Sürdürülebilir Kalkınma Amaçları

Yazarlar

  • MakaleYalnız künye2021Scopus SJRQ1
    Low-velocity impact, bending, and compression response of carbon fiber/epoxy-based sandwich composites with different types of core materials

    Dogan, Akar

    This study focuses on the investigation of the effects of different core types on the low velocity impact, three-point bending and out-of-plane compression loading performance of sandwich composites. Three core materials were selected: Balsa wood, PVC foam, and Ayous wood. The facesheets of sandwich composites were produced by woven carbon/epoxy. Balsa and PVC foam are widely used in sandwich composites as core materials. In this study, Ayous wood, which is the lightest tree after Balsa, was used as core material in addition to traditional core materials. Woven carbon fiber fabrics with an areal density 200 g/m2 as reinforcement and epoxy matrix were used to produce the sandwich composite. Vacuum-assisted resin infusion molding method was used to manufacture composite panels. A number of tests under various impact energy levels for three different sandwich composites were conducted with Fractovis Plus impact testing machine in order to investigate the energy absorption capacity of sandwich composites. Maximum contact forces, absorbed energies, and the maximum deflections of sandwich panels were obtained for each impact energy level. Despite having the same facesheets, Ayous core sandwich composites possess a higher perforation threshold than Balsa and PVC foam sandwich composites. The perforation threshold of Balsa, PVC foam, and Ayous sandwich composites are 85, 72, and 170 J, respectively. In addition, the Ayous core sandwich composites have better bending and compression strengths. The bending strength of the Ayous sandwich composite is higher about six times than PVC sandwich composite and about two times than Balsa sandwich composite.

    AtıfScopus61WoS56OpenAlex56
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  • MakaleYalnız künye2021Scopus SJRQ2
    Effects of Optimized Operating Parameters on Combustion Characteristics and NOx Emissions of a Burner based on Orthogonal Analysis

    Xu, Qian; Akkurt, Nevzat; Yang, Gang; Zhu, Lidong; Shi, Kejian; Wang, Kang; Zou, Zhenwei; Liu, Zhihui; Wang, Jiulong; Du, Zhiwei

    To optimize the structure of the burner, improve the combustion performance, and reduce the emission of NOx, a self-circulating low NOx combustion technology was used to design a new type of flue gas self-circulating low NOx burner. Based on previous research on the numerical model of combustion and the composition of mixed gas on combustion and NOx emissions, the effect of various factors on the ejection coefficient of the flue gas self-circulating structure was analyzed using the orthogonal test method, and the burner operating parameters, such as preheating temperature and excess air coefficient, were deeply studied through the three-dimensional finite element numerical model in this paper. The results show that the diameter ratio of the nozzle and the length of the cylindrical section of the flue gas self-circulating structure have great influence on its ejection and mixing ability. The optimal ejection coefficient was 0.4829. Overall, the amount of NOx emissions greatly increased from 6.23×10−6 (volume fraction) at the preheating temperature 973 K to 3.5×10−3 at preheating temperature 1573 K. When the excess air coefficient decreased from 1.2 to 1, the maximum combustion temperature decreased from 2036.3 K to 1954.22 K, and the NOx emissions decreased from 352.29×10−6 to 159.73×10−6.

    AtıfScopus7OpenAlex8
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  • MakaleAçık Erişim2021Scopus SJRQ2
    Facile preparation of commercial Bi2O3 nanoparticle decorated activated carbon for pseudocapacitive supercapacitor applications

