Esplosioni ventate di idrogeno/aria in armadi di stoccaggio per bombole di gas industriale

Con questa tesi sperimentale si vuole riprodurre in laboratorio il comportamento di un armadio di stoccaggio per bombole di idrogeno nel caso si verifichi una deflagrazione interna, dovuta per esempio a una perdita accidentale. Verranno quindi acquisiti ed elaborati i dati dei test di esplosione per analizzare ciò che accade all'interno dell'apparecchiatura per diverse concentrazioni di idrogeno, diversi punti di innesco della combustione e due tipologie di dispositivi di sicurezza. Nella prima parte si descrive il fenomeno della deflagrazione ventata, quali sono i parametri più importanti per valutarne lo sviluppo e i metodi per limitarne le conseguenze. In seguito si illustra l'apparecchiatura sperimentale: la struttura che simula un armadio di stoccaggio, i vari sensori per la misura delle grandezze in gioco e i sistemi di acquisizione ed elaborazione dati. Infine si riportano i risultati analizzando i grafici e spiegandone l'andamento. Il presente lavoro svolge anche la funzione di messa a punto e collaudo di tutta la strumentazione per ulteriori test sperimentali da effettuare nell'ambito del progetto europeo HySEA

HOMOGENEOUS HYDROGEN DEFLAGRATIONS IN SMALL SCALE ENCLOSURE. EXPERIMENTAL RESULTS

University of Pisa performed experimental tests in a 1 m3 facility, which shape and dimensions resemble a gas cabinet, for the HySEA project, founded by the Fuel Cells and Hydrogen 2 Joint Undertaking with the aim to conduct pre-normative research on vented deflagrations in real-life enclosures and containers used for hydrogen energy applications, in order to generate experimental data of high quality. The test facility, named Small Scale Enclosure (SSE), had a vent area of 0,42 m2 which location could be varied, namely on the top or in front of the facility, while different types of vent were investigated. Three different ignition location were investigated as well, and the range of Hydrogen concentration ranged between 10 and 18% vol. This paper is aimed to summarize the main characteristics of the experimental campaign as well as to present its results

An elasto-viscoplastic constitutive model for the rate-dependent behavior of polyvinylidene fluoride

To model the engineering performance of components made of polyvinylidene fluoride (PVDF), the 3D elasto-viscoplastic Eindhoven glassy polymer (EGP) model is extended to describe the rate-dependent behavior of PVDF. Careful analysis of the intrinsic behavior of PVDF revealed that the postyield compressive response shows a strain rate-dependence that evolves with increasing deformation. The extension of the constitutive model captures the deformation-dependent evolution of the activation volume and the rate-factor, which describes the driving stress. Given the significant temperature-dependent behavior, the model has been characterized for different temperatures (23, 55 and 75 °C). The accuracy of the model has been validated by means of tension and creep experiments at these temperatures. The constitutive model is implemented in finite element simulations and the results are compared with the experiments. It is shown that the proposed model allows for an accurate prediction of the short- and long-term rate-dependent behavior of PVDF.</p

Assessing Cancer Risk from Heavy Metals in Recycling Waste Electrical and Electronic Equipment: Preliminary Results from the WEENMODELS European Life Programme

Introduction The growing amount of waste derived from electrical and electronic equipment (WEEE) poses significant challenges to waste management, due to the presence of toxic chemicals with environmental and health implications for the general population and for occupationally-exposed workers. Methods Based on an toxicological and epidemiologic evaluation, we carried out a health risk assessment to evaluate the cancer risk deriving from environmental and occupational exposure to heavy metals released during different WEEE recycling procedures (electronic scrap in blister copper, treatment of metals recovery in copper smelter, treatment of shredding, pyrometallurgical treatment of Li-ion battery). We considered the typical WEEE production in a municipality of 150.0000 inhabitants, carrying out a Life Cycle Assessment. Outdoor (1 square km around a treatment plant) and indoor (for a factory volume of 3200 m3) emissions generated during the WEEE recycling procedures were computed. In particular, we estimated the amount of Cd, Ni and As inhaled by the potentially exposed population. We computed the cancer risk due to inhalation of these heavy metals in residents and workers using the methodology proposed by the California Office of Environmental Health and Hazard Assessment Results For the metals considered, our results showed negligible cancer risk (from 2,21x10-11 to 4,31x10-08) for the general population around the plant. On the converse, occupational exposures linked to specific procedures were associated with a cancer risk of 1,42x10-3 for workers in the shredding procedures mainly due to Ni exposure, and of 4,68x10-4 for workers with electronic scrap and exposed to As. Conclusions Based on our preliminary results from an integrated toxicological and epidemiologic approach, WEEE life cycle may be linked to health risks for workers in the recycling procedures, while it does not seem to adversely affect health of the general population around the treatment plants

