Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Gul, Muhammet(82)
- Akkurt, Nevzat(67)
- Güler, Ömer(66)
- Baskonus, Haci Mehmet(62)
- Bulut, Hasan(60)
- Tekin, H.O.(52)
- ALMisned, Ghada(49)
- Yucesan, Melih(43)
- Yildirim, Numan(42)
- Yildirim, Nuran Cikcikoglu(38)
- Paksoy, Mehmet Yavuz(36)
- Serdar, Osman(36)
- Zengin, Gokhan(36)
- Ince, Muharrem(34)
- Celik, Erkan(33)
- Benzer, Fulya(32)
- Kocabaş, Mehmet(30)
- Sulaiman, Tukur Abdulkadir(30)
- Tanyol, Mehtap(29)
- Yildirim, Ozal(28)
- Aslan, Naim(26)
- Kök, Mediha(26)
- Özkul, İskender(26)
- Ates, Mehmet(25)
- Danabas, Durali(25)
- Kutluyer, Filiz(25)
- Can, Erkan(24)
- Kutlu, Banu(23)
- Onat, Onur(23)
- Demir, Veysel(22)
- Erten, Fusun(22)
- Guler, Omer(22)
- Say, Yakup(22)
- Güler, Seval Hale(21)
- Yaman, Mehmet(21)
- Baykal, Duygu Sen(20)
- Sançar, Taylan(20)
- Susam, Selim Orhun(20)
- Cakilcioglu, Ugur(19)
- Orhan, Cemal(19)
Yayınlar
- MakaleYalnız künye2020Scopus SJRQ1Impact of mechanical properties of historical masonry bridges on fundamental vibration frequency
Onat, Onur
The fundamental frequency of a historical monument like a masonry bridge or any other structure provides a better and detailed seismic assessment of its demand to provide protection against unexpected seismic ground motion. On this basis, this paper aims to develop an empirical formulation to fit the ambient vibration frequency of historical masonry bridges using a nonlinear regression model. For this purpose, data series were collected from the literature especially focused on both ambient vibration measurement and finite element models of historical masonry bridges modeled on a full scale to get the first global natural frequency. The first approach is to forecast the natural vibration frequency by using only physical characteristics of the historical masonry bridges obtained from the literature-based experimental ambient vibration frequency data. The second approach consists of forecasting the first natural vibration frequency considering the unit weight and elasticity modulus of the dominant construction material based on the homogenization approach. In addition to mechanical characteristics, physical properties of historical masonry bridges were used, such as the length, height, width, and Main Arch Span (MAS) length of the masonry bridge, to predict the first natural vibration frequency. Among the proposed equations, a maximum accuracy of 58% was reached with the literature-based experimental approach. Moreover, an empirical formulation with 81% accuracy was proposed by using both physical characteristics and mechanical properties of the bridges on the basis of finite element model results. Also, this study highlights that this accuracy decreases to 35% if the modulus of elasticity and unit weight are ignored. In addition, the developed formulations are compared with other empirical formulations using the Mean Square Error (MSE), as a measure of the average of the squares of the errors. Consequently, the smallest MSE value of 1.95 was obtained with the proposed equation, whose accuracy was 81% in this study.
AtıfScopus17WoS19OpenAlex21
İncele - MakaleYalnız künye2020Scopus SJRQ1A deep convolutional neural network model for automated identification of abnormal EEG signals
Yıldırım, Özal; Baloglu, Ulas Baran; Acharya, U. Rajendra
Electroencephalogram (EEG) is widely used to monitor the brain activities. The manual examination of these signals by experts is strenuous and time consuming. Hence, machine learning techniques can be used to improve the accuracy of detection. Nowadays, deep learning methodologies have been used in medical field to diagnose the health conditions precisely and aid the clinicians. In this study, a new deep one-dimensional convolutional neural network (1D CNN) model is proposed for the automatic recognition of normal and abnormal EEG signals. The proposed model is a complete end-to-end structure which classifies the EEG signals without requiring any feature extraction. In this study, we have used the EEG signals from temporal to occipital (T5–O1) single channel obtained from Temple University Hospital EEG Abnormal Corpus (v2.0.0) EEG dataset to develop the 1D CNN model. Our developed model has yielded the classification error rate of 20.66% in classifying the normal and abnormal EEG signals.