    Üner, Osman; Aslan, Naim; Sarıoğlu, Akın; Semerci, Fatih; Koç, Mümin Mehmet

    In this work, a facile method to prepare Bi2O3 decorated activated carbon (Bi2O3@AC) composites with high pseudocapacitive properties was presented. The inorganic–organic composites synthesized using commercial Bi2O3 and active carbon with different weight ratio. The composites were assessed using spectroscopic, microscopic, and diffractive techniques. Our assessments confirmed that active carbons were successfully doped with commercial Bi2O3 nanoparticles with different dopant rates. The electrochemical performance of as-prepared materials was researched by cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy in 6 M KOH electrolyte. Higher specific capacitance was achieved for increased Bi2O3 nanoparticle in composites. The 20%-Bi2O3@AC had a maximum specific capacitance of 565 F/g at a current density of 1 A/g. In addition, the symmetrically assembled supercapacitor delivers a high energy density (23.0 Wh kg−1). Moreover, 67% of the initial capacitance is maintained after 1500 cycles at 200 mV/s, suggesting good cycling stability. Due to the synergistic effect of compositing a promising electrochemical performance was observed that was not obtained by bare AC or Bi2O3. As a result, the electrochemical properties of 20%-Bi2O3@AC composite is promising and it may be used as potential electrode for supercapacitor.

    AtıfScopus29WoS27
    ScopusWeb of Scienceİncele
  • MakaleAçık Erişim2021
    The evaluation of collaborative synchronous learning environment within the framework of interaction and community of inquiry: An experimental study

    Aslan, Alper

    This study aims to investigate a collaborative synchronous learning environment in terms of students‟ community of inquiry perceptions (cognitive, social, and teaching presences) and interaction levels. This quantitative study was conducted with the participation of fifty-nine freshmen (twenty-nine in the control group and thirty in the experimental group) in the department of Information Technologies at a university. The study lasted nine weeks, including two weeks of data collection and seven weeks of implementation procedure. After the implementation, the Community of Inquiry Scale and the Online Course Interaction Level Determination Scale were administered to the participants. The results revealed that co-operative synchronous learning experiences positively influenced students‟ community of inquiry perceptions and interaction levels in the experimental group. Further results and implications are discussed at the end.

    • SDG 4 · Nitelikli Eğitim
    AtıfScopus17OpenAlex21
    Scopusİncele
  • MakaleAçık Erişim2021Scopus SJRQ1
    Comprehensive biological and chemical evaluation of two seseli species (S. gummiferum and s. transcaucasicum)

    Zengin, Gokhan; Stojković, Dejan; Mahomoodally, Mohamad Fawzi; Jugreet, Bibi Sharmeen; Paksoy, Mehmet Yavuz; Ivanov, Marija; Gašić, Uroš; Gallo, Monica; Montesano, Domenico

    Seseli L. is one of the largest genera of the Apiaceae family widely known for their traditional uses as herbal remedies. In the present study, the methanolic and water extracts of two Seseli species, S. gummiferum and S. transcaucasicum were evaluated for their bioactive contents and biological activities. The total phenolic and flavonoid contents in the extracts ranged from 19.09 to 24.33 mg GAE/g and from 0.45 to10.09 mg RE/g, respectively. Moreover, while narcissin was detected as the most abundant component in the methanolic extract of S. transcaucasicum (261.40 µg/g), chlorogenic acid was identified as the major component in all the other extracts, although a high amount was also present in the methanolic S. transcaucasicum extract (107.48–243.12 µg/g). The total antioxidant capacity was also determined by the phosphomolybdenum assay (0.66–1.18 mM TE/g). Other antioxidant assays such as the radical scavenging assays (DPPH: 5.51–11.45 mg TE/g; ABTS: 43.46–51.91 mg TE/g), reducing assays (CUPRAC: 41.67–53.20 mg TE/g; FRAP: 31.26–34.14 mg TE/g), as well as the metal chelating activity assay (14.38–38.57 mg EDTAE/g) were conducted. All the extracts showed inhibitory potential against the enzyme’s amylase (0.12–0.78 mM ACAE/g), acetyl-and butyryl-cholinesterase (0.15–9.71 mg GALAE/g), while only the methanolic extracts acted as inhibitors of tyrosinase (107.15 and 109.37 mg KAE/g) and only the water extract of S. gummiferum displayed anti-glucosidase activity (0.13 mM ACAE/g). Interestingly, the methanolic extracts of both Seseli species showed lower cytotoxicity towards HaCaT cells (IC50: >500 µg/mL), compared to the water extracts (IC50: 267.8 and 321.41 µg/mL). Besides, only the methanolic extracts showed a slight wound healing effect (28.21 and 31.23%). All extracts showed antibacterial action against Staphylococcus lugdunensis (minimum inhibitory and bactericidal concentrations: 0.025–2 mg/mL). S. gummiferum methanolic extract, which exhibited the highest antibacterial potency was found to inhibit adhesion and invasion of S. lugdunensis to HaCaT cells as well. Taken together, this study demonstrated the two Seseli species to harbour interesting bioactive components, in particular polyphenolics and to exhibit several biological properties that could be further investigated for their potential exploitation as healing agents as supported by various traditional medicinal uses.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus16OpenAlex15
    ScopusWeb of SciencePubMedİncele
  • MakaleYalnız künye2021Scopus SJRQ2
    A modified failure modes and effects analysis using interval-valued spherical fuzzy extension of TOPSIS method: case study in a marble manufacturing facility

