78 research outputs found
Innovative method for damage identification and structural health monitoring based on vibration measurements
No full text[ITALIANO] Scopo della tesi è presentare una nuova metodologia, appartenente al campo dei Controlli Non Distruttivi, e basata su misure di vibrazioni, sviluppata dall’autore presso il Dipartimento di Progettazione Aeronautica dell’Università degli Studi di Napoli “Federico II”. Scopo della ricerca è stato sviluppare una tecnica di controllo non distruttivo che soddisfacesse la maggior parte dei requisiti necessari allo sviluppo di un sistema di Health Monitoring (monitoraggio dello stato di salute di una struttura), riducendo nel contempo la complessità sia dell’algoritmo di analisi dei dati sia della strumentazione necessaria per l’acquisizione degli stessi.
La tecnica proposta è basata sulla acquisizione e sul confronto delle Funzioni di Risposta in Frequenza (FRF) della struttura monitorata, prima e dopo che un qualsivoglia danno insorga. Per effetto di un danneggiamento strutturale si viene a modificare il comportamento dinamico della struttura in termini di massa, rigidezza e smorzamento, e, conseguentemente, si avrà una variazione delle Funzioni di Risposta in Frequenza relative alla struttura danneggiata rispetto a quelle ricavate dalla struttura integra. Il metodo è quindi in grado di rilevare l’insorgere di un danneggiamento (identificazione), localizzarne la posizione (individuazione), ed indicarne l’eventuale accrescimento e propagazione (quantificazione). Ai fini della valutazione quantitativa della variazione tra le Funzioni di Risposta in Frequenza della struttura integra e di quella danneggiata è stato definito un indice detto “del danno”, il quale fornisce direttamente la misura dell’eventuale presenza del danneggiamento strutturale.
La sopra citata metodologia è stata applicata su di un pannello reale di fusoliera di un MD11, su di un pannello realizzato in materiale composito di tipo aeronautico, e su di un velivolo ATR-72.
È stato sviluppato inoltre un algoritmo di Reti Neurali al fine di ottenere un metodo di apprendimento basato sulla ricognizione. Questa tecnica di apprendimento consente di addestrare la rete neurale rendendola in grado di riconoscere solo gli esempi “positivi”, scartando, di conseguenza, quelli “negativi”. Nell’ambito di un controllo non distruttivo di una struttura un esempio “positivo” rappresenta uno stato di “salute” del componente strutturale analizzato, e, ovviamente, un esempio “negativo” rappresenta uno stato “danneggiato” dello stesso. Sulla base di questo obiettivo le reti neurali sono state addestrate facendo uso delle stesse FRF, relative alle strutture “sane”, impiegate per la determinazione degli Indici del Danno.
Con riferimento al danno: corrosione, danneggiamento di rivetti di collegamento, cricche, impatti su strutture ed altre tipologie di danneggiamenti sono stati indotti sugli articoli di prova.
Relativamente al sistema di eccitazione e sensoristica, dispositivi magnetostrittivi sono stati impiegati quali attuatori, e piastrine piezoceramiche in qualità di attuatori e sensori. Inoltre è stato impiegato, per l’acquisizione delle FRF, anche un sistema di vibrometria laser a scansione. Queste tecniche consentiranno lo sviluppo di un sistema di Health Monitoring automatico in grado di identificare danni strutturali in tempo reale, aumentando l’affidabilità strutturale e riducendo i costi di manutenzione. / [ENGLISH] The purpose of the thesis is to present an innovative application within the Non Destructive Testing field based upon vibration measurements developed by the author at the Department of Aeronautical Engineering of the University of Naples “Federico II” (Italy). The aim of the research has been to develop a Non Destructive Test (NDT) which meets most of the mandatory requirements for effective health monitoring systems while, at the same time, reducing as much as possible the complexity of the data analysis algorithm and the experimental acquisition instrumentation.
This proposed new method is based upon the acquisition and comparison of the Frequency Response Functions (FRFs) of the monitored structure before and after a damage occurs. Structural damage modifies the dynamic behaviour of a structure affecting its mass, stiffness and damping and consequently the FRFs of a damaged structure, when compared with the FRFs of a sound structure, makes the identification, localization and quantification of structural damage possible.
The activities presented in this thesis focus mainly on a new FRFs processing technique based upon the determination of a representative “Damage Index” for identifying and analysing damage on real-scale aeronautical structural components, such as large-scale fuselage reinforced panels, on aeronautical composite panels and on a real ATR-72 aircraft.
Furthermore, a dedicated neural network algorithm has been elaborated aimed at obtaining a “recognition-based learning” method. This kind of learning methodology permits us to train the neural network in order to enable it to recognise only “positive” examples and consequently discarding “negative” ones. Within the structural NDT a “positive” example means a “healthy” state of the analysed structural component and, obviously, a “negative” example means a “damaged” or perturbed state. With this objective in mind the neural network has been trained to make use of the same FRFs of the healthy structure used in determining the Damage Index.
