1,720,976 research outputs found
Modello concettuale integrato di sistemi di distribuzione idrica
Get PDFIl comportamento piezometrico di una rete di distribuzione idrica è strettamente interconnesso con la domanda che ad essa si riferisce. La tesi di dottorato si propone di individuare analiticamente il legame tra queste due componenti partendo da un’analisi strutturale della domanda idrica e verificando come questa si ripercuote sul funzionamento della rete. Tale analisi è compiuta a partire dalla disponibilità di un campione di misure acquisite da un distretto idrico dotato di smart-meters che hanno registrato dati orari per una rara estensione spazio-temporale, la quale ha consentito di individuare a scala distrettuale una componente pseudo-deterministica perturbata da una componente stocastica. A seguito di un’analisi degli eventi estremi la componente pseudo-deterministica, legata al fattore di picco dei singoli eventi, è stata associata ad una formulazione capace di attribuire un tempo di ritorno a ciascun evento osservato e classificato come critico per il sistema. Tale formulazione, associata ad un’analisi statistica della componente stocastica, ha consentito di definire un generatore di scenari di domanda costituito da un modello additivo lineare di tipo Monte Carlo in grado di generare sinteticamente numerosi scenari continui, completi e contemporanei utili per l’analisi delle reti. Nota la composizione strutturale della domanda è stato possibile individuare la risposta piezometrica della rete di distribuzione idrica dovuta a ciascuna delle componenti individuate. In particolare, viene dimostrato che la proprietà di autosomiglianza della domanda si trasferisce linearmente sulle portate di tronco e secondo una legge di potenza sui carichi nodali. Noto il carico assunto dal singolo nodo di erogazione in presenza dello scenario medio annuo, è quindi automaticamente noto il carico assunto dallo stesso nodo in presenza di qualsiasi altro scenario di domanda perfettamente correlato con lo scenario medio annuo. Si dimostra inoltre che la perturbazione delle domande dovuta all’aleatorietà del fenomeno si ripercuote sul comportamento pressorio nodale con una perturbazione smorzata rispetto a quella della domanda a causa dell’effetto di filtro compiuto dal dimensionamento e dalla topologia della rete di distribuzione. La rete, tramite le proprie caratteristiche capacitive e la propria topologia, detiene infatti una capacità di dissipazione dell’energia che le consente di redistribuire i flussi al fine di minimizzare le perturbazioni. La dimostrazione analitica di questo fenomeno, contributo innovativo presentato in questa tesi, consente di stimare il valore atteso dal carico nodale in qualunque scenario di domanda stocastico a partire dalla conoscenza del dimensionamento della rete e del carico nodale dovuto allo scenario di domanda medio annuo. Tale formulazione determina numerosi vantaggi in termini computazionali, come la possibilità di considerare come soluzioni iniziali ottimali del sistema risolutivo di tipo iterativo della rete i valori assunti dal carico nodale e dalle portate di tronco sugli scenari deterministici definiti dallo stesso fattore di picco degli scenari analizzati. La scelta di questa soluzione iniziale prossima alla soluzione finale riduce significativamente il tempo di calcolo e l’onere computazionale richiesti ad un problema di dimensionamento o calibrazione. Allo stesso modo, le perdite di carico perturbate, individuate grazie alla teoria proposta in questo lavoro da un’unica equazione funzione del volume complessivamente immesso in rete nell’istante analizzato, possono essere utilizzate per efficientare le procedure di sensor placement, per eseguire un monitoraggio in tempo reale della rete volto all’identificazione di pressioni inattese o per definire un dimensionamento di tipo stocastico che tenga cautelativamente conto dell’aleatorietà del fenomeno
Water demand scaling laws and self-similarity properties of water distribution networks
Get PDFThe design of water distribution networks (WDNs) usually considers deterministic values of nodal water demand, calculated by multiplying the average water demand by an appropriate demand factor, which is the same for all nodes. Obviously, changes in the demand factor produce different, yet perfectly correlated, demand scenarios. Today’s large availability of high-frequency water consumption monitoring allows describing water demand in statistical terms. The traditional deterministic approach, characterized by a perfect correlation between nodal demands, leads to an analytical dependency between the hydraulic heads in each of the nodes and the total flow entering the network. On the other hand, if we consider that the nodal demand is described by marginal probability distributions, differently correlated with each other, this result is still valid, but only for the mean. In this work, several scenarios have been generated through stratified random sampling (Latin hypercube sampling). The nodal water demand is described by Gamma probability distributions whose parameters are related to the type and number of users according to suitable scaling laws, derived from historical data sets. The results were obtained considering different types of users and different network topologies and highlighted the possibility of evaluating the mean function of the nodal hydraulic head vs the total entering flow based on the direct acyclic graph (DAG) of the network. Moreover, the dispersion of the data around the mean function was found to be dependent on the properties of the network: dimension and topological structure
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Machine-Learning Approach for Monitoring Water Distribution Networks (WDNs)
Get PDFThe knowledge of the simultaneous nodal pressure values in a water distribution network (WDN) can favor its correct management, with advantages for both water utilities and end users, and guarantee higher sustainability in the use of the water resource. However, monitoring pressure in all the nodes is not feasible, so it can be useful to develop methods that allow us to estimate the whole pressure field based on data from a limited number of nodes. For this purpose, the work employed an artificial neural network (ANN) as a machine-learning regression algorithm. Uncertainty of water demand is modeled through scaling laws, linking demand statistics to the number of users served by each node. Three groups of demand scenarios are generated by using a Latin Hypercube Random Sampling with three different cross-correlations matrices of the nodal demands. Each of the corresponding groups of pressure scenarios is employed for the training of an ANN, whose performance parameter is preliminarily used to solve the sampling design for the WDN. Most of the so-derived monitoring nodes coincide in the three cases. The performance of each ANN appears to be strongly influenced by cross-correlation values, with the best results provided by the ANN relating to the most correlated demands
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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