University of Niš: Facta Universitatis (E-Journals) / Универзитет у Нишу
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FUNDAMENTAL TONE ESTIMATES ON FINSLER MANIFOLDS
Full text linkWe study the fundamental tone of Laplacian operators on Finsler manifold evolved by a special function , and we give some geometric estimates of the first eigenvalue of p-laplace and (p,q)-Laplace operators depend on this function for simply connected manifolds, a class of warped product manifolds, and a class of Finsler submersions. Under a similar setting, we also study these results on a quasi-linear operator
GEOMETRY AND CURVATURE ANALYSIS OF THE BERGER-TYPE CHEEGER-GROMOLL METRIC ON TANGENT BUNDLES OVER ANTI-PARAKÄHLER MANIFOLDS
No full textIn this paper, we introduce a novel metric known as a Berger-type Cheeger-Gromoll metric on the tangent bundle TM over an anti-paraKähler manifold . In this paper, we introduce a novel metric known as a Berger-type Cheeger-Gromoll metric on the tangent bundle TM over an anti-paraKähler manifold -unit tangent bundle, which is endowed with the Berger-type Cheeger-Gromoll metric. Within this context, we provide the Levi-Civita connection and detail all forms of the Riemannian curvature tensors associated with this metric
PROCENA BLIZINE URBANIH ZELENIH POVRŠINA U NIŠU: GEOPROSTORNA ANALIZA
No full textThe basic prerequisite for realizing the benefits of the implementation of urban green areas (UGS), such as physical and mental health, social cohesion, improving the quality of life, improving air quality, mitigating the effects of heat islands, biodiversity or storm water management, is the spatial proximity of the UGS, their physical availability and accessibility. Applying spatial analysis tools in a GIS environment, the study explores the relationship between the built environment and urban parks in Niš, where such planning tools are underutilized despite the strategic recognition of the importance of UGS in official planning documents. By evaluating the spatial distribution and availability of different types of parks, the research highlights the concept of the "15-minute city" in urban planning. The research includes 48 parks and 33662 buildings generated from the OpenStreetMaps database. The results indicate a low percentage of buildings in close proximity to parks, with significant disparities compared to European cities of similar size. Highlighting the potential of GIS in urban planning decision-making processes, this paper argues for the integration of spatial proximity analysis tools to improve the implementation of UGS and maximize their social benefits.Osnovni preduslov za ostvarivanje prednosti implementacije urbanih zelenih površina (UGS) kao što su fizičko i mentalno zdravlje, društvena kohezija, poboljšanje kvaliteta života, poboljšanje kvaliteta vazduha, ublažavanje efekata toplotnih ostrva, biodiverzitet ili upravljanje atmosferskim vodama, jeste prostorna blizina UGS-a, njihova fizička dostupnost i pristupačnost. Primenjujući alate za prostornu analizu u GIS okruženju, studija istražuje odnos između izgrađenog okruženja i urbanih parkova u Nišu, gde su takvi alati za planiranje nedovoljno iskorišćeni uprkos strateškom prepoznavanju važnosti UGS-a u zvaničnim planskim dokumentima. Ocenjujući prostornu distribuciju i dostupnost različitih tipova parkova, istraživanje naglašava koncept „15-minutnog grada“ u urbanističkom planiranju. Istraživanje uključuje 48 parkova i 33662 objekta generisanih iz OpenStreetMaps baze. Rezultati ukazuju na nizak procenat objekata u neposrednoj blizini parkova, sa značajnim disparitetima u poređenju sa evropskim gradovima slične veličine. Ističući potencijal GIS-a u procesima donošenja odluka o urbanističkom planiranju, ovaj rad se zalaže za integraciju alata za analizu prostorne blizine kako bi se poboljšala implementacija UGS-a i maksimizirale njihove društvene koristi
SLIDING MODE BASED CONTROL AND OBSERVER DESIGN FOR SERIES DC MOTOR VELOCITY REGULATION
Full text linkThis paper presents methods for designing sliding mode based control and observer using feedback linearization in order to obtain a linearized model of the system. Control and observer have been designed for a series DC motor, nonlinear system where the feedback linearization method is applied. A small number of studies examines the case when the armature current is estimated, and the sensor for the rotor velocity is present. The motivation for implementing feedback regulation based on estimated variables in practical applications lies primarily in reducing system costs. It is assumed that the angular velocity of the series DC motor can be measured, and sliding mode observer is used to estimate the armature current. The sliding mode control based on the so-called power rate reaching law is used. Its main characteristic is minimizing chattering, both in the control signal and the switching function. Due to the singularity at the start of the experiment when the armature current is zero, its value is constrained. It is experimentally shown that the estimated value converges to the measured output signal value of the series DC motor. The same holds even in the presence of white noise with a standard deviation of 1.0, although the effects are noticeable under these conditions. The presented simulation results are obtained using the Matlab/Simulink environment and are provided at the end of the paper
