Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Günaydin, Murat(6)
- Ak, Muammer(5)
- Akinoglu, Bulent G.(5)
- Akpinar, Muhammet Vefa(5)
- Genç, Ali Fuat(5)
- Kahraman, Yakup(5)
- Takaoğlu, Zeynep Başkan(5)
- Acet, Tuba(4)
- Aliyazicioglu, Yuksel(4)
- Altunişik, Ahmet Can(4)
- Ashyralyyev, Charyyar(4)
- Bölükbaş, Mehmet(4)
- Dağ, Serhat(4)
- Demir, Selim(4)
- Kaygusuz, Abdullah(4)
- Kayikçioglu, Temel(4)
- Okur, Fatih Yesevi(4)
- Ozden, Talat(4)
- Topal, Mehmet Hanefi(4)
- Turan, Ibrahim(4)
- Adanur, Süleyman(3)
- Akdu, Uğur(3)
- Aksakal, Vecihi(3)
- Aktaş, Ibrahim(3)
- Arslan, Mehmet(3)
- Ashyralyev, A.(3)
- Aslan, Emre Ş(3)
- Aydin, Orhan(3)
- Duran, Celal(3)
- Düzgün, Azer Özad(3)
- Gul, Fatih(3)
- Güllüpunar, Hasan(3)
- Karahasan, Olguhan Şevket(3)
- Kaya, Yusuf(3)
- Lukashov, A.(3)
- Nizetic, S(3)
- Orhan, Halit(3)
- Ozcan, Kadriye(3)
- Paksoy, Zahid(3)
- Papadopoulos, A(3)
Yayınlar
- MakaleYalnız künye2018Automated Model Updating of Historical Masonry Structures Based on Ambient Vibration Measurements
Altunisik, Ahmet Can; Okur, Fatih Yesevi; Genç, Ali Fuat; Günaydin, Murat; Adanur, Suleyman
Finite-element (FE) model updating is a very effective procedure for determining the uncertainty parameters in a structural model and minimize differences between experimentally and analytically identified dynamic characteristics. This procedure can be practiced with manual and global/local automatic model updating procedures. Automatic model updating is very popular because of its applicability to all kinds of engineering structures to minimize differences, and its damage localization and structural health monitoring. This paper considers a historical masonry bastion to obtain its dynamic characteristics numerically with the finite-element method and experimentally with ambient vibration tests (AVTs). Sensitivity analyses for the uncertainty parameters and manual and automated model updating to minimize differences are also performed. A castle bastion located in Trabzon, Turkey is selected as an application. The FE model of structure is developed in commercial software. The first three natural frequencies are obtained between 5 and 10Hz, and AVTs are performed under natural excitation using enhanced frequency domain decomposition (EFDD) and subspace structural identification (SSI) techniques. The first three natural frequencies are obtained between 4 and 7Hz. The comparison of analytically and experimentally identified dynamic characteristics shows a close agreement between mode shapes, but 26% difference in natural frequencies. To minimize the difference, the FE model of the bastion is updated using manual and global/local automated updating, changing its material properties of Young's modulus and material density. The maximum differences are reduced from 27 to 3% with manual updating, and to 0.02% with automated model updating.
- BildiriYalnız künye2018Reducing Urban Heat Islands by Developing Cool Pavements
Akpinar, Muhammet Vefa; Sevin, Sedat; Nizetic, S; Papadopoulos, A
- BildiriYalnız künye2018Comparison of Asphalt and Concrete Pavement Solar Reflectance
Akpinar, Muhammet Vefa; Sevin, Sedat; Nizetic, S; Papadopoulos, A
- MakaleYalnız künye2018COMPARISON OF FEM SOLUTION WITH ANALYTICAL SOLUTION OF CONTINUOUS AND DISCONTINUOUS CONTACT PROBLEM
Kaya, Yusuf; Polat, Alper; Özsahin, Talat Sukru
The continuous and discontinuous contact problem of a homogeneous layer loaded with three rigid flat blocks and resting on the elastic semi-infinite plane was investigated in this study by using the finite element method (FEM). All surfaces are assumed to be frictionless. The homogenous layer was loaded by means of three rigid flat blocks whose external loads are Q and P (per unit thickness in z direction). Two dimensional finite element analysis of the problem was performed using ANSYS package program. Analyzes were performed for loading conditions which are Q=P, Q=2P, Q=4P, Q=8P and Q=10P, and different values of block widths, distances between blocks and shear modulus. The initial separation loads and initial separation distances (lambda(cr), chi(cr)) between the homogeneous layer and the elastic semi-infinite plane were determined for continuous contact condition. The length of the separation zone was obtained for discontinuous contact condition. In addition to these, normal stress distributions between the layer and the semi-infinite plane were determined for continuous and discontinuous contact conditions. As a result of the study, the analytical results, and the results of the finite element method were shown by comparing as graphs and tables.
