Tesi di Dottorato
Permanent URI for this communityhttps://lisa.unical.it/handle/10955/10
Browse
58 results
Search Results
Item ADVANCED MODELING APPROACHES FOR THE FAILURE ANALYSIS OF HETEROGENEOUS MATERIALS AND STRUCTURES(Università della Calabria, 2024-07-30) Gaetano, Daniele; Greco, Fabrizio; Critelli, SalvatoreThe development of new engineered materials and the introduction of innovative design techniques have led researchers in the field of structural engineering to focus their attention on the mechanical behavior of these materials to develop optimal and innovative design procedures to improve the structural performance of new and existing buildings, especially concerning their seismic behavior. The most investigated aspects are, on the one hand, the mechanical characterization of complex microstructures, such as those of composite reinforced with fibers and/or particles, to be carried out taking into account the influence of the micro-constituents on the global properties, and, on the other hand, the study of the interactions between these materials and the structural elements to which these composites are applied for mechanical reinforcement, considering the damage and fracture phenomena that can potentially occur. From a mechanical point of view, both innovative materials (e.g. composite laminates) and conventional materials (e.g. concrete, reinforced concrete, and masonry) can be considered heterogeneous materials, as they are composed of a more or less complex microstructure, made up of different constituents, usually distinguishable at very small scale compared to the dimensions of the whole structure, known as microscopic scale [1]. Being formed by the combination of distinct phases, such materials often have different (even better) mechanical properties than those of the individual constituents, but at the same time are subject to failure phenomena including: • fiber/matrix debonding, for composites, or FRP/substrate debonding for FRP-strengthened structures; • delamination between the different constituents for layered composites; • matrix cracking; • damage and plasticity phenomena; • growth of voids in the matrix phase; •As a characteristic feature of materials with heterogeneous microstructure, the different failure mechanisms may interact with each other, especially if coupled with additional effects related to unilateral contact (with or without friction) between the surfaces of the cracks or due to the presence of imperfect interfaces between the different phases [2]. As a consequence, the analysis of these non-linear phenomena and the associated structural response, results in the solution of highly non-linear problems, which make the study of the behavior of heterogeneous materials extremely challenging, requiring highly specialized theoretical and numerical knowledge as well as accurate and computationally efficient tools. In recent decades, different theoretical and numerical models have been developed to study the collapse mechanisms in heterogeneous materials and their influence on the overall properties in terms of strength and stiffness. Among these, for example, multiscale approaches that make it possible to analyze the response by considering the interaction that occurs between the various phenomena at different involved scales, or methods that use damage and fracture mechanics to describe the behavior of heterogeneous solids subject to damage phenomena. Besides the study of these issues, research interest in recent years has been focusing on structural health monitoring and damage identification within existing structures; the aim is to reduce the risk of collapse mechanisms within the materials so that the structural integrity is no longer compromised and premature and catastrophic collapses of the structures are avoided. This thesis aims to develop a series of advanced numerical methods for the failure analysis of heterogeneous materials and structures, both at the meso- and micro-scale. All the developed models use a cohesive/volumetric finite element method, based on an inter-element fracture approach [3]. In particular, two models have been developed: • A first model combining the cohesive fracture approach with a hierarchical multiscale model used to study the collapse phenomena of materials at a microscopic scale; • A second model, based exclusively on the inter-element cohesive approach, to analyze the structural behavior of FRP-strengthened reinforced concrete elements subjected to cyclic loading conditions for structural health monitoring, as well as to investigate the failure mechanisms in masonry elements. The key aspect of this work is to illustrate the models developed, to show the different strategies and procedures required to adapt them to different scales, and to the different materials and structures in the engineering fields. Chapter 1 contains the introduction and a review of the technical literature, as well as the aims and objectives of the work. Chapter 2 presents the theoretical formulation of the proposed models, while Chapters 3 and 4 review the obtained numerical results. Finally, Chapter 