    Gul, Muhammet; Ak, M. Fatih

    Failure modes and effects analysis (FMEA) is a commonly used step-by-step approach to assess potential failures existing in a product or process design. In this paper, a modified FMEA model based on an interval-valued spherical fuzzy extension of technique for order preference by similarity to ideal solution (IVSF-TOPSIS) is proposed to cope with drawbacks of the traditional risk priority number (RPN) computation. Spherical fuzzy sets are the integration of Pythagorean fuzzy sets and neutrosophic sets. They provide more freedom to experts in decision making by including the degree of membership, non-membership, and hesitation of fuzzy sets. Therefore, initially, TOPSIS is merged with a special branch of spherical sets “interval-valued spherical fuzzy sets” to determine priorities of emerged failures. As a novelty to traditional RPN of FMEA, three parameters called cost, prevention, and effectiveness in addition to the existed parameters of severity, occurrence and detection are attached to the proposed approach. Weights of these parameters are determined via an interval-valued spherical weighted arithmetic mean operator (IVSWAM). As a demonstration, a case study in a marble manufacturing facility is provided to show the applicability of the novel model. Results show that the most crucial failure modes concern with the maintenance and repairing works of the factory and the lack of technical periodic checks of lifting vehicles regarding “block area: crane” failures. Some comparative and validation studies are also performed to test the solidity of the approach.

    • SDG 9 · Sanayi, Yenilikçilik ve Altyapı
    AtıfScopus108WoS93OpenAlex103
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  • MakaleYalnız künye2021Scopus SJRQ3
    Seismicity of East Anatolian of Turkey and Failures of Infill Walls Induced by Major Earthquakes

    Doǧangün, Adem; Yön, Burak; Onat, Onur; Emin Öncü, Mehmet; Saǧlroǧlu, Serkan

    There are three major fault zones in Turkey scattered around the country known as East Anatolian Fault (EAF), North Anatolian Fault (NAF) and Anatolian-Aegean Subduction Zone (AASZ). Last two decades, EAF has been rather quiescent compared with NAF. However, this quiescence was broken in the beginning of the millennium. The strong shaking was started in 2003 with Bingöl earthquake (Mw = 6.3) and the last earthquake on the EAF is the Sivrice-Elazlǧ (Mw = 6.8) on January 24, 2020. Strong seismicity of these faults damaged the structures severely and caused death of the habitants. This study aims to present, seismotectonic of the region, general characteristics of the earthquakes and more specifically to report structural damage of infill walls of the structure's damages caused by these earthquakes. Damage evaluation and identification of the observed infill wall damages due to 2003 Bingöl, 2011 Van earthquakes and January 24, 2020 Sivrice-Elazlǧ earthquake occurred Turkey's Eastern region, were presented, and possible solutions were suggested. Moreover, the effects of the infill walls on the behavior of structures under static and dynamic load cases are discussed that experienced in these earthquakes. Damages are classified according to formations such as in-plane or out-of-plane, evaluations and the results obtained from the discussions are presented for each category.

