FlowSort-GDSS:a novel group multi-criteria decision support system for sorting problems with application to FMEA

Failure mode and effects analysis (FMEA) is a well-known approach for correlating the failure modes of a system to their effects, with the objective of assessing their criticality. The criticality of a failure mode is traditionally established by its risk priority number (RPN), which is the product of the scores assigned to the three risk factors, which are likeness of occurrence, the chance of being undetected and the severity of the effects. Taking a simple "unweighted" product has major shortcomings. One of them is to provide just a number, which does not sort failures modes into priority classes. Moreover, to make the decision more robust, the FMEA is better tackled by multiple decision-makers. Unfortunately, the literature lacks group decision support systems (GDSS) for sorting failures in the field of the FMEA. In this paper, a novel multi-criteria decision making (MCDM) method named FlowSort-GDSS is proposed to sort the failure modes into priority classes by involving multiple decision-makers. The essence of this method lies in the pair-wise comparison between the failure modes and the reference profiles established by the decision-makers on the risk factors. Finally a case study is presented to illustrate the advantages of this new robust method in sorting failures

Multiple Criteria Assessment of Insulating Materials with a Group Decision Framework Incorporating Outranking Preference Model and Characteristic Class Profiles

We present a group decision making framework for evaluating sustainability of the insulating materials. We tested thirteen materials on a model that was applied to retrofit a traditional rural building through roof's insulation. To evaluate the materials from the socio-economic and environmental viewpoints, we combined life cycle costing and assessment with an adaptive comfort evaluation. In this way, the performances of each coating material were measured in terms of an incurred reduction of costs and consumption of resources, maintenance of the cultural and historic significance of buildings, and a guaranteed indoor thermal comfort. The comprehensive assessment of the materials involved their assignment to one of the three preference-ordered sustainability classes. For this purpose, we used a multiple criteria decision analysis approach that accounted for preferences of a few tens of rural buildings' owners. The proposed methodological framework incorporated an outranking-based preference model to compare the insulating materials with the characteristic class profiles while using the weights derived from the revised Simos procedure. The initial sorting recommendation for each material was validated against the outcomes of robustness analysis that combined the preferences of individual stakeholders either at the output or at the input level. The analysis revealed that the most favorable materials in terms of their overall sustainability were glass wool, hemp fibres, kenaf fibres, polystyrene foam, polyurethane, and rock wool

Otimização de uma linha de montagem de caixas de velocidades da Renault Cacia

Mestrado em Engenharia e Gestão IndustrialO presente estudo baseia-se na otimização de uma linha de montagem de caixas de velocidades para automóveis através de reduções de tempos de ciclo e da pilotagem de modos alternativos de produção. Uma vez que a Indústria Automóvel vive um ambiente de constante competição, a qualidade e a eficiência dos processos são dois dos principais requisitos competitivos que mais preocupam as empresas. No que diz respeito à otimização de tempos de ciclo, o objetivo é o aumento da cadência de produção identificando os postos de trabalhos mais críticos e melhorar a forma de operar dos mesmos, eliminando os principais desperdícios. No que diz respeito à pilotagem dos modos alternativos, o objetivo é garantir ganho de produtividade e de qualidade sempre que forem originadas falhas ou avarias na linha de produção, tendo em vista o atendimento às exigências dos clientes. Verifica-se também que a standardização dos procedimentos dos modos alternativos de produção contribuem significativamente para a diminuição dos impactos negativos das perturbações da linha de montagem. Ao serem formalizados, os modos alternativos de produção, são primeiro confrontados, recorrendo ao uso da ferramenta FMEA para sua deteção, de acordo com os seus modos de falha e meios de controlo. Este estudo tem como objetivo o aumento de cadência de produção, passando também pela diminuição das perdas diárias de produção.The present study is based on the optimization of an automobile’s gearbox assembly line by reducing the cycle time and through the piloting of alternative modes of production. Since the automotive industry is experiencing an environment of constant competition, the quality and the efficiency of the process are the two main competitive requisites that most concern the enterprises. Regarding the optimization of the cycle time, the goal is to increase the production rate by identifying the most critical workstations and to improve the way of operating it, eliminating the main wastes. In the piloting of alternative modes, the goal is to ensure that the productivity rises and quality is improved whenever occur failures or malfunctions in production line, with the ultimate purpose of meeting the customer requirements. Throughout the description of the case study, it is explicit that the standardization of the alternative modes procedures have a great contribution in the reduction of the negative impacts motivated by perturbations in the assembly line. To be formalized, the alternative modes are firstly confronted with the FMEA tool, according to their failure modes and control means. This study aimed to increase the production cadence while, at the same time, decreasing the daily production losses

On the modelling and design of environmentally friendly biochar production for soil application

Biochar production through pyrolysis of various agricultural wastes has the potential to effectively reduce waste disposal issues and mitigate the potential impact of global warming. This thesis firstly provided a comprehensive review of the state-of-the-art knowledge on the pyrolysis processing of agricultural waste, its influencing factors, and the multifunctional application of biochar. Meanwhile, machine learning modelling, life cycle assessment, multiple-objective optimization are reviewed in the context of advancing biochar production and applications, providing more effective means of optimising processes and assessing environmental impacts. However, existing studies tend to be targeted at individual machine learning models or environmental assessment approaches. From a time- and cost-saving perspective, the process operating parameters and the type of biomass must be appropriately selected to obtain the desired product yield and characteristics. It is necessary to determine the environmental performance of the process before deciding to apply the technology on a large scale. Thus, this thesis has innovatively developed a framework containing life cycle assessment method, machine learning modelling, multi-objective optimisation and multi-criteria decision making. Key aspects of the study included the comparison of machine learning methods for predicting the influences of agricultural waste compositions and process conditions on biochar production. Specifically, Multi-layer Perceptron Neural Network and Gaussian Process Regression models were compared in terms of their accuracy in predicting biochar yields and properties. An environmental impact assessment framework was developed by combining Machine Learning and Life Cycle Assessment to assess the carbon footprint of biochar production and soil application, highlighting the potential of biochar soil application to achieve negative carbon emissions. By combining Multi-Objective Optimization and Multi-Criteria Decision-Making techniques with Life Cycle Assessment, this study also developed a novel framework to optimise the biochar production process and analysis its environmental impact. Together, this research aimed to support the development of application-oriented biochar process pathways for agricultural waste management and low carbon development, promoting sustainable agricultural practices

Integrated Frameworks for Effective Multi-criteria Decision Making in Reliability Centred Maintenance of Industrial Machines

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