Yazarlar
- Gul, Muhammet(16)
- Kahraman, Gökhan(13)
- Onat, Onur(13)
- Yucesan, Melih(12)
- Etli, Serkan(11)
- Mete, Suleyman(11)
- Akkurt, Nevzat(10)
- Karataş, Mehmet(10)
- Utku, Anıl(10)
- Yön, Burak(10)
- Akmaz, Düzgün(8)
- Cemalgil, Selim(8)
- Demir, Yakup(8)
- Ergen, Burhan(8)
- Çil, Zeynel Abidin(8)
- Akgül, Melek(7)
- Doğan, Gürkan(7)
- Gülmez, Nihan(7)
- Xu, Qian(7)
- Yildirim, Ozal(7)
- Yilmaz, Mehmet(7)
- Özceylan, Eren(7)
- Celik, Erkan(6)
- Göçmen, Elifcan(6)
- Orhan, Ahmet(6)
- Ertarğın, Merve(5)
- Serin, Faruk(5)
- Yilmazer, Merve(5)
- Zheng, Qiang(5)
- Akpolat, Mustafa(4)
- Atangana, A(4)
- Baskonus, HM(4)
- Bulut, H(4)
- Ding, Yulong(4)
- Dogan, Akar(4)
- Eristi, Huseyin(4)
- Hammouch, Z(4)
- Işık, Erdem(4)
- Karakose, Mehmet(4)
- Kaya, Sema Kayapinar(4)
Yayınlar
- MakaleYalnız künye2020Scopus SJRQ3Increasing the Power Generation by Raising the Capacity of the Thrust Bearing Oil Cooling System in Hydroelectric Power Plants
Kahraman, Gökhan
Cooling capacity decreases due to faults appearing over time in the thrust bearing oil cooling systems of hydroelectric power plants and cooling process cannot proceed sufficiently. For this reason, while the turbine-generator unit generates energy, the thrust bearing heats up. This temperature problem prevents the unit from operating at full capacity and therefore decreases in energy production. Producing deficient energy in hydroelectric power plants, which is a renewable energy source, causes long-term economic losses for countries. In this study, the thrust bearing cooling system of a vertical Francis turbine, which produces 150 MW of energy per hour, is investigated. The reduction in the cooling capacity over time in turbine thrust bearing cooling system is solved by using exchanger system with additional plate and the power produced by the turbine-generator unit is increased 15 MW/h. This improvement has greatly contributed to the national economy. The method of increasing the cooling capacity applied to the hydroelectric power plant thrust bearings can be applied to all hydraulic turbines. This method will increase the energy production amount of the unit by approximately 10% and it costs approximately 80% cheaper than completely replacing the existing cooling system.
AtıfScopus5WoS2OpenAlex5
İncele - MakaleYalnız künye2020Scopus SJRQ3A fuzzy-based occupational health and safety risk assessment framework and a case study in an international port authority
Gul, Muhammet
Ports are complex systems that play a crucial role in the transportation of maritime-related products and services. Since ports face various safety issues in design, installation, operation and maintenance processes, there are many aspects open for improvement in Occupational Health and Safety risk assessment and it is required to deal with risks, reduce them to an acceptable level and control. To struggle with emerging risks and manage this process better, a risk assessment framework is proposed for ports in this study. A case study is performed in a Turkish international port authority using the proposed framework. Fuzzy Analytic Hierarchy Process (FAHP), which is a commonly used fuzzy multi-criteria decision-making method, was used in weighting two risk factors: likelihood and severity. The orders of priority of hazards were then determined by a fuzzy-based VIKOR method based on the output of FAHP. The proposed framework overcomes some drawbacks, including a lack of assignment on the weight to two risk assessment factors and lack of the high dependence of the prioritisation on the experts’ opinions. To validate the results, a sensitivity analysis was conducted. In conclusion, the study contributes to the applicability of the proposed framework to assess the risks in ports and provides a distinct risk prioritisation.
