The society today lives on the philosophy of ‘take-make-use-dispose.’ In the long run, this is not sustainable as the natural resources and the waste carrying capacity of the earth are limited. Therefore, it is essential to reduce dependency on the natural resources by decoupling the growth from the consumption. In this venture, both the society and the manufacturing industry have a vital role to play. The society needs to shift towards Circular Economy that rests upon the philosophy of ‘take-make-use-reuse’ and the manufacturing industry has to be a major stakeholder in this shift. Despite being proven to be both economically and environmentally beneficial, successful examples of circular systems are few today. This is primarily due to two reasons; firstly, there is a lack of systemic and systematic approach to guide industries and secondly, there is a lack of analysis methods and tools that are capable of assessing different aspects of circular manufacturing systems. Taking on to these challenges, the objective of this research is to bring forward a framework with methods and decision support tools that are essential to implement circular manufacturing systems. The initial conceptual framework with the systemic approach is developed based on extensive review and analysis of research, which is further adapted for industrial implementation. Systematic analysis methods, decision support and implementation tools are developed to facilitate this adaptation. This development has been supported by four cases from diverse manufacturing sectors. Behind each decision support tool, there are analysis methods built upon mainly system dynamics principles. These tools are based on simulation platforms called Stella and Anylogic. Among other things, these tools are capable of assessing the performance of closed-loop supply chains, consequences of resource scarcity, potential gains from resource conservation and overall economic and environmental performance of circular manufacturing systems.

Purpose

The question of resource scarcity and emerging pressure of environmental legislations has brought a new challenge for the manufacturing industry. On the one hand, there is a huge population that demands a large quantity of commodities; on the other hand, these demands have to be met by minimum resources and pollution. Resource conservative manufacturing (ResCoM) is a proposed holistic concept to manage these challenges. The successful implementation of this concept requires cross functional collaboration among relevant fields, and among them, closed loop supply chain is an essential domain. The paper aims to highlight some misconceptions concerning the closed loop supply chain, to discuss different challenges, and in addition, to show how the proposed concept deals with those challenges through analysis of key performance indicators (KPI).

Methods

The work presented in this paper is mainly based on the literature review. The analysis of performance of the closed loop supply chain is done using system dynamics, and the Stella software has been used to do the simulation. Findings The results of the simulation depict that in ResCoM; the performance of the closed loop supply chain is much enhanced in terms of supply, demand, and other uncertainties involved. The results may particularly be interesting for industries involved in remanufacturing, researchers in the field of closed loop supply chain, and other relevant areas. Originality The paper presented a novel research concept called ResCoM which is supported by system dynamics models of the closed loop supply chain to demonstrate the behavior of KPI in the closed loop supply chain.

Anticipated scarcity of natural resources and concern for the sustainable development forcing manufacturing industries to emphasise on conservation of resources on one hand. On the other hand high competition in the manufacturing industry is forcing companies to look for innovative value propositions. Service based business models are emerging business solutions that fulfil the functional needs of customers. Such business approach demands extensive and sophisticated information collection, sharing and management systems. However, there are evidences of knowledge gap when it comes to defining information requirements, information management and sharing systems needed to adopt such business models. The objective of this paper is to provide an overview of research done in the area of service based business models in terms of information management and communication systems. The paper also includes result of two case studies done in two different manufacturing companies with the purposes to understand information requirements to adopt service based business models.

The question of resource scarcity and emerging pressure of environmentallegislations have put the manufacturing industry with a new challenge. On theone side, there is a huge population that demands a large quantity ofcommodities, on the other side, these demands have to be met by minimumresources and with permissible pollution that the earth’s ecosystem can handle.In this situation, technologic breakthrough that can offer alternative resourceshas become essential. Unfortunately, breakthroughs do not follow any rule ofthumb and while waiting for a miracle, the manufacturing industry has to findways to conserve resources. Within this research the anatomy of a large body ofknowledge has been performed to find the best available practices for resourceconservation. Critical review of the research revealed that none of the availablesolutions are compatible with the level of resource conservation desired by themanufacturing industry or by society. It has also been discovered that a largegap exists between the solutions perceived by the scientists and theapplicability of those solutions. Through careful evaluation of the state-of-theart,the research presented in this thesis introduced a solution of maximizingresource conservation i.e., material, energy and value added, as used inmanufacturing. The solutions emerged from the novel concept named asResource Conservative Manufacturing, which is built upon the concept ofMultiple Lifecycle of product. Unlike other research work, the researchdocumented in this thesis started with the identification of the problem andfrom which a ‘wish to do’ list was drawn. The seriousness of the problem andpotential of adopting the proposed concept has been justified with concreteinformation. A great number of arguments have been presented to show theexisting gaps in the research and from that, a set of solutions to conserveresources has been proposed. Finally, one of the prime hypotheses concerningclosed loop supply chain has been validated through the system dynamicsmodeling and simulation.

