Novel Moving Average Filter for Detecting rms Voltage Step Changes in Triggerless PQ Data

The voluminous amount of raw waveform data recorded by triggerless power quality monitors contain conspicuous and inconspicuous disturbance events. Data reduction and detection techniques are needed to efficiently extract useful information hidden in the raw data and identify power quality disturbances. The overall objective of this study is to use step changes in the rms voltage profile as an alternative triggering feature for automatically detecting switching events. The full characterization of the event is based on processing a small portion of the voltage waveform selected around the detected rms voltage step change. A filtering method is proposed to smooth out rapid fluctuations in the rms voltage profile during steady-state operation, while preserving the sharp edges caused by rms voltage step changes. Once the rms voltage profile has been filtered, adaptive limits based on the median absolute deviation are computed for detecting rms voltage step changes. The effectiveness of the proposed technique is evaluated using triggerless voltage waveforms to detect capacitor switching events. The use of the filtered rms voltage profile allows accurate detection of capacitor energizing and de-energizing events, while more than 50% of the detections in the unfiltered profile correspond to false-positive

The university in Italy : historical background and changing trends

Traces the history of higher education in Italy. Discusses the nature and function of the Italian university; changes in Italy's system of higher education over the years; the issue of academic autonomy in Italy; and reform in Italian universities over the next few years (going corporate and walking the tightrope between autonomy and national guidelines).peer-reviewe

La contabilità a partita doppia e la "razionalità " economica occidentale: Max Weber e Jack Goody

In una prospettiva più sequenziale di quanto a volte non si sia immaginato, già nei suoi scritti sull'etica protestante, Weber aveva osservato che con i calvinisti inglesi "la vecchia immagine medievale (già presente nell'antichità) della tenuta dei conti da parte di Dio, arrivava . . . fino al caratteristico cattivo gusto di paragonare il rapporto del peccatore con Dio al rapporto di un cliente con lo 'shopkeeper', il padrone di una bottega: una volta che uno si è indebitato, potrà con l'importo di tutti i suoi guadagni, pagare, al massimo, gli interessi decorrenti, ma mai la somma principale dovuta". Stabilita questa rapida messa a fuoco, sembra di poter affermare che la problematica impostata da Goody intorno alla nozione di "razionalità occidentale" a suo dire rintracciabile negli scritti weberiani, appare interamente fondata tanto su una lettura affrettata del magma testuale weberiano quanto su una concettualizzazione di "razionalità" economica ben difficile, in se stessa, da accettare. Più dell'affermazione del fatto che il nesso fra religione ed affari non fu una esclusività dell'Occidente europeo, e che, per esempio, lo si rintraccia benissimo anche nell'Egitto medievale, sembrerebbe di maggior significato l'individuazione dei percorsi specificamente storici, dei vocabolari tecnici in grado di restituirei spiegandocela, l'interazione rituale e politico-religiosa, dunque culturalmente particolare, fra persone e istituzioni europee o non europee, impegnate dall'azione economica o dalla previsione finanziaria o dalla memorizzazione contabile

Wind Energy Conversion Systems based on DFIG Technology used as Active Filters: Steady-State and Transient Analysis

This thesis deals with the performance of a Wind Energy Conversion System operating as a power generator and Active Filter simultaneously. As a power generator, the Wind Energy Conversion System converts wind energy into electric energy; as an Active Filter, it sinks the harmonic currents injected by Non-Linear Loads connected at the same feeder. Three control systems are developed to ensure the described operation; a specific study regarding the compensation of the triplen harmonics is carried out; Doubly-Fed Induction Generator derating is defined; and an engineering economic analysis is performed to determine the profitability of the proposed operation. The Wind Energy Conversion System performance as generator and Active Filter has been studied for steady-state analysis, fast transients and low transients. It is concluded that the proposed control systems allow operating the Wind Energy Conversion System as power generator and harmonic compensator both during steady state and transient operation; the described operation causes power loss increase and voltage distortion that determine the choice of the component and require system derating

Modelling Renewable Energy Sources for Harmonic Assessments in DIgSILENT PowerFactory: Comparison of Different Approaches

With the increasing number of Renewable Energy Sources connected to the power grid, the impact on system operation is becoming more evident. To assess this impact, accurate computer models are required for both the power system and the devices connected to it. Various types of system integration studies need to be performed in order to study both steady-state and abnormal operation. Among the steady-state analyses, power quality studies assess the impact of Renewable Energy Sources on parameters such as voltage levels and harmonic content. Harmonic studies are gaining more attention because of the nature of renewable energy sources which are mainly connected to the power grid through electronic power converters, thus producing undesirable harmonics. This paper analyses various settings, solvers and harmonic source models in a commercial software – DIgSILENT PowerFactory – to ensure accurate calculation and correct interpretation of harmonic assessment. A simple model comprising seven harmonic devices is used for the analysis of various case studies. Their results are then compared with the standard IEC model and recommendations are proposed on how to appropriately model the RESs depending on the specific application considered

