05. Fakülteler

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Citation - WoS: 9
Citation - Scopus: 11
Adrenal Tumor Segmentation Method for Mr Images
(ELSEVIER IRELAND LTD, 2018) Barstuğan, Mücahid; Ceylan, Rahime; Asoğlu, Semih; Cebeci, Hakan; Koplay, Mustafa
Background and objective: Adrenal tumors, which occur on adrenal glands, are incidentally determined. The liver, spleen, spinal cord, and kidney surround the adrenal glands. Therefore, tumors on the adrenal glands can be adherent to other organs. This is a problem in adrenal tumor segmentation. In addition, low contrast, non-standardized shape and size, homogeneity, and heterogeneity of the tumors are considered as problems in segmentation. Methods: This study proposes a computer-aided diagnosis (CAD) system to segment adrenal tumors by eliminating the above problems. The proposed hybrid method incorporates many image processing methods, which include active contour, adaptive thresholding, contrast limited adaptive histogram equalization (CLAHE), image erosion, and region growing. Results: The performance of the proposed method was assessed on 113 Magnetic Resonance (MR) images using seven metrics: sensitivity, specificity, accuracy, precision, Dice Coefficient, Jaccard Rate, and structural similarity index (SSIM). The proposed method eliminates some of the discussed problems with success rates of 74.84%, 99.99%, 99.84%, 93.49%, 82.09%, 71.24%, 99.48% for the metrics, respectively. Conclusions: This study presents a new method for adrenal tumor segmentation, and avoids some of the problems preventing accurate segmentation, especially for cyst-based tumors. (C) 2018 Elsevier B.V. All rights reserved.
Citation - WoS: 50
Citation - Scopus: 55
Advanced Oxidation of Landfill Leachate: Removal of Micropollutants and Identification of By-Products
(ELSEVIER, 2021) Ateş, Havva; Argun, Mehmet Emin
Landfill leachate contains several macropollutants and micropollutants that cannot be removed efficiently by conventional treatment processes. Therefore, an advanced oxidation process is a promising step in post or pre-treatment of leachate. In this study, the effects of Fenton and ozone oxidation on the removal of 16 emerging micropollutants including polycyclic aromatic hydrocarbons (PAHs), phthalates, alkylphenols and pesticides were investigated. The Fenton and ozone oxidation of the leachate were performed with four (reaction time: 20-90 min, Fe(II) dose: 0.51-2.55 g/L, H2O2 dose: 5.1-25.5 g/L and pH: 3-5) and two (ozonation time: 10-130 min and pH: 4-10) independent variables, respectively. Among these operating conditions, reaction time played more significant role (p-value < 0.05) in eliminating di-(2-Ethylhexyl) phthalate, 4-nonylphenol and 4-tert-octylphenol for both processes. The results showed that Fenton and ozone oxidation processes had a high degradation potential for micropollutants except for the PAHs including four and more rings. Removal efficiencies of micropollutants by ozone and Fenton oxidation were determined in the range of 5-100%. Although the removal efficiencies of chemical oxygen demand (COD) and some micropollutants such as phthalates were found much higher in the Fenton process than ozonation, the degradation products occurred during the Fenton oxidation were a higher molecular weight. Moreover, the oxidation intermediates for the both processes were found as mainly benzaldehyde, pentanoic acid and hydro cinnamic acid as well as derivatives of naphthalenone and naphthalenediol. Also, acid ester with higher molecular weight, naphthalene-based and phenolic compounds were detected in the Fenton oxidation.
