Cazzuffi D.,Centro Elettrotecnico Sperimentale Italiano |
Moraci N.,University of Reggio Calabria |
Calvarano L.S.,University of Reggio Calabria |
Cardile G.,University of Reggio Calabria |
And 2 more authors.
Geosynthetics | Year: 2014
Geogrids are one of the most common types of geosynthetic used for soil reinforcement. In particular, the use of geosynthetics has unique advantages over other soil strengthening techniques, because of technical, economic, and sustainability reasons. The redistribution of internal stresses within reinforced soil mass and its deformations depends on soil shear strength, reinforcement tensile strength and stiffness, and on interface stress mechanisms between soil and reinforcement. The results of pullout tests carried out on two extensible geogrids embedded in a compacted granular soil, in terms of peak pullout resistance at soil-geosynthetic interface, are analyzed. Some considerations about deformation behavior analysis are also reported. The equipment incorporates two sleeves near the slot at the front wall of the pullout box to avoid front wall effects, as recommended by researchers. The pullout apparatus is capable producing the confined failure of a geosynthetic specimen by using an internal clamp placed inside the soil beyond the sleeves.
Solomos G.,European Commission - Joint Research Center Ispra |
Berra M.,Centro Elettrotecnico Sperimentale Italiano
Materials and Structures/Materiaux et Constructions | Year: 2010
The dynamic behavior of the bond slip between a deformed reinforcing bar and plain concrete has been experimentally investigated by employing Hopkinson bar techniques. Pullout tests with various specimen types (unconfined, confined, cast-in-place, post-installed etc.) have been performed. Pullout of the steel rebar and splitting of the concrete cylinder have been the failure modes induced. Test results comprise peak pullout forces and complete bond stress-slip diagrams. They clearly show that the dynamic pullout forces and curves are well above the static ones, and that the pullout work of bond failure is considerably greater for the dynamic impact loading. Confinement, provided by a steel tube, leads to improved bonding; peak loads increase up to 2.5 times. The effects of bond length and concrete strength have also been put into evidence. Finally it has been verified that post-installed rebars, depending upon the particular adhesive employed, can achieve the same bond resistance as the cast-in-place ones. © 2009 RILEM.
Brenna M.,Polytechnic of Milan |
De Berardinis E.,Centro Elettrotecnico Sperimentale Italiano |
Delli Carpini L.,ENEL S.p.A |
Foiadelli F.,Polytechnic of Milan |
And 6 more authors.
IEEE Transactions on Smart Grid | Year: 2013
The widespread use of distributed generation (DG), which is installed in medium-voltage distribution networks, impacts the future development of modern electrical systems that must evolve towards smart grids. A fundamental topic for smart grids is automatic distributed voltage control (ADVC). The voltage is now regulated at the MV busbar acting on the on-load tap changer of the HV/MV transformer. This method does not guarantee the correct voltage value in the network nodes when the distributed generators deliver their power. In contrast, the ADVC allows control of the voltage acting on a single generator; therefore, a better voltage profile can be obtained. In this paper, an approach based on sensitivity theory is shown to control the node voltages regulating the reactive power injected by the generators. After the theoretical analysis, a numerical example is presented to validate the theory. The proposed voltage regulation method has been developed in collaboration with Enel Distribuzione S.p.A. (the major Italian DSO), and it will be applied in the Smart Grids POI-P3 pilot project, which is financed by the Italian Economic Development Ministry. Before the real field application in the pilot project, a real-time digital simulation has been used to validate the algorithm presented. Moving in this direction, Enel Distribuzione S.p.A. built a new test center in Milan equipped with a real-time digital simulator (from RTDS Technologies). © 2010-2012 IEEE.
Lonati G.,Polytechnic of Milan |
Pirovano G.,Centro Elettrotecnico Sperimentale Italiano |
Sghirlanzoni G.A.,Centro Elettrotecnico Sperimentale Italiano |
Zanoni A.,Centro Elettrotecnico Sperimentale Italiano
Atmospheric Research | Year: 2010
The so-called "one atmosphere modelling approach" is applied over a mesoscale domain and model outputs for gaseous pollutants (NOX and O3) and for size resolved PM mass concentration (PM10 and PM2.5) are compared to observed data time series at reference sites representative of different locations (urban, suburban and rural sites) throughout the modelling domain. The CAMx model (Comprehensive Air quality Model with eXtensions) was used for simulation over the Po valley air basin with a 10 × 10 km2 spatial resolution based on emission and meteorological data for the 01/04/2003-31/03/2004 period. Model results for speciated PM2.5 mass concentration (including nitrate, sulphate, ammonium, elemental carbon and organic matter) are compared to artefact-corrected data from campaigns performed for the city of Milan and its neighbourhoods. Since model results are not concurrent with the available PM2.5 measurements, bootstrapping technique is applied in order to extract from model results restricted warm-season and cold-season data populations suitable for quantitative comparison with measured data. The model seems able to correctly reproduce the spatial distribution and the local concentration gradients of both PM10 and PM2.5 bulk mass with high concentration levels on the Po valley, increasing around urban areas. However, the comparison with experimental data shows relevant underestimations of PM10 and PM2.5 concentrations, especially at the most polluted urban "hot spots", where underestimations rise up to 60% of the actual PM levels. Speciated PM2.5 results, still in agreement with local composition gradients, point out that PM mass underestimations essentially derive from a 60% underestimation of organic matter (in both seasons) and sulphate (cold season only) concentrations, whereas a rather good agreement is observed for the other chemical species and especially for the ammonium-nitrate system. Such results suggest to better refine emission inventory data, with particular attention to sources like domestic heating wood burning, and to consider that the fine PM formation mechanism forms condensable gaseous precursors, directly emitted in the atmosphere, whose contribution may account for a large part of the missing PM mass in the cold season. © 2009 Elsevier B.V. All rights reserved.
