Mühendislik Fakültesi

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2021 5th International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT)
(2021 5th International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT), 2021-11-19) Al-Dulaimi, Ahmed; harman, güneş
3B Yazıcı Teknolojilerindeki Kullanılan Yöntemler ve Gelişmeler Üzerine Bir Derleme
(Düzce Üniversitesi, 2021-07-01) Karagöz, İdris; Danış Bekdemir, Ayşe; Tuna, Özlem
Additive manufacturing (AM) or 3D printer technologies, as today's promising technique, has been drawn attention to the production of innovative products/parts that can be used in various fields. It can produce materials with desired mechanical and structural properties with 3D technologies. As compared to traditional production methods, the promising technology provides flexibility in product design, and contributes to increase material, energy, and cost efficiency in manufacturing system. Herein, 3B printer technologies are divided into seven different groups according to the American Society for Testing and Materials (ASTM) classification. AM methods are explained by considering working principles, and the type of material, as well as studies conducted with 3B printers using these methods were examined. This study shows that in 3D printer technologies, polymers, metals and alloys, ceramics and composite materials can be utilized as raw materials and post-printing secondary processes promote to produce parts with excellent mechanical properties. On the other hand, the technologies have been expected to open new horizons for easily creating prototypes and production of components using plastics, metals, metal alloys and ceramic materials used in a wide range of industrial sectors, including automotive, defence, aerospace, and rail transport. Nowadays, the number of raw materials for 3D technologies are limited and, recent studies should be directed to investigate new materials.
A Numerical Study About the Effects of Design and Test Parameters on the Crushing Behavior of a Truncated Cone
(TUBITAK ULAKBIM, 2021-04-30)
A numerical study was performed on the crushing behavior of an aluminum truncated cone structure for different design parameters and test speeds. Numerical models were prepared in the Ls-Prepost v4.7.1 software, and simulations were run in the Ls-Dyna solver. The Mat_18 power law plasticity and Mat_20 rigid material models were used for mimicking the behaviors of the aluminum tube and rigid plate, respectively. The effects of three different parameters as the ratio of the bottom and top diameters, contact angle of the rigid plate and test speed were investigated. Force-displacement curves for each case were obtained and evaluated to understand the crushing behaviors of the geometries with the aforementioned parameters. The geometry which had the 2.5 bottom/top diameter ratio performed the highest energy absorption among all geometries.
A Relative Assessment of the Life-Cycle Costs of Rigid and Flexible Pavement Coatings in Turkey
(European Journal of Science and Technology, 2020-01-01) Abut, Yavuz
Choosing pavement type is a challenging and much-debated issue among public authorities. It includes engineering factors such as materials, labor, and long-term performance within the scope of the initial (construction) and life-cycle costs. In recent years, given the significant public expenditure on road construction and rehabilitation processes, the trends in vehicle ownership caused by an increasing need to travel, and the decrease in local resources, concerns have been raised about the efficiency of pavement coating types. To ensure that taxpayers understand the full value of road expenditure, it is important to identify a coating type selection process that seeks to include the most appropriate construction, maintenance, and repair strategies possible. In this study, an LCCA was performed for a 2.2 km–long Roller Compacted Concrete (RCC) test track constructed in Kocaeli city. If asphalt is chosen instead of RCC as the coating preference, the economic factors that may arise at a national scale (in this case, Turkey) are discussed. During the 20-year service period, maintenance, repair, and rehabilitation planning were carried out on the basis of a 30-year analysis period. In terms of initial construction costs, an RCC road is 39.4 more economical than an asphalt road and provides maintenance and repair economies of 62 during the service period. In terms of life-cycle costs, an RCC road is a 46 more economical paving alternative than an asphalt road. Although the first serious maintenance activity was carried out in the 10th and 20th years of the asphalt road, it was significant that it only took place during the 20th year for the RCC road, and the asphalt maintenance material was more expensive than that for the RCC road.
