1,721,178 research outputs found
Towards a mesoscale model of geopolymers: Interaction potential from the molecular scale
No full textGeopolymers are alumino-silicate hydrates obtained by reaction of an alumino-silicate source (e.g. metakaolin or fly ash) with alkali solution. Geopolymer-based binders are less environmentally impacting than ordinary cement, but their implementation in the construction field is still limited and requires a better understanding of the nanoscale origin of their mechanical properties. This understanding can be advanced with new simulations based on interaction-driven aggregation of nanoparticles, similar to what has happened in the last decade in the field of traditional cement science. This paper introduces a pathway to develop such a model starting from recent molecular models of geopolymers, which allow to compute the interaction potentials needed for the larger mesoscale. Interaction potential parameters are presented in this work as a function of different particle sizes, targeting experimentally-observed ranges of particle sizes and porosity. Overall, this work opens new opportunities to understand the linkage between mesostructure and engineering properties of geopolymers, with the aim of supporting their commercialisation as alternative cements and, in this way, contributing to the development of a greener economy
The Indoor Environmental Quality: A TOPSIS-based approach with indirect elicitation of criteria weights
No full textThe Indoor Environmental Quality (IEQ) assessment is a hot topic both for designers of industrial buildings and for academics since it has been proven to affect workers’ productivity. Despite the advantages of indirect eliciting approaches, only direct eliciting is used in the literature to assign weights to the main risks included in the IEQ assessment, i.e., those referring to the thermal comfort, visual comfort, acoustic comfort and indoor air quality. In order to bridge this gap and in line with the drivers of the human-centric industrial revolution, we have developed an indirect eliciting approach based on logistic regression and integer optimization that indirectly derives the aforementioned weights per worker (i.e., individual weighting) on the basis of the overall comfort perceived by him/her in different reference scenarios. These weights are then used to compute a TOPSIS-based risk measure that maps the aggregated, individual and dynamic risks to which the worker is subjected over time. A real case study is used to validate our proposal. The achieved results highlight the superiority of our indirect eliciting approach compared to the Analytical Hierarchic Process in reconstructing the overall comfort perceived by workers, as well as that age plays a crucial role to assign weights to the main risks included in the IEQ
Set up a supply chain observatory through the comparison of multi-criteria parsimonious methods
Full text linkTHE PLANT LAYOUT OF A FOUNDRY: CONSTRAINTS, OPERATIVE GUIDELINES AND A CASE STUDY
No full textThe problem of studying a plant layout is frequently tackled in literature. Nevertheless, approaches specifically dedicated to predefined market fields are rare. Usually, methodologies available for a wide variety of companies are studied and adopted, disregarding those details typical of each economical sector. On the contrary, in this paper, customized guidelines for the design of a plant layout of a foundry are proposed, in order to support such a critical productive environment where automated equipment, characteristic of Industry 4.0, are integrated with manual activities. Specifically, the casting area is studied. The long term design is supported by a medium term analysis, focused on the products turnover into the casting moulds. The application to a real life case study is finally described in order to assess the performance of the proposed approach
The Importance of Awareness of Coronavirus Disease 2019 Clinical Syndrome by Plastic Surgeons
Full text linkIndoor Environmental Quality (IEQ): A Comparison between TOPSIS- and PROMETHEE-Based Approaches for Indirect Eliciting of Category Weights
Full text linkIndoor Environmental Quality (IEQ) has received a great deal of attention in recent years due to the relationship between worker comfort and productivity. Many academics have studied IEQ from both a building design and an IEQ assessment perspective. This latter line of research has mostly used direct eliciting to obtain weights assigned to IEQ categories such as thermal comfort, visual comfort, acoustic comfort, and indoor air quality. We found only one application of indirect eliciting in the literature. Such indirect eliciting operates without the need for imprecise direct weighing and requires only comfort evaluations, which is in line with the Industry 5.0 paradigm of individual, dynamic, and integrated IEQ evaluation. In this paper, we use a case study to compare the only indirect eliciting model already applied to IEQ, based on TOPSIS, to an indirect eliciting method based on PROMETHEE and to a classical direct eliciting method (AHP). The results demonstrate the superiority of indirect eliciting in reconstructing individual preferences related to perceived global comfort
An open innovation B2B web platform design: Application of the QFD approach for the definition of its primary functions
No full textGlobal markets and the concept of innovation require modern companies to quickly adapt to two very relevant paradigms: digital innovation and open innovation. Therefore, the use of digital technologies and the development of open collaboration networks have radically changed the nature of the organisation of innovation and of the managerial approach and strategic choices. The objective of this paper is to describe the approach adopted to define the main functionalities of a digital Business to Business (B2B) platform for the development of new commercial collaborations between Small and Medium-sized Enterprises (SMEs). The approach of Quality Function Deployment and its House of Quality tool have been applied to support the combination of customer and technical needs. The prioritisation of the technical characteristics of the platform has identified in the ‘system for managing orders’ and ‘systems to speed up processes’ the main functions to be developed with greater attention within the platform
Roadway tunnels: A critical review of air pollutant concentrations and vehicular emissions
No full textAir quality is a widespread problem with the presence of pollutants in indoor and outdoor environments that generate significant consequences for the population, ecosystems and exposed materials. Vehicular traffic is one of the main sources of air pollutants and, therefore, needs to be studied and analysed in detail. This review reported the results of studies conducted on tunnels, in particular for the measurement of concentrations and the definition of emission factors. The characteristics of the tunnels, available ventilation systems, type of vehicular traffic, and geographical distribution, in addition to concentrations and emission factors, are discussed. Light-duty vehicles are the most frequent category in the case studies. Between the fuels used, gasoline is by far the most widespread. Pollutant concentrations concentrations can reach very high levels. For example, atmospheric particulates (with an aerodynamic diameter of 10 μm) and nitrogen dioxide have also reached levels of 1490 μg/m3 and 4982 μg/m3, respectively
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