102,117 research outputs found
Kinetics of heavy metals leaching from contaminated soils in metallurgical plants
No full textKinetics of Heavy Metals Leaching from Contaminated Soils in Metallurgical Plants
Paolo Desogus , Pier Paolo Manca , Giampaolo Orrù
Abstract
The work aims to highlight the main parameters that affect the efficiency of the process of leaching of heavy metals from a natural soil taken from inside a metallurgical plant. The studies were conducted by laboratory tests and the results will allow identifying the fundamental choices for the applications of the technique of in situ soil flushing.
The tested soil samples were mainly made by fine silica sand, with medium density. Their pollution was caused by waste of the metallurgy of lead and zinc released into the soil to transport by rainwater. Their depth ranges from 1 to 2 meters from ground the level from which they are separated by artificial strata composed of soil mixed with metallurgical solid waste. The layer of soil tested hosts an aquifer with a slow permeability, variable depth generally higher than 10m contaminated by heavy metals.
The leaching experiments were conducted through the batch and column tests. Acid solutions (acetic. nitric. hydrochloric and sulfuric) were used as extracting agents. During the leaching tests, concentrations of analytics Zn, Pb, Cd, Cu, Mn and Al were verified.
The results highlighted two aspects: (a) the conditions for which they get the best efficiency of leaching and (b) the laws of statistical correlation that describe the kinetics of reaction. The calculations performed have shown that the most efficient leaching agent was the CH3COOH and mainly the flow velocity of the leaching solution conditions the reaction kinetics in the column
Accuracy assessment of analysis of a free-fall gravimeter data
No full textThe measurement of the local acceleration due to gravity is based on the orbit reconstruction of the free fall in vacuo of a test mass [1]. In the set-up of the Istituto di Metrologia “G. Colonnetti” the test mass, which embeds a retroreflector, is tossed up and its ascent and descent are tracked and timed by a laser interferometer and a rubidium clock. The data actually supplied by the instrument is time versus fixed fringe number and the gravity value is obtained by fitting time-height pairs to a parabolic motion model. In order to overcome the limits of this procedure, to assess data processing, and to achieve full information about the test mass orbit, traveling interference fringes have been digitized by means of a fast Analog to Digital (AD) converter with 8-bit resolution and the entire interferometer signal is recorded for subsequent analysis [2]. The present article deals with the reconstruction of the test mass orbit and error propagation through gravity calculation. Owing to timing errors and noise correlation, the uncertainty resulting from conventional error propagation through least squares calculation is smaller than the actual one. To avoid underestimation, noise characterization and modeling was carried out and asymptotic formulae expressing the measurement uncertainty were obtained and verified against experimental data
Stone in the city. Extraction sites and spoliation of stone materials in the city of Nora (South -West Sardinia)
No full textIn this study we intend to read the "backstage" of the urban scene in the archaeological city of Nora, in the southwestern coasts of Sardinia, with the aim of identifying main urban processes that take into account the ancient supply and circulation of building materials essential for the urban formation. The intention is to create a different point of view in order to get a comprehensive picture of the urban form and characteristics, and also to define the social, cultural and economic context which led to the birth and development of the local building language, and to understand the relationship between the city and geo-resources in the surrounding region.In particular, the work intends to focus to the historical extraction sites and to the movement of construction materials, without neglecting the spoliation of monuments, to identify the plots between geology and urban structure, also in order to evidence as the historic cities possessed an unconscious smart approach. The choice of the city of Nora is not accidental; in fact, different kinds of local stones are undoubtedly the most widely used building materials within the city. The choice, optimization and use in buildings and urban infrastructures was masterly performed, without interruptions, from the late sixth century B.C. until at least the fourth or fifth century A.D. Already during his trip to Sardinia (1857) Alberto Ferrero La Marmora recognized in the peninsula of Is Fradis Minoris, close to the city ruins, traces of quarrying recorded in "quaternary grès" stone, widely used in buildings of Nora.. It will then Gennaro Pesce, who through his works (1957-1971) showed great interest in the main