1,720,969 research outputs found
A metaheuristic algorithm for the probabilistic orienteering problem
No full textThe Probabilistic Orienteering Problem (POP) is a variant of the orienteering problem where customers are available with a certain probability. In a previous work, we approximated its objective function value by using a Monte Carlo Sampling method. A heuristic speed-up criterion is considered in the objective function evaluator. In this work we study systematically the impact of the heuristic speed-up criterion in terms of precision and speed on the Monte Carlo evaluator, as well as the performance of a POP solver we propose, based on the embedding of the Monte Carlo evaluator into a Random Restart Local Search metaheuristic algorithm
A Tabu Search algorithm for the Probabilistic Orienteering Problem
No full textThe Orienteering Problem is a routing problem aiming at selecting a subset of a given set of customers to be visited within a given time budget, so that a total revenue is maximized. Multiple variants of the problem have been studied. The Probabilistic Orienteering Problem is one of these variants, where customers will require a visit according to a certain given probability. Stochasticity makes the model more practical, but concurrently more difficult to solve. Tabu Search is a method widely used in combinatorial optimization problems to escape from local optima in heuristic local search procedures. In this work, we solve the Probabilistic Orienteering Problem by embedding a Monte Carlo evaluator into a Tabu Search algorithm, exploiting their interaction in an innovative way. A detailed computational study of the new approach is presented, with the aim of studying the performance of the metaheuristic algorithm in terms of precision and speed, while positioning the new method within the existing literature
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
Notice of Removal: Re-Initialising Solutions in a Random Restart Local Search for the Probabilistic Orienteering Problem
No full textThe Probabilistic Orienteering Problem is an optimization problem where a set of customers, each with an associated prize and probability of requiring a service, a time budget and travel times between customers are given. The objective is to select the subset of customers that maximize the expected total prize collected in the given time (taking into account of the total travel time spent visiting them). Random Restart Local Search is a heuristic method widely used to solve combinatorial optimization problems. In particular, it is used in conjunction with local search procedures to escape from local optima. The method works by restarting the optimization search once no further improvement is possible by the embedded local search component. Each restart is associated with a new initial solution for the optimization, and selecting such restart initial solutions play an important role in the success of the overall algorithm. In this work we propose a method to effectively selecting such solutions, and we present an empirical study to validate our ideas
Assessing the duration of intralogistics forklift operations via machine learning
No full textIn the ongoing transition to Logistics 4.0, humans and technologies are increasingly interacting in operations systems. An example is the use of wireless devices for operation logs in the warehouse management systems. The performance and quality of such systems depend on human behaviors to a noticeable extent. Valid data from compliant operations provide great value for follow-up researches, while in actual operations deviant behaviors occur and contaminate the data. Quantitative studies on whether and to which extent operators do infringe or fulfill the organizational norms in the execution of digital workflows are limited. To close this gap, in this work we conduct a data-driven assessment of the duration of forklift operations in a German warehouse owned by a grocery retailing chain. By predicting the execution time of forklift picking tasks with given features, we study the proportion of standardized operations performed by different operators based on predicting accuracy. This could serve as an effective indicator before further developing systems using machine learning technologies for better distribution of the tasks based on the relevance of the operators' skills and the tasks' characteristics
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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