1,720,963 research outputs found
Check and forecasting of railway traffic regularity by a PETRI Nets based simulation model // Verifica e previsione della regolarità dei traffico ferroviario con un modello di simulazione basato sulle Reti di PETRI
No full textThe article describes the main features of a railway operation simulation model. The model simulates the operation of the elementary devices composing the railway traffic management systems by describing their logical steps sequence by using the graphic formalism of extended and colored " PETRI Nets. The model may be applied in railway traffic regularity studies as well as a decision support tool for the planning of new or upgraded lines and their timetable or for delays minimization in traffic management by its automatic trains overcome functionality
Wideband measurement of dielectric properties of powder materials. Developing an experimental set-up
No full textKnowledge of dielectric properties of materials is at the basis of the application of microwaves as non-destructive and non-invasive tools for quality evaluation of foods. In this contribution, the development of an experimental framework to characterize on a wide frequency range dielectric properties of powder food is proposed. The used methodologies include the open-ended coaxial probe technique and a waveguide system, the former being inherently a wideband technique but suffering from the typology of material under test, the latter being a medium-band technique. Examples of measured materials are reported, with particular reference to the measurement of sugar
Technical-economical analysis of cold-ironing. Case study of Venice cruise terminal
Full text linkCold-ironing is the practice that enables to power commercial ships by a link to fixed electricity network, in order to reduce pollutant emissions in the port areas caused by marine fuels in auxiliaries engines feeding on board installations during ships stops at quays. The present paper aims to provide an overview of the most important technical and functional features of the concerned ships power systems and to analyze the technical, economic and financial feasibility of this system. In the first part the main technical-constructive elements for the application of Cold-ironing to different types of ship (such as voltage, frequency, power supply and power demand on the quay) are analyzed. The variety of functional situations does not allow to establish general constructive solutions since the cold-ironing system is depending both on the operational mode and the layout of each terminal. In the second part of the paper it has been analyzed the case study of the cruise terminal in Venice (VTP Spa Venice Passenger Terminal) with the aim of verifying the feasibility of a cold-ironing system for power supply of cruise ships on quays. The analysis was based on ships timetable for the year 2012, which includes the arrivals and the departures of 86 different ships with a global volume of 570 movements. Starting from data on dwell times, following the guidelines of the MEET methodology for estimating emission factors [3] it has been estimated pollutant emissions (nitrogen oxide NOx, sulfur oxides SOx, volatile organic compounds VOC, particulates PM, carbon monoxide CO) as a basis to calculate externalities to be considered for the Cost-Benefit Analysis (CBA). Based on a probabilistic analysis of the terminal occupation by ships (disposal of ship stalls on each quays) five operational scenarios were defined. Each scenario has been defined on the basis of an economic evaluation by means of a cost-benefit parametric analysis with the aim of providing the maximum financial results for assigned budgets. From a comparison of the results of the cost-benefit analysis and an estimate of possible investment costs obtained from USA case studies, it is noticed that the scenario providing coverage of both financial and economic investment includes the minimum number of electrified stalls and a ships journeys reorganization. It was also proposed a sensitivity analysis of CBA for the evaluation of indicators variations according to reference conditions variation
Wideband measurement of dielectric properties of wheat flour
No full textUse of electromagnetic (EM) fields in the food industry for food inspection as well as sterilization and drying is increasing. To develop such applications, the knowledge of the dielectric properties of food is fundamental. In the literature, there is scarcity of data on dielectric properties of powdered foods, with reported values that are usually at specific frequencies only. This article reports the development of an experimental framework to characterize the dielectric properties of powdered food over a wide range of frequencies. The used methodologies include the open-ended coaxial probe technique and waveguide systems: the first being intrinsically a broadband technique but strongly dependent on the type of material being tested, and the latter being a medium- to narrowband technique allowing a better control of the tested material. The proposed framework is then used to measure the dielectric properties of several types of flour between 500 MHz and 20 GHz. The measured properties are then characterized in terms of density and interpolated with a Cole-Cole dispersive model. From the measured results, the suitability of the proposed setup was demonstrated. Additionally, it was verified that the permittivity of flour does not depend on the brand and can be expressed as a function of the density of the material, following a mixture formula already proposed in the literature. Moreover, the proposed Cole-Cole fit is able to represent the frequency behavior of the real part of permittivity of flour with differences within 3% from the measured data
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
La normativa sulla qualità geometrica del binario e l'esercizio dei raccordi ferroviari
No full textI valori di riferimento per la manutenzione dell'infrastruttura in termini di qualità geometrica di binario previsti dalle normative nazionali ed europee non fornisco-no molte informazioni specifiche per i raccordi ferroviari. Esse appaiono conce-pite per i binari e i deviatoi delle linee principali, appartenenti alle reti nazionali interoperabili, esercite a velocità normalmente superiori a 80 km/h con rallenta-menti a velocità di 40 km/h, e quindi ben superiori a quelle di interesse per que-sto lavoro, in genere inferiori a 10 km/h. L'obiettivo generale della ricerca è per-tanto la definizione per i raccordi ferroviari di possibili valori di riferimento per la geometria del binario, e degli apparecchi di binario (deviatoi), che possano in-tegrare tali normative. I principi di base nella definizione di tali valori sono la massimizzazione dell’efficienza tecnico-economica ed il mantenimento dell'ac-cettabilità del rischio associato all'esercizio ferroviario.The reference values for infrastructure maintenance in terms of track geometric quality provided in the Italian and European regulatory documents do not supply much information specific for railway sidings. These documents appear to be conceived for tracks, switches and crossings of main lines, comprised in the in-teroperable national networks, with line speeds normally of at least 80 km/h and temporary speed restrictions usually not less than 40 km/h. Such speeds are much higher than the speeds of interest for the work described in this paper, which are most often below 10 km/h. Therefore, the general objective of the re-search is the definition of possible track-geometry reference values for sidings, including values for switches and crossings, in order to integrate the above-mentioned regulatory documents. The basic principles in the definition of such values are to maximise technical-economic efficiency and to maintain the same degree of acceptance of the risk associated to railway operations
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
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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