Purpose: The transition from linear to circular product systems is a big step for any organization. This may require an organization to change the way it does business, designs product and manages supply chain. As these three areas are interdependent, bringing change in one area will influence the others, for instance, changing the business model from conventional sales to leasing will demand changes in both product design and the supply chain. At the same time, it is essential for an organization to anticipate the economic and environmental impact of all changes before it may decide to implement the circular product systems. However, there is no tool available today that can assess economic and environmental performance of circular product systems. The purpose of this research is to develop a multi-method simulation based tool that can help to evaluate economic and environmental performance of circular product systems. Method: The conceptual models that are used to develop the tool have been formulated based on review of the state-of-the-art research. System Dynamics (SD) and Agent Based (AB) principles have been used to create the simulation model which has been implemented in Anylogic software platform. Originality: This research presents the first multi-method simulation based tool that can evaluate economic and environmental performance of circular product systems. Findings: Multi-method simulation technique is useful in designing dynamic simulation model that takes into consideration mutual interactions among critical factors of business model, product design and supply chain. It also allows predicting system's behaviour and its influence on the economic and environmental performance of circular product systems.

To ensure multiple-lifecycle of products through remanufacturing intervention requires a well-functioning closed-loop supply network. Generally, the unpredictability of quantity, timing and quality (physical/functional) of the returned products and demand fluctuation of the remanufactured products are the main sources of uncertainty of closed-loop supply network. To some extent, efficient recollection strategies and separate distribution channels for remanufactured products can minimize the uncertainty. Nevertheless, efficient recollection does not necessarily close the loop if the recovered products do not enter into the main stream of the supply network. Beside, products that are distributed through separate channels create an open loop. Thus, the problem of uncertainty remains unsolved. The aim of this paper is to propose solutions to minimize the uncertainty involved in designing a well-functioning closed-loop supply network using the system dynamics principle and tool.

The main drivers for adopting product multiple lifecycles are to gain ecological and economic advantages. However, in most of the cases it is not straight forward to estimate the potential ecological and economic gain that may result from adopting product multiple lifecycles. Even though many researchers have concluded that product multiple lifecycles result in gain, there are examples which indicate that the gain is often marginal or even none in many cases. The purpose of this research is to develop system dynamics models that can assist decision makers in assessing and analysing the potential gain of product multiple lifecycles considering the dynamics of material scarcity. The foundation of the research presented in this paper is laid based on literature review. System dynamics principles have been used for modelling and simulations have been done on Stella iThink platform. The data used in the models have been extracted from different reports published by World Steel Association and U.S. Geological Survey. Some of the data have been assumed based on expert estimation. The data on iron ore reserves, iron and steel productions and consumptions have been used in the models. This research presents the first system dynamics model for decision making in product multiple lifecycles which takes into consideration the dynamics of material scarcity. Physical unavailability and price of material are the two main factors that would drive product multiple lifecycles approach and more sustainable decisions can be made if it is done by taking holistic system approach over longer time horizon. For an enterprise it is perhaps not attractive to conserve a particular type of material through product multiple lifecycles approach which is naturally abundant but extremely important if the material becomes critical. An enterprise could through engineering, proper business model and marketing may increase the share of multiple lifecycle products which eventually would help the enterprise to reduce its dependency on critical materials.

