06. Meslek Yüksekokulları

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Citation - WoS: 27
Citation - Scopus: 34
Analysis of Effect Factors on Thermoelectric Generator Using Taguchi Method
(ELSEVIER SCI LTD, 2020) Terzioğlu, Hakan
Due to technological developments in recent years, the need for domestic and industrial electric power is increasing day by day. Alternative energy resources have become more important to reduce production costs by converting waste energy into electricity. In this study, a research was carried out to increase the efficiency and on the factors which were effective in Thermoelectric Generators (TEG) used in the production of electrical energy by using thermal sources from alternative energy sources. In this study, the effects of heat transfer performance of the materials (copper, aluminum and brass) on which thermal water is carried, and the effects of water pressure and velocity on the performance of TEGs were investigated. Taguchi method was used to determine the performance effects in the most accurate way. Taguchi method used three levels with three factors: material (copper, aluminum and brass), engine speed (I, II and III) and water pressure (1-2.5-3.5 bar). In addition, in the Taguchi method, the orthogonal array was used and the optimum operation time was significantly reduced. In this study, TEG1-12706 and TEG1-12710 were performed in 2 different TEGs. 27 experiments were carried out for each TEG under different materials, speed and pressure of water with the experiment set up in this study. When the test results were analyzed by Taguchi method, it was determined that the material was the most important factor in determining the output power and efficiency in the production of electrical energy by using TEG (approx. 89%) and it was seen that the pressure and engine speed had almost no role. (C) 2019 Published by Elsevier Ltd.
Citation - WoS: 20
Citation - Scopus: 29
Classification of Flame Extinction Based on Acoustic Oscillations Using Artificial Intelligence Methods
(ELSEVIER, 2021) Taşpınar, Yavuz Selim; Köklü, Murat; Altın, Mustafa
Fire, one of the most serious disasters threatening human life, is a chemical event that can destroy forests, buildings, and machinery within minutes. For this reason, there have been numerous methods developed to extinguish the fire. Within the scope of this study, a sound wave flame extinction system was developed in order to extinguish the flames at an early stage of the fire. The data used in the study were obtained as a result of experiments conducted with the developed system. The created dataset consists of data obtained from 17,442 experiments. It is aimed to classify the fuel type, flame size, decibel, frequency, airflow and distance features, and the extinction-non-extinction status of the flame through rule-based machine learning methods. In the study, rule-based machine learning methods, ANFIS (Adaptive-Network Based Fuzzy Inference Systems), CN2 Rule and DT (Decision Tree) were used. The methods of Box Plot, Scatter Plot and Correlation Analysis were utilized for statistical analysis of the data. As a result of the classifications, respectively, 94.5%, 99.91%, and 97.28% success were achieved with the ANFIS, CN2 Rule, and DT methods. As a result of the evaluations made by using Box Plot, Scatter Plot and Correlation Analysis.
Citation - WoS: 20
Citation - Scopus: 18
Comparison of Different Optimization Based Land Reallocation Models
(ELSEVIER SCI LTD, 2020) Uyan, Mevlüt; Tongur, Vahit; Ertunç, Ela
Land reallocation, which is an optimization problem in the field of engineering, is the process of reallocating parcels to pre-determined blocks according to the preferences of landowners. In practice, this is done manually and takes weeks or even months. The elongation of this process affects both the cost of the project and the project's acceptability by the landowners and thus the success of the project. Because the success of land consolidation projects is determined by the satisfaction of the landowners. For these reasons, the optimization-based land reallocation studies have been extensively carried out recently. However, these methods in the literature are not used in practice and the reallocation is still done manually. Therefore, for the first time in this study, two new reallocation models were developed to solve this problem by using Migration Birds and Simulated Annealing Algorithms and the results of these methods in a real project area were compared. Additionally, the results were compared to the conventional reallocation method (manual reallocation) to evaluate the performance of the methods developed. Both proposed methods provided a successful and practicable reallocation plan in a very short time with respect to the conventional one.
