CNR Construction Technologies Institute

Bari, Italy

CNR Construction Technologies Institute

Bari, Italy
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Bisegna P.,University of Rome Tor Vergata | Caruso G.,CNR Construction Technologies Institute
Journal of Sound and Vibration | Year: 2011

This paper put forth a new approach, based on the mathematical theory of homogenization, to study the vibration localization phenomenon in disordered rotationally periodic structures. In order to illustrate the method, a case-study structure is considered, composed of pendula equipped with hinge angular springs and connected one to each other by linear springs. The structure is mistuned due to mass and/or stiffness imperfections. Simple continuous models describing the dynamical behavior of the structure are derived and validated by comparison with a well-known discrete model. The proposed models provide analytical closed-form expressions for the eigenfrequencies and the eigenmodes, as well as for the resonance peaks of the forced response. These expressions highlight how the features of the dynamics of the mistuned structure, e.g. frequency split and localization phenomenon, depend on the physical parameters involved. © 2010 Elsevier Ltd.

Scamoni F.,CNR Construction Technologies Institute | Scrosati C.,CNR Construction Technologies Institute
Proceedings of Forum Acusticum | Year: 2014

The sound insulation of façades plays a key role in the improvement of internal living comfort and protection of the inhabitants from the disturbing noise coming from the outside of the buildings. Only in few countries, on-site measurements and evaluations are made, in order to verify the real performance of building façades. Italy is one of them and ITC CNR, the main Italian Building Research Institute, has collected a dataset of such measurement results that can be considered unique of its kind, taking into account that on-site façade sound insulation measurements are less frequent and more complicated than internal sound insulation measurements. Starting from this dataset, all the factors that influence the final performance of the façade are analyzed and in particular the main acoustic and non-acoustic parameters, such as wall structures and glazing layers, window percentage and volume/surface ratio. The internal sound level is evaluated taking into account the contribution of outdoor or neighbor noise.

Strini A.,CNR Construction Technologies Institute | Schiavi L.,CNR Construction Technologies Institute
Applied Catalysis B: Environmental | Year: 2011

Photocatalytic materials for air depollution have received increasing attention in the last years, particularly for outdoor applications where the sun is used as freely accessible UV-A source. The naturally available irradiance at an outdoor catalytic material surface is, however, extremely variable according to the time of the day, the season and the local weather. The relationship between irradiance and activity is therefore of great importance in the characterization of a photocatalytic depolluting material. This work illustrates the investigation carried out on the toluene photodegradation activity of a cementitious photocatalytic material versus the UV-A irradiance in the 100-850μWcm-2 range. The photoactivity measurements were carried out using a stirred flow reactor. A specific successive approximation method was developed in order to bring all activity measurements to the same predefined pollutant concentration ensuring uniform conditions across the experiment. The study was repeated at four different pollutant concentrations lying between 0.25 and 1.0μmolm-3, showing evidences of a non-linear behaviour at low irradiances. A correction method for the irradiance measurement is also described, allowing the adjustment for the error caused by the specific spectral sensitivity of the utilized radiometric sensor. © 2011 Elsevier B.V.

Scrosati C.,CNR Construction Technologies Institute | Scamoni F.,CNR Construction Technologies Institute | Zambon G.,University of Milan Bicocca
Applied Acoustics | Year: 2015

The uncertainty of field measurements of a façade was evaluated by a Round Robin Test (RRT) conducted in a full-scale experimental building at the Construction Technologies Institute of the National Research Council of Italy (ITC-CNR). Each of the 9 teams involved in the RRT replicated the tests 5 times, for a total of 45 measurements, while reverberation time was repeated 110 times. Both for façade sound insulation and reverberation time the main variations in the one-third octave bands were found in the low frequencies range. The study was also focused on the evaluation of single number quantities (SNQs) and their uncertainties. Single number quantities were evaluated in both narrow (from 100 to 3150 Hz) and extended (from 50 to 5000 Hz) range. Concerning the SNQs and their uncertainties, no significant differences were observed whether the low frequencies were included or not, unlike the case of airborne sound insulation (investigated in the first part of this study). The uncertainty results were compared with the relevant standards and with literature results. Based on these comparisons, it was highlighted that the standard deviation of reproducibility of façade elements is not adequately reflected in the ISO 12999-1 and further research is needed to specify the in situ standard deviation of reproducibility for façade elements. © 2015 Elsevier Ltd.All rights reserved.

Marinetti S.,CNR Construction Technologies Institute | Cesaratto P.G.,CNR Construction Technologies Institute
NDT and E International | Year: 2012

In this paper an emissivity measurement method is proposed; it relies on individual calibration functions, and is based on the spectral response of a specific IR sensor. The reflected temperature is kept constant during the test, and its knowledge is not required. Results of measurements on materials commonly used as emissivity references in quantitative thermography are reported. Computer simulations of indoor and outdoor thermographic inspections show the differentiated influence of emissivity and surroundings temperature on the measurement accuracy. Finally experimental results of absolute and differential temperature measurements are discussed. © 2012 Elsevier Ltd. All rights reserved.