- BildiriYalnız künye2018Urban Heat Island Effects of Concrete Road and Asphalt Pavement Roads
Akpinar, Muhammet Vefa; Sevin, Sedat; Nizetic, S; Papadopoulos, A
- MakaleYalnız künye2018Assessment of knowledge level of university students about ovarian cancer
Demir Dogan, Melike; Aygün, H. Gulbahar; Baskin, Sema; Sensoy, Merve; Köken, Elif
The present study was conducted in order to determine the knowledge levels of female university students about ovarian cancer. The sample was planned to include 2220 students however 1468 students were reached. The data were collected via questionnaire about socio-demographic characteristics of the students and questionnaire involving expressions that measure their knowledge level. Mean age of the students was 20.78 +/- 1.20; 678 (46.1%) of the students were faculty students, 466 (31.7%) were collage students, and 324 (22.0%) were vocational school students. 874 (59.5%) of the students did not know what ovarian cancer is and 1332 (90.7%) did not receive any education about ovarian cancer. Therefore, 1227 (83.6%) of the students stated that they did not know symptoms of ovarian cancer. Thestudents were determined to have low level of knowledge about ovarian cancer
- MakaleAçık Erişim2018Comparison of Different Dynamic Contrast Enhanced-Magnetic Resonance Imaging Descriptors and Clinical Findings Among Breast Cancer Subtypes Determined Based on Molecular Assessment
Dogan, Serap; Ozmen, Soner; Oz, Bahadir; Imamoglu, Hakan; Kahriman, Guven; Zararsiz, Gokmen; Ozturk, Mustafa
Background: Breast cancer is a heterogeneous disease with different molecular and histologic subtypes, clinical behaviors and prognosis. The same stage of disease and similar histopathological characteristics may show different treatment responses. Identification of breast cancer subtypes has become important for planning the targeted therapy and personalized management of patients. Objectives: To compare the clinicopathologic findings, dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) characteristics and associated MRI findings among breast cancer molecular subtypes. Patients and Methods: 267 pathologically proven invasive breast cancers in 263 patients were included. Clinicopathological findings, DCE-MRI findings and associated MRI findings were retrospectively evaluated and compared among breast cancer subtypes. Results: Invasive ductal carcinoma was the most common histological tumor type (87.6%). There were 222 (83.1%) masses and 45 (16.9%) non-mass enhancements. The molecular subtypes were luminal A in 174 (65.1%), luminal B in 45 (16.9%), human epidermal growth factor receptor 2 (HER2) positive in 24 (9%) and triple negative (TN) in 24 (9%) of the lesions. Spiculated mass margin was significantly associated with luminal A breast cancer (45.2%) and irregular shape was significantly more common in luminal A (86.3%) and luminal B lesions (95.1%) (P < 0.001). Larger mass size (P= 0.027), non-mass enhancement (P= 0.005), perilesional+ prepectoral edema and skin + perilesional+ prepectoral edema were significantly associated with HER2 positive breast cancer (P= 0.001). Higher histological grade, oval mass shape, circumscribed mass margin, intratumoral high/very high signal intensity on T2 weighted image (T2WI) were significantly associated with TN breast cancer (P < 0.001). Conclusion: Histological grade, size and morphological features of masses on DCE-MRI, intratumoral signal intensity on T2WI and edema pattern would be helpful to distinguish breast cancer subtypes.