The transition towards a circular economy has become important. Manufacturing industry being a major stakeholder in this transition has started exploring the potential of this transition and challenges in implementation. Ambitious companies such as Gorenje d.d. has taken the circular economy transition seriously and aims to become a pioneer in implementing circular manufacturing systems. One vital step in this transition is the business model shift from the linear (sales model) to a circular model such as 'product as a service'. This brings new challenges to Original Equipment Manufacturers (OEMs) that have never been experienced in their conventional businesses. One of the challenges is to establish an information communication and technology (ICT) infrastructure that enables information management and sharing as well as establishes a real-time communication between relevant stakeholders. Outlining such an ICT infrastructure is the objective of this paper.

Circular Economy (CE) promotes trading functions of a product as aservice instead of selling the product in conventional ways. For a product like ababy stroller, the function means ensuring mobility with infants without needingto own a stroller. This approach of acquiring functions only when needed opensup the possibility to share the same products with multiple users. For a manufacturer that has built its business on a conventional sales model over the decades,this shift may be too radical. Therefore, for the manufacturers, it is important tounderstand consumer perceptions of the service-oriented business model beforeentering this unknown territory. To develop a thorough understanding of consumerperceptions of leasing a stroller instead of buying one, a survey among 200 parentsin Stockholm is conducted. The survey brings out quantitative results such as 39%of respondents are open to leasing and identifies key influencing factors such asconvenience and environmental image that play a key role for the remaining 61%of respondents to choose leasing. This research concludes that a large numberof consumers are open to leasing if a high level of service and environmentallysustainable strollers are offered at a competitive price.

The Design for Repeatedly Utilization (DFRU) is a proposed conceptto be used in the product realizationprocess to ensure optimum useable life (forinstance in terms of economy, resourceusage, environmental impact etc.) ofproducts or parts of products enablingmultiple lifecycle. In the DFRU approachproducts are restored as new like productsthrough remanufacturing processes. Theterm remanufacturing has been interpreteddifferently by different researchers and theindustries that are involved inremanufacturing business use differentapproaches to remanufacture theirproducts. In this paper the starter motorand alternator of automotives has beenused to demonstrate the novel concepts.The purpose of this paper is to expresswhat remanufacturing means in ourconcept, model their major lifecycleaspects and create a simulation modelfrom it. This is a preliminary work towardsdefining and specifying the processes,methods and design properties in DFRU.The work will be further extended to aholistic business model which can facilitateDFRU approach in an efficient way. Infuture the model will be developed andadopted to create new models for otherproducts appropriate for remanufacturingand eventually DFRU.

Our life is strongly linked with the usage of natural resources. Energy is a necessity in everyday life and is often generated using non-renewable natural resources which are finite. Energy consumption in manufacturing industry is increasing and the way it is consumed is not sustainable. There is great concern about minimizing consumption of energy in manufacturing industry to sustain the natural carrying capacity of the ecosystem. This is one of the challenges in today’s industrial world.In this paper two case studies have been carried out in crankshaft machining and cylinder head casting processes. The outcome of this research enables the company to identify potential avenues to optimize energy usage and offers a decision support tool.

This chapter will present an outlook on the modelling and simulation of circular manufacturing systems. Simulations in the linear context have long been an enabler in making the systems efficient through better design and improved decision-making. Circular aspects of manufacturing systems lead to another level of complexity to be tackled and understood in terms of the performance of the system from an economic, environmental and social perspective. This calls for enhanced understanding through analysis of the interdependencies between business models, product design, supply chains and consumption patterns interactions by modelling the effect of those interactions to provide a sound basis for decision-making. The role of modelling simulation for prediction and improved decision-making in complex situations will be presented and exemplified with case studies where simulation has been used as a tool to enhance decision-making. The chapter finishes by highlighting the potential of modelling and simulation in boosting the transition towards circular systems implementation.

Stretchable electronics is a new innovation and becoming popular in various fields, especially in the healthcare sector. Since stretchable electronics use less printed circuit boards (PCBs), it is expected that the environmental performance of a stretchable electronics-based device is better than a rigid electronics-based device that provides the same functionalities. Yet, such a study is rarely available. Thus, the main purpose of this research is to perform a comparative life cycle analysis of stretchable and rigid electronics-based devices. This research combines both the case study approach and the research review approach. For the case study, a cardiac monitoring device with both stretchable and rigid electronics is used. The ISO 14044:2006 standard's prescribed LCA approach and ReCiPe 2016 Midpoint (Hierarchist) are followed for the impact assessment using the SimaPro 9.1 software. The LCA results show that the stretchable cardiac monitoring device has better environmental performance in all eighteen impact categories. This research also shows that the manufacturing process of stretchable electronics has lower environmental impacts than those for rigid electronics. The main reasons for the improved environmental performance of stretchable electronics are lower consumption of raw material as well as decreased energy consumption during manufacturing. Based on the LCA results of a cardiac monitoring device, the study concludes that stretchable electronics and their manufacturing process have better environmental performance in comparison with the rigid electronics and their manufacturing process.