5 outlines the conclusions and the future perspective of the present work. microscopic and macroscopic instabilities due to finite deformations.Item Late pleistocene coastal sea surface temperature and environmental reconstruction for a post global-warming climate modelling in the central mediterranean(Università della Calabria, 2024-07-30) Santagati, Pierluigi; Critelli, Salvatore; Perri, Edoardo; Bernaconi, aria PiaThe Last Interglacial (MIS 5) is a warm period within the Late Pleistocene. In particular, its first substage (MIS 5e) is the last warmer than today period before the present-day Interglacial, therefore it is considered a good analogue for assessing future climate responses to global warming. The present work focuses on two shallow marine deposits cropping out along the Ionian Sea coastline, central Mediterranean: 1) a MIS 5e fossiliferous calcarenite from Taranto (Apulia), and 2) MIS 5a/c bioconstructed deposits from Capo Colonna (Calabria). These deposits were studied for a paleoenvironmental characterization, which included the paleoecology of benthic associations, paleotemperature estimates and early diagenetic phenomena, with the aim of providing new data on the response of these systems to climatic variations. The MIS 5e calcarenite from Taranto, sampled in three related sites cropping out along the Mar Piccolo (MP) coastline (Masseria La Penna, Mass. S. Pietro, and Il Fronte), returned a rich molluscan fauna consisting of 120 extant species and 5174 individuals, including four of the tropical Senegalese Fauna, today absent in the Mediterranean. The molluscan assemblages were used for a refined quantitative palaeoenvironmental reconstruction; as a whole, the fauna represents an autochthonous-parautochthonous assemblage coming from a sandy-vegetated infralittoral bottom, locally accompanied by coarser and less finer sediment fractions, and characterized by slight lateral variability, shifting from more sheltered and exposed areas, and from finer and coarser bottoms, suggesting a heterogeneous and well-structured palaeoenvironment during MIS 5e. The same molluscan assemblage was used for a multi-proxy palaeoclimatic study. The biogeographic-climatic affinity of the assemblage shows, compared to today, a double percentage of warm affinity species, while the cold affinity species are similarly represented, indicating a warmer but not strictly tropical Sea Surface Temperature (SST). This is confirmed by the most recurring preferred SST ranges of the assemblage, indicating an average of 20 °C. The skeletal compositions of five well-preserved molluscan and coral specimens were analyzed for trace elements and stable isotopes for further mean SST estimations. From the comparison of the results of several equations available in literature, it appears that only some SST estimations are realistic, converging into similar values of, on average, 20.8 ± 0.9 °C. Considering all the used proxies, the MIS 5e SST difference compared to today falls in the range 1.2 - 2.0 °C for the Gulf of Taranto (GT) (being a more reasonable scenario) and 2.0 - 2.8 °C for the MP. This is not a firmly tropical-like SST setting as suggested by the sole Senegalese fauna, indicating at least 2.7 °C to 3.5 °C more than to today’s GT and MP, respectively. The approximations and assumptions made for obtaining SST values with any single proxy indicates the need of a multi-proxy approach to define the best SST estimation. Cemented samples of the same MIS 5e calcarenite were analyzed through optical and SEM analyses. Clasts mostly consist in medium to coarse sandy size skeletons and fragments of skeletons of a variegated biota together with mainly large mollusks shells that inhabited the sediment and a very minor amount of siliciclastic. Micritization variably affects most of the bioclasts while cements are constituted by a microcrystalline texture with various micro-morphologies and fabrics: not-isopachous aphanitic and filamentous rims, vacuolar peloidal meniscus, aphanitic micro-mounds, and aphanitic porosity-filling matrix. Cements are constituted by sub-micron sized anhedral to nanospheroidal crystals of low Mg calcite, mixed with a minor amount of irregular platy crystals of saponite. All fabrics of cement are rich of mineralized filamentous, tubular, and sub-spherical bacteria bodies that imply the presence of a microbial community forming an epilithic to endolithic biofilm that stabilized the incoherent sediment and mediated the early precipitation of cements. This process led to the synsedimentary hardening of some parts the mobile sandy substrate, allowing the settlement of sessile taxa - such as Spondylus gaederopus, oysters, serpulids and barnacles. The Last Interglacial (MIS 5) transgressive-regressive deposits of the Capo Colonna marine terrace provide a good fossil example of a Central Mediterranean infra/circa-littoral setting, characterized by both calcareous coralline algae-dominated low-relief bioherms and biostromes, analogous respectively to the present coralligenous and mäerl habitats. The skeletal primary framework of the bioherms consists of