Machinery - Repository of the Faculty of Mechanical Engineering, University of Belgrade
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SMART, ERGONOMIC AND SUSTAINABLE MINING MACHINERY WORKPLACES: AN OVERVIEW OF THE SMARTMINER PROJECT
Get PDFDespite being the oldest, the mining industry continues to be a major source of pollution, with more people killed or injured than in all other industries. Additionally, social tension related to this sector is widespread around the world, since mining businesses continue to have a significant negative influence on land, water, air, biota, and people through direct and indirect mechanisms. The mining machinery workplaces, which are in the focus of this study have the largest environmental footprint. The dominance of technology-centered design in present research streams is most likely the explanation for the lack of advancement in the mining industry. The SmartMiner project creates shift from technology-centered design and its concept creates solutions for improving the standard of environmental quality in complex systems and suggests a paradigm change to a Human and Data-Centric Engineering. By aligning advanced operator I4.0&5.0 and society S5.0 standards, the SmartMiner project develops solutions for raising the level of environmental quality in complex interactions between physical, behavioural, and organizational processes field. Proposed paradigm can be easily transferred to other industries. The safety of mining machinery operators in their immediate surroundings and their regular alignment with value chain stakeholders are the first steps in our original idea approval process. Research moves to the operator macro-environment, which is determined by organizational contextual factors, and is encompassed by the development of intelligent, ergonomic, non-invasive, and dependable operator aid systems for regulating physical environment job stressors - noise, human vibration, lighting, temperature, air quality, workplace layout issues, etc., with high potential to solve environmental and human health issues and to influence overall performance
Reconfigurable open architecture control system with integrated digital twin for 3-axis woodworking milling machine
No full textThis study proposes a reconfigurable open architecture control system for the Computer Numerical
Control (CNC) woodworking educational machine tool called “EMCO F1 CNC”. On this machine
physical hardware reconfiguration (spindle position can be vertical and horizontal) is possible. The
idea was to develop a control system that would follow the configuration changes of the machine
tool. The educational character of the machine and its reconfigurability demand possibilities for
machining programme simulations in order to determine optimal workpiece position in the
workspace and programme verification. Those are the reasons for developing a virtual machine tool integrated with the control system as a digital twin. The study presents a novel methodology for the development of control systems, merging the concept of “virtual commissioning” with iterative errordriven processes. The objective was to develop a dynamic control system capable of promptly adjusting to kinematics changes in real time. In a wood machining experiment, a test workpiece for machine tools for both machine configurations verified the operation of the developed control system
Artificial Neural Network Model for Predicting Excavator Downtime
No full textPrevious research shows the significance of maintenance in enhancing performance levels and reducing
system costs of equipment. This paper aims to develop a quantitative model for predicting the failure rate of
excavators using artificial neural networks (ANN). As an input to the ANN, the duration times of 590
excavator downtimes measured over 198 days at the mining site in Serbia were used to obtain a classification
of failures longer than an hour based on the previous 14 days, in aim to prevent potential indirect financial
losses which could be over 15000€/hour. A Pareto analysis of the observed data was also performed and
showed the technological type of downtime as the most frequent. The results show that the ANN modeling is
suitable for mapping the non-linear relationship between excavation activities and the failure rates of
excavators. The results showed that the proposed ANN model provides an accurate estimating tool for the
early planning stage to predict failure rates of excavators. Future research avenue proposal is directed at
monitoring and forecasting the exact duration of excavator downtime in real-time
Influence of different living hinges geometries to compliant straight line mechanism trajectory
No full textClassical straight-line mechanisms are one of the most interesting, both from a theoretical and practical point of view. In many cases, those mechanisms frequently produce a nearly straight trajectory rather than one perfectly straight. In compliant form, those mechanisms can produce even better results. Compliant mechanism joints' deformability allows engineers to make further modifications. These modifications may improve the mechanism's ability to follow a straight path even further. This paper will provide an analysis of different hinge sizes, thicknesses, shapes, and overall geometrical characteristics. Their influence on the straightness of the mechanism trajectory will be analyzed and quantified
COMPARING THE DURATION OF DIFFERENT TYPES OF EXCAVATOR DOWNTIME
Get PDFIn the mining industry, excavator uptime is crucial for maintaining productivity and meeting project deadlines.
