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The imperative shift toward sustainable development mandates a revolutionary transformation in the transportation sector. While the transition from internal combustion engines to electric motors represents a pivotal step, its ecological impact may fall short of expectations. This undertaking is motivated by the recognition that a truly impactful transition necessitates intricate strategies, addressing resource consumption during manufacturing and minimizing post-use waste. This literature review is dedicated to enhancing the framework of circular strategies within the realm of electric motors, with a specific focus on remanufacturing. The objective is to cultivate a conscientious approach to product development, primarily centered on the four key pillars of circularity: reuse, remanufacture, upgrade, and recycle. The primary goal is to furnish a comprehensive overview of the myriad possibilities associated with reusing products, either in parts or as a whole. Upon introducing the circular approach, this review underscores pivotal enabling technologies essential for a successful transition. These include inspection, disassembly, rewinding, and demagnetization. The ensuing discussion delves into the technological challenges faced and presents cutting-edge solutions poised to redefine the landscape. The concluding section extends the perspective to the future, introducing innovative studies and solutions still in their developmental stages. This review is tailored for decision-makers, policymakers, and researchers, providing them with a valuable overview and facilitating discussions to propel our society toward a sustainable and responsible future in electric motor technology. [ABSTRACT FROM AUTHOR]

The Buffer Allocation Problem is a well-known optimization problem aiming at determining the optimal buffer sizes in a manufacturing system composed by various machines decoupled by buffers. This problem still has scientific relevance because of problem complexity and trade-off between conflicting goals. Moreover, it assumes industrial relevance in reconfigurable manufacturing lines, where buffer sizes can be easily adapted to the production scenario. This work proposes a novel algorithm integrating performance evaluation and optimization by means of throughput cuts based on a linear approximation. Numerical results show the validity of the proposed approach with respect to the traditional gradient-based method. Moreover, an industrial case study integrating the proposed approach into a decision-support system for the buffer allocation and reallocation is analyzed. [ABSTRACT FROM AUTHOR]

This special issue of Flexible Services and Manufacturing is an outgrowth of the 11th International Conference held in Acaya, Italy sponsored by the organization Stochastic Models of Manufacturing and Service Operations (SMMSO). Service systems (non-manufacturing) papers in this volume demonstrate that their operations are strongly related to manufacturing system operations and methodologies. The first paper is concerned with a Maritime Shipping Birthing Allocation Problem (MBAP) and the latter paper with policies and analysis of influenza vaccine supply-chain intervention programs. [Extracted from the article]

Maintenance and production are frequently managed as separate activities although they do interact. Disruptive events such as machine failures may find the company unready to repair the machine immediately leading to time waste. Preventive Maintenance may be carried out and maintenance time reduced to the effective task duration, in order to prevent time waste. Companies and researchers have been focusing on policies able to mitigate the impact of Preventive Maintenance on system availability, by exploiting the knowledge about degradation profiles in machines and the joint information from the machine state and the buffer level. In this work, the mathematical proof of the optimal threshold-based control policy for Preventive Maintenance with inventory cost, maintenance cost, backlog cost is provided. The control policy is defined in terms of buffer thresholds and dependency of the thresholds on the degradation condition. The optimal control policy is proved to include a combination of switching points and hedging points, where the first ones activate the Preventive Maintenance for a given condition and the latter ones control the production rate in order to minimize the surplus. An extensive experimental campaign analyzes the impact of system parameters such as the Maintenance duration on the cost function. The results show that there exists cases in which the optimal policy is dominated by the effect of the hedging points or the switching points, alternatively. Therefore, the proposed method is used to provide suggestions to the management for operative decisions, in order to choose the policy fitting best the system. [ABSTRACT FROM AUTHOR]

A methodology is proposed to provide a guided process for modularization of manufacturing system components within the broader design process. The application focus is on manufacturing systems, including flow processes. Component clusters are formed by simultaneously considering physical-functional and strategic drivers that are fundamental to a more holistic partitioning of the system. The clustering algorithm now includes the ability to compel component unification or separation. A broad review of modularization methods was conducted to improve upon the state-of-the-art. Current methodologies can be difficult to use, are disjoint in their goals, lack objectivity, and do not produce externally repeatable solutions. The proposed methodology aims to improve upon these limitations by providing a step-by-step framework and integrating strategic and technical perspectives when clustering. The methodology is structured to guide the user toward a deeper understanding of the system, whether or not one is an expert, whereby the designer can focus more on the technical and strategic issues that should inform the modularization. A realistic case study for the modularization of a transportable fast pyrolysis plant was performed to evaluate the meaningfulness of the methodology's results. The methodology clustered components into modules consistent with the information provided to the model, reflecting what would be expected from a deep understanding of the system. [ABSTRACT FROM AUTHOR]

