1,720,958 research outputs found
Advanced characterization of biofuels for combustion and gasification plants
No full textDetailed information on the biofuels is an essential requirement for the prediction of plant efficiency, carbon in ash, pollutant emissions, surface deposition and corrosion, in thermochemical processes. A fuelspecific
comprehensive characterization is required to design, operate and model combustion, oxy-firing and gasification plants. At IFRF it couples fundamental analyses with advanced tests in the Isothermal Plug Flow Reactor (IPFR), which allows high temperature and heating rate, under programmed gaseous environments (N2, O2, CO2, H2O). The aim of this work is to:
- define the experimental procedures for testing biomass fuels in the IPFR;
- provide significant results of the recent experimental campaigns on biomass fuels;
- extrapolate the prerequisites and principles that could be in common with other test facilities (in the frame of the BRISK project) for an advanced characterization.
Particular attention is devoted to the qualification of the system and procedures used. Different sources of uncertainty (due to diagnostic limitations, segregation phenomena, fuel heterogeneity) affecting the
operating parameters and test outputs (e.g., reaction conversion, obtained with the ash tracer method) are studied. The improvements in the experimental apparatus and procedures, as well as the support of CFD
assisted diagnostics (e.g., to estimate the effective thermal history of the particles inside the reactor) have helped in quantifying and reducing the experimental uncertainties. The aim is to provide qualified data for
the prediction of operational/design parameters for industrial-scale thermochemical systems. Uniform and reliable data will be finally inserted into the IFRF online Solid Fuel DataBase (SFDB)
Safety Data Analysis: Case Study of State Highway "Tirrena Inferiore"
No full textThe road safety has become a priority field worldwide and one of the major factors describing the transport system’s state with its positive and negative changes. Many studies on driver speed behaviour are found in the scientific literature, and researchers have addressed roadway alignment consistency for travel safety in context with real operating speeds. This paper illustrates an experimental analysis conducted on the State Highway “Tirrenia Inferiore” in Southern Italy without spiral transition curves between geometric tangent and circular elements on the horizontal alignment, to check a new prediction consistency model. Two consistency measures were developed and compared with the results available in scientific literature: the first was the relative area bounded by the speed profile and the average weighted speed; the second was the standard deviation of operating speeds in each design element along the entire road investigated. Combining these two previous measures and following an extensive sensitivity analysis, a consistency model was developed and thresholds for good, acceptable and poor road consistency can be proposed. The consistency prediction model was related to numbers of crashes occurred from 2003 to 2010. It was found that as design consistency increased, number of crashes decrease significantly. Consistency model can be use for this purpose during the geometric design process or during the evaluation process for two-lane rural highways
ROAD SAFETY ANALYSIS USING ITALIAN GUIDELINES
No full textSafe road design is about providing a road environment which ensures vehicle speeds will be within the human tolerances
for serious injury and death wherever conflict points exist. International researchers have thus suggested a variety of approaches to
analyze the road traffic safety level as some procedures based on the valuation of the accident rates and accident frequency. The
research described in this paper aims to illustrate a network safety approach as suggested by Italian Guidelines in order to identify
homogeneous roadway segments where the crash rate (crash frequency over traffic exposure) is higher or lower than on statistically
significant thresholds referred to the whole analyzed road path. Three different road safety thresholds are suggested: a) low when the
crash rate is of less than lower limit, b) moderate when the crash rate falls between upper and lower limits, c) severe when the crash
rate is greater than the upper limit. It’s suggested an additional careful study on the road segments with high crash rate making a
comparison between existing and potential infrastructural-geometric-environmental failures to determine potential countermeasures.
The study presented here involved a rural road in Southern Italy located on flat/rolling area with a vertical grade of less than 6%,
without spiral transition curves between geometric tangent and circular elements, which is provided with controlled access or rather
road interchanges and 11 km almost of slow lane for both travel directions. The data set used for this study includes crashes from
2003 through 2010; in particular 301 crashes were observed with 444 injuries and 41 deaths over the total length of the 71.92 km.
Analysis showed that homogeneous road segments with high crash rates occurred in 16% of cases, while with medium crash rates in
38% of cases and low crash rates in 46% of cases
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
Crash Severity Prediction Functions on Italian Rural Roads
No full textThe Highway Safety Manual (HSM) published by the American Association of State Highway and Transportation Officials (AASHTO) provides predictive models for rural two- lane highways giving estimates for total crashes and it presents predictive methods for urban or suburban arterial facilities to estimate the expected average crash frequency, crash severity and collision types. According to HSM methodological issues, the objective of the research is to calibrate and validate safety performance functions (SPFs) that predict the number of injuries and deaths per year (frequency of injuries and deaths) on homogeneous road segments of two-lane rural roads by investigating local conditions. More than 1,400 mi of road network were analyzed. Crash data over an 8-year period (2003- 2010) were used (1,597 injury crashes with 2,592 injuries and 67 deaths) of which 5 years (2003 – 2007) of crash information were used to calibrate SPFs while the remaining 3 years were used to check the reliability of SPFs. Reflecting HSM procedure, a base regression model was performed to predict the frequency of injuries and deaths and then multiplicative coefficients were introduced to account the differences between the first base conditions and the proper road geometric features for transferability to different networks. Three SPFs were performed as follows: a) one equation to predict the frequency of only injuries per year; b) one equation to predict the number of only deaths per year; c) one equation to predict the total injuries+deaths number per year
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
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