OR in the industrial engineering of Industry 4.0: experiences from the Iberian Peninsula mirrored in CJOR

Industry 4.0 (I4.0) implies a group of technologies, organisational concepts and management principles to improve the performance of manufacturing companies or supply chains driven by production cost optimisation, mass customisation requirements, connectivity and digitisation of factories. The purpose of this paper is to relate Iberian Peninsula advances in I4.0 from Spanish and Portuguese research works published in CJOR papers. Hence this paper reviews the Spanish and Portuguese operations research (OR) and industrial engineering-based papers published in CJOR from 2011, when the I4.0 concept emerged, to the present-day. Here 47 papers are reviewed according to classification criteria based on the following elements: (1) objectives; (2) application context; (3) modelling approach; (4) development or software tool; (5) I4.0 technologies. The main outcomes, limitations and further research are also identified for recent papers. Finally, research trends and future directions in industrial engineering, OR and I4.0 are discussed.


Introduction
Industrial engineering studies are the branch of engineering studies concerned about the analysis, design, organisation and control of production and service systems. In these first studies, researchers work on the challenges of manufacturing plant analysis, designing and control by considering mostly the operating efficiency of human 1 3 resources and machines. These studies include these activities: production planning, organisation and control; quality statistics and control; inventory optimisation and warehouse design; equipment and maintenance; optimal plant layout and workstation design.
Operations research (OR) methods and models as applied mathematics lie in implementation areas in many disciplines, and also in industrial engineering. As a multidisciplinary applied science, it utilises algebra and optimisation, probability and statistics, analyses in real and transformed spaces which, in industrial engineering, have led to many new approaches; for example, machine learning and other methods. Today's industrial engineering challenges are more broadly spread but concentrate on productivity and all the technical problems of production management and control, as well as financial and general economic consequences. OR methods can be found in all kinds of the industrial organisation from manufacturing to distribution, transportation, other logistics, and services. Industrial engineers' duties are wide-ranging, from the design of single operations to that of the management and control of complete production, logistics and other service systems. Their systems not only involve physical issues but also integrate them into financial, general economic and environmental components. One important challenge is engineering solutions in benefit of human resources by designing their working places and combining their activities with collaborative robots, modernised workstations and others. Then there are ergonomic solutions for which OR methods and models are essential for organisations to make profits and provide workers with benefits.
In Spain, PhD programs oriented to industrial production and engineering with solid OR support are based mainly on previous Bachelor (Mula et al. 2012) and/or Master studies in Organization Engineering. There are currently 17 Master degrees in Spain in the engineering and architecture branch related to production, logistics and/or supply chain engineering. Four Polytechnic Universities offer seven of these Master's degrees: Polytechnic University of Cartagena (1), Polytechnic University of Madrid (2), Universitat Politècnica de Catalunya (2) and Universitat Politècnica de València (2). About ten main PhD programs that focus on industrial production and engineering are offered by Spanish universities. The Spanish Association for the Development of Organization Engineering (ADINGOR) is integrating and disseminating Organization Engineering knowledge through, among others, the annual International Conference on Industrial Engineering and Industrial Management (ICIEIM) or CIO (Congreso en Ingeniería de Organización) conferences, whose selected better results obtained since 2017 are published in CJOR special issues (Mula and Bogataj 2020). In Portugal, there are five main PhD programs about industrial engineering and OR methodologies: Industrial Engineering and Management (Aveiro); Leaders for Industrial Techniques (Lisbon); Industrial and Systems Engineering (Minho); Engineering and Industrial Management (Porto); and Advanced Engineering Systems for Industry (Minho). The overall objective of these Master's and PhD degrees is to train practitioners and researchers in advanced production engineering, logistics and supply chains by orienting their training toward company requirements or choosing a research itinerary. Advanced planning, programming and sequencing techniques are addressed in both an 1 3 OR in the industrial engineering of Industry 4.0: experiences… industrial and supply chain context. Supply and distribution logistics techniques, logistics and supply chain engineering, and their strategies, are also studied. Finally, process management, performance measurement systems, and modelling and simulation techniques for production, logistics and supply chain systems are investigated and applied.
Regarding the international development of industrial engineering and OR solutions, according to the Journal Citation Report 2019, the Engineering, Industrial scientific category, with 48 journals, has an aggregate impact factor of 3.893, while Operations Research & Management Science, with 83 journals, has one of 3.176. Here it is essential to highlight that 18 of 48 Industrial Engineering journals also belong to the Operations Research & Management Science category, which shows that the growth of both disciplines is closely related.
From an operations management perspective, Industry 4.0 (I4.0) is a connection of technologies, organisational concepts and management principles that underlies a cost-efficient, responsive, resilient and sustainable supply chain (Ivanov et al. 2020;Fortuny-Santos et al. 2020). The main enabling technologies for I4.0 development are: additive manufacturing, artificial intelligence and machine learning, autonomous vehicles and mobile robots, big data and data analytics, blockchain, cloud computing and cloud manufacturing, cyber-physical systems (CPS), cybersecurity, digital twins, Internet of Things (IoT) and Industrial Internet of Things (IIoT), optimisation, real-time communication, RFID, simulation, social media analytics and tracking and tracing systems (TTS). While I4.0 focuses on practice and research, Ivanov et al. (2020) argue that operations management studies in this area are not progressive enough. Therefore, with their paper, they intended to understand the current I4.0 research state in different disciplines and to gain insights and opportunities for future research in operations management. They provided a focused analysis to examine state of the art and learned about researchers' perspectives in I4.0 by offering a global survey on I4.0 topics with researchers in operations management, OR, industrial engineering and control and data science, which was presented at the 9th IFAC MIM 2019 conference, where the current state of knowledge and research opportunities for I4.0 was discussed.
OR and industrial engineering are two main research disciplines involved in I4.0, together with control, data science, mechanical engineering and supply chain operations management.  identify that the majority of research works published in the I4.0-based production management and engineering context centre on the production programming of flow workshops and supply chain planning. In this paper, we provide an overview of recent results from I4.0-based OR and industrial engineering applications carried out in the Iberian Peninsula and mirrored in CJOR articles. The main motivation is to identify current trends and new research to be conducted in Spain and Portugal in relation to industrial engineering, OR and I4.0.
The rest of the paper is organised as follows. Section 2 and Sect. 3 present a short literature review about Iberian Peninsula CJOR articles and relate them to I4.0 technologies. Section 4 discusses the main findings of the review. Section 5 presents the conclusions and further research.  (Lopez and Saboya 2009) and also discussing business technical efficiency matters (Garcia-Sanchez 2010). Additionally, the first CJOR papers from Portugal were more orientated to routing and location problems (Craveirinha et al. 2008;Dias et al. 2008) by presenting the proposal of a multiobjective routing optimisation framework for multiprotocol label switching (MPLS) networks and a capacitated dynamic location problem. Witte and Marques (2010) strike a balance between economies of scale and a sufficient number of remaining comparable utilities using DEA by comparing the efficiency of the drinking water sector in the Netherlands, England and Wales, Australia, Portugal and Belgium.
Since 2011, ideas about I4.0 are also reflected in some CJOR articles. During the 2011-2021 period, we identified 47 Spanish and Portuguese papers published in CJOR (Table 1). Table 2 provides a general review of the articles published during the 2011-2020 period, along with their modelling approaches and major outcomes. These papers have been reviewed and classified according to the following criteria: objectives of the paper; application context; modelling approach; software tool used; I4.0 technologies contributed.

