Ertugrul Ayyildiz

• Karadeniz Technical University

The rapid advancements in 3D printing technologies have significantly reshaped the manufacturing landscape, enabling highly customized and efficient production processes. However, selecting the most appropriate 3D printing technology for custom manufacturing is a complex decision that requires careful consideration of multiple, often conflicting cr...

Ensuring resilience in healthcare supply chains (HSCs) is crucial for maintaining the timely, accurate, and reliable delivery of common goods in health, especially in the face of disruptions such as pandemics or natural disasters. This study investigates the role of Industry 4.0 strategies in enhancing HSC resilience through a two-stage optimizatio...

Earth observation (EO) provides dynamic scientific methods for tracking and defining ecological parameters in mountainous regions. Open-source platforms are frequently utilized in this context to efficiently collect and evaluate spatial data. In this study, we used Collect Earth (CE), an open-source land monitoring platform, to reveal and assess la...

Recognizing the significant role of the supply chain in economic activity, it is crucial to address its vulnerability areas. This research focuses on the forestry industry, where obtaining and maintaining the primary raw material source is notably more challenging compared to other supply chains. The primary objective of this study is to analyze vu...

In response to heightened competition arising from globalization, companies are crafting strategies to sustain their operations. However, these strategies also introduce risks that require meticulous management. The onset of the COVID-19 pandemic has exacerbated disruptions in supply chains, including the vulnerable food supply chain (FCS), straine...

Efficient freight carrier selection is pivotal to modern logistics and supply chain management, demanding a systematic approach to navigate the complexity of factors such as cost, reliability, sustainability, and collaboration. This study aims to prioritize these factors using the Best Worst Method (BWM), offering a novel framework for enhancing de...

The escalating global challenges of population growth, climate crisis, and resource depletion have intensified water scarcity, emphasizing the critical role of wastewater treatment (WWT) in environmental preservation. While discharging untreated wastewater poses extinction risks to various species, effective WWT operations are indispensable for eco...

The increase in waste and related environmental problems is one of the major problems compromising health and environmental quality in urban and rural areas. There are a number of policies that can be implemented to reduce waste, but since it cannot be completely eliminated, recycling and disposal facilities for waste will always be required. Resea...

Earth observation (EO) provides dynamic scientific methods for tracking and defining ecological parameters in mountainous regions. Open-source platforms are frequently utilized in this context to efficiently collect and evaluate spatial data. In this study, we used Collect Earth (CE), an open-source land monitoring platform, to reveal and assess la...

Küresel hava yolcu trafiğinin son yıllarda istikrarlı bir büyüme göstermesiyle birlikte havalimanı hizmet kalitesi faktörlerinin incelenmesi daha fazla önem kazanmıştır. Bu çalışmada, havalimanı hizmet kalitesini ölçmek için mevcut standartların ve yöntemlerin değerlendirilmesi amaçlanmaktadır. Araştırma kapsamındaki değerlendirme kriterleri, havay...

Purpose Blood availability is critical for saving lives in various healthcare services. Ensuring blood availability can only be achieved through efficient management of the blood supply chain (BSC). A key component of the BSC is bloodmobiles, which are responsible for a significant portion of blood donation collections. The most crucial factor affe...

Considering that cooling in cooling systems is more costly than heating, the importance of refrigerant selection in cooling systems is even more obvious. Due to the complexity of the refrigerant selection problem, a multi-criteria decision approach must be used to implement a thorough and organized evaluation of the factors. The purpose of this stu...

Practitioners and decision-makers often face difficulties in selecting and prioritizing effective strategies to address challenges to sustainable urban transportation development. Although there has been considerable research conducted on the subject, the Tanzanian context, which is greatly affected by social and environmental problems, has receive...

Gasoline is one of the most sought-after resources in the world, where the need for energy is indispensable and continuously increasing for human life today. A shortage of gasoline may negatively affect the economies of countries. Therefore, analyzes and estimates about gasoline consumption are critical. Better forecast performance on gasoline cons...

An emerging question for photovoltaic (PV) solar power development is how to ascertain the optimal choice from a finite set of available alternatives under numerous conflicting criteria as well as high levels of imprecise, vague, and uncertain information. For the first time, we investigate the prioritization of the alternatives for the development...

Risk analizi ve yönetimi, işletmelerin karşılaşabilecekleri olası tehlikeleri belirleyerek bu risklere etkin bir şekilde yanıt verme sürecidir. Risk analizi ve yönetimi, organizasyonların daha iyi kararlar vermesini, operasyonel verimliliği artırmasını ve kriz durumlarına hazırlıklı olmasını sağlar. Ayrıca, risklerin önceden belirlenmesi ve uygun ö...

