1,721,002 research outputs found
L’illuminazione nelle biblioteche storiche: un metodo di analisi applicato ad otto biblioteche statali pubbliche in roma
No full textIl presente lavoro si basa sugli studi effettuati dagli autori nell’ambito dell’indagine sperimentale sulle Biblioteche Statali Pubbliche in Roma, commissionata dal Ministero per i Beni e le Attività Culturali al Centro di Studio sulle Cause di Deperimento e sui Metodi di Conservazione delle Opere d’Arte del CNR di Roma. Il lavoro, effettuato da un gruppo di ricercatori, appartenenti al Centro ed a diversi Dipartimenti della Facoltà di Ingegneria dell’Università di Roma “la Sapienza”, è finalizzato alla valutazione delle condizioni strutturali ed ambientali in cui vertono le singole Biblioteche. Lo studio è articolato come segue:
controllo della stabilità strutturale, con la finalità di verificare fenomeni di dissesto e/o di degrado anche con indagini geotecniche;
controllo delle condizioni di sicurezza degli ambienti e degli impianti;
monitoraggio microclimatico, finalizzato ad una valutazione a livello energetico, conservativo e di comfort ambientale;
controllo ambientale a livello illuminotecnico, finalizzato ad una valutazione a livello energetico, conservativo e di comfort ambientale.
I risultati del monitoraggio saranno utilizzati per individuare gli interventi migliorativi da effettuare, secondo una scala di priorità, nelle biblioteche oggetto dell’incarico, nonché costituire un contributo estremamente utile alla bibliografia nell’ambito della conservazione del materiale librario e della gestione dei manufatti di interesse storico-bibliografico-documental
SIMULATIONS OF TURBULENT ISOTHERMAL FREE JETS
No full textIn present work fluid-dynamic behavior of plan isotherm and axisymmetric three-dimensional turbulent air jets in free field has been developed. The study has been led by means of a fluid-dynamic numeric analysis (CFD) with particular attention to discretization type and boundary conditions influence on mathematical solution. Velocity variation along jet axis and on transversal sections has been determined; then results have been compared with data available in literature. Fluid-dynamic jets behavior has been studied with particular attention on entrainment and mutual influence among two or more jets, in accordance with their distance, with the aim of giving useful information about velocity field for ventilation plants project and construction. Mathematical model defined for two-dimensional and axisymmetric three-dimensional problems led us to good results; so in next works the methodology will be extended to three-dimensional phenomena
Selected Papers from the 12th International Conference on Computational Heat and Mass Transfer (ICCHMT2019)
No full textSTUDY OF A MODEL FOR THE EVALUATION OF THE HEAT LOSSES FROM ELECTRIC CABLES BURIED ACCORDING TO THE NORM STANDARD
No full textThe capacity of electrical cables buried in the same cross section depends on the capacity
to dispose of heat into the ground around him. This depends on many factors: soil characteristics,
moisture, installation mode etc. The CEI 20-21 regarding the uses expressions that sometimes are
not very cautious and dimensioning of insufficient capacities for cables. This work has been done a
study of the behavior of underground cable based on using a forecasting model that uses the
techniques of cfd. This model was validated with a physical model in miniature, made from data
collected in situ measurement campaigns carried out in underground conduits in the province of
Foggia (Italy) that allowed the choice of the mesh to get more 'correct solution to of the problem.