Downtime, or periods when excavators are not operational, can significantly impact project costs and efficiency.
This paper examines various types of excavator downtime, including mechanical, electrical, technological,
organisational, and meteorological, to identify patterns and potential mitigating strategies. By comparing the
duration and implications of different downtime categories, this study seeks to highlight effective strategies for
minimising non-operational periods, thereby enhancing the overall productivity and safety of excavator
operations in the industry. The descriptive statistics indicated that the data exhibited non-parametric
characteristics. The non-parametric Mann-Whitney U-test was used to compare the data. The results of the
research showed that, in most cases, there is a difference in the duration of downtimes between different
categories of downtimes. This analysis aims to contribute to the optimisation of excavator use, offering valuable
insights for industry stakeholders
Renewable Energy Equipment in Biogas Plants
No full textEquipment used in biogas plants includes a broad array of devices and
technical solutions, with significant flexibility in component combinations. Each system demands a comprehensive technical analysis to ensure optimal functionality.
Contracting a single provider offers streamlined compatibility and operational
guarantees but limits customization options. In contrast, modular construction
accelerates project timelines and reduces costs, while engaging multiple specialized
contractors increases investor involvement but also raises risks. Both approaches
carry distinct advantages, underscoring the importance of balancing operational
efficiency with investment flexibility when designing and building biogas facilities
Wind Tunnel Testing of a Small UAV Electric Propulsion System
No full textThe purpose of this work was to gather experimental data and validate numerical results of the propulsion system behaviour intended for powering the light UAV “Putnik”, designed by the Beoavia Student Association The Putnik aircraft was designed and manufactured for the ACC2024 (Air Cargo Challenge) competition. According to the competition rules, the use of a T-MOTOR AT2826 KV900 BLDC motor and 3S LiPo battery is mandatory with free choice left for the ESC and propeller. For this purpose, several commercially available propellers were selected and numerically analysed. With the data obtained, Motor-Propeller matching was performed and a few of the most suitable propellers were chosen for testing. In the testing phase, the propulsion system was tested in static conditions after which wind tunnel tests were performed at the wind tunnel facility at the Faculty of Mechanical Engineering in Belgrade.
Wind tunnel tests were done to validate the numerical results and investigate the thrust force as a function of wind speed (flight velocity). Tests were performed at the following velocities: 0, 5, 10, 12, 14, 16, and 20 m/s. Every test lasted approximately 60 seconds, with a linear variation of power between 50 and 100%, defined by a custom PWM (Pulse Width Modulation) script. For data acquisition, custom software was developed by team members. In both static and dynamic testing, the following parameters were measured and obtained: thrust force, current, voltage, RPM, pressure and temperature.
After analysing the experimental results, it was noticed that at lower velocities, the maximal thrust obtained during tests was lower than numerically predicted, however, the thrust change was more linear, resulting in a smaller loss of thrust at greater velocities. Finally, the APC 13x6.5E was chosen, as it had good thrust reserve through the whole velocity range, as well as showing great overall efficiency at the designated cruising speed
Environmental and Social Assessment of SHPP Tearce Bistrica 2 – Expertise
No full textM103 - The expertise is done for Deloitte Consulting co. The investor was EIB (European Investment Bank)
Variational Approach to Heat Conduction Modeling
Get PDFIt is known that Fourier’s heat equation, which is parabolic, implies an infinite
velocity propagation, or, in other words, that the mechanism of heat
conduction is established instantaneously under all conditions. This is unacceptable
on physical grounds in spite of the fact that Fourier’s law agrees well
with experiment. However, discrepancies are likely to occur when extremely
short distances or extremely short time intervals are considered, as they must
in some modern problems of aero-thermodynamics. Cattaneo and independently
Vernotte proved that such process can be described by Heaviside’s telegraph
equation. This paper shows that this fact can be derived using calculus of
variations, by application of the Euler-Lagrange equation. So, we proved that
the equation of heat conduction with finite velocity propagation of the thermal
disturbance can be obtained as a solution to one variational proble