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Koleksiyondaki öğeler
- MakaleAçık Erişim2023Scopus SJRQ3WEAR AND ADHESION PROPERTIES OF MULTILAYER Ti/TiN, (/TiC)/ TiCN/ TaN THIN FILMS DEPOSITED ON Ti13Nb13Zr ALLOY BY CLOSED FIELD UNBALANCED MAGNETRON SPUTTERING
Aslan, Ali Kemal; Bahçe, Erkan
Ti13Nb13Zr alloy stands out as an alternative to Ti6Al4V alloy for orthopaedic joint implant applications due to its low modulus of elasticity, high mechanical properties, high corrosion resistance, high biocompatibility and low modulus of elasticity, as well as con-taining no cytotoxic elements. In this study, Ti13Nb13Zr alloy was coated with TiN/TiC/TiCN/TaN multilayer thin films by pulsed-dc CFBUMS method to increase wear resistance and improve surface properties. Characterization of the deposited films were con-ducted by XRD, SEM, AFM, pin-on-disk, progressive scratch experiments. As a result, it is observed that all the coatings enhanced the tribological properties of the Ti13Nb13Zr alloy surface. The 20-layer TiN/TiC/TiCN/TaN multilayer coatings gave the best results for wear resistance and adhesion properties. Enhancing the interlayer number resulted in increased wear and adhesion resistance. In addition, it was determined that using TiC instead of TiN in the interlayers gave higher results regarding adhesion, wear, and mechanical properties.
AtıfScopus1WoS1OpenAlex1
İncele - MakaleYalnız künye2024Scopus SJRQ1A novel algorithm based on DNA coding for substitution box generation problem
Artuğer, Fırat
Substitution boxes are very important for cryptographic structures. But getting an 8-bit strong s-box is a difficult problem. To address this problem, a new approach is proposed in this study. DNA chains are used in the proposed approach. First of all, a weak s-box is obtained with the help of a chaotic map. Then, a DNA chain is formed with the same chaotic map. In this study, 2000-long DNA chains were produced. Then, two random values consisting of four components are determined from these DNA chains, and these values are addressed to the s-box structure. By changing the places of these values, the s-box structure is improved up to a certain iteration. In this study, 10,000 iterations were examined, and three different strong s-boxes were obtained by using three different DNA chains. The nonlinearity values of these s-box structures were observed as 110.25, 110.5, and 110.75, respectively. The proposed study has proven to work effectively with effective results in three different chains. In addition, it has been proven as a result of the analysis that the proposed s-box structures also have other cryptographic features. The proposed algorithm has surpassed many s-box generation philosophies in the literature. In addition, the proposed algorithm will provide serious gains to cryptographic structures that will be developed in the future.
AtıfScopus21WoS22OpenAlex24İncele - MakaleYalnız künye2025Scopus SJRQ2Two new moss records for Turkey and Southwest Asia
Ezer, Tülay; Aslan Ergenekon, Züleyha; Uygur, Ahmet; Keskin, Ali; Alataş, Mevlüt; Batan, Nevzat
Hymenoloma mulahaceni and Mnium blyttii found as new to Turkey following a recent bryological excursion to the Bolkar Mountains (Taurus Mountain range) in Turkey. Also, this is the first record of the Mnium blyttii from Southwest Asia. Illustrations, geographic distributions, ecological characteristics, identification keys and comparisons with morphologically similar taxa are given.
- MakaleYalnız künye2024Scopus SJRQ2Degradation Products of Rhyolitic Rocks, Adsorption Applications, Isotherm Studies
Fırat, Tülay; Sarıcı-Özdemir, Çiğdem
Heavy metals and their toxicity are a major global concern. They are one of the major environmental problems causing serious problems for living beings. In this study, the adsorption properties of a clay sample located in nature are improved by treating with different materials, and then adsorption properties are examined. It is observed that clay sample can be used in many adsorption applications, including the adsorption of heavy metals such as copper. The clay mineral used in the study was obtained from a rhyolite type rock. Rhyolite rocks, one of the degradation products of volcanic rocks, are the volcanic counterparts of granite. In this study, rhyolite rock was crushed with suitable crushers and grinders, then sieved under 200 mesh with molecular sieve and clay minerals were obtained. The clay samples (K1,K2. K8) were synthesized by subjecting clay with acid and base. Adsorption properties of clay are due to wide surface area, surface functional groups and microporosity. Adsorption of methylene blue and iodine, adsorption from aqueous solutions of copper are done with clay samples and results were compared with samples of clay have not undergone any pre-treatment. In the study, the highest adsorption capacity was determined by applying the Freundlich isotherm. In the K6 sample treated with a base, the highest adsorption capacity was calculated as 26.98 Lg−1. In contrast, the Langmuir isotherm results were calculated in the range of 10.56 to 11.86 Lg−1. This indicates that the adsorption takes place on a heterogeneous surface. The structure and surface properties of clay were examined.