AtıfScopus164OpenAlex211İncele - MakaleAçık Erişim2020Scopus SJRQ2New national and regional bryophyte records, 63
Ellis, L.T.; Afonina, O.M.; Czernyadjeva, I.V.; Konoreva, L.A.; Potemkin, A.D.; Kotkova, V.M.; Alataş, M.; Blom, H.H.; Boiko, M.; Cabral, R.A.
AtıfScopus21OpenAlex23İncele - MakaleYalnız künye2020Scopus SJRQ2Empirical modeling between degree days and optimum insulation thickness for external wall
Kallioğlu, Mehmet Ali; Ercan, Umut; Avcı, Ali Serkan; Fidan, Cihad; Karakaya, Hakan
Insulating is the most effective method that is used to save energy in buildings. Samples from cities from different climatic zones from TS 825 (Turkey) first. Optimum insulation thickness (xopt) analysis is based on two types of insulating and four different fuels (natural gas, coal, fuel oil and electric) of related cities. Cost accounts, payback period and CO2-SO2 emission calculations were performed based on these analyses. Second of all, the relationship between a number of degree day (NDD) and optimum insulation thickness (xopt) was developed by linear, quadratic and cubic correlations. Thirty different mathematical correlations based on different fuel types by using XPS and EPS insulating materials. Twenty-four of these models that were developed were generated peculiar to the fuel type; six of them were generated based on average insulation thickness. R2 values of related correlations are between 0.9989 most and 0.9952 at least as well as it is pretty close to (R ≤ 1) one value. The model among these models is the xopt xopt = a+b (NDD) + c(NDD)2+ d(NDD)3 cubic mathematical model that gives the best average value. a = 0.0036, b = 5E-05, c =–7E-09 and d = 6E-13 are the values for XPS material. Following values are for EPS material; a = 0.0028, b = 5E-13, c =–7E-09 and d = 4E-05. R2 determination coefficient of both two equations is pretty close to 0.9989 and 1; the models obtained are less-than-stellar. Optimum insulation thickness of the area can be known based on the type of material via the number of degree day without the need for long analyses. According to the R2 values, the use of all models is recommended for academic and industrial users.
AtıfScopus21WoS24OpenAlex22İncele - BildiriAçık Erişim2020Speed Control of DC Motor Using Single Phase Matrix Converter
Boydak, Merve; Orhan, Ahmet; Caliskan, Abuzer
This paper focuses on speed control of DC motor using new driver circuit of Single-Phase Matrix Converter (SPMC). Changing of modulation index has been provided with closed loop PI control. Thus, the voltage applied to the armature has been controlled and rotating of motor at the desired speed has been enabled. Insulated Gate Bipolar Transistors (IGBTs) are used to perform SPMC topology. Sinusoidal Pulse Width Modulation (SPWM) technique is used to obtain switching signals. MATLAB / Simulink is used to implement simulation.
AtıfScopus3WoS3OpenAlex3İncele - MakaleAçık Erişim2020Scopus SJRQ3Modeling of Drying Processes of Dates (Phoenix, Arecaceae) with Oven or TGA and Microbiological Properties of Fresh and Dried Dates
Ertekin, Özlem; İpek, Yeliz
Drying method, which is one of the oldest preservation methods, is important for preserving fruits. Date palm fruit is an important food in human nutrition due to some vitamins, minerals, sugar, phenolic components, and high fiber content. In the literature, date palm drying was not studied sufficiently in the aspect of mathematical modeling and the effect of drying process on the microbiological properties. In this novel study, date palm drying process was applied with four different temperatures of 50°C, 70°C, 90°C, and 110°C with two different drying techniques; drying with oven and drying with thermogravimetric analysis (TGA). Chemical changes in the date palm structure after drying at different temperatures were investigated with FTIR analysis. Fibrous structure of palm fruit is also exhibited with SEM analysis. On the other hand, microbiological studies were applied both for fresh and dried date palm to observe the drying process effect on the growth of different types of microorganisms. Consequently, drying time decreased with increasing drying temperature while the color of the dried date palm fruit became darker with increasing temperature. However, the chemical structure was not affected. Drying time of oven drying technique was longer than drying with TGA technique. The mathematical model of the drying temperature depending on drying time is calculated as (Formula presented.) for TG-DTA drying experiments and (Formula presented.) for drying process with oven. In addition, the microbiological load has significantly decreased or disappeared with the drying process.
