1,454 research outputs found
Kepler Transit Depths Contaminated by a Phantom Star
We present ground-based observations from the Discovery Channel Telescope
(DCT) of three transits of Kepler-445c---a supposed super-Earth exoplanet with
properties resembling GJ 1214b---and demonstrate that the transit depth is
approximately 50 percent shallower than the depth previously inferred from
Kepler Spacecraft data. The resulting decrease in planetary radius
significantly alters the interpretation of the exoplanet's bulk composition.
Despite the faintness of the M4 dwarf host star, our ground-based photometry
clearly recovers each transit and achieves repeatable 1-sigma precision of
approximately 0.2 percent (2 millimags). The transit parameters estimated from
the DCT data are discrepant with those inferred from the Kepler data to at
least 17-sigma confidence. This inconsistency is due to a subtle miscalculation
of the stellar crowding metric during the Kepler pre-search data conditioning
(PDC). The crowding metric, or CROWDSAP, is contaminated by a non-existent
"phantom star" originating in the USNO-B1 catalog and inherited by the Kepler
Input Catalog (KIC). Phantom stars in the KIC are likely rare, but they have
the potential to affect statistical studies of Kepler targets that use the PDC
transit depths for a large number of exoplanets where individual follow-up
observation of each is not possible. The miscalculation of Kepler-445c's
transit depth emphasizes the importance of stellar crowding in the Kepler data,
and provides a cautionary tale for the analysis of data from the Transiting
Exoplanet Survey Satellite (TESS), which will have even larger pixels than
Kepler.Comment: 11 pages, 10 figures, 5 tables. Accepted for publication in AJ.
Transit light curves will be available from AJ as Db
Control of a bidirectional single-phase grid interface for electric vehicles
The number of electric vehicles is expected to increase exponentially
in the next decade. This represents a huge potential for grid support,
such as energy storage in their batteries, with advantages for grid
operators and for customers. For this purpose, flexible power interfaces
are required. This paper presents a simulation of a bidirectional singlephase
power interface between an electric vehicle battery and the grid.
The proposed system is fully simulated and counts with features such as
vehicle-to-grid, vehicle-to-home and grid-to-vehicle. All power flow and
the controllers for these modes of operation are described in detail. The
simulation was developed in a Software-in-the-Loop scheme to facilitate
a future physical implementation with a Hardware-in-the-Loop platform.
The proposed system was extensively tested via simulation, the results
proving the system is stable, able to change operation modes smoothly
and definition of the exchanged active and reactive powers.info:eu-repo/semantics/publishedVersio
Image Analysis of Morphological Changes in Wiener Batters During Chopping and Cooking
Histological changes in wiener batters during chopping and cooking have often been illustrated with representative fields . The practice of selecting representative fields ignores variation and leads to word descriptions that cannot be correlated with numerical scores for functional or sensory tests . If wieners are regarded as a multi-component system, objectivity can be achieved by selecting many fields for each sample according to a rigid sampling plan. Image analysis quantified parameters of both the fat and protein components . The reduction in size of fat globules during chopping of a commercial formulation, for example, was a function of area and aggregate perimeter of several hundred globules compiled by a computer . There was no relationship between wiener firmness and any feature of the microstructure ; but even at a low magnification of 30x , several statistically different factors were exposed during this survey which require further study
FFAD: A Novel Metric for Assessing Generated Time Series Data Utilizing Fourier Transform and Auto-encoder
The success of deep learning-based generative models in producing realistic
images, videos, and audios has led to a crucial consideration: how to
effectively assess the quality of synthetic samples. While the Fr\'{e}chet
Inception Distance (FID) serves as the standard metric for evaluating
generative models in image synthesis, a comparable metric for time series data
is notably absent. This gap in assessment capabilities stems from the absence
of a widely accepted feature vector extractor pre-trained on benchmark time
series datasets. In addressing these challenges related to assessing the
quality of time series, particularly in the context of Fr\'echet Distance, this
work proposes a novel solution leveraging the Fourier transform and
Auto-encoder, termed the Fr\'{e}chet Fourier-transform Auto-encoder Distance
(FFAD). Through our experimental results, we showcase the potential of FFAD for
effectively distinguishing samples from different classes. This novel metric
emerges as a fundamental tool for the evaluation of generative time series
data, contributing to the ongoing efforts of enhancing assessment methodologies
in the realm of deep learning-based generative models.Comment: 13 pages, 6 figures, accepted by ICTIS-2024 on March 8th, 202
Assessment of Physical, Technical, and Tactical Analysis in the Australian Football League: A Systematic Review.
