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Now showing 1 - 10 of 14
  • Article
    On the Lupas q-transform of Unbounded Functions
    (Walter de Gruyter Gmbh, 2023) Ostrovska, Sofiya; Turan, Mehmet
    The Lupa , s q-transform comes out naturally in the study of the Lupa , s q-analogue of the Bernstein operator. It is closely related to the Heine q-distribution which has a numerous application in q-boson operator calculus and to the Valiron method of summation for divergent series. In this paper, the Lupa , s q-transform (lambda(q)f)(z), q is an element of (0, 1), of unbounded functions is considered in distinction to the previous researches, where only the case f is an element of C[0, 1] have been investigated. First, the condition for a function to possess the Lupa , s q-transform is presented. Also, results concerning the connection between growth rate of the function f (t) as t -> 1(-) and the growth of its Lupa , s q-transform (lambda(q)f)(z) as z -> infinity are established. (c) 2023 Mathematical Institute Slovak Academy of Sciences
  • Article
    Citation - WoS: 1
    Citation - Scopus: 2
    Existence of Solutions for Odd-Order Multi-Point Impulsive Boundary Value Problems on Time Scales
    (Walter de Gruyter Gmbh, 2022) Georgiev, Svetlin G.; Akgol, Sibel Dogru; Kus, Murat Eymen
    Using a fixed point theorem due to Schaefer, the existence of solutions for an odd-order m-point impulsive boundary value problem on time scales is obtained. The problem considered is of general form, where both the differential equation and the impulse effects are nonlinear. Illustrative examples are provided.
  • Article
    Citation - WoS: 9
    Citation - Scopus: 9
    Existence and Uniqueness of Best Proximity Points Under Rational Contractivity Conditions
    (Walter de Gruyter Gmbh, 2016) Karapinar, Erdal; Roldan-Lopez-de-Hierro, Antonio-Francisco; Sadarangani, Kishin
    The main aim of this paper is to present some theorems in order to guarantee existence and uniqueness of best proximity points under rational contractivity conditions using very general test functions. To illustrate the variety of possible test functions, we include some examples of pairs of functions which are included in innovative papers published in the last years. As a consequence, we prove that our results unify and extend some recent results in this field.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    On the q-bernstein Polynomials of the Logarithmic Function in the Case q > 1
    (Walter de Gruyter Gmbh, 2016) Ostrovska, Sofiya
    The q-Bernstein basis used to construct the q-Bernstein polynomials is an extension of the Bernstein basis related to the q-binomial probability distribution. This distribution plays a profound role in the q-boson operator calculus. In the case q > 1, q-Bernstein basic polynomials on [0, 1] combine the fast increase in magnitude with sign oscillations. This seriously complicates the study of q-Bernstein polynomials in the case of q > 1. The aim of this paper is to present new results related to the q-Bernstein polynomials B-n,B- q of discontinuous functions in the case q > 1. The behavior of polynomials B-n,B- q(f; x) for functions f possessing a logarithmic singularity at 0 has been examined. (C) 2016 Mathematical Institute Slovak Academy of Sciences
  • Review
    Citation - WoS: 22
    Citation - Scopus: 36
    Principles of Reverse Electrodialysis and Development of Integrated-Based System for Power Generation and Water Treatment: a Review
    (Walter de Gruyter Gmbh, 2022) Othman, Nur Hidayati; Kabay, Nalan; Guler, Enver
    Reverse electrodialysis (RED) is among the evolving membrane-based processes available for energy harvesting by mixing water with different salinities. The chemical potential difference causes the movement of cations and anions in opposite directions that can then be transformed into the electrical current at the electrodes by redox reactions. Although several works have shown the possibilities of achieving high power densities through the RED system, the transformation to the industrial-scale stacks remains a challenge particularly in understanding the correlation between ion-exchange membranes (IEMs) and the operating conditions. This work provides an overview of the RED system including its development and modifications of IEM utilized in the RED system. The effects of modified membranes particularly on the psychochemical properties of the membranes and the effects of numerous operating variables are discussed. The prospects of combining the RED system with other technologies such as reverse osmosis, electrodialysis, membrane distillation, heat engine, microbial fuel cell), and flow battery have been summarized based on open-loop and closed-loop configurations. This review attempts to explain the development and prospect of RED technology for salinity gradient power production and further elucidate the integrated RED system as a promising way to harvest energy while reducing the impact of liquid waste disposal on the environment.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    On the Rate of Convergence for the q-durrmeyer Polynomials in Complex Domains
    (Walter de Gruyter Gmbh, 2024) Gurel, Ovgu; Ostrovska, Sofiya; Turan, Mehmet
    The q-Durrmeyer polynomials are one of the popular q-versions of the classical operators of approximation theory. They have been studied from different points of view by a number of researchers. The aim of this work is to estimate the rate of convergence for the sequence of the q-Durrmeyer polynomials in the case 0 < q < 1. It is proved that for any compact set D subset of C, the rate of convergence is O(q(n)) as n -> infinity. The sharpness of the obtained result is demonstrated.