AtıfScopus6WoS6OpenAlex6İncele - MakaleYalnız künye2020Scopus SJRQ2Synthesis and modification of amine-terminated maleic anhydride‑butyl acrylate copolymer and investigation of adsorption properties for cadmium (II) ions (Cd2+)
Yilmaz, Ersen; Erenler, Fatih Mehmet; Boztuğ, Ali
In this study, a maleic anhydride‑butyl acrylate copolymer (MA-BA) was synthesized using maleic anhydride (MA) and butyl acrylate (BA) monomers. The synthesis was carried out in methyl ethyl ketone by benzoyl peroxide as the initiator at 70 °C. Secondly, the MA-BA copolymer was chemically modified with ethylenediamine and abbreviated as NH2MA-BA. The copolymer and its modified structure were analyzed spectroscopically by FT-IR, thermally by Thermo Gravimetry (TGA) and by Differential Scanning Calorimetry (DSC). Solubility tests of both structures were performed. Then, the adsorption of cadmium ions (Cd2+) by the modified copolymer (NH2MA-BA) was studied. The copolymer and its modified structure were synthesized successfully, and this was proven by their FTIR spectra. The (MA-BA) copolymer is soluble in common organic solvents but (NH2MA-BA) is not due to cross-linking. The DSC and DTA results showed that chemical modification improved the structure thermally. It was shown that the Freundlich model was the best explanation for the adsorption type in correspondence with the experimental plots, and the modified copolymer is a good candidate for Cd2+ adsorption.
AtıfScopus8WoS7OpenAlex8İncele - MakaleYalnız künye2020Scopus SJRQ1Evaluation of the radiation shielding capabilities of the Na2B4O7–SiO2–MoO3-Dy2O3 glass quaternary using Geant4 simulation code and Phy-X/PSD database
Aşkın, A.
The important gamma and neutron radiation shielding parameters of the Dy3+ doped (65-x)Na2B4O7–15SiO2–20MoO3-xDy2O3 (x = 0, 5, 10, 15, 20 mol%) glass quaternary system were investigated to provide decisive information for their application in radiation environment. Gamma and neutron attenuation properties of the glass systems studied here were evaluated in terms of the mass attenuation coefficient (μm), transmission fraction (TF), half value layer (HVL), mean free path (MFP), effective atomic number (Zeff), exposure buildup factors (EBF) and fast neutron removal cross-section (∑R) parameters. Investigation of the each aforementioned parameter was performed thanks to the utilization of Monte Carlo simulations along with the Phy-X/PSD database. The photon attenuation characteristics were evaluated for gamma ray energies varying between 0.284 and 5.0 MeV. This study indicated that increase of the Dy2O3 content from 0% to 20% mole, enhances the gamma shielding capability due to the increase of the parameters μm and Zeff. In this study it was also observed that ∑R increases from 0.099 to 0.107 cm−1 as the molar fraction of Dy2O3 increases.
AtıfScopus75WoS74OpenAlex82İncele - MakaleYalnız künye2020Scopus SJRQ2Optimization of open channels using particle swarm optimization algorithm
Saplioglu, Kemal; Ozturk, Tulay Sugra Kucukerdem; Acar, Ramazan
Due to recent increasing water demand, planning and projecting of water resources has resulted in increased costs. There-fore, it is important to obtain optimum results in project planning. In this study, dimensioning of open channels used espe-cially for irrigation purposes has been studied using a particle swarm optimization algorithm to investigate optimum base width, channel height, and slope angles. The results are summarized in graphs and tables. In the study, it was found that the optimum slope angle varied between 0. 200. 45. Furthermore, it was found that increasing the slope angle significant-ly increased costs. Finally, the increase in flow increases costs but the rate of increase diminishes.
