1,720,989 research outputs found
A Decision Support System for Earthwork Activities in Construction Logistics
No full textMaking decisions in a complex system such as the construction of a
highway is a hard task that involves a combinatorial set of possibilities, concerning
thousands of interrelated activities and resources over several years. In this paper
we describe a decision support system (DSS) developed to assist project managers
in decision making for the construction of the Autostrada Pedemontana Lombarda
highway, in Italy. The considered problem evaluates the earthwork activities in de-
tail and defines the minimum cost earthwork plan satisfying all constraints. The
proposed DSS involves the use of linear programming to solve the earthwork pro-
blem in a two-phase approach: in the first phase, an aggregate model determines the
feasibility of the overall project, whereas in the second phase, disaggregate models
determine the actual flows of each material. The DSS gathers the needed informa-
tion directly from the master plan commonly used by the company and provides
as output a set of visual solutions. The solution are yielded in short times and can
be run many times with different data sets supporting a fast evaluation of different
decisions. The provided solutions are also optimized and could substitute the previ-
ous manual results. The DSS has been proved to be very effective for assisting the
project managers of the above highway construction and is currently in use in other
project
A two-phase approach for an integrated order batching and picker routing problem
No full textThis article addresses an integrated warehouse order picking problem. The company HappyChic is specialized in men’s ready-to-wear. A central warehouse is dedicated to supplying, every day, the shops of one brand. We focus on the picking area of this warehouse which relies on human picking system. For each picking wave (period of a working day), a set of customer orders has to be prepared. An order is a set of product references, with quantities, i.e., the numbers of items required. The problem consists in jointly deciding: (1) the division of orders into several boxes, respecting weight and size constraints; (2) the batching of boxes into trolleys, that implicitly defines the routing into the picking area. The objective function aims to minimize the total distance. To deal with the large size instances of HappyChic in short computation times, we design a heuristic method based on the split and dynamic programming paradigms. The results are very convincing: the total covered distance decreases by more than 20%. Moreover, we propose an adaptation of the algorithm to prepare homogeneous boxes with respect to classes of products. The logistic department of HappyChic is convinced by results obtained in this research work, and the warehouse management system is currently being updated in order to integrate the proposed algorithm
A Tool for Practical Integrated Time-Table Design and Vehicle Scheduling in Public Transport Systems
No full textPlanning of services and resources for public transport systems is a complex process. In practice the planning is usually decomposed into several stages, where service levels are decided first, while vehicles and drivers are only optimized later on. We describe the new TTD.XT tool, developed by M.A.I.O.R. S.r.l. in collaboration with the University of Pisa, that improves the efficient utilization of expensive resources by simultaneously optimizing timetabling and vehicle scheduling. We quickly present the underlying mathematical model and (math-heuristic) algorithm, and compare the solutions constructed by the tool for real-world bus transport planning instances for three major Italian cities with those produced by the standard sequential decision process; the former are significantly better than the latter both in terms of objective function value and when judged by experts of the field
Optimal Secure and Economical Dispatching by Means of a min-max-min Optimization Technique
No full text
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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