Flame intensity analysis for hot molten metal pouring in the steel industry by applying image segmentation

Pouring large quantities of hot metal (HM) can release substantial amounts of flame. This problem is frequently encountered within the Basis Oxygen Furnace (BOF) steelmaking process where large quantities of HM (frequently exceeding 300 t) are poured into the converter vessels. The HM is contained in specially designed ladles and poured using overhead girder cranes. Excess release of flame may damage surrounding components such as crane ropes and consequently reduce their lifecycle. Therefore, limiting the release of flame during pouring, allows extending the lifetime of the components located in proximity of the ladle. The scope of this paper is to characterise flame generation during different pouring operations at a BOF steelmaking plant and to relate the amount of flame generated to process factors. Due to the complexity of the process under investigation, this paper does not aim to eliminate flame generation, but rather to identify approaches to its mitigation. The proposed approach utilises a standard CCTV camera to record videos of pours. An image segmentation analysis is then performed, where the flame is separated from the background image using pixel information in the CIE L*a*b* colour space. For each frame, flame intensity is then calculated. This process is partially automated for each video making use of MATLAB. A total of 169 videos are analysed and the pours that cause higher flame intensity are identified. In the last steps of the analysis, the process factors with the most significant impact on the flame release are identified and mitigating solutions are proposed

Dispaches from the old man overseas: Ernest Hemingway's journalism

El objetivo de esta tesis es explorar cómo se conectan los escritos periodísticos y literarios de Hemingway arrojando luz sobre su carrera como periodista, menos conocida que su carrera de escritor. Nuestra principal pregunta de investigación es saber si es posible establecer una conexión entre la evolución del periodismo de Hemingway con su literatura. La metodología utilizada fue comparar las tres fases literarias de Hemingway con su producción para la prensa escrita. Después de analizar la obra periodística y literaria de Hemingway, observamos que su ficción y su producción periodística siguen un camino muy similar en cuanto a la elección de los temas y en el estilo, y son fuertemente complementarios en términos de contenido. En términos de elección de tópicos, Hemingway puede ser considerado un autor temático porque tiene intereses en asuntos específicos. En su actividad periodística, Hemingway escribió mayoritariamente sobre los temas que también aparecían en su literatura, como la guerra o los deportes. En cuanto al estilo de escritura, se ha podido verificar que tanto los textos periodísticos como los literarios pasaron por procesos parecidos. En la década de 1920, podemos ver a un joven Hemingway en sus inicios, con ojo para lo novedoso. Eso se refleja en frases cortas y diálogos agudos. No es de extrañar que en su literatura los protagonistas de Hemingway fueran héroes en busca de iniciación, desarrollando el papel de un iniciante ávido de aprender. En su periodismo, esta dinámica también aparecía a menudo, como la transcripción de diálogos con un viejo pescador que le enseña cómo pescar en los arroyos. Finalmente, en cuanto al contenido, Hemingway desarrolla algunos de los temas recurrentes en el periodismo y la literatura de manera que se complementan entre sí. El libro The Sun Also Rises ofrece un retrato convincente, elocuente y certero del desengaño general de la llamada Generación Perdida, mientras en su periodismo este retrato se queda más enfocado en los aspectos prácticos como sobre vivir en Paris con poco dinero o en los eventos clave del mundo posguerra. El periodismo constituye, por lo tanto, otra herramienta importante para analizar la vida y la obra de Ernest Hemingway en perspectiva. La prensa se convirtió en un canal más para que el escritor expresara sus puntos de vista y desarrollara un estilo de escritura por el cual se hizo famoso en todo el mundo

Killing by lung cancer or by diabetes? The trade-off between smoking and obesity

As the prevalence of smoking has decreased to below 20%, health practitioners interest has shifted towards the prevalence of obesity, and reducing it is one of the major health challenges in decades to come. In this paper we study the impact that the final product of the anti-smoking campaign, that is, smokers quitting the habit, had on average weight in the population. To these ends, we use data from the Behavioral Risk Factors Surveillance System, a large series of independent representative cross-sectional surveys. We construct a synthetic panel that allows us to control for unobserved heterogeneity and we exploit the exogenous changes in taxes and regulations to instrument the endogenous decision to give up the habit of smoking. Our estimates, are very close to estimates issued in the ’90s by the US Department of Health, and indicate that a 10% decrease in the incidence of smoking leads to an average weight increase of 2.2 to 3 pounds, depending on choice of specification. In addition, we find evidence that the effect overshoots in the short run, although a significant part remains even after two years. However, when we split the sample between men and women, we only find a significant effect for men. Finally, the implicit elasticity of quitting smoking to the probability of becoming obese is calculated at 0.58. This implies that the net benefit from reducing the incidence of smoking by 1% is positive even though the cost to society is $0.6 billions.