9,287 research outputs found
A simulation model of time-dependent plasma-spacecraft interactions
A plasma simulation code is presented that models the time-dependent plasma properties in the vicinity of a spherical, charged spacecraft. After showing agreement with analytic, steady-state theories and ATS-6 satellite data, the following three problems are treated: (1) transient pulses from photoemission at various emission temperatures and ambient plasma conditions, (2) spacecharge limited emission, and (3) simulated plasma oscillations in the long wavelength limit
STANCY: Stance Classification Based on Consistency Cues
Controversial claims are abundant in online media and discussion forums. A better understanding of such claims requires analyzing them from different perspectives. Stance classification is a necessary step for inferring these perspectives in terms of supporting or opposing the claim. In this work, we present a neural network model for stance classification leveraging BERT representations and augmenting them with a novel consistency constraint. Experiments on the Perspectrum dataset, consisting of claims and users' perspectives from various debate websites, demonstrate the effectiveness of our approach over state-of-the-art baselines
Fast Searching in Packed Strings
Given strings and the (exact) string matching problem is to find all
positions of substrings in matching . The classical Knuth-Morris-Pratt
algorithm [SIAM J. Comput., 1977] solves the string matching problem in linear
time which is optimal if we can only read one character at the time. However,
most strings are stored in a computer in a packed representation with several
characters in a single word, giving us the opportunity to read multiple
characters simultaneously. In this paper we study the worst-case complexity of
string matching on strings given in packed representation. Let be
the lengths and , respectively, and let denote the size of the
alphabet. On a standard unit-cost word-RAM with logarithmic word size we
present an algorithm using time O\left(\frac{n}{\log_\sigma n} + m +
\occ\right). Here \occ is the number of occurrences of in . For this improves the bound of the Knuth-Morris-Pratt algorithm.
Furthermore, if our algorithm is optimal since any
algorithm must spend at least \Omega(\frac{(n+m)\log
\sigma}{\log n} + \occ) = \Omega(\frac{n}{\log_\sigma n} + \occ) time to
read the input and report all occurrences. The result is obtained by a novel
automaton construction based on the Knuth-Morris-Pratt algorithm combined with
a new compact representation of subautomata allowing an optimal
tabulation-based simulation.Comment: To appear in Journal of Discrete Algorithms. Special Issue on CPM
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Werdingite from the Urungwe District, Zimbabwe
Electron and ion microprobe data on two samples of welshite from the type locality of Langban, Sweden, gave analytical totals of 99.38-99.57 wt.% and BeO contents of 4.82-5.11 wt.%, corresponding to 1.692-1.773 Be/20 O. Mossbauer and optical spectra of o
Evaluation of Interactions Between Oilfield Chemicals and Reservoir Rocks
The authors gratefully acknowledge Petroleum Technology Development Fund (PTDF) Nigeria for funding the PhD work from which the materials and results presented in this paper originated. The authors are also grateful to the Laboratory technicians in the School of Pharmacy and Life science and Gray School of arts, Robert Gordon University; and School of Engineering, University of Aberdeen for their technical support.Peer reviewedPublisher PD
Correlations between structure and dynamics in complex networks
Previous efforts in complex networks research focused mainly on the
topological features of such networks, but now also encompass the dynamics. In
this Letter we discuss the relationship between structure and dynamics, with an
emphasis on identifying whether a topological hub, i.e. a node with high degree
or strength, is also a dynamical hub, i.e. a node with high activity. We employ
random walk dynamics and establish the necessary conditions for a network to be
topologically and dynamically fully correlated, with topological hubs that are
also highly active. Zipf's law is then shown to be a reflection of the match
between structure and dynamics in a fully correlated network, as well as a
consequence of the rich-get-richer evolution inherent in scale-free networks.
We also examine a number of real networks for correlations between topology and
dynamics and find that many of them are not fully correlated.Comment: 16 pages, 7 figures, 1 tabl
Role of nucleation sites on the formation of nanoporous Ge
The role of nucleation sites on the formation of nanoporousGe was investigated. Three Gefilms with different spherical or columnar pore morphologies to act as inherent nucleation sites were sputtered on (001) Ge. Samples were implanted 90° from incidence at 300 keV with fluences ranging from 3.0 × 10¹⁵ to 3.0 × 10¹⁶Ge⁺/cm². Electron microscopy investigations revealed varying thresholds for nanoporousGe formation and exhibited a stark difference in the evolution of the Ge layers based on the microstructure of the initial film. The results suggest that the presence of inherent nucleation sites significantly alters the onset and evolution of nanoporousGe.The authors acknowledge the Intel Corporation for funding
this work
Discovery of hidden pedigree errors combining genomic information with the Genomic Relationship Matrix in Texel sheep
Including genotypic information in genetic evaluations increases the accuracy of sheep breeding values
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