Citation - WoS: 8
Citation - Scopus: 12
The Aerodynamic Effects of Blade Pitch Angle on Small Horizontal Axis Wind Turbines
(Emerald Group Publishing Ltd, 2022) Kaya, Mehmet Numan; Uzol, Oguz; Ingham, Derek; Köse, Faruk; Büyükzeren, Rıza
Purpose The purpose of this paper is to thoroughly investigate the aerodynamic effects of blade pitch angle on small scaled horizontal axis wind turbines (HAWTs) using computational fluid dynamics (CFD) method to find out the sophisticated effects on the flow phenomena and power performance. Design/methodology/approach A small HAWT is used as a reference to validate the model and examine the aerodynamic effects. The blade pitch angle was varied between +2 and -6 degrees, angles which are critical for the reference wind turbine in terms of performance, and the CFD simulations were performed at different tip speed ratio values, lambda = 2, 3, 4, 5, 6, 7, 9 and 10.5 to cover the effects in various conditions. Results are examined in two different aspects, namely, general performance and the flow physics. Findings The power performance varies significantly according to the tip speed ratio; the power coefficient increases up to a certain pitch angle at the design tip speed ratio (lambda = 6); however, between lambda = 2 and 4, the more the blade is pitched downwards, the larger is the power coefficient, the smaller is the thrust coefficient. Similarly, for tip speed ratios higher than lambda = 8, the positive effect of the low pitch angles on the power coefficient at lambda = 6 reverses. The flow separation location moves close to the leading edge at low tip speed ratios when the blade is pitched upwards and the also tip vortices become more intense. In conclusion, the pitch control can significantly contribute to the performance of small HAWTs depending on different conditions. Originality/value In the literature, only very little attention has been paid to the aerodynamic effects of pitch angle on HAWTs, and no such study is available about the effects on small HAWTs. The change of blade pitch angle was maintained at only one degree each time to capture even the smallest aerodynamic effects, and the results are presented in terms of the power performance and flow physics.
Citation - WoS: 29
Citation - Scopus: 54
Alexnet Architecture Variations With Transfer Learning for Classification of Wound Images
(Elsevier B.V., 2023) Eldem, H.; Ülker, E.; Işıklı, O.Y.
In medical world, wound care and follow-up is one of the issues that are gaining importance to work on day by day. Accurate and early recognition of wounds can reduce treatment costs. In the field of computer vision, deep learning architectures have received great attention recently. The achievements of existing pre-trained architectures for describing (classifying) data belonging to many image sets in the real world are primarily addressed. However, to increase the success of these architectures in a certain area, some improvements and enhancements can be made on the architecture. In this paper, the classification of pressure and diabetic wound images was performed with high accuracy. The six different new AlexNet architecture variations (3Conv_Softmax, 3Conv_SVM, 4Conv_Softmax, 4Conv_SVM, 6Conv_Softmax, 6Conv_SVM) were created with a different number of implementations of Convolution, Pooling, and Rectified Linear Activation (ReLU) layers. Classification performances of the proposed models are investigated by using Softmax classifier and SVM classifier separately. A new original Wound Image Database are created for performance measures. According to the experimental results obtained for the Database, the model with 6 Convolution layers (6Conv_SVM) was the most successful method among the proposed methods with 98.85% accuracy, 98.86% sensitivity, and 99.42% specificity. The 6Conv_SVM model was also tested on diabetic and pressure wound images in the public medetec dataset, and 95.33% accuracy, 95.33% sensitivity, and 97.66% specificity values were obtained. The proposed method provides high performance compared to the pre-trained AlexNet architecture and other state-of-the-art models in the literature. The results showed that the proposed 6Conv_SVM architecture can be used by the relevant departments in the medical world with good performance in medical tasks such as examining and classifying wound images and following up the wound process. © 2023 Karabuk University
Citation - WoS: 14
Citation - Scopus: 14
All-Dry Synthesis of Poly(2-Ethylhexyl Acrylate) Nanocoatings Using Initiated Chemical Vapor Deposition Method
(ELSEVIER SCIENCE SA, 2019) Şakalak, Hüseyin; Karaman, Mustafa
In this study, Poly(2-ethylhexyl acrylate) (PEHA) thin films were deposited on different substrates by initiated chemical vapor deposition (iCVD) technique. Being a long alkyl chain acrylate with a suitably low glass transition temperature, PEHA is an important member of acrylates family, which is used extensively in adhesives, paints, and coating applications. In iCVD, use of the tert-butyl peroxide as an initiator allowed a deposition rate of 155 nm/min at a filament temperature of 280 degrees C. Precursor flow ratios, filament and substrate temperatures were found to be important parameters that effect the deposition rates. The negative relation between substrate temperature and deposition rates implied an adsorption limited kinetics. FTIR and XPS analyses of the deposited films confirmed that the chemical functionality of the EHA monomer preserved well after iCVD. It was also revealed that the as-deposited films are smooth, uniform and optically transparent. PEHA film deposited by iCVD on glass improved the optical transmittance of glass, by acting as an anti-reflection coating due to its suitable refractive index of 1.45.
