Politecnio die Bari - Catalogo di prodotti della Ricerca
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Upwind Filtering of Scalar Conservation Laws
No full textWe study a class of multidimensional nonlocal conservation laws of the form \partial tu=
div\Phi F(u), where the standard local divergence div of the flux vector F(u) is replaced by an average
upwind divergence operator div\Phi acting on the flux along a continuum of directions given by a
reference measure and a filter \Phi . The nonlocal operator div\Phi applies to a general nonmonotone flux
F, and is constructed by decomposing the flux into monotone components according to wave speeds
determined by F\prime . Each monotone component is then consistently subjected to a nonlocal derivative
operator that utilizes an anisotropic kernel supported on the ``correct"" half of the real axis. We
establish well-posedness, derive a priori and entropy estimates, and provide an explicit continuous
dependence result on the kernel. This stability result is robust with respect to the size of the kernel,
allowing us to specify \Phi as a Dirac delta \delta 0 to recover entropy solutions of the local conservation
law \partial tu= div F(u) (with an error estimate). Other choices of \Phi (and the reference measure) recover
known numerical methods for (local) conservation laws. This work distinguishes itself from many
others in the field by developing a consistent nonlocal approach capable of handling nonmonotone
fluxes
Novel Approaches for Layer-Level Functionally Graded Materials via PBF-LB/M
No full textPowder Bed Fusion-Laser Beam (PBF-LB/M) enables the production of Functionally Graded Materials (FGMs) with tailored properties for specific applications. This study explores a novel method for creating FGMs within layers using a custom powder separation system that integrates seamlessly with existing PBF-LB plants employing blade/roller spreading. Two distinct approaches were implemented: the ex-situ method, where powders were pre-mixed before deposition in transition zones; and the other, which employed an innovative setup for in-situ real-time powder mixing during deposition. AISI 316L stainless steel and CoCrMo alloy were chosen for their excellent mechanical properties, biocompatibility and corrosion resistance, making them optimal for aerospace and biomedical applications. Results from microstructural analysis, mechanical testing and chemical characterization confirm the reliability and cost-effectiveness of this approach, highlighting its potential to advance multi-material AM
Industrial metamorphoses. Art saving industry (once again)
No full textThe paper considers one aspect among the many induced by the succession of the industrial revolutions: the concept of obsolescence. From the era of industrial revolutions onwards, this concept accompanies the production of objects, creating a very strong ideological contrast with the concept of art, which by definition
does not know the obsolescence or craftsmanship, which knows him only when the object meets its final break.
But not only: industrial revolutions have always been marked by buildings that, as they proved insufficient, were gradually abandoned.
These processes of obsolescence and insufficiency are unavoidable, as they belong to the same nature of the technology. However, some trends can be opposed to them, which today constitute a real phenomenology: in the case of objects, we talk about recycling, reuse, or the modern age; in the case of buildings, we talk about adaptive reuse, re-functionalization, or industrial archaeology. These last attitudes, respectively, attribute an unprecedented qualitative value to the products of industrial revolutions, which for this very reason, must in some way call into question art in an attempt to overcome any temporal limitation imposed. Not surprisingly, among the many uses for rethinking these buildings, today are those for theatrical or musical buildings and museums.
Through the analysis of Italian case studies, the reasoning is conducted on these questions and some emerging issues today relevant to reassigning a function for this large part of architectural heritage
Managing Innovation in European Research Projects
No full textThis paper presents a new innovation management approach in research projects. Based on the transformation from Open Innovation to User-Centric Innovation, going through Networked Innovation, the starting point of the proposed innovation process is the investigation of the users and stakeholders needs. In the presented approach, users and innovators exchange information to satisfy stakeholders needs. In order to meet these requirements, innovators develop Innovation Tools (Its) as a result of innovation activities. The concept of “Innovation Tools” is introduced as the mean to meet users’ needs and objectives. As a result of the study, a new innovation management strategy is defined. The defined strategy can be applied in European founded research projects. The originality of the presented work is the introduction of the novel innovation management approach called “European Project User-Centric Innovation” (EP U-CI), that can be applied in European founded research projects. The value of the EP U-CI strategy is enlightened by the application to the Horizon Europe IN2CCAM project and consists in the centrality of the users needs and in the way stakeholders interact with the innovators
Partial least squares regression analysis of natural gas-like mixtures absorption spectra collected using a mid-infrared supercontinuum broadband source
No full textWe report on a broadband gas sensor based on direct absorption spectroscopy in the mid-infrared range for the simultaneous detection of methane, ethane, and propane in natural gas-like mixtures. The system employs a broadband supercontinuum light source, coupled with an absorption cell and an optical spectrum analyzer with a resolution of 0.5 cm-1. This configuration enables reconstruction of the full absorption bands of the target alkanes, which exhibit significant spectral overlap in the 2.8-3.2 μm spectral region. A comparative study between multiple linear regression (MLR) and partial least-squares regression (PLSR) was conducted to determine the concentration of each individual component. The results highlight the superior performance of PLSR in the presence of unbalanced concentration ratios (1:10) among the three alkanes, achieving mean prediction accuracy of 98%, 93% and 94% for methane, ethane, and propane, respectively
Vulnerabilità fisica e recupero funzionale: uno studio biomeccanico che utilizza sensori indossabili
No full textLa vulnerabilità si riferisce a uno stato di stabilità fisica, emotiva e cognitiva che rischia di essere compromesso o alterato a causa della suscettibilità a influenze destabilizzanti. In questa tesi, l'attenzione sarà focalizzata sulla vulnerabilità fisica del corpo umano, che sarà classificata come fragilità, instabilità posturale e debolezza muscolare, e vulnerabilità biomeccanica e percettiva. L'attenzione si è concentrata sullo sviluppo di un framework per valutare e monitorare la vulnerabilità fisica umana attraverso sensori indossabili da integrare in soluzioni tecnologiche innovative. Gli aspetti della vulnerabilità studiati sono la fragilità negli anziani, il recupero funzionale nei pazienti ortopedici che hanno subito un intervento chirurgico e persone soggette a stress noti per causare cinetosi, ossia mal d’auto. Un altro fattore comune a tutti gli studi è stato la scelta della strumentazione utilizzata e la successiva elaborazione dei dati: sono stati scelti sensori indossabili (unità di misura inerziale, IMU, e sonde per l'elettromiografia di superficie, sEMG).
