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Koleksiyondaki öğeler
- MakaleAçık Erişim2021Scopus SJRQ1Performance of AC overlays using geogrids on PCC contraction joints
Çelik, Muhammet; Seferoğlu, Mehmet Tevfik; Akpınar, Muhammet Vefa
It is widely known that vertical displacements and strains occur on the joints and these cause defects on the asphalt concrete (AC) overlays on existing Portland cement concrete (PCC) pavements. Various approaches were introduced to minimize these defects. In this study, the effect of joint support formed using the geogrid material with grout mortar on the vertical displacement of PCC and the strain at the bottom of the AC layer. Produced layers were exposed to 1,186,000 Equivalent Single Axle Load (ESAL) in an APT (Accelerated Pavement Test) facility and the results were monitored. According to the obtained results, the use of AC overlay reduces vertical displacement in the PCC by 75%. When geogrid reinforced AC overlay was used, an additional reduction in displacement by 41.2% was achieved. Geogrid reinforcement reduced strain values formed at the bottom of the AC layer from 29.5% to 92.5%. The use of geogrid at joints instead of increasing the thickness of the AC layer from 50 to 80 mm resulted a more significant reduction in both strain and displacement. Besides, the usage of a geogrid interlayer instead of increasing the thickness of the AC layer also provided a significant cost reduction of 57.9% in overall cost.
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İncele - MakaleYalnız künye2021Scopus SJRQ1Extraction of Metals from Scrap Marble Cutting Segments in Nitric Acid Solutions
Celep, Oktay; Orak, Mürsel; Yazici, Ersin Y.; Deveci, Hacı
Extraction of cobalt, copper, and silver from scrap saw-blade segments using nitric acid solutions (0.1–0.4 M, 20–60°C) were investigated using response surface methodology. Extraction of cobalt and iron was more extensive than copper and silver, i.e., 35.7–96.2% Co and 72.6–100% Fe versus 8.50–35.4% Cu and 8.11–22.5% Ag. Statistical analysis of the experimental data has shown that increasing the acid concentration or temperature enhances the rate and extent of leaching of metals. Under suitable conditions, almost complete leaching of cobalt (99.9%), as well as high extractions of copper (95.9%) and silver (94.9%), were achieved. The activation energy, calculated to be 40.3 kJ/mol, indicates that nitric acid leaching of these metals occurs as a chemically controlled reaction. These findings have demonstrated that nitric acid as an effective oxidant/leaching agent could be suitably used for the extraction of cobalt, copper, and silver from scrap segments.
AtıfScopus4WoS3OpenAlex4İncele - MakaleAçık Erişim2022The Effect of Unemployment and Urbanization on Migration in Turkey: An Evaluation in terms of the Harris-Todaro Model; [Türkiye’de İşsizlik ve Kentleşmenin Göç Üzerindeki Etkisi: Harris-Todaro Modeli Açısından Bir Değerlendirme]
Sancar, Canan; Akbaş, Yusuf Ekrem
This study tested whether there was a relationship between migration, unemployment, and urbanization based on the Harris-Todaro model in 12 regions of Turkey, which were formed according to NUTS-1 classification, in the period between 2008 and 2019. For this purpose, panel data methods that consider cross-section dependency were used in the study. As a result of the analysis, it was concluded that the Harris-Todaro model was valid in TR1, TR2, TR3, TR4, TR5, and TR6 regions. In TR7, TR8, TR9, TRA, TRB, and TRC regions, it was found that the Harris-Todaro model was not valid.