building materials and construction techniques used in Nora, providing insights on the architectural aspects, and then making a specific focus on building materials, wall structures and architectural taste in the city during Roman imperial age (IVth period of Nora). In particular, G. Pesce (1957) provided an essential list of stone materials mostfrequently used in Nora for buildings, which are: 1) carbonatic sandstone (Quaternary),2) fine-grained sandstone (Tertiary), 3) andesite (Tertiary), 4) limestone (Miocene); 5) pyroclastite (Miocene). The contribution wants to investigate the correlations between urban building and the aforesaid stone materials, whose extraction was proximal, and whose masterful use has allowed the construction of the city of Nora
Il metodo balistico come metodo primario per la misura assoluta dell'accelerazione di gravità: la sua realizzazione in Italia
No full textLo spunto per questo articolo deriva da una recente proposta della prima riunione congiunta del Gruppo di Lavoro sulla Gravimetria (WGG) del Comitato Consultivo per la Masse e Grandezze Relative (CCM) del Comité International des Poids et Mesures (CIPM) e dello Gruppo di Studio sui Confronti dei Gravimetri Assoluti (SGCAG) della Sotto-Commissione Gravimetria e Reti Gravimetriche della commissione Campo Gravitazionale della International Association of Geodesy (IAG) tenutasi a maggio 2004 presso il BIPM durante la quale si è riconosciuto il metodo balistico assoluto di misura dell’accelerazione di gravità come metodo primario.
Facendo un passo indietro, possiamo affermare che la misura assoluta dell’accelerazione di gravità, g, è concettualmente semplice. Tuttavia, la misura a livelli di incertezza relativa di qualche parte in 10-9 della caduta libera dei gravi dovuta a g è tecnologicamente una sfida che dura ormai da parecchi decenni.
Un gravimetro assoluto che utilizza il metodo balistico per la misura assoluta di g è essenzialmente un interferometro ottico laser che misura l’accelerazione di un grave su cui è montato un retroriflettore durante il suo volo di caduta libera in vuoto. La misura si riferisce direttamente ai campioni atomici di lunghezza e del tempo, tramite un laser He-Ne stabilizzato e ad un orologio al rubidio. L’accelerazione g può essere misurata direttamente durante la caduta del grave misurando l’intervallo di tempo relativo per il cambiamento di velocità (accelerazione).
All’Istituto di Metrologia “G. Colonnetti” del CNR è stato realizzato in collaborazione con il Bureau International des Poids et Mesures (BIPM), alla fine degli anni ’70 del secolo scorso, il primo gravimetro assoluto trasportabile che ha permesso di migliorare la rete gravimetrica italiana e numerose altre reti gravimetriche in Europa e nel mondo. Esso ha partecipato a tutti i confronti internazionali organizzati dal BIPM e parteciperà anche al prossimo confronto in autunno 2005 organizzato sempre dal BIPM forse con la valenza di confronto chiave del CCM, i cui risultati saranno pubblicati nel BIPM key comparison database come appendice B del Mutual Recognition Arrangement (MRA)
Struttura e architettura nella scuola italiana di ingegneria. il “ridisegno ricostruttivo” e la stampa 3d come strumenti di conoscenza
No full textHow did the architects and their many collaborations with the engineers contribute to
the history of Italian structural engineering in the second half of the 20th century? How did they
participate in defining the identity of the Italian School of Engineering? Reconstructing the history
of Italian structural engineering, it turns out that there is a "story within the history". We talk
about the story of two generations of engineers and architects working together, while
international fame of Italian School of engineering spread worldwide and the great "made in
Italy" structures become an icon in the world.This contribution faces the subject through the story of some material investigations conducted on a selection of significant "structural architectures",
carried out between 1945 and 1980, but especially through the evolution of the pioneering tools of
investigation introduced by Sergio Poretti for the study of 20th century architecture: the "reconstructive
redrawing" - which from the axonometric cross-section, made with the 2D Cad, developed
it selfs in the 3D virtual model and in 3D printed models, embodies a fundamental tool of
knowledge for the analysis of the relationship between form and structure. The contribution is
part of the SIXXI project (ERC Advanced Grant, PI Sergio Poretti, Tullia Iori - www.sixxi.eu),
within the SIXXI3DLab
Absolute measurements of the acceleration due to gravity in Santangelo Romano, Palestrina and Castel Gandolfo (Italy)
No full textThe work hereafter described was carried out on November 14-19, 2005 by the Istituto di Metrologia "G. Colonnetti" (IMGC) of the National Research Council (CNR) for the Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Centro Nazionale Terremoti and Osservatorio Vesuviano.
