Geir Ringen
email: geir.ringen@ntnu.no

Frode Paalsrud

Eirin Lodgaard

Interorganizational learning in manufacturing networks

Keywords: Interorganizational Learning, Case Study, Industry 4.0

The ability to acquire and utilize new knowledge within an inter-organizational context is considered a key factor for gaining competitive advantage. This study aims at investigating how organizations do cross-border collaboration in the context of realizing Industry 4.0 principles at the operational level. The ever demand for advances in products, processes and systems, in a symbioses of product-and service performance, require new skills and knowledge at both organizational and inter-organizational level. This study investigates three case companies, and their maintenance departments, in order to understand if and how their role has changed in parallel with the adaption and implementation of Industry 4.0.

Introduction

Industry 4.0 is an area that has received great interest in the last decade, especially among scholars and scientists. The opportunities that industry 4.0 can bring for industries are seemed to be of great value in terms of efficiency based on improved decision support systems at the machine-human interface, HES, connectivity throughout the value chain, and maintenance operations [START_REF] Pereira | A review of the meanings and the implications of the Industry 4.0 concept[END_REF]. Industry 4.0 is predicted to significant impact product life cycles and product value chains, where increased digitization, automation and connectivity among companies in complex and comprehensive value chains will change the existing industrial collaboration platforms and how they operate and function. Additionally, it is anticipated that industries will become more flexible and effective in resource allocation. Traditionally, clusters are considered as a number of firms that share some key characteristics, and they may compete with each other where rivalry and competitiveness can be an important driver for innovation. Because of somewhat similarities in production capabilities performance benchmarking can enhance increased efficiency and competitiveness across the cluster as a whole [START_REF] Bathelt | Clusters and knowledge: local buzz, global pipelines and the process of knowledge creation[END_REF]. However, globalization, product diversity, shorter product life cycles, and sustainable measures increase complexity beyond traditional geographical and/or complementary clusters [START_REF] Aelker | Managing complexity in supply chains: A discussion of current approaches on the example of the semiconductor industry[END_REF].

The nature of networks and value chains is contextual according to type of market and industry. There can be dispersed and complex value chains, requiring many actors and processing steps, to manufacture the final product to global markets, and smaller and more local entities to serve market areas. Number of organizational interactions in combination with level of innovation according to product, process and system accumulates uncertainty. Thus, complexity in terms of unknowns and interdependent, non-linear factors that cannot be solved by existing methods, rules, systems and processes has to be managed [START_REF] Nason | It's Not Complicated: The Art and Science of Complexity in Business[END_REF].

In organizational learning, the word inter is adding a new dimension to learning. Interorganizational relations are "relatively enduring transactions, flows, and linkages that occur among or between an organization and one or more organizations in its environment" [START_REF] Oliver | Determinants of interorganizational relationships: Integration and future directions[END_REF]. This concept sheds new light on how knowledge and learning are located not only inside organizations, but also outside, where organizations are being part of a larger network of both social and material relationship. This sort of relations are set to cross organizational boundaries [START_REF] Mariotti | Exploring Interorganizational Learning: aReview of the Literature and FutureDirections[END_REF]. Despite different designation on the term interorganizational learning and its meaning, such as joint learning, horizontal learning, shared learning, relationship learning, network learning, they are applicable to project how learning and knowledge creation may form in value chains and networks. Selnes and Sallis [START_REF] Selnes | Promoting Relationship Learning[END_REF] defines relationship learning as: "a joint activity between a supplier and a customer in which the two parties share information, which is then jointly interpreted and integrated into shared relationship-domain specific memory that changes the range or likelihood of potential relationship-domain-specific behavior". Another view of interorganizational network is that these networks are created in order to share some sort of knowledge, and that an alliance of learning for developing dynamic capabilities is formed in which some will be learners and some will be teachers [START_REF] Oliveira | How can inter-organizational learning and dynamic managerial capability improve cluster performance? Clusters and Industrial Districts[END_REF].

Developing abilities to adapt methods and operations according to the changes that happens in company surroundings is considered an important asset for companies [START_REF] Howard | Procuring complex performance: studies of innovation in product-service management[END_REF]. In relationship learning, there are three sub-processes included; Information sharing, joint sense-making, and knowledge integration. Information sharing may act as the fundament for relationship learning [START_REF] Selnes | Promoting Relationship Learning[END_REF]. It is discovered that information sharing is central for work-relationships to function, and that information must be exchanged to make coordination and planning possible. This is believed to ultimately make operational efficiency possible. Secondly, it is believed that dialogue and communication is a key factor for common interpretation and sense-making among the participants in the relationship. This is especially important when considering how different organizations can be, and that there exist clear differences on how new information are being interpreted and made sense of. This paper addresses the following research question: How can interorganizational learning enhance Industry 4.0 realization and operational effectiveness?

Method

A qualitative research approach is typically used to discover new insights on a topic or area where there is little information available. Some possible advantages of conducting a qualitative research is that one can reveal new insights in areas that have received relatively little research, and it can help understand complexities, situations, processes, relationships, systems or people. In qualitative research it is easier to test the validity of certain assumptions, claims, theories, or generalizations in a real-world context, and it can help bring forward new information to verify, develop and improve concepts or theories on a phenomenon. For instance the theory of informal collaboration in geographical clusters [START_REF] Dahl | Knowledge flows through informal contacts in industrial clusters: myth or reality?[END_REF] is an assumption to be tested by the proposed method. Within a certain area, qualitative research can help reveal obstacles and problems that may exist, as well as giving the opportunity to evaluate the effectivity of certain practices [START_REF] Leedy | Practical Research: Planning and Design[END_REF]. To help answer the research question in this study, there have been conducted semi-structured interviews of operators and managers in three different case companies within a defined industrial cluster. The organizational level of interest is the maintenance department. This selection is made by hypothesizing that maintenance departments are central in the transition towards an Industry 4.0 state. All three organizations are well established manufacturing companies in the medium size segment, mainly exporting goods and product out of Norway.

The data gathering aimed at receiving insight and information within the defined topic and scope of this study from a practical real-world perspective. The interview guide was constructed in way that it should be executed in the same fashion for all respondents, letting the interviewee describe, explain and share their thoughts, knowledge and understanding, based on their own interpretations and views on the field of study was an important part of the research. By asking open questions and allow for individual interpretation and understanding to be highly evident, there was believed that new, interesting and objective data could be revealed. Despite having a structured, or semi-structured interview guide prepared, the interviews tended to be conversation about their practices, understanding and insight on the topic, which is often desired in such scenarios. The companies, respondents and their answers will be kept anonymous and neutral in this article.

The interview guide consists of the three parts: introduction, key-questions and additional questions. The main part, key questions, is supported by 15 questions, where the objective is asked about frequency of interaction, type of interaction, importance of interaction, relevance of interaction, roles (and equality) in interaction, content and scope for interaction, barriers/enablers in interaction, how knowledge is developed, shared and integrated, evolution of interaction and your role in influencing knowledge networks.

Critics to this method and approach is that the sample size is small and not necessarily representative of the broader population. Thus, generalization is difficultand it is difficult to tell how far the findings are biased by the researcher's own opinions and the way the interviews where conducted.

