Compressive and shear behaviour of masonry panels: experimentation and numerical analysis

The compressive and shear behavior of masonry is here studied both experimental- ly and numerically. An experimental campaign has been carried out on 9 square-shaped one leaf masonry panels, reproducing historical masonry. Tests have been done for evaluating the elastic and shear moduli in both plane directions, with 6 panels rotated by 90 degrees, lead- ing to vertically aligned bed joints, and 3 panels maintained with horizontal bed joints. Com- pressive tests were executed on 6 masonry panels, 3 of them rotated by 90 degrees. Initial shear strength and shear modulus parallel to bed joints are evaluated through shear tests on 9 masonry triplets. Shear tests are performed on 3 rotated panels, applying an horizontal dis- tributed load, without vertical compression. Attention is paid to the service load state: only the initial phase of the tests is studied. Numerical models are proposed for representing actu- al masonry behavior, both discrete [1] and continuous [2,3], standard and micropolar, ob- tained by homogenization procedures [4]. Several numerical analyses are performed for simulating the experimental tests on masonry triplets and panels. The mechanical elastic pa- rameters of both discrete and continuous models are calibrated starting from laboratory data of masonry constituents and then by fitting the results of the initial phases of the experimental tests on masonry specimens

Spatial Mismatch and Mobility Involvements: a Common Approach for the Urban Sprawl Parma-Bologna

An economic growth which is wide-area scattered is one of the most important indicator of social well-being and is such a strong factor that can induce long-range demographic dynamics. Incoming migration fluxes are scattered across the national territory following patterns that appear mostly relational rather than economically driven. The resulting effect can be the well-known problem of Spatial Mismatch, SM. The institutionalist approaches permits to use different scaled units of analysis, with different levels of integration but coexistent under the very same historical-social pattern-determining context. This work will try to explain the relationship between SM and the more general Transaction Costs. With this hypothesis it will be possible to read from a (neo)institutionalist perspective the whole, empirical and theoretical, body of Spatial Mismatch. Trough the introduction of the temporal perspective the present work propose a theoretical framework that shows that the increasing degree of spatial mismatch discussed in the case study has appeared only when the redistributive action so important for the initial development, and operated mainly trough the increasing of social capital stock, has declined. Therefore upgrade policies of public goods are considered constantly needed in order to promote growth itself

Damage-imperfection indicators for the assessment of multi-leaf masonry walls under different conditions

The complexity of multi-leaf masonry walls suggests further researches on the dy- namic behaviour mainly characterized by incoherent response between the different layers. The intrinsic discontinuity and the manufacturing imperfections are amplified by the incre- mental damage that triggers different failure mechanisms that affect the dynamic parameters, such as modal shapes, frequencies and damping ratios. The dynamic identification with out- put only methodology has been proposed in this work on different multi-leaf masonry walls subjected to uniaxial compressive load. The responses of full infill, damaged infill and strengthened infill masonry panels with different widespread damage have been recorded. The evolution of the damage scenario changes the modal shapes, the related frequencies and the damping ratios that through the comparison with the data of the initial conditions can de- tect the anomalies and then the intrinsic vulnerabilities. Through the curvature modal shape methods and the structural irregularity indices applied to different phases, it was possible evaluate the imperfection and the induced damage entity

Trophic compensation stabilizes marine primary producers exposed to artificial light at night

Artificial light at night (ALAN) is a widespread phenomenon along coastal areas. Despite in - creasing evidence of pervasive effects of ALAN on patterns of species distribution and abundance, the potential of this emerging threat to alter ecological processes in marine ecosystems has remained largely unexplored. Here, we show how exposure to white LED lighting, comparable to that experienced along local urbanized coasts, significantly enhanced the impact of grazing gastropods on epilithic microphytobenthos (MPB). ALAN increased both the photo-synthetic biomass of MPB and the grazing pressure of gastropods, such that consumers compensated for the positive effect of night lighting on primary producers. Our results indicate that trophic interactions can provide a stabilizing compensatory mechanism against ALAN effects in natural food webs

Ecological feedback mechanisms and variable disturbance regimes: the uncertain future of Mediterranean macroalgal forests

Loss of algal canopies can result in a shift towards a turf-dominated state, where variability in species life-history traits can determine new mechanisms of feedback, and influence the degraded system under variable regimes of disturbance. By focusing on rockpools dominated by Cystoseira brachycarpa, we tested the hypothesis that the alga Dictyopteris polypodioides could take advantage of extreme regimes of disturbance related to storms, and outcompete other turfs through a distinctive combination of life traits. Replacement of the canopy was initially driven by a mix of taxon-specific life-traits and resulting assemblages were susceptible to intense events of disturbance. Subsequently, D. polypodioides dominated removal quadrats, favored by density-dependent abilities to intercept more light and reach larger size than the rest of turf. These new positive feedbacks may contribute to maintain the modified state of the system and influence its ability to withstand extreme abiotic conditions

