Durabilit\ue0 del legno lamellare rinforzato: un prodotto innovativo

La ricerca sviluppata nell\u2019ultimo decennio in edilizia si \ue8 orientata sempre pi\uf9 verso quei materiali, cosiddetti ecocompatibili o ecosostenibili, tali da dissipare il meno possibile le risorse naturali. In questo senso il legno, ed in particolare quello lamellare, \ue8 divenuto una valida alternativa alle tecnologie pi\uf9 usuali e tradizionali del cemento armato e del ferro, anche perch\ue9 rappresenta una delle poche materie prime rinnovabili. Il legno lamellare \ue8 un prodotto evoluto, un prodotto industriale che supera i difetti propri del legno massello con caratteristiche di resistenza meccanica e di durabilit\ue0 superiori, cos\uec da poter ottenere qualunque forma e dimensione. Presenta per\uf2 una rigidezza limitata rispetto ad altre tecnologie, aspetto quest\u2019ultimo, che ha determinato un vasto campo di ricerca basato sulla possibilit\ue0 di inserire elementi irrigidenti all\u2019interno della sezione resistente. La memoria presenta i risultati raggiunti nell\u2019ambito di un progetto di innovazione PIA che ha avuto l\u2019obbiettivo di sperimentare un prodotto innovativo che possa avere una maggiore rigidezza, e quindi maggiori prestazioni a parit\ue0 di costi. L\u2019impiego di materiali originali ha richiesto la verifica delle prestazioni attraverso test ciclici di prove integrate di resistenza meccanica e di invecchiamento accelerato che sono state svolte, rispettivamente, dal Dipartimento di Ingegneria Strutturale e Geotecnica e dal Dipartimento di Progetto e Costruzione Edilizia entrambi dell\u2019Universit\ue0 di Palermo. Nel seguito si illustrano le prove di invecchiamento artificiale eseguite per verificare la durabilit\ue0 dei prototipi innovativi da sperimentare

Evaluation of innovative thermal insulation systems for a sustainable envelope

La memoria presenta i risultati ottenuti su sistemi di isolamento termico per l\u2019involucro edilizio. Si presentano i risultati ottenuti tramite simulazioni informatiche che hanno consentito di verificare e ottimizzare la trasmissione del calore attraverso un sistema sottovuoto in vetro per le facciate trasparenti. Inoltre la possibilit\ue0 offerta dal riciclo del materiale di scarto della potatura dell\u2019Opunthia Ficus Indica (fichi d\u2019india) che,opportunamente trattato ha permesso di ottenere un materiale isolante (Brevetto n. 1402131), in forma di pannello o in grani sfusi, (valori di coibenza termica 0.071\uad0.057 W/mK).The paper presents the results of the research on thermal insulation systems for the building casing. We present the results of computer simulations that have enabled us to verify and optimize the transmission of heat through several innovative insulation systems, such as vacuum solutions for transparent fa\ue7ades, or the possibilities offered by the recycling of waste material of Opunthia Ficus Indica (prickly pear) pruning, which, properly treated, allowed to obtain an insulating material (Patent n. 1402131), in the form of panels or bulk grains (thermal coefficient values 0.0710.057 W/mK)

Symmetries of stochastic differential equations using Girsanov transformations

Aiming at enlarging the class of symmetries of an SDE, we introduce a family of stochastic transformations able to change also the underlying probability measure exploiting Girsanov Theorem and we provide new determining equations for the infinitesimal symmetries of the SDE. The well-defined subset of the previous class of measure transformations given by Doob transformations allows us to recover all the Lie point symmetries of the Kolmogorov equation associated with the SDE. This gives the first stochastic interpretation of all the deterministic symmetries of the Kolmogorov equation. The general theory is applied to some relevant stochastic models

Weak symmetries of stochastic differential equations driven by semimartingales with jumps

Stochastic symmetries and related invariance properties of \ufb01nite dimensional SDEs driven by general c`adl`ag semimartingales taking values in Lie groups are de\ufb01ned and investigated. The considered set of SDEs, \ufb01rst introduced by S. Cohen, includes a\ufb03ne and Marcus type SDEs as well as smooth SDEs driven by L\ub4evy processes and iterated random maps. A natural extension to this general setting of reduction and reconstruction theory for symmetric SDEs is provided. Our theorems imply as special cases non trivial invariance results concerning a class of a\ufb03ne iterated random maps as well as (weak) symmetries for numerical schemes (of Euler and Milstein type) for Brownian motion driven SDEs

Gnss and photogrammetric uav derived data for coastal monitoring: A case of study in emilia-romagna, italy

GNSS real-time techniques and UAV photogrammetry can be alternative methods for the monitoring of sand beaches. This activity is particularly important in environments such as the Emilia-Romagna coastline. In this paper, two couples of surveys (year 2019 and 2020) performed using GNSS or a low-cost UAV equipment over a common area were compared in order to analyse: point-wise height differences, profile shapes along defined sections, and volumes variations over time. Both surveys were aligned to the same reference benchmark through GNSS measurements. The highest discrepancies between the two surveying methods (tens of cm) were found in vegetated areas and along the shoreline, otherwise, the height differences are mainly within the 10 cm level. In terms of volumes, excluding the most critical areas, differences close to zero can be found. Obtained results show that GNSS and UAV photogrammetry provides similar results, at least for quite flat terrains and when decimetre-level accuracy is required

Automotive leathers – evaluating the performance limits (part II)