AtıfScopus43WoS39OpenAlex49İncele - MakaleYalnız künye2020Scopus SJRQ3Investigation of the Effect of Operating Conditions Change on Water Hammer in Hydroelectric Power Plants
Kahraman, Gökhan
Renewable energy sources do not harm the environment, and they contribute greatly to national economies. Hydraulic energy is the leading renewable energy source. Hydraulic energy is used more widely than other renewable energy sources around the world. This situation of hydraulic energy makes it important to solve the faults in hydraulic turbine-generator units. In this study, water hammer impacts have been investigated. This issue is important and can be dangerous in hydroelectric power plants. As a result of the research, the optimum sudden shutdown time of the adjusting wings in the snail is determined by considering the different operating conditions of a hydroelectric power plant. When the turbine-generator units are operated according to the specified instantaneous shutdown time, they will be protected against the impact of the water hammer pressure and the turbine shaft overspeed. Thus, they will be operated with less risk.
AtıfScopus9WoS8OpenAlex8İncele - MakaleYalnız künye2020Scopus SJRQ1In-situ synthesis of 3D printable mono- and Bi-metallic (Cu/Ag) nanoparticles embedded polymeric structures with enhanced electromechanical properties
Aktitiz, İsmail; Varol, Remzi; Akkurt, Nevzat; Saraç, Mehmet Fahri
The interest of additive manufacturing with 3D printing increases day by day, which provides improved mechanical, electrical, magnetic and thermal properties of 3D parts. The production of 3D parts with the stereolithography (SLA) method, which allows it to be produced with high precision, resolution and complex geometries, distinguishes itself from other alternative additive manufacturing methods (FDM. SLS. LOM. LMD etc.). However, studies on the preparation of functional 3D polymer nanocomposites with the SLA method are quite limited. This study aims to produce silver (Ag) and/or copper (Cu) based 3D polymer nanocomposites for enhancing its mechanical strength, thermal stability and electrical conductivity. Mono and bimetallic (Cu/Ag) nanoparticles have been in-situ synthesized by selective irradiation of laser beam method using a commercial SLA device. In this method, metal (Cu/Ag) acrylate containing photocurable resin is not only cured but also leads to thermal decomposition of metal ions into nanoparticles to form functional 3D structures. The mechanical, electrical and thermal properties of polymer nanocomposites are characterized in detail. As a result of the analysis, the nanoparticles, with an average diameter of 25–55 nm, are well dispersed in the polymer matrix without agglomeration. The temperature at which 5% weight loss of Ag and Cu based polymer structures is measured as 179.3 °C while the glass transition temperature is found to be 223.81 °C. Most importantly, the resistance values are significantly decreased from 456.62 GΩ (Gigaohm) to 1.50 GΩ by increasing the amount of Ag addition at 3D polymeric structures. Therefore, this study allows the production of polymer nanocomposites not only in complex structures but also in desired properties especially for electrically conductive materials, capacitors and electronic applications.
AtıfScopus32WoS24OpenAlex33İncele - MakaleAçık Erişim2019Design and Analysis of a Water Pumping System with Photovoltaic Source and Switched Reluctance Motor
Omaç, Z.
Solar energy is a clean energy and it is increasingly being used all over the world. In this study, a centrifugal water pump system driven by switched reluctance motor (SRM) has been designed with powered by a photovoltaic (PV) energy source. The voltage of the PV source has been increased by using a boost converter. The mathematical model of the system has been composed in the Matlab/Simulink and simulation results have been obtained. Proportional–integral–derivative (PID) controller has been used to control output voltage of the boost converter at 50 kHz switching frequency. The boost converter is controlled by an eight-bit PIC16F877A microcontroller. The electrical energy obtained by PV panels has been stored in batteries. Battery charge testers have been used to control the battery charge level. The speed and current control of SRM has been done by using DS1103 Ace kit. The values of phases currents have been measured by using hall sensors and transferred to the digital signal processor (DSP) by analog to digital converter inputs. The accuracy of simulation results has been proved by experimental results.