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: LCE-07-2016-2017 | Award Amount: 3.42M | Year: 2016
Fight against climate change has its main battlefield at the energy sector. Electricity and transport are the largest contributors to GHG emissions; the trend in transport toward electric vehicle will increase pressure on the electricity system and fundamentally change its dynamics. With producers focused on their legitimate business targets, and consumers focused on security of supply and low prices, the burden of decarbonizing electricity falls on policy makers as driving force, and on transport system operators (TSOs) as technical managers that ensure the safety and stability of supply. Grid stability is a delicate equilibrium, where some agents provide stability via ancillary services (regulating voltage and frequency) and others rely on that stability (consuming energy and/or disturbing the frequency due to embedded capacitors/impedances); power producers are usually stabilizers (synchronous turbines that provide inertia against sudden changes). Penetration of non-synchronous renewables such as Wind and PV threatens to disrupt the balance, especially in islands and poorly interconnected areas, as they provide power but rely on stability provided by others; this forces the system to have lots of synchronous generators idle just for stability, which is inefficient and costly. GRIDSOL wants to change the approach: we propose Smart Renewable Hubs, where a core of synchronous generators (CSP and biogas combined cycle HYSOL) is integrated with PV under a dynamic control system (DOME), self-regulating and providing ancillary grid services thanks to firm, flexible generation on a single output, tailored to a specific location, relieving pressure on the TSO. The project will research an advanced control (DOME) to ensure operation efficiency and grid stability with higher RES penetration, and a multi-tower concept for CSP cost reduction and efficiency improvement, to provide secure, clean and efficient electricity by getting the most of each renewable primary source.
Corsi S.,Centro Elettrotecnico Sperimentale Italiano
IET Generation, Transmission and Distribution | Year: 2010
Two very promising wide-area voltage protection (V-WAP) solutions, able to face stability and security problems in the transmission grid, are presented. Both require real-time effective risk indicators whose timely computing is a crucial issue. The first method makes use of a voltage instability index based on real-time computing of the Thevenin equivalent circuit seen by a given high voltage (HV) bus. The innovating algorithm utilised for the real-time adaptive identification of the Thevenin voltage and impedance equivalent values requires local phasor measurements at fast sampling rate. The unique ability of the second method is mainly because of an effective coordination with a supposed operating wide-area voltage regulation (V-WAR) modern system where the secondary and tertiary voltage regulations (SVR and TVR, respectively) operate according to their hierarchies. Evidence for the feasibility and simplicity in defining and developing an effective V-WAP solution once reliable real-time risk indicators are available is provided. The feasibility of the first method comes from the high computing speed of the local risk indicator at each area bus where a phasor measurement unit (PMU) is installed. The main simplification of the second method comes from the already existing and appropriate subdivision of the network into areas provided by the operating SVR, the same areas as those of the protection scheme intervention. From this starting point, a voltage stability index is proposed operating the area load shedding (LS) according to a simple and incontrovertible logic based on the real-time area control effort. Dynamic simulation results on the North Italy power system show the proposed protection scheme's effectiveness and ability to achieve the continuity and stability of the controlled power system in front of a ramping load increase, by also containing the LS amount. © 2010 The Institution of Engineering and Technology.