The absence of effective coordination among different institutions involved in planning for public transportation has become a prominent global concern. At present, numerous cities are grappling with the need to establish a customized framework for institutional coordination that aligns with the specific circumstances of each city. Decision-makers...

As an alternate mode of transportation, the use of shared bicycle and scooter systems, which are now being brought to the forefront under the term micromobility, has recently been increasing. Among them, electric scooters called e-scooters have started to be preferred frequently due to their ease of use. With this study, the factors to be considere...

Social loafing refers to a decrease in motivation and effort between group members when working collectively compared to when working individually. This phenomenon can be a problem in many settings, including search and rescue teams. In a disaster or emergency situation, every team member needs to be at their best to save lives. However, social loa...

The Orienteering Problem (OP) is an optimization problem that finds the locations and routes that will return the highest profit/benefit, starting from the initial location of the traveler/vehicle, visiting these locations, and ending with the starting location of the tour within a given time or distance limit. There is no obligation to visit all l...

The statistics pertaining to accidents occurring at construction sites underscore the pressing requirement for a substantial and timely reevaluation of safety measures within the construction sector. Accidents do not occur randomly; rather, they arise from the presence of unsafe actions, hazardous conditions, or a combination of both. The majority...

In this study, we handle the geothermal power plant location selection problem by considering environmental conditions and aim to determine the critical factors in this decision problem and to determine their order of importance. For this purpose, after a detailed literature research and interviews with experts, we determine the factors that should...

The planning and execution of the entire process in a way that protects the environment, beginning with the supply of the raw materials and ending with the waste or leftover product produced by the consumer, is known as the “green supply chain.” The traditional supply chain has been replaced by a green one as a result of the rapid depletion of vita...

Bu çalışma, makine öğrenimi/yapay zekanın (ML/AI) sağlık tedarik zincirine entegrasyonu ile ilgilipotansiyel faydalar, zorluklar ve stratejik hususların kapsamlı bir analizini sunmaktadır. Sağlıksistemlerinin artan karmaşıklığı ve talepleriyle birlikte, ML/AI teknolojilerinden yararlanmak, tedarikzinciri operasyonlarını optimize etmek ve hasta sonu...

Online eğitim son yıllarda önemli ölçüde popülerlik kazanmıştır ve giderek artan sayıda lisans dersi,bir değerlendirme aracı olarak online sınavları içermektedir. Ancak, lisans öğrencileri arasında çevrimiçisınavlarda gözlemlenen yüksek başarısızlık oranları, bu değerlendirme yönteminin etkinliği konusundaendişelere yol açmıştır. Bu çalışma, çevrim...

The East African Community, inspired by successful trading blocs, has already begun major transportation strategic plans that will necessarily require large investments. Additionally, significant efforts have been made to harmonize regional transportation legislation and regulations. However, some challenges that may arise in developing such a sust...

Increasing competition in higher education forces universities to take steps to improve the quality of service. Pre-determining crucial factors in the provision of educational services is significant to ensure student satisfaction, and thus to strengthen the bond of students with the university. The perception of students and employers about the qu...

The lack of coordination among global institutions responsible for planning public transportation is a persistent issue. To tackle this issue, three strategies aimed at promoting sustainability have been proposed. However, there is a significant deficiency in preferentially prioritizing them, which poses a significant issue for local governments. I...

Floods are one of the natural disasters that affect human life materially and morally. There are various measures to prevent flood damage. The evaluation of flood risk and assembly points is of great importance for flood risk preparation and disaster mitigation measures. This study presents a two-stage framework with a multi-criteria decision-makin...

One of the main causes of the significant commercial vehicle traffic in the city region is last-mile deliveries. Parcel lockers, which are one of the easiest and most environmentally friendly solutions for last-mile delivery, are one of the most studied subjects recently. The parcel locker ensures consumer privacy while being quick and efficient. I...

With the increase in the consumption of petroleum and petroleum products, these limited resources must be provided efficiently, accurately, and with minimal damage. Therefore, the accurate and effective distribution of petroleum, and related problems with petroleum distribution have attracted much attention among the practitioners and optimization...

University rankings are an essential source of comparisons between universities according to specific combinations of criteria. International or national rankings have an increasing impact on higher education institutions, stakeholders, and their environments. Thereby, on behalf of effective decision-making, university-ranking efforts should be a p...