A Scale Development for Innovation Capability Measurement
(Journal of Advanced Management Science, 2017) Calik, Eyup; Calisir, Fethi; Cetinguc, Basak
Adsorption efficiency of sulfonated poly (ether ether ketone)(sPEEK) as a novel low-cost polymeric adsorbent for cationic organic dyes removal from aqueous solution
(JOURNAL OF MOLECULAR LIQUIDS, 2021) Hızal, Jülide; Yılmazoğlu, Mesut; Kanmaz, Nergiz
The aim of this study is to investigate the methylene blue (MB) and basic violet 16 (BV16) as cationic organic dyes adsorption on sulfonated poly(ether ether ketone) (sPEEK) in aqueous solution. sPEEK was synthesized, then characterized by FTIR, SEM, TGA, BET/N2 surface area analysis, particle size and zeta potential measurements. Batch experiments were performed to analyze the effects of key parameters such as contact time, initial concentration and pH on MB and BV16 adsorptions. Additionally, temperature effect was investigated for MB adsorption. Kinetic data revealed that cationic dyes adsorptions were well-fitted by pseudo-second order kinetic model. The required times to achieve equilibrium were determined as 40 and 20 min for MB and BV16, respectively. The adsorptions showed Langmuirian character, and the maximum adsorption capacities were found to be 98.04 mg/g (0.29 mmol/g) for MB, and 181.8 mg/g (0.50 mmol/g) for BV16. The thermodynamic data showed that the MB adsorption was an endothermic process occuring spontaneously at room temperature. Desorption and recycling experiments showed that the adsorption efficiency decreased from 99.6% to 99.2% after the fifth cycle, pointing out sPEEK reusability for MB removal. Low desorption percentage of BV16 loaded sPEEK shows that sPEEK may be used for immobilizing of BV16.
An Investigation into the Service Life of Seal Coated Roads in Turkey
(International Marmara Sciences Congress (Spring), 2021-05-22) Abut, Yavuz
Various effects such as service loads, uncertainties in material characteristics, changing environmental conditions (precipitation and temperature), and geographical differences are largely responsible for the pavement performance. Use of mechanistic-empirical methods is increasing in the recent years, and many approaches based on experimental works leave their place to the mechanistic approaches which take into account several performance criteria. In many countries, project administrations or organizations have started to formulate their specifications based on these methods. These adaptation studies are also continuing in Turkey. Mechanistic design is generally used in flexible and rigid pavements, but for low-volume roads, its use limited due to the economic reasons. Seal coating is designed using empirical methods with ten years as “estimated project period” in Turkey, and since it is based on empirical approach, maintenance and repair activities are very common and serious financial costs arise in the service life. In this study, thickness of seal coats is handled with a mechanistic approach and a design algorithm has been proposed depending on the compressive strain on the top of the subgrade. Due to the acceptable axle load repetition into the service life, an analysis with KENPAVE has been performed, which is the amount of permanent deformation that is likely to occur at the end of ten years. In an economic evaluation, it was determined that the mechanistic method offered a relatively more expensive solution and the difference depended on the resilient modulus of the subgrade soils.
Analysis approach for composite steel plate shear walls (CSPSW) reinforced with CFRP
(The 2021 World Congress on Advances in Structural Engineering and Mechanics (ASEM21), 2021-08-23) Avcı-Karataş, Çigdem; Ghamari, Ali
Steel plate shear walls (SPSWs) have been conducted as a capable system for resisting lateral forces induced on structures by wind and earthquakes. Adding concrete covering is a way of improving the behavior of SSWs. Studies by researchers indicated that, by using the concrete layer, stress is better distributed in the steel plate and the tension field lines are developed in a wider region. The only difference between the traditional system and the composited steel plate shear wall with the concrete system is that, in the latter, there is a gap between the concrete wall and the boundary columns and beams. In the traditional system, there is no gap, and the concrete directly rests against the boundary columns and beams. This seemingly simple modification resulted in a significant improvement in performance as well as an increase in ductility and damage mitigation. Some researchers showed that the carbon fiber-reinforced polymer (CFRP) would enhance the structural behavior of SPSWs. Nevertheless, no simple approach has been presented for composite SPSWs (CSPSWs) reinforced with CFRP. In the present research, the nonlinear behavior of CSPSW is determined and a method of analysis is proposed. The comparison between the findings of this approach and those of the finite element method (FEM) indicates that the proposed method is more accurate and its relevant computations take less time compared to the FEM. This model provides a good understanding of the interactions that might occur among different components of the system. It is also able to predict the overall pushover response, which is used in the nonlinear analysis of CSPSW systems.