laminar to massive encrusting coralline red algae acting as main bioconstructors, with minor bryozoans, encrusting foraminifera and serpulids as secondary frame-builders. Whereas the autochthonous mäerl tabular beds are mainly composed of free-branched coralline red algae rudstones. A variable amount of sandy bioclastic sediment is laterally interbedded with the bioconstructions and tends to be entrapped in their cavities and pockets. All sedimentary sub-facies of the bioconstructions and associated sediment, are rich in autochthonous syn-sedimentary microbial-mediated micrite, forming aphanitic, peloidal, clotted peloidal, and filamentous fabrics. Microbial micrite can also trap and bind a variable amount of grains or being a secondary component of the sandy detrital sediment with micritic rims surrounding the clasts. All these early-lithified micrites show the typical nanostructure of the primary microbial-mediated carbonates, rather than a detrital mud particles accumulation, as they consist of nanospheres coalescing into subhedral microcrystals, replacing, and mineralizing both microbial cells (present with several morphological types) and extracellular substances. This in turn implies the widespread presence of benthic lithifying microbial biofilms that colonized both the cavities of the skeletal framework of the bioconstructions, and the intergranular space of the associated sediment. These microbial communities, thanks to the metabolic processes of the microorganisms that induced the carbonate precipitation, significantly contributed to the early cementation of all the studied deposits. In conclusion, the results of the work were used to infer possible effects of climate change in similar Mediterranean contexts. The diversity and temperature preferences of the MIS 5e molluscan assemblage from Taranto show no significant differences compared to modern analogous faunas from some Southern Italy sites reported in the literature, which could show a resilient response to an SST increase of +2 °C, already experienced during MIS 5e and expected in the next decades. This, however, does not consider the different causes, the current higher warming rates, as well as the human impact, which could affect faunas more than the temperature itself. Today, microbial induced micritic cementation processes, similar to those reported in the studied MIS 5 deposits, are observed in tropical/subtropical carbonate platform realms and have not been indicated for similar infra-circalittoral beds of the modern Mediterranean. Their occurrence in MIS 5 deposits confirms the warmer SST during MIS 5e and suggests a persistently warm SST at the end of MIS 5. However, as these cements have been associated with an estimated SST of just +2 °C compared to modern times, it is suggested that early cementation could become common in the Mediterranean mobile bottoms already in the near future as an effect of the global warming.Item Risks and impacts of mercury use in gold mining in Ecuador(Università della Calabria, 2024-04-30) Mestanza Ramón, Carlos; Critelli, Salvatore; Straface, Salvatore; D'orio, Giovanni; Montoya, Alex V. GavilanesItem Definition and application of methodological protocols for the conservation and protection of cultural heritage: case studies(Università della Calabria, 2024-04-15) Donato, Antonio; La Russa, Mauro; Costanzo, Antonio; Buongiorno, Maria F.; Critelli, SalvatoreItem Versatility of Deep Eutectic Solvents (DESs): Green Restoration and Eco-sustainable Organic Synthesis(Università della Calabria, 2024-08-06) Strangis, Romina; Mancuso, Raffaella; La Russa Mauro Francesco; Beneduci, Roberto; Figoli, Alberto; Critelli, SalvatoreDeep Eutectic Solvents (DESs) represent a class of unconventional solvents obtained from the mixture of two or more pure compounds, resulting in a liquid form at room temperature due to their lower melting point than those predicted for an ideal liquid mixture. They stand out from conventional solvents due to their environmental sustainability, biodegradability, and versatility, attracting attention in various fields. However, their potential application in cultural heritage restoration remains largely unexplored, given the limited number of scientific papers addressing the use of DESs in this field. This research project aims to prepare DESs and evaluate their efficacy as eco-friendly strategies for restoration practices. A first case study demonstrates the promising utility of DESs as green biocidal solvents for use in the removal of biofilms from artworks in the cultural heritage sector. A second case study highlights the ability of hydrophobic DESs, as cleaning agents, to remove aged non-polar coatings, addressing degradation products commonly encountered in restoration work on metal and stone assets. The search for new solvents, such as DESs, to replace harmful and unsafe conventional solvents used in the cultural heritage sector has shown promising results. Furthermore, due to their unique characteristics, DESs can be used as unconventional solvents in organic synthesis representing excellent substitutes for volatile