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TOWARDS SMART ENGINEERING PRODUCTS
No full textThe evolution of traditional engineering products is moving towards the development of smart products, which are characterized by intelligence, networking and adaptability to the user. Using the elements of Industry 4.0, such as artificial intelligence (AI), Internet of Things (IoT), digital twins (DT) and data analytics (BDA), their design, manufacturing and life cycle management are carried out on a new basis. That is why smart engineering products are characterized by self-monitoring, autonomous decision-making and optimization of their work in real time. All this leads to greater satisfaction of their users, due to improved efficiency, reliability and a better user experience. Also, smart products include issues of cyber security, data privacy, interoperability and sustainability, which must be considered in order to fully realize the potential of smart engineering solutions in them. This paper provides an analysis and synthesis of smart engineering products (SEP) from the aspect of their development, characteristics, application examples and future research in this area
INVESTIGATION OF TRIBOLOGICAL BEHAVIOUR OF PA12 SLIDING BEARINGS PRODUCED BY SELECTIVE LASER SINTERING
No full textThis research examines dry sliding of journal bearings made of Polyamide 12 (PA12) using additive technologies, addressing the gap in knowledge related to tribological behaviour in real conditions. In contrast to traditional tribological tests on flat surfaces, in this paper, full-scale journal bearings are tested under radial load. Three different pressure-velocity (PV) regimes were used to determine their effect on the coefficient of friction (COF), contact temperature, and surface morphology change. The results show that after a period of running-in, all tested samples reached a steady state with friction coefficients around 0.1 with insignificant oscillations, which indicates a stable and repeatable friction behaviour. Contact temperatures vary with operating conditions, where they reach their maximum at the most loaded regime, around 90 degrees, but it is still below the PA12 Vicat softening temperature (175°C), which indicates thermal stability. Scanning electron microscopy (SEM) analysis of the surface before and after testing confirms microstructural changes at the contact zone, showing a transition from a particulate to a smoother structure. The intermediate mode used in the test shows an optimal balance between frictional performance and thermal stability. The obtained results demonstrate that SLS-printed PA12 bearings can be applied in conditions without external lubrication, thereby enabling maintenance-free systems with operational parameters suitable for use. This work provides significant insight into industrial applicability and provides a basis for future tests that will deal with long-term tests and comparative evaluation with bearings produced via other additive manufacturing techniques
Overview and Analysis of Electric Energy Consumption Indicators in Wastewater Treatment Plants
No full textWastewater must be treated before discharge into the recipient to such an extent that it meets standards and regulations on wastewater quality, so as not to damage the environment. Depending on the quality of the influent, different technological procedures are applied, which are more or less energy intensive. Also, with the tightening of the conditions related to the quality of the effluent, the application of more energy-intensive purification technologies occurs, and thus the energy consumption at the plants increases. Wastewater treatment plants are among the biggest consumers of energy. In this paper, electric energy consumption at wastewater treatment plants was analyzed depending on different indicators of specific energy consumption, the applied technological process, and the level of purification
Extension of the Throughflow Solver for Predicting the Aerodynamic Performance of Fans With Inlet Distortion
No full textNext-generation aircraft with boundary layer ingesting (BLI) engines can reduce fuel consumption but pose challenges for fan and compressor operation due to inlet distortion. To optimize the design of such engines, it is essential to assess the impact of nonuniform inlet flow on stability and performance, with the final result of a distortion-tolerant machine. One of the first steps in this process is estimating the aerodynamic performance using fast but reliable mathematical models. This paper presents an extension of the existing throughflow solver that predicts the effects of the upstream distortion. The proposed method, based on the parallel compressor theory, introduces multiple planes to accurately define and track the circumferential distribution of parameters as they advance through the machine. It applies to all types of distortion: total pressure, total temperature, and swirl. The model is demonstrated for a high-pressure, low hub-to-tip diameter ratio fan with nonuniform total pressure at the inlet. Flow physics associated with distortion is analyzed using results from full annulus unsteady RANS simulations for three operating points: near stall, design, and near choke. The flow field results are compared with the CFD data at the design point. The overall performance is evaluated against a clean inlet case
Comparison of Serial and Parallel Implementations of ILC in a Closed-Loop Feedback System
No full textIterative Learning Control (ILC) is a data-driven strategy for precise trajectory tracking in systems that operate repetitively under similar reference trajectories, disturbances, and
initial conditions. Despite more than three decades of development, some implementation aspects of the learned ILC signals remain underexplored. This paper compares serial and parallel ILC signal implementations within a closed-loop feedback system. Although both approaches have been equally addressed in the literature, our findings show that the serial implementation provides clear advantages in achieving desired performance.No. 451-03-137/2025-03/200105 from 04.02.2025;
451-03-136/2025-03/20006
Optimal Trajectory Tracking of Robot Manipulator Using Resonant Controller