Anode Performance of Sustainable, Hemp-derived, Flexible, Binder-free, Carbon Fabrics in Lithium-Ion Batteries
(International Journal of Environment and Geoinformatics, 2021) Toprakçı, Ozan; Karahan Toprakçı, Hatice Aylin
Antep Fıstığı Kabuk Atıklarından Esnek Elektronik Üretimi
(Bartın Üniversitesi 4.Ar-Ge Proje Pazarı, 2021-10-25) Demirel, Aybüke Sultan; Çetin, Mukaddes Şevval; Karahan Toprakçı, Hatice Aylin; Toprakçı, Ozan
Artificial Bee Colony Algorithm Based Hyper-Parameter Optimization for Convolutional Neural Networks
(Yalova University, 2021-05-21) Özdemir, Koray; Özen, Yunus; Tuncer, Adem
In recent years, Deep Learning has become a field that researchers are particularly interested in. The Convolutional Neural Network (CNN) is a type of multi-layered artificial neural network mostly used in the analysis, recognition, and classification of images and videos. The performance of CNN models is usually based on custom model architectures, thus several hyper-parameter values in a CNN are manually selected mostly. However, different combinations of hyper-parameters and models need to be used to achieve better performance results. Determination of optimum values of hyper parameters is also an optimization problem. The metaheuristic optimization techniques are able to solve such problems. In this paper, we propose to use the Artificial Bee Colony (ABC) algorithm which is a meta-heuristic approach to automatically determine the optimum architecture of a CNN by means of hyper-parameters. The most effective hyperparameters in the performance of CNN models have been optimized, which are the number of layers, the number and size of filters, activation function, batch size, learning rate, optimizer, and dropout rate. We have evaluated our optimized architecture using the well-known Fashion-MNIST dataset. The results demonstrate that the proposed model using ABC improves the performance of a CNN model.
BALIKESİR İLİ ERDEK İLÇESİ İÇİN BAĞIMSIZ HİBRİT ENERJİ SİSTEMİNİN FİZİBİLİTE ÇALIŞMASI VE EKONOMİK ANALİZİ
(Konya Journal of Engineering Sciences, 2021-12-04) GÜVEN, Mete,MertcanAykut Fatih
Bu çalışmada Balıkesir’in Erdek ilçesinin 2020 yılı aylık elektrik tüketim değerlerini karşılamak amacı ile oluşturulabilecek en optimum şebeke bağlantısız hibrit enerji sistemi tasarımı HOMER programında gerçekleştirilmiştir. Bu çalışmanın amacı ise fosil yakıtların tükenmesi ile artan maliyetleri ve çevreye verdikleri zararlardan ötürü seçilen bölgenin daha ucuz ve temiz olan yenilenebilir enerji kaynaklarından elektrik enerjisi eldesini sağlamaktır. Bölgenin enerji ihtiyacını karşılayacak en optimum sistem arayışında farklı senaryolar oluşturulup analizleri gerçekleştirilmiştir. Bu senaryoları oluşturan sistem bileşenleri ise güneş paneli, rüzgar türbini, batarya, dönüştürücü, yakıt pili, Elektrolizör, hidrojen tankı, dizel ve biyogaz jeneratörü olmaktadır. Oluşturulan farklı senaryolar arasındaki fark kullanılan jeneratör tiplerinden kaynaklanmaktadır. Oluşturulan senaryoların optimizasyon sonuçları arasında yapılan analizler sonucunda şebeke bağlantısız Güneş paneli /Rüzgar türbini/Dizel Jeneratör/Batarya sisteminin 165 milyon $ net bugünkü maliyet ve 0,109 $ birim enerji maliyeti ile en uygun sistem olduğu ortaya koyulmaktadır. Şebeke bağlantısız Güneş paneli/Rüzgar türbini/Dizel Jeneratör/Batarya sisteminin her ne kadar diğer sistemlere göre daha yüksek emisyon değerleri olsa da bu değerler kabul edilebilir düzeyde olmaktadır. Hem istenilen maliyet değerlerini hem de istenilen çevreci yaklaşım açısından en optimum sistem tasarımını temsil etmektedir
Bitümlü Sıcak Karışımların Kırılma Davranışının İncelenmesi
(7. Ulusal Asfalt Sempozyumu, 2017-11-30) Abut, Yavuz; Karasahin, Mustafa
