1,721,691 research outputs found
Boating Against the Current: Cases, Concepts, Models and Development Power
Get PDFGeneralizing from many of actual problems, this paper puts forward the game: boating against the current, discusses the related assumptions and analyzes the related characters of it. Further more, the author gives the dispersed and continuous models for boating against the current Based on the Partial Distribution[14]-[17]. It is worth to say that the game of boating against the current is a representative example of Development Power problems [18]-[21]. So we should see that the theories of Development Power is proved to have a wide realistic background, and studying Development Power is important for human to interpret and to analyze the macro-laws and macro-characters of economy and society developing.boating against the current, Development Power (DP), Partial Distribution, society and economy, analytic model
Analysis of wave behavior in rails using a numerical model
No full textThe vibration of the rail is a major contributor to railway rolling noise and consists of different waves that propagate along the rail. In order to study the dynamic behaviour of a railway track, models based on Timoshenko beam theory and waveguide finite element method were established. The solution procedures to obtain the free wave response and the forced response for each model were described. The characteristics of waves in rail in terms of wavenumber, group velocity, mobility and decay rate were analyzed based on two different models. The results indicate that using the waveguide finite element model, which includes all the features of rail cross-section deformation, eight kinds of waves are identified in rail within the frequency range up to 6 kHz. Moreover, the phenomena of wave mode exchange and group velocity exchange between waves are presented as well as the peak in the mobility due to the excitation of the higher order wave mode.</p
A comparison of confidence/credible interval methods for the area under the ROC curve for continuous diagnostic tests with small sample size
No full textThe receiver operating characteristic (ROC) curve is frequently used as a measure of accuracy of continuous markers in diagnostic tests. The area under the ROC curve (AUC) is arguably the most widely used summary index for the ROC curve. Although the small sample size scenario is common in medical tests, a comprehensive study of small sample size properties of various methods for the construction of the confidence/credible interval (CI) for the AUC has been by and large missing in the literature. In this paper, we describe and compare 29 non-parametric and parametric methods for the construction of the CI for the AUC when the number of available observations is small. The methods considered include not only those that have been widely adopted, but also those that have been less frequently mentioned or, to our knowledge, never applied to the AUC context. To compare different methods, we carried out a simulation study with data generated from binormal models with equal and unequal variances and from exponential models with various parameters and with equal and unequal small sample sizes. We found that the larger the true AUC value and the smaller the sample size, the larger the discrepancy among the results of different approaches. When the model is correctly specified, the parametric approaches tend to outperform the non-parametric ones. Moreover, in the non-parametric domain, we found that a method based on the Mann-Whitney statistic is in general superior to the others. We further elucidate potential issues and provide possible solutions to along with general guidance on the CI construction for the AUC when the sample size is small. Finally, we illustrate the utility of different methods through real life examples
The Partial Distribution: Definition, Properties and Applications in Economy
Get PDFIn this discussed draft, we want to present the Partial Distribution (F.Dai, 2001) for discussing. We compare the partial distribution with lognormal and levy distribution. Though the levy distribution is better to describe the prices distribution of stock and stock indexes in a moderately large volatility range, the lognormal is better in a region of low values of volatility. We shall try to elucidate that the Partial Distribution is better than lognormal distribution in many respects. From partial distribution, we can acquire lots of interesting results, such as, describing the probability that stock price become zero if corresponding company collapses or the commodity price become zero if it lapses, expressing the average selling price of a commodity or stocks as the cost and average profits, and offering the accurate analytic model of American puts options pricing, etc. there are some related studies in appendix.partial distribution, economic analysis, commodity pricing, American puts option, accurate pricing formula
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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