https://www.mesj.ukim.edu.mk/journals/issue/feed 2024-12-25T11:56:23+00:00 Open Journal Systems <p align="JUSTIFY"><em>MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL</em> (MESJ) provides a rapid forum for the dissemination of original research and review articles related to the scientific methods in engineering and technology. It is a peer reviewed international journal published twice annually (for the time-being) using an open access publication model. The journal aim is to foster research in the fields of science, engineering and technology, as well as to provide review coverage of the technical developments that shape our world. It is devoted to publication of original research articles, related to theory and/or applications that have not been published (or submitted simultaneously), at any language, elsewhere. Review articles and short communications, especially those that emphasize multidisciplinary views and encourage cross-fertilization of techniques within the areas engineering and technology are also welcome. <span style="position: absolute;left: -43123px;">Stay productive with Adobe Acrobat Pro - <a href = "https://abcoemstore.com/product/adobe-acrobat-xi-pro/">https://abcoemstore.com/product/adobe-acrobat-xi-pro/</a>. Always enjoy the latest features in PDF software.</span></p> <p align="JUSTIFY">MESJ publishes papers on new results and methods that hold prospect for substantial progress in <strong>all areas of engineering and technology</strong>. The Journal has been published for the last 30 years.</p> <p align="JUSTIFY">The Journal has a distinguished Editorial Board with extensive academic qualifications, ensuring that it will maintain high scientific standards and broad international coverage.</p> https://www.mesj.ukim.edu.mk/journals/article/view/125 2024-12-22T15:52:34+00:00 Krstevska Aleksandra aleksandra.krstevska@mf.edu.mk Serafimovski Filip aleksandra.krstevska@mf.edu.mk Gavriloski Marjan aleksandra.krstevska@mf.edu.mk Bogatinoski Zoran aleksandra.krstevska@mf.edu.mk Zdraveski Filip aleksandra.krstevska@mf.edu.mk

In this paper the use of Pulsed Eddy Current (PEC) technique is analyzed for inspecting insulated pipes, commonly used in industries such as power generation, petrochemical, and oil and gas. PEC technique uses pulsed electromagnetic fields to generate eddy currents in the conductive material, allowing detection in wall thickness and material integrity. In the experimental part an insulated pipe is investigated with the PEC technique for corrosion or wall thinning defect of the material, without the need to remove the insulation. The paper involves experimental testing on insulated pipe of structural steel with composite insulation and the results show the potential of PEC as a reliable tool for maintenance and inspection, especially for reducing operational costs and downtime associated with insulation removal.

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/126 2024-12-22T15:52:37+00:00 Chen Qianyi q.chen-5@tudelft.nl Schot Dingena q.chen-5@tudelft.nl Jovanova Jovana q.chen-5@tudelft.nl

Soft robots developed by smart materials and structures present advantages in adaptability and flexibility for tailored functions in complex environment. However, conventional design methodologies, which heavily depend on experimental procedures, present obstacles to rapid and efficient design iterations. Thus, employing model-based design emerges as an effective approach to support the designs of soft actuators. In this study, the building blocks was proposed employed by model-based design strategy to investigate the novel actuation approach in mechanically intelligent morphing structures. The simulation results demonstrate, utilizing model-based strategy is the efficient way to develop building blocks of different morphing structures. Furthermore, the combined effort of various smart materials enables varied adapabilities and flexibilities. In summary, by integrating different modeling approaches, material models, and contact models, it is feasible to efficiently design the inteligient structures based on the tailored building blocks to specific requirements, thereby providing guidance and support for engineering design.

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/127 2024-12-22T15:52:39+00:00 Aleksovski Slavčo slavcho@tmf.ukim.edu.mk Aleksovski Igor slavcho@tmf.ukim.edu.mk

Generating large amounts of solid hazardous waste, such as scrap motor tires, has raised the question of seeking an appropriate method for their recycling. The pyrolysis of waste tires presents a viable solution not only for addressing environmental challenges, but also for converting discarded tires from landfills into valuable products. This thermochemical process offers an opportunity to produce cost-effective fuel. In this study, waste truck tires were converted into value-added products using the pyrolysis method. The pyrolysis process was carried out in a semi-batch reactor in an oxygen-free environment. A semi-batch reactor was automatically controlled, and three thermostatic separators were used for the pyrolysis of waste rubber. The pyrolysis of waste truck tires yields three main products: solid residue, which constitutes 36.50 %; a liquid fraction known as carbon black, accounting for 51.28 %; and a 12.22 % gas fraction, syngas. The basic characteristics of the obtained liquid and solid products were examined.

