1,355,069 research outputs found
Cambodian Performing Arts in the Era of UNESCO’s Intangible Cultural Heritage
No full textUNESCO’s protection of Intangible Cultural Heritage (ICH) has been a topic of ongoing debate inthe field of Cambodian performing arts. UNESCO’s recognition as ICH means that international attention and renewed economic opportunities arise for the selected performing arts and thus can help to preserve cultural practices that are at risk of being lost. In Cambodia, only a handful of teachers and performers survived the brutalities of Pol Pot’s regime (1975-79), and the incorporation of the artistic traditions into a global scenario, also thanks to the UNESCO cultural strategy, has led to the possibility of revitalizing and rebuilding both old and new repertoires. This is certainly the case regarding the musical tradition of Chapei Dang Veng and the dance-drama Lkhon Khol Wat Svay Andet, registered in the “List of the Intangible Cultural Heritage in Need of Urgent Safeguarding” in 2016 and 2018 respectively. However, considering the “branding” effect of listing and heritage-making, ICH seems to open the doors to mass tourism and in general favors over-commercialization and folklorization of cultural practices, leading to the erosion of their religious significance
Reconstruction of 3D X-ray tomographic images from sparse data with TV-based methods
No full textQuesta tesi propone l'implementazione efficiente di due metodi iterativi per la ricostruzione di immagini tridimensionali di tomografia a raggi X, nel caso specifico in cui il volume debba essere ottenuto da dati sottocampionati. Quando le proiezioni non possono essere acquisite completamente, la risultante
tecnica di Tomografia Computerizzata Sparsa (SpCT) è descritta da un sistema lineare sottodeterminato, quindi ne riformuliamo il modello aggiungendo il termine di Variazione Totale (TV). Definiamo pertanto un problema di ottimizzazione e lo risolviamo con un algoritmo di Gradiente Scalato Proiettato e uno di Punto Fisso. Entrambi i metodi sono stati accelerati con valide strategie, calibrate appositamente per la SpCT. In questo contesto è infatti necessario ricostruire un'immagine in brevissimo tempo, risolvendo un problema di ampie dimensioni. Alcuni test di simulazione forniscono buoni risultati che attestano la validità sia dell'approccio model-based che dei metodi proposti. Accurate ricostruzioni sono state ottenute a partire da proiezioni mediche reali, in poche iterazioni: ciò conferma l'adeguatezza di quanto proposto per la ricostruzione di immagini nel campo della SpCT
A GIS‐Based Approach for Primary Substations Siting and Timing Based on Voronoi Diagram and Particle Swarm Optimization Method
No full textThe paper aims to provide primary substations’ optimal siting and timing to expand ex-isting distribution networks. The proposed methodology relies on three main features: a geographic information system for capturing, elaborating, and displaying spatial input data; a particle swarm optimization algorithm to locate and timing the new primary substations; a Voronoi diagram‐based approach to find the primary substation service areas and loading. The optimization criteria follow the approach of serving every customer from the nearest primary substation to ensure that the distribution delivery distance is as short as possible, reducing feeders’ cost, electric losses, and service interruption exposure. The algorithm also considers the primary substation transformers’ capacity limit. Thanks to Unareti, the distribution system operator of Milan and Brescia, the methodology was tested by carrying out several simulations, progressively increasing the number of new primary substations. The results obtained confirm the proposed approach’s effectiveness and show that the methodology is a valuable tool to guide Unareti, and distribution system operators in general, in expanding distribution networks to face the challenges of the energy transition
In litigation we trust: riflessioni su magistratura, politica e processo civile a partire dal rapporto tra Donald Trump e judiciary
No full textMachine Learning and GIS Approach for Electrical Load Assessment to Increase Distribution Networks Resilience
No full textCurrently, distribution system operators (DSOs) are asked to operate distribution grids, managing the rise of the distributed generators (DGs), the rise of the load correlated to heat pump and e-mobility, etc. Nevertheless, they are asked to minimize investments in new sensors and telecommunication links and, consequently, several nodes of the grid are still not monitored and tele-controlled. At the same time, DSOs are asked to improve the network’s resilience, looking for a reduction in the frequency and impact of power outages caused by extreme weather events. The paper presents a machine learning GIS-based approach to estimate a secondary substation’s load profiles, even in those cases where monitoring sensors are not deployed. For this purpose, a large amount of data from different sources has been collected and integrated to describe secondary substation load profiles adequately. Based on real measurements of some secondary substations (medium-voltage to low-voltage interface) given by Unareti, the DSO of Milan, and georeferenced data gathered from open-source databases, unknown secondary substations load profiles are estimated. Three types of machine learning algorithms, regression tree, boosting, and random forest, as well as geographic information system (GIS) information, such as secondary substation locations, building area, types of occupants, etc., are considered to find the most effective approach