- BildiriYalnız künye2018Health perception of nurses and affecting factors
Palazoglu, Cansu Atmaca; Kahraman, Beliz Yekeler; Elkoca, Ayse; Danaci, Esra; Nural, N
This study was carried out to determine the health perception of the nurses and the affecting factors. The study was carried out with the participation of 80 nurses working in the state hospital in Gumushane city centre. The data were collected using the nursing introductory information form and the 'The Perception of Health Scale'. In the analysis of the data, Kruskal-Wallis and Mann-Whitney U test with frequency, percentage, mean and standard deviation were used and in the examination of the relations between variables, Pearson correlation test from nonparametric methods was used. Of the nurses participating in the study, 92.5% were women, 7.5% were men, 46.3% were graduates, 68.8% loved their work, 62.5% were satisfied with the service and 60% worked in shifts. In literature research, sufficient numbers of studies were found to examine the health perception of nurses. It is recommended to increase the work in this area.
- MakaleYalnız künye2018The Relationship between Trade Openness and Inflation: An Analysis for Turkey within the Frame of Romer Hypothesis
Özçag, Mustafa; Bölükbas, Mehmet
The aim of the study is to investigate the relationship between trade openness and inflation in Turkey economy for the period of 1980-2015. Unlike the other studies, symmetrical and asymmetrical analyses were used to examine the relationship between variables. The symmetric relationship between variables was analysed with Johansen cointegration and Hacker and Hatemi-J (2006) causality tests. The findings of symmetric analyses show that there is no cointegration or causality relationship. Whereas Hatemi-J and Irandoust (2012) hidden cointegration test and Hatemi-J (2012) causality tests were used for asymmetric analyses. According to the results of Hatemi-J and Irandoust (2012) hidden cointegration test, a cointegration relationship between trade openness and inflation in Turkey has been proved.
- MakaleYalnız künye2018The Impact of Special Consumption Tax Increases on Personal Automobile Demand of Households: Panel Co-Integration Analysis
Önder, Kubra; Sahin, Muhammet
The automobile industry is one of the leading industries for economic growth and development of countries in terms of value added and export value. Consumer demand for automobiles exhibits a continuous fluctuation depending on the SCT (Special Consumption Tax) policy. The aim of this study is to analyze the impact of the change in SCT rates on automobile demand using panel co-integration method for Fiat, Ford, Toyota, Renault, Honda and Hyundai brands which have factories in Turkey. In the study, monthly time series data of January 2014 and February 2017 period has been used and increase in SCT rate, auto loan interest rates and petrol prices have a negative impact on personal automobile demand.
- BildiriYalnız künye2018R-peaks Detection with Convolutional Neural Network in Electrocardiogram Signal
Dogan, Ramazan Ozgur; Kayikçioglu, Temel
The performance of electrocardiogram applications is closely related to the succesful detection of R-peaks. Therefore, successful detection of R-peaks is of high importance. Electrocardiogram signals vary from person to person, so detection of R-peaks is getting difficult. In this study, Evolutionary Neural Network which is a deep learning model and imitates human vision, is used to detect R-peaks. The MIT-BIH Arrhythmia Database with 48 different records was used as the database and experimental results with very high accuracy were obtained.
- BildiriYalnız künye2018Detecting Cardiac Arrhythmia by Using Time Differences of Double Wavelength PPG Peaks
Yildirim, Omer; Kayikçioglu, Temel
Nowadays, photopletismogram (PPG) signals are used in respiration and blood pressure measurement, monitoring of the sleep pattern and also detecting of mental disorders, mainly blood oxygen saturation and heartrate measurement. The reason of the use of PPG signals instead of signals such as electroencephalogram (EEG) or electrocardiogram (ECG) is easy to obtain and real-time monitoring of these data, as well as being easily used by people in daily life and easily integrated into wearable technologies. In this study, detecting of cardiac arrhythmia was made successfully by using double wavelength PPG signals instead of ECG signals
- MakaleYalnız künye2018The effect of quench-aging on the mechanical properties of Zn-27Al-1Cu alloy
Aydin, Murat; Senaslan, Fatih
The ternary alloy Zn-27Al-1Cu was produced by permanent mold casting. As-cast alloy was aged for different periods after being subjected to solution treatment followed by water quenching. The microstructure, mechanical properties and fatigue behavior of as-cast and heat-treated alloy were then investigated. The quench-aging eliminated the as-cast dendritic structure and produced a uniform microstructure consisting of large grains combined with precipitates. The hardness and tensile strength generally increased, whereas the ductility slightly decreased with aging time. Under all conditions, the longest fatigue life was obtained from the alloy that had been aged for 0.5 h, while the alloy which had been aged for 10 h exhibited the shortest. The fatigue properties were found to be more dependent on impact toughness and elongation, rather than tensile strength.
