University of Niš: Facta Universitatis (E-Journals) / Универзитет у Нишу
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KONCEPT INTERMEDIJARNIH PROSTORA
No full textThe contemporary context, which manifests itself as transcultural and subject to hybridization, requires an appropriate spatial-programmatic logic that has the ability to assimilate and examine relations at different levels and support the needs of the contemporary user. The contemporary development of the methodology of the design process is essentially related to the complex state of relations between different typоlogies and relations within specific typologies in the contemporary cultural - social context. Accordingly, the research forms the concept of intermediary spaces through a tripartite synthesis, linking and permeating three themes: the relation architecture - deconstruction, the relation type - hybridization, and the concept of transculturality. Synthetically intertwined and interwoven, they provided an appropriate conceptual and theoretical basis for the research. Principles have been extracted from areas that are tangential to the theory of architecture and the methodology of architectural design, with the aim of forming the concept of intermediary spaces and examining the role of intermediary spaces as a methodological tool in the process of architectural design of trans-typological architectural concepts, which are characterized by hybridization and/or the state of hybridity in the contemporary context of architectural thinking and creation.Savremeni kontekst koji se manifestuje kao transkulturalan i podložan hibridizaciji, iziskuje odgovarajuću prostorno-programsku logiku koja poseduje sposobnost da asimiliuje i preispita relacije na različitim nivoima i podrži potrebe savremenog korisnika. Savremeni razvoj metodologije procesa projektovanja suštinski je vezan za kompleksno stanje relacija između različitih tipologija i relacija unutar posebnih tipologija u savremenom kulturno-društvenom kontekstu. U skladu sa tim istraživanje formira koncept intermedijarnih prostora kroz tripartitnu sintezu, uvezivanjem i prožimanjem tri teme: relacija arhitektura – dekonstrukcija, relacija tip – hibridizacija i koncept transkulturalnosti. Sintezno isprepletane i protkane, pružile su odgovarajuću pojmovnu i teorijsku osnovu za istraživanje. Iz oblasti koje su tangentne teoriji arhitekture i metodologiji arhitektonskog projektovanja ekstrahovani su principi, u cilju formiranja koncepta intermedijarnih prostora i preispitivanje uloge intermedijarnih prostora kao metodološkog alata u procesu arhitektonskog projektovanja trans-tipoloških arhitektonskih koncepcija, kojima je svojstvena hibridizacija i/ili stanje hibridnosti u savremenom kontekstu arhitektonskog mišljenja i stvaranja
NAPREDNA PRIMENA TEHNIKE "MLAZNOG INJEKTIRANJA" U BUGARSKOJ GEOTEHNIČKOJ PRAKSI
No full textThe primary objective of this paper is to showcase the versatile application of jet-grouting as a comprehensive approach for enhancing both structural integrity and soil behavior. This will be achieved by presenting practical examples of its successful implementation within the field of geotechnical engineering in Bulgaria, taking into account the unique local soil conditions. Jet-grouting is a well-acknowledged method for cement soil stabilization, involving the utilization of high-pressure water or cement suspension jets, enveloped in air, to erode and subsequently reconfigure the soil surrounding a borehole. The mechanical properties of the resultant medium are intricately linked to the local soil characteristics and various technical parameters associated with the jet-grouting system, including the number of nozzles, treatment duration, pressure, and fluid composition, among others. Remarkably, the existing design practices in Bulgaria, except for EN 12716:2003, do not offer specific directives or recommendations concerning the execution and quality control of the jet-grouting technique. Consequently, this paper not only aims to advocate best practices for the adoption of jet-grouting in the Bulgarian context but also seeks to elucidate the expected mechanical properties under diverse local soil conditions.Osnovni cilj ovog rada je da predstavi raznovrsnu primenu tehnike mlaznog injektiranja kao kompleksnog pristupa za poboljšanje strukturne celovitosti i ponašanja zemljišta. Ovo će biti postignuto predstavljanjem praktičnih primera njegove uspešne primene u oblasti geotehničkog inženjerstva u Bugarskoj, uzimajući u obzir jedinstvene lokalne uslove zemljišta. Mlazno injektiranje je dobro priznat metod stabilizacije cementnih zemljišta, uključujući korišćenje mlaznih tečnosti pod visokim pritiskom sa vodom ili cementnom suspenzijom, u okruženju vazduha, kako bi se erodiralo i posledično rekonfigurisalo zemljište u okolini bušotine. Mehaničke osobine rezultirajućeg sredstva su složeno povezane sa lokalnim karakteristikama zemljišta i različitim tehničkim parametrima povezanim sa sistemom mlaznog injektiranja, uključujući broj dizni, trajanje tretmana, pritisak i sastav tečnosti, između ostalog. Zapaža se da postojeći praktični projekti u Bugarskoj, osim za EN 12716:2003, ne nude specifična uputstva ili preporuke u vezi sa izvođenjem i kontrolom kvaliteta tehnike mlaznog injektiranja. Stoga, cilj ovog rada nije samo da propagira najbolje prakse za usvajanje mlaznog injektiranja u bugarskom kontekstu, već takođe da rasvetli očekivane mehaničke osobine u raznolikim lokalnim uslovima zemljišta
