1,720,963 research outputs found
Supervised classification and estimation of hydrometeors using C-band dual-polarized radars: a Bayesian approach
No full textAbstract—In this paper, a Bayesian statistical approach for
supervised classification and estimation of hydrometeors, using
a C-band polarimetric radar, is presented and discussed. The
Bayesian Radar Algorithm for Hydrometeor Classification at
C-band (BRAHCC) is supervised by a backscattering microphysical
model, aimed at representing ten different hydrometeor classes
in water, ice, and mixed phase. The expected error budget is
evaluated by means of contingency tables on the basis of C-band
radar noisy and attenuated synthetic data. Its accuracy is better
than that obtained from a previously developed fuzzy logic C-band
classification algorithm. As a second step of the overall retrieval
algorithm, a multivariate regression is adopted to derive water
content statistical estimators, exploiting simulated polarimetric
radar data for each hydrometeor class. The BRAHCC methodology
is then applied to a convective hail event, observed by two
C-band dual-polarized radars in a network configuration. The
hydrometeor classification along the line of sight, connecting the
two C-band radars, is performed using the BRAHCC applied to
path-attenuation-corrected data. Qualitative results are consistent
with those derived from the fuzzy logic algorithm. Hydrometeor
water content temporal evolution is tracked along the radar line
of sight. Hail vertical occurrence is derived and compared with an
empirical hail detection index applied along the radar connection
line during the whole event
Supervised fuzzy-logic classification of hydrometeors using C-band dual-polarized radars
No full textA model-based fuzzy-logic method for hydrometeor
classification using C-band polarimetric radar data is presented
and discussed. Membership functions of the fuzzy-logic algorithm
are designed for best fitting simulated radar signatures at
C-band. Such signatures are derived for ten supervised hydrometeor
classes by means of a fully polarimetric radar scattering
model. The Fuzzy-logic Radar Algorithm for Hydrometeor Classification
at C-band (FRAHCC) is designed to use a relatively
small set of polarimetric observables, i.e., copolar reflectivity and
differential reflectivity, but a version of the algorithm based on
the use of specific differential phase is also numerically tested and
documented. The classification methodology is applied to volume
data coming from a C-band two-radar network that is located in
north Italy within the Po valley. Numerical and experimental results
clearly show the improvements of hydrometeor classification,
which were obtained by using FRAHCC with respect to the direct
use of fuzzy-logic-based algorithms that are specifically tuned
for S-band radar data. Moreover, the availability of two C-band
rainfall observations of the same event allowed us to implement
a path-integrated attenuation correction procedure, based on
either a composite radar field approach or a network-constrained
variational algorithm. The impact of these correction procedures
on hydrometeor classification is qualitatively discussed within the
considered case study
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
Microphysical Evolution of a Convective Event retrieved from Two Operational Polarimetric C-Band Radars
No full textThe analysis of the evolution of convective clouds and their
correspondent microphysics vertical distribution will
contribute to a better understanding of convective processes
and will improve the representation of cloud evolution and
latent heat formation for assimilation in NWP models.
The use of polarimetric radar measurements allows us to
identify the prevailing hydrometeor type and their spatial
distribution within a meteorological event.
The study is carried out using two polarimetric Cband
radars located 90 km apart in the Po Valley of Northern
Italy, the S. Pietro Capofiume and the Gattatico radars, both
managed by ARPA EmiliaRomagna.
The radar observations are collected during the transition of
a severe evolving storm occurred on the afternoon of 20 may
2003, moving across the region explored by the two radars,
and the microphysical properties are obtained by using an
hydrometeor classification scheme developed at the National
Severe Storms Laboratory, and recently extended from Sband
to Cband radar data.
The aim of the work is the reconstruction of the 3D
storm structure vertical evolution to understand how the
microphysical properties change during the different stages
of the storm formation and development (from the early to
the mature and then dissipative stage of the cloud system).
Further “storm representative” vertical hydrometeor profiles
will be discussed in order to elucidate the microphysical
processes occurring during the storm’s lifetime and their
consequence on the ground rainfall field estimation.
A next step of this kind of analysis will be the comparison
with NWP simulated profiles, to check if they are able to
reproduce the reference hydrometeor vertical profiles seen
by the radars
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
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