AtıfScopus2WoS2OpenAlex2İncele - MakaleAçık Erişim2023Scopus SJRQ1Orbitrap Mass Spectrometry-Based Profiling of Secondary Metabolites in Two Unexplored Eminium Species and Bioactivity Potential
Babacan, Ebru Yuce; Zheleva-Dimitrova, Dimitrina; Gevrenova, Reneta; Bouyahya, Abdelhakim; Balos, Mehmet Maruf; Cakilcioglu, Ugur; Sinan, Kouadio Ibrahime; Zengin, Gokhan
The study aimed at the metabolite profiling and evaluation of antioxidant and enzyme inhibitory properties of methanol extracts from flowers, leaves, and tubers of unexplored Eminium intortum (Banks & Sol.) Kuntze and E. spiculatum (Blume) Schott (Araceae). A total of 83 metabolites, including 19 phenolic acids, 46 flavonoids, 11 amino, and 7 fatty acids were identified by UHPLC-HRMS in the studied extracts for the first time. E. intortum flower and leaf extracts had the highest total phenolic and flavonoid contents (50.82 ± 0.71 mg GAE/g and 65.08 ± 0.38 RE/g, respectively). Significant radical scavenging activity (32.20 ± 1.26 and 54.34 ± 0.53 mg TE/g for DPPH and ABTS) and reducing power (88.27 ± 1.49 and 33.13 ± 0.68 mg TE/g for CUPRAC and FRAP) were observed in leaf extracts. E. intortum flowers showed the maximum anticholinesterase activity (2.72 ± 0.03 mg GALAE/g). E. spiculatum leaves and tubers exhibited the highest inhibition towards α-glucosidase (0.99 ± 0.02 ACAE/g) and tirosinase (50.73 ± 2.29 mg KAE/g), respectively. A multivariate analysis revealed that O-hydroxycinnamoylglycosyl-C-flavonoid glycosides mostly accounted for the discrimination of both species. Thus, E. intortum and E. spiculatum can be considered as potential candidates for designing functional ingredients in the pharmaceutical and nutraceutical industries.
AtıfScopus15OpenAlex11
İncele - MakaleAçık Erişim2024Scopus SJRQ1Integrating discrete-event simulation and artificial intelligence for shortening bed waiting times in hospitalization departments during respiratory disease seasons
Ortiz-Barrios, Miguel; Ishizaka, Alessio; Barbati, Maria; Arias-Fonseca, Sebastián; Khan, Jehangir; Gul, Muhammet; Yücesan, Melih; Alfaro-Saíz, Juan-Jose; Pérez-Aguilar, Armando
Seasonal Respiratory Diseases (SRDs) usually produce a heightened number of Emergency Department (ED) attendances due to their rapid dissemination within the community and the ineffective prevention measures. Such a context requires effective management of the emergency care processes to provide in-time diagnosis and treatment to infected patients. Nonetheless, EDs have evidenced severe operational deficiencies during these periods, thereby provoking extended bed waiting times in Hospitalization Departments (HDs). Therefore, this paper presents a hybrid approach merging Artificial Intelligence (AI) and Discrete-Event Simulation (DES) to shorten the bed waiting times in HDs considering patient records collated in the first emergency care stages. First, we implemented Random Forest (RF) to estimate the probability of respiratory worsening based on sociodemographic and clinical patient data. Second, we inserted these probabilities into a DES model mimicking the emergency care from the admission to the HD. We then pretested different HD configurations and strategies seeking to reduce the HD bed waiting time. A case study of a European hospital group was used to validate the suggested framework. The AI-DES model enabled decision-makers to identify an improvement proposal with hospitalization bed waiting time lessening, oscillating between 7.93 and 7.98 h.
