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INFLUENCE OF LUBRICANT CONTAMINATION ON BALL BEARING RATING LIFE
No full textThis paper examines the service life of deep groove ball bearings, emphasizing a systems approach to service life calculation according to ISO 281. The contamination in the lubricant can accelerate wear and fatigue on the contact surfaces of bearings, leading to shortened service life. The paper investigates the influence of lubricant contamination on the service life of bearings using empirical data and established standard formulas. The resulting diagrams analytically show how service life varies depending on bearing size and operating conditions, such as lubricant viscosity, sealing efficiency, and load levels. The study's findings offer a more accurate understanding of ball bearing service life estimation under real operating conditions.Grant number: 451-03-137/2025-03/20010
Strategic mining management in light of resource scarcity, sustainability and environmental protection challenges AND ENVIRONMENTAL PROTECTION CHALLENGES
No full textSavremeno rudarstvo nalazi se na raskršću između rastućih potreba za mineralnim sirovinama i ograničenih prirodnih resursa, uz istovremeno pojačane pritiske javnosti i regulatornih tela da se očuvaju ekosistemi. Strateško upravljanje rudarskim aktivnostima zahteva integraciju ekonomskih, ekoloških i socijalnih aspekata, kao i usaglašavanje sa principima cirkularne ekonomije. Cilj ovog rada je da se analiziraju ključni izazovi u domenu održivosti, identifikuju faktori koji uslovljavaju nedostatak mineralnih resursa i ponude strategije za dugoročno planiranje. Metodologija je zasnovana na komparativnoj analizi globalnih trendova, proceni raspoloživosti rudnih ležišta i analizi uticaja na životnu sredinu kroz indikatore kao što su emisije CO₂, potrošnja vode i degradacija zemljišta. Rezultati ukazuju na potrebu primene integrisanog upravljačkog pristupa, razvoj tehnoloških inovacija za povećanje efikasnosti eksploatacije i uspostavljanje strogih ekoloških standarda. Diskusija pokazuje da uspešna transformacija rudarskog sektora zavisi od dugoročne vizije, javnoprivatnog partnerstva i usmeravanja investicija ka istraživanju i reciklaži sekundarnih sirovina. Zaključak ističe da je samo holistički pristup, koji istovremeno tretira ekonomsku dobit i zaštitu prirodnog okruženja, u stanju da obezbedi stabilnost i prihvatljivost rudarstva u narednim decenijama.Contract number: 451-03-136/2025-03/ 20021
Numerical Analysis of a Small-Scale Wind Turbine Blade Airfoil for Low Wind Velocity at Different Angles of Attack
No full textUnfortunately, wind turbines only collect a small portion of the of green energy that the wind produces. Furthermore, due to the noise and discomfort they produce, multi-megawatt wind turbines cannot be installed in urban areas. To reduce the noise as much as possible, tiny horizontal-axis wind turbines with low tip speed ratio can be installed instead. Unfortunately, because this wind turbine operates at low Reynolds numbers, the flow around it is rather complicated. When determining the aerodynamic performance of wind turbine airfoils, the computational grid and turbulence model are crucial. Blade optimization is required to determine an appropriate turbulence model and computational grid, to more precisely compute the aerodynamic performance data of wind turbine airfoils, and to gain a deeper understanding of the nature of flow over an airfoil. The airfoil’s shape, length, angle, and other characteristics are crucial. The present study examines the analysis of a unique airfoil- S814 designed for small-scale horizontal axis wind turbines (HAWT) at varying angles of attack and fixed Reynolds numbers. A thorough analysis of the airfoil S814 has been conducted to illustrate the flow behavior over the airfoil. ANSYS/Fluent software is used to perform a computational fluid dynamics analysis of an airfoils at various angles of attack and a wind speed of 6 m/s. Plots have been created to display the distributions of pressure, turbulence, velocity on airfoil and lift-to-drag coefficient at various angles of attack.contract No. 451-03-65/2024-03/200105 from 5 February 2024
Promising tensile mechanical properties of the flax fibre reinforced vitrimer matrix composites – seeking sustainable opportunities for automotive
No full textunder the agreement number 451-03-137/2025-03/200105
AUTHOR CONTACT
Milan Jankovic, MSc
email: [email protected]
Generalized Averaged Gaussian Quadrature Rules: A Survey
No full textaccording to Contract 451-03-137/2025-03/200105 dated on February 4, 202
APPLICATION OF FINITE ELEMENT ANALYSIS (FEA) SIMULATIONS IN MEASURING ROOT SURFACE TEMPERATURE DURING CRYOTHERAPY
No full textThe aim of this study is to implement Finite Element Analysis (FEA) simulations in order to obtain data that could not be acquired through in vitro experimental setups. Several in vitro experiments conducted at room temperature have shown that cryotherapeutic effects on the root surface of tooth can be achieved using specific root canal irrigation protocols. However, clinical conditions—such as body temperature and tissue moisture—differ significantly from those in a laboratory setting, raising questions about the direct applicability of these protocols in clinical practice.
