350 research outputs found
Verso una strada che si spiega da sè
No full textIl contributo si focalizza sull'analisi di usabilità di alcune strade e sui possibili interventi ad implementazione della stessa
8-Node solid-shell elements selective mass scaling for explicit dynamic analysis of layered thin-walled structures
No full textTo overcome the issue of spurious maximum
eigenfrequencies leading to small steps in explicit time integration,
a recently proposed selective mass scaling technique,
specifically conceived for 8-node hexahedral solid-shell elements,
is reconsidered for application to layered shells,where
several solid-shell elements are used through the thickness
of thin-walled structures. In this case, the resulting scaled
mass matrix is not perfectly diagonal. However, the introduced
coupling is shown to be limited to the nodes belonging
to the same fiber through the thickness, so that the additional
computational burden is almost negligible and by far
compensated by the larger size of the critical time step. The
proposed numerical tests show that the adopted mass scaling
leads to a critical time step size which is determined by the
element in-plane dimensions only, independent of the layers
number, with negligible accuracy loss, both in small and
large displacement problems
La Probabilità nel Progetto MathOnline
No full textGli autori hanno collaborato a definire e implementare tutte le fasi della progettazione di un'unità didattica del progetto-ponte "MathOnline" offerto dal centro METID del Politecnico di Milano alla fruizione di studenti e docenti delle scuole superiori italiane
The impact of classroom training on road hazards perception in a Tanzanian Secondary School
No full textIn Tanzania, in 2014, 3,760 people were killed on the roads, and 14,530 were injured. The possible
reasons are to be investigated around the fatalistic beliefs common in Africa, and the lack of effective
road safety education in schools. The present study was conducted in a Secondary School in Tanzania
in 2016. In January 212 students received a two-hour training held by a traffic psychologist and the
training effectiveness was assessed through Static Hazard Perception Test (SHPT), that was submitted
before the training and twice after the training, in February and in November (follow up). Aim of the
training was to open a ‘window of thought’ on simple concepts such as road risk and danger, starting
from the idea that reflecting on these concepts would help students to improve their awareness of the
dangers that can be found on the road. Pre-post repeated measures analysis of variance (ANOVA)
yielded a principal effect of the training on hazard perception (F (1,210)=27.519, p<.001). Data
collected in the follow up show that the level of hazards perception at eight months after the training
was lower than immediately after the training (repeated measures ANOVA: F (1,210)=11,700, p<.005)
but higher than before the training (repeated measures ANOVA: F (1,210) =85,685, p<.001). Although
there are some limits, the results suggest that a traffic psychology training about road safety, based on
students’ reflection about their experience as road users, may help to better recognize hazards on the
road and to maintain such ability forward. Such results have implications for more effective road safety
education in Africa
Blade cutting of thin walled structures by explicit dynamics finite elements
No full textIn cohesive crack propagation induced by blade cutting, it is necessary to consider the blade radius of curvature as a characteristic length additional to the shell thickness and to the cohesive process zone length, which usually characterize crack propagation in thin walled structures. When the finite element simulation of a blade cutting process is considered, these three lengths need to be properly resolved. The blade radius of curvature can be orders of magnitude smaller than the shell thickness and the cohesive process zone. Furthermore, the transition from a continuous mesh to a mesh containing a crack with a cohesive interface is well known to be critical for solution accuracy. Nodal equilibrium is in general violated during the transition, with subsequent generation of spurious stress oscillations that, in view of the non-reversible nature of the problem, can lead to significant inaccuracies in the stress response. The smallest length, i.e. the blade radius of curvature, is here resolved using the so called directional cohesive element model as in Pagani and Perego (CMAME 285:515–541, 2015), while the structural thickness is modeled using solid-shell elements. The concept of directional cohesive elements is here extended for application to the case of cutting by scissors. As for the cohesive process zone length, different modeling options are discussed in terms of their capability to reduce the spurious oscillations and to provide an accurate estimate of the cutting parameters. Numerical tests are presented to validate the proposed modeling strategies. © 2017, Springer Science+Business Media B.V
The perception of risk and safety in urban mobility from the perspective of blind people. An exploratory study.
No full textAccording to the 11th Sustainable Development Goal in the 2030 Agenda for Sustainable Devolopment adopted by all United Nations Member States in 2015, cities should aim at being inclusive (as well as green and safe), with a special focus on vulnerable groups. For an inclusive city, improving mobility and the related sense of autonomy for visually impaired people (VIP) is therefore a growing challenge. Unfortunately, there is a lack of data examining how urban mobility is experienced and perceived by these category of road users in terms of safety.
Aim of the present research is to investigate the mobility habits and the related perceptions of safety of VIP.
106 VIP from an urban area of Northern Italy took part in a semi-structured telephone interview. The interview explored the use of public transport (PT), the experience with transport services organized by volunteers, the representation of pedestrian walks and the perceptions of risk and safety related to the different modes of travel.
The key findings showed that 10% of the sample did not feel safe when walking at all, 30% feel safe only when walking with a companion and the remaining 60% feel safe also when walking independently. Regarding PT use, 20% of respondents do not use it, and among those who do, 52% do not feel safe.
The collected results provide useful information for planning the spatial layout of urban environments and developing urban infrastructure and innovative devices and sensors based on the subjective perception of risk and safety, so as to promote inclusive mobility
sj-docx-5-hpq-10.1177_13591053231168040 – Supplemental material for Analysis of healthcare workers’ mental health during the COVID-19 pandemic: Evidence from a Three-Wave Longitudinal Study
No full textSupplemental material, sj-docx-5-hpq-10.1177_13591053231168040 for Analysis of healthcare workers’ mental health during the COVID-19 pandemic: Evidence from a Three-Wave Longitudinal Study by Gaia Perego, Federica Cugnata, Chiara Brombin, Francesca Milano, Martina Mazzetti, Paola Taranto, Emanuele Preti, Rossella Di Pierro, Chiara De Panfilis, Fabio Madeddu and Valentina E Di Mattei in Journal of Health Psychology</p
Simulation of Fracture and Cutting Processes in Thin-walled Multi-layer Shell Structures
No full textsj-txt-1-hpq-10.1177_13591053231168040 – Supplemental material for Analysis of healthcare workers’ mental health during the COVID-19 pandemic: Evidence from a Three-Wave Longitudinal Study
No full textsj-txt-1-hpq-10.1177_13591053231168040 for Analysis of healthcare workers’ mental health during the COVID-19 pandemic: Evidence from a Three-Wave Longitudinal Study by Gaia Perego, Federica Cugnata, Chiara Brombin, Francesca Milano, Martina Mazzetti, Paola Taranto, Emanuele Preti, Rossella Di Pierro, Chiara De Panfilis, Fabio Madeddu and Valentina E Di Mattei in Journal of Health Psychology</p
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