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İncele - MakaleYalnız künye2021Scopus SJRQ2N epeta meyeri essential oil ameliorates fungal infection and the antioxidant response in grapevines (Vitis vinifera) infections by gray mold (Botrytis cinerea)
Karakuş, Sinem; Atici, Ökkeş; Köse, Cafer; Aydin, İhsan
The essential oil (EO) obtained from Nepeta meyeri Benth. used to struggle allelopathically with gray mold (Botrytis cinerea Pers.), which causes significant damage to vineyards (Vitis vinifera L. cv. Karaerik). The EO from N. meyeri was determined to contain 4aα, 7α, 7aα-nepetalactone (71.68%) at the highest rate when analyzed with GC/MS. Then, the doses (0.6, 0.8, and 1.0 µL/leaf) of 1 ppm EO solution were applied to the leaves together with the fungus inoculation (EO + F), as well as 1 day (EO + F1D) and 2 days (EO + F2D) before inoculation. The fungus application alone was evaluated as a control. Seven days after the inoculations, fungus development, lipid peroxidation level (as malondialdehyde), the contents of reactive oxygen species (ROS), photosynthetic pigments and soluble proteins, and the activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, and glutathione reductase) were determined in the leaves. Findings revealed that EO + F1D among the applications and 1.0 µL/leaf among the EO doses significantly prevented fungus development on the leaf, compared to the control. Moreover, the same applications decreased ROS levels, such as H2O2 and O2·− and lipid peroxidation, while they increased antioxidant enzyme activities, as well as chlorophyll and soluble protein contents. Therefore, it can be suggested that the EO from N. meyeri has a potentially powerful usage as biofungicide in the allelopathic struggle against the infection of B. cinerea in vineyards.
AtıfScopus5WoS4OpenAlex6İncele - MakaleAçık Erişim2020Scopus SJRQ2Multi-criteria decision making approach based on PROMETHEE with probabilistic simplified neutrosophic sets
Altun, Fatma; Şahin, Rıdvan; Güler, Coşkun
Probabilistic simplified neutrosophic set (PSNS) is an important tool to describe the vagueness existing in the real life. In this study, we define a PSNS and discuss some of theoretical set operations of PSNSs. Also we propose the concepts of module on PSNSs, as well as inner product and projection operator between two PSNSs. In relation to this new set, we introduce a probabilistic simplified neutrosophic number (PSNN). A PSNN has three components which is called probabilistic-valued truth membership degree, probabilistic-valued indeterminacy membership degree and probabilistic-valued falsity membership degree, respectively. We give some of algebraic operational rules, a score function and an accuracy function on PSNNs. Furthermore, we introduce two aggregation operators called the probabilistic simplified neutrosophic weighted arithmetic average operator and the probabilistic simplified weighted geometric average operator on PSNNs. Furthermore, we determine weights of criteria with a method that is based on fuzzy measure and develop a method based on preference function to determine weight of each decision maker. We present an extended PROMETHEE method based on PSNSs for group decision problems. Finally, as an application of this theory, we give a practice on a multi-criteria group decision making problem based on PSNNs by using extended PROMETHEE method to ensure stability of the proposed method.
AtıfScopus40WoS18OpenAlex28İncele - MakaleYalnız künye2021Scopus SJRQ2The impact of export dynamics on trade balance in emerging and developed countries: An evaluation with middle income trap perspective
Akbas, Yusuf Ekrem; Sancar, Canan
In this study, it was analyzed whether the export dynamics affected net exports in fourteen emerging countries and eight developed countries between the years of 1995–2019. Export sophistication, export product diversification, export market diversification, export product concentration, export market concentration, and real effective exchange rate were used as the proxy of export dynamics. Panel data methods that take into account cross-section dependency and structural breaks were used for the analysis. As a result of the study, in developed countries, it was concluded that export sophistication, export product concentration, and export market diversification positively affected the net export, and the real effective exchange rate negatively affected the net export. For the emerging countries, it was concluded that export market concentration and real exchange rate negatively affected the net exports. Also, in emerging countries, it was found that export sophistication and export product diversification do not have any impact on net exports since export sophistication and export product diversification are not an adequately high level compared to developed countries for increasing the net export. The fact that in these countries the proportion of high-tech product exports are low in total exports and the product range in exports are not wide cause these indexes to be low. This situation poses a significant risk in terms of falling into the middle-income trap.
