Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Merdan, Mehmet(9)
- Anaç, Halil(3)
- Öztürk, Serkan(3)
- Açikgöz, Pınar(2)
- Beki̇Ryazici, Zafer(2)
- Kesemen, Tülay(2)
- Terhan, Meryem(2)
- Yüksek, Halil İbrahim(2)
- Abak, Sena Saliha(1)
- Araz, Onur(1)
- Ari̇Foğlu, Uğur(1)
- Beker, Yasemin(1)
- Bingöl, Özkan(1)
- Bi̇Ngöl, Özkan(1)
- Boynueğri̇ Kaplan, Emine(1)
- Cakir, Tufan(1)
- Dedeturk, Mutlu(1)
- Demir, Yasin(1)
- Ertekin, Özteki̇N(1)
- Gerdan, Serpil(1)
- Güngör, Okan(1)
- Kahya, Volkan(1)
- Kaya, Aynur(1)
- Necati, Çeli̇K(1)
- Ozturk, Kasif Furkan(1)
- Pehlıvan, Levent(1)
- Sari, Mahmut(1)
- Yalcin, Numan(1)
- Öktem, Selami(1)
- Şengül, Süleyman(1)
- Şişman, Şeyma(1)
- Şi̇Şman, Şeyma(1)
- Şüküroğlu, Ebru Emine(1)
Yayınlar
- MakaleAçık Erişim2025Mathematical analysis of fractional order Covid 19 epidemic model
Açikgöz, Pınar; Merdan, Mehmet
This article aims to examine the dynamics of the fractional epidemic model of covid 19. The model in question incorporates the notion of a compatible derivative. Given their consistent and worldwide characteristics, fractional derivatives are presently employed to address nu-merous practical issues. In addition, we employ two numerical techniques, namely the con-formal differential transform and the variational iteration approach, to provide an approxi-mate solution for the given model. The research closes by providing an in-depth analysis and visually representing the numerical findings. Furthermore, it has been demonstrated that the solution obtained is convergent.
- MakaleAçık Erişim2025Investigation of fractional order covid-19 model with q-homotopy analysis transform method
Merdan, Mehmet; Açikgöz, Pınar
The primary objective of this paper is to derive approximate analytic solutions for the time fractional-order Covid-19 model by employing the q-homotopy analysis transform method (q-HATM) and the Laplace transform homotopy perturbation method (LT-HPM). The covid 19 model is a system of five-dimensional nonlinear ordinary differential equations. Moreover, this method applies even to more complex partial differential equations originating from mathematical biology, demonstrating computational efficiency and wide application. In this study, Caputo fractional derivative is used to obtain the fractional system and Laplace transformation is applied to analyze the approximate solutions of the system. Graphical results are presented and discussed quantitatively to illustrate the approximate solution. Copyright 2021, Yıldız Technical University.
- MakaleAçık Erişim20241D fuzzy inverse logic method and its use in the design of thick reinforced concrete columns
Ertekin, Özteki̇N
In this study, without using any uniaxial force and bending moment (N-M) interaction diagrams, designs were carried out on thick columns subjected to uniaxial bending and compression by a novel 1 dimensional (1D) Fuzzy Inverse Logic (FIL) method. For this purpose, firstly, a Fuzzy Logic (FL) model was developed and the FIL method was applied to it thereafter. While, the cross-section width (b), the cross-section height (h), the rebar diameter(f), the numbers of reinforcement rows (Rx and Ry) placed into the cross-section in X and Y directions, the characteristic concrete compressive strength(fck) and the axial force ratio Nr=N/ (b.h.(fck/1.5)) were taken as variable parameters, concrete cover thickness (c), rebar strength (fyd) and k1 parameter defined for the concrete pressure block were kept constant in the developed FL model. After designs were performed on 15 columns having different variable variations by the 1D FIL method, moment bearing capacities of the obtained 9737 alternative designs determined conventionally were compared with the desired moment values. The evaluations made on the comparisons show that the FIL method is not only a very effective artificial intelligence method for the design of reinforced concrete thick columns but also a promising method for many other problems such as control, optimization, design, etc.
