1,720,966 research outputs found
The resource efficiency in sustainable production system: Monitoring consumptions, reducing waste, and reusing them as raw materials
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
Economic sustainability under supply chain and eco-industrial park concurrent design
Full text linkFrom a systemic point of view, the environmental efforts of single companies to achieve sustainable economic and environmental development are not enough because of the economic difficulty of reaching both zero-waste production state and high level of resource efficiency. This work focuses on payback period as a commitment keeping mechanism to ensure network stability at least until the recovery of the investment made for value creation from waste. A scenario analysis is proposed to investigate how the characteristics of each stakeholder within a network can affect the economic sustainability of the others
Integrating buffer “stock” and buffer loops in an assembly line with conveyors: An automotive case study
No full textThe degree of automation in manufacturing systems, along with the characteristics of job handling and transport between workstations, and the product cycle time, determine the most suitable job handling system for each line. Conveyor systems allow for the management of re-entrant flows at the same workstations and more flexible system architecture through carousels, which also serve as a buffer loop to accommodate jobs awaiting machine availability. This paper explores the role of buffer stocks and blocking after service mechanisms, task allocation within the system, and operational characteristics to tackle the assembly line balancing problem in a fully automated assembly line interconnected by conveyors through discrete event simulation. Scenario analysis is employed to assess the impacts of constraining job flows through the conveyors on: fluctuations in throughput from shift to shift, its variability, and the critical WIP threshold for the CONWIP logic
Implementing Job Sequencing in a CONWIP fully automated assembly line
No full textElectric vehicle production poses several challenges from the manufacturing point of view due to the uncertainty in the price and availability of raw materials and the frequent fluctuations of market demand. Moreover, mass customisation requires flexible and reconfigurable manufacturing systems, while the automation of the assembly lines to achieve a higher throughput rate and the complexity of job handling require conveyors and carousels. This paper investigates the implementation of job sequencing policies through conveyor loops to improve the flexibility and reconfigurability of a realistic CONWIP assembly line while avoiding upstream and downstream variability propagation. Scenario analysis evaluates how different job sequencing strategies and WIP control can impact the average and standard deviation of the shift throughput, the average job flow time, and the probability of deadlocks on an assembly line for stators of electric engines
Circular economy at scheduling level: influencing factors and impacts on system performance
No full textIn manufacturing systems, Circular economy (CE) strategies to recover returned end-of-life prod-ucts can reduce raw material purchasing costs and lead times while improving environmental performance. However, CE strategies may undermine production planning, control, and inventory management activities, and there is a lack of scientific evidence about the impact on work-in-progress (WIP) and overall performance. This paper uses Discrete Event Simulation to analyse the factors influencing the exploitation of returned products under different CE strategies and priority rules. The experiments investigate the impacts on makespan, virgin raw material consumptions, and WIP at the scheduling level in a realistic production and assembly system where production is coupled with disassembly, repairing, remanufacturing, and reusing. The results highlight the importance of production control strategies in limiting the negative impacts of CE strategies on WIP, makespan,and materials consumption. Moreover, frequent rescheduling is required due to the high variability affecting the systems implementing CE strategies
A multi-objective tabu search algorithm for product portfolio selection: A case study in the automotive industry
No full textVariability propagation in manufacturing systems: the impact of the processing time distribution
Full text linkIn manufacturing and service systems, the negative effects of variability propagation are usually addressed through approximation models and other tools, such as simulation and optimization algorithms. This paper investigates the conditions in which these approaches are ineffective, and considering only the mean and variance of the processing time distribution is misleading. A scenario analysis deepens the impacts of considering the entire processing time distribution (beyond its mean and variance) on the inter-departure times in balanced and unpaced lines modeled through Discrete Event Simulation. The results correlate the impacts on variability propagation of approximating the processing time distribution with system characteristics such as utilization levels, line sizes, and inter-arrival and processing time variability. Production planning approaches can benefit from these results to reduce variability propagation, particularly in flexible and reconfigurable manufacturing systems, largely adopted in Industry 4.0, that can highly influence processing time distributions by varying product mix and line configuration
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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