University of Niš: Facta Universitatis (E-Journals) / Универзитет у Нишу
Not a member yet
4905 research outputs found
Sort by
ON ϕ-RECURRENT TYPES OF PARACONTACT METRIC (κ ̸= −1, µ)-MANIFOLDS
Get PDFThe main aim of the present paper is to investigate geometric properties of hyper-generalized ϕ-recurrent and quasi-generalized ϕ-recurrent paracontact metric (κ ̸= -1, µ)-manifolds
FUZZY AHP - FUZZY MABAC MODEL FOR RANKING A COMBINED CONSTRUCTION MACHINE - BACKHOE LOADER
Get PDFThe paper presents a multi-criteria decision-making (MCDM) model designed to rank combined construction machines - specifically, Backhoe Loaders - during procurement for military needs. However, the model can also be applied to construction companies. The ranking is based on criteria specifically defined for this research. The study found that most criteria relate to the structural elements of the Backhoe Loader, which is also significant for manufacturers working on improving these types of machines. The MCDM model is built on two methods: Analytic Hierarchy Process (AHP) and Multi-Attributive Border Approximation area Comparison (MABAC), both adapted using fuzzy numbers. The AHP method was modified with type 2 fuzzy numbers to calculate criteria's weight coefficients. The MABAC method, using classic triangular fuzzy numbers, is employed for ranking alternative solutions. Validation of the results involved two steps. First, a sensitivity analysis was performed by modifying the weight coefficients of the criteria. Second, a comparative analysis with other methods was performed. The validation process confirmed the stability of the obtained results
PRESSURE OPTIMIZATION IN DEC SPRAY CHAMBERS: A COMPREHENSIVE STUDY ON HEAT AND MASS TRANSFER DYNAMICS
Get PDFAchieving optimal contact between air and droplets is pivotal in direct evaporative cooling systems. This study presents an experimental analysis of spray cooling effectiveness in spray chambers utilizing pressure-swirl nozzles and impingement atomizing nozzle. Through the analysis of experimental data related to heat and mass transfer, the study reveals that if an optimal water supply pressure is identified, increasing the water flow rate does not necessarily enhance cooling performance. Furthermore, the study explores the impact of dry-bulb and wet-bulb temperatures of the air, as well as nozzle arrangement, on the determination of the optimal water supply pressure
PERFORMANCE ANALYSIS OF MODEL FOR FAULT DIAGNOSIS IN RADIATION-HARDENED MEMORIES USING SVDD-PSO
Get PDFRadiation-hardened memories are extensively used in critical commercial applications such as nuclear power plants, industrial systems, and space missions for reliable data storage and retention. While numerous algorithms have been proposed for diagnosing faults in these memories, most focus less on fault optimization. To address this gap, this paper presents a performance analysis of a fault diagnosis model based on the Support Vector Data Description–Particle Swarm Optimization (SVDD-PSO) algorithm for fault optimization. The proposed fault diagnosis model is designed using specific parameters tailored for radiation-hardened memories. The results demonstrate that the methodology achieves higher accuracy, optimal fitness value, and reduced time penalty when diagnosing fault samples. The model's performance is further evaluated using logistic regression, with a Receiver Operating Characteristic (ROC) curve accuracy of 96%, reflecting a balanced trade-off between the true positive rate (TPR) and false positive rate (FPR). The higher TPR and lower FPR confirm that the proposed model is well-suited for fault diagnosis in radiation-hardened memory systems
EMERGING CONCEPT OF PERSONALIZED MEDICINE VENDING MACHINE BASED ON THE ERA OF COVID-19 PANDEMIC
Get PDFThis paper presents the new concept of Medicine Vending Machine (MVM), called Personalized Medicine Vending Machines (PMVM), motivated by the need to increase social distancing during the COVID-19 pandemic. The conceptual model, the scenarios of using PMVM, and all the necessary preconditions are provided. This paper proposes modifying the existing MVM concept, which can provide better social distancing in times of pandemics and epidemics, emphasizing personalization and picking up prescribed therapy. The medical information system MEDIS.NET has been used as a keystone in the development of PMVM. Pharmacies and patients use prescription data stored in patient electronic health records in MEDIS.NET to provide all conditions needed for the operation of PMVM. Real data from the Pharmacy Institution Nis and Health Center Nis are used to define the scenarios for the use of PMVM. The proposed PMVM would be a new service for smart cities that can contribute to the significant increase of the efficiency of smart cities during the combat against COVID-19 and any similar pandemics in the future
NANOTECHNOLOGY QCA-BASED SUB-COMPONENTS OF PROCESSOR DESIGN AND APPLICATION OF FUTURISTIC LOW-POWER DESIGN
Get PDFMany devices consist of low-power processor. Quantum-dot-cellular-automata (QCA) based processor designs provide enhanced performance compared with conventional metal-oxide-semiconductor (MOS) based processors. Nanocomputing-based processors are often energy-efficient. We have developed Nanotechnology QCA-based different sub-components of processor such as 2-to-4 decoder, 3-to-8 decoder, Delay Flip-flop (D-FF), and sequence counter. A potential energy proof has been measured in the 2-to-4 decoder design. The synthesis approach algorithm has been presented for all designs. Further, the potential energy calculation results show for 2-to-4 decoder. According to the synthesis results 2-to-4 decoder has improved 82.3% cell count, 86% area, and 85% latency over previous work. Comparing the primitive results with the prior one, results improved by 64% and 76% in terms of cell count and area in the design of the 3-to-8 decoder. Among the different components of the processor is D-FF, which has an improvement of 66.37% in cell counts and 62.5% in area over the prior design. Primitive results have improved, including latency, cell count, and area, showing the proposed processor design is comparable to low-power devices and high speed. In terms of balance power, the proposed subcomponent of the processor will benefit low power device