- MakaleAçık Erişim2024Investigation of friction behavior of TiO2: Al2O3 composite coating formed on AA2024 alloy by micro-arc oxidation
Boynueğri̇ Kaplan, Emine; Şüküroğlu, Ebru Emine
In this study, an alumina (Al2O3) ceramic coating and a composite coating containing titanium dioxide (TiO2) particles were prepared on surfaces of AA2024 substrates by micro-arc oxidation (MAO) treatment. The effects of micro-sized (≈20-30 µm) TiO2 particles incorporated into electrolyte on the microstructure, phase and chemical composition, thickness, and friction behavior of the coating were investigated. The surface morphologies of the coatings were analyzed by scanning electron microscopy (SEM). The phase and chemical compositions of the coatings were evaluated by means of X-ray diffraction (XRD) and energy-dispersive X-ray spectrometry (EDS), respectively. The friction coefficient of the coatings was investigated using a pin-on-disc tribometer under condition of dry slip sliding. Moreover, the wear tracks were analyzed by SEM. Addition of TiO2 particles into the electrolyte resulted in the reduction in number of pores and formation of smaller and more uniform pores in comparison with the Al2O3 ceramic coating. XRD analyses demonstrated that the TiO2:Al2O3 composite coating was composed of anatase-TiO2 and rutile-TiO2, as well as pure aluminum, α-Al2O3 and γ-Al2O3 which are the primary phases. The friction tests showed a significant reduction in the friction coefficient of the composite coated samples which contains titanium oxide (TiO2) particles in comparison with Al2O3 coated and uncoated samples. Copyright 2021, Yıldız Technical University.
- MakaleAçık Erişim2024Analysis of grover's quantum search algorithm on a classical computer: Identifying opportunities for improvement
Necati, Çeli̇K; Bi̇Ngöl, Özkan
In this paper, Grover’s quantum search algorithm is analyzed using a classical computer by calculating the amplitudes and the probabilities of finding a single marked state for n=5, 10, 15, 20, 25, and 27 qubit states. The calculations show that the marked state can be found in iterations, where N = 2n is the number of items. The possibility of improving Grover’s search algorithm to find a single item in N search elements is discussed by calculating the amplitudes and hence the probabilities of finding a single marked state for n=5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 qubit states. The calculations showed that the marked state could be found with sufficiently high probability in (ln(N)) iterations. This is quite a remarkable speed-up that can be achieved to find a single marked element in an unsorted N search element. Copyright 2021, Yıldız Technical University.
- MakaleAçık Erişim2024On solutions of time fractional order random HIV/AIDS modelling
Merdan, Mehmet; Öktem, Selami
In this study, The fractional random HIV/AIDS model approximate analytical solutions were produced using the differential transformation method. The approximate analytical solution of the fractional order Random HIV/AIDS model was obtained with the help of the differential transformation method. For the fractional random HIV/AIDS model, which was created by choosing the initial conditions from the exponential, beta, and normal distributions, graphic simulations of the expected value, variance, and confidence intervals of the most commonly used probability characteristics were obtained with the help of the MATLAB package program. Results obtained are interpreted.
- MakaleAçık Erişim2023Wong-Zakai approximation for stochastic models of smoking
Şengül, Süleyman; Beki̇Ryazici, Zafer; Merdan, Mehmet
In this study, Wong-Zakai approximation method has been used to obtain approximate solutions for two compartmental models of smoking dynamics. Stratonovich stochastic differential equation systems are obtained for these two stochastic models for the application of Wong-Zakai method. Wong-Zakai method is used together with the predictor-corrector deterministic approximation method where Adams-Bashforth method is used as the predictor pair and Adams-Moulton method is used as the corrector pair. Stochastic Runge-Kutta IV, Euler-Maruyama and stochastic Runge-Kutta strong order 1.0 schemes are also used to investigate the models and the results are compared to the results from Wong-Zakai approximation. The comparison shows that Wong-Zakai method is a reliable tool for the analysis of stochastic models and can be considered as an alternative investigation method for modeling studies. Solution graphs, error graphs and numerical results have been given as evidence to show that Wong-Zakai method can also be a reliable method for analyzing various models. An alternate technique for parallelizing the algorithm has also been given to decrease CPU times for Wong-Zakai method. This technique is suggested to overcome the extra calculation load that comes with Wong-Zakai method.
