University of Niš: Facta Universitatis (E-Journals) / Универзитет у Нишу
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EXISTENCE RESULTS FOR A HYBRID SYSTEM OF MIXED DIFFERENTIAL EQUATIONS WITH SEQUENTIAL FRACTIONAL DERIVATIVES
Full text linkIn this paper, we focus on the study of a hybrid system of sequential type that incorporates both Caputo and Hadamard fractional derivatives. Our approach leverages the fixed point principle to derive novel results concerning the existence and uniqueness of solutions to this system. Additionally, we establish further results by employing Schaefer’s fixed point theorem, which allows us to extend the applicability of our findings. To illustrate the practical relevance and application of our theoretical results, we also provide a detailed example at the conclusion of the paper. At the end, an example is given
ON DOUBLE WIJSMAN STRONG DEFERRED CESÀRO SUMMABLE SET SEQUENCES
Full text linkBy this study, for double sequences of sets, we first presented strongly r-deferred Cesaro summability (0 < r < \infty) concept (in Wijsman sense), and we examined relations between this concept and deferred statistical convergence concept. Then, we gave theorems associated with Wijsman strongly r-deferred Cesàro summability concept
COMMON FIXED POINT FOR w−COMPATIBLE MAPS IN A BIPOLAR METRIC SPACE
Full text linkThe purpose of this paper is to establish some common fixed point theorems of w-compatible maps in bipolar metric spaces by employing a comparison function ϕ instead of some altering distance functions. We employ generalized type contraction conditions involving the comparison function ϕ to enunciate common fixed point theorems. Further, we provide illustrative examples to uphold our results
RICCI SOLITONS AND RICCI BI-CONFORMAL VECTOR FIELDS ON THE MODEL SPACE
Full text linkIn this paper, we classify the Ricci solitons and the Ricci bi-conformal vector fields on model space . We also show which of them are gradient vector fields and which one of those are Killing vector fields
A MODIFIED FREQUENCY FORMULATION FOR NONLINEAR MECHANICAL VIBRATIONS
Full text linkThe paper elucidates the characteristics of nonlinear oscillators that contain quasi-linear terms arising in mechanical engineering. Analytical solutions for this type of nonlinear oscillator are often difficult to obtain; they may involve singular and discontinuous terms, which can make them significantly more difficult to obtain. In this paper, a modified frequency formulation for this type of nonlinear oscillator is presented. While the mathematical proof is not provided, illustrative examples are included to demonstrate the remarkable simplicity and reliability of the approach. This paper challenges the conventional wisdom in analytical methods and offers a promising new direction for further investigation
SCENARIO-LEVEL HIERARCHICAL ENERGY MANAGEMENT CONTROL STRATEGY FOR HYBRID ELECTRIC VEHICLE
Full text linkTo address the challenge that single-scenario solutions often fail to adequately handle the complex and dynamic mixed environments that drivers regularly navigate, this study aims to leverage learning-based algorithms to design energy management control strategies tailored to the unique characteristics of different driving scenarios. The goal is to achieve precise matching and efficient execution of the driving strategies. The main research focus of this study is developing a scene-level hierarchical energy management control strategy (SHEMS) framework for hybrid electric vehicles in mixed driving environments. In the car-following scenario, to address the challenges of reward function design and the impact of environment and driver habits, an adaptive strategy learning strategy with imitation learning is proposed. To overcome issues of suboptimal expert knowledge and the curse of dimensionality, optimization factors are added. For the intersection scenario, aiming at the challenge of reward sparsity caused by the scarcity of traffic signals and safety incentives, an additional reward mechanism is innovatively proposed to enrich the reward function. The experimental results demonstrate that the SHEMS significantly reduces fuel consumption. Specifically, the PPO, A2C, A3C, and DQN-based strategies achieved 7.52%, 5.29%, 9.6%, and 5.93% reductions, respectively. Taking the DQN algorithm as an example, the emissions of harmful gases CO, HC, PM and NOx are reduced by 18.3%, 14.23%, 16.94%, and 20.9%, respectively, after layering
STATE OF THE WASTEWATER TREATMENT SYSTEM IN SOUTHEASTERN SERBIA BY MUNICIPALITIES AND CITIES
Full text linkThis paper focuses on the state of wastewater treatment systems in Southeastern Serbia, specifically within the municipalities and cities of the Nišava, Toplica, Pirot, Jablanica and Pčinja districts. It provides a comprehensive overview of wastewater treatment systems in Europe and globally, offering a comparative perspective on Serbia's current status. This study conducts research and a comparative analysis using an indicator to monitor the state of wastewater treatment in the Republic of Serbia, across regions, and in cities and municipalities of Southeast Serbia, based on the most recent available data. Key results and findings are presented, followed by conclusions derived from the analysis, aiming to contribute to a deeper understanding of the challenges and opportunities in improving wastewater treatment systems in Southeastern Serbia