organic solvents. The main advantages of their use as reaction solvents are increased reaction speed, increased reaction yield and selectivity, and the possibility of recycling the solvent/catalyst system. DESs prove to be efficient solvents in the synthesis of high-value-added organic compounds, facilitating processes such as the iodocyclization reaction and the Sonogashira and Suzuki coupling reactions. This approach underscores the versatility and potential of DESs in cultural heritage conservation and cleaning, and in synthetic chemistry, offering a viable alternative with wide applicability.Item Numerical modeling of fracture phenomena by means of moving mesh method(Università della Calabria, 2023-07-15) Ammendolea, Domenico; Critelli, Salvatore; Lonetto ,PaoloIn recent years, the impact of crack evolution on the bearing capac-ity of a structure has become one of the most important features in mod-ern design processes to choose the best structural intervention, which must be as “sustainable” as possible both in terms of the materials used and from an economic point of view. The important advances in computational fields have led to several numerical methods that can accurately reproduce crack propagation phenomena. Most of them have been developed in the framework of the Finite Element (FE) method because of its simplicity and flexibility in analyzing complex structures. Commonly, FE methods are classified into (i) smeared crack models and (ii) discrete crack approaches. Dis-crete crack approaches reproduce internal defects, including strain or discontinuity fields, into finite element formulations. In contrast, smeared crack models account for the presence of cracks at the consti-tutive level by using proper damage laws that degrade the mechanical properties of the material once crack conditions occur. Each method presents negative and positive features, thus denoting that it is some-what challenging to find the best one. Developing advanced approaches ensuring a suitable compromise between low computational costs and reliable predictions is attracting considerable attention from national and international research communities. The present thesis aims to develop a numerical model for reproduc-ing crack propagation mechanisms in different structural components under generalized loading conditions. The proposed methodology com-bines the Moving Mesh (MM) technique and the Interaction integral method (M-integral) in an FE framework. In particular, based on the Arbitrary Lagrangian-Eulerian (ALE) formulation, the MM approach is used for tracing the variation in the geometry of the computational do-main due to the crack advance. More precisely, the mesh node associ-ated with the crack tip is moved consistently with the conditions dic-tated by classic fracture criteria developed in the context of Fracture Mechanics. To ensure the consistency of the mesh point's motion, the proposed strategy uses mesh regularization techniques based on proper rezoning equations. This feature drastically reduces the overall amount of re-meshing events, which typically affect the computational effi-ciency of standard crack propagation procedures, thereby saving rele-vant computational resources meanwhile avoiding convergence issues. Useful solutions to overcome the major issues of traditional FEM pro-cedure for studying crack propagation mechanisms are much sought. Another key aspect of the present thesis is a novel strategy for ex-tracting fracture variables at the crack front, which are necessary for defining crack onset conditions, the direction of propagation, and the crack tip velocity. Specifically, the proposed model uses the M-integral method to extract Stress Intensity Factors (SIFs) at the crack front. In particular, in the framework of the MM strategy adopted, this work in-troduces the ALE formulation of the M-integral. Comparisons with predictions of other numerical methodologies, analytical formulations, and, especially, experimental results are devel-oped to check the reliability and efficacy of the proposed method. In this context, parametric analyses regarding mesh discretization and pa-rameters involved in the numerical model serve to assess the computa-tional efficiency and accuracy in predicting fracture variables and crack trajectories. The results show that the proposed approach is an efficient and robust and numerical tool for reproducing complex crack propaga-tion phenomena. The thesis is organized as follows: chapter 1 contains the introduc-tion, which reports a brief literature review on the fracture phenomena and modeling approaches, the aims and scope. Chapters 2 and 3 present the developed method in a static framework. In particular, chapter 2 depicts the theoretical formulation, the numerical implementation, and the computational procedure, while chapter 3 shows numerical results to assess the proposed strategy's reliability and efficacy. Chapter 4 gen-eralizes the proposed modeling approach to the context of dynamic Fracture Mechanics. Finally, chapter 5 outlines the conclusions and fu-ture perspectives of this work.Item Geologia ed