Regarding damage, corrosion, failure of linking rivets, simple cracks, impacts on structure and other kind of damage have been induced on the test articles.
From an architectural standpoint, magnetostrictive devices have been tested as actuators, and piezoceramic patches as actuators and sensors. Besides it has been used a laser-scanning vibrometer system to acquire the FRFs. These techniques promise to bring us a step forward in the implementation of an automatic “health monitoring” system which will be able to identify structural damage in real time thereby improving safety and reducing maintenance costs
Philosophical tributes: Between apathy and acknowledgment: (Rico Bovio-Pallares Ronquillo case, an historiographic commentary)
No full textIn this article we study a pair of collective books about a two Chihuahuan Philosophy professors, Enrique Pallares Ronquillo and Arturo Rico Bovio. Both recognized for their teaching and thought. However, some historiographical questions are unsolved through the main part of the chapters. How it can be described and understand the philosophical work of each one? Which is the social, political, intellectual and cultural context in which their philosophies were born and had been developed? Which connection had each acknowledgment book author with Pallares and Rico? In which way contribute both texts to nourishing the weak local philosophy’s memory
Homenajes filosóficos: entre la apatía y el reconocimiento (el caso Pallares Ronquillo-Rico Bovio, comentario historiográfico)
No full textResumen: En este trabajo se revisa el contenido de dos libros
de homenaje acerca de dos profesores chihuahuenses de
Filosofía: Enrique Pallares Ronquillo y Arturo Rico Bovio.
Ambos reconocidos por su labor pedagógica y sus ideas. Sin
embargo, existen varios cuestionamientos historiográficos que
quedan sin resolver a lo largo de la mayor parte de los capítulos.
¿Cómo ha de describirse y comprenderse el trabajo filosófico
de ambos?, ¿cuál es el medio político, social, intelectual y
cultural en el que surgieron y se desarrollaron sus filosofías?,
¿qué vínculo tiene cada autor, que participó en los libros de
homenaje, con Rico y Pallares?, ¿de qué manera contribuyen
ambos textos con la flaca memoria de la filosofía local?
Palabras clave: filosofía de la actualidad, filosofía del norte de
México, historiografía de la Filosofía, memoria, pensamiento
contemporáneo.
Abstract: In this article we study a pair of collective books
about a two Chihuahuan Philosophy professors, Enrique
Pallares Ronquillo and Arturo Rico Bovio. Both recognized for
their teaching and thought. However, some historiographical
questions are unsolved through the main part of the chapters.
How it can be described and understand the philosophical
work of each one? Which is the social, political, intellectual
and cultural context in which their philosophies were born
and had been developed? Which connection had each
acknowledgment book author with Pallares and Rico? In
which way contribute both texts to nourishing the weak local
philosophy’s memory?
Keywords: contemporary thought, historiography of
Philosophy, memory, Northern Mexican philosophy, today’s
philosophy
Homenajes filosóficos: entre la apatía y el reconocimiento (el caso Pallares Ronquillo-Rico Bovio, comentario historiográfico)
No full textResumen: En este trabajo se revisa el contenido de dos libros
de homenaje acerca de dos profesores chihuahuenses de
Filosofía: Enrique Pallares Ronquillo y Arturo Rico Bovio.
Ambos reconocidos por su labor pedagógica y sus ideas. Sin
embargo, existen varios cuestionamientos historiográficos que
quedan sin resolver a lo largo de la mayor parte de los capítulos.
¿Cómo ha de describirse y comprenderse el trabajo filosófico
de ambos?, ¿cuál es el medio político, social, intelectual y
cultural en el que surgieron y se desarrollaron sus filosofías?,
¿qué vínculo tiene cada autor, que participó en los libros de
homenaje, con Rico y Pallares?, ¿de qué manera contribuyen
ambos textos con la flaca memoria de la filosofía local?
Palabras clave: filosofía de la actualidad, filosofía del norte de
México, historiografía de la Filosofía, memoria, pensamiento
contemporáneo.
Abstract: In this article we study a pair of collective books
about a two Chihuahuan Philosophy professors, Enrique
Pallares Ronquillo and Arturo Rico Bovio. Both recognized for
their teaching and thought. However, some historiographical
questions are unsolved through the main part of the chapters.
How it can be described and understand the philosophical
work of each one? Which is the social, political, intellectual
and cultural context in which their philosophies were born
and had been developed? Which connection had each
acknowledgment book author with Pallares and Rico? In
which way contribute both texts to nourishing the weak local
philosophy’s memory?