AtıfScopus19WoS12OpenAlex23İncele - MakaleAçık Erişim2021Scopus SJRQ3Satellite-derived shallow wetland bathymetry using different classification algorithms and datasets
Dervisoglu, Adalet; Yagmur, Nur; Bilgilioglu, Burhan Baha
Remote sensing (RS) effectively identifies, analyzes, and monitors wetlands. In addition to these two-dimensional studies, RS is used with several techniques in determining shallow water depths. The primary purpose of this study is to obtain shallow wetland bathymetry utilizing spectral reflections obtained at different water depths by field study and satellite images. Machine learning (ML) algorithms, which are widely used in remote sensing, are used in this study. Four algorithms were selected as random forest (RF), support vector machine (SVM), Neural Networks (NN), and Maximum Likelihood Classification (MLC). Since machine learning algorithms use training samples/datasets, the classification accuracy is directly related to selecting these data. The effect of pixel counts on classification was investigated by using two different training data set also. Duden (Kulu) Lake, which is a shallow wetland, was chosen as the study area. The Iterative Self-Organizing Data Analysis Technique (ISODATA) classification algorithm divided into as many clusters as possible was applied on Sentinel-2 multispectral images. All classes were rede-fined using measured spectral signatures and were created a bathymetric map. This map was used as reference data in creating training sets and the accuracy assessment of ML algorithms. When the water surface areas obtained from algorithms were compared with the bathymetric map and Normalized Difference Water Index, the best result was obtained with RF. According to the accuracy assessment results, it was seen that the number of training data affects the accuracy, and the best results were obtained with SVM and RF algorithms with training data containing more pixels (overall accuracy 93.87% and 92.64, kappa 0.89 and 0.87, respectively).
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2021Scopus SJRQ2High-resolution total field magnetic anomaly maps of Lake İznik (NW Turkey): assessment of faults which play important roles in tectonics of the lake
Aktaş, Gülten; Hisarli, Z. Mümtaz; Demirel, A. Sinan
In total, 380 km of marine magnetic data were processed and interpreted to reveal the main tectonic elements that control the formation of the lake. Lake İznik, which is an approximately rectangular-shaped active tectonic basin with 32 km length and 12 km width, is located between two segments of the North Anatolian Fault in the northeast Marmara region, Turkey. The purpose of this study is to identify the tectonic elements that played a role in the formation of Lake İznik with the help of new magnetic data and to reveal the tectonic evolution of the region by using other previously collected geophysical data. The Euler deconvolution, tilt angle, analytic signal and source edge detection methods were applied to the total field magnetic data for Lake İznik and its surroundings to determine the boundaries and depths to the source of magnetism. From the structural map obtained as a result of the review of this data, linearity in the magnetic data was detected along the NW–SE direction in the north of Lake İznik, N–S direction in the west and east, and E–W direction in the south. These lineaments were correlated with a limited amount of seismic data obtained from previous studies and were associated with faults. This linearity in NW–SE direction in the north was evaluated as the continuation of the Orhangazi fault and it is thought to play a significant role in the tectonic evolution of Lake İznik. When the results obtained from this study and the paleomagnetic results for the Eocene volcanic rocks in the study area are evaluated together, Lake İznik was connected with Gemlik Bay and the Marmara Sea during the Eocene–Pleistocene and Orhangazi Fault disconnected Lake İznik from Gemlik Bay in the Pleistocene–Holocene. It was deduced that the lake basin is a pull-apart basin developed up to the present day.
AtıfScopus4WoS3OpenAlex5İncele - MakaleAçık Erişim2020Scopus SJRQ4The mediating role of self-compassion in the relationship between perceived COVID-19 threat and death anxiety; [Algılanan COVID-19 tehdidi ve ölüm kaygısı arasındaki ilişkide öz şefkatin aracı rolü]
Kavaklı, Mehmet; Ak, Mehmet; Uğuz, Faruk; Türkmen, Osman Oğulcan
Objective: The COVID-19 pandemic is a new and highly detrimental event that has influenced the world over. Besides the obvious health risks, COVID-19 has also affected people psychologically. The high risk of contamination can increase the perceived COVID-19 threat and death anxiety in individuals. The aim of the present study was to investigate the mediating role of self-compassion in the relationship between perceived COVID-19 threat and death anxiety. Additionally, the study also investigated the role of gender, profession and income level in the perceived COVID-19 threat and death anxiety. Method: The research sample was composed of 562 individuals from the community. The data was gathered by using personal information form and the Perceived COVID-19 Threat Form, Self-Compassion Scale and Turkish Death Anxiety Scale. Results: The relationship between perceived COVID-19 threat and death anxiety was partially mediated by self-compassion. Moreover, people in the high income group had a lower level of perceived COVID-19 threat and death anxiety score compared to the low-income group. Perceived COVID-19 threat levels were lower among health care professionals compared to unemployed individuals. Female participants had a higher level of perceived COVID-19 threat and death anxiety score compared to male participants. Discussion: Self-compassion may be an essential variable to help cope with problems related to perceived COVID-19 threat and death anxiety. Improving our understanding of the psychological impacts of COVID-19 is necessary and essential.