CRKVENA MUZIKA U NAPISIMA KOMPOZITORA SRĐANA JAĆIMOVIĆA
No full textThe paper is written with the idea of presenting the theoretical work of the renowned Serbian composer, pedagogue, and producer, Srđan Jaćimović (1960–2006), more specifically his relation to church music, with reference to his selected works: On the Differences in the Tradition of Chanting between Byzantium and Serbia (2021), On Authenticity in the Music of the Serbian Church (1992), and On Contemporary Interpretations of Byzantine Church Music (1993). The central part of this paper is dedicated to presenting the key features of church chants in Byzantium and Serbia, taking into account the scale system, texture, type of melodic movement, consideration of consonance and dissonance, treatment of liturgical text, and the attitude to 'progress' in music. Additionally, the paper presents the composer's understanding of the authenticity of music in the Serbian church, taking into consideration the circumstances that influenced its development, while in the discussion of contemporary interpretations of Byzantine church music, Jaćimović addressed the problems caused by the work of Western Byzantinists due to inadequate transcription. The aim of the paper is to provide a comprehensive overview of substantial views of the composer regarding various aspects of Byzantine and Serbian church music, with a particular emphasis on the anomalies present in the interpretation of Byzantine church music.Rad je napisan sa idejom da se predstavi teorijski rad poznatog srpskog kompozitora, pedagoga i producenta, Srđana Jaćimovića (1960–2006), odnosno njegov odnos prema crkvenoj muzici na osnovu izabranih radova: „O razlikama u tradiciji crkvenog pevanja Vizantije i Srbije” (2021), „O autentičnom u muzici srpske crkve” (1992) i „O savremenim interpretacijama muzike vizantijske crkve” (1993). Centralni deo rada posvećen je predstvaljanju vitalnih odlika crkvenog pevanja Vizantije i Srbije, koje uzima u obzir lestvični sistem, fakturu, tip melodijskog pokreta, razmatranje konsonance i disonance, tretman liturgijskog teksta i odnos prema ‛progresu’ u muzici. Pored toga, u radu se predstavlja i kompozitorovo shvatanje autentičnosti muzike u srpskoj crkvi, uz razmatranje okolnosti koje su uticale na njen razvojni put, dok u razmatranju savremene interpretacije muzike vizantijske crkve Jaćimović govori o problemima koji su uzrokovani radom zapadnih vizantologa usled neadekvatne transkripcije. Cilj rada jeste da se na jednom mestu ponudi prikaz najznačajnijih stavova kompozitora kada su u pitanju različiti aspekti vizantijske i srpske crkvene muzike, sa posebnim osvrtom na anomalije koje poseduje interpretacija muzike vizantijske crkve
PROMENE U PSIHOSOCIJALNOM FUNKCIONISANJU STUDENATA UNIVERZITETA IZAZVANE PANDEMIJOM COVID-19: PREPREKA I PRILIKA
No full textThe COVID-19 pandemic has caused numerous changes, both on a global level and in the lives of every individual, particularly affecting university students. This paper examines how students perceived the impact of the COVID-19 pandemic on their lives. Fifty-one university students participated in the research. Data were collected via an online questionnaire and analyzed using thematic analysis. Two primary themes with subthemes emerged from the analysis: theme Positive Changes (including subthemes Increased Awareness of Family Values; Idling without Remorse; Restarting Neglected Activities; Practical and Mental Self-Improvement) and theme Negative Changes (including subthemes Restricted Movement and Freedom; Diminished Opportunities for In-Person Social Engagement; Online Class-Related Boredom; Declining Interest in Studying; Empty Days). The obtained data indicate that the COVID-19 pandemic was perceived as significantly disrupting students' routines and social interactions while also providing room for personal development as an opportunity to function more optimally in different life domains. Based on these findings, the paper offers recommendations for supporting students in overcoming difficulties possibly caused by pandemics or events necessitating the transition to remote learning.Pandemija COVID-19 izazvala je brojne promene, kako na globalnom nivou, tako i u životima svakog pojedinca, pri čemu su studenti univerziteta bili posebno pogođeni. Ovaj rad istražuje kako su studenti percipirali uticaj pandemije COVID-19 na svoje živote. U istraživanju je učestvovao 51 student univerziteta. Podaci su prikupljeni putem onlajn upitnika i analizirani tematskom analizom. Analizom podataka izdvojene su dve glavne teme sa podtemama: tema Pozitivne promene (podteme: Povećana svest o porodičnim vrednostima; Lenčarenje bez griže savesti; Vraćanje zapostavljenim aktivnostima; Praktično i mentalno samousavršavanje) i tema Negativne promene (podteme: Ograničenost kretanja i slobode; Smanjene mogućnosti za lične socijalne interakcije; Dosada povezana sa onlajn nastavom; Opadanje interesovanja za učenje; Prazni dani). Dobijeni podaci ukazuju na to da je pandemija COVID-19 značajno narušila rutine i društvene interakcije studenata, ali je istovremeno otvorila prostor za lični razvoj i priliku za optimalnije funkcionisanje u različitim životnim domenima. Na osnovu ovih nalaza, rad nudi preporuke za podršku studentima u prevazilaženju poteškoća koje mogu nastati usled pandemije ili događaja koji zahtevaju prelazak na učenje na daljinu