- MakaleAçık Erişim2023Solutions of multiplicative linear differential equations via the multiplicative power series method
Yalcin, Numan; Dedeturk, Mutlu
In this study, fundamental concepts of multiplicative analysis is given. Also, definitions of multiplicative Taylor series (MTS), multiplicative Taylor polynomials (MTP), and multiplicative power series (MPS) are given. Solutions of higher-order multiplicative linear differential equations (MLDE) are investigated with the help of the MPS method. Applications of MPS method are done for first, second, and third-order multiplicative ordinary linear differential equations. Copyright 2021, Yıldız Technical University.
- MakaleAçık Erişim2023Energy, exergy analysis and optimization of insulation thickness on buildings in a low-temperature district heating system
Terhan, Meryem; Abak, Sena Saliha
In the study, energy and exergy analysis of the buildings on a campus in Turkey are conducted by using actual operating data and taking measurements in the district heating system as a case study. The energy and exergy demands, losses that stem from all buildings are calculated according to average daily outdoor temperature data. Due to the high heat losses in the buildings, determining the optimal insulation thickness for the exterior wall should be investigated. Therefore, optimal insulation thicknesses, energy savings, fuel consumptions and payback periods of the insulation material on the exterior wall of the building are examined by using Life Cycle Assessment and P1–P2 method for natural gas. Optimal insulation thicknesses are calculated for different insulation materials such as XPS, glass wool, rock wool and EPS for the climatic regions (HDD=800–4250°C days). According to average exergy losses from the building components per unit area, the average total exergy loss is calculated as 2.39×10-2 kW/m2.year and 1.42×10-3 kW/m2 (5.92%) of this loss stems from the exterior walls, 1.93×10-3 kW/m2 (8.07%) from the floors, 7.37×10-4 kW/m2 (3.08%) from the roofs, 1.58×10-2 kW/m2 (65.99%) from the windows and doors, 4.04×10-3 kW/m2 (16.92%) from the ventilation with infiltration. Energy requirement values of the building are found between 2.68–25.70 kWh/m3 towards from the warmest to the coldest climatic region for the uninsulated wall. In the un-insulated state, fuel consumption varies between 1.93-18.48 m3/m2 from the warmest to the coldest region. The optimal insulation thickness values of the building’s exterior wall are calculated as between 2.3–10.0 cm according to different climatic regions. In-state of exterior wall insulation of 3 cm, fuel consumption decreases by 46.63%–53.46% compared to different insulation materials and climatic regions compared to the un-insulated state
- MakaleAçık Erişim2023Detection of pneumonia from pediatric chest X-ray images by transfer learning
Demir, Yasin; Bingöl, Özkan
When pathogens such as viruses, bacteria and fungi attack the lungs, the alveoli fill with inflamed fluid, causing pneumonia. Early diagnosis of this disease, which has fatal outcomes especially in children under 5 years old, is very important in controlling undesirable situations. Chest X-ray images play an important role in the diagnosis of pneumonia. In addition, the fact that the amount of radiation is lower than imaging devices such as tomography and the possibility of being accessible even from rural areas creates an advantage for X-ray devices. However, X-ray images that are not always clear or human conditions such as fatigue and lack of attention can make it difficult for specialists to detect pneumonia. In this study, a transfer learning-based convolutional neural network (CNN) approach is proposed, which can help specialists in the early and accurate diagnosis of pneumonia in children and, classify healthy and diseased individuals through Chest X-ray images. As a result of the study, an original CNN was proposed by adding additional layers to the AlexNet architecture layers and a test accuracy of 96.31% was obtained. Copyright 2021, Yıldız Technical University.