No full textControlling robotic manipulators remains a challenging research area due to their complex, nonlinear, and coupled dynamics [1]. Numerous tracking control methods have been proposed, particularly for tasks requiring repeated execution of closed trajectories in three-dimensional (3D) space - common in industrial applications like welding and painting. While resonant controllers are widely used in electrical systems, their potential in robotics has been largely overlooked. These controllers offer a key advantage: a structural term aligned with the fundamental frequency of the target trajectory. This paper proposes integrating a resonant controller with a particle swarm optimization (PSO) algorithm to minimize tracking error. The main contribution is the novel combination of PSO and resonant control for improved motion accuracy.No. 451-03- 137/2025-03/200105 from 4.2.2025
Monitoring of Reinforced Concrete Beam Damages Using HHT-based Acoustic Emission and Digital Imaging Correlation Technologies
No full textA comprehensive experimental method for monitoring and characterizing the damage evolution of Reinforced Concrete (RC) beams was conducted under three-point bending load, using a combination of Hilbert-Huang Transform (HHT)-based Acoustic Emission (AE) technology and Digital Image Correlation (DIC). AE sensors capture the passive elastic waves emitted during damage progression, and their signals are analyzed using Empirical Mode Decomposition (EMD) to extract key features such as frequency and amplitude. Simultaneously, DIC and strain gauges monitor the deformation and stress distribution on the beam surface and reinforcement. The experimental results demonstrate a clear correlation between AE signal characteristics and the various stages of crack initiation, propagation, and structural failure. AE signals exhibit stage-specific spectral changes, evolving from low-frequency, low-amplitude patterns during micro crack formation to high-frequency, high-amplitude signals during major crack propagation. The DIC strain fields visually capture deformation concentration zones that align well with AE signal trends. This integrated monitoring approach enables the quantitative evaluation of structural damage and offers a reliable method for health monitoring of concrete structures. Subsequently, a database of characteristic parameters for different damage stages is established, providing theoretical support for the application of HHT in analyzing non-stationary signals in Structural Health Monitoring (SHM)
Quadrature rules with quasi-degree of exactness
No full textMany quadrature rules are designed to be exact for easily integrable functions similar to the integrand. The Gauss formula with nodes is exact on the space of all polynomials of degree and it represents a unique optimal interpolatory quadrature rule. It is suitable for application if the integrand is polynomial-like. Note that a function can be similar to certain polynomials, but not similar to some other polynomials. This motivates us to construct a quadrature rule exact only on a subspace of polynomials that share certain properties with the integrand. After choosing arbitrary points (at which the integrand is defined), we transform the given integral into a sum of an integral that does not cause a quadrature error and an integral with a property that the points are the zeros of its modified integrand. Then, we approximate the integral of the modified integrand by an -point formula exact on the subspace of polynomials of degree with fixed zeros (those fixed zeros are not a disadvantage, since the modified integrand has the same zeros) -- such a formula is said to have a quasi-degree of exactness
CNC SIMULATOR BASED ON LINUXCNC CONTROL AND PROGRAMMING SYSTEM
No full textThis work presents a CNC simulator that was created based on the need to design and form a working environment within which training of operators and programmers of CNC machines will be carried out in an economically profitable way. The CNC simulator is based on a Raspberry PI 5 microcomputer and LinuxCNC open source software system intended for control and programming of CNC machines and industrial robots. The LinuxCNC software system was configured according to the set requirements and current needs. With the control system configured in this way, two working environments were formed that are currently used in the realization of laboratory exercises of the teaching process of the higher education institution. In the framework of the paper, the
created working environments are described, and in the conclusion, the observations obtained by analyzing the results achieved using the CNC simulator are presented.Conference proceedings [Elektronski izvor] : 60th Anniversary of the Association of Production Engineering of Serbia
/ 40th International Conference of Production Engineering ICPES 2025 - Serbia 2025, Nis, Serbia, 18th - 19th
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DEVELOPMENT OF COATINGS FOR THE PROTECTION OF METALS STRUCTURES BASED ON PYROPHYLLITE, ZEOLITE AND TALC
No full textThe goal of this work is the development of two types of protective coatings based on pyrophyllite and
talc and coatings based on pyrophyllite and zeolite. For two types of coatings, a mixture of 80% pyrophyllite,
grain size 20 μm and 20% talc, grain size 15 μm, i.e. 80 % pyrophyllite, grain size 20 μm and 20% zeolite,
grain size 15 μm, was used as a filler, respectively. In the composition of the coating, the total amount of
refractory filler was 85%, binder based on epoxy resin 7-10%, 1-2% organic additives and solvent based on
water. Pyrophyllite contributed to the improvement of thermos stability and mechanical resistance of the
coating, talc improved the ability to adhere and coat filler grains, while zeolite contributed to the improvement
of microporous adsorption of active phases, gases, heat, toxins, heavy metals. The manufacturing technologies
of these coatings are ecologically clean. The characterization of the obtained coatings was carried out using
the XRD, SEM and ultrasonic vibration method with a stationary sample according to the ASTM G32
standard. Research has shown that the obtained coatings increase the anti-corrosive and thermal protection of
metal substrates, and in particular, the resistance to wear and cavitation erosion is increased. This provides
wide possibilities of application of these coatings in industry, construction, energy, military industry