Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651

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  • Article
    Dielectric and Thermal Properties of the Ferroelectric NH4HSO4 Close to Phase Transitions
    (Elsevier, 2025) Kiraci, A.; Yurtseven, H.
    This work gives the analysis of the dielectric and thermal properties close to the second order and first order types of ferroelectric-paraelectric phase transitions in ferroelectrics, in particular, NH4HSO4. The power-law formula is used by adapting the Kouvel-Fisher (KF) method describing the magnetization (M) and magnetic susceptibility (chi M) in the case of the spontaneous polarization (PS) and the dielectric constant (& varepsilon;), respectively, in ferroelectric systems. Similar treatment is performed to describe the heat capacity (CP) and the thermal expansivity (proportional to P) close to the phase transitions in NH4HSO4. We show that the variations of PS and & varepsilon; with the temperature near the upper Curie point (TC1 = 270 K) exhibit linearity for the second order transition in NH4HSO4. A linear variation is also obtained between the CP and proportional to P with the temperature close to the lower Curie point (TC2 = 160 K) for the first order transition in this crystal. Experimental data are used from the literature for our analysis. Our approach given here to describe dielectric and thermal properties of NH4HSO4 close to the Curie points, can be applied to some other ferroelectric materials.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Artificial Neural Networks for Predicted Bending Properties of Additively Manufactured Pyramidal Lattice Truss Core Sandwich Structures
    (Elsevier, 2025) Karagozlu, Cem Onat; Ayli, Ece; Tanabi, Hamed; Sabuncuoglu, Baris
    An Artificial Neural Network (ANN) model is developed to predict the mechanical behavior of pyramidal lattice truss core sandwich structures under bending load. The development process aims to optimize material use, enhance structural efficiency, and reduce analysis time for the developed ANN model. Key phases include specimen fabrication via additive manufacturing, experimental testing in four-point bending, and validation of the finite element model (FEM). Experimental tests on five specimens validated FEM simulations with a 4.5 % error rate. The ANN, trained on FEM data, accurately predicts reaction forces and stress components (sigma,, sigma 2, tau,2). Comparison of training algorithms (LM, Levenberg-Marquardt, BR, Bayesian Regularization, SCG, Scaled Conjugate Gradient) highlights LM's superior performance in convergence and MSE reduction (max. MSE value: 2.287), while BRexcels in generalization and robustness. Scaled Conjugate Gradient's performance was lower than the others. The ANN demonstrates high accuracy within the training range but shows limitations in extrapolation. Overall, this ANN model offers engineers a rapid and precise tool for predicting the mechanical behavior of these sandwich structures, reducing reliance on time-consuming FEM simulations and facilitating efficient design optimization across various engineering applications.
  • Article
    Htstego: a Halftone Steganography Utility
    (Elsevier, 2024) Ciftci, Efe; Suemer, Emre; Sümer, Emre
    Steganography, the art and science of concealing secret information within seemingly innocent cover media, is crucial in secure information exchange and data protection. This work introduces a free and open -source steganography software for concealing plaintext payloads within halftone images, accompanied by a payload extraction utility to retrieve payloads from images generated using the featured utility. The utility can compress the payload before hiding and generate color and binary stego halftone images via a selection of methods, including ordered dithering and error diffusion, with support for custom-defined error diffusion kernels. A distinguishing feature of the utility is the distribution of payloads across multiple outputs to enhance payload security against unauthorized extraction and eliminate the necessity of the original image during payload extraction. Additionally, the utility provides quantitative assessments of image quality for the produced images, which is used in this paper to showcase the efficiency of the featured method.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Mitoseg: Mitochondria Segmentation Tool
    (Elsevier, 2025) Tasel, Faris Serdar; Ciftci, Efe
    Recent studies suggest a potential link between the physical structure of mitochondria and neurodegenerative diseases. With advances in Electron Microscopy techniques, it has become possible to visualize the boundary and cristae structures of mitochondria in detail. Segmenting mitochondria from microscopy images remains challenging due to image quality and complex morphology of mitochondria, including cristae and the other subcellular structures. It is crucial to automatically segment mitochondria from images exhibiting different mitochondrial boundary and crista characteristics to investigate the relationship between mitochondria and diseases. In this paper, we present a software solution for mitochondrial segmentation using an automatic validation scheme based on the general physical properties of mitochondria, highlighting boundaries in electron microscopy tomography images and generating corresponding 3D meshes. These capabilities help researchers conduct further investigations into mitochondrial morphology and explore its role in the mechanisms of neurodegenerative diseases.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 4
    Adaptive Optics Compensation of M-Ary Pulse Position Modulated Communication Systems in Anisotropic Non-Kolmogorov Turbulent Atmosphere
    (Elsevier, 2021) Ata, Yalcin; Baykal, Yahya; Gokce, Muhsin Caner
    Adaptive optics compensation effect on the performance of an optical wireless communication system (OWC) employing M-ary pulse position modulation (PPM) scheme in anisotropic non-Kolmogorov turbulent atmosphere is investigated. Avalanche photodetector (APD) is used at the receiver side and log-normal channel that models the weak turbulence conditions is utilized. Anisotropy, generally resulting in better performance in OWC systems operating in the turbulent medium, combined with the adaptive optics applications will enhance the bit-error-rate (BER) of the OWC systems significantly. Results are obtained depending on various parameters for both the turbulent atmosphere and the receiver. Our work gives OWC system designers a perspective to optimize their design.