AtıfScopus16OpenAlex17İncele - MakaleYalnız künye2023Scopus SJRQ1Latent heat thermal energy storage in a shell-tube design: Impact of metal foam inserts in the heat transfer fluid side
Ghalambaz, Mehdi; Sheremet, Mikhail; Raizah, Zehba; Akkurt, Nevzat; Ghalambaz, Mohammad
The improvement of heat transfer in latent heat thermal energy storage (LHTES) system is a crucial task. In the current study, the impact of diverse metal foam (MF) layer arrangements on heat transfer fluid (HTF) within a shell-tube LHTES is explored. Six distinct cases (A-F) with varied MF coverage percentages and layer dimensions were assessed. The local thermal non-equilibrium model was utilized to take into account the PCM and MF temperatures. The finite element method was used for solving the partial differential equations. The impact of MF configurations and inlet pressures (250 Pa, 500 Pa, and 750 Pa) on the thermal energy storage/release was addressed. Cases A-C, featuring a 50 % MF concentration, exhibit shorter melting times than Cases D–F, with decreasing MF concentrations. A higher MF concentration improves the melting process due to increased thermal conductivity and lower thermal resistance on the HTF side. Cases D–F, with a centralized MF layer and decreasing concentrations from 25 % to 6.25 %, display progressively shorter melting times, suggesting that a lower MF concentration leads to more efficient melting. Solidification times also decrease with increasing inlet pressures across all cases. Reynolds numbers, influenced by average HTF tube outlet velocity, vary substantially across cases and inlet pressure differences. Cases A-C demonstrate similar Reynolds numbers for each inlet pressure difference, while Cases D–F show a more pronounced increase in Reynolds numbers as the MF layer is reduced and flow resistance drops. Cases A (50 % MF layer) and F (6.5 % MF layer) provide the quickest charging and discharging times due to their unique combination of MF layer properties and inlet pressures. The study highlights the need to consider MF layer composition and inlet pressure when designing optimal LHTES systems for efficient energy storage/release.
AtıfScopus11WoS10OpenAlex11İncele - MakaleAçık Erişim2025Scopus SJRQ3Cu, Fe, Mn AND Zn CONTENTS IN PROPOLIS SAMPLES FROM MALATYA, TÜRKİYE AND HEALTH RISK ASSESSMENT; [MALATYA, TÜRKİYE ARI PROPOLİSİNDEKİ CU, FE, MN VE ZN İÇERİKLERİ VE SAĞLIK RİSK DEĞERLENDİRMESİ]
Karaaslan Ayhan, Nagihan
In this study, copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) contents of propolis samples obtained from five different districts of Malatya, Türkiye were investigated. Element contents were determined using flame atomic absorption spectrometry (FAAS). The concentration ranges of propolis samples taken from five different districts of Malatya province varied between 1.24 ± 0.06 mg/kg and 6.28 ± 0.02 mg/kg for Cu, 206.28 ± 21.50 mg/kg and 663.08 ± 55.24 mg/kg for Fe, 15.40 ± 0.17 mg/kg and 27.11 ± 1.83 for Mn, 39.36 ± 1.82 mg/kg and 52.57 ± 2.13 mg/kg for Zn. The results obtained for each district and element were evaluated in detail considering the estimated daily intake (EDI), recommended dietary allowance (RDA), provisional maximum tolerable daily intake (PMTDI) of these elements for adults. Moreover, hazard coefficient (HQ) was calculated for risk assessment and it was determined that HQ values for the studied elements in bee propolis from all districts were below 1.