AtıfScopus57WoS56OpenAlex41TR Dizin23İncele - MakaleYalnız künye2021Scopus SJRQ3An experimental investigation of single lignite particle dried in superheated steam and hot air
Celen, P.; Erdem, H.H.
In lignite (low-rank coal)-fired thermal power plants, thermal efficiency can be improved by decreasing the lignite moisture. The lignite moisture can be removed by using superheated steam and hot air as drying fluids. In this study, Turkish (Afşin-Elbistan) lignite having a diameter of 30 mm was dried with superheated steam and hot air at temperatures of 117°C under atmospheric pressure. The changes in its weight and temperature with time were observed, and the drying characteristics were obtained during the drying process. In the first period of drying, which is called heating period, the drying rate of superheated steam is higher than hot air in contrary to during constant-rate period. Moreover, the experiments revealed that less time is required to heat lignite sample with superheated steam compared to hot air.
AtıfScopus3WoS3OpenAlex2İncele - MakaleAçık Erişim2021Scopus SJRQ3The Curricular Practical Training Rotation Problem Formulation and the Assessment of Rotation Strategies
Şimşek, Ahmet Bahadır
This study addresses the curricular practical training rotation problem, which is a type of staff assignment problem. Many educational institutions require theoretical knowledge to be complemented by practical training. Although the details of the implementation differ from institution to institution, it is necessary to prepare a rotation plan that determines how long the trainees will practice in which unit in which training period. Because of the complexity of the problem and humanistic reasons, the manual rotation plan can not reach the optimal level that satisfies all stakeholders and takes time. This study defines a general Curricular Practical Training Rotation Planning Problem specific to the curriculum-based trainee assignment process carried out in a university department and proposes an integer mathematical model for its solution. It is one of the important contributions of this study. It also provides a methodological approach to identify the most appropriate rotation strategy that will satisfy stakeholders. The methodological approach followed is a structure that can be adapted to different perspectives. The study has the potential to guide practitioners and researchers in the field and to lead a rich literature that will be formed with different side constraints and purposes to the problem.
- Kitap BölümüYalnız künye2020Multilevel governance and participation mechanisms in European Union
Kalkisim, Hasan Mahmut
- MakaleAçık Erişim2021Scopus SJRQ3Comparison of field and laboratory result of fiber reinforced shotcrete application
Külekçi, Gökhan
Synthetic fibers, which have become one of the main components of shotcrete, have been studied by many researchers in the laboratory environment. Unfortunately, the results obtained as a result of these researches are not suitable for underground chimneys due to the differences in ambient conditions and application differences. In this study, it is aimed to compare the results of the experiment samples prepared and kept in the laboratory with the mechanical properties of the shotcrete applied in underground conditions. For this purpose, keeping the slump and cement proportions constant, 35 cubic samples were prepared using 2 and 6 kg synthetic fiber for 1 m3 in the laboratory, and 30 cylinder samples and 6 plate samples were prepared for underground. While mechanical experiments were carried out on prepared cube and cylinder samples, the EFNARC plate test and freeze-thaw test were carried out on plate samples. It was observed that the set accelerator made a significant increase in resistance at the end of the 28 days and that the resistance of the samples prepared with polyester fibers in the laboratory environment were very high. As a result of the EFNARC panel tests performed, it was determined that the energy absorption of synthetic fibers increased with fiber amount. Thanks to this study, the energy absorption of the synthetic fiber used has been measured, and the reliability and practicality of the experiments carried out in the laboratory have been increased by evaluating the field conditions and laboratory conditions.