Citation - WoS: 20
Citation - Scopus: 20
Comparison of Microbiota and Volatile Organic Compounds in Milk From Different Sheep Breeds
(Elsevier Inc., 2021) Yusuf, B.; Ezgi, T.A.; Gonca, S.; Telli, Nihat; Gürkan, U.
In this study, we compared the microbiota and volatile organic compounds (VOC) present in the milk obtained from 3 different sheep breeds, namely Merino, Lacaune, and Assaf. Udder milk was collected from 21 animals, 7 from each breed. Bacterial microflora was determined metagenomically by extracting the DNA from the milk and analyzing the V3-V4 region of the 16S rRNA gene. Headspace solid-phase microextraction gas chromatography-mass spectrometry method was used to analyze VOC. The metagenomic analysis revealed (for Merino, Lacaune, and Assaf milk, respectively) Firmicutes (66.32, 69.36, and 57.08%), Actinobacteria (19.09, 7.67, and 19.40%), Proteobacteria (13.76, 21.06, and 22.19%), and Bacteroidetes (0.84, 1.91, and 1.33%) phyla in the milk samples. Lactobacillus was highly abundant in the milk of 3 breeds (29.64, 43.50, and 18.70%). The genera constituting more than 2% of all bacteria in all groups were Jeotgalicoccus (7.19, 5.34, and 10.77%), Enterococcus (5.18, 9.78, and 3.64%), and Corynebacterium (4.08, 3.00, and 13.44%). A total of 32 different VOC were identified by headspace solid-phase microextration analysis with 9, 30, and 24 different compounds from Merino, Lacaune, and Assaf breeds, respectively. Although ketone was the most abundant compound in Merino milk (71.84%), hydrocarbons were the most detected in Lacaune and Assaf milk (37.18% and 55.42%, respectively). A positive correlation was found between acetone, which was detected at the highest level in all groups, with Salinicoccus, Alloiococcus, Psychrobacter, and Dietzia. In addition, a negative correlation was found between the Lactobacillus genus, detected at the highest level in all groups, with methyl cyclopentane, 3-methylheptane, octane, decane, 3,3-dimethyloctane, and dodecane. Thus, differences were observed in the bacterial microflora and VOC in the sheep milk from different breeds under different feeding and breeding conditions. © 2021 American Dairy Science Association
Citation - WoS: 18
Citation - Scopus: 19
Development of Highly Luminescent Water-Insoluble Carbon Dots by Using Calix[4]pyrrole as the Carbon Precursor and Their Potential Application in Organic Solar Cells
(Amer Chemical Soc, 2022) Coşkun, Yağız; Ünlü, Fatma Yelda; Yılmaz, Tuğbahan; Türker, Yurdanur; Aydoğan, Abdullah; Kuş, Mahmut; Ünlü, Caner
Carbon dots (CDs) are carbon-based fluorescent nanomaterials that are of interest in different research areas due to their low cost production and low toxicity. Considering their unique photophysical properties, hydrophobic/amphiphilic CDs are powerful alternatives to metal-based quantum dots in LED and photovoltaic cell designs. On the other hand, CDs possess a considerably high amount of surface defects that give rise to two significant drawbacks: (1) causing decrease in quantum yield (QY), a crucial drawback that limits their utilization in LEDs, and (2) affecting the efficiency of charge transfer, a significant factor that limits the use of CDs in photovoltaic cells. In this study, we synthesized highly luminescent, water-insoluble, slightly amphiphilic CDs by using a macrocyclic compound, calix[4]pyrrole, for the first time in the literature. Calix[4]pyrrole-derived CDs (CP-DOTs) were highly luminescent with a QY of over 60% and size of around 4-10 nm with graphitic structure. The high quantum yield of CP-DOTs indicated that they had less amount of surface defects. Furthermore, CP-DOTs were used as an additive in the active layer of organic solar cells (OSC). The photovoltaic parameters of OSCs improved upon addition of CDs. Our results indicated that calix[4]pyrrole is an excellent carbon precursor to synthesize highly luminescent and water-insoluble carbon dots, and CDs derived from calix[4]pyrrole are excellent candidates to improve optoelectronic devices.
