Browsing by Author "Yilmaz, M."

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Analysis and Detection of Mucilage Bloom from Multispectral Satellite Images
(Institute of Electrical and Electronics Engineers Inc., 2022) KüÇük, S.; Abaci, B.; Dede, M.; Yuksel, S.E.; Yilmaz, M.
In this paper, we aim to detect and observe the mucilage formations in the Sea of Marmara by means of Sentinel-2A satellite data. For this purpose, we produce mucilage index maps by utilizing the relationship between the spectral bands of Sentinel-2A. Sentinel-2A has four 10m fine bands and six 20m coarse bands. To compute the mucilage index, the spectral bands must have the same spatial resolution. Although the Sentinel-2A does not have a panchromatic band, the spatial resolution of the 20m bands can be increased to 10m thanks to its four fine bands. Based on the results of this analysis, we utilize seven of the existing image fusion approaches to enhance the spatial resolution of 20m bands to 10m. We monitor changes in mucilage formations over time with the mucilage maps acquired by using fused images through the mucilage index. © 2022 IEEE.
Dependence of Electrical Parameters of Co/Gold-chloride Diode on Frequency and Illumination
(Elsevier, 2021) Erdogan, E.; Yilmaz, M.; Aydogan, S.; Incekara, U.; Sahin, Y.
In this study, metal-semiconductor contact with an organic interlayer was fabricated. Ideality factor (n), barrier height (phi(b)), and series resistance (R-s) values for Co/Gold-chloride/p-Si structure were calculated for dark and 100-400 mW/cm(2) light illumination intensities. The current-voltage (I-V) measurements were used to extract the electrical parameters of Co/Gold-chloride/p-Si device such as ideality factor, barrier height and series resistance using different methods like thermionic emission theory and Norde method. The n values were found in the range of 2.00-2.52 and the phi(b) were calculated in the range of 0.50-0.53 eV and under light power intensities. Additionally, frequency-dependent capacitance-voltage (C-V) measurements were done at room temperature and frequency range from 100 kHz to 1 MHz. The results show that at sufficiently high frequencies, the interface cannot flow A.C signals. Furthermore, barrier height was also calculated from the C-2-V plot for given the frequency range for Co/Gold-chloride/p-Si device. With this study, it has been shown that the rectifier contact of the organic-inorganic structure formed with suitable organic and inorganic semiconductor can be formed and this structure can be used in optoelectronic applications.
Differential Expression of LOXL4 in Normal and Tumour Tissue Samples of Laryngeal Squamous Cell Carcinoma
(Wiley, 2016) Yilmaz, M.; Suer, I.; Karatas, O. F.; Cansiz, H.; Ozen, M.
Objective: Head and neck cancer is the sixth most common cancer in worldwide with an increasing incidence rate in recent years. LOXL4 is expressed in several tissues, and its expression has been shown to display a significant correlation with local lymph node metastasis. In this study, we aimed to explore the LOXL4 expression level in metastatic and non-metastatic LSCC tissues and to determine its prognostic significance. Study design: Basic science research study. Setting: University hospital. Participants: A total of 40 patients were included in the study. Main outcome measure: LOXL4 expression status in metastatic, non-metastatic LSCC and normal tissue samples was investigated by quantitative reverse-transcription PCR. Results: We demonstrated that LOXL4 was significantly overexpressed in LSCC tumour tissue samples in comparison with the corresponding normal tissues (P < 0.001); however, no significant relationship has been found between LOXL4 expression and either the metastatic potential or the T classification of the specimens. Conclusions: Although expression of LOXL4 is not statistically associated with neck metastases, we showed that LOXL4 expression significantly increased in laryngeal cancer.
Hierarchical Chinese Postman Problem with Fuzzy Travel Times
(University Sistan & Baluchestan, 2021) Sokmen, O. C.; Yilmaz, M.
The hierarchical Chinese postman problem (HCPP), one of the kinds of Chinese postman problem (CPP), aims to visit at least once the arcs are classified according to their precedence relations and to find the shortest tour or tours. In HCPP, if the travel time values between two nodes constituting the cost are not crisp, this problem type can be said to be the hierarchical Chinese postman problem with fuzzy travel times (HCPP-FTT). In real-life problems, as the travel time between the nodes is not fixed due to various factors, in this study triangular fuzzy numbers are used at objective function coefficients of a small-size sample problem. Different ranking methods are used to defuzzify the fuzzy numbers and the acquired results are compared. The mathematical model formed is resolved using CPLEX solver GAMS 24.2.3 software. Besides, in this study, a large-size real-life problem was discussed. The objective function coefficients representing the travel time between the two nodes in the case study discussed were considered as trapezoidal fuzzy numbers. Due to the NP-hard nature of the problem, the mathematical model cannot find solutions in large size problems in the appropriate time interval. For this reason, in this study, the heuristic method based on the Greedy Search (GS) algorithm and the meta-heuristic method based on ant colony optimization (ACO) is proposed for the solution of the real-life problem. The proposed algorithms are coded using the Matlab-2019b programming language. Using the developed algorithms, the results of different ranking methods and solution times were compared.
Hierarchical Chinese Postman Problem with Fuzzy Travel Times
(University of Sistan and Baluchestan, 2021) Sokmen, O.C.; Yilmaz, M.
