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La copertura dell'aula Giulio Cesare nel Palazzo Senatorio in Campidoglio. Note sul cantiere di fine Ottocento
No full textDevelopment of methods for the determination of reactivity from flux measurements in nuclear reactors
No full textAccelerator Driven systems (ADS) have been proposed as safe and reliable nuclear systems for energy production and, especially, for the transmutation of nuclear radioactive waste, thus contributing to a safer and non-proliferating use of nuclear energy for peaceful uses. The ADS can operate at a higher safety level, since, being driven by an external source, is always characterized by a sub-criticality condition and can thus be shut down by simply switching off the source. To ensure that the system always remain at a sub-critical level, an on-line reactivity monitoring is needed during both normal operation and transient conditions. Research programs such as MUSE, FREYA and GUINEVERE were involved in the development of reactivity measurement methods for ADS. At Politecnico di Torino a method that is suitable for both on-line and off-line reactivity monitoring has been developed and tested. The method has been given the name MAρTA (Monitoring Algorithm for Reactivity Transient Analysis). The method is based on an inverse point kinetic approach which reconstructs the reactivity from the system neutron flux or power measurement obtained instantaneously by a localized neutron detector. The adoption of point kinetics for the reactivity reconstruction is due to the simplicity of the mathematical formulation of the inverse approach. However, the accuracy of the reactivity prediction by point kinetics can deteriorate owing to spatial and spectral effects. Furthermore the kinetic parameters are needed through evaluations or independent measurements. The research activity during the Ph.D. program has been devoted to assess the MAρTA method for reactivity predictions using computationally simulated experiments, evaluated by means of time-dependent diffusion calculations. A technique to improve the prediction when strong spatial and spectral effects are present is proposed and tested. A method for the measurement of the ratio between the effective fraction of delayed neutrons and the effective mean prompt generation time through oscillated experiments has also been proposed and tested. The method has also been applied to real experimental cases available from the Kyoto University Critical Assembly (KUCA). Part of the work carried out is included as a contribution to the IAEA Collaboration Research Project on Accelerator-Driven System (ADS). The collaboration with INFN is also acknowledged
Building damage scale proposal from VHR satellite image
No full textNatural hazards have a huge impact in terms of economic losses, affected and killed people. Current exploitation of remote sensed images play a fundamental role in the delineation of damages generated by catastrophic events. Institutions like the United Nations and the European Commission designed services that provide information about the impact of disasters rapidly. One of the approach currently used to carry out the damage assessment is based on very high resolution remote sensing imagery (including both aerial and satellite platforms). One of the main focus of the responders, especially in case of events like earthquakes, is on buildings and infrastructures. As far as the buildings are concerned, to date international standard guidelines that provide essential information on how to assess building damages using VHR images still does not exist. The aim of this study is to develop a building damage scale tailored for analyses based on VHR vertical imagery and to propose a standard for the related interpretation guidelines. The task is carried out by comparing the current scales used for damage assessment by the main satellite based emergency mapping services. The study will analyze the datasets produced after the Ecuador (April 2016) and Central Italy(August and October 2016) earthquakes. The results suggest that by using VHR remotely sensed images it is not possible to directly use damage classi- fication scales addressing structural damages (e.g the 5 grades proposed by EMS-98). A fine-tuning of existing damage classes is therefore required and the adoption of an internationally agreed standard should be encouraged, to streamline the use of SEM products generated by different services
Innovative and functional electrode/electrolyte materials for green and safe post-lithium batteries
No full textModern life style depends on energy storage systems in which the role of Li-ion batteries (LiBs) is peerless. However, state-of-the-art LiBs are approaching the verge of possible technological imagination in energy density. Some researchers argue that next-gen secondary batteries should switch to heavier elements. Indeed, when it comes to energy storage systems for electricity grid, electric transportation or other non-portable applications, Na-ion (NiB) and Lithium Sulphur (Li-S) batteries can be an intelligent choice. These devices are still at an early stage of advancement and research must necessarily focus on the development of novel types of materials: safe polymer electrolytes, high-energy electrodes and novel production processes thereof. Here, an overview is provided on both solid/quasi-solid polymer electrolytes and nanostructured electrodes specifically conceived for NiB and Li-S secondary cells. Polymer electrolytes are based on polyethylene oxide (PEO), methacrylates and/or their mixtures; eventually, pyranose ring based natural additives and/or low volatile plasticizers are added along with supporting sodium salts to improve specifically defined characteristics. Both standard casting and smart free radical polymerization techniques are explored, thus producing multiphase electrode-electrolyte composites. In this process, an appropriate liquid reactive mixture comprising monomers, salts and eventually additives, which constitutes the polymer electrolyte precursor, is in-situ polymerised to form, in a single step, a self-standing electrode intimately connected to the ion conducting electrolyte membrane, with an efficient interpenetration of the two surfaces. Lab-scale Na-ion and Li-S polymer cells are assembled with different nanostructured electrode materials (e.g., LiFePO4, TiO2 nanotubes, sulphur-activated carbon) and tested for their long-term cycling ability and rate capability, demonstrating that safe, durable and high energy density post-lithium devices operating at ambient temperatures can be a reality in the near future
Information Modeling for Virtual and Augmented Reality
No full textSmart Building is recent interdisciplinary research field that aims to improve the monitoring, management and maintenance of buildings. In this scenario, we present an innovative solution for combining BIM (Building Information Modelling) data with ambient information collected by heterogeneous devices deployed in the building. In order to collect environmental information, we exploit in this work a distributed software architecture. It enables the interoperability between heterogeneous data-sources, either physical devices like sensor nodes or third party software like Archibus, where building information resides. On top of this infrastructure, we developed an Android-based application that presents environmental building information integrated with BIM data in an Augmented and Virtual Reality environment. The proposed solution provides users awareness about building conditions and energy consumptions