Citation - WoS: 13
Citation - Scopus: 13
Electrical Behaviors of the Co- and Ni-Based Poms Interlayered Schottky Photodetector Devices
(Wiley, 2022) Yıldırım, Murat; Kocyigit, Adem; Torlak, Yasemin; Yenel, Esma; Hussaini, Ali Akbar; Kuş, Mahmut
Polyoxometalates (POMs) are attractive materials for various applications such as energy storage, catalysis and medicine. Here, Co and Ni-based POMs are chemically synthesized and characterized by X-ray diffractometer (XRD) and Fourier transform infrared spectroscopies (FT-IR) for structural characterization. While the morphological behaviors are analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM), the optical properties are investigated by UV-Vis spectrometer. Electrochemical characterizations are carried out by cyclic voltammetry to determine oxidation levels of the metal centers in the POMs. The CoPOM and NiPOM are inserted in between the Al metal and p-Si semiconductor to obtain Al/CoPOM/p-Si and Al/NiPOM/p-Si Schottky-type photodetector devices. Current-voltage (I-V) and current-transient (I-t) measurements are employed to understand the electrical properties of the Al/CoPOM/p-Si and Al/NiPOM/p-Si devices under dark and various light power intensities. The devices exhibit phototransistor like I-V characteristics in forward biases due to having POMs active layers. Various device parameters are extracted from the I-V measurements and discussed in details. I-t measurements are performed to determine various detector parameters such as responsivity and specific detectivity values for under 2 V and zero biases. The Al/CoPOM/p-Si and Al/NiPOM/p-Si Schottky-type photodetector devices can be employed in optoelectronic applications.
Citation - WoS: 9
Citation - Scopus: 11
Enhanced Control Method for Voltage Regulation of Dstatcom Based Seig
(Elsevier, 2022) Özer, Ali Sait; Sevilmiş, Fehmi; Karaca, Hulusi; Arabacı, Hayri
Self-excited induction generator (SEIG)-based wind energy conversion systems (WECS) are very popular for feeding standalone loads in remote areas where there is no grid. SEIG needs adjustable reactive power to regulate terminal voltage and frequency. Usually, a combination of a distributed static compensator (DSTATCOM) and a fixed capacitor bank is used to meet this reactive power demand. DSTATCOM is the most suitable option for power quality compensation. The performance of DSTATCOM depends on its control algorithm that generates the proper switching signals for voltage source inverter (VSI). Many control algorithms have been proposed for DSTATCOM in the literature. Among them, the most frequently used algorithms are synchronous reference frame (SRF), instantaneous reactive power (IRP), and current synchronous detection (CSD) algorithms. An effective control algorithm must accurately estimate the amplitude of the terminal voltage without being affected by harmonics, DC-offset, and frequency variation. For this purpose, an enhanced phase locked loop (EPLL)-based CSD control algorithm is proposed to estimate the amplitudes of individual phase voltages, and to filter SEIG voltages in case of harmonics, DC offset, and frequency variation. The proposed algorithm has been tested under linear and nonlinear load conditions. The obtained results clearly demonstrate the effectiveness of the proposed EPLL-based CSD control algorithm. (C) 2022 The Author(s). Published by Elsevier Ltd.
