Endüstri Mühendisliği Bölümü

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Citation - WoS: 5
Citation - Scopus: 5
A blood distribution problem with new transportation options - an application for the Turkish Red Crescent
(inderscience Enterprises Ltd, 2019) Kurt, Atıl; Kurt, Atil; Cetinkaya, Ferda Can; Çetinkaya, Ferda Can; Azizoglu, Meral; 50129; Endüstri Mühendisliği
This paper considers the blood distribution problem in the Central Anatolian Regional Blood Centre of the Turkish Red Crescent (TRC) and proposes several demand satisfaction options considering the irradiation centres, urgent demands, and product availability. Our aim is to maximise the total weighted blood demand satisfaction. To address the problem, we develop a mixed integer linear programming model and propose a hybrid genetic algorithm (HGA). The results of our experiments have revealed that the mathematical model cannot handle even small sized problem instances in reasonable times; however, the hybrid genetic algorithm is capable of handling complex daily operations of the Turkish Red Crescent.
Citation - WoS: 5
Citation - Scopus: 14
A branch and bound algorithm for sector allocation of a naval task group
(Wiley-blackwell, 2011) Karasakal, Orhan; Karasakal, Orhan; Kandiller, Levent; Kandiller, Levent; Ozdemirel, Nur Evin; 5706; 2634; Endüstri Mühendisliği
A naval task group (TG) is a collection of naval combatants and auxiliaries that are grouped together for the accomplishment of one or more missions. Ships forming a TG are located in predefined sectors. We define determination of ship sector locations to provide a robust air defense formation as the sector allocation problem (SAP). A robust formation is one that is very effective against a variety of attack scenarios but not necessarily the most effective against any scenario. We propose a 0-1 integer linear programming formulation for SAP. The model takes the size and the direction of threat into account as well as the defensive weapons of the naval TG. We develop tight lower and upper bounds by incorporating some valid inequalities and use a branch and bound algorithm to exactly solve SAP. We report computational results that demonstrate the effectiveness of the proposed solution approach. (C) 2011 Wiley Periodicals, Inc. Naval Research Logistics 58: 655-669, 2011
Citation - WoS: 0
A partial coverage hierarchical location allocation model for health services
(inderscience Enterprises Ltd, 2023) Karasakal, Orhan; Karasakal, Orhan; Karasakal, Esra; Toreyen, Ozgun; 216553; Endüstri Mühendisliği
We consider a hierarchical maximal covering location problem (HMCLP) to locate health centres and hospitals so that the maximum demand is covered by two levels of services in a successively inclusive hierarchy. We extend the HMCLP by introducing the partial coverage and a new definition of the referral. The proposed model may enable an informed decision on the healthcare system when dynamic adaptation is required, such as a COVID-19 pandemic. We define the referral as coverage of health centres by hospitals. A hospital may also cover demand through referral. The proposed model is solved optimally for small problems. For large problems, we propose a customised genetic algorithm. Computational study shows that the GA performs well, and the partial coverage substantially affects the optimal solutions. [Submitted: 20 January 2021; Accepted: 15 January 2022]
Citation - WoS: 201
Citation - Scopus: 228
Ammonia removal from anaerobically digested dairy manure by struvite precipitation
(Elsevier Sci Ltd, 2005) Uludag-Demirer, S; Demirer, GN; Chen, S
Ammonia is one of the most important contaminants impairing the quality of water resources. When this is considered along with the fact that the global demand for nitrogenous fertilizers is in constant rise, the need for recovery as well as removal of nitrogen is well justified. Crystallization of N and P in the form of struvite (MgNH4PO4 center dot 6H(2)O), which is a slow releasing and valuable fertilizer, is one possible technique for this purpose. This study investigated the removal of NR4+ through struvite precipitation from the effluents of one- (R1) and two-phase (R2) anaerobic reactors digesting dairy manure. To force the formation of struvite in the anaerobic reactor effluents, Ma(2+) ion was added by using both Mg(OH)(2) and MgCl2 center dot 6H(2)O. To prevent the effect of different total phosphorus (TP) concentration in the effluents of RI and R2, as well as to not limit the formation of struvite, an excess amount Of PO43- (0.14 M) was added in the form of NaHPO4. Different stoichiometric Mg2+:NH4+:PO43- ratios were tested to determine the required Mg2+ concentrations for maximum NH4+ removal by keeping NH4+:PO43- ratio constant for the effluents of reactors RI and R2. The results revealed that very high NH4+ removal efficiencies (above 95%) were possible by adding Mg 21 ions higher than 0.06 M concentration in the effluents from reactors RI and R2. It was also observed that the initial pH adjustment to 8.50 using NaOH did not result in any significant increase in the removal of NH4+ and the removal of NH4+ in the reactors treated with MgCl2 center dot 6H(2)O was higher than those treated with Mg(OH)(2) for the same Mg2+ concentration. (c) 2005 Published by Elsevier Ltd.