AtıfOpenAlex3TR Dizin1
İncele - MakaleAçık Erişim2019Hidroelektirik santrallerde generatör stator sargı arızaları ve çözüm yöntemleri
Taşgın, Yahya; Kahraman, Gökhan
Hidroelektrik santraller ile elektrik üretimi, dünyada toplam elektrik üretimine küçümsenmeyecek bir oranda katkıda bulunmaktadır. Hidroelektrik santralleri ile enerji üretimi için uygun coğrafi koşulların sağlanması gerekmektedir. Günümüz koşullarında kullanılabilir hidroelektrik kapasitenin büyük bir bölümü hali hazırda kullanılmaktadır. Türkiye hidrolik enerji bakımından dünyadaki birçok ülkeye göre avantajlı durumdadır. Özellikle Güney ve Doğu Anadolu bölgelerimizde hidroelektrik santraller sayesinde üretilen elektrik enerjisi küçümsenemez. Kurulması planlanan veya inşaatı süren birçok hidroelektrik santralleri, Türkiye'nin geleceğine damga vuracaktır. Hidroelektrik santralleri, diğer enerji üretim yöntemlerine göre doğaya en az düzeyde zarar verdikleri için temiz enerjikaynakları arasında değerlendirmek gerekir. Hidroelektrik santraller yenilenebilir bir enerji kaynağı olması ve enterkonnekte sistemin güvenliğinin sigortası olması açısından her zaman üretime hazır olmaları önemlidir. Hidroelektrik santrallerde arıza kaynaklı duruş sürelerini azaltmak için birçok ölçüm sistemleri, uzaktan izleme sistemleri geliştirilmiştir. Bu santrallerde en önemli ve giderilmesi uzun zaman alan arızalardan biride generatör stator sargı arızalarıdır. Bu çalışmada stator sargı arızalarının sebepleri, giderilme yöntemleri ve bu tip arızaları engellemek için yapılması gerekenler incelenmiştir. Bir hidroelektrik santralinde stator arızası örneği verilmiş arızanın oluşumu, tespiti, yapılan elektriksel testler,onarımı detaylı bir şekilde anlatılmıştır. Yapılan onarımın sonucunda sargı sıcaklıkları izlenmiş ve herhangi bir sorunun olmadığı görülmüştür. Hidroelektrik santrallerde işletme ve bakım şartlarında belirlenen önlemlerin alınması stator sargılarından kaynaklanan arızaları engelleyeceği gibi santralin elektrik arz güvenliğini en üst düzeyde tutacaktır. Ayrıca arızadan kaynaklanan işçilik vemalzeme maliyetlerini düşürecektir.
AtıfTR Dizin1İncele - MakaleYalnız künye2019Scopus SJRQ1Earthquake Damage to Nonstructural Elements of Reinforced Concrete Buildings during 2011 Van Seismic Sequence
Yön, Burak; Onat, Onur; Öncü, Mehmet Emin
Infill and partition walls as nonstructural elements are generally constructed with hollow brick masonry and briquette as single or multilayered vertical walls. The seismic responses of infill walls and reinforced concrete (RC) framed buildings have been investigated with field observations after earthquakes all over the world. This study focuses on the reasons infill and partition walls failed as a result of the October 23, 2011 (Mw=7.2), and November 9, 2011 (Mw=5.7), Van earthquakes in Turkey. In this paper, in-plane, out-of-plane, and combined failure mechanisms of single and multilayered infill walls enclosed within reinforced concrete structures were investigated, and construction rules were suggested. To limit the failure of nonstructural elements enclosed within an RC frame, design and construction requirements should be included in the seismic code by adopting suitable solutions for both in-plane and out-of-plane behavior. This paper will be a reference for future studies that investigate infill wall damage. (c) 2019 American Society of Civil Engineers.
AtıfWoS51OpenAlex62İncele - MakaleYalnız künye2019Scopus SJRQ1Fundamental vibration frequency prediction of historical masonry bridges
Onat, Onur
It is very common to find an empirical formulation in an earthquake design code to calculate fundamental vibration period of a structural system. Fundamental vibration period or frequency is a key parameter to provide adequate information pertinent to dynamic characteristics and performance assessment of a structure. This parameter enables to assess seismic demand of a structure. It is possible to find an empirical formulation related to reinforced concrete structures, masonry towers and slender masonry structures. Calculated natural vibration frequencies suggested by empirical formulation in the literatures has not suits in a high accuracy to the case of rest of the historical masonry bridges due to different construction techniques and wide variety of material properties. For the listed reasons, estimation of fundamental frequency gets harder. This paper aims to present an empirical formulation through Mean Square Error study to find ambient vibration frequency of historical masonry bridges by using a non-linear regression model. For this purpose, a series of data collected from literature especially focused on the finite element models of historical masonry bridges modelled in a full scale to get first global natural frequency, unit weight and elasticity modulus of used dominant material based on homogenization approach, length, height and width of the masonry bridge and main span length were considered to predict natural vibration frequency. An empirical formulation is proposed with 81% accuracy. Also, this study draw attention that this accuracy decreases to 35%, if the modulus of elasticity and unit weight are ignored.
