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Test in Operative Environment of an Artificial Neural Network for Aerodynamic Angles Estimation
No full textThe development of an avionic system passes through several steps, which aim is to obtain a reliable equipment able to confirm the initial theoretical design. All these steps can be influenced by a lot of factors coming both from the sensors applied and from practical considerations. Thus, the identification of a valid Flight Test Instrumentation (FTI) has a key role in the design of innovative equipment. After being validated in simulated environment, an ANN (Artificial Neural Network)-based equipment started the operative environment test phase. This innovative patented virtual sensor named Smart-ADAHRS (Air Data, Attitude and Heading Reference System) is able to provide a complete suite of inertial and air data measurements using on-board sensors only plus a single external source of dynamic pressure. In contrast to the state-of-the-art ADS (Air Data System), Smart-ADAHRS is capable of estimate the aerodynamic angles by means of a non-linear regression that has been proven to meet, at least in simulated environment, the requirements given by typical aircraft control systems and safety operations. A successful training procedure has been conducted thanks to a partnership between academic and industrial entities. A prototype of Smart-ADAHRS has been placed on a ULM (Ultra-Light Machine) fully equipped by an ULMdedicated low cost, low intrusive and reliable FTI capable of synchronous acquisition of more than 40 parameters. After a comprehensive description of Mnemosine Mk-V and Smart-ADAHRS, an analysis of some results obtained by flight test is presented. Typical issues around the flight test phase, as well as future improvements are discussed in the final part of this work
Hydro-Mechanical Behaviour of Tailings in Unsaturated Conditions
No full textMany geotechnical problems are related with soils and structures in unsaturated conditions. Among them, a significant role is played by tailing dams that represent complex geotechnical systems. Because of their wide extension, tailing storage facilities are subjected to many external actions and interactions with the atmosphere, whose effects governing the position of phreatic surface. Hence, the low permeability deposited tailings are subjected to drying-wetting processes, leading variation in the extensions of the unsaturated zone above the phreatic surface with a significant role in stability of the embankment. The current research is aimed to study the hydro-mechanical behaviour and the water retention response of unsaturated silt and silt-sand tailings mixtures, respectively, in order to extend a previous characterization of the same soil performed in saturated conditions. This research is also aimed at investigating the occurrence of the critical state in unsaturated conditions, showing the range of state variables leading the static liquefaction. Finally, irradiation by means of gamma rays is proposed as an accelerated technique in order to simulate the natural ionizing radiations acting on stored tailings that, in many countries, are beginning to be re-used as backfill, landscaping material or feedstock for cement and concrete. Wet and dry silty samples were exposed to gamma rays and then characterized in order to study any possible physical and chemical modifications of the exposed matter. The starting point of this research is an available hydro-mechanical characterization of saturated tailings coming from Stava tailing dams collapsed in 1985 (Italy). The first series of experimental tests was carried out to study the hydraulic behaviour of the Stava tailings by means of water retention tests. To account for the heterogeneity of the tailing material within the basin, the dependency of the water retention relationship on grain size distribution and void ratio was investigated. In order to extend the limited range of matrix suction allowed by the axis translation technique, the water retention curves were also implemented with data obtained by indirect soil suction measurement and soil suction controlling methods, dew point technique and vapour equilibrium technique, respectively. Since the pre-shearing state of the soil has a relevant effect on the behaviour shown during shearing before reaching the critical state conditions, a second campaign of experimental tests, consisting in five mono-dimensional compression tests, was performed. Results were compared with those in saturated conditions obtained by Carrera (2008) in order to investigate the dependency of preconsolidation stress and stiffness of the soil on suction. Aimed to extend the hydraulic characterization and to approach the possible critical state in unsaturated conditions from drying and wetting sides, a third campaign of experimental tests was carried out by using a suction controlled triaxial cell and imposing different hydro-mechanical stress paths. Statically compacted silty samples were subjected at different suction levels, then isotropically consolidated at different net stresses, and finally sheared at constant water content or constant suction level by means of the axis translation technique or the vapour equilibrium technique. Finally, due to the importance of the static liquefaction phenomena in stability problems of tailing dams, a fourth series of experimental tests was performed by means of a triaxial cell. Silt specimens were tested in unsaturated or close to saturated conditions, in order to investigate some of the main factors (degree of saturation, initial density and preparation technique) that are supposed to influence the liquefaction response
