TR Dizin İndeksli Yayınlar Koleksiyonu / TR Dizin Indexed Publications Collections

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/4

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Now showing 1 - 6 of 6

Citation - WoS: 5
Citation - Scopus: 4
Design, Manufacture and Thermal Analysis of a Single Pass Solar Air Collector at Different Mass Flow Rates
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2020) Darıcı, Selçuk
Solar air collectors are generally used for drying industrial and agricultural products or for space heating. Nowadays solar energy is paid more attention due to decrease in fossil fuels and increase in energy prices. In this study, a single pass, forced convective solar air collector has been designed, manufactured and analysed experimentally under climatic conditions of Konya/Turkey. Experiments have been conducted at three different mass flow rates, on different days and under clear weather conditions. Hourly variation of solar radiation, inlet and outlet air temperatures, glass cover temperature, absorber plate temperature and thermal efficiency of the solar air collector have been examined by using the experimental data obtained. It is seen that with the increase in mass flow rate, temperature of the air at the outlet of the collector decreases while thermal efficiency of the collector increases.
Investigation of the Effects of Molasses-Based Fly Ash Compound on Bitumen and Bituminous Mixture Properties by Laboratory Tests
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2024) Arslan, Deniz; Guru, Metin; Çubuk, M. Kürşat; Öztürk, Şeyma
Purpose: The purpose of the study was to evaluate the effects of molasses based fly ash compound (MEUKB), which was derived chemically as seen in Figure A, on the engineering properties of bitumen and bituminous mixturesTheory and Methods: Rotational viscosity and dynamic shear rheometer tests were used in rheological definition of the modified bitumens. Assessment of MEUKB on bituminous mixture properties were performed through Marshall and Nicholson stripping tests. Results: Viscosity and complex shear modulus were found to be increased by MEUKB doping. Marshall stability and stripping resistance of the bituminous mixtures were increased 10.6 % and 85-90 %, respectively.Conclusion: Roadway pavements manufactured with 3% MEUKB modified bitumen will show greater resistance to deformation type distresses, especially rutting, and stripping problems which may occur more often in regions with heavy rainfall.
Citation - WoS: 3
Citation - Scopus: 4
Investigation on the Effect of Use of Movable Die in Sheet Hydroforming With Die on Formability
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2020) Ankaralı, Mustafa Samet; Dilmeç, Murat; Türköz, Mevlüt
In this study, effect of use of movable die has been numerically investigated on thinning of sheet metal parts in sheet hydroforming with fixed die process using finite element analysis and analyses have been verified experimentally in fixed die. Both of sheet hydroforming processes with fixed and movable die has been modeled by using the same coefficient of friction, blank holder force and pressure curves so as to compare thinning of flat cylindrical part. SS 304 was selected as material. As results of conducted analysis, while maximum percentage of thinning of the part analyzed by using sheet hydroforming processes with fixed die is about 17%, in case of using movable die maximum thinning occurs about 9%. In the other words, maximum thinning of the part analyzed using the hydroforming with movable die is about 8% lower than that's of the fixed die. Moreover, when the strains on the part is evaluated on the forming limit curve, while there is risk of crack on the part analyzed with fixed die, there is no risk of crack on that's of with movable die. Less percentage of thinning of the part analyzed by using sheet hydroforming processes with movable die can be explained by friction duration between sheet metal and die is less than that's of fixed die during the process. Because of less friction duration between sheet metal and die, sheet hydroforming with movable die process, resistance of the sheet metal against to thinning increases
Citation - WoS: 4
Citation - Scopus: 4
A Mathematical Model for Multi-Period Multi-Stage Multi-Mode Multi-Product Capacitated Wheat Supply Network Design Problem and a Case Study
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2022) Dündar, Abdullah Oktay; Tekin, Mahmut; Peker, Kenan; Şahman, Mehmet Akif; Karaoğlan, İsmail
