1,721,094 research outputs found
Examination of Pervious Pavement Pore Parameters with X-Ray Tomography
No full textPervious pavement (PP) is an infrastructure material that can alter rainfall-runoff relationships, filter particulate matter (PM), and
sequester runoff constituents. Beyond a measure of total porosity ( φt), less-commonly measured pore parameters and relationships thereof
influence these phenomena. In this study, cementitious PP (CPP), used as a permeable surface for an exfiltration system loaded by runoff, was examined. X-ray tomography (XRT) was utilized to examine pore size and frequency, generate a total-to-effective porosity (φt − φe) relation- ship, quantify pore tortuosity (Le=L), and relationships for specific surface area (SSA), pore-size distributions ðPSDÞpore, and φt. Gravimetric analyses were used for SSA based on mass ðSSAÞs as well as validation of XRT porosity. Results indicate that φt ranged from 10 to 30% while φe ranged from 4 to 27%. Relationships for (φt − φe), SSA, φt, and median pore diameter (d50n) were represented with a power law model (PLM). Using φt the ðSSAÞpt of pores ranged from 11,000 to 19,000 m2=m3 while for φe, ðSSAÞpe ranged from 12,000 to 21,000 m2=m3. XRT results show that the ðPSDÞpore is hetero-disperse. (Le=L) ranged from 2.9 to 5.9, compared to 1.4 for a monodisperse and uniform distribution of pore sizes. The ðLe=LÞ-φt relationship and probability density function (pdf) of (Le=L) were Gaussian. Beyond the common index of φt, these parameters are building blocks for infiltration, filtration, evaporation, storage, and reaction components of models such as the storm water management model (SWMM) and computationalfluid Dynamics (CFD
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
Pore-structure models of hydraulic conductivity for permeable pavement
No full textPermeable pavement functions as a porous infrastructure interface allowing the infiltration and evaporation
of rainfall–runoff while functioning as a relatively smooth load-bearing surface for vehicular transport.
Hydraulic conductivity (k) of permeable pavement is an important hydraulic property and is a
function of the pore structure. This study examines k for a cementitious permeable pavement (CPP)
through a series of pore-structure models. Measurements utilized include hydraulic head as well as total
porosity, (/t), effective porosity (/e), tortuosity (Le/L) and pore size distribution (PSD) indices generated
through X-ray tomography (XRT). XRT results indicate that the permeable pavement pore matrix is hetero-
disperse, with high tortuosity and /t – /e. Power law models of k–/t and k–/e relationships are
developed for a CPP mix design. Results indicate that the Krüger, Fair-Hatch, Hazen, Slichter, Beyer
and Terzaghi models based on simple pore-structure indices do not reproduce measured k values. The
conventional Kozeny–Carman model (KCM), a more parameterized pore-structure model, did not reproduce
measured k values. This study proposes a modified KCM utilizing /e, specific surface area (SSA)pe
and weighted tortuosity (Le/L)w. Results demonstrate that such permeable pavement pore-structure
parameters with the modified KCM can predict k. The k results are combined with continuous simulation
modeling using historical rainfall to provide nomographs examining permeable pavement as a low
impact development (LID) infrastructure componen
Filtration and clogging of permeable pavement loaded by urban drainage
No full textPermeable pavement, as a sustainable infrastructure material can promote hydrologic
restoration, particulate matter (PM) and solute control. However, filtration and commensurate
clogging are two aspects of continued interest and discussion. This study quantifies
filtration and clogging of cementitious permeable pavement (CPP) for loadings from 50 to
200 mg/L of hetero-disperse sandy-silt PM. The CPP mix design provides a hetero-disperse
pore size distribution (PSD)pore, effective porosity (4e) of 24% and median pore size of
658 mm with a standard deviation of 457 mm. The PM mass separation across the entire
particle size distribution (PSD)PM exceeds 80%; with complete separation for PM greater
than 300 mm and 50% separation for suspended PM. Turbidity is reduced (42e95%), and
effluent is below 10 NTU in the first quartile of a loading period. Permeable pavement
illustrates reductions in initial (clean-bed) hydraulic conductivity (k0) with loading time. For
all PM loadings, k0 (3.1 101 mm/s) was reduced to 104 mm/s for runoff loading durations
from 100 to 250 h, respectively. Temporal hydraulic conductivity (k) follows exponential
profiles. Maintenance by vacuuming and sonication illustrate that 96e99% of k0 is recovered.
Permeable pavement constitutive properties integrated with measured PM loads and
a year of continuous rainfall-runoff simulation illustrate k reduction with historical loadings.
Study results measure and model filtration and hydraulic conductivity phenomena as
well as maintenance requirements of permeable pavement directly loaded by urban
drainag
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