AtıfScopus13WoS12OpenAlex11İncele - BildiriYalnız künye2020Nine Years Long Term Performance and Degradation Assessment of Two On-Grid PV Systems
Ozden, Talat; Ozgun, Ensar Mesut; Keles, Bedirhan; Akinoglu, Bulent G.
Nine years outdoor testing of the two on-grid PV systems at Central Anatolia under the same ambient conditions is very important to be discovered toward transition to renewables. The systems consist of a monocrystalline silicon and micro-crystalline silicon based amorphous thin film PV technologies. The analyses are carried out on monthly based using the outdoor efficiencies. In addition, degradation rates of these systems are calculated and compared with each other and also with international literature. It is also compared the results using the degradation rates of an earlier study carried out using measurements of a shorter period of time.
AtıfScopus3OpenAlex2İncele - MakaleYalnız künye2021Experimental Investigation of Usability of Construction Waste as Aggregate
Kulekci, Gokhan; Yilmaz, Ali Osman; Cullu, Mustafa
The aim of this work is to obtain recycled aggregate (RA) from construction debris in order to reduce the rapid consumption of aggregate resources and the environmental impact of these resources. In order to fulfill this aim, the density, porosity, Schmidt hardness test, uniaxial compression resistance, carbonation depth, and ultrasonic p-wave velocity experiments were conducted on different construction debris transported by trucks from 9 different points in Turkey. In addition, the debris samples taken were broken down to the size of the aggregate and subjected to the tests of density, porosity, moisture content, freeze-thaw, and impact resistance. As a result of the conducted experiments, the lowest mass loss as a result of freezing-thawing was in GRA with 9.36%, the highest mass loss was in ORA with 22.58%, the highest ORA average aggregate impact strength index was 21.27%, and the lowest TRA aggregate impact strength index was found to be 18.26%. İt was determined that most of the physical properties of RA obtained from the construction wreckage was within the limit values specified in the literature and that the recycled aggregates could be used instead of natural aggregate. With this work and these results, RA obtained could be used in many areas such as concrete aggregate in the construction sector, underground filling in mining, filling material in gunned concrete, and filling materials on highways.
AtıfScopus15WoS12OpenAlex8İncele - MakaleAçık Erişim2022Scopus SJRQ3A MODIFICATION OF APPROXIMATE RANDOM CHARACTERISTICS FOR A MODEL OF ZIKA VIRUS TRANSMISSION
Bekiryazici, Zafer; Kesemen, Tulay; Merdan, Mehmet; Khaniyev, Tahir
In this study, a theoretical model of Zika virus transmission is investigated with random parameters. The parameters of a deterministic model are transformed to random variables to obtain a system of random differential equations. The approximate solutions of the model are analyzed with modified random differential transformation method. It is seen that modified random differential transformation method performs better than random differential transformation method on long time intervals
AtıfOpenAlex1İncele - MakaleYalnız künye2020Scopus SJRQ4Macroeconomic Dynamics of Labour Income Share in the United States: Evidence From MARS
Çelik, Orkun
Macroeconomic dynamics of labour income share (will be referred to herein as lis) in the United States for the period of 1948Q1-2019Q1 are tried to be determined in this study, where Multivariate Adaptive Regression Splines (will be referred to herein as MARS) approach is employed. In order to investigate sectoral differences, the business, non-farm, and non-finance sectors are evaluated, respectively. In accordance with the obtained results, it may be observed that the macroeconomic dynamics of lis in the business sector are productivity, export, profit, gross private domestic investment, unemployment rate, current account balance, gross domestic product, and tax revenue, respectively. Related macroeconomic dynamics of lis concerning non-farm sector are productivity, current account balance, gross private domestic investment, export, consumer price index, gross domestic product, profit, unemployment rate, and gross government investment. Aforementioned dynamics for non-finance sector are also profit, productivity, import, gross domestic product, tax revenue, gross government investment, consumer price index, and unemployment rate. In accordance with this, the most significant dynamic with respect to lis is profit in the non-finance sector, while it is productivity in the business and non-farm sectors.