AtıfScopus6WoS6OpenAlex9İncele - MakaleYalnız künye2020Scopus SJRQ1Assessment of occupational risks from human health and environmental perspectives: a new integrated approach and its application using fuzzy BWM and fuzzy MAIRCA
Gul, Muhammet; Ak, M. Fatih
Occupational safety issues encountered in the worksite environment are the issues that companies should consider in improving their operations with a view to human health and environmental awareness. Many methods with different rationales have been existed in the literature to prioritize hazards according to their risk levels and to mitigate their consequences. In this study, a new model is developed for occupational risk assessment by merging two well-known multi-criteria decision-making methods named best and worst method (BWM) and multi attribute ideal real comparative analysis (MAIRCA) under fuzzy environment. The proposed model differentiates from other similar models by three aspects. First, it considers severity of a hazard and its associated risk from the human and environmental riskiness perspectives. Secondly, it applies fuzzy BWM (F-BWM) to calculate the relative importance of three risk factors named as “probability, frequency and severity” of traditional Fine–Kinney method. Thirdly, it applies fuzzy MAIRCA (F-MAIRCA) to rank hazards according to their risk level using importance values obtained by F-BWM. To show applicability of the approach, a case study of risk assessment in a marble factory is fulfilled. Additionally, a number of validation studies including benchmarking analysis with fuzzy VIKOR and fuzzy TOPSIS methods; a sensitivity analysis by varying importance weights of risk factors are carried out to highlight the solidity of the proposed approach.
AtıfScopus80WoS70İncele - MakaleYalnız künye2020Scopus SJRQ1Teaching Shakespeare digitally: the Turkish experience
Öğütcü, Murat
Although teaching Shakespeare in Turkey naturally creates barriers of language, space and time, the use of digital humanities helped me to overcome these obstacles. My experiences at Hacettepe University, Ankara, Turkey, showed me that combining conventional methods of teaching Shakespeare in Turkey with digital tools helps to familiarise students with Shakespeare's plays both in the Early Modern English and Modern Turkish contexts. To motivate students to study Shakespeare's plays within and without the classroom environment, I used conventional methods like teacher-led assignments and methods including the use of social media and social projects which were then unconventional.
AtıfScopus4WoS3İncele - MakaleYalnız künye2020Scopus SJRQ1Mechanical, thermal, and morphological properties of powder coating waste reinforced acetal copolymer
Kismet, Yilmaz; Wagner, Manfred H.
The present study investigates the individual effects of three different thermosetting waste materials, used as fillers, on the mechanical, thermal and flow properties of acetal copolymers (POM). Different amounts ranging from 5% to 30% by weight of hydrolyzed powder coating recyclates were mixed as filler material in POM. The matrix and the fillers were first dry-mixed and then compounds were prepared through melt extrusion. The resulting compounds were cooled, granulated, and then standard tensile test bars were produced through use of an injection-molding machine. We investigated the mechanical and thermal properties of test specimens, and tensile strength, bending strength and impact strength were evaluated as a function of type and amount of filler material in the POM matrix. In addition, the change in melt flow index of POM/filler mixtures was determined, before and after extrusion. Furthermore, the morphology of the specimens was examined via electron microscopy. The results of this investigation are encouraging and present an innovative approach to reutilize hydrolyzed electrostatic powder coating wastes with thermoset structures as fillers in acetal copolymers.
