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Vedere con le mani il castello del Valentino. L'accessibilità di un bene culturali per visitatori con disabilità visiva
No full textIn order to make heritage buildings culturally significant for everyone they have to become accessible. This should not only be a physical accessibility; the information which the buildings contain must also be accessible. Where physical disability is concerned it is equally important to be able to open the buildings to an ever wider and more diverse public and to make it possible for everyone to "read" the information. A project with students on degree courses in architecture has made it possible to build a pathway to knowledge of the Valentino Castle for visitors with visual impairments. The castle is part of the Politecnico di Torino. Students made use of small scale models, tactile tables, information read aloud through Qr-codes to enable blind and visually impaired visitors to gauge space and to "read" elements of volume, structure, architecture and decor. The students' work, with the support of the Department of Architecture and Design laboratory, led to the creation of a "tactile guided tour", composed of maquettes and tactile boards, which in the near future will be exhibited in one of the main floor rooms of the Castle adding to the guided tours which are already in place
Modelling of Multi-Scale Phenomena in Nanoparticle Suspensions
No full textSelf- or driven-assembly of nanoparticles (NPs) into mesoscopic ordered structures play a crucial role in a large variety of applications including energy, pharmaceutical, food, drug delivery, immunology and technological. On the one hand, trying to prevent and avoid the self-organization of nanoparticles has traditionally been the main issue to stabilizing nanosuspensions, foams, and emulsions. On the other hand, the aggregation of building-blocks into mesoscopic structures has allowed to explore new materials with desired functionalities and properties. In the latter context, a proper attention has been devoted to the dominant role of aggregation in altering the thermal properties of nanosuspensions. However, due to the challenges of controlling the inter-particle interactions and the process of aggregation, clear guidelines for a rational design of tailored suspensions is still missing. Accurately modelling heat and mass transport phenomena across many different length scales is essential to optimize the self-assembly and stability of colloidal suspensions. In this thesis, Molecular Dynamics (MD) simulations, Coarse-Grained (CG) techniques, Brownian Dynamics (BD) and theoretical modelling studies are combined to understand how the interfacial phenomena influence the mechanisms of building-block interactions and hence how to predict the shapes of assembled clusters and their related macroscopic properties. First, the behaviour of nanoconfined water and the adsorption of ionic surfactants at the solid-liquid nanoscale interface are investigated. Second, atomistic Potentials of Mean Force (PMFs) are evaluated between couples of NPs dispersed in aqueous solutions. A sensitivity analysis is carried out by altering the hydrophilicity of the nanoparticles, their surface charge and the salt concentration of the bulk solution. Moreover, the role of anionic (Sodium Dodecyl Sulphate -SDS-) and cationic (Dodecyl Trimethyl Ammonium -DTAB-) surfactants is included in the evaluation of the PMF. All the study cases are then compared with the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, and remarkable discrepancies have emerged, underling the limits of a continuum theory to model the colloidal interactions at the nanoscale. In particular, the results highlight that the assumption of a uniform and continuum media and the hypothesis of homogeneous particles present in the DLVO theory break down at the solid-liquid nanoscale interface and by considering patchy NPs after surfactant adsorption. Thus, MD simulations offer the best alternatives to capture all coupled phenomena included in NP interactions. Subsequently, the atomistic PMFs are implemented in a multi-scale model, where MD simulations and Brownian dynamics are integrated offering a detailed picture of the kinetic of NP aggregation. The qualitative agreement with the experimental observations validates the novel multi-scale platform, able to connect the nanoscale features to the size of aggregates and related macroscopic properties of colloidal suspensions. Finally, with a coarse-grained technique, a force field for heterogeneous NPs is also provided. Thus, in the present work, powerful tools and multi-scale modelling approaches are developed to describe some of the multi-scale phenomena occurring in NP suspensions. Clear guidelines to perform multi-scale simulations of the self-assembly processes are proposed, and the first step towards a rational design of NP suspensions is presented
Hidden magnetism in periodically modulated one dimensional dipolar fermions
No full textThe experimental realization of time-dependent ultracold lattice systems has paved the way towards the implementation of new Hubbard-like Hamiltonians. We show that in a one-dimensional two-components lattice dipolar Fermi gas the competition between long range repulsion and correlated hopping induced by periodically modulated on-site interaction allows for the formation of hidden magnetic phases, with degenerate protected edge modes. The magnetism, characterized solely by string-like nonlocal order parameters, manifests in the charge and/or in the spin degrees of freedom. Such behavior is enlighten by employing Luttinger liquid theory and numerical methods. The range of parameters for which hidden magnetism is present can be reached by means of the currently available experimental setups and probes