    AtıfScopus35WoS32
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  • MakaleAçık Erişim2021Scopus SJRQ1
    Occurrence of micropollutants in the Yesilirmak River Basin, Turkey

    Kucuk, Elif; Pilevneli, Tolga; Onder Erguven, Gokhan; Aslan, Sibel; Olgun, Elmas Ö.; Canlı, Oltan; Unlu, Kahraman; Dilek, Filiz B.; Ipek, Ubeyde; Avaz, Gulsen

    The European Water Framework Directive (WFD) (2000/60/EC) is the most visionary piece of European environmental legislation that aims to achieve good water status of both surface water and groundwater bodies. The Directive provides a fundamental basis for surface water monitoring activities in the European Member States. The objective of this study is to investigate the occurrence of micropollutants in the Yesilirmak River and to develop a cost-effective monitoring strategy based on spatiotemporal data. A 2-year seasonal monitoring program was conducted between 2016 and 2018, and the water samples were analyzed for 45 priority substances as defined by the WFD and 250 national river basin–specific pollutants. In the basin, 166 pollutants were quantified in at least one of the samples with individual concentrations ranging from 6 × 10−6μg/L to 100 mg/L. Fifty-four pollutants with a frequency of occurrence greater than 5% were selected for further evaluation. Based on statistical evaluation of the data, 20 pollutants were identified as the pollutants of primary concern. These 20 pollutants were grouped under three categories (metals, biocides, and industrial organic compounds) and their spatiotemporal distributions in the basin were assessed to establish a monitoring strategy specific to each pollutant category. The results of the study revealed that the common season for the monitoring of all pollutant categories was the spring. This study provides a generic methodology for the development of a cost-effective water quality monitoring strategy, which can be applicable for use in different basins and pollutant datasets.

    • SDG 6 · Temiz Su ve Sanitasyon
    AtıfScopus13OpenAlex14
    ScopusWeb of SciencePubMedİncele
  • MakaleYalnız künye2021Scopus SJRQ1
    Hazard identification, risk assessment and control for dam construction safety using an integrated BWM and MARCOS approach under interval type-2 fuzzy sets environment

    Celik, Erkan; Gul, Muhammet

    Undoubtedly, dams are one of the projects developed by people to make optimal water use and generate hydroelectric energy power. In addition to the importance of detailed project planning, faultless production, and optimal working conditions in dam constructions, it is equally important to identify and analyze the risks from the occupational health and safety (OHS) perspective that may arise during construction and operation. In this context, hazard identification, risk analysis, and control, which are the main issues of dam safety, have gained importance. In this study, a novel approach is developed for dam construction safety. Two newly proposed multi-criteria decision-making (MCDM) methods of “Best-Worst Method-BWM” and “measurement of alternatives and ranking to Compromise solution-MARCOS”, are merged under the context of interval type-2 fuzzy sets (IT2FSs). Severity and probability, two essential parameters of the risk score, have been weighted using BWM. Subsequently, the priority orders of hazards have been determined by the MARCOS. In implementing the approach to the blasting process in dam construction, several control measures are suggested for stakeholders. Some comparative works and sensitivity analyses are performed to test the approach's validity and solidity from the methodological viewpoint.

    AtıfScopus140WoS113
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  • MakaleYalnız künye2021Scopus SJRQ3
    Calculation of Gamma Shielding Properties for Glass Ceramics using FLUKA

    Nur, Kuluöztürk Zehra; Demir, Nilgün; Dal, Murat

    Abstract: In this paper, gamma radiation shielding properties of same glass ceramics are reported for 356, 662, 1173, and 1330 keV gamma energies. Firstly, the validity of the FLUKA method was determined using the (90–x)TeO2-xMoO3-10ZnO glass system whose shielding parameters were determined by different analytical methods in the literature. The mass attenuation coefficients (µm), half-value layer, and mean free path parameters for the glass ceramic samples were calculated by the FLUKA. When the results obtained with the FLUKA and XCOM database were examined, it was found that glass f6, which is one of the PbO–Al2O3–SiO2–TiO2 glass-ceramic samples, had the highest gamma shielding property among the glass ceramics. Additionally, comparisons show that the FLUKA code is an alternative method to analytical methods for determining gamma shielding parameters and it is a tool that can provide preliminary information and comparisons for experimental studies.

