181 research outputs found
Uncorrected land-use planning highlighted by flooding: the Alba case study (Piedmont, Italy)
Alba is a town of over 30 000 inhabitants located along the Tanaro River (Piedmont, northwestern Italy) and is famous for its wine and white truffles. Many important industries and companies are based in Alba, including the famous confectionery group Ferrero. <br><br> The town suffered considerably from a flood that occurred on 5–6 November 1994. Forty-eight percent of the urban area was inundated, causing severe damage and killing nine people. After the flood, the Alba area was analysed in detail to determine the reasons for its vulnerability. <br><br> Information on serious floods in this area since 1800 was gathered from official records, state technical office reports, unpublished documents in the municipal archives, and articles published in local and national newspapers. Maps, plans and aerial photographs (since 1954) were examined to reconstruct Alba's urban development over the last two centuries and the planform changes of the Tanaro River. <br><br> The results were compared with the effects of the November 1994 flood, which was mapped from aerial photographs taken immediately after the flood, field surveys and eyewitness reports. <br><br> The territory of Alba was subdivided into six categories: residential; public service; industrial, commercial and hotels; sports areas, utilities and standards (public gardens, parks, athletics grounds, private and public sport clubs); aggregate plants and dumps; and agriculture and riverine strip. The six categories were then grouped into three classes with different flooding-vulnerability levels according to various parameters. Using GIS, the three river corridors along the Tanaro identified by the Autorità di Bacino del Fiume Po were overlaid on the three classes to produce a final map of the risk areas. <br><br> This study shows that the historic floods and their dynamics have not been duly considered in the land-use planning of Alba. The zones that were most heavily damaged in the 1994 flood were those that were frequently affected in the past and sites of more recent urbanisation. Despite recurrent severe flooding of the Tanaro River and its tributaries, areas along the riverbed and its paleochannels have been increasingly used for infrastructure and building (e.g., roads, a municipal dump, a prison, natural aggregate plants, a nomad camp), which has often interfered with the natural spread of the floodwaters. Since the 1994 flood, many remedial projects have been completed along the Tanaro and its tributaries, including levees, bank protection, concrete walls and floodway channels. In spite of these costly projects, some areas remain at high risk for flooding. <br><br> The method used, which considered historical data, river corridors identified by hydraulic calculations, geomorphological aspects and land-use planning, can indicate with good accuracy flood-prone areas and in consequence to be an useful tool for the coherent planning of urban expansion and the mitigation of flood risk
A new design approach to the use of composite materials for heavy transport vehicles
In order to keep or to reach a high level of competitiveness and performance of a product, it is necessary to explore all the possible solutions that allow the best compromise between costs and project requirements. By this point of view the study of alternative designs and/or materials to use, is an important aspect that can identify a new concept or way of thinking about a product. This paper presents how to make use of composite materials in the field of heavy vehicles transportation. A new semitrailer in composite material has been designed, using a methodical redesign approach and an optimisation process. The main innovation in this project is, besides the use of the Glass Fibre Reinforced Plastics (GFRPs), also a new topology of the vehicle frame; the designed semitrailer, in fact. has a monocoque structur
Effect of snow-covered ground albedo on the accuracy of air temperature measurements
open8Solar radiation is one of the main factors which introduce significant deviations between thermometers reading and true air temperature value. Techniques to protect the sensors from direct radiative influence have been adopted almost since the beginning of meteorological observations. Reflected radiation from a snow-covered surface can also cause extra warming to thermometers hosted in solar shields, which are not always optimised to protect the sensors from this further radiative heat transfer. This phenomenon can cause errors in near-surface temperature measurements results, with a relevant impact on the quality of data records and series. This study experimentally evaluates the effect of reflected radiation from a snow-covered surface on the accuracy of air temperature measurements. The investigation is based on the evaluation of temperature differences between pairs of identical instruments, positioned above ground covered by natural vegetation, with one instrument in snow-free conditions and the other above a snow-covered surface, at the same time and at the same site. The work involved a representative number of sensors and shields, in terms of different typologies, technologies