Exponential stabilization of infinite-dimensional systems by finite-dimensional controllers

This paper studies the feedback stabilization of abstract Cauchy problems with unbounded output operators by finite-dimensional controllers. Both necessary conditions and sufficient conditions for feedback stabilizability are presented. The proof of closed-loop stability is based on a novel input-output gain introduced in this paper. For systems satisfying a property we call quasi-finite, an equivalent characterization of feedback stabilizability is obtained. Quasi-finiteness is verified for classes of parabolic and hyperbolic equations

Self-help retrofitting technologies for low-cost housing construction. The case study of Vila Novo Ouro Preto, Brasil.

The paper presents low-tech and low-cost solutions such as, in particular, self-help retrofitting technologies, to improve the quality in spontaneous settlements (favelas) which arise close to the major Brazilian towns. In particular, a critical analysis of the favela Vila Novo Ouro Preto in Belo Horizonte has been elaborated, highlighting both social, cultural and technical aspects to design suitable technological components to be adopted in order to improve environmental comfort. The study has been developed in order to meet people needs and expectations so as to guide planning and design perspectives aiming at improving the quality of life in a sustainable socio-cultural way. The contribution suggests a selection of interesting techniques and processes achievable in self-help construction; some of them are quite innovative since they use in a new and different way recycled materials and products, thus boosting economic growth and social development

Quasi-static and low-velocity impact behavior of intraply hybrid flax/basalt composites

In an attempt to increase the low-velocity impact response of natural fiber composites, a new hybrid intraply woven fabric based on flax and basalt fibers has been used to manufacture laminates with both thermoplastic and thermoset matrices. The matrix type (epoxy or polypropylene (PP) with or without a maleated coupling agent) significantly affected the absorbed energy and the damage mechanisms. The absorbed energy at perforation for PP-based composites was 90% and 50% higher than that of epoxy and compatibilized PP composites, respectively. The hybrid fiber architecture counteracted the influence of low transverse strength of flax fibers on impact response, irrespective of the matrix type. In thermoplastic laminates, the matrix plasticization delayed the onset of major damage during impact and allowed a better balance of quasi-static properties, energy absorption, peak force, and perforation energy compared to epoxy-based composites

Demolishing or Renovating? Life Cycle Analysis in the Design Process for Building Renovation: The ProGETonE Case

It is well known that a large part of the existing European building stock needs to be renovated to increase structural and energy performance. Unfortunately, deep renovations come with high ini-tial costs, and therefore, owners and real estate developers often prefer complete demolition and reconstruction. Both options depend on specific factors, and to select which option could be the closest to the optimal scenario, it is necessary to evaluate all environmental, social, and economic indicators. Life Cycle Analysis is of great significance to evaluate building sustainability, in partic-ular through the comparison between different design alternatives. However, the life cycle impacts of the construction stage depend on selected materials and technologies that can be subject to change during the subsequent stages of the design process, i.e., moving from preliminary design to detailed design and execution plans. With the aim of understanding the role of LCA during the design process, the case study of “ProGETonE—Proactive Synergy of Integrated Efficient Tech-nologies on Buildings’ Envelopes” has been addressed, leading to the observation that the impacts, in particular the global warming potential (GWP), raised significantly. Building Information Mod-elling (BIM) helped the information sharing and management of this project, which consists of the deep renovation and architectural reshaping of an existing student residence through the con-struction of integrated façade systems

Can a fully integrated approach enclose the drainage system design and the flood risk analysis?

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Displacement monitoring in airport runways by persistent scatterers SAR interferometry

Deformations monitoring in airport runways and the surrounding areas is crucial, especially in case of low-bearing capacity subgrades, such as the clayey subgrade soils. An effective monitoring of the infrastructure asset allows to secure the highest necessary standards in terms of the operational and safety requirements. Amongst the emerging remote sensing techniques for transport infrastructures monitoring, the Persistent Scatterers Interferometry (PSI) technique has proven effective for the evaluation of the ground deformations. However, its use for certain demanding applications, such a as the assessment of millimetric differential deformations in airport runways, is still considered as an open issue for future developments. In this study, a time-series analysis of COSMO-SkyMed satellite images acquired from January 2015 to April 2019 is carried out by employing the PSI technique. The aim is to retrieve the mean deformation velocity and time series of the surface deformations occurring in airport runways. The technique is applied to Runway 3 at the “Leonardo da Vinci” International Airport in Rome, Italy. The proposed PSI technique is then validated by way of comparison with the deformation outcomes obtained on the runway by traditional topographic levelling over the same time span. The results of this study clearly demonstrate the efficiency and the accuracy of the applied PSI technique for the assessment of deformations in airport runways

Predicting the bearing capacity of road flexible pavements using GPR

Most of the damage in road-flexible pavements occur where stiffness of the asphalt and loadbearing layers is low. To this extent, an effective assessment of the strength and deformation properties of these layers can help to identify the most critical sections [1]. This work proposes an experimental-based model [2] for the assessment of the bearing capacity of road-flexible pavements using ground-penetrating radar (GPR – 2 GHz horn antenna) and the Curviameter [3] non-destructive testing (NDT) methods. It is known that the identification of early decay and loss of bearing capacity is a major challenge for effective maintenance of roads and the implementation of pavement management systems (PMSs). To this effect, a time-efficient methodology based on a quantitative modelling of road bearing capacity is developed in this study. The viability of using a GPR system in combination with the Curviameter NDT equipment is also proven. The research is supported by the Italian Ministry of Education, University and Research under the National Project “Extended resilience analysis of transport networks (EXTRA TN): Towards a simultaneously space, aerial and ground sensed infrastructure for risks prevention”, PRIN 2017, Prot. 20179BP4S

An investigation into the railway ballast grading using GPR and image analysis

This study reports on an investigation into the grain size distribution of the railway ballast using ground-penetrating radar (GPR) and image analysis. The proposed approach relies on the hypothesis that the dimension (grading) of the ballast aggregates can influence the back-reflected spectrum received by the use of GPR. This assumption was confirmed by the finite difference time-domain (FDTD) simulations of the GPR signal, which were run by using the numerical simulator package gprMax 2D. A regression model was developed which related the "equivalent" diameter of the ballast aggregates and the frequency of the peak within the received spectrum. The model was validated in the laboratory environment by means of a 155 cm x 155 cm x 50 cm methacrylate tank, filled up with railway ballast. An air-coupled GPR system equipped with a 2000 MHz central frequency antenna was used for testing purposes. A total of three spatial distributions of the ballast aggregates within the tank were investigated, by emptying out and filling up thrice the tank with the same material. The geometric information on the ballast grading obtained from the simulation-based regression model was compared to the actual grading curve of the ballast. To this effect, an algorithm based on the automatic image analysis was developed. The comparison showed that the modelled aggregate diameter corresponded to the 70 % of the grading of the material sieved out in the laboratory. This contribution paves the way to new methodologies for the non-destructive assessment and the monitoring of segregation phenomena within the railway ballast layers in railway track-beds