- MakaleAçık Erişim2021Global stability of Susceptible Diabetes Complication (SDC) model in discrete time
Şi̇Şman, Şeyma; Merdan, Mehmet
In this study, the mathematical model (DC) of diabetes disease is discussed. This model divides people into (D) uncomplicated and (C) complex diabetics two. In addition, diabetes is a disease known to be caused by genetic and environmental factors, and this factor is one of the main causes of genetic disorder at birth. Considering these two factors, the diabetes complication (SDC) model, which is sensitive from the diabetes complication (DC) model, is being developed. In this model, the responsive diabetes complication (SDC) model of a nonlinear system of differential equations is transformed into a discrete-time system of equations. The positivity and limitation of Model solutions were examined R0 the basic increment number is calculated. If R0 < 1, it has a global asymptotically stable balance for the situation where there is no genetic disorder at birth, and for R0 < 1, the system has an unstable balance. In addition, random behavior of the discrete model was examined for different probability distributions.
- MakaleAçık Erişim2021PREDICTION SULPHURIC ACID AND WATER VAPOUR DEW POINT TEMPERATURES OF FLUE GASES AND COMBUSTION ANALYSIS FOR SOLID FUELS IN TURKEY
Terhan, Meryem
In the study, the combustion analysis is examined for the solid fuels in Turkey. The principal aim of the analysis is determined the limits and obstacles in the design heat exchanger to avoid the corrosion risk on the heat exchanger surfaces in the latent heat recovery applications from waste flue gas. To do this, in which regions of the heat exchanger the flue gas temperature reached to the sulphuric acid and water vapour dew point temperatures are required to predict. In order to predict the condensing zone, an air preheater for the coal-fired boiler in a heating system is designed using finite difference method. Designed the air preheater is consists of the counter-cross flow, U-shaped stainless steel tube bundle. The tube is discredited 200 cells to one-dimensional during the flow. The heat transfer rates, the flue gas and air inlet and outlet temperatures, surface temperatures of the tube wall, the mole fractions of water and sulphuric acid vapour, the other non-condensing gases in the flue gas are calculated in each discrete cell. According to the results of the study, while the dew point temperature of the water vapour changes over the range 30-40 °C, the acid dew point temperature waves to 125 °C from 140 °C for the coal types mined in Turkey.
- MakaleAçık Erişim2021Estimation of ground types in different districts of Gümüşhane province based on the ambient vibrations H/V measurements
Öztürk, Serkan; Beker, Yasemin; Sari, Mahmut; Pehlıvan, Levent
In this study, an attempt was made to estimate the ground types for Torul, Kürtün, Kelkit, Şiran and Köse districts of Gümüşhane, Turkey, by analyzing the predominant frequency and H/V ratio from microtremor data through the single station microtremor H/V ratio of Nakamura technique. For all districts, predominant frequencies show a general distribution between 1.36 and 9.84 Hz, H/V ratios between 1.01 and 9.58. According to these variations, three transient zones can be suggested as i) Z1, stiff rock composed of gravel, sand and other soils mainly consisting of tertiary or older layers with period of 0.1 to 0.2s, ii) Z2, sandy gravel, stiff sandy clay, loam or sandy alluvial deposits whose depths are 5m or greater with period of 0.2 to 0.4s, and iii) Z3, standard grounds other than type Z1, Z2 or Z4 (alluvial deposits whose depths are 5m or greater) with period of 0.4 to 0.8s. These r esults s uggest that p redominant period obtained from predominant frequency shows significant changes based on the soil formation, and H/V ratio highly corresponds to these subsurface properties. Soil-structure interaction can also be evaluated by considering these results and possible resonance risk can be investigated for building resonant frequency in these residential districts in the next. Thus, this type of application and evaluation of microtremor data may provide primary and useful information for other geophysical, geological and geotechnical studies such as planning the seismic resistant infrastructure, detecting the small-scale seismic risks and making a suitable and reliable seismic hazard microzonation in Gümüşhane. Copyright 2021, Yıldız Technical University.
