Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Uzun, Sevda(77)
- Merdan, Mehmet(73)
- Duran, Celal(54)
- Ozdes, Duygu(50)
- Baltaci, Cemalettin(45)
- Kaygusuz, Abdullah(45)
- Kulakaç, Nurşen(39)
- Ashyralyyev, Charyyar(38)
- Karsli, Orhan(37)
- Demir, Selim(36)
- Öztürk, Serkan(36)
- Dokuz, Abdurrahman(35)
- Turan, Ibrahim(35)
- Araz, Onur(33)
- Kandemir, Raif(31)
- Sipahi, Ferkan(30)
- Topal, Fevzi(30)
- Kurt, Kemal(28)
- Peker, Iskender(28)
- Arslan, Mehmet(27)
- Baltacı, Cemalettin(27)
- Maden, Nafiz(27)
- Ozturk, Samet(27)
- Aydin, Aydanur(26)
- Vural, Alaaddin(26)
- Bayrakdaroglu, Serdar(25)
- Kurnaz, Muammer(25)
- Reis, Hatice Catal(25)
- Akar, Zeynep(24)
- Aydin, Faruk(24)
- Gücer, Mehmet Ali(24)
- Topal, Meryem(24)
- Yolcu, Halil(24)
- Yücel, Cem(24)
- Anaç, Halil(23)
- Kankal, Murat(23)
- Ürkek, Bayram(23)
- Aliyazicioglu, Yuksel(22)
- Günen, Mehmet Akif(22)
- Tuncer, Metin(22)
Yayınlar
- 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).
AtıfScopus1WoS1OpenAlex1
İncele - 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 - 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.
- 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 - 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 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.
AtıfScopus7WoS6OpenAlex10İncele - MakaleAçık Erişim2021Production and characterization of zinc oxide nanoparticles in microsystems via green synthesis; [Yeşil sentez yoluyla mikrosistemlerde çinko oksit nanopartiküllerin üretimi ve karakterizasyonu]
Akay, Şeref; Sefaoğlu, Melike
Nanoparticles (NP), which can be produced for many different fields and purposes; are at size vary from nanometer to a micrometer. These particles can be prepared by different approaches such as chemical, physical and biological methods. However, the biological approach is the most promising approach among other methods due to its simplicity and environmentally friendly conditions. The production of the nanoparticle by means of a biological approach does not require any high temperature, acidic/basic conditions and hazardous chemicals. Therefore, this method is named “green synthesis”. Development in microtechnology has had profound effects in many areas such as drug discovery, biology, diagnosis, and tissue engineering. Microfluidics which focuses on the processing of liquids in microscale systems has attracted wide attention in the production process of nanoparticles due to precise control and fast mixing. The main purpose of this study is to produce and characterize metal nanoparticles by combining microsystems and green synthesis approaches. For this purpose, in the first step, the design of microsystems that suitable for the flow of different phases was performed. In the second step, ZnO nanoparticle synthesis was carried out using the red cabbage (Brassica oleracea var.capitata f. Rubra) extracts. The synthesis of nanoparticles achieved by optimizing different parameters such as; extract: zinc ratio, zinc solution concentration, flow rates, and flow rates ratio in the microsystem and temperature. The results showed that the herbal red cabbage components can be used for the green synthesis of ZnO nanoparticles.
AtıfScopus1OpenAlex2TR Dizin1
İncele - MakaleYalnız künye2021Scopus SJRQ1Single-step recovery of pectin and essential oil from lemon waste by ohmic heating assisted extraction/hydrodistillation: A multi-response optimization study
Tunç, Merve Tuğçe; Odabaş, Halil İbrahim
The main products obtained from citrus wastes are pectin and essential oil. In this work, ohmic heating assisted extraction/hydrodistillation (OHAE/H) was applied for the simultaneous recovery of pectin and essential oil from lemon waste. Optimum OHAE/H conditions to maximize the yield of pectin and essential oil were determined with response surface methodology. Three independent variables, namely liquid to solid ratio (w:v), extraction/hydrodistillation time (min) and voltage gradient (V/cm) were varied to obtain maximum pectin and essential oil yield. Optimum OHAE/H conditions were determined as 8.7:1 liquid to solid ratio, 58.4 min extraction/hydrodistillation time and 14.2 V/cm voltage gradient. The predicted pectin and essential oil yields at optimum conditions were 16.58 and 3.62 g/100 g lemon waste, respectively. Data analysis showed that all of the independent variables significantly affected the pectin and essential oil yield. In the verification study, close agreement was found between predicted and experimental values. Conventional heating extraction/hydrodistillation (CHE/H) were conducted to evaluate the effectivity of OHAE/H. With OHAE/H process, the yields of the pectin and essential oil were significantly increased when compared to CHE/H. Limonene concentration of the essential oil produced with OHAE/H was higher than the essential oil produced by CHE/H. Results demonstrate that the single-step OHAE/H could be an effective method for simultaneous extraction and hydrodistillation of pectin and essential oils.