Citation - WoS: 6
Citation - Scopus: 7
Fuzzy-Based Modeling and Speed Optimization of a Centrifugal Blood Pump Using a Modified and Constrained Bees Algorithm
(Elsevier Ireland Ltd, 2022) İncebay, Ömer; Önder, Ahmet; Arif, Şen, Muhammed; Yapıcı, Rafet; Kalyoncu, Mete
Background and objective: Side effects that may occur when using blood pumps for treatment of patients are the main limitations on pump rotational speed determination. Efforts are being made to reduce side effects in both design and usage procedures. In determining the pump speed for treatment, decreasing the pressure on the main artery and preserving the valve functions are taken into consideration. In addition to these, the parameters considered for design which include pump efficiency and mechanical effects on blood cells, should also be taken into consideration. In this study, the aim is to obtain the optimum pump speed for the maximum hydraulic efficiency and minimum wall shear stresses that occur inside the pump. Methods: Blood pump modeling based on fuzzy logic is created on the hydraulic performance data of a centrifugal blood pump, whose design, CFD analysis, manufacture and experimental testing have been performed previously. Using this fuzzy logic model, the optimum pump speeds were determined using the Bees Algorithm, an intuitive optimization algorithm, in the operating range 1-7 L/min fluid flow rate. In the optimization process, the aim is to achieve minimum shear stress with maximal efficiency. Intravascular pressure limits (90-160 mm-Hg) were set as pressure constraints. Results: The optimum operating point is obtained as a 3350 rpm pump speed and a 4.35 L/min flow rate. At this operating point, CFD simulation is performed, and maximum wall shear stress was found to be 1458 Pa and its efficiency as 34.2%. Conclusions: In addition to the parameters commonly used in the pump speed optimization of blood pumps, the use of wall shear stresses and pump efficiency can provide certain improvements. © 2022
Citation - WoS: 1
Citation - Scopus: 1
Investigation of Changes in Culturable Lactic Microflora During Freeze Storage in Cow and Goat Milk Kefirs by High-Throughput Sequencing
(Wiley, 2022) Biçer, Yusuf; Telli, A. Ezgi; Sönmez, Gonca; Türkal, Gamze; Telli, Nihat; Uçar, Gürkan
This study determined changes in the live lactic microflora of cow and goat milk kefirs, traditionally produced using kefir grain and freeze stored for 30 days, using high-throughput sequencing. In kefir grains, 71.29% Lactococcus, 16.27% Enterococcus, and 12.3% Serratia were found in the M17 agar, and 69.93% Lacticaseibacillus and 24.54% Lactobacillus were found in MRS agar. In the M17 agar of cow milk kefir, 78.26% Lactococcus was found on day 0, and this rate was 91.68%, 87.98%, and 88.14%, on the 7th, 14th, and 30th days, respectively. As for goat milk kefir, Lactococcus levels were 82.98%, 93.28%, 87.77%, and 84.92%, respectively. On the MRS agar in cow milk kefirs, Lacticaseibacillus levels were found as 56.98%, 61.21%, 87.54%, and 75.50%, on days 0, 7, 14, and 30 of storage, respectively, while the rates were 48.95%, 77.02%, 87.85%, and 83.38% for goat milk kefirs, respectively. As a result, although kefir beverages frozen at -25 degrees C contain sufficient levels of Lactobacillus and Lactococcus, it has been determined that the genus Serratia, which is one of the main spoilage factors in dairy products, is also increasing. Novelty impact statement In this study, the changes in the living lactic microflora during the frozen storage of traditional kefir beverages, whose production is increasing, were determined by high-throughput sequencing. It is thought that it is important to determine the effect of the freezing process on the viability of lactic acid bacteria, which are thought to have probiotic properties, for the long-term storage of these beverages. However, while lactic acid bacteria maintain their viability, it should be taken into account that microorganisms that are resistant to freeze conditions and cause spoilage can also develop.