- MakaleYalnız künye2020APPLICATION OF CRANK-NICOLSON METHOD TO A RANDOM COMPONENT HEAT EQUATION
Anaç, Halil; Merdan, Mehmet; Kesemen, Tülay
In this study, the solution of a random component heat equation is obtained by using Crank-Nicolson Method. The initial condition of this equation is examined by Normal distribution. The expected value and variance of solution of this equation are obtained. Crank-Nicolson method is applied to analyze the solution of this equation. Also, the solution and the graphs of the expected value and variance are obtained by using MATLAB software. The results of the heat equation are compared with random characteristics of this equation. Firstly, a random component heat equation is solved by this method.
- MakaleYalnız künye2020A GENERAL OVERVIEW ON THE REGION-TIME BEHAVIORS OF THE RECENT EARTHQUAKE ACTIVITY IN THE MARMARA REGION OF TURKEY
Öztürk, Serkan; Gerdan, Serpil
The principal aim of this study is to make a general assessment of the regional and temporal behaviors of the seismicity in the Marmara region of Turkey. For this purpose, the well-known spatio-temporal tools such as Mc-value, b-value, Dc-value, Z-value, recurrence period and annual probability were evaluated. The data catalog is homogeneous for local magnitude, ML, and includes 18,662 events with 0.4≤ML≤5.7 between 2000 and 2020. Earthquake magnitudes change between 1.5 and 3.0 and hence, Mc-value was taken as 2.7. b-value was calculated as 1.14±0.07 and the earthquakes with small magnitude can be effective on this relatively large value. Dc-value was estimated as 1.57±0.03 with a scale invariance from 5.03 to 87.64 km. This moderate value means that distance between the epicenters approaches the diameter of cluster and, earthquake activity is more clustered in larger areas or at smaller scales. Time-magnitude estimations of annual probability and recurrence period indicate that the Marmara region has an intermediate/long terms hazard for the occurrence of strong/large earthquakes. Anomaly regions with low b-value and large Z-value observed at the beginning of 2019 can be considered as the most likely regions for strong/large earthquake occurrences in the next. As a remarkable fact, a correlation and combined interpretation of these seismotectonic parameters may supply a preliminary and essential perspective in the seismic hazard for strong/large earthquake occurrences in the Marmara region of Turkey in the intermediate/long terms.
- MakaleYalnız künye2020AN OVERVIEW TO THE DYNAMIC BEHAVIOUR OF THE INVERTED T TYPE CANTILEVER RETAINING WALL TAKING INTO ACCOUNT SOIL STRUCTURE INTERACTION PHENOMENON
Cakir, Tufan; Ozturk, Kasif Furkan
The dynamic response of the cantilever retaining walls is affected by many factors such as the geometry of the wall, the earthquake frequency content, the wall flexibility, the backfill characteristics, and the soil structure interaction. Therefore, it may not be possible to analyse all aspects of the dynamic response of the cantilever retaining walls in spite of their simplicity. It is also well known that some unfavourable effects on the behaviour of the walls may impair the balance of the wall. In this context, the study aims to investigate the dynamic response of the T type cantilever retaining wall considering soil structure interaction. In line with this purpose, the soil structure interaction system is produced with a three dimensional finite element model. The seismic analyses are performed in time domain using C-OLC360 component of 1983 Coalinga earthquake, and four different foundation soil systems are used in these analyses. The elasto-plastic behaviour of the backfill and the foundation soil are represented with Drucker-Prager material model. In order to reflect the material damping of the system, Rayleigh damping is utilized considering mass and stiffness proportional dampings. In addition, the viscous boundary dashpot elements which consider the criteria of Lysmer and Kuhlemeyer for wave propagation, are placed around the boundaries of the numerical model. The results are examined in terms of both the stresses and displacements. The findings have revealed that the dynamic response of the T shaped cantilever retaining walls is considerably affected by the soil structure interaction.