AtıfScopus10WoS8OpenAlex13İncele - MakaleYalnız künye2020Scopus SJRQ1Geochemical characteristics of the adakite-like Dodurga Pluton (Central Pontides, N Turkey): implications for Middle Triassic continental arc magmatism in southern Black Sea region
Çimen, Okay
The tracing of Triassic arc magmatism is much-debated for a long time along the Sakarya Composite Terrane in Turkey and the southern Black Sea region. The Dodurga Pluton is located in the Central Pontides (N Turkey), one of the most complicated regions around the Black Sea region, and represents the first documented middle Triassic continental arc in the region. This pluton comprises of dacite porphyry and granodiorite, and displays calc-alkaline signatures, which is in agreement with arc-related and I-type magmas. The PM-normalized multi element and CN-normalized REE patterns are akin to volcanic arc granites, and characterized by LILEs and LREEs enrichments relative to HFSEs and HREEs coupled with negative Nb anomalies, which confirm derivation in a subduction-related tectonic setting. Moreover, the major and trace element systematics of the samples including higher Sr/Y ratios (22.93–101.36) and lower Yb contents (0.31–1.30 ppm) are consistent with those from adakitic melts compared to classical arc magmas. Therefore, this pluton also represents the first middle Triassic adakite-like magmatic occurrence in Turkey. Overall petrographic and geochemical signatures reported here indicate that the Dodurga Pluton might have been derived from a heterogeneous source, mixed by melts from subducted oceanic slab and lower continental crust in an active continental margin. Based on the Tethyan evolution in the Anatolian realm, three geodynamic scenarios are possible for its formation, and it could have been formed as a result of northward or southward-subduction of the Paleotethys Ocean or northward-subduction of the northern branch of Neotethys Ocean during the middle Triassic.
AtıfScopus8WoS8OpenAlex4İncele - MakaleAçık Erişim2020Scopus SJRQ1Evaluation of hospital disaster preparedness by a multi-criteria decision making approach: The case of Turkish hospitals
Ortiz-Barrios, Miguel; Gul, Muhammet; López-Meza, Pedro; Yucesan, Melih; Navarro-Jiménez, Eduardo
Considering the unexpected emergence of natural and man-made disasters over the world and Turkey, the importance of preparedness of hospitals, which are the first reference points for people to get healthcare services, becomes clear. Determining the level of disaster preparedness of hospitals is an important and necessary issue. This is because identifying hospitals with low level of preparedness is crucial for disaster preparedness planning. In this study, a hybrid fuzzy decision making model was proposed to evaluate the disaster preparedness of hospitals. This model was developed using fuzzy analytic hierarchy process (FAHP)-fuzzy decision making trial and evaluation laboratory (FDEMATEL)-technique for order preference by similarity to ideal solutions (TOPSIS) techniques and aimed to determine a ranking for hospital disaster preparedness. FAHP is used to determine weights of six main criteria (including hospital buildings, equipment, communication, transportation, personnel, flexibility) and a total of thirty-six sub-criteria regarding disaster preparedness. At the same time, FDEMATEL is applied to uncover the interdependence between criteria and sub-criteria. Finally, TOPSIS is used to obtain ranking of hospitals. To provide inputs for TOPSIS implementation, some key performance indicators are established and related data is gathered by the aid of experts from the assessed hospitals. A case study considering 4 hospitals from the Turkish healthcare sector was used to demonstrate the proposed approach. The results evidenced that Personnel is the most important factor (global weight = 0.280) when evaluating the hospital preparedness while Flexibility has the greatest prominence (c + r = 23.09).
AtıfScopus87WoS69OpenAlex97
İncele - MakaleAçık Erişim2020Scopus SJRQ11D-CADCapsNet: One dimensional deep capsule networks for coronary artery disease detection using ECG signals
Butun, Ertan; Yildirim, Ozal; Talo, Muhammed; Tan, Ru-San; Rajendra Acharya, U.