AtıfScopus53WoS43OpenAlex54İncele - MakaleAçık Erişim2021Scopus SJRQ4Automatic Classification of COVID-19 using CT-Scan Images
Reis, Hatice Catal
Medicine and engineering sciences have been working in close contact for common purposes. Machine learning algorithms are used in the medical field for early diagnosis prediction. The major aim of this study is to evaluate machine learning algorithms and deep learning algorithms using computed tomography scan (CT-scan) images for automated detection of the coronavirus disease 2019 (COVID-19) patients. We obtained seven hundred and fifty-seven (757) CT-scan images from a public platform. We applied four automated traditional classification methods to predict COVID-19 using deep learning and machine learning. These algorithms are SVM, AdaBoost, NASNetMobile, and InceptionV3. Comparative analyses are presented among the four models by considering metric performance factors to find the best model. The results show that the InceptionV3 model achieves better performance in terms of accuracy, precision, recall, Cohen’s kappa, F1-score, root mean squared error (RMSE), and receiver operating characteristic-area under the curve (ROC-AUC), in comparison with the other Covid-19 classifiers. Accordingly, the InceptionV3 approach is recommended for the automatic diagnosis of Covid-19 and assessments. This research can present a second point of view to medical experts and it can save time for researchers as the performance of standard machine learning methods in detecting COVID-19 is evaluated.
AtıfScopus1WoS1OpenAlex1İncele - BildiriYalnız künye2021Stability estimates for a third order of accuracy difference scheme elliptic overdetermined multi-point problem
Ashyralyyev, Charyyar; Akyuz, Gulzipa; Cakalli, H.; Kocinac, L.D.R.; Ashyralyev, A.; Harte, R.; Dik, M.; Canak, I.; Kandemir, H.S.; Tez, M.
In this work, we discuss a third order of accuracy difference scheme for approximate solution of the elliptic overdetermined multi-point problem in the Hilbert space. Functional operator approach is used to study existence and uniqueness of solution of difference problem. Stability, almost coercive stability and coercive stability estimates for solution of difference scheme are established.
- MakaleAçık Erişim2021Scopus SJRQ4Evaluation of added sugar and sugar-sweetened beverage consumption by university students
Meric, Çağdaş Salih; Ayhan, Nurcan Yabanci; Yilmaz, Hacı Ömer
Today, increased intake of sugar and sugar-sweetened beverages is seen as an important factor in the growing prevalence of chronic diseases, such as obesity, obesity-related diabetes, and coronary heart diseases. This study involved 214 Ankara University students from the Department of Nutrition and Dietetics, which was intended to evaluate the consumption of sugar and sugar-sweetened beverages. The frequency of student consumption of beverages and the quantities and amounts of sugar taken with beverages were questioned. The average total amount of sugar added to drinks by the students was 4.69 ± 6.35 gram, while the average total amount of sugar taken with sugar-sweetened beverages was 11.34 ± 15.32 gram. Female students relative to male students, students in grade 4 compared to grades 2 and 3, and students who had daily breakfast compared to those who did not had lower average sugar consumption (p-value < 0.05). As class grades increase, the amount of sugar added to beverages and fruit juice and sweetened soft drinks and carbonated beverages decreased (p-value < 0.05). The consumption of herbal teas and dietary beverages increased and the eating habits of students generally changed positively (p-value > 0.05). It is important to educate university students about the reduction in sugar intake and sugar-containing food in order to avoid many chronic diseases that may be seen in older ages.