THE CHARNES, COOPER AND RHODES MODEL AND ITS APPLICATION
Get PDFThe paper is about application of the Data Envelopment Analysis methodfor combined heat and power plants. The methodology of analyzing complex systemsis developed. The efficiency of complex systems based on the Charnes, Cooper andRhodes model is evaluated. An algorithm for estimating efficiency using the CCRmodel is presented. Experiments on the use of this algorithm on the model are carriedout. Efficiency coefficients of the analyzed combined heat and power plants using theCCR model with input and output orientation have been calculated. The inputs andoutputs for achieving the efficiency of the CCPPs facilities with efficiency coefficientsless than 1 are calculated
ON GENERALIZED FRAMED AND FRENET-TYPE FRAMED BERTRAND CURVES IN EUCLIDEAN 3-SPACE
Get PDFIn this paper, we consider Framed and Frenet-type Framed Bertrand curves. We generalized the notion of Framed and Frenet-type Framed Bertrand curves in Euclidean 3-space. According to this generalization, the Bertrand curve conditions of a given Framed and Frenet-type Framed Bertrand curves are obtained and the relations between the moving frames and curvature functions are given
SURFACE ENERGY CHARACTERIZATION OF A SINGLE MICROSPHERE PARTICLE USING PEAKFORCE QUANTITATIVE NANOMECHANICAL MAPPING MODE OF ATOMIC FORCE MICROSCOPE
Get PDFThe composites are typically created by embedding functional fillers in polymeric matrices. The key indicators of reliable performance include homogeneous filler dispersion and optimal interfacial properties between the fillers and matrix. Poor dispersion causes stress concentration, premature failure, and increased filler requirement for achieving functional properties like conductivity. Additionally, interfacial characteristics are governed by surface energy differences and significantly influence the mechanical properties like elongation and rupture stress. Conventional methods for measuring surface energy, such as contact angle or Washburn adsorption, have limitations when applied to microscale powders, including issuers with accurate size handling and bulk material requirements. To overcome these challenges, the PeakForce QNM (quantitative nanomechanical mapping) mode of atomic force microscopy (AFM) was used to measure the surface energy on the surface of the powder microspheres. This method was used to characterize the surface energies of 2–5 μm carbonyl iron powders with various surface coatings. Differences in the surface energies corresponded to variations in the dispersibility and mechanical performances of these powder-based composites. The proposed nanoscale approach provides critical insights into the interfacial mechanisms, enabling enhanced design and optimization of stetchable composites for advanced electronic applications
LUMBOSAKRALNI BOL KOD STUDENATA FAKULTETA SPORTA I FIZIČKOG VASPITANJA
No full textThe aim of the research was to determine the presence, prevalence, and causes of lumbosacral pain (LP), as well as the connection between lifestyle habits and the occurrence of LB among students at the Faculty of Sports and Physical Education (FSPE) at the University of Belgrade. The sample consisted of 187 third- and fourth-year students. Data collection regarding personal characteristics, lifestyle habits, and characteristics of LP was conducted using a non-standardized questionnaire. The data were presented in terms of response frequency and percentage representation of each category. The significance of the differences between response categories, as well as differences between genders, was tested using the t-test for independent samples for parametric variables, while the chi-square test was used for non-parametric variables. The results show that 48.1% of all the respondents had experienced pain at least once in their lifetime; 20.3% reported pain once in the past 12 months; 13.5% experienced pain 2-4 times in the past 12 months; and 18.1% had LP more than 4 times during the past year. Reported LB most commonly ceased within a few hours to one day after onset (66.6%), and rarely lasted longer than 7 days (6.2%). The conclusion is that the prevalence of LP among FSPE students is high, but the pain itself most often lasted briefly and did not significantly impair their daily activities. To reduce the prevalence of LP in the future, greater attention should be directed towards developing and implementing various preventive measures that may include specific forms of exercise and corrected sitting postures.Cilj istraživanja je bio da se utvrde prisustvo, prevalencija, uzroci lumbosakralnog bola (LB), kao i povezanost životnih navika sa pojavom LB kod studenata Fakulteta sporta i fizičkog vaspitanja (FSFV-a) Univerziteta u Beogradu. Uzorak ispitanika je činilo 187 studenata treće i četvrte godine akademskih studija. Prikupljanje podataka o ličnim karakteristikama, životnim navikama i karakteristikama LB je izvršeno pomoću nestandardizovanog upitnika. Podaci su predstavljeni frekvencijom odgovora i procentualnom zastupljenošću svake kategorije. Značajnost razlike između kategorija odgovora, kao i razlike između polova su testirane t-testom za nezavisne uzorke kod parametrijske varijable, dok je kod neparametrijskih korišćen Hi-kvadrat test (chi-square test). Rezultati pokazuju da je 48,1% svih ispitanika osetilo bol barem jedanput u životu, 20,3% ispitanika je bol osetilo jednom u proteklih 12 meseci, 13,5% ispitanika 2-4 puta u proteklih 12 meseci. a 18,1% ispitanika je imalo LB više od 4 puta tokom proteklih 12 meseci. Prijavljeni LB je najčešće prestajao nakon nekoliko sati do jednog dana od momenta javljanja (66,6%), a retko je trajao duže od 7 dana (6,2%). Zaključak je da je prevalencija LB kod studenata FSFV-a na visokom nivou, ali je sam bol najčešće trajao kratko i nije u većoj meri ugrožavao njihove svakodnevne aktivnosti. U cilju smanjenja prevalencije LB, u budućnosti bi veću pažnju trebalo usmeriti na razvoj i primenu različitih preventivnih mera koje mogu uključivati primenu specifičnih oblika vežbanja i korigovanog načina sedenja