AtıfWoS14OpenAlex6İncele - MakaleAçık Erişim2019Public transportation graph: A graph theoretical model of public transportation network for efficient trip planning
Serin, Faruk; Mete, Suleyman
The presentation and usage of traditional graphs is very important for effective and fast solution of routing in public transportation. However, the traditional graph approach is unable to consider the passenger requests such as total travel time, minimum number of transfer and total distance of travel without pre-processing and/or post-processing. Moreover, the vehicles are not represented on traditional graph. In this paper, after analyzing the different kind of graphs, we propose a novel graph named as public transportation graph. The proposed graph models the public transportation system and considers distance, waiting time, travel time, self-transportation and number of transfers simultaneously for efficient trip planning. In this way, passenger requests can be met without pre-processing and post-processing. In addition, the vehicles are also considered and demonstrated in the proposed graph.
AtıfWoS1OpenAlex4TR Dizin1İncele - MakaleYalnız künye2019Scopus SJRQ2A fuzzy-based model for risk assessment of routes in oil transportation
Gul, M.; Guneri, A.F.; Nasirli, S. Miralp
The transportation of oil is the final step that the oil is taken before it is distributed to consumer. Road transport is a type of oil transportation methods, and transfers between facilities of primary and secondary bases are carried out by tanker trucks. A particular advantage of tanker trucks is that they provide direct travel from the source to the destination. However, road transport involves possible hazards for population and environment. At this point, this study presents a fuzzy-based risk assessment model for the routes in an oil transportation company. Fuzzy analytic hierarchy process, which is a commonly used multi-criteria decision-making method, is applied in weighting nine criteria related to the road characteristics. Then, risk scores for eleven different routes which the tanker trucks of the company followed are determined by using a basic multi-criteria scoring method. Results of the case study emerge that the most important criterion is narrow road. The riskiest route for the company has been determined. In order to reduce risks to an acceptable level, a number of control measures are suggested such as to assign experienced drivers for this route, provide regular training for drivers, make regular vehicle maintenance and transport large quantities at one time as possible. To demonstrate validity, a comparison is also provided between the proposed approach and Pythagorean fuzzy analytic hierarchy process-based risk scoring model. In conclusion, this study contributes to the applicability of fuzzy analytic hierarchy process to assess riskiness for routes in oil transportation.
AtıfScopus36WoS28OpenAlex46İncele - MakaleAçık Erişim2019Scopus SJRQ1Identification of optimum working conditions in hydroelectric power plants for cavitation
Kahraman, Gökhan; Yücel, Halit Lütfi; Taşgin, Yahya
Turbine faults in hydroelectric power plants not only reduce the operation time of the plant, but also cause a serious loss of income. One of the most important turbine faults is the turbine wheel wear caused by the cavitation and accordingly the other machine equipment faults which cause excessive vibration. In this study, cavitation intensity that the turbines have been exposed in operating conditions has been investigated. As a result of the calculations, optimum working conditions of the units have been determined with graphs obtained in various operating conditions. The obtained data can be easily applied to all hydroelectric power plants exposed to cavitation, and safe operating conditions can be determined.
