Real-time location systems selection by using a fuzzy MCDM approach: An application in humanitarian relief logistics

Highlights

• The RTLS technology selection and evaluation model is developed.

• The performances of the RTLS are compared and the most suitable one is determined.

• Interval-valued intuitionistic fuzzy sets have advantages to deal with fuzziness.

• The best RTLS technology is selected for humanitarian relief logistics.

Abstract

The real-time location systems (RTLSs) with different positioning technologies allow real-time and high-precision localization of assets. Since the usage of RTLSs technologies and their population increase, RTLSs technology selection problem that addresses many factors should be considered. Therefore, it is important to determine the performance criteria and evaluation of these technologies should be investigated before RTLSs technology is applied to the system. This paper aims to select the most appropriate RTLSs technology by using a combined fuzzy based decision-making approach. Thus, the first paper for selection of RTLSs systems in a holistic approach by combining benefit and risk factors has been revealed. The developed approach is applied to humanitarian relief logistics warehouse with four alternatives which are given as Ultra-Wide Band, Wi-Fi, UHF RFID and Active RFID for the selection. The proposed approach has been integrated with interval-valued intuitionistic fuzzy (IVIF) sets that allow to deal with fuzziness inherent in decision making processes. For this aim, firstly IVIF DEMATEL is used to determine the inner and outer dependencies of the sub and main criteria; secondly, weights of the sub-criteria are obtained by using IVIF ANP. Finally, the best RTLSs technology to be used in humanitarian logistics warehouse is selected by using IVIF TOPSIS. As a result of the calculations, the best system is determined as the “Wi-Fi RTLS” system based on the given context. By the way, a sensitivity analysis has been also implemented to test and validate the developed methodology.

Introduction

Many natural disasters have been experienced all over the world in natural formations or due to effects such as climate change, recently. In the past years, many disasters such as earthquakes, floods, and tsunami have led to ecological damage and huge losses. The concept of disaster is explained by the World Health Organization (WHO) as follows: damage, destruction, ecological degradation, loss of human life, human suffering and deterioration of health services, any event that imposes on a scale sufficient to guarantee an extraordinary response from outside the affected community or area. In general, earthquakes, hurricanes and floods among natural disasters have caused tremendous damage to communities [1]. In recent years, disasters have caused enormous repercussions, especially in developing countries, resulting in millions of deaths [2]. Despite the advances in science and technologies, thousands of people have been affected by natural disasters such as earthquakes, hurricanes, drought, volcanic eruptions, wildfires, floods, snowstorms and millions of dollars of habitat and property damage [3].

The humanitarian relief logistics (HRL) is defined as the systems and processes covering the assembly of people and goods, the collection of resources, technical opportunities and information to help the weak and vulnerable people who are affected from extraordinary situations and in need of help [4]. Natural disasters make the concept of human logistics a vital action instrument for disaster management and HRL is an important area that tries to reduce the negative consequences of natural disasters [1]. The most critical step in humanitarian logistics is to bring humanitarian relief needs (e.g. water, food, tents and medicines) from supply depots to disaster areas [5]. For this reason, it is crucial to establish a humanitarian logistics system which has ability to plan, organize, direct, direct, direct and control the necessary measures after the disaster since deficiencies and delays in a human logistics system can cause the suffering and pain of victims or their families [6], [7].

The real-time location systems known as RTLSs are the wireless technology solutions which have been increasingly used for different execution zones in every area with the aim of increasing the labor productivity and quality. With RTLSs, the employees and equipments are tracked, and the locations of products and materials are determined. Real time positioning and tracking of assets, people and workflows can be monitored by using RTLSs. Moreover, speed, ambient temperature, humidity can be controlled. Along with the rapid development of wireless communication technologies, it becomes possible to implement RTLSs in every area such as hospital, automotive, health, military, manufacturing, mining, and library. Alternative technologies can vary according to sector, environment, size of area to be tracked and equipment types. It is important to evaluate these technologies according to certain criteria. Because, the selected technology should be able to provide the best performance with minimum risk.

