121,194 research outputs found
Streamline curvature effects in confined isothermal recirculating flowfields behind an axisymmetric bluff body - Numerical calculations with the k-epsilon turbulence model
No full textThe confined turbulent recirculating flowfield due to the isothermal mixing of dual coaxial streams in the near-wake region of an axisymmetric bluff body is numerically investigated. The finite-difference computations based upon the Reynolds-averaged Navier-Stokes equations and the k-epsilon turbulence model examine modifications to the turbulence model to account for the effects of streamline curvature and for the preferential influence of normal stresses on turbulence dissipation. This examination is facilitated by a comparison of the predicted and measured results of the axial and radial distributions of the mean and rms axial velocity, the centerline stagnation points, and the axial decay of the centerline CO2 concentration
Isothermal Predictions of Recirculating Turbulent Flow fields of Confined Dual Coaxial Jets Behind an Axisymmetrec Bluff Body
No full textFinite-difference numerical computations are presented to predict the isothermal, turbulent, recirculating flowfields in a centerbody combustor configuration which involves confined dual coaxial jet mixing in the near-wake region of an axisymmetric bluff body. The calculations based upon the Reynolds-averaged Navier-Stokes equations and the k-epsilon turbulence model consider the influence of the annular and central flow rates on the nature of the flowfield downstream of the bluff body. Other questions addressed include the effects of inlet turbulence length scales and streamline curvature. The recirculating flowfield structure is studied by examining the axial and radial distributions of the mean and rms velocity fields, the centerline stagnation points, the vortex center, and the zero mean axial velocity contour. The present numerical results demonstrate the complex nature of the flowfield interactions in the near-wake region and refine the understanding of the centerbody combustor flowfields
Mujeres toman el poder de la tierra: acceso a la tierra como una estrategia de empoderamiento de mujeres indígenas en Guatemala
No full textDe conformidad con el presente estudio, en Guatemala las personas más pobres y marginadas son las mujeres indígenas. De acuerdo con el PNUD, de las mujeres indígenas, 80% están ligadas a la tierra y a la agricultura por diversas formas. Sin embargo, las mujeres sólo representan un 6,5% entre l@s proprietari@s de la tierra. La mayoría de las veces esa conexión compleja del mundo indígena con la tierra no es reconocida por las estadísticas oficiales porque apenas están remuneradas por su trabajo en la agricultura. El presente estudio, realizado por la politóloga Archana Krishnamurthy se enfoca en la realidad guatemalteca y la exclusión masiva de las mujeres indígenas en la tenencia de la tierra. Recoge, con base en casos concretos las experiencias que diversas comunidades han tenido con los programas de tierra y explica en qué medida y de qué forma las mujeres pueden participar
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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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