AtıfScopus11WoS10OpenAlex13İncele - MakaleYalnız künye2019Scopus SJRQ1A decision-support system based on Pythagorean fuzzy VIKOR for occupational risk assessment of a natural gas pipeline construction
Mete, Suleyman; Serin, Faruk; Oz, Nurdan Ece; Gul, Muhammet
Natural gas pipeline construction projects are major projects between countries that include onshore and offshore sections. Aim of these projects is to supply the natural gas from one place to another. Safety of workplace, environment and employers is also another important argument. In this respect, it is essential to conduct an occupational risk assessment (ORA) study to eliminate the risks that may arise around the pipeline. Application of multi-criteria decision analysis (MCDA) methods for the ORA has shown great increase recently. Also, developing a decision support system (DSS) which is easy to use and capable of extracting results enables decision makers to assess health and safety risks. Therefore, (i) A DSS based on Pythagorean fuzzy VIKOR (PFVIKOR) in ORA literature is developed for the first time; (ii) A case study is employed to risk assessment for trenchless crossings installation by auger boring process of the pipeline project; (iii) A sensitivity analysis is performed in the results of PFVIKOR-based DSS; and (iv) Two additional risk parameters called sensitivity to PPE non-utilization and undetectability are considered in ORA process apart from the classical risk assessment parameters of severity and probability. Developing such a DSS and applying it for risk assessment in a natural gas pipeline construction will contribute stakeholders in the energy industry.
AtıfScopus89WoS67OpenAlex83İncele - MakaleYalnız künye2019Scopus SJRQ1Supply-driven rebalancing of disassembly lines: A novel mathematical model approach
Mete, Suleyman; Çil, Zeynel Abidin; Celik, Erkan; Ozceylan, Eren
In recent years, the interest of disassembly line has increased owing to the economic reasons and increase of environmental awareness. The balancing of the disassembly line is one of the factors affecting directly the performance of the process. Companies with a line used effectively can gain many advantages in terms of economic aspect and it facilitates competition the companies with others. Moreover, uncertainties end-of-life products characteristics and quantity of supply/demand causes reassigned of task and altering cycle time. Rebalancing of disassembly line is required in this situation. In this study, a novel mixed integer programming model is proposed. Firstly, disassembly line balance is created, and then according to the given new supply, tasks are reselected and reassigned to the workstations. A real case study is presented. The generated test problems are also analyzed using proposed mathematical model. Through the analysis of rebalancing the existing disassembly line, it has been identified that an existing balance might have been changed to accommodate changes in the desired output rate in order to cope up with the variation of the cycle time.
AtıfScopus31WoS27OpenAlex31İncele - Derleme MakaleYalnız künye2019Scopus SJRQ1Designing the airport service with fuzzy QFD based on SERVQUAL integrated with a fuzzy multi-objective decision model
Kayapınar, Sema; Erginel, Nihal
Airport service quality is a crucial issue in the transportation industry. Although many studies focus on service quality and measurement of the airports, only a small number of studies that consider linguistic expression and fuzzy approach exist in the literature. This study aims to propose a new integrated approach to develop airport service quality. An integrated approach involving fuzzy Quality Function Deployment (QFD) based on SERVQUAL is used to measure airport service quality and to determine fuzzy weights of technical design requirements. Firstly, passengers’ needs are prioritised by using the SERVQUAL method and gap scores, then QFD matrix is constructed by defining fuzzy relationships between passengers’ needs and expectations, and technical design requirements under imprecise knowledge. Technical design requirements are weighted by using fuzzy QFD matrix as fuzzy numbers. Finally, a fuzzy multiple objective decision model is proposed to select the significant technical design requirements with two objectives: maximising the total fuzzy weights of technical design requirements and minimising the fuzzy technical difficulty level under a fuzzy budget constraint. A two-phase approach is used to solve the constructed fuzzy multi-objective decision model. The final results indicate four design requirements named as ‘the number of information board’, ‘capacity of wi-fi’, ‘emergency help button and automation’, and ‘the number of the signboard’, which maximise the total fuzzy weights of technical design requirements and minimise the sum of the fuzzy technical difficulty of each design requirements under the fuzzy budget constraint. This study is a real-world application which was implemented at the Anadolu University Airport in Turkey.