AtıfScopus6WoS5OpenAlex7İncele - MakaleYalnız künye2021Scopus SJRQ2ReCRNet: a deep residual network for crack detection in historical buildings
Reis, Hatice Catal; Khoshelham, Kourosh
In historical buildings, surface cracks are important indicators of potential structural damage. Natural disasters and indirect human factors, which are frequently encountered in recent periods, negatively affect historical buildings and structures. Fast and cost-effective crack detection methods play a key role in structural health monitoring of historical buildings. This paper presents methodologies for identifying concrete cracks using deep learning. We propose ReCRNet, a deep learning architecture designed for classifying images of cracks. The performance of the proposed method is evaluated and compared with state-of-the-art methods such as AlexNet, VGG 19, linear support vector machine (SVM), and decision tree (DT). The results show that ReCRNet achieves better performance in terms of accuracy, precision, recall, F1-score, and receiver operating characteristic (ROC), in comparison with the other crack classifiers. Accordingly, the proposed approach is recommended for automatic monitoring of historical buildings and building condition assessments.
AtıfScopus17OpenAlex15İncele - Kitap BölümüYalnız künye2021Impact of Covid-19 Pandemic on Cryptocurrency Prices
Karaaslan, İbrahim
- MakaleAçık Erişim2021Scopus SJRQ2Investigation of class 1 integrons with antibiotic resistance genes in multidrug-resistant acinetobacter baumannii strains and determination of plant extract effects on multidrug-resistant isolates
Saral, Ayşegül; Cinemre, Sedanur; Okumuş, Funda; Akar, Zeynep; Çiçek, Ayşegül Çopur; Düzgün, Azer Özad
This study aimed to investigate the presence of resistance genes in multidrug-resistant A. baumannii isolates as well as to determine the antibacterial activity of selected plant extracts against isolates. 41 strains were isolated from various clinical samples. PCR tests were performed using the primers. Methanol was used as solvent for the preparation of the plant extracts. MIC values of the plant extracts were determined by the broth microdilution method. The blaOXA-23, blaCTX-M-1, blaCTX-M-2, blaGES genes and Class 1 integrons were detected in five isolated strains. The lowest MIC value (2.25 mg/mL) was determined for the Echinacea purpurea extract, while the highest MIC value (50 mg/mL) was determined for the Morus alba extract. Determination of the antibacterial effect of plants extracts used in the study against A. baumannii isolates shows the importance of screening the antibacterial activity of plants in the fight against antibiotic resistance.
AtıfScopus1WoS1OpenAlex3İncele - MakaleYalnız künye2021Scopus SJRQ2Crustal Contamination of Tertiary Volcanic Rocks: Evidence from K, U, Th and Radiogenic Heat Production Data in Eastern Pontides (NE Turkey)
Maden, Nafiz; Akaryalı, Enver; Aydınçakır, Emre
Herein, we present new 238U, 232Th, and 40K radionuclide concentrations, density and radiogenic heat production (RHP) data on the Tertiary volcanic rocks outcropping in Borçka, Gumushane and Trabzon regions within the Eastern Pontide Orogenic Belt (EPOB). The mean K values for Trabzon, Borçka and Gümüşhane regions were 2.19 ± 0.87%, 0.90 ± 0.70% and 0.59 ± 0.25%, respectively, the mean U values for Trabzon, Borçka and Gümüşhane regions were 2.12 ± 0.76 ppm and 1.29 ± 0.68 ppm and 0.90 ± 0.32 ppm, and the average Th values were calculated as 6.54 ± 2.32 ppm, 2.49 ± 1.93 ppm and 1.33 ± 0.60 ppm for Trabzon, Borçka and Gümüşhane regions, respectively. The average Th/U values are 3.38 ± 1.48 for the Trabzon region, 2.01 ± 1.22 for the Borçka region, and 1.69 ± 1.09 for the Gümüşhane region. Average U/Th values were calculated as 0.35 ± 0.14, 0.71 ± 0.52 and 0.89 ± 0.72 for the Trabzon, Borçka and Gümüşhane regions, respectively. The RHP values were determined as 1.16 ± 0.35 μW m - 3, 0.58 ± 0.33 μW m - 3 and 0.37 ± 0.10 μW m - 3 for Trabzon, Borçka and Gümüşhane regions, respectively. The Tertiary aged rocks in the EPOB that we have examined within this study scope have been derived from an enriched mantle, previously metasomatized by fluids derived from subducted slab. The parental magma of Eocene basaltic rocks was contaminated with crustal material during the ascension of the magma through the crust or in the shallow-level crustal magma chambers.