I risultati hanno dimostrato che l'uso di sensori indossabili consente la raccolta di dati oggettivi e quantitativi, essenziali rispetto all'uso di strumenti che consentono solo valutazioni qualitative, come scale cliniche e questionari. Inoltre, le caratteristiche biomeccaniche ottenute attraverso l'elaborazione dei dati raccolti sono risultate correlate alla stabilità, il che potrebbe aiutare a prevedere la debolezza, ma anche facilitare la valutazione del recupero funzionale. Infine, lo studio preliminare sulla cinetosi ha mostrato una vulnerabilità transitoria ma significativa del sistema sensomotorio, dimostrata dall'attività muscolare dei muscoli del collo, che sono stati attivati in momenti critici durante il percorso in auto.
In conclusione, da questi studi emerge chiaramente che la vulnerabilità fisica è una dimensione fisiologica e multifattoriale; è un indicatore della complessità del sistema corporeo, che può modulare continuamente le sue risposte in base agli stimoli ambientali, sensoriali e meccanici.Vulnerability refers to a state of physical, emotional, and cognitive stability that is in danger of being disturbed or destroyed due to being susceptible to destabilizing influences. In this thesis, the focus will be on the physical vulnerability of the human body, which will be categorized as frailty, postural instability, and muscle weakness, and therefore as biomechanical and perceptual vulnerability. The focus was on developing a framework to assess and monitor human physical vulnerability through wearable sensors to integrate into innovative technological solutions. The aspects of vulnerability studied are frailty in the elderly, functional recovery in orthopaedic patients who have undergone surgery, and people being subjected to stresses that are known to cause motion sickness.
Another common factor in all studies was the choice of instrumentation used and subsequent data processing: wearable sensors (Inertial Measurement Unit, IMU, and probes for surface electromyography, sEMG) were chosen.
The results demonstrated that the use of wearable sensors allows the collection of objective and quantitative data, which is essential compared to the use of instruments that only allow qualitative assessments. Furthermore, biomechanical features obtained through the processing of collected data emerged as being related to stability, which could help predict weakness, but can also facilitate the evaluation of functional recovery. Lastly, the preliminary study of motion sickness has shown a transient but significant vulnerability of the sensorimotor system, demonstrated by the muscle activity of the neck muscles, which were activated at critical moments during the car ride.
In conclusion, it is clear from these studies that physical vulnerability is a physiological and multi-factorial dimension; it is an indicator of the complexity of the body system, which can continuously modulate its responses according to environmental, sensory, and mechanical stimuli
Induction thermography as a powerful tool to crack detectability and quantification: a feasibility study at consistent scanning speeds
No full textThis work investigates the potential of induction thermography for quantitatively assessing surface-breaking cracks under dynamic inspection conditions. Experimental tests were conducted on S355J2 steel specimens with artificial notches of varying depth and length, scanned at a constant speed of 4 km/h. A thermal contrast-to-noise ratio was computed for each crack and correlated with its geometry in terms of length and depth using a power-law calibration, enabling an empirical probability of detection (POD) curve derivation. A Finite Element Model (FEM) was used to simulate the electromagnetic-thermal response and physically interpret the contrast variation with depth. The results demonstrate the feasibility of depth and length quantification under motion and support induction thermography as a fast, non-contact method for both crack detection and characterisation in industrial environments
How Powerful are LLMs to Support Multimodal Recommendation? A Reproducibility Study of LLMRec
No full textLarge language models (LLMs) have been exploited as standalone recommender systems (RSs) and, more recently, as support tools for already existing RSs. A notable example of the latter is LLMRec [28], which prompts a LLM with the user-item data, the items' metadata, and the candidate items generated by other multimodal RSs to obtain an augmented version of the original dataset where a final RS is trained on. While a few recent studies have proposed reproducing and rigorously evaluating LLM-based recommender systems (RSs) as standalone approaches (first research line), little to no attention has been devoted to exploring the use of LLMs as supportive components within existing RSs, particularly in the context of multimodal recommendation (second research line). To this end, in this work, we propose the first reproducibility study of a LLMs-based RS belonging to the second research line, LLMRec, in the multimodal recommendation domain. First, we try to replicate the results of LLMRec with the authors' provided data and our own reconstructed data, outlining critical issues in the measured recommendation performance. Then, we benchmark LLMRec: (i) with unimodal and multimodal LLMs, showing how the latter may be more beneficial in a multimodal scenario; (ii) other competitive multimodal RSs, LLMs-based solutions, and an additional dataset, demonstrating inconsistencies with the trends emerging in the original paper. Finally, in an attempt to disentangle the observed performance trends, we evaluate (for the first time in the literature) the topological differences of the original user-item graph to the LLMRec's augmented one