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Citation - WoS: 1
Citation - Scopus: 3
Spectral Approach To Derive the Representation Formulae for Solutions of the Wave Equation
(Hindawi Publishing Corporation, 2012) Guseinov, Gusein Sh.
Using spectral properties of the Laplace operator and some structural formula for rapidly decreasing functions of the Laplace operator, we offer a novel method to derive explicit formulae for solutions to the Cauchy problem for classical wave equation in arbitrary dimensions. Among them are the well-known d'Alembert, Poisson, and Kirchhoff representation formulae in low space dimensions.
Citation - WoS: 29
Citation - Scopus: 36
Massive Mimo Systems for 5g: a Systematic Mapping Study on Antenna Design Challenges and Channel Estimation Open Issues
(inst Engineering Technology-iet, 2021) Benzaghta, Mohamed; Rabie, Khaled M.
The next generation of mobile networks (5G) is expected to achieve high data rates, reduce latency, as well as improve the spectral and energy efficiency of wireless communication systems. Several technologies are being explored to be used in 5G systems. One of the main promising technologies that is seen to be the enabler of 5G is massive multiple-input multiple-output (mMIMO) systems. Numerous studies have indicated the utility of mMIMO in upcoming wireless networks. However, there are several challenges that needs to be unravelled. In this paper, the latest progress of research on challenges in mMIMO systems is tracked, in the context of mutual coupling, antenna selection, pilot contamination and feedback overhead. The results of a systematic mapping study performed on 63 selected primary studies, published between the year 2017 till the second quarter of 2020, are presented. The main objective of this secondary study is to identify the challenges regarding antenna design and channel estimation, give an overview on the state-of-the-art solutions proposed in the literature, and finally, discuss emerging open research issues that need to be considered before the implementation of mMIMO systems in 5G networks.
Citation - WoS: 1
Citation - Scopus: 1
Synthesis and Characterization of New Dithienosilole Based Copolymers
(Electrochemical Soc inc, 2016) Karabay, Lutfiye Canan; Al-Jumaili, Mohammed; Cihaner, Atilla
2-Ethylhexyl substituted dithienosilole based soluble polymers including thiophene (1) and bithiophene (2) units were synthesized via Stille coupling reaction. The presence of 2-ethylhexyl substituents on the silole ring gave solubility property to the polymers in common solvents. According to gel permeation chromatography measurements, the weight average molecular weights of the polymers 1 and 2 were found to be as 70,977 with a polydispersity index of 2.30 and 110,439 with a PDI of 1.42, respectively. Fluorescent polymers in toluene solution have maximum emisssion bands at 634 nm for the polymer 1 and 613 nm for the polymer 2. Chemical and electrochemical doping of the polymers in the solution and in the film forms were monitored by using ultraviolet-visible spectroscopic technique. The polymers exhibited chromic (chemochromic and electrochromic) properties. While the colors of the neutral polymer films are purple for the polymer 1 and reddish brown for the polymer 2, both polymers are transparent sky blue at their oxidized states. The bandgaps of polymers in film forms were calculated as 1.81 eV for the polymer 1 and 1.92 eV for the polymer 2. Also, electrochromic device applications of the polymers were done. Electrochemical and optical behaviors of the polymers demonstrated that they can be good candidates for optoelectronic applications. (C) 2016 The Electrochemical Society. All rights reserved.
Citation - WoS: 4
Citation - Scopus: 5
Thermoluminescence Properties of Tl₂ga_{2< Layered Single Crystals}
(Amer inst Physics, 2013) Delice, S.; Isik, M.; Bulur, E.; Gasanly, N. M.
The trap center(s) in Tl2Ga2S3Se single crystals has been investigated from thermoluminescence (TL) measurements in the temperature range of 10-300 K. Curve fitting, initial rise, and peak shape methods were applied to observed TL glow curve to evaluate the activation energy, capture cross section, and attempt-to-escape frequency of the trap center. One trapping center has been revealed with activation energy of 16 meV. Moreover, the characteristics of trap distribution have been studied using an experimental technique based on different illumination temperature. An increase of activation energy from 16 to 58 meV was revealed for the applied illumination temperature range of 10-25K. (C) 2013 AIP Publishing LLC.
Citation - WoS: 11
Citation - Scopus: 12
Structural and Temperature-Tuned Bandgap Characteristics of Thermally Evaporated β-in_{2< Thin Films}
(Springer, 2021) Surucu, O.; Isik, M.; Terlemezoglu, M.; Gasanly, N. M.; Parlak, M.
In2S3 is one of the attractive compounds taking remarkable interest in optoelectronic device applications. The present study reports the structural and optical characteristics of thermally evaporated beta-In2S3 thin films. The crystalline structure of the thin films was found as cubic taking into account the observed diffraction peaks in the X-ray diffraction pattern. The atomic compositional ratio of constituent elements was obtained as consistent with chemical formula of In2S3. Three peaks around 275, 309 and 369 cm(-1) were observed in the Raman spectrum. Temperature-tuned bandgap energy characteristics of the In2S3 thin films were revealed from the investigation of transmittance spectra obtained at various temperatures between 10 and 300 K. The analyses of the transmittance spectra indicated that direct bandgap energy of the In2S3 thin films decreases from 2.40 eV (at 10 K) to 2.37 eV (at 300 K) with the increase of measurement temperature. The bandgap energy vs. temperature relation was investigated by means of Varshni optical model. The fitting of the experimental data under the light of theoretical expression revealed the absolute zero bandgap energy, the rate of change of bandgap energy and Debye temperature.