evoluzione tettono-stratigrafica del acino di Cirò fra S. Morello (CS) e strongoli (KR): implicazioni paleogeografiche durante i Serravalliano-Tortoniano(Università della Calabria, 2023-06-28) Arcuri, Nicodemo; Critelli, Salvatore; Muto, FrancescoItem Criteri e metodi er la predisposizione di studi di pericolosità da alluvione a scala di bacino mediante l'uso di modelli numerici bidimensionali di tipo "RAIN ON GRID"(Università della Calabria, 2023-05-23) Lombardo, Margherita; Critelli, Salvatore; Macchione, Francesco; Fiorentino, Mauro; Russo, BeniaminoIn contesti come quello Calabrese, l’attuazione della Direttiva Europea sulle Alluvioni (Flood Directive, 2007/60/CE) ha subito ritardi, principalmente legati alla mancanza di cooperazione tra gli enti preposti e alla disuniformità delle informazioni territoriali. Questo ha fatto sì che le mappe della pericolosità e del rischio da alluvione, strumenti ai quali la Direttiva riconosce un ruolo fondamentale per la pianificazione della gestione del rischio, si presentino come poligoni frammentati e mosaici di studi ottenuti mediante modelli a diversa complessità. La ricerca in questo settore sta spingendo verso l’introduzione e l’impiego di criteri più rigorosi e metodi fisicamente basati per la valutazione della pericolosità idraulica finalizzata alla pianificazione e alla gestione del rischio. Le considerazioni sulle potenzialità e i vantaggi legati all’applicazione dei modelli 2D fisicamente basati a supporto delle analisi di pericolosità e di rischio da alluvione a scala di bacino idrografico sono suffragate da numerosi studi disponibili in letteratura. A queste considerazioni sono legate le motivazioni del presente lavoro di tesi, che, partendo da una overview sui recenti avanzamenti e sulle problematiche ancora aperte nel campo degli studi sulle inondazioni, ha inteso approfondire alcuni degli aspetti di maggiore interesse scientifico al fine di suggerire dei criteri e dei metodi innovativi e di facile implementazione in modelli bidimensionali a supporto degli studi di pericolosità a scala di bacino. L’attenzione è stata rivolta, più nello specifico, verso gli items elencati di seguito: - Metodi innovativi per una preliminare individuazione delle aree potenzialmente inondabili; - Criteri per la definizione degli scenari pluviometrici di progetto; - Inclusione nella modellazione degli effetti idraulici indotti dall’interazione della piena con opere di attraversamento; - Criteri idrodinamici per la valutazione della vulnerabilità dei beni esposti.Riguardo gli aspetti connessi ad una preliminare individuazione delle aree potenzialmente inondabili è stato messo a punto un framework metodologico basato sull’uso di un modello idrodinamico bidimensionale a partire da un input di pioggia distribuito congiuntamente all’impiego dell’informazione topografica di tipo LiDAR (Ligth Detection And Ranging). Attenzione particolare è riservata al set-up del dominio di calcolo, il quale prevede l’elaborazione di una griglia computazionale localmente rifinita, che consente di ridurre gli oneri computazionali. Ciò si rivela utile in particolare ove sia prevista l’esecuzione di simulazioni multi-scenario per uno stesso caso studio. Il framework metodologico è stato applicato all’intera fascia costiera comprendente i bacini del torrente Soverato e del fiume Ancinale. La validazione dei risultati è stata eseguita sulla base delle informazioni storiche reperibili da archivi regionali e rilievi post-evento. La delimitazione delle aree inondabili, ottenuta per via idrodinamica, è stata inoltre messa a paragone con quella ricavata mediante un metodo morfologico-idraulico su cui attualmente sono basate le misure di salvaguardia regionali. Riguardo la componente idrologica, si propone, sulla base dei principali studi regionali disponibili, un criterio per la definizione di un input idrologico distribuito nello spazio e nel tempo, adatto alle peculiarità climatiche e si analizzano le implicazioni di tale scelta progettuale sull’estensione delle aree inondabili riconducibili agli scenari associati a probabilità di accadimento bassa, media ed elevata, come suggerito dalla Direttiva Alluvioni. Lo stesso caso studio è poi stato oggetto di un’analisi finalizzata alla ricostruzione numerica dell’evento di Soverato del 2000. E’ stato inoltre messo a punto un flow-chart a supporto della modellazione a scopo ricostruttivo di eventi alluvionali passati e di analisi di tipo what if per valutare la possibilità di includere nel modello i fenomeni di ostruzione di ponti e attraversamenti. Il flow-chart è basato sulla valutazione di fattori predisponenti diretti o indiretti. Per la trattazione equivalente degli effetti idraulici indotti a scala territoriale da fenomeni di occlusione e repentina disostruzione di ponti è stato implementato un metodo basato sull’uso dinamico di una scabrezza equivalente, che consente di riprodurre sia l’effetto di rigurgito imputabile alla presenza dell’ostruzione, sia l’onda conseguente alla rapida disostruzione. Il metodo è stato validato, ammettendo l’analogia con il caso di dam-break con deflusso di