Citation - WoS: 20
Citation - Scopus: 23
Investigation of Usability of Boron Doped Sheep Wool as Insulation Material and Comparison With Existing Insulation Materials
(Elsevier Sci Ltd, 2022) Altın, Mustafa; Yıldırım, Giray Şamil
The limited energy resources in the world require maximum attention in energy saving and energy use. It has always been important to conserve energy by making thermal insulation in buildings which are one of the places where energy is used the most, and subsequently reducing environmental pollution as a result. The importance of existing thermal insulation materials in maintaining heat is already known. However, the damage they cause to the environment in their production is great, therefore insomuch that the manufacture and use of some insulation materials are prohibited. As a result, it is known that studies have been carried out to produce alternative thermal insulation materials. In this study, as a thermal insulation material, the usability of sheep wool which is an environmentally friendly, economical, and natural fiber, has been researched. A new insulation board was produced by adding boron to sheep wool, and this new insulation board was compared with rock wool and expanded polystyrene (EPS), which are widely used today. To carry out the experimental studies, an experiment building with full size and 3 rooms had been built. First, the building was completely covered with rock wool and the effect of the facades on the temperature and moisture in the environment was observed. Afterwards, as one room was covered with EPS and the other room was covered by the boron doped sheep wool insulation material, the insulation materials were compared wtih one another. In the experimental studies that was carried out, while rock wool gave the best results in ambient and surface temperature tests, EPS provided the best insulation in the moisture test. In the sound test, while rock wool and EPS absorbed the sound at very close decibel levels, the boron-doped sheep wool insulation material provided a higher level of sound insulation. In the experimental studies that was carried out, it has been determined that the boron-doped sheep wool insulation material has serious competition with both rock wool and EPS even with the first production of 10 mm.
Citation - WoS: 19
Citation - Scopus: 19
Land Valuation With Best Worst Method in Land Consolidation Projects
(Elsevier Sci Ltd, 2022) Ertunç, Ela; Uyan, Mevlüt
Land Consolidation is the regulations made to increase agricultural productivity. In these projects, improperly shaped parcels are optimally rearranged in the land allocation process and reallocated to predetermined blocks. The amount of the land to be reallocated depends on the value of parcels. Because, after land consolidation in the project area, it is necessary to determine the value of existing parcels based on certain factors so that the landowner will be provided with the land of equal value to its previous land. In land consolidation projects, determining the value of the land, developing and recommending principles acceptable to the landowner, and the overall duration of the project are of critical importance for the quality and success of the project. In other words, the key to the positive evaluation of the whole project is to determine the value of the land transparently and without causing injustice among landowners. The methods used in land valuation in many countries fall behind the existing techniques and technologies. Therefore, a new approach based on scientific methods is needed for land valuation. To this end, a new model based on multi-criteria calculations, which is compatible with today's technologies and eliminates weaknesses in the existing land valuation methods, has been developed in this study. In the model, the most important factors affecting the land value in land consolidation projects were determined, and the value of parcels in the consolidation area was determined by weighting these factors using the Best Worst Method (BWM). The BWM is a new Multi-Criteria Decision Making (MCDM) method in the literature and has been used for the first time in this field. In the study, three different scenario models were created to investigate how the factor influencing land value are allocated during the land valuation. The generated land value maps were examined from different aspects, and the results were revealed. In conclusion, the proposed method performed an analytical, objective, and transparent land valuation since it objectively evaluates the factors used in land valuation by a scientific method.
