336 research outputs found
Predictive maintenance for monitoring performance decay of plaster converings according to the criteria of ISO 16686-7 code
The aim of the present work is the construction of the performance/time curve that characterizes and defines the aging of plaster coverings on tuff masonry, a widely used technical solution in the building stock of the city of Naples. 53 sample building were tested; these were selected according to a criteria of homogeneity of the technological characteristics of the support and covering material (tuff masonry + lime-cement plaster + acrylic paint). The year of construction of the buildings, as well as any problem occurred during the work realization, was acknowledged.
The described objective represents a result of indubitable utility and practical consequence, as it allows:
- the evaluation of the residual service life at the moment of the execution of field tests with fixed methodologies;
- the definition of the time thresholds for the execution of the most appropriate interventions, determined in a maintenance plan, in which predictive maintenance of course plays a fundamental role. The chosen methodology for the evaluation of performances, considering the indications of ISO 15686-7, is the infrared thermographic camera test, combined with close-up visual inspections and percussion tests.
The activities were carried out through the following main phases:
- defining the task;
- planning;
- examination;
- evaluation;
- reporting.
The results showed the possibility to create curves like the one represented in the annex B of the already quoted ISO 15686-7 and hence to define the decay with 5 performance degrees (no symptoms – slight symptoms – medium – strong symptoms – totally unacceptable, including collapse and malfunction), corresponding to an accurate quantification of the conditions of conservation, and that is mainly possible thanks to the output of the thermographic camera.
In relation to the results, different scenarios of planned maintenance for a period of 30 years have been hypothesized
Analisi multicriteria per la manutenzione dei rivestimenti intonacati
Il problema della più appropriata scelta di strategia manutentiva è di complessa risoluzione, in quanto coinvolge diversi aspetti, concomitanti ma tuttavia spesso contrastanti:
• quello economico “assoluto”, secondo il quale si tenderebbe ad eseguire quanto meno interventi possibile;
• quello economico “relativo”, secondo il quale attuare interventi di piccola entità ma più spesso, evita di dovere poi eseguire opere di maggiore impegno, che finiscono per coinvolgere anche altri componenti per i cosiddetti “guasti a catena”;
• quello della sostenibilità , secondo il quale alla scelta di materiali dal punto di vista di eco-compatibilità , non si deve evitare di abbinare considerazioni in termini di durabilità ;
• quello della sicurezza, che porterebbe ad evitare che nel ciclo di vita si raggiungano valori di prestazione troppo vicini al valore minimo ammissibile;
• quello della disponibilità , secondo il quale una rarefazione dell’attività manutentiva è meglio sopportata dai committenti/utenti, e dunque deve esistere un giusto rapporto fra ciclo di vita e durata dell’intervento manutentivo.
Tante e così diverse variabili in gioco determinano una complessità che può essere adeguatamente affrontata e risolta solo con analisi multicriteriali.
Nell’articolo si mettono a confronto 4 diverse strategie per la manutenzione di rivestimenti intonacati, mediante diversi metodi di analisi multi-criteria (TOPSIS, WSM, WPM, VIKOR), pervenendo a risultati di indubbio interesse per orientare le scelte di tecnici e proprietari di immobili
Safety assessment of scenarios triggered by accidental seawater immersion of lithium batteries in innovative naval applications
The request of lithium-ion batteries in naval applications features an increasing trend due to the need of high performance energy storage devices. Beside the hazard of runaway when the battery is crushed or overcharged, the naval environment poses additional safety issues due to the possible immersion with seawater of the battery room following accidental flooding. In such a case, seawater electrolysis may generate hydrogen and chlorine, thus giving rise to an explosive and toxic mixture in a confined environment. In this study, a quantitative safety assessment of the possible accidental scenarios induced by seawater electrolysis in battery rooms is performed. The analysis is based on i) the deterministic evaluation of the hazardous gases development according to a three-dimensional physically-based electrochemical model and ii) the discussion of possible prevention and mitigation measures. The dynamics of gas release and the time required to produce an explosive atmosphere are evaluated as a function of the level of seawater for a reference case study. The outcomes of the study support the safety assessment of accidental scenarios induced by seawater electrolysis in naval applications and provide indications on the effectiveness of hazard reduction measures. More specifically, the study reveals that a proper electric insulation of the surface of battery terminals represents a sensible mitigation strategy to reduce the severity of explosions in addition to the ventilation of the battery room
MULTICRITERIA ANALYSIS FOR CHOOSING MAINTENANCE STRATEGIES
The life cycle of building components can be managed according to different maintenance strategies, which mainly differ in performance and economic terms.
What is the most convenient among the possible scenarios? It has been shown in the past that the typology of maintenance interventions and the consequent periodicity are closely related to performance decay, and can lead to choices that, however, generally concern the purely economic sphere.
