196,160 research outputs found
Né codice, né amministrazione: considerazioni su un paradosso inglese, in M. Basso, M. Farnesi Camellone, C. Mogno (a cura di), La società e le sue discipline. Scritti in onore di Mario Piccinini, Padova University Press 2024.
No full textImplementation, Parameters Calibration and Field Validation of a Closed Loop Performance Monitoring System
No full textThe paper illustrates the main features of a performance monitoring system which supervises more than 1200 loops of refinery plants. The system analyses data recorded by the DCS during routine operations and originates verdicts about the performance of control loops; also, indications of low performance causes and different strategies to adopt (retuning, valve maintenance, upstream actions) are given. First, the architecture of the system is illustrated, and characteristics of modules which accomplish different tasks of data acquisition and transfer, system configuration and priority assignment, performance analysis and verdicts emission, database query and operator support, are described. A synthesis of main techniques adopted in the system for stiction detection, process identification and performance evaluation, is also reported. The procedure for calibration of threshold values of key parameters, in order to match verdicts issued automatically by the system with operators evaluations and to avoid false alarms, is also discussed. Examples of results achieved from field validation are then presented, with illustration of loop performance before and after actions suggested by the monitoring system
Coscienza e religione in Hobbes: una prospettiva etico-politica
No full textLa ricerca intende approfondire, in primo luogo, il controverso rapporto di Thomas Hobbes (1588-1679) con la religione. Sulla base di un'analisi della nozione hobbesiana di coscienza, fortemente correlata al tema della religione, il lavoro mette quindi in luce cosa può suggerire, in prospettiva, una rilettura del pensiero hobbesiano e della sua concezione religiosa - e in particolare della sua descrizione di coscienza - in merito a questioni che impregnano la nostra quotidianità, interrogando gli esseri umani sul rapporto tra religione e vita pubblica. Analizzando poi il transito di queste tematiche nell'etica contemporanea, la ricerca prova a enucleare alcuni punti di contatto su cui poter sviluppare un confronto sensato e fruttuoso tra il pensiero di un grande classico della modernità qual è Hobbes e le preoccupazioni del nostro tempo, riguardo a temi come la vita, il fine vita e la sessualità, che inevitabilmente coinvolgono il ruolo della coscienza nello spazio pubblico
Key Parameters Calibration and Benefits Evaluation of a Closed Loop Performance Monitoring System.
No full textThe paper presents results from field validation of a closed loop performance monitoring system installed on several units of a refinery plant. The system supervises more than 1200 base control loops and evaluates performance periodically, after scheduled data acquisitions followed by off-line analysis. The first point taken into account is a comparison between verdicts issued by the system and indications by control operators: the large number of issued verdicts indicating scarce performance, but considered still acceptable by operators, results practically in False Alarm and forced to revisit the criterion adopted to classify a response as excessively oscillatory. New threshold values for the widely used Hägglund criterion (1995) were found and similar criteria were proposed and compared in order to match operators practical indications. The efficiency of criteria and threshold values depend on the type of loop (i.e. flow, pressure, level or temperature). The second point examined concerns validation of valve stiction diagnosis: indications from the monitoring systems are compared with evidence before and after plant shut down. Results confirm that oscillations in valves indicated as sticky disappeared after the operation, while many valves which underwent the maintenance procedure on the basis of a time schedule did not require it. Therefore, a systematic application of diagnostics tools for maintenance scheduling would be beneficial in order to focus on real needs and avoid unnecessary revision cost
Soft-Switching Power Converters for Efficient Grid Applications
No full textNowadays, the Modular Multilevel Converter represents an important solution for grid applications, as it can easily extend the output voltage range, as required for instance in high voltage applications. The present paper studies the generalization of such a converter to a resonant version, not already used in high power applications, analyzing how it could perform in grid applications
La sovranità scomposta. Sull'attualità del Leviatano
No full textUna lunga tradizione interpretativa considera il Leviatano di Thomas Hobbes il testo in cui
ha preso forma il dispositivo logico-concettuale con cui la modernità ha pensato la politica.
I tre studi qui contenuti “scompongono” la teoria hobbesiana per metterne in evidenza alcune
aporie che manifestano oggi, nell’apparente crisi della sovranità statale, una cogente attualità.
Nella dottrina di Hobbes l’individuo, presentato come presupposto della sovranità, è anche
prodotto di una biopolitica che della sovranità è correlato essenziale; la natura umana è
segnata dalla scissione tra bisogno di riconoscimento e affermazione di quella individualità
irrelata che è premessa necessaria della rappresentanza politica; la condizione umana viene
sospesa in un presente astorico pensato come intrascendibile, per eliminare ogni pulsione
al mutamento. Senza voler risolvere le tensioni tra sovranità e biopolitica, riconoscimento e
rappresentanza, eternità e mutamento, questo libro mostra la centralità di queste aporie tanto
nel momento di affermazione della scienza politica moderna, quanto negli odierni processi
di soggettivazione
Solid-state transformers in locomotives fed through AC lines: A review and future developments
No full textOne of the most important innovation expectation in railway electrical equipment is the replacement of the on-board transformer with a high power converter. Since the transformer operates at line-frequency (i.e., 50 Hz or 16 2/3 Hz), it represents a critical component from weight point of view and, moreover, it is characterized by quite poor efficiency. High power converters for this application are characterized by a medium frequency inductive coupling and are commonly referred as Power Electronic Transformers (PET), Medium Frequency Topologies or Solid-State Transformers (SST). Many studies were carried out and various prototypes were realized until now, however, the realization of such a system has some difficulties, mainly related to the high input voltage (i.e., 25 kV for 50 Hz lines and 15 kV for 16 2/3 Hz lines) and the limited performance of available power electronic switches. The aim of this study is to present a survey on the main solutions proposed in the technical literature and, analyzing pros and cons of these studies, to introduce new possible circuit topologies for this application
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