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A comprehensive approach to small and large-scale effects of earthquake motion variability
No full textThis work deals with the evaluation of the effects of the spatial variability of earthquake input motion on the dynamic response of structures. The variability of the free-field motion both over the area of a single foundation as well as over the distance between independent foundations of large structures is considered. Two significant applications of the proposed numerical procedure are presented. In the first one a base isolated nuclear reactor building is considered where the issue of the rocking excitation on the peak value of axial forces in the isolation devices and acceleration in the building structure is investigated. Extended structures having tall members are considered as second application. A cable-supported bridge model, formerly studied within a simpler representation of the seismic ground motion, serves as case study in which spatial variability acts at different scales
Stability analysis of different types of steel scaffolds
No full textScaffolds are temporary structures commonly used in construction to support various types of loads. Recently their collapse is becoming more common as shown by the number of accidents and injuries reported. The paper analyzes the main flaws and imperfections that could lead to the collapse of the scaffoldings. The study has been focused at the numerical level on three different types of steel scaffoldings: (i) joint tubes, (ii) multidirectional and (iii) prefabricated systems, which are commonly used in Italy. Several finite element simulations under different loading conditions on three types of steel scaffoldings have been performed, taking into account the imperfections during the assembly at the construction site, the base boundary conditions and the effects of lateral restraint arrangement. Finally, the study proposes an empirical formula to identify the critical load of different types of steel scaffoldings based on the number of story levels and the type of boundary conditions
Lignin/Phosphinate/PA11 Composite: A Renewable & Sustainable Intumescent Flame Retardant System for Textile Application
No full textIntumescent formulations based on lignin & ammonium polyphosphate (APP) were studied previously. This work is dedicated to lignin/Zinc Phosphinate combination to improve flame retardant properties of PA11 in order to develop sustainable flame retardant textile. Lignin has the advantage of being bio-based compound, can be effectively used as carbon source for intumescent with other flame retardant additives. Different PA11 composites based on lignin and zinc phosphinateare formulated and extruded. Thermal stability is studied by TGA, flammability tests were performed using UL94 vertical flame test and cone calorimetery test used for fire behavior study
Survey on a Neural Network for Non Linear Estimation of Aerodynamic Angles
No full textUnmanned Aerial Vehicles (UAV) design may involve issues on redundancy of the systems due to restricted available space and allowable weight. Virtual sensors offer great advantages from this point of view and several research projects carry out more or less complicated solutions in order to estimate a signal without applying a physical sensor. This approach brings to a reduction of the overall cost and to improve the Reliability, Availability, Maintainability and Safety (RAMS) performance. The patented technology named Smart-ADAHRS (Smart - Attitude and Heading Reference System) is a powerful technique presented during previous research for estimation of the aerodynamic angles. This algorithm is based on Artificial Neural Network (ANN) and receive inputs from onboard sensors only. Whereas previous studies considered also the signals coming from the Flight Control System (FCS), this work presents the important simplification of not considering them in the input vector. This paper resumes the previous results obtained in simulated environment with former neural networkbased estimators. Then, a comparison of the results obtained by the new estimator, applying the reduced input vector in different environments, is carried out. Moreover, it re-discusses accuracy by means of a new test case that consider simulated realistic faults and noise. Eventually, a first analysis around performance in operative environment is conducted using data obtained from flight test campaigns. Results show how accuracy is preserved both in realistic situation and critical circumstances
Francesco Prestino and Giacomo Tensini, engineers at the service of the king of Spain. Fortifications reinforcement, cities drawings
No full textIn the first half of the Seventeenth century, some of the most important and prolific military engineers at the service of Spain focused their attention on the northern Italian peninsula. In particular, interests laid on the border between the State of Milan and the Duchy of Savoy. In few decades, actions of fortification reinforcement of the cities located in the border were undertaken, along with the aggression and the conquest of some Piedmont's obsolete fortresses subsequently reinforced in the walls and the defence aimed at the prevention of a France-Savoy counterattack, after the unsuccessful sieges of Turin and Casale Monferrato (1640). Especially starting from the 1630s, Francesco Prestino stood out as " ingegnere maggiore dell'Esercito di sua maestà nostro signore nel Stato di Milano". In 1633, he was commissioned by Philip IV to draw an atlas of cities of the State of Milan, not yet identified. Teacher of Gaspare Beretta, who will replace him after his death, he was committed to the defence of the cities of the State of Milan during the war that broke out after the death of Vittorio Amedeo I of Savoy and the occupation of Piedmont by the Marquis of Leganés. Active in the newly Spanish fortress of Vercelli, he dealt with the strengthening and the maintenance of the walls signing, in the first half of the 1640s, a series of reports on the conditions of the fortresses of the State of Milan. The documents must be linked to an atlas of drawings preserved in the Biblioteca Nacional de España (already the subject of a contribution in the conference Fortmed 2015) and to a series of drawings dated 1642, preserved in the Biblioteca Ambrosiana of Milan and signed by Giovanni Giacomo Tensini, a military engineer who was also active in Gaspare Beretta's entourage
How to Address Subsidence Evaluation for a Fractured Carbonate Gas Reservoir Through a Multi-disciplinary Approach
No full textThis paper presents and discusses the outcome of a multi-disciplinary study aimed at evaluating ground surface movements which could be potentially induced by the future gas production of a carbonate reservoir located in central Italy. Thanks to both good quality and quantity of data (i.e. seismic surveys, well logs, petrophysical data, PVT-PressureVolumeTemperature- fluid data, geotechnical lab data) the issue was addressed via the set-up of a coupled 3D fluid flow and mechanical model based on the preliminary definition of a 3D structural and geological model. Because it is a forecast study, no model calibration was possible, consequently a set of sensitivity analyses were performed so as to assess the effect of the most critical parameters on subsidence evolution. The 3D FEM (Finite Element Method) mechanical model was set up by adopting an elastoplastic constitutive law. The model was populated via the integration of data from different sources at different scales (i.e. lab tests, in situ acquisition, literature) and data interpretation adopting a traditional rock mechanics approach, in other words Bieniawski classification and the Barton classification. The obtained strength and deformation parameters depend on the Hoek and Brown criterion and the GSI classification applicatio
Electromagnetic characterization of installed antennas through UAVs
No full textThe characterization of the radiation pattern of low-frequency antennas is a challenging problem that requires an advanced strategy to reach the expected measurement accuracy. A micro Unmanned Aerial Vehicle (UAV) has been used as a radio frequency test-source to perform such measurements with an innovative technique, obtaining outstanding results. In particular, a Differential Global Navigation Satellite System (DGNSS) based positioning has been introduced through the use of an external GNSS (Global Navigation Satellite System) receiver to obtain the UAV position during the flight with a high level of accuracy. The system has been experimentally tested since a challenging topic is to define all the issues that can occur in the combined use of unmanned aerial systems and electromagnetic components. For this reason, it was investigated to assess sensors problems (such as interferences and positioning troubles with the external sensor) and to define some best practices in the use of such system for this particular field of application to reach the expected result. Finally, an experimental case to demonstrate the suitability of the proposed system is presented in this paper. The radiation pattern of a log-periodic antenna at 250 MHz has been measured with good results