- MakaleAçık Erişim2024Scopus SJRQ4EFFECT OF EXTENDER AND DILUTION RATIO ON THE SPERM MOTILITY, VIABILITY, AND EGGS FERTILITY OF CLARIAS BATRACHUS, LINNAEUS 1758 (PISCES: CLARIIDAE)
Handayani, Luvi S.; Maulida, Siti; Rahayu, Sri R.; Razi, Nanda M.; Kocabas, Mehmet; Kocabas, Filiz K.; Eriani, Kartini; Fadli, Nur; Siti-Azizah, Moh N.; Marimuthu, Kasi
The study aims to determine the type of extender and the best dilution ratio for short preservation walking catfish Clarias batrachus sperm at a refrigeration temperature of 4°C. The study employed a completely randomized design with two factors, each consisting of 6 treatments and 3 replications. The experiments were divided into 2 stages: the first stage tested several types of extenders, namely tap water, Ringer’s solution, physiological solution, Alsever’s solution, urea solution, and glucose base solution, all at the same dilution level of 1:20 (sperm: extender, v/v). The second stage examined various levels of sperm dilution ratios, namely 1:10, 1:20, 1:30, 1:40, 1:50, and 1:60 (sperm: extender, v/v). The samples were stored at a refrigerated temperature of 4°C. Furthermore, motility and viability were monitored at 24-hour intervals for next 6 days, and on the final day of the experiment. The ANOVA test showed that the type of extender and dilution ratio significantly affected the motility and viability of the spermatozoa and percentage of fertilization (P < 0.05). Generally, the quality of sperm decreased after preservation for 144 hours at 4°C, but diluted with Ringer solution at a ratio of 1:40 (sperm: extender, v/v), still maintains good parameters. Therefore, it is recommended that Ringer’s solution at a dilution ratio of 1:40 is suitable for preserving walking catfish C. batrachus sperm at a refrigerated temperature of 4°C.
AtıfScopus1İncele - MakaleYalnız künye2024Scopus SJRQ1Lanthanum-based magnetic biopolymers for brilliant green removal from aqueous solutions
Karaaslan Ayhan, Nagihan
In this study, lanthanum (La)-based magnetic biopolymers were synthesized, and the first adsorption study was conducted on the removal of brilliant green dye from aqueous water with these biopolymers. For the adsorption study, adsorption parameters were investigated and the ideal adsorption conditions determined for the removal of brilliant green dye from aqueous solutions are pH 11, t 60 min, m 10 mg, C0 25 mg/L, T 298 K. It was determined that the adsorption process was compatible with the single-layer Langmuir isotherm, and maximum adsorption capacity obtained according to the Langmuir isotherm was calculated as 256.41 mg/g. The adsorption process was found to be in accordance with the pseudo-second-order, and the adsorption process was explained by intra-particle diffusion. According to studies of adsorption thermodynamics, it has been established that the nature of the adsorption reaction is spontaneous, and this process is endothermic and has increasing randomness. Moreover, the reusability of magnetic lanthanum/alginate (La/Alg) biopolymers was investigated, and it was determined that the biopolymers could be used successfully. In summary, brilliant green dye has been successfully removed with simple, low-cost, environmentally friendly, and easily obtained magnetic La/Alg biopolymers. It can be stated that even low amounts of these biopolymers can be effective in the treatment of highly concentrated dye wastewaters.
AtıfScopus1OpenAlex1İncele - MakaleAçık Erişim2023Phycoremediation of Thallium Toxic Metal Present in Gallery Water of an Abandoned Mine Area by Algae Cladophora fracta
Topal, Murat; Arslan Topal, E. Işıl; Öbek, Erdal
In this study, phycoremediation of thallium toxic metal present in galery water of an abandoned mine area was investigated by using Cladophora fracta. Within the scope of the study, a reactor containing Cladophora fracta was used and it was determined whether the Cladophora fracta accumulated thallium depending on time. Additionally, the bioconcentration factor was calculated. According to research findings; the accumulations of thallium by Cladophora fracta, compared with uncontaminated alga, were 225% at 5 min, 450% at 10 min, 550% at 20 min, 575% at 40 min, 700% at 60 min, and 900% at 120 min, respectively. BCF values were between 1000-5000. This indicated that Cladophora fracta had bioaccumulation potential. As a result, this research carried out in mining area has documented the phycoremediation of thallium in gallery water of an abandoned mine area.