base. L’applicazione del metodo ha consentito di ottenere una affidabile ricostruzione delle dinamiche di un evento anche in termini di evoluzione della piena. L’applicazione del metodo messo a punto ha anche permesso di evidenziare come l’inclusione di “eventi associati” nella modellazione possa permettere di apprezzare l’effetto di aggravio in termini di vulnerabilità degli elementi esposti. Considerazioni di questo tipo sono, in prospettiva di una stima dei tempi di intervento, più interessanti rispetto alle valutazioni inerenti i valori massimi registrati durante tutto l’evento stesso. Infine, proprio con riferimento ai criteri di vulnerabilità, nell’ultima parte della tesi si è voluto dare spazio ad alcune valutazioni inerenti i criteri con cui eseguire le analisi di rischio in presenza di beni culturali esposti, spesso trascurati dalla letteratura scientifica, che si concentra sulla vulnerabilità delle persone. Per questo tipo di beni la modellistica idrodinamica basata sulle equazioni complete del moto vario è capace di supportare analisi per la definizione delle migliori strategie per la conservazione dei beni esposti a rischio. In presenza di beni esposti all’azione diretta delle precipitazioni, i criteri di vulnerabilità dovrebbero essere basati sulla valutazione di grandezze derivate come gli sforzi tangenziali. L’applicazione al caso della Villa Romana di Els Munts ha messo in evidenza come per questo tipo di beni, gli scenari di progetto dovrebbero includere anche scenari di pioggia frequente in quanto capaci anch’essi di provocare gravi perdite al bene esposto.Item Approccio integrato alla gestione strategica delle reti idriche per l’ottimizzazione delle performance di sistema(Università della Calabria, 2023-05-23) Femiano, Rossella; Critelli, Salvatore; Belgiorno, VincenzoStrategic integrated approach for hydraulic network management and optimization of performance system Water plays a significant role in the twin transition towards a greener and digital European society. Water scarcity is an increasingly frequent and worrying phenomenon that affects at least 11% of the European population and 17% of EU territory. It is estimated that some 20-40% of Europe’s available water is being wasted (leakages in the supply system, no water saving technologies installed, too much unnecessary irrigation, dripping taps etc.). The main goal of this PhD thesis is to develop an integrated methodology improving the efficiency of the drinking water service through the reduction of network losses and the decrease of maintenance interventions. The proposed model, with a strong application approach, considers specifically the infrastructural assets and the efficiency criteria indicated by ARERA (i.e. the Italian Organism of Regulation of the Water Supply), in coherence with the various hierarchical plans such as the “Management Plan of Water” introduced by the European Directive 2000/60/CE and allows a quick follow up of system to identify the best solution for maximizing performance indexes. The methodological path, structured in several distinct and consequential phases, foresees the actual investigation of the physical and operating conditions of the hydraulic assets: an in-depth knowledge of the system is essential to analyse the service and improve its quality, to make more informed decisions in real-time and to direct investments towards concrete and effective priorities. This approach, thanks to the use of decision-making process with predictive and prescriptive algorithms, is useful for accurately planning interventions even in the medium-term long term and to optimize the maintenance activity based on the reconnaissance analysis of the actual state of the networks rather than the theoretical useful life. The tool built in this research activity allows the achievement of the general objectives of the European legislation on water, of the national regulation of the sector and - indirectly - of adaptation to climate change: it is based on international asset management best practices so it helps to identify specific processes for effective management of water networks in terms of intervention planning, monitoring and system control. Below are summarized in simple "operative guidelines", the thesis outcomes useful for evaluating the water system and the possible choices to adopt to improve its management and operational performance1. Overview of the reference regulatory framework with the combined reading of various regulatory acts of both a sectoral (concerning water services) and general nature, with particular reference to the regulation on local public services, public procurement, corporate shareholdings of public administrations; 2. Investigation on the regulatory framework of the IWS that takes into account the stratification and complexity of multilevel governance; 3. Insights on the construction, technological and maintenance aspects of the main assets of an aqueduct system;: 4. Adequate monitoring of functional parameters and careful analysis of network behaviour through: 4.1 Construction of multi-parametric indices starting from the aggregation