Citation - WoS: 6
Citation - Scopus: 7
An approximation for kanban controlled assembly systems
(Springer, 2011) Topan, Engin; Topan, Engin; Avsar, Zeynep Muge; 164129; Endüstri Mühendisliği
An approximation is proposed to evaluate the steady-state performance of kanban controlled two-stage assembly systems. The development of the approximation is as follows. The considered continuous-time Markov chain is aggregated keeping the model exact, and this aggregate model is approximated replacing some state-dependent transition rates with constant rates. The approximate aggregate model is, then, decomposed into submodels and a product-form steady-state distribution is obtained for each submodel. Finally, the submodels are combined in such a way that the size of the problem becomes independent of the number of kanbans. This leads to the computational advantage in solving the combined model using numerical matrix-geometric solution algorithms. Numerical comparisons of the combined model with simulation, exact model, approximate aggregate model and an approximation in the literature show that the proposed approximation performs well in terms of accuracy and computational burden.
Citation - WoS: 11
Analysis of Dengue Transmission Dynamic Model by Stability and Hopf Bifurcation with Two-Time Delays
(Imr Press, 2023) Murugadoss, Prakash Raj; Baleanu, Dumitru; Ambalarajan, Venkatesh; Sivakumar, Vinoth; Dhandapani, Prasantha Bharathi; Baleanu, Dumitru; 56389; Matematik
Background: Mathematical models reflecting the epidemiological dynamics of dengue infection have been discovered dating back to 1970. The four serotypes (DENV-1 to DENV-4) that cause dengue fever are antigenically related but different viruses that are transmitted by mosquitoes. It is a significant global public health issue since 2.5 billion individuals are at risk of contracting the virus. Methods: The purpose of this study is to carefully examine the transmission of dengue with a time delay. A dengue transmission dynamic model with two delays, the standard incidence, loss of immunity, recovery from infectiousness, and partial protection of the human population was developed. Results: Both endemic equilibrium and illness-free equilibrium were examined in terms of the stability theory of delay differential equations. As long as the basic reproduction number (R0) is less than unity, the illness-free equilibrium is locally asymptotically stable; however, when R0 exceeds unity, the equilibrium becomes unstable. The existence of Hopf bifurcation with delay as a bifurcation parameter and the conditions for endemic equilibrium stability were examined. To validate the theoretical results, numerical simulations were done. Conclusions: The length of the time delay in the dengue transmission epidemic model has no effect on the stability of the illness-free equilibrium. Regardless, Hopf bifurcation may occur depending on how much the delay impacts the stability of the underlying equilibrium. This mathematical modelling is effective for providing qualitative evaluations for the recovery of a huge population of afflicted community members with a time delay.
