1,720,959 research outputs found
General EM Algorithm for Fitting Non-Monotone Hazard Functions from Truncated and Censored Observations
No full textRecently, many researchers focused on modeling non-monotonic hazard functions such as bath-tube and hump shapes. However, most of their estimation methods are focused on complete observations. Since reliability data are typically censored and truncated, a general EM algorithm is proposed, which can fit any of those complex hazard functions. The proposed EM algorithm is analyzed by fitting well-known 4-parameter hazard functions, where its performance is compared by their specific direct methods through extensive Monte Carlo simulations. (c) 2022 Elsevier B.V. All rights reserved.11Nsciescopu
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
불완전한 신뢰도 데이터에서 다부품 시스템의 유지 보수 전략 최적화
No full textJoint maintenance optimization of a multi-component system is not straightforward due to inter-dependence among components, and because reliability data is known to be incomplete and scarce. Also, when analyzing multi-component systems, phase-type distributions are widely used because they allow approximation of non-Markovian models, which permits to analyze complex systems under Markovian deterioration. Thus, a novel approach that fits a restricted class of discrete phase-type distribution through a pre-specified hazard sequence from incomplete observations is proposed. In addition, a 4-parameter pre-specified hazard sequence that unifies non-decreasing, hump-shaped, and bath-tube shaped hazard functions are presented. Since reliability data are typically truncated and censored, an Expectation-Maximization algorithm is derived to fit the parameters of the proposed pre-specified hazard sequence from left-truncated and right-censored observations. Thus, the maintenance optimization problem is modeled by using a model-based reinforcement learning scheme, where the transition probabilities are derived from the discrete phase-type distribution linked to the fitted pre-specified unified hazard sequence. In addition, looking for optimal joint preventive maintenance policy is known to be challenging due to the combinatorial maintenance grouping problem. Hence, a reduced action space is proposed by preserving optimality for homogeneous multi-component systems. A threshold policy derived from the characterization of optimal policy's decision boundaries is presented for heterogeneous multi-component systems. Moreover, we observe that the optimal policy’s decision boundary is counter-intuitive, which is not seen in the literature. Some detailed analysis is given about it. Finally, the proposed Expectation-Maximization algorithm and the threshold policy are analyzed through extensive Monte Carlo simulations.한국과학기술원 :산업및시스템공학과,학위논문(박사) - 한국과학기술원 : 산업및시스템공학과, 2021.2,[v, 76 p. :
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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