1,720,960 research outputs found
Minimum power multicasting on wireless networks: a shared incumbent environment approach
No full textShared incumbent environment is a new approachwhere a mixed integer linear programming solverand a meta-heuristic search algorithm work in paralleland inform each other when they improve the best knownsolution. In this study, we implement a shared incumbentenvironment by combining simulated annealing with amathematical programming formulation for solving theminimum power multicasting problem, where the goal isto find a topology for the wireless network terminals suchthat the source terminal will be able send data to alldestination terminals with minimized total transmissionpower. We present our results and analyze the success ofshared incumbent environment approach on instances ofdifferent sizes.
Keywords: minimum power multicasting problem; wir
A three-stage robust approach for minimum power multicasting in wireless sensor networks
No full textIn this paper we study the minimum power multicasting problem in wireless sensor networks, where the transmission power required for one network terminal to transmit to another is subject to uncertainty.
We propose a three-stage approach based on linear programming.
Our novel approach adds two polynomial time stages to a first stage corresponding to a classical approach well known in the literature and based on a mathematical programming formulation. Stages two and three are introduced to adjust the transmission power of nodes in such a way to achieve a better protection against uncertainty, without increasing the total power consumption.
Experimental results show that our three-stage approach increases the robustness of the solutions obtained using the classical approach
A robust multiple ant colony system for the capacitated vehicle routing problem
No full textIn transportation problems like the vehicle routing problem, the decision makers are increasingly adopting the idea that the problem data can be subject to uncertainty. The uncertainty can be encountered because of events that are not exactly predictable, like weather conditions, traffic jams, etc. In this paper, we study vehicle routing problem with uncertain travel costs. Then, to solve the problem, we propose a robust multiple ant colony system: a metaheuristic in which multiple ant colonies work in parallel to generate a collection of solutions with different levels of protection against the uncertainty. The uncertainty is handled by incorporating linear formulations from the field of robust optimization into the metaheuristic approach
An ant colony system for the capacitated vehicle routing problem with uncertain travel costs
No full textIn this study, we consider a capacitated vehicle routing problem where the objective function is to minimize the total travel cost.We also consider that the travel costs between the locations are subject to uncertainty, therefore they are expressed as intervals, rather than fixed numbers. The motivation of this study is to solve this problem by using a metaheuristic approach. We base our approach on a variant of ant colony optimization metaheuristic, called ant colony system, which was originally implemented for solving the deterministic version of the problem (i.e. the classical version of the problem without the uncertainty), previously reported in the literature. We modify the algorithm to incorporate a robust optimization methodology, so that the uncertainty on traveling costs can be handled
Aggregate blending via robust linear programming
No full textAggregate blending is a problem frequently encountered in the construction industry. In this article, it is shown that robust linear programming can be used to produce solutions protected against noisy data with the same computational complexity of the classic optimization methods for the problem. It is also shown that nonlinear cost functions can be approximated by piecewise linear functions, keeping complexity at a low level. Finally, experimental results are presented. The aim is to understand how robust linear programming solutions compare with those of other methods previously described in the literature and to evaluate the actual quality of the robust solutions
A shared incumbent environment for the minimum power broadcasting problem in wireless networks
No full textIn this study, we consider the minimum power broadcasting problem in wireless actuator networks. We attack the problem with a method - the shared incumbent environment - that executes two algorithms in parallel: a mathematical programming approach and a simulated annealing approach. According to the shared incumbent environment paradigm, when an incumbent solution is found by one method, the other method is notified and profits from the information received. Experimental results show that the shared incumbent environment lead to results which are better than those of the two algorithms combined in it taken singularly
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
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