  • Correction
    Citation - WoS: 3
    Citation - Scopus: 5
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Exploring the Linear and Nonlinear Optical Behavior of (Tlins2)0.75 Insights From Ellipsometry Measurements
    (Elsevier, 2023) Guler, I.; Gasanly, N.; Isik, M.
    The search for layered structured new semiconductor materials with remarkable optical properties has become a driving force, especially for materials science. Tl2In2S3Se [(TlInS2)0.75(TlInSe2)0.25], a fascinating compound, holds great promise for advanced photonic and optoelectronic applications. In the present study, the linear and nonlinear optical properties of Tl2In2S3Se layered single crystals were studied by ellipsometry measurements. The variation of refractive index, extinction coefficient, absorption coefficient and skin depth with energy were investigated. Applying the derivative analysis technique to the absorption spectrum, indirect bandgap was found as 2.19 eV. The refractive index data was analyzed considering single-effective-oscillator model. The lattice dielectric constant, plasma frequency, carrier density to the effective mass ratio and zero-frequency refractive index were found. Moreover, the change in optical conductivity with energy yielded to determine the direct bandgap as 2.40 eV. The optical parameters of nonlinear refractive index, first-and third-order nonlinear susceptibilities were also reported.
  • Article
    Citation - WoS: 62
    Citation - Scopus: 70
    The Novel Augmented Fermatean Mcdm Perspectives for Identifying the Optimal Renewable Energy Power Plant Location
    (Elsevier, 2022) Parthasarathy, Thirumalai Nallasivan; Pragathi, Subramaniam; Shanmugam, Ponnan; Baleanu, Dumitru; Ahmadian, Ali; Kang, Daekook; Narayanamoorthy, Samayan
    The Fermatean fuzzy set has been authorized as a suitable tool for the uncertainty and vagueness of information by augmenting the spatial space of acceptance membership and non-acceptance membership degrees of both intuitionistic and Pythagorean fuzzy sets. Solar energy does not emit any hazardous gases into the atmosphere, making it one of the most effective strategies to reduce global warming in the environment. Under a variety of circumstances, finding a spot for a photovoltaic solar power plant might be difficult. As a result, we experiment with multi-criteria decision-making (MCDM) techniques. We presented a hybrid technique based on the PV-SPSS method based on the Removal Effects of Criteria (MEREC) and Multiple Objective Optimization on the Basis of Ratio Analysis with Full Multiplicative Form (MULTIMOORA) analysis. The MEREC approach is used to calculate the weightage of each attribute, and MULTIMOORA is used to find the ranking of the alternatives. Also, a new rectified generalized score function determines the score value of FFSs. Culmination: the validity of the result is assessed by implementing the existing MCDM approaches and by changing the criterion weight.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 4
    Solar Radiation Effect on Pcm Performance in the Building Applications: the Collector Energy-Saving Potential Using Cf-Mwcnts and Cf-Gnps
    (Elsevier, 2022) Sajadi, S. Mohammad; Liu, Fenghua; Alrabaiah, Hussam; Aldabesh, Abdulmajeed; Baleanu, Dumitru; Chen, Liangliang; Mohammad Sajadi, S.
    In this study, a hot and desert location with an annual temperature of 27.1 ? and a very high radiation intensity of 2143 kWh/m(2), a solar system (ES) was approved to provide building cooling necessities. The cooling system, by connecting to the solar system, supplied a part of its required energy. The outer layer of the building walls was equipped with PCM (SP-21EK) with a melting point of 21-23 and latent heat of 170 kJ/kg. In the solar system, water was filled to absorb energy and then a combination of CF-MWCNTs and CF-GNPs nanoparticles were injected to the solar system to improve effectiveness. In July, when the radiation intensity was very high, the combination of PCM and SC condensed energy consumption (EC) by up to 46.48%. The presence of CF-MWCNTs and CF-GNPs at 0.1 wt% was useful in all conditions (2, 3 and 4 lit/min). In this case, the EC reduction was in the range of 360 to 1026 kWh. At lower concentrations, the nanoparticles not only were not worthwhile, in some cases increased EC by 937 kWh.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 13
    Molecular Dynamic Approach To Predict Thermo-Mechanical Properties of Poly(Butylene Terephthalate)/Caco3 Nanocomposites
    (Elsevier, 2021) Boga, Cem; Akar, Samet; Pashmforoush, Farzad; Seyedzavvar, Mirsadegh
    Thermo-mechanical properties of poly(butylene terephthalate) polymer reinforced with carbonate calcium nanoparticles have been investigated using molecular dynamics simulations. Detailed analyses have been conducted on the effects of nanofiller content, at concentration levels of 0-7 wt%, on the mechanical properties of PBT, i.e. Young's modulus, Poisson's ratio and shear modulus. Thermal properties, including thermal conductivity and glass transition temperature, have been determined using Perl scripts developed based on nonequilibrium molecular dynamics and a high temperature annealing procedure, respectively. Experiments have been performed to verify the accuracy of the results of MD simulations. The CaCO3/PBT nanocomposites were synthesized using melt blending and mold injection techniques. The uniaxial tensile test, thermal conductivity, differential scanning calorimetry and x-ray diffraction spectroscopy measurements were conducted to quantify the thermo-mechanical properties of such nanocomposites experimentally. The results showed significant improvements in the mechanical properties by addition of CaCO3 nanoparticles due to strong binding between rigid particles and PBT polymer and high nucleation effects of nanoparticles on the matrix. Thermal conductivity and glass transition temperature of nanocomposites represented a consistent increase with the ratio of CaCO3 nanoparticles up to 5 wt% with an enhancement of 38% and 36% with respect to that of pure PBT, respectively.