AtıfScopus40WoS37OpenAlex47İncele - MakaleYalnız künye2019Scopus SJRQ2Experimental damage evaluation of prototype infill wall based on forced vibration test
Onat, Onur
This paper aims to investigate vibration frequency decrease (vibration period elongation) of reinforced concrete (RC) structure with unreinforced infill wall and reinforced infill wall exposed to progressively increased artificial earthquake load on shaking table. For this purpose, two shaking table experiments were selected as a case study. Shaking table experiments were carried on 1:1 scaled prototype one bay one storey RC structure with infill walls. The purpose of this shaking table experiment sequence is to assess local behavior and progressive collapse mechanism. Frequency decrease and eigen-vector evolution are directly related to in-plane and out-of-plane bearing capacities of infill wall enclosure with reinforced concrete frame. Firstly, frequency decrease-damage relationship was evaluated on the base of experiment results. Then, frequency decrease and stiffness degradation were evaluated with applied Peak Ground Acceleration (PGA) by considering strength deterioration. Lastly, eigenvector evolution-local damage and eigenvector evolution-frequency decrease relationship was investigated. Five modes were considered while evaluating damage and frequency decrease of the tested specimens. The relationship between frequency decrease, stiffness degradation and damage level were presented while comparing with Unreinforced Brick Infill (URB) and Reinforced Infill wall with Bed Joint Reinforcement (BJR) on the base of natural vibration frequency.
AtıfScopus14WoS12OpenAlex9İncele - MakaleYalnız künye2019Scopus SJRQ2Design and development of travelling-wave-frequency-based transmission line fault locator using TMS320 DSP
Arkan, Müslüm; Akmaz, Düzgün; Mamiş, Mehmet S.; Tağluk, Mehmet Emin
The authors use a TMS320 digital signal processor (TMS320-DSP) to determine fault instants and estimate their location in real time in a laboratory environment. The fault instant is determined via examining the instantaneous differential changes in the line currents. After the fault is detected, the fault location is determined by processing the time-domain transient current waves. First, the travelling-wave frequency is determined by application of the fast Fourier transform to the positive-sequence-component line current after the fault, and subsequently, the fault location is estimated by utilising this frequency. The alternative transients programme (ATP)–electromagnetic transient programme is used to simulate the line currents and create short-circuit fault conditions. Furthermore, LabVIEW software and a National Instruments data acquisition board are used to transform the line currents obtained through the ATP programme into analogue signals. The TMS320-DSP determines the fault in real time and estimates the fault location using the completed software and analogue input signals. Their results indicate that the prototype device designed with the use of the TMS320-DSP is suitable for real-time fault detection.
AtıfScopus16WoS16OpenAlex16İncele - MakaleYalnız künye2019Scopus SJRQ1Research of thermal performance by metallographic investigation of stator winding solder region in hydroelectric power plants
Kahraman, Gökhan; Taşgın, Yahya
Hydroelectric power plants are the most widely used renewable energy sources all over the world. In these plants, many studies have been conducted in order to produce energy continuously and efficiently. Among these studies, predictive maintenance methods, efforts to increase power by improving cooling conditions, and improving efficiency by improving the turbine wheel. In this paper, soldering at the junctions of the stator windings in the central generators has been investigated. Traditional solder (Cu–Zn) materials and silver alloy solders (Ag-Cu-Zn) have been investigated in terms of thermal and metallographic. Silver alloy soldering has been found to have lower electrical conductivity than conventional soldering. The winding temperatures measured on the generating generator show that silver alloy soldering is more efficient. Reducing the stator winding temperature in hydroelectric power plants allows more energy production and also reduces costs by preventing winding failures.
AtıfScopus2WoS2OpenAlex2İncele - MakaleYalnız künye2019Scopus SJRQ2Assessing occupational risks in pipeline construction using FMEA-based AHP-MOORA integrated approach under Pythagorean fuzzy environment
Mete, Suleyman
The aim of natural gas pipeline projects is generally to make it possible to transfer the natural gas produced from one place to another. There are various safety risks for these broad construction systems. Therefore, to reduce the negative effects of emerged risks, a new risk assessment approach for occupational health and safety (OHS) is needed. In this paper, FMEA-based AHP-MOORA integrated approach under Pythagorean fuzzy sets is proposed for assessing occupational risks in a natural gas pipeline construction project. A case study for concrete coating process of natural gas pipeline project is employed to show the feasibility and effectiveness of the proposed integrated approach. A comparative study, correlation analysis, and sensitivity analysis are also presented to approve the novel risk assessment approach. In conclusion, the integrated approach gives more reasonable results for evaluating the occupational risks in project of pipeline construction using the advantage of Pythagorean fuzzy sets that reflects uncertainty in more suitable way.