PROBABILISTIC DISTRIBUTION SYSTEM PLANNING: INTEGRATING PV-BASED DG, DSTATCOM, AND RECONFIGURATION UNDER SOLAR IRRADIANCE AND LOAD UNCERTAINTIES
Full text linkRecent technological developments in power distribution networks (PDN) have triggered significant interest regarding the optimal operation of power grids. Despite the high cost of power network development and installation, there is a significant opportunity to improve voltage deviation, reduce power loss, boost efficiency, and ultimately raise system stability. This can be accomplished by reconfiguring the network and allocating distributed generations (DG) and distribution FACT devices, like distribution static compensator (DSTACOM), in the most effective way while considering the stochastic nature of solar irradiance variations, uncertainties, and load variations. The presented article enumerates the planning for optimal photovoltaic distributed generation (PVDG) and DSTATCOM device with Network Reconfiguration (NRX) using a hybrid marine predator jellyfish algorithm (HMPJA). Inspired by the coordinated movements of jellyfish and the effective hunting techniques of marine predators such as sharks, the HMPJA was created. It seeks to improve the exploration, exploitation, resilience, and flexibility of optimization algorithms in handling challenging situations by combining these tactics. Inspired by the social behavior of jellyfish and marine predators, this hybrid algorithm is used to evaluate the techno-economic benefits of installing PVDG and DSTACOM in radial PDN with reconfiguration. With multi-objective function Cost reduction, voltage stability enhancement, and voltage profile (VP) augmentation in radial PDN are the primary goals of the current study. The IEEE 33- and 69-bus systems are used to demonstrate the efficacy of the HMPJA, demonstrating notable decreases in energy and power losses and improved VP with overall net profit. A comparison of the suggested strategy with other nature-inspired alternatives demonstrates its superiority. The findings of the proposed approach provide valuable insights for distribution system planning and operation in future grids with high renewable energy source penetration
DEVELOPMENT OF A PROCEDURE FOR INCREASING THE ACCURACY OF THE RECONSTRUCTION AND TRIANGULATION PROCESS OF THE CRANIAL VAULT GEOMETRY FOR ADDITIVE MANUFACTURING
Full text linkCT scanners installed in clinics used different slice thicknesses, which usually produce data with an anisotropic structure of voxels. The low visual quality results are due to the discontinuous interpolation between neighboring voxels, resulting in a very “blocky” appearance of the reconstructed surfaces (stair-step artifact). This structure can also directly affect the volume, geometry, and linear accuracy of digital and physical 3D models. The article presents a method that improves the design of cranial vault models for additive manufacturing after the staircase artifact has occurred. The research was performed on 14 different patients (seven males and seven females). Changing the slice thickness from 2.4 mm to 4.8 mm generated over 90% errors in reconstructing the cranial vault area in the range of 0.830 mm +/- 1.364 mm (mean deviation +/- expanded uncertainty) for males and 0.780 mm +/- 1.338 mm for females. To increase the spatial resolution of the digital imaging data, an interpolation process was performed on 2D radiographic images. After using the data interpolation procedure (Lanczos filter), deviations were mainly in the range of 0.465 mm +/- 1.038 mm for males and 0.328 mm +/- 0.842 mm for females. The last stage of the improved process involved mesh optimization. Utilizing Laplacian smoothing surface and isotropic polygonal remesh, this procedure decreased global error, especially in regions with high curvatures. Over 90% of the analyzed points after using the Lanczos filter and optimization mesh procedure are within the range of 0.338 mm +/- 1.014 mm for males and 0.301 mm +/- 0.806 mm for females
MORFOLOŠKA ANALIZA URBANISTIČKIH BLOKOVA NA NOVOM BEOGRADU: OD IZGRADNJE DO TRANSFORMACIJE
No full textThe plan to expand Belgrade onto the left bank of the Sava River was developed despite the social and technological limitations of the period. Its implementation integrated the confluence of the Sava and Danube rivers into the urban structure, establishing both of them as key urban axes.Early ideas for development of this site, originating in the first decades of the twentieth century, were directly linked to socio-political circumstances that shaped planning strategies for New Belgrade. These strategies were repeatedly revised during the twentieth century, leading to interruptions in urban planning, construction, and policy development.This study examines the planning and construction of New Belgrade, emphasis on its transformation through different stages. It focuses on the design uniformity of residential blocks and the impact of recent urban concepts.The paper