Results

Case A

Results from the interviews at case company A demonstrates low degree of interorganizational learning, at least in an organized and formal manner. In the maintenance and manufacturing departments, there are considered to be a low degree of interaction with other maintenance departments across the industrial cluster. But there exists informal interaction in terms of informal meetings between workers that have some sort of personal relations with other workers in the cluster. These connections stem from the fact that people in the past has been colleagues in the same company or that they are sharing hobbies and/or neighborhood. There are considered to exist some sort of exchange in experience and knowledge at this level, but because of the degree of informality it is categorized as transfer of tacit knowledge. The workers confirm that they do seek other industries to gain new insight and to understand how other practices unfold due to change in technology. Their supplier base is also reported as a valuable source of information, where frequent, planned or un-planned meetings with suppliers due to particular issues or fixed service schedules increase the bandwidth to externals. The interviewee points out that being a part of regional industrial cluster has been a decisive factor for their ability to develop and grow the business in recent years. Access to local competence, personnel, personnel rotation, and equipment are just a few decisive contributions for this development. The department also reports that they in the future will work more pro-actively towards the outside world, particularly in making spare parts available for others through open digital systems.

Case B

The same tendency seems to apply to case company B, where little organized interaction with other companies and maintenance departments, inside and outside the industrial cluster, is reported. The limited number of relations that exist between the companies is said to be an important factor for the limitations in communication. They claim that relationships were stronger before, but now diluted because of the changed nature of the cluster in terms of number of companies, core products and changes in the resource pool of the different companies. The cluster has evolved from one relatively big cornerstone company towards more than 40 separate companies targeting different segments and markets. This journey has taken 20-30 years, so ties and bonds exist between those employees that has been part of the described transition. There is reported no formal structure for interacting with other firms, and the perceived busy work mode leaves little room for interacting with others. The highest ranked type of outside interaction is with their suppliers. High degree of learning and knowledge-creation is reported to happen at the intersections with their existing suppliers of core technology for manufacturing of their products. Case company B asserts that they are continuously leveraging their technology, and they make regular investments and replacements to improve their maintenance performance. Investments in robots, control systems, machinery and equipment are about many technological investments that are made recently. Frequent interaction and communication with suppliers are central in this technological evolution. This source of information guides decisions with regards to Industry 4.0 based on insights and common understanding on how new technology can improve manufacturing capability. Supplier meetings are regarded as learning sessions, where as many as possible of the maintenance workers are involved to create a common understanding and baseline for further learning.

Case C

Case company C reports in general that learning processes are internally focused due to the long term systematic continuous improvement program going on. Improving existing capacities and capabilities have been the focal point for some time, impacting how internal knowledge creation, sharing and realization is organized through leanprinciples. The reasoning by this operational strategy is reported to be rooted in a combined need for cost-cutting as well as producing at high capacity utilization. Perceived daily intensity to maintain and operate critical equipment for producing the demanded quantity is said to limit communication with other organizations. High utilization of human and technological capabilities is argued to reduce their ability to engage in learning activities related to new technologies possible available in the cluster and value chain. This "constant" situation makes interorganizational learning unpractically and difficult. Competing from a defined high-cost country, and numerous lean programs, leaves no free capacity to educational activities or learning from neighboring companies. The growing dynamic of the industrial cluster is also said to be a barrier for interorganizational level, because it requires a lot of effort to keep updated on what the others do. Some years ago, there were closer bonds between the firms, and the interpersonal connections were more frequent. This led to a situation where the threshold for interacting outside the firm was lower, and it was also in some cases more necessary and practically needed, because the industrial cluster was more homogenous. Despite the lack of organized inter-organizational learning, there are to some extent reported interaction and learning from the supplier base. Especially new investments and implementation of new technologies spur curiosity and knowledge creation and sharing within the company as well as between the company and the particular suppliers. Case C is also part of large international company, getting impulses from sister plants in the global production network.

Discussion and conclusion

Learning and knowledge creation is considered as a difficult and fuzzy domain, hard to express, measure and manage. This is often the situation at organizational level, so how can we approach it from an inter-organizational learning perspective. It is claimed that the latter perspective is becoming more and more important as technology and organizations increase its complexity. Increasing number of materials, product interfaces, ICT implementations, service contents, sustainability criteria, suppliers and collaboratorsall adds uncertainties and thus complexity to the manufacturing system. In interorganizational learning, where learning across firms intends to reduce level of uncertainty, there is expected that organizations in value chains adapt and change accordingly. Learning across firms can help organizations increase their capabilities and capacities in order to innovate faster at product, process and system level. A general advice towards establishing inter-organizational learning among organizations is that strengths, weaknesses, challenges and opportunities among the actors should be defined. Defining focus areas and clear goals are recommended to create efficient and trustful interorganizational networks, where rules and practices for all the organizations to follow can help make shared knowledge-creation and sharing less challenging. Creating a high degree of synergy and interdependency should also be sought of, additionally, investigating what kind of knowledge is needed both internally and externally.

Collaboration platforms for interorganizational learning in the maintenance department in the three manufacturing companies can be divided into the regional cluster, supplier base and international production network. For the former, informal and irregular interactions is reported, where tacitness is the common learning mode, and where frequency and number of connections are declining due to cluster evolution. The reasons are plentiful -from scarcity of resources to be allocated to external activity, to limited information about what their neighbors do, and that sufficient information is to be found at other sources as for instance through their supplier base or sister plants. The strongest inter-organizational learning platform is the supplier base. Here, frequency, number of contact points, formality and insights with regards to Industry 4.0 are common parameters among all three case companies. All companies say they want to increase their number of interactions with externals at all collaboration platforms, believing that the way forward is about combining formal vs informal work modes in relations to other companies in clusters and value chains to keep up the technological phase. All three case companies particularly claim to have too little formal interaction with their neighbors in the defined regional industrial cluster, a potential low-hanging fruit to increase their learning component.

The future maintenance departments as an inter-organizational learning node must comply to the criteria; awareness and understanding of system interconnections in their near and distant proximity, cause-and effect understanding upon process and product development internal and external, overview of expanding areas of generic technology developments, improved skills to become better problem-solvers with a more holistic perspective.

Interacting with organizations that are different, or contrasting, can foster new ways of approaching challenges and questions. New insight from heterogeneous organizations can help develop entirely new work modes and practices. Contrasting and diverse knowledge can be also be acquired. This can bring new and unique ideas to the organization, which can be combined with the existing base of experience and knowledge, creating a potential for generating new ways of exploiting learning situations. However, our findings somehow support a study by Holmqvist that interorganizational learning is similar to intraorganizational learning, where differences in learning conditions seem to depend upon degree of collaboration rather than the kind of collaboration [START_REF] Holmqvist | Intra-and interorganisational learning processes: an empirical comparison[END_REF]. The study gives practical advice to companies about awareness of interorganizational learning on parameters such as sources, frequency, role, value, relevance. This can be viewed in accordance with for instance a study by Gibb et al, claiming a situated learning approach along the dimensions "learning to perform" and "learning to compete" [START_REF] Gibb | Network learning: Episodes of interorganizational learning towards a collective performance goal[END_REF]. In such, awareness is stage one towards utilization of the learning in products, processes and systems that increase competitiveness of the firm. Some general considerations on interorganizational learning is that it can help increase the resource management in the value chain. Thus, interorganizational learning can contribute to release resources, it can help understanding where resources are

originated, how they should be utilized, and how practices can be learned, shared and implemented.


Solimar Garcia
email: solimar.garcia@docente.unip.br

Irenilza De

Alencar Naas

Pedro Oliveira

Costa Neto

Valdice João Reis

Neves Pólvora

Luiz Lima

Angel Martinez

Vanessa Santos Lessa

Garcia Solimar

Alencar Nääs

Pedro Luiz De Oliveira

João Gilberto Mendes Dos Reis

Valdice Neves Pólvora

Antonio Luiz

De Lima

Angel Antonio Gonzalez Martinez

Sustainability in Fabric Chains and Garments for a Circular Economy

Keywords: Textile residue, waste textile, reverse logistics

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Society, in general, seeks new forms of development, which contributes to reducing and limiting the use of natural resources, contemplating three pillars of sustainability, or the triple bottom line (TBL): profit, environment, and society, proposed by Elkington in 1997 [START_REF] Elkington | Enter the Triple Bottom Line. Chapter 1. Cannibals with Forks: The Triple Bottom Line of 21st Century Business[END_REF], with the maintaining of the natural resources, and seek activities that can lead to a circular economy in advances of industry 4.0.