- MakaleAçık Erişim2024Scopus SJRQ2Development of rare earth element and carbon fiber-based filler for polyethylene—Mechanical and thermal performance
Kısmet, Yılmaz; Ayikurt, Pamuk
In the present study, three fillers produced with carbon fiber powder (CFP) and rare earth elements were developed for low-density polyethylene production. These fillers included CFP with a grain size of less than 400 microns and over 90% pure lanthanum and cerium oxides. Polyethylene was employed to ensure the thermoplasticity and homogeneity of the fillers. The fillers were mixed with the matrix material separately, first mechanically and then homogenously in the extruder, then the test bars were produced with an injection machine. In the mechanical tests, it was determined that the tensile strength of the test bars improved by ~20% and the elastic region increased due to the increasing amount of filler. Similarly, an improvement of about 40% in bending stress was realized. In addition, as the fluidity of the mixtures has improved, it has been possible to produce at lower temperatures and save energy in the production. Thermogravimetric analysis was conducted to determine the melting/crystallization temperatures and material losses in the compounds. The scanning electron microscope analysis showed that the fillers were irregularly distributed on the surface in parallel and perpendicular directions. In addition, x-ray diffraction and energy dispersive spectroscopy analyses were performed on the surfaces.
AtıfScopus1WoS1OpenAlex1İncele - BildiriAçık Erişim2024Classifying induction motor faults using spectrogram images with deep transfer learning
Ertargin, Merve; Yildirim, Ozal; Orhan, Ahmet
For industrial systems to be reliable and efficient, motor faults detection is important. Conventional methods of fault detection are typically expensive and time-consuming. The ability to detection motor faults has advanced significantly in recent years thanks to the application of deep learning techniques. Deep learning algorithms have the ability to automatically extract complicated features from big data sets, which can speed up and improve the accuracy of motor faults detection. Since collecting motor acoustic data is cost-effective and easy, it is advantageous to use it in fault detection. In this study, motor acoustic signals were converted into spectrograms and faults in induction motors were detected using a transfer learning approach with pre-trained models. Totally 8-class fault detection was performed with an accuracy rate of 91.52% using VGG16 and 92.11% using VGG19.
AtıfScopus4OpenAlex4İncele - MakaleAçık Erişim2024Scopus SJRQ2Photoresponse, thermal and electrical behaviors of MXene-based polysulfone nanocomposite
Demirelli, Kadir; Barim, Esra; Çelik, Aytekin; Yegin, Mustafa; Aksoy, Yunus; Hanay, Özge; Hasar, Halil
The Ti3C2Tx MXene nanosheet was prepared by 40% (v/v) hydrofluoric acid etching at 20 °C for 48 h and delamination of bulk MAX Ti3AlC2 precursor material. A 2D nanomaterial MXene Ti3C2Tx as a nanofiller was introduced to polysulfone (PSulfone) matrix. MXene and PSulfone/MXene nanocomposite systems were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope, Fourier-transform infrared and thermogravimetric analysis instruments. Dielectric and electrical characterization of PSulfone/MXene nanocomposite was carried out. The electrical resistance of Ti3C2Tx MXene from measurement current (I)–voltage (V) was measured as 116 Ω. Pure PSulfone matrix exhibits typical insulator behavior, and MXene exhibits a good conductor behavior. But, when MXene was added to the pure PSulfone matrix, the resistance of the MXene/PSulfone nanocomposite increased moderately compared to that of pure MXene. In spite of the excess of surface functional groups, MXene showed surprisingly good electron transport across the surface, while in the case of PSulfone/MXene nanocomposite, the insulating behavior of PSulfone significantly reduced the electron transport of MXene. The semiconductor behavior of PSulfone/Ti3C2Tx MXene nanocomposite indicates that MXene provides efficient charge carrier transfer in the nanocomposite system. By comparing the TGA results between the PSulfone and different weight ratios of PSulfone/Ti3C2Tx MXene nanocomposites, it was determined that MXene nanosheets had a significant effect in slightly accelerating the thermal degradation of PSulfone. Optical conductivity was investigated by preparing a film of PSulfone/MXene nanocomposite on an interdigital contact. It was observed that the optical current values changed depending on the increasing illumination intensity. Considering current–voltage measurements, the photocurrent generation potential of PSulfone/MXene nanocomposite shows that it can be used in photodevice production.
AtıfScopus24OpenAlex27İncele - MakaleYalnız künye2023Scopus SJRQ2Does surgery cause anxiety, stress and fear in geriatric patients?
