1,720,959 research outputs found
Energy efficient WWTPs: simulation and validation of a decision support system through modelling
No full textMathematical modelling has been tested as a decision support system to management of a biological WWTP, aimed at optimizing energetic efficiency. A conventional activated sludge plant has been studied and the ASM1 mathematical model has been implemented, calibrated and validated, by using West 2012, DHI software. Optimal operating strategies, under different operating conditions, such as variable influent loading, have been defined. Also, indicators concerning energy efficiency and effluent quality have been defined and quantified
Signal monitoring toward an intelligent and automatic control of wastewater treatment plant
No full textIn small plants typical operating costs for treated water are higher than those of large plants and this is certainly dependent on the relative higher load variations at small plants compared at the larger, but also on the fact the instrumentation installed on the former is minimal. An appropriate low cost equipment could be installed in small - medium plants (data logger stand-alone with suitable sensors) and the data produced used to implement an intelligent control system capable to monitor the processes continuously, analyse the collected time series and classify the various operational states reachable by the plant. Such a system should be able to recognize known situations, extracting features and patterns from the signals, and apply domain knowledge to choose itself the most appropriate control actions, effectively acting as a Decision-Support System (DSS) with Fault Detection and Isolation (FDI) capabilities.
In this paper, the first part of a project where a preliminary analysis of this correlation, comparing trends, range of values and characteristic points, is introduced. The signals used are pH, ORP, DO, measurable by cheap and reliable sensors, which correlation with biological processes is well known in Sequencing Batch Reactor (SBR), but not in Conventional Activated Sludge (CAS) plants
Monitoring denitrification by means of pH and ORP in continuous-flow conventional activated sludge processes
Full text linkIndirect signal analysis (pH, ORP and DO) are often used in monitoring and control of SBRs
(Sequencing Batch Reactors), where operating conditions can be clearly identified during the various
cyclic phases. Only few studies applied this methodology to control continuous flow plants, as it is
much more difficult to identify operating conditions because of continually variable inflow characteristics.
This work applied indirect signal analysis to control pre-denitrification in continuous-flow
activated sludge processes: (i) a laboratory-scale plant, fed with synthetic wastewater, simulating real
municipal wastewater and (ii) a pilot-scale plant, fed with real sewage. Three different ranges of ORP
values identify three operational conditions of the denitrification process. (1) ORP > 0 mV means
that nitrates and/or nitrites are present, possibly due to a low C/N ratio. (2) –50 < ORP < –200 mV is
typical of normal operating conditions, that is with a balanced C/N ratio. (3) ORP < –350 mV means
that oxidized nitrogen load is too low or that C/N exceeds the stoichiometric ratio. The trend of pH,
instead, points out if and how the process is evolving from one to another operating condition. The
correlation between pH and ORP signals (as well as their derivatives) allows to restore normal operating
conditions by acting on the internal recycle flow-rate. Improved denitrification process ensures
lower effluent nitrate concentration, and reduce external carbon dosage to achieve stricter nitrogen
limits
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
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
Analisi di pH, ORP e DO finalizzata all'utilizzo di segnali indiretti per il monitoraggio e il controllo automatico di impianti di depurazione a fanghi attivi
No full textCon il presente lavoro di tesi si è studiata la possibilità di estrarre informazioni sugli andamenti dei processi biologici dall’osservazione dei segnali di pH, potenziale di ossido riduzione (ORP) e ossigeno disciolto (DO) nelle vasche di processo di un impianto a fanghi attivi a flusso continuo (predenitro/nitro) per verificare la possibilità di utilizzare questo tipo di sonde per lo sviluppo di sistemi per il controllo automatico e la gestione intelligente, eventualmente remota, degli impianti di depurazione.
Il lavoro di sperimentazione è stato svolto su un impianto pilota a flusso continuo con schema predenitro – nitro, costruito ed installato presso i laboratori della sede Enea di Bologna (Sezione ACS PROT IDR - Gestione Risorse Idriche). L’obiettivo primario della sperimentazione è stato quello di portare il sistema in uno stato stazionario di equilibrio, così da poter stabilire delle condizioni di funzionamento note e costanti, riscontrabili anche nei segnali di riferimento. Tali condizioni sono state definite prendendo come riferimento un impianto reale noto, funzionante in condizioni di processo costanti e medie, definendo contestualmente test sperimentali che riproducessero condizioni riscontrabili sullo stesso impianto reale. Le condizioni del sistema sono state monitorate costantemente, attraverso il monitoraggio giornaliero dei processi, effettuato con attività di campionamento e di analisi, osservando costantemente i segnali indiretti
Analisi dei processi biologici per la gestione, il controllo e l'automazione degli impianti di depurazione acque reflue
No full textGli impianti di trattamento acque reflue (WWTP, Waste Water Treatment Plant) sono sistemi non lineari, spesso soggetti grandi a perturbazioni in termini di portata e di carico, e risentono dell’incertezza legata alla composizione del refluo in ingresso e delle variazioni giornaliere e stagionali delle condizioni ambientali. Nonostante questo, devono lavorare in continuo, soddisfacendo regolamentazioni sempre più stringenti.