L’ipotesi di una terza via tra i modelli di responsabilità civile degli insegnanti
No full textLa responsabilità civile degli insegnanti conosce un doppio regime di responsabilità, a titolo extracontrattuale per i danni cagionati da un allievo a terzi, contrattuale da inadempimento per i danni che l’allievo cagiona a se stesso. Nonostante tale diversità, i due titoli di responsabilità richiedono una prova
liberatoria estremamente rigorosa, che svaluta l’effettivo grado di colpevolezza dell’insegnante. È lecito, quindi, domandarsi se abbia ancora senso prevedere un regime di responsabilità degli insegnanti così stringente, ai limiti della responsabilità oggettiva, se poi, nei fatti, è la Pubblica Amministrazione che interviene nel processo a riparare i danni, surrogandosi nel processo al posto dell’insegnante. La logica di trovare in ogni caso un soggetto responsabile potrebbe lasciare il posto a strumenti alternativi, come, ad esempio, l’attivazione di assicurazioni per i danni prodotti nel contesto scolastico
Litispendenza, connessione, cumulo oggettivo: interferenze e regime delle preclusioni a seguito della riunione (App. Catanzaro, 6 luglio 2023)
No full textDEVELOPMENT OF A VIRTUAL TESTING LABORATORY FOR LOWER LIMB PROSTHESIS
No full textThe introduction of computer-aided tools into the product development process allows improving the quality of the product, evaluating different variants of the same product in a faster way and reducing time and costs. They can play a meaningful role also in designing custom-fit products (especially, those characterized by a tight interaction with the human body), increasing the comfort and improving people’s quality of life.
This thesis concerns a specific custom-fit product, the lower limb prosthesis. It is part of a research project that aims at developing a new design platform centred on the digital model of the patient and his/her characteristics. The platform, named Prosthesis Virtual Laboratory (PVL), is being developed by the V&K Research Group (University of Bergamo) and integrates ICT tools and product-process knowledge. It provides two environments: one for prosthesis design (named Prosthesis Modelling Lab), both transfemoral and transtibial, and one for the prosthesis testing (named Virtual Testing Lab).
The main objective has been to embed within the Virtual Testing Environment numerical simulation tools to analyse the interaction between the socket and the residual limb under different loading conditions, allowing the prosthetist to automatically run the simulation and optimize socket shape. Simulation tools, such as Finite Element Analysis (FEA), permit to predict the pressures at the interface socket-residual limb, evaluate the comfort of socket and validate the socket design before manufacturing phase. However, the diffusion of simulation tools in orthopaedic laboratories is strongly limited by the high level of competence required to use them. Furthermore, the implementation of the simulation model is time consuming and requires expensive resources, both humans and technological, especially onerous for small orthopaedic labs. To effectively employ the numerical analysis in prosthesis design, the simulation process has been automated and embedded within the virtual design platform. Therefore, in such a context, the specific scientific objectives have been to:
• Critically analyse the state of the art with regard to methods and tools to evaluate socket-residual limb interaction.
• Identify the key issues to automate the simulation activities.
• Define a set of simulation rules and the Finite Element Analysis model.
• Implement and integrate within the new design platform the automatic simulation procedure.
• Test the integrated design platform with a case study.
• Identify future development trends.
Research activities have been organized into four main activities as follows.
The first activity consisted in an extensive analysis of the last two decades State of the Art on numerical models adopted to study residual lower-limb and prosthetic socket interaction. Starting from literature, the key issues of the simulation process (e.g., geometric models reconstruction, materials characterization, simulation steps, and boundary conditions), the methodologies and procedures have been identified. Particular attention has been also paid to the parameters commonly adopted to evaluate socket comfort. This phase played a fundamental role since it constituted the basis for the implementation of the embedded simulation procedure. It also permitted to highlight that current finite element models are stand-alone and not integrated with prosthetic CAD or Digital Human Modelling (DHM) systems.