Citation - WoS: 26
Citation - Scopus: 35
Anti-ship missile defense for a naval task group
(Wiley-blackwell, 2011) Karasakal, Orhan; Karasakal, Orhan; Ozdemirel, Nur Evin; Kandiller, Levent; Kandiller, Levent; 2634; 5706; Endüstri Mühendisliği
In this study, we present a new formulation for the air defense problem of warships in a naval task group and propose a solution method. We define the missile allocation problem (MAP) as the optimal allocation of a set of surface-to-air missiles (SAMs) of a naval task group to a set of attacking air targets. MAP is a new treatment of an emerging problem fostered by the rapid increase in the capabilities of anti-ship missiles (ASMs), the different levels of air defense capabilities of the warships against the ASM threat, and new technology that enables a fully coordinated and collective defense. In addition to allocating SAMs to ASMs, MAP also schedules launching of SAM rounds according to shoot-look-shoot engagement policy or its variations, considering multiple SAM systems and ASM types. MAP can be used for air defense planning under a given scenario. As thorough scenario analysis would require repetitive use of MAP, we propose efficient heuristic procedures for solving the problem. (C) 2011 Wiley Periodicals, Inc. Naval Research Logistics 58: 305-322, 2011
Citation - WoS: 17
Citation - Scopus: 17
Bi-objective dynamic weapon-target assignment problem with stability measure
(Springer, 2022) Silav, Ahmet; Karasakal, Orhan; Karasakal, Esra; Karasakal, Orhan; 216553; Endüstri Mühendisliği
In this paper, we develop a new bi-objective model for dynamic weapon-target assignment problem. We consider that the initial weapon assignment plan of defense is disrupted during engagement because of a destroyed air target, breakdown of a weapon system or a new incoming air target. The objective functions are defined as the maximization of probability of no-leaker and the maximization of stability in engagement order of weapon systems. Stability is defined as assigning same air target in sequence in engagement order of a weapon system so that reacquisition and re-tracking of air target are not required by sensors. We propose a new solution procedure to generate updated assignment plans by maximizing efficiency of defense while maximizing stability through swapping weapon engagement orders. The proposed solution procedure generates non-dominated solutions from which defense can quickly choose the most-favored course of action. We solve a set of representative problems with different sizes and present computational results to evaluate effectiveness of the proposed approach.
Citation - WoS: 6
Citation - Scopus: 9
Bi-objective missile rescheduling for a naval task group with dynamic disruptions
(Wiley, 2019) Silav, Ahmet; Karasakal, Orhan; Karasakal, Orhan; Karasakal, Esra; 216553; Endüstri Mühendisliği
This paper considers the rescheduling of surface-to-air missiles (SAMs) for a naval task group (TG), where a set of SAMs have already been scheduled to intercept a set of anti-ship missiles (ASMs). In missile defense, the initial engagement schedule is developed according to the initial state of the defensive and attacking units. However, unforeseen events may arise during the engagement, creating a dynamic environment to be handled, and making the initial schedule infeasible or inefficient. In this study, the initial engagement schedule of a TG is assumed to be disrupted by the occurrence of a destroyed ASM, the breakdown of a SAM system, or an incoming new target ASM. To produce an updated schedule, a new biobjective mathematical model is formulated that maximizes the no-leaker probability value for the TG and minimizes the total deviation from the initial schedule. With the problem shown to be NP-hard, some special cases are presented that can be solved in polynomial time. We solve small size problems by the augmented epsilon-constraint method and propose heuristic procedures to generate a set of nondominated solutions for larger problems. The results are presented for different size problems and the total effectiveness of the model is evaluated.
Citation - WoS: 3
Citation - Scopus: 4
Comparison of classroom furniture to anthropometric measures of Turkish middle school students
(Ios Press, 2021) Satir, Benhur; Satır, Benhür; Erdogan, Filiz Celikci; 54700; Endüstri Mühendisliği
BACKGROUND: The match between classroom furniture and students' anthropometry is an important factor in students' academic performance. OBJECTIVE: Our aim was to investigate the ergonomic suitability of the classroom furniture to the students, and to propose design suggestions for both desks and chairs. METHODS: We analyzed the ergonomics of classroom furniture that students aged 10-14 years old in Turkey currently use. To this end, we selected Maltepe Primary Education School, one of the largest schools in the cankaya district of Turkey's capital city, Ankara, in which to conduct the study. A sample of 119 students was selected, and seven anthropometric measurements were taken for each of these students. We then calculated five relationships between the dimensions of the furniture and the students' anthropometric measures. RESULTS: We observed high levels of mismatch rates, with an average of 66.6% and high values of over 95% for the relations of two furniture measures, seat depth (related with buttock-popliteal length) and seat-to-desk height (related with elbow height, sitting). Each anthropometric measure was applied a fit probability distribution, and based on those distributions; we suggested the most appropriate classroom furniture dimensions in order to maximize suitability of the furniture to the anthropometric measures in terms of fixed-size (i.e., non-adjustable) classroom furniture. CONCLUSIONS: High mismatch rates can be reduced by 52.0% on average based on the classroom furniture dimensions suggested in this study.
Citation - WoS: 0
Citation - Scopus: 0
Control of trichloroethylene emissions from sparging systems by horizontal bio- and chemo-barriers
(Selper Ltd, Publications Div, 2005) Tezel, U; Demirer, GN; Uludag-Demirer, S
The scope of this study was to develop a continuous system to clean-up a trichloroethylene (TCE) contaminated gas stream, where biotic and abiotic removal mechanisms are undertaken sequentially simulating the horizontal bio- and chemo-barriers proposed for the in-situ remediation of the contaminated sites. The bio- and chemo-barriers were simulated by using glass columns packed with granular anaerobic mixed culture and Fe(0) filings, respectively. The effect of gas residence time, which is adjusted by the gas flowrate, on the TCE removal efficiency of the reactor system was investigated. TCE removal efficiency of over 90% was achieved at gas residence times above 1hr. Furthermore, the effluent of reactor system contained only ethane and ethylene, which are non-toxic by-products of TCE reduction reactions, along with trace amounts of TCE.
Citation - WoS: 27
Citation - Scopus: 30
Customer order scheduling problem: a comparative metaheuristics study
(Springer London Ltd, 2008) Hazir, Oncue; Gunalay, Yavuz; Erel, Erdal; 56488; 3019; 1986
The customer order scheduling problem (COSP) is defined as to determine the sequence of tasks to satisfy the demand of customers who order several types of products produced on a single machine. A setup is required whenever a product type is launched. The objective of the scheduling problem is to minimize the average customer order flow time. Since the customer order scheduling problem is known to be strongly NP-hard, we solve it using four major metaheuristics and compare the performance of these heuristics, namely, simulated annealing, genetic algorithms, tabu search, and ant colony optimization. These are selected to represent various characteristics of metaheuristics: nature-inspired vs. artificially created, population-based vs. local search, etc. A set of problems is generated to compare the solution quality and computational efforts of these heuristics. Results of the experimentation show that tabu search and ant colony perform better for large problems whereas simulated annealing performs best in small-size problems. Some conclusions are also drawn on the interactions between various problem parameters and the performance of the heuristics.
Citation - WoS: 3
Citation - Scopus: 9
Customer order scheduling with job-based processing on a single-machine to minimize the total completion time
(Growing Science, 2021) Cetinkaya, Ferda Can; Çetinkaya, Ferda Can; Yeloglu, Pinar; Catmakas, Hale Akkocaoglu; 50129; Endüstri Mühendisliği
This study considers a customer order scheduling (COS) problem in which each customer requests a variety of products (jobs) processed on a single flexible machine, such as the computer numerical control (CNC) machine. A sequence-independent setup for the machine is needed before processing each product. All products in a customer order are delivered to the customer when they are processed. The product ordered by a customer and completed as the last product in the order defines the customer order's completion time. We aim to find the optimal schedule of the customer orders and the products to minimize the customer orders' total completion time. We have studied this customer order scheduling problem with a job-based processing approach in which the same products from different customer orders form a product lot and are processed successively without being intermingled with other products. We have developed two mixed-integer linear programming models capable of solving the small and medium-sized problem instances optimally and a heuristic algorithm for large-sized problem instances. Our empirical study results show that our proposed tabu search algorithm provides optimal or near-optimal solutions in a very short time. We have also compared the job-based and order-based processing approaches for both setup and no-setup cases and observed that the job-based processing approach yields better results when jobs have setup times. (C) 2021 by the authors; licensee Growing Science, Canada
Citation - WoS: 21
Citation - Scopus: 24
Effects of electrospinning process parameters on nanofibers obtained from Nylon 6 and poly (ethylene-n-butyl acrylate-maleic anhydride) elastomer blends using Johnson S-B statistical distribution function
(Springer, 2010) Biber, Erkan; Gunduz, Gungor; Mavis, Bora; Colak, Uner; 169408; 169746
The impact strength of Nylon 6 can be further improved by blending it with ethylene-butyl acrylate-maleic anhydride elastomer. The blending is achieved in solution phase. Due to incompatibility of Nylon 6 and the elastomer, a special mixture of solvents is used to dissolve both components. The solution is electrospun, and the effects of the process parameters on the expected radii of nanofibers are investigated. The effects of process parameters such as polymer concentration in solution, electrical field, diameter of the syringe needle, feed rate, and collector geometry on nanofibers were investigated. Statistical analysis is carried out using the Johnson S-B distribution. A relation is proposed to relate the effect of the process parameters feed rate, electrical voltage, and tip to collector distance on the expected diameter of fibers. It is found that concentration and electrical field have a profound effect on the diameter of fibers compared to those of the syringe diameter and feed rate.
Citation - WoS: 16
Citation - Scopus: 17
Freight transportation using high-speed train systems
(Taylor & Francis Ltd, 2016) Ertem, M. A.; Ertem, Mustafa Alp; Ozcan, M. Keskin; 52460; 52460; Endüstri Mühendisliği
This study investigates the use of high-speed trains (HSTs) for transporting freight, such as small cargo and mail. A HST scheduling model is constructed to observe the effects of including freight in a passenger-only system. The proposed mathematical model is tested with an experimental study using the Turkish State Railways high-speed rail network and train sets. Freight transportation is analyzed in two cases, namely, adding separate freight trains to the system and using passenger trains for freight transportation. It can be concluded that dividing the sequences of cities into two allows for the completion of train services earlier in the day, and using the same train for transporting both passengers and freight provides more time saving in the system.
Citation - WoS: 4
Citation - Scopus: 4
Inference in multivariate linear regression models with elliptically distributed errors
(Taylor & Francis Ltd, 2014) Yıldırım, Fetih; Islam, M. Qamarul; Yildirim, Fetih; Yazıcı, Mehmet; Yazici, Mehmet; 6772; 144084; Ortak Dersler Bölümü; İktisat
In this study we investigate the problem of estimation and testing of hypotheses in multivariate linear regression models when the errors involved are assumed to be non-normally distributed. We consider the class of heavy-tailed distributions for this purpose. Although our method is applicable for any distribution in this class, we take the multivariate t-distribution for illustration. This distribution has applications in many fields of applied research such as Economics, Business, and Finance. For estimation purpose, we use the modified maximum likelihood method in order to get the so-called modified maximum likelihood estimates that are obtained in a closed form. We show that these estimates are substantially more efficient than least-square estimates. They are also found to be robust to reasonable deviations from the assumed distribution and also many data anomalies such as the presence of outliers in the sample, etc. We further provide test statistics for testing the relevant hypothesis regarding the regression coefficients.
Citation - WoS: 3
Citation - Scopus: 5
Lot Streaming In A Two-Machine Mixed Shop
(Springer London Ltd, 2010) Cetinkaya, Ferda C.; Çetinkaya, Ferda Can; Duman, Mehmet; 50129; Endüstri Mühendisliği
Most classical scheduling models overlook the fact that products are often produced in job lots and assume that job lots are indivisible single entities, although an entire job lot consists of many identical items. However, splitting an entire lot (process batch) into sublots (transfer batches) to be moved to downstream machines allows the overlapping of different operations on the same product while work needs to be completed on the upstream machine. This approach is known as lot streaming in scheduling theory. In this study, the lot streaming problem of multiple jobs in a two-machine mixed shop where there are two different job types as flow shop and open shop is addressed so as to minimize the makespan. The optimal solution method is developed for the mixed shop scheduling problem in which lot streaming can improve the makespan.
Citation - WoS: 5
Citation - Scopus: 7
LP relaxation-based solution algorithms for the multi-mode project scheduling with a non-renewable resource
(inderscience Enterprises Ltd, 2015) Azizoglu, Meral; Çetinkaya, Ferda Can; Cetinkaya, Ferda Can; Pamir, Selin Kirbiyik; 5546; 50129; Endüstri Mühendisliği
In this study, we consider a multi-mode resource allocation problem with a single non-renewable resource. We assume the resource is released at defined time points and at defined quantities. We also assume that the activity costs are charged once they are completed. Our aim is to minimise the project completion time. We formulate the problem as a pure integer programming model and show that it is strongly NP-hard. We find lower bounds by pure and mixed integer linear programming relaxations of the model and develop three heuristic procedures based on those relaxations. The results of our computational study have revealed the satisfactory performances of our lower bounds and heuristic procedures.
Citation - WoS: 1
Citation - Scopus: 1
Naval Air Defense Planning problem: A novel formulation and heuristics
(Wiley, 2024) Arslan, Caner; Karasakal, Orhan; Karasakal, Orhan; Kirca, Oemer; Endüstri Mühendisliği
This article focuses on air defense in maritime environment, which involves protecting friendly naval assets from aerial threats. Specifically, we define and address the Naval Air Defense Planning (NADP) problem, which consists of maneuvering decisions of the ships and scheduling weapons and sensors to the threats in order to maximize the total expected survival probability of friendly units. The NADP problem is more realistic and applicable than previous studies, as it considers features such as sensor assignment requirements, weapon and sensor blind sectors, sequence-dependent setup times, and ship's infrared/radar signature. In this study, a mixed-integer nonlinear programming model of the NADP problem is presented and heuristic solution approaches are developed. Computational results demonstrate that these heuristic approaches are both fast and efficient in solving the NADP problem.
Citation - WoS: 4
Citation - Scopus: 3
Optimum bidding strategy for wind and solar power plants in day-ahead electricity market
(Springer Heidelberg, 2021) Ozcan, Mehmet; Satır, Benhür; Keysan, Ozan; Satir, Benhur; 54700; Endüstri Mühendisliği
There are two possible strategies for wind power plants (WPPs) and solar power plants (SPPs) to maximize their income in day ahead markets (DAM) in the presence of imbalance cost: joint bidding (JB) via collaboration by participating to balancing groups and deployment of storage technologies. There are limited studies in the literature covering the comparative analysis of "JB strategy" with "battery deployment (BD) strategy". In the existence of balancing responsibility, the comparative analysis of these strategies is the main contribution of this study to the literature. Our Second contribution is the analysis of the impact of different regulatory regimes, which are set by the regulatory authority, on total income. JBM (joint bidding model), which is the model for joint bidding via different collaboration groups, is developed for the analysis of JB strategy, BDM (battery deployment model), which is the model covering the deployment of storage technology, is developed for the analysis of BD strategy. The impact of each strategy on total income is analyzed. According to the analysis of the results of the models, while JB strategy, which is sensitive to the regulatory regime, increases the total annual income of the collaboration groups up to 0.65%, BD strategy seems not feasible and financially viable. On the other hand, extra income values per MW of battery for SPP is between $218 and $400 /MW-year, while these values are between $2460 and $6795/MW-year for the group of 15 WPPs. Therefore, deployment of battery for WPPs creates extra income more than tenfold of that of SPP. BD strategy can be viable provided that the levelized cost of deployment of battery drops below the extra income values achieved per MW of battery.

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