University of Niš: Facta Universitatis (E-Journals) / Универзитет у Нишу
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QUANTITATIVE ANALYSIS AND OPTIMIZATION OF ENERGY EFFICIENCY IN ELECTRIC MULTIPLE UNITS
Full text linkThe increasing urgency for sustainable transportation solutions necessitates a thorough examination of energy efficiency within railway systems. This study investigates the energy performance of Siemens Ventus (i.e., Siemens Desiro ML type) electric multiple units on Austria's Raaberbahn network, focusing on route-specific energy consumption and the optimization of regenerative braking. Utilizing data collected from January to May 2023, the research employs a robust methodology that integrates statistical analysis, curve-fitting, and geospatial modeling to assess energy trends along routes connecting Vienna, Bratislava, and Deutschkreutz. The findings reveal that terrain, operational practices, and external environmental factors significantly contribute to energy inefficiencies. Specifically, hotspots of energy overconsumption were identified, leading to the development of tailored optimization models for each route. The analysis also produced heatmaps that illustrate critical spatial and temporal patterns, which are essential for implementing targeted interventions aimed at enhancing energy efficiency
POLYESTER APPAREL CUTTING WASTE AS SOUND INSULATION MATERIAL
Full text linkThis study developed an insulation structure using waste from apparel cutting and examined its sound insulation capabilities. Shredded polyester apparel cuttings served as the primary material for this structure. Results indicate that the insulation made from apparel waste exhibits superior sound absorption properties compared to conventional sound and thermal insulators. The average sound absorption ranged from 54.7% to 74.7% across frequencies from 250 to 2000 Hz. This research proposes a method to reduce environmental pollution by repurposing polyester apparel waste for insulation in roofs and internal walls
DYNAMIC ANALYSIS OF A NANOBEAM UNDER THE INFLUENCE OF AN ELECTROMAGNETIC ACTUATOR AND A MECHANICAL IMPACT
Full text linkThe Optimal Auxiliary Functions Method (OAFM) is applied in the study of nonlinear vibration of a nanobeam, considering the curvature of the beam, the presence of an electromagnetic actuator and a mechanical impact. Our procedure is based on the existence of some auxiliary functions which assure a fast convergence of the approximate solution. The convergence-control parameters present in the auxiliary functions are evaluated by rigorous mathematical procedures
NOISE LEVEL MEASUREMENTS OF ROAD TRAFFIC AT DIFFERENT HEIGHTS IN RELATION TO THE NOISE SOURCE
Full text linkThe paper provides an analysis of the results of noise levels originating from road traffic measured at different heights on the example of an eighteen-story solitaire in the Dušanovac, which is located along the traffic road Bulevar Franše d'Eperea in Belgrade (the former section of the E-75 Belgrade-Niš highway). Measurements were made simultaneously at three measuring points, on the second, tenth and eighteenth (last floor) of the solitaire
OPTIMIZING FRACTIONAL ORDER PID CONTROLLER FOR DC MOTOR SPEED CONTROL USING ARTIFICIAL HUMMINGBIRD ALGORITHM
Full text linkThis study implements the artificial hummingbird algorithm (AHA) to tune the FOPID controller optimally for DC motor speed control. The AHA algorithm is a straightforward and efficient method that mathematically simulates the foraging strategies of hummingbirds. It has been specifically designed to tackle a wide range of optimisation challenges. For a fair comparison, the proposed AHA-FOPID controller is tuned using the ITAE objective function and evaluated alongside the controllers optimized through GWO, PSO, and DE in the previous researches. Additionally, transient response analysis and load disturbance analysis are conducted. The suggested controller exhibits exceptional transient performance, as seen by a settling time of 0.0329 seconds, a rising time of 0.0208 seconds, and no overshoot. The simulation findings are encouraging and confirm the efficacy of the proposed technique. Ultimately, a statistical analysis is conducted to confirm the superiority of the proposed method
ON RICCI SEMI-SYMMETRIC MIXED QUASI-EINSTEIN HERMITIAN MANIFOLD
Full text linkThe object of the present paper is to study Bochner Ricci semi-symmetric mixed quasi-Einstein Hermitian manifold and holomorphically projective Ricci semisymmetric mixed quasi-Einstein Hermitian manifold
ON CONFORMALLY FLAT p-POWER (alpha,beta)-METRICS
No full textThe purpose of this paper is to study the class of conformally flat p-power (alpha,beta)-metrics F = alpha(1 + beta/alpha)^p, where p ̸= 0 is a constant. This metric is interesting, because for p = -1; 1/2; 1; 2 it reduces to the Matsumoto, square-root, Randers, and square metric, respectively. We prove that if a p-power (alpha,beta)-metric has relatively isotropic mean Landsberg curvature, then it is either a Riemannian metric or a locally Minkowski metric
ROUGH STATISTICAL CONVERGENCE OF SEQUENCES IN A PARTIAL METRIC SPACE
Full text linkIn this paper, using the concept of natural density, we have introduced the notion of rough statistical convergence which is an extension of the notion of rough convergence in a partial metric space. We have defined the set of rough statistical limit points of a sequence in a partial metric space and proved that this set is closed and bounded. Finally, we have found out the relationship between the set of statistical cluster points and the set of rough statistical limit points of sequences in a partial metric space
ALMOST SCHOUTEN SOLITONS ON N -CONTACT METRIC MANIFOLDS
No full textIn the current paper, we have studied almost Schouten solitons and gradient Schouten solitons on an -Contact metric manifold of dimension . Besides, we have shown that the almost Schouten soliton does not exist on -Contact metric manifold for . In addidtion, it has been proved that the manifold complying with the gradient Schouten solitons only when it is an almost -Contact metric manifold. Moreover,we have determined that a -dimensional -Contact metric manifold admitting a gradient Schouten soliton is either flat or of constant scalar curvature. Finally, an example has been conducted to verify the outcomes
DOMINATION NUMBER AND WATCHING NUMBER OF SUBDIVISION CONSTRUCTION OF GRAPHS
Full text linkIn light of the results of a domination number of the subdivision of a graph G, we determine an upper bound of the watching number of S(G). In addition, we obtain a condition with which the upper bound becomes sharp