Embedded Model Control for UAVs: theoretical aspects, simulations and experimental results
No full textUnmanned Aerial Vehicles (UAVs) and, more specifically, n-copters have come to prominence in the last decade. Indeed, unmanned vehicles may have several applications in society, spanning from complex operations, also in potentially hazardous environments for humans to more entertaining purposes. Furthermore, UAVs have drawn great attention in the automatic control research community. This is mainly due to two reasons. First of all, designing a control for this non-linear and underactuated system can represent a stimulating challenge for control researchers. Secondly, n-copters, being typically mechanically simple and fast-prototyping devices, are widely considered as a good technology for testing a wide range of control algorithms and designs, also employing a wide range of sensors. In fact, the possibility of having several low cost sensors on-board enables the implementation of many navigation solutions as well as sensor calibration algorithms. In this work, the control unit design for a quadrotor was addressed. In particular, the study regards the Borea quadrotor which is part of an internal project (Borea) of the former Space and Precision Automatics research, now Systems and Data Science group, at Politecnico di Torino. The Borea project aims to test Guidance, Navigation and Control (GNC) algorithms designed within the framework of the Embedded Model Control (EMC) methodology. In particular, one of the main project objectives regards the testing of planetary landing algorithms because of the similitude in the command authority between n-copters and spacecrafts during the landing phase. In fact, both n-copters and spacecrafts can provides a thrust vector which is constant in direction whereas its intensity can be regulated. The EMC framework matches the GNC architecture perfectly. More important, EMC is a methodology based on an internal model which includes the uncertainties, in the form of disturbances, that have to be rejected. Indeed, the main design effort is focused on the internal model design, which is the core of the whole control unit. The Borea UAV has been endowed with a control system in order to control its position, velocity, and attitude. These results has been achieved by means of a well structured design process which started from the plant modelling and arrived to the flight test. Indeed, the process has involved intensive numerical simulation and control refinements as well as multi-staged tests and model validations. During the design process some neglected dynamics has turned out to be very important for the control design and their identification was revealed mandatory. On the other hand, the control problem was separated into two independent controllers in order to have a more simple controller which makes the quadrotor able to fly allowing to test all the subsystems, improve the simulator fidelity and support the design and validation of the second controller. Each controller has required specifics flight tests aimed to validates particular functionalities and control performance. Testing has included the design and building of a single axis test-bench in order to perform the very first control tuning in a safety way. The objective of the first controller was the attitude stabilization of the quadrotor in order to perform a hovering flight initially and the attitude tracking later. The design of the attitude controller has required the identification of the actuator dynamics as well as the sensors calibration. The attitude control unit has been implemented in all its parts and successfully tested in real flight. As mentioned before, the next step has been focused on controlling the quadrotor position within a limited flight area. In particular, this study investigates the use of the feedback linearization approach as a novel way to design the internal model for EMC. The feedback linearization allows us to collect all the non-linearities at the command level. EMC, by means of a disturbance dynamics model, makes possible to estimate and then reject the non-linear terms through the control law. The control solution has been validated by means of intensive numerical simulations and real-flight tests. As a final result, the control units developed in this work enhance the EMC applicability to non-linear systems, such as quadrotor UAVs, and evidence the EMC disturbance rejection capabilities
New Nanocomposite Materials with Improved Mechanical Strength and Tailored Coefficient of Thermal Expansion for Electro-Packaging Applications
No full textIn this research, copper nanocomposites reinforced by graphene nanoplatelets (GNPs) were fabricated using a wet mixing method followed by a classical powder metallurgy route. In order to find the best dispersion technique, ball milling and wet mixing were chosen. Qualitative evaluation of the structure of the graphene after mixing indicated that the wet mixing is an appropriate technique to disperse the GNPs. Thereafter, the influence of graphene content on microstructure, density, hardness, elastic modulus, and thermal expansion coefficient of composites was investigated. It was shown that by increasing the graphene content the aggregation of graphene is more obvious and, thus, these agglomerates affect the final properties adversely. In comparison with the unreinforced Cu, Cu-GNP composites were lighter, and their hardness and Young's modulus were higher as a consequence of graphene addition. According to the microstructural observation of pure copper and its composites after sintering, it was concluded that grain refinement is the main mechanism of strengthening in this research. Apart from the mechanical characteristics, the coefficient of thermal expansion of composites decreased remarkably and the combination of this feature with appropriate mechanical properties can make them a promising candidate for use in electronic packaging applications