Learning: Semantics
No full textLearning semantics, which is intended as a way to provide digital learning resources with a meaning and make them processable by machines by mimicking human reasoning, is changing the way teaching and learning processes are being carried out. Through semantic processing, a machine could act as a personal assistant at the service of learners, trainers and other actors involved in the education context, and could help them to address knowledge-intensive problems, encompassing the creation, management and personalization of learning paths, the identification of suitable learning resources, the automatic grading of assignments and exams, etc. This paper aims to draft an overall picture of learning semantics, by illustrating enabling technologies, providing hints on how a semantic system for learning could be realized, presenting relevant application scenarios, showing expected benefits, discussing challenges and threats and outlining possible solutions
A discrete mathematical model for the dynamics of a crowd of gazing pedestrians with and without an evolving environmental awareness
No full textIn this article, we present a microscopic-discrete mathematical model describing crowd dynamics in no panic conditions. More specifically, pedestrians are set to move in order to reach a target destination and their movement is influenced by both behavioral strategies and physical forces. Behavioral strategies include individual desire to remain sufficiently far from structural elements (walls and obstacles) and from other walkers, while physical forces account for interpersonal collisions. The resulting pedestrian behavior emerges therefore from non-local, anisotropic and short/long-range interactions. Relevant improvements of our mathematical model with respect to similar microscopic-discrete approaches present in the literature are: (i) each pedestrian has his/her own dynamic gazing direction, which is regarded to as an independent degree of freedom and (ii) each walker is allowed to take dynamic strategic decisions according to his/her environmental awareness, which increases due to new information acquired on the surrounding space through their visual region. The resulting mathematical modeling environment is then applied to specific scenarios that, although simplified, resemble real-word situations. In particular, we focus on pedestrian flow in twodimensional buildings with several structural elements (i.e., corridors, divisors and columns, and exit doors). The noticeable heterogeneity of possible applications demonstrates the potential of our mathematical model in addressing different engineering problems, allowing for optimization issues as well
An Unconventional Adaptive Flutter Suppression Actuation System: from Modeling to Experimentation
No full textThis article contributes to the definition of an unconventional actuation system coupled with an adaptive control algorithm, it is intended specifically for slender/highly flexible wings flutter suppression. The design and validation process of the novel actuation architecture is presented together with the performance analysis of the post-flutter dynamics control. Robustness of the overall control architecture is verified with respect to the uncertainties deriving from the unpredictable degradation of the structural properties. The proposed actuation system is based on a row of multiple minispoilers, located in proximity of the leading edge and coordinated by a modified model reference adaptive control algorithm. The spoiler configuration is optimized by computational fluid dynamics numerical simulation, whereas the aerodynamic database is derived by wind tunnel tests on the prototype by means of a six-axes force balance. The resulting aeroelastic mathematical model is then used to implement and validate the adaptive control algorithm for a wide range of conditions, from on-design flutter speed and nominal structural stiffness to post-flutter speed and reduced structural stiffness. The two degree of freedom aeroelastic model is successfully controlled in all conditions. This article aims at defining a robust procedure for aeroelastic phenomena control system design, which employs a synergy of modeling, simulation, and experimental approaches. Pertinent conclusions are discussed in the final section of the article
Electro-oxidation of phenol over electrodeposited MnOx nanostructures and the role of a TiO2 nanotubes interlayer
No full textMore and more attention has recently been paid to the electrochemical treatment of wastewater for the degradation of refractory organics, such as phenol and its derivatives. The electrodeposition of different types of manganese oxides (MnOx) over two substrates, namely metallic titanium and titania nanotubes (TiO2-NTs), is reported herein. X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS) analyses have confirmed the formation of different oxidation states of the manganese, while Field Emission Scanning Electronic Microscopy (FESEM) analysis has helped to point out the evolutions in the morphology of the samples, which depends on the electrodeposition parameters and calcination conditions. Moreover, cross section FESEM images have demonstrated the penetration of manganese oxides inside the NTs for anodically deposited samples. The electrochemical properties of the electrodes have been investigated by means of cyclic voltammetry (CV) and linear sweep voltammetry (LSV), both of which have shown that both calcination and electrodeposition over TiO2-NTs lead to more stable electrodes that exhibited a marked increase in the current density. The activity of the proposed nanostructured samples toward phenol degradation has been investigated. The cathodically electrodeposited manganese oxides (α-MnO2) have been found to be the most active phase, with a phenol conversion of 26.8%. The anodically electrodeposited manganese oxides (α-Mn2O3), instead, have shown higher stability, with a final working potential of 2.9 V vs. RHE. The TiO2-NTs interlayer has contributed, in all cases, to a decrease of about 1-1.5 V in the final (reached) potential, after a reaction time of 5 h. Electrochemical impedance spectroscopy (EIS) and accelerated life time tests have confirmed the beneficial effect of TiO2-NTs, which contributes by improving both the charge transfer properties (kinetics of reaction) and the adhesion of MnOx films
Theoretical flow rate in crescent pumps
No full textIn this paper, a method for evaluating the kinematic flow rate of a crescent oil pump is presented. The procedure also allows calculating the angular derivatives of the delivery, suction and trapped volumes of the pump, which are the prerequisites for the simulation of the unit using a lumped parameters approach. The method is based on the knowledge of the length of the vector rays between the centres of the gears and the contact points. From the volume derivatives, an analytic expression of the pump displacement and of the kinematic flow ripple index is obtained. Moreover, the same formula can also be applied to external gear machines. Finally, in this study the influence of the number of teeth of the driving and driven gears has been assessed. The increase of the number of teeth of the inner gear is beneficial; both for the reduction of the flow ripple and for the increase of the displacement at equal overall pump size