5,321 research outputs found
The radial evolution of solar wind speeds
The WSA-ENLIL model predicts significant evolution of the solar wind speed. Along a flux tube the solar wind speed at 1.0 AU and beyond is found to be significantly altered from the solar wind speed in the outer corona at 0.1 AU, with most of the change occurring within a few tenths of an AU from the Sun. The evolution of the solar wind speed is most pronounced during solar minimum for solar wind with observed speeds at 1.0 AU between 400 and 500 km/s, while the fastest and slowest solar wind experiences little acceleration or deceleration. Solar wind ionic charge state observations made near 1.0 AU during solar minimum are found to be consistent with a large fraction of the intermediate-speed solar wind having been accelerated or decelerated from slower or faster speeds. This paper sets the groundwork for understanding the evolution of wind speed with distance, which is critical for interpreting the solar wind composition observations near Earth and throughout the inner heliosphere. We show from composition observations that the intermediate-speed solar wind (400-500 km/s) represents a mix of what was originally fast and slow solar wind, which implies a more bimodal solar wind in the corona than observed at 1.0 AU
Sublinear Estimation of Weighted Matchings in Dynamic Data Streams
This paper presents an algorithm for estimating the weight of a maximum
weighted matching by augmenting any estimation routine for the size of an
unweighted matching. The algorithm is implementable in any streaming model
including dynamic graph streams. We also give the first constant estimation for
the maximum matching size in a dynamic graph stream for planar graphs (or any
graph with bounded arboricity) using space which also
extends to weighted matching. Using previous results by Kapralov, Khanna, and
Sudan (2014) we obtain a approximation for general graphs
using space in random order streams, respectively. In
addition, we give a space lower bound of for any
randomized algorithm estimating the size of a maximum matching up to a
factor for adversarial streams
The quality of fibre grown by Australian alpacas : part 2 : survey of the quality of fibre grown by Australian alpacas
ICFHR 2018 Competition on recognition of historical Arabic scientific manuscripts - RASM2018
This paper presents an objective comparative evaluation of page analysis and recognition methods for historical scientific manuscripts with text in Arabic language and script. It describes the competition (modus operandi, dataset and evaluation methodology) held in the context of ICFHR2018, presenting the results of the evaluation of six methods – three submitted and three baseline systems. The challenges for the participants included page segmentation, text line detection, and optical character recognition (OCR). Different evaluation metrics were used to gain an insight into the algorithms, including new character accuracy metrics to better reflect the difficult circumstances presented by the documents. The results indicate that, despite the challenging nature of the material, useful digitisation outputs can be produced
Temperature dependence of the ohmic conductivity and activation energy of Pb1+y(Zr0.3Ti0.7)O3 thin films
The ohmic conductivity of the sol-gel derived Pb1+y(Zr0.3Ti0.7)O3 thin films
(with the excess lead y=0.0 to 0.4) are investigated using low frequency small
signal alternate current (AC) and direct current (DC) methods. Its temperature
dependence shows two activation energies of 0.26 and 0.12 eV depending on
temperature range and excess Pb levels. The former is associated with Pb3+
acceptor centers, while the latter could be due to a different defect level yet
to be identified.Comment: 13 pages, 3 figures, PostScript. Submitted to Applied Physics Letter
The development of reading tests for use in a regularly spelled language.
Data are presented on the development of tests of reading skill in rural Tanzanian primary school pupils. Instruction in these schools is in Kiswahili, a regularly spelt language. Using a translation of a standard reading test, children could read aloud all words once they had learnt sound-letter correspondences, regardless of comprehension. In addition, children can appear to pass traditional comprehension tasks by decoding only some of the words. Three graded tests were developed which allow testing of children who either have only some letter knowledge, can read single words, or are proficient readers. The tests require children to both decode and understand the reading material in order to achieve high scores. The tests correlated well with scores on other educational achievement tests, and showed age and school grade differences. It is suggested that these tests are useful measures of reading development in a regularly spelt language. Adaptation to English and validation against standardised instruments is planned
Measuring Active-Sterile Neutrino Oscillations with a Stopped Pion Neutrino Source
The question of the existence of light sterile neutrinos is of great interest
in many areas of particle physics, astrophysics, and cosmology. Furthermore,
should the MiniBooNE experiment at Fermilab confirm the LSND oscillation
signal, then new measurements are required to identify the mechanism
responsible for these oscillations. Possibilities include sterile neutrinos, CP
or CPT violation, variable mass neutrinos, Lorentz violation, and extra
dimensions. In this paper, we consider an experiment at a stopped pion neutrino
source to determine if active-sterile neutrino oscillations with delta-m
greater than 0.1 eV2 can account for the signal. By exploiting stopped pi+
decay to produce a monoenergetic nu_mu source, and measuring the rate of the
neutral current reaction nu_x + 12C -> nu_x +12C* as a function of distance
from the source, we show that a convincing test for active-sterile neutrino
oscillations can be performed.Comment: 10 pages, 9 figure
- …