In Brazil, the National Solid Waste Policy (PNRS), introduced by Law No. 12.305/2010, led to responsibility for the proper disposal of waste to companies [START_REF]Low n.º 12[END_REF] and implemented reverse logistics for some segments, including agrochemicals, tires, and batteries. The daily production of garbage is estimated at 10 million tons, two billion tons per year [32]. Brazilians produced 215,000 t/day of waste [5]. Data from 2018 show that the damage reaches US$ 40 billion per year, with recycling reaching only 3% of the 80 million tons of annual wastes [START_REF] Boehm | Brasil perde R$ 5,7 bilhões por ano ao não reciclar resíduos plásticos. Brazil loses R $ 5.7 billion a year by not recycling plastic waste[END_REF].

On the other hand, one of the largest generators of waste and environmental pollution is the textile and garment chain. In the world, textile production, cotton or synthetic, moves US $ 797 billion [START_REF] Amaral | Industrial textile recycling and reuse in Brazil: case study and considerations concerning the circular economy[END_REF]. The fabrics and apparel textile industry as an essential segment in the Brazilian economy, which is amongst the five most significant in the world, and produced US$ 48 billion in 2019, representing 8% of the Brazilian GDP [START_REF] Abit | Brazilian Association of the Textile and Clothing Industry. Profile of the textile and clothing sector[END_REF].

The destination of waste from the textile and clothing industry is part of the complexity and difficulty of bringing sustainability to the supply chain. In Brazil, these numbers are diffuse, and no agency has specific information on reuse and recycling of textiles [START_REF] Zonatti | 37 Recycling of waste from the textile and clothing sector in Brazil: overview and related actions[END_REF]. This waste is considered with the total number of urban waste in Brazilian standard NBR 10.004 [START_REF] Abnt | Associação Brasileira de Normas Técnicas[END_REF].

In addition to the chemicals used in textile production, there is also the aggravating factor of fast fashion, these low prices products, which generate excessive consumption and waste. The reuse of textile waste and discarded clothing can reduce the negative impact on the textile chain; however, reverse logistics is still insipient in the segment. It is also necessary to recycle and reuse fabrics in the production phase or collection of clothes discarded by the consumer, since the disposal is done incorrectly and without care for the environment.

There is no information about the waste generated by the disposal of clothes done by the final consumer, and that can be recycled. The recycling and reuse industry, part of reverse logistics and the circular economy, can generate 1.8 trillion euros by 2030 [START_REF] Mckinsey | Europe's circular economy opportunity[END_REF].

There are still few companies that work with the recycling of fabrics, reuse of production residues, and discarded clothes. These activities are carried out by handicraft and charity initiatives, which involve an inexpressive result. Indeed, Brazil imports fabric waste, because the recycling does not have the quality to be used for the companies of that segment.

Therefore, the research question is: how to bring sustainability to the textile chain and put it on the path of the circular economy, being the objective of this article to discuss recycling and reverse logistics as a driving to circular economy.

Background

Reverse logistics is one of the most critical factors for economic and social growth and can be supported for innovation and sustainability [START_REF] Castaño | Innovation, internalization and business-growth expectations among entrepreneurs in the services sector[END_REF]. The knowledge of consumer behavior it is a be there are as a path in the search for textile sustainability [START_REF] Garcia | The sustainability awareness of Brazilian consumers of cotton clothing[END_REF]. Consumers, on the other hand, demand the sustainability of the companies and their products [START_REF] Valenzuela-Venegas | Sustainability indicators for the assessment of eco-industrial parks: classification and criteria for selection[END_REF].

The Brazilian Association of Technical Standards defines the rejects of domestic and commercial activity in urban centers, which including clothes in brazilian standard NBR 10.004 [START_REF] Abnt | Associação Brasileira de Normas Técnicas[END_REF]. The textile waste and the used clothing are discarged with other types recycled waste.

In Brazil and all countries, there is the same difficulty in treating waste textiles. France has a national tissue recovery program whose policy has held the waste producer for fabric, clothing, and footwear producers since 2017 [START_REF] Bukhari | Developing a national programme for textiles and clothing recovery[END_REF][START_REF]Resource Productivity in the G8 and the OECD. A Report in the Framework of the Kobe 3R Action Plan[END_REF]. In Brazil, this prerogative is still under discussion, as an addendum to Law No. 12.305/2010 [START_REF]Low n.º 12[END_REF].

The use of second-hand clothing can reduce greenhouse gas emissions by 53%, pollution, and chemical production processes by 45% [START_REF] Ecosign | Textile recycling as a contribution to circular economy and production waste enhancement[END_REF]. Recycling and reuse contribute to reducing the exploitation of natural resources to produce new products [START_REF] Abramovay | An agreement for the circular economy[END_REF][START_REF] Castro | Innovation in the fashion industry: the contributions of Marxist theory to the fashion universe[END_REF].

Despite this, the country cannot properly recycle and reuse its waste and needs to import textile waste [START_REF] Amaral | Industrial textile recycling and reuse in Brazil: case study and considerations concerning the circular economy[END_REF]. In 2013, Brazilian recyclers imported nearly 10,000 tons of textile waste, more than $ 11 million, and attributed this to people's lack of information and unorganized waste collection [START_REF] Amaral | A national solid waste policy and reverse logistics in the national textile and clothing sector. 2nd Textile and Fashion Scientific Congress[END_REF]. [START_REF] Garcia | Reverse Logistics and Waste in the Textile and Clothing Production Chain in Brazil[END_REF] show that these imports between 2013 and 2018 were 74,000 tonnes and a loss of US $ 42 million.

[24] attributed to Brazil a loss of US$ 600 million for not recycling and improving the working conditions of the cooperatives of waste pickers, the main responsible for this work in the country, and running without any governmental support.

The increase in waste use rates positively affects the performance of sustainability indicators but depends on awareness, as observed by [START_REF] Heidari | Sustainable design of a municipal solid waste management system considering waste separators: A realworld application[END_REF]. A lack of recycling culture and higher costs of removal, transportation, and logistics has been found by [START_REF] Zonatti | 37 Recycling of waste from the textile and clothing sector in Brazil: overview and related actions[END_REF]. This behavior associated with a lack of tax incentives is an aggravating factor for the implementation of reverse logistics.

Methods

To discuss this subject, we analyzed the results found in Garcia [START_REF] Garcia | The sustainability awareness of Brazilian consumers of cotton clothing[END_REF][START_REF] Garcia | Reverse Logistics and Waste in the Textile and Clothing Production Chain in Brazil[END_REF][START_REF] Garcia | Disorganization of the reverse logistics and recycling of textile waste delay advances in the Brazilian circular economy[END_REF], also using the information published in the current literature about sustainability in the textile chain.

These previous studies were based on data mining and government data related to the output of the fabric and clothes processing supply chain, as well as the way consumers face recycling old garments.