Cazzuffi D.,Centro Elettrotecnico Sperimentale Italiano
10th International Conference on Geosynthetics, ICG 2014 | Year: 2014
The use of exposed geomembranes for the rehabilitation of concrete and masonry dams was introduced in Italy in 1976, when the entire upstream face of a 11 m high masonry dam was lined with a 2 mm thick PVC (polyvinyl chloride) geomembrane as waterproofing element (Lago Miller). In the following applications (among which Lago Nero, 1980; Piano Barbellino, 1987; Cignana, 1988), the system progressively evolved. In fact, instead of using only one component, i.e. a PVC geomembrane, the watertight function was performed by a bi-component geocomposite, obtained by thermal coupling of the PVC geomembrane with a PET (polyester) nonwoven needle-punched geotextile directly during the manufacturing process in factory, thus obtaining an anti-puncturing function, reducing the installation time and increasing the dimensional stability of the geomembrane itself. The geotextile in-plane drainage capacity also allowed to prevent the accumulation of water between the geomembrane and the dam itself, solving one of the major concerns for a good long-term performance of the whole system. From 1988 to present, this technique underwent several other changes, mainly thanks to the use of additional geosynthetics, such as geonets (Publino, 1988) and as thick nonwoven needle-punched geotextiles which allow to avoid the surface regularisation before the geomembrane installation (Camposecco, 1993). In all these applications, the geomembranes were left exposed on the upstream face, without external protection, to environmental factors and weather conditions, especially to UV rays, very intense also because many of these dams are at high elevation (typically greater than 2000 m). On the other hand, the fact that geomembranes are exposed makes it easier to control and monitor their behaviour vs. time. Therefore, in order to verify the performance of the waterproofing system over time, several geomembrane samples have been taken from a considerable number of dams. These samples have then been subjected to physical and mechanical tests, in order to observe the evolution of the properties of the geosynthetics over the years. In a lot of cases, particularly when the results of tests on virgin samples were available, it was possible to evaluate the residual life of exposed geomembranes on the different types of dams.
Cazzuffi D.,Centro Elettrotecnico Sperimentale Italiano
Geotechnical Special Publication | Year: 2016
The use of exposed geomembranes for the rehabilitation of concrete and masonry dams was introduced in Italy in 1976, when the entire upstream face of an 11 m high masonry dam was lined with a 2 mm thick PVC (polyvinyl chloride) geomembrane as the waterproofing element (Lago Miller). In subsequent applications, the system progressively evolved. From 1988 to present, this technique underwent several other changes, mainly thanks to the use of additional geosynthetics, such as geonets and as thick nonwoven needle-punched geotextiles which allow to avoid the surface irregularities before the geomembrane installation. In all of these applications, the geomembranes were left exposed on the upstream face, without any external protection, to environmental factors and weather conditions, especially to UV rays, which are very intense because many of these dams are at high elevation (typically around 2.000 m above the sea level). On the other hand, the fact that geomembranes are exposed makes it easier to control and monitor their behavior over time. Therefore, in order to verify the performance of the waterproofing system, several geomembrane samples have been taken in different years from a considerable number of dams. These samples have then been subjected to physical and mechanical tests, in order to observe the change of the properties of the geomembranes over the years. In several cases, particularly when the results of tests on virgin samples were available, it was possible to evaluate the residual life of exposed geomembranes on the different types of dams. The main updated results of this large research program will be reported in the paper. © ASCE.
Centro Elettrotecnico Sperimentale Italiano | Date: 2014-07-28
A Monolithic photovoltaic cell is proposed. Said cell comprises at least one junction. Each one of said at least one junction comprises a base formed by a doped semiconductor material of a first conductivity type and an emitter formed by a doped semiconductor material of a second conductivity type opposed to the first. Said emitter is stacked on the base according to a first direction. The semiconductor material of the base and/or of the emitter of at least one of said at least one junction is a semiconductor material formed by a compound of at least one first element and a second element. The band gap and the lattice constant of said semiconductor material of the base and/or of the emitter depend on the concentration of said first element in said compound with respect to said second element. Said concentration of the first element in said compound with respect to the second element is not uniform along said first direction, being equal to a first value at a lower portion of said base and/or emitter and being equal to a second value lower than the first value at an upper portion of said base and/or emitter. Said upper portion is above said lower portion according to the first direction.
Cristiani P.,54 Energy |
Perboni G.,Centro Elettrotecnico Sperimentale Italiano
Bioelectrochemistry | Year: 2014
Biofouling and corrosion phenomena dramatically reduce the functionality of industrial cooling circuits, especially in marine environments. This study underlines the effectiveness of a low level chlorination treatment of seawater to prevent biological fouling and biocorrosion.Reported examples emphasize the reaction of chlorine with bromide, ammonia and organic compounds in seawater and the effectiveness of a treatment performed in such a way to guarantee a residual concentration lower than 3. μM at the outlet of the condensers.In a brief review of antifouling strategies, alternatives to chlorination and the monitoring approach able to optimize the treatments are also reported.An integrated, on-line system based on electrochemical probes (Biox system and a linear polarization resistance probe) demonstrated to be sufficient to monitor in real time: corrosion, biofilm growth and chemical treatments based on chlorine or alternative oxidant products (chlorine dioxide, etc.).A careful electrochemical monitoring and the optimized treatments help the plant operators of industrial cooling circuits prevent the decay of the equipment performance, allowing at the same time the control of the halogenated by-products formation. © 2014 Elsevier B.V.