    AtıfScopus6WoS5OpenAlex9
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  • Kitap BölümüYalnız künye2021
    A Risk Prioritization Method Based on Interval-Valued Pythagorean Fuzzy TOPSIS and Its Application for Prioritization of the Risks Emerged at Hospitals During the Covid-19 Pandemic

    Gul, Muhammet; Yucesan, Melih

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus2
    Scopusİncele
  • MakaleAçık Erişim2021Scopus SJRQ3
    Removal of total organic carbon and color from slaughterhouse wastewaters using electrocoagulation process: Central composite design optimization

    Tanyol, Mehtap; Tevkur, Servet

    In the present work, the process of electrocoagulation was utilized to remove total organic carbon (TOC) and color from slaughterhouse wastewaters and response surface methodology (RSM) inte-grated central composite design (CCD) was applied to optimize the operating factors of the pro-cess, that used iron electrodes. The optimal values for the removal of TOC and color were achieved with the quadratic regression model obtained from CCD. The optimum points for current density, inter-electrode distance, and reaction time obtained by the numerical analysis were 22.97 mA/m2, 12.03 mm, and 78.95 min for TOC, while these values were 23.08 mA/m2, 15.84 mm, and 80.77 min for color, respectively. At the optimum values, maximum TOC and color removal were obtained as 94.77% and 99.32%, respectively. The results indicated that the electrocoagulation process is an effective treatment technique for the removal of TOC and color from slaughterhouse wastewaters.

    • SDG 6 · Temiz Su ve Sanitasyon
    • SDG 12 · Sorumlu Üretim ve Tüketim
    AtıfScopus5WoS4OpenAlex3
    ScopusWeb of Scienceİncele
  • MakaleYalnız künye2021Scopus SJRQ2
    Boron-Doped Hydroxyapatite Coatings on NiTi Alloys Using the Electrophoretic Deposition Method: Enhanced Corrosion and Adhesion Performances

    Aksoy, M.E.; Aksakal, B.; Aslan, N.; Dikici, B.

    Metallic implants are functionalized with coatings due to the need to protect against biological corrosion in the body. Hydroxyapatite (HAp) has desirable biocompatibility and structural properties, but poor mechanical properties limit its use as a standalone coating. In this study, boron-doped hydroxyapatite (B-HAp) biocomposites containing 5, 10, and 15% boron by weight were synthesized by the sol-gel method and applied as a coating to NiTi using electrophoretic deposition (EPD). The deposition was carried out for 60, 90, and 120 s, and sintering at 750 °C for 75 minutes under vacuum. The coated substrates were then characterized by XRD, SEM, and FT-IR, and their adhesion strengths and in-vitro corrosion behaviors in simulated body fluid were compared with uncoated samples. The results showed that the microporous powders formed well-bonded structures, which positively affect adhesion strength. The highest adhesion strength (30 MPa) and corrosion resistance were achieved with 15 wt.% B-HAP coating at 120 s deposition time and 76.5 μm coating thickness.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus18WoS16OpenAlex19
    ScopusWeb of Scienceİncele
  • MakaleYalnız künye2021Scopus SJRQ1
    Effect of pumice powder and artificial lightweight fine aggregate on self-compacting mortar

    Etli, Serkan; Cemalgil, Selim; Onat, Onur

    An experimental program was conducted to investigate the fresh properties, mechanical properties and durability characteristics of the self-compacting mortars (SCM) produced with pumice powder and Artificial Lightweight Fine Aggregate (aLWFA). aLWFA was produced by using fly ash. A total of 16 different mixtures were designed with a constant water-binder ratio of 0.37, in which natural sands were partially replaced with aLWFA and pumice powder at different volume fractions of 5%, 10% and 15%. The artificial lightweight aggregates used in this study were manufactured through cold bonding pelletisation of 90% of class-F fly ash and 10% of Portland cement in a tilted pan with an ambient temperature and moisture content. Flowability tests were conducted on the fresh mortar mixtures beforehand, to determine the self-compacting characteristics on the basis of EFNARC. To determine the conformity of the fresh mortar characteristics with the standards, mini-slump and mini-V-funnel tests were carried out. Hardened state tests were conducted after 7, 28 and 56 days to determine the flexural strength and axial compressive strength respectively. Durability, sorptivity, permeability and density tests were conducted at the end of 28 days of curing time. The test results showed that the pumice powder replacement improved both the fresh state and the hardened state characteristics of the mortar and the optimum mixture ratio was determined as 15%, considering other studies in the literature. In the aLWFA mixtures used, the mechanical and durability characteristics of the modified compositions were very close to the control mixture. It is concluded in this study that mixtures with pumice powder replacement eliminated the negative effects of the aLWFA in the mortars and made a positive contribution.