Results and Discussion

Brazilian consumers' awareness of sustainability about cotton clothing was identified by [START_REF] Garcia | The sustainability awareness of Brazilian consumers of cotton clothing[END_REF] using data mining. The dissemination of a more sustainable lifestyle, with healthier habits, can contribute to the reduction of the carbon footprint, ecological footprint, and sustainability of the planet [START_REF] Garcia | The sustainability awareness of Brazilian consumers of cotton clothing[END_REF][START_REF]Questionaire to calculate the index in Brazil[END_REF].

When dealing with solutions that affect not only the citizen but big companies, and the whole of society, change of paradigm is challenging to implement [START_REF] Boströom | Introducing the sustainability challenge of textiles and clothing[END_REF]. It is likely that at some point, it will be necessary that both companies and consumers, be forced to change their choices and use. The influence of policies applied to sustainability on political and citizen attitudes was assessed by [START_REF] Xu | An account of the textile waste policy in China (1991 -2017)[END_REF], and the authors noted that such changes might not be suitable to organize this sector Garcia [START_REF] Garcia | The sustainability awareness of Brazilian consumers of cotton clothing[END_REF] show that the reduction in the use of vehicles, changes in diet, and in the way of buying clothes can impact sustainability. These habits can make people more aware to avoid excessive purchasing of unnecessary clothes and other items produced by fast fashion. It was also evidenced that the income and the value consumed in clothes interfere in the sustainable behavior of the surveyed Brazilians, although the results is suitable for the textile chain, the result cannot be expanded to other segments of the population, as the sample of respondents was restricted and limited to high income and education levels.

Garcia [START_REF] Garcia | Reverse Logistics and Waste in the Textile and Clothing Production Chain in Brazil[END_REF] provide an overview of the reverse logistics and disposal of the fabrics in the production chain of clothes in Brazil, country that only 3% of the waste generated is recycled. According to calculations by Brazilian Association of Public Cleaning and Special Waste Companies (Abrelpe), about 45 million tons of waste that could be recycled, and be not, could yield about US$ 750 million a year to the country [5].

Fabric companies must import waste from other countries [START_REF] Garcia | Reverse Logistics and Waste in the Textile and Clothing Production Chain in Brazil[END_REF], disregarding the potential for generating income and sustainable businesses that result in this investment because the population does not know about recycling of this waste. Brazilians are not trained about the selective collection (66%), and 39% do not separate organic waste from recyclable waste [START_REF] Gama | Research shows that Brazilians know little about collection and recycling[END_REF].

The recycling and reverse logistics performed by the textile and clothing industry in Brazil, based on the National Solid Waste Policy (PNRS) and Brazilian legislation, has been studied by [START_REF] Garcia | Disorganization of the reverse logistics and recycling of textile waste delay advances in the Brazilian circular economy[END_REF]. It was found that companies are not responsible for the final destination of their products, which occurs only in some industrial sectors such as tires, lubricating oils, and pesticide packaging [START_REF]Low n.º 12[END_REF].

The Brazilian Association of Public Cleaning and Special Waste Companies [5] attributed a possible loss to the country of approximately US$ 30 billion per year for not recycling products that could be recycled, but are otherwise wasted.

The country is the largest in the European Union with 67 million inhabitants, France and it aims to recover 50% of the production of annual solid waste. Such anti-action represents a recovery of 300,000 tonnes, or 4.6 kg per person, over the total sold in clothing, bedding and sneakers [START_REF]Circular economy in practice -reducing textile waste[END_REF]. Zonatti [37] reports that of the 175 thousand tons of solid textile waste generated in Brazil, about 90% were incorrectly discarded. A clothing cluster in the outskirts of São Paulo houses around 1200 companies that produce 12 tons of textile waste per day, about 2% of the country's total, estimated at 175,000 tons/year. Of these, 36,000 are reused in the production of blankets, twine, new clothes, and yarns [START_REF] Freire | Implications of the National Solid Waste Policy for waste management practices in the clothing industry[END_REF]. According to [START_REF] Lorenzetti | The Importance of Reusing Textile Waste in São Paulo. A Importância do Reaproveitamento de Resíduos Têxteis em São Paulo[END_REF], this number considers the loss of 10% of the cutting process, of which recyclers reprocess 70,000 tons (40%), and 60% go to landfills and dumps. [START_REF] Campos | Textile waste, raw material that generates income[END_REF] estimate approximately 10% of the textile production in waste with an inadequate final destination.

The actions carried out for the recycling and reuse of textiles, all over the world, point to charitable activities [START_REF] Leal Filho | An overview of the problems posed by plastic products and the role of extended producer responsibility in Europe[END_REF]. [START_REF] Bianchi | Sell, give away, or donate: an exploratory stu of fashion clothing disposal behaviour in two countries[END_REF] show that the clothing banks of charities provide directly to the recycling companies. In the United Kingdom, the collection of textile waste is done by charitable organizations that resell in their stores, and surplus stocks are sold to recycling companies [START_REF] Kim | A case study comparing textile recycling systems of Korea and the UK to promote sustainability[END_REF].

In Brazil, collectors of recyclable material, live in poverty and are integrated into cooperatives or associations with the support of local governments [START_REF] Baruque-Ramos | Social and economic importance of textile reuse and recycling in Brazil[END_REF][START_REF] Leal Filho | An overview of the problems posed by plastic products and the role of extended producer responsibility in Europe[END_REF]. The waste collection of fabrics and clothing is just a charity activity in Brazil and has no government support [START_REF] Garcia | Disorganization of the reverse logistics and recycling of textile waste delay advances in the Brazilian circular economy[END_REF].

Currently, 60% more clothes are consumed than 15 years ago. These clothes are kept in the consumer closet for half of their useful life, and a third of them are discarded in after a year. Responsible for 8% to 10% of global greenhouse gas emissions, the fashion industry pollutes more than combined air and sea transport [33].

Final remarks

The discussion in search of appropriate governmental policy is an emergency. The scenario is even worse in developing countries due to the lack of structure for recycling and reuse, and the absence of environmental awareness of the general public. When studying the implications of investment in innovation for a textile and clothing chain and its relationship to the circular economy, legislation, and practices, we confirm that are small-scale and handicraft activities that require government support for advances. The National Solid Waste Policy, with action plans for the implementation of reverse logistics in various industrial sectors, has been under discussion at the Brazilian Congress since 2011, without any concrete results. The support of the responsible authorities must also reach the collectors, with adequate legislation to regulate people's working conditions and quality of life. Such activities are highly harmful and challenging for waste workers.

Acknowledgment:

The authors wish to thank the Paulista University, CAPES, and CNPQ.


Danijela Lalić
email: danijelalalic@uns.ac.rs

Bojana Milić

Virtual and Augmented reality as a digital support to HR systems in production management

Keywords: VR and AR technologies, human resource management, production management

Digital transformation has disrupted every domain of production management, as well as the human resource management as one of the production manager's most important responsibilities. Besides of product and process design and issues involving planning and control of quality and capacity, production management also includes responsibility for organization and supervision of the workforce. In new industry operations, it is important to anticipate human resource requirements, as well as to translate them into recruiting and training programs in order to develop a base of highly skilled and qualified workers capacitated for installed machinery and equipment. According to the relevant literature review, integration of virtual and augmented reality technology in any business process has a proven potential for employee engagement improvement and memory retention capacity. The aim of this research is to provide a comprehensive summary of using VR and AR technologies as a digital support for managing human elements in operating systems. This study found that VR and AR can be successfully used in improving workers' productivity, enhancing employee training, reducing costs, making worksites safer and closing the skills gap more effectively and efficiently. This study could encourage both academics and practitioners to seek innovative use of VR and AR technologies in a particular industry as digital tools that saves time and costs in human resource management.