Citation - WoS: 17
Citation - Scopus: 19
Analysis of Electrospinning and Additive Effect on ? Phase Content of Electrospun Pvdf Nanofiber Mats for Piezoelectric Energy Harvester Nanogenerators
(Institute of Physics, 2022) Oflaz, Kamil; Özaytekin, İlkay
Harvesting energy with piezoelectric nanoparticles enables the development of self-powered devices. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF) has been widely used in a variety of fields due to its superior piezoelectric properties. PVDF’s piezoelectric performance is affected by the presence of polar phase in the crystalline structure. The electrospinning process was used in this study to achieve high ? phase ratios in the PVDF crystalline structure using various additives (graphene, boron nitride, and quartz (SiO2)). The Taguchi experimental design method was used to determine the most significant parameters affecting ? phase content from seven factors, as well as the optimal levels of the significant factors. The Fourier transform infrared, x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray and differential scanning calorimetry analyses were used to characterize the composite PVDF nanofiber mats produced under optimal conditions, and the output voltage was measured using an oscilloscope. The composite PVDF nanofiber mat with the highest ? phase concentration demonstrated a maximum output voltage of 8.68 V under optimal conditions, indicating that it outperformed than pure PVDF under equal electrospinning conditions. © 2022 IOP Publishing Ltd.
Citation - WoS: 37
Citation - Scopus: 46
Analysis of the Cp Structure of the Yukawa Coupling Between the Higgs Boson and Tau Leptons in Proton-Proton Collisions at Root S=13 Tev
(Springer, 2022) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Dragicevic, M.; Güler, Yalçın; The CMS Collaboration
The first measurement of the CP structure of the Yukawa coupling between the Higgs boson and tau leptons is presented. The measurement is based on data collected in proton-proton collisions at root s = 13 TeV by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb(-1). The analysis uses the angular correlation between the decay planes of tau leptons produced in Higgs boson decays. The effective mixing angle between CP-even and CP-odd tau Yukawa couplings is found to be -1 +/- 19 degrees, compared to an expected value of 0 +/- 21 degrees at the 68.3% confidence level. The data disfavour the pure CP-odd scenario at 3.0 standard deviations. The results are compatible with predictions for the standard model Higgs boson.
Citation - WoS: 18
Citation - Scopus: 19
Antibacterial Activity of Linezolid Against Gram-Negative Bacteria: Utilization of Epsilon-Poly Capped Silica Xerogel as an Activating Carrier
(MDPI, 2020) Kaya Güzel, Gülcihan; Medaglia, Serena; Candela-Noguera, Vicente; Tormo-Mas, Maria Angeles; Marcos, Maria Dolores; Aznar, Elena; Martinez-Manez, Ramon
In recent times, many approaches have been developed against drug resistant Gram-negative bacteria. However, low-cost high effective materials which could broaden the spectrum of antibiotics are still needed. In this study, enhancement of linezolid spectrum, normally active against Gram-positive bacteria, was aimed for Gram-negative bacteria growth inhibition. For this purpose, a silica xerogel prepared from a low-cost precursor is used as a drug carrier owing to the advantages of its mesoporous structure, suitable pore and particle size and ultralow density. The silica xerogel is loaded with linezolid and capped with epsilon-poly-l-lysine. The developed nano-formulation shows a marked antibacterial activity against to Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. In comparison to free linezolid and epsilon-poly-l-lysine, the material demonstrates a synergistic effect on killing for the three tested bacteria. The results show that silica xerogels can be used as a potential drug carrier and activity enhancer. This strategy could provide the improvement of antibacterial activity spectrum of antibacterial agents like linezolid and could represent a powerful alternative to overcome antibiotic resistance in a near future.