Purpose: Cardiovascular disease (CVD) is a leading cause of death globally. Electrocardiogram (ECG), which records the electrical activity of the heart, has been used for the diagnosis of CVD. The automated and robust detection of CVD from ECG signals plays a significant role for early and accurate clinical diagnosis. The purpose of this study is to provide automated detection of coronary artery disease (CAD) from ECG signals using capsule networks (CapsNet). Methods: Deep learning-based approaches have become increasingly popular in computer aided diagnosis systems. Capsule networks are one of the new promising approaches in the field of deep learning. In this study, we used 1D version of CapsNet for the automated detection of coronary artery disease (CAD) on two second (95,300) and five second-long (38,120) ECG segments. These segments are obtained from 40 normal and 7 CAD subjects. In the experimental studies, 5-fold cross validation technique is employed to evaluate performance of the model. Results: The proposed model, which is named as 1D-CADCapsNet, yielded a promising 5-fold diagnosis accuracy of 99.44% and 98.62% for two- and five-second ECG signal groups, respectively. We have obtained the highest performance results using 2 s ECG segment than the state-of-art studies reported in the literature. Conclusions: 1D-CADCapsNet model automatically learns the pertinent representations from raw ECG data without using any hand-crafted technique and can be used as a fast and accurate diagnostic tool to help cardiologists.
AtıfScopus100OpenAlex96İncele - MakaleYalnız künye2020Scopus SJRQ2Analytical and finite element solutions of continuous contact problem in functionally graded layer
Kaya, Yusuf; Polat, Alper; Özşahin, Talat Şükrü
In this study, we solve the continuous contact problem of two layers with different material properties, loaded with two rigid flat blocks and resting on a rigid plane, by analytical and finite element methods. All surfaces are assumed to be frictionless. The upper layer is the functionally graded layer (FG), the height h1, the underlying layer is homogeneous, and the height is h2. It is assumed that the FG layer is isotropic and that the shear modulus and density change exponentially. The FG layer is loaded by means of two rigid flat blocks whose external loads are Q and P (per unit thickness in z direction). In the analytical solution of the problem, stress and displacement expressions are substituted in the boundary conditions and the problem is demoted to singular integral equations where the contact stresses are the unknown functions. These singular integral equations are solved numerically using the Gauss–Chebyshev integration formulas. Two-dimensional finite element analysis of the problem is performed using the ANSYS package program. The analyses are performed for different shear modulus ratios (μ2/μ-h1), distances between the blocks ((c − b)/h1) and inhomogeneity parameters (βh1). The contact stresses under the blocks, the normal stresses (σy) between interfaces of the FG layer and the homogeneous layer and between the homogeneous layer and rigid plane are also measured. In addition, the initial separation load and the initial separation distances (χcr, λcr) of the FG layer and homogeneous layer are determined. The results are presented comparatively as graphs and tables.
AtıfScopus18WoS19OpenAlex14İncele - MakaleYayıncıda açık erişim2020Scopus SJRQ2Phytoremediaton of priority substances (Pb and Ni) by Phragmites australis exposed to poultry slaughterhouse wastewater
Topal, Murat; Arslan Topal, E. Işıl
The aim of the work was to evaluate the ability of Phragmites australis to uptake lead and nickel from the stream taking the treated poultry slaughterhouse wastewater (PSW). Pb and Ni concentrations, which are the priority substances of the water frame directive, were detected separately at the root, stem and leaf of P. australis at 50 m and 100 m from the downstream of discharge point. The uptake of Pb and Ni by P. australis followed the order of root > leaf > stem. The Ni uptake was higher than Pb uptake in P. australis exposed to poultry wastewater. As a result, P. australis exposed to PSW were found to have the ability to uptake Pb and Ni. It has been determined that P. australis can be used for removal and phytoremediation of Pb and Ni metals from PSWs.
AtıfScopus13WoS12İncele - MakaleYalnız künye2020Scopus SJRQ1A manufacturing failure mode and effect analysis based on fuzzy and probabilistic risk analysis
Gul, Muhammet; Yucesan, Melih; Celik, Erkan
This study proposes an improved failure mode and effect analysis (FMEA) with fuzzy Bayesian Network (FBN) and fuzzy best-worst method (FBWM) to assess failures in plastic production. To eliminate the drawbacks of the classical risk priority number (RPN) computation of FMEA, this approach is developed. Unlike classical RPN, a new parameter hierarchy is constructed, and three sub-parameters are injected into the approach. These parameters are weighted by the aid of FBWM. Hereafter, a fuzzy rule-based system is constructed by incorporating Bayesian Network (BN). Also, a sensitivity analysis is performed to observe the final FMEA score changes in accordance with the change of subjective probability values. Finally, a comparative analysis with two approaches of classical FMEA and FBWM-based FMEA (without a fuzzy rule-based system incorporating BN) is fulfilled. The results of the study are strengthened with the experts’ opinions regarding the importance of failure modes for the final product and the whole system and supported them by experience feedback in the observed facility.