Surface EMG for human-machine interfaces: New knowledge and open issues
No full textRobotic technologies are progressively gaining considerable importance in motor rehabilitation. In this context, the development of non-invasive man-machine interfaces has a significant role. Among other physiological signals, surface EMG is of paramount importance. However, the detection of surface EMG signals in rehabilitation is currently based almost exclusively on a single or a few electrode pairs. In the last decade, some important limitations of this approach emerged. This work reviews the more recent knowledge about issues in the use of simple bipolar system when the objective is to estimate muscle activation and highlight the benefits provided by multi-channel surface EMG to muscle activity estimation
In vitro characterization of two different atmospheric plasma jet chemical functionalizations of titanium surfaces
No full textPlasma surface activation and plasma polymers deposition are promising technologies capable to modulate biologically relevant surface features of biomaterials. The purpose of this study was to evaluate the biological effects of two different surface modifications, i.e. amine (NH2-Ti) and carboxylic/esteric (COOH/R-Ti) functionalities obtained from 3-aminopropyltriethoxysilane (3-APTES) and methylmethacrylate (MMA) precursors, respectively, through an atmospheric plasma jet RF-APPJ portable equipment. The coatings were characterized by Scanning Electron Microscopy, FT-IR spectroscopy, XPS and surface energy calculations. Stability in water and after UV sterilization were also verified. The pre-osteoblastic murine cell line MC3T3-E1 was used to perform the in-vitro tests. The treated samples showed a higher quantity of adsorbed proteins and improved osteoblast cells adhesion on the surfaces compared to the pristine titanium, in particular the COOH/R-Ti led to a nearly two-fold improvement. Cell proliferation on coated samples was initially (at 24 h) lower than on titanium control, while, at 48 h, COOH/R-Ti reached the proliferation rate of pristine titanium. Cells grown on NH2-Ti were more tapered and elongated in shape with lower areas than on COOH/R-Ti enriched surfaces. Finally, NH2-Ti significantly enhanced osteocalcin production, starting from 14 days, while COOH/R-Ti had this effect only from 21 days. Notably, NH2-Ti was more efficient than COOH/R-Ti at 21 days. The amine functionality elicited the most relevant osteogenic effect in terms of osteocalcin expression, thus establishing an interesting correlation between early cell morphology and later differentiation stages. Taken together, these data encourage the use of the functionalization procedures here reported in further studies
Life Cycle datasets of the Italian stone production chain
No full textThe ornamental stone production chain deeply changed in the ‘70s and in the following decades, when the mechanization of processes increased the production and the safety of workers. Nevertheless, the new techniques are also responsible of not negligible environmental impacts. This paper is focused on the currently most diffused techniques of extraction, cutting and polishing of the Italian stone sector (gneiss and marble). The study follows a Life Cycle Thinking approach and aims to make available detailed Life Cycle datasets on specific techniques of stone production. To this aim, primary data were collected in Italian quarries and transformation plants. The realization of the dataset related to the bridge cutting technique is presented. Some results on environmental impacts associated to this particular stone cutting technology show the most relevant flows in relation to different impact categories
Elementi di Ingegneria delle Terapie Termiche
No full textQuesto volumetto `e la sintesi delle lezioni del corso di Terapie termiche tenuto presso il corso di Laurea Magistrale in Ingegneria Biomedica e di Ingegneria Energetica e Nucleare del Politecnico di Torino. Il corso ha l'obiettivo di sviluppare l'analisi delle terapie termiche in ambito medico e veterinario, dal punto di vista della Fisica Tecnica, quindi prestando attenzione ai fondamenti termodinamici e di trasmissione del calore. Queste lezioni presentano i principi fondamentali dell'ingegneria delle terapie termiche, da cui lo studente approfondir`a autonomamente gli argomenti in relazione ai suoi interessi applicativi. Si vogliono quindi fornire le conoscenze di base utili per rendere lo studente autonomo nello studio e nell'applicazione delle terapie termiche. Nel testo non sono presenti le esercitazioni che sono svolte durante il corso, per consentire a chiunque avesse intenzione di introdurre questi argomenti in un corso equivalente, di svolgere le applicazioni pi`u coerenti con il percorso di studi a cui afferisce il corso stesso
Hyperpolarizability and operational magic wavelength in an optical lattice clock