A finite element-discrete element approach for the analysis of the venice trans-lagoon railway bridge

In this paper, the feasibility of the utilization of a combined finite element/discrete element (FE-DE) approach to investigate the behavior of masonry arch bridges is proposed. Attention is paid to the assessment of the load carrying capacity by means of a suitable coupled FE-DE two-dimensional approach. This paper outlines the fields and limits of applicability of the FE-DE method to the study of masonry arch bridges. The main contribution is to evaluate the applicability of FE-DE, in particular its reliability to describe the nonlinear behavior of masonry arch bridges under increasing static loads, to catch kinematic failure mechanisms and collapse load multipliers, as well as to evaluate the role played by the backfill. A discussion on a possible approach to FE-DE modelling of the Venice trans-Lagoon masonry arch bridge is proposed. With such a purpose, a series of parametric analyses has been conducted in order to evaluate the influence of the different parameters involved on the behavior of the bridges. Pushover analyses have been performed to investigate the nonlinear behavior up to the collapse and up to a clear formation of a failure mechanism in the model

Giant g factor tuning of long-lived electron spins in Ge

Control of electron spin coherence via external fields is fundamental in spintronics. Its implementation demands a host material that accommodates the highly desirable but contrasting requirements of spin robustness to relaxation mechanisms and sizeable coupling between spin and orbital motion of charge carriers. Here we focus on Ge, which, by matching those criteria, is rapidly emerging as a prominent candidate for shuttling spin quantum bits in the mature framework of Si electronics. So far, however, the intrinsic spin-dependent phenomena of free electrons in conventional Ge/Si heterojunctions have proved to be elusive because of epitaxy constraints and an unfavourable band alignment. We overcome such fundamental limitations by investigating a two dimensional electron gas (2DEG) confined in quantum wells of pure Ge grown on SiGe-buffered Si substrates. These epitaxial systems demonstrate exceptionally long spin relaxation and coherence times, eventually unveiling the potential of Ge in bridging the gap between spintronic concepts and semiconductor device physics. In particular, by tuning spin-orbit interaction via quantum confinement we demonstrate that the electron Land\'e g factor and its anisotropy can be engineered in our scalable and CMOS-compatible architectures over a range previously inaccessible for Si spintronics

Ecoprofit environmental certification as a public good: SWOT analysis of a relationship network

The present work aims at carrying out an analysis of the strengths and weaknesses of the Ecoprofit certification through an institutionalist framework capable of incorporating the role of enterprises, institutions and relationship networks. Through the analysis of case studies on cooperation and on the food farming industry it is possible to subdivide the possible markets into 4 stages of maturity, according to the different degree of interaction among the agents, and to investigate the present and future role of environmental certifications seen as social capital increase vectors, thanks to their capability of recognizing and producing a culture of quality and, therefore, of sustainable development

Hybrid datasets: integrating observations with experiments in the era of macroecology and big-data

Understanding how increasing human domination of the biosphere affects life on earth is a critical research challenge. This task is facilitated by the increasing availability of open-source data repositories, which allow ecologists to address scientific questions at unprecedented spatial and temporal scales. Large datasets are mostly observational, so they may have limited ability to uncover causal relations among variables. Experiments are better suited at attributing causation, but they are often limited in scope. We propose hybrid datasets, resulting from the integration of observational with experimental data, as an approach to leverage the scope and ability to attribute causality in ecological studies. We show how the analysis of hybrid datasets with emerging techniques in time series analysis (Convergent Cross Mapping) and macroecology (Joint Species Distribution Models) can generate novel insights into causal effects of abiotic and biotic processes that would be difficult to achieve otherwise. We illustrate these principles with two case-studies in marine ecosystems and discuss the potential to generalize across environments, species and ecological processes. If used wisely, the analysis of hybrid datasets may become the standard approach for research goals that seek causal explanations for large-scale ecological phenomena. This article is protected by copyright. All rights reserved

Sensitivity to damage imperfection for multileaf masonry walls based on vibrational analyses

Damage-imperfection indicators based on variation of dynamic parameters allow to identify the intrinsic discontinuity and the damage of structures. Here, the structural health monitoring through the vibration-based approach has been carried out by two steps on three different multileaf masonry specimens (full infill, damaged infill, and strengthened infill) subjected to uniaxial compressive load. In the first step, the characterization of initial conditions based on the investigation of the intrinsic discontinuity and the manufacturing imperfections has been done. In this phase, the detection, localization, assessment, and prediction of damage have been given by the comparison between the experimental and numerical modal data calculated by the commercial finite element code. Subsequently, in the second step, starting from the identification of undamaged condition, the damage effects on changes of the dynamic parameters have been recorded. As well known, the incoherent response between the leaves is related to frequency values, damping ratios, and modal shapes