1,721,152 research outputs found
Radon entry models into buildings vs. environmental parameters, building shape and types of foundations
No full textMany studies have been carried out around the world to identify the carcinogenic risk associated with human exposure to air pollution and, nowadays, epidemiological evidences are the way to characterize the risk. Human exposure to naturally occurring ionizing sources is one of the main risks highlighted by the WHO. There is still a great need to make the population aware of this risk, to avoid unaware exposure. For decades, the radon entry has been studied through diagnostic measurement techniques, designing efficient mitigation systems.
The rate of radon entry into indoor air also varies with climatic conditions, such as rain, which alters the soil conditions and thus the flow of gas through the soil to the building shell.
Environmental parameters and building specific shape need to be examined to quantify their influence for radon entry. Several mechanisms are responsible: the dominant ones are the "stack effect" driven by temperature differences between the indoors and the outdoors, the effect of wind on the building shell, the operation of mechanical ventilation systems which distribute heated or cooled air throughout the house and each types of foundation which connects the building to the ground.
Italy is a geologically fragile Country, constantly hit by earthquakes; this allowed to develop over the centuries, safer building strategies. Most of the Italian building heritage, in over 7900 Municipalities, consists of masonry buildings, often made up of local materials with a high radium content. The purpose of this article is to evaluate and analyse how environmental, anthropic and constructive factors can influence radon entry models into buildings. Understandings of the various mechanisms that drive radon into buildings permit the development of specific technologies aimed to limit the radon entry rate and satisfy the Council Directive 2013/59/EURATOM requirement
Piattaforma (autocentrante) con dispositivo incorporato per la misura della forza di bloccaggio durante la lavorazione
No full textValutazione Multicriteri di tecniche di Rapid Prototyping con il metodo Analitic Hierarchy Process (AHP)
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Experimental and Numerical Appraisal of Self-Piercing Riveting
No full textSelf-piercing riveting (SPR) has become an interesting alternative joining technique for difficult to weld materials. A limitation of this technology is still the heavy experimental procedure needed for joint optimisation. In this paper, an experimental activity on Al6082-T4 sheet metal samples has been conducted to achieve a better understanding of the process. The joining process and the tensile tests have then been simulated using a FE code to predict deformed shape, failure mechanism (e.g. crack propagation, rivet pull-out) and shear resistance of the joint. Results show how this procedure can be a powerful tool for joint optimisatio
High Speed Machining: Tool Performance and Surface Finish in Steel Turning
No full textThe main design principles and specifications of an experimental vertical boring mill built for high speed turning tests (up to over 100 m/s) are described, and some results of an investigation on turning steel with ceramic tool within a 15 to 50 m/s cutting speed range are discussed. Data on single and combined effects of machining parameters on surface finish, tool life, chip formation and cutting power were obtained in the tests, and their significance is assesse
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