Micromechanics modeling of unit cells using CUF beam models and the Mechanics of Structure Genome
No full textFinite beam elements based on Legendre polynomial expansions and node-dependent kinematics for the global-local analysis of composite structures
No full textThis work introduces an innovative type of FEM beam models with node-dependent kinematics. A variety of global-local approaches have been proposed to reduce the consumption of computational resources in FEM analysis, in which mostly the main idea is to couple the elements in the locally refined region (with either refined mesh or higher-order theories) and those in the less refined area. As a new method to build FEM models in a global-local analysis, node-dependent kinematics makes it possible to construct elements with different kinematic theories on different nodes and implement a kinematic variation conveniently within an element to bridge a local model to a global one. With the help of the introduced cross-section functions, CUF allows the definition of different kinematics on each node and their interpolation over the axial domain of the beam element. Without using any ad hoc coupling method, beam elements with node-dependent kinematics have very compact and coherent formulations through the Fundamental Nucleus (FN). Corresponding FEM governing equation is derived from the Principle of Virtual Displacements (PVD), and the expressions of FNs of the stiffness matrix and load vector are given. Both ESL (Equivalent Single-layer) and LW (Layer-wise) models are addressed. In fact, in this work, Legendre polynomials are used to construct refined beam models, obtaining cross- section functions (nodal kinematics) with Hierarchical Legendre Expansions (HLE) and, eventually, LW accuracy. In the numerical examples, refined models with HLE are employed in the local area with a higher stress gradient, and in the less critical regions ESL models are adopted; meanwhile, in the kinematic transition zone, a beam element with node-dependent kinematics are used to connect these two domains. By comparing the numerical results with those in literature and from 3D FEM modeling, it is demonstrated that when used in the analysis of composite beams with local effects to be considered, node-dependent kinematic beam elements can reduce the computational costs significantly without losing numerical accuracy
Comparing network-centric and power flow models for the optimal allocation of link capacities in a cascade-resilient power transmission network
No full textAnalysis of a Moon outpost for Mars enabling technologies through a Virtual Reality environment
No full textThe Moon is now being considered as the starting point for human exploration of the Solar System beyond low-Earth orbit. Many national space agencies are actively advocating to build up a lunar surface habitat capability starting from 2030 or earlier: according to ESA Technology Roadmaps for Exploration this should be the result of a broad international cooperation. Taking into account an incremental approach to reduce risks and costs of space missions, a lunar outpost can be considered as a test bed towards Mars, allowing to validate enabling technologies, such as water processing, waste management, power generation and storage, automation, robotics and human factors. Our natural satellite is rich in resources that could be used to pursue such a goal through a necessary assessment of ISRU techniques. The aim of this research is the analysis of a Moon outpost dedicated to the validation of enabling technologies for human space exploration. The main building blocks of the outpost are identified and feasible evolutionary scenarios are depicted, to highlight the incremental steps to build up the outpost. Main aspects that are dealt with include outpost location and architecture, as well as ISRU facilities, which in a far term future can help reduce the mass at launch, by producing hydrogen and oxygen for consumables, ECLSS, and propellant for Earth-Moon sorties and Mars journeys. A test outpost is implemented in a Virtual Reality (VR) environment as a first proof-of-concepts, where the elements are computer-based mock-ups. The VR facility has a first-person interactive perspective, allowing for specific in-depth analyses of ergonomics and operations. The feedbacks of these analyses are crucial to highlight requirements that might otherwise be overlooked, while their general outputs are fundamental to write down procedures. Moreover, the mimic of astronauts' EVAs is useful for pre-flight training, but can also represent an additional tool for failures troubleshooting during the flight controllers' nominal operations. Additionally, illumination maps have been obtained to study the light conditions, which are essential parameters to assess the base elements location. This unique simulation environment may offer the largest suite of benefits during the design and development phase, as it allows to design future systems to optimize operations, thus maximizing the mission's scientific return, and to enhance the astronauts training, by saving time and cost. The paper describes how a virtual environment could help to design a Moon outpost for an incremental architecture strategy towards Mars missions