Fire Spalling Prevention via Polypropylene Fibres: A Meso-and Macroscale Approach

A deep understanding of concrete at the mesoscale level is essential for a better comprehension of several concrete phenomena, such as creep, damage, and spalling. The latter one specifically corresponds to the separation of pieces of concrete from the surface of a structural element when it is exposed to high and rapidly rising temperatures; for this phenomenon a mesoscopic approach is fundamental since aggregates performance and their thermal properties play a crucial role. To reduce the risk of spalling of a concrete material under fire condition, the inclusion of a low dosage of polypropylene fibres in the mix design of concrete is largely recognized. PP fibres in fact evaporate above certain temperatures, thus increasing the porosity and reducing the internal pressure in the material by an increase of the voids connectivity in the cement paste. In this work, the contribution of polypropylene fibres on concrete behaviour, if subjected to elevated thermal ranges, has been numerically investigated thanks to a coupled hygrothermomechanical finite element formulation. Numerical analyses at the macro- and mesoscale levels have been performed

Development of a new GIS-based method to detect high natural value farmlands. A case study in central Italy

An original method for the identification of High Natural Value farmlands is presented. Gathering information about land use (CORINE Land Cover), geomorphology (elevation and Terrain Ruggedness Index) and remote sensing data in a GIS environment we were able to develop a new detection process; its application to a wide sector of central Italy, in areas characterized by high biodiversity and relevant agronomic and cultural value, is presented. Thus, a new tool for diminishing sampling efforts and economic and time wastes in territorial studies is provided

The Haldane model and its localization dichotomy

Gapped periodic quantum systems exhibit an interesting Localization Dichotomy, which emerges when one looks at the localization of the optimally localized Wannier functions associated to the Bloch bands below the gap. As recently proved, either these Wannier functions are exponentially localized, as it happens whenever the Hamiltonian operator is time-reversal symmetric, or they are delocalized in the sense that the expectation value of |x| 2 diverges. Intermediate regimes are forbidden. Following the lesson of our Maestro, to whom this contribution is gratefully dedicated, we find useful to explain this subtle mathematical phenomenon in the simplest possible model, namely the discrete model proposed by Haldane [10]. We include a pedagogical introduction to the model and we explain its Localization Dichotomy by explicit analytical arguments. We then introduce the reader to the more general, model-independent version of the dichotomy proved in [19]

Paradigmi relazionali nello spazio urbano: il caso-studio del centro storico di Palermo

In questo scritto analizzeremo le modalità attraverso le quali vengono sovvertite, con piccole azioni dei cittadini, le regole che disciplinano gli spazi urbani. Partendo dal caso studio del centro storico di Palermo illustreremo come la “conquista” anche temporanea, di strade e piazze possa permettere una rivitalizzazione ed una rivalutazione dei luoghi. Il nostro interesse è rivolto a comprendere come si siano sviluppati processi di ri-conquista dello spazio urbano, che hanno permesso di “addomesticare” alcuni spazi della città, modificando usi e configurazioni comuni, che estrapolati dal contesto abituale sono stati inseriti in nuove relazioni. La scelta di prendere Palermo come caso studio deriva da alcune caratteristiche di questa città: la prima caratteristica può essere individuata nelle sue radici storico-culturali che in qualche modo favoriscono l’insediamento di nuove comunità; l’altra caratteristica è che le forme di scambio con abitanti di diverse culture avvengono, non in periferia, ma in centro. Questo rende la città siciliana un caso non unico ma atipico nel panorama europeo, dove si tende ad avere una spinta centrifuga e quindi una emarginazione delle popolazioni non locali e dei ceti meno abbienti. Da questo punto di vista il centro di Palermo può essere considerato come una sorta di spugna, che riesce non solo ad assorbire nuove comunità ma anche ad attrarre esponenti del ceto sociale medio. A differenza di altre città europee, dove si sono innescati processi di gentrification grazie agli interventi strutturali promossi dalla pubblica amministrazione, a Palermo il processo di riqualificazione è dovuto a piccole azioni promosse dai residenti. L’inversione della tendenza degenerativa che era in atto e l’inversione dell’andamento dei valori immobiliari non è dovuta quindi ad una politica integrata, quanto alla libera iniziativa delle fasce sociali più deboli.In this script we’ll describe the everyday,little actions of the citizens that break the rules of the urban areas’ organization. Starting from the Old Town of Palermo, that we used as the example in our analysis, we’ll show how the “conquest”, even just temporary, of streets and squares could achieve a revitalization and a revaluation of quarters. Our focus is on understanding how revitalization/ re-conquest of urban areas has taken place. By altering people preconcieved ideas of areas of the city, this process achived the “domestication” of some areas that, out of their usual context, are inserted in new relations. Our choice to take Palermo as example derives from some typical characteristics of this city: the first one is due to its historical-cultural origins which, in some way, favor the settlement of new comunities; the second is that the way of live among population of different cultures develops in the centre of the city, not in the suburbs. These features make Palermo not unique, but atipical compared to the rest of Europe where immigrants and lower-class people, are generally forced to the external areas of towns. From this point of view we can imagine Palermo’s Old town as a sponge which is able not just to absorb new comunities, but also to attract people from the middle classes. In European cities gentrification processes are started thanks to projects realized by the Public Administrations, On the contrary in Palermo this process generates from actions of the inhabitants themselves. The change of degenerative trend and the increasing value in the Real Estate Market is therefore not caused by a political action, but thanks to the initiative of the lower class.Peer Reviewe

