Archivio Istituzionale della Ricerca - Università degli Studi di Pavia
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Zero Deforestation Commitments and Industry 4.0 Enabling Technologies: An Analysis of Their Role in Mitigating Deforestation
No full textEstimating the population size and density of Italian wall lizards (Podarcis siculus) through photo identification capture-recapture
No full textIn the face of a global biodiversity crisis, accurate estimates of population parameters â especially size and survival â are critical for effective conservation, yet such data are often scarce due to logistical, financial, and methodological challenges. Reptiles in Europe are particularly underrepresented in population studies. Although many are protected under the EU Habitats Directive, robust estimates of population density and survival exist for fewer than half of the listed species. In this study, we present a demographic assessment of the Italian wall lizard (Podarcis siculus) using capture-mark-recapture (CMR) methods. Fieldwork was carried out in 2019 at three distinct sites in Central and Southern Italy. We employed photographic identification combined with Jolly-Seber models to estimate population size, separately for males and females. Population densities showed marked spatial variation, ranging from 102 to 384 individuals per hectare. Apparent survival and detection probabilities also varied substantially, probably reflecting differences in local environmental conditions and habitat structure. These findings reveal significant demographic heterogeneity among populations, consistent with patterns observed in other Podarcis species. Our study demonstrates the applicability and reliability of CMR approaches for reptile monitoring and underscores the need for standardized long-term population data to inform conservation management. Importantly, these represent the first density estimates for P. siculus based on CMR, helping to address a major data gap for this species of conservation concern
Design and characterization of innovative medical devices
No full textChronic skin conditions such as non-healing ulcers and pathological scars represent a major unmet
clinical challenge due to their prevalence, limited therapies, and impact on quality of life. Current
treatments rarely modulate aberrant scarring or support regeneration effectively, while
pharmacological options show limited efficacy and systemic risks. Biomaterials therefore offer
unique opportunities to design therapeutic systems combining structural, mechanical, and bioactive
functions. This PhD project aimed to develop innovative biomaterials for medical devices targeting
wound healing and scar management, articulated across seven chapters. The research spans
bioinspired graded scaffolds, protein-chitosan complexes, and drug-free microneedles modulating
mechanotransduction, to inorganic-organic nanocomposites, like chitosan-nanoclay composites,
improving mechanics, adhesion, and hydration. Advanced microneedle systems incorporating
carvacrol-loaded sepiolite demonstrated antifibrotic potential in keloid models. Finally, a regulatory
review contextualized substance-based medical devices under MDR 2017/745. Collectively, the
thesis bridges material innovation, biological validation, and regulatory translation
Don't waste the waste: by-products from viticulture and local crops management as source of extracts and/or secondary metabolites with biological properties
No full textFourth-order isogeometric phase-field modeling of dynamic brittle fracture: Numerical study and comparison with second-order models
No full textWe provide a thorough numerical investigation on phase-field simulations for dynamic brittle fracture; our analysis focuses on numerical performance, in terms of computational time and accuracy, measured by quantitative physical properties: energy conservation, crack speed, and critical stress. Simulations are performed by means of a semi-implicit staggered scheme, combining a Newmark method with the Projected Successive Over-Relaxation algorithm. This coupling ensures both an accurate solution of the elasto-dynamic equation and an effective solution of the linear complementarity problem, arising in the evolution of the phase-field parameter. In particular, with the Newmark method numerical dissipation is almost negligible; as a result, energy is conserved and simulations feature a remarkable representation of P and S waves, which irradiate from the boundary condition and from the tip, reflect on the boundary and interact with each other. While accuracy requires both small time increments and small mesh sizes, which easily lead to unaffordable computational time, we employ a fourth order AT1 functional that allows (as a rule of thumb) to halve the mesh size, and then halve the time increment. This multiplicative effect produces a remarkable saving of computational time (up to the order of 90%) without compromising the quality of the results. Moreover, AT1 functionals, compared with AT2, feature a sharp value of the critical stress and sharper damage profiles and showcase in all results a gain in accuracy. We employ an isogeometric framework that yields a straightforward discretization of the higher-order operators. First, we provide a calibration of the weight in front of the higher-order term, balancing the trade-off between accuracy and computational cost. Then, we compare the results obtained with second- and fourth-order AT1 and AT2 energies, using a few benchmark setups designed to focus the analysis on specific computational and physical aspects
ASIC Front-End Integrato nella Sonda per Imaging Ultrasonico Biomedico 3D basato su MUT
No full textQuesto lavoro ha presentato la progettazione, l’implementazione e la validazione sperimentale di un ASIC front-end personalizzato a quattro canali per sistemi di imaging in-probe basati su CMUT, realizzato in tecnologia BCD-SOI a 160 nm. L’obiettivo principale è stato quello di ottenere un’interfaccia mista analogico-digitale compatta, a basso rumore ed elevata efficienza energetica, in grado di operare nel rispetto dei requisiti stringenti imposti dall’eccitazione ad alta tensione dei CMUT e dalla ricezione di segnali acustici a larga banda.