Single-minute exchange of dies (SMED) is one of the most significant lean tools which reduces the required time for setup operations. The consideration of appropriate ergonomic interferences during the SMED implementation improves working conditions, productivity, and flexibility. The SMED literature has an opportunity for expansion with ergonomic...

This paper defines a capacitated multiple-source multiple-sink shortest path problem and introduces its extension, called the capacitated multiple-source multiple-sink shortest path network interdiction problem (CMSSNIP). CMSSNIP examines the actions of attackers who attempt to maximize the total shortest path of network users trying to reach the c...

This study focuses on how to determine the location of electric scooter (e-scooter) charging stations. In the station location determination problem, the sustainability perspective, which is one of the indispensable elements of smart city practices, is focused. To solve the highlighted problem, new three-stage pythagorean fuzzy group decision-makin...

Successfully managing the supply chain, which has become complex with many factors such as changes in customer demands, social perception, ease of access to information, advances in technology, increasing needs, and changing environmental conditions, provides great convenience to businesses. Effective supply chain and all operations management in t...

The Cash in Transit (CIT) deals with the money distribution and picking up between depot(s), central bank, bank branches, Automated Teller Machines (ATMs), jewelry stores, and exchange offices, safely and quickly. It is critical for companies carrying out CIT activities to identify risks and their priorities. It is one of the problems to be resolve...

The cash in transit (CIT) problem is a version of the vehicle routing problem (VRP), which deals with the planning of money distribution from the depot(s) to the automated teller machines (ATMs) safely and quickly. This study investigates a novel CIT problem, which is a variant of time-dependent VRP with time windows. To establish a more realistic...

Pharmaceutical warehouses are among the centers that play a critical role in the delivery of medicines from the producers to the consumers. Especially with the new drugs and vaccines added during the pandemic period to the supply chain, the importance of the regions they are located in has increased critically. Since the selection of pharmaceutical...

The issue related to energy efficiency is being addressed worldwide as a subject that is becoming more and more important every day. The implementation of insulation measures for buildings, which is one of the most crucial measures of energy consumption, is a critical issue that can be applied to both increase efficiency and reduce the greenhouse g...

It is essential to measure the quality and performance of health centers and propose policies in order for health services to continue without interruption during the pandemic period and for the continuous and proper implementation of new procedures in hospitals with COVID-19.The measurement of service quality and performance in hospitals should be...

Due to unconscious consumption of natural water resources and climate change, a water crisis is expected in the upcoming years. At this point, it is necessary to know the water levels in the dams and develop strategies for water-saving applications in the coming periods. This study aimed to propose the artificial neural network models for forecasti...

The Sustainable Development Goals have been developed with the aim of ensuring that no individual living in the world is left behind from the social, economic and environmental gains achieved. Accessible and Clean Energy, the Sustainable Development Goal-7 (SDG-7), aims to provide accessible, reliable and sustainable energy for all. In this study,...

COVID-19 pandemic has affected the entire world. During the Covid-19 pandemic, which is tried to be prevented by all countries of the world, regulations have been made to reduce the effect of the virus in sectors such as banking, tourism, and especially transportation. Social isolation is one of the most critical factors for people who have or are...

Measuring customer satisfaction in service businesses is very important in terms of both increasing service quality and meeting customer expectations. Up-to-date and comprehensive quality of service measurement techniques provide important information to the companies about the way customers perceive the quality and their service quality expectatio...

There is an increase in the number of people who have changed their country for compulsory reasons due to the wars experienced worldwide. This raises the problem of identifying the regions where these people, called refugees, will live in the countries. In this regard, we determine in this paper where the camps established for refugees living in Is...

This study introduces a forecasting model to help design an effective blood supply chain mechanism for tackling the COVID-19 pandemic. In doing so, first, the number of people recovered from COVID-19 is forecasted using the Artificial Neural Networks (ANNs) to determine potential donors for convalescent (immune) plasma (CIP) treatment of COVID-19....

Supply chain organizations should calmly and cautiously take the most accurate and sustainable decisions quickly and put them into practice. It is obvious that traditional time series–based demand and supply planning approaches are insufficient to meet current business needs due to factors such as sharp changes in market and commercial dynamics, pa...

Şehirlerarası otobüs firmaları, yolcularına güvenli, kaliteli ve konforlu yolculuklar vadederek maksimum yolcu memnuniyetini elde etmeyi amaçlamaktadırlar. Çalışmada, yapılan literatür taraması ve sektörde çalışan uzmanlarla görüşmeler neticesinde, şehirlerarası otobüs firmaları için yolcuların kalite beklentilerini değerlendirmek üzere hizmet, kon...