Localization implies Chern triviality in non-periodic insulators

We investigate the relation between the localization and the topological properties of two-dimensional gapped quantum systems of independent electrons in a disordered background, including magnetic fields, as in the case of Chern insulators and Quantum Hall systems. We prove that the existence of a well-localized generalized Wannier basis for the Fermi projection implies the vanishing of the Chern marker, which is a natural generalization of the Chern number to non-periodic insulators, and coincides with the Hall conductivity in the linear response regime. Moreover, we state a localization dichotomy conjecture for general non-periodic gapped quantum systems.Comment: 34 pages, no figure

Piloting a meta-database of agroecological transitions: an example from sustainable cereal food systems

Despite the fact that policy makers and governments are promoting the development of diverse agro-bio food systems to push and promote sustainability, they are challenging to implement because of a series of obstacles that hinder a successful transition from a conventional to an agro-ecological model of agriculture. Produce is extremely heterogeneous and agricultural technology is often not standard, rather alternative, and knowledge is contextual, tacit and place-specific. However, information about the characteristics of these systems is still sparse and difficult to analyse because of the complexity and multidimensionality. As a result, the aim of this paper is to review the existing literature in order to identify a coding system that allows for the creation of a meta-database of case studies on agroecological transitions. This coding system will be piloted in six case studies dealing with agrobiodiversity along cereal food systems producing grains, bread and pasta in France, Italy and the UK. In this analysis, we found that both the transition towards sustainable agriculture and the reduction of transaction costs require social innovation, which benefits from strong social capital. In the conclusions, we discuss the efficacy of the proposed coding scheme and its ability to capture in-depth information contained in similar case studies

Using an adaptive neuro-fuzzy inference system for the classification of hypertension

In this work, neuro-fuzzy systems are compared to standard machine learning algorithms to predict the hypertension risk level. Hypertension is a cardiovascular disease, which should be continuously monitored to avoid the worsening of its symptoms. Automatic techniques are useful to support the clinicians in this task, however, most of the machine learning techniques behave like black boxes, thus they are not able to explain how their results have been obtained. In the medical domain, this is a critical factor, and explainability is demanded. Neuro-fuzzy systems, that combine Neural Networks (NNs) and Fuzzy Inference Systems (FISs), are used to obtain explainable results. Moreover, to enhance the explanation, a feature selection method has been used to reduce the number of relevant features and thus the overall number of fuzzy rules. Qualitative analyses have shown comparable results between the machine learning methods and the neuro-fuzzy systems. However, the neuro-fuzzy systems are able to explain the hypertension risk level with only nine fuzzy rules, which are easy to interpret since they use linguistic terms

Spin Conductance and Spin Conductivity in Topological Insulators: Analysis of Kubo-like terms

We investigate spin transport in 2-dimensional insulators, with the long-term goal of establishing whether any of the transport coefficients corresponds to the Fu-Kane-Mele index which characterizes 2d time-reversal-symmetric topological insulators. Inspired by the Kubo theory of charge transport, and by using a proper definition of the spin current operator, we define the Kubo-like spin conductance $G_K^{s_z}$ and spin conductivity $\sigma_K^{s_z}$. We prove that for any gapped, periodic, near-sighted discrete Hamiltonian, the above quantities are mathematically well-defined and the equality $G_K^{s_z} = \sigma_K^{s_z}$ holds true. Moreover, we argue that the physically relevant condition to obtain the equality above is the vanishing of the mesoscopic average of the spin-torque response, which holds true under our hypotheses on the Hamiltonian operator. This vanishing condition might be relevant in view of further extensions of the result, e.g. to ergodic random discrete Hamiltonians or to Schr\"odinger operators on the continuum. A central role in the proof is played by the trace per unit volume and by two generalizations of the trace, the principal value trace and it directional version.Comment: 35 pages, 2 figure