Keywords: contemporary thought, historiography of
Philosophy, memory, Northern Mexican philosophy, today’s
philosophy
Comparative Understory Development in Fenced and Unfenced Beech Forest Stands in the Southern Alps
No full textThis study examines the impact of ungulate browsing on the understory dynamics of the Cansiglio Forest, the only European beech high forest in the Southern Limestone Alps. Utilizing seven pairs of fenced versus unfenced forest stands established over two decades, we assessed how fencing affects understory structure and tree regeneration. Significant differences were found in cover, height and vascular species composition in both tree regeneration and shrub layers. Fenced areas showed a significantly higher number and greater average height of young trees, supporting the hypothesis that ungulate browsing negatively impacts tree regeneration. Despite previous studies attributing the lack of silver fir (Abies alba Mill.) regeneration primarily to red deer (Cervus elaphus Linnaeus, 1758) browsing, our findings did not show a significant association of this species with fenced conditions. While Rubus abundance was higher inside fenced areas, overall vascular species richness did not differ. Our results highlight the evident effects of ungulate browsing and suggest the need to consider other factors influencing forest regeneration and understory development. Future research should establish additional study replicates, balanced across diverse site and stand structure conditions, to further explore these dynamics
Dandelion pappus morphing is actuated by radially patterned material swelling
No full text<p>The dandelion pappus opens and closes reversibly to tune seed dispersal according to environmental moisture levels.</p>
<p>In the Nature Communications paper "<em>Madeleine Seale, Annamaria Kiss, Simone Bovio, Ignazio Maria Viola, Enrico Mastropaolo, Arezki Boudaoud, Naomi Nakayama</em>, <strong>Dandelion pappus morphing is actuated by radially patterned material swelling</strong>, https://doi.org/10.1038/s41467-022-30245-3 the authors combined experiments with a computational model to show that pappus closure is coordinated by radially-patterned tissue swelling at the base of floral organs.</p>
<p>This repository contains the source data for the paper.</p>
Surface Confinement Induces the Formation of Solid-Like Insulating Ionic Liquid Nanostructures
No full textWe
report on the modification of the electric properties of the
imidazolium-based [BMIM][NTf2] ionic liquid upon surface
confinement in the sub-monolayer regime. Solid-like insulating nanostructures
of [BMIM][NTf2] spontaneously form on a variety of insulating
substrates, at odds with the liquid and conductive nature of the same
substances in the bulk phase. A systematic spatially resolved investigation
by atomic force microscopy of the morphological, mechanical, and electrical
properties of [BMIM][NTf2] nanostructures showed that this
liquid substance rearranges into lamellar nanostructures with a high
degree of vertical order and enhanced resistance to mechanical compressive
stresses and very intense electric fields, denoting a solid-like character.
The morphological and structural reorganization has a profound impact
on the electric properties of supported [BMIM][NTf2] islands,
which behave like insulator layers with a relative dielectric constant
between 3 and 5, comparable to those of conventional ionic solids
and significantly smaller than those measured in the bulk ionic liquid.
These results suggest that, in the solid-like ordered domains confined
either at surfaces or inside the pores of the nanoporous electrodes
of photoelectrochemical devices, the ionic mobility and the overall
electrical properties can be significantly perturbed with respect
to the bulk liquid phase, which would likely influence the performance
of the devices
Investigation of interfacial properties of supported [BMIM][NTf2] thin films by atomic force microscopy
No full textWe report the results of an atomic force microscopy investigation of the morphological and structural properties of thin films of [C4mim][NTf2] ionic liquid on mica, amorphous silica, oxidised Si(110), and highly-oriented pyrolytic graphite. We show that [C4mim][NTf2] forms solid-like ordered structures on these surfaces at room temperature, with a vertical structural periodicity of 0.6 nm. Moreover, we analyse the contact angles of nano-scale [C4mim][NTf2] droplets on the different surfaces and show that they are sensitive to the chemical and morphological environment. Our findings highlight the potentialities of atomic force microscopy for the quantitative investigation of the interfacial properties of thin ionic liquid coatings. The results of this study suggest that at the liquid-solid interface, the structural properties of ionic liquids can be far more complex than those depicted so far, and indicate new fundamental investigations of the forces that drive supported ionic liquids through a liquid-to-solid-like transition
Dandelion pappus morphing - FreeFem script in 2D
No full textThe dandelion pappus opens and closes reversibly to tune seed dispersal according to environmental moisture levels.
In the Nature Communications paper "Madeleine Seale, Annamaria Kiss, Simone Bovio, Ignazio Maria Viola, Enrico Mastropaolo, Arezki Boudaoud, Naomi Nakayama, Dandelion pappus morphing is actuated by radially patterned material swelling, https://doi.org/10.1038/s41467-022-30245-3 the authors combined experiments with a computational model to show that pappus closure is coordinated by radially-patterned tissue swelling at the base of floral organs.
This repository contains the FreeFem script implementation of the computational model.
Source data for the same paper is in the following repository
Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition
No full textGreat emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance in interdisciplinary fields such as biotechnology, medicine, and advanced materials. Here, we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO2) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently, over several relevant interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption. In particular, we show that the very good control of nanoscale morphology is obtained by taking advantage of simple scaling laws governing the ballistic deposition regime of low-energy, mass-dispersed clusters with reduced surface mobility
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