- MakaleYalnız künye2020ANALYSIS OF RANDOM DISCRETE TIME LOGISTIC MODEL
Merdan, Mehmet; Şişman, Şeyma
In this study, the behavior of the logistic difference model is investigated under random conditions using discrete probability distributions. The logistic difference model consists of parameters that depend on the population models to be used. For the study of random difference equation population models, the parameters are treated as random variables which constitutes the basis of the study. Random models were created using Uniform, Bernouilli, Binom, Negative Binomial (or Pascal), Geometric, Hypergeometric, Poisson distributions and their numerical characteristics are obtained through their simulations. Then, the results showing random numerical characteristics such as expected value, variance, standard deviation, coefficient of variation and confidence intervals were obtained with MATLAB package program. Analysis of random logistic difference model is given with the help of graphics and tables.
- MakaleYalnız künye2020MODELING OF THREE-PHASE THREE-LEVEL RECTIFIER WITH SPACE VECTOR PULSE WIDTH MODULATION METHOD IN MATLAB/SIMULINK PROGRAM
Yüksek, Halil İbrahim; Ari̇Foğlu, Uğur
Multi-level rectifiers have low harmonic content and electromagnetic interference (EMI). In recent years, especially in medium and high-power applications are increasing use. As the voltage level per switch and switching frequency are low, the multi-level rectifiers have low losses and high efficiency. In this study, three-level neutral point clamped (NPC) rectifier topology with pulse width modulation (PWM) is investigated and the decoupled equations in the d-q synchronous rotating axis of the rectifier are given and a space vector PWM (SVPWM) control algorithm based on the d-q synchronous rotating axis of three-level rectifier is proposed. The control of the whole system is provided by voltage oriented control (VOC) strategy, which enables the realization of control in cascade system with outer voltage and inner current control blocks. This paper is focused on explaining in detail modulus optimum and symmetrical optimum methods used in the design of the inner current and outer voltage PI controllers of the three-level rectifiers, respectively. PI voltage controller is used to keep the rectifier output voltage constant, and PI current controller is used to reduce the harmonic content of the grid current. In addition, a simplified method compared to conventional SVPWM is used to calculate switching times and switching sequences. In this study, three-level rectifier is simulated in Matlab / Simulink with the help of SVPWM. The performance of the circuit has been tested by changing both the load value and the load voltage suddenly and successful results have been achieved.
- MakaleYalnız künye2020MODELING OF BOOST AND CUK CONVERTERS AND COMPARISON OF THEIR PERFORMANCE IN MPPT
Güngör, Okan; Yüksek, Halil İbrahim
The efficiency of photovoltaic (PV) panel systems depends on the structure of the photovoltaic cells and the transfer of energy from the PV panel to load. The focus of this study is energy transfer. The most important component in the energy transfer is maximum power point tracking (MPPT). The MPPT consists of two components: the algorithm for calculation the maximum power and the hardware for power generating. This study investigates how some the DC-DC converters (hardware) impact on the performance of the MPPT under six different environmental conditions by using two different duty cycle calculation methods. Contribution of this study to the literatüre is to analyze the performance of some the DC-DC converters in MPPT by completely eliminating the effect of MPPT algorithms. As a result of this study, while using the Boost converter in MPPT applications, the internal resistance of the PV panel must be equal or smaller than load resistance. However, the Cuk converter can reach to maximum power point in all conditions such as temperature, radiation and load.
- MakaleYalnız künye2019GLOBAL STABILITY IN A PATHOGEN-SPECIFIC CD8 IMMUNE RESPONSE PREDICTION MODEL
Anaç, Halil; Merdan, Mehmet; Beki̇Ryazici, Zafer
In this study, a system of ordinary differential equations used for modeling pathogen-specific CD8 cell immune response is studied. The positivity and the limitation of the model solutions are proven. The equilibrium points in the cases with the presence and the absence of the pathogen are determined and their stabilities are investigated. Furthermore, the essential reproduction number is obtained for the system. The conditions of the reproduction number for the stability of the equilibrium are shown and numerical examples are given for supporting the analytical results.