Introduction

Combining different digital technologies with production and business processes represent one of the pillars of industry 4.0. In order to support digital transformation initiatives, many industries adapt a technology-driven approach in their function and activities, by creating "smart" working environment within production system [START_REF] Crnjac | From Concept to the Introduction of Industry 4.0[END_REF].

In order to overcome the shortage of fit workforce, long-time adaptation and defective work, production systems are taking advantages of technologies to better recruit and preserve new employees. Engineers and technicians of the 21 st century must be equipped with highly advanced skills in their function area and they must be sharp in process fault diagnosis and decision making. Human resource systems are responsible for recruiting, developing and managing of skillful labor force, and those systems need a digital support in order to keep production and other operational activities running with minimal disruption. Each year, Gartner identifies the "Top 10 Strategic Technology Trends" and some of the key trends published for 2019 are related to autonomous things, augmented analytics, immersive experience etc. This research [START_REF] Gartner | Gartner Identifies the Top 10 Strategic Technology Trends for[END_REF], for example highlights the fact that AR technologies will be embedded in enterprise application (eg. HR, sales, marketing function etc.) in order to optimize the decisions and actions of all employees within their context. In addition, Gartner has presented the latest technological innovations that are transforming HRM: VR and AR application in corporate learning, learning experience platforms, VR assistants in human capital management, AI in talent acquisition, employee experience tech, VR recruiting assistants and so forth. [START_REF] Gartner | Hype Cycle for Human Capital Management Technology[END_REF].

The purpose of this paper is to analyze the current state of implementation of virtual and augmented reality in a field of human resource management in production systems. The research focus is to review the literature in Directory of Open Access Journals (DOAJ) and provide a comprehensive summary of potential opportunities of VR and AR technologies as a digital support for managing human elements in operating systems.

Theoretical and conceptual perspectives

Digital technologies have transformed every domain of production management: planning and production approaches, business development models, use of technologies, shifts in traditional operational tools and processes etc. As one of the strategic fields in production management, human resource management (HRM) is also experiencing a digital transformation in its working approach. This section highlights the importance of human resource in production management as well as the importance of virtual and augmented reality in modern industry.

The importance of human resource in production management

The multidimensional and fundamentally disruptive character of change causes problems in maintaining the characteristics of workflows and structures in production systems [START_REF] Ćosić | Proizvodni menadžment[END_REF]. The increasing intensity of technological shifts necessitates finding a solution that will provide the ability to adapt the structures of the company and thus mitigate the effects of change.The production manager must plan and control the process of production so that it moves smoothly at the required level of output while meeting cost and quality objectives [START_REF]Production management: industrial engineering[END_REF].

A more than century-old theory of work measurement and time study introduced by Taylor and the Gilbreth's, still have an application in today's fast-paced, technology-driven world. In his publications on production management, Taylor set the scene for developments in many business functions and disciplines including human re-sources [START_REF] Taylor | The Principles of Scientific Management[END_REF]. One of the Taylor's most important contributions are incentive systems for motivation and rewarding high levels of worker output, as well as the identification of new functions for managers relating to the selection and training of new employees [START_REF] Tracey | Human Resources Management & Development Handbook[END_REF][START_REF] Myers | One hundred years later: What would Frederick W. Taylor say[END_REF]. These HRM tendencies are still relevant and ongoing. According to Beatty and Schneier [START_REF] Beatty | New HR roles to impact organizational performance: From "partners" to "players[END_REF], the main areas of strategic choices in HRM are: work design, performance measures, selection, development, rewards and communication. Therefore, HRM is linked to strategic choices of quality, flexibility, investment and cost reduction by the use of a functional and performance approach [START_REF] Pasupa | Impact of work-sharing on the performance of production line with heterogeneous workers[END_REF][START_REF] Korobaničová | Human Capital Investment: Practices and Measurement In Slovak Enterprises[END_REF], which means that manufacturing strategy and production management are usually related to performance appraisal, work design, career management, training and development etc. Today's biggest challenge to HR profession is to learn more about the effective application and appropriate use of new technologies in order to improve their working processes [START_REF] Swanson | Foundations of human resoruce development[END_REF].

The usage of Virtual and Augmented reality

There are many scenarios of industrial application of VR and AR solutions, from visualization of prototype technology components to the complex development of interactive workshops for personnel at hazardous industries [START_REF] Zhao | Sustainability and digitalization of corporate management based on Augmented/Virtual Reality tools usage: China and other world IT companies' Experience[END_REF].

Virtual reality (VR) represents a three-dimensional computer simulation of real world environments that can be explored and interacted through a person [START_REF] Ahmed | A review on using opportunities of augmented reality and virtual reality in construction project maagement[END_REF]. These simulations are interactive and are capable of responding to user inputs making it interactive in real time [START_REF] Burdea | Virtual reality technology[END_REF]. The VR is the computer-generated simulation of a threedimensional image or environment that may be interacted within an apparently real or physical manner by a person with the use of a special digital system, which includes a helmet with a display screen inside or gloves outfitted with sensors [START_REF] Whyte | Industrial applications of virtual reality in architecture and construction[END_REF].

Unlike virtual reality, augmented reality (AR) implements fragments of virtual reality and incorporates them into real world. Using technology it aligns real and virtual objects while running interactively in real-time [START_REF] Van Krevelen | A survey of augmented reality technologies, applications and limitations[END_REF]. Augmented reality (AR) stocks the same concept, but in place of interacting in a nonexistent surrounding (digital fact), AR makes use of the existing environment at the same time as implementing virtual elements to appear as if both are together at the same time [START_REF] Dunleavy | Augmented reality teaching and learning[END_REF]. AR is a kind of interactive, reality-based display environment that takes the capabilities of computer-generated display, sound, textual content and effects to enhance the user's realworld experience [START_REF] Loijens | What is augmented reality?[END_REF]. AR combines real and computer-based scenes and images to deliver a unified but enhanced view of the world.

In terms of the comparison of virtual reality and augmented reality, VR is a fully immersive and closed experience with no sense of the real world, while in AR user can see a real world with digital information overlay, which implies that a real world remains central to the experience, enhanced by virtual details.

Potentials of VR and AR implementation for HR systems in production management

Access to the internet and other digital technologies can further enhance the sense of human connection, especially for people facing physical and social barriers [START_REF] Guo | A Common Open Space or a Digital Divide? A Social Model Perspective on the Online Disability Community in China[END_REF]. In this respect, VR and AR becomes a transcendent experience, almost mystical in its ability to permit humans to go beyond their known realities [START_REF] Hinchcliffe | Virtual Reality Takes Consciousness Research into Mystic Realms of the Divine Play[END_REF]. Thus, it is of great significance to examine how new trends in technology, especially VR and AR, are being used for HRM activities in production systems.

Identification of VR/AR-human resource-production management relations in journals with open access

In order to analyze the available researches about application of VR and AR in human resource management in a field of production management (PM), the journals available through the Consortium of Libraries of Serbia for Unified Procurement (KoB-SON) were analyzed. The journals were divided into three groups according to the three analyzed areas: HR, VR/AR and PM. Based on the availability of the journal through the repository of KoBSON, which are also members of the Directory of Open Access Journals (DOAJ), a listing of the frequency of articles dealing with this interdisciplinary topic found in each journal are presented in the Tables 1-3. For each group of journals, the keywords of the other two research areas were used to identify the number of articles that covers all three analyzed areas. Based on this review, it can be concluded that there is a lack of research that analyzes the use of new VR/AR technologies in human resource management in the field of production management. This topic and trends require a multidisciplinary approach in research and represent an unexplored, but challenging and current field for research.