and engineering solutions, from different manufacturers. A mountain site with acceptable field conditions, offering long-lasting snow presence to maximise data availability, was selected to perform the experiment. Quantities of influence, such as relative humidity, wind speed and direction and solar radiation (global and reflected), were constantly measured. The main findings of this work show that none of the involved instruments were immune to the extra heating due to the snow-reflected radiation. Excluding nighttimes and days of high wind or low incident radiation, the differences among sensors positioned above natural soil and identical ones exposed to snow albedo ranged up to more than 3 ∘C. Solar screens with forced ventilation showed a partially reduced effect compared to most of the naturally ventilated ones. A full data analysis is reported here, together with complete results and uncertainties.openhttps://doi.org/10.5281/zenodo.5126973Musacchio, Chiara; Coppa, Graziano; Begeš, Gaber; Hofstätter-Mohler, Christina; Massano, Laura; Nigrelli, Guido; Sanna, Francesca; Merlone, AndreaMusacchio, Chiara; Coppa, Graziano; Begeš, Gaber; Hofstätter-Mohler, Christina; Massano, Laura; Nigrelli, Guido; Sanna, Francesca; Merlone, Andre
Study of a constrained finite element elbow prosthesis: the influence of the implant placement
Background: The functional results of total elbow arthroplasty (TEA) are controversial and the medium- to long-term revision rates are relatively high. The aim of the present study was to analyze the stresses of TEA in its classic configuration, identify the areas of greatest stress in the prosthesis–bone–cement interface, and evaluate the most wearing working conditions. Materials and methods: By means of a reverse engineering process and using a 3D laser scanner, CAD (computer-aided drafting) models of a constrained elbow prosthesis were acquired. These CAD models were developed and their elastic properties, resistance, and stresses were studied through finite element analysis (finite element method—FEM). The obtained 3D elbow-prosthesis model was then evaluated in cyclic flexion–extension movements (> 10 million cycles). We highlighted the configuration of the angle at which the highest stresses and the areas most at risk of implant mobilization develop. Finally, we performed a quantitative study of the stress state after varying the positioning of the stem of the ulnar component in the sagittal plane by ± 3°. Results: The greatest von Mises stress state in the bone component for the 90° working configuration was 3.1635 MPa, which occurred in the most proximal portion of the humeral blade and in the proximal middle third of the shaft. At the ulnar level, peaks of 4.1763 MPa were recorded at the proximal coronoid/metaepiphysis level. The minimum elastic resistance and therefore the greatest stress states were recorded in the bone region at the apex of the ulnar stem (0.001967 MPa). The results of the analysis for the working configurations at 0° and 145° showed significant reductions in the stress states for both prosthetic components; similarly, varying the positioning of the ulnar component at 90° (− 3° in the sagittal plane, 0° in the frontal plane) resulted in better working conditions with a greater resulting developed force and a lower stress peak in the ulnar cement. Conclusion: The areas of greatest stress occur in specific regions of the ulnar and humeral components at the bone–cement–prosthesis interface. The heaviest configuration in terms of stresses was when the elbow was flexed at 90°. Variations in the positioning in the sagittal plane can mechanically affect the movement, possibly resulting in longer survival of the implant. Level of evidence:
Mechanical behavior of a sandwich with corrugated GRP core: numerical modeling and experimental validation
In this work the mechanical behaviour of a core reinforced composite sandwich structure isstudied. The sandwich employs a Glass Reinforced Polymer (GRP) orthotropic material for both the twoexternal skins and the inner core web. In particular, the core is designed in order to cooperate with the GRPskins in membrane and flexural properties by means of the addition of a corrugated laminate into the foamcore. An analytical model has been developed to replace a unit cell of this structure with an orthotropicequivalent thick plate that reproduces the in plane and out of plane behaviour of the original geometry.Different validation procedures have been implemented to verify the quality of the proposed method. At first acomparison has been performed between the analytical model and the original unit cell modelled with a FiniteElement mesh. Elementary loading conditions are reproduced and results are compared. Once the reliability ofthe analytical model was assessed, this homogenised model was implemented within the formulation of a shellfinite element. The goal of this step is to simplify the FE analysis of complex structures made of corrugatedcore sandwiches; in fact, by using the homogenised element, the global response of a real structure can beinvestigated only with the discretization of its mid-surface. Advantages are mainly in terms of time to solutionsaving and CAD modelling simplification. Last step is then the comparison between this FE model andexperiments made on sandwich beams and panels whose skins and corrugated cores are made of orthotropiccross-ply GRP laminates. Good agreement between experimental and numerical results confirms the validity ofthe proposed model