Purpose: The purpose of this paper is to develop a cost-effective network design model, including transport and storage that will enable a decision at a tactical and strategic level to be taken to optimize the structure of the Turkey wheat supply chain. Theory and Methods: The proposed model was developed using 0-1 mixed integer linear programming. First, the model was tested with the data obtained from the interviews with 103 farmers to investigate whether the model worked properly. Then, the case study method was used to test the model with the data obtained from a Flour Mill Company which is one of the first 500 industrial enterprises in Turkey. Results: The results were obtained by using IBM ILOG CPLEX Optimization Studio 12.6.2.0. Although farmers used eighteen different-capacity vehicles for transport, five different-capacity vehicles were used in the model. Smaller capacity vehicles were used by the farmers; however, the model proposed larger-capacity vehicles. Wheat was transported by farmers with 10-ton vehicles using 100 trips, 20-ton vehicles using 115 trips and 30-ton vehicles using 13 trips. However, the model proposed transportation using 10-ton vehicles and 13 trips, 20-ton vehicles and 22 trips and 30-ton vehicles and 151 trips. The proposed model reduced the number of smaller-capacity vehicle trips and increased the number of larger-capacity vehicle trips. As a result, the model has significantly reduced total transportation costs in wheat supply chain in Turkey. Conclusion: In this study, a mathematical model for multi-period multi-stage multi-mode multi-product capacitated was developed for wheat supply chain in Turkey. The developed supply network design model selected a vehicle of the appropriate capacity to suit the amount of load to be transported in the wheat supply chain and decrease the number of vehicle trips. This improvement gained by the model can be applied to other sectors. The model showed that supply warehouses, which have been considered for rental to the private sector, can be effectively used for cost-effectiveness. Additionally, the consolidation of the purchased wheat provides an alternative way for the wheat to be transported, in particular by rail.
Citation - WoS: 1
Citation - Scopus: 2
A Mixed Integer Mathematical Model and a Heuristic Approach for Two Echelon Location Routing Problem With Simultaneous Pickup and Delivery
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2021) Yıldız, Ece Arzu; Karaoğlan, İsmail; Altıparmak, Fulya
This study considers Two Echelon Location Routing Problem with Simultaneous Pickup and Delivery (2E/LRP-SPD). In a two-echelon distribution network consisting of factories, warehouses and customers, the aim is to determine which facilities will be opened in which candidate regions and routing activities to be carried out among them. Routing activities include distributing and collecting activities. While distributing activities are performed from primary facilities (factory) to secondary facilities (depots) and secondary facilities to customers, collecting activities are done from customers to the secondary facilities and from secondary facilities to primary facilities. We propose a two-index node based mixed integer programming formulation for the 2E-LRPSPD. As the problem is in NP-Hard problem class, a constructive heuristic algorithm based on Clarke-Wright algorithm is developed to solve medium- and large- size problems. The performance of the heuristic approach is investigated on test instances derived from literature. Computational results show that heuristic algorithm gives good quality solutions for medium- and large-size instances in a very short computation time. Thus, the contribution of this study to the literature is to present an efficient mathematical model for solving small-size problems and to develop a constructive heuristic algorithm that produces very fast and high-quality solutions for medium and large-size problems.
Citation - WoS: 1
Citation - Scopus: 1
Mobile Healthcare Service Planning in Rural Areas: a Hybrid Record To Record Travel Algorithm
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2024) Akkuş, İlhami; Yıldız, Ece Arzu; Karaoğlan, İsmail; Altıparmak, Fulya
Due to the economic infeasibility of establishing comprehensive healthcare facilities in sparsely populated areas and the responsibility of governments to ensure equal healthcare access for citizens, different approaches have been sought in healthcare service delivery. The Republic of Turkiye's Ministry of Health provides mobile healthcare services (MHS) to 9 million people monthly through 3400 healthcare facilities and 7500 doctors. This study focuses on the Mobile Healthcare Service Routing and Scheduling Problem (MHS-RSP). The objective of MHS-RSP is to determine the daily routes of doctors on a monthly basis to minimize total distance traveled, taking into account constraints such as working hours, route time, minimum service time per visit, and dedicated doctor assignments to villages. A mixed-integer mathematical model is developed to address the problem, which is NP-hard and equivalent to the multi-depot time-constrained periodic vehicle routing problem. To solve medium-and large-sized problems efficiently, a hybrid metaheuristic algorithm named GCH-RRT is introduced, based on greedy constructive heuristic(GCH) and record-to-record travel(RRT) metaheuristic. The performance of the mathematical model and the GCH-RRT algorithm is compared with existing service plans in Ankara, resulting in a 15.6% improvement with the mathematical model and a 22.3% improvement with the GCH-RRT algorithm in total distance traveled.

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