The mobile tag detects the location by sending signals to fixed tags within specific times and sends these locations to main server. The location information which is created by processing the location data collected in the server are processed with different algorithms and they are stored in the server for the reporting and visualization. Ultra-Wide Band, RFID, Wi-Fi, Zigbee, Bluetooth and Infrared are the most used RTLSs technologies in the different business segments due to the mentioned advantages [8]. The benefits provided by RTLSs technology to logistics industry are as follows [9]: (i) finding the products easily, (ii) tracking the locations of equipment, (iii) examining the distances covered by the products and parts, (iv) following up and improving the current work processes, and (v) increasing the occupational safety and tracking.

The redundant supply produces the wrong amount of supply and causes stock increase. The increasing stock may also cause various problems such as storage of stocks. The operation and successfully usage of the right RTLSs technologies have a critical importance since their effects in the area of safety together with decreasing the possibility of causing errors due to human factors in the humanitarian relief processes. The effective and efficient use of information plays a simultaneous role for decreasing the uncertainty, risk and waste [10].

The real time information acquired by using RTLSs enables the firms to ensure the improvement of processes underlying the HRL by increasing the quickness and coordination of their relief operations. The real time tracking of the products in the warehouse and achieving better coordination of the relief effort can be made by using RTLSs technology. The warehouse managers can instantly reach to accurate product information and quantity in the warehouses where the goods enter and exit continuously. Moreover, the theft issues can be prevented. All these properties can eliminate the cost issues of warehouse. In HRL warehouses, the perishable products which can be technical equipment, aid materials, foods, medicines, etc. are stored. The data such as ambient temperature and humidity are followed with sensors and thus, the deteriorations which may occur on the products can be prevented. In this way, the efficiency is increased while the operational and maintaining costs together with labor forces are decreased [11].

These systems which provide solution to problems and add value to firms by using in many sectors for various purposes can be specialized in the field of usage area. Therefore, many factors come to forefront in terms of the integration of a new RTLSs technology with the system. These factors should be taken into consideration for evaluation and comparison of RTLSs technologies. In this way, the best RTLSs technology can be integrated to the system. The selection and evaluation criteria of RTLSs should be considered as a multi-dimensional structure.

The benefits of using RTLSs have also been reviewed in the recent literature. Usually, RTLSs application areas are common in the health sector but applications in HRL are gaining importance nowadays. Some of studies are briefly summarized as follow:

Dong et al. [12] developed a feasibility study about misuse of personal protective equipment. An automated control system was designed by using RTLSs and virtual construction for tracking of workers’ location. Moreover, coordinates positions and determine situations whether a worker should wear helmet or not. Biswal et al. [13] considered humanitarian supply chain warehouse improvement by using RFID. Two scenarios were considered which are with and without RFID. Mathematical model was created to minimize total expected cost. Implementation of RFID in warehouse can prevent shrinkage recovery rate, errors and deprivation cost. Lanfranchi et al. [14] dealt with outdoor localization system. GPS position technology was used in humanitarian logistics operations for high risk regions and developed an alert system. Different scenarios were identified to test system. Yoo et al. [15] particularly concentrated on improving hospital efficiency and nursing workflow by using Bluetooth Low Energy/Wi-Fi in a tertiary care hospital. This study considered real case study and analyzed its experiences. Huang et al. [16] designed a holistic an approach based on of Radio Frequency Identification (RFID) and Ultra-Wide Band (UWB) to obtain real-time location information system. It can be concluded that developed RTLSs system improve system performance. Ozguven and Ozbay [17] used an inventory management system for emergency relief operations based on RFID system. When using tracking systems, flow of commodities, such as water, food and medicines could be monitored. Stochastic optimization model was applied based on RFID data. Oliveria et al. [18] used RFID and geofencing algorithms for tracking and tracing the system to reduce cost in cargo transportation and provide safety. Automatic delivery system could detect inconsistencies at real-time. Logistics flow could be monitored, delivery and pickups can be controlled so that optimized logistic flow could be obtained. Budak and Ustundag [8] considered selection of the appropriate RTLSs technology decision problem in healthcare sector. Three main criteria were defined namely economical, technical and implementation factors. Ozdamar and Ertem [19] made a survey about information system applications in humanitarian logistics and their mathematical applications. Lee et al. [20] applied a safety management system in Korea. It can be stated that developed tracking system can prevent construction accidents and a safety management system can be applied on other areas. Baulos and Berry [21] identified key factors of RTLSs deployment in healthcare systems, various applications and their benefits. Najera et al. [22] used UHF RFID for medical equipment tracking system. Curran et al. [23] evaluated indoor and outdoor location determination technologies and discuss their usage in different areas. Yang et al. [11] applied hybrid Zigbee RFID sensor system which are composed of “passive RFID reader as a sensor” and “active tag as a sensor” for humanitarian logistics center. The aim of their study was to have ability to track and monitor rescue equipment in HRL warehouse.