CANCER RISK FROM HEAVY METAL EXPOSURE IN RECYCLING WASTE OF ELECTRICAL AND ELECTRONIC EQUIPMENT: PRELIMINARY RESULTS FROM THE WEEENMODELS EUROPEAN LIFE PROGRAM

Background and objectives: When electrical and electronic equipment reaches its end of life, it becomes ‘Waste Electrical and Electronic Equipment’ (WEEE). The growing amount of this type of waste has posed significant challenges to waste management, since WEEE contains a whole range of toxic chemicals having relevant environmental and health implications. The WEEE life cycle may expose the general population and workers to various toxic chemicals, such as heavy metals. We conducted a health risk assessment to evaluate the cancer risk derived from environmental and occupational exposure to trace elements from different recycling procedures (electronic scrap in blister copper, treatment of metals recovery in copper smelter, treatment of shredding, pyrometallurgical treatment of Li-ion battery). We considered the typical production of WEEE in a municipality of 150.0000 inhabitants, where a Life Cycle assessment (LCA) was carried out. Methods: Outdoor (1km2 around a WEEE treatment plant) and indoor (factory volume of 3200m3) emissions generated from the above-mentioned procedures were computed, to perform a health risk assessment for occupationally-exposed workers and for the general population around the plant. Dose of the heavy metals cadmium, nickel, arsenic inhaled by the potentially exposed population was estimated using the values obtained through a toxicological model. Cancer risk due to inhalation was calculated using the method proposed by the California Office of Environmental Health and Hazard Assessment. Results and Conclusions: For the heavy metals considered, generated from WEEE treatment, these preliminary results show negligible cancer risk for the general population. On the converse, some risks may be present for occupational exposures linked to specific procedures (from cancer risk of 1,42x10-3 for men working in shredding procedure and exposed to nickel to cancer risk of 4,68x10- 4 for women working with electronic scrap and exposed to arsenic)

Early life of Neanderthals

The early onset of weaning in modern humans has been linked to the high nutritional demand of brain development that is intimately connected with infant physiology and growth rate. In Neanderthals, ontogenetic patterns in early life are still debated, with some studies suggesting an accelerated development and others indicating only subtle differences to modern humans. Here we report the onset of weaning and rates of enamel growth using an unprecedented sample set of three late (~70-50 ka) Neanderthals and one Upper Paleolithic modern human from Northeastern-Italy via spatially-resolved chemical/isotopic analyses and histomorphometry of deciduous teeth. Our results reveal that the modern human nursing strategy, with onset of weaning at 5-6 months, was present among these Neanderthals. This evidence, combined with dental development akin to modern humans, highlights their similar metabolic constraints during early life and excludes late weaning as a factor contributing to Neanderthals' demise

Italian guidelines for primary headaches: 2012 revised version

The first edition of the Italian diagnostic and therapeutic guidelines for primary headaches in adults was published in J Headache Pain 2(Suppl. 1):105–190 (2001). Ten years later, the guideline committee of the Italian Society for the Study of Headaches (SISC) decided it was time to update therapeutic guidelines. A literature search was carried out on Medline database, and all articles on primary headache treatments in English, German, French and Italian published from February 2001 to December 2011 were taken into account. Only randomized controlled trials (RCT) and meta-analyses were analysed for each drug. If RCT were lacking, open studies and case series were also examined. According to the previous edition, four levels of recommendation were defined on the basis of levels of evidence, scientific strength of evidence and clinical effectiveness. Recommendations for symptomatic and prophylactic treatment of migraine and cluster headache were therefore revised with respect to previous 2001 guidelines and a section was dedicated to non-pharmacological treatment. This article reports a summary of the revised version published in extenso in an Italian version

Time dependent fracture behaviour of a carbon fibre composite based on a (rubber toughened) acrylic polymer

The fracture behaviour of continuous carbon fibre laminates based on plain and rubber-toughened acrylic resins was investigated focusing on the influence of rate and temperature. The tensile behaviour of the two matrices was also characterized for subsequent analysis. In all cases the experimental window was extended by applying the time-temperature equivalence postulate. Fracture toughness at varying crack propagation rate turned out to have opposite trends for the two matrices. For the plain acrylic resin, a monotonically increasing trend with crack rate was found in agreement with viscoelastic fracture theories. For the rubber-toughened resin the change of the failure mechanisms occurring at the crack tip, resulted in a monotonically decreasing trend for increasing crack rate. Rate and temperature effects were analysed in terms of volumetric strain during tensile tests. Composites turned out to be more resistant to crack propagation than the relevant matrices in both cases. Delamination fracture toughness turned out to have the same dependence on crack rate for rubber toughened matrix only. For composites based on the plain resin, no effect of crack rate on delamination fracture toughness was observed