Recent results toward Industry 4.0
The papers published in 2021 are mostly written on the bases of presentations at ICIEIM conferences before 2020 and further developed for CJOR. They were reviewed and classified according to the following criteria ( Table 3): objectives of the paper; research area; application context; research methodology and approach modelling; software tool used; I4.0 technologies contributed; major outcomes, limitations and further research, identified by the authors.
According to , I4.0 could lead to growth in industrialisation and disrupt the sustainability of existing manufacturing supply chains in terms of higher resource consumption, global warming, and climate change issues. Mula and Bogataj (2020)

Conclusion
This paper identified and reviewed the articles published in CJOR by authors from the Iberian Peninsula during the 2011-2021 period to relate their contributions to the advances and implementations of I4.0 technologies. Indeed the sustainable concept was especially contemplated. We reviewed 47 papers that have been classified in terms of objectives, application context, modelling approach, software tools, and I4.0 technologies contributed. For more recent articles (in 2021), major outcomes, limitations and further research were also identified. Papers from the 2011-2020 period contribute mainly to the state of the art of optimisation (13), simulation (10), data analytics (9), machine learning (4), big data (2), cooperative games for blockchain algorithms (2), optimisation simulation (1) and RFID (1). Papers from 2021 contribute mostly to optimisation (5), data analytics (5), simulation (4) and real-time communication (1).
It is essential to highlight that until 2021, the reviewed papers did not explicitly mention making contributions to I4.0 technologies. It was then when the benefits of digital transformation (Manresa et al. 2021) and a framework proposal to integrate I4.0 and lean thinking were addressed (Munoz-Villamizar et al. (2021). Sustainability should be covered in an integrated manner from its three perspectives: social, environmental, and economic . The sustainable concept is included in the reviewed papers from 2020, but mainly in relation to environmental aspects. In 2021, more papers contemplate sustainable thinking in their proposals from its three perspectives: social, environmental and economic. Nevertheless, more research that addresses industrial engineering problems by considering OR solutions under the sustainable I4.0 term umbrella is required.
Future research lines should centre on proposing, testing and validating sustainable I4.0 conceptual, analytical, simulation, and artificial intelligence models to enable I4.0 adoption by companies and to bridge the gap between I4.0 strategy and operational implementation. More software tools for I4.0 practical applications by business leaders and decision-makers are necessary. Finally, real-world validations of I4.0 implementations based on OR solutions would be welcomed, among others, that focus on additive manufacturing, autonomous vehicles and mobile robots, blockchain, cyber-physical systems (CPS), digital twins, Internet of Things (IoT) and Industrial Internet of Things (IIoT), social media analytics and tracking and tracing systems (TTS).