UTICAJ RAZLIČITIH FAKTORA PREDIKCIJE NA REZULTATE U DISCIPLINI PRESKAKANJA PREPONA
No full textEven though its role in the development of equestrian sports has been confirmed, a small number of authors have conducted a thematic analyses of the interaction between errors and sports performance in the show jumping discipline. This may indicate that performance analysis is still insufficiently emphasized in equestrian sports, particularly in relation to sports performance. The aim of this study was to identify types of errors as predictors of total penalty points in a competition and to determine their predictive capacity as components of performance. A total of 7,285 jumping actions were analyzed during the “Balkan Championship 2022” across 512 starts. The identified errors (independent variables – predictors) included: obstacle knockdown (OP), stepping into water (SV), first refusal (PN), second refusal (DN), first closed circle (PZK), second closed circle (DZK), fall of the rider and/or horse (PJ/K), exceeding the allowed time (PDV), exceeding the maximum allowed time (PMDV), and jumping the wrong obstacle (PSP). Their impact was assessed on the total penalty points (UKP) (dependent variable). The data obtained were processed using the SPSS 19 statistical package. Descriptive statistical parameters were calculated, followed by Pearson’s correlation analysis to determine the strength and direction of existing correlations. Multiple regression analysis was then applied to assess the influence of the independent variables (errors) on the dependent variable (UKP). The results of this model indicate that the cumulative effect of the predictors significantly (Sig=0.000ª) explains 88% of the total variance in UKP. With statistical significance confirmed for all independent variables (Sig≤0.027), their individual positive correlations with the dependent variable ranged from r=0.85 to r=0.774. Individually, all predictors exerted a differentiated yet statistically significant influence, with statistical significance (Sig=0.000), with effects ranging from minimal [PDV (t=3.708; Sig=0.000; β=0.063; 0.34%)] to maximal [DN (t=19.889; Sig=0.000; β=0.424; 9.54%)]. It can be concluded that all predictors, when viewed individually, are significant, while they simultaneously exert a cumulative significant influence on UKP. Furthermore, each predictor individually exerts a statistically significant predictive effect on UKP. This analysis provides valuable data for all stakeholders and may support the development and implementation of more effective competition strategies aimed at improving performance.I pored toga što je uloga konjičkog sporta u njegovom razvoju potvrđena, mali broj autora je sproveo tematsku analizu interakcije između grešaka i sportske uspešnosti u disciplini preskakanja prepona, što može ukazivati na nedovoljnu zastupljenost analize performansi u konjičkom sportu, sa posebnim osvrtom na sportsku uspešnost. Cilj ove studije bio je da se identifikuju tipovi grešaka kao prediktori ukupnog broja kaznenih poena na takmičenju i da se utvrdi njihova prediktivna moć u okviru ukupne sportske performanse. Ukupno je analizirano 7.285 skokova tokom „Balkanskog prvenstva 2022“, u okviru 512 startova, pri čemu su analizirane greške (nezavisne varijable – prediktori) obuhvatile: rušenje prepreke (OP), gaženje vode (SV), prvo odbijanje (PN), drugo odbijanje (DN), prvi zatvoreni krug (PZK), drugi zatvoreni krug (DZK), pad jahača i/ili konja (PJ/K), prekoračenje dozvoljenog vremena (PDV), prekoračenje maksimalno dozvoljenog vremena (PMDV), kao i skakanje pogrešne prepreke (PSP), i njihov uticaj na ukupan broj kaznenih poena (UKP) (zavisna varijabla). Dobijeni podaci obrađeni su statističkim paketom SPSS 19. Izračunati su deskriptivni statistički parametri, zatim je sprovedena Pirsonova korelaciona analiza radi utvrđivanja postojanja međuzavisnosti, kao i višestruka regresiona analiza sa ciljem procene uticaja nezavisnih varijabli (grešaka) na zavisnu varijablu (UKP). Rezultati dobijeni ovim modelom ukazuju da kumulativni efekat prediktora statistički značajno (Sig=0.000ª) objašnjava 88% ukupne varijanse UKP. Sa potvrđenom značajnošću svih nezavisnih varijabli (Sig≤0.027), izračunate su njihove individualne pozitivne korelacije sa zavisnom varijablom, koje se kreću u rasponu od r=0.85 do r=0.774. Svi prediktori imaju individualni, diferencirani prediktivni uticaj, uz statističku značajnost (Sig=0.000), u rasponu od minimalnog efekta [PDV (t=3.708; Sig=0.000; β=0.063; 0.34%)] do maksimalnog efekta [DN (t=19.889; Sig=0.000; β=0.424; 9.54%)]. Može se zaključiti da su svi prediktori, posmatrani pojedinačno, statistički značajni, dok istovremeno ostvaruju i kumulativno značajan uticaj na UKP. Pored toga, svaki prediktor zasebno pokazuje statistički značajnu prediktivnu moć u odnosu na UKP. Ova analiza može pružiti korisne informacije svim akterima u cilju razvijanja i implementacije efikasnijih takmičarskih strategija usmerenih ka unapređenju sportske uspešnosti