Fino a qualche anno fa l’automazione per gli impianti di depurazione è stata considerata costosa e sono stati spesso trascurati nella fase di progettazione. Tuttavia un adeguato utilizzo degli strumenti offerti dal controllo automatico basato su segnali acquisiti dalle vasche di trattamento (ICA, Instrumentation Control and Automation) può diventare una risorsa economicamente vantaggiosa. I sistemi di controllo richiedono misure affidabili e precise per implementare politiche di controllo efficaci ed adeguate, quali una strumentazione dedicata, oltre che sensori per nutrienti on-line e in-situ. Per impianti di piccole dimensioni (<50.000A.E) il costo dela strumentazione del sistema di controllo può comportare un rapporto costi/benefici sfavorevole.
Lo scopo di questa attività di ricerca è stata ala definizione di una relazione tra i segnali indiretti (pH e ORP) ed i processi biologici negli impianti di depurazione a fanghi attivi a flusso continuo, al fine di verificare se ed in che modo questi segnali possano essere utilizzati per monitorare e controllare i processi in modo economicamente sostenibile.
L’attività di ricerca nasce da una collaborazione tra il Politecnico di Milano, l’ENEA di Bologna e di HERA S.p.A, nell’ambito di un progetto avente come obiettivo l’automazione ed il controllo di impianti di depurazione a fanghi attivi.
In particolare lo studio ha valutato gli effetti di una efficiente strategia di controllo dell’aerazione per la vasca di nitrificazione (controllo a cascata ossigeno disciolto – azoto ammoniacale) e la fattibilità di attuare il controllo del processo biologico di denitrificazione in reattori a flusso continuo mediante l’elaborazione dei segnali indiretti.
Le attività sono state svolte su due impianti pilota a flusso continuo con schema Ludzack-Ettinger modificato (MLE, predenitrificazione-nitrificazione con ricircolo interno), uno a scala di laboratorio installato presso i laboratori dell’ENEA alimentato con refluo sintetico e l’altro in scala pilota, installato presso l’impianto reale di Trebbo di Reno (BO), alimentato con refluo reale.
I risultati di questa ricerca indicano che è possibile acquisire informazioni importanti sul processo di denitrificazione mediante il monitoraggio dei segnali pH e ORP in vasca anossica. In particolare il segnale ORP identifica delle specifiche condizioni operative (es. eccesso di carbonio e carenza di nitrati e viceversa, o l’equilibrio dei due); mentre l’andamento del pH indica la possibile transizione tra due differenti condizioni e il coefficiente di Pearson può essere utilizzato nel monitoraggio della transizione.Wastewater treatment plants are complex systems, where a large amount of information should be known to prevent failures and keep the plant running regularly. Some variables and parameters in wastewater treatment plants (WWTPs) may be conveniently monitored to gather information that helps in monitoring and controlling the bioprocess that occur in the plant. Up to recent years, automation has been considered costly in WWTP design, and it has been often neglected in the initial design of these plants. However, an adequate use of ICA (Instruments, Control and Automation) can make a plant run consistently and economically.
Although process control in SBR plants has been widely studied and implemented based on simple and roust indirect signals such as pH, ORP and DO, the same does not apply for CAS (Conventional Activated Sludge) plants.
The aim of this research is to study the indirect signals (pH and ORP) and biological process performance in continuous-flow activated-sludge plants in order to verify how these signals can be used to monitor and control the biological processes.
Especially this research has evaluated the effects of the implementation of an efficiency control strategy for the aeration system in the nitrification tank (cascade control for dissolved oxygen-ammonia nitrogen). It also studied the feasibility of control strategies implementation based on indirect signals (pH, ORP) for the pre-denitrification tank in conventional activated sludge plant.
The research activities have been carried out on two conventional activated sludge pilot plants based on Ludzack-Ettinger modified scheme (predenitrification-nitrifcation with internal recycle). One of them, the lab-scale, was fed with a synthetic feed and the other one, the pilot scale, installed on Trebbo di Reno (BO) was fed with the real incoming influent.
This study indicates that there is the possibility to achieve important information about the denitrification process by monitoring pH and ORP in the anoxic tank. In particular ORP characterizes typical operational conditions (e.g.: excess carbon and lack of nitrate, or vice versa, or, finally, a balanced ratio of the two), while pH trend indicates possible transitions between two different conditions (e.g. due to variable influent COD/N ratios) and the Pearson’s coefficient shall be used to monitoring the transition.DIPARTIMENTO DI INGEGNERIA CIVILE E AMBIENTALE26CANZIANI, ROBERTOGUADAGNINI, ALBERT
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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