Exploring this topic, we found some articles dealing with the application of VR/AR technologies in HRM in specific industries, whose key conclusions are presented in the next part of the paper.

A literature summary of using VR/AR technologies for HR systems in production management

In recent years there has been an active development and growth of investments in VR and AR business, and the number of VR users is growing around the world [START_REF] Zhao | Sustainability and digitalization of corporate management based on Augmented/Virtual Reality tools usage: China and other world IT companies' Experience[END_REF]. Transformation of the role of VR and AR is evident as well: from gaming technologies, used mainly for entertainment purposes, to modern and effective tool applicable in the business environment (both for managing employee training, recruiting purposes, marketing, branding, and for main operational business processes, for example, measurement, 3D visualization, and modeling) [START_REF] Emarketer | Augmented Reality Marketing and Advertising[END_REF]. Zhao et al. [START_REF] Zhao | Sustainability and digitalization of corporate management based on Augmented/Virtual Reality tools usage: China and other world IT companies' Experience[END_REF] indicate that VR and AR allow managers to improve their current technologies, identify weak points, reduce risks and time for testing, rather than using real objects and processes.

VR offers HR employees a new way to provide an interesting experience for candidates and employees through basic HR processeshiring, adapting, training and organizing work [START_REF] Korenková | Linking a performance management system and competencies: Qualitative research[END_REF]. Its interactivity allows not only assessing the competences and skills of a candidate or employee, but also identifying his strengths and weaknesses.

Analyzing the modern possibilities of VR and AR tools, it is clear that these technologies can become an indispensable assistant and support in HR management.

By using VR and AR technology, companies can develop simulations, a type of game for attracting and hiring talent, or an interactive course for an employee and in general everything that a given workplace can offer. This can be a great way to attract people and a useful working approach in teaching them some of the skills they may need to succeed [START_REF]Ideal: 4 Innovative Ways Companies Are Using AR in Recruiting[END_REF]. Also, through these technologies many companies could collaborate with remote employees. With VR and AR technologies, companies can conduct recruiting and staff selection more efficiently, by presenting their employer brand to potential employees through an immersive experience. In new operations particularly, it is important to anticipate human resource requirements and to translate them into recruiting and training programs so that a nucleus of appropriately skilled operators is available as production machinery and equipment are installed [START_REF]Production management: industrial engineering[END_REF]. Integrating VR and AR technologies in this type of HR planning reduces the chance that expensive capital equipment will stand idle and that effort, time, and materials will be lost during startup and regular operations.

Journal

In addition, VR and AR can contribute to team building activities, significantly reduce the economic and time costs of staff training (especially travel cost and hotel accommodation) and improve staff adaptation in general. It allows distance meetings with remote employees or business partners located anywhere in the world. It is possible to demonstrate in detail and visualize the innovations, projects and its advantages, to attract the attention of the colleagues and audience etc. In production systems, the special value of VR and AR application in HRM can be a vivid insight in the flow of the main operational processes in production, visualization of potential weaknesses, operations that can and should be automated, etc.

Many studies show that through immersion in VR and AR, individuals can get "a contextual visualization of the environment to assist with an event or task while remaining within the bounds of the system" [START_REF] Randeniya | Virtual Reality Based Maintenance Training Effectiveness Measuresa Novel Approach for Rail Industry[END_REF]. Contextual learning and interactivity on engagement has a much higher contribution for learning [START_REF] Gutiérrez | Augmented Reality Environments in Learning, Communicational and Professional Contexts in Higher Education[END_REF], which is approved by an experiment of comparison of traditional training methods (TTM) and virtual reality-based training systems (VRTS). This experiment compared attributes between TTM and VRTS, such as comfort, ease of learning, ease of use, interactivity and engagement, and the results showed that VRTS are easier for learning and use and more engaged [START_REF] Xu | A VR-based the emergency rescue training system of railway accident[END_REF].

Conclusion

As a new technology trend that marked a last decade, virtual and augmented reality is increasingly being used for work simulation, but still it is not widely used in all functions and all areas of production management. This is evidenced by the very small number of articles published in journals on the SCI list (Science Citation Index list) that deals with this interdisciplinary topic. A literature review indicates that introduction of modern technologies, such as VR and AR, can support the design, engineering, management, and delivery of services, as well as employee engagement and memory retention capacity for working processes. In that manner, represented technologies meet the needs of the workforce as a significant stakeholder category in a business system, in a new, intelligent and innovative way. Summarizing the results of the research analysis, we can draw a conclusion that VR and AR technologies are not used only in entertainment sector. Moreover, these are proved to be effective and useful tools in managing corporate business processes, in our case, primarily observed in HRM activities. Empirical studies suggest that companies are starting to realize that VR and AR can be used in simultaneously training, recruitment, employee engagement and knowledge retention, in increasing productivity, reducing costs and time and in ensuring safe and secure working condi-tions. Also, numerous studies show that VR and AR will reduce costs, improve the performance indicators of the company as a whole, and take a strong competitive advantage. It is clear that VR and AR can become HR digital support in main operational activities in production management. The coherence among production management and HR strategy systems is substantial for the attainment of business success.

However, despite the existing successful examples and results of using VR and AR in the labor market, as well as their benefits in the work of HR specialists, if we consider the cost and complexity of technology implementation, this trend still poses challenges and questions. Therefore, this study could stimulate further research of new potential fields of VR and AR application in particular companies, sectors, industries, or even countries.

Table 1

 1 The frequency of HR and VR/AR articles in top listed PM journals by KoBSON

Table 2

 2 The frequency of HR and PM articles in top listed VR/AR journals by KoBSON

	Journals	IF 2018	Launched	Human	Virtual	Augmented	HR and	Field of research
			(year)	resource	reality	reality	VR and AR
				identified	identified	identified	identified
	International Journal of Operations	4.111	1980	775	9	2	9		Performance management;
	and Production Management								smart manufacturing;
									work organization
	Production and Operations	2.171	1992	1	1	-	1		Manufacturing;
	Management								individualization
	Advances in Production Engineering	2.047	2006	-	1	-	-		Product customization
	and Management
	Anbar Management Services.	-	-	-	-	-	-		-
	Production Abstracts
	Baking Management; The Production	-	1996	-	-	-	-		-
	Magazine for Volume Bakers
	Brazilian Journal of Operations and	-	2004	12	-	-	-		Process management;
	Production Management								training; work
									performance
	Independent Journal of Management	-	2010	48	4	1	6		Organizational
	and Production								performance; training
	International Journal of Production	-	2013	1	-	-	-		Evaluation; modeling;
	Management and Engineering								human capital
	Journal of Engineering, Project, and	-	2011	40	2	2	3		Project management
	Production Management
	Journal of Production and Operations	-	2011	5	-	-	-		Work performance;
	Management								human capital
	Management and Production	-	2010	1	-	-	-		Motivation; knowledge
	Engineering Review								management
	Production and Inventory	-	1959	-	-	-	-		-
	Management Journal
	Journal	IF 2018	Launched	Human resource	Production system	HR and PM	Field of research
					identified	identified		identified
	Virtual Reality	2.906	1995	3	5		1	Learning technology
	Journal of Virtual Reality and Broadcasting	-		2004	5	12		-	Tracking; performance
									analysis

Table 3

 3 The frequency of VR/AR and PM articles in top listed HR journals by KoBSON


Jannicke Baalsrud Hauge

Masoud Zafarzadeh

Yongkuk Jeong

Yi Li

Wajid Ali Khilji

Magnus Wiktorsson

Digital and physical testbed for production logistics operations

Keywords: Technology assessment, Cyber-physical system, Production logistics

Digitalisation and automation of existing processes are key factors for competitive industry, but still logistics operations are often dominated by manual work. A shift towards higher degree of automation within existing infrastructure is often challenged by high cost and complex processes, thus a return-on-investment is hardly achievable within decent time. The experience has shown that it is hard to assess all restrictions and interactions between new and old components before any new equipment or infrastructure is implemented and put into operation. This paper presents and discusses if the usage of digital twins representing and simulating a physical part can support the related assessing and decisionmaking processes. In this context, this paper presents a production logistics testbed includes physical devices, an IoT-infrastructure and simulation software for innovation as well as operational management purposes.

