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A mixed reality framework for interpretable and explainable joint replacement assessment
No full textExperimental Approach of Thermal Management Properties for Phase Change Materials in Energy Storage Modules at Different Power Loading
No full textEfficient thermal management of lithium-ion batteries is essential to increase safety, extend service life and improve operating range, while ensuring stable performance in electric vehicles. Although phase change materials (PCMs) have been extensively studied in the context of thermal control systems, systematic experimental evaluations conducted on commercially available pure PCMs are still limited. This study experimentally analyses the thermal performance of pure PCMs with melting points of 42°C, 47°C, and 57°C by subjecting them to thermal loads of 20, 40, and 80 W in a simulated energy storage module based on a 2S2P configuration of 18 650 cylindrical cells. The thermal response of the system was monitored using thermocouples and infrared thermography, while the thermophysical properties of the PCMs (latent heat, specific heat, and thermal conductivity) were characterized using DSC calorimetry and thermal conductivity analysis. To assess material reliability, all PCMs were subjected to 100 consecutive thermal cycling tests. Based on module-level results, the most effective PCM was further validated through 2C charge–discharge cycling of a commercial lithium-ion cell, followed by post-cycling structural examination using X-ray micro-computed tomography. The results demonstrate that PCM integration reduces maximum operation temperatures by up to 40°C–60°C compared to the reference case without PCM, depending on the thermal load. Among the tested materials, PCM with a melting point of 47°C showed the most balanced performance, providing temperature uniformity, extended delay times and stable behavior under both thermal and electrochemical cycling. Overall, the results confirm that pure PCMs are a practical solution to improve the safety and thermal stability of electrochemical storage systems
Numerical investigation of different morph wing configurations for the rolling maneuver
No full textWing design in the last decades directed efforts and studies to improve the aircraft performance allowing fuel reduction, which implies more ecological and sustainable solutions and cost reduction for air transportation. Efficient design with a morph wing can fulfill such objectives. Different concepts of morph wing have been numerically investigated in this study proposing different wing configurations with the aim to improve aircraft performance in particular for the rolling maneuver. The assessment is performed by using an aerodynamic analysis based on a low fidelity 2D method such as the panel method, in combination with a 3D analysis using vortex lattice method, without considering elastic structural effects. The main morph wing concept is based on the constant morph of a part of the wing tip which has the aim of acting as a control surface hence as a substitution of the aileron for the rolling maneuver. The twist will then be applied linearly decreasing to the center of the wing. Within this concept three main configurations were evaluated: (a) the twist of the fixed airfoil section (Morph type M1 – rib twist), (b) the twist of the aileron which profile is changing according to a curvilinear law based on two morph angles (Morph type M2) and (c) both trailing edge and leading edge are morphed (Morph type M3). A comparison with a correspondent conventional aileron configuration at the same rolling moment coefficient showed an advantage of the morph wing in terms of drag coefficient with reductions that go up to 30%. It was also observed that in some cases such as M1 and M2C a morph deflection lower than 10° produce the same rolling moment coefficient of a typical small aircraft aileron deflection of 25°. Moreover, a parametric evaluation showed an optimum of the span wise parameter yrib to be 40% of the semi span b. Furthermore, a smoother distribution of the lift along the span wise direction will be determined in comparison with a conventional aileron. This also implies a smoother approach to stall conditions that can be beneficial for the pilot
Measuring the distance between single random inputs and OWA operators
No full textConsidered a random sample of fixed cardinality extracted from a population with unknown distribution, this paper deals with the ability of an Ordered Weighted Averaging (OWA) operator to approximate the distance between the values it assumes and the single observation of the sample. To this purpose, a measure of distance between random quantities recently introduced in the literature is considered, which takes into account both their mutual dependence and the shape of their distributions. Conditions are identified on the weights of the OWA operator that
minimize this distance, or for which the different distances are ordered as the weights of two different operators vary. The paper also considers the case of operators defined as mixture of order statistics and, subsequently, the case of input values from populations with different distributions, showing conditions on these distributions that highlight the importance of the inputs in the value assumed by this distance
Folding and Deployment Simulation of Elastically Foldable Flat Arrays Using Refined Beam Finite Elements
No full textThis work explores the numerical simulation of the folding of complex structures consisting of pairs of Triangular Rollable and Collapsible (TRAC) longerons linked by transverse battens and parallel hinges. The analysis uses the Carrera Unified Formulation (CUF), which divides the three-dimensional displacement field of the structure into axial and cross-sectional terms, enabling one-dimensional beam finite elements to be used without sacrificing accuracy. Higherorder CUF models capture cross-sectional deformation through nine-point Lagrange expansions, extending through the whole structure. Thus, the numerical model of a complete structure consists of a single beam. An implicit quasi-static scheme, coupling Newton–Raphson iterations with displacement control is used across all analyses. Contact between the longerons is represented by nonlinear spring elements assigned to prescribed pairs of nodes
Reducing CM Conducted EMI in Output Filterless WBG Traction Inverters by Means of a Dummy Leg