L’ASIC proposto integra quattro canali di ricezione indipendenti, ciascuno comprendente due interruttori TX/RX ad alta tensione, un amplificatore a basso rumore (LNA) e un driver di linea in classe AB. Un regolatore LDO integrato e condiviso fornisce una tensione di alimentazione pulita a 1,8 V, garantendo prestazioni analogiche robuste e un’adeguata isolazione tra i canali. Gli interruttori TX/RX sono stati progettati per gestire impulsi di eccitazione bipolari fino a 200 Vp–p utilizzando esclusivamente un’alimentazione di 3,3 V, assicurando una protezione affidabile e basse correnti di perdita in modalità di ricezione, senza la necessità di polarizzazioni ad alta tensione esterne.
La caratterizzazione elettrica ha confermato un guadagno misurato pari a 17 dB e una larghezza di banda a –3 dB compresa tra 60 kHz e 8 MHz, dimostrando un’ampia dinamica operativa adatta a array CMUT funzionanti intorno ai 3 MHz. La densità di rumore riferita all’ingresso è risultata pari a 12,2 nV/√Hz, corrispondente a un Noise Efficiency Factor (NEF) di 0,854 nV√W/√Hz, rappresentando uno stato dell’arte nel compromesso rumore–potenza per questa classe tecnologica. La distorsione armonica di secondo ordine (HD2) è stata misurata pari a –37,7 dB per un segnale di ingresso di 20 mVp–p, validando la linearità degli stadi di amplificazione e di pilotaggio. Il crosstalk inter-canale misurato, pari a –36 dB, ha ulteriormente confermato la robustezza delle scelte di layout, della distribuzione di potenza e delle strategie di isolamento adottate.
Le misure acustiche hanno verificato il corretto funzionamento di ciascun percorso di ricezione in un setup sperimentale in vasca d’acqua, in cui l’elemento CMUT ha trasmesso e ricevuto segnali di eco riflessi da un bersaglio metallico. L’ASIC ha amplificato con successo il debole segnale di eco ricevuto, preservandone l’integrità e confermando la piena funzionalità acustica del sistema. Tali risultati dimostrano che l’ASIC front-end proposto è in grado di supportare in modo affidabile sia la fase di trasmissione sia quella di ricezione nei sistemi di imaging basati su CMUT.
Dal punto di vista dell’integrazione di sistema, il chip presenta un’area attiva totale di 2 mm2, corrispondente a soli 0,13 mm2 per canale, rappresentando una riduzione significativa rispetto alle soluzioni di stato dell’arte precedenti, che occupano tipicamente 0,75–0,9 mm2 per canale. Il consumo di potenza totale pari a 20,1 mW (4,9 mW per canale) garantisce la compatibilità con implementazioni in sonde compatte, dove l’efficienza energetica e la gestione termica risultano aspetti critici. Il confronto con recenti lavori pubblicati su JSSC 2021 ed ESSCIRC 2022 evidenzia come l’ASIC proposto offra un compromesso superiore tra rumore, potenza e area, validando l’efficacia delle topologie circuitali e delle metodologie di layout adottate.