Citation - WoS: 42
Citation - Scopus: 46
Apricot Kernel Shell Waste Treated With Phosphoric Acid Used as a Green, Metal-Free Catalyst for Hydrogen Generation From Hydrolysis of Sodium Borohydride
(PERGAMON-ELSEVIER SCIENCE LTD, 2020) Fangaj, Enis; Ceyhan, Ayhan Abdullah
In this study, grinded apricot kernel shell (GAKS) biobased waste was used for the first time as a cost-effective, efficient, green and metal-free catalyst for hydrogen generation from the hydrolysis reaction of sodium borohydride (NaBH4). For the hydrogen production by NaBH4 hydrolysis reaction, GAKS was treated with various acids (HCl, HNO3, CH3COOH, H3PO4), salt (ZnCl2) and base (KOH). As a result, the phosphoric acid (H3PO4) demonstrated better catalytic activity than other chemical agents. The hydrolysis of NaBH4 with the GAKS-catalyst (GAKS(cat)) was studied depending on different parameters such as acid concentration, furnace burning temperature and time, catalyst amount, NaBH4 concentration and hydrolysis reaction temperature. The obtained GAKS(cat) was characterized by ICP-MS, elemental analysis, TGA, XRD, FT-IR, Boehm, TEM and SEM analyses and was evaluated for its catalytic activity in the hydrogen production from the hydrolysis reaction of NaBH4. According to the results, the optimal H3PO4 percentage was found as 15%. The maximum hydrogen generation rate from the hydrolysis of NaBH4 with the GAKS(cat) was calculated as 20,199 mL min(-1) g(cat)(-1) As a result, it can be said that GAKS treated with 15% H3PO4 as a catalyst for hydrogen production is an effective alternative due to its high hydrogen production rate. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Citation - WoS: 72
Citation - Scopus: 78
Article Info Keywords: Cfrp Reinforced Concrete T-Beams Strengthening Analytical Analysis Anchorage Building Codes Damage Analysis
(Elsevier Science Inc, 2022) Yazman, Şakir; Aksoylu, Ceyhun; Gemi, Lokman; Arslan, Musa Hakan; Hamad, Ahmed Abed; Özkılıç, Yasin Onuralp
Strengthening of shear deficient T-beams is not as easy as rectangular beams due to the presence of slabs. In this study, externally bonded reinforcement (EBR) such type of reinforced concrete shear deficient T-beams with and without anchorage in different CFRP configurations was experimentally and analytically investigated. Pursuant to this goal, nine half-scale T-beams were produced and tested with monotonic loading under four points. Seven of these T-beams are strengthened with partial CFRP strip and one is strengthened with full CFRP wrapped in the shear span. The failures of strengthened beams are initiated with the debonding failure of FRP sheets followed by brittle shear failure. In order to prevent this failure, two specimens with partial CFRP strip are fixed to the beam by using anchors at different angles of 45 and 90. The experimental results indicated that the contribution of EBR to the shear capacity is significant and depends on different variables such as anchorage angle, strengthening type. Moreover, the strengthening method that gives the most effective results in strengthening T-beams are full wrapping CFRP and partial CFRP with a 45-degree anchorage type. The anchorage application increased the shear capacity by 42.6%-53.8% compared to the reference specimens. In addition, the anchors with angle of 45 increased stiffness by 37%. In terms of ductility, the best result was given by the type of strengthening where the slabs were broken and the beam was completely wrapped. This method contributed 42%-80% more to ductility than other methods. The obtained experimental results were also compared with the empirical correlations given by ACI 440.2R-17, TBEC-2019 and FIB-2010 and recommendations are given. Especially in fully wrapped beams, the estimation of ACI was determined to be 96%. The estimations of the other codes are far from meeting the experimental results; therefore, essential improvements should be applied to the codes, especially with regard to CFRP deformation and approaches for anchored connections.