  • Article
    Citation - WoS: 104
    Citation - Scopus: 109
    On Generalized Α - Ψ-Geraghty Contractions on b-metric Spaces
    (Walter de Gruyter Gmbh, 2020) Afshari, Hojjat; Aydi, Hassen; Karapinar, Erdal
    In this paper, we consider generalized alpha - psi-Geraghty contractive type mappings and investigate the existence and uniqueness of a fixed point for mappings involving such contractions. In particular, we extend, improve and generalize some earlier results in the literature on this topic. An application concerning the existence of an integral equation is also considered to illustrate the novelty of the main result.
  • Article
    Uncorrelatedness Sets of Discrete Random Variables Via Vandermonde-Type Determinants
    (Walter de Gruyter Gmbh, 2019) Turan, Mehmet; Ostrovska, Sofiya; Ozban, Ahmet Yasar
    Given random variables X and Y having finite moments of all orders, their uncorrelatedness set is defined as the set of all pairs (j, k) is an element of N-2; for which X-j and Y-kappa are uncorrelated. It is known that, broadly put, any subset of N-2 can serve as an uncorrelatedness set. This claim is no longer valid for random variables with prescribed distributions, in which case the need arises so as to identify the possible uncorrelatedness sets. This paper studies the uncorrelatedness sets for positive random variables uniformly distributed on three points. Some general features of these sets are derived. Two related Vandermonde-type determinants are examined and applied to describe uncorrelatedness sets in some special cases. (C) 2019 Mathematical Institute Slovak Academy of Sciences
  • Article
    Citation - WoS: 14
    Citation - Scopus: 13
    SOME FIXED POINT THEOREMS IN BRANCIARI METRIC SPACES
    (Walter de Gruyter Gmbh, 2017) Berzig, Maher; Karapinar, Erdal; Roldan-Lopez-de-Hierro, Antonio F.
    In this paper, we investigate the existence and uniqueness of a fixed point of certain contraction via auxiliary functions in the context of complete Branciari metric spaces endowed with a transitive binary relation. Our results unify and extend some existing fixed point results in the related literature.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Impact Behavior of Sandwich Composites With S2-glass/Epoxy and PVC Foam Under Low Velocity Loading
    (Walter de Gruyter Gmbh, 2025) Karakuzu, Ramazan; Sarioglu, Rifat; Kandas, Halis
    The purpose of this research is to examine the absorbed energy, resistance to impact load of sandwich composite, and power exercised by impactor, experimentally. Therefore, low velocity impact tests were performed at three different energy levels for two distinct noses on sandwich composite with a PVC core and varying amounts of S2-glass layers. The vacuum-assisted resin infusion method (VARIM) was used to manufacture sandwich composites. S2-glass fabric with an areal density of 190 gm-2 and polyvinyl chloride (PVC) core material with a thickness of 10 mm were utilized. For every face sheet material, three distinct layer numbers of S2-glass fabrics were used. It is seen that composites exposed to flat impactors absorb considerably more energy than hemispherical ones.