- MakaleYalnız künye2020Scopus SJRQ1Effects of Mn Content on Microstructure, Mechanical and Dry Sliding Wear Properties of Eutectic Al–Si–Cu Alloy
Alemdag, Yasin; Beder, Murat
Abstract: In the present study, effects of Mn content on microstructure, hardness, tensile and dry sliding wear properties of eutectic Al–Si–Cu alloy in as cast-state were investigated. Mn addition to the eutectic alloy results in the formation of α-Al15Mn3Si2 phase in its microstructure. It was found that hardness of eutectic alloy increases continuously with increasing Mn content while its tensile strength and percentage elongation values decrease. It was also found that the friction coefficient and volume loss of eutectic alloy decrease as Mn content increases. Amongst the alloys, the lowest friction coefficient is obtained with Al–12Si–3Cu–2Mn alloy yet the Al–12Si–3Cu–1Mn alloy exhibits the highest wear resistance. Formation of adhesion layer, its oxidation and delamination were observed to be main wear mechanisms of Al–12Si–3Cu–(0–2)Mn alloys. These findings are explained in terms of formation of α-Al15Mn3Si2 phase, and its cracking tendency effect. Graphic abstract: [Figure not available: see fulltext.].
AtıfScopus19WoS19OpenAlex19İncele - MakaleAçık Erişim2021Scopus SJRQ1Land subsidence and its relations with sinkhole activity in karapınar region, turkey: A multi-sensor insar time series study
Orhan, Osman; Oliver-Cabrera, Talib; Wdowinski, Shimon; Yalvac, Sefa; Yakar, Murat
The Karapinar basin, located in the Central Anatolian part of Turkey, is subjected to land subsidence and sinkhole activity due to extensive groundwater withdrawal that began in the early 2000s. In this study, we use Interferometric Synthetic Aperture Radar (InSAR), Global Navigation Satellite System (GNSS), and groundwater level data to monitor and better understand the relations between groundwater extraction, land subsidence, and sinkhole formation in the Karapinar basin. The main observations used in the study are InSAR-derived subsidence velocity maps calculated from both Sentinel-1 (2014–2018) and COSMO-SkyMed (2016–2017) SAR data. Our analysis reveals broad areas of subsidence with rates exceeding 70 mm/yr. The InSAR-derived subsidence was compared with GNSS data acquired by a continuously operating GNSS station located in the study area, which show a similar rate of subsidence. The temporal characteristic of both InSAR and GNSS time series indicate a long-term subsidence signal superimposed by seasonal variability, which follows the overall groundwater level changes, with over 80% cross-correlation consistency. Our results also indicate that sinkhole activity is limited to slow subsidence areas, reflecting strong cohesion of near-surface rock layers that resist subsidence but yield to collapse in response to aquifer system deformation induced by groundwater extraction.
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İncele - MakaleAçık Erişim2021Scopus SJRQ2Geochemistry and Pb isotopic proof for sources of heavy metal(loid)s in Late Cretaceous sandstones from Eastern Pontides (NE Turkey)
Saydam Eker, Çiğdem
Upper Cretaceous sedimentary rocks are widely exposed around Trabzon, Giresun and Gümüşhane in the eastern Pontides. The sedimentary rocks are mainly composed of sandstones and marls, and the thicknesses of these rocks range from 170 to 400 m. This paper focused on Late Cretaceous sandstones of Trabzon, Giresun and Gümüşhane regions to identify the concentrations, sources, deposition environment and conditions of certain heavy metal(loid)s (Zn, Pb, Cu, Ni, As, Co, Mo and V). Enrichment factor (EF), geo-accumulation index (Igeo), Pollution index (Pi), Pollution load index (Pln), Pb isotope and multivariate statistical analysis were performed to elucidate the pollution levels and sources. In general, the evaluation indices exhibited that the sandstones were moderately polluted by As in the Trabzon area, and strongly polluted by Ni and As, moderately polluted by Co and V in the Giresun and Gümüşhane areas. The results of multivariate statistical analyses indicated that As and partly Pb might be originated from anthropogenic sources, whereas other metals were derived from geogenic origin. Lead isotopic analysis demonstrated two characterized signatures of the pollution sources in the sandstones, one related to geogenic origin and the other to coal, gasoline and pesticides. The sandstones were deposited in transition—marine environment under oxic—weak oxic conditions and paleoclimatic conditions ranged from arid to moist during Late Cretaceous period.
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