The experimental results of absolute measurements of the acceleration due to gravity carried out at Santangelo Romano, Palestrina and Castel Gandolfo are reported.
Gravity measurements were performed with the new transportable absolute gravimeter IMGC-02
Approaches of circular economy applied to stadiums: from the policies of stripping old buildings to the demolition with recovery of fractions. the case of Cagliari stadium (Italy)
No full textLa pratica dello spoglio dei monumenti ha sempre consentito l’ottimizzazione dei processi di edificazione, spesso scaturita dal disconoscimento delle politiche precedenti. Lo spoglio nel ‘600 con Papa Gregorio Magno divenne una pratica sistematica in favore delle chiese cristiane: significativo è stato il prelievo proveniente dall'anfiteatro Flavio (Colosseo). Simili strutture hanno avuto lo stesso destino, quali gli anfiteatri di Aquileia, Tivoli, Cagliari e Catania. Lo spoglio nel tempo si affievolisce per effetto della graduale conservazione del patrimonio urbano, secondo i principi del collezionismo. L’attenzione al patrimonio storico culturale diventa sempre più forte: conservazione e cura dei monumenti, se da una parte preservano la storia attraverso le sue architetture, dall'altra parte, fanno perdere progressivamente la storica pratica dello spoglio, con particolare riferimento alla pietra. Sino alla fine del ‘moderno’, si procede alla progettazione e costruzione secondo i principi fordisti, diversamente dal ‘contemporaneo’, con una nuova attenzione riferita alla sostenibilità ambientale. Le nuove forma della città pubblica degli stadi e delle arene rappresentano un banco di prova per reinterpretare lo spoglio nella contemporaneità, attraverso demolizioni selettive e recupero di materiali, come il calcestruzzo. Ne sono esempio gli impianti sportivi dei Winter Olympic Games di Torino (2006), lo stadio di London Olimpics (2012), le strutture per World Cup 2018 (Russia). In questa ampia letteratura della nuova economia circolare si colloca il Progetto MEISAR (2014-2020) , che, abbinato al nuovo progetto selezionato per il Nuovo stadio di Cagliari, intende fornire il supporto tecnico scientifico alle aziende che intendano riutilizzare il calcestruzzo come materia grezza e di seconda mano per le nuove costruzioni
Absolute Measurements of the Free-Fall Acceleration g in Santangelo Romano Palestrina and Castel Gandolfo (Italy)
No full textThe work hereafter described was carried out on May 23-30, 2007 by the Istituto Nazionale di Ricerca Metrologica (INRIM) for the Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Centro Nazionale Terremoti and Osservatorio Vesuviano. The experimental results of absolute measurements of the free-fall acceleration g carried out at Santangelo Romano, Palestrina and Castel Gandolfo are reported. Gravity measurements were performed with the new transportable absolute gravimeter IMGC-02
Absolute measurements of the free fall acceleration g in Pantelleria (Italy)
No full textThe work hereafter described was carried out on June 23-36, 2007 by the Istituto Nazionale di Ricerca Metrologica (INRIM) for the Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Centro Nazionale Terremoti and Osservatorio Vesuviano.
The experimental results of absolute measurements of the free-fall acceleration g carried out in Pantelleria are reported.
Gravity measurements were performed with the new transportable absolute gravimeter IMGC-02
Absolute measurements of the free-fall acceleration g in the Republic of Panama
No full textThe work hereafter described was carried out on January and February 2008 by the Istituto Nazionale di Ricerca Metrologica (INRIM) of Turin (Italy) in the framework of a cooperation with the Centro Nacional de Metrologia de Panama (CENAMEP AIP) and the Istituto Geográfico Nacional “Tommy Guardia” (IGNTG).
The project consists of the measurements of the free-fall acceleration g in twelve sites in the Republic of Panama.
Gravity measurements were performed with the transportable absolute gravimeter IMGC-02
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