BACKGROUND: Elite Australian Football (AF) match-play requires proficiency in physical, technical, and tactical elements. However, when analysing player movement practitioners commonly exclude technical and tactical considerations, failing to recognise the multifactorial nature of AF match-play and providing little context into the movement requirements of the players. OBJECTIVES: This systematic review aimed to identify the physical, technical, and tactical requirements of the Australian Football League (AFL) and to highlight the importance of integrating data from multiple sources when analysing player output. METHODS: A systematic search of electronic databases (CINAHL, PubMed, Scopus, SPORTDiscus, and Web of Science) was conducted from January 2009 to June 2022. Keywords relating to physical, technical, and tactical match requirements were used. RESULTS: Forty-eight studies met the inclusion criteria. In isolation, physical requirements were the most analysed construct within the AFL (n = 17), followed by technical (n = 9) and then tactical (n = 6). Thirteen studies integrated physical and technical elements, one study integrated technical and tactical elements, one study integrated physical and tactical elements, and one study integrated all three elements. Movement analysis centred around average 'whole' match requirements, whereas technical and tactical match analyses focused on key performance indicators of match performance. CONCLUSION: While the physical requirements of the AFL have been well documented, there is little understanding of how player technical output and various team tactics influence player movement requirements. Knowledge of how the elements of AF match-play interact with one another could enhance our understanding of match performance and provide a greater resource for training prescription
Dietary intake of professional Australian football athletes surrounding body composition assessment
© 2018 The Author(s). Background: Sports Dietitians aim to assist in improving performance by developing nutrition knowledge (NK), enhancing dietary intake and optimising body composition of athletes. In a high-pressure environment, it is important to identify factors that may compromise an athlete's nutrition status. Body composition assessments are regularly undertaken in sport to provide feedback on training adaptions; however, no research has explored the impact of these assessments on the dietary intake of professional athletes. Methods: This cross-sectional study assessed dietary intake (7-day food diary), nutrition knowledge (Nutrition for Sport Knowledge Questionnaire) and body composition (Dual-energy X-ray absorptiometry) of 46 professional male Australian football (AFL) athletes during a 2017 pre-season training week (7days) where body composition assessments were undertaken. Dietary intake was assessed against International Olympic Committee recommendations for professional athletes. Results: Overall, no athlete met dietary their recommended energy intake (15±1.1 vs. 9.1±1.8MJ, respectively) or carbohydrate recommendations (6-10 vs. 2.4±0.9g.kg-1.day-1). Only 54% met protein recommendations. Secondary analyses demonstrated significant associations between education status and energy intake (P<0.04) and vegetable intake (P<0.03), with higher levels of education being associated with higher intakes. A moderately positive association was observed between NK scores and meeting estimated energy requirements (r=0.33, P=0.03). NK scores were also positively associated with protein (r=0.35, P=0.02), fibre (r=0.51, P=0.001) and calcium intakes (r=0.43, P=0.004). Conclusions: This research identified that the dietary intake of professional AFL athletes during a pre-season training week where body composition assessments were undertaken did not meet current recommendations. Several factors may influence the dietary intake of AFL athletes, including lower education levels, poor NK and dietary intake restriction surrounding body composition assessment. Athletes may require support to continue with performance-based nutrition plans in periods surrounding body composition assessment
Hubble Space Telescope Near-IR Transmission Spectroscopy of the Super-Earth HD 97658b
Recent results from the Kepler mission indicate that super-Earths (planets
with masses between 1-10 times that of the Earth) are the most common kind of
planet around nearby Sun-like stars. These planets have no direct solar system
analogue, and are currently one of the least well-understood classes of
extrasolar planets. Many super-Earths have average densities that are
consistent with a broad range of bulk compositions, including both
water-dominated worlds and rocky planets covered by a thick hydrogen and helium
atmosphere. Measurements of the transmission spectra of these planets offer the
opportunity to resolve this degeneracy by directly constraining the scale
heights and corresponding mean molecular weights of their atmospheres. We
present Hubble Space Telescope near-infrared spectroscopy of two transits of
the newly discovered transiting super-Earth HD 97658b. We use the Wide Field
Camera 3's scanning mode to measure the wavelength-dependent transit depth in
thirty individual bandpasses. Our averaged differential transmission spectrum
has a median 1 sigma uncertainty of 23 ppm in individual bins, making this the
most precise observation of an exoplanetary transmission spectrum obtained with
WFC3 to date. Our data are inconsistent with a cloud-free solar metallicity
atmosphere at the 10 sigma level. They are consistent at the 0.4 sigma level
with a flat line model, as well as effectively flat models corresponding to a
metal-rich atmosphere or a solar metallicity atmosphere with a cloud or haze
layer located at pressures of 10 mbar or higher.Comment: ApJ in press; revised version includes an updated orbital ephemeris
for the plane
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