Service quality is one of the most important factors that increase the use of public transportation, especially in metropolitan cities such as Istanbul. When evaluating service quality in public transportation systems, one of the most important factors is customer satisfaction. The increase in service quality increases the usage of public transport...

Environment and social life are open to hazards, because of the distribution, diffusion, and conversion processes of chemicals contained in hazardous materials. These chemicals are very dangerous. Various precautions should be taken into consideration during the displacement of hazardous materials. Therefore, it is important to identify and minimiz...

Many governments decided to cancel face‐to‐face teaching and learning activities in schools and universities. They replaced them with online teaching and distance learning activities to prevent the spread of Coronavirus disease 2019 (COVID‐19). Due to this sudden change, students experienced some anthropometric, environmental, and psychosocial diff...

Earthquakes are the leading natural disasters that seriously affect human life. Furthermore, earthquakes are natural disasters that have the ability to trigger a second disaster in addition to the damages they cause. From this point of view, post-earthquake fires are defined as the one of the most dangerous secondary disasters after an earthquake a...

Water treatment plants play a major role in the cycle of water recovery and reuse. Besides the benefits of water treatment plants, they have a great impact on the environment, social life, economy, and natural habitats. In this sense, decision-makers should effectively plan the construction and operational activities of plants, taking into account...

Public and private companies make significant water infrastructure investments to meet increasing water demand. In this context, investments in wastewater treatment plants (WWTPs), which play an important role in recycling of used water, are also increasing. This study investigates determination of the efficiency scores of WWTPs considering each me...

Oryantiring Problemi (OP) gezginin/aracın başlangıç noktasından başlayarak en yüksek karı/faydayı sağlayan konumların belirlenmesi ve bu konumlara uğranılmasından oluşan ve turun başlangıç noktasında sonuçlandığı bir optimizasyon problemidir. Problem yapısında tüm müşterilere uğrama zorunluluğu yoktur. OP, NP-zor bir kombinatoryal optimizasyon prob...

Supply chain operations reference (SCOR) is a combined benchmarking, business process reengineering, and best practices, and it also references a model that is intended to be an industry standard. SCOR model is one of the best models to describe supply chain activities in operations management for research and practice alike. There are radical chan...

In this paper, first, it is aimed to determine the most important criteria which affect the credit evaluation process. A type-2 trapezoidal fuzzy analytic hierarchy process method is proposed to analyze the criteria influencing the credit evaluation. Then, a ranking of experts is obtained using a type-2 trapezoidal fuzzy Electre (elimination and ch...

The petrol station location selection problem is taken into consideration in this study. In order to identify the main and sub-criteria for evaluation, the literature is reviewed and five experts from different companies are interviewed. After that, thirteen different alternative locations are for specified to evaluation. Then, the novel spherical...

Researchers work on facility location problems in different structures and solve them by developing different models over the years. In this study, we focus on the automated teller machine (ATM) site selection problem for a public bank in İstanbul. Twenty-five districts, which are located at the European side of İstanbul, are designated as ATM cand...

Her geçen gün önemi artan küreselleşme süreciyle birlikte dünyada teknoloji, ticaret ve iletişim alanlarında büyük gelişmeler görülmüştür. Bu gelişmeler, şirketlerin birbirleriyle daha rahat iletişim kurması ve ticaret yapabilmesini önemli ölçüde kolaylaştırmıştır. Şirketlerin birbirlerine bu derece yakınlaşması, ürünlerin(malların) güvenli ve daha...

Reusing of the wastewater has a vital importance because of limited natural water resources all around the world. Recycled wastewater can be used in many areas such as agriculture, industry, cleaning etc. Treatment of wastewater is one of the important tasks of metropolitan municipalities. Theaim of this study is to evaluate the performances of was...

In case of fire, the supplying of the water requirements of the fire area is a vital issue. The water requirements must be satisfied as quickly as possible without encountering any obstacles. In the study, once a terrorist attack which will cause fire at certain area (node) is occurred, the situation in which the terrorists want to prevent the fire...

In case of …re, the supplying of the water requirements of the …re area is a vital issue. The water requirements must be satis…ed as quickly as possible without encountering any obstacles. In the study, once a terrorist attack which will cause …re at certain area (node) is occurred, the situation in which the terrorists want to prevent the …re truc...

This paper defines and studies the multiple-sink shortest path problem (MS-NIP). The MS-NIP corresponds to many real-life problems relating to especially terrorist actions. In the MS-NIP, a network user seeks the shortest path to meet the demands of sink nodes while an interdictor aims to maximize the shortest path of a network user by interdicting...