Life Cycle Assessment (LCA) is a well-known methodology used to calculate the environmental impacts of a product across its life cycle. The industrial machines used to manufacture consumer products are generally heavy, bulky, and have a complex product structure which makes their environmental assessment using LCA difficult as well as time and resource-intensive. Few studies have conducted LCA of complex industrial machines. The paper presents an LCA of a jet printing and dispensing machine (MY700), an industrial machine used in the production of printed circuit boards (PCBs) carried out using ReCiPe 2016 (Hierarchist) impact assessment methodology. In this study, the use phase of the machine accounted for 91% of the total environmental impacts. The compressed air and electricity consumed in the use phase of the machine were the major environmental hotspots. Additionally, some measures to minimize energy and compressed air use are also discussed. The methodology proposed in this article can be adopted by practitioners to conduct LCA of other industrial machines. The results of this study can help the machine manufacturers to undertake relevant eco-design activities as well as a comparison of different versions/machines in the product family for their environmental impact.

This paper introduces an agent-based approach to study customer behavior in terms of their acceptance of new business models in Circular Economy (CE) context. In a CE customers are perceived as integral part of the business and therefore customer acceptance of new business models becomes crucial as it determines the successful implementation of CE. However, tools or methods are missing to capture customer behavior to assess how customers will react if an organization introduces a new business model such as leasing or functional sales. The purpose of this research is to bring forward a quantitative analysis tool for identifying proper marketing and pricing strategies to obtain best fit demand behavior for the chosen new business model. This tool will support decision makers in determining the impact of introducing new (circular) business models. The model has been developed using an agent-based modeling approach which delivers results based on socio-demographic factors of a population and customers’ relative preferences of product attributes price, environmental friendliness and service-orientation. The implementation of the model has been tested using the practical business example of a washing machine. This research presents the first agent-based tool that can assess customer behavior and determine whether introduction of new business models will be accepted or not and how customer acceptance can be influenced to accelerate CE implementation. The tool integrates socio-demographic factors, product utility functions, social network structures and inter-agent communication in order to comprehensively describe behavior on individual customer level. In addition to the tool itself the results of this research indicates the need for systematic marketing strategies which emphasize CE value propositions in order to accelerate customer acceptance and shorten the transition time from linear to circular. Agent-based models are emphasized as highly capable to fill the gap between diffusion-based penetration of information and resulting behavior in the form of purchase decisions.

The recent circular economy movement has raised awareness and interest about untapped environmental and economic potential in the manufacturing industry. One of the crucial aspects in the implementation of circular or closed-loop manufacturing approach is the design of circular products. While it is obvious that three post-use strategies, i.e., reuse, remanufacturing, and recycling, are highly relevant to achieve loop closure, it is enormously challenging to choose “the right” strategy (if at all) during the early design stage and especially at the single component level. One reason is that economic and environmental impacts of adapting these strategies are not explicit as they vary depending on the chosen business model and associated supply chains. In this scenario, decision support is essential to motivate adaptation of regenerative design strategies. The main purpose of this paper is to provide reliable decision support at the intersection of multiple lifecycle design and business models in the circular economy context to identify effects on cost and CO2 emissions. The development of this work consists of a systematic method to quantify design effort for different circular design options through a multi-method simulation approach. The simulation model combines an agent-based product architecture and a discrete event closed-loop supply chain model. Feasibility of the model is tested using a case of a washing machine provided by Gorenje d.d. Firstly, design efforts for reuse, remanufacturing, and recycling are quantified. Secondly, cost and emissions of different design options are explored with different business model configurations. Finally, an optimization experiment is run to identify the most cost-effective combination of reused, remanufactured, and recycled components for a business model chosen on the basis of the explorative study results.