Cesaratto P.G.,University of Padua | Cesaratto P.G.,CNR Construction Technologies Institute | De Carli M.,University of Padua
Energy and Buildings | Year: 2013

In the last years many studies concerning the evaluation of the thermal conductance of building elements via measurements have been carried out; this value has to be ensued from the analysis of recorded temperature and heat flux profiles. The determination of this property in situ would allow a more accurate a more accurate evaluation of the real heating energy demand of a building. Papers discussing different data analysis methods are present in literature and measurements on test components under real conditions and evaluations on different theoretical aspects by means of numerical simulations have been already developed. This paper aims at widening the existent literature of the in situ evaluation of the thermal conductance, through the discussion of the results of a measuring campaign which lasted four years on real buildings, and by comparing the reference specific thermal conductance (C) values with those computed on the basis of the measurements. Various tests on the same elements are discussed. Finally an analysis on the influence of the C value on the evaluation of the net heating energy demand of a building in different climates is presented. © 2012 Elsevier B.V.

Bisegna P.,University of Rome Tor Vergata | Caruso G.,CNR Construction Technologies Institute
Journal of Sound and Vibration | Year: 2012

This paper deals with the analysis and optimization of tuned mass dampers (TMDs). It provides design formulas for maximizing the exponential time-decay rate (ETDR) of the system transient response. A detailed analysis is presented for the classical TMD configuration, involving an auxiliary mass attached to the main structure by means of a spring and a dashpot. Analytic expressions of the optimal ETDR are obtained for any mass ratio and tuning condition. Then, a further optimization with respect to the latter is performed. The proposed method is applied also to other TMD configurations involving an auxiliary mass connected to both the main structure and the ground, as well as to a piezoelectric damping device. A justification to the well-known heuristic optimality condition based on the enforcement of coincident couples of complex conjugate poles is presented. That condition is shown, however, to fail in providing optimal solutions for some mass ratio values and/or TMD configurations, and the optimality conditions prevailing in those cases are derived. The present analysis, besides its theoretical interest, may be useful in practical applications, e.g., to assess the sensitivity of the optimal ETDR with respect to the design parameters or to promptly adjust some of those parameters during service, after any variation of the operative conditions. © 2012 Elsevier Ltd. All rights reserved.

Fedele L.,CNR Construction Technologies Institute | Colla L.,CNR Construction Technologies Institute | Bobbo S.,CNR Construction Technologies Institute
International Journal of Refrigeration | Year: 2012

Nanofluids, i.e. suspensions of nanoparticles in liquids, seem to be very promising as thermal vectors in systems where secondary fluids are applied. Here, the characterisation of water-based nanofluids containing titanium oxide (TiO 2) in concentrations ranging between 1 and 35% in mass is presented. First of all, the mean nanoparticle diameters are studied by dynamic light scattering (DLS) technique and the nanofluid stability is analysed by Zeta potential measurements. Then, the behaviour of viscosity as a function of composition and temperature is evaluated by means of a rheometer, in the temperature range between 283 K and 343 K. Furthermore, the thermal conductivity of these nanofluids is measured, in order to understand its possible enhancement as a function of temperature and nanoparticle concentration. © 2012 Elsevier Ltd and IIR. All rights reserved.

Marinetti S.,CNR Construction Technologies Institute | Vavilov V.,Institute of Introscopy
Corrosion Science | Year: 2010

Principles of infrared thermographic non-destructive testing for determining hidden corrosion in metals are summarized and discussed. 1D, 2D and 3D heat conduction models are introduced to simulate thermal processes in corroded areas. In thick metals, the lateral heat dissipation is mainly responsible for significantly smoothing the temperature contrast curves. Modelling small-size corroded sites requires 3D numerical models. Numerous defects have been simulated and the inversion formulas for determining material loss have been modelled for both flash and square-pulse heating. It has been shown that corrosion characterization inaccuracy is lower than 20% in cases representing a practical interest. © 2009 Elsevier Ltd. All rights reserved.

Belussi L.,CNR Construction Technologies Institute | Danza L.,CNR Construction Technologies Institute
Energy and Buildings | Year: 2012

The article explains the stages of a research project aimed at establishing an analytical methodology to analyse the energy performance of existing buildings through Energy Signature (ES), a monitoring method in which measured consumption is related to climatic variables. The energy consumption of buildings represents a large percentage of the total consumption of a country. The consumptions are often higher than those actually needed to ensure optimal conditions for the comfort of a zone, due to both typological defects (poor thermal insulation, thermal bridges, etc.), and wrong behaviour of users. ES has a two-fold purpose: on one hand it can be used as a pre-energy audit by a professional to highlight the glaring problems. On the other hand it can be a valuable tool for raising end users' awareness. The goal of the present study is to define a new accurate calculation method, called MESH, aimed at characterizing the ES from a scientific point of view. In the article, the ES is applied to the heating period; the method can also be used to analyse other types of energy consumption, such as cooling and electrical consumption; in this case it is important to define the appropriate climatic variable. © 2012 Elsevier B.V. All rights reserved.

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