La tecnologia BCD-SOI a 160 nm ha consentito l’integrazione di dispositivi ad alta tensione, componenti analogici di precisione e regolazione di potenza on-chip all’interno di un unico die, evidenziando il potenziale di questa piattaforma per futuri sistemi front-end per ultrasuoni scalabili. In conclusione, questa ricerca contribuisce con una soluzione ASIC completamente integrata, a basso rumore ed elevata efficienza in area, ottimizzata per applicazioni di imaging basate su CMUT.This work presented the design, implementation, and experimental validation
of a custom four-channel front-end ASIC for CMUT-based in-probe imaging
systems, fabricated in a 160-nm BCD-SOI technology. The primary objective
was to achieve a compact, low-noise, and power-efficient mixed-signal interface
capable of operating under the demanding requirements of high-voltage CMUT
excitation and broadband acoustic signal reception.
The proposed ASIC integrates four independent receive channels, each
comprising two HV TX/RX switches, an LNA, and a class-AB cable driver. A
shared on-chip LDO regulator provides a clean 1.8-V supply rail, enabling
robust analog performance while maintaining channel-to-channel isolation.
The TX/RX switches were designed to handle bipolar excitation pulses up
to 200 Vp–p using only a 3.3 V supply, thereby ensuring reliable protection
and low leakage in receive mode without the need for external HV biasing.
Electrical characterization confirmed a measured gain of 17 dB and a –3 dB
bandwidth from 60 kHz to 8 MHz, demonstrating a wide dynamic range suit-
able for CMUT arrays operating around 3 MHz. The input-referred noise den-
sity was measured at 12.2 nV/√Hz, resulting in an NEF of 0.854 nV√W/√Hz,
representing state-of-the-art noise–power performance in this technology class.
The HD2 was measured at –37.7 dB for a 20 mVp–p input, validating the lin-
earity of the LNA and driver stages. The measured inter-channel crosstalk of
–36 dB further confirmed the robustness of the layout, power routing, and
isolation strategy.
Acoustic measurements verified the correct operation of each receive path
in an experimental water-tank setup, where the CMUT element transmitted
and received echo signals from a metallic reflector. The ASIC successfully
amplified the weak received echo, maintaining signal fidelity and confirming full acoustic functionality. These results demonstrate that the proposed front-
end ASIC can reliably support both transmission and reception phases in
CMUT-based imaging systems.
From a system integration standpoint, the chip achieves a total active
area of 2 mm2, corresponding to only 0.13 mm2 per channel—representing
a substantial reduction compared to prior state-of-the-art designs occupy-
ing 0.75–0.9 mm2 per channel. The total power consumption of 20.1 mW
(4.9 mW per channel) ensures compatibility with compact probe implementa-
tions, where power efficiency and thermal management are critical.
When compared to recent JSSC’21 and ESSCIRC’22 designs, the proposed
ASIC demonstrates a superior trade-off among noise, power, and area, vali-
dating the effectiveness of the adopted circuit topologies and layout method-
ologies. The 160-nm BCD-SOI process enabled the integration of high-voltage
devices, precision analog components, and on-chip power regulation within
a unified die, illustrating the potential of this technology for future scalable
ultrasound front-end systems.
In conclusion, this research contributes a fully integrated, low-noise, and
area-efficient ASIC solution optimized for CMUT-based imaging applications.
