1,721,015 research outputs found
Attitude profiles for ground-path pointing and alignment of radar footprints: Application to the INCUS mission
Full text linkThis work presents the derivation of pointing profiles for a satellite mission requiring continuous observations of a ground path. The study is directly applied to the INvestigation of Convective Updrafts (INCUS) mission, a three-satellite constellation designed to investigate tropical convective storms through time-differenced radar observations. A sequence of pitch, roll, and yaw rotations was investigated to align each spacecraft with the reference ground path, while accounting for mission-specific requirements and constraints. A pointing strategy with fixed pitch and time-varying roll was examined to achieve ground-path pointing. A subsequent yaw rotation was then studied to ensure correct cross-track alignment of the radar footprints. A numerical search-strategy was performed to derive the time difference between observations and the pointing profiles, while an additional analytical formulation was also developed to address the footprint alignment problem. The effects of in-track spacecraft knowledge position errors on both the pointing profiles and cross-track alignment of the footprints were also investigated. Moreover, the effects of variations in orbital inclination and altitude on the pointing profiles have been addresse
High-Resolution Simulations of the 2010 Pakistan Flood Event: Sensitivity to Parameterizations and Initialization Time
Full text linkEstimating the risk of flood-generating precipitation events in
high-mountain regions with complex orography is a difficult but crucial
task. Quantitative precipitation forecasts (QPFs) at fine resolution are
an essential ingredient to address this issue. Along these lines, the
ability of the Weather Research and Forecasting (WRF) Model, operated at
3.5-km grid spacing, to reproduce the extreme meteorological event that
led to the 2010 Pakistan flood and produced heavy monsoonal rain in the
Indus basin is explored. The model results are compared with Tropical
Rainfall Measuring Mission (TRMM) rainfall estimates, the available
ground measurements, and radar observations from the CloudSat mission.
In particular, the sensitivity of the WRF simulations to the use of
different convective closures (explicit and Kain-Fritsch) and
microphysical parameterizations (WRF single-moment 6-class microphysics
scheme and Thompson) is analyzed. The impact of using different initial
conditions, associated with a different initialization day, is also
examined. The use of the new-generation Distributed Simulation and
Stimulation System NASA Earth Observing System Simulators Suite radar
simulator allows a more accurate and extensive representation of the
mesoscale processes and of the interaction with the complex orography.
The results reported here indicate that the quality of the large-scale
initial conditions is a prominent factor affecting the possibility of
retrieving a realistic representation of this event when using a
nonhydrostatic regional model
EarthCARE's cloud profiling radar antenna pointing correction using surface Doppler measurements
Full text linkThe Earth Cloud Aerosol and Radiation Explorer (EarthCARE) mission, a joint effort between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), aims to advance our understanding of aerosols, clouds, precipitation, and radiation using a comprehensive payload of active and passive sensors. A key component of the payload is the 94 GHz cloud profiling radar (CPR), which provides the first-ever Doppler velocity measurements collected from space. Accurate knowledge of the CPR antenna pointing is essential for ensuring high-quality CPR Doppler velocity measurements. This study focuses on the geolocation assessment and antenna mispointing corrections during EarthCARE's commissioning phase and beyond, using Earth's surface Doppler velocity measurements collected over the first 9 months of the mission. While the instrument footprint is proven to be properly geolocated within about 100 m, surface Doppler velocity observations reveal mispointing trends influenced by solar illumination cycles and thermoelastic distortions on the antenna. Correcting these effects significantly reduces biases, ensuring better Doppler velocity measurements, essential for understanding cloud microphysics and dynamics. The results, validated through the analysis of Doppler velocities in ice clouds, underline the critical role of pointing corrections for the success of the EarthCARE mission
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
- …