Citation - WoS: 13
Citation - Scopus: 14
Assessing the Performance of Bds-3 for Multi-Gnss Static and Kinematic Ppp-Ar
(Elsevier Ltd, 2022) Öğütçu, S.; Alcay, S.; Özdemir, Behlül Numan; Li, P.; Zhang, Y.; Konukseven, C.; Atiz, O.F.
As of 2021, a total of four different GNSS constellations – namely, GPS, GLONASS, Galileo, and BDS-3 – can be used with Full Operational Capability (FOC). In this work, the contribution of BDS-3 FOC to GPS + GLONASS + Galileo (GRE) PPP-AR is investigated, considering the three different cut-off angles (7°, 30°, and 45°) and different lengths of static observation sessions (24-, 12-, 6-, 3-, 1-, 0.5-, 0.25-hour). The data of 31 IGS-MGEX stations is processed with GRE PPP-AR and GREC3 (GPS + GLONASS (using float mode) + Galileo + BDS-3) PPP-AR modes. The results showed that BDS-3 degraded the horizontal (except for 24-h sessions) and vertical accuracy of static GRE PPP-AR solutions regardless of the elevation cutoff angle and observation time. The kinematic results showed that BDS-3 significantly contributed to the accuracy of GRE kinematic PPP-AR for 30° and 45° cutoff angles. The convergence time analysis showed that BDS-3 only contributes to GRE kinematic PPP-AR for the vertical component. © 2022 COSPAR
Citation - WoS: 14
Citation - Scopus: 15
Assessing the Structural Behavior of Reinforced Concrete Beams Produced With Macro Synthetic Fiber Reinforced Self-Compacting Concrete
(Elsevier Science Inc, 2022) Ünal, Alptuğ; Uğur, Ahmet Emin
This study was carried out to investigate the effect of polypropylene-based structural macro synthetic fiber (PPF) reinforcement on the behavior of reinforced concrete beams produced with self-compacting concrete (SCC). For this purpose, it was aimed to spread the PPFs homogeneously in the concrete by making use of the fluid form of SCC. The variation of non-fibrous-low-medium-high PPF ratios and stirrup ratios in specimens produced with SCC are the variables of the study. In this study, the shear span/effective depth ratio (a/d) was taken as the limit value of 2.5 in terms of shear and bending, and the behavior of reinforced concrete beams at this critical value was investigated. Within the scope of the study, 16 large-scale specimens were tested under monotonic loads in a 4-point bending setup. Load-displacement, stiffness and energy consumption graphs of the tested specimens were drawn, ductility values were determined, crack distributions were examined and failure modes were determined. The graphs and the determined values were interpreted in detail. In addition, numerical models of the tested specimens were created and analyzed using a finite element program. Experimental study results were compatible with numerical analysis results and similar results were obtained. According to the results obtained, it was observed that the specimens produced with SCC and using PPF reinforcements at appropriate ratios (5 kg/ m3 and 10 kg/m3) exhibited bending failure even if stirrups were not used.
Citation - WoS: 26
Citation - Scopus: 25
An Assessment of Deterioration in Cultural Heritage: the Unique Case of Eflatunpinar Hittite Water Monument in Konya, Turkey
(SPRINGER HEIDELBERG, 2020) Bozdağ, Ali; İnce, İsmail; Bozdağ, Ayla; Hatır, M. Ergün; Tosunlar, M. Bahadır; Korkanç, Mustafa
Stone monuments are important symbols of cultural heritage of countries. However, many environmental factors negatively affect these monuments. The increasing damage on the stone monuments and the danger of irreversible loss of cultural heritage have resulted in growing efforts for the preservation of the monuments. Eflatunpinar Hittite Water Monument in Beysehir, Konya, Turkey, is a unique Hittite cultural monument that has survived for nearly 3200 years even though it has been exposed to many environmental effects. In this study, non-destructive testing (NDT) was used to detect the degradation on the building stones of the Eflatunpinar Hittite Water Monument and change-deterioration maps were prepared subsequently. It was also investigated whether the chemistry of the Eflatunpinar spring water may cause deterioration. Additionally, the petrographic, chemical, and physico-mechanical properties of the rocks taken from the ancient stone quarry were determined in order to compare with the properties of the monument's building stones. Based on the physico-chemical characteristics of the Eflatunpinar spring water and XRD results of crusts in building stone surface of the monument, it was identified that water can be effective on the formation of calcite and gypsum crusts especially in the lower parts of the monument. However, applied NDT methods and change-deterioration maps indicated that the deterioration as well as neglect and abandonment in the monument are mostly associated with the capillary effect of the flowing water through the structure and the deterioration effect is more apparent in contact points between the building stone and the flowing water. Additionally, in the building stones above the capillary front, the conservation condition is significantly better.
