1,721,017 research outputs found
How to evaluate and plan the freight-passengers first-last mile
No full text“First-last mile” (FLM) is an informal composed-word, widely used to indicate the first and the last leg of each transport movement. In this paper, it is defined as a complex system characterized by three interconnected macro factors that determine the success of a transport planning system. This is a very challenging part of the transport system from a planning perspective because of the critical issues that make it not much reliable and cost-effective. This paper capitalizes on the experiences gained in different implementations/studies and provides a theoretical framework for a good assessment and planning of the first-last mile. It stems from the recognition that the literature proposes different solutions and methods, ranging from the promotion of green transport to the use of ITS technologies. For this reason, this paper aims at elaborating some guidelines on how to tackle the problem in different territorial contexts, trying to be a help to the planners to reduce the negative consequences of mobility. Five main phases are identified here: 1) First-last mile identification; 2) Schematization of the problem and cost analysis; 3) Definition of the stakeholder involvement in the process; 4) Identification of the critical aspects of the process; 5) Identification of the best strategies to reduce costs. For each phase, the indicators to be taken into account for a correct transport planning are discussed, as a first step for stakeholders and policy-makers for making themselves aware of the significant potential of this issue
A proposal of a unique formula for computing compliance in bolted joints
Full text linkThe connection system between mechanical parts with the greatest advantages in terms of production is the threaded connection. This type of connection has considerable stiffness but also high weight. Often the search for the reduction of the masses clashes with the limits dictated by production needs. A considerable effort has been made in making screws with higher performance materials and therefore guaranteeing greater tightening forces with smaller cross sections, but there have not been as many notable developments on the method of determining the compliance of tightened elements. The classical theory identifies three different conditions for calculating deformability, which are sometimes not easy to interpret and implement. The use of numerical techniques such as finite elements allows designers to be very precise, but requires a great deal. To facilitate the work of the designers and provide them with a more manageable tool to better understand the type of threaded connection to be designed, the present work proposes an analytical formulation that allows a quick assessment of the compliance value of the clamped elements, regardless of the geometric relationships and materials. To achieve this, starting from a literature analysis, a parametric finite element model was developed and, based on the results obtained, a formula is proposed that covers all the possible scenarios for determining compliance. The results were compared with the classical theory in order to verify the correctness and applicability of the formulation. At the moment the formulation is valid for screws whereas for the bolts with nut unified formula is under investigation
Modelling Strategy and Parametric Study of Metal Gaskets for Automotive Applications
Full text linkThis paper is focused on finite element simulation of cylinder head gaskets. Finite element codes support several methodologies, each of which has its own strengths and weaknesses. One of the key points lies in the influence of the gasket geometry on its final behaviour. Such a contribution can come from the detailed modelling of the gasket or by defining a global non-linear behaviour in which material and geometry non-linearities are summarised. Two approaches were used to simulate the gasket behaviour. The first one consists in using a 2D approach, which allows to model through-thickness non-linear behaviour of gasket. The second one consists in using conventional 3D finite element modelling. The numerical methods have been discussed and compared in relation to the accordance with experimental data, amount of information supplied and computational time required. Finally, a parametric study shows how some geometric parameters influence the compressive load and the elastic recovery of a single-layer steel gasket
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
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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