Düşük sıcaklıklarda asfalt kaplamalarda termal çatlakların oluşumu sıklıkla ortaya çıkar ve bu çatlaklar ilk etapta ciddi bir hasara neden olmamasına rağmen, çatlağın zamanla yayılmasıyla yapısal hasarın boyutu artmaya başlar. Bu çalışmada, bitümlü sıcak karışımlarda düşük sıcaklıklarda çatlak oluşumu ve yayılmasının araştırılması amacıyla yarım daire şeklinde numuneler üretilmiş ve AASHTO TP105-13’e uygun eğilme prosedürü uygulanarak kırılma özelliklerinin belirlenmesi amaçlanmıştır. Aşınma (Tip1) karışımları üzerinde yapılan deneysel çalışmalar sonucunda; Kırılma Enerjisi = 2706 J/m2, Birim Direnç = 1.035 kN/mm ve Tokluk = 0.83 MPa × m0.5 düzeyinde tespit edilmiştir. Ayrıca yarım daire numune üretiminde titreşimli tokmak kullanımının diğer kompaksiyon yöntemlerine alternatif olabileceği saptanmıştır.
Change Effect of LCL Filter Parameter Values and Series Damping Resistor Value in Single Phase Grid Connected Inverter
(EMO Bilimsel Dergi, 2020) Karafil, Akif
In this study, LCL filter parameters of a single phase grid connected inverter were calculated. The change of total harmonic distortion (THD) of the grid current and power loss values when the calculated LCL filter parameters and series damping resistor were increased and decreased by 50% was analyzed and the most appropriate values were determined. Analysis studies were carried out using the PSIM simulation program. The study had a power of 1 kW and proportional resonant (PR) control was used in current control and T/4 delay PLL structure was used in PLL algorithm. According to the results of the analysis, it was determined that increasing the inductor values decreased the THD value of the current and the amount of power loss. In addition, decreasing the damping resistor value also decreased THD and power loss values. In LCL filter design, it was seen that it would be appropriate to increase the inductor values and to decrease the series damping resistor value.
Comparison of the various irregular pulse density modulation (PDM) control pattern lengths for resonant converter with photovoltaic (PV) integration
(Journal of the Faculty of Engineering and Architecture of Gazi University, 2021) Karafil, Akif
In this study, the maximum power obtained from photovoltaic (PV) panels was transferred the load using the proposed 8, 16 and 32 irregular pulse density modulation (PDM) pattern controlled series resonant converter. In the study, changes in the system occurred due the variations in PDM pattern lengths were analyzed. The output power was controlled by providing maximum power point tracker (MPPT) at different solar irradiation values with varying PDM pattern lengths. Zero current switching (ZCS) conditions were achieved by using phase locked loop (PLL) technique at each power point of the PV system. Therefore, soft switching was realized by continuously tracking the appropriate switching conditions at the resonant frequency. Incremental conductance (IC) algorithm was used to track the maximum power in PV panels and tracking efficiency of a novel PDM controlled IC MPPT algorithm was obtained above 99%.
Computational Simulation of Two Phase Flow in a Refrigerant Distributor
(Sinop Üniversitesi Fen Bilimleri Dergisi, 2017-12-29) Direk, Mehmet; Sökücü, Mehmet Harun; Çakmak, Mehmet Ekrem; Bayrak, Ergin
In order to keep pressure drops at lower levels and to maintain uniform refrigerant distribution, flow behavior of refrigerants in the distributors at the entrance of evaporators should be elucidated. The aim of this study is to obtain a validated computational simulation of two-phase flow distribution in conventional and new designs refrigerant distributor. The results of the computational simulations of the distributor are validated against the experimental results. The influence of the flow distribution on the evaporator performance has been considered. Distribution of mass flow rate in the distributor channels and pressure drop are numerically calculated and then compared to the data obtained from the experimental facility. As a result, the difference between numerical and experimental study of the pressure drop is less than 2%.