Citation - WoS: 9
Citation - Scopus: 8
Atmospheric and Anthropogenic Deterioration of the Ivriz Rock Monument: Eregli-Konya, Central Anatolia, Turkey
(SPRINGER HEIDELBERG, 2021) Korkanç, Mustafa; İnce, İsmail; Hatır, Mehmet Ergün; Tosunlar, Mehmet Bahadır
The aim of this study is to determine the extent of deterioration of the limestone on which the Ivriz rock monument is engraved. This monument is near Aydinkent (Ivriz) village and located 12 km from the Eregli district of Konya. The height of the Ivriz Hittite monument is 4.20 m and its width is 2.40 m. It dates back to the second-half of the eighth century BC. The rocks on which the reliefs are engraved are limestone; the lower parts are brecciated with open cracks, and the upper parts show fewer cracks with smaller gaps. To enable the identification of the characteristics of the rocks on which the figures are located, non-destructive methods were used. Surface humidity, P wave velocity, thermal imaging, and Schmidt hardness measurement were applied to the wall surface of the monument, and mapping studies were conducted. Surface humidity varied between 26 and 58% with the highest values measured in the sections where the cracks are densest. The P wave velocity measured at the rock monument varied between 1.6 and 5.8 km/s, with the lowest values found in the sections where cracks were denser. Schmidt rebound values varied between 18 and 42, with higher values obtained in those sections with fewer effects of deterioration. According to the detailed observations and data obtained from non-destructive techniques (NDT) and laboratory data, the most significant deterioration has resulted from atmospheric conditions and damage by humans. The most common effects of degradation in this area are erosion by water, granular disintegration, cracks, microkarst, black crust, biodegradation (lichen, algae, and higher plants), and vandalism.
Citation - WoS: 70
Citation - Scopus: 75
Behavior of Cfrp-Strengthened Rc Beams With Circular Web Openings in Shear Zones: Numerical Study
(Elsevier Science Inc, 2022) Özkılıç, Yasin Onuralp; Aksoylu, Ceyhun; Yazman, Şakir; Gemi, Lokman; Arslan, Musa Hakan
In practice, especially the basement floor beams are drilled and damaged by the users. In some cases, this damage to the beams can be significant for the load-bearing element and the whole structure. In this study, the behavior of reinforced concrete beams with circular openings and the failure types resulting from strengthening these beams with CFRP are parametrically investigated. The diameter of the opening/beam height ratio (D/H), con-crete compressive strength, stirrup spacing, the position of the opening to the beam support, the type of CFRP application, CFRP ply orientation, and the number of CFRP layers were selected as parameters. Numerical models were verified using 9 specimens having different circular openings with/without CFRP strengthening and the analyses of 95 numerical models with the selected parameters were carried out utilizing the finite element program, ABAQUS. The ultimate load capacity, ductility, stiffness, energy dissipation capacity and failure modes of the beams were determined. As a result of the study, it was observed that there was no significant loss in ductility for the beams with D/H < 0.3 and the number of CFRP layer and type of application did not have a significant effect on D/H < 0.44. However, for the beams with D/H > 0.64, the CFRP application that completely surrounds openings should be preferred instead of partial CFRP strengthening. In addition, the concrete strength is an effective parameter for the beams with D/H < 0.44. The effect of the stirrup spacings in the beam on the ductile behavior was also limited with the increase in the hole diameter. The number of CFRP layers should theoretically be 4 for an effective strengthening in beams with D/H > 0.44. Finally, U wrapping is recommended instead of using full wrapping. It has been seen that the location and diameter of the hole are very important parameters in the failure type of the beam.
