Innovative Mechanical Engineering

SOLVINGA NON-STATIONARY HEAT CONDUCTION PROBLEMIN A WALL WITH ASYMMETRIC BOUNDARY CONDITIONSUSINGTHE LAPLACE TRANSFORM

Goran Vučković — 2024-12-06

This paper presents the application of the Laplace transform to non-stationary heat conduction in a wall with asymmetric boundary conditions. The Laplace transform, a numerical method for the inverse Laplace transform, and the Mathematica software are utilized to derive a solution to the considered problem. A3D temperature distribution over a period of 8.3 hours was examined. The temperature profile equalized gradually, and after 8.3 hours, it became nearly linear, indicating that the system reached thermal equilibrium, as anticipated during the cooling of the wall under the specified conditions. A comparison with the findings in paper [3] showed that the temperature behavior was identical.

CFD INVESTIGATION OF LAMINAR AND TURBULENT FLOW AROUND A SMOOTH SPHERE AND AN NFL BALL

Petar Miljković — 2024-12-31

This paper presents a detailed analysis of the flow around a scaled-down National Football League (NFL) ball submerged in water, with special attention given to the velocity field in the wake region behind the ball. The simulation was performed in a channel with a rectangular cross-section. Laminar and turbulent flows were developed, where the Reynolds number (Re) ranged from 1,300 to 50,000. An unstructured tetrahedral mesh with refined regions was used to accurately represent the flow characteristics around the ball, particularly in high-velocity zones. The CFX module of the ANSYS software was used to obtain numerical results and the velocity field. The reduced model of the NFL ball was made in SolidWorks. The simulation results were validated by comparing the flow around a sphere (ping-pong ball) with widely recognized experimental and numerical data from the literature. The results reveal the formation of distinct flow patterns and vortex structures in both laminar and turbulent regimes, with notable differences in the wake region as the Reynolds number increases.

THE EFFECT OF WELDING SPEED ON THE MECHANICAL PROPERTIES OF FSW JOINTS IN AA2024-T351 ALUMINIUM ALLOY

Miodrag Milčić — 2024-12-31

To achieve high-quality friction stir welded (FSW) joints with reliable mechanical performance, it is essential to select appropriate welding parameters. This study investigates the effect of welding speed on the fracture toughness and impact strength of butt joints in AA2024-T351 aluminum alloy produced by FSW. The experiments were conducted using a constant tool rotation speed of 750 rpm and varying welding speeds of 73, 116, and 150 mm/min. Fracture toughness and impact strength were evaluated in distinct zones of the FSW joint, providing insight into the correlation between welding speed and mechanical properties.

MACHINE LEARNING APPROACH FOR ENERGY CONSUMPTION ESTIMATION IN DISTRICT HEATING SYSTEMS

Ivan Ćirić — 2024-12-27

This paper explores the application of various machine learning methods for time series estimation in district heating systems. The focus is on predicting heat load using supervised machine learning techniques, such as artificial neural networks and the Random Forest algorithm. Input parameters are derived from the SCADA system, including outdoor air temperature, water temperature, and pressure in the primary and secondary circuits.The development of advanced predictive models enables a better analysis of energy consumption patterns, which is crucial for improving the efficiency of district heating systems. The paper examines different machine learning approaches to identify the models that best meet the requirements for prediction in real operating conditions.The expected contribution of this study lies in establishing a foundation for further automation and optimization of district heating systems, potentially leading to reduced operational costs and energy consumption, as well as enhancing the sustainability of energy systems.

CONSTRUCTIVE SEMIGROUPS WITH APARTNESS: A COMPREHENSIBLE SURVEY FOR EXPERTS AND NON-EXPERTS

Melanija Mitrović — 2024-11-28

Our main goal is to provide a clear, understandable picture of constructive semigroups with apartness for both (classical) algebraists and those applying algebraic knowledge. This paper will shed light on our results obtained over the last decades.