applies a morphological analysis to selected urban blocks, defined as basic spatial units of New Belgrade. Criteria for analysis are presented in a tabular form, providing a structured contribution to understanding the urban structure’s development and transformation.Realizacija ambiciozne vizije širenja Beograda na levu obalu reke Save, koja je u trenutku nastanka delovala kao izazov u odnosu na društvene i tehnološke mogućnosti tog vremena, integrisala je ušće Save u Dunav u gradsku strukturu i istovremeno afirmisala obe reke kao važne urbane ose.Ideje o izgradnji na levoj obali Save, koje datiraju iz ranih decenija 20. veka, bile su usko povezane sa društveno-političkim okolnostima koje su snažno oblikovale urbanističke strategije razvoja za Novi Beograd. Ove strategije su tokom dvadesetog veka više puta revidirane, što je dovodilo do prekida u urbanističkom planiranju, izgradnji i razvoju politika.Ovaj rad ispituje planiranje i izgradnju Novog Beograda, sa naglaskom na njegovu transformaciju kroz različite faze. Posebna pažnja posvećena je uniformnosti u projektovanju stambenih blokova i uticaju savremenih urbanističkih koncepata.Primenjena je morfološka analiza karkaterističnih urbanističkih blokova, definisanih kao osnovne prostorne jedinice Novog Beograda. Kriterijumi za analizu predstavljeni su u tabelarnom formatu, pružajući strukturiran doprinos razumevanju razvoja i transformacije urbane strukture
CHALLENGES AND STATISTICAL CONSIDERATIONS IN DERIVING HIGH-FREQUENCY RADIATION LIMITS FOR POWER DRIVE SYSTEMS
Full text linkLimits for high frequency radiated emissions from electrical equipment have been specified for many decades already. Though the main reason for the limits is the protection of radio services which parameters are well known, in many cases the technical background or the justification for the derivation of those limits is not known or has not been described and published. To overcome this situation, in particular when being faced with the work on new limits, a probabilistic approach has been developed in the standardisation document CISPR TR 16-4-4 which is intended to be used for the derivation of limits. This paper describes the process of deriving such limits for a particular type of equipment, i.e. power drive systems (PDS), and for a particular probability factor which considers the directivity. It focuses on a probabilistic approach with respect to the radiation pattern caused by such equipment
A SCALABLE EDGE-CLOUD ARCHITECTURE FOR SMART ADAPTIVE STREAMING DATA ANALYSIS
Full text linkThe dynamic nature of data generated by Internet of Things (IoT) devices creates challenges for maintaining the accuracy of machine learning models in real-time anomaly detection. Most existing methods assume static datasets and fail to handle evolving distributions, leading to model degradation, a phenomenon known as concept drift. This paper introduces a scalable edge–cloud architecture with a feedback loop for adaptive streaming analysis, enabling real-time anomaly detection and automated model updates when drift is detected. A prototype system implementation demonstrates feasibility, showing that the system adapts to changing patterns, lowers computation on resource-limited edge devices, and scales effectively across data streams. Experimental results validate the approach, revealing improvements in detection accuracy and reduced edge-side processing, thereby sustaining model performance in dynamic IoT environments
A RECTANGULAR PATCH ANTENNA FOR INTERNET OF THINGS APPLICATIONS IN SUB-6 GHZ BAND
Full text linkIn the rapidly expanding domain of the Internet of Things (IoT), there is a burgeoning requirement for compact and efficient antennas operating within the Sub-6 GHz frequency range (2.3–4.2 GHz). This research focuses on the design and optimization of a rectangular patch antenna, specifically intended for use in Internet of Things (IoT) applications within this frequency spectrum. The proposed antenna features a rectangular slot in the ground plane and employs substrate removal methodologies to enhance its performance. It is made on an FR-4 substrate, characterized by a loss tangent of 0.025, a dielectric constant of 4.3, and a thickness of 1.6 mm. The antenna is fed through a 50-Ohm inset feedline to ensure effective signal transmission. Simulations are conducted using CST Studio Suite to evaluate the antenna's design and performance metrics. The results indicate an impressive reflection coefficient (S11) of 35.39057 dB, a 209.273 MHz bandwidth (2.525316 GHz–2.734589 GHz), and a VSWR of 1.03908. Furthermore, the antenna exhibits a gain of 0.623 dBi, a directivity of 3.71 dBi, and a radiation efficiency of 49.12%. These findings strongly suggest the antenna’s excellent potential for diverse IoT services, promising reliable and robust wireless communication. Future research will focus on physical prototyping, further parametric optimization, and integration into practical IoT devices. This study significantly contributes to the progression of high-performance antenna design for next-generation IoT systems, consequently aiding in the creation of more compact and efficient wireless communication technologies