quality in local waterways. Effectively managing process wastewater from large industrial facilities, such as copper rolling mills, presents a significant challenge that requires attention. In this paper, we present experimental testing of the neutralization process for technological wastewater from copper rolling mills, conducted at laboratory levels. Experimental research has shown that the neutralization process involves adding 10% Ca(OH)2 until a pH of 8.5 is achieved. The duration of the neutralization process is 30 minutes. During this time, a flocculant called Settafloc AP-17 is added at a concentration of 0.033%, specifically 6 ml per liter. This method effectively meets the water quality standards outlined in the Regulation on Limit Values of Pollutant Emissions into Water and the deadlines for compliance.

  • Smelting and structure of high-entropy alloys of the FeNiCrCuAl system

    • Ruslan Sergiienko
    • Roman Serhiiko
    • Volodymyr Shcheretskyi
    • Olexiy Yakovenko
    • Olexandra Zatsarna
    • Anatolii Verkhovliuk

    pg(s) 152-156

    • Abstract
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    This work was aimed to smelt high-entropy alloys (HEAs) based on inexpensive and common metallic elements using iron-based alloys, ligatures, commercially pure metals and study HEAs’ phase structure. High-entropy alloys of the FeNiCrCuAl system were smelted in air using induction furnace in a crucible with a rammed neutral lining made of aluminum and magnesium oxides. Elements of Fe, Ni, Cr, Cu, Al were added by way of high-alloyed cast iron or stainless-steel grade X10CrNiTi18-10 (EN 1.4541), low-carbon ferrochrome of industrial grade FeCr70C1, binary Cu-33Al ligature, tough-pitch copper and semi-finished nickel. The investigated alloys were prepared by lost foam and sand mold casting methods. A study of the microstructure showed the presence of rounded shape branches of dendrites, copper-rich interdendritic space and high-chromium carbides in the structure of samples. The phase composition of the as-cast FeNiCrCuAl alloys was represented by several phases: ordered solid solution with primitive cubic lattice of type B2, solid solutions with BCC and FCC lattices and complex carbides (FeCr)₇C₃.

  • Surface-modified polyethersulfon nanofiltration membranes – preparation, properties and biotechnological prospects

    • Darinka Christova
    • Silvia Bozhilova
    • Mariela Alexandrova
    • Maya Staneva
    • Filip Ublekov

    pg(s) 157-160

    • Abstract
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    In this study, different methods for surface modification of polyethersulfone nanofiltration membranes are explored in view of improving water-ethanol separation properties. Thin copolymer film deposition as well as surface grafting of hydrophilic monomers is applied and modified membranes are characterized by using Fourier transform infrared spectroscopy, optical microscopy, atom force microscopy, etc. Surface properties of the modified membranes revealed by contact angle measurements together with specific surface area and pore distribution are evaluated and compared to those of the base membrane. The influence of structure and composition of the modifying polymer on overall membrane properties is assessed and discussed in view of their potential biotechnological application.

  • Study on the Failure of Heat Exchanger Tubes in the Chemical Industry

    • Julieta Daniela Chelaru

    pg(s) 161-162

    • Abstract
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    In the chemical industry, heat exchangers play a critical role in maintaining process efficiency. However, these systems are prone to frequent failures, often necessitating extensive maintenance or repairs, which in turn adversely affect the overall economic performance of industrial operations. The chemical industry commonly operates in highly corrosive environments, making corrosion the predominant failure mechanism for heat exchangers. Key factors contributing to corrosion-related failures include defects in fabrication and welding, suboptimal material selection, improper water flow or chemistry management, and the presence of corrosive species in water. This study investigates the corrosion behaviour of heat exchangers under various corrosive conditions, utilizing COMSOL Multiphysics for simulation and analysis.