Citation - WoS: 3
Citation - Scopus: 3
Lc-esi-ms/Ms-based Phytochemicals and Cytotoxic, Antioxidant, and Enzyme Inhibitory Activities of Scorzonera Mollis Subsp. Szowitzii: a New Reserve of Bioactive Compounds
(Wiley, 2022) Deveci, Ebru
Scorzonera L. species are important species used in folk medicine against as hypertension, arteriosclerosis, diabetes, kidney diseases, and rheumatism. In this study, phytochemical compounds, cytotoxic (against DLD-1 (colorectal cancer) and CCD-18Co (human colon fibroblast cell line)), antioxidant and enzyme inhibitory (against cholinesterases, tyrosinase, urease, alpha-amylase, and alpha-glucosidase) activities of various extracts of Scorzonera mollis subsp. szowitzii were investigated. LC-ESI-MS/MS analysis led to screen 56 phytochemical compounds with predominance of chlorogenic acid in acetone (0.118 +/- 0.010 mu g/mg) and methanol (34.105 +/- 0.012 mu g/mg) extracts and gallic acid (0.153 +/- 0.008 mu g/mg) in water extract. The methanol extract showed superior cytotoxic activity on DLD-1 with IC50 value of 19.46 +/- 0.36 mu g/ml. The highest antioxidant activity was recorded in methanol extract in beta-carotene linoleic, DPPH center dot, ABTS(center dot+), CUPRAC, and phosphomolybdenum assays with IC50 values of 16.23 +/- 0.98, 68.55 +/- 0.24, 40.32 +/- 0.27, 241.66 +/- 0.01, and 95.65 +/- 0.78 mu g/ml, respectively. All extracts exhibited varying degrees of enzyme inhibitory activity, while hexane extract (89.18 +/- 0.84%) showed a degree of urease inhibitory activity to exceed the standard (78.93 +/- 0.18%). Novelty impact statement Since the side effects of synthetic origin drugs have reached levels that cannot be ignored, the interest in scientific studies on plants and their bioactive properties has deepened. In this study, it was planned to investigate the phytochemical profile and bioactive properties of S. mollis subsp. szowitzii, a member of Scorzonera genus used as food and drugs in traditional medicine. In addition to being the first to point out the potential of S. mollis subsp. szowitzii as a natural food additive, this study proved its medicinal importance by uncovering bioactive compounds and properties.
Citation - WoS: 6
Citation - Scopus: 12
Refractory-Metal Chalcogenides for Energy
(Wiley-V C H Verlag Gmbh, 2022) Özel, Faruk; Arkan, Emre; Coşkun, Halime; Deveci, İlyas; Yıldırım, Murat; Yıldırım, Mehmet; Ersöz, Mustafa; Kuş, Mahmut
When it is asked, where can refractory metals be used?, the possible shortest answer is, where cannot they be used? The uses of refractory-metal-based compounds in research and industry are too many to be enumerated; nevertheless, some outstanding examples are briefly mentioned here. Essentially, chalcogenide forms of refractory metals are preferred in the fabrication of high-performance structures. Therefore, expanding the current studies that usually focus on tungsten- and molybdenum-based structures to other materials may open new opportunities. Moreover, research on ternary and quaternary structures can also be a keystone in creating high-performance products. The rationale of the present review is to give a brief overview of the recent history of refractory-metal-based chalcogenides (RMCs). Initially, the framework is confined to the general design and approaches for the synthesis of refractory metal chalcogenides. The assay is continued by extending with characteristic features of materials from crystalline properties to thermoelectric attributes and examining device fabrication processes. Taken together, the device fabrication part where RMCs are mainly used is extensively focused upon. Finally, outlook and future perspectives are given on the design and construction of RMCs to enable future inspiration and innovation.
Citation - WoS: 28
Citation - Scopus: 28
Use of the Migrating Birds Optimization (mbo) Algorithm in Solving Land Distribution Problem
(ELSEVIER SCI LTD, 2020) Tongur, Vahit; Ertunç, Ela; Uyan, Mevlüt
Land distribution is an important process in Land Consolidation (LC) projects where agricultural parcels are reallocated to predetermined blocks. Land distribution is a process that takes a long time, requires high operating costs, and conflicts between landowners occur frequently. The parcels are tried to be placed in the best and most appropriate place of the existing blocks by considering many parameters in the distribution stage. Therefore, the placement of new parcels in blocks is seen as an optimization process. In LC projects, this process is carried out manually by technical staff using a software and thus it becomes a process that takes weeks and even months. Various methods have been developed to solve this important stage of the LC projects. It is required to find the best solution, since this issue is an optimization problem. This study aims to develop a new land distribution method. For this purpose, land distribution were carried out by use Migrating Birds Optimization (MBO) Algorithm. Used land distribution method in practice and the results of the new developed method were compared and thus the usability of the method that developed by us was tested. With this study, it has developed a new and successful distribution method according to the preference of land owners.

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