In the second activity the tools and methods necessary to develop the embedded simulation module have been selected. By using these tools, it was possible to identify the simulation rules and the best practice procedures, which are fundamental to implement an automatic simulation module. Initially, the modelling tools have been considered since they provide the geometric models for the numerical analysis of the socket-residuum interaction and for the virtual gait analysis of the patient’s avatar. Then, particular attention has been paid on the choice of the FE solver, that has been made according to the results of preliminary FE models. They were implemented using two different solvers: Abaqus (commercial) and CalculiX (open-source). The latter has been experimented to verify the possibility to develop a design platform totally independent from commercial tools. However, according to the results, Abaqus has been chosen because it allows managing adequately simulation problems characterized by large deformations and difficult contact conditions, its results are comparable with those found in literature, and its scripting code does not require specific customization. The last considered tool was the Digital Human Modelling system (LifeMOD) since it permits to enhance the accuracy of the numerical analysis. By performing the gait simulation of the patient’s avatar, it provides the directions and the magnitude of forces and moments that act on the socket.
The third activity consisted in defining the architecture of the simulation module, implementing the module and the interfaces with the socket CAD tool (namely Socket Modelling Assistant-SMA) to get the geometric models of the involved parts (socket and residual limb) and with the DHM system to acquire forces acting on the socket during patient’s walking. The simulation module has been implemented using the Python language and the integrated environment works as follows. Once the prosthetist has created the 3D socket model, SMA acquires the input for the analysis (e.g., residual limb length, patient’s weight, friction coefficient, material properties), and produces the files required to generate the FE model. Abaqus automatically generates the FE model without any human intervention, solves the analysis and generates the output file containing the pressure values. Results are imported in SMA and visualized with a colour map. SMA evaluates pressure distribution and highlights the areas that should be modified. Geometry modifications are needed in the areas where pressure exceeds the maximum value and are carried out automatically by the system or by the prosthetist using the virtual tools available in SMA. Then, the system re-executes the simulation. Through this iterative process of adjustments, the socket shape is modified and optimized in order to eliminate undercuts, minimize weight and, especially, distribute loads in the appropriate way so that they can be tolerated for the longest period of time.
The fourth and last activity concerned the test and validation of the simulation module integrated within the new design platform, by considering a transfemoral patient. The new virtual process and the key issues of the simulation procedure have been tested starting from the patient’s data acquisition to the release of the socket using also data coming from the gait simulation with the DHM system. The geometric model of the residual limb has been reconstructed from MRI images and the socket has been modelled using SMA. Through an iterative process, the socket shape has been optimized until the pressure distribution on the residuum was consistent. Preliminary activity concerning the FE model validation has been performed comparing the pressure distribution experimentally acquired with pressure transducers over the residuum with the simulation results. To accomplish this task, the geometric model of the real socket has been acquired using reverse engineering techniques. Two numerical simulations have been implemented, they differ for the residuum geometric models adopted: from MRI and from 3D scanning. Preliminary results have been considered positive but improvements are necessary. As an example, some geometric inconsistencies, occurred during the acquisition of the geometric model of the residual limb, have reduced the accuracy of the final results. To complete the evaluation of the simulation model, a new residuum geometric model is needed and a refinement of the material model characterization is desirable.
To conclude, the simulation module embedded within Virtual Testing Laboratory has improved the prosthesis development process with the goal of assessing and validating the socket shape under different load conditions (static or dynamic) before the manufacturing phase. The testing phase of the new procedure has demonstrated the feasibility of the virtual approach for lower limb prosthesis design. The tests carried out permitted to highlight necessary improvements and future developments, such as the definition of a protocol to acquire the residual limb through MRI and 3D scan, refinement of the FE model (e.g., non-linear viscoelastic behaviour for soft tissues, friction coefficients), parallel computing to improve simulation performances, open-source solvers to implement a design platform totally independent from commercial systems, and a massive test campaign involving transtibial and transfemoral patients to fully validate the FE model and the design platform
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