Background: Transitions from a linear (take-make-dispose) to a circular product system (consideringreuse/remanufacturing/recycling) require changes of business models through new value propositions.Therefore, the focus for industrial businesses shifts from selling physical products to, for example,providing access to functionality through business innovation. In this context it is particularly challengingto understand what complexity a new concept like circular economy (CE) brings to establishedbusinesses where the success and the failure of the business is dependent on customer’s acceptance ofnew value propositions.Objective: The objective of this paper is to develop an algorithm based on gathered survey data to “learn”choice behavior of a small customer group and then replicate that choice behavior on a larger populationlevel.Purpose: This paper explores the opportunities of different circular business offers in the city of Stockholmby embedding support vector machine classifiers, which are trained on CE survey data, in asimulation model to quantify and study choice behavior on city level.Method: Stated choices from CE surveys including unique demographic data from the respondents, i.e.age, income, gender and education, are used for algorithm training. Based on the survey data, supportvector machine algorithms are trained to replicate the decision-making process of a small sample ofrespondents. The example of a washing machine is used as a case study with the attributes price andpayment scheme, environmental friendliness as well as service level. The trained support vector machinesare then implemented in a simulation model to simulate choice behavior on population level(Stockholm city).Originality: This paper is the first of its kind to use both machine learning and simulation approaches in aCE market acceptance context.Findings: Based on the washing machine-specific survey and Stockholm-specific customer data, resultsindicate that larger share of the Stockholm population would be willing to opt for circular washingmachine offers compared to the existing linear sales model. Given the data-driven nature of machinelearning algorithms and the process-oriented structure of simulations programs allows for generatinglarge amounts of data from small samples. This supports exploration of new emerging areas like CE inaddition to saving time and expenses.

Background: In industrial practice a transition from a linear (take-make-dispose) to a circular product system (considering reuse/remanufacturing/recycling) requires the change of business models through new value propositions. In doing so the focus of the value proposition shifts from selling a physical product to providing access to functionality through business innovation. One key factor related to circular business transitions is market acceptance. It is particularly challenging to understand what complexity a new concept like circular economy (CE) brings to established businesses where the success and the failure of the business is dependent on customer's acceptance of new value propositions. Purpose: This paper empirically explores the opportunities of a circular business approach for washing machines in the city of Stockholm by quantifying and assessing customer preferences for CE value propositions for a business to customer (B2C) scenario. Method: This study uses the method of choice-based conjoint analysis to investigate preferences based on the attributes price and payment scheme, environmental friendliness as well as service level. Originality: This paper is the first of its kind to assess customer preferences from the CE market acceptance point of view using a conjoint approach and provides insight to what extent new CE value propositions may be adopted. Findings: Results indicate that there is general interest in paying for access rather than for ownership. Service levels have the strongest impact on customer utility of a washing machine offer. If associated with reduction in CO2 emissions the number of remanufacturing cycles can increase purchase probability. As a method choice-based conjoint analysis is highlighted as beneficial to break down CE value propositions and to identify to what extent particular service-related attributes and product-related attributes contribute to overall customer utility. (C) 2017 Elsevier Ltd. All rights reserved.

Optimizing the energy consumption of robot movements has been one of the main focuses for most of today's robotic simulation software. This optimization is based on minimizing a robot's joint movements. In many cases, it does not take into consideration the dynamic features. Therefore, reducing energy consumption is still a challenging task and it involves studying the robot's kinematic and dynamic models together with application requirements. This research aims to minimize the robot energy consumption during assembly. Given a trajectory and based on the inverse kinematics and dynamics of a robot, a set of attainable configurations for the robot can be determined, perused by calculating the suitable forces and torques on the joints and links of the robot. The energy consumption is then calculated for each configuration and based on the assigned trajectory. The ones with the lowest energy consumption are selected. Given that the energyefficient robot configurations lead to reduced overall energy consumption, this approach becomes instrumental and can be embedded in energy-efficient robotic assembly.

The products and the business models developed for conventional open-loop product systems are unable to cope with the requirements for resource efficiency. This paper redefines the conventional paradigm of closed-loop product systems and outlines the novel concept of multiple lifecycle products. The newly developed conceptual framework considers the conservation of energy, material and value added with waste prevention and environment protection as integrated components of the product design and development strategy. It also presents innovative ideas regarding designing products with multiple life cycles, business model for closed-loop supply chain, empowering customers, and multi-stakeholder approach required for the transition towards resource efficient production and consumption.