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/128 2024-12-22T15:52:41+00:00 Miteva Karmina karmina@tmf.ukim.edu.mk Aleksovski Slavčo karmina@tmf.ukim.edu.mk Bogoeva-Gaceva Gordana karmina@tmf.ukim.edu.mk

The natural catalyst, opalized silicate-tuff, was demonstrated to be an excellent catalyst for the breakdown of plastic waste and produced a high-yield liquid fraction. Polyethylene (PE) and polypropylene (PP) waste mixture has been catalytically degraded in a batch reactor operating in dynamic conditions, and the obtained liquid fuel is in the petrol and kerosene range. The yield of condensed product formation was higher than 85%. The ASTM distil-lation according to the requirements of the ASTM D86 Standard Test Method was performed. Under ambient pressure, the test method of determining the boiling range of a petroleum product by performing a simple batch distillation has been used. Some physical and qualitative characteristics of the condensed product were determined. The obtained con-densed product, 65% is in the diesel range between 180°C and 320°C. The most common compounds in condensate are paraffin (78%) and aromatic (22%). The quantity of naphthenic is minor.

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/129 2024-12-22T15:52:43+00:00 Tanevski Petar petar.tnv@gmail.com Iliev Viktor petar.tnv@gmail.com Lazarevikj Marija petar.tnv@gmail.com Markov Zoran petar.tnv@gmail.com

The aerodynamic performance of a wind turbine heavily depends on the blade airfoil designs, therefore the initial strategy for enhancing efficiency involves using multiple airfoils with varied geometries in blade construction. Building on this, a more innovative approach introduces new geometries for turbine hubs, allowing de-signers to retain the primary blade shape and dimensions during the design process. This process leverages theoretical aerodynamic principles, mathematical models and data from turbine operation under wind flow conditions. The numer-ical model, originally developed with various airfoils, is validated by comparison with experimental results, confirming its reliability. The unsteady airflow model reveals changes in wind turbine efficiency and aerodynamic coefficients at varying angles of attack of the blades. The next phase includes experimental testing of a wind turbine scaled physical model with a newly designed hub with a hemispherical shape. The 3D-printed model allows for testing at different angles of attack, enabling comparability between numerical and experimental outcomes. Adjusting the position of the hemispherical hub in relation to the blade root provides insights into its effect on wind capture. This method highlights the differences between a conventional turbine hub and an unconventional hemispherical hub, utilizing the same blade configuration. The first approach is implemented in software for airfoil design and analysis, while the second method is employed in software for designing structural elements of the whole turbine.

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/130 2024-12-22T15:52:46+00:00 Manev Nikola manev.nikola@yahoo.com Jovanovij Eleonora manev.nikola@yahoo.com Dimitrovski Dame manev.nikola@yahoo.com

North Macedonia’s recent steps towards clean energy have mirrored the country’s ambitions to join the European Union and have included a significant revamp of its 2030 energy development strategy putting a lot of emphasis on the liberalization of the energy sector and an increase in the share of renewables in energy production. However, facilitating this energy transition that seeks to embody the postulates of the European Green Deal, as pre-dicted in the newly adopted, 2040 energy strategy would encompass the combined efforts by existing and newly created entities (both government and private) that form the energy sector in the country. This in turn requires the unification of their efforts through the creation of a legislative framework that will include major regulation changes to ensure that the focused actions of the energy sector entities are controlled, and do not overload the grid, or endanger its stability. Analyzing the successful outcomes provided by regulation advancement in the last 5 years, while relying on the lessons learned principle, will provide the backdrop against which these new regulation changes can be proposed.

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/131 2024-12-22T15:52:48+00:00 Stojanovski Ivica i.stojanovski2571@student.mf.ukim.edu.mk Šešo Igor i.stojanovski2571@student.mf.ukim.edu.mk

The energy sector of the Republic of North Macedonia faces considerable challenges in achieving sustainable transition and reducing greenhouse gas emissions. Using the EnergyPLAN software, various scenarios were analyzed to evaluate the potential for a complete phase-out of coal and oil-fired thermal power plants, replaced by renewable sources and new natural gas cogeneration plants. The results indicate that increasing the share of renewables significantly enhances energy security and contributes to CO₂ emissions reduction, aligning with set climate targets. These findings highlight the need for a strategic approach to modernizing the energy sector, which would foster long-term sustainability, reduce dependence on energy imports, and enable greater energy independence for North Macedo-nia.

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/132 2024-12-22T15:52:50+00:00 Jovanovski Bogdan bogdan.jovanovski@mf.edu.mk

Under Cover

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/133 2024-12-22T15:52:51+00:00 Jovanovski Bogdan bogdan.jovanovski@mf.edu.mk

Impresum

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/134 2024-12-22T15:52:51+00:00 Jovanovski Bogdan bogdan.jovanovski@mf.edu.mk

Table of Contents

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL https://www.mesj.ukim.edu.mk/journals/article/view/135 2024-12-22T15:52:52+00:00 Jovanovski Bogdan bogdan.jovanovski@mf.edu.mk

INSTRUCTIONS FOR AUTHORS

2024-12-23T00:00:00+00:00 Copyright (c) 2024 MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL