Akdoğan, Muharrem Altan
In this thesis, emergency medical service (EMS) vehicle location problem with uncertainties in demand, travel times, and incident handling time is studied in three layers. The performance measures of EMS systems are evaluated with discrete event simulation models due to the uncertainties incorporated. Firstly, we focus on the equity in service quality resulting from vehicle location decisions in emergency medical services. We address the unbalanced service quality among regions with respect to various mathematical models including conventional ones. An extensive numerical study is conducted to show the effect of modeling approaches and network features on equity. Several observations are drawn and it is shown that the use of overall performance measures in the objective functions of mathematical models ignores other essential criteria, and there is room for improvement in terms of equity. Secondly, we propose decomposition methods based on queueing theory to assess the performance measures of the EMS system under a given location solution without needing to construct computationally cumbersome queueing or simulation models. The proposed decomposition methods require a set of nonlinear equations to be solved simultaneously, yet they are still favorable to exact queueing or simulation models in terms of the computational burden. A genetic algorithm is proposed to use the decomposition method in the optimization problems and find solutions for the EMS vehicle location problem based on queueing theory. It is shown that the proposed methods perform well in assessing the performance measures and evaluating close enough solutions the best solution for the optimization problems. Lastly, we propose mixed integer nonlinear problems (MINLP) with various objective functions incorporating closed-form formulations for the performance measures of the system based on decision variables. With MINLP models, there is no need for estimating problem parameters such as busy probability of vehicles in advance. The proposed models are easier to construct and solve with respect to approximation algorithms or decomposition methods in the literature where stochastic processes are incorporated. Hence, the proposed MINLP models enable decision-makers to incorporate uncertainties in the problem environment directly in the estimation of the parameter of the models based on queueing theory while still keeping the models relatively easy to solve since only the objective functions are nonlinear.


An Integrated optimization and simulation approach for the ambulance location problem
Şahin Macit, Medine; Meral, Fatma Sedef; Department of Industrial Engineering (2015)
Management of smooth-functioning Emergency Medical Services (EMS) along with efficient and effective utilization of ambulances which are an essential part of this service is of vital importance. Selecting the suitable location of ambulance stations and the allocation of ambulances to their corresponding stations are important decisions which directly affect the quality of response to an emergency case. In this study, an integrated optimization and simulation approach is proposed so as to determine the size ...
Location analysis of emergency vehicles using an approximate queueing model
Akdoğan, Muharrem Altan; Bayındır, Zeynep Pelin; İyigün, Cem (Elsevier BV; 2016-09-07)
In this study, location analysis of emergency system vehicles is discussed using an approximate queueing model (AQM) on fully connected networks. We relax single vehicle restriction in each vehicle location which is commonly employed in the literature. Order of districting structure is used to transition rates in AQM. Service rates are computed regarding the location of the demand call and the vehicle, which provides higher resolution than inter-intra district service rates. Generic rate formulations are de...
Locating EMS vehicles in general networks with an approximate queueing model and a metaheuristic solution approach
Akdoğan, Muharrem Altan; Bayındır, Zeynep Pelin; İyigün, Cem; Department of Industrial Engineering (2015)
In this study, problem of optimal location decision of ambulances as an server-to-customer Emergency Medical Service (EMS) vehicle is discussed. Hypercube queueing models (HQM) are employed to achieve performance measures significant to the location decision of EMS vehicles in spatial networks. Geroliminis et al(2009) extends HQM and propose Spatial Queueing Model(SQM). Our study proposes a generalization of SQM to be used in general networks. Quality of approximations inherit to SQM is questioned, and repo...
Preliterate preschoolers oral explanationsand visual narratives in response to picturebooks
Ulusoy, Mustafa; Altun, Dilek (null; 2016-05-01)
Hikâye dinleme ve okuma, çocukların hem ev içi hem de okul öncesi eğitim kurumlarında gelişimlerinin eğlenerek desteklendiği önemli etkinliklerden biridir. Çocuklara sunulacak zengin içerikte, kaliteli çocuk kitapları çocukların gelişimlerini desteklemek adına büyük önem taşımaktadır. Bu nedenle, okul öncesi öğretmenlerinin piyasada yayınlanan kitaplar arasından çocukların gelişim düzeylerine uygun kitapları seçmeleri önem taşımaktadır. Öğretmen adaylarının okuma tutumları ve alışkanlıklarına bağlı olarak k...
Design strategies for the development of home use medical devices: a study on CPAP devices
Okursoy, Mehmet Erçin; Börekçi, Naz Ayşe Güzide Z.; Department of Industrial Design (2021-9-09)
Medical device development and design (MDDD) is one of the sectors with the highest level of safety regulations offering almost risk free products. Actors participating in the development process of these devices (governments, investors, non-governmental organizations, patients, etc.) not only create these highly strict regulations but also define boundaries for the design space in which design strategies are structured. These requirements eliminate suspicions over safety issues and also create a hard shell...
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