Karabulut, Neziha; Gürçayır, Dilek; Abi, Özlem; Kızıloğlu Ağgül, Beyzanur; Söylemez, Nilgün
Background: Because of physiological changes in geriatric patients, their surgical process differs from that of young adults. In this regard, the perioperative period is an extremely risky time for geriatric patients. The present study examined preoperative fear, anxiety, and perceived stress levels as well as the factors affecting them in elderly patients prior to surgical intervention. Methods: This study adopted a cross-sectional descriptive design. The study sample consisted of geriatric patients (n = 407) scheduled for elective laparoscopic cholecystectomy in a research and training hospital in northeast Turkey. Data were collected by the researchers using the personal information form, Perceived Stress Scale (PSS-10), Surgical Fear Questionnaire (SFQ) and Anxiety Specific to Surgery Questionnaire (ASSQ). In the data analysis, descriptive statistics, the t-test in independent groups, one-way analysis of variance (ANOVA), correlation analysis and Bonferroni tests for post hoc analyses were used. Results: On the PSS–10, the mean score was higher for the 75-and-older age group, single patients, patients with a disease requiring medication, and those who had previously undergone surgery (P < 0.05). On the ASSQ, the mean score was lower for patients aged 65–69, university graduates, patients without children, and those without a disease requiring medication (P < 0.05). On the SFQ, the mean score was higher for the 75-and-older age group, primary school graduates, and single patients (P < 0.05). Conclusion: It was determined that being single, having a chronic disability, and advancing age had an effect on the patients' surgery-specific anxiety, perceived stress, and fear of surgery. Long-standing chronic diseases can negatively affect both stress and anxiety levels of individuals.
AtıfScopus14WoS13OpenAlex13İncele - MakaleAçık Erişim2024Scopus SJRQ4Effect of naproxen on oxidative stress biomarkers in Gammarus pulex; [Efecto del naproxeno sobre los biomarcadores de estrés oxidativo en Gammarus pulex]
Seker, Engin
Non–steroidal anti–inflammatory drugs (NSAIDs) are a widely prescribed medication class that is used in the treatment of numerous conditions worldwide. Of these drugs, naproxen is the most commonly used NSAID. Following administration, non–steroidal anti–inflammatory drugs (NSAIDs) such as naproxen are eliminated from the body in either their original chemical form or as metabolites, ultimately entering the aquatic environment. The current study sought to show the impacts of naproxen on the oxidant/antioxidant status of Gammarus pulex, an aquatic invertebrate (Amphipoda). Gammarus pulex were exposed to sublethal concentrations of naproxen (3.44, 6.87 and 13.75 mg·L-1) for 96 hours (h). Whole body tissue samples were collected after 24, 48 and 96 h of exposure and analysed to determine the oxidant/antioxidant status by quantifying malondialdehyde (MDA) and total glutathione levels (GSH), and superoxide dismutase (SOD), and catalase (CAT) activities of the G. pulex. The level of MDA exhibited a remarkable increase, while the endogenous GSH level showed a significant depletion in tested whole body tissues in a time–dependent manner after naproxen treatment of G. pulex. In G. pulex exposed to the highest dose of naproxen; decreases in GSH activity, SOD and CAT activities were observed.The SOD activity did not show a discernible rise in statistics after 24 and 48 h of exposure, however, a difference was observed after 96 h compared to the control group (P<0.05). The findings of this study demonstrated the capacity of naproxen to initiate oxidative stress and elevate MDA levels in G. pulex, even at remarkably low concentrations. This study emphasizes that it is essential to develop effective methodologies to impede naproxen entry into the aquatic environment.
- MakaleYalnız künye2023Scopus SJRQ2Engineering Properties of Geopolymer Mortars Containing Industrial Steel Shavings
Gülmez, Nihan; Koçkal, Niyazi Uğur
The purpose of using waste materials is to prevent the unnecessary use of resources and to reduce the amount of waste. Geopolymer, developed as an alternative to cementitious materials, prevents the depletion of natural resources and saves a large amount of energy. This paper presents the effect of waste steel shavings on the improvement of physical and mechanical properties of geopolymer mortars. For this purpose, geopolymer mortars were produced by using two binder types [slag (BFSb) and silica fume] as well as steel shavings in five different replacement percentages (0%, 2.5%, 5%, 7.5% and 10%) by volume instead of aggregate. A series of experiments on geopolymer mortars were carried out to determine properties such as bulk density, water absorption, apparent porosity, sorptivity coefficient, splitting tensile strength, flexural strength and compressive strength. Results showed that steel shavings recovered from metal processing and forming sector were highly effective at improving engineering properties of geopolymer mortars. Furthermore, although replacement of 20% by volume of BFSb with silica fume improved properties of geopolymer mortar, it was observed that the use of silica fume at higher ratios reduced mechanical properties by increasing porosity and sorptivity of BFSb-based geopolymer mortars.