Citation - WoS: 37
Citation - Scopus: 47
Behaviour of Waste Polypropylene Pyrolysis Char-Based Epoxy Composite Materials
(SPRINGER HEIDELBERG, 2020) Soğancıoğlu, Merve; Yel, Esra; Ahmetli, Gülnare
In this study, polypropylene (PP) plastic wastes were pyrolysed. Solid pyrolysis product (char) was used as filler material for the preparation of epoxy composite. 300, 400, 500, 600 and 700 degrees C were selected as final pyrolysis temperatures. Solid pyrolysis product (char) was analysed by elemental, FTIR, SEM, BET and TGA analysis. The epoxy composite samples were prepared with char obtained from pyrolysis. Mechanical properties of composites were analysed by hardness, tensile strength, elongation at break, electrical conductivity tests to explain the effects of pyrolysis temperature and char doses over composite properties. Thermogravimetric properties of composites were determined by TGA analyses. The water absorption behaviour of composite samples was determined by water adsorption test. Epoxy composite produced from PP char obtained under 300 degrees C showed the most ideal behaviour.
Citation - WoS: 42
Citation - Scopus: 49
Bi-Objective Coordinated Production and Transportation Scheduling Problem With Sustainability: Formulation and Solution Approaches
(Taylor & Francis Ltd, 2023) Yağmur, Ece; Kesen, Saadettin Erhan
This paper studies a new variant of integrated production scheduling and vehicle routing problem where production of customer orders are performed under job-shop environment and order deliveries are made by a heterogeneous fleet of vehicles, each of which is allowed to take multiple trips. Two conflicting objectives are considered, namely minimisation of the total amount of CO2 emitted by the vehicles and minimisation of maximum tardiness resulting from late deliveries. To this end, we present a bi-objective mixed-integer programming formulation. Augmented epsilon-Constraint (Augmecon) method is implemented to find Pareto optimal solutions. Due to problem complexity, Augmecon cannot provide solutions even with small-sized problems. Thus, we adopt Pareto Local Search (PLS) and non-dominated sorting genetic algorithm-II (NSGA-II) for practical sized instances. For small-sized instances involving 5, 6, and 7 customers, experimental results indicate that CPU time of Augmecon are 11, 84, and 524 sec, respectively with an average number of Pareto efficient solution of 3.5. In terms of hypervolume index, Augmecon shows the best performance, followed by NSGA-II with 11.32% and PLS with 20.75% degradation for small-sized instances. For medium and large-sized instances, PLS shows worse performance than NSGA-II by 16.87% and 40.48%.
Citation - WoS: 30
Citation - Scopus: 36
Binary Aquila Optimizer for 0-1 Knapsack Problems
(Pergamon-Elsevier Science Ltd, 2023) Baş, Emine
The optimization process entails determining the best values for various system characteristics in order to finish the system design at the lowest possible cost. In general, real-world applications and issues in artificial intelligence and machine learning are discrete, unconstrained, or discrete. Optimization approaches have a high success rate in tackling such situations. As a result, several sophisticated heuristic algorithms based on swarm intelligence have been presented in recent years. Various academics in the literature have worked on such algorithms and have effectively addressed many difficulties. Aquila Optimizer (AO) is one such algorithm. Aquila Optimizer (AO) is a recently suggested heuristic algorithm. It is a novel population-based optimization strategy. It was made by mimicking the natural behavior of the Aquila. It was created by imitating the behavior of the Aquila in nature in the process of catching its prey. The AO algorithm is an algorithm developed to solve continuous optimization problems in their original form. In this study, the AO structure has been updated again to solve binary optimization problems. Problems encountered in the real world do not always have continuous values. It exists in problems with discrete values. Therefore, algorithms that solve continuous problems need to be restructured to solve discrete optimization problems as well. Binary optimization problems constitute a subgroup of discrete optimization problems. In this study, a new algorithm is proposed for binary optimization problems (BAO). The most successful BAO-T algorithm was created by testing the success of BAO in eight different transfer functions. Transfer functions play an active role in converting the continuous search space to the binary search space. BAO has also been developed by adding candidate solution step crossover and mutation methods (BAO-CM). The success of the proposed BAO-T and BAO-CM algorithms has been tested on the knapsack problem, which is widely selected in binary optimization problems in the literature. Knapsack problem examples are divided into three different benchmark groups in this study. A total of sixty-three low, medium, and large scale knapsack problems were determined as test datasets. The performances of BAO-T and BAO-CM algorithms were examined in detail and the results were clearly shown with graphics. In addition, the results of BAO-T and BAO-CM algorithms have been compared with the new heuristic algorithms proposed in the literature in recent years, and their success has been proven. According to the results, BAO-CM performed better than BAO-T and can be suggested as an alternative algorithm for solving binary optimization problems.