of simple data processed in statistically significant period and compared to a homogeneous reference area (Macro - ARERA indicators (M1 and M2) - KPIs (Key Performance Indicators)); .2 Hydraulic modelling and definition of significant parameters for the implementation of technical and management choices to optimize the service: Districtualisation; Positioning of pressure reducing valves; Planning of reduction activities and active control of losses; Identification of network sections to be rehabilitated or replaced ollowing these four steps, immediately applicable, it is possible to increase the performances, in terms of efficiency and economy, of water service both in the "ordinary management" and in more wide-ranging strategic projects. The research activity carried out allowed to build a simple, flexible but at the same time objective and scalable tool for the evaluation and control of network anomalies as well as having identified the significant parameters that affect the main issues of the service (network losses and interruptions in supply water).Item Gas permeation through zeolite membranes: modelling and experimental analysis(Università della Calabria, 2020-03-27) Zito, Pasquale Francesco; Critelli, Salvatore; Barbieri, Giuseppe; Brunetti, AdeleLa separazione gassosa è uno stadio fondamentale in numerosi processi industriali, in quanto consente la purificazione e il recupero di componenti ad alto valore (come H2) e, allo stesso tempo, la riduzione delle emissioni di vari inquinanti atmosferici, quali, ad esempio, la CO2. Tradizionalmente, essa viene condotta tramite assorbimento e distillazione criogenica, tecniche ben note e consolidate. Tuttavia, entrambe risultano ad alto impatto ambientale, in quanto necessitano dell’impiego di un solvente (assorbimento) o di condizioni operative drastiche (distillazione criogenica). Pertanto, nell’ottica di uno sviluppo più sostenibile, che vada nella direzione della green chemistry (ovvero progettare prodotti e processi che evitino o riducano l’utilizzo e la produzione di sostanze dannose per l’ambiente) e segua i principi della Process Intensification in termini di minori consumi energetici e volumi di impianto, le membrane rappresentano una valida alternativa ai processi tradizionali. In questo lavoro di dottorato, sono state studiate le potenzialità delle membrane zeolitiche nel separare correnti gassose contenenti CO2, gas permanenti (N2, H2, CH4) e vapore, mediante un’indagine modellistica e sperimentale. Il trasporto di materia attraverso i pori zeolitici è stato descritto sviluppando un modello ad-hoc che considerasse la competizione tra surface diffusion e gas translation diffusion. Tale modello, validato per miscele secche ed umide su membrane di vario tipo (SAPO-34, DDR, NaY, 4A), è stato utilizzato per prevedere la separazione multicomponente al variare delle condizioni operative. La permeazione in miscela è risultata molto diversa rispetto quella in gas singolo. In particolare, la CO2 ha mostrato un incremento di permeanza in presenza di alcune specie, come l’idrogeno. In questo caso, infatti, essa usufruisce dell’effetto positivo esercitato dall’idrogeno sulla diffusività binaria, che regola la surface diffusion in miscela. Al contrario, le specie più debolmente adsorbite (H2, N2, CH4) hanno subìto una netta riduzione di flussi e permeanze in miscela, a causa dell’effetto di hindering che la CO2 adsorbita esercita sulla loro diffusione. Ciò si è tradotto in selettività di miscela (per esempio, 22 nel caso di CO2/N2 in SAPO-34) significativamente migliori rispetto a quelle valutate con i gas singoli. Si è dimostrato, quindi, come sia importante avere un’analisi del trasporto in miscela, nell’ottica di una valutazione realistica delle proprietà separative delle membrane, fondamentale in fase di progettazione di unità di separazione. Le previsioni modellistiche sono state confermate e corroborate da prove sperimentali per correnti a diversa composizione, effettuate su una membrana DDR fornita dal Professore Xuehong Gu, della Nanjing Tech University. Le misure sperimentali hanno confermato elevate selettività in miscela (per esempio, 106 e 17 nel caso di CO2/CH4 e CO2/H2), diverse da quelle calcolate sulla base di misure a gas singolo. Questi valori di selettività rendono le zeoliti particolarmente adatte per recuperare la CO2 da correnti di miscele multicomponente. Per quanto riguarda le miscele umide, si è dimostrato come l’acqua in fase vapore blocchi completamente la diffusione superficiale dei gas permanenti (H2, CO e CH4), i quali permeano solo per gas translation diffusion. Pertanto, la competizione tra surface diffusion e gas translation diffusion, espressa nel modello proposto, ha consentito di descrivere accuratamente la permeazione in membrane zeolitiche e di prevedere così il comportamento in ampi intervalli di condizioni operative. L’analisi modellistica ha confermato come l’alta affinità di queste membrane verso CO2 e H2O le renda particolarmente selettive e, dunque, indicate per ottenere correnti concentrate di permeato e retentato da poter riutilizzare e valorizzare.