When analyzing literature about RTLSs and humanitarian logistics, it can be revealed that there is no study about performance measurement of RTLSs in HRL. Therefore, in this paper a holistic fuzzy approach which consists IVIF based DEMATEL, ANP, and TOPSIS methods is used to evaluate performance measurement of RTLSs in HRL. For this aim, five main criteria including benefit and cost factors are used and detailed hierarchy is created. Through that, the strategic advantages and risk factors of RTLSs are deeply analyzed by developed methodology.

RTLSs performance evaluation has a great importance for decision makers (DMs) in system performance improvements. The evaluation of the RTLSs performance in HRL can be considered as a MCDM problem. The aim of the fuzzy logic is to transform human’s decision making ability into a mathematical formula. It has the ability to reflect the vagueness, uncertainties and ambiguity in human beliefs and offers researchers to consider these characteristics into their methodologies. Thus, in this study, a fuzzy based decision making methodology has been used to overcome ambiguities of linguistic variables. In some situations, DMs cannot provide their expressions for alternatives in a certain degree and in such circumstances intuitionistic fuzzy sets (IFSs) can express judgments which DMs have a lack of judgment about their preferences appropriately. Since the IFSs consider both membership and non-membership functions of an element, they can successfully manage hesitancy and uncertainty in defining the corresponded mathematical representation of the judgements [24]. Since the RTLS performance evaluation usually involves imprecise and uncertain judgments and is a holistic approach to combine both benefits and risk factors, the applied methodology is extended with IFSs for representing the data accurately. Therefore, the proposed IFSs based MCDM method is capable of handling vagueness and conflicting nature of RTLSs evaluation. This study aims to propose a combined methodology consists of DEMATEL, ANP, and TOPSIS methods with their extended IFSs versions to evaluate RTLSs performance. Interval-valued intuitionistic fuzzy (IVIF) DEMATEL method is applied to find the inner and outer relations of the criteria. Through these relations, pairwise comparison matrices are constructed and merged to form limit super matrix by using IVIF ANP method for obtaining the weights of the sub-criteria. Finally, IVIF TOPSIS method is applied to measure and rank RTLSs performance and determine the most appropriate RTLSs.

This study focuses on identifying the performance criteria of RTLSs and evaluating the different RTLSs technologies. The proposed methodology is applied to the HRL warehouse. The performances of the RTLSs technologies are compared and the most suitable technology has been determined. In this way, application in HRL warehouse and sensitivity analysis show the applicability and robustness of the methodology. For this aim, the proposed approach is comprised of three phases. In Phase 1, criteria for assessing RTLSs performance evaluation are identified. In Phase 2, DMs are invited to provide linguistic evaluation ratings of the four RTLSs technologies by using identified criteria. The extended integrated methodology is applied for the evaluation of the alternatives. In Phase 3, for the interpretation of the results, sensitivity analysis and comparative analysis have been conducted and the obtained results are discussed.

The rest of the paper is organized as follows: In Section 2, a brief introduction related with the fuzzy sets is presented. In Section 3, the steps of the proposed methodology are detailed. In Section 4, the criteria and sub-criteria together with their definitions for RTLSs performance evaluation problem and the details of the application are presented. In Section 5, a sensitivity analysis based on the main criteria weights is conducted. In Section 6, a comparative analysis consists of two MCDM methodology is applied by using the same data set. The paper ends with the discussion about the obtained results and future research directions.