1,721,227 research outputs found
Two-particle scattering amplitude in gauge ISO(2,1) quantum gravity
No full textThe gauge ISO(2, 1) interpretation of quantum gravity in 2 + 1
dimensions is considered. The structure of the braid group constraints
to be imposed on the many particle states is found. The exact
expression of the most general scattering amplitude for two spinless
particles is derived
Modeling of domestic wastewaters in sewer networks
No full textWastewater treatment plants are designed to work effectively in a certain range of operating conditions, in relation to the values of flow rate, characteristics of the sewage, concentrations of constituents and load values. The standard design approach is based essentially on the assumption of steady conditions and the estimate of the wastewater conveyed to the plant in different scenarios (daily peak and night time minimum in dry weather conditions; total maximum flow rate during wet weather).
The flow rates and pollutant load are however magnitudes that vary in time and space. The need therefore arises to modify the design procedures currently in use, abandoning the steady condition assumption and taking a dynamic approach. Knowledge of the variability of the quantitative and qualitative characteristics of civil wastewater are of decisive importance when locating and dimensioning the spillways and the pumping stations upstream of the treatment plants.
The time diagram of the concentrations arriving at the treatment plant could also make it possible to opti-mise its management and obtain a better estimate of the equalization volumes.
The article presents a model capable of characterising, in dry weather, the flow rate diagrams and pollutant loads in the sewer networks starting with the use of the main residential appliances (WC, washbasin, sink, shower, washing machine and dishwasher).
Flow into the sewer is the result of an almost random use of domestic devices, each with its own character-istics and frequency of use connected to the particular time of day. These flows are intermittent and are characterised by a relatively short duration by which it is possible to interpret the habitual use of domestic devices in the residential units by the users (Butler et al 1995, 1996).
For domestic devices the parameters average daily frequency of use, start time, average duration of use and volume discharged are estimated using a probabilistic process by estimating the standard deviation from the average value considering a normal distribution (Butler & Graham 1995). This assumption makes it possible to take account of the habits, lifestyles and different needs of the users which can induce consid-erable variability in the types and frequency of use.
The same approach was used to characterise the inputs of pollutants arising from the use of residential devices. The COD (Chemical Oxygen Demand) was considered as a pollution parameter of the wastewaters, fixing an average daily input per capita of 120 gCOD/AE/d, for all the discharges. The per-centage values, on a daily average basis, of the individual devices were determined by referring to studies found in literature (Butler et al., 1995; Friedler and Butler, 1996; Almeida et al., 1999).
The problems related to the lamination and equalisation of the hydraulic and pollutant loads due to the transfer of the wastewater into the sewer network were analysed. In the model used it was assumed that a generic sewer pipe behaves as if it were a continuous reactor with perfect mixing (CFSTR, Continuous-Flow Stirred-Tank Reactor), as developed also by Nielsen et al. (1992).
In this first phase the model, applied to a single section of sewers with a limited number of users, seemed to represent a usable instrument at the design stage and in the management of an entire sewer net-work/treatment plant.
The model proposed, applied previously for characterising the domestic water demand, was applied successfully for the first time for the distribution network of the municipality of Sparanise (Lombardi et al., 2018)
Sul controllo del trasporto solido in fognatura
No full textNell’analisi del complesso ed articolato processo legato al trattamento ed allo scarico delle acque pluviali si colloca lo studio della capacità di trasporto di materiale solido da parte della corrente idrica in una rete fognaria. Il fenomeno è in corso di studio sul bacino sperimentale della Cesarina sito nel Comune di Roma in destra idraulica del fiume Aniene. Il bacino, di estensione complessiva di circa 2015 ettari, è drenato da una fognatura mista caratterizzata da collettori ovoidali e scatolari di grandi dimensioni e debole pendenza. L’attività sperimentale in corso è rivolta sia a localizzare, caratterizzare a livello quali – quantitativo tali depositi sia ad individuare un modello del trasporto solido che consenta di localizzare i tronchi ad elevata probabilità di deposito e di valutare l’ordine di grandezza dei volumi depositati. Nel presente lavoro si mettono a confronto i risultati del modello sviluppato dal gruppo di ricerca dell’Università di Roma Tor Vergata (UTV) con quello proposto in letteratura da Schlutter (1999) tarati sulla rete in esame evidenziandone le principali differenze in termini computazionali e gestionali
I consumi idropotabili
Full text linkLa conoscenza e la caratterizzazione dei consumi idropotabili assumono oggi una sempre maggiore importanza strategica nella gestione di una rete di distribuzione idrica, in attuazione delle disposizioni della legge 36/94 e successive integrazioni, volte al ri-sparmio della risorsa, alla garanzia del soddisfacimento dei livelli minimi di servizio ed al raggiungimento degli obbiettivi di efficacia, efficienza ed economicità. Nella nota è presentato un modello di analisi dei consumi registrati in alcuni comuni italiani che con-sente sia di quantificarne i valori, sia di caratterizzarne la variabilità nella giornata con parametri di validità territoriale. Il modello di analisi è in grado descrivere in modo compatto il livello di servizio richiesto dall’utenza e costituisce un utile strumento per un’agevole attività di gestione delle reti di distribuzione così come richiesto dalla vigen-te normativa. La procedura di analisi seguita, con il monitoraggio continuo della risorsa distribuita, contribuisce all’interpretazione del diagramma tempo – portata registrato in punti significativi della rete. La lettura frazionata del diagramma consente l’individuazione del consumo domestico e la sua scomposizione nelle varie componenti con parametri che sembrano caratterizzare i diversi ambiti territoriali
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Problematiche relative all'impatto allo scarico delle acque pluviali: il modello U.T.V.
No full textLo studio delle problematiche connesse al trasporto solido nel complesso meccanismo di intercettazione superficiale dei deflussi, del loro trasporto nelle reti fognarie e di recapito nei corpi idrici recettori, ha consentito di definire nuovi strumenti per una più corretta manutenzione e gestione del sistema di drenaggio urbano.
Nella presente nota si riportano i risultati di due ricerche sperimentali sviluppate negli ultimi anni su alcuni bacini del comune di Roma tese al controllo dell’interrimento delle caditoie pluviali ed alla caratterizzazione delle onde di carico nei collettori fognari durante un evento di piena
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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