AtıfScopus1OpenAlex1İncele - MakaleYalnız künye2024Scopus SJRQ1Investigation of the variation of mechanical and durability properties of elements manufactured with rubber substituted SCMs with element height
Akgül, Melek; Etli, Serkan
Controlling the homogeneous distribution of granulated rubber materials added to self-compacting concrete/mortars along the height is of great importance in terms of preserving and defining the holistic behavior of structural elements. In this study, the effect of EPDMGR (ethylene propylene diene monomer granulated rubber) ratio (0 %, 5 %, 10 %, 15 %, 20 % and 25 %), test age, L/D (slenderness ratio) and element test zone (bottom, middle and top) on the mechanical properties (flexural and compressive), durability properties (porosity and sorptivity) of the elements produced with SCM were evaluated. The results obtained were statistically evaluated by GLM-ANOVA. It was observed that flexural tensile strength was strengthened up to 5 % substitution rate due to the hydrophobic properties and elasticity properties of EPDMGR used, while porosity values increased with height in the upper regions compared to the lower regions due to the placement properties of SCM. Differences in compressive strength appeared in the upper and lower sections after 5 % EPDMGR substitution. This indicates that for the mixture properties used, the properties examined in terms of mechanical and durability test results may have different properties with limited variability in terms of L/D ratio depending on the EPDMGR ratio used and the region where the element was taken.
AtıfScopus7WoS7OpenAlex10İncele - MakaleAçık Erişim2025Scopus SJRQ3Role of tungsten oxide (WO3) on thermal and optical properties of smart polymer composites
Aydın, Handan; Özen Öner, Ecem; Aydın, Cihat
Tungsten oxide, a versatile transition metal with numerous polymorphs and sub-stoichiometric compositions, containing inherent tunnels and oxygen vacancies, has become a current field of study due to its rich crystal structure, high electrochemical stability, easy accessibility, and environmental friendliness. Thus, the versatile structure of WO3-based materials makes them promising candidates for advanced applications. Our study aims to provide valuable insights into the performance of these materials used in various fields. The structural, optical, and thermal characteristics of PVC-PCL composites doped with tungsten oxide (WO3) were examined in this work. According to DSC research, the thermal characteristics of the polymer matrix were significantly impacted by the addition of WO3. The thermal stability was found to have increased based on the TGA measurement findings. XRD analyses revealed that as the doping rate increased, improved crystallinity was seen. According to SEM tests, the grain clusters are uniformly mixed and the tungsten oxide is evenly spread across the surface. The dopant reacted either chemically or physically with the polymer matrix, according to the ATR-FTIR spectra of PVC-PCL matrix nanocomposite films. An improvement in conductivity with an increase in dopant concentration was noted in the optical experiments. Thus, it can be stated that PVC-PCL composites doped with WO3 can be used in optoelectronic, various industrial, and biomedical application areas due to their structural, optical, and thermal properties.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2023Scopus SJRQ3Rotor Field-Oriented Control of Doubly Fed Induction Generator in Wind Energy Conversion System
Omac, Zeki; Erdem, Irfan
In this study, robust and high-performance vector control of a rotor side converter (RSC) was performed for stability and efficient operation doubly fed induction generator (DFIG) based on the variable speed wind turbine (VSWT). The mathematical model of the DFIG is simulated in the computer. Amplitude and frequency of the voltage in the DFIG were controlled for different values of load and variable speeds. In the experimental study, a DFIG-based wind turbine system was set up in the laboratory. The field position of the stator was detected from stator voltages by a phase-locked loop (PLL) circuit. The rotor position was measured with an incremental encoder connected to the rotor shaft of the DFIG. The angular position of the slip was calculated by the difference between the rotor and the stator field positions. The frequency and amplitude of rotor currents were determined with the angular position of slip. To generate output voltages of converter feeding rotor windings, the space vector pulse width modulation (SVPWM) technique was used. In the experimental study, the RSC was controlled with the DS1103 board. The prepared experiment set was tested at different operating speeds.
AtıfScopus4WoS3OpenAlex4
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