Immunohistochemical detection of aetiological agents of proliferative and necrotizing pneumonia in Italian pigs
Proliferative and necrotizing pneumonia (PNP) is a form of interstitial pneumonia that occurs in weaning and post-weaning pigs. PNP is characterized by hypertrophy and hyperplasia of type II pneumocytes and coagulative necrosis and granular debris within alveolar spaces. Canadian and European studies suggest that the porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are the main causes of the disease, but Aujezsky's disease virus (ADV) and swine influenza virus (SIV) have also been considered as potential aetiological agents. An immunohistochemical study was carried out on the lungs of 28 Italian pigs with PNP in order to evaluate the role of PRRSV, PCV2 and ADV in PNP lesions. PRRSV infection was identified in the lungs of 11 pigs, PCV2 in the lungs of four pigs and coinfection with both viruses in the lungs of eight pigs. Neither virus was detected in the lungs of the remaining five pigs. ADV antigen was not detected in any sample. The principle aetiological agent of PNP in Italy therefore appears to be PRRSV. Coinfection with PRRSV and PCV2 is characterized by more severe microscopical changes in affected lungs
Sequence types and pleuromutilin susceptibility of Brachyspira hyodysenteriae isolates from Italian pigs with swine dysentery: 2003–2012
Swine dysentery is a mucohaemorrhagic colitis of pigs caused by infection with Brachyspira hyodysenteriae. The disease can be controlled by treatment with antimicrobial agents, with the pleuromutilins tiamulin and valnemulin being widely used. In recent years, the occurrence of B.hyodysenteriae with reduced susceptibility to these drugs has been increasing. The aim of this study was to determine temporal changes in genetic groups and pleuromutilin susceptibility amongst B.hyodysenteriae isolates from Italy. Multilocus sequence typing (MLST) was performed on 108 isolates recovered from 87 farms in different regions of Italy from 2003 to 2012, and their minimum inhibitory concentrations (MICs) for tiamulin and valnemulin were determined. Logistic regression was performed to assess associations between susceptibility to the two antimicrobial agents and genetic group, year and region of isolation. The isolates were allocated to 23 sequence types (STs), with five clonal clusters (Ccs) and seven singletons. More than 50% of isolates were resistant to both pleuromutilins (MIC >2.0 μg/mL for tiamulin and >1.0 μg/mL for valnemulin). All 10 isolates in ST 83 were resistant; these were first isolated in 2011 and came from nine farms, suggesting recent widespread dissemination of a resistant strain. Significant associations were found between the proportion of pleuromutilin susceptible isolates and the genetic group and year of isolation. Although resistant isolates were found in all Ccs, isolates in Ccs 2 and 7 were over five times more likely to be susceptible than those in the other Ccs. A significant trend in the reduction of susceptibility over time also was observed
New insights in the relation between climate and slope failures at high-elevation sites
Climate change is now unequivocal; however, the type and extent of terrestrial impacts are still widely debated. Among these, the effects on slope stability are receiving a growing attention in recent years, both as terrestrial indicators of climate change and implications for hazard assessment. High-elevation areas are particularly suitable for these studies, because of the presence of the cryosphere, which is particularly sensitive to climate. In this paper, we analyze 358 slope failures which occurred in the Italian Alps in the period 2000–2016, at an elevation above 1500 m a.s.l. We use a statistical-based method to detect climate anomalies associated with the occurrence of slope failures, with the aim to catch an eventual climate signal in the preparation and/or triggering of the considered case studies. We first analyze the probability values assumed by 25 climate variables on the occasion of a slope-failure occurrence. We then perform a dimensionality reduction procedure and come out with a set of four most significant and representative climate variables, in particular heavy precipitation and short-term high temperature. Our study highlights that slope failures occur in association with one or more climate anomalies in almost 92% of our case studies. One or more temperature anomalies are detected in association with most case studies, in combination or not with precipitation (47% and 38%, respectively). Summer events prevail, and an increasing role of positive temperature anomalies from spring to winter, and with elevation and failure size, emerges. While not providing a final evidence of the role of climate warming on slope instability increase at high elevation in recent years, the results of our study strengthen this hypothesis, calling for more extensive and in-depth studies on the subject
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