    • SDG 9 · Sanayi, Yenilikçilik ve Altyapı
    • SDG 12 · Sorumlu Üretim ve Tüketim
    AtıfScopus16WoS15OpenAlex17
    ScopusWeb of Scienceİncele
  • MakaleAçık Erişim2021Scopus SJRQ1
    A multiple criteria decision-making approach for increasing the preparedness level of sales departments against COVID-19 and future pandemics: A real-world case

    Ortiz-Barrios, Miguel; Borrego-Areyanes, Arlen Alaine; Gómez-Villar, Iván Darío; De Felice, Fabio; Petrillo, Antonella; Gul, Muhammet; Yucesan, Melih

    The impact of the pandemic and the lockdown has been more devastating than expected on the world economy. It is essential to formulate strategies in real-time. In this research, a multicriteria decision-making model for increasing the preparedness level of sales departments when facing COVID-19 waves and future pandemics is proposed. The model is comprised of 8 criteria, 29 sub-criteria, and 7 alternatives. The study is based on the integration of the AHP and TOPSIS techniques. AHP is used for calculating the criteria and sub-criteria weights. While, TOPSIS is used for calculating the preparedness level, ranking the companies, and identifying the weaknesses that should be addressed for increasing their effectiveness in the current market scenario. The model is developed with the aid of an experts’ group from the electrical appliance sector and studies from the reported literature. This application is completely novel in the literature and has been applied in the wild with remarkable companies in Colombia. A case study in the electrical appliance sector is presented as a pilot study but it should be noted that the methodology is flexible and scalable in any scenario.

    AtıfScopus18OpenAlex21
    ScopusWeb of Scienceİncele
  • MakaleYalnız künye2021Scopus SJRQ1
    Failure prioritization and control using the neutrosophic best and worst method

    Yucesan, Melih; Gul, Muhammet

    Failure prioritization process is described by identifying potential failures and its effects, quantifying their priorities and determining appropriate ways to mitigate or control. In the literature, many approaches are suggested to prioritize failures and associated effects quantitatively. Multicriteria decision-making (MCDM) approaches are forefront that they can express the failures verbally based on decision-makers’ judgments. They explain different types of uncertainties, which are generally modeled by fuzzy sets. However, fuzzy sets focus only on one membership value in decision-making. At this point, neutrosophic sets are more suitable than classical fuzzy sets by proposing three membership values named truth-membership, indeterminacy-membership and falsity-membership. Therefore, in this study, a novel approach based on the neutrosophic best and worst method (NBWM) is proposed and a case study is also performed in the implant production. The best and worst method (BWM) is merged with neutrosophic sets since it has fewer pairwise comparisons while determining the importance weights of failures. To show the applicability of the approach, a case study in an implant manufacturing plant that produces many products, including implants in different shapes and sizes in Turkey is carried out. Besides the case study, a comparative study is performed to test the validity of the proposed NBWM approach. This approach can make the decision-making process more dynamic in real-world problems with indeterminate and inconsistent information, considering the benefits of BWM and neutrosophic sets either individually or in integration. The present study contributes to the knowledge both methodologically and in an application by proposing NBWM for failure assessment problems for the first time in the literature and creating an adaptive model for manufacturing and other industries.