For sustainability of our future societies we need sustainable manufacturing strategies with resource and environment conservation as their integral part. In this perspective closed-loop supply chains are considered as the most feasible solution. However, their implementation within the paradigm of prevailing open-loop product systems seems extremely complicated and practically infeasible. This paper argues for a radical shift in thinking on the closed-loop systems and presents the novel concept of Resource Conservative Manufacturing (ResCoM). The ResCoM concept considers the conservation of energy, material and value added with waste prevention and environment protection as integrated components of the product design and development strategy. It also presents the innovative idea of products with multiple lifecycles where several lifecycles of predefined duration are determined already at the product design stage thus demanding for new design strategies and methodologies. To succeed with this concept ResCoM advocates for new approach to supply chain design and business models as well, where the customers are integral part of manufacturing enterprises and the product design is effectively connected with the supply chain design. This work concludes that the products, supply chains and the business models developed for open-loop product systems are unable to cope with the dynamics of closed-loop systems. The uncertainties associated with product returns are inherent to the conventional concept of lifecycle and closed-loop systems. The ResCoM concept has much better capability in dealing with these uncertainties while developing sustainable closed-loop systems. The presented work outlines and discusses the conceptual framework of ResCoM. A comprehensive work on the strategic and tactical issues in the implementation of the ResCoM concept will follow.

Manufacturing industry is a major consumer of the energy and material resources generating significant amount of waste. Circular manufacturing systems (CMS) that are designed intentionally for closing the loop of products for reuse, maintaining their original performance at the least, through multiple lifecycles are indispensable for sustainable development. For successful implementation of CMS, a systemic approach for integration of business model, product design and supply chains exploiting Information and Communication Technology (ICT) a vital enabler is essential. In CMS, the business model is a primary driver dictating the design of both products and supply chains. While these three functions influence each other in diverse ways, they also define needs and requirements for ICT infrastructure for handling the complexity of information management throughout the value chain. Several leading industrial practices across the manufacturing landscape are representative examples of CMS, where the systemic approach of integrating business model, product design, supply chain and ICT is taken into consideration. Prominent examples of such approach include companies like Xerox, Ricoh, Caterpillar, HP, Renault and Michelin. This chapter explores the concept of CMS, their characteristics and need in the context of circular economy. It also analyses leading examples of CMS implementation in the current linear economy paradigm and challenges in scaling up to realise their full business and sustainability potential.

It is estimated that the adaptation of the Circular Economy approach can yield material cost savings of hundreds of billions of dollars per year for the EU and can result in huge environmental benefits. To tap this potential, the manufacturing industry needs to take a circular approach, where the products are designed intentionally to be used for multiple lifecycles. However, there is a lack of methodologies to date that can support such an approach. To fill this gap, this research has proposed a novel methodological approach that can support designing products for multiple lifecycles to keep the products as well as the components and the materials at their highest utility and value at all times. This research has identified that there is a strong synergy among the concepts of product design strategies, product obsolescence and product end-of-life options. Taking this synergy as the foundation and adopting modular architectures in the product design and development process, lifecycle planning can be performed for products that will sustain multiple lifecycles. This research is performed in two steps: first, the research review process is used to explore the knowledge base in the field of product design methodologies and based on the insights from the literature a novel methodological approach is proposed; second, a case example is used to demonstrate the applicability and effectiveness of the proposed methodological approach.

Circular manufacturing systems (CMS) constitute complex value networks comprising a large and diverse set of stakeholders that collaborate to close the loop of products through multiple lifecycles. Complex systems modelling and simulation play a crucial role in providing quantitative and qualitative insights into the behaviour of such systems. In particular, multi-method simulation modelling that combines agent-based, discrete-event, and system dynamics simulation methods is considered more suitable to model and simulate CMS as it allows to capture their complex and dynamic nature. This paper provides a step-by-step approach on how to build a CMS multi-method simulation model in order to assess their economic, environmental, and technical performance for enhanced decision-making. To model and simulate CMS three main elements need to be considered: • A multi-method model architecture where the CMS stakeholders with heterogeneous characteristics are modelled individually as autonomous agents using agent-based, discrete-event, and system dynamics. • An agent environment defined by a Geographic Information System (GIS) to establish connections based on agents’ geographic location. • The product journey resulting from the product's interaction with various CMS stakeholders in the circular value network is traced throughout its multiple lifecycles.

