Browsing by Author "Yetkin Ekren, Banu"

Now showing 1 - 5 of 5

Citation - WoS: 55
Citation - Scopus: 65
A multi-objective optimisation study for the design of an AVS/RS warehouse
(TAYLOR & FRANCIS LTD, 2021) Banu Yetkin Ekren; Yetkin Ekren, Banu; Ekren, Banu Yetkin
This paper deals with a hierarchical solution approach for multi-objective optimisation of an autonomous vehicle-based storage and retrieval system (AVS/RS) warehouse design. As a result of recent technological and Industry 4.0 developments industries tend to automise their facilities using systems such as AVS/RS an intra-logistics system mostly utilised by large distribution centres. Compared to a traditional crane-based automated storage and retrieval system (AS/RS) these systems are more advantageous for having a flexible travel pattern of autonomous vehicles enabling the designer vary the number of vehicles in the system based on the changed demand environment. Since it may affect the initial and operational costs as well as the system efficiency significantly it is important to decide on the right warehouse design at first for these systems. In this paper a multi-objective optimisation solution procedure under a hierarchical approach for the design of an AVS/RS by considering minimisation of two conflicting performance measures - average cycle time and average energy consumption per transaction - is presented. By this work it is also aimed to attract the attention of practitioners for the significance of multi-objective performance optimisation. For the multi-objective optimisation Pareto-optimal solutions are presented.
Citation - WoS: 12
Citation - Scopus: 10
Cost and performance comparison of tier-captive SBS/RS with a novel AVS/RS/ML
(Taylor and Francis Ltd., 2024) Banu Yetkin Yetkin Ekren; Tone Lerher; Melis Küçükyaşar; Boris Jerman; Yetkin Ekren, Banu; Jerman, Boris; Lerher, Tone; Küçükyaşar, Melis; Ekren, Banu Yetkin
This paper introduces a novel autonomous vehicle-based storage and retrieval system that utilizes movable lifts (AVS/RS/ML) proposed as an alternative to the tier-captive shuttle-based storage and retrieval system (SBS/RS). The newly proposed system aims to provide an affordable solution with highly utilised AGVs that can also perform operations out of warehouse. The performance of this novel system is compared with the equivalent tier-captive SBS/RS warehouse design where each shuttle is dedicated in a specific tier in that design. The comparison is based on the initial system investments costs throughput rates and average utilisation of lifts/MLs in the system. Collision prevention rules are also applied to AVS/RS/ML and its performance is tested through simulation. The results show that the tier-captive SBS/SR system becomes cost-efficient under high throughput rate requirements while the AVS/RS/ML technology is preferred for relatively moderate and low process rate requirements. The unit-cost per month performance metric of AVS/RS/ML is less sensitive to an increase in number of tiers in the system compared to the tier-captive SBS/RS case indicating that AVS/RS/ML may be promising for high-tier warehouse system designs. © 2024 Elsevier B.V. All rights reserved.
Citation - Scopus: 11
Energy efficient design of autonomous vehicle based storage and retrieval system
(Institut za Istrazivanja, 2017) Anıl Akpunar; Banu Yetkin Yetkin Ekren; Tone Lerher; Yetkin Ekren, Banu; Akpunar, Anil; Lerher, Tone
Autonomous warehousing is moving beyond traditional crane-based AS/RS technologies on the way to autonomous vehicle (AV) based AS/RS (AVS/RS) technologies. AVS/RS proposes substantial flexibility with respect to throughput capacity in the transfer of unit loads in high density storage areas due to having opportunity in changing the number of AVs in the system. Because of recent trend in ecological concern an efficient AVS/RS warehouse design should not only consider minimization of cycle time of a transaction to process but also consider the minimization of energy consumption in the system. In this study we explore energy minimum AVS/RS warehouse design providing maximum utilization of resources in the system. We consider rack design in terms of number of aisles tiers and bays as well as number of AVs as decision variables in the design and energy minimization as objective function. We completed 81 simulation experiments for different levels of those decision variables and provide the results via a histogram graph. © 2023 Elsevier B.V. All rights reserved.
Citation - WoS: 49
Citation - Scopus: 52
Graph-based solution for performance evaluation of shuttle-based storage and retrieval system
(TAYLOR & FRANCIS LTD, 2017) Banu Yetkin Ekren; Yetkin Ekren, Banu; Ekren, Banu Yetkin
The aim of this study is to provide a graph-based solution for performance evaluation of a new autonomous vehicle-based storage and retrieval system shuttle-based storage and retrieval system (SBS/RS) under various design concepts. By the graph-based solution it is aimed the decision-maker (i.e. warehouse manager) evaluates a pre-defined system's performance promptly and decides on the correct design concept based on his/her requirements from thousands of alternative design scenarios of SBS/RS. The design concepts include number of bays (NoB) aisles (NoA) and tiers (NoT) for the rack design and arrival rate of storage/retrieval (S/R) transactions to an aisle of the warehouse (AR). The performance of the system is evaluated in terms of average utilisation of lifts and average cycle time of S/R transactions. Simulation is utilised for the modelling purpose. Seven NoT seven NoB and six AR scenarios are considered in the experiments. Hence 294 experiments are completed to obtain the graphs. By this study to the best of our knowledge it is the first time a graph-based solution including comprehensive design concepts of SBS/RS is presented.
Citation - WoS: 15
Citation - Scopus: 18
Investigating the impact of COVID-19 on sustainable food supply chains
(EMERALD GROUP PUBLISHING LTD, 2023) Vikas Kumar; Banu Yetkin Ekren; Jiayan Wang; Bhavin Shah; Guilherme Francisco Frederico; Shah, Bhavin; Yetkin Ekren, Banu; Wang, Jiayan; Kumar, Vikas; Frederico, Guilherme Francisco; Ekren, Banu Yetkin
Purpose The ongoing pandemic has gravely affected different facets of society and economic trades worldwide. During the outbreak most manufacturing and service sectors were closed across the globe except for essential commodities such as food and medicines. Consequently recent literature has focused on studying supply chain resilience and sustainability in different pandemic contexts. This study aims to add to the existing literature by exploring the economic environmental and societal aspects affecting the food supply chain and assessing the impact of COVID-19 on food sustainability. Design/methodology/approach A survey method has been adopted with a questionnaire instrument investigating the role of technology government policies geopolitics and intermediaries on sustainable organisational management. A five-point Likert scale (i.e. 1 = strongly disagree, 5 = strongly agree) is used to evaluate the responses. The findings are based on 131 responses from entry-level workers and senior executives of different food supply chains across Asia and Europe. The data has been analysed to derive insights into the impacts of this pandemic. Findings The survey concludes with the significant impact of COVID-19 on the three pillars of sustainability i.e. economic social and environmental dimensions. The empirical analysis shows digitalisation and its applications help mitigate the negative effect of COVID-19 on sustainability. In addition the supportive government policies and intermediatory interventions were helpful in improving sustainability at each level. Research limitations/implications The findings have implications for businesses and policymakers. Companies can learn from the advantages of digitalisation to counter the challenges imposed by the pandemic or similar situations in the future in maintaining the sustainability of their supply chains. Managers can also learn the importance of effective organisational management in driving sustainability. Finally policymakers can devise policies to support businesses in adopting sustainable practices in their supply chains. Originality/value This study adds to the limited literature exploring the impact of COVID-19 on food supply chain sustainability through the triple bottom line lens. To the best of the authors' knowledge this is also one of the first empirical studies to examine the effect of technology government and organisational management practices on the sustainability of food supply chains.