AtıfScopus68WoS59OpenAlex68İncele - MakaleYalnız künye2020Scopus SJRQ2The effect of graphene nano-sheet (GNS) weight percentage on mechanical and corrosion properties of AZ61 and AZ91 based magnesium matrix composites
Guler, Omer; Say, Yakup; Dikici, Burak
In this study, the effect of graphene nano-sheets (GNSs) on mechanical and corrosion properties of AZ61 and AZ91 based composites was investigated, detail. GNSs have been successfully produced by the liquid phase exfoliation (LPE) method and then, added AZ61 and AZ91 matrix with 01, 0.2, and 0.5 wt% GNSs for the production of the composites. The composite compacts were produced by powder metallurgy technique and sintered for 2 h at 500 °C under Ar atmosphere. The composite characterizations were carried out by scanning and transmission electron microscopes (SEM, TEM), electron dispersive spectroscope (EDS), Raman spectroscopy, and X-ray diffraction. The mechanical properties and corrosion behaviors of the composites have been compared with compression tests and potentiodynamic scanning (PDS) techniques, respectively. The results showed that the compressive strength of the composites increased with increasing GNS amount in both the AZ61 and AZ91 matrix alloys. The most susceptible composites to corrosion for both AZ61 and AZ91 matrix were observed in the 0.5 wt% GNS containing structures. However, there is a certain ratio of GNS in the Mg matrix to achieve good corrosion resistance.
AtıfScopus29WoS25OpenAlex33İncele - MakaleYalnız künye2020Scopus SJRQ1Linear, nonlinear optical and photon attenuation properties of La3+ doped tellurite glasses
Boukhris, Imed; Kebaili, Imen; Sayyed, M.I.; Askin, A.; Rammah, Y.S.
Linear and nonlinear optical features of La3+ doped tellurite glasses in the form 75TeO2–10ZnO –5Li2O –(10-x)Nb2O5 –xLa2O3: x = 0, 0.5, 1.0, 1.5, 2.0, and 2.5 in mol% (abbreviated as La0.0. La0.5, La1.0, La1.5, La2.0, and La2.5) were investigated. Also, the γ-photons attenuation parameters were tested utilizing Geant4 simulation code. Results revealed that the molar polarizability (αmolar) takes values from 8.685 × 10−24 to 7.933 × 10−24 cm3, while the molar refraction (Rmolar) changes from 21.886 to 20.219 (cm3/mol) for La0.0 to La2.5 glasses. The static dielectric constant (εstatic) varies from 6.368 to 5.191, whereas optical electronegativity (χ*) varies from 0.690 to 0.852 for La0.0-La2.5 glasses. Non-linear optical susceptibility (χ3) decreases from 5.675 × 10−12 to 2.109 × 10−12 (esu) with increment La2O3 content in the glasses, while non-linear refractive index (n2optical) decreases from 8.472 × 10−11 to 3.488 × 10−11 (esu). The radiation attenuation characteristics for the tested glasses were investigated with the help of Geant4 code. The mass attenuation coefficient (μm) was simulated between 0.284 and 2.506 MeV. The influnce of La2O3 on the shielding parameters was examined. Among the studied glasses, La2.5 posseses the highest μm values. Also, La2.5 sample has the lowest transmission fraction, which implies that more photons can be attenuated with La2.5 glass using a thin glass layer. From the transmission fraction results, we found that thick glasses are needed to attenuate gamma rays coming at high energies. At 0.511 MeV, the half value layer (HVL) value of the La0.0 glass is 1.49 cm while, at the same energy, the HVL value of the La2.5 glass is 1.44 cm.
AtıfScopus34OpenAlex35İncele