The hierarchical Chinese postman problem (HCPP), one of the kinds of Chinese postman problem (CPP), aims to visit at least once the arcs are classified according to their precedence relations and to find the shortest tour or tours. In HCPP, if the travel time values between two nodes constituting the cost are not crisp, this problem type can be said to be the hierarchical Chinese postman problem with fuzzy travel times (HCPP-FTT). In real-life problems, as the travel time between the nodes is not fixed due to various factors, in this study triangular fuzzy numbers are used at objective function coefficients of a small-size sample problem. Different ranking methods are used to defuzzify the fuzzy numbers and the acquired results are compared. The mathematical model formed is resolved using CPLEX solver GAMS 24.2.3 software. Besides, in this study, a large-size real-life problem was discussed. The objective function coefficients representing the travel time between the two nodes in the case study discussed were considered as trapezoidal fuzzy numbers. Due to the NP-hard nature of the problem, the mathematical model cannot find solutions in large size problems in the appropriate time interval. For this reason, in this study, the heuristic method based on the Greedy Search (GS) algorithm and the meta-heuristic method based on ant colony optimization (ACO) is proposed for the solution of the real-life problem. The proposed algorithms are coded using the Matlab-2019b programming language. Using the developed algorithms, the results of different ranking methods and solution times were compared. © 2021, University of Sistan and Baluchestan. All rights reserved.
An Investigation of Spray Deposited CdO Films and CdO/P-Si Heterojunction at Different Substrate Temperatures
(Springer, 2021) Turgut, G.; Aydogan, S.; Yilmaz, M.; Ozmen, A.; Kacus, H.
In this study, CdO films were successfully obtained by using a homemade chemical spray pyrolysis technique. The crystal structures of the CdO thin films improved due to an increase in the substrate temperature when the spray time was kept constant. Additionally, CdO film deposited at 250 degrees C exhibited amorphous crystal structure. The surface morphology of the samples was evaluated by scanning electron microscope (SEM) and it was observed that well-defined granules started to be clearly seen when the substrate temperature increased. Optical properties of CdO films were also investigated by using an ultraviolet-visible (UV-Vis) spectrophotometer, and the optical band gap of CdO varied from 2.57 eV to 2.73 eV with increasing substrate temperature. The electrical performance of the CdO films in the Au/CdO/p-Si device were determined by I-V measurements. According to the results, it was found that diode parameters depend on the changing properties of CdO in terms of the substrate temperature.
An Investigation of Spray Deposited Cdo Films and Cdo/P-si Heterojunction at Different Substrate Temperatures (Vol 73, Pg 566, 2021)
(Springer, 2021) Turgut, G.; Aydogan, S.; Yilmaz, M.; Ozmen, A.; Kacus, H.
This article was corrected to remove extraneous units of eV for ideality factor introduced during the production process.
Modification of Barrier Diode with Cationic Dye for High Power Applications
(Elsevier GmbH, 2021) Erdogan, E.; Yilmaz, M.; Aydogan, S.; Incekara, U.; Kacus, H.
Current-voltage (I-V) measurements of Au/methylene blue (MB)/p-Si/Al diode were taken at room temperature, in the dark and under illumination and also in a wide temperature range (100-360 K). Schottky diode showed non-ideal current-voltage behavior at 360 K and 100 K with ideality factors (n) equal to 1.81-1.46 and 3.52-2.73, respectively, using TE and Cheung methods. Experimental barrier height (phi(b)) values of the diode were determined as 0.29 eV for TE, 0.33 eV for Cheung and 0.38 eV for Norde at 100 K, and 0.79, 0.81, and 0.87 eV at 360 K, respectively. Series resistance (R-s) was found with the help of Cheung functions and Norde functions. The results show that the produced diode can be used in a variety of optoelectronic applications.
Structural and Morphological Properties of Al-Doped ZnO Nanoparticles
(Iop Publishing Ltd, 2016) Akdag, A.; Budak, H. F.; Yilmaz, M.; Efe, A.; Buyukaydin, M.; Can, M.; Sonmez, E.
Zinc oxide nanoparticles have a wide area of use because of their unique properties such as catalytic, electrical, and optical properties and low cost. Since the suitable additive materials can be changed the electrical and optical properties of zinc oxide, the demand of the industrial commercial area to the zinc oxide increased. In this study, Al doped ZnO nanoparticles produced by using the methods of reduction thought having materials of the Zn(NO)(3), AlCl3 and NaOH. XRD, SEM and EDS used for making analyzing of structural and dimensional of particles. The analyses show that the large amount of the Al3(+) ions did nut substitute with Zn2(+) successfully with the reduction method. XRD and EDS results confirm this situation.
Titanium Doping Effect on the Characteristic Properties of Sol-Gel Deposited ZnO Thin Films
(Redakcia Kovové Materiály, 2015) Yilmaz, M.; Turgut, G.
Undoped and Ti doped ZnO thin films were made by sol-gel spin coating, and the investigation of structural, morphological and optical features was applied as a function of the doping ratio. The films had a polycrystalline ZnO wurtzite crystal structure with (002) preferential direction and film crystallinity decreased with Ti doping content. The SEM studies indicated that the nanoparticle structure of undoped films changed to nano-network like structure with Ti doping. The transmittance and optical band gap of undoped sample firstly increased with 1 at.% Ti doping and then they decreased with higher Ti level. Consequently, the present work suggests that the characteristic properties of ZnO can be tailored with Ti doping and ZnO:Ti films have a potential importance for usage in many technological applications.