VEHICLE DETECTOR BASED ON THE MAGNETIC FIELD SENSOR AND THE FIXED-THRESHOLD ALGORITHM IMPLEMENTED VIA FINITE STATE MACHINE
Full text linkAn automated vehicle detection process is one of the main objectives of Intelligent Transportation Systems. Different technologies, such as inductive loops, video surveillance, or acoustic sensors, are used for vehicle detection. A one of the most effective solution is based on magnetic field measurement. This detection method relies on analysis of the Earth's magnetic field changes induced by ferromagnetic materials inside a vehicle's structure. The vehicle detector composed of the magnetic field sensor used for measurements and the microcontroller with embedded detection algorithm is described in this paper. The detection algorithm compares changes in the magnetic field with a defined fixed-threshold value implemented as the finite state machine. Changing the state of the finite state machine in the defined order means that the vehicle is detected successfully. The method for determining the finite state machine parameters that depend on the fixed-threshold values and frequency of the measurements is described in detail. The vehicle detector is tested in the laboratory environment, and the results show the appropriate detection accuracy compared to the other detection algorithms in the literature
A RESULT ON THE CHERMAK-DELGADO MEASURE OF A FINITE GROUP
Full text linkIn this short note, we describe finite groups all of whose non-trivial cyclic subgroups have the same Chermak-Delgado measure
ON DOUGLAS TENSOR OF INFINITE SERIES FINSLER SPACE
Full text linkIn this article, we consider the Finsler space Fn (n > 2) with an infiniteseries (α, β)-metric and establish the necessary and sufficient conditions for it to be of Douglas type. Additionally, we demonstrate the criteria under which this metric in a Finsler space becomes a Berwald space. Furthermore, the space is shown to be projectively flat if it is a Berwald space.
A NOVEL APPROACH TO PREDICTING THE CUTTING FORCE IN TURNING USING DIMENSIONAL ANALYSIS
Full text linkCutting forces are a critical indicator of the machining process, and their modeling is important for a variety of reasons, including tool life assessment, chatter prediction, tool condition monitoring, assessment of machining strategies and machining process optimization and control. This paper presents a new principle of modeling the main cutting force using dimensional analysis (DA). Dry longitudinal single-pass turning of two different steels (20MnCrS5 and S235JRG2) with two different cutting inserts, was considered. Taguchi's 33×21 design with 6 trials was applied to arrange seven parameters: depth of cut, feed rate, cutting speed, feed velocity, rake angle, cutting edge angle, and workpiece material parameter, i.e., tensile strength. The obtained results, including additional validation tests, showed a very good prediction capacity of the DA-based model in estimating the cutting force during the turning process. The analysis includes the influence of parameters on the cutting force as well as examination of 3D surface diagrams and correlation coefficients. The chip slenderness ratio proved to be the most important dimensionless group for cutting force prediction. By performing additional experimental trials, the correction coefficient for the tool nose radius was estimated and extended models were developed. The well-known Victor-Kienzle model can be used to predict the cutting force if the exact values of mc and kc1.1 coefficients. The proposed DA-based models proved to be valid for predicting all three cutting force components with high accuracy
SVM-BASED EMOTION RECOGNITION FROM SPEECH WITH GTCC AND FREQUENCY FEATURES
Full text linkWhen a person is in a certain emotional state, a large number of physiological changes occur in the body. These changes significantly affect the way words are pronounced compared to neutral speech. This means that the configuration of the vocal tract changes depending on the speaker’s emotional state. Furthermore, in emotional speech, physiological changes influence certain speech properties, such as speech rate, intensity, and pitchSuccessful classification of emotional speech into the appropriate emotion class requires extraction of salient speech features and construction of a feature vector composed of discriminative attributes that facilitate accurate classification. In this study, we use Gammatone Cepstral Coefficients (GTCC) as components of the feature vector for speech emotion recognition. GTCC are a biologically inspired modification of Mel-Frequency Cepstral Coefficients (MFCC). They are based on gammatone filters, which simulate the human auditory system more effectively than the mel-frequency filters used in MFCCThe remainder of the feature vector is composed of spectral characteristics extracted from the speech signal. In our classification model, the components of the feature vector are primarily extracted by performing spectral analysis on short-time frames of the observed speech signal. Feature vectors constitute discriminative representations that facilitate the more effective classification of speech into corresponding emotional categories. Our classifier is based on Support Vector Machines (SVM), with optimized hyper-parameters