No full textOptical clocks benefit from tight atomic confinement enabling extended interrogation times as well as Doppler- and recoil-free operation. However, these benefits come at the cost of frequency shifts that, if not properly controlled, may degrade clock accuracy. Numerous theoretical studies have predicted optical lattice clock frequency shifts that scale nonlinearly with trap depth. To experimentally observe and constrain these shifts in an 171Yb optical lattice clock, we construct a lattice enhancement cavity that exaggerates the light shifts. We observe an atomic temperature that is proportional to the optical trap depth, fundamentally altering the scaling of trap-induced light shifts and simplifying their parametrization. We identify an ``operational" magic wavelength where frequency shifts are insensitive to changes in trap depth. These measurements and scaling analysis constitute an essential systematic characterization for clock operation at the 10-18 level and beyond
Study of magnetization processes in rare-earth-free materials: MnBi and Mn-Fe-P-Si
No full textMagnetic materials are at the base of many innovative devices. In many cases these materials are based on rare-earth (RE) intermetallic compounds, like Nd2Fe14B for permanent magnets and La(FeSi)13 for magnetic cooling. Permanent magnets are employed in a large range of application fields: e.g. in motors, hard disc drives, magnetic resonance imaging, mobile phones, microphones etc. Magnetic materials for permanent magnets need a high magnetocrystalline anisotropy energy (MAE). The MAE is associated with the angle formed by the magnetization vector with the axes of the crystal lattice and its microscopic origin is due to the coupling between the atomic magnetic moments and the crystal lattice. High performance permanent magnets are based on compounds with rare earth elements, like NdFeB-based and SmCo-type magnets. The magnetic refrigeration is based on the magnetocaloric effect (MCE). This cooling technique is 30% more efficient than vapor-compression refrigeration. The MCE is defined as the adiabatic temperature change ΔTad or the isothermal entropy change ΔSiso due to the application of a magnetic field H at constant pressure. For a first order magnetic transition, from an ordered ferromagnetic to a disordered paramagnetic phase with an abrupt change in magnetization, the MCE is maximum. In the last years the research has found many different classes of materials, which exhibit a large magnetocaloric effect. Among these, La(FeSi)13 based compounds have been already optimized, while Fe2P-based compounds still need further investigations. In recent years the problems of rare earth supply have prompted the research in the development of new magnetic materials without RE, as MnBi and Mn-Fe-P-Si alloys. MnBi is a good candidate as permanent magnet for its high magnetocrystalline anisotropy. Both MnBi and Mn-Fe-P-Si compounds have a first order magnetic transition, interesting for magnetic refrigeration. The aim of the present work has been to investigate the contributions of the composition (through the partial substitutions of the elements) and/or of the microstructure (by means of different preparation techniques) on magnetization processes of rare-earth-free MnBi and Mn-Fe-P-Si compounds. In this framework the investigation has regarded especially two topics: (i) the study of the magnetization reversal mechanisms in MnBi compounds with the aim to improve their hard magnetic properties by means of the enhancement of the coercive field, without losing magnetization; (ii) the study of the first order transition and the characterization of MCE of MnBi and Mn-Fe-P-Si compounds, which are promising candidates for cooling applications. The room temperature magnetic refrigeration requires materials with a phase transition around room temperature and a thermal hysteresis as small as possible. However, much research is needed to understand how to minimize the unwanted hysteresis in the phase transitions (for MnBi and Mn-Fe-P-Si) and how to decrease the transition temperature of MnBi (633 K). The research activity described in this thesis has been carried out in collaboration with the National Institute of Metrology (INRIM) in Turin (Italy). The preparation and the characterization of the intermetallic MnBi samples are objects of this activity (both carried out at National Institute of Metrological Research (INRIM) in Turin (Italy)). The Mn-Fe-P-Si samples were prepared at Satie Institute of Cachan (France) and in this work their MCE has been characterized. The main results achieved regard: • the preparation of a unknown metastable (Mn,Ti)Bi phase that exhibits a second order magnetic transition around 180 K; • the increasing of the coercive field of MnBi by means of two different techniques (reduction of the particle size and partial substitution of Mn with Ti); • the decrease of the activation volume of the first order transition of the MnBi by means of the introduction of Ti in the MnBi alloys; • the high value of the isothermal entropy change ΔSiso and the adiabatic temperature change ΔTad of the Mn1.30Fe0.65P0.5Si0.5 compounds at first order transition, prepared by classical sintering. In addition to this results, small thermal hysteresis ΔThyst has been obtained on powders (smaller particle size) of the same compounds
