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PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)
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    Digital Twin, Virtual Reality and Metaverse: what technologies to support the asset management workforce?

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    The challenging paradigm of the Digital Twin of construction combined with the new possibilities offered by information and visualization technologies provide innovative ways to approach, study, and investigate the risk and vulnerability of an area. The Digital Twin is proposed as a digital copy of an artefact, city or territory overcoming the use of Geographic information system (GIS) and Building Information Models (BIM) as capable of establishing a bi-directional data transfer between the physical object and the model (Khallaf et al., 2022). On the other hand, three-dimensional dealing with infrastructure has opened up new horizons related to communication and the fruition of the assets, expanding the pool of users that can be reached. If the digital model is the computer representation of the work containing all the information for its life cycle, the virtual model is an interactive simulation of it. The Spoke TS2 of the RETURN project also reflects how these methodological and technological advances can be leveraged to enhance the asset management workforce and forecasting capacity. In particular, situational awareness applications are considered for the staff's re-skilling and up-skilling. In this context, WebGIS platforms, Virtual Reality experiences, and the new frontier of the Metaverse can play a role. Geospatial technologies promote spatial thinking skills and enhance content knowledge necessary to examine linear infrastructure, which requires a multi-scalar approach concerning their specific connotation. Possible integration with BIM, which examines the scale of the point artefact, enhances the system capability by allowing it to move from particular to broader context. As understanding the context is necessary for comprehending the problems, the WebGIS framework enables integration, simulation, analysis, and visualization of the GIS technology result in an online environment. The distribution of spatial geographic information is, at this point, interfaced with big data from the sensor network, empowering stakeholders’ decisions based on real-time changing situations. Through Decision Support Systems, they can have valuable information for planning and management without so much effort and time. According to the literature, incorporating traditional knowledge into modern technology is suitable for disaster risk reduction education. In recent years, web hazard maps have received attention not only from experts but also from students (Song et al., 2022), and flood resilience information systems for raising awareness among citizens (Albano et al., 2015). On the other hand, the navigability of the model achievable through Virtual Reality (Ghobadi et al., 2020) technologies overturn the condition of the observer on both an experiential and conceptual level. Starting from digital models, it is possible to promote engaging and stimulating cognitive experiences to illustrate even to a non-technical or non-expert audience how complex constructions work so that political and economic choices can be made with greater awareness. The immediacy and hypermedia nature of the graphical representation makes the virtual model a powerful tool that enables more effective dialogue in, for example, local authorities planning conferences and service meetings. At the same time, it makes it possible to create innovative training solutions for the training of actors who operate in different roles on infrastructures: improving knowledge of sites, even those that are difficult to reach; transferring skills for maintenance; simulating or reproducing critical situations (Tender et al., 2023), such as emergencies or failures, which when they occur require a rapid response. Let us imagine the potential and stakeholder interest in simulating an accident interconnected perhaps to a natural event on a railroad tunnel section. Examining the situation in a realistic and safe environment without needing to be in the field allows for the best assessment of safety procedures and operation management efficiency while also reducing costs. As the final frontier, the Metaverse (Ritterbusch et al., 2023) emerges as the further evolution of these immersive and multimedia environments by enabling their interconnection and decentralization based on open platform. Unlike the traditional virtual world, the concept of community emerges strongly, emphasizing much more realistic interaction between people and with their surroundings. As we glimpse the possibilities are remarkable. Are we ready for change

    Comparison of Different Approaches to Derive Global Safety Factors for Non-linear Analyses of Slender RC Members

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    The present study relates to comparison between different approaches for definition of global safety factors for non-linear analysis of slender RC members with reference to new or existing structures. Firstly, a benchmark set of 40 experimental results on reinforced concrete columns is presented. After the description of the main features of the benchmark test sets the related non-linear numerical models have been realized using fiber-modelling as solution strategy. Then, appropriate assumptions concerning aleatoric and epistemic uncertainties have been performed with the aim to run probabilistic analysis of global resistance for each one of the 40 columns. The results of the probabilistic analysis are useful to define global safety factors in line to the global resistance method. Finally, the comparison between different approaches to derive global safety factors is presented and discussed