Citation - WoS: 44
Citation - Scopus: 47
Binary Artificial Algae Algorithm for Feature Selection
(Elsevier, 2022) Türkoğlu, Bahaeddin; Uymaz, Sait Ali; Kaya, Ersin
In this study, binary versions of the Artificial Algae Algorithm (AAA) are presented and employed to determine the ideal attribute subset for classification processes. AAA is a recently proposed algorithm inspired by microalgae's living behavior, which has not been consistently implemented to determine ideal attribute subset (feature selection) processes yet. AAA can effectively look into the feature space for ideal attributes combination minimizing a designed objective function. The proposed binary versions of AAA are employed to determine the ideal attribute combination that maximizes classification success while minimizing the count of attributes. The original AAA is utilized in these versions while its continuous spaces are restricted in a threshold using an appropriate threshold function after flattening them. In order to demonstrate the performance of the presented binary artificial algae algorithm model, an experimental study was conducted with the latest seven highperformance optimization algorithms. Several evaluation metrics are used to accurately evaluate and analyze the performance of these algorithms over twenty-five datasets with different difficulty levels from the UCI Machine Learning Repository. The experimental results and statistical tests verify the performance of the presented algorithms in increasing the classification accuracy compared to other state-of-the-art binary algorithms, which confirms the capability of the AAA algorithm in exploring the attribute space and deciding the most valuable features for classification problems. (C) 2022 Elsevier B.V. All rights reserved.
Citation - WoS: 31
Citation - Scopus: 32
A Binary Artificial Bee Colony Algorithm and Its Performance Assessment
(PERGAMON-ELSEVIER SCIENCE LTD, 2021) Kıran, Mustafa Servet
Artificial bee colony algorithm, ABC for short, is a swarm-based optimization algorithm proposed for solving continuous optimization problems. Due to its simple but effective structure, some binary versions of the algorithm have been developed. In this study, we focus on modification of its xor-based binary version, called as binABC. The solution update rule of basic ABC is replaced with a xor logic gate in binABC algorithm, and binABC works on discretely-structured solution space. The rest of components in binABC are the same as with the basic ABC algorithm. In order to improve local search capability and convergence characteristics of binABC, a stigmergic behavior-based update rule for onlooker bees of binABC and extended version of xor-based update rule are proposed in the present study. The developed version of binABC is applied to solve a modern benchmark problem set (CEC2015). To validate the performance of proposed algorithm, a series of comparisons are conducted on this problem set. The proposed algorithm is first compared with the basic ABC and binABC on CEC2015 set. After its performance validation, six binary versions of ABC algorithm are considered for comparison of the algorithms, and a comprehensive comparison among the state-of-art variants of swarm intelligence or evolutionary computation algorithms is conducted on this set of functions. Finally, an uncapacitated facility location problem set, a pure binary optimization problem, is considered for the comparison of the proposed algorithm and binary variants of ABC algorithm. The experimental results and comparisons show that the proposed algorithm is successful and effective in solving binary optimization problems as its basic version in solving continuous optimization problems.

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