- MakaleYalnız künye2018EFFECTS OF STRAND CONFIGURATION ON PRE-TENSIONED I-GIRDERS
Atmaca, Barbaros; Ates, Sevket; Günaydin, Murat; Altunisik, Ahmet Can
The purpose of this paper is to examine the effect of strand configuration on the behavior of precast, pre-tensioned concrete I-girders by considering design load components for highway bridges as dead loads and equivalent lane loads. Under these loads, bridge girder's bottom flange is exposed to tensile stresses. To minimize or eliminate the tensile stresses, compressive stresses are induced in pre-stressed concrete with strands. Determination of strand configuration is important as well as number of strands because it affects stress distribution and displacement of bridge girders. One of the typical precast I-girder with 90 cm height is considered in this study. To determine strand configuration effects, eighteen I-girders with the same cross-section, effective span length and material properties but different strand configuration are selected as an application. Equal prestressing force is applied all strands simultaneously. Three dimensional finite element (FE) models of girder are constituted using ANSYS software. Result of beam theory is used to verify the modeling techniques. At the end of the study, numerically identified stress distribution and displacement for I-girders compared with each other. It is seen that proper strand configuration is effective to reducing stresses and displacements of pre-stressed I-girder.
- MakaleYalnız künye2018ANTIMICROBIAL AND ANTIOXIDANT SCREENING, SYNERGY STUDIES OF HELICHRYSUM CHIONOPHILUM EXTRACTS AGAINST TO RESISTANT MICROBIAL STRAINS
Ozcan, Kadriye; Acet, Tuba
In this study, the antimicrobial activities and antioxidant properties of five different extracts of Helichrysum chionophilium plants from Gumushane/Turkey were investigated. To determine the antimicrobial activity disc diffusion and microdilution methods were used against to fifteen microorganisms. The effect of plant extracts and antibiotic combinations against to vancomycin-resistant Enterococcus faecium and methicillin-resistant Staphylococcus aureus were investigated as well. Total phenolic and flavonoid contents were determined by spectrophotometric techniques. Antioxidant properties of plant extracts evaluated by free radical scavenging assays which ABTS and DPPH. The plant ethyl acetate extract showed the highest level of total phenolic (423.01 +/- 0.8 mg GAE/g extract) and flavonoid contents (100.18 +/- 1.4 mg QE/g extract). Similarly, ethyl acetate extract exhibited the highest level of DDPH (IC50: 67.44 +/- 0.9 mu g/ml). However, hexane extract exhibited the highest level activity of ABTS (IC50: 55.20 +/- 1.3 mu g/ml). The highest MIC value was determined as 8 mu g/ml against to Pseudomonas aeruginosa on ethyl acetate extract. Besides, all of extracts exhibited antimicrobial activity on at least one test organism. Plant extracts with some antibiotic combinations generated synergies or partial synergic activity against to VREF and MRSA. These findings revealed that the plant has strong antimicrobial and antioxidant properties. Finally, using the plant extracts and antibiotic combinations might be a good tool in fighting with antibiotic resistance strains.
- MakaleYalnız künye2018A New Nomogram Proposal to Determine Concrete Compressive Strength by Combined Nondestructive Testing Methods
Bingöl, Şinasi; Çavdar, Ahmet
Concrete is the most widely used construction material in contemporary construction technology. In particular, it holds an important place in the building industry in the world. Since concrete is a nonhomogeneous material, determining the strength of concrete accurately is quite difficult. In this respect, to check the mechanical properties of concrete in-situ, nondestructive test (NDT) methods can be used. They are useful as they do not damage concrete; however, these test results are sometimes deceptive. To reduce these deceptive results, destructive test methods were proposed to increase the accuracy of nondestructive methods. The objective of this study is to determine the strength of concrete with different characteristic strengths using destructive and NDT methods, and to establish new relationships between the compressive strength of concrete and Schmidt rebound values, and ultrasonic wave velocities. For this purpose, 101 concrete cube samples were prepared. After 7 and 28 days of curing, Schmidt rebound and ultrasonic wave velocity tests were applied as NDT methods. New formulations and graphs were established by carrying out a multiple regression analysis between the ultrasonic wave velocities, Schmidt rebound values, and compressive strengths. Thus, a new combined NDT method was developed with a nomogram. Furthermore, the applicability and accuracy of the formula and graph obtained were investigated by comparing the results of core samples from existing structures. The most important findings obtained from the study are summarized below. The concrete strength can be determined with nondestructive formulas obtained with an accuracy of 85%. High strength concrete cube samples are obtained in-house with 1.6% deviation, and core samples in-situ can be obtained with 7.3% deviation with the newly developed NDT nomogram. These test results show that the newly developed NDT formulas in this study are a very good alternative for determining concrete strength in-situ.