    Stochastic ordering of variability measure estimators

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    Variability measures, such as the variance or the Gini mean difference, are widely used to summarize the dispersion of random variables. In the statistical setting, it is quite natural to assume that if a random quantity has more variability, then the estimators of its variability measures should be greater in some stochastic sense. Stochastic orders can be used to give inequalities in this regard, confirming, or not, this suitable property. This paper is devoted to the stochastic comparison of some variability measure estimators; conditions such that some of these estimators are comparable in the usual stochastic order and in the increasing convex order whenever the involved random variables have different variability are provided. Special attention is devoted to the cases of sample variance and Gini mean differences, and to the case of simple random samples

    Digital Twinning for the Prognosis of Spatial Architectures: Morandi’s Underground Pavilion in Turin

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    Concrete spatial architecture was mainly built using techniques that at the time were still experimental and based on design criteria that did not consider seismic actions. The validity of accurate models accounting for such complex structural schemes can be demonstrated, but the latter still would not support a clear comparison with the original predictions. Different from other Morandi’s balanced beam schemes, in the underground Pavilion V of Turin Exhibition Center the main post-tensioned ribs are not parallel beams but are diagonally directed and multiply reciprocally interconnected in order to obtain a spatial structure offering a high overall rigidity and lateral stability, and to contrast the instability of the very thin webs of the main ribs. The paper focuses on how information from the experimental campaign can help to formulate virtual models for prognostic and diagnostic assessments under different scenarios, such as for example the design of structural health monitoring activities and systems

    Dynamic behavior of porous graphite under laser-induced shocks

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    The present study focuses on developing reliable numerical models to describe the mechanical behavior of isotropic polycrystalline graphite subjected to laser shocks. Isotropic graphite of nuclear grade, which was extensively used in Beam Intercepting Devices of particle accelerators, is characterized by a high porosity enabling effective absorption of laser-induced shockwaves. Accurate numerical models which aim at describing shockwaves traveling inside porous graphite must take into account the effect of pores on the structural response of the material. In this work the Fu Chang foam material model was calibrated to capture the behavior of R4550 graphite. Based on the foam material model, hydrodynamic simulations were developed and compared to experimental data from literature and from PHELIX experimental campaign

    On durable materials for dielectric-barrier discharge plasma actuators

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    In the current experimental investigation various electrode and dielectric materials for dielectric-barrier discharge plasma actuators have been studied in quiescent air under consideration of actuator degradation during long-term operation. The performance variation of the different actuators was initially monitored via alteration of the electrical power consumption P̄a during 6-hour continuous operation. While some material combinations led to premature failure, certain dielectrics such as quartz-glass and aluminum oxide maintained constant performance. The latter was selected for screen-printing of electrodes, so as to obtain reproducible actuator geometries. These actuators were deployed in 10-hour continuous operation. Besides P̄a, the cold capacitance C0 was tracked for each actuator, in order to assess the degradation process of the actuator. Among the tested metals for the screen-printed electrodes, copper showed the best endurance characteristics and, thus, is recommended for both comparable laboratory experiments and durability in AFC application. Admixtures of platinum in the electrode material are to be avoided because of heavy oxidation under ozone exposition.The quantitative outcomes supported by the P̄a and C0 measurements were qualitatively supported by visual inspection of the actuators and of the discharge light emission. On a final note, the screen-printed copperaluminum-oxide actuator configuration, featuring both good durability and reproducibility, is a recommended combination

    Optimization of Customized Industrial Pneumatic Nozzle to Reduce Noise Emissions

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    This study proposes a customized industrial nozzle for generating impulsive air jets. It is installed on an automatic machine where wine caps are stacked and shot consecutively into a rotating cyl-inder by an air jet. This process is very noisy; hence, this study aimed to investigate possible geo-metric variations of the nozzle that can reduce the emitted noise. First, the nozzle was tested in a laboratory to measure the air consumption at different supply pressures. Subsequently, 3D models of the nozzle and its variations were created and used for computational fluid dynamics simula-tions. Different boundary conditions were set, first to validate the model and compare it with the experimental test results, and then to simulate the real working conditions and determine the geometry that is less noisy while maintaining the velocity peak. Among the various possibilities, shortening the final ducts of the nozzle appears to be the most promising solution. These modified nozzles could be easily added to current machines to provide immediate benefits, and this study represents a promising start for action on other machines where this type of device is present

