1,721,022 research outputs found
ON OCCUPANT IDENTIFICATION AND RELATED CRASH OUTCOME IN OUT OF POSITION CONDITIONS
Full text linkThe methodology for crash tests in vehicle development and homologation is based on dummies sitting in a standardized posture, defined by the H-point of the car body and design specifications. As a result, injury criteria are directly influenced by these precisely defined initial conditions. Out-of-Position scenarios are not included in passive safety tests but are usually analysed conventionally through specialized experiments. The combination of crash dynamics and improper airbag deployment can increase the forces exerted on the body. While airbags have saved numerous lives, statistics also report injuries and fatalities caused by improper contact with deploying airbags. This study examines strategies to make the Airbag Control Unit effectively adaptive to an occupant position. Pre-crash scenarios are identified using sensors in the vehicle seat and the corresponding outcomes are simulated. The research highlights the importance of a thorough examination of crash circumstances, process and outcomes to improve safety in intelligent vehicles
A methodology for out of position occupant identification from pressure sensors embedded in a vehicle seat
No full textThe airbag deployment against an out of position (OP) occupant is critical. The OP condition can be hardly expected during design, while a too close airbag deployment can cause serious injuries instead of mitigating the crash effects. An adaptive airbag system would be capable to adjust its deployment to the inside scenario. However, the integration between human passengers and intelligent vehicle requires the airbag control unit to be aware of the actual occupant(s) position. In the present research, a methodology for monitoring the occupant(s) position is developed and tested with a seat prototype. A layout of thin film sensors monitors the interface pressure between the occupant and the seat cover. An inertial measurement unit (IMU) monitors the accelerations of the vehicle, considered the reference moving platform. A microcontroller is programmed for pressure sensors calibration, IMU alignment with the vehicle reference system, signals processing, OP detection, and identification. Real driving experiments on a race track were performed in the correct position and in three different OPs. The comparison of the pressure center in longitudinal and transversal directions with the vehicle acceleration enables to identify the OPs
Out of Position Driver Monitoring from Seat Pressure in Dynamic Maneuvers
No full textAn airbag system is designed to reduce the accident outcome on the car occupants. The airbags deployment against manikins is severely tested according to international regulations. The accident scenarios with Out of Position (OP) occupants are critical since they can be hardly expected during design. The airbag deployment in these scenarios can be improved by developing adaptive strategies, provided that the Airbag Control Unit must be aware of the actual occupant position. The present research investigates a sensor system to monitor the occupants in an interactive Human-Car system. The driver position is monitored by pressure sensors, while an accelerometer enables to compensate for acceleration and noise. Real driving experiments in dynamic conditions are reported. The results prove that three OP conditions are effectively identified
Interactive casting simulation assistant for conceptual design of permanent moulds
No full textCasting simulations evaluate the physics in the cavities, up to micro-physics in the formation of porosities, metallurgical structures and mechanical properties. As a limit in this procedure, a 3D CAD model of the mould is required, which is very time consuming to deliver. Therefore, the simulations can be little exploited in the initial conceptual phase and the equipment layout must be defined mainly based on the experience of practitioners. This research studies a Casting Simulation Assistant tool for Gravity Die Casting and Low Pressure Die Casting in order to calculate the simulation parameters and to deliver the simulation results as fast as possible. The paper discusses the necessary simplifications, the input and output data, the modelling technique, the software structure and the user interface. In particular, a mould is modelled as a thermal machine, with in- and out-flows of matter and energy. The tool is evaluated against the results from a commercial software, first on theoretical cases and then also on four real moulds. The Casting Simulation Assistant calculates the performance of the mould in a few seconds, allowing design parameters to be modified and recalculated interactively. The results can be used for the evaluation of the main performance of the mould as feasibility analysis, for production costs estimation, for the rapid comparison of different design variants in the conceptual design phase and to give a first assessment of a set of parameters in order to save time in the following simulations
Geophysical Recipe to Model the Covid-19 Epidemic
No full textThe coronavirus pneumonia epidemic, caused by SARS-CoV-2, was classified by the World Health
Organization as a public health emergency of international concern on January 30th, 2020. The new
SARS-CoV-2 was named coronavirus disease 2019 (COVID-19). Countries have reacted with different
actions to control the source of infection, to inhibit the way of transmission and to protect the susceptible
population. Italy has been strongly impacted by the diffusion of the contagion with about 30000
fatalities at mid-May 2020.