No full textThe design of traction inverters for electric vehicles poses several challenges, particularly in reducing Common Mode (CM) conducted Electromagnetic Interference (EMI) without the use of bulky input filters. This paper proposes a novel approach based on a small dummy leg, which acts as a source of canceling switching noise. By connecting the dummy leg to the motor chassis through a given impedance, CM current cancellation is achieved when active zero state modulations are employed. To this purpose, the design procedure for the impedance loading the dummy leg is proposed, together with an optimized control method of the dummy leg. Experimental results validate the effectiveness of this approach in a real-case scenario, achieving up to up to 30 dB reduction in the 150 kHz-1MHz range, thus reducing the input filter volume and overall system cost compared to conventional solutions
Semantic Segmentation to Improve Remeshing of 3D Human Characters
No full textThe retopology of a 3D mesh is the process of optimizing the position of the vertices defining its surface to obtain a "cleaner" geometrical representation. Retopology plays a vital role in achieving professional results in various creative and technical fields. Existing automatic methods cannot achieve the results provided by skilled professionals due to the variety of geometrical features characterizing 3D meshes and the large number of conflicting constraints. This research investigates a novel approach that leverages a semantic segmentation of the input model to mimic the human approach of identifying different mesh areas in the retopology process. Edge loops between adjacent semantic regions are used to define the feature lines to be preserved by a field-align remeshing method. The use case consists of the remesh of 3D human-like models to be rigged and animated. The topological quality of the output and its suitability for animation have been evaluated over multiple metrics, and results show that introducing a semantic segmentation step in the retopology pipeline consistently improves the remesh of 3D human models
Photovoltaic energy conversion models with clustering-based classification of days from irradiance data
No full textIn the literature, many contributions compare the effectiveness of different energy models for photovoltaic (PV) generators in specific installation sites. Most techniques are analytical or based on electrical equivalent circuits. However, only a few works investigate the performance of the models in different weather classes. The parameter mostly used to classify the days into weather categories is the clearness index. An alternative parameter is the clear sky index. However, information about their values and ranges in different weather conditions is missing in the literature. This paper is based on data gathered in Italy, Brazil and Portugal, at different latitudes, with fixed and sun-tracking configurations of the PV generators, and for different weather conditions, and has a twofold objective. First, the clearness index is shown to be inappropriate to represent general situations, while the clear sky index is suitable to identify consistent ranges that represent different sunny, partly cloudy and cloudy days, at different latitudes and PV configurations, by using a clustering procedure. Next, the effectiveness of the PV energy conversion models for different installation sites is evaluated, showing which model is more suitable for each site and type of day. In this context, a model based on single diode model is proposed, formulated after numerically determining the parameters of the equivalent circuit. The parameters under reference conditions and the coefficients of the equations that quantify the dependency on weather conditions have been numerically optimized starting from experimental datasets of PV modules
Lumped Parameter Modelling of High-Energy-Density and High-Speed Rotors With Passive Magnetic Supports
No full textThis study presents a lumped parameter model of a High-Energy-Density and High-Speed Rotor developed in MAT-LAB/Simulink. The model includes several sources of nonlinearity including the use of circumferentially segmented Passive Magnetic Supports (PMB) and the presence of backup bearings. Simulink provides an efficient computational framework for implementing the governing equations, allowing the rapid evaluation of critical speeds, resonance conditions, and dynamic stability in different operative conditions. The methodology employed in this research combines analytical and computational techniques. In the first part, the modelling of segmented PMB is investigated. It introduces superharmonic characteristics, which influences the rotor dynamic behaviour and stability, analysed through frequency and time-domain response simulations, providing insights of the system performance. In the second part, the inclusion of backup bearings is performed by defining inelastic collision mechanism, crucial for predicting the system’s behaviour during abnormal operating conditions. The results from the simulations show the effectiveness of the lumped parameter model in predicting key dynamic behaviours, such as critical speeds and stability margins. The model has broad applications in the study of high-speed rotating systems. This work emphasizes nonlinear modelling relevance to Flywheel Energy Storage Systems (FESS). In FESS, high-speed rotors are a critical component, and their dynamic performance is crucial to achieving competitive energy storage performance, such as round-trip efficiency, when compared to electrochemical storage systems
The Role of HVDC Transmission Systems in the Evolution of the Italian Power System
Get PDFThis paper explores the potential contributions of modern High-Voltage Direct-Current (HVDC) transmission systems to the Italian National Power System, with a focus on adequacy and security, and providing an overview of their role in system stability. An operational methodology is proposed to assess the impact of planned infrastructure developments, within the context of medium- to long-term forecast scenarios. To this end, starting from a model of the current transmission network, a prospective model of the primary transmission grid for the year 2040 was developed, covering voltage levels of 230 kVAC, 400 kVAC, and 525 kVDC. Load-flow analysis under both N and N-1 conditions was performed, with particular emphasis on the Ionian-Tyrrhenian HVDC backbone "Priolo-Rossano-Latina"