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Coefficient of restitution and dimensions of surface deformations for particle-wall collisions in various fluids
No full textControlled particle-wall collisions are conducted in various fluids. Impact and rebound velocities of a particle as well as the diameter and depth of the generated crater on the surface are reported in this dataset. Three materials are used for the walls: aluminum alloys 6061, 2014, and 7075. The impact experiments are performed in seven fluids with a wide range of density and viscosity: air and six different mixtures of water-glycerin.
Properties of the impacting particle, target surfaces, and fluids are given in the PhD dissertation: Ruiz-Angulo, Angel (2008) Surface Deformation in a Liquid Environment Resulting from Single Particle Collisions. Ph.D. Dissertation, California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-05222008-090253.
Concise description of the experimental procedure, material properties, results, and analyses are also given in the following article:
Ruiz-Angulo, A., Roshankhah, S., and Hunt, M. L. "Surface deformation and rebound for normal particle-wall collisions in a surrounding fluid." under review in the Journal of Fluid Mechanics.Related Publication:
Surface deformation and rebound for normal single-particle collisions in a surrounding fluid
Ruiz-Angulo, Angel Icelandic Meteorological Office
Roshankhah, Shahrzad California Institute of Technology
Hunt, Melany L. California Institute of Technology
Fluid Mechanics
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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
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
Surface Deformation in a Liquid Environment Resulting from Single Particle Collisions
Get PDFMultiphase flows are fairly complex and they are usually studied as a bulk. In this thesis, these flows are approached by looking at single particle interactions (particle-particle and particle-wall). This work presents experimental measurements of the approach and rebound of a particle colliding with a ``deformable' surface in a viscous liquid. The complex interaction between the fluid and the solid phases is coupled through the dynamics of the flow as well as the deformation process. A simple pendulum experiment was used to produced single controlled collisions; steel particles were used to impact different aluminum alloy samples (Al-6061, Al-2024, and Al-7075) using different aqueous mixtures of glycerol and water as a viscous fluid. The velocity of the particle before and after the collision was estimated by post-processing the particle position recorded with a high speed camera. For the combination of materials proposed, the elastic limit is reached at relatively low velocities. The deformations produced by the collision were analyzed using an optical profilometer. The measurements showed that the size of the indentations is independent of the fluid media. It was found that the size of the indentations was the same for collisions in air than for the rest of the collisions using various viscous fluids. The results show that the plastic deformation is only a function of the impact velocity and the material properties. The normal coefficient of restitution and deformation parameters account for losses due to lubrication effect and inelasticity, identifying then, the dominant energy loss mechanism during the collision process.
According to the strain imposed in the samples due to the collision, the deformations were either elastic or elastic-plastic. The equivalent load due to the impact velocities used in this work did not reach the fully-plastic regime. For the collisions in air, different models were used to compare the experimental results showing that the elastic-plastic regime is not well characterized by only the material properties and the impact velocity. The time-resolved contact force was measured during the process of the indentation for the dry collision experiments using a quartz load transducer.
The experiments clearly show four different regimes depending on the impact Stokes number: lubrication effect and elastic deformation, lubrication effect and elastic-plastic deformation, elastic deformation with no hydrodynamic effects, and elastic-plastic deformation with negligible lubrication effect. An analysis of the erosion of ductile materials during immersed collisions is presented. The size of the crater formed by the impact of a single particle against a ductile target can be estimated from theory, and these estimates agree well with experimental measurements. </p
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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