AtıfScopus5WoS5OpenAlex6İncele - MakaleAçık Erişim2021Scopus SJRQ4Evaluation of Load-Transfer Efficiency of Steel Mesh Reinforced Contraction Joints in Concrete Pavement: Accelerated Pavement Test and FE Analysis
Celik, Muhammet; Seferoglu, Mehmet Tevfik; Akpinar, Muhammet Vefa; Nasery, Mohammad Manzoor; Seferoglu, Aysegul Gunes
Transverse contraction joints are by far the most common type of joint in jointed plain concrete pavements. Early loading of contraction joints can create a weakened vertical plane and later grow as a full-depth crack. In this study, load transfer efficiency (LTE) of steel mesh reinforced transverse contraction joints were studied at accelerated pavement tests (APT). 3D finite element (FE) model of jointed plain concrete pavement (JPCP) was developed to study deflections and crack propagation in just under the joint of the concrete pavement. The APT tests were focused on the LTE values before and after the crack initiation under the contraction joint region. Experiments were performed on three slabs in which two of these slabs were prepared without reinforcement and one of them was reinforced with steel mesh. Data generated by APT was used for verification of crack propagation modeling in the finite element analysis. Steel mesh reinforced slab gave the lowest vertical deflections (51μm) and highest LTE (91.56%). The LTE value in the reinforced slab after 25,000 passes was 13.63% higher than the average of unreinforced slabs. The findings suggest that the load transfer efficiency was found to be a complex parameter and should be interpreted together with average displacement values when contraction joints are evaluated at early traffic loadings.
AtıfScopus3WoS2OpenAlex2TR Dizin1İncele - MakaleYalnız künye2021Scopus SJRQ2Design of series tuned mass dampers for seismic control of structures using simulated annealing algorithm
Araz, Onur; Kahya, Volkan
The effectiveness of the series tuned mass dampers (STMDs) in reducing the dynamic vibrations of the structures under the ground motion is investigated, and their optimum parameters are obtained based on the simulated annealing (SA) optimization. The STMD is one of the most well-known passive control devices which consists of two TMD units arranged in series. However, only a few studies are available on the control performance and optimum parameters of the STMDs for structural systems subjected to ground motion. Thus, the goal of this study is to carry out a thorough optimization analysis based on the SA algorithm for the structures equipped with an STMD under the effect of ground motion. The objective function is selected as the reduction of the displacement response of the structure. It is proved that the optimum STMD has better effectiveness than the optimum TMD in suppressing the maximum story displacement of the structure. Further, the effect of the frequency shift on the effectiveness of the optimally designed STMD is investigated.
AtıfScopus38WoS32OpenAlex37İncele - MakaleYalnız künye2021Scopus SJRQ2Investigating the historical development of accuracy and precision of Galileo by means of relative GNSS analysis technique
Yalvac, Sefa
Galileo navigation system has significantly expanded satellite constellation over the last few years and now serves with 22 satellites in three orbital planes. The development of the Galileo is not only limited to the number of satellites in the space segment, but also the quality of the IGS MGEX products produced by different Analysis Centers has increased gradually and brought up the topic of investigation of the accuracy and precision of the Galileo-only positioning. However, almost all of the studies on Galileo-only positioning in the literature have been performed with Precise Point Positioning method and comprehensive studies with the relative positioning technique are quite a few. In this study, the development of the accuracy and precision of the Galileo from 2016 to the end of 2019 (4 years) has been investigated for the first time by means of relative positioning technique. For this purpose, data of eight GNSS stations selected from the IGS MGEX network were obtained and analyzed with GAMIT/GLOBK software as GPS-only and Galileo-only, separately. Using the daily solutions obtained from both navigation systems, time series were produced and the differences between them were compared in order to reveal the Galileo accuracy. According to the results, the accuracy of the Galileo was variable during the experiment and it could be examined in three periods. The averages of 3D positioning error in the first period (2016-2017) is 14.92 mm and improved by 56%, and decreased to 6.55 mm in the second period (2017-2018), and then improvement at 23% in the third period (2018 to the end of 2019) and decrescent to level of 5.13 mm on average for all stations. Similarly, standard deviations obtained from Galileo increased during the experiment and during the 3rd period it was closed to a few mm with GPS. It was concluded that the accuracy and precision of the Galileo showed parallel development and the development was directly related to the number of satellites in the Galileo constellation, and as a result, nowadays, Galileo-derived coordinates are close to the coordinates obtained from the GPS by a few mm.
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