Thus it was possible to evaluate the differences with the CEI and attribute the correction factors
that lead to more realistic value
Impact of shortwave multiple reflections in an urban street canyon on building thermal energy demands
No full textThe urban fabric plays a fundamental role in convective and radiative heat exchanges between buildings. The main parameters which influence these heat exchange mechanisms are due to climate conditions such as air temperatures/humidity, wind speed/direction and solar irradiance. These weather data are related on where our cities are located rather than on how they are built. In this work, a building energy simulation tool is exploited to study the impact of multiple shortwave inter-reflections exchanges in an urban environment with the aim of evaluating their influence on the thermal energy demand of a building. These multiple radiative exchanges modify the buildings envelope energy budget influencing space cooling and heating demand. A street canyon model validated in a previous work was used to investigate the effects of the urban radiative trapping. Due to multiple shortwave reflections, the effective solar radiation absorbed by the buildings envelope surfaces is higher than in a street canyon building where only shadowing phenomena due to canyon geometry are considered. A comparison has been performed between these two configurations as a function of several driving parameters such as street canyon aspect ratio, orientation, transparent/opaque surfaces ratio and solar absorption. The goal is to characterize how these parameters influences the inter reflections inside an urban canyon and thus the buildings energy demands. Increases in cooling demand up to 35% and decreases in heating demand up to 7.5% are found
Aflatoxin occurrence in goat milk and supplied concentrate feed in farms of Veneto, Trentino and Friuli Venezia Giulia
Full text linkAflatoxin M1 (AFM1) is a probable human hepatocarcinogen (IARC, monographs on the evaluation of carcinogenic risks to human. Vol. 56, 1993) found in milk of animals that consume feeds contaminated with aflatoxin B1 (AFB1), produced by fungi of genus Aspergillus. There is little information about goat milk: the aim of this study was to
examine the level of contamination of milk, and related concentrate feed, in goat farms of Veneto, Trentino and Friuli Venezia Giulia. In 2005 and 2006, during the lactation period, 79 samples of total daily milk and 125 concentrate feed samples
(principally maize and concentrate feeds), collected in 17 goat farms of Triveneto, were analysed for the content of AFM1 and AFB1 respectively, by HPLC technique. Concerning the milk samples, only one-third of total samples exceed the analytical reliability level (3 ppt), 14 of which
were positioned under the value of 9 ppt and only 1 sample was over the value of 27 ppt.With regard to the feed samples,
the two-thirds of total samples exceed the analytical reliability level (0.1 ppb), 54 of which had a value lower than 1 ppb and only 1 had a value higher than 10 ppb. The relation between levels of aflatoxin in milk and feeds was also considered: there is a significant correlation that confirms the role of feeds in the contamination of milk.
All the samples had values lower than the maximum limit established by Italian law concerning the content of aflatoxins
in milk for human diet and the content of aflatoxin in the concentrates for the goat diet (AFM1: 50 ppt; AFB1: 20 ppb), showing a general situation of absence of risk for animal and human health, with only few cases to keep under control. The results are in accordance with the situation found in other regions of North Italy (Regione Lombardia, 2003-2005), where, also in the dairy cow sector, there was a reduction of aflatoxin contamination risk in 2005 after two years of high levels of contamination of the maize and of the milk
Analisi exergetica per la minimizzazione dell’inquinamento prodotto dall’impianto di climatizzazione di bus turistici
No full text
Raffreddamento dei componenti elettronici per convezione naturale: predizione CFD ed analisi interferomentrica per il dimensionamento di una cavità quadrata
No full textRetrofit Proposals for Energy Efficiency and Thermal Comfort in Historic Public Buildings: The Case of the Engineering Faculty’s Seat of Sapienza University
Full text linkThe building sector greatly contributes to energy consumption and Greenhouse Gas emissions, relating to the whole building life cycle. Boasting a huge building heritage of historical and architectural value, Europe faces challenging retrofit perspectives, as the potential for high energy efficiency has to be exploited while preserving the buildings' original characteristics. The present work aims to feature the influence of a passive strategy on a heritage building in a mild climate. As historical its facade cannot be modified, its large glazing areas involve multiple issues, such as an increase in the heating (QH) and cooling (QC) energy demands and the risk of thermal discomfort. Thus, window replacement was proposed for retrofitting. A dynamic simulation model in TRNSYS was validated with experimental data collected by the continuous monitoring of walls of different thicknesses and orientations. Solutions from replacement with Double Glazing Units (DGUs) with improved thermal insulation, to internal shading activation were applied. All configurations were compared in terms of QH, QC, thermal performance of the building and user comfort (Fanger). Low-e DGU enabled the saving of up to 14% of the annual energy demand, and shading also offered good results in summer, reducing QC by 19%. In summer, DGU involved a maximum PPD reduction of 10 units
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