A transition towards circular manufacturing systems (CMS) has brought awareness of untapped economic and environmental benefits for the manufacturing industry. Conventional manufacturing systems already present a high level of complexity in terms of physical flows of materials and products as well as information and financial flows linked to them. Closing the loop of materials and products through multiple lifecycles, as proposed in CMS, increases this complexity manifold. To support practitioners in implementing CMS through enhanced decision-making, this research studies CMS from a complex adaptive systems (CAS) perspective and proposes to exploit methods and tools used in the study of CAS to characterise, model and analyse CMS. By viewing CMS as CAS composed of autonomous, interacting agents, this research proposes a multi-method model architecture for modelling and simulating CMS. The different CMS stakeholders are modelled individually as autonomous agents by integrating agent-based, discrete-event, and/or system dynamics modules within each agent to capture their diverse and heterogeneous nature. The applicability of the proposed multi-method approach is illustrated through a case study of a white goods manufacturing company implementing CMS in practice. This case study shows the relevance and feasibility of the proposed multi-method approach as a decision support tool for the systemic exploration and quantification of CMS. It also shows how a transition towards CMS necessitates a lifecycle approach in terms of costs, revenues and environmental impacts to identify hotspots and, therefore, design circular systems that are viable in both economic and environmental terms. In fact, the analyses of the simulation results indicate how decisions in terms of business models, product design, and supply chain affected the CMS performance of the case company. For instance, implementing a service-based model led to a high number of usecycles (on average six usecycles per washing machine), which, in turn, led to high lifecycle costs and emissions due to more frequent transportation and recovery operations. Similarly, the deployment of long-lasting washing machines, which is a core principle of CMS, led to high manufacturing costs. Due to the high initial costs and a time mismatch between revenues and costs in the service-based model, it required a longer time for the company to reach the break-even point (approximately 23 months). Overall, the case study shows that multi-method simulation modelling can provide decision-making support for a successful implementation of CMS.

Life cycle assessment (LCA) is used frequently as a decision support tool for evaluating different design choices for products based on their environmental impacts. A life cycle usually comprises several phases of varying timespans. The amount of emissions generated from different life cycle phases of a product could be significantly different from one another. In conventional LCA, the emissions generated from the life cycle phases of a product are aggregated at the inventory analysis stage, which is then used as an input for life cycle impact assessment. However, when the emissions are aggregated, the temporal variability of inventory data is ignored, which may result in inaccurate environmental impact assessment. Besides, the conventional LCA does not consider the environmental impact of circular products with multiple use cycles. It poses difficulties in identifying the hotspots of emission-intensive activities with the potential to mislead conclusions and implications for both practice and policy. To address this issue and to analyze the embedded temporal variations in inventory data in a CE context, the paper proposes calculating the emission intensity for each life cycle phase. It is argued that calculating and comparing emission intensity, based on the timespan and amount of emissions for individual life cycle phases, at the inventory analysis stage of LCA offers a complementary approach to the traditional aggregate emission-based LCA approach. In a circular scenario, it helps to identify significant issues during different life cycle phases and the relevant environmental performance improvement opportunities through product, business model, and supply chain design.

Modern manufacturing industry calls for a new generation of production system with better interoperability and new business models. As a novel information technology, Cloud provides new service models and business opportunities for manufacturing industry. In this research, recent Cloud manufacturing and Cloud robotics approaches are reviewed. Function block-based integration mechanisms are developed to integrate various types of manufacturing facilities. A Cloud-based manufacturing system is developed to support ubiquitous manufacturing, which provides a service pool maintaining physical facilities in terms of manufacturing services. The proposed framework and mechanisms are evaluated by both machining and robotics applications. In practice, it is possible to establish an integrated manufacturing environment across multiple levels with the support of manufacturing Cloud and function blocks. It provides a flexible architecture as well as ubiquitous and integrated methodologies for the Cloud manufacturing system.