Corrosion behaviour of hydroxyapatite coatings on AZ31 and AZ91 magnesium alloys by plasma spray
(JOURNAL OF CERAMIC PROCESSING RESEARCH, 2021-02-02) BUGDAYCI, MEHMET; BASLAYICI, SERKAN; MAHMUT ERCAN, AÇMA
In the scope of this study, AZ31 and AZ91 magnesium alloys are to be coated with hydroxyapatite by plasma spray to be used as biodegradable implant material and their in-vitro corrosion behaviors are to be examined. There are a number of researches on the production of biodegradable cortical screws and plates used in orthopedic surgery in last decade. The advantage of biodegradable implants is that they do not need to be surgically removed. Moreover, the elastic modulus and the mechanical properties of magnesium are relatively close to those of the human bone, and this prevents the phenomenon of the human bone named “stress shielding. During this study, the hydroxyapatite coating processes, characterizations and corrosion behaviors of AZ31 and AZ91 will be examined. The aim of this work is to determine the optimal coating conditions for magnesium alloys for biodegradable implants. As a result of the plasma spray coating, the corrosion rate has decreased from about 1.2 mm/year to 0.4 mm/year.
Corrosion Protection Process for Istanbul Golden Horn Metro (Halic) Crossing Bridge
(International Congress on Engineering Sciences and Multidisciplinary Approaches, 2021-02-22) Avcı-Karataş, Çigdem
This paper focuses on the corrosion control process for the Golden Horn (Halic) Metro Crossing Bridge which is constructed over the Golden Horn in the city of Istanbul-Turkey consisting of a swing bridge and cable-stayed bridge both to be founded on a steel tubular pile foundation as the most important infrastructure steel bridge in Turkey in two ways; i) the paint coating method used in 12.770 tons steel members for the superstructure and ii) an active cathodic protection (CP) method with external current source used in 7.928 tons steel members for substructures which impose an external voltage on the steel surface in a manner that forces the steel to become cathodic. One of the unique aspects of this present study is that the external current CP given details in this paper for a steel bridge is used in Turkey for the first time in this area.
Crew Scheduling Optimization with Artificial Bee Colony Algorithm
(8th International Advanced Technologies Symposium (IATS’17), 2017-10-19) Sardoğan, Melike; Tuncer, Adem
Crew scheduling is one of the most important optimization problems for airline companies. It is the scheduling of weekly or monthly work schedule under certain constraints, such as working hours and weekly permits. There are many studies using analytical and heuristic approaches in the literature in order to solve this problem. In studies using heuristic approaches, genetic algorithms are used frequently. In this study, an artificial bee colony algorithm, which is a heuristic method, is used instead of the approaches applied to the current problem. Weekly work schedules are optimized according to daily working hours and days off for crew scheduling under a number of different personnel. From the simulation results, it is clearly seen that the artificial bee colony algorithm produces successful results within reasonable time.
DC Fast Charging Station Modeling and Control for Electric Vehicles
(The Black Sea Journal of Sciences, 2021-12-15) Güven, Akbaşak, Salih Burak Aykut Fatih
Due to environmental problems in the world, the need for electric vehicles is increasing. While the transition to Electric Vehicles continues, the acceleration of this process plays an important role in reducing environmental problems. In order to accelerate this transition, charging units should become widespread and charging time should be reduced. Higher power charging units are needed to reduce charging time. This is where DC (Direct Current) fast charging units come into play. In this study, the charging process of electric vehicles, the behavior of the DC fast charging unit on the battery and the control systems are modeled in MATLAB/Simulink environment. The designed model represents the electric power system that will charge electric vehicles and is suitable for more than one electric vehicle to be included in the DC fast charging system. The simulation is integrated according to the DC level-2 charging conditions. The system model consists of 1 AC(AC Current)/DC converter, 1 DC busbar, 2 DC/DC converters to charge electric vehicles and multiple EV batteries. The system model includes the design methods (AC/DC-DC/DC) design and different control strategies) and descriptions of these components. The simulation result shows that the filter and control system integrations in the electrical power system exhibit more stable behavior by correcting the negative effects on the power system. Thus, it offers positive outputs about the integration of DC fast charging units, which will increase rapidly in the future, into the power system and how this process should be established.

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