AtıfScopus122WoS103OpenAlex124İncele - MakaleYalnız künye2019Scopus SJRQ2An efficient algorithm for U-type assembly line re-balancing problem with stochastic task times
Serin, Faruk; Mete, Süleyman; Çelik, Erkan
Purpose: Changing the product characteristics and demand quantity resulting from the variability of the modern market leads to re-assigned tasks and changing the cycle time on the production line. Therefore, companies need re-balancing of their assembly line instead of balancing. The purpose of this paper is to propose an efficient algorithm approach for U-type assembly line re-balancing problem using stochastic task times. Design/methodology/approach: In this paper, a genetic algorithm is proposed to solve approach for U-type assembly line re-balancing problem using stochastic task times. Findings: The performance of the genetic algorithm is tested on a wide variety of data sets from literature. The task times are assumed normal distribution. The objective is to minimize total re-balancing cost, which consists of workstation cost, operating cost and task transposition cost. The test results show that proposed genetic algorithm approach for U-type assembly line re-balancing problem performs well in terms of minimizing total re-balancing cost. Practical implications: Demand variation is considered for stochastic U-type re balancing problem. Demand change also affects cycle time of the line. Hence, the stochastic U-type re-balancing problem under four different cycle times are analyzed to present practical case. Originality/value: As per the authors’ knowledge, it is the first time that genetic algorithm is applied to stochastic U-type re balancing problem. The large size data set is generated to analyze performance of genetic algorithm. The results of proposed algorithm are compared with ant colony optimization algorithm.
AtıfScopus19WoS17OpenAlex20İncele - MakaleYalnız künye2019Scopus SJRQ1Elimination of a measurement problem: A robust prediction model for missing eigenvector value to assess earthquake induced out-of-plane failure of infill wall
Onat, Onur; Yön, Burak
One of the effective methods to assess local or global behavior of structural system is to perform shake table experiment. The biggest challenge of all experiments, either shake table or others, are missing data during the experiments due to removed instruments. This problem is arose especially during the out-of-plane tests. This problem is named as “Measurement” problem. This paper is focused on detection the measurement problem and solving this problem by using Adaptive-Network Based Neuro Inference System (ANFIS). Definition of the problem is briefly missing out-of-plane eigenvector value during the implementation of a shake table experiments on a full scale one bay one storey reinforced concrete structural system. For this aim, two shake table experiments were performed with reinforced concrete frame (RCF)and infill wall at the National Civil Engineering Laboratory (LNEC)Portugal. The out-of-plane failure of infill wall was assessed under combined bidirectional seismic load. Shake table experiments were conducted on two types of specimens. One of them is Unreinforced Brick Infill Wall (URBIF)composed of single layer 22 cm thick brick. The other is single layer 22 cm thick Infill Wall with Bed Joint Reinforcement solution (IwBJR). Both specimens were made of a single-layer brick infill wall enclosure with the RCF. Bed joint reinforcement term refers horizontal bed joint reinforcement as a strengthening technique. Shake table experiments were performed on each specimen at four stages. After third level of earthquake load, the accelerometers were removed on the wall to prevent damage to them. The removal of these instruments results in missing data. The missing eigenvector values were predicted with a robust Adaptive-Network Based Neuro Inference System (ANFIS)model to present failure mode of infill wall. The estimation quality was tested with R2, Mean Absolute Percentage Error (MAPE), Mean Square Error (MSE)and Root Mean Square Error (RMSE)among with available data. The results of the quality indicator of R2 are 0.999 for URBIF model and 0.997 for IwBJR model, respectively. Moreover, rest of the indicator results are less than %1. The proposed approach is reliable on the base of quality indicator. Moreover, this study can be used for seismic engineering to predict eigenvector values to see local behavior of infill wall and mode shape evolution to determine which mod prone for partial and total collapse of infill wall.
AtıfScopus12WoS11OpenAlex10İncele