The initial plan for research involved designing an in vitro experiment that would simulate the real conditions of a tooth embedded in bone. The setup included P1000 temperature sensors attached to the root surface, with the tooth placed in a water bath maintained at body temperature (37°C) to replicate a humid physiological environment. However, the results exhibited significant anomalies, including unexpected temperature fluctuations, which were attributed to inadequate insulation of the sensors from the surrounding fluid. Despite multiple attempts, a reliable method of sensor attachment and waterproofing could not be achieved. To overcome these limitations, FEA simulations were implemented to computationally recreate the desired clinical conditions. The simulation model was validated using previously published data obtained at room temperature, which had been successfully established in earlier studies. The outcomes of the simulations aim
to determine whether cryotherapeutic effects can also be achieved under clinical conditions. Additionally, by manipulating key variables such as fluid volume, temperature, flow rate, dentin wall thickness, and irrigation time, FEA allows for the identification of optimal parameters for inducing cryogenic effects in clinical conditions.po Ugovoru 451-03-136/2025-03/ 200105 оd 04.02.2025. go
Additive Technologies in the Service of Advanced Robotics and Vice Versa
No full textFor decades, since the introduction of the first industrial robot, Unimate, achieving a harmonious balance between performance and feasible robotic design has been essential. Manufacturing limitations, material availability, and sensor and actuator systems have significantly influenced robotic system design. However, since their commercial debut in 1986, additive manufacturing (AM) technologies have been revolutionizing how once-unimaginable ideas are designed, presented, and ultimately produced. This paper explores the achievements in additive manufacturing with a special focus on its application in advanced robotics. A detailed classification of existing additive technologies is presented, along with a comprehensive review of their advantages in specific robotic applications. The growing role of additive technologies in expanding robotics across industries is also discussed. Furthermore, the increasing presence of advanced robotics in households, alongside AM, is largely driven by the exponential advancement of artificial intelligence (AI). AI contributes not only to the development of control models but also to the structural design of robotic systems. As a result, robotics itself plays a crucial role in the ongoing evolution of additive technologies, a key focus of this paper. One critical aspect explored is the development of models for active vibration damping, addressing vibrations as an undesirable phenomenon in production processes. Additionally, the integration of additive technologies with robotics enhances sustainability by reducing material waste, improving energy efficiency, and enabling the use of eco-friendly materials. These innovations are already reshaping industries such as aerospace, medical robotics, and construction, where additive manufacturing enables the creation of lightweight, customized, and highly functional robotic components. Future advancements in hybrid manufacturing, multi-material printing, and AI-driven process optimization will further enhance the synergy between additive technologies and robotics, paving the way for more autonomous, efficient, and adaptable robotic systems
STRUCTURAL MODIFICATION OF THE CARGO HOLD DOUBLE BOTTOM FOR A MULTI-PURPOSE VESSEL
No full textIncreasingly, modern maritime vessels must demonstrate sructural flexibility to accommodate the growing
need for transporting various cargo types in response to evolving industry demands. As a result, regulatory
bodies, and their respective rules, regulations and standards, require that novel structural solutions are to be
verified through advanced structural assessments, including finite element analysis (FEA). Therefore, this
study focuses on FEA-based structural assessment and optimization of the double bottom and underdeck
reinforcement structure in the two cargo holds of a multi-purpose vessel originally designed for bulk cargo.
However, the vessel now also needs to carry standard 20-foot high cube containers, imposing a significantly
different loading scenario. While bulk cargo results in nearly uniform load distribution, containerized cargo
introduces concentrated point loads. The analysis accounted for container weights, gravity, and accelerations
due to ship motion. Von Mises stress criteria were used to evaluate the structural response, according to the
rules and regulations of two major regulatory bodies: Lloyd’s Register and International Association of
Classification Societies. The results indicated that the original structure could not withstand the new loading
demands according to the regulatory standards. Consequently, structural modifications were proposed and
implemented. The study highlights that even multi-purpose vessels, which are assumed to be suitable for
various cargo types by design, require structural modifications to safely accommodate containerized cargo.
The presented solution demonstrates how targeted reinforcements can ensure compliance with modern
classification society rules while enabling operational flexibility.Project no. 451-03-137/2025-03/200105 from 4 February 202
MOTION ANALYSIS OF A VIBRATORY CONVEYOR’S TROUGH DURING ITS OPERATION
No full textThis study investigates the dynamic behavior of a trough of a vibratory conveyor. The main focus is on modeling the motion of the trough, analyzing the forces acting on the system, and assessing the spring stiffness and deflections under operational conditions. Using theoretical modeling based on the theory of elasticity and rigid body mechanics mechanics, the dynamics of the system are described, and the differential equations of motion for a single-degree-of-freedom oscillator are derived. A finite element analysis inside Solidworks Simulation package is performed to observe the motion of the vibratory trough. Orthogonal displacements of the centre of mass of the vibratory trough were observed. Simulation results are provided and discussed accordingly at the end of this paper. The findings suggest that the axial displacement of the trough is couple orders of magnitude smaller than its transversal displacement, allowing for a simplification in further modeling. This study provides valuable insights into the design and operation of electromagnetic vibratory conveyors, contributing to the optimization of spring stiffness and system stability for industrial applications.451-03-137/2025-03/200105 from 04.02.2025;
451-03-136/2025-03/200034 from 04.02.2025
“I mean, what are you talking about? You have the morals of an alley cat” – the negative evaluations of the political opponent in the 2024 US presidential debates
No full textThe paper focuses on the rhetoric of the two US presidential debates held in 2024 between the Republican and Democrat presidential nominees, the first between Joseph Biden and Donald Trump, and the second one between Kamala Harris and Donald Trump. We investigate the strategies of discrediting the political opponent, such as insults, pronoun-based oppositions, repetitions and three-part lists, and metaphors. It is shown that both the Republican and Democrat nominees abundantly used these devices and relied on similar argumentative strategies in the debates, which may have had an evaluative and persuasive function and deepened the political polarization. This has contributed to the impression of the predominantly hostile and polarizing rhetoric employed in the 2024 debates.br. 451-03-137/2025-03/20010