    3D bioprinting of multifunctional alginate dialdehyde (ADA)–gelatin (GEL) (ADA-GEL) hydrogels incorporating ferulic acid

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    : The present work explores the 3D extrusion printing of ferulic acid (FA)-containing alginate dialdehyde (ADA)-gelatin (GEL) scaffolds with a wide spectrum of biophysical and pharmacological properties. The tailored addition of FA (≤0.2 %) increases the crosslinking between FA and GEL in the presence of calcium chloride (CaCl2) and microbial transglutaminase, as confirmed using trinitrobenzenesulfonic acid (TNBS) assay. In agreement with an increase in crosslinking density, a higher viscosity of ADA-GEL with FA incorporation was achieved, leading to better printability. Importantly, FA release, enzymatic degradation and swelling were progressively reduced with an increase in FA loading to ADA-GEL, over 28 days. Similar positive impact on antibacterial properties with S. epidermidis strains as well as antioxidant properties were recorded. Intriguingly, FA incorporated ADA-GEL supported murine pre-osteoblast proliferation with reduced osteosarcoma cell proliferation over 7 days in culture, implicating potential anticancer property. Most importantly, FA-incorporated and cell-encapsulated ADA-GEL can be extrusion printed to shape fidelity-compliant multilayer scaffolds, which also support pre-osteoblast cells over 7 days in culture. Taken together, the present study has confirmed the significant potential of 3D bioprinting of ADA-GEL-FA ink to obtain structurally stable scaffolds with a broad spectrum of biophysical and therapeutically significant properties, for bone tissue engineering applications

    Numerical Simulation of Heat Pipe Thermal Performance for Aerospace Cooling System Applications

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    The design of integrated and highly efficient solutions for thermal management is a key capability for different aerospace products, ranging from civil aircraft using hydrogen on board to miniaturized satellites. In particular, this paper discloses a novel numerical tool for the design and thermal performance assessment of heat pipes. To achieve this goal, a numerical Ansys Parametric Design Language code is set up to verify the effective subtractive heat flux guaranteed by the selected heat pipe arrangement. The methodology and related tool show their ability to provide good thermal performance estimates for different heat pipe designs and operating conditions. Specifically, the paper reports two very different test cases: (1) solid metal heat pipes to cool down the crotch leading-edge area of the air intake of a Mach 8 civil passenger aircraft, and (2) a copper-water heat pipe to cool down a Printed Circuit Board of a generic small LEO satellite. The successful application of the methodology and numerical code confirms the achievement of the ambitious goal of developing in-house tools to support heat pipe thermal performance prediction for the entire aerospace domain

    Semidiscrete Modeling of Systems of Wedge Disclinations and Edge Dislocations via the Airy Stress Function Method

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    We present a variational theory for lattice defects of rotational and translational type. We focus on finite systems of planar wedge disclinations, disclination dipoles, and edge dislocations, which we model as the solutions to minimum problems for isotropic elastic energies under the constraint of kinematic incompatibility. Operating under the assumption of planar linearized kinematics, we formulate the mechanical equilibrium problem in terms of the Airy stress function, for which we introduce a rigorous analytical formulation in the context of incompatible elasticity. Our main result entails the analysis of the energetic equivalence of systems of disclination dipoles and edge dislocations in the asymptotics of their singular limit regimes. By adopting the regularization approach via core radius, we show that, as the core radius vanishes, the asymptotic energy expansion for disclination dipoles coincides with the energy of finite systems of edge dislocations. This proves that Eshelby's kinematic characterization of an edge dislocation in terms of a disclination dipole is exact also from the energetic standpoint

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