The SEIR (Susceptible-Exposed-Infectious-Removed) model predicts the time-evolution of the
epidemic phenomenon, based on the analysis of the infection and recovery rates. The prediction is based
on the solution of a system of differential equations, usually solved according to a deterministic method.
We propose a probabilistic approach, often used in geophysics, to solving the SEIR model of COVID19 epidemic diffusion in Italy and in its most impacted northern regions. Particularly, we solve the
differential equations of the SEIR model by adopting a metaheuristic method, the Particle Swarm
Optimization (PSO) algorithm, belonging to the family of computational swarm intelligence (Kennedy
and Eberhart, 1995). The similarities with geophysical problems are many: the geophysical measures
are replaced by official data on the spread of the infection, there is a consolidated predictive model and
the goal is to estimate the model coefficients, in order to satisfy the experimental data. Like the
geophysical inverse problem, the SEIR differential equations represent an ill-posed problem, whose
solution is not unique. The advantage of the PSO approach is that the adaptive exploration of the space
domain of the solutions decreases the risk of being trapped into a local minimum and it iteratively
searches for the global minimum as the final solution. Moreover, the PSO method provides several
scenarios so that the a-posteriori reliability of the model-solution can be evaluated (Godio and Santilano,
2018). The modelling was carried out by using observed data up to the mid of April with a 30-day
prediction
SEDILE DI VEICOLO CON SISTEMA DI RILEVAMENTO PASSEGGERI
Full text linkÈ descritto un sedile di veicolo con sistema di rilevamento passeggeri, comprendente una pluralità di sensori di forza (11) distribuiti 5 superficialmente su almeno un substrato (1), sostenuto da un telaio (F) del sedile oppure facente esso stesso funzione di telaio, in risposta alla sollecitazione del peso dell'occupante del sedile e dei suoi sforzi durante la guida, un cablaggio (12) 10 collegato elettricamente a ciascun sensore di forza (11), almeno una scatola di giunzione (2), il cablaggio (12) collegato elettricamente alla scatola di giunzione (2), un cablaggio comune (21) collegato elettricamente alla scatola di giunzione (2), il 15 cablaggio comune (21) adattato per essere collegato ad un controllore del veicolo (3) per fornire un segnale elettrico. Una pluralità di porzioni rigide di supporto (4) è interposta tra i sensori di forza (11), a loro volta sostenuti dal substrato (1), ed 20 almeno uno strato di imbottitura (5)
Efficiency and reliability of gravity die casting models for simulation based design
Full text linkSimulation of Gravity Die Casting (GDC) requires to couple different models for fluid dynamics, heat transfer and solidification, together with material physics properties. Very long calculation times are required since several heating and production cycles have to be run. The simplification of the simulation models is critical to have results in useful times for the design process. The present work discusses the solidification and heat transfer physics with simplification hypoth-eses. A simulation approach skipping the pouring model for the heating cycles is introduced. A realistic case study on an engine head GDC is presented to evalu-ate four possible simulation sequences. The results show that including the heat-ing cycles in the simulation is advisable. The simplified sequences reproduce the temperature field of the die with sufficient accuracy. The proposed simulation approach results in considerable time savings with respect to the actual simula-tions and even in little accuracy improvements
Seir modeling of the italian epidemic of sars-cov-2 using computational swarm intelligence
Full text linkWe applied a generalized SEIR epidemiological model to the recent SARS-CoV-2 outbreak in the world, with a focus on Italy and its Lombardy, Piedmont, and Veneto regions. We focused on the application of a stochastic approach in fitting the model parameters using a Particle Swarm Optimization (PSO) solver, to improve the reliability of predictions in the medium term (30 days). We analyzed the official data and the predicted evolution of the epidemic in the Italian regions, and we compared the results with the data and predictions of Spain and South Korea. We linked the model equations to the changes in people’s mobility, with reference to Google’s COVID-19 Community Mobility Reports. We discussed the effectiveness of policies taken by different regions and countries and how they have an impact on past and future infection scenarios
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