Technology assessment challenge

The cost of logistics is often high, but with minimal value-added contribution [START_REF] Veres | Intelligent Transportation Systems to Support Production Logistics[END_REF][START_REF] Christopher | Logistics and Supply Chain management[END_REF]. Consequently, stakeholders are looking into how to use technology to offer the same or better services at a lower cost [START_REF] Forcolin | EURIDICE-IoT applied to Logistcst using the intelligent Cargo concept[END_REF][START_REF] Zunder | Is it Possible to Manage and Plan Co-Modal Freight Transport Without a Centralised System?[END_REF][START_REF] Strandhagen | Logistics 4.0 and emerging sustainable business models[END_REF]. This trend encounter several challenges, which concerns more the implementation of different components in an existing operative environment than the technical development [START_REF] Patil | 6 key IoT Implementation Challenges for Enterprises to consider[END_REF][START_REF] Ek | Hur kan staten främja användandet av digitaliseringens möjligheter i näringslivet? 2[END_REF]. A key challenges is related to assessing how different new components will interact with the existing systems -i.e. a typically challenge when dealing with technology introduction in complex system [START_REF] Strandhagen | Logistics 4.0 and emerging sustainable business models[END_REF]. The usage of test-beds can contribute to overcoming these challenges [START_REF] Bosson | Digitalisering av svensk industri-kartläggning av svenska styrkor och utmaninger[END_REF]. However, it will not sufficiently contribute to understand the interactions of new components in an industrial operative environment, since there are several context related challenges such as physical limitations. For example, a challenge is related to the decentralised decision-making process carried out by the autonomous robots (like automated guided vehicles, or smart cargo) [START_REF] Forcolin | EURIDICE-IoT applied to Logistcst using the intelligent Cargo concept[END_REF][START_REF] Veres | Intelligent Transportation Systems to Support Production Logistics[END_REF][START_REF] Tao | Digital twin driven product design, manufacturing and service with big data[END_REF]. The usage of digital twins can help in overcoming this challenge, since it can visualise the differences between the optimal path based on algorithms and the optimal path based on the inbuilt decision-system in the AGV.

The focus of this article is to discuss how digital twins can contribute to support the decision-making process of selecting the right components for a specific task both related to the degree of automation and the digitalisation of the operations. The rest of the article first describes the requirements on a digital twin used for decision-making; secondly how the manipulation of the digital twin can be used for a better understanding of the system and components interactions, before the test-bed we are using is described in more detailed. Finally, we describe how the different components are integrated and interacting and as well as the first results. The last section discusses the main challenges and the next steps.

Digital twin preconditions for production logistics' activities planning

Technology introduction has a large impact on the organisation of operational processes both at managerial and operative level [START_REF] Tao | Digital twin driven product design, manufacturing and service with big data[END_REF]. Therefore, it is not sufficient to only pay attention to the technical aspects, but also required to predict their outcomes and based on that, make right decisions. According to [START_REF] Yao | Optimizing the Scheduling of Autonomous Guided Vehicle in a Manufacturing Process[END_REF] digital twins can support planning as well as prediction of the working processes. Regarding the definition of digital twin, we build it upon the definition by Tao et al. [START_REF] Tao | Digital twin driven product design, manufacturing and service with big data[END_REF] p.3566 as well as the characteristics of digital twin as described in [START_REF] Tao | Digital twin driven product design, manufacturing and service with big data[END_REF] in respect to a) real-time reflection b) interaction and convergence and c) self-evolution. As described in the introduction, a main challenge of introducing concepts like IoT, CPS, and Industrie4.0 etc. in existing environments is the assessment of how the technology will affect the whole organisation and interact with existing solutions. According to [START_REF] Brenner | Digital twin as enabler for an innovative digital shopfloor management system[END_REF][START_REF] Ştefan | Approaches to Reengineering Digital Games[END_REF][START_REF] Hauge | An educational framework for supporting the implementation of the Intelligent Cargo concept[END_REF] digital twins that can be manipulated can support the decision-making process. Regarding the assessment of autonomous and decentralized decision-making, which is required in cyber-physical systems [START_REF]VDI 3633 Simulation von Logistik[END_REF][START_REF] Nokelainen | Mind or Machine? Opportunities and Limits of Automation[END_REF] it is hard to model these with the right interactions with other system components and with the right routing (decided upon by the autonomous object) [START_REF] Forcolin | EURIDICE-IoT applied to Logistcst using the intelligent Cargo concept[END_REF][START_REF] Yao | Optimizing the Scheduling of Autonomous Guided Vehicle in a Manufacturing Process[END_REF]. However based on experiences on importing sensor data from a lab-environment into the virtual environment, comparing the routes and interaction with the first simulations, and then modify and manipulate these data in the digital twin (by using game mechanics), a better system understanding can be achieved [START_REF] David | Leveraging Digital Twins for Assisted Learning of Flexible Manufacturing Systems[END_REF]. Digital twin can mirror or simulate complex scenarios very close to the reality [START_REF] Tao | Digital twin driven product design, manufacturing and service with big data[END_REF][START_REF] Nokelainen | Mind or Machine? Opportunities and Limits of Automation[END_REF][START_REF] David | Leveraging Digital Twins for Assisted Learning of Flexible Manufacturing Systems[END_REF][START_REF] Zhuang | Digital twin-based smart production management and control framework for the complex product assembly shop-floor[END_REF]. Besides providing an opportunity to be used as a learning and awarenessincreasing tool in which operators, or management can use virtual reality (VR) tools to experience the real working conditions with high precision [START_REF] Hc Pfohl | Produktionslogistik[END_REF], the digital twin can support the introduction of new technologies and installations within the existing physical environment [START_REF] Hc Pfohl | Produktionslogistik[END_REF][START_REF] Hauge | Bridging educational and working environments through pervasive approches[END_REF]. In this case, we simulate the working processes and observe the material movements, machines, robots etc. and their interactions [START_REF] Toivonen | The FMS Training Center -a versatile learning environment for engineering education[END_REF]. One of the Swedish test-beds focuses on production logistics, i.e. it focuses on the material and information handling within the production system, with strong and integrated interfaces to supply chain management. This physical test-bed should allow testing of a) man to material technologies b) robot to material c) material to man and d) material to robot. Furthermore, in order to realise the latter, it should explore the usage of Real time locating system (RTLS) and the interaction and operation of different AGVs. It should be set up to meet the industrial need for improved demand assessment, dynamic and more efficient milk-runs, shortened cycle times, reduced bullwhip effects, highly transparent and integrated supply chains as well as improvements in production planning, real-time information flows, end-to-end supply chain transparency and general improvements in flexibility [START_REF] Hofmann | Industry 4.0 and the current status as well as future prospects on Logistics[END_REF]. By the four pillars of technology support, real-time information, interoperability and decentralized decisions core technology areas needed should include real-time data acquisition, organization, and management; digital twin representation; data analytics for logistics applications; and digital twin-based shopfloor management and control [START_REF] Zhuang | Digital twin-based smart production management and control framework for the complex product assembly shop-floor[END_REF].