UWB-BASED GEOFENCING: A ONE-CLASS CLASSIFICATION APPROACH WITH FINGERPRINTING AND TRILATERATION
Full text linkUltra-wideband (UWB) technology has emerged as a powerful solution for indoor localization, offering high accuracy, low power consumption, and robust penetration through obstacles. Among its applications, geofencing enables the creation of virtual boundaries for monitoring and security purposes. This paper presents a novel one-class classification (OCC) approach for UWB-based geofencing, named the k-Nearest Neighbours with Residual Norm Threshold (kNN-RNT) algorithm. The proposed method utilizes fingerprinting and trilateration techniques, operating in two distinct phases: an offline phase for constructing a reference fingerprint database and an online phase for real-time classification of a mobile tag’s location. The kNN-RNT algorithm determines geofence violations by analysing the distribution of nearest fingerprints and computing a residual norm to classify locations. A filtering mechanism enhances detection stability, mitigating noise and transient errors. Experimental validation in a controlled indoor environment demonstrates the effectiveness of the method, achieving over 99% accuracy within the geofenced area and significantly reducing classification errors in proximity zones. The proposed approach provides a reliable and efficient solution for real-time UWB-based geofencing applications
PHASE ANGLE CONTROL AND RPM MEASUREMENT OF UNIVERSAL MOTOR UTILIZING OF CAN BUS
Full text linkThis paper presents phase angle control and RPM measurement of a universal electric motor using a CAN interface. The system consists of two devices based on a microcontroller ATmega328P that are connected through a CAN bus for sending and receiving data for phase angle regulation and speed measurement. The system is implemented and checked in the laboratory using an oscilloscope and logic analyzer. Also, the obtained results and signal diagrams are presented as well
KORELACIONI VEZNICI I IZGRADNJA MENTALNIH PROSTORA: NARUŠAVANJE KOORDINISANIH STRUKTURA NUDI KORELACIONE DOKAZE U KORIST PSIHOLOŠKE REALNOSTI MENTALNIH PROSTORA
No full textThe paper aims to explore how violations of parallel structure in English correlative conjunctions affect participants’ response times (RTs) and accuracy ratings in an online incremental grammaticality judgment task, where correlative conjunctions are understood as space builders (i.e., each correlative conjunction is expected to yield a dual-space network). The study included 37 advanced EFL students from the University of Niš. The main experiment included 14 target sentences with 7 different correlative conjunctions, with the second part of a correlative conjunction missing. Stimuli were presented word-by-word, with a mask, in a self-paced moving windows paradigm. The relevant independent variables recorded in Open Sesame were RTs and response accuracy. The obtained results show increased RTs associated with error positions. Specifically, the analysis of the overall mean tendency across all items and over the entire sample showed significantly higher mean RTs in the error position compared to RTs in accurate sentence positions (p<.001). Moreover, the analysis of overall accuracy showed a significantly higher mean value of accurate responses for correct sentence parts compared to the sentence parts with an error (p=.006), and a significantly lower mean value of inaccurate responses in correct sentence parts compared to parts of sentences with errors (p=.015). By-item analyses showed higher counts of accurate responses in error positions, which also reached significance in most cases. The obtained results offer correlational support for the psychological reality of parallel structure and mental spaces.Cilj istraživanja je da utvrdi kako narušavanje koordinisanih struktura kod korelacionih veznika u engleskom jeziku utiče na brzinu reakcije i tačnost odgovora ispitanika prilikom ocene gramatičnosti ciljnih rečenica. Korelativni veznici se dovode u vezu sa izgradnjom mentalnih prostora. U glavnom eksperimentu, ciljne draži predstavljane su reč-po-reč, kroz paradigmu pokretnih ekrana, a ispitanici su imali zadatak da nakon uvođenja svake nove reči ocene gramatičnost rečenice u datom trenutku. Rezultati su pokazali duže vreme reakcije u pozicijama na kojima se nalazila greška, a razlika je dostigla i statističku značajnost (p<.001). Analizom tačnosti odgovora utvrđen je takođe značajno veći broj tačno ocenjenih grešaka u ciljnim pozicijama. Dobijeni rezultati nude korelacione dokaze u korist psihološke realnosti koordinisanih struktura i mentalnih prostora