Higher Institute on Territorial Systems for Innovation
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Utilizzi del modello BIM per il Facility Management
No full textLa metodologia di lavoro indagata nell'ambito del progetto ToBIM promuove la realizzazione di accurati modelli virtuali rappresentativi dello stato di fatto degli edifici esistenti. Questi modelli non si riducono a semplici elaborazioni tridimensionali, bensì si configurano come strumenti multi-dimensionali che permettono un'analisi ed un controllo più efficiente rispetto ai processi tradizionali
A new CFD-Simulink based systems engineering approach applied to the modelling of a hydraulic safety relief valve
No full textA safety relief valve is a simple hydro-mechanic device, needed to avoid overpressure transients inside hydraulic circuits. Such valves are a critical part of the hydraulic system of aircraft; hence their performances must be adapted to a specific nominal pressure level and design requirements. In the following paragraphs the authors will address the issue of designing and validating a safety valve through a hybrid CFD/MATLAB-Simulink® approach. The main constraints are the geometrical dimensions and the need to limit the weight of the device. A significant part of the work consists of gathering all the possible information available in the literature, dealing with the best design practices to achieve the performance objective. Thanks to a robust computational procedure, it should be possible to reduce the amount of "physical" prototypes required to validate the functionality of a safety relief valve. The process presented uses a numerical computational fluid dynamic (CFD) approach, to define the pressure field inside the valve and the forces acting on it; identifying the force distribution inside the valve is paramount to address the performance evaluation of the valve itself. The first step deals with the definition of a computer aided design (CAD) model of the valve. Then the CFD software uses the above-mentioned CAD model to define the domain of the problem. Once obtained the pressure field, it is possible to integrate it through the surface of the valve, thus obtaining the forces acting on the moving part (poppet). After the numerical scheme has been calibrated, some investigations are done to reduce the computational cost: the main aim is to run a complete simulation (meshing and solving) on a standard computer. Some of the positions (i.e. strokes) of the valve have been simulated as static, hence a steady-state calculation has been applied to solve the motion field. Another important result consists of creating a MATLAB-Simulink® model, capable to reach results comparable to the CFD simulation, but in shorter times. While the CFD model can provide high quality results, the MATLAB-Simulink® calculation should be used to create a "first guess" instrument, useful to address the very first valve geometry. The implementation of the Look-Up Tables (LUTs) links the MATLAB-Simulink® model to the CFD simulation, but increases the time required to obtain a solution: on the other hand, this reduces the amount of equation-modeled quantities, delivering a greater precision to the calculations
Itinerant ferromagnetism of two-dimensional repulsive fermions with Rabi coupling
No full textWe study a two-dimensional fermionic cloud of repulsive alkali-metal atoms characterized by two hyperfine states which are Rabi coupled. Within a variational Hartree-Fock scheme, we calculate analytically the ground-state energy of the system. Then we determine the conditions under which there is a quantum phase transition with spontaneous symmetry breaking from a spin-balanced configuration to a spin-polarized one, an effect known as itinerant ferromagnetism. Interestingly, we find that the transition appears when the interaction energy per particle exceedes both the kinetic energy per particle and the Rabi coupling energy. The itinerant ferromagnetism of the polarized phase is analyzed, obtaining the population imbalance as a function of interaction strength, Rabi coupling, and number density. Finally, the inclusion of a external harmonic confinement is investigated by adopting the local density approximation. We predict that a single atomic cloud can display population imbalance near the center of the trap and a fully balanced configuration at the periphery
Paper-based quasi-solid dye-sensitized solar cells
No full textNatural cellulose fibres are proposed as promising components for bioderived photoanodes and polymer electrolytes in dye-sensitized solar cells (DSSCs). In particular, TiO2-laden paper foils, prepared by simple papermaking, can be applied to several substrates (conductive glass or plastics) instead of the high-temperature sintered traditional commercial pastes. In addition, nanoscale microfibrillated cellulose is used as reinforcing filler in acrylate/methacrylate-based thermo-set polymer electrolyte membranes prepared by means of fast, low-cost and green UV-induced free-radical photopolymerization. The laboratory-scale quasi-solid state paper-DSSCs assembled with cellulose-based electrodes and electrolytes guarantee sunlight conversion efficiencies as high as 3.55 and 5.20% at simulated light intensities of 1 and 0.2 sun, respectively, along with an excellent efficiency retention of 96% after 1000 h of accelerated aging test. The simple, low cost and green approach here specifically developed opens up intriguing prospects in the design of bio-inspired energy conversion devices showing high performance, outstanding durability and truly sustainable characteristics
Experimental Setup to Compare Measurements and Numerical Simulations in Magnetic Resonance Imaging RF Dosimetry
No full textQuality and energy evaluation of rail-road terminals by microsimulation
No full textThe aim of this paper is to present a method to evaluate the quality and energy performance of inland freight terminals, using a quantitative approach based on traffic microsimulation models. The transport of goods should meet requirements of environmental sustainability and combined transport can be an eco-friendly option for medium/long distance connections, in which the railway mode can provide its efficiency if properly accessible. The analysis of the terminal aims at quantifying Key Performance Indicators (KPIs) by traffic microsimulation. The relevant features of the typical phases of the internal process are represented and the traffic flow data of arrivals are disaggregated by specific service needs. The model is used to compare the chosen indicators in different scenarios, varying the arrival rates for trucks and reducing the duration of check-out and cranes operations. Results of quality and energy are also reported disaggregated for the differ-ent types of service lines
ARSSET: Augmented Reality Support on SET
No full textThe preparation of a set for a television production is a complex work; usually, several objects have to be manually placed in the environment and the configuration might be changed many times before finding the final set up. This configuration phase can be expensive and time consuming when large and heavy objects have to be moved. In order to tackle this issue, virtual sets allow the director of production to create virtual scenes before placing real objects. This paper proposes an alternative approach based on augmented reality technologies: objects of the scene are computer generated assets, which can be placed and manipulated in a real environment. With respect virtual sets, the proposed solution allows the director to move in a real scene enriched by computer-generated objects to be placed in the environment. The user wears an AR headset and manipulates objects by a tablet. The proposed system was evaluated by a group of 9 testers, which had to create an augmented TV set. Subjective and objective parameters have been used to assess the system usability
Proposal of a risk model for vehicular traffic: A Boltzmann-type kinetic approach
No full textThis paper deals with a Boltzmann-type kinetic model describing the interplay between vehicle dynamics and safety aspects in vehicular traffic. Sticking to the idea that the macroscopic characteristics of traffic flow, including the distribution of the driving risk along a road, are ultimately generated by one-to-one interactions among drivers, the model links the personal (i.e., individual) risk to the changes of speeds of single vehicles and implements a probabilistic description of such microscopic interactions in a Boltzmann-type collisional operator. By means of suitable statistical moments of the kinetic distribution function, it is finally possible to recover macroscopic relationships between the average risk and the road congestion, which show an interesting and reasonable correlation with the well-known free and congested phases of the flow of vehicles