3

The physical and digital test-bed

Physical environment

The focus of the first set-up is on connecting equipment and RTLS, since these are a prerequisite for being able to realise a transparent and efficient material flow from one warehouse to a production site as visualised in Fig. 1. The initial demonstration scenario is to kit three different parts in two different kits by introducing a UR (collaborative robot), an AGV, a Kinect vision system, and a RTLS. The AGV transport the parts from storage position to the UR robot station, which performs the kiting with the help of the vision system. The kitted parts will be transported by the AGV to the assembly station at the end.

Fig. 1. Material flow process within the testbed

In order to investigate the problems mentioned in section 2, the physical objects and the digital twin are integrated in a single system, which components communicate via a data streaming bus. This system interconnects all components to make use of digital twin of the real-world scenario. As a first step, communication between each component was realised. A data streaming bus, which will hold and serve messages wherever needed was chosen for this purpose. Secondly, there is an application layer, which is required in order to write business logic or calculations. In addition, data storage and digital twin ought to be connected through the application layer. Fig. 2. represents the system architecture for the production logistics digital twin. Here, the robot is treated as a server and connected via a TCP client application. c) The RTLS system uses API to retrieve location data of these various objects. d) The vision system is currently built by using Microsoft Xbox Kinect and working via a C# program with the help of OpenCV wrapper, called EMGU. Coordinated captured by Kinect will be send to a middle-ware that translates them into the collaborative robot coordinates. e) To visualise the digital twin, Unity is used. Along with some complex prefabs like AGV and collaborative robot, delivered by the supplier or modelled using IPS. Each controller is responsible for fetching data or controlling the machine. f) Data storage is used for the long-term data solution for data analytics, or data mining aiming to replay a particular scenario. The next section describes the different possibilities we have for the models in the digital twin, as well as outlines what we currently mainly look at. The digital environment does not only mirror the physical environment in the testbed, but also allow 'manipulation' to allow experimentation with different technologies and equipment prior to the decision in a virtual world.

Applications for workstation design

As described above, it is needed to know what granularity our models should have, depends on what we intend to use them for. For the purpose of the test-bed and the given requirements, we need different granularities for different manipulations. Therefore, three examples in this spectrum of applications are presented. a) engineering of workstations, b) layout planning and c) collaborative robotics. This will cover all the levels we need in the test-bed on long term and gives an overview of the different levels of required granularities. In order to realise the three different cases, specific modelling tool is used: a detailed analysis of robotic workstation design and AGV route planning has been carried out through IPS simulation tool shown in Fig. 3. The UR robot trajectories during the kitting process is simulated to calculate the required space to place kitting boxes, loading rack, and AGV docking position. Besides, the required distances for safe operation is calculated here. The AGV movement within the testbed area is simulated based on IPS route planning algorithm, which is the optimal path. The simulated path can be compared with actual path taken by the AGV to compare the deviations and root cause analysis.

Fig. 3. Using IPS simulation tool to engineer workstation design and AGV route planning within the testbed environment

Applications for logistics operations analysis

The digital twin is used both with pure simulation data as well as with data from what we already have in operation to figure out the integration and interaction of AGV and picking robot investigating how the AGV is doing its mission scheduling and how this can be improved. Interaction and interference with existing systems as well as to decide upon the right new object (like the type of AGV) is a challenge as described earlier.

Secondly, another challenge is that there is limited information about the algorithm the AGVs are using for calculating their path. In this case, we have however full control over the algorithm the digital twin of the AGV (modelled using IPS), which is the optimised algorithm. Comparing the results of the digital twin optimised algorithm and the physical movements of the AGV can give valuable information on the behaviour and thus help in the assessment of the suitability for implementation in different environments. Furthermore, the integration of the physical data in the digital twin allows a better visualisation that can be used for: a) Detailed investigation of the exact movements of the AGV or collaborative robot (as shown in fig. 4). b) Using a re-play function as well as combining different experiments in one single digital twin scenario helps to understand the variation in movements as well as to recognise patterns (i.e. continuously occurring deviations between real movements and optimised calculated paths). c) To explore an environment, which might have no or limited access (either using VR, AR or a 3D computer model on the PC). This can be used for teaching purposes to explain the interaction of the different components as well as for letting the students try out simple actions in a safe environment. The digital twin has the capability to start the different physical operations via the digital twin interface. This opens up the possibility for carrying out experiments in risk areas. In this case, except few individuals, most of the personnel do not have the right access to operate the physical equipment on site, can perform experiments through digital twin. This increases the possibilities to utilise expensive lab equipment to a higher degree.

Fig. 4. Tracking AGV in real time within the digital twin

The mixed-reality environment, which we have described here, is in its prototypical implementation phase and the results are preliminary, but promising. During the last semester, the lab used as part of a master course for production logistics. Here a group of students carried out experiments studying the exact movements of the AGV in the physical lab. At that time, it was not possible to import and store the data in the digital twin for visualisation, but the collected data will now be imported and compared with the ideal (optimised) movements. Secondly, the first tests of using the digital twin for educational purposes have been successfully tried out in different labs. We have therefore now integrated our digital -physical twin environment for educational purposes in a digitalisation course. The remote control scenario is so far working well as long as it is operated within the network.

In the next step, it will also be possible to run and manipulate the model from outside. This will allow us to connect different test-beds to one single digital test-bed in order to look at larger challenges. The simulated optimized route in the digital twin will be compared to the actual chosen route by AGV in the physical environment. Besides, quality control checkpoints needs to be located as well as to investigate how to embed this into the material flow process.

Discussion and conclusion

The focus of this article is to discuss how digital twins can be used for technology assessment. . The digital twin has been used to analyse workstation design and AGV route planning with a focus on understanding how the granularity in the modelling used in the digital twin affect the transferability of the results achieved with the digital twin technology assessment to a physical world. By using a testbed environment, it has been possible to compare the technology assessment in the digital twin with a technology assessment of the physical environment and based on this draw conclusion about the need of granularity differences in the modelling. Main conclusion is that the granularity of the model is one of the key limiting factors for using a digital twin for technology assessment of real-world/physical logistical operations. . In this case, picking operation is simulated to analyse required space, cycle time, and safety. Compare to a manual system, a fully automated system is less flexible as human has much higher level of intelligence, but it has drawbacks such as mistakes, fatigue and less availability, however looking into the degree of granularity for the models, the experiments shows that this can be fairly low as long as we are only interested in cycle time and costs, but needs to be high for safety and medium for space usage For AGV route planning, the results showed how the AGV might behave in the physical environment compare to IPS simulated model. For these first experiments, a low granularity was needed, the required space, routes, possible hinders and safety concerns could be sufficiently well analysed. The collaboration with UR robot is another issue, which we could analyse by using digital twin and where we have to conclude that a high granularity is required.

In general, the primary results of how digital twin can be used for technology assessment in production logistics are promising. However, more tests and investigations are required to be able to be more explicit.

Fig. 2 .

 2 Fig. 2. Production logistics digital twin system architecture

Fig. 4

 4 illustrates this possibility. The picture to the left shows the digital model of the lab environment. The viewer can use a camera to move around and experience the room. Besides the detail of the models-here the path of the AGV-is visualised. The image to the right shows the movement of the physical AGV (data imported in the Unity model via the communication bus).

Acknowledgment

The present work was carried out partly within the project DIGILOG (Produktion 2030, Vinnova) and UniLog (Central Baltic program, grant no. CB743). This presentation does not represent the opinion of the European Community or Vinnova, and the European Community and Vinnova are not responsible for any use that might be made of its content.