1,720,959 research outputs found
A Heuristic Procedure to Solve an Evolutionary Vehicle Routing Problem with Time Windows
No full textThe paper deals with a hybrid clustering-genetic algorithm that is applied to a rolling-horizon procedure for solving the dynamic vehicle routing problem with time windows. The paper mainly focuses on the advantages of introducing a clustering algorithm jointly with the genetic algorithm. Discussion is supported by numerical tests carried out by simulating the implementation of the procedure to the urban logistic centre of Padova, Italy. Results highlight that introducing clustering criteria to guide a genetic algorithm in the operations of generating the initial population, mutation and cross-over can improve the solution as 20%
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
Citylog©, a software tool for city logistics operation: Testing and validation activities
No full textThe paper describes the results of testing and validation of CityLog©, a software tool developed by ENEA (Italian Agency for the Environment, New Technologies and Environment) and the Department of Transport of University of Rome “La Sapienza”, allowing the manager of a City Terminal to define in real-time the best delivering program even in a “within day” operational scheme.
Firstly the authors briefly discuss the modelling framework and provide a concise description of the solution procedure, which is based on a two-string genetic algorithm that solves the Vehicle Routing Problem with vehicle capacity and time window constraints. Finally, they describe the results obtained by simulating the actual operation at the urban terminal of Padua Interport and a comparison with the results provided by Transcad, one of the most popular software packages for transportation planning
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
A Model for Transit Design with Choice of Electric Charging System
No full textThe paper deals with the problem of transit system design for a mixed fleet of electric and internal combustion buses and introduces a model for the vehicle type choice that involves computation of lifetime internal and external cost. Unlike previous works focused on transit network design problem, this model assumes the set of routes as fixed. It introduces instead different fast charging alternatives and constraints related to battery autonomy, energy consumption and power transfer from the electricity grid. Results of a real-size numerical application carried out on a transport corridor in Rome are illustrated.The paper deals with the problem of transit system design for a mixed fleet of electric and internal combustion buses and introduces a model for the vehicle type choice that involves computation of lifetime internal and external cost. Unlike previous works focused on transit network design problem, this model assumes the set of routes as fixed. It introduces instead different fast charging alternatives and constraints related to battery autonomy, energy consumption and power transfer from the electricity grid. Results of a real-size numerical application carried out on a transport corridor in Rome are illustrated
Last-mile, a Procedure to set up an Optimized Delivery Scheme
No full textThe paper illustrates a comprehensive procedure for the design of a delivery scheme in an urban area, where a set of possible locations for logistic transit-points exists. In such a scheme it is assumed that deliveries for Business-to-Consumer (BtoC) e-commerce of goods are performed at specific drop-points, suitably selected to match the pick-up of the parcels to usual activities of the customers, like the breakfast at the bar or the purchase of the newspaper. The solution procedure, which integrates transportation system theory and operational research techniques, applies a disaggregate Nested Logit Model (NLM) for demand estimation, an Analytic Hierarchy Process (AHP) to compare and select possible drop-points, and a double string Genetic Algorithm (GA) to solve jointly both the problems of transit-point location and sizing and of drop-point clustering for deliveries tours. A GA performance function is computed by solving a standard Travel Salesman Problem (TSP) on the road graph, whose travel times have been estimated by assigning the O/D matrix of car trips. The first application of the procedure to the town of Terni, in Italy, has provided very encouraging results
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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