In this sense, it seems interesting to know the modalities of the performance decay, which may allow – even though for many components the "measurement" of its values is problematic - the construction of performance / time curves.
This result was possible, in other experiments conducted in the past, for one of the components to be considered most critical for the whole building (the plaster), thanks to a study that sampled 53 buildings with homogeneous characteristics (both from the technological point of view and from the era of realization), observed within 20 years.
This paper highlights that the only economic evaluation is not enough to identify the ideal solution, because – inter alia - there is a more suitable solution depending on the context framework in which the decision maker is operating. Commitment, budget, component typology, time span to consider, are the main factors influencing the choice, not ignoring design issues.
A Topsis multicriteria analysis is proposed, the results of which are an interesting starting point for define maintenance plans characterized by greater reliability, not only technical but also economical
LCC analysis for glued laminated timber components exposed in external
The aim of the experimentation is to characterize the performances of glued laminated timber components exposed to atmospheric agents, in the light of the concept of Life Cycle Cost, particularly emphasized in the Italian new legislation on public works.
In fact, it could be seen that the design of the construction details and the initial characteristics of glue laminated timber components, require a particular attention to avoid errors that may undermine the possibility to perform the structural functions for which, above all, this material it is dedicated.
The experimentation consisted of a series of tests aimed to identify the performance of glued laminated timber beams taken in site, after a work executed some years ago on a theatre built in Roman era, and to compare them with similarly manufactured new elements. The tests performed were thermography, ultrasound, Wood-Pecker penetrometer, mechanical characterization.
The results will be used to begin setting limits and conditions for outdoor use of glue
laminated timber, and assume a reliable life cycle, and consequently identify the most
appropriate maintenance strategy for the LCC
Ex vivo determination of bone tissue strains for an in vivo mouse tibial loading model
AbstractPrevious studies introduced the digital image correlation (DIC) as a viable technique for measuring bone strain during loading. In this study, we investigated the sensitivity of a DIC system in determining surface strains in a mouse tibia while loaded in compression through the knee joint. Specifically, we examined the effect of speckle distribution, facet size and overlap, initial vertical alignment of the bone into the loading cups, rotation with respect to cameras, and ex vivo loading configurations on the strain contour maps measured with a DIC system.We loaded tibiae of C57BL/6 mice (12 and 18 weeks old male) up to 12N at 8N/min. Images of speckles on the bone surface were recorded at 1N intervals and DIC was used to compute strains. Results showed that speckles must have the correct size and density with respect to the facet size of choice for the strain distribution to be computed and reproducible. Initial alignment of the bone within the loading cups does not influence the strain distribution measured during peak loading, but bones must be placed in front of the camera with the same orientation in order for strains to be comparable. Finally, the ex vivo loading configurations with the tibia attached to the entire mouse, or to the femur and foot, or only to the foot, showed different strain contour maps.This work provides a better understanding of parameters affecting full field strain measurements from DIC in ex vivo murine tibial loading tests
A Methodology for a Performance Information Model to support Facility Management
Current facility management practice relies on different systems which require new technologies to integrate and manage information more easily. Building information modeling offers a good opportunity to improve facility information management by providing a unified platform for various data sources rather than an intuitive information interface. Although current research trends reveal that there is a continuously growing interest in facility management aided by building information modeling, an integrated model is still hard to obtain. This paper aims at developing a novel methodology based on building information modeling and facility management systems integration, underpinned by a performance information model. The implementation process of a performance information model is described, including information technologies involved, the data and process requirements, and the building performance assessment methods used. A first pilot case-study has been conducted with regards to surgery rooms in healthcare buildings. The proposal can support condition-based maintenance work schedule, as well as the achievement of organizational, environmental, and technical requirements. Among the practical implications found: Improved technological and environmental performances assessment; better visualization of building condition; improved decision-making process; facilitated maintenance tasks planning and maintenance records management
Sistema de gestão ambiental: aspectos teóricos e análise de um conjunto de empresas da região de Campinas, SP.
Parte I. Normas Ambientais: aspectos teĂłricos: Normas Ambientais; Normas da SĂ©rie ISO 14.000. Sistema de GestĂŁo Ambiental (SGA) - NBR-ISO 14.001; PrincĂpio 1 - PolĂtica Ambiental; PrincĂpio 2 - Planejamento; PrincĂpio 3 - Implementalção e Operação. PrincĂpio 4 - Verificação e Ação Corretiva; PrincĂpio 5 - Análise CrĂtica. Parte II. DiagnĂłstico de GestĂŁo Ambiental: análise de um conjunto de empresas da regiĂŁo de Campinas; Caracterização, levantamento de dados e informações; Metodologia de pesquisa; Resultados e discussĂŁo; ConclusĂŁo.bitstream/CNPMA/5813/1/documentos_39.pd
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