- BildiriYalnız künye2018Behavior of T and X joints of elliptical hollow sections at both ambient and high temperatures
Ozyurt, E.; Wang, Y.C.; Heidarpour, A.; Zhao, X.-L.
This paper presents the results of a numerical study to develop a method to calculate the ultimate load carrying capacity of welded Elliptical Hollow Section (EHS) joints at elevated temperatures. Extensive numerical simulations, using the non-linear finite element package ABAQUS v6.14-1, have been conducted on EHS T-and X-joints subjected to brace axial compression or tension, considering a wide range of geometrical parameters, pre-stress in chord member and different type of joint orientations. The FE simulation results indicates that the equivalent RHS method is not appropriate for calculating the load carrying capacity of EHS joints at ambient temperature. At elevated temperatures, for T-and X-joints with braces welded to wide sides of chord, replacing the ambient temperature yield strength of steel by the elevated temperature value overestimates the ultimate load carrying capacity of axially loaded EHS T-and X-joints with compressive brace. Alternative design methods have been proposed.
- MakaleYalnız künye2018Experimental and numerical investigation of natural convection in a discretely heated vertical channel: Effect of the blockage ratio of the heat sources
Sarper, Bugra; Saglam, Mehmet; Aydin, Orhan
This study deals with the buoyancy induced flow and heat transfer in a parallel plate channel with a heat source array, which simulates an electronic package. The heat source array consists of four discrete protruding heat sources made of copper. The focus of this study is concentrated on the effect of heat source blockage ratio (br) on recirculating flow and cooling performance of the system. Studies are conducted both for flush mounted or protruding heat source cases. Four different values of the blockage ratio of the protruding heat sources (br = 0.125, 0.25, 0.375 and 0.5) are considered. The range of the modified Grashof number covers the values between 9.6 × 105 and 1.53 × 107. In the experiments, flow visualization and temperature measurements are conducted. Numerical studies are performed via ANSYS Fluent software. From the experimental results and numerical studies, it is found that buoyancy induced flow and cooling performance is significantly affected by the blockage ratio of the heat source array.
- MakaleAçık Erişim2018The investigation of the lattice strains and crystallite sizes of Y358 and Y123 high-temperature superconductors
Duzgun, Ibrahim
In this study, the Y358 phase, the newest high-temperature superconductor member of the yttrium barium copper oxide family, was produced using the solid-state reaction technique. The Y358 superconductor exhibited the Meissner effect at low temperature (77 K). The X-ray diffraction spectra indicated that the crystal structure was almost identical to that of Y123, but with some impurity peaks. An X-ray peak broadening analysis was applied to determine the lattice strain, and the medial crystallite size was calculated perpendicular to the surface of the superconductor specimens. As a result of the analyses, it was determined that the crystallite size of the Y358 superconductor was about 1.125 times larger than that of the Y123 superconductor.
- MakaleYalnız künye2018Hybrid global maximum power point tracking approach for photovoltaic power optimisers
Basoglu, Mustafa Engin; Çakir, Bekir
A new hybrid global maximum power point (MPP) tracking (MPPT) method is introduced in this study by using an improved 0.8 VOC model-based algorithm containing a smart power scanning procedure which is based on the sign of a change of photovoltaic (PV) module power. By courtesy of this procedure, the global MPP is determined effectively and within a small scanning time interval. The effectiveness of the proposed global MPPT algorithm has been validated by experimental studies. One of the buck-boost converter types, a single-ended primary inductance converter was implemented in this context. Experimental results show that tracking efficiency in the proposed algorithm is very satisfactory since blind scanning is prevented. Furthermore, it is presented in the experimental results that tracking efficiency is bigger in the proposed shading detection approach by up to 11.29% than the other technique which monitors voltage and current variations. In addition, there are no high software and hardware burdens which make this MPPT algorithm applicable especially in the smart alternating current module, module-integrated converters, PV power optimisers, and module level distributed MPPT applications.