Content: Consumers perceive leather as a durable and natural product. To support this positive image, car manufacturers have set demanding performance profiles addressing wear, emissions and sustainable manufacture. Poor performance of auto leather becomes visible as the polymeric finishing coat wears off or cracks over time. Therefore ageing property is seen as a representative key performance parameter and is determined by checking how flexible and strong a polymer coating remains after leather has been exposed to light, heat and humidity for a given time. Ageing of leather is complex to determine and depends on various parameters and requires a full system approach . In a first step different type of crusts (wet-blue, wet-white) were prepared and finished with a standard polyurethane coating. It turned out that the selection of the right fat liquors and tanning agents as well as the presence of vegetable tannins play an important role. On top of this the effective use of proper protective chemicals like anti-oxidants is needed. In a second approach the polymer coating itself was studied and optimized with regard to aged flexing and abrasion. Parameters like polymer type, crosslinking, application technology, coating thickness and impact of additives were investigated and tested when applied on the best crust leathers selected from part 1 of this work. Results show that not only is the right selection of polymers critical but also so is the way the coat is being applied . Furthermore coating thickness greatly defines wear (abrasion), lightfastness and ageing properties. Additives like dulling agents, levelers, feel agents, waxes ,fillers although needed can weaken the integrity of the polymer matrix and consequently reduce physical and chemical fastness properties. This may also apply to a certain extent to protective additives such as anti-oxidants and UV stabilizers, but when used properly their advantages outweigh the potential disadvantages. As to application, special emphasis is given to transfer coating technology which can provide advantages in application and quality consistency but also with regards to fastness properties such as wear and ageing. Take-Away: - crust leather has a critical impact on performance of finishing coat of automotive leathers and requires careful selction of products and use of protective chemical - polymer selection and use of protective chemical play an important role for achieving good aged flexing performance - type of application of finishing coat on auto leather further determines the performance of coatin

Modulation of opportunistic species Corynebacterium diphtheriae, Haemophilus parainfluenzae, Moraxella catarrhalis, Prevotella denticola, Prevotella melaninogenica, Rothia dentocariosa, Staphylococcus aureus and Streptococcus pseudopneumoniae by intranasal administration of Streptococcus salivarius 24SMBc and Streptococcus oralis 89a combination in healthy subjects

\u2013 OBJECTIVE: Probiotics S. salivarius 24SMBc and S. oralis 89a comprised in the nasal spray Rinogermina are known to exert inhibition of harmful pathogens and ameliorate the outcome of patients with chronic upper airways infections. In this study, for the first time, the effect of this formulation on the modulation of the microflora of healthy subjects was evaluated, with particular interest on pathobionts and pathogens present. PATIENTS AND METHODS: Metagenomic identification and quantification of bacterial abundances in healthy subjects were carried out by means of Ion Torrent Personal Machine. In particular, nasal swabs were sampled one, two and four weeks after seven days of treatment with Rinogermina. RESULTS: The modulation of the abundance of pathobionts and pathogenic species (i.e., Corynebacterium diphtheriae, Haemophilus parainfluenzae, Moraxella catarrhalis, Prevotella denticola, Prevotella melaninogenica, Rothia dentocariosa, Staphylococcus aureus and Streptococcus pseudopneumoniae) was characterized and a significant temporary decrease in their presence was identified. CONCLUSIONS: The beneficial effects of S. salivarius 24SMBc and S. oralis 89a nasal intake was assessed but seemed to be restricted in specific temporal windows. Thus it would be interesting to evaluate also this positive impact of longer administration of this probiotic formulation

Multitrace deformations, Gamow states, and Stability of AdS/CFT

We analyze the effect of multitrace deformations in conformal field theories at leading order in a large N approximation. These theories admit a description in terms of a weakly coupled gravity dual. We show how the deformations can be mapped into boundary terms of the gravity theory and how to reproduce the RG equations found in field theory. In the case of doubletrace deformations, and for bulk scalars with masses in the range $-d^2/4<m^2<-d^2/4+1$, the deformed theory flows between two fixed points of the renormalization group, manifesting a resonant behavior at the scale characterizing the transition between the two CFT's. On the gravity side the resonance is mapped into an IR non-normalizable mode (Gamow state) whose overlap with the UV region increases as the dual operator approaches the free field limit. We argue that this resonant behavior is a generic property of large N theories in the conformal window, and associate it to a remnant of the Nambu-Goldstone mode of dilatation invariance. We emphasize the role of nonminimal couplings to gravity and establish a stability theorem for scalar/gravity systems with AdS boundary conditions in the presence of arbitrary boundary potentials and nonminimal coupling.Comment: 14 pages, references added, introduction change

Dynamical charge density fluctuations pervading the phase diagram of a Cu-based high-Tc superconductor

Charge density waves are a common occurrence in all families of high critical temperature superconducting cuprates. Although consistently observed in the underdoped region of the phase diagram and at relatively low temperatures, it is still unclear to what extent they influence the unusual properties of these systems. Using resonant x-ray scattering we carefully determined the temperature dependence of charge density modulations in (Y,Nd)Ba$_2$Cu$_3$O$_{7-{\delta}}$ for three doping levels. We discovered short-range dynamical charge density fluctuations besides the previously known quasi-critical charge density waves. They persist up to well above the pseudogap temperature T*, are characterized by energies of few meV and pervade a large area of the phase diagram, so that they can play a key role in shaping the peculiar normal-state properties of cuprates.Comment: 34 pages, 4 figures, 11 supplementary figure

A note on symmetries of diffusions within a martingale problem approach

A geometric reformulation of the martingale problem associated with a set of diffusion processes is proposed. This formulation, based on second-order geometry and It\uf4 integration on manifolds, allows us to give a natural and effective definition of Lie symmetries for diffusion processes