1,720,963 research outputs found
Off-Policy Temporal Difference Learning for Perturbed Markov Decision Processes
No full textDynamic Programming suffers from the curse of dimensionality due to large state and action spaces, a challenge further compounded by uncertainties in the environment. To mitigate these issue, we explore an off-policy based Temporal Difference Approximate Dynamic Programming approach that preserves contraction mapping when projecting the problem into a subspace of selected features, accounting for the probability distribution of the perturbed transition probability matrix. We further demonstrate how this Approximate Dynamic Programming approach can be implemented as a particular variant of the Temporal Difference learning algorithm, adapted for handling perturbations. To validate our theoretical findings, we provide a numerical example using a Markov Decision Process corresponding to a resource allocation problem
Price Management in Resource Allocation Problem with Approximate Dynamic Programming
No full textThe problem of managing the price for resource allocation arises in several applications, such as purchasing plane tickets, reserving a parking slot, booking a hotel room or renting SW/HW resources on a cloud. In this paper, we model a price management resource allocation problem with parallel Birth-Death stochastic Processes (BDPs) to account for the fact that the same resource can be possibly purchased by customers at different prices. In addition, customers can hold the resource at the purchase price to the necessary extent. The maximization of the revenue in both the finite and infinite time horizon cases is addressed in this paper with Stochastic Dynamic Programming (DP) approaches. To overcome the difficulty in solving the corresponding optimization problem due to the state space explosion, Approximate Dynamic Programming (ADP) techniques (in particular, the Least Square Temporal Difference method along with Monte Carlo simulations) are adopted. Furthermore, a MATLAB Toolbox is developed with the aim of solving stochastic DP/ADP problems and supporting probabilistic analysis. Extensive simulations are performed to show the effectiveness of the proposed model and the optimization approach
A stochastic dynamic programming approach for the machine replacement problem
Full text linkThis paper addresses both the modeling and the resolution of the replacement problem for a population of machines. The main objective is the computation of a minimum cost replacement policy, which, based on the status of each machine, determines whether one or more machines have to be replaced over a given finite time horizon.
The replacement problem of a set of machines can be regarded as a sequential decision-making problem under uncertainty. Thanks to this, we propose a novel formulation for such problems consisting of a composition of discrete-time multi-state Markov Decision Processes (MDPs), one for each specific machine. The underlying optimization problem is formulated as a stochastic Dynamic Programming (DP), and then solved by using the principles of the backward DP algorithm. Moreover, to deal with the curse of dimensionality due to the high-cardinality state–space of real-world/industrial applications, a new generalized multi-trajectory Least-Squares Temporal Difference (LSTD) based method is introduced. The resulting algorithm computes an approximate optimal cost function by: (i) running Monte Carlo simulations over different trajectories of a given length; (ii) embedding the policy improvement step within the recursive LSTD iterations; (iii) enforcing an off-policy mechanism to improve the LSTD exploration capabilities. A study on the convergence properties of the proposed approach is also provided. Several numerical examples are given to illustrate its effectiveness in terms of parametric sensitivity, computational burden, and performance of the computed policies compared with some heuristics defined in the 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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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