In engineering-to-order (ETO) or manufacturing-to-order (MTO) systems producing highly customized items, the high level of customization, together with long flow times, forces the production plan to be defined before information on items customization, and details on the manufacturing activities are completely disclosed. Due to the partial available information, the production plan must provide a robust schedule of the activities and of the resources utilization, trying to incorporate a certain degree of anticipation of uncertainty. This paper proposes a two-stage stochastic programming project scheduling approach to support production planning in ETO/MTO system. The approach provides a baseline production plan together with a set of revisions of the plan to react to the occurrence of uncertain events. A scenario-based approach is used to model the changes affecting the characteristics of the activities to be processed. The proposed approach is tested on random-generated instances and on a real manufacturing system producing machining centers. [ABSTRACT FROM AUTHOR]

Long- and medium-term production planning are tools to match production orders with resource capacity and that can also be used as a baseline for material procurement. The lack of a detailed schedule for the manufacturing operations, however, may cause difficulties in providing a proper material requirements planning and may affect the feasibility of the production plan itself. This paper proposes an approach, based on production process knowledge, to extract scheduling information from an aggregate production plan in order to support material procurement. The proposed approach is applied to an industrial case involving machining center production. [ABSTRACT FROM AUTHOR]

The paper proposes a decomposition method for evaluating the performance of transfer lines where machines can fail in multiple modes and can be repaired with non-exponential times. Indeed, while times to machine failure can be often modeled using exponential distributions with acceptable accuracy, times to repair are very rarely observed to be exponentially distributed in actual systems. This feature limits the applicability of existing approximate analytical methods to real production lines. In this paper, the discrete acyclic phase-type distribution is used to model the repair process, for each failure mode of the machines composing the system. The exact analysis of the two-machine system is used as a building block for the decomposition method, proposed to study multi-stage lines. Numerical results show the high accuracy of the developed method in estimating the average throughput and buffer levels. [ABSTRACT FROM AUTHOR]

The paper addresses the problem of fully using buffer spaces in manufacturing flow lines. The idea is to exploit recent technological devices to move in reasonable times pieces from a machine to a common buffer area of the system and vice versa. In such a way machines can avoid their blocking since they can send pieces to the shared buffer area. The introduction of the buffer area shared by all machines of the system leads to an increase of production rate as demonstrated by simulation experiments. Also, a preliminary economic evaluation on a real case has been carried out to estimate the profitability of the system comparing the increase of production rate, obtained with the new system architecture, with the related additional cost. [ABSTRACT FROM AUTHOR]

This paper presents an approximate analytical method for the performance evaluation of a production line with finite buffer capacity, multiple failure modes and multiple part types. This paper presents a solution to a class of problems where flexible machines take different parts to process from distinct dedicated input buffers and deposit produced parts into distinct dedicated output buffers with finite capacity. This paper considers the case of two part types processed on the line, but the method can be extended to the case of n part types. Also, the solution is developed for deterministic processing times of the machines which are all identical and are assumed to be scaled to unity. The approach however is amenable of extension to the case of inhomogeneous deterministic processing times. The proposed method is based on the approximate evaluation of the performance of the k-machine line by the evaluation of 2(k-1) two-machine lines. An algorithm inspired by the DDX algorithm has been developed and the validation of the method has been carried out by means of testing and comparison with simulation. [ABSTRACT FROM AUTHOR]

Loading in flexible manufacturing systems (FMSs) is affected by the characteristics of the FMS under analysis, by the type of plant where the FMS is introduced, and by the production planning hierarchy where the loading module operates. We propose an analysis of the various aspects that influence the problem formulation, identifying the alternatives available in real systems and possible future evolutions. We then provide a survey of different approaches proposed in the literature to tackle the loading problem. Articles are classified according to the type of FMS analyzed, the objective function, and the constraints. Finally, based on our analysis, we suggest some problem issues which need to be addressed, and also directions for future research. [ABSTRACT FROM AUTHOR]

The paper presents a new approach for estimating the throughput of a closed queueing network with exponential servers, finite buffer capacity and a blocking after service discipline. The problem is tackled by decomposing the network. The population constraint is enforced by requiring that the sum of the expected number of customers in the various subsystems is equal to the population size. Each subsystem is analyzed as an M/M/1/Ci + 1 queue with state-dependent arrival and service rates. The rationale behind this last assumption is that the behavior of the system at a given time is affected by the history of blockings and starvations. The results obtained by applying the proposed algorithm to a set of test problems show a good agreement with those obtained with simulation, the difference on the maximum throughput of the network being of the order of 3%. The obtained results also compare favorably with those described in the literature. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various papers within the issue on topics including development of a decomposition method for evaluation of production capacity of stochastic-capacity machines, performance of a multiproduct manufacturing system, and inventory minimization.