    AtıfScopus33WoS32OpenAlex41
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  • MakaleYalnız künye2021Scopus SJRQ1
    Factors affecting ICT integration in TURKISH education: a systematic review

    Turgut, Yigit Emrah; Aslan, Alper

    This research aims to reveal factors affecting Information and Communication Technologies (ICT) integration in learning environments in Turkey. The meta-synthesis method is used to make in-depth analysis and to interpret qualitative research findings on this issue. Through inclusion and exclusion criteria, 60 studies among 907 candidate studies accessed from databases named Web of Science, Education Resource Information Center (ERIC) and the Turkish Academic Network and Information Center (ULAKBIM) are included in this research. As a result of analyses, it is revealed that ICT integration into learning environments in Turkey is affected by five factors; students, educational material, infrastructure, management, and teachers. Considering these factors, it has been found that certain factors become prominent namely: the ICT and pedagogy competence of teachers; students’ ICT competence; a lack of technical equipment and technical support; a lack of educational materials; the attitudes of school administrators; and the quality and lack of in-service training for ICT. It is concluded that the factors affecting the ICT integration in education are directly or indirectly related to each other, and that ICT integration should be addressed with all its stakeholders and phases as a whole.

    • SDG 4 · Nitelikli Eğitim
    AtıfScopus38WoS28OpenAlex51
    ScopusWeb of Scienceİncele
  • MakaleAçık Erişim2021Scopus SJRQ2
    N(κ)−contact metric manifolds with generalized Tanaka-Webster connection

    Ünal, İnan; Altın, Mustafa

    In this paper, we characterize N(κ)-contact metric manifolds with generalized Tanaka-Webster connection.We obtain some curvature properties. It is proven that if an N(κ)-contact metric manifold with generalized Tanaka-Webster connection is K-contact then it is an example of generalized Sasakian space form. Also, we examine some flatness and symmetric conditions of concircular curvature tensor on an N(κ)-contact metric manifolds with generalized Tanaka-Webster connection.

    AtıfScopus5WoS1OpenAlex2
    ScopusWeb of Scienceİncele
  • MakaleAçık Erişim2021Scopus SJRQ4
    DETERMINATION OF THE ANTIOXIDANT PARAMETERS OF COMMONLY AVAILABLE BLACK PINE (PINUS NIGRA J.F. ARNOLD)

    Yildirim, Nuran Cikcikoglu; Gezer, Esref; Yildirim, Numan

    The antioxidant parameters of black pine (Pinus nigra J.F. Arnold) needles samples collected from different areas in the province of Diyarbakir, Turkey were studied. Black pine needles samples were collected from three different locations (Egil, Kosuyolu, and Diyarbakir industrial area) in the province of Diyarbakir in summer and winter seasons. The activity of enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST) and malondialdehyde (MDA) levels of the samples were determined by ELISA method. Results showed that SOD enzyme activities of the samples collected in summer from Kosuyolu and the industrial area decreased compared to the control group, but increased in the samples collected in winter from the same areas. When compared to the control group, it was observed that the MDA levels of the samples collected from Kosuyolu and the industrial area increased.

  • MakaleAçık Erişim2021
    A holistic FMEA approach by fuzzy-based Bayesian network and best–worst method

    Yucesan, Melih; Gul, Muhammet; Celik, Erkan

    Failure mode and effect analysis (FMEA) is a risk analysis tool widely used in the manufacturing industry. However, traditional FMEA has limitations such as the inability to deal with uncertain failure data including subjective evaluations of experts, the absence of weight values of risk parameters, and not considering the conditionality between failure events. In this paper, we propose a holistic FMEA to overcome these limitations. The proposed approach uses the fuzzy best–worst (FBWM) method in weighting three risk parameters of FMEA, which are severity (S), occurrence (O), and detection (D), and to find the preference values of the failure modes according to parameters S and D. On the other side, it uses the fuzzy Bayesian network (FBN) to determine occurrence probabilities of the failure modes. Experts use a procedure using linguistic variables whose corresponding values are expressed in trapezoidal fuzzy numbers, and determine the preference values of the failure modes according to parameter O in the constructed BN. Thus, the FBN including expert judgments and fuzzy set theory addresses uncertainty in failure data and includes a robust probabilistic risk analysis logic to capture the dependence between failure events. As a demonstration of the approach, a case study was conducted in an industrial kitchen equipment manufacturing facility. The results of the approach have also been compared with existed methods demonstrating its robustness.

    AtıfScopus105WoS93
    ScopusWeb of Scienceİncele