Citation - WoS: 6
Citation - Scopus: 5
The Effect of Zn Concentration on the Structural and Optical Properties of Cd_1-xzn_{x< Nanostructured Thin Films}
(Springer, 2021) Isik, M.; Terlemezoglu, M.; Isik, S.; Erturk, K.; Gasanly, N. M.
The structural and optical properties of electrodeposited Cd1-xZnxS nanostructured thin films were investigated in the present paper for compositions of x = 0, 0.03, 0.06 and 0.09. X-ray diffraction patterns of the deposited thin films consisted of diffraction peaks related to cubic crystal lattice. The atomic compositional ratios were determined by performing energy dispersive spectroscopy measurements. Scanning electron microscopy images indicated that deposited thin films have nanostructured forms. Raman spectra of the Cd1-xZnxS thin films exhibited two vibrational modes associated with longitudinal optical mode and its first overtone. Transmission measurements were performed on the deposited thin films to get their band gap energies. It was seen from the analyses of absorption coefficient that band gap energy of Cd1-xZnxS thin films increases almost linearly from 2.40 to 2.51 eV as the composition was increased from x = 0 to x = 0.09.
Citation - WoS: 7
Citation - Scopus: 7
Surface Plasmon Resonance Aptasensor for Soluble Icam-1 Protein in Blood Samples
(Royal Soc Chemistry, 2022) Dursun, Ali Dogan; Dogan, Soner; Kavruk, Murat; Tasbasi, B. Busra; Sudagidan, Mert; Yilmaz, M. Deniz; Tuna, Bilge G.
Intercellular Adhesion Molecule-1 (ICAM-1) is considered to be a cancer biomarker in the assessment of metastatic potential in patients and an early indicator of atherosclerosis. A labelless biosensor based on the surface plasmon resonance (SPR) signal from the specific affinity interaction of an aptamer and a soluble ICAM-1 protein was developed for blood samples. The developed aptasensor provided real-time information on the concentration of the ICAM-1 protein in blood when integrated to a purification step based on a magnetic pull-down separation. The SPR aptasensor was highly specific with a limit of detection of 1.4/0.2 ng ml(-1), which was achieved through aptamer-functionalized silica-coated magnetic nanoparticles.
Citation - WoS: 43
Coupled Fixed Points for Meir-Keeler Contractions in Ordered Partial Metric Spaces
(Hindawi Ltd, 2012) Abdeljawad, Thabet; Aydi, Hassen; Karapinar, Erdal
In this paper, we prove the existence and uniqueness of a new Meir-Keeler type coupled fixed point theorem for two mappings F : X x X -> X and g : X -> X on a partially ordered partial metric space. We present an application to illustrate our obtained results. Further, we remark that the metric case of our results proved recently in Gordji et al. (2012) have gaps. Therefore, our results revise and generalize some of those presented in Gordji et al. (2012)
Citation - WoS: 42
Citation - Scopus: 41
Analysis of Forward and Reverse Biased Current-Voltage Characteristics of Al/Al_{2< Schottky Diode With Atomic Layer Deposited Al₂o_{3< Thin Film Interlayer}}
(Springer, 2019) Gullu, H. H.; Yildiz, D. E.
The dark current-voltage (I-V) characteristics of Al/Al2O3/n-Si Schottky diode are investigated in a wide temperature range of 260-360 K. The diode shows four orders of magnitude rectification. In forward and reverse bias regions, the temperature-dependent I-Vcharacteristics are detailed in terms of diode parameters and dominant conduction mechanisms. Due to the existence of Al2O3 film layer and series resistance in the diode structure, current flow under the forward bias is observed in a deviation from pure exponential characteristics. The diode parameters are estimated from thermionic emission model with non-unity ideality factor, and this non-ideal behavior is resulted in the ideality factors greater than two. In addition to these values, zero-bias barrier height is found to be strongly temperature dependent, and this variation indicates a presence of inhomogeneties in the barrier according to Gaussian distribution (GD) approximation. This fact is investigated plotting characteristic plot of this model and by extracting mean barrier height with its standard deviation. In order to complete the work on the forward I-V region, the carrier transport characteristics of the diode are explained on the basis of thermionic emission mechanism with a GD of the harrier heights. In accordance with this approximation, the conventional Richardson plot exhibits non-linearity behavior and modified current relation based on GD model is used to calculate mean barrier height and Richardson constant. In addition, the values of parasitic resistances are determined using Ohm's law as a function of temperature for all bias voltage spectra. In the reverse bias region, Poole-Frenkel effect is found to be dominant on the conduction associated with the barrier lowering, and barrier height in the emission process from the trapped states, and high-frequency dielectric constant of Al2O3 film layer is calculated.
The Impact of Socioeconomic Status on Clinical Parameters in Female Psa Patients
(Clinical & Exper Rheumatology, 2021) Tekeoglu, I.; Nas, K.; Keskin, Y.; Kilic, E.; Sargin, B.; Kasman, Acer S.; Tuncer, T.
[No Abstract Available]

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