The presented architecture establishes a foundation for next-generation minia-
turized ultrasound probes and intravascular imaging catheters, where high
channel density, low power, and broadband operation are essential. Future
work may focus on extending the design toward multi-frequency operation,
on-chip digital beamforming, and advanced calibration techniques to further
enhance image quality and integration at the probe level
Novel Approaches to Quantum State Tomography
No full textQuantum state tomography (QST) aims at reconstructing the representation of a quantum state from the measurement of a sufficiently large number of observables. Traditionally, in QST the number of required observables grows exponentially with the dimension of the Hilbert space associated with the system under consideration, unless a priori knowledge of the state is available. In practice, QST becomes infeasible for systems of limited size. Thus, it is necessary to develop novel methods that are easy to implement and allow one to reconstruct high-dimensional states. The focus of this PhD research is to improve the efficiency of QST protocols. The main goal is to develop QST approaches that do not make any assumptions about the state to be reconstructed, reduce the number of required observables, are computationally efficient, and are experimentally feasible. The core idea is to introduce a threshold parameter that allows an efficient trade-off between the number of observables and the accuracy of the state reconstruction. Threshold quantum state tomography (tQST) is the first protocol based on this concept, tailored to systems composed of qubits that can be measured via projective measurements, and the state is reconstructed via maximum likelihood estimation. In many cases, including those of interest for technological applications, tQST works and accurately reconstructs the density matrix. We leveraged the feasibility of the protocol to numerically validate it on computer-generated data and experimentally test it on two different platforms, a superconducting and a photonic one. We show that tQST can drastically reduce the resources required for state reconstruction, but it can also be used to obtain an approximate density matrix by further reducing the number of measurements and the experimental efforts. State reconstruction can also be performed using tools other than maximum likelihood estimation. Furthermore, the tQST protocol might allow us to estimate quantities that are functions of the density matrix elements, such as purity, without reconstructing the entire state. We investigated this possibility through an original deep learning model that leverages the specific symmetries of the density matrix to enhance its performance. We then develop the enhanced compressive threshold QST (ECT-QST) protocol, specifically designed for systems composed of qudits where one can implement measurement settings. As an extension of tQST, ECT-QST is tailored for multiplexing platforms where one can perform projective measurements on all the basis vectors of a given setting. We numerically validate and experimentally test ECT-QST on the same platforms as tQST. Finally, moving beyond application matters, we turn to deeper questions and examine a problem at the crossroads of information theory and energetics, which are at the core of modern physics. We explore ECT-QST and QST through the lens of the quantum Maxwell demon, directly comparing their roles in the fundamental challenge of quantum work extraction.Quantum state tomography (QST) aims at reconstructing the representation of a quantum state from the measurement of a sufficiently large number of observables. Traditionally, in QST the number of required observables grows exponentially with the dimension of the Hilbert space associated with the system under consideration, unless a priori knowledge of the state is available. In practice, QST becomes infeasible for systems of limited size. Thus, it is necessary to develop novel methods that are easy to implement and allow one to reconstruct high-dimensional states. The focus of this PhD research is to improve the efficiency of QST protocols. The main goal is to develop QST approaches that do not make any assumptions about the state to be reconstructed, reduce the number of required observables, are computationally efficient, and are experimentally feasible. The core idea is to introduce a threshold parameter that allows an efficient trade-off between the number of observables and the accuracy of the state reconstruction. Threshold quantum state tomography (tQST) is the first protocol based on this concept, tailored to systems composed of qubits that can be measured via projective measurements, and the state is reconstructed via maximum likelihood estimation. In many cases, including those of interest for technological applications, tQST works and accurately reconstructs the density matrix. We leveraged the feasibility of the protocol to numerically validate it on computer-generated data and experimentally test it on two different platforms, a superconducting and a photonic one. We show that tQST can drastically reduce the resources required for state reconstruction, but it can also be used to obtain an approximate density matrix by further reducing the number of measurements and the experimental efforts. State reconstruction can also be performed using tools other than maximum likelihood estimation. Furthermore, the tQST protocol might allow us to estimate quantities that are functions of the density matrix elements, such as purity, without reconstructing the entire state. We investigated this possibility through an original deep learning model that leverages the specific symmetries of the density matrix to enhance its performance. We then develop the enhanced compressive threshold QST (ECT-QST) protocol, specifically designed for systems composed of qudits where one can implement measurement settings. As an extension of tQST, ECT-QST is tailored for multiplexing platforms where one can perform projective measurements on all the basis vectors of a given setting. We numerically validate and experimentally test ECT-QST on the same platforms as tQST. Finally, moving beyond application matters, we turn to deeper questions and examine a problem at the crossroads of information theory and energetics, which are at the core of modern physics. We explore ECT-QST and QST through the lens of the quantum Maxwell demon, directly comparing their roles in the fundamental challenge of quantum work extraction